As we know, 3DPC is printed layer by layer compared with mold-casting conventional concrete. Pore structure and layer-to-layer interface are two main aspects of the internal structure for 3DPC, which decide 3DPC’s mechanical performance. The layer-to-layer interface caused by printing is specific to 3DPC. The emphasis of this study lies in the layer-to-layer interfaces of 3DPC. The first aim of this study is to quantify the characteristics of the layer-to-layer interface and therefore characterize different aspects of the interfaces. The second aim of this study is to explore how the internal structure of printed concrete influences the mechanical performance of 3DPC. This research set out to design a series of experimental comparisons between 3DPC and casted concrete with the same compositions. Mechanical tests, i.e., compressive stress, ultrasonic Pulse Velocity test, flexural tension, and tension splitting, as well as the Ultrasonic Pulse Velocity test, were performed to check the mechanical performance of 3DPC. Contrary to what has often been expected, the mechanical test results showed the printed concrete has a quality not worse than casted concrete with the same recipe. Meanwhile, the X-ray computed tomography (X-CT) is used to characterize the internal structure, pore shapes, and interfaces of 3DPC. First, the investigation revealed that the lower total porosity and fewer big voids could be the fundamental causes meaning 3DPC has a better mechanical performance than casted concrete. Second, the statistics based on aspect ratio show that the distribution curves follow similar trends, regardless of the printed or casted concrete. Third, this study quantified the depth of the different interfaces for 3DPC. The results suggest that the porosity in an interface varies in a range. The author’s pioneer work has contributed to our present understanding of the interfaces of 3DPC. Such benefits include improved geometrical freedom, greater safety in construction, formwork and mold-free manufacturing, and reduction in construction time, labor, cost, and waste. It has been shown that 3DCP reduces COanalysis . CompareThe layered nature of 3DPC might result in more porous and weaker interfaces, which will lead to anisotropy in mechanical properties, weaken the overall load-bearing capacities, and influence the transport and durability behaviors of 3DPC structures ,3,4,5. TOwing to this significance, the research interest on layer-to-layer interfaces of 3DPC is growing ,7,8. TheSince many issues resulting from the interfaces of 3DPC are still open and need to be investigated sufficiently, several studies to date have carried on the interface analysis of 3D-printed mortar. For instance, Liu et al.  and ChenSo far, however, there is less information about the specific definition of the printing layered interfaces, and there has been very little discussion about the characteristics of the interfaces. For instance, with respect to the number of interfaces, most of the research only showed several layers in the 3D CT rendering, which was limited to four layers (three interfaces) ,25,28. XTherefore, the emphasis of our study lies in the layer-to-layer interfaces of 3DPC. More interlayers of printed concrete are presented in 3D X-CT reconstruction compared to the existing literature. The aim of this study is twofold. The first is to quantify the characteristics of the layer-to-layer interface and therefore characterize different aspects of the interfaces. The second is to elaborate on how the internal structure of printed concrete influences the mechanical performance of 3DPC.In this research, a custom-designed printable mixture was adopted, containing Portland cement (CEM I 52.5 R) blended silica fume, granite aggregates with a maximum particle size of 2 mm, limestone filler, calcium formate as setting time modifier, PCE (polycarboxylate ether) dispersants as rheology control additives, and a small amount of PVA fibers. The water-to-binder ratio was 0.22 by volume, or 0.36 by weight. The printed concrete slab under investigation is contributed by Hyperion Oy in Finland without any commercial purpose, aiming to contribute to modern concrete research.The slab is printed with a 3DPC setup as shown in The same mixture was cast in several steel molds of 10 cm × 10 cm × 10 cm and compacted with a vibrating table. Immediately after casting, the samples were covered with a plastic sheet to prevent moisture loss and left to harden at room temperature (20 °C). After 24 h, the samples were demolded and cured in the standard curing room at 100% RH and 20 °C for 50 days. In this research, the specimens under investigation were manufactured from both printed and mold-cast states, with the purpose of comparing the differences in internal structure of concretes and mechanical performances between printed and mold-cast states. The sampling process is presented in In the meanwhile, casted specimens of the same size were sawn from the 10 cm cubic mold-cast specimens.An experimental program has been designed to investigate the mechanical properties of 3D-printed specimens with different interfaces’ distributions and the casted specimen using destructive mechanical tests and non-destructive tests, namely, compressive strength, flexural tension, tensile splitting, and Ultrasonic Pulse Velocity (UPV). Compressive strength was measured in prismatic specimens from both 3D-printed and mold-cast specimens, according to the SFS-EN 12390-3 standard. The prismatic specimens were 5 × 5 × 10 cm and were loaded with a rate of 0.6 N/mm² s until failure. The maximum load ; Three-point bending test were performed on the prismatic specimens in accordance with the SFS EN 196-1 standard. A load was applied on the specimens vertically by means of the loading roller to opposite side face of the prism at a rate of d is the designated cross-sectional dimension, in Tensile splitting strength test were performed on prismatic specimens, according to the SFS/EN 12390-6 standard. The initial load applied on specimens did not exceed approximately 20% of the failure load. Afterwards, load was applied to the specimen without shock and increased with a constant rate of 390 X-ray computed tomography (X-CT) is a powerful and non-destructive tool to create 3D visualizations of the internal structure of cementitious materials. The 3D data can be used for qualitative and quantitative investigation ,36,37,38From the compression test results shown in Meanwhile, the Ultrasonic Pulse Velocity test (UPV) was conducted on the paralleled specimens to investigate the quality of concrete. High pulse velocity values generally indicate a good quality of concrete. The Ultrasonic Pulse Velocity device “Matest Ultrasonic Pulse Velocity Tester C373N” was calibrated using the calibration reference bar before conducting each measurement. The measurements were performed using the UPV indirect transmission according to the “SFS-EN12504-4,2004” standard. Qualities of concrete for different values of UPV are presented in v is the UPV velocity (km/s). It can be seen from the equation that a higher value of UPV indicated a higher value of compressive strength. In this research, the test results for the UPV and the correlated compressive strength are presented in Based on the previous research from Fahim et al. , the comCombined with the information in The failure patterns for specimens were observed in  when benThis is attributed to the interlayer distribution in the loading direction. As we know, interlayers are the weak joints for 3D-printed concrete. For x-orientation specimens, loading is parallel to the V-interfaces  is a 3D imaging technique which is based on the 3D-computed reconstruction of a sample from the 2D radiographic projections acquired from different angles around its axis of rotation. In this study, three 3D-printed concrete samples with different printing orientations and one casted sample as the reference were scanned to determine how printing orientation affects their internal structure. Specifically, three cores of 40 mm diameter and 100 mm height  were driAs per the 3D rending displayed in As shown in Moreover, a 3D rending of several representative single irregular pores for 3DPC were visualized as 3D) of a 3D void, as a parameter of shape descriptors, which quantify the form of a pore/void, is defined as the average value of elongation index (EI) and flatness index (FI) [For the purpose of investigating the voids shapes in concrete further, we statistically analyzed the aspect ratio of voids in 3DPC concretes, as well as in the casted concrete. The aspect ratio (ARdex (FI) ,45. Elondex (FI) . Figure Meanwhile, aiming to explore the difference further between printed concrete and casted concrete, we visualized the relationship between elongation, flatness, and volume (bubble size) of a particular void in relation to the void shapes with the bubble figure , as showAs shown in lues see , there aWe mentioned above that the porosity profile trends inversely resemble the grayscale values curves. Then, as for 3DPC-Z, the significant sharp peaks (downwards) in Further, the porosity for the interfaces can be observed from Moreover, specimens’ mechanical strength  can be solely attributed to neither the bonding strength of interfaces nor the total porosity of specimens, because the force diagram of specimens under the loading The results of mechanical investigation  have shown that 3DPC significantly tends toward interlayers’ orientation dependency with respect to mechanical performance, especially regarding the splitting tensile resistance. The results also showed that 3DPC has good mechanical performance, i.e., compressive strength, flexural strength, and tensile splitting strength, which is not inferior to casted concrete with the same recipe.(2)The results from X-CT revealed that higher total porosity and more coarse voids in casted concrete than 3DPC could be the fundamental reason for its slightly inferior strength. The results of this study indicate that specimens’ mechanical strength can be solely attributed to neither the bonding strength of interfaces nor the total porosity of specimens; still, the force diagram of specimens under loading (as shown in (3)Concerning the X-CT analysis, the first major finding was that porosity profiles for 3DPC  showed several regular adjacent valleys and peaks with comparison to casted concrete, and that the distance between the adjacent valley and peak happens to be equal to the thickness of each layer of matrix. Based on this finding, this study first attempted to provide the specific definition of the layer-to-layer interfaces and therefore quantified the depth/width of the interfaces. Moreover, the porosity results suggested that porosity in an interface area varies in a certain range.(4)The second significant finding was that the distribution curves regarding the aspect ratio statistic follow similar trends regardless of the type of concrete (printed or casted), and coarser voids in casted concrete are somewhat more “equant” compared to printed concrete.(5)The third significant finding was the samples from different orientations of 3DPC had a unified pore size distribution, which can be easily distinguished from the casted concrete.The study is limited by the absence of bonding strength tests due to a lack of unified and mature testing standards. Whether or not bonding strength is the key point that affects the mechanical performance of 3DPC might depend on the stress conditions from loading. Further research is needed to investigate how these factors, i.e., numbers of interlayers, the porosity of interfaces, the depth/width of interfaces, pore distribution and pores shape in the interface area, affect the bonding strength of the printing interfaces, as well as the transport properties of printed concrete. Meanwhile, further study on defining and unifying the testing standard of the printing interfaces is therefore recommended.


