DNA damage repair (DDR) is an essential process for living organisms and contributes to genome maintenance and evolution. DDR involves different pathways including Homologous recombination (HR), Nucleotide Excision Repair (NER) and Base excision repair (BER) for example. The activity of each pathway is revealed with particular drug inducing lesions, but the repair of most DNA lesions depends on concomitant or subsequent action of the multiple pathways.E. coli. We combined genomic methods (TIS and Hi-SC2) and imaging assays with genetic dissections.In the present study, we used two genotoxic antibiotics, mitomycin C (MMC) and Bleomycin (BLM), to decipher the interplays between these different pathways in We demonstrate that only a small set of DDR proteins are common to the repair of the lesions induced by these two drugs. Among them, RecN, an SMC-like protein, plays an important role by controlling sister chromatids dynamics and genome morphology at different steps of the repair processes. We further demonstrate that RecN influence on sister chromatids dynamics is not equivalent during the processing of the lesions induced by the two drugs. We observed that RecN activity and stability requires a pre-processing of the MMC-induced lesions by the NER but not for BLM-induced lesions.Those results show that RecN plays a major role in rescuing toxic intermediates generated by the BER pathway in addition to its well-known importance to the repair of double strand breaks by HR. E. coli, they induce the SOS response  to each type of lesions (Molecular Biology of the Cell). Omics data, however, showed that genomic alterations and their processing involve broader cellular responses such as cell cycle adaptations, metabolic changes or oxidative stress response for example . The Genresponse  that wilresponse .Streptomyces verticillus that targets primarily the furanose rings of DNA. In the presence of required cofactors (Fe2+ and O2), BLM directly causes both single-stranded and double-stranded DNA damage. DNA degradation by BLM is initiated by generating a free radical, in the deoxyribose. At low oxygen tension, oxidized abasic (AP) sites are favored while at high oxygen tension SS and DS breaks predominate  of both drugs. We found that the absence of RecN increased the pressure on the BER pathway while concomitantly reducing the importance of homologous recombination. TIS analysis also highlighted the importance of drug tolerance pathways such as efflux systems, oxidative stress management and cell cycle controllers for successful recovery from DNA alterations and how RecN activity moves the equilibrium between different solutions. More generally, this work illustrates that GSR is an integrated processes that cells deploy to create the conditions for their survival.E. coli, imaging of individual genomic loci revealed a short period of cohesion of the two newly replicated sister loci before segregation . In the WT strain, we observed that MMC treatment provoked a general decrease of RF (mean RF ≈ 6%) and presumably of SCI. In the absence of RecN this reduction was dramatic and almost no recombination was observed in the conditions of the assay  and decreased modestly in the recN mutant  and the recN mutant . In the presence of BLM, we observed a very high recombination frequency in the WT strain (RF ≈ 60%) but correlated with that of the untreated cells (PC WT/WT–BLM50 = 0.79). In the recN strain, by contrast, RF became very low (RF ≈ 5%) during the recovery period. Hi-SC2 analysis confirmed that RecN is required to maintain SCI in the immediate moments following MMC treatment; however, during the recovery phase of MMC-induced damage, RecN does not seem important to restore SCI. We also reveal that RecN does not play a major role during the initial BLM-induced damages’ phase but instead is required during the recovery phase of BLM-induced damages. These observations suggest that RecN intervenes at different time points of the repair strategies for MMC and BLM tolerance.In bacteria, chromosome segregation follows replication, leading to a complete segregation of the origins before the end of the replication round. However, in regation . Using aregation . Using tregation . Recentlregation ,b. We haregation . We obse strains  and did g window . In the gle loci . The WT C or BLM . 50 min recN mutant did not compact its nucleoid after the addition of MMC and filamented extensively (P = 0.00054) at time point 6 h and a large distribution of the average DAPI fluorescence in the nucleoid . The next day, we collected about 1 million colonies for each sample and extracted genomic DNA. We mapped about 10 million insertions in the genome of E. coli. The Normalized Number of Insertions (NIN) was measured for each gene of the genome for each replicate and condition. Component analysis revealed a significant dispersion of the replicates , mean Log2 FC <−1 and P-value <0.1, recN + MMC, recN + BLM). First, both WT and recN mutant’s survival to MMC and BLM depended on a cluster of genes linked to the BAM complex  and AcrB . In addition to AcrAB, TolC cooperates with other efflux systems MdtA, MdtB, MdtC, MdtEF, EmrABC, EmrYK, AcrE, and AcrF which mutants were less detrimental for survival in these conditions  methods, which combine genome-wide transposon mutagenesis with high-throughput sequencing allows the estimation of fitness contribution or essentiality of each genetic component in a bacterial genome. TIS gives the opportunity to decipher the pathways that led to WT and plicates . We obseplicates . This suplicates . Among t complex . This renditions . These oiability . The funrecN, recF, uvrABC, radA, smrA, and nfo genes. In the presence of BLM, this cluster changed, it contained recN, sbcB, nth, endA, XseA, and sbmC. The absence of recN did not change the dependence on uvrABC, recF, and radA but revealed new important genes: exoX and rep for MMC survival. The absence of RecN profoundly modified the gene set required for survival to BLM, it included recO, rep, vsr, and xthA.The second cluster of genes detected in the TIS data reflects DNA Damage Repair (DDR). Interestingly this cluster presented diverse members according to the conditions . In the dksA and relA), cell division , oxidative phosphorylation/oxidative stress  or extracellular appendages  suggesting that other cellular pathways were involved in genotoxic drug tolerance.We did not analyze further the other clusters revealed by String but we noticed the presence of genes involved in the stringent response (R2 = 0.87). The CFU of the mutants challenged with a 40 min treatment followed a linear regression with a slope = 0.50 and R2 = 0.80. Therefore, TIS data adequately revealed colony formation of MG1655 treated for identical times. Results for the BLM treatment were less convincing. At 20 min the slope for the linear regression was 0.33 with a R2 = 0.38 and at 40 min the slope = 0.25 with a R2 = 0.51. Spearman correlation coefficients, 0.53 and 0.65, respectively, at 20 and 40 min indicated that overall TIS and CFU were correlated although data did not follow a monotonous trend. CFU and TIS data of several individual genes correlated very well. For instance, both TIS and CFU showed the importance of UvrA in the presence of MMC but not BLM. In addition, the viability loss of acrA, pyrE, borD, and hflC deletion mutants after BLM treatment was comparable to the TIS results. Interestingly, we also observed gain of function of some Mariner insertions in the nuoA, fruK, and ybfE genes and their corresponding deletions. Altogether, these results validated the TIS analysis as a good predictive tool for genes involved in DNA damage tolerance and repair.To control TIS reliability, we constructed mutants of 20 selected genes in WT MG1655. We picked genes that presented TIS FC differences in MMC and BLM. First, we analyzed the gene set as a whole . The CFUrecA, ruvA,B,C, and priA,B for example (nfo (Endonuclease IV), nth (Endonuclease III), rarA and exoX presented important mean reductions (Log2 FCMMC–wt <−2) but with the larger deviations between replicates  and Nei (Endo VIII) when RecN was absent. Endo III and Endo VI, respectively, catalyze the first (glycosylase) and second (AP endonuclease) steps of the BER pathway of FappyA and Opyr  than in the WT (Log2 FCMMC–wt = −4.8). This is in agreement with previous observation in B. subtilis  were important for survival of the WT strain in both conditions. In addition, TIS revealed a role for SmrAB, EndA, RadA, SbcB (xonA), XthA, Nfi, and SbmC for the processing of BLM lesions in the WT strain. Obviously, we must also add RecA to this group , recC (Log2 FC BLM–recN = 0.49) and recD (Log2 FC BLM–recN = 1.17) displayed positive FC in the absence of RecN confirmed this hypothesis. Reckless DNA degradation by RecBCD might explain the poor survival of the recN mutant to BLM. The presence of SbcB and Nth in the RecN dependent group, and XthA and Nfi in the RecN independent group suggest that BLM-induced lesions also require a processing by the BER pathway. In addition, the dependence on the Rep helicase  and radA mutants and double mutants combined with recN deletion  and CFU data showed that MMC and BLM induced lesions require both HR and BER pathways, with RecN playing an important role in the flux or the outcome of these processes. Differently, NER only participates in the GSR accompanying MMC , 5A. Sur pathway . This pa pathway . This lereatment . Hi-SC2 ox assay  at a sinSCI loss . ImagingN mutant . Thus, iA mutant . Howevero the WT . By contM’s wash . Stabiliwith MMC . AltogetuvrA mutant. As observed for the WT and the recN strains, the AcrAB-TolC efflux system and its BAM assembly complex were crucial for survival (msrC and msrB two methionine-(R)-sulfoxide reductases . Mariner insertions in all of these genes are positively selected in the presence of MMC . TIS is a powerful approach that can be extensively applied to the genome-wide definition of loci that are required for bacterial growth under diverse conditions  the correlation between TIS data and CFU was very good  challenged with two drugs. This strategy allows us to propose an integrated model of the GSR that includes equilibrium changes in the different contexts  might explain the important increase of SCI that we observed in the recovery phase.In the presence of BLM, RecN activity was only visible later during the recovery phase. One possible explanation for this observation is that adequate single strand DNA substrates are not immediately available for RecN. BLM lesions produce double strand breaks that will be processed by RecBCD and covered by SSB and RecA. Since RecN is only induced at this stage, we speculate that it may function only after the initial homology search and D loop formation by RecA. At this timing, its loading on SS DNA could stabilize D loops as observed in vitro . ReplicaE. coli. Recently, a similar partnership was described for NER and TLS in non-replicating C. crescentus bacterium .Experiments were performed in LB  or on LB-agar (LB + 1.5% de bacto-agar). Viability assays were performed as described . MitomycPrecN-GFP or pFCCGI (ParaBAD-GFP) was diluted 1/200 in LB and grow until OD600 nm: 0.2 at 37° in a Tecan Spark plate reader. BLM or MMC was added at concentrations of 1 μg/ml or 5 μg/ml, respectively, with 0.1% arabinose when required. Western blot were performed as described  when required. The next day, colonies were recovered in 30 mL of LB. A culture of the Mariner library was set with a starting ODnm600 of 0.03 in 45 ml LB. The culture was grown at 30°C with agitation (150 rpm) until OD600 nm 0.15. When required the genotoxic agent (MMC 5 μg/ml or BLM 0.5 or 0 1 μg/ml) was added for 20 min. Cultured were immediately washed twice in fresh LB and cells were spread to 20 cm × 20 cm LB agar plates at 30°C. According to the drug and mutant considered different dilutions were used to reach the target number of colonies. Since BLM toxicity varies according to the lot number, we performed preliminary tests to adapt TIS protocol to these changes. The next day, ≈ 2 million colonies were recovered from each condition in 30 mL of LB and genomic DNA extracted. The sequencing libraries were constructed as described (Transposon insertion sequencing was performed as described  Mariner escribed . Sequencescribed  with theloxP sites were introduced by conjugation and transposition. The conjugation were performed between E. coli β-2163 pSWT23 (E. coli MG1655 carrying the recombination system OE2358 (WT), OE2360 (recN), and OE2361 (uvrA) at the lacZ site. Transposition library was obtained with the TIS protocol in presence of DAP (0.6 mM) and IPTG (0.1 mM) to repress Cre. One millions of colonies with independent LoxP cassette insertions were flash frozen at −80°C with 50% glycerol. Aliquots of the transposition library were placed on ice for thawing. Cells were grown to exponential growth phase (OD600: 0.2) from 108 cells diluted in 100 ml LB with IPTG (OD600: 0.05). Then 1 ml of culture is centrifuged and transferred into 40 ml of new culture medium without IPTG at 30°C under agitation 180 rpm. After 90 min, when OD600: 0.1 was reached, the genotoxic agent was added for 20 min. Three washes in LB were performed and either arabinose (0.1%) was added immediately for 60 min or after 50 min of recovery time in LB. Cells were harvested and genomic DNA extracted and processed for sequencing as described  camera. The acquisition was done with ZEN software and the processing and analysis of the images with Fiji software and its application MicrobeJ (An overnight culture was diluted 1/200 in LB. The cells were grown to an ODMicrobeJ . FiguresThe original contributions presented in this study are included in the article/AC designed, performed and analyzed the experiments, constructed the tools, and prepared the figures. EE and PZ designed, performed and analyzed the experiments. PS designed and constructed the tools. NQ constructed the tools and performed the experiments. EV designed and supervised the experiments. MM designed, performed and analyzed the experiments, and acquired funding. FXB designed and supervised the experiments, interpreted the results, acquired funding, and wrote the manuscript. OE designed, analyzed and supervised the experiments, interpreted the results, acquired funding, and wrote the manuscript. All authors contributed to the article and approved the submitted version.


