Coating materials are considered one of the most antique materials of human civilization; they have been used for decoration and the protection of surfaces for millennia. Concrete structures—due to their permanent exposure to different types of environments and contaminants—require the use of coatings that contribute to its preservation by reducing the corrosion of its components (steel and aggregates). This article intends to introduce the principal causes of concrete deterioration and the coating materials used to protect concrete structures, including a summary of the coating types, their advantages and disadvantages, and the latest developments and applications. Furthermore, this paper also assesses brief information about the potential challenges in the production of eco-friendly coating materials. In the last few decades, reinforced concrete (RC) has become one of the most used construction materials. Its versatility and adaptability offer infinite applications in the construction sector ,2. The cConstruction, energy, mining, agriculture, and transport industries, are one of the primary sources of contaminants; according to Enshassi et al. and Zolfagharian et al. ,11, thesPrevious studies have focused on the durability, deterioration, and service life of concrete structures, including numerical models ,15,16 anRecently, different coating materials have been used to protect concrete structures in the construction industry. Among the most common ones, it is possible to find fire protection coatings used as a precautionary measure preventing buildings from collapsing during fire exposure  and wateIn the last few decades, research studies about the utilization of coating materials as protection for concrete elements exposed to different environments have increased due to the significant growth of this sector and the development of a large diversity of coating materials, varying not just raw ingredients but also the process of manufacture; among the most common techniques for the preparation of coating materials, it is possible to distinguish the solution casting method proposed by Sakamaki , the phaGenerally, coating materials are commonly used in concrete structures when they are exposed to contaminants. Zouboulis et al.  proposedo et al.  evaluateo et al.  studied This review paper aims to review the most relevant and recent investigations related to the use of coatings materials for the protection of concrete exposed to different types of contamination, also it reviews the deterioration of concrete exposed to a contaminated environment by summarizing the relevant manuscripts published in the last five years, until 2021. i. Search protocol: A set of rules and parameters for the search process was used together with logical and relational operators .This study’s research adopted the steps proposed by Ferenhof and Fernandez  for the Keywords: Concrete, corrosion, concrete protection, durability, concrete degradation, carbonation depth, alkali reaction, diagnosis, repair, steel corrosion, chemical attack, soil contamination, coating materials, organic coating, non-organic coatingDatabases: MDPI, SpringerLink, Elsevier—Science Direct, Scopus, Access Engineering, ASTM Year of publication: 2010–2021 for study casesii. Analysis: It refers to the consolidation and combination of data according to different criteria, such as most-cited authors, year of publication, and type of journal by creating a database with various articles that meet the search and consolidation criteria.iii. Data synthesis: It allows to generate conclusions and new knowledge based on the results presented by the different papers analyzed.A database was developed using an online tool containing basic information of the articles selected, such as author name, title, year of publication, journal of publication, organized by the main topic: coating materials, soil contamination, concrete degradation, and steel degradation.The database prepared in the analysis section was extracted to a spreadsheet and evaluated, resulting in selecting the papers to be used.Article selection: 210 articles were selected, 162 articles were read, and 76 articles are referenced in this paperiv. Writing: The information was extracted from 76 articles. The results were consolidated through scientific and academic writing.The principal purpose of this research paper is to contribute to the comprehensive state-of-the-art about the corrosion of concrete elements that are embedded in contaminated and noncontaminated soils, together with a brief overview of the current coating materials used in the construction sector. This paper summarizes all relevant data from different articles, such as types of laboratories, exposition time, sample size, etc., and determines the principal causes and consequences of contamination.From the analysis of the articles, it is possible to determine that the main cause of corrosion in elements exposed to contaminated soil is the contamination generated by human activities, construction, mining, agriculture, and others. On the other hand, it is possible to state that there is no evidence regarding the use of coating materials to protect concrete elements located below ground level, representing a wide area of research with high potential.During the last few decades, the continuous growth of the human population has contributed towards increasing different industrial activities, such as agriculture, energy, transport, construction, technology, and mining. These, in turn, increase soil pollution , the losHeavy metal contamination is one of the most severe types of contamination; uranium, arsenic, cadmium, tin, lead, manganese, vanadium, and mercury are the most abundant metallic pollutants introduced into soil through the use of fertilizers and pesticides in the agriculture industry. Human exposure to these metals can lead to several body dysfunctionalities and damage, including depression, osteoporosis, liver disease, and anemia . Coal-fimination . Finallymination .Concrete structures that are located below the level of the ground are exposed to different types of contamination. Some of them come from natural sources; however, most of them are related to human and industrial activity ,48. OtheOne of the most concerning topics about cement-based structures is their durability when exposed to different chemically aggressive scenarios causing its degradation; these scenarios can be classified into three groups: physical, biological, and chemical , which cOsuji et al.  analyzedIn the study conducted by Adewuyi et al. ,54, concYu et al.  exposed Carbonation is also known as a major cause of deterioration of concrete structures embedded in contaminated soil, this type of corrosion depends on different factors, such as bonation .A phenolphthalein indicator is commonly used to determine the carbonation depth, being sprayed onto the surface of a freshly cut sample. Chang et al.  shows thFoundation structures are exposed continuously to different aggressive agents, such as chlorides and sulfates during their service lifespans ,59. ChloBy the measurement of potential and velocity of corrosion, Baltazar-Zamora et al.  observedConcrete structures are exposed to constant environmental impacts that affect their physical and mechanical properties . In consZhong et al.  analyzedSimilar results were found in the research conducted