The statistical account of language acquisition asserts that language is learned through computations on the statistical regularities present in natural languages. This type of account can predict variability in language development measures as arising from individual differences in extracting this statistical information. Given that statistical learning has been attested across different domains and modalities, a central question is which modality is more tightly yoked with language skills. The results of a scoping review, which aimed for the first time at identifying the evidence of the association between statistical learning skills and language outcomes in typically developing infants and children, provide preliminary support for the statistical learning account of language acquisition, mostly in the domain of lexical outcomes, indicating that typically developing infants and children with stronger auditory and audio-visual statistical learning skills perform better on lexical competence tasks. The results also suggest that the relevance of statistical learning skills for language development is dependent on sensory modality. Infangrammars , a possigrammars . Alternagrammars .Statistical learning (SL) can be defined as the implicit and rapid process of extracting regularities present in the structure of the sensory input . NaturalDespite the fast growth of the field of SL and the already established tradition of language acquisition research, the evidence of a direct impact of SL skills on language learning outcomes is still limited. While a couple of influential theoretically-motivated reviews published over the last decade  establis1.1SL studies typically involve exposing participants to an artificial language, whose statistical structure mimics the complex structure of natural languages. Crucially, one or more regularities of interest are manipulated, while keeping all other statistics constant . Participants are then tested on their implicit and/or explicit learning of the artificial language, using behavioural or neurophysiological methods. Importantly, this paradigm only measures SL ability, but not natural language outcomes or concurrent language knowledge.SL has been amply documented for auditory speech stimuli. The SL experimental paradigm has shown that word segmentation, phonological learning, and syntactic learning can be performed solely based on statistical cues . From a Given the nature of SL as a powerful broad cognitive mechanism, an important question is how it manifests in other modalities and to what extent its operation and manifestation in other modalities may be relevant for language. Developmental research has shown that SL is also a crucial mechanism for learning non-auditory and non-linguistic material. Infants' and children's ability to extract statistics from visual  and non-1.2The increasing number of studies showing children's and adults' ability to extract statistics from linguistic material has contributed to the SL account of language acquisition . ThiWhile extant research suggests that SL may indeed be positively associated with language development in both infants and children, there is also evidence of null correlations. It has been suggested that this association might be more complex than what the first theoretical accounts have predicted, because SL is likely to be componential . Differe1.3We conducted a preliminary search for existing scoping and systematic reviews on February 9, 2021 in PROSPERO, Cochrane Database of Systematic Reviews, and Open Science Framework (OSF) database. No reviews were found that examined the association between SL and typical language development in children. Given the absence of such a review in the literature, we performed a scoping review  of prima1.3.1(a)to identify and assess the body of evidence on the association between SL skills and language proficiency during childhood;(b)to organize this evidence according to: age (from 0 to 12 years of age); language domain; sensory modality of the SL; characteristics of the SL measure and type of stimuli of the SL task(c)to summarize the evidence of a statistical account of language acquisition, based on the review of these empirical studies;(d)to identify gaps in research and domains of evidence.This review set out the following objectives:22.1Studies that included and reported results from typically developing children between 0 and 12 years of age were considered. We decided not to include studies and/or results from atypical populations, since the association between language impairment and SL has already been subject to a meta-analysis . Rega2.2Included studies reported a quantitative measure of language development or language competence and a quantitative measure of SL abilities from the participants and analyzed statistically the association between the two measures. Regarding language measures, tasks or tests of proficiency in the phonology, vocabulary, morphology, syntax, and literacy domains, and overall language  were considered. Regarding the SL measures, we considered experimental paradigms where participants were familiarized with a natural or artificial language, in any sensory modality , and then tested on their learning of a given probabilistic rule or pattern embedded in the language, by giving an implicit or explicit response.2.3The studies were conducted in a controlled laboratory setting in any geographical location.2.4Sources of information were limited to primary research studies published in peer-reviewed journals and in English. Research on SL typically employs experimental paradigms from which quantitative measures are obtained. We therefore limited our sources to quantitative studies, both with cross-sectional and longitudinal designs. No timeframe restrictions were imposed on the search.3https://doi.org/10.17605/OSF.IO/CEQH5).This review adopted the Joanna Briggs Institute (JBI) methodology for scoping reviews ,34. The 3.1Scoping reviews involve a comprehensive three-step search strategy. First, we performed an initial limited search in PsycINFO, in order to analyze the keywords contained in the title, abstract and index terms of relevant articles. Using these keywords, we developed the following full search strategy:  AND (“language” OR “phonology” OR “vocabulary” OR “lexicon” OR “grammar” OR “syntax” OR “morphology”) AND (“infants” OR “toddlers” OR “children” OR “preschoolers” OR “school children”). The search strategy was implemented in four relevant databases: PsycINFO (Ovid), Web of Science, PubMed, and EBSCOHost . Additionally, we searched for more sources of information in the reference list of all the articles included in the review.3.2The study selection process was performed independently by two reviewers. After each step of the process, the reviewers met to compare and discuss their individual results. Disagreements were solved upon joint discussion. Study selection included the following phases: 1) removal of duplicates, 2) screening on title and abstract, 3) publication in peer-reviewed journals check, 4) full-text examination.3.3In order to fully accommodate all relevant information, the instrument initially developed for data extraction and presented in the review protocol was revised, as data was extracted. The final instrument included extraction fields for design and sample characteristics, language development measures, SL task measures, and the statistical analysis of the association (see Appendix B). Data extraction was independently conducted by the two reviewers and disagreements were resolved through discussion. When data was missing from the research reports, the authors were contacted.44.1The results of the study selection are reported in the flow diagram proposed by the PRISMA Extension for Scoping Reviews protocol , which 4.1.14.2Fifty nine percent of the studies obtained measures in only one language domain, typically the lexical domain. 4.3Among the 32 studies, there was a total of 34 SL tasks: 13 studies included a visual task, 10, an auditory task, 7, an audio-visual task, and 2 studies had one auditory task and one visual task. The triplet segmentation task, which involves CV syllables organized into triplets and tests whether participants can distinguish between syllable triplets forming words vs. syllable triplets spanning word boundaries, was employed in 67% of the studies measuring SL in the auditory modality, followed by artificial grammar learning tasks (33%). 92% of these studies presented linguistic material, syllables in most cases. In the visual modality, 33% of the studies used the serial reaction time, 27% used the triplet segmentation task, and 20% used artificial grammar learning tasks. Most of the visual SL tasks presented cartoon figures as stimuli. In the audio-visual modality, 5 out of 7 studies used the cross-situational word learning task, with words used as auditory stimuli and, typically, objects as visual stimuli.The statistical pattern to be learned in SL tasks was typically transitional probabilities (56%), but also a rule (21%), or the co-occurrence of word-object pairs (15%). Half of the studies used implicit measures of learning, the most common ones being eye movements  and reaction times , which are online measures. The other half of the studies used explicit measures of learning, particularly a forced choice measure , which is an offline measure.4.423 out of the 32 studies (68%) report at least one statistically significant association between the two measures. Across these studies, 53 tests of association were performed – including different sensory modalities and different language domains. When we analyzed these 53 tests of association, the proportion of significant results was reduced to 41% of the tests. 4.5For infants, auditory SL at 15–16 months correlates with concurrent lexical-processing efficiency, but not with the number of words understood . FurtherThe positive relationship between vocabulary and SL skills is also attested in the audio-visual modality. Thus, 12- and 14-month-olds who learn novel word-object pairs in audio-visual SL tasks are the ones with more advanced vocabularies for their age . HoweverVisual SL skills at 8–9 months of age predict concurrent vocabulary comprehension and gesture comprehension at 13–14 months , but not4.6The majority of studies which have investigated associations between SL and syntactic development have addressed the visual modality. Visual SL abilities at 7 months of age predict the mean length of utterance at 24 months . In pres4.7Some studies suggest that visual SL skills are associated with reading, writing, and spelling abilities in school-age children ,53,62, F4.8One study found phonological processing abilities to be associated with both auditory and visual SL skills in 4- to 10-year-olds ; Fig. 5)4.9Auditory SL skills at 8–9 months of age are associated with concurrent babbling ability, but not with babbling ability at 4 months of age ; Fig. 6)4.10Acquisition of word structure was found to be associated with auditory SL in children between 3 and 12 years of age ; Fig. 7)5Statistical learning has been implicated as a viable candidate to explain the fast rate of language development, given the complexity and richness of the input infants and children are exposed to throughout development ,10. It hThe observable trend for the majority of studies in this review was a cross-sectional design, English-speaking children as participants, and the inclusion of measures of lexical development and either auditory or visual SL skills. Triplet segmentation tasks and artificial grammar learning tasks were the most commonly used paradigms to measure SL skills. Both implicit and explicit measures of learning were used, typically eye movements (online) or forced choice measures (offline).Since our main aim was to analyze the association between language development and SL skills across language domains and SL modalities, we were looking for evidence of links in different domains of language competence. A large part of the included studies obtained measures of lexical skills, which allows