Moreover, the chloride ion diffusion coefficient D is in accordance with the power function relationship with the wet and dry cycle time, and a time-varying model of chloride ion concentration on the surface of coral concrete is established. The surface chloride ion concentration of coral concrete reinforcement was modeled as a time-varying model; the cathodic zone of coral concrete members was the most active, increasing from 0 V to 0.14 V from 0 to 20 years, with a large increase in potential difference before the 7th year, and a significant decrease in the increase after the 7th year.The actual protective performance of the coated reinforcement in coral concrete was investigated by measuring the chloride ion diffusion coefficient, electrochemical analysis, and numerical simulation. The test results show that the corrosion rate of coated reinforcement in coral concrete under the action of wet and dry cycles is kept at a low level, and the Rp value is always greater than 250 kΩ·cm China’s marine and ocean-related businesses have experienced rapid growth as a result of the Belt and Road Initiative’s promotion of construction and the nation’s maritime defense strategy. Because of its better qualities, local availability, high efficiency, and economy, the coral reef has become an important building material for the infrastructure of offshore islands. However, the use of mixed seawater and the hostile maritime environment make steel corrosion a severe issue, reducing the service life of coral concrete structures significantly ,6,7,8,9.Therefore, steel coating is more cost-effective than stainless steel reinforcement and can also be used in conjunction with other corrosion protection techniques, such as rust inhibitors, among the various methods of protecting reinforcing steel from corrosion. It also has the advantages of being simple to use and protecting the environment. However, the majority of the present research on the preservation of coral concrete reinforcement focuses on the kinds of reinforcement used and rust inhibitors, and it is not quite clear how to best maintain CAC reinforcement coatings. To increase the strength of the structure and lengthen its service life, an in-depth study of the protective qualities of reinforcing coatings in CAC is crucial.In light of this, we conducted a test on the steel coating of coral concrete under dry and wet cycle regimes, investigated in depth the actual protection performance of steel coatings on coral concrete, and analyzed the process of coating failure by determining the chloride ion diffusion coefficient, electrochemical analysis, and numerical simulation. We sought to design a powerful analytical and computational model that can accurately depict the chloride ion infiltration process in coral concrete while protecting the reinforcing coating in a real-time marine environment.3, the bulk density was 928 kg/m3, the compressive strength was 1.6 MPa, the porosity was 55%, the natural water content was 0.1%, and the mud content was 0.58%. Coral sand with a fineness modulus of 2.5 was used as the fine aggregate; the laboratory-measured apparent density of the fine aggregate was 2450 kg/m3, the bulk density was 1163 kg/m3, the porosity was 55%, the natural water content was 0.1%, and the mud content was 0.58%. Following ASTM D1141-2013, we artificially prepared seawater, the main components of which are shown in The specimens were cubic 100 mm × 100 mm × 100 mm specimens. The coral concrete was made of Conch P-O 42.5 grade cement. The coarse aggregate was South China Sea coral reef with 5~16 mm continuous grading; the laboratory-measured apparent density of the coarse aggregate was 1865 kg/mThe dry and wet cycles of the ocean were simulated using artificial seawater, and the dry and wet cycles were simulated once a day with a dry-to-wet time ratio of 1:1, or 12 h of immersion and 12 h of drying. After the specimens were cured, the coral concrete specimens were sealed with paraffin wax on the rest of the surface except the working surface to test at 30 days, 60 days, 90 days, 120 days, 150 days, 180 days, 270 days, and 360 days. After removing the specimens, the concrete’s surface was cured. A hand drill with a 6 mm diameter was used to drill samples at depths of 0–5, 5–10, 15–20, 20–25, and 25–30 mm. After drilling each depth, we rapidly gathered the powder and used a brush to wipe up the residual powder in the hole to prevent the mixing of powder from various depths. The samples were dried in an oven for two hours, and after cooling, 5 g was weighed and put into a beaker with 250 mL of deionized water. The magnetic stirrer was then turned on and dynamically stirred, and a rapid chloride ion content detection tester was used to measure the free chloride ion content , as shown in After removing the coral concrete samples at 120, 180, 240, 300, and 360 days, electrochemical tests were carried out. For these tests, the saturated glycerol electrode served as the reference electrode, the coral concrete reinforcement that was to be tested served as the working electrode, and the platinum sheet electrode served as the auxiliary electrode of the three-electrode system. The components to be tested had to be immersed in saturated Ca(OH)x = 0 was substituted into this relational equation. The coral concrete specimen’s ambient temperature remained constant during the erosion stage; hence, the only factor affecting the chloride ion diffusion coefficient (D) was time (t). Using the least squares approach and the ORIGIN software fitting, the relationship curve between the free chloride ion concentration 2/s); The protective layer of reinforcement had a thickness of 30 mm, and to make data handling easier, powder samples at average depths of 2.5 mm, 7.5 mm, 12.5 mm, 17.5 mm, 22.5 mm, and 27.5 mm were taken and measured to collect information on the concentration of free chloride ions The It is evident from Based on the observed The chloride ion diffusion coefficient of coral concrete under both the dry and wet cycle regimes is obtained from the results in The polarization curves of bare and coated steel bars at various dry and wet cycle periods are shown in 2. In the dry and wet cycles after 180 days, the corrosion potential continued to move in a positive direction, indicating that the corrosion resistance of the coating improved while the corrosion rate remained low. For the epoxy-coated rebar in the dry and wet cycle at 180 days, the corrosion potential Ecorr moved in the negative direction, indicating that the corrosion resistance of coated rebar somewhat declined.Due to the coral aggregate’s porosity and the chloride ions in the water used in the concrete mix, the surface passivation coating of exposed reinforcement in coral concrete was in a more unstable state during the 360 days wet and dry cycle test than it was in silicate cement concrete. According to the polarization resistance value, it can be seen that corrosion began to occur at 360 days while the epoxy resin coating was still intact, demonstrating a better ability to protect against corrosion. Without the protection of a coating, corrosion will activate when the surface chloride ion concentration reaches the critical value.(a)Model BuildingThis model represents the portion from the outer surface of the protective layer to the surface of the reinforcement to mimic the electrochemical corrosion on that surface. By intercepting a 100 mm long CAC part with a reinforcement coating having a thickness of 1 mm and a protective layer of 30 mm, a simplified two-dimensional model of the coated reinforcement in the CAC was developed in relation to the work of Y. D. Yan . Figure (b)Model parameter settingA cubic current distribution with a Nernst–Planck interface was used in the COMSOL model. With reference to the study by Jiuxin Fang , the par2/d for corrosion media and T = 14 day for water to reach the substrate.For various times and various intrusion depths, the chloride ion content C can be calculated using Equation (3). According to Yingying Zhang’s study , the difSince reactant and product concentrations are not always the same and chemical reactions often take place in non-standard states, the electrode potential is a number that changes over time. The Nernst equation is typically employed in this situation to quantitatively express the electrode potential’s magnitude. Some researchers, such as Hussain R. R. , employe(c)Boundary conditions and initial conditions−, OH−, Fe2+, Na+, and Ca2+. For the movement of materials, the Nernst–Planck equation is employed, and for the corrosion of steel bars, the modified Tafel equation is used. An equation for the slope of the anodic Tafel reaction for steel corrosion was proposed by fitting the experimental data to rectify the anodic Tafel influence on the electrode reaction.(d)Boundary conditions and initial conditionsThe model employs the physical field control model, sets the cell size to the standard value, and dissects the concrete, coating, and other components one at a time using the free triangular mesh. The results of the dissection are displayed in To obtain the cloud map of chloride ion concentration distribution within the coral concrete and the potential distribution on the surface of the reinforcement, the corrosion age was set to 20 years. To explore the corrosion of coral concrete’s coated reinforcement in the marine environment, we analyzed the variation in parameters such as chloride ion diffusion coefficient with time by measuring the chloride ion content in coral concrete at different times and depths under dry and wet cycle regimes, and we performed a qualitative analysis of the corrosion of the reinforcement by electrochemical tests. Meanwhile, the protection model of CAC-coated reinforced concrete members in natural corrosion conditions at a fine scale was established based on COMSOL, and the following conclusions were obtained.(1)The diffusion law of chloride ions in coral concrete under the dry and wet cycle regimes is in accordance with Fick’s second law of diffusion, and a time-varying model of chloride ion diffusion coefficient in coral concrete was established based on several sets of experimental data, through which the chloride ion concentration on the surface of the reinforcement at any time under the dry and wet cycle regimes can be calculated. The Cs value of coral concrete in the dry and wet cycle regimes increased from 0.361% to 0.931% with time. The Cs value of coral concrete increased at a faster rate from 30 to 150 days, and after 150 days, the increase in Cs value continued to decrease and finally remained stable, which can help to predict the service life of coral concrete.(2)6 for coated reinforcement at the 360-day wet and dry cycle time is an order of magnitude greater than the Rp value of 3.14 × 105 for bare reinforcement. The epoxy resin coating remained in the uncorroded state and showed better protection under the dry and wet cycle regimes for one year.The electrochemical test results show that the corrosion of exposed reinforcement in coral concrete started at 360 days, and that the corrosion resistance of coral concrete without anti-corrosion measures is poor. The Rp value of 3.36 × 10(3)The protection model of CAC-coated reinforced concrete members in natural corrosion conditions at a fine scale was established based on COMSOL. The cathodic zone of the member reacted the most actively, and the potential difference between the cathodic and anodic zones first showed an increasing trend and then decreased with time. It increased from 0 to 20 years from 0 V to 0.14 V, with a large increase in potential difference up to year 7 and a large decrease after year 7.