by Tagnit-Hamou et al. , where bAnother example of the deterioration of concrete foundations is given by Yoshida et al. , where rOther types of sulfate attack in concrete foundations can be found in sewage water, which leads to the degradation of the elements due to sulfuric acid produced by the different microorganisms present in the contaminated water, reducing by this, mechanical properties of the concrete and the loss of adhesion of the cement matrix. Tulliani et al.  evidenceBased on previous research, it is evidenced that the presence of different minerals and contaminants produce chemical reactions that lead, in some cases, to severe corrosion and thus degradation of the elements embedded in contaminated soil, which results in the effects on their mechanical and physical properties.The rapid and continuous growth of different industries, the lack of control in the production of materials, food, and poor waste management, can eventually increase air and soil pollution, as evidenced in previous chapters, decreasing the service life of structures exposed continuously. Different materials have been implemented over the years to protect concrete elements by reducing corrosion at an early age. As Protective coatings are present in most of the surfaces around us, used from the simple protection of food to the complex protection of steel and concrete. Nevertheless, most of these coatings go through a manufacturing process that generates contamination. Some of them use nonrenewable materials, such as bitumen obtained from petroleum refining, causing several environmental problems. In addition, some of the coatings use organic solvents that emit volatile organic compounds, producing air pollution that affect human health. Therefore, it is necessary to continue developing eco-friendly coating materials that contribute to environmental preservation without sacrificing the main properties of the materials, e.g., high durability, toughness, adhesion, strength, etc. Coating materials must follow the specifications stated in the European Standards (Eurocode) regarding coating adhesion to the substrate, absorption, and permeability, among others. Approximately 54% of the articles reviewed applied Polish–European standards (PN-EN), 38% used the American Society for Testing and Materials (ASTM), and just 2% used local test methods approved by the ITB (Building Research Institute) in Poland. The most common procedures among the literature were adhesion, tensile stress, and resistance to freeze/thaw cycles tests. In addition, the article analyses focused on the reduction and control of the carbonation process and on the proposal of new coating materials for the protection of concrete exposed to contaminated environments.During the last decades, different raw materials have been used to produce new protective coatings materials intended to improve the concrete properties. Elnaggar et al.  presenteFrancke et al.  proposedImproving the protection of concrete structures is one of the most critical objectives in manufacturing new coating materials. Significant results have been evidenced by applying protective (As/PU) layers showing a reduction in the chloride penetration of about 75% with respect to the control sample. Even though the immersion of both coated and non-coated samples in sulfuric acid and NaCl solutions show a decrease in the compressive strength of the concrete samples, it can be evidenced that the coated samples present a reduction in the compressive strength between 22% and 27% and a decrease of 50% in the non-coated material. Finally, it can be concluded that the protection with asphaltic polyurethane (As/PU) coating improves the mechanical and physical properties gradually when the ratio is increased with respect to the samples without coating.According to Baba et al. , to miniThe authors mentioned above evaluated the benefits of coating materials in structures exposed to contamination. It was evidenced that coating materials effectively reduce the impact caused by different chemical attacks, and are able to extend the lifespan of concrete structures and reduce corrective maintenance costs.This literature review was prepared to give an overview of the causes of corrosion of concrete elements exposed to different types of contaminants and the procedures proposed and used by some researchers to protect these elements. Different coating materials have been proposed, varying from naturals sources, such as bituminous coatings, to synthetic productions, like acrylic coatings. Among the results, in all cases where concrete samples were subjected to contamination either by exposition to chemical or natural contaminants, the compressive and flexural strengths showed a significant reduction. In addition, galvanized and carbon steel bars embedded in concrete samples showed an increase in corrosion, potentially leading to a premature corrosion of the bars and premature cracking and deterioration of the concrete elements. Even though several investigations have been carried out on how different types of contamination affect concrete, there is not much evidence yet on how coating materials can protect concrete elements embedded in contaminated soils.This review paper was limited to Spanish and English articles found in the journals mentioned in


ALK and ROS1 fusion, MET fusion is relatively rare in NSCLC. In this case, we report the case of a female patient with NSCLC positive for a novel ARL1-MET fusion. The patient achieved about a 5-month progression-free survival (PFS) after receiving crizotinib for unresectable right lung malignancies. To the best of our knowledge, this case provides the first clinical evidence that the novel ARL1-MET fusion might be an actionable mutation in NSCLC.It is imperative to know the status of oncogenic drivers in patients with non-small cell lung cancer (NSCLC). Compared with  MET fusion is relatively rare compared with ALK and ROS1 fusion in NSCLC. To date, eight MET fusion partners have been reported for NSCLC: ATXN7L1, KIF5B, STARD3NL, SPECC1L, HLA-DRB1, UBE2H, SLC1A2, and PTPRZ1. MET fusion has been reported to be a therapeutic target in lung cancer  is a disease commonly caused by alterations in oncogenic drivers. g cancer .MET inhibitor and has been proven effective in preclinical and phase I clinical trials -competitive, small-molecule inhibitor of the receptor tyrosine kinases (RTKs) c-MET [also known as hepatocyte growth factor receptor (HGF)], ALK, and ROS1. When the drug was initially developed, it was mainly used as a small-molecule l trials . It can l trials .ADP-ribosylation factor, GTPase 1 (ARL1)-MET fusion, was detected in the right lung tumor tissues using next-generation sequencing (NGS). She obtained a 5-month progression-free survival (PFS) after receiving crizotinib for the unresectable right lung malignancies.Herein, we reported the case of a 60-year-old woman with NSCLC. This patient was found to have synchronous multiple primary lung cancer (SMPLC), which meant that the time since tumor discovery was less than 6 months. The patient underwent thoracoscopic wedge resection of the left upper lobe and dissection of the mediastinal lymph node. Histologically, postoperative pathology confirmed that the left lung tumor was adenocarcinoma, while the unresectable right lung tumors were confirmed to be adenosquamous carcinomas through bronchoscopic biopsy. A novel SPT24). The tumor in the right lung was confirmed to be stage IVA NSCLC with squamous and glandular differentiation with a favored diagnosis of adenosquamous carcinoma according to the WHO Classification of Tumors, 5th Edition (pT4N3M1a). To seek personalized treatment strategies, formalin-fixed paraffin-embedded (FFPE) sections of tumor tissues from the right lung of the patient were subjected to NGS using a 68-gene panel associated with the pathogenesis and targeted therapy of lung cancer  on March 6, 2019. The average sequencing depth is 1,887×. NGS revealed a novel ARL1-MET rearrangement (fusion) in the tumor tissue sample from the right lung. The breakpoints occurred within intron 1 of ARL1 and within exon 14 of MET. Therefore, the ARL1-MET fusion protein in the patient was supposed to retain the completed tyrosine kinase domain of MET, which conferred potential oncogenic activity  Co. Ltd., Beijing, China) on September 28, 2021. The average sequencing depth was 347.4×. The results of NGS analysis are shown in ARL1-MET fusion disappeared but ERBB2 insertion (NM_004448: exon 20: c.2313_2324dup: p.Y772_A775dup) appeared . Three weeks after treatment with crizotinib, cough and dyspnea were remarkably relieved. In June 2019, thoracic CT showed that the size of the nodule shadow in the right middle lobe was reduced to approximately 22 mm × 14 mm, and multiple lymph node shadows in the right pulmonary hilum and mediastinum were also greatly reduced. She achieved a partial response (PR) defined by RECIST1.1 Figure 3ARL1 exon 1 (NM_001177) to part of MET exon 14 (NM_000245) was detected in a patient with NSCLC and SMPLC using NGS.In this case, a previously undescribed fusion of ARL1 is located at 12q23.2, encoding a protein belonging to the ADP-ribosylation factor-like (ARL) family of proteins. ARL1 is the first identified member of the large ARL family, which serves as an important regulator of the Golgi complex structure and is involved in several cellular processes, such as the endosomal trans-Golgi network, secretory trafficking, and innate immunity -MET fusion is one of the few known MET fusions. It is a rearrangement that fuses the oligomerization domain of TPR with the completed tyrosine kinase domain of MET maintaining its oncogenicity  of the United States for the patients with metastatic NSCLC harboring MET exon 14 skipping mutations. Others are being evaluated in clinical trials.MET tyrosine kinase inhibitors (MET-TKIs) are generally divided into three types depending on their structure and modes of binding with MET. Types I and II are ATP-competitive inhibitors. Type I inhibitors are further subdivided into types Ia and Ib, depending on their interaction with the solvent front residue G1163. Type Ia inhibitors, such as crizotinib, interact with the solvent front residue G1163, whereas type Ib inhibitors, such as capmatinib, tepotinib, savolitinib, and APL-101, are independent of G1163 interaction. Type II MET-TKIs, such as cabozantinib, foretinib, merestinib, and glesatinib, are ATP competitors that bind to the inactive “DFG out” conformation of MET. Type III MET-TKIs, such as tivantinib, are non-ATP-competitive allosteric inhibitors , 15. AmoMET, like a point mutation at the tyrosine residue Y1230 of the MET tyrosine kinase domain and somatic M1268T mutation  appeared which activates the bypass signaling pathway. This might be a mechanism underlying resistance in the patient  associated with resistance to MET inhibitors.In conclusion, to the best of our knowledge, this study provides the first clinical evidence that the novel The original contributions presented in the study are included in the article/supplementary materials. Further inquiries can be directed to the corresponding author.The studies involving human participants were reviewed and approved by the ethics committee of Tianjin Medical University General Hospital. The patients/participants provided their written informed consent to participate in this study.Conceptualization: DZ. Attending physicians for the patient: LK. Writing—original draft: QM. Editing draft: DZ. All authors read and approved the final manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Recycling scrap tyres as alternative aggregates of concrete is an innovative option. To clarify the dynamic properties of the pretreated rubberized concrete with some cumulative damage, the natural frequency, flexural dynamic stiffness, and damping ratio of the specimens under incremental stress level were investigated in this paper. The results indicated that the pretreatment of rubber particles improved the strength, ductility, and crack resistance of the rubberized concrete. The reduction of the flexural dynamic stiffness was clarified with the increase of concrete stress level. The addition of the pretreated rubber particles enhanced the concrete energy dissipation capacity during the destruction, and the specimen dissipated more energy with the increase of rubber content before its failure. In recent years, the continuous development of new raw materials has enriched the materials in the field of construction ,2,3,4, aThe rubberized concrete (RUC) with the appropriate amount and size of rubber particles featured better durability , thermalIn recent years, researchers have paid more and more attention to concrete’s dynamic properties ,33. The According to the above studies, rubber particles replacing coarse aggregate increased the concrete damping capacity more notably, but the strength reduced significantly. The concrete with fine aggregate replaced with rubber particles was relatively better. Muñoz-Sánchez et al.  reportedNumerous mentioned papers have drawn important conclusions about the damping capacity of RUC through different methods, and promote the development of research on the dynamic capacity of concrete ,42,43. AThe reported publications mainly studied the properties of original rubberized concrete with undamaged specimens. The dynamic properties of concrete with some damage directly affect the anti-vibration capacity of the structures. It is necessary to study the dynamic properties of PRC during its destruction. In this test, specimens of uniform size were used, and the dynamic properties of the PRC, including natural frequency, flexural dynamic stiffness and damping ratio under incremental loading, were investigated using free vibration tests on them. The raw materials and the test methods were stated first, and then a brief research on the concrete slump and mechanical properties was made. Finally, the concrete dynamic properties were investigated.The cement used in this test was the 42.5 Ordinary Portland Cement produced by Tianrui Group Cement Co., Ltd., Zhengzhou, China. The chemical compositions and properties of the cement are listed in 3, and the ash content, fiber content and moisture content are 2.7%, 0.5%, and 0.6%, respectively. The distributions of the rubber and aggregate particle size are shown in The coarse and fine aggregates were natural crushed stone and river sand. Their properties are listed in The pretreated solution of rubber particles was sodium hydroxide solution with a mass concentration of 5%. The rubber particles were washed with water three times and dried, then soaked in the solution for 30 min. The mass ratio of rubber particles and the solution was 1/2, and each batch