us to draw some relatively stable conclusions on the association between vocabulary development and SL skills. However, the number of studies measuring other language domains might not be sufficient for the same type of conclusions.Receptive and expressive vocabulary seem to be associated with auditory and audio-visual SL, but not with visual SL alone. This is not surprising, given the central role of the auditory modality in oral language skills and, specifically, in word segmentation. The role of skills in audio-visual binding is also quite consistent with the process of mapping auditory information  to visually available referents corresponding to word meanings, which is an essential step in word learning . The revThe results concerning the visual modality and syntactic skills, literacy and phonological skills are mixed, with some studies suggesting that these language domains are not associated with visual SL, while others have found positive associations. These results may indicate that language development in general might not be directly associated with visual SL. Alternatively, the data may suggest that visual SL may be operative selectively at different stages of language development and for different types of skills. The latter conclusion is particularly plausible, given the wide age ranges studied and the inconsistency of paradigms used. Interestingly, nearly all of the studies which addressed grammar/syntax skills, used a visual SL task and half of those studies found positive associations between a measure of grammar and SL in the visual domain. In addition, the only study which tested auditory SL did not document an association with grammar. This may suggest that statistical learning skills in the visual domain may be more relevant for grammar/syntax, but not for vocabulary learning. However, whether the association found between lexical skills and auditory and audio-visual SL also holds across other language development domains, is still an open question.From all the tests of the association between language outcomes and SL skills, only 41% were statistically significant. When this percentage is further analyzed according to categories, the largest shares are found for the lexical domain and for audio-visual SL. There is also a tendency for a higher percentage of significant results in language domains that have been studied in more tests see . This suThe current findings suggest that the role of SL in language acquisition is dependent on the sensory modality of the statistics to be learned. This is based on two results. Firstly, auditory and audio-visual SL are positively associated with, and seem to predict, lexical competence, in at least a proportion of the reviewed studies. Secondly, visual SL is not associated with lexical competence, but may be associated with syntactic and literacy skills, pending further evidence. The primary role of the auditory modality for language development is consistent with findings concerning the differences in the developmental trajectories of SL in different modalities. Thus , found eIt has been noted elsewhere that SL tasks lack important psychometric characteristics, and therefore might not be used as a reliable measure of individual differences ,71,72. TOne of the goals of this review was to identify gaps in research. We found that, while the lexicon has been addressed in the majority of studies included in the current review, all language domains require systematic future research, especially given the statistically inconclusive evidence so far. This would provide a more complete overview on the importance of SL in language acquisition. If auditory SL skills are associated with other linguistic domains, this would suggest that auditory SL skills are basic cognitive abilities for language development in general. However, given the evidence of associations between visual SL and grammar identified in the current review, the possibility arises that other SL skills are selectively associated, and more tightly yoked, with domains, such as grammar/syntax. However, this requires future studies measuring these skills within a direct comparison between auditory and visual SL skills. Other domains in need of detailed future investigation are phonological and morphological skills, since evidence for these domains is scarce.A serious limitation for interpreting the findings from the reviewed studies is the heterogeneity of the tasks used to measure SL, as well as the language constructs which have been used as dependent variables. For instance, the studies looking at associations between SL and lexical skills and outcomes have selectively studied either overall vocabulary or only receptive or expressive vocabulary or lexical processing, as well as word and gesture comprehension. This reflects inconsistency regarding the hypotheses and the constructs under study.Studies which include SL tasks across different sensory modalities can provide useful evidence, by allowing a direct, within-subjects comparison across modalities. SL cross-modal comparisons are relevant, since there seems to be an advantage for auditory learning relative to tactile and visual learning . The audResearch would clearly benefit from more longitudinal data, which can inform on the predictive role of early SL skills for later language outcomes. In particular, the directionality of the association between language competence and SL skills needs to be established in controlled designs, especially given that the current review provides some evidence of a bi-directional relationship, which may be due to inconsistencies in the study designs and/or selection of analyses. Most studies in the current review have employed explicit measures, such as e.g., forced choice tasks. The latter have been criticized for not adequately capturing individual differences ,71,72. F6Scoping reviews provide a map of the literature, summarize evidence, and inform about knowledge gaps , and theIn this review, and according to established scoping review practice, we opted not to search for unpublished studies. A large percentage of the studies included here reported non-significant results (32%), and it remains unclear to what extent these results might still be affected by publication bias. For example, the fact that even published studies report non-significant results might suggest that others may have obtained non-significant results too, which were never published. We also excluded non peer-reviewed publications and secondary research. Although these can be included in a scoping review, we aimed at some homogeneity and therefore looked for literature with comparable standards.7Our findings support the SL account of language acquisition by revealing SL-based individual differences in language competence measures. Typically developing infants and children with stronger auditory and audio-visual SL skills perform better on lexical competence tasks. Due to the scarcity of studies, it is still unknown whether auditory and audio-visual SL also play a role in other linguistic domains. Our results also open up the question of the role of visual SL for language development, and the possibility of selective associations between specific SL modalities and language domains, pending future research. These results indicate that the relevance of SL skills for language development is dependent on sensory modality.Research on SL individual differences in language acquisition is biased towards lexical measures and auditory/visual SL measures. More studies are needed in non-lexical domains and in other sensory modalities. Studies should apply longitudinal designs to more consistently inform about how SL skills predict language proficiency.All authors listed have significantly contributed to the development and the writing of this article.This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 857897.https://doi.org/10.17605/OSF.IO/CEQH5).Data associated with this study has been deposited at Open Science Framework (registration The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.


This study assesses the durability of coated and uncoated concrete surfaces protected with four different coating materials: water-soluble (BW), solvent-based (BR), mineral (MI), and epoxy (EP). The durability assessment includes evaluating the absorption rate of water, pull-off adhesion strength, and coating material thickness. Concrete samples were subjected to immersion in regular water and a 7% urea solution, followed by cyclic freezing and thawing. Furthermore, the diffusion of chloride ions in concrete was evaluated using the impressed voltage method, with the samples exposed to the aging process immersed in a 3.5% NaCl solution. The results indicate that EP and BW coatings were significantly affected by the presence of urea and freeze–thaw cycles, resulting in a 43% and 47% reduction in pull-off adhesion strength, respectively. Notably, the MI-coated concrete samples exposed to urea solution and the freeze–thaw cycles exhibited a significant reduction in the absorption rate due to the accumulation of crystals on the coating surface, resulting in reduced porosity of the material. Concrete porosity directly affects the transport of chlorides, sulfates, CO2, leading to steel corrosion, cracking, and a reduced life span of reinforced concrete structures3. Reinforced concrete structures face challenges in various regions worldwide due to unfavorable environmental conditions. Moreover, these structures are additionally affected by soil contamination, resulting from various human industries such as energy, transport, construction, mining, and others. This contamination, combined with the impacts of climate change, accelerates the deterioration of reinforced concrete5.The durability of concrete structures embedded in soil is primarily influenced by the porosity of the concrete and the chemical properties of the soil6. The presence of salts, sulfates, and alkalis contributes to leaching, increasing porosity and weakening the concrete matrix7. Additionally, freeze–thaw cycles at different temperatures generate hydraulic pressure and subsequent expansion of the pores of the concrete, causing cracking, scaling, and crumbling8.During the service life of concrete structures, damage occurs due to chemical attacks and aggressive environments. The combustion of fuels, resulting in sulfuric acid, along with hydrochloric acid, aluminum chloride, and calcium bisulfite, leads to rapid concrete deterioration9, various systems can be employed to protect concrete structures, including improved structural design, incorporation of mineral additives, and application of coating materials. Implementing effective protection measures reduces permeability and extends the lifespan of structures10.To mitigate the deterioration of concrete matrix and, thus, the corrosion of reinforcing steel, it is crucial to implement an adequate protection technique. According to Aguirre-Guerrero et al.12, categorized coatings into three groups: metallic, organic, and inorganic. Epoxy, water-soluble, acrylics, vinyl resin, urethane resins, and bitumen, are commonly used to protect concrete structures in the construction sector.14. The primary objective of these materials is to prevent the entry of chemical agents that could compromise the structural integrity of the concrete elements.Coating materials can be applied to the reinforcing steel or the concrete surface. According to Taylor et al.15 evaluated the adhesion strength, chloride permeability, and thermal variations of five types of coating materials, including epoxy resin. The results showed that the epoxy material exhibited the highest adhesion strength values when applied in one layer, achieving 3.3 MPa after two weeks of application. Overall, epoxy resin demonstrated excellent crack bridging ability, resistance to thermal variations, and low chloride permeability, outperforming polyurethane and acrylic coatings. In a similar study, Diamanti et al.16 investigated the effect of a modified cementitious coating exposed to regular water and chlorides. Adhesion