We aimed to formulate a consensus for the therapeutic utilization of antibiotics based on contemporary evidence and the real-world experiences of the clinicians at the forefront of the care of patients with urinary tract infection (UTI).n=397), across India (PRISM Survey group), rated their level of agreement with 11 questions with each item on a five-point Likert scale and 5 objective response questions. The consensus was pre-defined if the weighted mean score for the Likert scale was >100. Data were statistically analysed by GraphPad software version 9.5.0.We developed customized technological response system for mapping exercise and panel of eminent specialists was convened. Prior consent was obtained, and the weblink of the questionnaire was provided. Sub-expert nationwide panel , and cumulative clinical experience was 3669 person-years. The predominant clinical practice setting of the respondents was a public hospital (58.6%). The highest agreement score in the decreasing rank order (of adjusted weighted mean score) for UTI were: antibiotic resistance is a major challenge (126.1), oral fosfomycin-based regimens are effective against MDR pathogens (123.4), is a good option for bacterial biofilm reduction (121.7), the potential to manage recurrent lower UTI (121.6), oral fosfomycin along with nitrofurantoin is been useful to manage MDR UTI (106.8), nitrofurantoin and fosfomycin are chosen as empirical treatment (103.7), fosfomycin has stood the test of time (120.2). Adjusted mean response scores  for consensus were: agree  followed by strongly agree , neither agree nor disagree , disagree , strongly disagree .In the era of MDR UTI, time-tested oral fosfomycin and nitrofurantoin can improve management of UTI without increasing the complexity.


In-situ synchrotron X-ray diffraction reveals a unique temperature-dependent reversal of CO2 and C2H2 adsorption affinities on CUK-1, which is validated by gas sorption and dynamic breakthrough experiments, affording high-purity C2H2 (99.95%) from the equimolar mixture of C2H2/CO2 via a one-step purification process. At low temperatures (<253 K), CUK-1 preferentially adsorbs CO2 with both high selectivity (>10) and capacity (170 cm3 g−1) owing to the formation of CO2 tetramers that simultaneously maximize the guest-guest and host-guest interactions. At room temperature, conventionally selective adsorption of C2H2 is observed. The selectivity reversal, structural robustness, and facile regeneration of CUK-1 suggest its potential for producing high-purity C2H2 by temperature-swing sorption.The interactions between adsorbed gas molecules within porous metal-organic frameworks are crucial to gas selectivity but remain poorly explored. Here, we report the modulation of packing geometries of CO Guest clusters within confined nanospaces have a significant impact on molecular recognition. Here authors highlight the potential to systematically control gas-cluster rearrangement, leading to tunable sorption and separation behaviour in a MOF. The optimization of cooperative interactions, such as electrostatic interactions and hydrogen bonding, plays a crucial role in the design of efficient molecular recognition systems, particularly in porous materials. These cooperative interactions are essential for achieving high performance in gas adsorption, sensing, and catalysis applications17. On the other hand, guest-guest interactions or the formation of guest clusters also play an important role in molecular recognition. However, the direct observation and control of guest-guest interactions within confined nanovoids of porous materials is highly challenging and remains poorly explored20. Screening new host-guest and guest-guest interactions can promote the design of new functional porous materials21.Host-guest chemistry is fundamental to the selectivity of many molecular recognition systems27. In particular, the modular nature and reticular structure endow ultramicroporous MOFs with the possibility to precisely control the host-guest and guest-guest interactions within the pores29. Great advances in host-guest chemistry have been achieved in ultramicroporous MOFs with tailor-made properties for gas adsorption and separation, owing to the confinement effect from the strong host-guest interactions32. Currently, the major interest in gas adsorption and separation using ultramicroporous MOFs is focused on enhancing recognition selectivity by tuning the host-guest interactions36. This is pronounced for selective adsorption of acetylene (C2H2) from carbon dioxide (CO2), as C2H2 is one of the most important industrial precursors, and the CO2 contaminant would be coproduced during the production of C2H2 via partial combustion of natural gas36. However, the understanding of the impact of guest-guest interactions or guest clusters on selectivity remains lacking due to the difficulties in the direct observation of such dynamic and weak interactions.Ultramicroporous metal-organic frameworks (MOFs), featuring highly inerratic porosity, tunable pore chemistry, and designable structures, provide a unique platform to explore host-guest interactions2 and C2H2 within the robust ultramicroporous M-CUK-1  materials. The guest-guest interactions and binding domains within CUK-1 with different metal nodes have been observed by in-situ synchrotron X-ray diffractions and molecular simulations. The efficient packing of well-organized CO2 clusters with T-shaped dimers gives rise to notably higher crystallographic occupancy and capacity of CO2 (106 vs. 86 cm3 g−1 of C2H2 in Co-CUK-1 at 298 K), while the stronger host-guest interactions between C2H2 and CUK-1 at room temperature lead CUK-1 to preferentially adsorb C2H2 over CO2  and clear sorption inversion of CO2 over C2H2. Such an inverse CO2/C2H2 adsorption behavior is more desirable for industrial production of C2H2 via a one-step CO2 adsorption process but is rarely investigated40. The temperature-dependent reversal of sorption behavior for CO2 and C2H2 is demonstrated by gas sorption isotherms and dynamic breakthrough experiments at various temperatures. High-purity C2H2 (99.995%) can be directly obtained in a one-step process, and the low energy input for the regeneration suggests that CUK-1 is a promising adsorbent for C2H2 production via the temperature-swing adsorption (TSA) process.Herein, we report the modulation of geometries of guest-clusters as a function of temperature Fig.  for the 2pdc) and M2+-containing salts  with KOH in water at 210 °C for 24 h43. The CUK-1 materials are isostructural. The edge- and vertex-sharing M3(µ3-OH)2 chains serve as undulating pillars connecting the 2,4-pdc ligands in an orthogonal fashion, forming a ‘wine-rack’ topology with one-dimensional diamond-shaped and corrugated channels  were hydrothermally synthesized by reacting 2,4-pyridinedicarboxylic acid  at 298 K indicate the preferential adsorption of C2H2 at low pressure but higher saturation capacity of CO2 upon increasing the pressure , which notably exceed those of C2H2 . The densities of adsorbed CO2 molecules  in Co-, Ni-, and Mg-CUK-1 at 233 K were estimated to be 1.40, 1.27, and 1.25 g cm−3, respectively. Notably, these densities are higher than that of liquid CO2 (1.1 g cm−3) but lower than that of dry ice (1.55 to 1.7 g cm−3)44, indicating the highly efficient packing of CO2 in the pores. However, the densities of adsorbed C2H2 molecules were recorded as only 0.56, 0.50, and 0.45 g cm−3 in Co-, Ni-, and Mg-CUK-1, respectively, lower than that of liquid C2H2 (0.69 g cm−3)45. At 253 K and 233 K, there is a clear inversion in the adsorption selectivity from C2H2 to CO2 on the CUK-1 materials. The uptake gap between CO2 and C2H2 at 0.5 bar on Co-CUK-1 can reach 40 and 45 cm3 g−1 at 253 and 233 K . At 298 K, CUK-1 only shows a moderate C2H2/CO2 selectivity of ca. 2. However, at 233 K, CUK-1 exhibits the inversed CO2/C2H2 selectivity of 9.5, 8.4, and 12.1 for Co-, Ni-, and Mg-CUK-1, respectively (bpe)] (9)46, Ce(IV)-MIL-140-4F (9.6)37, PCP-NH2-ipa (6.4)35, and SIFSIX-3-Ni (7.5)29, but lower than the benchmark material Cu-F-pymo (> 105)38. Furthermore, the isosteric heats of adsorption (ΔHads) of CO2 on Co- and Ni-CUK-1 were calculated to be 20.8 and 21.7 kJ mol−1, respectively 35, [Mn(bdc)(bpe)] (29.5 kJ mol−1)46, MUF-16 (32 kJ mol−1)39, and Tm2(OH-bdc) (45 kJ mol−1)40.State-of-the-art Cely Fig. . The invF-pymo > 538. Furt2- and C2H2-loaded CUK-1 materials were collected as a function of temperature  in Co-CUK-1 is in excellent agreement with that obtained from the isotherm (2.07 C2H2 per cell). C2H2 molecules at site I locate almost perpendicular to μ3-OH groups, forming O-H⋯πC2H2 H-bonds , supplemented by additional interactions via C-HC2H2⋯Oligand H-bonding  and πC2H2⋯Hligand (3.44–3.67 Å) interactions. Moreover, at high loading, the neighboring C2H2 molecules synergistically interact with each other through multiple HC2H2⋯πC2H2 interactions , forming the tetramer-clusters of C2H2 , but no interactions between CO2 and the ligand of CUK-1 were observed. CO2 molecules at site II interact with the pore surface via weak O⋯Hligand interactions  running along the channel were formed via strong guest-guest interactions . Notably, the neighboring CO2 molecules exhibit a head-to-center (C = O⋯C) geometry , indicating the high capacity of Co-CUK-1 for CO2 at 233 K compared with that for C2H2. This is entirely consistent with the isotherms. C2H2 molecules at site I interact with bridging μ3-OH groups via πC2H2⋯H-O H-bond (2.96 Å) that is supplemented by weak C-H⋯Oligand H-bonding  and C-OCO2⋯Hligand interactions , similar to that of CO2 in the channels at 298 K. However, CO2 molecules are located in the corner of the pore channels and stabilized by multiple weak host-guest interactions , thus leading to the strong binding affinities of host framework for CO2. Meanwhile, in Co-CUK-1, C2H2 clusters are formed with C2H2 molecules via πC2H2⋯πC2H2 interactions  with the head-to-center configurations, forming the quasi-T-shaped geometry  in Co-CUK-1. Similar CO2 clusters with quasi-T-shaped dimers were also observed in Ni-CUK-1 at 233 K  were further estimated by first-principles density functional theory (DFT) calculations , directly validating the preferential adsorption of CO2 over C2H2. There is a subtle difference in host-guest interactions when varying the metal nodes in CUK-1 . To mimic the industrial processes for C2H2 production, we further studied a gas mixture of CO2/C2H2 (1/2). A complete inversed CO2/C2H2 separation was realized with CO2 retained in the fixed bed for a longer duration  can reach 62 and 41.7 L kg−1 on Co-CUK-1 and Mg-CUK-1, respectively, much higher than that on MUF-16 (27 L kg−1)39 and Cu-F-pymo (3.7 L kg−1)38. It is worth noting that these materials show excellent cycling separation performance and can be easily regenerated by purging helium (He) at 298 K  obtained in a one-step process. Furthermore, the fixed-bed packed with CUK-1 can be easily regenerated at room temperature by purging an inert gas, indicating that the TSA process using CUK-1 materials is highly efficient for C2H2 production.In summary, we report the direct observation of packing geometry rearrangement of gas clusters as a function of temperature to control the adsorption selectivity of CO2 and C2H2 sorption isotherms were collected at different temperatures on a Micromeritics ASAP 2020 instrument equipped with commercial software for data calculation and analysis. The test temperatures were controlled by soaking the sample cell in a circulating water bath (298 K), ice/methanol mixture (233–273 K), dry ice/acetone mixtures (196 K), or liquid N2 (77 K). Before measurement, the sample (80–100 mg) was degassed at 423 K for 24 h. The breakthrough experiments were performed in a stainless-steel fixed bed (4.6 mm inner diameter × 50 mm length) packed with ~0.6 g of CUK-1 powder. Before the breakthrough experiment, the fixed bed was heated at 423 K under a flow of He for complete activation. The fixed bed was then cooled to room temperature and immersed in a water/methanol bath with different temperatures. Then, the gas