The main variables for this experiment are the concentration levels  of a MgCl2 solution for test phase 1, charging time  in EDT for test phase 2, and configuration of pre- and post-treatment processes in EDT for test phase 3. The rehabilitation performance of EDT is evaluated by analyzing the AC impedance properties of the steel-and-concrete interface using electrochemical impedance spectroscopy (EIS) for the test phases 1 and 2, and microscopic alternation in concrete cracks using optical microscopic image and SEM/EDX. It is demonstrated that EDT is an effective method for preventing and mitigating corrosion-induced deterioration in the initiation and rust propagation periods of corrosion and for repairing (closing and filling) a corrosion-induced surface-breaking crack in the acceleration phase of corrosion. Corrosion-resistant performance of concrete increases as the concentration levels of a MgCl2 solution in an electrolyte increases and as the charging time in EDT increases. In addition, a post-treatment process (applying a NaOH solution) after the electrochemical deposition process significantly improves crack-repairing performance of EDT.The primary purposes of this study are to investigate the feasibility of electrochemical deposition treatment (EDT) as a comprehensive rehabilitation method for corrosion-induced deterioration in reinforced concrete with various severity levels, and to propose a guideline for the determination of critical factors to advance EDT. This study includes three experimental phases, each of which simulates the initiation (de-passivation), propagation (high corrosion activity), and acceleration (formation of a surface-breaking crack) periods of corrosion-induced deterioration. After completion of a series of accelerated corrosion tests, damaged concrete samples with different severity levels are rehabilitated by a series of EDT processes using a MgCl The passive film becomes unstable when the pH of the concrete lowers below a certain level or the chloride ion concentration in concrete exceeds a threshold level [Corrosion is a process through which metals in manufactured states return to their natural oxidation states. Corrosion of steel in reinforced concrete is generally described by multiple phases, including initiation, rust propagation, and acceleration as illustrated in ld level . The faild level . The enhCorrosion of infrastructures causes high costs to the society of many industrialized countries in the world. Estimated annual direct corrosion cost is about US $240 billion in the US. Approximately 20% of the direct costs were attributed to corrosion of reinforced concrete  . More thThere are various practical methods for rehabilitation of old and/or damaged reinforced concrete structures that suffer from different phases of corrosion-induced deterioration see b. BeforeElectrochemical deposition treatment (EDT) is a kind of cathodic protection method. After being proposed in Japan first in early 1990s ,13, ther2 solution for test phase 1, charging time of EDT  for test phase 2, and configuration of pre- and post-treatment processes in EDT for test phase 3. As will be discussed, the experimental results in this study would provide a fundamental basis to better understand and further improve the capability of the EDT method as a comprehensive rehabilitation method of corrosion-induced deterioration with various severity levels. In this study, a series of experimental studies was performed in the laboratory to investigate the effectiveness of EDT for rehabilitation of deteriorated reinforced concrete with three different corrosion levels: initiation, rust-propagation, and acceleration phases of steel corrosion. Each test phase was composed of multiple experimental processes that include preparation of test specimens, accelerated corrosion tests, electrochemical deposition treatment (EDT), and condition assessment of solid, deteriorated, and rehabilitated reinforced concrete specimens. The main variables of this study include the concentration levels  of a MgCl2. The cuboidal concrete samples were made of Type I Portland cement and ISO standard sand with a water-to-cement ratio of 0.6 and a cement-to-sand ratio of 0.5. A total of four samples were fabricated under the same shape and rebars. The rebar spacing was kept constant at 10 mm in all samples. The clear cover of rebars was kept constant at 10 mm. Test phase 1 used four concrete prism samples (100 mm length × 120 mm width × 25 mm thickness) shown in 2. In contrast, the test phases 2 and 3 used concrete cylinder samples (25 mm diameter by 70 mm length) shown in For test phase 1, the four concrete prism samples . For test setup 3, the accelerated corrosion test setup and procedure were the same as those from test setup 2, except for applying an enhanced current density of 1 mA/cm2 for 48 h to generate corrosion-induced surface-breaking cracks in concrete. For test phase 2, corrosion of rebars in the three of the four concrete cylinders . A potentiostat was used to pass a constant electric current, −2 μAcm−2, between the embedded rebar (cathodic electrode) in concrete and a titanium anode (anodic electrode) in a MgCl2 solution. The stabilized potential levels measured in the EDT processes was in a range of −0.8 V to −1.0 V (vs. Ag/AgCl), which prevented the formation of hydrogen gas around rebars in concrete (cathode) during EDT [2 solution for test phase 1, the duration of polarization  during EDT for test phase 2, and the configuration of pre- and post-treatment processes in EDT for test phase 3.ring EDT ,33. TablPR, PR is polarization resistance of reinforced concrete samples) to exceed a criterion for the initiation of corrosion  (4 × 10−6 Ω−1cm−2) [2 solutions  were used to investigate the effect of concentration level of MgCl2 in an electrolyte on the corrosion prevention capability of the EDT. After completion of EDT, all concrete samples were taken out of the water tank and oven-dried under 60 °C. The dried samples were exposed to the wetting-and-drying cycles (from 14th to 45th cycles) again to investigate the corrosion-resistant properties of the concrete prisms after EDT. In test phase 1, EDT was applied to the four concrete prisms after completion of the 13th cycle of the wetting-and-drying process see a. The tiΩ−1cm−2) . Four di2 solution. A constant current with a density of −2 µAcm−2 was continuously applied for 0, 2, and 7 days to investigate the effect of polarization time on the rehabilitation performance of EDT. In test phase 2, electrochemical deposition was applied to deteriorated concrete cylinders with high corrosion activity see b. Three 2 solution with a constant current density of −2 µAcm−2 for 240 h (10 days). After that, treated concrete cylinders were submerged again in a 2M NaOH solution (pH 13) for 10 h as a post-treatment. Test phase 3 included four different scenarios of EDT processes to investigate the effect of pre- and post-treatment on the crack-filling capability of the multi-stage EDT.In addition, EDT was used to repair a surface-breaking crack in the four concrete cylinders in test phase 3. In this study, several extra processes were added before and after the main EDT process to improve the crack-filling capability of EDT. The multi-stage EDT is composed of four processes, including pre-treatment, electrical deposition, post-treatment, and baking. In the pre-treatment stage, the cracked concrete cylinders were submerged in NaOH solution (pH 13) for 10 h. In the main EDT stage, concrete samples were immersed in a 2M MgClElectrochemical impedance spectroscopy (EIS) was used to investigate the effectiveness of EDT processes on the rehabilitation of deteriorated concrete samples in the test phases 1 and 2. sR, fR, and cR) are connected in series, where sR represents the electrical resistance associated with the electrolyte solution in concrete pores; fR refers to the resistance of interfacial film on a steel rebar caused by rust propagation and/or precipitation of cement hydration and electrochemical deposition [cR corresponds to the resistance of the charge transfer involved in the corrosion mechanism. Impedance, (CPEZ), caused by capacitance actions in the interface of the layers, was modelled by the constant phase element (CPE), which was connected in parallel to a resistance component in each layer.CPE,iC is the electric capacitance, αi is a constant for calibrating the non-uniform properties of steel and concrete interfaces, the subscript i represents an interface where the capacitance action occurs , j is complex number and w is the angular frequency . Warburg impedance element (W) was used to model the impedance due to diffusion of corrosion product (WZ), which is composed of a resistance component WR, a capacitance component τ and a calibration factor αW.In this study, a reinforced concrete sample was modelled by an equivalent EIS circuit shown in position ; Rc corrZ) of the EIS circuit in this study is represented as follows,Finally, the total impedance , highZ, and low frequency impedance, lowZ, provided that cR value is large enough compared to fR and WZ. Consequently, the approximate polarization resistance In this study, the polarization resistance, It was demonstrated that this simplified approach is effective for rapid monitoring of the corrosion rate by EIS ,39.2 concentrations  are shown in ectively . Figure −6 Ω−1cm−2) [−6 Ω−1cm−2 in the dry condition and over 1 × 10−5 Ω−1cm−2 (about 250% of the de-passivation criteria) in the wet condition (−6 Ω−1cm−2) even after being continuously exposed to a harsh environment during the 14th to 45th cycles. The use of 0.5M MgCl2 solution was effective for prevention of steel corrosion by suppressing the corrosion rate under the de-passivation criterion (4.0 × 10−6 Ω−1cm−2). Specifically, cR and sR values in the steel and concrete interface. The recovery of corrosion protection performance by EDT is mainly attributed to the presence of precipitates on the steel surface. The precipitates formed by EDT impede charge transfer rate for the steel corrosion reaction (Fe → Fe2+ + 2e−) and reduction rate of dissolved oxygen (O2 + 2H2O + 4e− → 4OH−) in the rust layer. Furthermore, the use of a higher concentration level of MgCl2 solution (1M and 3M) further decreased the corrosion rate of reinforced steel in concrete compared to the use of 0.3M MgCl2. 2 solutions (TP1-3 and TP1-4) decreased to approximately 50% of the values before EDT process. However, the use of 3M MgCl2 solution does not show a clear benefit compared to 1M MgCl2 solution. The concrete samples in the experimental phase 1 were under low corrosion activity. Therefore, the EDT process can be governed by the amount of hydroxide ion (OH−) caused by corrosion of steel rather than the amount of magnesium ion (Mg2+) in concrete pore solution. In this study, it can be inferred that 1M MgCl2 is sufficient to recover corrosion protection capability of concrete under relatively low corrosion rate.In the 1st~13th cycles of the immersion and drying cycles, the instantaneous corrosion rate in the four concrete prism samples was lower than the criterion for the de-passivation of reinforcing steel (4.0 × 10Ω−1cm−2) . After tondition a. Howeve2 [2+ ions due to EDT. The modulus of impedance in a high frequency range of 10 kHz to 100 Hz (see sR). In contrast, the modulus of impedance values in a low frequency range (0.01 Hz to 0.001 Hz) represents the impedance of charge transfer associated with corrosion reaction . Bode plots obtained from EIS are informative on the variation of interfacial conditions of steel and concrete in the concrete samples during EDT. The phase shift curves in 2 ,37. It w0 Hz see a, where cR (on the left side in the y axis) and solution resistance sR (on the left side in the y axis). The variation of the corrosion rate is shown in cR values summarized in cR value of the concrete sample (TP2-2) was only 19.5 kΩcm2, which is significantly lower than the value of solid concrete sample (TP2-1). Accordingly, the corrosion rate of the TP2-2 sample was 5.12 × 10−5 Ω−1cm−2, indicating the deteriorated concrete before EDT is under high corrosion activity [cR value increases to 38.5 kΩcm2 and 165.1 kΩcm2 as the polarization time of EDT increases to 2 days and 7 days, respectively. Consequently, the corrosion rate of concrete sample decreases as the duration of EDT increases to 0, 2, and 7 days. The speed of corrosion rate becomes slower as the duration of EDT increases. Furthermore, it appears to converge into a certain value greater than a criterion for the initiation of corrosion (4 × 10−6 Ω−1cm−2). It can be inferred that there is a limitation in the status of deteriorated concrete that can be recovered by EDT processes, which is dependent on corrosion activity levels. activity . After E2) filled the mouth of the surface-breaking crack and the voids in concrete. Similar results were observed on the three other concrete samples  in this study. This section describes the efficiency of EDT on repairing (closing and filling) a surface-breaking crack in concrete samples. sp is the solubility product of Mg(OH)2 (=5.61 × 10−12 at 25 °C) [One interesting finding in this study is that the post-treatment with a NaOH solution significantly reduces the time for repairing a surface-breaking crack using EDT process. The effectiveness of the post-treatment process with high alkalinity solution can be explained by higher solubility of magnesium ions in lower pH as follows,t 25 °C) . By taki2+ ions decreases as pH increases, which indicates the amount of precipitation of Mg2+ decreases as pH decreases. In general, the conventional EDT mechanism in the literature follows path 1 in Consequently, the concentration of Mg− ions toward the external anodic electrode during the EDT processes, and (3) pH drop in an external electrolyte due to the migration of OH−. It seems that only two weeks was not sufficient for conventional EDT method to work. In this study, it was found that the post treatment process with a NaOH solution is effective for facilitating the precipitation of Mg2+ ions through the 2nd path in However, a conventional EDT process used in the experimental phases 1 and 2 was not effective for repairing (closing or filling) a surface-breaking crack in concrete samples in this study. It can be attributed to several reasons: (1) pH drop around cracks in concrete after formation of a surface-breaking crack during the accelerated corrosion test, (2) migration of (OH)(1)2 solution in an electrolyte by applying a constant current −2 µAcm−2 for 24 h, impedance of the steel-and-concrete interface  increased to prevent de-passivation of steel, even when the concrete specimen was exposed to harsh corrosive environment. The corrosion protection performance is attributed to precipitates on the steel surface that impeded charge transfer rate for the steel corrosion reaction (Fe → Fe2+ + 2e−) and reduction rate of dissolved oxygen (O2+2H2O +4e− → 4OH−) in the rust layer. The use of higher concentration of MgCl2 solutions  was effective for further decreasing the corrosion rate of steel in concrete compared to the use of 0.3M MgCl2 solution.It was observed from test phase 1 that EDT was an effective method to improve corrosion-resistant properties of the concrete specimens in the initiation phase of corrosion. After EDT using a 0.3 M MgCl(2)Furthermore, EDT successfully suppressed the corrosion rate of concrete specimens under high corrosion activity. It was observed that the corrosion rate decreased as the polarization duration in EDT increased. The speed of corrosion rate decrement appears to be slower as the duration of EDT increases. However, it is not clear based on the limited data in this study how much the deteriorated reinforced concrete can be recovered by EDT. More systematic studies are still needed to investigate the corrosion recovery capability of EDT for concrete with various degree of corrosion levels.(3)From the experimental results of test phase 3, EDT was effective for repairing (closing and filling) a corrosion-induced surface-breaking crack in concrete. From the visual inspection based on optical microscopic and SEM images, precipitation of magnesium ions formed at the mouth of a surface-breaking crack and continued to the crack interface and rust products, eventually reaching the crack tip rooted on the steel-and-concrete interface. One interesting finding in this study is that the post-treatment with a NaOH solution significantly reduced the time for repairing a surface-breaking crack using an EDT process.(4)Experiments in this study were performed using reduced concrete samples and deteriorated by accelerated corrosion tests in the laboratory. More systematic studies are still needed to better understand the rehabilitation performance EDT for the deteriorated concrete in actual reinforced concrete structures.A series of experimental studies was conducted in this research to investigate the rehabilitation performance of electrochemical deposition treatment (EDT) for deteriorated reinforced concrete with various severity levels. Deteriorated concrete specimens, representing the three degrees of corrosion phases: corrosion initiation, rust propagation, and formation of a surface-breaking crack, were rehabilitated by a series of EDT processes. It was observed that EDT has a great potential as a comprehensive rehabilitation method for corrosion-induced deterioration with various severity levels. Specific findings and conclusions of this study are drawn as follows:


Increased circulating concentrations of ceramides (Ce) in dairy cows contribute to subcutaneous adipose tissue (SAT) lipolysis and could enhance the risk of developing metabolic disorders. Dietary supply of methionine (Met) or arginine (Arg) alters cellular metabolism in key tissues including SAT. Whether Met or Arg directly affect SAT metabolism when Ce concentrations are elevated is unknown. We propose that Met or Arg could have a beneficial effect within adipose tissue in terms of alleviating potential inflammatory and pro-oxidant effects associated with the transition into lactation.N-Acetyl-d-sphingosine). Ceramide stimulation downregulated the overall abundance of phosphorylated (p) protein kinase B (AKT), p-mechanistic target of rapamycin (mTOR), and p-eukaryotic elongation factor 2 (eEF2). Without Ce stimulation, increased Met, Arg, or Met + Arg resulted in lower p-mTOR. Compared with control SAT stimulated with Ce, increased Met, Arg, or Met + Arg resulted in greater activation of mTOR  and AKT , with a more pronounced response due to Arg. The greatest protein abundance of glutathione S-transferase Mu 1 (GSTM1) was detected in response to increased Met supply during Ce stimulation. Ceramide stimulation decreased the overall protein abundance of the Na-coupled neutral amino acid transporter SLC38A1 and branched-chain alpha-ketoacid dehydrogenase kinase (BCKDK). However, compared with controls, increased Met or Arg supply attenuated the downregulation of BCKDK induced by Ce. Circulating ceramides might affect amino acid, insulin signaling, and glutathione metabolism in dairy cow adipose tissue. Further in vivo studies are needed to confirm the role of rumen-protected amino acids in regulating bovine adipose function.The objective was to perform a proof-of-principle study to evaluate the effects of methionine (Met) and arginine (Arg) supply on protein abundance of amino acid, insulin signaling, and glutathione metabolism-related proteins in subcutaneous adipose tissue (SAT) explants under ceramide (Ce) challenge. SAT from four lactating Holstein cows was incubated with one of the following media: ideal profile of amino acid as the control , increased Met , increased Arg , or incMet plus incArg (Lys:Met 2.5:1 Lys:Arg 1:1) with or without 100 μM exogenous cell-permeable Ce ( Lipolyse uptake . Thus, SBesides its profound effect on insulin signaling in mammalian cells, downregulation of amino acid (AA) transporters by ceramides could lead to cell death . A lowerThe mechanistic target of rapamycin (mTOR), a key regulator of protein synthesis and cell growth and proliferation in mammals , is reguDespite being a semi-essential AA for adult mammals, available data on Arg highlighted its significance in promoting milk protein synthesis  and alleAs the role of Arg in modulating mTOR in bovine SAT is largely unknown, and there is evidence to support a role for Met on SAT AA and glutathione metabolism, our hypothesis was that enhanced Met and/or Arg supply could counteract negative effects of Ce via increased AA transport and mTOR activation in bovine SAT. Thus, the main objective of this study was to investigate the effects of Met and Arg supply, alone or in combination, on the abundance of AA transporters and mTOR, insulin signaling, and glutathione metabolism-related proteins in bovine SAT explants challenged with C2:0-ceramide.All procedures involving the handling and slaughter of cows were conducted under protocols approved by the University of Illinois Institutional Animal Care and Use Committee . Four clinically-healthy multiparous lactating Holstein cows from the University of Illinois dairy herd that were due to be culled for being open were used. Average body weight, parity, days in milk, and milk yield prior to slaughter were 696 kg, 4, 248 d, and 27.0 kg/d, respectively. Cows had ad libitum access to the same diet formulated according to NRC (2001) [Cows were euthanized with a captive bolt at the College of Veterinary Medicine diagnostic laboratory facilities . Samples of SAT from the tailhead were obtained immediately post-slaughter and brought to the laboratory in warm Dulbecco’s modified Eagle’s medium and Ham’s F-12 nutrient mixture  containing 1% penicillin/streptomycin  within 30 min of collection. Subsequently, the tissue was trimmed into pieces using a sterile scalpel blade in a sterile Petri dish , and then 200 mg tissue was incubated in duplicate in 5 mL of medium in 6-well plates. Culture media were: ideal profile of EAA as the control , increased Met , increased Arg , or incMet plus incArg  with or without 100 μM exogenous cell-permeable C2:0-ceramide . The dose of C2:0-ceramide was based on a previous in vitro bovine adipose tissue study [2. After 4 h incubation, SAT explants were transferred from 6-well plates to screw-capped microcentrifuge tubes, snap-frozen in liquid nitrogen, and preserved at −80 °C until further analysis.Ten EAAs  were added into the custom high-glucose serum-free DMEM  . BrieflyTotal protein was extracted using RIPA lysis and extraction buffer  containing Halt protease and phosphatase inhibitor cocktail , following the manufacturer’s instructions. Protein concentration was measured using the Pierce BCA protein assay kit . Details of the Western blot procedure were reported previously . Brieflyp ≤ 0.05.All data were analyzed as a 2 × 2 × 2 factorial arrangement of treatments using the MIXED procedure of SAS 9.4 . The 3 factors were Met, Arg, and C2:0-ceramide, each including 2 levels: basal or increased levels of Met or Arg and with or without C2:0-ceramide, leading to 8 treatments. The model contained the main effects of Met, Arg, and C2:0-ceramide, as well as the following interactions: Met × Arg × C2:0-ceramide, Met × C2:0-ceramide, Arg × C2:0-ceramide, and Met × Arg. The random effect was cow. Variables were assessed for normality of distribution using the Shapiro–Wilk test. Non-normally distributed data were log2-scale transformed to fit the normal distribution of residuals. Least squares means and standard errors were determined using the LSMEANS statement of SAS v.9.4 (SAS Institute Inc.) and were compared using Tukey’s test when significant interactions were observed. Significance was determined at p < 0.01; p < 0.01; p < 0.01; p < 0.01; p < 0.01; p < 0.01; p < 0.01; p < 0.01; p < 0.01; p < 0.01; p < 0.01; p < 0.01; p < 0.01; p < 0.01; p < 0.01; p < 0.01; p < 0.01; p < 0.01; Ceramide stimulation downregulated overall abundance of p-AKT, p-mTOR and p-eEF2  and GSTM1, suggesting that these proteins might be crucial during the peripartal period ,33. DairIn the current study, the lower GSTM1, coupled with lower activation of p-AKT in SAT during stimulation with C2:0-ceramide, suggested that this metabolite could impair insulin signaling and may also disrupt redox balance in SAT. Although increased Met had no overall effect on the activation of AKT, it is noteworthy that the greatest protein abundance of GSTM1 in response to enhanced Met supply was observed in SAT stimulated with ceramide suggesting that enhanced Met itself might play a positive role within SAT under physiological conditions that increased concentrations of these compounds.In nonruminants, it is well-established that the mTOR signaling pathway is a key regulator of protein synthesis, cell growth, and proliferation . Amino aSome limitations of the present study should be acknowledged. First, by design, this study narrowly focused on few components of the AA, insulin signaling, and glutathione metabolism-related pathways during C2:0-ceramide stimulation under basal conditions. Thus, the effect of insulin per se could not be clarified and will require, for example, an insulin challenge. Second, in spite of its use in similar studies , a supraOverall, data suggested that stimulation with C2:0-ceramide could inhibit AA uptake by adipose tissue and decrease insulin signaling. Under those conditions, enhancing the supply of Arg or Met contributed to altering AA metabolism by increasing the protein abundance of BCKDK and mTOR pathway activity. Unique responses to Arg and Met supply during ceramide stimulation included greater activation of mTOR by Arg, while Met increased the antioxidant response through upregulation of GSTM1. Future in vivo work is warranted to investigate how AA modulate the effect of longer-chain ceramides on insulin signaling in dairy cows, especially during the peripartal period. The focus should be placed on both SAT and immune cell activation.


The surface film thickness reached up to 1.94 mm after repair. The average infrared temperature increase in the repaired specimens at different damage temperatures was averagely reduced by about 80% compared with that before the repair. It showed more obvious repair effects at higher temperatures in water absorption and compressive strength tests; the compressive strength of repaired specimens was 194% higher than that before repairs at 600 °C. A negative pressure method was found to be more effective than an immersion method. This study revealed the utilization of SICP on repairing high-temperature damage of concrete is feasible theoretically.In this study, the effects of soybean-urease-induced carbonate precipitation on a high-temperature damage repair of concrete were explored. C50 concrete specimens were exposed to high temperatures from 300 to 600 °C, then cooled to an ambient temperature and repaired by two different methods. The influences of the damage temperature and repair methods on surface film thickness, average infrared temperature increase, water absorption, and compressive strength were investigated. Scanning electron microscopy (SEM) images were carried out to further study the mechanism involved. The results revealed that the white sediments on the surface of the repaired specimens were calcium carbonate (CaCO Concrete structures are the largest type of building structures worldwide, and they will still be the main type of building structures for a long time in the future. Fire is one of the most severe building disasters. The frequency of building fire is very high, and it is easy to cause disastrous consequences. According to the statistics from the Fire and Rescue Department Ministry of Emergency Management of China, there were 109,000 residential fires in 2020, accounting for 43.4% of the total fires, causing 917 deaths and 499 injuries, accounting for 77.5% and 64.4% of the total casualties, respectively.The fire damage of concrete is mainly due to high temperature. Du  expoundeThe mechanical properties and durability of concrete are significantly reduced after a fire. Wu et al.  preparedIn order to deal with high-temperature damage of concrete, some researchers try to improve the fire resistance of concrete. Hossein et al. ,5 proposThis method can improve the fire resistance of concrete and reduce the damage caused by building fires from the root. Moreover, industrial waste is used, which is in line with the principles of economic and energy efficiency and being environmentally friendly. However, how to repair concrete damages after a fire is not in their research content. Fires still happen frequently, and buildings will still be damaged by fire. If the fire damage of concrete is not repaired timely, external water and corrosive media may penetrate into the damaged concrete, leading to reinforcement corrosion; eventually, the concrete mechanical properties and durability deteriorate rapidly . TherefoThere are many methods to repair the damage of concrete structures , includiSporosarcina pasteurii) can produce urease through metabolism. Urease can decompose urea in the environment to produce carbonate ions and ammonium ions. Bacteria carry negative charges on their surfaces, and calcium ions in the environment are adsorbed to form calcium carbonate (CaCO3) crystals with bacteria as the crystal nucleus. These CaCO3 crystals adhere to concrete defects in the liquid environment so as to repair concrete defects. Some urease-producing bacteria . The mechanism of SICP and MICP are similar. The urease of MICP comes from microbial metabolism, while the urease of SICP is directly extracted from soybean.Mobley  reviewedm value of soybean urease as Before the SICP technique is applied to repair the fire damage of concrete, it is necessary to find an appropriate method to extract soybean urease. Several researchers studied the extraction of soybean urease and the determination of urease activity. Zhou et al.  extracte58 U. Gu  compared3 precipitated by the SICP technique. Yuan et al. [3 was produced if the concentration of urease was low, and CaCO3 crystals changed to spheres with the increase in urease concentration.Are the crystals produced by SICP suitable for fire damage repair of concrete? Some researchers studied the crystal structures of CaCOn et al.  studied 3 precipitation to solidify silty soil. In the triaxial consolidated undrained test, the solidified silty soil showed a greater expand response on the stress-strain curve, indicating significantly improved mechanical properties. Gao et al. [2) was determined as 0.2 mol/L and 4 L/m2, respectively.At present, the researches on SICP are mainly in the following fields. Gao et al.  used soyo et al.  carried Research on the numerical parametric analysis of SICP was also carried out. Chen et al.  carried It is obvious that the research on SICP is mainly concentrated in the windbreak, sand fixation, and soil consolidation at present. However, findings on high-temperature damage repair of concrete are sparse. There are many pieces of research on MICP on the repair of concrete defects, and these studies have achieved some results. The mechanisms of MICP and SICP are similar; it is reasonable to believe that SICP can also achieve results in the high-temperature damage repair of concrete. High-temperature damage of concrete is characterized by gradual loosening and cracking from the outside to the inside, and most of the defects are cracks . AccordiIn this study, the SICP technique was used to repair high-temperature damage of concrete by two different repair methods. The apparent characteristics, surface film thickness, average infrared temperature increase, water absorption, and compressive strength of concrete were tested to evaluate the repair effect. At the same time, the mechanisms involved were studied by scanning electron microscopy (SEM) imaging and an energy dispersive spectrometer (EDS). The results of this study will provide theoretical bases for applying SICP in repairing high-temperature damage of concrete.The raw materials in this study include dried soybean flour , deionized water, urea analytical reagent , calcium acetate analytical reagent , P.O 42.5 ordinary Portland cement , 5–26.5 mm continuously and well-graded crushed stone, IIarea medium sand with fineness modulus of 2.87, and polycarboxylate superplasticizer  with water-reducing ratio 15–20%.C50 concrete is often used in buildings and structures, and it was also used in this study. The mix proportion of C50 concrete is shown in For each test, 40 mm cube specimens were cast and cured for 24 h in accordance with GB/T 50081-2019  and GB/TThe concrete specimens were divided into five groups; they were ambient temperatures, 300 °C, 400 °C, 500 °C, and 600 °C, respectively. There was a thermocouple embedded in the center of one specimen in each group. A muffle furnace was used to heat the specimens. The heating rate was set as 10 °C/min. The temperature in the center of the specimens was shown on a temperature inspection instrument outside the muffle furnace in real-time. When the temperature shown on the temperature inspection instrument reached 300 °C, 400 °C, 500 °C, and 600 °C, respectively, the center of the specimens reached the corresponding temperature, then the muffle furnace was turned off, the furnace door was opened for cooling, as shown in Soybean flour was sifted out with a 100 meshes sieve. It was then added in deionized water, and the mixed solution was stirred evenly and allowed to rest for 2 h. The supernatant was taken out and filtered with gauze. The filtered solution was the crude extract solution of soybean urease. The urease activity of the crude extract solution was tested by the conductivity method proposed by Victoria . From meThe immersion and negative pressure methods were used to repair concrete specimens damaged by high temperature in this study. Urea and calcium acetate were mixed to prepare 1 mol/L repair solution according to molar mass 1:1 in the two different methods. Crude extract solution of soybean urease was added into the repair solution according to the volume fraction of 5%. The ambient temperature was maintained at 30 °C throughout the process. The specimens were put in a beaker, then the mixed solution of urea, calcium acetate, and crude extract solution of soybean urease was added to the beaker in immersion method. The specimens were subsequently dried after reaching the predetermined repair time, whereas in negative pressure method, specimens were treated with negative pressure refers to the ‘rapid chloride migration coefficient method’ in GB/T 50082-2009 . The speAfter repair, the white sediments on the surface of repaired specimens along with the repaired specimens themselves were analyzed. The white sediments on the surface of specimens repaired by negative pressure method for 72 h were scraped off to prepare EDS samples. The concrete specimens damaged at 600 °C and repaired by immersion and negative pressure methods for 72 h were cut into two parts, and a small block with repair marks was chiseled by a small hammer to prepare SEM samples. The samples were observed by a TESCAN-LYRA3 scanning electron microscope . The SEM was equipped with an EDS module, which made it possible to analyze the chemical elements and their content in the selected area in real-time.The surface of repaired specimens was enlarged by an industrial camera to measure the surface film thickness. The concrete specimens damaged at 600 °C and repaired by immersion and negative pressure methods were taken as research objects. According to Victoria’s  formula,Infrared thermal imaging is a nondestructive test method that transforms the infrared radiation from the targets into visible thermal images, making it possible to analyze the temperature distribution on the surface of objects and to infer the defects on the surface of objects . The infThe infrared thermal images of concrete specimens before heating, after heating, and after repairs were performed by a TH9100WV  infrared thermal imager in accordance with GB/T 19870-2018 , as showWater absorption is an item of concrete durability reflecting the surface damage degree and the internal compactness of concrete. It was used to measure the repair effect of concrete in this study.M0). After cooling to ambient temperature for 6 h, the specimens were put into a water tank with a temperature of (20 ± 2) °C. Water was added to the water tank; the water height was first kept to M) immediately. The water absorption was calculated according to the formula: The concrete specimens before heating, after heating, and after repair were tested for water absorption in accordance with GB/T 11969-2020 . A groupCompressive strength is one of the most critical parameters of concrete mechanical properties. The compressive strength of undamaged specimens, damaged specimens, and repaired specimens was compared to reveal the repair effect in this study. The concrete specimens before heating, after heating, and after repair were tested for compressive strength according to GB/T 50081-2019 .Compared with the undamaged specimen a, there Concrete is a hydrophilic material; when the dry specimen is immersed in the repair solution, it will quickly absorb the repair solution. With the action of negative pressure, the repair solution enters the interior of the specimen, so the white sediments deposit on both the upper surface, the sides, and even on the bottom surface of the concrete specimen. As a consequence, the cracks and pores on the sides are completely filled with white sediments. The repair solution is runny, and gravity plays an important role in the deposition of sediments; more sediments are deposited on the upper surface than on the sides, so the film thickness of the upper surface is thicker than that of the sides. Fan et al.  also menThe white sediments on the upper surface of the specimen were scraped off in layers and analyzed by EDS. 2O4), the upper sediments may be calcium carbonate (CaCO3).2O4 crystals from the upper layer and CaCO3 crystals from the bottom layer, respectively.2O4 and CaCO3 crystals. There are obvious differences in morphology and size between CaC2O4 and CaCO3 crystals. The CaCO3 crystals from the bottom layer are almost solid spheres with smooth surfaces, and the spheres are uneven in size with a diameter of 5–10 μm. They stacked with each other and arranged closely and continuously. In contrast, the CaC2O4 crystals from the upper layer are mainly spheres, with some irregularly shaped crystals attached to them. Unlike CaCO3 crystals, their surfaces are rough, even cracks distributed on the surfaces of some crystals. The spheres are smaller with a diameter of 2–10 μm, compared with the CaCO3 crystals from the bottom layer.As 2O4 and CaCO3 crystals may be due to the high activity of soybean urease in the early stage of decomposition, which makes the urea in the repair solution quickly decomposed to produce carbonate ions and ammonium ions. At this time, the content of carbonate ions in the repair solution is significantly less than that of calcium ions, so carbonate ions are surrounded and attracted by calcium ions; the crystallization speed on each crystal plane is almost the same, so the crystal morphology is a sphere. Large crystals have a relatively large weight; under the action of gravity, they precipitate on the bottom layer. As decompose time goes by, the decompose rate decreases with the decrease in soybean urease activity. At the same time, the content of calcium ions in the repair solution decreases due to the precipitation of crystals. At this time, the crystallization speed on each crystal plane is different. The growth of crystal morphology is irregular, CaC2O4 and some irregular crystals are formed, even cracks appear on their surface.The difference between the morphology and size of CaCNotably, the crystals generated on the surface of specimens are smaller than the particle size (5–80 μm) obtained by Qian et al. . This isAs It can be seen from As seen in As for the surface film thickness of the two different repair methods, the negative pressure method is slightly higher (less than 5%) than the immersion method, indicating that surface film thickness is less affected by the repair method.When the urea in the repair solution completely decomposed, the surface film thickness by immersion method reaches 1.84 mm. Compared to the film thickness, which also used the immersion method by Qian et al. , the filAs seen in From As seen in (1)2O4 and CaCO3 crystals are formed, CaCO3 crystals are larger, and the depose effect is better; these two kinds of crystals make the concrete denser.From the results of EDS and SEM, CaC(2)From the results of apparent characteristics, surface film thickness, and average infrared temperature increase, SICP has a good effect on the surface repair of high-temperature damage of concrete; the repair effect of the negative pressure method is slightly better than that of the immersion method.(3)From the results of water absorption and compressive strength, SICP has a certain effect on the recovery of mechanical properties and durability of damaged concrete; the repair effect of the negative pressure method is obviously better than that of the immersion method.This study extended the SICP technique to the field of high-temperature damage repair of concrete. The applicability of SICP on high-temperature damage repair of concrete was examined by a series of laboratory tests. Based on the results achieved during this study, the following conclusions are drawn:This study revealed that the utilization of SICP in the repair of high-temperature damage of concrete is feasible theoretically. However, the actual application effect requires further examination. Firstly, repair method. The two methods in this study can be used in the laboratory, but they are difficult to apply in practice. Spraying, daubing, and painting are common in practical engineering. However, these methods were not used in this study; the repair effect of these methods needs to be examined. Secondly, repair effect at a lower temperature. The repair effect below 500 °C was not obvious. It needs further study to improve the repair effect when the temperature is not so high. Finally, regarding the internal repair, the surface repair effect was significant, but the internal repair effect has not been fully studied; thus, it needs to be further investigated. If these issues have been addressed, SICP will have a broad prospect in more fields in the near future.


On account of the better diffuse ability of nanocrystals, the time needed for solvent exchange and guest soaking protocols are shortened 50-fold faster versus the original protocol. The crystal structure of the crystalline sponge incorporated with three different guests was fully resolved using a merged dataset. The structure model was identical to previously reported ones using x-ray, showing that the accuracy of the 3D-ED was comparable with SCXRD. The refinement results can also give the precise occupancy of the guest molecule soaked in the porous crystal. This work not only provides a new data collection strategy for crystalline sponge method but also demonstrates the potential of 3D-ED techniques to study host-guest interaction by solving the fine structure of porous material.The crystalline sponge method has shown to be a novel strategy for the structure determination of noncrystalline, oily, or trace amount of a compound. A target compound was absorbed and oriented orderly in the pregrown porous crystal for x-ray diffraction analysis. However, the diffusion in the micron-sized crystals is rather difficult. Lots of trial-and-error experiments are needed to optimize the guest-soaking process and to improve data quality. Nanocrystals are better in diffusion, yet it could not conduct a single crystal x-ray diffraction (SCXRD) analysis. Three-dimensional electron diffraction (3D-ED) is a powerful diffraction tool for the structure determination of small crystals. In this work, we successfully carried out the crystalline sponge method by 3D-ED technique using {(ZnI A molecular structure of a substance determines its intrinsic properties, such as reactivity, stereochemistry selectivity, etc. Chemists have developed nuclear magnetic resonance spectroscopy (NMR) and mass spectroscopy (MS) to provide essential structural information, but there are still chances to assign the structure incorrectly. Single-crystal x-ray diffraction (SCXRD) is the standard method that provides a direct three-dimensional structure at the atomic level. However, the major limitation of SCXRD is that it requires the target compound to crystallize into a single crystal with sufficient quality and size (>5 μm × 5 μm × 5 μm).2)3-(tpt)2·x(Guest)]n porous complex . The CS method has successfully determined the structure of natural products  method . The CSsproducts , metabolproducts , and phaproducts . This meproducts . Howeverproducts . UnoptimThree-dimensional electron diffraction (3D-ED) is an emerging technique that collects single-crystal diffraction data from a nanocrystal . It has ab initio and have comparable accuracy with a traditional x-ray diffraction method.In this work, we demonstrate the crystalline sponge method using the 3D-ED technique with nanosized CS crystal. Using a merged dataset with high completeness and resolution, the position of the framework and the guest molecule can be resolved 2 and guaiazulene were purchased from the Shanghai Aladdin Biochemical Technology Co., Ltd. All solvents used were purchased from Energy Chemical Co.2,4,6-Tris(4-pyridyl)-1,3,5-triazine was purchased from the Energy Chemical Co. ZnI2)3-(tpt)2·x(Guest)]n porous complex  (donated as 1-Guest) host was synthesized following the protocol of Fujita (2 (14.4 mg in 1.5 ml) on a nitrobenzene solution of (9.5 mg in 6 ml). The solution was left for 7 days for crystallization. The powder-like 1-Nitrobezene at the bottom of the bottle was transferred to a new glass vial. It was then washed 2–3 times cyclohexane using the same volume of the synthesis liquid. The powder-like crystals were heated in cyclohexane at 50°C for 2 h and stored in the same liquid after it cooled to room temperature. The solvent exchange process was monitored by IR spectroscopy  was added in the vial. The pierced capped vial was heated at 50°C for 12 h and transferred to 4°C for storage. This sample was noted as 1-Guaiazulene.The n (noted as 1-Guest) was synthesized following the protocol of Fujita  to cyclohexane (less affinity) for better guest-soaking result, the powder-like 1-Nitrobenzene was washed with cyclohexane several times and soaked in it at 50°C for 2 h (donated as 1-Cyclohexane). The IR spectroscopy signal at 1,346 cm−1, assigned to nitrobenzene, completely disappeared (1-Cyclohexane was soaked in the cyclohexane solution of guaiazulene (1 mg/ml) in a pierced capped vial at 50°C for 12 h and then transferred to 4°C for storage. This guest-soaked sample was noted as 1-Guaiazulene. The guest inclusion time (12 h) needed in this work was about fourfold faster than that in the original protocol (2 days)  as synthesized, 2) solvent exchanged, and 3) guest included. The crystalline sponge n framework is flexible to the response of the guest. Therefore, the guaiazulene-soaking condition will influence the fine structure, i.e., host conformation, number, and the position of the guests, dramatically. The guest location and occupancy in the literature-reported ones are also different   are almolved one . We beliifferent . This re2)3-(tpt)2·x(Guest)]n porous complex nanocrystals. Utilizing the better diffuse ability of small crystals, the time needed for solvent-exchange and guest-soaking protocols were shortened to 2 and 12 h respectively, about 50-fold faster versus the original protocol. It should be noticed that these conditions can be further optimized. The structures of 1-Nitrobenzene, 1-Cyclohexane, and 1-Guaiazulene were fully resolved using a merged dataset. The structure model was identical to previously reported ones using x-ray, showing that the accuracy of the 3D-ED was comparable with SCXRD. The occupancy of the guest molecule, nitrobenzene and guaiazulene, were 0.81(3) and 0.465(15), respectively. This work not only provides a new data collection strategy for crystalline sponge method but also demonstrates the potential of the 3D-ED techniques to study host–guest interaction by solving fine structures of porous materials.In conclusion, the crystalline sponge method was successfully carried out by the 3D-ED technique using [(ZnI