strength, water absorption, chloride diffusion, and chloride penetration rate were assessed after two months of application. The study highlighted that this coating material significantly reduced the water content of concrete and improved its performance, particularly with an increased polymer/cement ratio, effectively reducing steel corrosion. Epoxy coatings have also been studied for their effectiveness in protecting against sulfates attacks17 and carbonation19.A. Almusallam et al.20.Freeze–thaw cycles are a common natural phenomenon that can significantly impact the durability and performance of various materials, especially in regions with seasonal temperature fluctuations. The repeated freezing and thawing of water within the pores of materials causes the water to expand and contract, exerting substantial stresses on the material matrix. The severity and frequency of these stresses are determined by the temperature range at which the cycles occur21, approximately 60% of research papers use temperature ranges between −5 and + 15 °C in their freeze–thaw cycles.In particular, temperatures between −5 and + 15 °C have been identified as an optimal range for studying freeze–thaw effects. This range encompasses the transition phase from freezing to thawing and represents conditions commonly encountered in temperate climates. According to a study by Wang et al.23.By investigating freeze–thaw cycles within this temperature range, researchers can gain insights into the mechanisms and consequences of these cycles. They can also assess the performance and durability of materials, and develop strategies to enhance material resilience in environments prone to such cyclic conditions8 subjected the material to up to 18 cycles and used Fourier transform infrared (FTIR) to analyze the chemical composition changes. The results showed that the fatigue resistance decreased gradually after the freeze–thaw cycles, and the viscosity was excessively reduced. However, no changes were observed in the spectral peak range of 4000–2000 cm−1.The fatigue resistance and viscosity of modified bitumen coatings were evaluated under the influence of freeze–thaw cycles.. Tengfei et al.Four different coatings were used to protect concrete samples in this study. The samples were subjected to a unique accelerated aging method that involved freeze–thaw cycles, exposure to regular water and urea, and exposure to chlorides. Concrete samples without coating protection were used as reference samples. It is important to note that there is no published data on the results of the pull-off test and the impressed voltage technique using the proposed aging technique and materials.The objective of this research study is to comprehensively evaluate the performance and behavior of four distinct coating materials utilized in the construction industry to safeguard concrete structures. The coatings will be subjected to exposure to two specific contaminants, namely water and urea, which are commonly encountered in real-world scenarios. The investigation will involve applying these protective materials to the surfaces of both reinforced and non-reinforced concrete samples.To conduct this research, a set of carefully prepared concrete specimens will be utilized. These specimens will be divided into two groups: reinforced and non-reinforced concrete. Reinforced concrete includes additional materials such as steel bars, while non-reinforced concrete consists solely of cement, aggregates, and water.Four distinct coating materials will be selected based on their common usage in the construction sector. These coatings may vary in their composition, formulation, or application technique, representing a range of protective materials available in the market. By using multiple coatings, the research aims to capture a comprehensive understanding of their individual behaviors and performance characteristics.The findings of this research will provide valuable insights into the performance and behavior of the four coating materials when exposed to water and urea contaminants. The results can inform construction industry professionals, engineers, and material manufacturers about the most effective protective coatings to employ in specific environmental conditions.This research study aims to evaluate the effectiveness of different coating materials applied to concrete surfaces exposed to various contaminants. The study will combine quantitative evidence of changes in adhesion strength, absorption, and coating thickness. The findings will contribute to the growing research area on concrete protection in contaminated environments. Figure Four types of commercial coating materials commonly employed in the construction sector were used for the protection of reinforced concrete elements embedded in contaminated soil. These coating materials include water-soluble coating (BW), solvent-based coating (BR), mineral coating (MI), and epoxy coating (EP). Additionally, control samples without any coating material (NC) were evaluated. Table 24 and PN-B-06265:2018-10 standard25. Table The specifications of the concrete utilized for producing the specimens with dimensions of (100 × 100) mm are described as per the PN-EN 206+A2:2021-08 standardFirstly, the concrete surface was thoroughly cleaned using a regular brush to remove any dirt or debris after a curing period of 28 days.26Before applying the MI coating, the concrete surface was properly moistened. This procedure minimizes water absorption of the mixing water by the concrete and reduces the potential for cracking of the mineral coatingThe application of the coating materials was carried out in accordance with the specifications provided by the manufacturer. The protected samples were left to dry for approximately five days at room temperature of 20  ± 1 °C.For the preparation of the, a water/cement ratio of 0.20 was used.The epoxy material was mixed in a weight ratio of 4:1 [A: B]. The two components were thoroughly mixed using a plastic knife for a duration of 3 min to achieve a uniform consistency.The number of coating layers applied varied depending on the type of coating. One layer was applied for EP and MI coatings, while two layers were applied for BR and BW coatings.The application process for the coating materials is described as follows:In this study three types of concrete samples were utilized. Pull-off adhesion strength tests were performed on cube-shaped specimens measuring 100 × 100 mm. Cylinders with reinforced concrete measuring 150 × 300 mm were used for the impressed voltage technique. Additionally, cylinders measuring 100 × 50 mm were employed to assess water absorption rates. Detailed illustrations of these concrete specimens can be found in Figs. Before and after the aging process and before the exposure of the specimens to saturation, the thickness of coating materials was determined using a PosiTector 200 coating thickness gauge. Figure An accelerated aging test was conducted using a Toropol K-012 frost resistance test chamber, which is commonly employed for assessing the frost resistance of building materials. The specimens were subjected to cyclical freezing in air and thawing in water, while an electronic programmer monitored the cycles.To simulate freeze–thaw conditions in the laboratory, the test was performed at temperatures ranging between [−5] and [+ 15] °C. Two solutions were employed to simulate contaminated environments: regular water and urea solution with a concentration of 7%. The aging process, as depicted in Fig. The aging process used in this research is a proper procedure proposed by our research team.4. Cubic samples, as illustrated in Fig. The pull-off adhesion strength of coating applied to concrete surfaces was assessed in accordance with the ASTM D 7234-21 standardTo measure the adhesion strength, a DTH 500 DC testing machine with a maximum tensile strength of 5 kN was employed. Metallic dolls with a diameter of 50 mm and a height of 20 mm were utilized. To ensure accurate measurement, a circular notch was drilled to define the specific surface area to be measured. Subsequently, the metallic dolls were securely attached to the concrete surface using an epoxy material. Prior to the aging process, six pull-off tests were conducted for each coating material and environment type. The same procedure was repeated after the aging process.27 was followed to determine the absorption rate of water. The coating materials were applied to only one side of the sample under controlled environmental conditions at 20 ± 2 °C and 65 ± 5% relative humidity. After curing for 7 days, the samples were dried in an environmental chamber at [+ 50] °C for 3 days. To ensure internal moisture equilibrium, the specimens were then stored in a sealed container for 15 days. Weight measurements were taken at various intervals, including up to 6 h and once daily for 8 days.The ASTM C1585-20 Standard28 was employed. A constant direct current of 5 V was applied between a steel bar embedded in the concrete sample and the concrete surface. Furthermore, reinforced concrete specimens were partially immersed in a 3.0% NaCl solution during the test duration.To assess resistance to chloride ion permeability, the impressed voltage technique specified in the NT BUILD 356 standardThis test was conducted both before initiating the aging process and after seven days of completing the aging process in both coated and uncoated reinforced concrete samples. The test concluded upon the appearance of cracks or corrosion on the surface of the steel bar. The circuit assembly utilized an external DC power supply, YIHUA 3005D [0–30 V] 5 A, and a measurement data acquisition system capable of connecting ten samples simultaneously. The schematic design is illustrated in Fig. The pull-off adhesion strength results for concrete samples with and without coating material are depicted in Fig. 15, who reported values within the range of 1.5 and 3.2 MPa. Similarly, the adhesion strength values for the MI coating align with the findings of Flores-Colen et al.29, who obtained values higher than 1.2 MPa for mineral and cement-based coatings. On the other hand, the BR coating exhibited the least reduction in adhesion strength after the aging process, with reductions of 0.51% for samples saturated in water and 13.63% for samples saturated in urea. This behavior can be attributed to the low water absorption of the material resulting from the presence of hydrocarbon constituents30.The results indicate that exposure to urea led to a decrease in the adhesion strength for all coatings after the aging process. Among the coatings, EP and BW were the materials more affected, exhibiting reductions of 43.09% and 47.22%, respectively, compared to the pre-aging process results. The obtained adhesion strength values for the EP coating, ranging between 1.36 and 2.39 MPa, align with those reported by A. Almusallam et al.31. This heightened susceptibility to damage during freeze–thaw cycles can be attributed to the sensitivity of epoxy materials to moisture. The cycling of freezing and thawing can introduce additional moisture into the epoxy, particularly if there exist microcracks or pores within the material. The presence of moisture has the potential to weaken the mechanical properties of the epoxy, leading to degradation or failure and ultimately resulting in a reduction in adhesion strength32.In the case of EP coatings exposed to freezing temperatures, it is important to note that epoxy materials can undergo increased rigidity and become more vulnerable to fractures when subjected to stress33.The reduction in adhesion strength observed in BW coatings can be attributed to the formation of ice crystals during the freeze–thaw cycle. The repeated ingress of water followed by freezing can result in an increased moisture content within the material, rendering it more susceptible to damage. The expansion and growth of these ice crystals have the potential to disrupt the integrity of the bituminous material, ultimately leading to cracking and degradation34.In contrast, solvent-based coatings (BR) are generally