mixtures (C2H2/CO2) were introduced, and the outlet gas was monitored by mass spectrometry .CO2H2 or CO2 was introduced into the capillary, and diffraction data were collected after one-hour stabilization. Data were measured between 0 and 35° with a 13-channel multi-analyzer stage under the wavelength of 0.354267(4) Å. Data were binned using a step size of 0.002°. For samples measured under 298 K, high-resolution powder X-ray diffraction patterns were collected on the powder diffractometer (λ = 0.825829(1) Å) at room temperature on beamline I11 . C2H2 or CO2 was dosed offline and then sealed for measurement. Data were collected between 0 and 150° using a step size of 0.001° with five multi-analyzing crystal (MAC) detectors without further re-binned.Fresh samples of Co-CUK-1 or Ni-CUK-1 were pre-activated under a dynamic vacuum at 200 °C, then loaded into a 0.7 mm borosilicate capillary under an inert atmosphere. Then the capillary was further activated by heating to 100 °C under a dynamic vacuum for 2 h before cooling down to room temperature. For samples measured under 233 K, synchrotron X-ray powder diffraction was carried out on the ID22 high-resolution powder diffraction beamline at the European Synchrotron Radiation Facility (ESRF). Cx, y, z) and isotropic displacement factors for all atoms except hydrogen, and the site occupancy factors (SOF) for guest molecules. The accuracy of the final model was verified by the convergence of the weighted profile factor (Rwp), the chemical sense of the model, and the good correlation between the observed and calculated diffraction patterns.Pawley and Rietveld refinements of the structure were carried out using the TOPAS software package (roughly between 18–0.90 Å in d-spacing). Due to the high flexibility of the framework, index with constraints was used to get the information on cell parameters and space groups. Stephen fitting was applied to describe the diffraction peaks and their anisotropic broadening. Approximate positions of the guest molecule under a rigid body model were found using the simulated annealing approach before further refinement was used to find the optimal orientation of the guest molecules. The final refined structural parameters include cell parameters, the fractional coordinates (Supplementary InformationPeer review file


Background: Antibiotic resistance is one of the biggest threats to global health, and by 2050 it is expected to cause 10 million deaths per year globally. Sex differences depend on context and sociodemographic factors; therefore, studies addressing sex differences have been inconclusive. Furthermore, to our knowledge, sex differences in the Puerto Rican population have not been analyzed. We sought to understand whether knowledge and practices regarding antibiotic use and antibiotic resistance in the Puerto Rican population differ by sex. Methods: A convenience sampling was performed at outpatient clinics across Puerto Rico. Those who agreed to participate completed a self-report questionnaire aimed to address demographics, antibiotic knowledge, and experiences. Bivariate analyses were performed using Stata version 17.0 software. Results: In total, 252 participants received the questionnaire, and 250 completed it. Most of the participants were female (71.2%), aged >56 years (40.0%), and had a high school diploma (40.4%). Women had 2.71 . Conclusions: Women perceived themselves to be more knowledgeable regarding antibiotic use and resistance than men. However, no difference in actual knowledge could be identified. Similarly, antibiotic-related practices did not differ by sex except for using previously saved antibiotic treatment, and men had higher odds of conducting this practice. Further studies should be conducted to understand the factors that influence these behavioral practices, and educational interventions should focus on addressing misconceptions regarding antibiotics and antibiotic resistance.Disclosures: None


Affected by the erosive environment, tunnel lining concrete in the long-term service zprocess often exhibits engineering diseases such as concrete corrosion degradation and loss of strength, decreasing the stability of the tunnel lining structure and the traffic safety. Based on HTG tunnel project, the basic distribution rule of tunnel lining corrosion and macro mechanical properties of corroded concrete were explored in this paper through engineering disease site investigation. Then, on this basis, aiming at large-scale corrosion of tunnel lining structure, two reinforcement and repair schemes are proposed, corrugated steel plate reinforcement method and channel steel reinforcement method. Indoor component tests are carried out on the two reinforcement schemes. The failure characteristics and stress and deformation law of tunnel lining members after reinforcement and repair were verified. The analysis showed that the failure process of the reinforced specimens on the tensile side could be divided into the non-cracking stage and the working stage with cracks, and the cracking load and failure load of the specimens were significantly increased. The bearing capacity of the reinforced specimens was divided into the ultimate bearing capacity against cracking and the ultimate bearing capacity during failure. Finally, the calculation methods of the bearing capacity of the channel steel reinforcement method and the corrugated steel plate reinforcement method were derived. Comparative analysis shows that the results of numerical simulation, experimental testing and theoretical simplification methods are close to each other, and the maximum deviation is less than 8%. The established method for calculating the bearing capacity of corroded components after reinforcement is reliable and can be used for the design calculation of corroded lining reinforcement. By the end of 2020, there were 21,316 road tunnels 15,285 km) and 16,798 railroad tunnels  built in China ,5. In pa,285 km aFor the reinforcement and repair technology of corrosion-deteriorated tunnel lining structure, Britain, the United States and other countries have performed relevant studies earlier, and proposed many practical local reinforcement and reinforcement schemes. For example, Asakura et al.  used higHowever, for the large area corrosion deterioration of plain concrete lining structure, due to the fact that the lining concrete has lost its structural strength within a certain thickness range, it is impossible to paste fiber material or anchor steel plate on the surface of the lost strength during actual repair. Hence, it is often necessary to chisel out the severely corroded part before the next step of reinforcement construction. Meanwhile, the mechanical conversion mechanism and design method of the lining structure after reinforcement and repair are still relatively vague, In the actual construction, the repair design scheme is mostly determined by the method of empirical judgment, and the reliability and economy of the design lack of rigorous theoretical basis.To this end, this paper relies on the HTG tunnel project, firstly, through the disease site investigation, to grasp the basic distribution law of the tunnel lining corrosion and the macro mechanical properties of corroded concrete. Further, on this basis, for the large area of corroded tunnel lining structure, two types of reinforcement and repair solutions are proposed: corrugated steel plate reinforcement method and channel steel reinforcement method. Then, indoor component tests were carried out on the two reinforcement schemes to investigate the damage characteristics, force deformation law of the lining components after reinforcement and repair. Finally, the calculation method of the bearing capacity of the corroded tunnel lining structure after reinforcement was established.The research team went to the site several times to investigate and detect the engineering diseases of the HTG tunnel. Field investigation and analysis found that the main damage types of tunnel lining concrete are: leakage, salt corrosion damage, concrete carbonization, weathering and spalling, etc. .(1) Water quality tests showed that the measured sulfur dioxide concentration in the groundwater of the HTG tunnel exit section was as high as 618.9 mg/L, and the environmental action level of the concrete structure was V-C, which is a severe chemical erosion environment ,27.(2) No anti-sulfate erosion cement was used in the actual construction, and the lining concrete showed serious corrosion deterioration under the effect of sulfate erosion for many years. Statistically, a thick layer of salt crystals attached to the concrete surface (width about 0.5–2 m) existed almost every 2–3 m within the 100 m long range of HTG tunnel exit, and the concrete on the lining surface was swollen and collapsed, with serious loss of strength ,26,28,29(3) The results of on-site drilling and coring showed that the concrete in the severely corroded area could no longer form a complete core sample after being disturbed by the drilling rig. The cementing material inside the core was seriously lost, and the concrete was densely filled with holes and soil particles brought by groundwater, the material completely lost strength, the maximum corrosion depth of about 20 cm, as shown in After large-scale corrosion of tunnel lining, the strength of concrete decreases, which weakens the overall stability of tunnel lining structure ,31. TherChannel steel reinforcement method. In this reinforcement scheme, the corroded part of the concrete lining is first chiseled away, and then the structure is reconstructed with channel steel and concrete to achieve structural replacement and strengthening. In this case, the channel steel is fixed on the uncorroded concrete by expansion bolts, and then the slightly expansion concrete ,31 is poCorrugated steel plate reinforcement method. The program is to cut out the corroded concrete after the installation of corrugated steel plate, with a special location of rivets, anchor bolts and concrete filling between the steel plate and the existing lining structure, so as to achieve the corrosion of the inner lining structure of the application, reinforcing and strengthening the overall lining structure, as shown in Considering the actual conditions of the relying project (only plain concrete lining) and the structural force characteristics, two types of reinforcement models were designed as shown in Meanwhile, considering the test requirements, five eccentric compressive members were made for the two types of reinforcement schemes, including two reinforcement specimens by channel method, two reinforcement specimens by corrugated plate method and one plain concrete specimen (control of reinforcement effect). Specific specimen parameters are shown in 3, particle size 5–10 mm and the fine aggregate was natural yellow sand with fineness modulus 2.7. The admixture was polycarboxylic acid high efficiency air-entraining water-reducing agent and calcium sulfoaluminate expansion agent. The mixing water was tap water. After maintenance and testing, the average uniaxial compressive strength of the cubes was measured to be 36.3 MPa.The original concrete was poured with C30 commercial concrete, and the measured average uniaxial compressive strength of the cube was 34.1 MPa. The repaired concrete was made of slightly expansion concrete, and the mix ratio is shown in In addition, to ensure the connection between the reinforced steel plate and concrete, rivets or expansion bolts are set behind the reinforced steel plate, respectively, as shown in As shown in In After the specimen and its measuring instrument are installed in place, the oil delivery valve is slowly opened for preloading (about 20% of the estimated limit load), and the working state of the measuring instrument is observed to be normal. After confirming the correctness, the test piece is unloaded and cleared for formal loading. Press readings were loaded at a rate of 0.3 kN/s until 80% of the estimated ultimate load was reached, then reducing to 0.1 kN/s until complete failure of the specimen.