Photobiomodulation with low-intensity laser (LIL) and chondroitinase ABC (ChABC) can repair damaged muscle tissue, so the aim of this study was to investigate the effect of co-administration of these two factors on anal sphincter repair in rabbits.Male rabbits were studied in 5 groups (n = 7): Control (intact), sphincterotomy, laser, ChABC and laser + ChABC. 90 days after intervention were evaluated resting and maximum squeeze pressures, number of motor units, collagen amount, markers of muscle regeneration and angiogenesis.p < 0.0001). Maximum squeeze pressure in the all study groups was higher than sphincterotomy group (p < 0.0001). In the laser + ChABC and ChABC groups, motor unit numbers were more than the sphincterotomy group (p < 0.0001). Collagen content was significantly decreased in the laser (p < 0.0001) and laser + ChABC groups. ACTA1 (p = 0.001) and MHC (p < 0.0001) gene expression in the Laser + ChABC group were more than the laser or ChABC alone. VEGFA (p = 0.009) and Ki67 mRNA expression (p = 0.01) in the Laser + ChABC group were more than the laser group, But vimentin mRNA expression (p < 0.0001) was less than the laser group.Resting pressure in the Laser + ChABC group was higher than the sphincterotomy, laser and ChABC groups (Co-administration of ChABCs and photobiomodulation with LIL appears to improve the tissue structure and function of the anal sphincter in rabbits more than when used alone.The online version contains supplementary material available at 10.1186/s12876-021-02047-2. Anal sphincter injury is one of the pelvic floor disorders, a major cause of fecal incontinence (FI). FI occurs in patients due to the injured anal sphincter's weakness in obstruction of the anal canal , 2 irresOn the other hand, fibroblasts have a wide range of chromophores stimulated by different wavelengths of laser . FollowiThe present experimental study was designed and performed according to the ARRIVE standard guidelines  Guidelines. In this study, 35 male rabbits with 5 groups (n = 7) were studied. To minimize bias in the study, the animals were randomly divided into study groups. The researchers performing the experimental, data gathering, and interpretation of the data were blinded to the study. Each rabbit was kept in separate cages during the study procedure.In this study, 35 healthy New Zealand white male rabbits weighing 2.5–3 kg were prepared from Pasteur Institute of Iran, Iran, Tehran. All animals were individually housed in rabbit cages  in the standard conditions (21 ± 3 °C and 12-h light and dark cycle) by access to the sufficient storage of fresh water and food.Animals randomly were divided to 5 equal groups (n = 7) consist of: (A) Control, (B) Sphinctrotomy, (C) Laser, (D) ChABC, and (E) ChABC + Laser Table .Table 1ESphincterotomy was performed based on the fourth degree rupture of the 1999 Sultan classification  . As in oIn this study, a CW diode laser with a wavelength of 660 nm and power of 100 mW  was used. The laser irradiation device was mounted on a metal height-adjustable stand (2 cm to the lesion site) to stabilize the laser's irradiation point. The location of the laser irradiation was three points (each point 5 mm wide). The first and second points included the border between the lesion and the healthy tissue of the sphincter (both sides of the lesion) and the third point was the center of the lesion. The irradiation time at each point was 30 s .Immediately after sphincterotomy, the lesion site was irradiated. Laser irradiation was performed every day for 14 days at the specified time (2 pm).ChABC  diluted with 0.01% bovine serum albumin in normal saline (10 µl of 100U/ml/in situ). A single dose was injected immediately after sphincterotomy with a Hamilton syringe attached to the microinjection device. The injection was made by inserting a 5 mm needle on two edges of the lesion in the sphincter (5 µl per edge) slowly over 2 min. After an injection to prevent ChABC leakage, the needle remained in place for 2 min.The standard anorectal catheter (4.7 mm 8 h) and a pressure transducer  were used to perform manometry. After three months, to measure the pressure of the anal sphincter, after inserting the probe into the rectum and positioning the balloon baseline pressure, at the same time as the probe was pulled out (constant rate of 0.05 cm/s), the sphincter pressure profile (resting and maximum squeeze pressures) was recorded. Manometry was done three times for each rabbit by the blind operator.2/Ambu Copenhagen, Denmark). Rabbits were placed in a lithotomy position (without anesthesia or relaxant). The EMG needle was inserted vertically at the sphincterotomy site (in the boundary of anus mucosa and skin/depth of 0.5 cm). After setting the device (sweep: 10 ms/cm and Sensitivity: 100–200), the number of motor units was recorded and counted for 20 s for each rabbit by the blind operator.To record EMG from the sphincterotomy site after three months, a Synergy on Nicolet EDX System  was used with disposable electrode and needle  were anesthetized. After cardiac perfusion , the anal sphincter was completely removed and post-fixed  in each group. After tissue preparation and paraffin molding process, serial transverse sections were prepared (10 µm thickness). The rest of the animals in each group (n = 4) after deep anesthesia were sacrificed, and their anal sphincter was freshly removed. Finally, the sphincterotomy site was separated and stored at − 80 °C for Real-time PCR assessment.In each group, three animals were selected, and three sections from each animal were stained with Mallory's Trichrome method for collagen assessment. In this method, collagen fibers are seen in blue. After photographing the sphincterotomy site (light microscopy ×40), the area occupied by blue dye to the sphincterotomy site was considered to the amount of collagen . The rat2O2 10% (diluted in methanol) for 15 min. Third incubation was done at 37 °C by Goat Serum 10%  for 30 min (due to the blocking process). The primary antibody did fourth incubation at four °C, humidified environment for 24 h. After three times washing with PBS, final incubation was done by the secondary antibody in the dark, 37 °C, humidified atmosphere for 2 h. After the exact final three times washing with PBS, DAPI staining was done due to cell nuclei staining. Tissue sections were assessed and photographed (fluorescence microscopy × 10).The list of primary and secondary antibodies and their number codes are given in Table S1. IHC was performed according to standard protocols. Briefly as follows: First incubation of tissue sections was done in 95 °C with citrate buffer (PH = 6) for 10 min . After washing with PBS, second incubation was done by HThe total RNA of Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), Vascular endothelial growth factors A (VEGFA), Myosin heavy chain (MYH), Actin alpha 1, skeletal muscle (ACTA1), Ki67, and Vimentin was extracted by EURx RNA Extraction Kit. Then, 1 mg of total RNA was reverse transcribed using EURx cDNA synthesis kit and random hexamer primer. Real-time PCR was performed using Stepone ABI , QuantiTect primers (Kyagen Company), and Master Mix Cyber Green PCR. The sequence of primers is shown in Table S2. Data were normalized to GAPDH as a housekeeping gene.P-value less than 0.05 was considered significant. SPSS® for windows version 16 software was used for analysis.Quantitative data are reported as mean (standard deviation) or median (range) and qualitative data as frequency (percent). One-way ANOVA and Bonferroni post hoc was used to assess any differences in studied groups. A df: 4, 34; F = 226.6; p < 0.0001). Photobiomodulation with LIL (p < 0.0001) and administration of ChABC (p < 0.0001) led to a significant improvement in resting pressure compared to the sphincterotomy group. Co-application of ChABC + Laser increased the resting pressure compared to laser and ChABC alone (p < 0.0001). There is no significant difference between the laser and ChABC group (p > 0.99).90-day after sphincterotomy, a significant decrease was observed in resting pressure in all treated groups compared to control animals . Treatment with laser, ChABC, and ChABC + Laser led to a significant improvement in the maximum squeeze pressure compared to sphincterotomized animals (p < 0.0001). The laser had better efficacy on maximum squeeze pressure than ChABC (p = 0.011). Co-administration of ChABC + Laser is associated with higher maximum squeeze pressure than laser (p = 0.005) and ChABC (p < 0.0001) alone . The laser (p < 0.0001) and ChABC + Laser groups (p < 0.0001) displayed substantially more motor units than the sphincterotomy group (p < 0.0001). However, administration of ChABC did not affect the number of motor units (p = 0.567). Finally, there is no significant difference between laser alone and ChABC + Laser in increasing motor units (p > 0.99) . Photobiomodulation with LIL (p < 0.0001) and a combination of ChABC + Laser (p < 0.0001) decreased the collagen amount compared to the sphincterotomy group. However, administration of ChABC did not reduce the collagen content (p > 0.99). Similar results were seen in the muscle tissue  . Photobiomodulation with LIL (p = 0.005) and ChABC + Laser (p < 0.0001) significantly increased the α-actin gene expression and reached to intact animals (pfor laser = 0.643 and pfor ChABC + Laser > 0.99). ChABC administration did not change the level of α-actin gene expression (p > 0.99). The level of α-actin gene expression in the ChABC + Laser group was significantly higher than ChABC (p < 0.0001) and Laser (p = 0.033) alone treated animals. The immunohistochemical assessment showed similar findings . ChABC (p = 0.003), photobiomodulation with LIL (p = 0.001) and ChABC + Laser (p < 0.0001) administration significantly increased the myosin heavy chain gene expression. The level of myosin heavy chain gene expression in the ChABC + Laser group was significantly higher than ChABC (p = 0.001) and laser (p = 0.002) alone treated animals. The immunohistochemical assessment showed similar findings . Although, ChABC (p > 0.99) and laser (p > 0.99) administration did not change the VEGF gene expression but the combination therapy (ChABC + Laser) significantly increased level of VEGF expression . The VEGF expression level was significantly higher in the ChABC + Laser group than laser and ChABC alone treated animals (p < 0.0001). The immunohistochemical assessment showed similar findings . ChABC administration (p < 0.0001), photobiomodulation with LIL (p < 0.0001) and ChABC + Laser (p < 0.0001) administration significantly decreased the vementin gene expression. The level of vimentin expression reached intact animals in laser (p = 0.464) and ChABC + Laser (p > 0.99) groups. The vimentin gene expression level in laser (p = 0.035) and ChABC + Laser (p = 0.001) was less than the ChABC group. The immunohistochemical assessment showed similar findings . Photobiomodulation with LIL (p = 00.1) and ChABC + Laser (p = 0.04) administration significantly increased the Ki67 gene expression. The level of Ki67 expression reached intact animals in laser (p = 0.501) and ChABC + Laser (p > 0.99) groups. Ki67 expression was significantly higher in the laser group compared to the ChABC group (p = 0.002). The immunohistochemical assessment showed similar findings  are located in the perineal surface area, so a wavelength of 660 nm was chosen for laser therapy. The best laser wavelength in such cases is 600 to 700 nm  because,The present study depicted that following the anal sphincter injury, immediate co-application of ChABC and photobiomodulation with LIL improve sphincter function by promoting myogenesis and angiogenesis. This protocol is more efficient than laser and ChABC treatment alone.Additional file 1.List of antibodies Primer sequences. Table S1: The list of primary and secondary antibodies. Table S2: Primer sequences.


Bloodstream infections are traditionally treated with intravenous (IV) antimicrobial therapy, which may increase length of stay and healthcare costs. The purpose of this study is to evaluate if oral antibiotic step-down therapy for non-staphylococcal gram-positive bloodstream infections (GP-BSIs) is non-inferior to IV antibiotics.Staphylococcus aureus, non-Staphylococcus lugdunensis GP-BSI from January 2017 to December 2019. Patients were excluded if they fit any of the following criteria: organism identified as contaminant, polymicrobial BSI, recurrent BSI within the past 90 days, or receipt of an effective antibiotic for a duration longer than what is indicated for BSI treatment. Patients were categorized into those who received an IV antibiotic for the total duration of therapy and those who received an oral step-down antibiotic for at least one-third of the treatment course. The primary composite outcome was the incidence of 90-day clinical failure consisting of 90-day all-cause mortality, change in therapy due to inadequate clinical response, and 90-day BSI recurrence. The secondary outcomes included the individual components of the primary composite outcome, line-related complications, and hospital length of stay. Bivariate analysis was conducted to assess for predictors of 90-day clinical failure.This single-center, retrospective cohort study included patients with a non-p=0.045). The oral group had a higher proportion of GP-BSI caused by streptococcal species . The oral group had a lower incidence of 90-day clinical failure and was found to be noninferior to the IV group . The IV group had a longer hospital length of stay , however there were no other significant differences in secondary outcomes. Bivariate analysis found no significant predictors of 90-day clinical failure.A total of 308 patients were included . Pitt Bacteremia Scores were low overall, but higher in the IV group (0 vs 1, Oral antibiotic step-down therapy was found to be non-inferior to IV antibiotic therapy, and thus may be an alternative option for the treatment of non-staphylococcal GP-BSIs.All Authors: No reported disclosures


Nano graphite platelets (NGPs) belong to the carbon family and have a huge impact on the construction industry. NGPs are used as multi-functional fillers and have the potential to develop reinforcing within cementitious composites. In this paper, NGPs were incorporated in cementitious composites to investigate the effects of NGPs on the fresh, mechanical, durability, and microstructural properties of concrete. Five mixes were prepared with intrusion of NGPs . The properties studied involved workability, air content, hardened density, compressive strength, tensile strength, flexural strength, sorptivity, ultrasonic pulse velocity (UPV), water absorption, and external sulfate attack. The workability and percent air content decrease by 22.5% and 33.8%, respectively, for concrete with 5% NGPs compared to the control mix. The specimens containing 5% of NGPs revealed the hardened density, compressive, tensile, and flexural strength to increase by 11.4%, 38.5%, 31.6%, and 44.34%, respectively, compared to the control mix. The results revealed that the incorporation of 5%NGPs in cementitious composites reduces the sorptivity and water absorption by 32.2% and 73.9%, respectively, whereas, it increases the UPV value by 7.5% compared to the control mix. Furthermore, the incorporation of NGPs provided better resistance against external sulfate attacks. SEM–EDX spectroscopy was carried out to investigate its microstructural analysis. Advancements in nanotechnology play a huge role in the construction industry by incorporating new nanomaterials or fibers in concrete, which plays a tremendous role in enhancing its mechanical properties. Today, concrete is more durable and stronger than in the past, because of better knowledge and skills at the nano level, and the improved mechanical characteristics of concrete. These nanomaterials exhibit extraordinary strength in cementitious composites by reinforcing nano levels. Moreover, cement is being replaced by several additives to enhance the cementitious performance of concrete and eco-friendly–sustainable construction ,2,3. The2) , and nanGraphene oxide (GO), nano graphite platelets (NGPs), graphene-based derived, carbon nanotubes (CNTs), etc., are carbon-based nanomaterials that might definitely result in “smart” properties ,13. ChouNGPs are carbon-based nanomaterials derived from graphite. NGPs have a two-dimensional 2D) structure consisting of several layers of graphene and the diameter of particles ranging from submicron up to 100 μm ,19. NGPsD structuA brief assessment of the current literature shows that, to date, there are few published studies concerning the role NGPs on the behavior of concrete, suggesting that a ,15,25,29The remainder of this paper is structured as follows. OPC (Type-1) obtained from BESTWAY cement factory was utilized for concrete production as per ASTM C-150 standard. Locally available “Lawrencepur sand” was utilized as a fine aggregate, having a fineness modulus of 2.25 as per ASTM C-33 standard. Coarse aggregate utilized in this research work was obtained from the Taxila brand , Pakistan, having a maximum particle size of 20 mm, and superplasticizer (polycarboxylate based) was obtained from BASF. Ordinary tap water was used for both castings and curing, having a PH range between 6.5 and 7. The general characteristics of aggregates are enlisted in Nano graphite platelets (NGPs) were commercially procured in powdered form. To investigate the structural characterization of commercial NGPs, SEM, EDX, XRD, and XRF analyses were carried out. SEM, EDX, XRF, and XRD patterns of NGPs are discussed in NGPs are carbon-based nanomaterials and have the tendency to agglomerate and stack to one another, owing to the strong van der Waals forces among the nanoparticles. Moreover, due to their hydrophobic nature, it doesn’t interact with water-based systems ,31. Due 3, 715 kg/m3, and 1113 kg/m3, respectively. Different dosages of NGPs i.e., 0.5%, 1.5%, 3%, and 5% by weight of the cement were added. In this study, a total of five mixes were prepared, and the mix ratio used was 1:1.86:2.89. The water/cement ratio was kept at 0.45. The cement, sand, and coarse aggregate content were kept constant at 384 kg/m3 were prepared. For the sorptivity test, cylindrical samples of 50 mm in thickness and 100 mm diameter were prepared. To determine the influence of external sulfate attack on concrete performance, cylindrical specimens of 150 × 300 mm were cast and cured for 28 days, the specimens were then submerged in sodium sulfate solution of 30 g/L for 28 days, and then the specimens before and after the submersion were tested.To study compressive and tensile properties of concrete, 30 cylindrical specimens of 150 × 300 mm were cast. Whereas, for the analysis of flexural behavior of concrete, 15 prismatic specimens of 100 × 100 × 400 mmThe comprehensive flow chart of the experimental program is indicated in The fresh concrete properties include workability and air content. The air content of fresh concrete was evaluated by the pressure method, as per ASTM C231/C231M-17a . WorkabiThe hardened concrete properties include hardened density, compressive, flexural, and tensile strength of concrete. The hardened density of concrete specimens was calculated using analytical balance, by evaluating its size and weight at saturated surface dry conditions (SSD) after 28 days. As per ASTM C496/C496M-17 and ASTM C39/C39M-12 ,36 standIn Equation (1), 3 were prepared, and by using the flexural testing machine, the specimens were tested. The flexural strength of the rectangular specimens  was determined using the following formula:Flexural strength of NGP-reinforced concrete was determined as per ASTM C78/C78M-18 , by carrIn Equation (2), The durability characteristic of NGP-reinforced concrete were determined based on sorptivity co-efficient, UPV test, water absorption, and external sulfate attack, UPV test. To evaluate the sorptivity co-efficient, the cylindrical specimen 100 × 200 mm was cut into 100 × 50 mm discs, and were tested, as per ASTM C1585-04 . To prevS denotes sorptivity coefficient evaluated in mm/min1/2, t denotes time in minutes, and W1 is the dry weight of the sample in grams, W2 is the sample weight in grams after 4 h of ingression via capillary rise, A is the surface area of the exposed surface, and d is the water density.In Equation (3), The UPV test was performed to analyze the uniformity and quality of cementitious composites. The cylindrical specimens (150 mm in diameter × 300 mm in length) were tested to determine the UPV value. The UPV values were evaluated as per ASTM C597-09 standard. The two transducers, i.e., transmitter and receiver, were provided at both ends of the cylindrical specimen, and then, the pulse velocity, having a frequency range of 55 kHz, was allowed to travel between the two transducers. The travel time between the two transducers was noted, and the UPV value was obtained by dividing the length of the cylinder by the corresponding time of travel.Water absorption of NGP-reinforced cementitious composites was determined as per the ASTM C642 standard . For conAn external sulfate attack test was conducted to check the resistance of concrete against sulfate. A sulfate attack adversely affects the durability characteristics of concrete. To determine the influence of an external sulfate attack on the concrete performance, cylindrical specimens (150 mm in diameter × 300 mm in length) were cast and cured for 28 days, and then the specimens were submerged in a sodium sulfate solution of 30 g/L for 28 days. The concrete specimens were tested before and after the submersion, and the loss/reduction in compressive strength was noted.Study of the microstructure of NGP-reinforced cementitious composites were carried out using SEM and EDX analyses. SEM was carried out according to guidelines mentioned in ASTM C1723 . The SEMThe analysis of commercially available NGPs were conducted by means of SEM, XRD, XRF, and EDX spectroscopy. SEM, EDX, and XRF spectroscopy were carried out to analyze the morphology/surface texture, chemical composition, and mineral oxide composition of NGPs, respectively. The SEM micrograph shown in The workability of nano-reinforced concrete was examined using a slump test. Air content of NGP-incorporated fresh concrete was obtained by the pressure method, as per the ASTM C231/C231M-17a  standardThe evolution of density for samples containing different percentage contents of NGPs  at 28 days is shown in Compressive strength is an essential property of concrete that measures its ability to carry loads and used in the reinforced concrete design. In the present study, the compressive strength of nano-reinforced concrete, having different dosages of NGPs, was examined, as per the ASTM C39  standardThe splitting tensile strength test is widely used to examine a concrete specimen’s resistance to elongation. This test is performed on a cylindrical specimen in accordance with ASTM C496/C496M-17 . The UTMThe flexural strength test determines the ability of concrete to counter bending loads and was performed as per the ASTM C78/C78M-18  standard1/2) for the concrete mixes containing different content of NGP inclusion has a lesser value than the control mixed. It was observed that the percentage decrease in sorptivity was maximum for a mix containing 5% NGPs, which was reported to be 32.3%, and the minimum reduction was noted to be 6.4% of mix prepared with 0.5% NGPs, compared to the control mix. Ahmad, F. [Sorptivity measures the capacity of porous media to absorb water through capillary actions. The sorptivity coefficient of concrete provides a good measure of the durability of concrete, as many chemicals can penetrate the microstructure of concrete from soils and water by capillary actions. Materials with a high sorptivity coefficient are more susceptible to degradation, which reduces their toughness. The sorptivity coefficient is evaluated by determining the increase in weight of the sample caused by the water absorption (only through one surface of the specimen). The amount of water absorbed by the samples having different dosages of NGPs  through capillary rise per unit area is shown in hmad, F. ,53,56. Thmad, F. .The UPV is a durability test used to determine the uniformity, quality, and consistency of concrete. It determines a concrete mix’s compactness, homogeneity, and imperfections, such as voids and cracks. The concrete homogeneity was examined from whether the pulse wave passes at a higher or lower velocity through the specimen ,58. WhenWater absorption is a durability test conducted to measure the amount of water absorbed by cementitious composites. This absorbed water