less affected by freeze–thaw cycles compared to other types of materials. This is primarily due to their low water content, which significantly reduces the formation of ice crystals. Solvent-based coatings exhibit better flexibility and toughness compared to water-based materials, allowing them to withstand the stresses and strains associated with freezing and thawing cycles. Their increased resilience and resistance to cracking or delamination contribute to their ability to withstand freeze–thaw conditions35. The polymers can accommodate minor movements and stresses within the material, reducing the likelihood of crack formation and propagation, especially during freeze–thaw cycles or structural movement36. Additionally, it improves the adhesion to substrates and the bond strength and the most important the polymers create a denser and more water-resistant matrix, preventing water from entering the material and reducing the potential for freeze–thaw damage38.Finally, even though mineral coatings usually are more susceptible to damage from freeze–thaw cycles compared to other types of coatings due to its high porosity and the different coefficients of thermal expansion of its materials, in our case the presence of modified polymers in the mixture improved the performance and resistance of MI coating, by incorporating polymers, such as acrylics, latexes, or styrene-butadiene rubber (SBR), into the mix, the resulting composite exhibits improved resistance to cracking39 when concrete samples exposed to freeze–thaw cycles in saline and non-saline environments presented surface scaling and internal damages. According to Penttala, this deterioration is primarily attributed to the requirement for higher air content in low-strength concretes.Furthermore, the concrete samples without coating materials also experienced a reduction in concrete surface resistivity as a result of contaminants infiltrating the concrete matrix and exposure to freezing and thawing cycles. Similar results were reported by Penttala40:i.Glue failure [A]: Failure occurring between the epoxy used to attach the dollies to the concrete surface and the coating material.ii.Cohesive failure [B]: Failure observed within the coating layer itself.iii.Adhesive failure [C]: Failure that occurs between the coating material and the concrete surface.iv.Substrate failure [D]: Failure identified when the adhesion of the coating is stronger than the tensile strength of the concrete surface.Additionally, to categorize the results, the four types of failures resulting from the pull-off test were determined in accordance with the ASTM D 7234-2140, all types of coatings exhibit adhesive failure [C] after the aging process and exposure to urea due. This can be attributed to the high contamination levels on the concrete surface caused by the urea components and the aging effects. Substrate failure, as depicted in (j), (k), (l), and (h), is the preferred mode of failure for coatings on concrete41. However, it is important to note that the cases of substrate failure observed in Fig. Figure A physical examination was conducted on the samples to analyze the structural changes in the concrete samples protected with the various coating materials.42 in a study on the development of a self-repairing material able to remedy cracks and fissures in concrete using Bacillus pasteurii, Sporosarcina bacteria, and urea as a curing method. The study revealed the formation of calcite crystals accumulations on superficial cracks, which aided in filling them and reducing the infiltration of contaminants deeper into the concrete. Micrographs of the MI coating before and after the aging process with urea exposure are presented in Fig. For the MI coating, a noticeable accumulation of calcite crystal was observed after the aging process. This phenomenon can be attributed to the crystallization of urea on the concrete surface. similar results were reported by Ramakrishnan1 et al.8 reported that bitumen materials exposed to freeze–thaw cycles undergo changes in the content of different chemical compounds, leading to reduced durability of the material and adversely affecting the final adhesion strength values.However, in the case of BW and BR coatings, physical deterioration of the material was evident. Tengfei et al.27, where a linear relationship for the initial and secondary absorption was observed, with a correlation coefficient higher than 0.98. Figure 43. In their research, similar coating specimens were exposed to salt and regular water to assess their absorption properties. based on these findings, the MI coating exhibited the highest water absorption rate, followed by BR, BW, and EP coatings.The results of water absorption rate for both coated and uncoated concrete samples before and after the aging process are illustrated in Fig. Figure Table 44.The findings of the study reveal a compelling observation regarding the impact of aging processes on the thickness of coating materials. In particular, when subjected to both water and urea saturation, a discernible decrease in the coating material thickness becomes apparent. This reduction in thickness can have significant consequences for the overall properties of the coating, potentially resulting in a loss of color and compromised quality45.The aging process of coating materials involves exposure to various environmental factors, including moisture and chemical substances like urea. When the coatings are subjected to water saturation, the moisture can gradually penetrate the material, causing it to undergo physical changes. The water may seep into the coating, leading to a swelling effect and subsequently causing the material to expand. Over time, this expansion can result in a reduction in the thickness of the coating layer as the material becomes more porous or undergoes partial dissolution42.The current intensity curves for samples before and after freeze–thaw cycles, saturated with regular water and urea, are presented in Fig. 46, where the highest current value for samples with epoxy coating was reported as 8 mA. Furthermore, it can be observed that, for all samples, the use of coating materials extended the appearance of corrosion products, thus protecting the concrete matrix in a chloride ion environment.MI, BR, and BW were the most affected materials by the freeze–thaw cycles. Before the aging process, these samples registered current values of 4.28, 2.08, and 1.98 mA, respectively. These values increased to 26.41, 35.54, and 27.73 mA for samples saturated in regular water and 35.78, 19.72, and 33.37 mA for samples saturated in urea solution. in the case samples protected with EP coatings, the highest current value of 18.93 mA was obtained in the samples exposed to urea, showing an increase of 235.10% before freeze–thaw cycles and 297.57% for samples saturated in water. These results align with previous findings by with Aguirre et al.Figure The implementation of the impressed voltage technique in this study provides supplementary evidence that reinforces the relationship between absorption rate and coating degradation. The observed increase in current intensity, for all samples in both water and urea, and the accelerated appearance of corrosion products indicate a more rapid corrosion process when the absorption rate is higher. This conclusion is further reinforced by the substantial reduction in the time required for corrosion products to manifest. Specifically, the duration decreased from 386 to 30 h for EP, from 107 to 12 h for MI, and corrosion appearance was evident for BR and BW coatings after 77 h of exposure to the urea solution.Figure The pull-off adhesion strength of the different coatings presented a reduction after the freeze–thaw cycles. However, the presence of urea during the aging process led to a significant decrease in adhesion values, particularly for EP and BW coatings. The thickness measurements for these materials showed reductions of 34.46% and 61.69%, respectively, which likely contributed to the decrease in adhesion strength along with surface contamination by urea crystallization. In contrast, BR coating demonstrated a reduction of 13.10% in thickness and 13.63% in adhesion strength when exposed to urea solution, indicating it superior performance in terms of adhesion and thickness measurements after the aging process.The results of absorption rate analysis revealed that MI, EP, and BW coatings, when exposed to regular water and urea, as well as BR coating exposed to regular water, exhibited a decrease in water absorption rate compared to samples that were not exposed to freeze–thaw cycles. Although these results were unexpected considering the reductions observed in adhesion strength and thickness, the decrease can be attributed to the accumulation of crystals on the coating surface. Moreover, the physical examination analysis indicating the formation of calcite crystals on the concrete surface when cured in the urea solution. These crystals effectively filled superficial cracks, thereby reducing the material's permeability.The impressed voltage technique demonstrated an increase in current intensity after the freeze–thaw cycles. Furthermore, samples saturated with the urea solution exhibited higher current values compared to those saturated with regular water. However, regardless of the saturation solution, all types of coatings extended the appearance of corrosion products, with BR and BW coatings performing the best in this regard.The findings of this study provide valuable insights into the behavior of epoxy-based coatings under aging conditions, particularly in relation to exposure to urea. The results clearly indicate that the adhesion strength of the epoxy coating is significantly reduced after undergoing the aging process, with urea exposure being a particularly influential factor in this degradation. The results demonstrate a direct correlation between the increase in the current intensity and the weakening of bonds between the coating and the substrate in the case of exposition to urea solution.Overall, the findings indicate a decrease in adhesion strength and an increase in current intensity for all samples when exposed to regular water and urea. However, it is worth noting that there is no clear evidence of an increase in the absorption rate in the case or regular water. On the contrary, the results suggest that the absorption rate actually decreases with the aging process and water exposure. Further investigation is necessary to fully understand and elucidate this behavior.A noticeable reduction in coating material thickness after the aging process, whether through water or urea saturation, has implications for the visual appearance and protective qualities of the coating. To mitigate these issues, further research and development may be necessary to enhance the durability and resistance of coating materials against aging processes. The formulation of coatings could be optimized to withstand prolonged exposure to water, urea, and other environmental stressors.Based on the findings related to adhesion strength and absorption rate, the epoxy-based (EP) coating demonstrates its superiority as the optimal choice for providing effective protection to concrete structures. The results of this study provide substantial evidence supporting the suitability of EP coatings in safeguarding against deterioration and corrosion processes.The consistently high adhesion strength exhibited by the EP coating, even after the aging process, suggests its ability to maintain a robust bond with the substrate. This strong adhesion is crucial for ensuring long-term durability and protection, as it minimizes the potential for coating detachment or delamination. The ability of the EP coating to withstand the adverse effects of aging, including exposure to urea and regular water, further validates its suitability for concrete protection.This paper was limited to English articles, which excludes literature published in other languages and is also limited to academic publications. Moreover, it does not consider the results from industrial practice.