(1)At the initial stage (before cracking), the specimen material is in the elastic stage, and the deflection in the column increases linearly with the load until the concrete in the tensile area cracks, at which time the separation of steel plate and concrete occurs in the corrugated steel plate reinforcement method. Thereafter, the specimen enters the working stage with cracks, its cross-sectional stiffness decreases as a whole, the tensile stress is continuously provided by the channel steel or corrugated steel plate, and the concrete stress on the compressed side increases rapidly.The cracking loads of the channel method and corrugated steel plate method reinforced specimens reached 415.6 kN and 556.8 kN, respectively, which increased by 72% and 130.5% compared with the unreinforced plain concrete specimens. After the development of the working stage with cracks, the breaking loads of the channel method and corrugated steel plate method reinforced specimens were 797.2 kN and 823.7 kN, respectively. The bearing capacity was increased by 2.3 times and 2.4 times of that of the plain concrete, respectively.The deflection in the column of the specimens reinforced by the channel method and the corrugated steel plate method at the tensile side was 3.85 mm and 4.27 mm, respectively, while the deflection at the unreinforced specimen was 2.55 mm, which shows that the deformation performance of the specimens reinforced by the tensile side was also improved.The load–deflection curve of the reinforced specimen on the tensile side shows an overall two-stage evolution relationship, as shown in (2)Plain concrete specimen: when the load reached 241.6 kN, the test load dropped rapidly, and a crack with a penetration depth of 16 cm appeared on the tensile side of the specimen, and the concrete lost its load-bearing capacity by tensile cracking.Channel steel method of reinforced specimens on the compression side: before the specimen was damaged, the testing machine screen load value continued to rise, and there are no cracks on the concrete surface. When the load reached 271.3 kN, the testing machine screen load rapidly declined. Meanwhile, the test specimen tensile side presents a crack with the depth of 25 cm; the test specimen tensile zone concrete reached the ultimate bearing capacity cracking, and the concrete in the compression zone did not see crushing and spalling.Corrugated steel plate method of compression side reinforcement specimen: the damage process is similar to the channel steel method of compression side reinforcement specimen, and when the load reaches 263.8 kN, the tensile area of the specimen cracks and destroys.The load–deflection curves of the reinforced specimens on the compressive side showed an overall linear variation relationship, as shown in (3)EI is the flexural stiffness; N is the axial load of the eccentrically compressed member; e is the loading eccentricity of the specimen; l is the height of the specimen; and f is the lateral deflection of the central section of the specimen.After the corrosion of tunnel lining, the local stiffness of the lining decreases, and stiffness changes affect the overall structure of the lining internal force distribution, which often leads to the increase in the bending moment of adjacent areas of the corroded lining, and further affects the structural safety of adjacent parts. The ratio of the load to deflection value at the moment of damage of the specimen is defined as its stiffness, that isFrom the analysis, it can be seen that:Thus, according to the experimental results, the flexural stiffness of the specimen at the peak load point of different repair schemes can be obtained, as shown in The analysis shows that compared with the unreinforced plain concrete specimen, the flexural stiffness of the specimen increased by more than 1 times after reinforcement by the channel method or corrugated steel plate method on the tensile side, respectively, and the reinforcement effect was significant ,30. HoweN reached 415.6 kN in the tensile side of the reinforced specimen by the channel method, resulting in the measured data of strain gauges S1 and S2 not truly reflecting the strain of the internal channel steel. The strain data at a height of 50 cm in the cross-section were replaced with the data measured by strain gauges S2′ affixed to the waist of the channel steel to describe the strain after the channel steel had assumed the full tensile stress. As seen from the figure, the axial strain of the section in the specimen column basically follows a linear distribution before cracking [(1) Cracks appeared on the tensile side of the specimen after the bias load cracking . After t(2) In the process of loading the tensile side reinforced specimen with corrugated steel plate method, the cracking load is 627.2 kN. The axial strain of the column section of the specimen before cracking is basically in line with the linear distribution, meeting the assumption of flat section. The corrugated steel plate, repaired concrete and corroded concrete work well together, and the ultimate bearing capacity is 823.7 kN.με, and the specimens exhibited brittle tensile damage characteristics.(3) The axial strains in the column section of the three specimens, namely, the reinforced specimen in the compression side of the channel method, the reinforced specimen in the compression side of the corrugated steel plate method and the unreinforced plain concrete specimen, are basically distributed linearly and can satisfy the assumption of flat section. When the specimens reached the ultimate load, the concrete strain values at the edge of the tensile zone were all about 100 According to the analysis of test results in It can be seen from the test data in (1) The eccentricity of the specimen should be not less than 0.2 times of the height of the section.(2) The average strain of the section varies linearly along the horizontal height direction, satisfying the assumption of flat section.(3) The corroded concrete is well bonded to the reinforcement and repaired concrete, which can coordinate deformation and work together. For the reinforced repaired specimen, when the concrete strain at the edge of the tensile zone reaches 300 µε, the specimen concrete cracks, after which the concrete on the tensile side withdraws from the bearing work and the tensile stresses is all provided by the channel steel or corrugated steel plate.(4) When the specimen reaches the ultimate bearing capacity, the tensile side of the channel steel or corrugated steel plate does not reach the yield strength and the edge strain of the compressive zone is 2500 µε at this time.(1) Calculation of cracking bearing capacityThe experiment shows that when the tensile zone of concrete reaches the limit tensile strain When cracking of the specimen, the concrete in the tensile zone already has a plastic development zone, and the tensile stress is distributed along the horizontal cross-section in a trapezoidal shape with the maximum stress h is the leg length of the channel, as shown in Thus, according to the strain geometry relationship shown in h is the cross-sectional thickness of the tunnel lining; b is the longitudinal width of the tunnel lining.In Further, according to the balance of forces, it is obtained by, respectively:Jointly (2) and (3) can be obtained as follows.N and Form (4) is a binary equation with (2) Calculation of ultimate bearing capacityChannel reinforced specimen damage, away from the near axial force side of the tensile area of the concrete has cracked, tensile stress is fully assumed by the channel. However according to the test, the channel has not yielded at this time, the tensile stress can be expressed as Similarly, according to the strain geometry relationship and the balance of forces, we can get:By solving the above equation, the calculation formula of section bearing capacity of the component strengthened by channel steel can be obtained, as shown in Equation (6). Then, the ultimate bearing capacity of the specimen reinforcement by channel steel can be obtained by substituting relevant parameters.When the corrugated steel plate is used to repair the tunnel lining, it deforms with concrete through the anchor bolt nails, and its damage process also includes two critical states: cracking moment and overall failure moment, and its stress mode is roughly the same as the effect of corrugated steel plate repair, as shown in e is the distance from the point of action of the axial force to the concrete joint point of the tension zone,Referring to the derivation method in In order to compare and analyze the reliability of the simplified design method derived in In the model, only the elastic working state of steel is considered, and only the ideal elastic material is considered. The isotropic elastic damage model is adopted for concrete materials and is combined with isotropic tensile or compressive plasticity to simulate the inelastic behavior of brittle materials such as concrete, as shown in In the numerical model, whether the specimen is cracked or not can be judged according to the strain value of the tensile side and the damage factor for the bearing capacity of the component when it is cracked. For the ultimate bearing capacity of the specimen when it was damaged, the maximum axial force value in the loading process was directly read, as shown in The relevant calculation results are shown in (1) Program I: channel steel method of reinforcement (corrosion depth of 10 cm)N of this section is 531 kN, the bending moment M is 78.5 kN·m, which is an eccentric compressive member with large eccentric distance. The length of the element is analyzed along the longitudinal line, that is, the cross-section size of the eccentric compression member is 1 m × 0.45 m. Channel steel type selected GB 18#B, steel type Q345.The channel steel is connected with the existing lining through expansion bolts, and the slightly expansion concrete C30 is poured at the site where the corroded concrete is chiseled. The relevant calculation parameters are shown in For the large area sulfate corroded tunnel with corrosion depth of 0–10 cm, channel steel with repair concrete was used to strengthen and repair the corroded parts. The design control section is selected from the section at the minimum value of safety factor at the location of the side wall, the axial force Mcr = 360 kN·m. That is, when 18#B channel steel is used to reinforce and repair the lining, the cracking moment of the lining increases to 360 kN, which is much larger than the lining moment value of 78.5 kN·m at this moment, and the lining cross-section retains 3.6 times of safety margin, so it can be seen that the program is feasible.After corrosion deterioration of the tunnel lining, the axial force of each part remains almost constant , and the(2) Program II: corrugated steel plate method (corrosion depth of 20 cm)sgA = 0.0067 m2; elastic modulus of steel plate Es = 2.06 × 105 MPa.For the large area sulfate corroded tunnel with a corrosion depth of 10–20 cm, a corrugated steel plate can be used to reinforce and repair the corroded parts. The design control section selects the section at the minimum safety factor of the side wall position. The axial force N of this section is 527 kN and the bending moment M is 87.5 kN·m, which is an eccentric compressive member with a large eccentricity. The length of the element is analyzed along the longitudinal line, that is, the cross-section size of the eccentric compression member is 1 m × 0.45 m. The corrugated steel plate is made of Q345 steel with a thickness of 5 mm. The steel plate is processed into a corrugated shape by a hydraulic bending machine, and the micro-expanded concrete C30 is poured at the part where the corroded concrete is chiseled. The relevant calculation parameters are as follows: the cross-sectional area of the steel plate Mcr = 458 kN·m. That is, after using a 5 mm thick corrugated steel plate to reinforce and repair the lining, the bending moment of lining cracking increases to 536.5 kN, which is much larger than the bending moment value of lining at this moment of 87.5 kN·m, and the lining section retains 5.1 times of safety margin, and the scheme can play a better role in reinforcing and repairing.After the tunnel lining is corroded and deteriorated, the axial force of each part is almost constant, and the bending moment value increases with the increase in the corrosion degree, which leads to the continuous increase in the eccentric distance of the lining, and the tensile side faces the risk of being pulled apart and cracked. According to the specification, when the eccentricity (1)Based on the HTG tunnel project, the basic distribution pattern of HTG tunnel lining engineering diseases and macro mechanical properties of corroded concrete were mastered. The results show that: HTG tunnel is located in a severe chemical erosion environment, the measured sulfur dioxide concentration is as high as 618.9 mg/L. Affected by the erosion environment, the tunnel lining surface concrete is swollen and collapsed, with serious loss of strength, the measured concrete compressive strength is 17–24 MPa, which has influenced the overall stability of the lining structure.