In a human immunodeficiency virus (HIV) clinic for children and their families in Eswatini, we sought to understand the use of antibiotics and identify specific areas for improvement. We performed a retrospective patient chart review as part of a quality improvement (QI) initiative to assess antimicrobial use before and after implementation of a standardized antimicrobial guide. For each prescribing period, 100 random patient encounters were selected for review if the indication for antibiotics, duration, and dose were consistent with World Health Organization (WHO) guidelines. Two physicians reviewed each encounter using a structured abstraction tool, with a third resolving discrepancies. Results were analyzed using a chi-square test of proportions and a structured survey was performed to assess perceptions of the guide. After the implementation of an antimicrobial guide, there was a significant decrease in the proportion of clinic visits with an antibiotic prescribed (p < 0.001). Incorrect indication for antimicrobial use decreased from 20.4% in the initial period to 10.31% and 10.2% but did not reach significance (p = .0621) in the subsequent periods after implementation. Incorrect dose/duration decreased from 10.47% in the initial period to 7.37% and 3.1% in the subsequent periods, but this was also was not significant (p = 0.139). All prescribers who completed the survey felt that it positively impacted their prescribing. Our study found that an antimicrobial guide reduced and improved the prescription of antimicrobials, demonstrating practical solutions can have a lasting impact on prescribing in low resource settings. Global antimicrobial consumption is estimated to have increased by 36% from 2000 to 2010 , 5 whichAntibiotic prescribing, especially in LMICs, can be challenging. This is due to differing levels of prescriber training, limited access to resources for correct antibiotic choice and dosing, and stock outs or general unavailability of optimal antibiotic choices. In order to evaluate antibiotic prescribing patterns on a facility level, the World Health Organization (WHO) has developed prescribing indicators for health care facilities (WHO-drug use indicators). These indicators, aimed at increasing attention on antibiotic stewardship at a local level, have resulted in a number of hospital-based interventions across sub-Saharan Africa with an observed decrease in antibiotic use without increasing morbidity and mortality at those institutions , 14. WhiMany LMICs in sub-Saharan Africa lack the ability for targeted diagnostic testing, such as blood cultures, rapid antigen tests, or nucleic acid amplification tests, in order to target antibiotic prescribing , 17, 18.Our quality improvement project sought to investigate the prescribing patterns at a family-centered HIV clinic in Eswatini and investigate whether a targeted “Antimicrobial Guide” providing a quick reference for antimicrobial choices, weight-based dosing of antimicrobials, and the location-specific drug formulations available, could improve use of antibiotics. To our knowledge, this is the first quality improvement (QI) project on antimicrobial stewardship in an outpatient clinic in Eswatini, though the approach could be used in other geographic and treatment settings.This study took place at the Baylor College of Medicine-Bristol-Myers Squibb Children's Clinical Centre of Excellence (COE) in Mbabane, Eswatini which serves children with HIV and their families. Eswatini has the highest prevalence of HIV in the world among adults aged 15 to 49 years at 27.3% with 13,000 children (age 0–14) living with HIV . AlthougTrichomonas vaginalis infection). Clinician prescribing was evaluated against the guide as well as current medical organization guidelines such as the Eswatini Ministry of Health, the WHO and the American Academy of Pediatrics. Incorrect indication was any prescription in which the prescribed antibiotic did not treat the most likely organisms for that syndrome or was unnecessary . Each encounter was reviewed by at least two clinicians  working independently. Any discrepancies or uncertainties were resolved after review and discussion with the third reviewer and group consensus.This was a pre-post quasi experimental study to assess the efficacy of an antimicrobial prescribing guide and standardized training. A retrospective patient chart review of encounters was conducted in three distinct time periods, from January 1 to April 30, 2019 (Period 1), from July 1 to September 30, 2019 (Period 2), and from October 1 to January 17, 2020 (Period 3). The antimicrobial guide was introduced in May 2019 and continues to be used. Two time periods following the guide introduction were chosen to determine if changes in prescribing were sustained. The percentage of encounters with antibiotic prescribing in each period was calculated from the electronic medical records. Trimethoprim/sulfamethoxazole (TMP-SMX) was excluded as it is usually prescribed for prophylaxis in HIV patients. The overall percent of encounters in each time period in which antibiotics were prescribed was calculated from this data. From those encounters in which antibiotics were prescribed , 100 encounters were randomly selected, via a random number generator, to review the indication for antibiotics , and the prescribed dose and duration. Dose and duration were interpreted as a single parameter due to their being acceptable dose/duration alternatives for an antibiotic for a syndrome , TN , AK1 , and AK2  collaborated to create an Antimicrobial Guide for the clinic, based on country guidelines, WHO guidelines and other available resources. The guide was not meant to be all encompassing but tailored to provide guidance on commonly encountered diseases or clinical syndromes  and more rare diseases requiring specific therapy. The guide included the type and dosage of antibiotic recommended for adults and children and reflected the medications available in the clinic formulary. Alternative recommendations were offered in order to account common medication shortages. Additionally, weight-based charts for specific doses of antibiotics were provided for quick reference to increase efficiency of providers. Figs Standardized training on the use of the antimicrobial guide was provided for clinical staff with implementation of the guide in May 2019 and on an as-needed basis through targeted “patient-specific” teaching in response to the interim reviews. The Antimicrobial Guide was placed in each clinic consultation room as well as the Pharmacy for ease of reference and continued staff to staff education. Staff were provided the opportunity for feedback on the guide which was integrated into the guide on an ongoing basis.To control for provider bias in interpretation of “correct” versus “incorrect” prescribing choices by time period, patient encounters reviewed by the initial two physicians were randomly mixed and provided to a third physician reviewer, blinded to the time point of the prescription. This third provider agreed with the interpretation of prescribing choices indicating the clinicians were not influenced by the desire to show improvement in prescribing patterns after the implementation of the antibiotic guide. Although it was impossible to blind the first two physicians to the name of the individual who prescribed the antibiotic reviewed based on the set-up of our electronic medical record, the third physician was always blinded to this and no physician reviewed their own prescribing.In addition to objective measures of improved prescribing, a qualitative assessment of how providers felt about the antimicrobial guide was conducted through an anonymous semi-structured survey. The questionnaire was provided to ten clinicians (doctors or nurses) and two pharmaceutical staff with a 100% response rate. The questionnaire asked whether the provider used the antibiotic guide, how often the antibiotic guide was used, how it impacted care, what types of diseases and antibiotics the guide was used most often for, and if they would recommend the guide to other clinics. The questionnaire is included under Results of the retrospective chart reviews were analyzed to determine the impact of the antimicrobial guide by comparing the results , and % of encounters with an incorrect dose and/or duration) of the initial time period prior to guide implementation to the subsequent time periods after the intervention. Chi-square tests were conducted to analyze the impact of the intervention by comparing the results of three time periods; the initial time period prior to guide implementation and two subsequent time periods after guide implementation. If the chi-square tests were significant for all three periods, the pairwise chi-square tests were conducted to compare the first and second period, the first and third period, and then the second and third period. The p-values from pairwise chi-square tests were adjusted by the Holm method to counteract the problem of multiple comparisons. A p-value less than .05 was considered statistically significant. Two time periods post implementation were selected in order to see if the impact was sustained. Fisher’s exact test was used, instead of chi-square test, when small cell sizes  were present. The results of the provider survey were summarized but no statistical analysis was performed.This study utilized de-identified patient data extracted from the electronic medical record (EMR) database of the Baylor COE with the assistance of the data manager with permission to collect the data from all relevant parties, including the clinic director and pharmacotherapy committee. It was considered a quality improvement measure with no impact to human subjects so did not require informed consent or specific Institutional Review Board approval.Patient demographics from the three prescribing periods are summarized in In all three prescribing periods, metronidazole, erythromycin, and doxycycline were the most commonly prescribed antibiotics. The most common diseases/clinical syndromes included skin and soft tissue infections, respiratory infections, and urogenital infections. There did not appear to be any increase or decrease in any specific infections/clinical syndromes or antibiotics. In the initial prescribing period , 9.83% (538/5471) of patient encounters involved the prescription of an antibiotic. In subsequent time periods (post-implementation) 6.99% (440/6293) and 7.02% (446/6355) of encounters involved an antibiotic prescription. Using a chi-square test comparing all three time periods gave a p-value (p < 0.001), meaning at least one of the periods was significantly different from other periods. The p-value for Period 1 and Period 2 was <0.001, Period 1 and Period 3 was <0.001, and Period 2 and