The objective of this study was to investigate the potential of arthroscopic scapholunate ligament repair and dorsal capsulodesis with suture anchor as a treatment option for patients experiencing symptomatic acute and subacute (< 3 months) scapholunate instability.From Jan. 2017 to Jan 2020, 19 wrists with acute or subacute tears of the SL ligament with symptomatic instability were treated with arthroscopic SL repair and dorsal capsulodesis with a suture anchor. The average time from injury to operation was 8.8 weeks  and the regular follow-up mean duration at our clinic was 26.5 months . The pain score according to the visual analog scale, wrist range of motion, grip strength, radiographic outcomes and functional outcomes according to the Modified Mayo Wrist Score (MMWS) were evaluated preoperatively and postoperatively during the follow-up period.P > .01).The Wilcoxon signed-rank test was used to compare the results: grip force improved significantly with 14.7% improvement of that on the normal side (P < .01); the postoperative MMWS was significantly better than the preoperative scores (P < .01). Of 19 patients of the series, 18 patients (94.7%) achieved good or excellent results according to the MMWS and 16 patients (84.2%) resumed their previous activities. Only one patient (5.3%) had residual laxity of the scapholunate ligament joint at 15 months of follow-up.All 19 patients had rupture and dissociation of the SL ligament in the radiocarpal joint. The total arc of wrist motion in the flexion–extension plane loss averaged 5.1° (At a minimum of two years of follow-up, patients with acute or subacute symptomatic dissociation of scapholunate ligament instability who underwent arthroscopic scapholunate ligament repair and dorsal capsulodesis with suture anchor treatment had satisfactory results.Level IV, case series. Scapholunate (SL) ligament injury, which is the most common cause of carpal instability, can lead to pain, loss of wrist function and progressive wrist arthritis .Early traditional open repair with capsulodesis have been shown to yield satisfactory results in some studies –7. HowevThere are few studies to demonstrate the outcomes of arthroscopic-assisted primary repair and dorsal capsulodesis in patients with acute or subacute phase SL ligament injury –13. ThosApproval for this study was obtained from our hospital’s institutional review board. During the period from January 2017 to January 2020, we treated 19 young patients sustained symptomatic SL ligament tear within 3 months of an injury. . These Plain radiographs were obtained from all patients, including loaded clenched fist films and unloaded ordinary plain films. Scapholunate widening was assessed by one surgeon and one radiologist. As clinical examination revealed ligament insufficiency, magnetic resonance imaging was routinely performed to identify the SL ligament rupture, bone edema and other associated acute injury. All patients underwent wrist arthroscopy not only to confirm the diagnosis but also to assess associated injury or the occurrence of the chondral lesion. Postoperative plain radiographs were evaluated for the stability between SL ligaments as well. Patients with chronic SL ligament injury (> 3 months), dorsal intercalated segmental instability, carpal bone fractures, or degenerative changes in their radiocarpal or midcarpal joints were excluded from this study.We used standard wrist arthroscopic equipment with finger trap, wrist tower distraction, and an upper arm tourniquet to ensure clear visualization during surgery. All patients received general anesthesia or axillary nerve block. A dorsal approach via 3–4, 6R, midcarpal radial (MCR), and midcarpal ulnar (MCU) portals were created. We explored and identified the SL ligament injury type according the Andersson-Garcia-Elias classification  from 6R Arthroscopic treatment procedures were the same in all patients; after confirming acute or subacute SL ligament tears, the other structures of the radiocarpal joint were also evaluated.After the operation, we applied a plaster cast for 8 weeks, and patients began a rehabilitation program that included gentle wrist motion and occupational therapy once the cast was removed. The K-wires were removed after 12 weeks postoperatively.P < 0.05.The normality of the data was verified using the Kolmogorov–Smirnov test, which showed that the data were nonparametric. The Wilcoxon signed-rank test was used to compare preoperative and postoperative values. Statistical analyses were demonstrated by using SPSS for Windows version 24 . Statistical significance was set at This study comprised 16 men and 3 women, with an average age of 24.1 years (range: 17–27 years)  and SL ballottement test. The clenched fist radiographs showed a wide interval (> 3 mm) in the SL joint of 15 patients. To confirm the diagnosis of acute or subacute tears of the SL ligament, evaluate ligament quality, and detect other lesions in radiocarpal or midcarpal joints, all patients underwent wrist arthroscopy surgery. Via the midcarpal portals, a step-off with Geissler grade III SL ligament tear was found in all wrists. The scaphoid avulsion SL ligament tear (type 1) was found in 17 patients while lunate avulsion SL ligament tear (type 2) was found in 2 patients, according to the Andersson-Garcia-Elias classification [P < 0.01), with a 14.7% strength increase from pre-operative phase to postoperative phase. The mean MMWS was 90.1 points , and the Wilcoxon signed-rank test revealed that postoperative scores were significantly better than preoperative scores (P < 0.01). At the 2-year follow-up, there was an average loss of 5.1° in the total arc of wrist motion in the flexion–extension plane . At the minimum 2 years follow-up, patients’ VAS and grip force improved significantly  exhibited laxity of the SL joint with a positive Watson test and SL joint diastasis in clenched fist view after 15 months following the surgery. Therefore, the patient underwent an SL ligament reconstruction surgery with palmaris longus tendon graft via open-dorsal approach. During the operation, limited vascularity remnants with fibrous scar tissue was found in patient’s SL joint. There was symptoms improvement and satisfactory results in patient’s VAS and MMWS after a year follow-up.As early diagnosis of acute SL ligament tear is challenging, wrist arthroscopy is recommended as a valuable tool not only for confirming the diagnosis and developing appropriate treatment modalities for SL ligament injuries, but providing quality of ligaments and other associated ligament injury or osteochondral lesion , 18, 19.Numerus procedures have been demonstrated to repair acute phase SL dissociation, including open approach to reinsertion the SL ligament by transosseous suture or anchor repair with dorsal capsulodesis and K-wire fixation . SeveralRecently, Carratalá et al.  publisheThere are some limitations in this study, including a small sample size and potential interobserver variability in physical findings. Besides, there were no control group patients with conservative treatment or traditional open procedure.The analytical results suggest that repairing the SL ligament with a suture anchor in patients with acute or subacute phase SL ligament dissociation can be a reasonable and minimal invasive surgical treatment, with satisfactory outcomes observed at a minimum follow-up of 2 years.


This paper conducts an experimental study on the axial compressive performance of FRP-steel-concrete composite columns. Nine short columns were produced and evaluated in the study, comprising of three concrete-filled steel tube reference columns and six FRP-steel-concrete composite columns, respectively denoted as “reference columns” and “composite columns”. Two categories of failure modes, including shear failure and waist drum, were observed from the experiments. The failure mode may trend toward waist drum from shear failure as more FRP layers were used. The number of FRP layers had a direct effect on the level of compressive strength attained, with a greater number of layers resulting in a greater increase in compressive strength. Moreover, a greater tensile strength and higher elastic modulus of CFRP sheets are more effective at improving the compressive stiffness of the columns. Finally, a four-stage confinement mechanism for FRP-wrapped steel tube concrete composite columns is proposed and discussed, through which the damage mechanisms of the composite structures are more rationally characterized. Concrete-filled steel tube (CFST) columns are widely utilized in civil engineering structures due to their significant enhancement of the performance of inner concrete facilitated by steel tube confinement ,2,3,4,5.In order to improve the pressure-bearing performance of CFSTs and their ability to resist environmental erosion, high-performance or functional materials have been adopted to wrap and reinforce CFSTs. The most typical method is the augmentation method of wrapping FRP layers ,12,13 anOne pioneer study on the axial bearing performance of FRP-wrapped CFSTs was written by Tao et al. . In theiAlthough previous studies have addressed the bearing strength of FRP-wrapped CFST columns, few studies have investigated the complex load-bearing effects of composite columns—particularly the failure mechanism of composite columns under axial forces, and the effect of different FRP materials (and thicknesses) on load-bearing capacity. This paper examines the characteristics and mechanism of compression failure in CFST columns strengthened with wraps composed of two different FRP materials with varying thicknesses. The failure mechanism of composite columns will be investigated to gain a deeper understanding of the factors affecting such mechanisms. Finally, based on the experimental results, a four-stage failure mechanism of an FRP-steel-concrete column under axial compress is proposed. The research methodology of this study is illustrated in D and thickness of the steel tubes were 100 mm and 2 mm, respectively. The composite column and the test setup are plotted in In order to study the effect of FRP wraps on the compressive performance of CFST, 9 short columns were fabricated, including 3 CFST columns (referred to as “reference columns”) and 6 FRP-steel-concrete composite columns  were manufactured. Detailed information about the columns is listed in For the convenience of expression, each specimen was named separately. As in 5 and 9.24 × 104 MPa respectively, as provided by the manufacturer. The steel tubes were made of 06Cr19Ni10 stainless steel , and the tensile strength of the steel material was 550 MPa. The average yield strength and Young’s modulus were measured as 207 MPa and 198 GPa, respectively, by the manufacturer. The concrete inner core was C60 grade. The compressive strength of the concrete cube was measured via a cube test block with a side length of 150 mm, according to the “Concrete Strength Inspection and Evaluation Standard” (GB/T50107-2019). The average compressive strength of the cubes was measured to be 61.4 MPa. To precisely determine the material properties of the FRP sheets, a tensile test of six FRP specimens (including three CFRP and three BFRP) was fabricated. The sizes of the FRP specimens were designed as 100 mm (length) × 10 mm (width) × 0.167 mm (thickness), respectively, according to the recommendation of “Carbon fiber sheets for structural reinforcement and repair” (JG/T 167-2016). The loading and failure diagram of the test for FRP sheets is depicted in The FRP wrapping utilized in this study was sourced from Jiangsu Green Material Valley New Material Technology