(2)According to the site survey and the existing engineering experience, the corrugated steel plate or channel steel method reinforcement plan was designed and indoor tests were conducted, respectively. The test results showed that the damage process of the specimens reinforced on the tensile side could be divided into the uncracked stage and cracked working stage, and the cracking load and damage load of the specimens were significantly improved. Compared with the unreinforced plain concrete specimens, the tensile stiffness of the members could be significantly improved by using the channel steel method or the corrugated steel plate method on the tensile side.(3)After analyzing the test results of the reinforced specimen, the stress characteristics and damage process of the reinforced specimen are obtained. The bearing capacity of the reinforced specimen is divided into the cracking limit bearing capacity and the limit bearing capacity at the time of damage, and the bearing capacity calculation methods of the channel reinforcement method and the corrugated steel plate reinforcement method can be deduced. The results of comparison and analysis show that: the results of numerical simulation, experimental test and theoretical simplification method are close to each other, and the maximum deviation is less than 8%. The established method of calculating the bearing capacity after reinforcement of corroded members is reliable and can be used in the design calculation of corroded lining reinforcement.For the plain concrete lining structure with large area corrosion and deterioration, the existing reinforcement methods cannot meet the needs. The lining concrete has lost structural strength within a certain thickness range, and it is impossible to paste fiber materials or anchor steel plates on the surface of the lost strength during the actual repair, so it is often necessary to chisel out the severely corroded parts before the next step of reinforcement construction. The mechanical transformation mechanism and design method of the reinforced and repaired lining structure is not complete. In the actual construction, the repair design scheme is mostly determined by the method of empirical judgment. The reliability and economy of the design lack of rigorous theoretical basis. From this investigation, the following findings may be drawn:


Antibiotic persistence (subpopulation tolerance) occurs when a subpopulation of antibiotic sensitive cells survives prolonged exposure to a bactericidal concentration of an antibiotic, and is capable of regrowth once the antibiotic is removed. This phenomenon has been shown to contribute to prolonged treatment duration, infection recurrence, and accelerated development of genetic resistance. Currently, there are no biomarkers which would allow for segregation of these antibiotic-tolerant cells from the bulk population prior to antibiotic exposure, limiting research on this phenomenon to retrograde analyses. However, it has been previously shown that persisters often have a dysregulated intracellular redox homeostasis, warranting its investigation as a potential marker for antibiotic tolerance. Furthermore, it is currently unknown whether another antibiotic tolerant subpopulation - viable but non-culturable cells (VBNCs), are simply persisters with extreme lag phase, or are formed through separate pathways. VBNCs similarly to persisters remain viable following antibiotic exposure, however, are not capable of regrowth in standard conditions.E. coli cells on a single-cell level. [NADH:NAD+] was used as a proxy for measuring intracellular redox homeostasis and respiration rate.In this article we employed an NADH:NAD+ biosensor (Peredox) to investigate NADH homeostasis of ciprofloxacin-tolerant E. coli, E. coli HipQ, ciprofloxacin-tolerant cells have a significantly lower [NADH:NAD+] ratio than tolerant cells of its parental strain, providing further link between disturbed NADH homeostasis and antibiotic tolerance.First, we demonstrated that ciprofloxacin exposure results in a high number of VBNCs, several orders of magnitude higher than persisters. However, we found no correlation in the frequencies of persister and VBNC subpopulations. Ciprofloxacin-tolerant cells (persisters & VBNCs) were actively undergoing respiration, although at a significantly lower rate on average when compared to the bulk population. We also noted significant heterogeneity on a single-cell level within the subpopulations, however were unable to segregate persisters from VBNCs based on these observations alone. Finally, we showed that in the highly-persistent strain of  Cellular redox environment can be broadly defined as the balance between oxidants: reactive oxygen species (ROS), reactive nitrogen species (NOS) and hydrogen peroxide, and antioxidants – ROS/NOS-degrading enzymes, e.g., superoxide dismutase which breaks down superoxide ions . During Alternatively, NADH:NAD+ ratio detection system can be used as a proxy to estimate the intracellular redox homeostasis. NAD(H) acts as a co-factor in hundreds of intracellular redox reactions, including oxidative respiration (a major ROS-producing pathway) , warrantE. coli strain: E. coli HipQ  (Sigma Aldrich) and incubated at 37°C until an OD600 value of 0.3–0.5 (~3 h). Next, the cultures were spun at 5000 g for 10 min. The supernatant was removed and remaining pellet was concentrated 10 times in transport and storage solution , placed immediately on ice and left for an hour. 100–200 ng of DNA to be transformed was diluted to 200 μL in chilled TCM  and kept on ice. 200 μL of prepared as above competent cells was then transferred to tubes containing the TCM-diluted DNA and mixed by pipetting, taking care to not warm up the tubes. The mix was left on ice for an hour. Afterwards the samples were transferred to a heating block set to 45°C for 2 min and returned to ice for 5 min. Next the samples were diluted with 0.6 mL of SOC (SOB medium supplemented with 20 mM filter-sterilized glucose) and incubated at 37°C, with shaking at 200 rpm for 1 hour. 100 μL of the sample was then spread on Lysogeny Broth (LB) plates supplemented with 100 μg/mL ampicillin and incubated at for 24 h. PUC19 plasmid was used as positive transformation control and non-transformed competent E. coli cells were used as the negative control.Overnight Sigma Aldrich) agar plates or LB agar plates containing 100 μg/mL of ampicillin for pRSETB-Peredox transformed strains. Pates were incubated at 37°C overnight. Next, single colonies were inoculated into 1 mL of LB or LB with 100 μg/mL ampicillin added for plasmid retention. Cultures were incubated at 37°C overnight, with shaking at 200 rpm. Overnight cultures were then transferred to a black, clear-bottom, 96-well plate (ThermoFisher Scientific) (200 μL/well). Total biomass (OD600) and fluorescence intensity measurements were performed in the CLARIOstar plate reader (BMG LabTech). Fluorescence intensity was recorded at 575 nm excitation, 610 nm emission for mCherry (plasmid copy number), in precise mode, sequential well scan and automatic gain adjustment. Fluorescence intensity was normalized to OD values and compared between pRSETB-Peredox-transformed and untransformed samples in GraphPad Prism (GraphPad).Glycerol (25%) in LB bacterial stocks were stored at −80°C, streaked on LB . OD600 measurements in a 1 cm plastic cuvette, as well as a Miles & Misra (MM) dilution series , pH 7.4 (Sigma Aldrich) or fresh media and this suspension was used in the MM dilution series. MM plates were incubated at 37°C for 48 h, as it was previously determined that the HipQ strain persisters required 48 h for regrowth on agar plates. For direct comparison, time-kill assays and cytosolic [NAD(H)] (section 2.4) measurements were carried out on the same bacterial cultures simultaneously.Overnight (16–18 h) n series  on LB agn series . Culture0 (prior to antibiotic addition) and T24 (24 h post antibiotic addition) sample aliquots were diluted 1:500 in sterile PBS . Next, cells were live/dead stained with Zombie near-infrared (near-IR) fixable dye (BioLegend) (1:1000 or 1 μL/106 cells) and incubated for 20 min in the dark. For heat-killed control samples, undiluted aliquots (1 mL) were incubated at 75°C for 30 min and diluted to 106 total cells/mL in PBS prior to live/dead staining. Next, cells were loaded onto the LSR Fortessa Cell Analyser (BD Biosciences) and forward scatter (FSC), side scatter (SSC) and zombie near-IR fluorescence  was recorded. Additionally, T-sapphire fluorescence intensity ([NADH:NAD+]) was recorded at 405 nm excitation and 520 nm emission and mCherry fluorescence intensity (Peredox plasmid copy number) was recorded at 561 nm excitation and 610 nm emission wavelengths. Laser power was kept consistent throughout the independent experiments. Subsequent data analysis was performed in FlowJo v.10.8 (BD Biosciences). First, doublets were excluded based on FSC-A/FSC-H ratio ((BD Biosciences). For statistical analysis, fluorescence intensity values of T-sapphire and mCherry of individual events were exported into Microsoft excel, T-sapphire fluorescence was normalized to mCherry fluorescence and values were averaged within biological replicates. All statistical analyses (see respective figure legends) were performed in GraphPad Prism v.8. The antibiotic tolerant subpopulation (persisters & VBNCs) was classified as cells which stained as ‘live’ following antibiotic exposure was estimated by subtracting the % of persister cells in a given biological replicate from the % of live cells at T24.The time-kill assay method described above was followed, with the exception that at T-H ratio  and thenE. coli HipQ and its parental strain, confirmed by growth on ampicillin (pRSETB selection marker) agar plates. The biosensor consists of T-Sapphire-Rex fusion protein whose fluorescence intensity correlates with intracellular [NADH:NAD+], as well as constitutively expressed mCherry which can be used to normalize T-sapphire fluorescence to plasmid copy number  was successfully transformed into the highly persistent E. coli strains with a T7 polymerase-expressing vector. However, pRSETB-Peredox transformants formed red-tinted colonies on agar plates, and it was subsequently confirmed by fluorescence measurements, relative to the untransformed E. coli controls, that those cells expressed mCherry, confirming expression from the T7 operon  following 24 h of ciprofloxacin exposure between biosensor-expressing and untransformed E. coli , or betwE. coli , investiInterestingly, the frequency of persisters in a biological replicate did not correlate with the frequency of VBNCs, i.e., a higher % of live cells did not consistently equal to a higher number of persisters . This suIn this assay exponentially growing cultures were exposed to 25XMIC of ciprofloxacin and cytosolic [NADH:NAD+], as well as viability of individual cells was measured with a flow cytometer. As mentioned previously (section 3.2), ciprofloxacin is non-lytic and therefore it was reasoned