Period 3 was 0.9817.Ten prescribers and two pharmacists voluntarily and anonymously completed the Provider Questionnaire. All reported using the guide at least weekly. The prescribers reported using the antibiotic guide most for clinical symptoms involving skin/soft tissue infections (the highest at 11/12 survey respondents), ear/nose/throat infections (8/12), pneumonia (6/12) and sexually transmitted infections (6/12). When asked about specific antibiotics the guide was referenced for, cloxacillin was the highest use (8/12 survey respondents), followed by amoxicillin (7/12), metronidazole (5/12) and acyclovir (5/12). One provider commented “It makes my job easier; I spend less time now thinking about choice of antibiotic to use.” Another stated “It’s really helpful and straight to the point.” Of the two pharmacists, one felt that the guide had led to 50% decrease in number of daily phone calls to ask prescribers to correct an antibiotic prescription and the other felt there was a 75% decrease in daily call volume.Antibiotics were a ground-breaking advancement in the fight against infectious diseases and are a vital tool in the armamentarium of clinicians. Despite this benefit, overuse and misuse of antibiotics threaten to undermine their effectiveness due to the development of drug-resistant bacteria . The impThe development of the guide was informed by antimicrobials that were available at the clinic, so prescribers would not have to consider antibiotic choices that were unavailable. We believe pragmatic contextual adaptation of more universal tools for stewardship can contribute to efficacy. In addition, when possible we offered several options for each clinical syndrome so that in the case of a pharmaceutical stock out, there would be other options available. Lastly, we recognized that weight-based dosing can be complicated and time consuming, so we provided easy-to-use dosing charts for the formulations available within our pharmacy.We found a statistically significant decrease in patient encounters in which an antibiotic was prescribed, meaning that providers were more thoughtful about whether an antibiotic was necessary. This continued for both time periods following guide implementation indicating that this change was sustained. We observed some evidence of a decrease in the number of antibiotics prescribed without a documented indication, and a reduction in incorrect antibiotic choices and dosing; however, our ability to detect statistically meaningful changes was limited by the sample size evaluated. Engagement of pharmacists in the intervention also may have limited our ability to detect ongoing improvements as pharmacists contacted prescribers to provide stewardship throughout the intervention.Previous interventions on behalf of antimicrobial stewardship have primarily been based at the provider level, but pharmaceutical and patient level interventions have also been shown to be beneficial. One meta-analysis of educational interventions to improve antibiotic prescription and dispensing showed that of 47 studies conducted in the outpatient setting, 33 utilized the dissemination of printed/audiovisual educational materials similar to the antimicrobial prescribing guide used in this study . AnotherOur study has several limitations. It is possible that improvements in prescribing patterns were seen with our chart review due to prescribers being aware that their antibiotic use would be reviewed. While no formal announcement was made to prescribers that chart reviews were being done, it was also not kept secret and it is possible that prescribers heard about the study and adjusted their practices. Even if this was the case, provider questionnaires showed that they overwhelmingly utilized the guide and found it helpful, making it more likely that use of the guide resulted in improved prescribing. As mentioned, the guide was introduced in May 2019, and our subsequent reviews did not begin until July 2019 to allow time for prescribers to settle into routines and the subsequent reviews covered a six month period, making it unlikely prescribers maintained a change in behavior for this extended period of time simply based on a fear of being audited (Hawthorne effect). A limitation, as with all printed materials, is that the guide is not easily updated to reflect changes in the clinic formulary or new emerging research. Despite this, we feel that reviewing the guide every 6 months will allow for a functioning, helpful guide without too much of an administrative burden. Data costs and slow internet speeds in many LMICs mean that hard copies of guides are preferred to online tools. In addition to continuing to review the guide on a regular basis, next steps should include reassessing the guide’s impact over the coming years and evaluating the implementation of a similar guide in other settings, such as other outpatient clinics or inpatient settings.Overall, our study highlights that an outpatient facility-level intervention, in the form of an antimicrobial guide, pharmacist engagement and targeted clinician training on antimicrobial stewardship and infectious syndromes, can have a positive impact on antibiotic prescribing patterns and is deemed a valuable tool by prescribers and pharmacists. Antimicrobial guides and stewardship training should be more broadly implemented in LMICs. Strategies that involve patient engagement should also be considered to improve antibiotic use at the outpatient facility level in LMICs.S1 File(PDF)Click here for additional data file.


This paper presents the methodology for predicting the mechanical performance of structural elements made of polymer concrete (PC). A vinyl ester polymer concrete composition and the results of experimental studies to determine the basic mechanical properties of the material are presented. Following the strategy for sustainable development in the building industry, the material cost of polymer concrete was lowered by reducing the consumption of raw materials and the partial replacing of the microfiller fraction with recycled waste products—calcium fly ash. An accurate computational model enabling stress analysis is a convenient way to verify the suitability of PC as a construction material in structural applications. Due to difficulty in deriving an accurate analytical formula, numerical approximation (finite element method) was used as a method for solving the problem. Constitutive modeling of PC is a very important aspect of the strength calculations and here it was done within the framework of elasto-plasticity. Numerical evaluation of the static bearing capacity of PC manhole covers is shown as an example of the proposed FEM methodology. The results of computer simulations were compared with laboratory tests. Finally, the adequacy of the numerical modeling for testing new construction and material improvements is discussed. The study showed that the concrete damaged plasticity material model can be effectively used for the description of PC mechanical behavior. The use of polymeric materials in concrete formulations is well known, but in recent years the applications of polymer concrete (PC) have been broadened . From thAnother potential application, which is a fast-emerging technology and a source of debate, is the use of PC for 3D printing in the construction industry. The use of polymer concrete in that context, contrary to cementitious-based concrete types, would provide a finished material that would be more impermeable, stronger, more durable and cure much more quickly .Three principal classes of polymer concrete materials exist: (a) polymer-cement concrete (PCC), (b) polymer-impregnated concrete (PIC) and (c) polymer concrete (PC) . The resPolymer concrete is a mixture of aggregates and resins or monomers that are used to replace Portland cement as a binder. The resultant polymer concrete mix hardens by polymerization after it is placed. Thermoset polymers are typically used as the matrix material, as the main advantage of these materials are low viscosity and the possibility of curing at room temperature or lower. Among the numerous thermoset polymers, unsaturated polyester (UP), vinyl ester (VE), methyl methacrylate (MMA), furan resin (FU) and epoxy resins have been applied in PC .For example, orthophthalate unsaturated polyester resins combined with methyl ethyl ketone peroxide as an initiator are commonly used as binders ,8. Orak While epoxy resins are commonly used, much attention has been focused on the use of cheaper vinyl monomers such as polystyrene , methyl-The suitability of polymer concrete as the construction material in any structural application should be verified by the direct testing of the prototype. This allows for evaluating the final product, but not predicting or optimizing its features. The results are only valid for a given geometry and loading condition so cannot be easily generalized. Simultaneously, many fundamental studies on the mechanical properties of polymer concrete are available. These studies on the strength of polymer concrete under uniaxial tension–compression or more complex stress conditions can be used to predict the performance of any structure. An appropriate numerical model based on experimental tests can be used to design and evaluate the mechanical performance of any structural elements made of polymer concrete.The objective of this study is to develop methodology for predicting the mechanical performance of structural elements made of polymer concrete. The derivation of analytical formulas is difficult since the behavior of this material is highly nonlinear. An accurate computational model is crucial in the design process and the stress analysis can be accomplished by means of finite element modeling . An apprThe structure of the paper is as follows: in In www.ciechresins.com) in the chemical plant Organika-Sarzyna, Poland was used. The properties of vinyl ester resin are summarized in The resin is the main binding material for the polymer concrete. The choice of resin was dictated by the operating conditions that the example product (manhole cover) has to withstand. As a result of the operation of solar radiation, the surface of the cover can heat up to about 60 °C. Unfortunately, this temperature is close to the polyester resin softening point. In contrast, vinyl ester resin has increased thermal resistance—it can be used up to a temperature of about 100 °C. For this reason, vinyl ester resin was chosen for the study. It is typically used when high durability, thermal stability and high corrosion resistance are needed. Vinyl ester, in comparison to polyester and epoxy resin, is in the middle of the performance spectrum. Vinyl ester, even if not as cheap as polyester, provides a lower cost than epoxy resin. It is made by the