Development Co., Ltd. Both CFRP (Carbon Fiber Reinforced Polymer) and BFRP  composites were employed in the sample specimens. The Young’s moduli of CFRP and BFRP were 1.67 × 10The axial compression loading test was conducted utilizing the Bonwe 3000 kN high-rigidity geotechnical concrete testing machine, and the test setup is depicted in Preloading: The column specimen’s axis was positioned at the central axis of the testing machine to ensure that the specimen bore the force on the axis and remained within the range of the elastic loading stage of the specimen. The loading process was initiated by preloading the specimen up to approximately 10% of the estimated ultimate load at a loading rate of 2 mm/min, and the specimen was subjected to preloading three times. This ensured that the instrument worked correctly and the influence of the gap between the test specimen and the tool was eliminated.Formal loading: Each specimen underwent monotonic axial compression testing, with the complete loading process utilizing a program for automatic control of axial displacement. The load was applied with the displacement-control mode at a rate of 2 mm/min. The specimen’s load increased until it was damaged  or the loading was stopped when the load declined to 80% of the peak load. The specimen was unloaded afterward.The measurement items for the columns’ monotonic axial compression test primarily entailed information on the vertical load, vertical compression, and horizontal and vertical strain in the middle plane of the specimen. The vertical load was evaluated using the built-in dynamometer of the press, and the vertical compression was calculated utilizing the vertical relative displacement of the loading plate at both ends of the specimen during the loading process as measured by the displacement gauges, as demonstrated in ccf and cf are the axial compressive strength of the inner concrete with and without confinement, respectively, p denotes the magnitude of the lateral confining pressure, and k denotes the strength-increasing coefficient of the inner concrete. From this formula, it can be seen that the stronger the confinement effect of the outer wrapped FRP and the steel pipe, the higher the bearing strength of the inner core concrete column.Considering that the FRP-steel-concrete composite short column is a composite structural system, the load-bearing state of the concrete core is the key factor affecting the bearing strength of the composite columns. The mechanical behavior of the concrete inside is then analyzed. The inner concrete of the columns is in a typical triaxial stress condition. Based on the discussion of Liu et al. , the axicσ1 is the axial press of the concrete. cσ2 and cσ3 are the principal stresses in the other two directions; they have the following relation:p can be adopted as follows:sσ and FRPσ denote the transverse stresses of the steel pipe and FRP sheets, respectively; st and FRPt denote the thicknesses of the steel pipe and FRP sheets, respectively; and D denotes the diameter of the inner concrete column. By combining Equations (1) and (4), the final expression can be obtained:Based on the force diagram of the FRP-steel layer in Equation (5) shows that for steel-concrete columns wrapped in FRP, if the circumferential confinement stress or the thickness of the confining circle of the outer steel pipe and FRP layer increases, the compressive strength of the composite column will be effectively improved accordingly.ssA is the cross-sectional area of the steel tube; cA is the cross-sectional area of the concrete; and cuf is the strength of the concrete cube.For the CFST column, the confinement effect of the steel on the inner concrete can be expressed as the following:uN is the bearing capacity of the CFST column, b is the influence parameter of steel refinement.Han et al.  proposedAfter testing the specimens, the damaged specimens are shown in a”~“b” have identical meanings to those of Similar testing phenomena were observed in the six composite columns. Take CC3 as an example. The load–displacement curve is plotted in The experimental findings revealed that the load–displacement curves of both the reference and composite specimens can be discerned into four distinct stages: linear elastic, elastic–plastic, descending, and steady. From Compared with the N1 specimen, CC1, CC2, and CC3 show longer elastic–plastic stages and larger peak loads due to the constraint effect of CFRP on the steel-concrete column, with the peak loads (bearing capacities) of 886.9 kN, 1030.6 kN, and 1165.3 kN, respectively. When the compressing load reaches the peak, FRP begins to rupture, and the load–displacement curve enters the descending stage. When the load reaches the lowest point, FRP fractures extensively, and thereafter, the specimen continues to be compressed and the steel material remains in the yield stage. When entering the steady state, the load of the specimen is in the micro-fluctuation stage. Comparing the curves of the CC1, CC2, and CC3 specimens, it can be concluded that, with the increase in the number of CFRP layers, the slope of the load–displacement curve in the elastic stage gradually increases, and the starting point of the elastic–plastic stage increases while the corresponding displacement decreases.The load–displacement curves of the CB1, CB2, and CB3 specimens are illustrated in In summary, during the linear elastic stage, a similar phenomenon of the load–displacement curve of CFRP- or BFRP-constrained specimens could be observed. This may be attributed to the small expansion deformation of the concrete at this stage, resulting in limited compression on the steel pipe. Consequently, the steel tube remains at the linear elastic stage with the FRP and the steel tube deforming in coordination, resulting in small forces on the FRP. As the specimen was continuously compressed and entered the elastic–plastic stage, the concrete underwent significant expansion deformation, the steel tube endured large stress and produced plastic deformation, and the restraining effect of the FRP became increasingly significant. The ultimate bearing capacity of the steel tube enhanced by CFRP is more significant than that by BFRP, which can be attributed to the bigger elastic modulus and higher tensile strength of CFRP. In addition, more FRP wrapping layers cause an increase in the bearing capacity of the composite columns, indicating that wrapping FRP sheet is an effective method to improve the bearing performance of CFST columns.syR is the strength-yield ratio, and yf and cf are the yield strength and ultimate strength of the columns, respectively.Based on the results of The strength-yield ratios of all nine specimens were calculated as 1.17 (N1), 1.17 (N2), 1.17 (N3), 1.11 (CC1), 1.23 (CC2), 1.20 (CC3), 1.13 (CB1), 1.17 (CB2), and 1.19 (CB3), as presented in The aforementioned loading test results of composite columns demonstrate that the outer coating of FRP will change the load-bearing failure mechanism of the short column and enhance its bearing capacity. The change in this load-bearing mechanism is embodied in the confinement mechanism of the FRP layer, which is discussed in this section, as shown in (1)Stage I: steel dominating confinementIn the initial loading stage, the axial compression effect is minimal, and the lateral deformation of the inner concrete results primarily from Poisson’s effect and the emergence of microcracks. As activation is insufficient at this stage, only a slight rise in total confining pressure is observed. The bulk of the confinement occurs as a result of the steel pipe, with the FRP being inconsequential due to inadequate activation. Throughout this stage, the axial stress–strain reaction of the internal concrete registers on the first ascending branch.(2)Stage II: FRP-steel multiple confinementsWith an increase in axial strain, gradual radial dilation is observed in the internal concrete, accompanied by the initiation and propagation of minor cracks. Consequently, the steel and FRP confinement forces become fully activated, inducing a much faster acceleration in their increase rate compared to that observed earlier. This surge in forces leads to the swift development of total confining pressure. To accurately determine the boundary of this phase, this deviation must be captured. Additionally, the steel tube exhibits yielding at the end of the second stage, which can be defined as a critical boundary line. The duration of this stage hinges on the yield strength and yield strain of the steel tube, with higher values of these parameters extending the duration of the second stage proportionately.(3)Stage III: FRP dominating confinement.uε), leading to the rupture of the FRP hoop Stage IV: steel dominating confinementFollowing the third stage, the FRP hoop layers are pulled off while the steel pipe remains in a plastic stress state following yielding. During the fourth stage, the confinement pressure is primarily borne by the steel pipe, resulting in the external confinement force being returned to the confining effect of the steel pipe in the concrete inner core. The confinement mechanism during this stage was similar to that observed in a pure steel tube concrete column . As the compression continued, the final failure of the specimen is reflected in the crushing of the concrete core.Drawing on experimental research, this study investigated the bearing mechanism and damage process of short columns, including pure steel tube concrete columns and FRP-wrapped steel tube concrete composite columns. The failure process, failure mode, load–displacement relationship, strength-yield ratio, and initial stiffness were discussed. The following conclusions can be drawn:(1) Two failure modes, shear failure and waist drum, were observed during testing. For FRP-wrapped steel tube concrete composite columns, the failure mode may trend toward waist drum from shear failure as more FRP layers are used. Due to the strong external combining constraints of the FRP and steel tube, the inner core concrete column is always in a state of obvious triaxial compression. Consequently, the failure of the concrete column is more inclined to material destruction, resulting in the waist drum failure mode.(2) When compared with the pure steel tube concrete column, the CFRP- and BFRP-wrapped columns exhibit larger peak loads, indicating that the effective use of FRP wraps can significantly increase the compressive strength of steel-concrete columns. Furthermore, the number of FRP layers has a direct impact on the level of compressive strength attained, with more layers resulting in a greater increase in the compressive strength.(3) The incorporation of wrapped FRP sheets has no direct effect on the strength-yield ratio of the composite specimens. However, the initial stiffnesses  of CFRP-reinforced specimens are significantly greater than those reinforced with BFRP. This discrepancy indicates that the higher elastic modulus and greater tensile capacity of CFRP sheets are more effective at improving the compressive stiffness of columns.(4) This research proposed a four-stage confinement mechanism for FRP-wrapped steel tube concrete composite columns, comprising the following stages: Stage I—steel dominating confinement, Stage II—multiple confinements by both FRP and steel, Stage III—FRP dominating confinement, and Stage IV—steel dominating confinement. The confinement effect during stages II and III is primarily influenced by the mechanical properties of the FRP layer, with higher-strength FRP layers being the most effective at improving the ultimate bearing strength of the specimens.