that the majority of ciprofloxacin-exposed cells will retain their protein content (including the Peredox biosensor), regardless of their viability status.n = 2) there was a subpopulation of ‘live’ cells which expressed mCherry at low levels, lower than the majority of ‘dead’ cells, yet higher than autofluorescence at this wavelength (n = 3). It was possible that these cells could have been carrying a very low copy number of the NADH biosensor, since we have previously demonstrated that mCherry protein is stable up to 24 h post expression inhibition (data not shown). Alternatively, these cells could have been ‘dormant’  prior to ciprofloxacin exposure resulting in extremely low levels of biosensor expression, however if that was the case, they were functionally indistinct from dead cells. Due to its unique characteristics, this subpopulation was analyzed separately and is referred to below as the ‘zombie subpopulation’. Interestingly, no ‘zombie cells’ were observed in E. coli HipQ . The 405/520 nm (T-Sapphire) autofluorescence of live cells at t = 24 h vs. t = 0 h was not significantly different  and the bulk population prior to antibiotic exposure. As can be seen in ifferent , and theE. coli HipQ persisters and VBNCs showed a significantly lower [NADH:NAD+] than persisters and VBNCs of its parental strain despite no statistically significant difference at bulk population level prior to antibiotic exposure. This supports the hypothesis that perturbed NADH homeostasis relates to antibiotic tolerance. However, it is important to note that the ciprofloxacin-tolerant subpopulation was itself heterogeneous on a single cell level   which isE. coli, Vibrio cholerae (Mycobacterium tuberculosis (in vivo (or in vivo mimicking) conditions, which could contribute to infection recurrence. Therefore, better understanding of the VBNC state would aid in design of improved antibiotic treatment regimens, effective against heterogenous antibiotic-tolerant subpopulations which include both persisters and VBNCs.There has been an ongoing debate in the field whether the VBNC state is separate phenomenon to persistence, with some research groups reporting a distinct phenotypic state associated with VBNC cells , and othcholerae  and Mycorculosis  VBNC celIt is important to note that the definition of ‘viability’ regarding the viable but non culturable state differs and can be based either on transcriptional/translational activity and membrane integrity e.g.,  or on meE. coli cultures, ofloxacin persisters were more likely to have a lower reductase activity than the bulk population  staining, that in exponentially growing pulation . We valipulation . To the piration . Respirapiration , and ourpiration . AlthougE. coli HipQ generates 10–1000 fold more ofloxacin persisters than its parental strain  homeostasis of antibiotic-tolerant and antibiotic-susceptible bacterial cells.E. coli ciprofloxacin-tolerant cells are in the VBNC state. These observations could be easily expanded on in the future work to other non-lytic antibiotics and/or bacterial species, following the method we established and validated here. Furthermore, we evaluated dysregulated NADH homeostasis as a potential marker for antibiotic tolerance and showed that the antibiotic tolerant subpopulation differs significantly from the bulk population in their cytosolic [NADH:NAD+]. We note that the biggest limitation of our study is that we were not able to determine whether this dysregulation occurs as cause or effect of antibiotic tolerance  homeostasis dysregulation prior to antibiotic exposure). To expand on the observations presented here, we suggest employing fluorescence-activated cell sorting (FACS), in order to sort populations based on [NADH:NAD+] prior to antibiotic exposure, which would allow to answer the aforementioned research question, and subsequently validate whether [NADH:NAD+] can be used as antibiotic tolerance marker. Furthermore, to increase sensitivity of this system, higher level of Peredox expression could be obtained by inducing T7 promoter-dependent expression. However, the potential effect of high amounts of recombinant protein on cellular metabolic state , and subsequently antibiotic tolerance, would need to be evaluated first.In this work we demonstrated that the majority of http://flowrepository.org/id/FR-FCM-Z64Q.The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found at: Flow Repository: JU: study design, data collection and analysis, and draft manuscript preparation. FH, JM, MS-S, and SH-W: supervision and critical revision of data and manuscript. All authors contributed to the article and approved the submitted version.This work was funded by the MRC/AMED grant MR/T028998/1.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.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Despite antibiotic prescription being recommended for dysentery and suspected cholera only, diarrhea still triggers unwarranted antibiotic prescription. We evaluated antibiotic-prescribing practices and their predictors among children aged 2–59 months in the Vaccine Impact on Diarrhea in Africa (VIDA) Study performed in The Gambia, Mali, and Kenya.VIDA was a prospective case-control study (May 2015–July 2018) among children presenting for care with moderate-to-severe diarrhea (MSD). We defined inappropriate antibiotic use as prescription or use of antibiotics when not indicated by World Health Organization (WHO) guidelines. We used logistic regression to assess factors associated with antibiotic prescription for MSD cases who had no indication for an antibiotic, at each site.VIDA enrolled 4840 cases. Among 1757 (36.3%) who had no apparent indication for antibiotic treatment, 1358 (77.3%) were prescribed antibiotics. In The Gambia, children who presented with a cough  were more likely to be prescribed an antibiotic. In Mali, those who presented with dry mouth  were more likely to be prescribed antibiotics. In Kenya, those who presented with a cough , decreased skin turgor , and were very thirsty  were more likely to be prescribed antibiotics.Antibiotic prescription was associated with signs and symptoms inconsistent with WHO guidelines, suggesting the need for antibiotic stewardship and clinician awareness of diarrhea case-management recommendations in these settings. Inappropriate antibiotic prescribing for diarrheal diseases can promote antimicrobial resistance. In VIDA, unnecessary or incorrect antibiotics were prescribed for 77% of diarrhea and 41% of dysentery cases. Interventions are needed to promote judicious adherence to international guidelines in low-/middle-income countries. Shigella, for example, have emerged, leaving few options for effective, affordable therapy ) and metronidazole (27/428 [6.3%]) in The Gambia, metronidazole (50/60 [83.3%]) and cotrimoxazole (41/60 [68.3%]) in Mali, and ciprofloxacin (67/153 [43.8%]) and metronidazole (50/153 [32.7%]) in Kenya. A total of 1757 (36.3%) enrolled MSD cases had no clinical indication for antibiotics according to our study definition and consistent with IMCI guidelines. Of those who had no apparent indication for antibiotics, 1358 of 1757 (77.3%) were prescribed antibiotics .The highest proportion of MSD cases with no apparent antibiotic indication who were prescribed antibiotics was observed in Mali (1055/1075 [98.1%]), followed by The Gambia (232/403 [57.6%]) and Kenya (70/279 [25.1%]) . The mosP = .039). A similar pattern was seen in Kenya for cough  and difficulty breathing . Children with signs of dehydration were less likely to receive an inappropriate antibiotic prescription in The Gambia  but more likely in Mali  and Kenya . In The Gambia, younger children appeared more likely to receive an inappropriate antibiotic prescription. In Kenya, children with fever  were more likely to receive an inappropriate antibiotic prescription, whereas in The Gambia, children with belly pain were less likely .The distribution of characteristics of MSD cases with no antibiotic indication who did and did not receive antibiotic prescription stratified by site is shown in The trends observed in the univariate, bivariate, and multivariable analyses were consistent and generally produced concordant statistically significant associations with some exceptions. For example, in the multivariable analyses, there was no association between antibiotic prescribing and age or fever, whereas children who appeared irritable in Kenya were marginally less likely to receive a prescription.Cases of MSD with no antibiotic indication in The Gambia who presented with cough in the absence of respiratory distress were more likely than those without cough to have an antibiotic prescribed ; those who presented with belly pain  and dry mouth  were less likely to have an antibiotic prescribed than those without these symptoms. In Mali, MSD cases who presented with dry mouth were more likely to have an antibiotic prescribed compared with those who did not . In Kenya, a cough , decreased skin turgor , and the child being very thirsty  were positively associated with apparent unnecessary antibiotic prescribing among MSD cases with no antibiotic indication, whereas those who were restless/irritable  were less likely to have an antibiotic prescribed .Our findings indicate that nonadherence to IMCI guidelines for treatment of diarrhea is prevalent at the study sites in sub-Saharan Africa, manifesting as prescription of antibiotics that are ineffective or unnecessary, or not prescribing antibiotics when they are indicated. Overall, 88% of children with dysentery were prescribed antibiotics, but only 59% of them received the recommended first-line therapy with ciprofloxacin. In addition, 77% of MSD cases who had no apparent indication for therapy were prescribed antibiotics. Unindicated antibiotic prescription was associated with specific clinical features, which varied somewhat from site to site, suggesting that cross-cutting antimicrobial stewardship is needed that is informed by local clinical practices.Overall, most children with watery diarrhea in The Gambia (58%) and Mali (98%) and 25% in Kenya received an antibiotic that the guidelines deemed unnecessary, corroborating results from other studies indicating the widespread nature of this problem in primary care across low- and middle-income countries (LMICs) , with soShigella isolates were resistant to cotrimoxazole during GEMS [Inadequate laboratory capacity, a common problem in Africa, has been suggested as a barrier to effective decision making by clinicians in LMICs regarding the need for antibiotic therapy ; howevering GEMS  and VIDAing GEMS . Prescriing GEMS .Antibiotics were prescribed significantly more often in our study when selected clinical findings were present that do not carry an indication. For example, in Mali and Kenya, antibiotic prescription was 2–4 times more likely when a healthcare provider observed signs of dehydration . In The Gambia and Kenya, both rural sites, children with cough in the absence of respiratory distress were more likely to receive antibiotics than those without these findings. These observations corroborate those of Rhee et al  in KenyaThe main limitation in our current study is that it was not originally designed to evaluate the decision process in antibiotic prescribing, which could have resulted in misclassification of some cases as not warranting antibiotics. Important factors that this study did not explore include the prescribers’ knowledge, attitude, and rationale for their antibiotic prescription decisions or barriers to implementing guidelines such as drug cost or availability.The WHO considers AMR to be one of the biggest threats to global health, food security, and development, and underscores the role of antibiotic misuse in accelerating the process . The higClinical Infectious Diseases online. Consisting of data provided by the authors to benefit the reader, the posted materials are not copyedited and are the sole responsibility of the authors, so questions or comments should be addressed to the corresponding author.ciac980_Supplementary_DataClick here for additional data file.