adversely affects the durability behavior of the resulting cementitious materials. Water acts as a medium for the ingression of aggressive agents, such as chloride, sulfate, etc., by capillary actions. In this study, different dosages of NGPs were added to the concrete composites, which showed a substantial decrement in water absorption, as shown in It was observed that the control sample (OPC0NGP) without NGP intrusion indicated a maximum water absorption by an amount of 2.95% at the 28-day curing period. OPC5NGP showed the lowest water absorption of 0.77%, whereas OPC0.5NGP revealed the maximum water absorption of 2.43% compared to the control sample without nano intrusion. Percentage reductions in water absorption of NGP-intruded cementitious composites were reported to be 17.62%, 35.93%, 56.61%, and 73.89% for OPC0.5NGP, OPC1.5NGP, OPC3NGP, and OPC5NGP, respectively, compared to the control mix (OPC0NGP) without NGP intrusion. The influence of NGPs upon the water absorption of concrete is consistent with the findings of previously published studies ,54,61,62An external sulfate attack test was performed to check the resistance of concrete against sulfate. A sulfate attack adversely affects the durability properties of concrete. Sulfate from external sources, such as soil, seawater, underground water, or swamp water reacts with hydration compounds, i.e., calcium aluminate and calcium hydroxide hydrates, and, as a result, expansive delayed ettringite is formed. Expansive ettringite formation causes an increase in solid volume, which results in cracking, expansion, mass loss, and disintegration of concrete ,64. The A maximum decrease in compressive strength of about 37.43% was reported in the control formulation, without nano intrusions. In control formulation (OPC0NGP), compressive strength of 28-day cured concrete reduced from 33.5 to 20.96 MPa after submersion of the specimen for 28 days in a sodium sulfate solution. This decrement in strength is due to the susceptibility of the control specimens to admittance of sulfate ions from the solution, and no reinforcement is there at the nano level that can obstruct the stresses employed by expansive ettringite; hence, resulting in loss of high strength. The ingression of sulfate ions into the control concrete specimen can be attributed to its least resistance against waster absorptivity .OPC5NGP showed maximum resistance against an external sulfate attack, and only a 9.22% reduction in strength loss was observed. In other mixes, such as OPC0.5NGP, OPC1.5NGP, and OPC3NGP, approximately 29.4%, 23.38%, and 16.57% strength reductions were reported, respectively. It was observed that concrete samples containing different dosages of NGPs have less percentage reductions in compressive strength, with reference to the control sample without nano intrusion. This decrement in strength reduction is owed to the presence of NGPs. The existence of NGPs decreases water absorption, as shown in Microstructural analysis were carried out to analyze the effects of NGPs at the nano level. In this study, a microstructural investigation was carried for mix containing 5% NGPs because of its extensive performance as a reinforcing agent, acting as a pore refining and densifying agent at the nano level. The SEM and EDX analysis were carried out in the “Material characterization lab-USPCAS-E NUST, Pakistan”. These are the general features of the SEM device used: VEGA3 TESKAN, resolving power (max): 2.3 nm, energy: 30 KV, and magnification (max): 300,000×); whereas the EDX device: EDX with SEM (JSM910) INSA200/Oxford instruments, U.K, and analysis range Boron to Uranium. The samples were examined via several magnification ranges, i.e., 50 μm, 5 μm, 1 μm, and 500 nm near ITZ. The SEM micrographs of specimens containing 5% NGPs are shown in This study examined the effects of NGPs on the fresh and hardened properties of concrete, including workability, air content, hardened density, compressive strength, split tensile strength, and flexural strength. Furthermore, durability properties of nano-reinforced concrete, such as sorptivity coefficient, UPV, water absorption, and external sulfate attacks, were explored. Based on the findings, the following conclusions can be deducted.The workability of NGP-modified concrete decreased as compared to the control sample due to the fine particle size and large surface area of NGPs. The decreasing trend in workability was found with increasing NGP dosages. Moreover, a decrement in percentage air content was observed with increasing dosages of NGPs. The concrete mix with 5% NGPs indicated the maximum reduction in air content, about 33.83%, with reference to the control mix.The hardened density of concrete increased with the rise in dosages of NGPs. The maximum increase in density of about 11.46% was observed for the sample containing 5% NGPs, with reference to the control mix. The compressive and split tensile strength of the concrete also increased. Compressive and tensile strength values increased in the range of 5–38.5% and 8.25–31.6%, respectively. This is because of the intrusion of NGPs, which strengthened the concrete composites at the nano level; increasing the density and hardness of concrete make NGP a promising reinforcing agent in cementitious composites. In addition, the mix containing 5% NGP intrusion showed a maximum enhancement in flexural strength of 44.34%.The incorporation of NGPs significantly reduced the sorptivity value (32.3% reduction for 5% NGPs intrusion) due to its filler effect. The values of UPV also improved. The maximum increase in the UPV value was from 3890 m/s to 4182 m/s at 5% intrusion of NGPs.The addition of NGPs in concrete composites proved effective at reducing water absorption. The mix with 5% NGPs showed a 73.9% reduction in water absorption compared to the control mix.The current study focused on the physical and mechanical characteristics of NGP-incorporated concrete. The NGPs can potentially be used to achieve high-density concrete with improved performance for sustainability and nuclear infrastructure. It is strongly recommended to see the influence of NGPs in the freeze–thaw cycles, alkali–silica reaction, salt scaling, and carbonation; the optimum dosage levels of NGPs for future implementations; the effects of NGPs on drying shrinkage of cementitious composites; the influence of different water to cement (W/C) ratios on NGP-modified concrete composites; NGP-modified concrete at low and high W/C ratios; statistical analyses of NGP-incorporated concrete specimens to analyze the deviation from the experimental results.The paradigm shift in regression models using machine learning significantly contributes to solving engineering problems ,69,70,71


Understanding stray light (SL) is a crucial aspect in the development of high-end optical instruments, for instance space telescopes. As it drives image quality, SL must be controlled by design and characterized experimentally. However, conventional SL characterization methods are limited as they do not provide information on its origins. The problem is complex due to the diversity of light interaction processes with surfaces, creating various SL contributors. Therefore, when SL level is higher than expected, it can be difficult to determine how to improve the system. We demonstrate a new approach, ultrafast time-of-flight SL characterization, where a pulsed laser source and a streak camera are used to record individually SL contributors which travel with a specific optical path length. Furthermore, the optical path length offers a means of identification to determine its origin. We demonstrate this method in an imaging system, measuring and identifying individual ghosts and scattering components. We then show how it can be used to reverse-engineer the instrument SL origins. SL can appear through partial reflection between the lens interfaces (ghosts)  reaches the detector6. Afterwards, SL is characterized experimentally to verify the performance. This is done by illuminating the system with a point-like source, returning an image of the different SL components superposed with the nominal image. Such process does not allow to decompose and retrieve the origin of the individual SL components. Therefore, if the measured SL is higher than expected, improvement actions are limited5. The inability to decompose and identify SL contributors is a major drawback for engineers who can only guess SL origins and use a trial and error approach for improving a system. This is highly time consuming and sometimes no solution is found.For these reasons, SL mitigation is inherent of every steps in instruments development. Ray-tracing allows prediction of SL paths, which are then suppressed or attenuated with baffles or coatingsIn this work, we demonstrate how ultrafast time-of-flight imaging (ToF) offers a new paradigm in SL characterization. As SL components have different optical path lengths (OPL), illumination with a pulsed laser beam and detection with an ultrafast camera allows to characterize them separately. Furthermore, the OPL offers a means of identification to determine their origin. With these capabilities, major limitations of current methods will be overcome, paving the way to new possibilities in the development of space optical instruments. In the demanding case of refractive assemblies, SL components with typical millimeter path length differences should be made observable with temporal resolution of a few picoseconds. High spatial resolution is also desired for unequivocal characterization of SL.8. Latest works with SPADs also involve occluded scene reconstruction11. Nevertheless, the reported temporal resolution (a few tens of picoseconds) remains too small for our application. An alternative is the use of streak cameras which allow visualizing time arrival of photons from the scene along the unidimensional direction of the streak tube entrance slit12. Various studies showed their use as a framing camera to allow single shot direct imaging of 3D scenes with a few ps of temporal resolution but the spatial resolution remains limited17. In our application, the scene is static and repeated pulsed illumination with a scanning of the slit allows to reconstruct images with high spatial and temporal resolutions. In this frame, considerable breakthroughs in 3D scene reconstructions by ToF imaging were made by MIT23. Before reaching the streak tube, a pulsed laser beam travelling through a scene interacts with objects through a variety of processes: specular and diffuse reflection (sometimes multiple times), subsurface interactions, or diffraction. Suitable processing allows applications such as observing occluded objects19, observing light travelling through complex scenes21, retrieving three-dimensional reflectance function of surfaces on very-wide angles22, or more recently multi-zoom and multi-spectral imaging23. The principle of ToF imaging with streak cameras can be understood as tagging temporal arrival of photons in a spatial dimension. Another possibility is to use white light pulses to illuminate the scene and then to tag arrival of photons spectrally, as demonstrated by Goda et al24 and later by Nakagawa et al25. This method is not relevant for our application since SL is spectrally dependent and its characterization is envisaged at a specific wavelength. Finally, a method called light-in-flight holography, popularized by Abramson27 allows tagging temporal photons through spatial multiplexing in holographic plates29, or more recently via digital hologram recording30, making use of low-coherence light pulses. Despite the interesting spatial and temporal resolution (up to ~ 100 fs30), holography seems unsuitable for recording multiple SL components over a large dynamic range.Recent improvements of 2D fast sensors based on single-photon avalanche diodes (SPADs) make them an interesting candidate technology for ultrafast ToF imaging, with increasing numbers of pixels21. In this paper, ultrafast ToF imaging at ps-scale for retrieving unequivocally and characterizing SL components in an optical system, whether they are generated by ghost reflections or scattering. The different contributors are isolated and reverse engineering of the instrument properties is achieved.Therefore, the method that appeared the most suited for our application was that of ultrafast ToF imaging based on streak camerasa to f. The instrument is illuminated at a small field angle along x (0.73°), producing a non-rotationally symmetrical stray light profile at the detector. A streak camera . With a typical 100 fs laser pulse duration, a temporal resolution of a few ps is reached.The experimental setup is shown in Fig. era Fig. a is placx (a), acquiring streak images I with steps dx of 100 µm (b). The different images are then recombined