reaction between an epoxy resin and an unsaturated monocarboxylic acid. Essentially, it comprises a base of polyester resin strengthened with epoxy molecules. Vinyl ester has fewer open sites in its molecular chain. This causes some outstanding features like broad chemical resistance and low water penetration. It is more tolerant of stretching than polyesters. This makes it easier for it to absorb impact without damage. Additionally, it exhibits low peak exotherms and less shrinkage during curing . For thiThe basic aggregate used to prepare the mix consisted of standard sand  and natural gravel. Commercially available standard sand (according to the European standard EN-196-1) with a maximum size of 2 mm was used. Choice of standard sand was dictated by the need for controlled grading of fine aggregate . The natural gravel of the fraction 2/4 mm was washed and dried to remove additional dust and ensure precise dosing of microfiller to the mix. Sand and gravel were used in a ratio of 1:2 (by mass).The addition of microfillers  in polymer concrete has been reported to enhance its mechanical properties and to improve the workability of the mix. Thanks to its spherical shape, fly ash grains may fill the empty voids between the larger grains of aggregate, reducing intermolecular friction and facilitating mixing.A lot of effort is made to utilize wastes and by-products in civil industry as a part of a strategy for sustainable development. Following that trend, the material cost of polymer concrete can be lowered by reducing the consumption of raw materials and replacing it with less expensive equivalents. Partial replacing of the microfiller fraction with calcium fly ash—a product of combustion in fluidized bed boilers—can be an example of recycled waste products which, due to their properties, have not found a wide application. For this reason, the microfiller fraction consists of quartz powder and waste mineral powder. Quartz powder was prepared by grinding pure quartz sand . Fly ash applied in this polymer concrete mix was the by-product of the energy industry—the waste material of hard coal combustion from a cogeneration plant in Warsaw. Analysis of the microfillers’  size distributions was carried out at Warsaw University of Technology and the results can be found in . The sizA/B [g/g]—aggregate to binder ratio by mass;B/M [g/g]—microfiller to binder ratio by mass;P/M [g/g]—waste powder to microfiller mass ratio.The polymer concrete mix used in this research was designed according to a mathematical model. The model was elaborated during the project entitled “Polymer Concrete Composites”  and furtThe effect of silica microfiller replacement by calcium fly ash on selected polymer concrete mechanical properties , as well as binder hardening characteristics, were investigated in previous research ,19. The The composition of vinyl ester concrete for manhole covers was selected using this previously developed mathematical model ,18. ConsMechanical properties are necessary to develop and calibrate a constitutive model of polymer concrete. For this reason, the next step was to test the material in compression, tension, flexure and fracture to obtain necessary parameters. Additionally, the homogeneity of different specimens was assessed.The flexural strength under one-point loading was done in accordance with EN 12390-5. Beams of 40 × 40 × 160 mm were cast and cured in water for 28 days. The flexural strength test was carried out using the Instron 5567 testing machine , as shown in The tensile strength of the polymer concrete was experimentally measured using the Instron 5567 testing machine. Three specimens from the batch were tested in order to get the split tensile strength. The samples were demolded after 24 h of casting and allowed to cure for 7 days. The force at failure was recorded see .Compressive strength test results are crucial in studying concrete, especially when considering FEM modeling for structural applications. The tests were undertaken in accordance with the technical requirements outlined in the EN 12390-3 standard using the hydraulic press Controls MCC8 . Standard cubes (d = 100 mm) and cylinders (d = 100 mm and h = 200 mm) were molded using the designed polymer concrete mix. Additionally, for comparative purposes, two halves of each specimen after the flexural test were used to conduct a compression test. The compressive strength test setup is shown in The modulus of elasticity of polymer concrete was determined by conducting the laboratory test on cylindrical specimens. The compressive load was applied to the specimens in the longitudinal direction and the deformation of the specimen with respect to different load values was analyzed. Three strain gauges were attached to the concrete cylinder to measure the axial deformation during the compression test as shown in F. Three samples of 100 × 100 × 100 mm with an initial notch 30 mm wide and 20 mm thick were used. The test was undertaken with a controlled speed of notch opening of vCOD = 0.1 mm/min. The obtained graphs of the vertical load versus the crack mouth opened deflection (CMOD) are shown in To fully reveal the material characteristics on fracture toughness, a wedge splitting test (WST) was conducted as shown in The mechanical properties of the PC are summarized in The concrete damaged plasticity (CDP) constitutive model implemented in Abaqus software  consists of the combination of non-associated multi-hardening plasticity and scalar (isotropic) damaged elasticity to describe the irreversible damage that occurs during the fracturing process . The yieIn order to fully define the CDP model, one has to provide many parameters defining the elastic response, the shape of the yield surface and the plastic potential, as well as tabular data describing the concrete behavior in uniaxial compression and tension. Herein, all these parameters were assumed based on laboratory test results, the literature or suggested default values in Abaqus.The Young’s modulus describing the material response in the elastic range was assumed to be equal to the mean Young’s modulus,K, which The parameters of the yield function and plastic potential are summarized in concrete ,24,25. TCompressive behavior of the material outside the elastic range was assumed according to the following relation between compressive stress train εc :(2)σcεc=Tension stiffening data were defined in terms of the cracking strain, The CDP model assumes that the reduction of the elastic modulus is given in terms of a scalar degradation variable  so that (4)E=1−dThe damage parameter was calculated both for compression and tension from the compression and tension behavior as the percentage drop of compressive or tensile strength, respectively. Additionally, care was taken to ensure that no negative plastic strain occurred according to Equation (5). The damage parameter input data are shown in Finally, a small viscosity parameter was introduced in the CDP material to improve the numerical stability of calculations see . To elimThe manhole cover was chosen as an example of using PC for the production of prefabricated elements . This tyThe concrete manhole cover geometry was adopted based on typical cast-iron covers commonly used in Europe. The diameter of the plate was assumed to be 640 mm and its thickness to be 32 mm. The model geometry and boundary conditions were related to a laboratory test setup shown in Axisymmetric and three-dimensional models were built. The axisymmetric model geometry is shown in For the axisymmetric case, the concrete plate was discretized with four-node bilinear, reduced integration finite elements with hourglass control, which led to a fully regular rectangular mesh. The different average global size of these elements was assumed for convergence study. The three-dimensional plate was discretized using eight-node linear, reduced integration brick elements. The finite element mesh of the 3D model is shown in Contact was modeled between steel elements  and the concrete cover with a penalty constraint enforcement method. The basic Coulomb friction model was used to describe the frictional behavior with a coefficient of friction equal to 0.4.The analysis was carried out in two steps. In the first step, gravity was applied, whereas in the second, the Static/Riks ,28 . In the paper, polymer concrete composition was described. The concrete material was tested in order to evaluate its applicability as a cheaper and more durable alternative for commonly used cast-iron covers. The laboratory test data was later used to find material parameters of the concrete damaged plasticity constitutive model. An FEM model of the concrete manhole cover was build according to the conditions of a laboratory test setup. The numerical model was used mainly to predict the carrying capacity of the concrete slab subjected to the loading generated by a steel piston of a hydraulic press moving vertically along the center of the concrete plate.The concrete damage plasticity (CDP) material model can be successfully adopted to simulate the nonlinear mechanical behavior of polymer concrete.The CDP model takes many parameters and finding these parameters based on standard laboratory test data is not straightforward. The authors showed a clear procedure of finding CDP model input data based on standard laboratory tests.The CDP model was originally developed for the description of cement concrete. For polymer concrete, the authors proposed how to make necessary assumptions regarding the post-failure behavior.The authors showed that PC can be considered for the design of manhole covers. In this study, manhole cover made of plain PC showed too little structural capacity. However, in the authors’ opinion, the numerical approach presented here can still be considered as a valuable design tool . The numerical solution can be used to choose the type and geometry of the reinforcement, which will be the subject of future studies. Evaluating the application of a certain material model and formulating necessarily steps for finding material parameters is an important milestone before proceeding to the reinforcement design, as it can significantly limit the number of laboratory tests.The main findings of this paper can be summarized in the following points:


The evolution of spoken languages has been studied since the mid-nineteenth century using traditional historical comparative methods and, more recently, computational phylogenetic methods. By contrast, evolutionary processes resulting in the diversity of contemporary sign languages (SLs) have received much less attention, and scholars have been largely unsuccessful in grouping SLs into monophyletic language families using traditional methods. To date, no published studies have attempted to use language data to infer relationships among SLs on a large scale. Here, we report the results of a phylogenetic analysis of 40 contemporary and 36 historical SL manual alphabets coded for morphological similarity. Our results support grouping SLs in the sample into six main European lineages, with three larger groups of Austrian, British and French origin, as well as three smaller groups centring around Russian, Spanish and Swedish. The British and Swedish lineages support current knowledge of relationships among SLs based on extra-linguistic historical sources. With respect to other lineages, our results diverge from current hypotheses by indicating (i) independent evolution of Austrian, French and Spanish from Spanish sources; (ii) an internal Danish subgroup within the Austrian lineage; and (iii) evolution of Russian from Austrian sources. Signing communities have likely existed throughout human history in communities with high incidences of deafness ) for Latin and the voiced labiodental fricative (IPA [v]) for Cyrillic. Thus, a decision must be made about whether to organize the comparison based on (i) form, by comparing handshapes representing Cyrillic 〈B〉 with handshapes for Latin 〈b〉; or instead, based on the (ii) sound represented, by comparing handshapes for Cyrillic 〈B〉 with those for Latin 〈v〉. In many such cross-alphabet comparisons, the documentary record is suggestive about how the comparisons should be organized. In the example just mentioned, we decided to compare handshapes representing Cyrillic 〈B〉 with Latin 〈b〉 and not 〈v〉, thus opting for variant (i), because historical records provide clues about how the Russian SL MA was adapted from other European MAs in the early nineteenth century ): Greek 〈γ〉. Starting at the top of the figure, Afghan SL represents the grapheme 〈〉 by extending the index and middle fingers, a form that is unique in this comparison. To represent the grapheme 〈g〉, historical Brazilian SL (Brazilian 1875) and French SL use forms with an extended index finger and the thumb orientated in a similar direction. Pakistan SL uses a similar handshape for the grapheme 〈〉. Finally, Greek SL, Russian SL and historical Russian SL (Russian 1835) represent 〈γ〉 and 〈Γ〉 with extended index finger and thumb extended outward.In In the upper right side of 2.3.et al. [The matrix includes characters supporting language cliques that are compatible (inherited patterns) and incompatible  with the splits in the unknown true tree. The true tree is, in this case, not necessarily a sequence of dichotomous splits because the tree can be polytomous and anastomizing: (i) one ancestor may have more than two direct descendants; and (ii) a descendant may have more than one direct ancestor in the case that, for example, an MA is the product of combining two (or more) different sources. Thus, any simple, dichotomizing tree that we infer or select using tree-reconstruction methods and commonly used optimality criteria will be incomprehensive, and any signal in the matrix reflecting aspects not covered by the tree’s selected or inferred topology will add to data incompatibility . Another source of tree-incompatible signal is the inclusion of putative ‘ancestors’ in the form of historical MAs, as well as their direct or distant ‘descendants’. Spencer et al.  showed tet al. ), which Support Consensus Networks [xy shares CogIDs with three different SL groups, the bootstrap replicate trees may reflect this situation by showing a three-way split support for each topological alternative (xy is placed within a different group in each pseudoreplicate tree) and an according three-dimensional box in the CNet. We used PAUP* [With respect to the complex signal in the underlying matrices, we thus relied exclusively on network-based EDA ,60 usingNetworks ,62, CNeted PAUP*  to compued PAUP*  for LS aed PAUP*   along time-filtered networks .Post-analysis character mapping was done by hand-and-eye following the logical framework of median networks and guidelines provided by Bandelt et al.  for thei3.The NNet in NJ = 37, but BSML,MP < 15), hence, its intermediate placement in the NNet .The robustness of discriminating signal in the underlying matrix for each main group, estimated using non-parametric BS support, is shown in the NNet  and (ii)The results of the EDA indicate that each major group goes back to an independent founding event: there is little to no support for the deepest splits; the centre of the overall NNet in Contemporary Icelandic SL is a direct derivate from the Danish subgroup within the Austrian-origin group; the same holds for Norwegian SL, which started to strongly deviate from the closely related Icelandic SL in the second half of the twentieth century. The Russian group can be linked historically to the Austrian-origin group  or modified the original and not the later Spanish form (e.g. in the handshape representing 〈q〉). Second, independent formation of the French MA is suggested by the clear separation of the French and Spanish groups in j〉, 〈k〉, 〈v〉 and 〈w〉. Thus, in adapting the early Spanish sources, the signing community in Paris changed them substantially, both consciously by innovating new forms and through usage in a community.Multiple sources report that the founder of deaf education in France, de l’Épée in Paris, had become aware of Bonet’s (1620)  century ,69, suggsynapomorphies in biology) would support such a conclusion, indicating a unified basis from which both MAs later diverged. Shared innovations would be, in this case, those forms that differed from Spanish sources but that were uniquely shared in French and Austrian MAs. In fact, we find relatively few such potentially derived forms between the earliest Austrian and French MAs, including those representing 〈d〉, 〈e〉, 〈l〉, 〈r〉 and 〈w〉. Forms for 〈f〉 and 〈v〉 were shared by Austrian 1786 and French 1800, but also by early unrelated SLs, such as Swedish 1866.The other main continental European lineage is the Austrian-origin lineage. Some scholars have claimed that Austrian and French SLs share a common origin . A largetrunk in the NNet of the earliest MAs in the sample ; other forms were dropped (e.g. the Austrian form representing 〈d〉); and some forms were used to represent Cyrillic letters that appear similar to Latin letters, but which occupy different positions in the alphabet (e.g. Cyrillic 〈〉). One consequence of this mismatch between alphabets is that there are fewer cross-alphabet comparanda between Latin- and Cyrillic-representing MAs. In addition, as discussed in §2, there are serious methodological challenges in deciding which forms should be compared, with the resulting possibility that some connections between sources and adaptations cannot be recovered. Thus, differences between Latin and Cyrillic alphabets may cause phylogenetic methods to overestimate the distance between the Austrian-origin and Russian groups. Conversely, because of iconicity, our approach in this comparison may, in general, underestimate distances between MAs representing the same type of alphabet. Many MA forms represent letters iconically, for example, by matching the shape of the letter with the shape of the hand. MAs representing typologically similar alphabets are more likely to converge on handshapes, evolving independently to similar forms. It is also possible that iconic MA forms evolve more slowly or resist changes in order to maintain the iconic link between the handshape and letter represented.While the results support classifying Russian as a separate lineage created using Austrian sources, any interpretation of the results with respect to Russian SL is complicated by substantial adaptation and restructuring of an existing MA to represent the Cyrillic alphabet. Similarities between Russian SL and early Austrian MAs are reflected in the NNet of early MAs in et al. [The British-origin group forms an independent lineage. The NNet in et al.  for Croaet al.  for Czecc〉, 〈f〉, 〈k〉, 〈l〉, 〈m〉, 〈n〉, 〈o〉, 〈u〉 and 〈v〉. Thus, while the results support the conclusion that the new Swedish MA was created mainly in isolation from other lineages, Borg may have borrowed a limited number of handshapes known widely in Europe. That he may not have had a preference for handshapes from any existing MA is indicated by the general lack of branch support for an alternative that would place the Swedish lineage as sister to any other group. The only somewhat similar MA, according to the results, is Albanian SL , which also lacks any clear affinity to any of the major groups.Finally, the Swedish group, which consists of only historical and contemporary Swedish SL, as well as Portuguese SL, form a separate lineage. The edge bundle separating the Swedish group from the centre of the graph in 5.Despite their relevance to our understanding of human linguistic diversity and to theories of language change, the evolutionary histories of the world’s SLs have not, until now, been studied using state-of-the-art methods. We have shown that computational phylogenetic methods can be applied to MA data to uncover new insights into the evolutionary histories of SLs, to generate new hypotheses about their relationships, and to better understand the evolutionary processes that have shaped the diversity of contemporary SLs. Our analysis supports some aspects of existing SL classifications, such as relationships among French SL and Dutch, Flemish and French-Belgian SLs, as well as SLs of the Americas, including American, Brazilian, Mexican and Quebec SLs. In addition, our results support previous analyses of the relationships of BANZSL languages, and use language data to confirm known historical institutional connections among Swedish and Portuguese SLs, as well as Danish, Icelandic and Norwegian SLs. At the same time, our results add complexity to the overall picture of SL relationships, in particular to our understanding of the evolution of Austrian, French and Spanish SLs from early sources. Our discussion of the independent establishment of SL lineages points to a characterization of similarities across lineages as primarily horizontal, and not due to descent from a common ancestor, while within-lineage diversification does appear to be characteristically vertical in many cases. Finally, our comparison has generated new hypotheses about relationships among Austrian, Danish, Polish and Russian SLs, as well as other SLs in those groups. We anticipate that future studies of lexical data may contradict our phylogeny based on MAs, in particular for SLs that adopted the International Sign MA, because this adoption did not likely affect a language’s lexicon to any great extent. Notwithstanding these limitations, we suggest that our analysis be taken in future research as the best available phylogenetic classification of these SLs.


P-d, P-CMOD, and P-CTOD curves) were all recorded. Bilinear softening laws of the PC and SG series were determined by inverse analysis. Furthermore, the cohesive toughness was predicted using an analytical fracture model. The cohesive toughness obtained by experimental study was consistent with that predicted by analytical method, proving the correctness of the tension softening law obtained from inverse analysis. In addition, both initial and unstable fracture toughness values of SG mortar were lower than those of PC mortar given the same compressive strength. Moreover, the initial fracture toughness of SG concrete was generally lower than that of PC concrete, whereas the unstable fracture toughness exhibited an opposite trend.This paper aimed to determine the softening laws and fracture toughness of slag-based geopolymer (SG) concrete and mortar (SGC and SGM) as compared to those of Portland cement (PC) concrete and mortar (PCC and PCM). Using three-point bending (TPB) tests, the load vs. mid-span displacement, crack mouth opening displacement, and crack tip opening displacement curves ( It can reuse the industrial by-product, i.e., ground granulated blast furnace slag (GGBFS), in an efficient way using alkali activation ,2,3. In solution ,5. The msolution ,2,3. Extsolution . HoweverAs has been widely known, concrete is a quasi-brittle material and the dimension of its fracture process zone (FPZ) is comparable to the size of structure component. Hence, referring to this large nonlinear FPZ, it is improper to predict the failure process of a concrete specimen using linear elastic fracture mechanics (LEFM) ,8. HilleK fracture criterion was proposed [K fracture parameters can be calculated using an analytical method by conducting three-point bending (TPB) tests [Fracture toughness is also a crucial parameter describing the fracture resistance ability of a material containing a crack. In general, concrete structures experience the following three stages during fracture process: under the external load, a crack first initiates and then propagates stably until an unstable fracture happens . For theproposed , which iess KIcc , which iB) tests . F) and the characteristic length of SG concrete and mortar and PC concrete and mortar with comparable compressive strength, and found that the GF of SG concrete was always higher than that of PC concrete given similar compressive strength, whereas the GF of the mortar system exhibited an opposite tendency. However, obviously, these fracture properties are very essential for predicting the mechanical performance of SG structure elements subjected to static and dynamic load, and for achieving safe applications of SG materials [K model. In addition, comparisons of tension softening curves and fracture toughness between PC concrete and mortar and their SG counterparts were discussed.By far, very limited understanding has been achieved on the fracture properties  of SG concrete and mortar. Ding et al.  comparedaterials ,18,19,20aterials  recommenThe GGBFS used was from Nanjing, China. 2 to Na2O) of sodium silicate solution were 59% (by mass) and 3.7, respectively; and the sodium hydroxide (NaOH) flakes had a purity of 99%. A Grade 42.5 PC whose chemical composition is listed in 3 and 2.75%, respectively. Furthermore, gravel particles from a local river with a maximum size of 10 mm were selected as coarse aggregate. The bulk specific density and the water absorption of the coarse aggregate were 2530 kg/m3 and 1.83%, respectively.The liquid alkali activator consisted of sodium silicate solution and sodium hydroxide. The water content and the modulus (the mole ratio of SiOn) and the modulus of the alkali activator (sM). All the concrete specimens had a constant sand ratio (SR) of 0.4, which was equal to the amount of fine aggregate per unit volume to that of the sum of fine aggregate and coarse aggregate.Three compressive strength grades varying from 30 to 70 MPa were selected for both the PC and SG series. The mixtures of the PC and SG series listed in Both the SG and PC specimens were demolded 24 h after casting. All the specimens were cured in a curing chamber with a constant temperature of 21 ± 1 °C and a related humidity of 90% ± 5% for 28 days until testing. Three types of specimens were prepared for PC and SG concrete and mortar to conduct compressive tests, splitting tensile tests, and TPB tests, respectively. For compressive tests and splitting tensile tests, the mortar specimens had dimensions of 70.7 × 70.7 × 70.7 mm, while concrete specimens had dimensions of 150 × 150 × 150 mm. The dimensions of the mortar and concrete specimens were 100 × 100 × 515 mm when the TPB tests were conducted.ft was calculated using the following equation:P is the ultimate load (N) and A is the area of cross section (mm2).A 2000 kN capacity universal testing machine was adopted to obtain the compressive and splitting tensile strengths of specimens. The loading rates operated were 0.5–1.0 MPa/s for the compressive tests and 0.05–0.10 MPa/s for the splitting tensile tests, respectively, according to the different compressive strength grades . The spld) of the beam. Furthermore, another two HPDTs were settled at both supports to eliminate their settlement influence on the mid-span displacement. A 200 kN capacity hydraulic jack was adopted to conduct the TPB tests. The machine was operated at a loading rate of 0.02 mm/min [P-d), P-CMOD, and P-CTOD curves.The beams used for the TPB tests had a span/depth ratio of 4.0. All the specimens were pre-cut in the middle of the bottom side using a wet diamond saw, and the notch was 40 mm height and 3 mm wide see . A total2 mm/min  in orderP-d) and P-CMOD curves of the PC and SG concrete beams in each group with different compressive strengths. The ultimate load Pu, the initial cracking load Pini, the Pu, the modulus of elasticity E calculated from the P-CMOD curves [F calculated from the P-d curves [Pini was determined using a graphical method in this study, referring to the load value where non-linearity started on the P-d curves [D curves , and thed curves  are summd curves . It can Pu of concrete and mortar beams increased with increasing compressive strength for both the SG and PC series as expected. The improvement of the average ultimate load Pu with the compressive strength increasing from C30 to C70 was more significant of the PCC beams than that of the SGC specimens. In the former case, Pu increased from 2.39 kN to 3.56 kN with a 49.6% increase, whereas only a 14.7% increase was observed in the latter case. Comparing the ultimate loads Pu between the PCC beams and the SGC beams, it is seen that, in the case of the C30 strength grade, the average ultimate load Pu of the PCC beams was 20.4% lower than its SGC counterpart. Nevertheless, with increasing compressive strength, the ultimate load Pu of the SGC beams became close to that of the PCC beams. It is known that the interfacial transition zones (ITZs) between the aggregates and the matrix are generally the weakest parts in low strength concrete. As a result, cracks prefer to occur in the ITZs and thus a stronger ITZ could lead to a higher ultimate load. The microscopic observations conducted by previous researchers [Pu of the PCM beams were always slightly higher than those of the SGM beams given the similar compressive strength grade. This could be explained by the high shrinkage of SGM [earchers ,25 reveae of SGM ,27,28, wThe tension softening law is a basic component of the fictitious crack model (FCM) . It is aFor practical applications, a bilinear strain-softening diagram is adopted by several researchers ,30,32,33ft, the kink points  can be written as Equation (10) [x, which can be calculated by Equation (12) when the cohesive force is linearly distributed along the fictitious fracture zone:cCTOD can be measured directly by using the clip gauge holder. The detailed values are listed in In general, the cohesive toughness predicted by analytical method ion (10) . At the After the cohesive force 1/2 to 0.538 MPa·m1/2  and 1.238 MPa·m1/2 to 1.960 MPa·m1/2 , respectively, with the increase of compressive strength from 30 MPa to 70 MPa. In the case of SGC, the increases of 1/2 to 0.432 MPa·m1/2  and 1.586 MPa·m1/2 to 1.793 MPa·m1/2 , respectively . The aggravation of the discrepancy of the initial and unstable fracture toughness values between SGM and PCM with the increase of strength is attributed to the utilization of a higher alkali concentration activator of SGM that generated more serious shrinkage cracks [It is clearly shown in  PCM did ,25. Becae cracks ,28, leadCohesive fracture toughness K fracture model to SG concrete and mortar.K fracture model. Then, the cohesive fracture toughness of the PC and SG concrete and mortar was calculated by analytical method and experimental method, respectively. According to the results of mechanical tests and theoretical analyses, the following conclusions can be obtained.For both the PC and SG series, the values of The first descending slopes of the normalized bilinear softening curves of PCC and SGC are generally the same, whereas PCM has a gentler first descending branch than its SGM counterpart.The The The variation of This paper determined the softening laws and fracture toughness of the PC and SG concrete and mortar by conducting TPB tests, which has been rarely studied in previous research. The softening laws obtained by inverse analysis provided critical input parameters for numerical analysis. The initial and unstable fracture toughness values of the PC and SG series were calculated referring to the double-


Similarly, a higher early-age strength and a lower later-age strength was observed for the concrete in the presence of corrosive calcium chloride. The results from this research are expected to inform future studies on the long-term performance of RC structures under accelerated ASR and corrosion.This study focuses on two separate investigations of the main aging mechanisms: alkali–silica reactivity (ASR) and the corrosion of reinforcing steel (rebar) concrete, both of which may result in a premature failure to meet the serviceability or strength requirements of a concrete structure. However, these processes occur very slowly, spanning decades. The impact of direct chemical additives to fresh concrete to accelerate ASR and the corrosion of reinforcing steel on the fresh and hardened properties of the ensuing material are investigated to inform the potential use of chemicals in large-scale studies. The deterioration of reinforced concrete (RC) is determined by means of expansion, cracking, bulk diffusivity and surface resistivity measurements, and compressive, split tensile and flexural strength tests. The results indicate that the addition of sodium hydroxide and calcium chloride can effectively accelerate the crack formation and propagation in concrete due to ASR and the corrosion of rebar, respectively. The ASR-induced cracks maintained a constant crack width from 0.05 mm to 0.1 mm over the measurement period regardless of the intensity of aging acceleration. Adding 4% chloride by weight of cement for accelerating rebar corrosion resulted in an average crack that was 82% larger than in the case of ASR accelerated with the addition of sodium hydroxide. The addition of alkali resulted in an increase in early-age (7-day) strength. At a total alkali loading of 2.98 kg/m Aging in reinforced concrete (RC) structures occurs due to a combination of physical ,2,3, the−) of the alkalis (sodium and potassium) from hydraulic cement or other sources with the silanol groups (Si-O), and the breaking of the siloxane bonds of the silicon atom from the lattice [ASR is a pathogenic reaction in cement composites and is known as a major degradation mechanism in concrete structures . Pesaven lattice , forming lattice . The swe lattice . The swe lattice . To stud lattice  ; and lattice ,27,28,29Sanchez et al.  studied Another very important aging mechanism that may impact the performance of RC structures is the corrosion of rebar. The initiation of corrosion needs an anode for oxidation reactions, a cathode for the reduction of oxygen, an electrical connector to carry the electron charge and an electrolyte to carry the ionic charge . When a −/OH− ratio compared to calcium chloride (CaCl2) addition. This has been verified by other investigations with a conclusion that the corrosive effect of NaCl is less than that of CaCl2 [Three methods or their combinations have commonly been adopted in literature to accelerate corrosion in RC: creating a corrosion cell and driving the corrosion by passing an electric current through rebar, submersion of specimens in chloride solutions with wet–dry cycles and the addition of chloride directly into the concrete in its fresh state. To create the corrosion cell, a wet sponge ,36,37 orof CaCl2 ,40. HoweOtieno et al.  performeBoth ASR and corrosion in RC structures manifests itself in the form of cracks, which have an adverse effect on the mechanical performance of the structure. Existing studies focused on mixture designs, sample size and curing and exposure conditions, among others, to understand the influence of these parameters on the ASR or corrosion rate. A major contribution of our study is in the understanding of the only practical accelerated aging method for large-scale studies  on the properties of the ensuing concrete. This has been lacking in existing studies. Additionally, the influence of the batch size was also studied because it is important for large-scale studies. The results presented in this paper add to the existing datasets to improve the understanding of not only the ASR and corrosion degradation of concrete structures but also how accelerated aging studies can be conducted with minimal influence on the concrete properties to represent the field conditions.3 to 5.57 kg/m3), for accelerating ASR and calcium chloride (from 1% to 4% by weight of cement) for accelerating corrosion, on the material properties of concrete were investigated. The measurements were performed on three series of specimens with different batching volumes . Expansion, cracking, bulk diffusivity, surface resistivity and compressive, split tensile and flexural strength tests were carried out to assess the efficiency of these two accelerated aging methods. The objective of this study is to expand the knowledge base regarding the acceleration of ASR and corrosion by the direct addition of alkaline and salt, respectively, into the fresh concrete as a practical method for the long-term performance evaluation of RC structures.The solution immersion method used in the literature consists of conditioning, fluid ingress and salt ion diffusion ,48,49,502, with respective purities of 96% and 85%, were used as alkali and chloride resources to accelerate ASR and rebar corrosion, respectively. Analytical grade calcium hydroxide (Ca(OH)2) and NaCl with a purity of 99% were employed to make saturated lime water and a chloride solution for the bulk diffusivity test.Both Type I/II and Type II cement were used in the concretes prepared for this study. Additionally, to suppress ASR in the specimens intended for accelerated corrosion study, Class F fly ash was used. The chemical compositions of cement and fly ash for these mixtures are given in 3, 3.84 kg/m3 and 5.57 kg/m3, which was calculated according tofc is the fraction of cement in the concrete, Na2Oe is the alkali content of the cement and Aa is the added alkali. Two concrete mixtures were made with Type II cement and El Paso reactive sand, from which the total alkalinity of one of the mixtures (NaOH-12) was increased to 5.3 kg/m3 using NaOH to accelerate ASR. The other concrete mixture (NaOH-00) did not contain additional alkali and its only source of alkali was the alkali content of Type II cement, as presented in 2 flakes) by weight of cement to the fresh SCC mixture (with fly ash). CaCl2 was preferred over other salts because it induces higher corrosion rates, as discussed in The proportions of the ten concrete mixtures prepared in this study are provided in 3 from Type II cement (0% NaOH addition by weight of cement), 2.1 kg/m3 from Type I/II cement (0% NaOH addition by weight of cement), 2.98 kg/m3 (0.2% NaOH addition by weight of cement), 3.84 kg/m3 (0.4% NaOH addition by weight of cement), 5.57 kg/m3 (0.8% NaOH addition by weight of cement) and 5.3 kg/m3 (1.25% NaOH addition by weight of cement) are referred to as NaOH-00, NaOH-0, NaOH-2, NaOH-4, NaOH-8 and NaOH-12, respectively, in the remainder of this paper. Similarly, mixtures containing 0%, 1%, 2% and 4% chloride ion by weight of cement are referred to as SCC, CaCl2-1, CaCl2-2 and CaCl2-4, respectively. Specimens were prepared in 13 separate casts. In addition to the eight casts for the eight mixtures from Type I/II cement and Brazos River sand shown in 2-4 mixtures were repeated using a larger batch size to study the effect of mixing volume on the material properties. The batching volume for the larger series  was 2000 L, while the same for the smaller series was 100 L. The remaining two casts (one from each of the NaOH-00 and NaOH-12 mixtures) were made using Type II cement and the proportions shown in The concretes with a total alkali loading of 1.7 kg/mThe eight mixtures from Type I/II cement and Brazos River reactive sand had water-to-binder and fine-to-coarse aggregate ratios of 0.5 and 0.89, respectively. One type of coarse aggregate, pea gravel, with a nominal size of 19 mm, was used in these mixtures. A water-reducing admixture (Pozzolith 200N) and a high range water-reducing superplasticizer (Glenium 7500N) were used. The two mixtures from Type II cement and El Paso reactive sand had water-to-binder and fine-to-coarse aggregate ratios of 0.53 and 0.58, respectively. Two types of coarse aggregates, pea gravel and crushed rock, with nominal sizes of 9.5 mm and 19 mm, were used in these two mixtures. A water-reducing admixture (Pozzolith 8) and a high range water-reducing superplasticizer (Glenium 3400 NV) were used.From the mixtures with Type I/II cement and Brazos sand, sixteen 75 × 150 mm cylinders were cast for the smaller batch for crack, density and absorption measurements. In total, four hundred and forty-two 100 × 200 mm cylinders for compression and split tension tests were cast. Four 100 × 200 mm cylinders were cast from the smaller batch for chloride diffusion tests. Forty-five 100 × 200 mm cylinders, with 13 cylinders from the smaller batch and 32 from the larger batch, were cast for surface resistance and corrosion potential tests. As shown in The testing plan and standards for specimens from concretes with Type I/II cement and Brazos River reactive sand in larger mixing volume size  and smaller mixing volume size  are summarized in Density, void and absorption were measured at 28 days following ASTM C642 , which iAn image processing method, as shown in The surface resistivity test was performed on 100 × 200 mm concrete cylinders according to AASHTO TP 95-14 . The spe3 of water) for 28 days, 180 days and 365 days. The specimens were then ground in layers and a small amount of concrete powder was collected from different depths. The amount of chloride in these concrete powder specimens was measured using titration according to NT-Build 208 [−) was calculated according toV1 is the added amount of silver nitrate solution (mL), N1 is the normality of the silver nitrate solution, V2 is the amount of ammonium thiocyanate solution added during the titration (mL), N2 is the normality of the ammonium thiocyanate solution and m is the weight of the specimen (g).A bulk diffusivity test for ASR specimens was performed based on NT-Build 443 . After 2uild 208 . The amoC is the chloride concentration as a percentage of grams of chloride per gram of concrete (wt.%), Cs is the surface chloride concentration (wt.%), Ci is the initial chloride concentration measured in the concrete (wt.%), x is the depth below the exposed surface (m), De is the effective chloride transport coefficient (m2/s), t is the exposure time (s) and erf is the error function.To calculate the effective chloride transport coefficient, a general form of Fick’s second law with the assumption of constant external chloride concentration was used2-X cylindrical specimens (where X represents the different percentages of CaCl2 addition) with an embedded #10 rebar according to ASTM C876 [2+ + 2e−, corresponding to the potential of the saturated copper/copper sulfate reference electrode (CSE), with the reference to the hydrogen electrode being −0.30 V at 22.2 °C. The copper/copper sulfate reference electrode has a temperature coefficient approximately 0.0005 V more negative per Fahrenheit degree for the temperature range from 0 °C to 49 °C [In order to determine the corrosion activity of the embedded steel rebar, open circuit corrosion potential measurements were performed monthly from 28 days on the SCC and CaClSTM C876 . In RC, STM C876 . The prito 49 °C . In the to 49 °C , the proST, of the specimen was calculated according to:P is the maximum load indicated by the testing machine, l is length and D is diameter the specimen.The compressive strength and split tensile strength tests were carried out on cylindrical specimens of 100 × 200 mm according to ASTM C39  and C496R, of the prism was calculated according to:P is the maximum applied load indicated by the testing machine, L is the span length, b is the average width of the specimen and d is the average depth of the specimen.The flexural strength tests were carried out on prism specimens of 150 × 150 × 525 mm dimensions according to ASTM C78 . There wExpansion measurements were performed on 150 × 150 × 525 mm prisms made from NaOH-00 and NaOH-12 mixtures. Prisms were reinforced with longitudinal reinforcement ratios of 0% with no rebar and 1.23%, 2.18% and 3.41% using different sizes of rebars having 9.525 mm, 12.7 mm and 15.875 mm diameter, respectively, close to the four corners of the section, as shown in 3 and 3.84 kg/m3, the absorption decreased by 3% and 9%, and the voids decreased by 5% and 9%, respectively. Meanwhile, the alkali loading of 5.57 kg/m3 resulted in similar results to the control specimens. The decrease in the absorption and voids in NaOH-2 and NaOH-4 is attributed to the modification of cement hydration and the corresponding hydration products. As the amount of alkali increased, a less dense microstructure is obtained due to the formation of a more reticular and porous micro-texture. The chloride addition resulted in a negligible variation in the density of concrete of about 4.9%.The results of the measurements at 28 days are shown in 3. A comparison of the cracks on the specimens with two different sizes indicated that the geometry plays an important role in the amount of cracking, and smaller specimens showed more cracks on the surface. These results highlight the important effect of specimen geometry on the accelerated aging testing. The crack widths were measured, and it was observed that they remained almost constant (from 0.05 mm to 0.1 mm) during the testing period.In the specimens with accelerated ASR, the expansion of the ASR gel around the aggregate resulted in micro-cracks which, over time, propagated and appeared on the surface of the specimens. For the larger batch series of NaOH-8 specimens, the first map cracks were observed after approximately 90 days. Over the course of time, the density of cracks increased and the cracks started to coalesce. −3 was observed and this value kept increasing over time and reached to 33.5 ×10−3 at 432 days. The larger specimen showed a reduced crack density. At the same testing times (117 days and 432 days), the average crack density of the 100 × 200 mm cylinders was 73% and 70% less than that of the small specimens.Size effect was observed in the results, which means that the crack density is a function of the specimen size. Both samples were of the same concrete mixture and were maintained in the same environmental conditions. In the smaller cylinders, the cracks were fully joined together, and further expansion did not create additional cracks, unlike the larger cylinders. As shown in 2-4 concrete of the larger batch series with an embedded soft Metric #10 rebar are shown in −3. However, the crack density experienced a rapid increase after 276 days and this value at 592 days increased to 15.1 × 10−3. The total pixel density was not calculated; however, as shown in Results from the visual inspection of cylindrical specimens made of CaCl3 (0.8% NaOH addition). This difference is attributed to the presence of NaOH but more importantly to the reduced diffusivity of the SCC mixture due to the presence of fly ash [The bulk diffusivity test was performed on the larger batch series of SCC and NaOH-8 mixtures only. The results of these tests are shown in  fly ash ,67,68. A fly ash . These d2-4 and SCC mixtures is shown in The development of open circuit corrosion potential as a function of time for the larger batch series of CaClA comparison of the larger batch series of NaOH-8 and SCC mixtures in 2-2 were not consistent with the rest of the data, which might have been caused by random concentrations of the chloride ion close to the surface. Therefore, this group is not presented here. It is seen that, without the addition of chloride salt, the chloride penetrability of SCC for the smaller batch of specimens was high in the first 50 days, moderate between 50 and 100 days, and then became low. However, by mixing 4% chloride ion by weight of cement, the chloride penetrability was high in the first 100 days and then became moderate. The surface resistivity results indicate that, after 180 days, the chloride penetrability of SCC, CaCl2-1 and CaCl2-4 was in the range of low, low and moderate, respectively.Chloride content is normally considered as one of the parameters that affects the surface resistivity. The presence of chloride in concrete decreases the surface resistivity because the electrons are carried through the negatively charged ions in the concrete pore solution in saturated conditions . The res3 total alkali content and conditioned outside was about three times the average expansion of 0.22% of the prisms built from NaOH-00. High temperature and RH caused the expansions of the prisms in the environmental chamber to be higher than those in the lab or outside, with one exception. The exception occurred for the 0.49% final expansion of the plain concrete prism from the NaOH-12 mixture in the environmental chamber compared with the 0.62% expansion of similar prisms conditioned outside. This higher expansion of the prisms conditioned outside is attributed to the wet and dry cycles. The prisms from the NaOH-12 mixture conditioned in the environmental chamber showed a 0.49% final expansion while the other prisms in the chamber built from the NaOH-00 mixture showed a 0.34% expansion. The 0.34% expansion of the plain concrete prism from NaOH-00 shows that in an environment with high temperature and RH, even concretes with a low alkali content may experience a high level of ASR in the presence of reactive aggregates.The results of the longitudinal expansion measurements on the prisms from NaOH-00 and NaOH-12 are presented in this section. Each data point is the average of two measurements taken from one prism. 2 coefficient of the regression was found to vary between 0.8 and 0.9 for different datasets. The final expansions of prisms obtained from the regression at 575 days of age are summarized in Logarithmic regression analysis was performed on the expansion data points shown in 2 at later ages. Note that the slight drop in strength for the CaCl2-4 series at 210 days and then the increase at 365 days is attributed to the variation in the material properties. The strength due to tricalcium silicate  and dicalcium silicate (belite) increased, but the strength due to tricalcium aluminate decreased with the addition of calcium chloride [2 was higher than the other mixtures. The overall strength of CaCl2-4 was the lowest among all mixtures. The reduction in the final strength might be attributed to the formation of chloroaluminate hydrates  of cement), which is responsible for the concrete softening [The effect of chloride ion on the compressive strength of the specimens from the larger batch series is shown in chloride . Additiochloride . The samoftening ,78.3) total alkali content, these cylinders were kept in an environment that accelerates ASR. The cylinders from this group showed about a 40% decrease in tensile strength at 550 days of age compared to that at 28 days. The cylinders from the NaOH-00 mixture kept in the laboratory showed a higher tensile strength at all ages compared to the other cylinders. At 28 days and 550 days of age, the cylinders from the NaOH-00 mixture in the lab had 13% and 25% higher tensile strength, respectively, compared to the cylinders from the NaOH-12 mixture in the environmental chamber. The cylinders from the NaOH-00 mixture kept in the laboratory showed a 30% reduction in the tensile strength at 550 days compared to the same at 28 days of age. It is concluded that ASR affected the tensile strength of the cylinders with reactive aggregates and normal doses of alkali provided by typical cements in the absence of supplementary cementitious materials such as fly ash.The retarding effect of alkali on the strength development of concrete was also observed in the splitting tensile tests. For the specimens from the larger batch series, as shown in (1)Using reactive fine aggregate, no fly ash and adding alkalis in the form of NaOH directly into the fresh concrete paste was found to be an effective method to accelerate ASR of specimens kept in ambient outdoor conditions. The increase in total alkali loading resulted in a decrease in the compressive and splitting tensile strength of concrete at 28 days but an increase in strength after 180 days. When the error bars are considered, the general trend of decreasing strength with increasing NaOH addition is observed, suggesting accelerated ASR in the presence of alkali.(2)3 were observed at around 90 days and the crack intensity increased over time during the 432-day measurement period. While the crack intensity on the surface increased and the cracks coalesced, the crack widths remained between 0.05 mm and 0.1 mm throughout the measurement period of 432 days.The first ASR cracks on specimens with a total alkali loading of 5.57 kg/m(3)The addition of chloride accelerated the rebar corrosion, evidenced by the reduced open circuit corrosion potential measurements and crack maps. Cracks due to corrosion in specimens with 4% chloride by weight of cement were first observed approximately 90 days after casting. Differently from the cracks generated by ASR, both the crack length and width increased with time.(4)The effect of 4% chloride addition on the physical and mechanical properties of concrete was observed to be more severe than that of 1% and 2% chloride, indicating that the corrosion of the embedded steel rebar with a high probability occurred at a chloride level of 4%.(5)The bulk diffusivity results show that the chloride diffusivity of concrete with fly ash and no NaOH addition was lower than that of the mix without fly ash and a 0.8% NaOH addition. This indicates the role of sodium hydroxide in increasing the porosity of the ensuing concrete in addition to the increased diffusivity created from the interconnectedness of micro-cracks due to ASR gel expansion.(6)In comparison with SCC, a lower surface resistivity was observed for the NaOH-8 mixture and its difference from the SCC grew over time. The addition of chloride resulted in a decreased surface resistivity and the chloride permeability of concrete increased with increasing chloride addition.(7)3 total alkali content was 0.62% during the 575 days in the outside environment, while this value for the same concrete with a 3.41% reinforcement ratio was 0.28%.The concrete reinforcement ratio was shown to reduce the ASR expansion. Increasing the longitudinal reinforcement ratio of concrete from 0% to 3.41% reduced the ASR-induced expansion by 29% to 56% in different environments. The ASR expansion of plain concrete prisms from the mixture with a 5.3 kg/mThis study reports on the results of two separate accelerated aging methods achieved through direct additions of sodium hydroxide and calcium chloride for ASR and rebar corrosion, respectively, and their impact on the properties of concrete. The following conclusions were drawn from the findings of this research:In summary, this study not only addresses an existing research gap on the influence of the addition of chemicals for accelerated aging in concrete on the ensuing concrete properties, but it also covers a range of variables that influence ASR and reinforcement corrosion. The dosage of the chemicals for accelerated aging, concrete ingredients, batch size, sample size, reinforcement ratio and curing conditions were among the variables that were studied. The degradation of the physical and mechanical properties of concrete due to aging were assessed over a wide range of variables and time. The generated datasets helped create a more complete picture of the range of effects from ASR and corrosion. Additionally, the ASR expansion saturation over time towards different limits based on the reinforcement ratio were defined as an estimate of potential effects in RC structures with varying reinforcement detailing. It is noted that the results of this research are influenced by experimental uncertainty. The application of these results to any engineering design/verification can be affected by this uncertainty, in addition to other aleatory and epistemic uncertainties.


Antibiotic resistance (ABR) is a major threat to public health, and the majority of antibiotics are prescribed in the outpatient setting, especially in primary care. Monitoring antibiotic consumption is one key measure in containing ABR, but Swiss national surveillance data are limited. We conducted a retrospective cross-sectional study to characterise the patterns of antibiotic prescriptions, assess the time trends, and identify the factors associated with antibiotic prescribing in Swiss primary care. Using electronic medical records data, we analysed 206,599 antibiotic prescriptions from 112,378 patients. Based on 27,829 patient records, respiratory (52.1%), urinary (27.9%), and skin (4.8%) infections were the commonest clinical indications for antibiotic prescribing. The most frequently prescribed antibiotics were broad-spectrum penicillins (BSP) (36.5%), fluoroquinolones (16.4%), and macrolides/lincosamides (13.8%). Based on the WHO AWaRe classification, antibiotics were 57.9% Core-Access and 41.7% Watch, 69% of which were fluoroquinolones and macrolides. Between 2008 and 2020, fluoroquinolones and macrolides/lincosamides prescriptions significantly declined by 53% and 51%; BSP prescriptions significantly increased by 54%. Increasing patients’ age, volume, and employment level were significantly associated with antibiotic prescribing. Our results may inform future antibiotic stewardship interventions to improve antibiotic prescribing. Antibiotic resistance (ABR) and its consequences have escalated into a serious threat to public health globally ,2. A keyOne of the top five priorities of the European Center for Disease Prevention and Control (ECDC) and the WHO global action plan to optimise the use of antimicrobials includes gathering data on antibiotic resistance and consumption to improve surveillance as a central element in containing ABR ,10,11. SAntibiotic consumption in the outpatient care setting in Switzerland is lower than in many of the European countries collaborating in the project of the European Surveillance of Antibiotic Consumption (ESAC) by the ECDC ,16,17. IIn Switzerland, the Federal Office of Public Health (FOPH) and the Swiss Centre for Antibiotic Resistance (ANRESIS) collect antibiotic consumption data both from the inpatient and outpatient settings . The SwiPrimary research on the study of antibiotic consumption in Swiss primary care is also limited. A few observational studies have provided some insights into the prevalence, predictors or quality of antibiotic prescribing in Swiss primary care, but these focused on specific clinical indications or a specific type  of prescribers ,23,24,25We aimed to characterise the patterns of antibiotic prescriptions, assess the time trends of these patterns, and identify the factors associated with antibiotic prescribing in Swiss general practice using electronic medical records (EMR) fed by a network of GPs. The EMRs are part of a database project for research in family medicine currently running in German-speaking areas of Switzerland and has so far aggregated patient health routine data over 12 years .p < 0.001).We identified a total of 155,292 patients with antibiotic prescriptions . EligiblPrescribing data by the canton of practicing GPs were available for 96.0%  of the prescriptions. Of these, 99.8%  of the prescriptions were issued in the German-speaking areas, including cantons of different languages but where German is officially the dominant language. The other 0.2% (n = 323) of the prescriptions were issued in cantons where French is officially the dominant language.Broad-spectrum penicillins (BSP) were the most common class of antibiotics used, accounting for 36.5%  of the prescriptions among all classes . Amoxicip < 0.001) and almost tripled . At the same time, there was a constant decline in the rates of fluoroquinolone and macrolide/lincosamide. Prescriptions of such antibiotics significantly reduced by 53%  and 51%  respectively. Tetracyclines show a significant linear increase of 0.07 (p = 0.006) while cephalosporins, intestinal antiinfectives and narrow-spectrum penicillins showed a wide variation but no significant difference in the rates of prescribing  over the twelve years  (Distribution of antibiotic prescribing showed a significant variation in the number of prescriptions by month (< 0.001) a. There p = 0.008) in the number of antibiotic prescriptions per 1000 consultations. From 2013 to 2020, the rate significantly fell by 39%  prescriptions per 1000 consultations.Fluctuation of antibiotic prescribing by year showed that the year 2013 was the observed peak of antibiotic prescriptions b. From 2A subgroup of 27,829 (24.7%) patient records contained information by the International Classification of Primary Care 2 (ICPC-2) code system allowing the identification of fifteen clinical indications for which antibiotics were most prescribed. Based on ICPC-2 codes for both general  and infeThe index of inequality in the rate of prescriptions across 240 GPs with 26,595 prescriptions is presented in p < 0.001), i.e., as the number of consultations increased, the number of prescriptions also increased. Similarly, GPs employed at a level of <50% prescribed significantly fewer antibiotics  compared to GPs employed full-time. At the patient level, increasing patient age  and being female  were significantly associated with more antibiotic prescriptions. Sensitivity analysis showed, however, that after excluding the sample of patients with ICPC codes available for UTIs, gender was no longer associated with antibiotic prescribing . Thus, in our analysis, UTIs were a confounding variable for antibiotic prescribing in women.Regression analysis demonstrated a significant correlation between several factors and antibiotic prescribing in the multivariable analysis . At the To the best of our knowledge, our study is the first assessing both the patterns of antibiotic prescribing and its associated factors exclusively in Swiss primary care with a network of GPs as the source of health data. As such, our study contributes by adding data specific to the GP setting, which in national reports is not distinguished from outpatient care . Our stuRegardless of the clinical indication, women were more likely to receive antibiotics than men. The three most common clinical indications for antibiotics were, in descending order of frequency, RTIs, UTIs and skin infections. The most frequently prescribed antibiotics were amoxicillin plus BLI, ciprofloxacin and clarithromycin. We found a constant and significant increase in prescriptions of BSP and a significant and steady decline in quinolones prescriptions.Monitoring antibiotic consumption in both the in- and out-patient settings is of utmost importance as it provides the basis for the implementation and evaluation of antibiotic stewardship interventions. Antibiotic consumption, especially the inappropriate use of antibiotics, is associated with increased rates of ABR . In EuroOur findings on the most common antibiotic classes used in Swiss primary care are in line with both national and European surveillance programs ,27. BSP,The WHO recently introduced the AWaRe classification to emphasise the importance of the optimal use of antibiotics and their potential for ABR . It recoOur study shows a steady decline in the rate of antibiotic prescriptions per 1000 patients, which is consistent with the trends of antibiotic consumption reported by the Swiss national surveillance  and westOur study indicates that RTIs, UTIs, and skin infections are the most common indications for antibiotic prescribing in Swiss primary care. This finding is consistent with previous Swiss and international studies evaluating the consumption of antibiotics at the primary care level ,33,34,35Our findings by seasonal fluctuation are similar to those both from Swiss  and intep = 0.145).Research shows that a minority of physicians prescribe the majority of antibiotics in the outpatient care setting . Our resp = 0.505). These findings are in line with previous studies from Europe  to describe numerical data. We performed subgroup analyses of patient records with available ICPC-2 diagnosis  codes to identify the most common clinical indications for antibiotic prescribing. These analyses used data from two weeks before and two weeks after the first antibiotic prescription to make sure of a connection between the diagnoses and antibiotic prescriptions. We used the Lorenz curve  to analyp ≤ 0.2 in the univariable analysis. Using stepwise backward elimination, we developed the final multivariable model with the best fit for the outcome of interest. We performed sensitivity analyses to identify potential confounders of antibiotic prescribing using univariable analyses based on the number of prescriptions for the sample of patients with available ICPC codes. We also considered the type of dispensing license in a sensitivity analysis. We present the results as effect estimates with their corresponding 95% confidence intervals (CI) and intraclass correlation coefficient and report the summary statistics.We performed univariable and multivariable analyses to assess the association between patients’ and GPs’ characteristics and antibiotic prescribing. We included patients’ and GPs’ characteristics as predictors or fixed effects including age, gender, number of consultations per year, years in practice, employment level and status, and practice type. We performed linear random-effects mixed model regression analysis at the GP cluster-level. We corrected the model for GP consultations using a dichotomous variable (< or ≥6000 GP consultations per year). In the multivariable model analysis, we considered relevant effects together by constructing a model using variables with potential relevance for subgroup analyses, and which had a significance level of p < 0.05 statistically significant for all tests [We performed all analyses using the statistical software package R (version 3.6.1) and considered ll tests . For allll tests  since diIn Swiss (German-speaking) general practice, RTIs, UTIs and skin infections are the most common clinical indications prescribed with antibiotics. Amoxicillin plus BLI, ciprofloxacin and clarithromycin are the most commonly prescribed antibiotics. In keeping with national and European surveillance, we found a decline in prescriptions of fluoroquinolones, macrolides and lincosamides, however, at the expense of their potentially inappropriate use and increased use of BSP. Several patients and GPs’ characteristics were associated with antibiotic prescribing. Health policy initiatives engaged in antibiotic stewardship could use these findings to inform future interventions tailored to the factors associated with antibiotic prescribing.