The adequacy of retrofitting with concrete jacketing is influenced by the bonding between the old section and jacketing section. In this study, five specimens were fabricated, and cyclic loading tests were performed to investigate the integration behavior of the hybrid concrete jacketing method under combined loads. The experimental results showed that the strength of the proposed retrofitting method increased approximately three times compared to the old column, and bonding capacity was also improved. This paper proposed a shear strength equation that considers the slip between the jacketed section and the old section. Moreover, a factor was proposed for considering the reduction in the shear capacity of the stirrup resulting from the slippage between the mortar and stirrup utilized on the jacketing section. The accuracy and validity of the proposed equations were examined through a comparison with the ACI 318-19 design criteria and test results. Concrete jacketing is an effective seismic retrofit method to improve strength and rigidity by enlarging the cross-section of reinforced concrete columns. The seismic performance of a retrofitted member with a concrete jacket is affected by the reinforcement in the jacketing section, the compressive strength of concrete, and the bonding between the old section and the jacketing section. Therefore, recent studies have been conducted on seismic hooks and steel wire mesh (SWM) to improve the shear performance of the jacketing section and on the use of dowels to constrain the jacketing section and the old section ,2,3. ManThe hybrid concrete jacketing method is divided into two types according to the reinforcement in the jacketing method, as shown in To analyze the seismic performance of the hybrid concrete jacketing method, two test specimens of reinforced concrete columns without seismic design and three specimens retrofitted with hybrid concrete jackets were fabricated and subjected to a cyclic loading test. The details of the specimens are shown in The manufacturing process of the specimens retrofitted with the hybrid concrete jacketing method is presented in In this study, a cyclic loading test considering axial load, lateral load, and torsional load was conducted to simulate actual seismic load. The test setup and the quasi-static loading protocol are shown in The load-displacement curves for each specimen are shown in HCJ-1U and HCJ-1B retrofitted with Type 1 reached the maximum loads at 8.5% and 6% of the drift ratio, respectively, and the maximum loads were 198.32 kN and 202.45 kN, respectively. The maximum load of HCJ-2U retrofitted with Type 2 was 7% lower than that of HCJ-1U retrofitted with Type 2 under the same load scheme. Unlike Type 1, in which dowels were placed to improve the bonding performance between the old section and the jacketing section, Type 2 omitted additional reinforcement by placing SGR with hooked details in the jacketing section. The bonding capacity between the old section and the jacketing section was reduced in Type 2 compared to Type 1, resulting in relatively more slip. However, since similar seismic performances were observed compared to the simple construction process, this study confirmed that if Type 2 details are used, seismic performance can be secured without using additional shear reinforcement such as dowels. These results can be observed through the failure patterns of each specimen shown in The torsional moment and twist were obtained from LVDTs and strain gauges, as shown in Here, Torsional moment-twist envelopes are shown in Strains of the reinforcing bars in the old column and the jacketing section were compared to analyze the integration behavior of the hybrid concrete jacketing method. When a reinforced concrete column retrofitted with concrete jacketing behaves like a monolithic column, the difference in concrete strain between the old section and the jacketing section tends to increase proportionally until the ultimate strain ,20. HoweThe seismic performance of a concrete jacketed column depends on the bonding of the old concrete and added concrete. If appropriate shear reinforcement is designed in the jacketed section, a column with a concrete jacket should act monolithically under seismic load. Therefore, the shear strength and behavior of a reinforced concrete column retrofitted with concrete jacketing are predicted, considering the jacketed section to be an equivalent monolithic section . The expTo obtain the slip coefficient, gauges were used to measure the concrete strain in both the old section and the jacketing section, as shown in This study proposed a novel concrete jacketing method that employs non-shrinkage mortar for concrete jacketing, with the objective of enhancing workability and alleviating the problem of high self-shrinkage that is typically associated with Ultra-High-Performance Fiber-Reinforced Concrete (UHPFRC). It is important to note that the slip of stirrups in concrete can have a significant impact on the strength and durability of columns, particularly in columns that use mortar. This is due to the relatively smooth surface of mortar, which can lead to increased stirrup slippage compared to concrete columns. As depicted in During the initial stage of the experiment, the load was carried by the stirrup in the old column until yielding occurred, after which the stirrup within the jackets began to carry the load with an increase in load. Consequently, the monolithicity factor K, which denotes the ratio of stirrup strain in the jacketing section to that in the old section, gradually increased and approached unity in the early stages of the experiment. However, the load carried by the stirrup within the jacketing section increased as the torsional load increased, causing a reduction in friction between the stirrup and mortar in the jacket, resulting in a decrease in K. This phenomenon was observed consistently in all specimens, and K approached a constant value at the maximum load. The loading scheme was closely related to K, and the values of K at the failure for HCJ-1U, HCJ-2U, and HCJ-1B were 0.9, 0.82, and 0.97, respectively. Unidirectional loading led to an increase in torsional load, a reduction in bonding capacity between the stirrup and mortar within the jacketing section, and an increase in shear stress in the jacketing section. Moreover, Type 2 showed a greater decrease in bonding capacity between the stirrup and mortar within the jacketing section than Type 1 because no dowel was used to connect the old and jacketing sections, resulting in more sliding between the two sections and an increase in shear strength within the jacket.In this study, the shear strength of concrete and stirrup was estimated using the ACI 318-19 design criteria as shown in Equations (3)–(5).d is the distance from extreme compression fiber to the centroid of longitudinal reinforcement, λ represents the influence of lightweight concrete. Here, (1)When a unidirectional load is applied.(2)When no additional steel, such as dowels, is provided to enhance the bonding performance between the old section and the jacketing section.The shear strength equation of the reinforced concrete column retrofitted with hybrid concrete jacketing was proposed as shown in Equations (6)–(8). If slippage occurs between the old and jacketing sections, both sections may not fully exhibit their shear performance under seismic loads. To mitigate this issue, this study proposed a slip coefficient for each type of hybrid concrete jacketing method that considers the level of slippage between the old and jacketing sections based on experimental results. As a result, the contribution of concrete was estimated by multiplying the sum of the shear contributions of the old and jacketed sections by the slip coefficient to evaluate the shear strength of a reinforced concrete column retrofitted with hybrid concrete jacketing. The hybrid concrete jacketing method used mortar instead of concrete in the jacketing section, which can result in increased slip between the reinforcement steel and mortar due to the absence of coarse aggregate. Therefore, the reduction in stirrup shear capacity due to a slip between the mortar and the stirrup should be considered. The shear strength of the stirrup in the jacketing section was determined by multiplying the shear strength of the stirrup in the existing reinforced concrete column by a monolithicity factor, which is a reduction factor. The variable n in Equation (8) indicates the number of pertinent entities drawn from the subsequent options:The experimentally obtained shear strengths were compared with those predicted by the ACI 318 design code and the proposed equation presented in (1)The hybrid concrete jacketing used non-shrinkage mortar and steel fiber to suppress shrinkage and enhance strength. This retrofitting method improved bond capacity with steel wire mesh and steel grid reinforcement, and this method is divided into two types, Type 1 and Type 2, according to the reinforcement details in the jacketing section. Additional dowels which can improve the bonding capacity were used only in Type 1;(2)The cyclic loading test results demonstrated that the torsional moment of the jacketed column with Type 2 was approximately 80% of the jacketed column with Type 1. Additionally, the difference in strain between the old section and the jacketed section increased gradually, indicating that a slip occurred between the two sections. Therefore, when applying hybrid concrete jacketing for retrofitting old columns, it should be considered the slippage between two sections and shear resistance capacity according to the types of hybrid concrete jacketing methods used;(3)The slip coefficient and the monolithicity factor were proposed in this study for reinforced concrete columns retrofitted with hybrid concrete jacketing. The slip coefficient accounts for the bonding capacity between the old and jacketed sections; it was dependent on the type of hybrid concrete jacketing, with Type 1 exhibiting a value of 0.86, while Type 2 had a coefficient of 0.82. The monolithicity factor was proposed as a parameter that accounts for the reduction of the stirrup shear strength resulting from the slip between the mortar and the stirrup in the jacketing section. This factor varies based on the presence of dowel bars and the loading pattern;(4)In this study, the shear strength equation for reinforced concrete columns retrofitted with the hybrid concrete jacketing was proposed by introducing the slip coefficient and monolithicity factor. In contrast to the ACI 318-19, which overestimates test results by approximately 23%, the proposed equation yielded conservative estimates, underestimating the results by approximately 3%. It was indicated that the proposed equation is more reliable and accurate for evaluating the shear strength of jacketed columns. Overall, the results of this study provided important insights into the use of the hybrid concrete jacketing method for retrofitting reinforced concrete columns, and the proposed shear strength equation could be useful for assessing the structural performance of jacketed columns.This study investigated the bonding capacity of a reinforced concrete column retrofitted with hybrid concrete jacketing under combined loading. Five specimens were fabricated, and cyclic loading tests were conducted. Based on the test results, the authors proposed a shear strength equation that considers the slip between the jacketed section and the old section. The following conclusions have been drawn: