Drosophila melanogaster. However, it remains less clear in lepidopteran insects. This study characterized the apoptotic protease activating factor-1 (Apaf-1) from Spodoptera litura. The results showed that S. litura Apaf-1 (Sl-Apaf-1) is similar to the mammalian Apaf-1. Sl-Apaf-1 consists of a caspase recruitment domain (CARD), as well as nucleotide-binding and oligomerization domain (NOD) and the C-terminal WD40-repeat domain (WD), and interacts with Sl-caspase-5 . The activated Sl-caspase-5 can cleave Sl-procaspase-1 , which directly causes apoptosis. The apoptosis signal pathway is conserved between lepidopteran insects and mammals.Apoptosis plays an important role in both the development of lepidopteran insects and the elimination of cells. The apoptosis signal pathways are well documented in mammals and Spodoptera litura, named Sl-Apaf-1. Sl-Apaf-1 contains three domains: a CARD domain, as well as NOD and WD motifs, and is very similar to mammalian Apaf-1. Interference of Sl-apaf-1 expression in SL-1 cells blocked apoptosis induced by actinomycin D. Overexpression of Sl-apaf-1 significantly enhances apoptosis induced by actinomycin D in Sf9/SL-1/U2OS cells, suggesting that the function of Sl-Apaf-1 is evolutionarily conserved. Furthermore, Sl-Apaf-1 could interact with Sl-caspase-5  and yielded a binding affinity of 1.37 × 106 M–1 according isothermal titration calorimetry assay. Initiator caspase (procaspase-5) of S. litura could be activated by Sl-Apaf-1 (without WD motif) in vitro, and the activated Sl-caspase-5 could cleave Sl-procaspase-1 , which directly caused apoptosis. This study demonstrates the key role of Sl-Apaf-1 in the apoptosis pathway, suggesting that the apoptosis pathway in Lepidopteran insects and mammals is conserved.Apoptotic protease activating factor-1 (Apaf-1) is an adaptor molecule, essential for activating initiator caspase and downstream effector caspases, which directly cause apoptosis. In fruit flies, nematodes, and mammals, Apaf-1 has been extensively studied. However, the structure and function of Apaf-1 in Lepidoptera remain unclear. This study identified a novel Apaf-1 from  Caenorbabditis elegans CED4 [Plutella xylostella and Bombyx mori have been cloned [Apoptosis is a highly conserved mechanism by which eukaryotic cells commit suicide. This mechanism plays a critical role in tissue development, tissue homeostasis, host defense, and the elimination of unwanted cells in multicellular organisms ,2. Apoptans CED4 . It contans CED4 . Both thans CED4 . Brieflyans CED4 , and theans CED4 . The Apan cloned ,15, but Spodoptera frugiperda, Spodoptera exigua, Spodoptera litura, and Bombyx mori), and studies from different laboratories have shown that cytochrome c plays an essential role during apoptosis [Spodoptera littoralis) for Sl-caspase-1 [S. frugiperda, and recombinant Sf-caspase-5 can cause autocatalytic cleavage at position D340 and cleaves the Sf-caspase-1 [Apoptosis also plays an important role in insect physiology, e.g., development, tissue homeostasis, DNA damage response, and immune response . Evidencpoptosis ,24,25,26aspase-1 ,28. Caspaspase-1 . Howeverapaf-1 homolog gene from S. litura and designated it Sl-apaf-1. The function of Sl-Apaf-1 during apoptosis was studied through RNA interference and over-expression assay. Protein expression and biochemical analysis were also performed to further characterize Sl-Apaf-1. The results indicate that Sl-Apaf-1 plays an important role in apoptosis, and provide useful information for the study and utilization of the apoptosis pathway in Lepidoptera.This study identified an S. litura  was obtained from the Institute of Entomology, Sun Yat-sen University, Guangzhou, Guangdong, China. Sf9  and U2OS (Homo sapiens bone osteosarcoma cells) cells were maintained in the laboratory. The insect cell lines were cultivated in Grace’s Insect Medium  supplemented with 8% fetal bovine serum (Gibco), 100 U/mL penicillin and 100 µg/mL streptomycin (Gibco) at 28 °C. U2OS cells were grown in Dulbecco’s Modified Eagle Medium  supplemented with 10% fetal bovine serum, 100 U/mL penicillin, and 100 µg/mL streptomycin (Gibco) at 37 °C and 5% CO2. β-Actin Rabbit mAb (#12620) and Anti-rabbit IgG, HRP-linked antibody (#7074) were purchased from Cell Signaling Technology . Anti-Sf-caspase-1 antiserum was provided by Paul Friesen [Cell line SL-1, which originated from an embryo of Apaf-1 from B. mori, Manduca sexta, and Danaus plexippus was performed by Clustal W software version 2.0 . Highly conserved nucleotide sequences were used to design and synthesize specific primers . The remaining cDNA sequences of Sl-apaf-1 were amplified by 3′- and 5′-RACE using the Smart RACE cDNA amplification kits . The experiment was performed according to the recommendation of the manufacturer, and the gene specific primers (GSP) are listed in l-apaf-1 was amplified with Phusion® High-Fidelity DNA Polymerase . PCR was performed under the following conditions: pre-denaturation at 98 °C for 30 s; then, 30 cycles of heating to 98 °C for 10 s, cooling to 60 °C for 15 s, and re-heating to 72 °C for 120 s; followed by a final 5 min cycle at 72 °C. The PCR product was separated using gel electrophoresis (0.7% agarose), and then recovered and cloned into the pGEM-T vector  by TA clones. The recombinant plasmid (pGEM-Sl-Apaf-1) was then transformed into competent Escherichia coli DH5α cells and positive clones were screened on an LB agar plate (with 100 μg/mL ampicillin) for plasmid extraction and sequence verification.Sequence alignment of putative  primers . A 778 bSl-apaf-1 from the pGEM-Sl-Apaf-1 vector. The ligation product (pEGFP-N1–Sl-Apaf-1) was constructed by subcloning the digested Sl-apaf-1 CDS into a pEFGP-N1 vector. To express Sl-Apaf-1 in insect cells, the pIE2-Sl-Apaf-1-EGFP vector was constructed by replacing the CMV promoter in the pEGFP-N1–Sl-Apaf-1 vector with the OpIE2 promoter from the pIZTV5-His vector.The restriction endonucleases Xho I and Pst I were used to digest and isolate the CDS of https://zhanglab.ccmb.med.umich.edu/I-TASSER/) was used to predict the tertiary structures of the putative Sl-Apaf-1 protein [http://www.pymol.org/) was used to visualize the protein structure, and the subdomain schema was made by DOG software . For phylogenetic analysis, 10 homologous Apaf-1 proteins sequences were download from GenBank. MEGA version 7.0.21 was used to construct the tree  [The I-Tasser server ( protein . PyMOL seletion) .5 cells/well and were cultured overnight. Cells in each well were transfected with 2 μg of plasmid and 8 μL of cellfectin reagent II  according to the manufacturer’s protocol. The cells were continuously cultured for 48 h for detection. For RNA interference, siRNA sequences that target Sl-apaf-1 mRNA were designed  were amplified using specific primers  is a well-known clinical antitumor drug that can induce the apoptosis of HepG2 through the Fas- and mitochondria-mediated apoptosis pathway . It can 2PO4, 1.44 g Na2HPO4, 8 g NaCl, and 0.2 g KCl in 1 L water, at pH 7.4), and fixed with 40% paraformaldehyde for 10 min. Then, cells were washed with PBS once, and stained with 0.1 μg/mL 4′,6-diamidino-2-phenylindole (DAPI) in PBS for 10 min. After staining, the cells were washed three times with PBS, and samples were mounted with glycerol/PBS (4:1). Then, cells were observed under a Leica TCS SP5 inverted confocal laser scanning microscope equipped with an argon–helium–neon laser light source .The transfected cells were digested and replanted in 6-well plates with cover glass. After the cells had adhered to the cover glass, they were washed with PBS buffer once . Then, the stained cells were analyzed on a BD Coulter Epics flow cytometer .SL-1 cells were transfected with pIE2-SlApaf-1-EGFP plasmid or siRNA targeting Sl-caspase-1 and Sl-caspase-5 were also amplified with specific primers  and Sl-caspase5  were amplified with specified primers  and clon primers  and clonE. coli BL21(DE3), and the strain was cultured in 3.2 L Luria-broth (LB) media with 100 μg/mL ampicillin at 37 °C for 3 h until the OD600 value reached 1.0, then, induced by 0.4 mM isopropyl-1-thio-D-galactopyranoside (IPTG) at 28 °C for 24 h. To prevent procaspase-5 auto-activity, E. coli BL21 with caspase-5 expression vector was induced with IPTG at 28 °C for only 45 min. The cells were harvested, flash frozen in liquid nitrogen, and stored at −80 °C.The expression vector was transferred into E. coli cells were washed and re-suspended in 50 mL binding buffer . The bacterial cells were lysed with an ultra-high-pressure homogenizer at 1.2 × 109 Pa three times at 4 °C. The cell lysate was centrifuged at 20,000× g for about 1 h to remove cellular debris. The fusion protein was purified by Ni-affinity resin  with elution buffer . The proteins were further purified on a superdex 16/60 200HR gel filtration column  with HEPES buffer . Purified proteins were then lyophilized and stored at −80 °C.For the purification of the His tagged protein, The reaction was conducted at 28 °C for 30 min with 10 nmol dATP, 0.5 μg purified Sl-proaspase-5, 2 μg purified Af627, and 10 ug purified Sl-procaspase-1 (C178A) protein in the reaction buffer  . The reaThe concentration of the Sl-Apaf-1-CARD protein was adjusted to 50 µM and the Sl-caspase-5-CARD protein was adjusted to 450 µM with reaction buffer. The reaction buffer consisted of HEPES 10 mM, NaCl 100 mM, DTT 2 mM, at pH 7.4. The isothermal titration calorimetry assay (ITC) was performed with a VP-ITC isothermal titration calorimeter . Parameters include: total injection 20, cell temperature 20 °C, reference power 5, initial delay 60 s, and stirring speed 500 RPM. The data were analyzed using ORIGIN 7.0 .