E. coli populations under subinhibitory concentrations of combinations of antibiotics with synergistic, antagonistic, and additive interactions. We then used these results to expand our previously developed computational model to account for the effects of antibiotic interaction. We found that populations grown under synergistic and antagonistic antibiotic conditions exhibited significant differences from predicted behavior. E. coli populations grown with synergistically interacting antibiotics developed less resistance than predicted, indicating that synergistic antibiotics may have a suppressive effect on resistance development. Furthermore E. coli populations grown with antagonistically interacting antibiotics showed an antibiotic ratio-dependent development of resistance, suggesting that not only antibiotic interaction, but relative concentration is important in predicting resistance development. These results provide critical insight for quantitatively understanding the effects of antibiotic interactions in wastewater and provide a basis for future studies in modelling resistance in these environments.While wastewater is understood to be a critically important reservoir of antimicrobial resistance due to the presence of multiple antibiotic residues from industrial and agricultural runoff, there is little known about the effects of antibiotic interactions in the wastewater on the development of resistance. We worked to fill this gap in quantitative understanding of antibiotic interaction in constant flow environments by experimentally monitoring  A recent systematic analysis of global AMR has predicted that there were an estimated 4.95 million deaths associated with bacterial AMR in 20193. Contributing factors to AMR in human medicine  have been well documented7; however, environmental distribution of antibiotics and its impact on AMR has received less attention9. Wastewater specifically has been shown to be a reservoir of resistant pathogens, often stemming from the antibiotic pollution present in runoff from industrial and agricultural sources10. Furthermore, computational modeling of wastewater has shown that even low concentrations of antibiotic residues can lead to the development of AMR11. This is particularly of concern in low-income communities which can often have open sewer systems and little access to wastewater treatment, putting them at particular risk for deadly drug-resistant outbreaks.Antimicrobial resistance (AMR) is a rapidly evolving critical threat to global health with the potential to lead to financial losses of as much as $100 trillion USD11. However, experimental validation of the model was limited to systems with only one antibiotic residue. The interaction between two or more antibiotics is of particular interest, with combination therapy used both clinically to increase treatment efficacy and lower the risk of AMR development as well as prophylactically in livestock to prevent infections from developing and spreading across these large animal populations. The interaction between two antibiotics from different classes have previously been shown to affect resistance acquisition12. Synergy is the interaction of multiple drugs to have a greater killing action than the sum of their parts while antagonism is the interaction of multiple drugs to have reduced killing action than the sum of their parts. Drugs that do not interact, or in other words have the killing action equal to the sum of their parts are said to have an additive interaction. Interestingly, synergy between two antibiotics has also been shown to increase the likelihood of resistance population development at subtherapeutic doses12. However, the effects of antibiotic interaction on the growth of resistant populations in wastewater settings has not previously been observed. Wastewater can often have many antibiotic residues present, which have the potential to interact with each other either synergistically or antagonistically. For example, antibiotic residues found in water sampled from hospital sewage in Sweden included the drugs doxycycline, erythromycin, and ciprofloxacin among others13. This is of note because doxycycline and erythromycin are known to have a synergistic interaction, while doxycycline and ciprofloxacin are known to have an antagonistic interaction12. Antimicrobials in combination often have different mechanisms of action, so it is possible that interactions between the multiple antibiotic residues in wastewater will have unique effects on the development of antimicrobial resistance. However, quantitative data on these effects of antibiotic interactions on AMR in wastewater is lacking. We aim to fill this critical gap in knowledge about the effects of antibiotic interactions on AMR in continuous flow environments such as wastewater through an iterative approach to computational modeling and experimental validation. While the developed model will be generalized rather than specific to a particular wastewater setting, it can be applied to various geographic locations and seasonal conditions.Previously, we have developed a computational model of resistance acquisition in continuous flow environments based on known mechanisms of bacterial growth and mutation as well as experimental validation11. Bacteria specific input factors include the growth rates of antibiotic susceptible and resistant strains and mutation rates in response to subinhibitory concentrations of antibiotic. The antibiotic specific inputs, such as bactericidal activity, allow for the study of the effects of antibiotic pollution on the development of resistance. Additionally, environmental inputs, including physical inflow and outflow rates and antibiotic residue concentrations, allow for the modelling of resistance development in a variety of settings of interest. Ordinary differential equations incorporating these input parameters were used to model an output of resistant bacterial populations over time, thus allowing for the prediction of resistant population development (Tables C1 and C2) over time as well as equations modelling the susceptible population (S), two populations of bacteria that are resistant through chromosomal mutation to each antibiotic individually (R1 and R2), and a population multiresistant to both antibiotics 1 and 2 from chromosomal mutation (Rm) (Table E) and the antibiotic clearance rate (ke). Bacterial population growth is modelled with terms for growth rate (α), which is limited by an experimentally derived carrying capacity (Nmax). The antimicrobial activity of the antibiotics are modelled by the killing rate term in response to each antibiotic  and outflow (kT) rates (Table m) which are concentration dependent.The model used in this paper is based on a previously developed model of the growth of antibiotic resistant bacterial populations in wastewater that builds on prior studies and extends to incorporate a variety of critical inputs which can be broadly classified into bacterial parameters, environmental parameters and antibiotic parameterst Tables  and 3. T14. Experiments were done with antibiotics which have been found to be present in wastewater with known interactions with one pair of antibiotics exhibiting additive interaction (12.5 mg/L Rifampicin + 4 mg/L Streptomycin), one pair of antibiotics exhibiting synergistic interaction (1.5 mg/L Doxycycline + 64 mg/L Erythromycin) and one pair of antibiotics exhibiting antagonistic interaction (1.5 mg/L Doxycycline + 0.0375 mg/L Ciprofloxacin)17. Drug interactions were confirmed using checkerboard assays and calculating fractional inhibitory concentration (FIC) values as described in Bellio et al. where combinations with an FIC less than 0.5 were considered synergistic, those with an FIC greater than 4 were considered antagonistic and those with an FIC between 0.5 and 4 were considered to have an additive interaction18. Experiments were initialized with inoculation of 20 mL LB media with E. coli MG1655 in static conditions at 37 °C. Then, inflow and outflow of the antibiotic-containing LB media at two concentration combinations was started. During the course of the experiment, 200 µL of each culture condition was sampled daily, and the concentrations of total bacteria (Nmax) and resistant bacteria were calculated through plating on drug-free and selective LB agar containing 8× MIC Drug A and/or 8× MIC Drug B respectively.Experimental validation of the model was done using the eVOLVER system, which is an automated, highly flexible platform allowing for scalable continuous culture microbial growth and independent, precise and multiparameter control of growth conditions such as temperature and flow rateThe first antibiotic combination tested was Rifampicin and Streptomycin at half of their respective MICs (12.5 mg/L Rifampicin + 4 mg/L Streptomycin). Checkerboard assays confirmed an FIC of 1 indicating additive interaction between these two drugs. Model prediction was made based on previously determined parameter values from eVOLVER experiments with each drug in isolation. The experimental results with the eVOLVER qualitatively verified the model prediction with dominant susceptible and Rifampicin-resistant populations as well as a significant population of bacteria resistant to both Rifampicin and Streptomycin . These experiments found an antibiotic-ratio dependent effect. Several changes were made to the previous model to account for the ratio dependency of the resistant population behavior (Table The third antibiotic combination tested was Doxycycline and Ciprofloxacin which have been observed as residues in wastewater samples and have previously found to interact antagonisticallyugs Fig. a. Howeve19. Though the current model is limited in its ability to model bacteria in biofilm, it still succeeds in being able to predict the resistance development occurring in the continuous liquid culture. Thus, it still can have use as a predictive tool for understanding AMR in wastewater.This adjusted model was able to capture the relative behaviors of the different resistant populations for differing ratios of Dox and Cip, notably the transient Doxycycline-resistant population giving way to the combination resistant population Fig. . FurtherE. coli populations grown in additively interacting antibiotic combinations grew predictably according to the previously developed model. This confirmed our assumption that in the absence of antibiotic interaction, resistance to each antibiotic will develop independently. We also found that E. coli populations grown under synergistic and antagonistic antibiotic conditions exhibited significant differences from predicted behavior. E. coli populations growing in subinhibitory concentrations of synergistically interacting antibiotics showed the development of less resistance than predicted. Interestingly, this indicated that synergistic antibiotics have a suppressive effect on antimicrobial resistance development in continuous flow conditions. This is in contrast to previous studies in non-flow conditions which found that synergy increased resistance acquisition20. Thus, our novel finding suggests that differing flow conditions significantly alter resistance acquisition patterns and studies in continuous flow conditions are necessary for understanding environments like wastewater. Additionally, we found that E. coli populations grown with antagonistically interacting antibiotics showed an antibiotic ratio-dependent development of resistance. This behavior has previously been observed in non-flow conditions, though only with single-resistant populations17. Our studies further this finding to multi-resistant populations and also find that not only antibiotic interaction, but relative concentration is important in predicting resistance development in continuous flow environments.Overall, through our integrated computational and experimental approach, we were able to model the development of antibiotic resistance in response to subinhibitory combinations of antibiotics exhibiting additive, synergistic and antagonistic interactions. We demonstrated 22. In order to develop quantitative models of resistance development in wastewater incorporating both planktonic bacteria and biofilm, experimental methods for controllably maintaining both populations in continuous flow conditions will need to be developed.Though we have been able to draw a number of conclusions about the effects of antibiotic interaction on resistance development in wastewater, we note that our studies do have limitations. Primarily, we only studied a limited number of antibiotic combinations and as such cannot conclude the effects of all antibiotic interactions. Future studies investigating a wider array of antibiotics could elucidate further findings on specific combinations in constant flow conditions. Additional studies looking at three or more antibiotics in combination with varying interactions or media conditions better approximating wastewater than the LB broth used here would also be a step forward in modelling the types of complex conditions that would be found in wastewater. Another major area of interest in developing the model would be to further integrate the role of biofilm in resistance development. While biofilm has been observed in samples both up- and downstream from wastewater treatment plants and is a known environmental reservoir of resistance, there is limited quantitative understanding of how this resistance develops, particularly in response to antibiotic residues present in wastewaterDespite these limitations, experimental validation demonstrated our ability to model resistance development in subinhibitory antibiotic concentrations of antibiotics with varying interactions. We were able to determine that synergistic interaction have a suppressive effect on resistance development. Additionally, more complex resistance development patterns were observed in the case of antagonistic interaction where we found an antibiotic ratio-dependent behavior. This has important implications for understanding the effects of industrial and agricultural antibiotic runoff in wastewater and determining acceptable antibiotic concentrations and combinations when treating wastewater. These findings can be used as a basis for public health policy makers and the developed model can be utilized as a tool alongside bacterial or antibiotic sensors to predict resistant population emergence in different sewage and wastewater conditions where multiple antibiotic residues may be present.