into a temporal sequence of 2D maps I (c). A movie of the SL reaching the detector is obtained. The map I at time tl shows the nominal image (focused spot for an object at infinity) while at time tm and tn we get images of different SL contributors.The principle of the temporal SL characterization is shown in Fig. x0,y0), surrounded by several SL ghosts decentered along x (because of the 0.73° field angle) and by others widespread over the focal plane.In order to understand our results, Fig. I with the slit at 700 µm from x0. It presents several features at different times, with different irradiances and sizes. The features present a curvature if all the rays in their underlying SL path do not reach the focal plane simultaneously. While the nominal spot arrives at time t = 0 ps, the streak image is acquired with the slit slightly beside. Indeed, the dynamic range of the camera is insufficient to display simultaneously the nominal spot and SL. Close to 0 ps, scattering due to surface roughness of the lenses creates SL over the entire slit, with an irradiance decreasing away from y0. The most significant ghost paths usually involve only two partial reflections (second level ghosts). In on-axis systems, there are α = N(N − 1)/2 paths of that sort1, where N is the number of refractive interfaces. Here, α = 15 but only 14 of them are easily identified by the OPL on the streak image. Mapping of the features to their origin is done by comparing their time of arrival with the theoretical OPL of each SL path, predicted by ray tracing. The missing path is the ghost ef, occurring inside the optical window. The latter creates a slightly defocused ghost around the nominal image, which is not measured as the slit is too far from x0. At around 150 ps, a ring is present  and corresponds to scattering on the housing. The streak image can also present much weaker features from paths involving more than two partial reflections . In our setup, such higher-level ghosts can be generated either by the instrument under test or by the streak camera relay optics itself. Usually, these are negligible compared to second level ghosts.Figure I of the SL movie at different specific times. A black vertical stripe is present at the center because the streak image I is not measured at x0, as explained above. The first (upper left) figure of the series is at t = 0 ps. It shows an intense light around the image center at  as well as a quite uniform irradiance pattern all around. This is the result of a first SL component attributed to scattering due to lens roughness. This SL does not experience any delay due to secondary reflections. The other figures, obtained between t = 24 ps and 132 ps, show the decomposition of various ghosts. In some cases, different ghosts have similar optical path lengths and reach the detector simultaneously. It is the case at t = 35 ps where dc and fd are superposed while easily distinguishable . On the contrary, at t = 59 ps, ghosts cb and ec are superposed and indistinguishable. Another remarkable pattern is the one shown at t = 151 ps: a large external ring is visible and is likely to arise from the scattering by the optical instrument housing. Summing the images I for all times t, we obtain the total irradiance at focal plane as shown in Fig. The full SL movie reconstituted by the streak images is available as supplementary material. In Fig. x due to scattering on the lens roughness at t = 0 ps. The fact that the scattered light reaches the focal plane at a time which is function of x, as shown by the curvature of the scatter feature in Fig. t = 0 ps in . Reverse engineering was performed to estimate the bidirectional scattering distribution function (BSDF) of the lenses, initially unknown. For that, we start with an initial guess for the BSDF and compute the corresponding SL profile at the focal plane. Then, we iteratively adapt the model until it fits the experiment. A Harvey model BSDF31 with 2.04 nm effective roughness for each lens interface yields ray tracing results similar to the experiment.The last step of our work was to consider the use of this measurement method to understand the origin of SL (ghost or scattering). Furthermore, we meant to determine whether these observations match with ray tracing simulations and scattering modeling, as a prelude to reverse engineering the SL origin. Figure x for ghost eb (t = 122 ps). The continuous black line shows the theoretical profile, obtained by ray tracing the specular reflections at lens interfaces. With uncoated lenses, the reflectivity is modeled by Fresnel equations, for which the results are in excellent agreement. In addition, the experimental profile presents a signal around the ghost. Usually neglected in simulations, this comes from the fact that ghost rays are partly scattered. Performing the ray-tracing with the BSDF model derived above, this behavior is reproduced, as shown by the black dotted lines.Figure Ultrafast ToF SL characterization is demonstrated in the case of an imaging instrument. We were able to isolate and identify ghosts, scattering from lens roughness and scattering from the housing. Hence, individual SL contributors can be compared with the theoretical model. Reverse engineering can be performed to retrieve information on optical properties, as it was carried out in this study with the scattering from lens roughness. With raw lenses, partial reflections are modeled with Fresnel equations and ghosts are therefore predicted accurately. With coated lenses, the comparison between measurement and theory could serve as a means to verify coating performances. Similarly, for SL due to scattering on non-optical surfaces, comparison between experiment and theory could emphasize an underperforming black surface treatment. Practically, this tells which surface and associated optical properties should be improved to reduce the SL to the expected level.For optical instrument characterization, this method significantly improves the understanding of the SL. It is not only the total SL that can be measured and compared to performance requirement. In fact, because the different contributors are accessed separately, they are identified and can be compared to their respective expected level. Afterward, the SL model can be adapted accordingly. In the case where the total SL is larger than expected, this allows to identify the problematic contributor and to act upon it. When an unexpected feature is present, the optical path length is used to reverse engineer its origin. While this is not a trivial task to perform, the OPL is a useful clue to determine the surfaces involved in a SL path. For example, a feature with a small OPL necessarily involves surfaces close to each other, and reversely. Then, once the origin is found, classical SL control methods can be applied, for example by adding a baffle. Finally, it can happen that some of the detected SL comes from the measurement facility . If a feature is identified as such, it can be eliminated from the measurement by removing the signal at the corresponding time. For example, if a SL path with an OPL significantly larger than any dimension in the optical system under test is detected, it is likely that it is an external SL path.Our method is applicable to a broad range of situations. In off-axis instruments, straight shots can occur when direct light reaches the detector without following the sequence of elements intended by the design. For instance, in a multi-mirrors system, this occurs when light is reflected on the first mirror directly toward the detector. In that case the SL path has an OPL shorter than the nominal image, therefore arriving sooner at the detector. In the case of instruments with diffractive elements, this method could also identify SL coming from unwanted diffraction orders. In each case, the knowledge of the origin is used as a baseline to determine the actions to undertake.32) allows to build high performing compact instruments with a reduced number of optical elements. In that case, the ToF measurement is not necessarily harder to interpret, regardless of the complexity of individual optical elements.In this paper, the method is applied to a relatively simple optical system. However, it can be generalized to more complex systems as well. In the case of instruments with a larger number of optical elements, ToF measurements could emphasize a larger number of peaks as the number of possible SL paths is increased too. This can lead to ambiguities if multiple SL paths have an identical OPL, hence advanced mathematical tools will need to be developed. Nevertheless, SL features with the same OPL could be distinguished spatially if they are located on different areas of the focal plane. Finally, recent advances in optical design , smaller temporal resolution can be sufficient, opening the possibility to use other sensors such as SPADsBesides SL characterization of optical instruments, another application of this method concerns the validation and improvement of traditional SL measurement facilities. When an instrument is to be tested, it requires a facility with very low SL. Otherwise, the SL measurement may contain contributions from the facility itself which cannot be distinguished with traditional methods. This happens frequently, in particular because SL facilities are usually validated by simulations only. Hence, this method would be particularly useful as it would allow for characterization of the SL in a facility and derivation of its origin, therefore contributing to improving it. Practically this could be envisaged by replacing the source of the facility by a pulsed laser and by placing the ultrafast sensor in the way of the output beam.To conclude, ToF imaging with high temporal resolution offers new possibilities for SL characterization, in-line with the trend of high-end instruments requiring better SL control. By enabling decomposition and identification of SL components with the OPL, it breaks the status quo of conventional methods whose purpose is only verification. It solves a decades-old problem and offers the ultimate characterization and understanding of SL properties in optical instruments.The source is a Titanium Sapphire 780 nm pulsed laser with a 400 mW optical power (Tsunami from Spectra-Physics). It has a repetition rate of 81.2 MHz and a pulse duration of 100 fs.Optoscope SC-10 from the company Optronis GmbH, set in synchroscan mode. The streak tube is equipped with an S25 photocathode with quantum efficiency of 12% at a wavelength of 780 nm. The slit is adjusted with a width of 60 µm along x, and a length of 13 mm along y. The sampling along the slit is of 14.47 µm and the temporal behavior is measured with a sampling of 210 fs per pixel.The streak camera is the R1 = 24.02 mm and R2 = − 134.6 mm; thickness e = 6.5 mm), followed by a plano convex lens  and an optical window (e = 1 mm). The different elements are made of N-BK7, uncoated and with a clear aperture of 25.4 mm. They are mechanically supported by spacers inside a lens tube of respectively 8 mm and 4 mm. The optical combination has an effective focal length of 63.3 mm and a back focal length of 33.2 mm.The optical instrument under test Fig. x-direction is performed by translating the tested instrument while the camera and the slit remain in place. The reason is that the instrument is much lighter than the camera. To avoid vignetting of the SL features, the input beam must have a sufficiently large diameter so that the instrument can be uniformly illuminated by the beam. Optical densities are placed in the way of the beam to adjust the input power for the signal to be below saturation of the streak camera. This enables the measurement of SL over a large dynamic range. The different acquisitions performed during the scan are then recombined into a 2D image.The collimator has a diameter of 100 mm and is placed at 1000 mm from the optical instrument under test. The scan along the 9. Indeed, in our experimental conditions , the total number of photons sent is in the range of 1.6 × 1019. Consequently, the maximum achievable dynamic can be very high. For example, a feature at dynamic of 1015 would mean that about 1000 photons are measured at every pixel, considering the quantum efficiency. This is much higher than the noise of a typical S25 photocathode, which is of the order of a few tens of photons per cm2∙s in photon counting mode.In the experiments presented here, we were not limited by photon-efficiency and we demonstrated measurements of SL features over a dynamic of 1031 whose profile is given by Eq. (b, s and L. Equation (b = 55.395, s = - 1.55 and L = 0.00078, corresponding to an effective roughness of 2.04 nm.Lens roughness BSDF is fitted with a Harvey modelentclass1pt{minimaSupplementary Video 1.Supplementary Information 1.