® software version 6.0 . Data are expressed as the means ± SD. The results were considered statistically significant if p < 0.05 was obtained by the Student’s t-test.Statistical analyses were performed using GraphPad PRISMSl-apaf-1: MT793718; Sl-caspase-1: JN794535; Sl-caspase-5: JQ768051.S. litura Apaf-1 was 5221 bp (termed as Sl-apaf-1) containing a 4626 bp open reading frame. The sequence encoded 1542 amino acids, a 0.2 kb untranslated region at the 5′ end, and a 0.4 kb untranslated region at the 3′ end (The complete cDNA sequence of e 3′ end . The dede 3′ end A. The prD. melanogaster and C. elegans (CED4) were located on another large branch  was expressed and purified. This fragment contains a CARD domain and a NOD domain (627 amino acids). Sl-procaspase-5 , and Sl-procaspase-1  in E. coli system. The binding interaction between Sl-Apaf-1-CARD and Sl-caspase-5-CARD was determined by ITC titration. The ITC data showed that Sl-Apaf-1-CARD and Sl-caspase-5-CARD had a binding affinity of 1.28 × 106 ± 0.34 × 106 M–1, a ∆H of −1.55 × 104 ± 0.24 × 104 kcal/mol, and a ∆S of −24.8 ± 8.6 cal/mol/deg, which were appropriate values. The stoichiometry of the two proteins was 1, which is consistent with the known binding model in mammals  and Sl-caspase-5 (Sl-caspase-5-CARD) were expressed and purified with the  mammals B. ClearlTo determine the functional conservatism of Sl-Apaf-1, Sl-Apaf-1 was over-expressed in Lepidopteran cells (Sf9) and mammalian cells (U2OS). FACS assay of transfected cells was performed after treatment with 500 ng/mL Act D for 4 h. The results showed that overexpression of Sl-Apaf-1 significantly promoted apoptosis in both cells. For both, the apoptosis rate was promoted by over 20% (22.02% for Sf9 cells and 32.33% for U2OS cells) when compared with EGFP-overexpressing cells A,B.Drosophila [apaf-1 in S. litura, named Sl-apaf-1, which represents a new member of the Apaf-1 family. Apaf-1 from lepidopteran and mammals was located on the same large branch of the phylogenetic tree and sequence analysis showed that the Sl-Apaf-1 contains three domains: a CARD domain, as well as NOD and WD motifs. It is likely that Sl-Apaf-1 exerts a conservative function during apoptosis (l-apaf-1 was silenced by RNAi, which decreased the apoptosis level induced by Act D, and Sl-caspase-1 cleavage was also inhibited in the cells (Apaf-1-mediated apoptosis signaling transduction has been well-characterized in mammalian cells . Althougosophila ,36,37,38poptosis . To detehe cells . Moreovehe cells . These rDrosophila, studies have demonstrated that Dark plays a central role during apoptosis and appears to act independent of cytochrome c [S. litura cells. Furthermore, Sl-Apaf-1 could not promote apoptosis if it was overexpressed in Sf9 cells without stimuli. It is likely that Sl-Apaf-1 functions in a similar way with mammalian Apaf-1 during apoptosis, and cytochrome c is an important factor for the activation of Sl-Apaf-1. The interactions between Apaf-1 and cytochrome c were tested, and they could co-localize in human U2OS cells by co-transfection with plasmids expressing Sl-Apaf-1 or S. litura cytochrome c with fluorescent biological labels (In the mitochondria-mediated apoptosis pathway, it is clear that Apaf-1 is an adaptor molecule that interacts with cytochrome c through its WD-40 repeats, while it recruits and activates procaspase-9 through its CARD. In chrome c ,38. In tchrome c , the rell labels . HoweverS. frugiperda, B. mori, and Lymantria dispar [As an adaptor or activator, in mammals, Apaf-1 stimulates caspase-9 activation through the CARD domain and formed a 1:1 complex between the CARD domains of Apaf-1 and caspase 9 ,39. Intea dispar ,40,41. Fapaf-1 homolog gene from S. litura was identified and designated as Sl-apaf-1. Sl-Apaf-1 can bind and activate Sl-caspase-5. These results indicate that Sl-Apaf-1 plays a key role in apoptosis, suggesting that the apoptosis pathway is conserved between Lepidopteran insects and mammals.An


The repairs of building structures are inevitable and indispensable. Repairs are used to restore or maintain the usability of existing facilities, often contributing to the extension of their expected service life, increasing the sustainability of building resources. Given that conservation rules are observed, repairs are also used to save monuments. The concept of repair durability brings to the foreground the durability of the repaired structure (after repair): what service life has been obtained/recovered as a result of the repair. Based on the available data (limited set), a generalised distribution function of repair durability was developed, with a disappointing course. This, however, applies (necessarily) to the past. Significant progress was shown to have been achieved in the theoretical and technical fundamentals of technical repair measures. In this situation, a prognostic distribution function was also designed for future repairs according to EN 1504. A rule of thumb called estimating concrete repair durability, CRD was proposed. The risk associated with estimating the durability of repairs was indicated. A reason for optimism is that proactive monitoring of the condition of the structure and, consequently, management of the repair strategy allows to reach the designed life of the structure. Durability is the building structure’s ability to remain in a functional condition, expressed in time units. Repair means eliminating defects, while a defect is a condition which requires interference. The conviction that concrete structures are durable is common and justified. Concrete structures are designed to provide at least 50 years of service, while public and monumental buildings are intended to last even longer. The service life of concrete structures is defined in “EN 206: Concrete—Requirements, Properties, Production and Compliance”  as a perThe purpose of the paper is to present the possibilities of estimating concrete repair durability, CRD in reference to the state of knowledge and engineering, and to indicate how a designed service life can be ensured through proactive management of the repair strategy. Historical information has been shown to be key to understanding several issues that the “technological” engineering approach leaves unresolved, and science is the last aid in saving some valuable buildings. In the paper, we focus particularly on the question of whether, in the current state-of-the-art, we can assess how many years, as a result of repairs, we will extend the life of the structure.The inevitability of repairs is subject to the random nature of impacts on the structure, including: hitting, overloading, explosion etc., as well as extraordinary weather impacts . These are unique and sudden instances. The inevitability of repairs is also determined thermodynamically, by the structure striving to achieve the condition of energy minimum and entropy increase, which can be confirmed by different corrosion processes, which are aggravated in certain conditions . Past experiences also indicate the indispensability of repairs. Six out of the seven wonders of the ancient world, i.e., the Hanging Gardens of Babylon (600 BCE), the Temple of Artemis at Ephesus 550 BCE), the Statue of Zeus at Olympia (435 BCE), the Mausoleum of Halicarnassus (352 BCE), the Colossus of Rhodes (281 BCE) and the Lighthouse of Alexandria (285 BCE) were severely damaged as a result of earthquakes and fires [50 BCE, tAmong twenty monuments aged from several thousand to several dozen years  all but Repairs are an inevitable and indispensable necessity. Given that conservation rules are observed, repairs are also used to save monuments, but first and foremost they help to restore or maintain the usability of existing structures. Consequently, repairs restore or extend expected durability. Due to the fact, that stone/brick skeletons have a much longer tradition in construction than that of Portland cement concrete, the historical approach to structural repairs is also much deeper for masonry structures.In this context, it is worth recalling the very significant history of St. Peter’s dome repairs . In 1742Overall, in construction, the linkage between theory and practice is of great importance.In the field of repair, it may happen at any moment that practice triumphs over modern theory. It is sufficient to say that concrete repair has been performed since the introduction of concrete into construction practice , but the standard for concrete repair was established in USA through the ACI-1999 Concrete Repair Manual, and in Europe in 2004–2013 according to the volumes of European Standards EN 1504.1-10.Many valuable lessons can be learned from these studies, which also apply to our topic. They can be defined as follows:Under some conditions, the repairs are also intended to increase the sustainability of building resources . FurtherAuthority in the field of concrete A.M. Neville in 1987 asked the question: Why do we have problems with the durability of concrete? . Apart fThe postulate of effective repair entails the requirement of repair durability. Data related to practice in this area are scarce. A building structure repair—contrary to its construction—entails certain discretion, arising from the professional embarrassment experienced in reference to the non-fulfilment of the common conviction of durability. The unwillingness to reveal information about the need to make repairs is additionally aggravated by the fact that 90% of the causes of repairs are workmanship and design errors  . “A repaLet us illustrate these deliberations with an example: the Prince Józef Poniatowski overpass in Warsaw. In 1985, a major repair started on the Prince Józef Poniatowski overpass in Warsaw. It was the first time injection of cracks in concrete with epoxy resin and the repair of vast vertical areas by concrete spraying had been used. The repair took five years with 30 years having lapsed since. It can be concluded that if the repair rules are observed ,25,26, tThe difficulty in determining “repair durability” can be attributed to the interchangeable use of the terms “repair as restoring a structure’s use potential” (correct) and “repair as restoring a structure’s durability” (excess).The term “durable repair” is a mental shortcut, which means ensuring the durability of repair effects. Durability (service life) of the repaired building structure is important (rather than durability of the “repair”), which results from the influence of the use potential and the rate of destruction processes . A repaithe use potential is always restored back to the original conditionthe destruction rate does not change as a result of the repairthe fact that the repair occurs in time is not taken into account (the repair arrows are oriented upwards)If premature degradation of a structure occurs, e.g., as a result of a random event or continuous destructive processes of significant intensity, EN 1504-9  states tGenerally, there are also more complex structure durability management strategies to be considered ,30. StruIn fact, the durability management model can be even more complex, if the applied repair methods impact not only the level of the use potential after the repair but also the degradation rate, stalling it e.g., by applying corrosion inhibitors, or accelerating it e.g., as a result of concentration cell formation following the repair. The latter is normally not intended and, more dangerously, it can go unnoticed. It will be emphasised that structural safety is the most important requirement, which we want to meet as a result of the repair.Following earlier deliberations, it was demonstrated that the commonly used term “concrete repair durability” is correctly understood as a structure’s durability (service life) after the repair. The subject literature is vast; there are many publications including the term “repair durability” in their titles ,39,40,41Rarely , the documents give a clear answer, e.g., indicating the number of years which determine repair durability, i.e., the period of maintaining the structure’s service life achieved (regained) owing to repair. This results from the fact that if a successful repair restores the service condition prior to repair, the structures last and the designed service life of a structure is still running. The value added by the repair as such is hard to separate. In the case of repairs made in structures in critical condition see , the entThe repair process operations are carried out taking into consideration direct and indirect impacts, namely both functional and environmental loads.adhesion—high; it is the prerequisite for successful repair: the higher the adhesion, the higher the tolerances for any potential compatibility errors shrinkage—low; excessive shrinkage  is oftentensile strength—highfatigue strength—high chloride penetration—lowsusceptibility to carbonation—lowresistance to aggressive environmental impact—highThe relevant publications  present theoretical substantiation ,32,34,36These are only one-side limited requirements, usually formulated as in equation: ≥ and ≤.Young’s modulus,creep factor,coefficient of thermal expansion,water absorbability.There is a number of requirements which depend on the repaired concrete characteristics. Concrete of different ages can be repaired. Their values are expressed as closed sets, with the highest and lowest values specified ≤ x ≤, e.g.:It is not surprising that adhesion is a fundamental issue in construction engineering. This is of particular significance for concrete repair, as in this case the repair materials have to be combined with an existing concrete substrate. The most important factor affecting the durability of the repair is the adhesion between repair material and concrete substrate. Approximately, successful repair means “no cracks status”. Considering the damage models and failure mechanisms, the repair system consists of two basic lines  [“The Durability of Repaired Concrete Structure”  by G. Tind EP79) ,47,48. TAs much as 20% of the repaired structures were damaged within the initial five years after the repair. This means that repair durability in this group did not exceed five years. A total of 55% of the repaired structures were damaged within the initial ten years following their repair. Only 10% exhibited repair durability over 25 years, which should be considered as the desired expected value. In this context, the results are disappointing. It needs to be emphasised though that the data refer to the past. The set of repairs included in G. Tilly’s analysis covers repairs carried out before the implementation of the European standard on repairs EN 1504-1 ÷ 10 (2004–2013). Significant progress was made both in the development of the theoretical fundamentals of repairs and in reference to the repair products and systems. In our opinion, the following rule can be formulated: “if a structure is repaired and protected correctly, according to EN 1504-1 ÷ 10, and if it survives the first year of its use with no reservations, it will last for 10 years”. In the final wording: “if a structure is repaired and protected correctly, according to EN 1504-1 ÷ 10, and if it survives the first year of its use with no reservations, it can last for up to 25 years”. Future experiences will verify the predictions.In G. Tilly’s paper, repair success is differentiated depending on the applied repair method. For the most common method of defect filling , the success factor was only 30%, but if the defect filling was combined with the application of surface protective coating, the success factor increased to 50%. An optimistic projection is the successful restoration of durability (load bearing capacity) by 75% and crack injection by 70%. This is particularly important because crack injection repair cannot be repeated. The main reasons for unsuccessful repairs include: scratches (30%), loosening (25%), progressive corrosion (20%), leakage (7%), aggregate alkaline reaction (3%) and other (15%). The ranking of the reasons emphasises the significance of careful repair and stressed the difficulty related to delaying (interrupting) the inevitable corrosion processes. The adhesion of ordinary fresh concrete to old one is rather weak. This phenomenon is the main reason for the presence of polymer in repair materials as a response to the demand to assure a high level of adhesion .A > α ftC; where α = 1.15 to1.30. The safety factor depends on the various repair materials and different systems; with and without coating [In general: f coating ,49.At the same time, along with the increase in adhesion, the tolerance to incompatibility of the properties of the joined materials also increases ,51. EvenIn engineering terms, Concrete Repair Durability, CRD, means additional construction service lifetime obtained through successful repairs. This means that CRD should be expressed in time units. In this case, it was necessary to analyse past repair experiences.The following conclusions have been formulated as a result of the juxtaposition of the modern state of concrete repair technology with selected historical information on concrete repairs and masonry structures repairs.A in the repair joints should be above tensile strength of the concrete, ftC and internal shrinkage stress, σt. Therefore, we arrive at: fA ≥ ftR ≥ ftC ≥ σt that should be maintained throughout the expected service life.A successful repair means that there are “no cracks” occurring throughout the estimated service life. This means that the adhesion, fThe adhesion between repair materials and concrete structures is a decisive factor of radical concrete repairs. The answer to ensuring a high level of adhesion is the presence of the polymer in repair materials. This means that if a repaired concrete is of a higher class, we would need a repair material with a higher polymer content.Concrete repairing impact on the repair durability is acting according to the two mechanisms:-Restore the original (or even improved) application potential,and/or-The reduction of the rate of destruction process.The distribution function of the aforementioned repaired structural damages indicates that the durability of 50% of these repairs is less than 10 years. These poor results relate to historical structures and past attempts at repairing them. The expected repair durability median value is 25 years. Successful repairs are not only dependent on observing best practices in a given period, but also on the skills of people executing the repairs. There is an opportunity to manage repair strategy in a proactive way to assure expected durability of repaired concrete.


Due to the non-uniform tension and compression strength of concrete, carbon fiber can be added to concrete to improve its static tensile behavior and increase the tension–compression ratio. In view of the destructive consequences of impacts and explosions, it is necessary to study the dynamic responses of carbon fiber reinforced concrete (CFRC) structures. Therefore, the effects of the stress rates and carbon fiber contents on the dynamic tension behavior of CFRC were investigated in this paper. The dynamic splitting tests of concrete with the fiber contents of 0, 0.1, 0.2, and 0.3% were carried out by using a split Hopkinson pressure bar (SHPB) device with a diameter of 74 mm. We found that with the increase of fiber content, the static tensile strength of CFRC increases obviously, but the increased amplitude tends to decrease. The dynamic tensile strength and dynamic increase factor (DIF) both increase with the increase of stress rate, but the growth rate slows down, showing an obvious rate effect. The rate sensitivity of ordinary concrete is higher than CFRC. There are significant differences in the influence of carbon fiber on the dynamic and static strength of concrete. In the design of concrete mixing proportion, the content of carbon fiber should be appropriately selected to meet the requirements of dynamic and static mechanical properties. Concrete is by far the most important building material. Due to its relatively low price, simple production, and wide range of application, its consumption is increasing all over the world. The requirements of concrete strength and mechanical properties have gradually increased with the rapid development of high-rise buildings and long-span buildings. The damage to a concrete structure is often affected by its tensile properties. In the uniaxial compression, the damage to concrete is essentially controlled by the tensile damage perpendicular to the direction of pressure . HoweverThe steel fibers and polymer fibers are easily obtained and incorporated into the concrete matrix, which can effectively inhibit the initiation and expansion of cracks during the destruction of concrete structures, and improve durability and tensile strength, so they have become widely used fibers ,8,9,10. D.D.L. Chung  first foAfter a brief introduction to the entire test process, the test results on the static tensile strength of CFRC were reported. The influence of fiber content on the splitting tensile strength and failure patterns of CFRC was investigated by analyzing the test results. Then, considering the action of dynamic loading, a series of dynamic splitting tensile tests were carried out on concrete with different carbon fiber contents using the split Hopkinson pressure bar (SHPB) system. Combined with high-speed imaging technology, the crack propagation process and dynamic tensile properties of CFRC, including failure morphology, stress time-history curve, and dynamic tensile strength, were studied. The effects of carbon fiber content and strain rate on the mechanical properties of CFRC were analyzed. The differences in the mechanical properties of CFRC under static and dynamic loading were discussed based on the change of meso-structure. The test results can provide a reference for practical engineering application and stability analysis of carbon fiber concrete under dynamic load.This section mainly briefly describes the test methods and procedure, including the preparation of materials, the selection of test equipment and the methods of data processing, the preparation process of test pieces, etc.−3, the maximum particle size of 5 mm, and the fineness modulus of 2.70 was used as fine aggregate. The water used in the test was tap water, and the chemical composition is shown in Raw materials: The cement was made of ordinary Portland cement (P.O42.5), the silica fume was produced in Sichuan Province, China, and the composition of the cement and silica fume are shown in Li  suggesteAt present, the static tensile strength of brittle materials such as concrete and rock are generally determined by direct tensile test and splitting tensile test ,38. BecaP is the compressive force applied to the specimen, and D and L are the specimen diameter and length, respectively.During the loading process, the relatively uniform tensile stress perpendicular to the loading direction was formed on the vertical diameter plane, which eventually led to the failure of the specimen along the vertical diameter. Elasticity analysis ,40 showe−3, an elastic modulus of 210 GPa, and a longitudinal wave velocity of 5190 m·s−1. The SHPB test device is shown in The 74-mm-diameter SHPB test device was used to conduct the dynamic splitting test on concrete specimens. The length of the striker bar, incident bar, and transmission bar were 0.4, 3.20, and 1.80 m, respectively. All the pressure bars of the SHPB device were alloy steel, with a density of 7.8 g·cmIn the dynamic test, under the action of driving pressure, the striker bar impacted on the incident bar to generate an incident wave, and propagated along the incident bar. Due to the difference of wave impedance between the specimen and the pressure bar, one part of the incident wave was reflected back to the incident bar and generated a reflected wave, while the other part propagated the transmission bar through the specimen and generated a transmission wave. The super dynamic strain indicator was used to measure incident wave, reflected wave, and transmitted wave in the bar. Then the stress and strain in the bar were calculated according to the propagation theory of the one-dimensional elastic stress wave. The resistance strain gauges with a model of BX120-3AA and a sensitivity coefficient of 2.08 ± 0.01 mm were pasted in the incident bar. In order to acquire weak transmission wave accurately, the semiconductor strain gauges with a resistance of 120 Ω and a sensitivity coefficient of 110 ± 0.05 were pasted in the transmission bar.tσ(t) is the stress of the specimen; tε(t) is the transmitted strain in the pressure bar; A is the cross section area of the pressure bar; E is the elastic modulus.The results of Gomez  and Guo The tensile strength and failure patterns of concrete specimens with different carbon fiber contents under static load were mainly analyzed in this part. The static test can provide a basis for the discussion and analysis of subsequent dynamic tensile test results. It should be noted that the steel strips were not used to distribute the load between the specimen and the loading plate in this test. It is mainly because of the existence of the steel strips in the dynamic splitting test that the specimen is difficult to be placed, and there is wave reflection at the interface between the steel strip and the test piece, which interferes with the incident wave and reflected wave. The transmission waveguide measured by the strain gauge results in complex and inaccurate data processing . To comp−1. Three parallel specimens were tested for each group, and the static tensile strength of the specimens can be calculated by Equation (1). The tensile strength of concrete with different carbon fiber contents is shown in Static splitting test loading was carried out in the form of control force, and the loading rate was 0.1 kN·sAs shown in The failure patterns of CG, CFRC0.1, CFRC0.2, and CFRC0.3 are shown in The CG specimen had an obvious straight crack and relatively smooth fracture surfaces. The specimen was split into two semicircles, and the tensile strain capacity was insufficient, showing significant brittle failure characteristics. The main reason was that the water evaporated rapidly in the process of hydration reaction, resulting in many micro-cracks and pores in the matrix. When the specimen was subjected to static loading, stress concentration occurred in the crack tip, and micro-cracks expanded from the center to both ends gradually, eventually forming a straight crack leading to brittle failure of the specimen . With th−1 to 460 GPa·s−1. Under high stress rate, the increase of dynamic tensile strength is usually expressed by the dynamic increase factor (DIF), that is, the ratio of dynamic tensile strength to static tensile strength. The DIF can be obtained by Equation (3). Test results are shown in ftd and fts are the dynamic and static tensile strength, respectively.Dynamic splitting tests of CFRC specimens with different carbon fiber contents  were carried out with the SHPB device under different impact pressures . Meanwhile, for the convenience of analysis and comparison, dynamic splitting tests were carried out for concrete specimens without carbon fiber at different impact pressures. In the dynamic splitting test, the stress rate is commonly used to characterize the rate effect of materials. The stress rate can be obtained according to The typical SHPB waveform curve was obtained through the experimental collection, as shown in From the analysis in Combined with the high-speed camera technique, the failure patterns of CFRC under dynamic splitting tension were investigated by using the SHPB technique. To reflect the crack development process of the concrete specimen, the sampling frequency of 50,000 frames per second was adopted by the high-speed camera. The time difference between any two images taken with the high-speed camera was calculated as 20 μs. The crack propagation diagram of the concrete specimen under the same impact pressure is shown in As shown in To explain the change process in the dynamic tensile strength of CFRC more clearly, the test data were processed by Equation (2) to obtain the stress time-history curves of specimens with different carbon fiber content, as shown in From As shown in The distribution of DIF values under different stress rates is shown in From Through the special research on CFRC, although some valuable research results were obtained, there are still some phenomena and problems that need to be further analyzed and discussed.Previous studies on the influence of carbon fiber content and length on the mechanical properties of concrete ,26,52 haAccording to the above analysis of the test results of CFRC, under static loading, the tensile strength increased significantly with the increase of carbon fiber content. Under impact loading, the dynamic tensile strength of concrete decreased with the addition of carbon fiber, which was different from the static test results. To explore the reasons for the difference between dynamic and static mechanical properties of concrete, the digital electron microscope with an amplification factor of 1000 was used to observe the fracture surface of CFRC. The observation results of the microscopic structure are shown in From The phenomenon of the mesoscopic structure in The dynamic tensile strength of carbon fiber with a content of 0.3% was higher than that with 0.2%, which means that the dynamic tensile strength has a rising phenomenon as the fiber content continues to increase. The reason may be that the content of carbon fiber in CFRC0.3 is relatively high. Under impact loading, some fibers are not directly fractured but broken after being pulled out, which improves the mechanical properties. In subsequent research, the reason for dynamic tensile strength rebound can be further studied in view of the high content of carbon fiber, and the strength variation law of CFRC under impact load can be found out, which can provide more reliable reference for engineering applications. However, there were inevitable errors in the specimen preparation and testing system. The main influencing factors included the dispersion of carbon fiber in concrete, the stability of impact pressure and the accuracy of the acquisition system. Therefore, the failure mode and tensile properties of CFRC specimens need to be further studied on this basis.With the increase of fiber content, the static tensile strength of CFRC increases obviously, but the increased amplitude tends to decrease. From the perspective of failure morphology, both CG and CFRC specimens show the characteristics of brittle failure. Under static load, carbon fiber does not significantly improve the ductility of concrete specimens.When the fiber content is constant, the dynamic tensile strength and DIF both increase with the increase of stress rate, which has an obvious rate effect, but the growth rate becomes slower. Contrary to static loading, the addition of carbon fiber makes the dynamic tensile strength and DIF of CFRC lower than CG, but the failure form shows certain ductility characteristics.CG and CFRC specimens show a similar rate sensitivity trend, and the DIF value of the specimen increases linearly with the increase of the logarithm of the stress rate. Besides, CG specimens have higher rate sensitivity than CFRC, and the rate sensitivity does not decrease only with the increase of carbon fiber content.The static tensile strength of CFRC is significantly improved, and the tension–compression ratio of concrete is increased, which is of great significance to concrete. This improvement reduces the risk of unpredicted damage to concrete structures, which means that it has a wide application prospect. But the addition of carbon fiber has a negative effect on dynamic tensile strength. Obviously, the content of carbon fiber should be selected according to the requirements of the application field, so that the compressive strength and tensile strength/impact resistance can be balanced.In this paper, the dynamic splitting tensile tests of CFRC with different contents were carried out by using the SHPB test device, and its dynamic tensile strength, DIF, and damage characteristics were analyzed and researched. The differences between dynamic and static mechanical properties of CFRC were discussed. The following conclusions were drawn:


The interface bonding behavior between the steel tube and the concrete of concrete-filled steel tube (CFST) blended with circulating fluidized bed bottom ash (CFB-BA) was investigated in this study. A total of 8 groups of CFSTs stub columns were prepared with different dosage of CFB-BA, water-binder ratio (W/B), and interface bonding length. A series of push-out tests were carried out to acquire the data representing the interface bonding behavior. The results show that the dosage of CFB-BA has a direct effect on interface bonding behavior of CFST. CFB-BA can improve the interface bonding behavior of CFST. The highest ultimate bonding load and strength are achieved when the dosage of CFB-BA is 30%. When the dosage of CFB-BA increases to 50%, its interface bonding behavior decreases, but is still better than that of CFST without CFB-BA. W/B has a negative correlation with the interface bonding behavior of CFST. While the W/B increases, the interface bonding load and strength of CFST decreases. The increase of the interface bonding length can improve the interface bonding load, but cannot improve the interface bonding strength. Concrete-filled steel tube (CFST) is composed of steel tube and core concrete working together ,2. It haThe interface bonding force of the CFST consists of chemical bonding force, mechanical biting force, and frictional resistance . There ax emissions [2 and Al2O3, so it also has pozzolanic activity [Circulating fluidized bed bottom ash (CFB-BA) is a waste product from the bottom of circulating fluidized bed combustion in thermal power plants. CFB technology has been widely used due to its advantages such as good fuel adaptability, high efficient combustion, and low NOmissions ,18,19. Tmissions . Differeactivity . Researcactivity ,23,24. Tactivity . Zhi CheThe aforementioned works indicate that CFB-BA has expansibility, which is benificial for compensating the shrinkage of concrete. This paper presents the interface bonding behavior between the steel tube and the core concrete of CFST, which can contribute to the application of CFB-BA in CFST. In the paper, a controlled variable method was used to design a total of 8 groups of CFSTs, and push-out tests were carried out. The dosage of CFB-BA, the water-binder ratio and the interface bonding length are considered to be the main influencing factor. Load-slip curves, longitudinal strain distribution, and other data were obtained to analyze the interface bonding behavior of the CFSTs.2/kg. Particle size distribution of ground CFB-BA is shown in Grade P.O 42.5 Portland Cement (PC)  was used in the experiment. The physical and mechanical properties of the PC are shown in 3 and 1550 kg/m3, respectively. The sand was sieved in compliance with the Chinese Industry Standard “GB/T 14684-2011 Construction sand” [The crushed stone (G) (5~20 mm) was used as the coarse aggregate, which meets the demand of the Chinese Industry Standard “GB/T 14685-2011 Pebble and crushed stone for construction” . The finon sand” . All aggThe polycarboxylate superplasticizer (PS) was from Baoding Muhu Hengyuan New Building Material Company . Grade Q235 circular steel tubes with a straight slit  were adopted to fabricate the test specimens. The steel tube was 2.5 mm in thickness and 89 mm in outer diameter. The material properties of steel are shown in A total of 8 groups CFSTs were fabricated with a dosage of CFB-BA, W/B, and interface bonding length as variables. Each group contained two specimens, and the final test results were averaged accordingly. The self-compacting concretes (SCCs) were prepared, and the values of slump flow all exceed 650 mm. Before pouring the specimens, both ends of the steel tubes were polished, and the bottom was sealed with thin-film plastic to prevent the poured concrete from flowing out. The specimens were fabricated in the laboratory with a temperature of 20 ± 2 °C and a relative humidity of 50%. Three standard test cubes were reserved for each group to test the compressive strength of SCCs. The Mix proportions of SCCs is shown in The static grading load method was adopted in the push-out test. The test device model is shown in The loading process of the CFST specimen is divided into two stages, known as the pre-loading stage and formal loading stage.During the process of test loading, the 5 kN load was pre-applied. The upper and lower pressure plates, specimens and pads of the press were in close contact so that the core concrete was evenly stressed.In the formal loading stage, the load was graded, the rate was lower than 200 N/s, and the load was recorded every 5 kN load until the test specimens failed. At the beginning of loading, there was no change in the value displayed by the dial gauge and strain gauge. As the load increased, the loading process was gradually stabilized, and a small amount of slippage occurred at the end of the loading process. The relative amount of slippage became even larger as the load increased from the initial stage. The produce of the slippage means the chemical bonding force failure between the steel tube and the CFB-BA concrete . In the The load-slip curves of CFST are shown in During the initial loading, slip occurs on a small scale between the concrete and the steel tube, because the core concrete is in direct contact with the loading slab. The core concrete produces the elastic compression deformation, causing slip afterward. As the load increases, the relative slip between the steel tube and the core concrete undergoes a process from slight slip to partial slip, and finally to full slip. When the load is increased to the failure load of the component interface bonding, the load-slip curve grows almost linearly. Besides, the interface bonding force is continuous along with the component length. With the increase of the load, the relative slip also increases with the speed lower than the load speed. When the applied load is close to the interface failure load, the relative curvature of the load-displacement curve becomes smaller. Load-slip curve shows an evident inflection point. With the increasing of component relative slip, the load has no significant change. The curve stays at a certain level for a period of time.In the OA section, the initial load is rather small, and the specimens have a slight relative slip. At this time, the interface bonding force of the CFST is mainly borne by the chemical bonding force. The main factors affecting the chemical bonding force are cement dosage, concrete strength, and water binder ratio . The cheFU). The load shows approximate linear distribution before the load is near to point B.In the AB section, when the load continues increasing, a relatively large slip occurs between the core concrete and the steel tube. The local relative slip becomes more evident. At this time, the load on the specimen increases faster than the increase of relative slip. The interface bonding force is mainly caused by part of the chemical bonding force and mechanical biting force. When the chemical bonding force and mechanical biting force on the interface reach the maximum value, the load is near to the ultimate bonding load 2, and Ⅱ-CaSO4 can hydrate to gypsum. Gypsum can continue to react with Ca(OH)2 and hydrated calcium aluminate, and then produce ettringite. The ettringite can fill the pores and improve the compactness of the core concrete, and even produce self-stress in the CFST. So dosage of CFB-BA can improve the compressive strength of the core concrete, and make the core concrete and steel tube closer. But too much CFB-BA can lead to great expansion and anhydrite cannot hydrate completely, which decrease the compressive strength of the core concrete. So there exists a reasonable amount of CFB-BA. When the amount of CFB-BA is 30%, the CFST gains the maximum bonding load and maximum bonding strength [strength .The load slip curve of CFST blended with CFB-BA can be divided into four stages. The strains along the longitudinal height of the steel tube are the same as the ordinary CFST without CFB-BA.Adding CFB-BA within a certain range has a positive effect on the bonding strength of CFST. When the dosage of CFB-BA is 10%, 30% and 50%, the interface bonding strength of CFST increased by 22.8%, 26.9% and 1.5%, respectively. The micro-expansion property of the CFB-BA can make the concrete squeeze on the sidewall of the steel tube to improve the interface bonding strength. However, too much CFB-BA in concrete will reduce the strength of the concrete, thereby reducing the bonding strength of CFST.The W/B has an important influence on the interface bonding strength of CFST with CFB-BA. When the dosage of CFB-BA and the interface bonding length are constant, the higher the W/B, the lower the interface bonding strength of the CFST. W/B has negative correlation with the interface bonding load and bonding strength. When the W/B is 0.3, the interface bonding strength of the CFST reached the maximum, the value reaches 2.50 MPa.Bonding length has a significant effect on the ultimate bonding load of CFST. However, because the force-bearing area increases with the increase of the bonding length, the bonding strength of CFST is basically unaffected.The interface bonding behavior of CFST blended with CFB-BA was studied in the paper, and a total of 8 groups of CFST were designed for the push-out test. Several conclusions can be drawn as the following:


ObjectiveTransforaminal lumbar interbody fusion (TLIF) is a common approach and results in varying degrees of lordosis correction. The purpose of this study is to determine preoperative radiographic spinopelvic parameters that predict change in postoperative segmental and lumbar lordosis after TLIF.Materials & MethodsThis study is a single surgeon retrospective review of one-level and two-level TLIFs from L3-S1. All patients underwent bilateral facetectomies, 10 mm TLIF cage (non-lordotic) insertions, and bilateral pedicle screw-rod construct placements. Pre- and post-operative X-rays were assessed for preoperative segmental lordosis (SL), lumbar lordosis (LL), and pelvic incidence (PI). Univariate and multi-predictor linear regression analyses were performed to determine the relationships between preoperative radiographic findings and change in early postoperative segmental and lumbar lordosis.ResultsNinety-seven patients contributing 128 intervertebral segments were examined. The mean change in SL after TLIF was 7.3 . The mean change in LL after TLIF was 5.5˚  7.16°). Greater preoperative LL predicted less postoperative LL correction, while greater preoperative PI predicted more postoperative SL and LL correction. Greater anterior disk height was noted to be associated with a decreased change in SL (∆SL). An annular tear on preoperative magnetic resonance imaging (MRI) predicted a 2.7° decrease in ∆SL. A Schmorl's node on preoperative MRI predicted a 4.0° decrease in change in LL (∆LL).ConclusionsA greater preoperative lordosis and a lower spinopelvic mismatch lessen the potential for an increase in the postoperative SL and LL after a TLIF, which is likely due to a ‘ceiling’ effect of an otherwise optimized spinal alignment. A greater anterior disk height and the presence of an annular tear are associated with decreased ∆SL. Transforaminal lumbar interbody fusion (TLIF) is a widely used, safe, and efficacious approach for surgical management of lumbar degenerative disease and spinal deformity -4. TLIF Sagittal imbalance is the primary predictor of disability in adult spinal deformity, and restoration of sagittal alignment with spinopelvic harmony (or matched PI and LL) is known to lead to the best long-term outcomes in patients who undergo surgical correction , 16, 17.Currently, there are limited studies that use patient-specific imaging characteristics to predict SL correction after TLIF . TherefoAfter obtaining approval from the University of Florida's internal review board (IRB202002814), we conducted a single surgeon retrospective review of all patients that underwent one- and two-level TLIFs from levels L3-S1, between 2010 and 2015. Data was de-identified and therefore, informed consent was not sought. Patients less than 18 years of age were excluded from this study. Each patient included in the study had preoperative 36-inch standing x-rays and post-operative lumbar x-rays. Additionally, 39% had a preoperative lumbar computerized tomography (CT) scan and 95% had a preoperative lumbar MRI. Each patient included in the study underwent a standard open TLIF technique (as previously described) involving a laminectomy with complete bilateral facetectomies, bilateral pedicle screw-rod construct placements, and placement of a 10mm non-lordotic cage .Data acquisitionPreoperative and immediate postoperative x-rays were assessed for spinopelvic parameters, including LL, SL and PI. LL was defined as the Cobb angle between the superior endplates of L1 and S1. SL was defined as the Cobb angle between the superior endplate above and the inferior endplate below the operative level. PI was defined as the angle between a line perpendicular to the sacral plate at its midpoint and a line connecting this point to the femoral head axis. The spinopelvic mismatch was calculated as PI-LL. Changes in LL and SL were calculated by determining the difference between pre- and postoperative Cobb angles of the lumbar spine and at the level(s) of operation, respectively. Immediate postoperative x-rays were used to determine the change in the SL and LL to reflect the primary effect of the TLIF procedure on spinal alignment. Additional radiographic assessments of the intervertebral segment(s) at the operative level(s) were performed using preoperative MRI and CT scans, including the anterior disk height, annular tears, presence of a Schmorl's node, Modic type endplate change, bridging osteophytes, and vacuum disk. All preoperative disk characteristics and pre-/postoperative spinal measurements were performed and collected by two individuals (KP and AD), with a calculated discordance of 2.3% when considering all values included in the study.Statistical MethodsWe used the mixed effect linear regression to fit single- and multi-predictor models of change in LL (ΔLL) and SL (ΔSL) , 35. PosWe used the adjusted R-square to assess the predictive performance of our best multi-predictor linear regression models and validated using Efron's "optimism" . ResiduaA total of 97 patients undergoing TLIFs at 128 levels were examined . There were 32 patients with annular tears (26.02%), 26 patients with a Schmorl's node (21.31%), 63 patients with Modic type endplate changes (51.22%), and 60 patients with intradiskal vacuum phenomena (46.88%).Preoperative spinopelvic parametersThe average preoperative PI was 56.96 SD 14.12) , with a mean improvement of 7.33° . Univariate analysis revealed that greater preoperative SL negatively impacted postoperative ΔSL   -5.34° to -0.38°) Table . ΔSL in The SL cohort was further stratified into the 5th percentile (3.4°), the mean (16.6°), and the 95th percentile (30.9°). This analysis demonstrated that for a mean preoperative SL with an annular tear, a statistically significant ΔSL was only obtained if the preoperative LL was >35° and the PI was >31°. With a preoperative SL in the 95th percentile, but without an annular tear, a statistically significant ΔSL was only obtained if the preoperative LL was >50° and the PI was >60°. No significant change was observed for those with a preoperative SL in the 95th percentile with an annular tear. Otherwise, all other preoperative spinopelvic parameters were observed to cause significant post-operative SLs.All TLIF levels demonstrated improved ΔLL, with a mean change of 5.50° . Univariate analysis revealed a 3.18° increase in LL correction with two-level over one-level surgeries Table .All patients in our study had improvement of segmental lordosis only in the immediate postoperative period, with variation based on characteristics of the intervertebral segment and preoperative spinopelvic parameters. Of the intervertebral segment characteristics we studied, anterior disk height and the presence of an annular tear at least marginally impacted postoperative segmental lordosis change. Patients with a higher preoperative anterior disk height had significantly less ∆SL for a given instrumented level . This suggests a decreased capacity for lordosis correction in these patients, which is a “ceiling" effect as these patients may already have maximal, well-preserved segmental lordosis. This effect, however, lost statistical significance when all predictors were considered, likely due to high variability. The presence of an annular tear was associated with a less postoperative change in SL (2.9°). This may be explained by the association of an annular tear with a more severely degenerated and less mobile disk. Alternatively, the small effect size of < 3 degrees may not represent a true clinically relevant finding. Lower preoperative SL and high preoperative spinopelvic mismatch are both associated in the literature with greater postoperative lordosis restoration ,19,24. OThis study has several limitations including its retrospective design and inclusion of patients from a single surgeon and a standardized technique for open TLIF, which may impact the generalizability of the findings. Postoperative radiographic assessment was performed using immediate postoperative x-rays, and not at longer-term follow-up. This study was designed to isolate the primary effect of the TLIF procedure on change in LL and SL. It is well understood that delayed subsidence may occur over time which may reduce LL and SL, but this is likely variably affected by individual patient factors . Therefore, the study findings observed here likely represent the maximal extent of lordosis correction at the index surgical procedure and may demonstrate loss of effect in some patients over time. Additionally, our prediction equations require additional power in order to further reduce error.The TLIF is a valuable procedure for restoration of lordosis, but individualized intervertebral segment and spinal alignment parameters may limit the degree of attainable correction. A greater anterior disk height and an annular tear are associated with a decreased ∆SL. Greater initial lordotic angles and lower spinopelvic mismatch lessen the potential for change in LL and SL due to a ‘ceiling’ effect of an otherwise well-aligned spine. Alternatively, patients with significant preoperative losses of segmental and overall lumbar lordosis may demonstrate potentially greater corrections of spinal alignment with TLIFs.


Damage to large reinforced concrete structures is rarely due to design errors. Sometimes, however, a small error can lead to major damage and costly repairs. The article describes the damage, the results of non-destructive and destructive tests, the results of numerical calculations, and the method of repairing a reinforced concrete tank in a sewage treatment plant. The failure was caused by applying the wrong boundary conditions to the reinforced concrete wall support inside an existing biological reactor. During leak testing, one of the new walls cracked and was displaced, which resulted in the tank leaking. An inspection of wall damage and displacement was carried out on termination of the leak testing and while the tank was draining. The causes of the failure were determined based on the inventory information and numerical simulations. Both non-destructive tests of reinforcement and concrete and destructive tests of concrete were carried out. The concrete class of the foundation slab was determined based on a compression test of sample cores obtained from drilling. The aim of the non-destructive tests was to indicate the location and diameter of reinforcement in the damaged wall using electromagnetic and radar methods, as well as the location of internal defects using ultrasonic and radar methods. It was found out that the failure was a result of an incorrect determination of the anchoring length of the reinforcement. Based on the analysis, a plan to repair the damaged wall was formulated and then successfully implemented. In the article the authors proposed the IVD (identification-verification-design) scheme to make the design easier in similar cases. Structural failure and collapses are usually the consequence of various factors, such as the technology applied during operation ,2, instaThe use of bar anchoring techniques has been well known for many years and is used in extensions to existing buildings. Manufacturers of anchorage systems provide calculation programs for designers based on their research and standard regulations. The recommendations of the manufacturers of anchoring systems focus on the quality of the hole in the concrete, assuming at the same time that it will be made perfectly, will not be wet, and will be cleaned. Current scientific and materials research focuses on the local failure mechanism, leaving aside the global load-bearing capacity of the element to which the new element is to be fixed. Despite the efforts of modern researchers on the influence of various adverse conditions such as anchoring of bars in a wet hole  and the The biological reactor was brought into operation in 1989 . HoweverThe reduction of the tank capacity allowed the structure to be optimized. Optimization covered both the reduction of the amount of the material needed and also simplification in the installation process. Then, the full anchorage of the planned wall to the existing foundation slab of the reactor was designed.As far as anchoring the wall to the existing foundation is concerned, the rebars were fixed to a concrete floor with an adhesive ,11. It iPost-installed reinforcing bars required using so-called chemical bonds. Usually, this means applying a chemical system comprising two components: a resin  and a hardener, which, when mixed together, harden in an appropriate adhesion to existing concrete. The joining (anchoring) of the rebar in the concrete floor is achieved by means of a mechanical interlock between the adhesive cement and the ribs of the rebar, as well as the adhesive forces and micro-interlock due to the roughness of the borehole surface at the adhesive-concrete interface. The resistance of the rebar join  may resuThe first type of failure, namely a pull-out of the rebar from the resin, is not common. The production of chemical bonds is now strictly controlled, and the products undergo detailed testing in the process of preparing technical specifications  and due In the second half of 2018, renovation work and technological upgrade of the biological reactor in the waste treatment plant began. Reconstruction of the biological reactors involved a partial change of the internal wall arrangement and also a reduction of the reactor capacity by installing new walls along the A axis .The concrete class for walls was assumed as C35/45, and reinforcement as B500SP steel in the form of double-sided steel mesh with ϕ 16 mm and ϕ 20 mm rebars. The thickness of the wall on the A axis was 40 cm, whereas the wall height from the upside surface of the foundation slab of the reactor was 5.0 m. The project design involved fixing the planned wall into the foundation slab of the reactor. The rebars were fixed to the foundation slab with adhesive one of the systems available on the market ,20. The The project design engineer did not calculate the length required for the anchoring in the foundation slab, which must have been taken into consideration when fixing rebars with adhesive. The design engineer adopted a nominal depth without verifying whether it was sufficient in relation to the possible failure of the rebar. Based on the catalogue of the anchor manufacturer , the engCompletion of the building work on reactor 2 was planned for mid-September 2018. As part of this process, the reactor vessel was filled with water to a level of 4.35 m above the bottom and leak testing was initiated—During the leak testing, leaks appeared showing the location of shrinkage cracks . ShrinkaOnce the tank was completely drained, it was determined that the wall deflection was partly reduced to an average about 1.0–2.5 cm. On the inside of the tank, a crack was observed at the base of the wall at the interface between the old and new concrete of ~0.7 cm indicates that joining the wall with the foundation slab of the existing biological reactor was not completed.Both non-destructive tests of reinforcement and concrete, and destructive tests of concrete were carried out. The aim of the NDT (non-destructive testing) was to indicate the location and diameter of reinforcement in the damaged wall using electromagnetic and radar methods, as well as the location of internal defects using ultrasonic and radar methods. Devices used in the tests are presented in 2 area each were made on the tested wall. The location of the tested areas is shown in The PS 200 electromagnetic scanner was used to determine the location and diameter of reinforcement a. The seThe Pundit 250 Array ultrasonic tomography for concrete was also used during tests b. The in2) were made on the tested wall. The scans were made in the same places as those of the PS 200 scanner.For radar tests, we used the GPR Live System with antennas generating measurement signal of stepwise variable frequency within the range of 0.2–4.0 GHz c. In theThe conducted NDT showed the compliance of the reinforcement with the project in terms of quantity and location of rebars. However, the concrete cover of the bars was found to be slightly larger than the designed one. The reinforcement was at an average depth of 55 mm, with a standard deviation of 6 mm. This fact was considered in the design by taking the average concrete cover. A comparison of the results of the reinforcement detection using electromagnetic and radar methods is presented in Based on the scans made using the radar method, it was also possible to determine the occurrence of internal defects in the concrete. Images of radar scans at depths behind the reinforcement zone are shown in The effectiveness in anchoring the rebars is directly related to the quality of the concrete bases, in which they are to be embedded. For this reason, compression tests were carried out for the concrete making up the existing foundation slab to determine the concrete class. The concrete class of the foundation slab was determined on the basis of a compression test of sample cores with a diameter of ϕ 100 mm and a height of 100 mm obtained from drilling , in accoA static calculation was carried out using the finite elements method of the SOFiSTiK system . The aimAs a first step, according to ,32,33, tfyk = 500 MPa), which according to the project design were to be anchored at a depth of 25 cm in the foundation slab using the Fischer company injection system [The next step of the verification involved checking on the correctness of the design length of the anchorage in the foundation slab of the existing reactor. The calculations were carried out for B500SP steel rebars  amounts to 75 kNm. On the other hand, the calculated anchorage moment for the wall in the foundation plate obtained from the static calculations (Rd. The key to solving this problem is to use deep anchorage and check the connection with the strut and Tie (S-T) method for reinforced concrete structures. The second important criterion is sufficient bearing capacity of the foundation slab due to bending and cracking. In the case under consideration, the bearing capacity of the foundation slab is twice as low.To answer the question posed earlier, the value for the anchoring moment in the foundation slab was set as a function of the anchorage depth for a ϕ 20 mm rebar in accordance with ,34. In tulations  amounts Therefore, the design concept adopted as a basis for realising the wall was destined for failure from the start as there was no possibility of achieving a completely effective anchorage in the foundation.Both numerical analyses carried out in SOFiSTiK  and inspz-axis is given with the normal to the element’s plane and the local x-axis can be selected freely. The default orientation is parallel to the global XY plane with an angle smaller-equal than 90 degrees to the global X-axis. If the observer looks into the positive direction of the z-axis (thus from “above”), then they watch the nodes numbered counter-clockwise. If the element’s plane coincides with the global XY plane, the local and the global coordinate systems are then identical. Because the normal element remains plane, the bending and the membrane structural behaviour of the individual elements are decoupled. The element properties can thus be defined separately for both components. Additionally the consideration of the components of elastic support and a numerically conditional stiffness for the rotations around the shell normal occurs still. For a twisted element, the membrane and plate parts are generated by decoupling. Then they are coupled with each other via the twist of the element. Thus the element can represent curved shells very accurately.The numerical model using the shell element implemented in the program ASE is a surface element . The ind3, the Young’s Modulus of 34,077 N/mm2 (C35/45) and the Poisson’s ratio of 0.2, nominal strength 35 N/mm2, tensile strength 3.21 N/mm2. Properties of the concrete material for the old, existing structure were assumed as: a unit weight of 24 kN/m3, the Young’s Modulus of 31,476 N/mm2 (C25/30) and the Poisson’s ratio of 0.2, nominal strength 25 N/mm2, tensile strength 2.56 N/mm2. Properties of the reinforcing steel material properties were assumed as: the yield strength of N/mm2 and the Young’s Modulus of 200,000 N/mm2.The ribs supporting the walls were designed as 40 cm thick reinforced concrete pilasters from C35/45 concrete. Due to considerable forces being transferred by the ribs to the foundation plate, additional support was planned in the form of a reinforced concrete base of 2.00 m × 3.50 m in the area and 0.50 m in height. The need to extend the base of the ribs resulted from insufficient flexural load-bearing of the existing foundation slab. While pressing on the slab, the rib generates flexural moments on the slab from ground resistance. Extending the base of the ribs allowed to distribute the loading over a larger area. What is more, the inclusion of a larger area of the slab secures additionally a twofold increase in height of the transverse cross-section for flexural and punching shear forces (50 cm + 50 cm = 100 cm). The basis for rib design was provided by several numerical models (FEM) which replicated the boundary conditions on the edges of the wall support. The numerical model was developed using quadrilateral mesh on surfaces . AdditioEct).The SOFiSTiK  program This approach was adopted to eliminate hidden cracks, about which the authors had no knowledge.The first stage of numerical calculation involved calculating the external forces in the ribs. The next step was to determine the transverse forces including the interactions at the interface of the rib–wall, side walls–wall, wall–foundation slab, and rib base–foundation slab. Determination of the forces provided the basis for designing the connection in the form of post-installed rebars using chemical adhesives .Based on a determination of the external forces in this way, the required strengthening of the pilasters was determined and the serviceability limit state (SLS) and ultimate limit state (ULS) were verified for the wall with the assumption that cracks would be no larger than 0.20 mm.The last stage of the calculations was aimed at verifying the foundation slab in relation to reactions transferred by the base of the ribs to the underlying substrate. A corrected numerical model, based on the previous one, was developed for this purpose. The numerical model was extended to include the existing tank in order to approximate as closely as possible the existing field conditions, for instance: the Winkler model of the soil, the elastic half-space model, and the non-linear behaviour of cracked concrete. Meeting this goal required using the rigid linear connections to take into account the connections at the interface between the bottom of the rib base and the existing foundation slab. A sketch of the most important elements of the numerical model is presented in Numerical analysis and static calculations carried out by the authors provided the basis for the preparation of a repair design. Prior to applying the pilasters, all of the shrinkage cracks, which appeared during the leak test, were sealed. The sealing was carried out by means of injection . The nexγf = 1.50. It is also worth mentioning that the problem of the lack of anchoring would not have appeared if the leak test of the tank had been carried out after infilling unused space behind the wall . In such a situation, the loading from liquid pressure is balanced by a response from the ground. The problem might have revealed itself only during the next renovation when the tank would have been empty. The values of the anchorage moment with pressure from the ground are smaller and can withstand the water accumulation foreseen in the analysed situation of water surface at about 3.0 m, which would have suggested that the proposed solution might have succeeded. The problem with incorrect anchoring depth is a common design problem. The authors discuss all the significant problems that appear in relation to adopting such a solution and present how to make corrections in order to sensitise design engineers and building inspectors to the need to carefully verify these types of solution. All the significant aspects and problems related to the calculations which were carried out for other engineers and researchers to make use of the insights presented have been also included.This paper confirms that adopting the appropriate technical solution and verifying whether the assumed boundary conditions can be realised are an essential part of the design process. In the case discussed, the whole design process was directed, above all, to optimising the structure from the point of view of minimising the volume of concrete to be used and simplifying the implementation technology. The design engineer did not verify whether it was possible to anchor the wall in the foundation slab and, in consequence, adopted the length of the rebar strengthening based on experience in accordance with the nominal catalogue value. No verification was carried out using relevant calculations, as for example in . The desAt the end of the considerations, the authors point out that the reason for the failure was the lack of knowledge about the anchoring rebar in the existing structure. The designer treated the rebar as a simply injectable adhesive anchor without considering the structural requirements and guidelines of the manufacturer of the anchoring system. The problem of the proper interpretation of construction conditions for deep anchoring of rebars requires good knowledge of PN-EN 1992-1-1 , consideStrengthening the structure with inappropriate boundary conditions is a very common mistake. According to the foundation slab, a typical problem is to verify the wall anchorage only by checking the local failure mechanisms .It is also common practice to use simple computer programs prepared by anchor manufacturers. Furthermore, the examples with the anchorage design are prepared considering only the anchors and neglecting among other things the load-bearing capacity of the reinforced concrete node. This node will be formed after the wall is fixed in the existing foundation slab. The authors have presented the entire procedure using all the necessary equipment to assess the quality of the material, the distribution of the reinforcement, and the strength parameters of concrete. The authors proposed also the IVD (identification-verification-design) scheme  to make


Unverified penicillin allergies are common but most patients with a penicillin allergy label can safely use penicillin antibiotics. Penicillin allergy labels are associated with poor clinical outcomes and overuse of second-line antibiotics. There is increasing focus on penicillin allergy “de-labeling” as a tool to improve antibiotic prescribing and antimicrobial stewardship. The effect of outpatient penicillin allergy de-labeling on long-term antibiotic use is uncertain. We performed a retrospective pre- and post- study of antibiotic dispensing patterns, from an electronic dispensing data repository, in patients undergoing penicillin allergy assessment at Auckland City Hospital, New Zealand. Over a mean follow-up of 4.55 years, 215/304 (70.7%) of de-labeled patients were dispensed a penicillin antibiotic. Rates of penicillin antibiotic dispensing were 0.24 (0.18–0.30) penicillin courses per year before de-labeling and 0.80 (0.67–0.93) following de-labeling with a reduction in total antibiotic use from 2.30 (2.06–2.54) to 1.79 (1.59–1.99) antibiotic courses per year. In de-labeled patients, the proportion of antibiotic courses that were penicillin antibiotics increased from 12.81 to 39.62%. Rates of macrolide, cephalosporin, trimethoprim/co-trimoxazole, fluoroquinolone, “other” non-penicillin antibiotic use, and broad-spectrum antibiotic use were all lower following de-labeling. Further, antibiotic costs were lower following de-labeling. In this study, penicillin allergy de-labeling was associated with significant changes in antibiotic dispensing patterns. Clostridium difficile diarrhea  are common with 8–25% of individuals labeled as allergic to penicillin, depending on the patient group studied . PALs ardiarrhea , inapprodiarrhea , increasdiarrhea , and incdiarrhea .Clarifying a patient's penicillin allergy status has the potential to improve their access to appropriate and safe antibiotic therapy while also contributing to antimicrobial stewardship efforts in the era of increasing antimicrobial resistance , 12. AssElectronic dispensing data repositories are powerful potential tools for research on community antibiotic use . The patElectronic pharmacy dispensing records allow the direct comparison of community antibiotic dispensing before and after penicillin allergy evaluation. Here, we contrast antibiotic prescribing before and after penicillin allergy de-labeling through the analysis of several years of pharmacy dispensing records, thus providing information on antibiotic use over longer periods than previously reported. We characterize the use of specific non-penicillin antibiotics that are important targets for antimicrobial stewardship efforts. Further, we compare both the antimicrobial spectrum and cost of antibiotics dispensed before and after de-labeling.Adult patients who underwent an observed penicillin challenge through the Penicillin Allergy Clinic in the Department of Clinical Immunology at Auckland City Hospital between 01/01/2012 and 31/12/2017 were identified from electronic records of Immunology Day Ward attendances. There are approximately 70 penicillin challenges performed through the Antibiotic Allergy Clinic at Auckland City Hospital annually. Further, those with positive penicillin skin testing were identified from electronic records of penicillin skin testing results in the Penicillin Allergy Clinic in the same time period. Patients were excluded from the final analysis if they were aged <15 years at the time of assessment, if they had no medication entries in the TestSafe database prior to assessment, and if they had no antibiotic dispensing entries in the TestSafe database across the pre- and post-assessment periods.Penicillin skin tests were performed by medical laboratory scientists using increasing doses of commercial testing reagents . Skin prick testing (SPT) was followed by intradermal testing (IDT) using a standard protocol with a total of either three or five testing steps, as outlined in the Electronic community pharmacy antibiotic dispensing records for patients in the study cohort were retrieved from the “TestSafe” pharmacy dispensing record repository; this repository contains community pharmacy dispensing records for patients living in four of the ten District Health Boards in the catchment area for our clinic. Patients can opt to have their dispensing records excluded from the TestSafe database. For these reasons, coverage is not universal in our clinic population. Dispensing records specifically relating to oral and intravenous antibiotics were identified by ATC code see , groupedThe primary outcome of the study was the change in penicillin antibiotic dispensing rates before and after penicillin allergy assessment, stratified by allergy assessment outcome . Secondary outcomes, all stratified by allergy assessment outcome, were: the change in non-penicillin antibiotic dispensing rates .Dispensing rates and proportions after assessment were compared with those before assessment using paired Patients with a positive  or negative  penicillin challenge in the Auckland City Hospital Immunology Clinic between 01/01/2012 and 31/12/2017 were identified. There were 483 negative challenges and 17 positive challenges. A review of skin testing records from the same clinic identified 43 patients who were labeled as penicillin allergic based on positive skin test results without an oral challenge. Antibiotic dispensing data, defined as at least one dispensing record for an antibiotic in either the pre- or post- intervention period, was available for 304/483 (62.9%) negative challenge patients, 12/17 (70.6%) positive challenge patients, and 25/43 (58.1%) positive skin testing patients; these 341 patients comprised the study cohort , giving n = 304) and no change in confirmed penicillin allergic patients (n = 37), with 2.75 (95% CI 1.59–3.91) and 2.33 (95% CI 1.33–3.33) courses dispensed per year before and after assessment, respectively  were subsequently dispensed a penicillin antibiotic , compareectively .n = 304, For clinical reasons, the total number of annual antibiotic courses is likely to differ between patients. To control for this, dispensing of penicillin antibiotics as a proportion of total antibiotic courses was calculated for each de-labeled patient before and after penicillin allergy de-labeling n = 304, . The mean = 304, The effect of penicillin allergy de-labeling on the use of non-penicillin antibiotics was assessed by comparing non-penicillin antibiotic dispensing rates before and after de-labeling n = 304, . Macrolin = 304, p < 0.001, Non-penicillin antibiotic use was also measured as a proportion of each de-labeled patient's total antibiotic use before and after penicillin allergy de-labeling n = 304, . MacroliPenicillin allergy de-labeling is increasingly recognized as safe and has the potential to impact antibiotic prescribing. However, longer-term, high-quality data on antibiotic use following penicillin allergy de-labeling is limited. In this pre- and post- study, penicillin antibiotic use increased significantly in those who had their penicillin allergy removed following an observed challenge. After de-labeling, 70.6% of patients went on to use a penicillin antibiotic over a mean follow up period of 4.55 years. Further, patients who had their penicillin allergy confirmed had a lower penicillin antibiotic dispensing rate post-assessment, indicating that there may be benefits of undergoing assessment with skin testing and/or an observed penicillin challenge even for patients who are confirmed to be allergic to penicillin.Our findings support those from patients enrolled in a study of penicillin skin testing reagents, 94/196 (47%) received at least one penicillin antibiotic in the year following negative skin testing compared with 40/196 (20%) in the year prior . At a meIn de-labeled patients, the increased use of penicillin antibiotics in our study did not result in an overall increase in antibiotic use; total antibiotic use was lower following de-labeling. At 0.80 (95% CI 0.67–0.93) penicillin courses per patient per year, penicillin use in our de-labeled cohort exceeded the national rate of 0.48 penicillin antibiotic courses per year , likely This study also demonstrated that non-penicillin antibiotic use, when measured by either dispensing rate or as a proportion of a given patient's total antibiotic courses, reduced significantly across a range of classes that are important targets for antimicrobial stewardship . Further, rates of broad-spectrum antibiotic use were lower following penicillin allergy de-labeling. A reduction in tetracycline use was an inconsistent finding perhaps reflecting that tetracycline has indications outside of the treatment of acute infections (such as for acne) and so may be prescribed specifically in certain situations without consideration given to alternative antibiotics. This represents an important limitation of the study: no data were available on the indication for each antibiotic course as these data are housed in separate health record systems e.g., in primary care, acute clinics, etc. Some antibiotic use captured in our dispensing data will have been for empiric treatment of infections where penicillin antibiotics are first line, others will have been prescribed for infections where other antibiotics are recommended preferentially  , and somThe retrospective and observational nature of this study means that other factors could have affected antibiotic use in this cohort and, therefore, changes in antibiotic dispensing patterns cannot solely be attributed to the effect of the penicillin allergy assessment. Results should be interpreted acknowledging that antibiotic dispensing data were used as a surrogate for antibiotic consumption and were available for 341/543 (63%) patients assessed in the Penicillin Allergy Clinic. As a regional service, some patients attending our clinic may reside in areas outside of the greater Auckland region that is covered by the TestSafe dispensing repository. Further, patients can opt to have their dispensing data excluded from the repository and it is possible that some patients did not use any antibiotics in the pre- and post- assessment periods . Clinical information on the nature of the reaction that gave rise to the penicillin allergy label was not available. We do not know whether subsequent antibiotic courses resulted in allergic or adverse drug reactions. Previous work indicates that in patients with negative skin testing, after a mean follow-up period was 4.5 years, and after exposure to a mean of 8.2 therapeutic antibiotic courses, the rate of new antibiotic “allergy” to penicillin antibiotics was 2.9% . Lastly,In conclusion, this pre- and post- study of the effect of penicillin allergy assessment on antibiotic dispensing patterns demonstrates that penicillin allergy de-labeling is associated with increased penicillin antibiotic use, decreased non-penicillin antibiotic use, and reduced antibiotic costs. This study provides support for penicillin allergy evaluation in a specialist clinic as an important intervention in the era of antimicrobial stewardship. It is not clear if other de-labeling interventions delivered outside a specialist clinic, such as pharmacist-led penicillin allergy de-labeling, which have the potential to improve access to penicillin allergy de-labeling, will be associated with similar changes in antibiotic use although early data are promising . WhetherThe raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by Auckland Health Research Ethics Committee (AHREC 000130). Written informed consent for participation was not required for this study in accordance with the national legislation and the institutional requirements.TH designed the study, performed data analysis, and wrote the manuscript. NA performed the dispensing data extract and data analysis. ED performed data analysis and wrote the manuscript. JC performed data entry and analysis. AJ designed the study. PF designed the study and wrote the manuscript. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.