of the solution was used only once on the rubber particles. Finally, they were washed with water again, and dried.The concrete mixtures were based on China Standards JGJ 55- contents of the rubber particles were 0%, 5%, 10%, 15%, and 20%. The dynamic 2011 . The volA total of nine groups of specimens, including four groups of RUC, four groups of PRC, and a group of NC as reference specimens were prepared. Each group contained 17 concrete specimens, three for the test of dynamic elastic modulus and flexural strength, two for the test of dynamic properties, and three for each other test. The six specimens for the test of cube compressive strength and splitting tensile strength were of the size of 100 × 100 × 100 mm. Another six specimens for the test of axial compressive strength and static elastic modulus were of the size of 150 × 150 × 300 mm. Three specimens for the test of dynamic elastic modulus and flexural strength were in the size of 100 × 100 × 400 mm. The last two specimens for the test of dynamic properties were in the size of 100 × 100 × 1000 mm.The structural form of the cantilever beam is simple, and the pre-loading damage is easy to operate ,50. The rM, 0.6uM and 0.8uM) with 0–0.8 of the concrete stress level –(4), the stress level  Natural frequencyξ, E, I, and f are the damping ratio, dynamic elastic modulus, the moment of inertial, and natural frequency, L are the mass per unit length and calculated length of cantilever beams. Based on Equation (6), the theoretical natural frequency of the specimens was determined byThe acceleration-versus-time data were obtained through the free vibration test of a cantilever beam under incremental loading. The test natural frequency of the specimens was determined with the attenuated curves of acceleration. For the concrete specimens without damage, their natural frequency can be calculated by(2) Damping ratioξ bya1 and a21 were the initial peak and the 21st peak in the given time history.The acceleration amplitude from the first 20 oscillation cycles was used to calculate (3) Flexural dynamic stiffnessEI is no longer an invariant constant. Based on Equation (6), once the natural frequency was obtained, Equation (9) could be used to approximately predict the flexural dynamic stiffness under various conditions, and the dimensionless flexural dynamic stiffness was calculated by Equation (10).EI)0 and f0 were the flexural dynamic stiffness and natural frequency about cantilever beams of reference, and (EI)i and if were the values of cantilever beams under different conditions. For each test of natural frequency, damping ratio and flexural dynamic stiffness, the average value of the two specimens was reported as the test value.The properties of concrete change with the increase of rubber content and cumulative damage, and The concrete workability was measured by the slumps obtained by the standard test. The slumps of RUC and PRC with the same rubber content were similar, as listed in In this test, the concrete slumps first decreased and then increased slightly with the increase of rubber content. This is understandable since both the amount of sand and water are the important factors of fresh concrete slumps. When some sand was replaced by rubber particles, the flowability of concrete decreased as the result of the reduction of sand and coarse aggregate ratio. Note that when the sand was replaced with enough rubber particles, the actual moisture content of RUC was higher due to the lower water absorption of rubber particles (1–2 mm) than that of sand, which may have increased the slump of concrete slightly. Also, the gas carried by rubber particles during the concrete mixing process can also improve the workability of the concrete.The test results for the concrete strength and static elastic modulus are listed in As most papers reported, the addition of rubber particles weakened the concrete strength significantly ,56,57,58ff, fcp and fts represent the dimensionless values of flexural strength, axial compressive strength, and splitting tensile strength. As shown in ff/fcp is larger than fts/fcp, and both the ff/fcp and fts/fcp increase first and then decrease with the increase of rubber content. To ff/fcp and fts/fcp of PRC, the values are larger than that of RUC. This indicated that the pretreatment of rubber particles with sodium hydroxide further enhanced the ductility of the rubberized concrete, and the recommended content of rubber was about 15%.The effects of rubber content and pretreatment of rubber particles on the ratio of splitting tensile and axial compressive strength, and the ratio of flexural and axial compressive strength, are shown in The surface of the routine and pretreated rubber particles, as well as their bonding interface with cement matrix, were obtained by scanning electron microscopy. As shown in ff/fcp and fts/fcp decrease when the content of rubber particles exceeds 15%.Gao et al.  and BompcM/uM) of the cantilever beams reflects the ductility of the specimens. When cM/uM is too high, the material lacks ductility and there will be a sudden brittle failure of the specimen without obvious warning signs. The test results of cM and uM are listed in The ratio of cracking and ultimate moment  about all the mixtures are listed in The dynamic elastic modulus  was 26.684 Hz, while the value reduced 2.8% and 2.5% for the specimens produced with RUC (RUCB) and PRC (PRCB), respectively, with 20% rubber content. To the simply supported beams in the similar test condition reported by Zheng et al. , the redThe natural frequency is a major dynamic parameter of concrete, which is mainly affected by dynamic elastic modulus and unit weight of the specimen. With the increase of rubber content, the natural frequency of concrete specimens decreases slightly since the reduction of dynamic elastic modulus is smaller than that of unit weight. The reduction of dynamic elastic modulus is the representation of development in concrete damage ,59. The d2E) can also be determined through the free vibration test of cantilever beams, as listed in d1E and d2E, but all of the differences are less than 11.2%, and less than 10.0% reported by Zheng et al. [d1E and d2E of PRCB with 20% rubber content reduced by less than 15.0% and 11.6%. The flexural dynamic stiffness calculated with d2E reduced by 41.8% for NCB with the stress level of 0.8 and about 43.1–47.2% for RUCB (PRCB).The concrete dynamic elastic modulus  of the specimen decreases with the increase of rubber content, and the concrete failure period is prolonged. Therefore, the specimen will dissipate more energy with the increase of rubber content before its failure.The increase of damping ratio is slight in the elastic and elastic–plastic stage before the specimen cracking  and rubber content, respectively. PRC is a good choice where the requirement of strength is not too high, and the deformation as well as dynamic properties are relatively strict.The research of dynamic properties presented in this paper is of great significant for reference to evaluate the dynamic properties of rubberized concrete with some damage. Moreover, considering the limitation of the test data, improvement of the test setup and specimens, to verify further applicability and validity of the method to measure the concrete dynamic properties, the extended numerical tests are the focus of our next work.


Most antibiotics are prescribed in primary care. Locum or sessional GPs (locums) are perceived as contributing to higher prescribing and may face barriers to engaging with antimicrobial stewardship (AMS).To identify how locums’ antibiotic prescribing compares with other general practice prescribers, and how they perceive their role in antibiotic prescribing and AMS.Mixed-methods study in primary care.Data on antibiotic prescribing, diagnoses, and patient and prescriber characteristics were extracted from The Health Improvement Network database. A mixed-effects logistic model was used to compare locums’ and other prescribers’ antibiotic prescribing for conditions that do not usually benefit from antibiotics. Nineteen semi-structured telephone interviews were conducted with locums in England and analysed thematically.Locums accounted for 11% of consultations analysed. They prescribed antibiotics more often than other GPs and nurse prescribers for acute cough, sore throat, asthma and chronic obstructive pulmonary disease exacerbations, and acute bronchitis. The number of patients receiving antibiotics for these conditions was 4% higher  when consulting with locums compared with when they consulted with other GPs. Four themes capture the perceived influences on prescribing antibiotics and AMS: antibiotic prescribing as a complex but individual issue, nature and patterns of locum work, relationships between practices and locums, and professional isolation.Locums contribute to higher antibiotic prescribing compared with their peers. They experience challenges but also opportunities for contributing to AMS, which should be better addressed. With an increasing proportion of locums in general practice, they have an important role in antibiotic optimisation and AMS. The NASGP highlights the many challenges faced and skills required by locums, noting that locums are generally undervalued, lack support, and may be scapegoated.16 Studies support the widespread negative perceptions and experiences of employing and working as locums, which can have adverse implications for the professional identity, organisations, and patients.17–19 A recent narrative review on the quality and safety of locums across settings and countries suggested that the context of locums’ work may increase risks; however, only eight empirical studies were identified, which were methodologically poor.20Locum or sessional GPs are registered, licensed GPs who work in temporary positions — often for multiple organisations — covering short-term absences and vacancies.How does locums’ antibiotic prescribing compare to other general practice prescribers?How do locums experience and view antibiotic prescribing and AMS?Although locums form a substantial proportion of the GP workforce, there is little research on locums and, to the authors’ knowledge, none focused specifically on the role of locums in AMS. This study aimed to assess locums’ role in prudent antibiotic prescribing and explore their perceptions of AMS, which could help identify opportunities for further optimisation of antibiotic prescribing. Two research questions were addressed:21 The quantitative and qualitative data were analysed separately and sequentially; quantitative analysis addressed research question one and qualitative analysis addressed question two. Stakeholders, including professionals  and Patient and Public Involvement representatives provided advice and feedback on the study .A sequential explanatory mixed-methods study design was used to address the two research questions.22,23 The THIN database distinguishes antibiotic prescribing between different roles, including locums, salaried GPs, partners, and registrars. Data were included from English general practices that provided data for at least one full calendar year between 1 January 2013 and 31 December 2015.Data on oral antibiotic prescribing, diagnoses, and patient, practice, and prescriber characteristics were extracted from The Health Improvement Network (THIN) database, a primary care electronic database that is representative (∼7% coverage) of the UK population.7 and the extent of variation in practice-level antibiotic prescribing rates that can be explained by patient and practice characteristics.10 Using a similar approach, this study evaluated whether there were differences between the proportion of patients prescribed an antibiotic for common conditions when consulting with locums, compared with those consulting with other GPs and nurse prescribers. Prescribing patterns were not assessed for GP retainers, assistants, or other healthcare providers, owing to the low number of consultations associated with these groups.The authors previously evaluated variation between practices in the percentage of patients being prescribed an antibiotic for common conditions that do not generally require antibiotics,7 patients with relevant comorbidities or complications and recurrent and chronic presentations were excluded to reduce potential confounding by patient frailty or severity of disease. Confidence intervals for the prescribing proportions were calculated using robust standard errors to take into account dependence between multiple episodes from the same patient/practice.The following conditions, for which antibiotics do not usually provide additional benefit, were included: acute bronchitis, acute cough, acute otitis media, acute rhinosinusitis, acute sore throat, asthma exacerbations, and mild acute exacerbations of chronic obstructive pulmonary disease (COPD). In line with previous work,Locums were recruited through newsletters of the Royal College of General Practitioners and NASGP. Those interested were emailed study information and asked questions to enable sampling. Participants were included if they primarily worked as locums in NHS general practices in England. They were purposefully sampled to ensure diverse characteristics  exploring experiences of working as a locum, perceived influences on locums’ antibiotic prescribing and optimisation, awareness of and engagement with AMS initiatives, and suggestions for improvements. Participants were reimbursed for participation. Interviews were audiorecorded, transcribed verbatim, checked for accuracy, and anonymised.24 using NVivo (version 12) software. The first five transcripts were inductively and independently coded by three experienced qualitative researchers. The multiple coding25 was compared between the three authors and discussed to develop a coding framework, which was then used to analyse the remaining transcripts. New codes were added as necessary. Codes and categories were combined into themes to address the research questions.Interviews were analysed thematically ,In total, locums accounted for 11% of 1 511 787 consultations analysed. Acute sore throat  and acute cough (38%) were the two main conditions for which antibiotics were prescribed (data not shown). The number of patients receiving antibiotics for these conditions was 4% higher  when consulting with locums compared with when consulting with other GPs . A similFor several conditions, nurses prescribed antibiotics in a smaller proportion of consultations  and 2 thNineteen locums were interviewed . Intervi‘It’s very much an individual GP responsibility really. If a practice stressed to me the importance of avoiding inappropriate antibiotics, I’d almost feel like they were stating the obvious […] all GPs should understand what appropriate antibiotic prescribing is, that’s real basic bread and butter general practice.’Interviewees described antibiotic prescribing as complex clinical decisions influenced by individual-level factors, such as the GP’s experience, skills, confidence, the patient’s clinical presentation , and expectations/behaviour. Some described an increasing awareness of AMS among GPs and patients; others argued that more change is still needed. They perceived locums as having an important role in AMS because they constitute many prescribers, but that role was seen as similar to all GPs’ responsibility for appropriate prescribing:‘I’d be more interested in my own prescribing in comparison to the other doctors within the practice […] I don’t have a vested interest in any of the practices that I’m working in, it wouldn’t be that useful to me to know whether they’re high or low prescribers ...’Participants also reported varied experiences and views of using AMS strategies . Most did not know their individual antibiotic prescribing rates nor receive feedback on it, but they believed that they were low/prudent prescribers. They were interested in feedback on their prescribing and thought that it would be useful to locums and all GPs, and could be incorporated into GP appraisals. While most participants did not know the prescribing rates in practices they worked in, they had little or no interest in this, because as locums they described having no ‘vested interest’ in the practices:However, they were also unsure how locums’ prescribing could be identified, as partner GPs’ names were often on prescriptions issued by locums.The overall nature and patterns of locum work seemed to influence locums’ antibiotic prescribing. Participants worked across different practices and areas, which varied considerably in IT systems, workflows, and prescribing guidelines. This variation was challenging for locums who, as a result, might not always follow the local guidelines or workflows. For example, some participants reported following familiar prescribing guidelines from a different area to where they currently worked, and relied on IT prompts to indicate non-concordance with local guidelines. Participants suggested that working in one local area and regular, longer-term practices helped to minimise this challenge, and that adopting similar guidelines and approaches would make appropriate prescribing easier for locums.‘… the pressure that patients put on locums to prescribe, and the pressure of time on the locum […] it is to do with the time that we have, so you’re paid by the hour. You don’t necessarily want to run over […] think that makes a lot of locums more likely to not want to have that discussion to change patient perceptions about their use of antibiotics, and that it’s just easier to give antibiotics.’Participants described how locums have more control and flexibility over their work. Thus, some requested longer appointments or catch-up slots to ensure sufficient time to provide good-quality care . Others perceived locums as being under more pressure from patients and time owing to hourly payment. This could lead to quickly ‘closing’ consultations with antibiotic prescriptions (rather than taking time to discuss patients’ perceptions about antibiotic treatment) to avoid running over:Participants also described another aspect of control and flexibility: being able to choose the practices where they work. For example, they reported avoiding practices perceived as being disorganised and struggling with demand and insufficient staff . They perceived appropriate prescribing and good-quality care as being more difficult in such practices.‘… because I’m not their normal GP […] I have the time and I have the fresh pair of eyes to go, “Actually, you know, things are changing a bit and I read something recently or I’ve been to an education session and how about trying without antibiotics this time?”’Locums reported consulting more patients with acute infections who were more likely to require antibiotics (while patients with chronic illnesses were seen by regular doctors). They also reported that seeing unfamiliar patients and not being able to follow patients up can make locums more likely to prescribe antibiotics to avoid the risks of not prescribing, such as complaints and additional work for other GPs if patients re-consulted. However, participants also described how seeing unfamiliar patients may put locums in a better position to suggest a ‘new’ no-antibiotic approach, and that locums might be less concerned about potential negative impact of not prescribing on doctor–patient relationship:Participants’ relationships and communication with practices varied considerably. They reported no communication about practices’ initiatives or approaches related to prescribing and AMS , and said that they could participate or contribute if they were told about them . There was generally little to no feedback between practices and locums (unless concerning safety issues), and even less scrutiny over, and accountability for, locums’ prescribing than for regular clinicians. Participants reported that receiving feedback from practices would be helpful for them to improve and/or feel appreciated.just to see patients’  and not a part of practice teams. Thus, some reported that locums have neither influence on, nor a role in influencing, practices’ antibiotic prescribing, or AMS initiatives:‘… you’re not part of the team and they don’t make you feel part of a team, you’re just there to come in and cover the session and that’s all you’re there to do. You’re not involved in discussions about prescribing or the processes in the practice […] it’s not really my role as a locum to get involved in trying to change processes that don’t seem to be working.’Participants described how locums were generally perceived, and felt to be ‘ Others noted that locums working across many different practices have opportunities to observe, compare what works well with what does not, and identify potential improvements. Although locums’ feedback to practices was rare, some reported contributing to improvements in practices where they had good relationships.‘I saw a patient today who has COPD and you look back and see that’s what they do and I’m more inclined to prescribe antibiotics just in case because that’s what they do, rather than making my own judgment, I’m just following what the practice are doing.’Although participants reported that they practise similarly regardless of their role or where they work, the influence of different organisational cultures was apparent. Patient notes  and patients’ expectations for antibiotics gave locums a sense of the practices’ approaches to prescribing. Some reflected on being more inclined to prescribe antibiotics in higher-prescribing practices and where they would not feel supported by other GPs when not prescribing:‘working in silos’  and locums as even more professionally isolated than practice-based GPs. This was exacerbated by limited or no communication from commissioners, being less connected to professional groups and networks, and having to participate in professional training and meetings during unpaid time. Consequently, locums found keeping up to date with guidelines, evidence, and training more challenging, and having fewer opportunities for peer learning. This could contribute to less appropriate prescribing:‘ [Locums] are a little bit outside […] the mainstream GPs who are going to all the regular CPDs [continuing professional developments] and GP updates and maybe are more aware of the problems around antibiotic stewardship and resistance […] as a locum you can go to no CPD meetings […] you can be far away from the nourishing flow of information […] and you can see how you can have a very different viewpoint about antibiotic prescribing.’Participants described GPs as Nevertheless, some participants described locums as well trained and aware of evidence as a result of being more proactive about their professional development. Many reported being proactive about ensuring they had access to relevant resources  and communicating with practices and peers  to provide good care.‘We’re a significant amount of the workforce and we prescribe lots of antibiotics […] However, because we can’t influence local policy, perhaps our involvement would be limited only based on our personal experience […] our voices are minimally heard in general when we talk about health policy, just because locums and sessional GPs is just this nebulous group that aren’t really organised very well. So I think you’re missing probably lots of people that could add value to any sort of policy discussion.’Participants discussed how practices and commissioners should better integrate and support locums; for example, by circulating information, updates, and training opportunities to all GPs registered on Performers Lists. Some suggested that AMS-related training should be mandatory, and that local peer groups for locums should be encouraged. Finally, some suggested that locums should be better recognised as a considerable professional group, and involved in wider policy development:The analysis of prescribing data showed that locums were more likely than other GPs and nurse prescribers to prescribe antibiotics for acute cough, sore throat, acute bronchitis, asthma, and COPD exacerbations. The interviews found that although locums perceived appropriate antibiotic prescribing and engagement with AMS as individual GP’s responsibility, they are nevertheless influenced by factors specific to, or reinforced by, the characteristics of locum work.26 and qualitative27 studies (see Supplementary Tables S1 and S2 for checklists).To the authors’ knowledge, this is the first study to identify the role of locums in antibiotic prescribing and stewardship in general practice in England. A mixed-methods design allowed two complementary questions to be answered: the in-depth qualitative data provided possible explanations for the quantitative data. Quantitative data were derived from a large database and used established analysis methods. Qualitative data involved a purposeful sample and reached saturation on the themes reported. Trustworthiness and credibility were ensured by involving multiple researchers in the analysis and interpretation, keeping of analytic notes, and sharing the findings/interpretations with participants, stakeholders, and the Patient and Public Involvement group. Relevant guidelines were followed for reporting of mixed-methodsHowever, it is likely that a certain degree of misclassification affected the quantitative analyses. An unknown proportion of the consultations performed by locums could be incorrectly attributed to other GPs owing to the wrong identifier being used when entering the information about the consultation into the practice software. Given that default identifiers are more likely to be associated with individuals working in the practice, this may have resulted in a dilution bias reducing any difference between locums and other GPs. While the focus was on patients without relevant comorbidities or complications and excluded recurrent and chronic presentations, the possibility cannot be excluded that some of the (absence of) differences are explained by other differences in case-mix seen by nurse prescribers, locums, and other GPs. The quantitative data to which the authors had access dated from 2013 to 2015; prescribing patterns may have changed since then. It is possible that locums who volunteered to be interviewed had different views and experiences to non-volunteers. Finally, the findings are limited to locums practising in England, and their relevance to other parts of the UK may not necessarily be transferable.13,14 and this study shows that locums may indeed be more likely to prescribe antibiotics for some conditions. A survey published in 2000 found that 31% of practices employing locums in England were dissatisfied with locums’ clinical competence and underprescribing or overprescribing.19 As in this study’s interviews, the literature points to some factors that may affect the quality of locum care and prescribing; for example, locums may be less aware of local policies, less familiar with the practice population, and less likely to participate in audits, professional development, and networks.20 Moreover, it was found that locums consider appropriate antibiotic prescribing a GP’s responsibility (regardless of their role as locums), but some may perceive no vested interest in knowing or improving antibiotic prescribing rates in the practices where they work as locums. Lack of continuity of care may also affect doctor–patient relationships, potentially creating barriers to prudent antibiotic prescribing.28 The present findings show some similarity to influences on antibiotic prescribing in out-of-hours (OOH) practice: lack of existing relationship with patients (with similarly mixed views on the direction of this influence), lack of follow up, changing workforce, and inconsistencies between prescribers.29 Strategies and resources to address such specific challenges seem to be lacking for locums as for OOH prescribers.30 Effective AMS interventions can benefit from being informed by qualitative studies that identify behavioural influences on antibiotic prescribing.28,31–33 For example, communication training to help address antibiotics without extending consultation time may help locums, similarly to all GPs34 and OOH prescribers.35 Interventions targeting subgroups of GPs  can also help.36 Thus, targeted interventions for locums to promote prudent antibiotic prescribing by addressing the identified influences may be beneficial.Although research on locums is limited, this study’s findings are generally in line with other studies. It was previously found that health professionals perceived locums as contributing to suboptimal antibiotic prescribing,20 highlighting that locums ‘can only work as well as their working environment’.16 Moreover, it was found that locums may adjust their antibiotic prescribing to different practices where they work, influenced by different patient populations and prescribing cultures. An Australian study showed that while targeting antibiotic-related education and feedback at GP trainees may be helpful, inconsistencies in antibiotic prescribing among practice doctors contributed to internal conflicts for GP trainees, limiting the impact of the intervention.36 Similarly, other studies highlighted the role of organisational, social, and cultural contexts on antibiotic prescribing and AMS.13,37–39 Therefore, effective AMS interventions may benefit from targeting practice teams, and supporting better integration of locums into practice teams and wider professional networks.This qualitative analysis identified many influences on locums’ antibiotic prescribing that related to interpersonal and organisational factors , and contextual influences . Similarly, previous literature showed that most factors affecting the quality and safety of locum practice related to the organisational context and ways in which organisations deploy and support locums,and opportunities for practices and locums need to be recognised.16 Importantly, these findings may also be relevant to other prescribing issues , and locum work in OOH services.It is also important to recognise that locums are a diverse group with varied working patterns and approaches, and not all factors are equally relevant to every locum. Moreover, the interviewees in this study described (developing) different ways for dealing with challenges and opportunities for locums to contribute to improving antibiotic prescribing and processes in practices where they work . The role and contributions of locums in patient care, and both challenges Suggestions for improving antibiotic prescribing are summarised in To conclude, this study showed that locums may contribute to higher antibiotic prescribing and identified possible reasons. Locums face specific challenges to optimising antibiotic prescribing and engaging with AMS, including dealing with variation between practices and areas, more acutely unwell and unfamiliar patients, limited communication, feedback, and support, and professional isolation. They also have opportunities to contribute to AMS; for example, through more flexibility in consultations, ability to try ‘new’ no-antibiotic approaches with unfamiliar patients, and ability to identify and share good practice. These challenges need to be addressed and opportunities utilised. As locums are a considerable and growing part of the GP workforce their role in AMS and practices’ responsibilities towards enabling optimal prescribing by locums need to be recognised.


Pseudomonas fluorescens, a common, ubiquitous bacterium. We exposed P. fluorescens to the four antibiotics most commonly found in surface waters  and investigated antibiotic interactions for single and mixed treatments at different, field-realistic temperatures. We observed an overall dependence of antibiotic potency on temperature, as temperature increased efficacy of ciprofloxacin and ofloxacin with their EC50 lowered by >75% with a 10 °C temperature increase. Further, we show that mixtures of ciprofloxacin and ofloxacin, despite both belonging to the fluoroquinolone class, exhibit low-temperature-dependent synergistic effects in inhibiting bacterial growth. These findings highlight the context dependency of antibiotic efficacy. They further suggest antibiotic-specific off-target effects that only affect the bacteria once they enter a certain temperature range. This has important implications as freshwater systems already contain multi-drug antibiotic cocktails and are changing temperature due to environmental warming. These factors will interact and affect aquatic food webs, and hence this creates an urgent need to adapt and improve laboratory testing conditions to closer reflect natural environments.Use of antibiotics for the treatment and prevention of bacterial infections in humans, agri- and aquaculture as well as livestock rearing leads to antibiotic pollution of fresh water and these antibiotics have an impact on free-living bacteria. While we know which antibiotics are most common in natural environments such as rivers and streams, there is considerable uncertainty regarding antibiotics’ interactions with one another and the effect of abiotic factors such as temperature. Here, we used an experimental approach to explore the effects of antibiotic identity, concentration, mixing and water temperature on the growth of  DespiteAs a case in point, Cruz-Loya and colleagues (2019) showed that bacterial response to antibiotic–temperature interaction is complex and mechanism dependent . The resPseudomonas fluorescens. First, we determined MICs and concentration-dependent growth inhibition of four antibiotics at higher temperature (25 °C and 30 °C). As a second step, we combined two antibiotics (ciprofloxacin and ofloxacin) in tandem  at a range of environmental temperatures (from 15 to 25 °C).Although it is obvious that water temperature, antibiotic type and concentration as well as antibiotic mixture interact in their effects on bacteria, a more mechanistic understanding of these interactions is lacking. Here, we used an experimental approach to explore these drivers on bacterial growth response in Pseudomonas fluorescens SBW25 [5 cells/mL in 75% LB (except for experiment 2 where densities were 106 cells/mL as this density was more straightforward to adjust from the stock densities). Importantly, these initial concentrations are below stationary phase densities of around 109 cells/mL. P. fluorescens was exposed to four antibiotics (and their combinations) chosen because they are the most prevalent in polluted fresh waters [ns SBW25  was firsns SBW25 . Main cu®) set to 15, 17.5, 20 and 25 °C, which are all ecologically relevant as they are within the range of natural variation in fresh waters and are sub-optimal/optimal temperatures for growth. As temperature was hence confounded with a cabinet, we made sure to run replicates in time blocks  and this enabled us to replicate temperature treatments. The environmental chambers had a light source set to a 12 h dark and 12 h light cycle. For all experiments, growth was assayed after 24 h.MICs of ciprofloxacin, ofloxacin, sulfamethoxazole and sulfapyridine, all obtained from Sigma-Aldrich, were determined by measuring growth  in the presence of different antibiotic concentrations  at 30 °C (experiment 1) and 25 °C (experiment 2) after 24 h . To asse50 , also called ED50 . Supple50 values of single antibiotics and by comparing antibiotic–antibiotic interactions.The effects of temperature were explored mainly for experiment 3 across four temperatures by comparing bacterial growth for control and single antibiotics, by contrasting ECFor antibiotic–antibiotic interactions, we first performed a synergy check for the 30 °C data (experiment 1) using a serial dilution checkerboard approach. To analyze data from the interaction experiment at near field-realistic concentrations (experiment 3), we chose a simple and visual ‘expected OD’ approach. As the antibiotics used have the same mode of action, additive effects were to be expected and mathematical models exist . Here, wAll statistical analyses were performed in R statistical software  includin50 values of the latter two antibiotics were under 400 ug/L at 25 °C but there was no obvious pattern or growth inhibition for sulfamethoxazole and sulfapyridine (Experiment 1 (30 °C) showed that ciprofloxacin and ofloxacin had MICs of under 500 ug/L at this temperature, while sulfamethoxazole and sulfapyridine concentrations inhibiting bacterial growth were over 16 times higher than that . Comparing EC50 across the four temperatures in experiment 3 , the antibiotic mixtures showed increased synergy, yet overall temperature increased antibiotic efficacy for single antibiotics. A striking result of our study was that antibiotic mixtures had lethal effects even when the concentrations added together were below their respective individual toxicity in a realistic antibiotic pollution scenario.In this study, we investigated interactions between temperature and antibiotics at sub-MIC concentrations for The latter result was unexpected because ciprofloxacin and ofloxacin both belong to the fluoroquinolone class and are not expected to act in synergy. Antibiotics with different target action are more likely to show interactions when combined—either as synergy  or as anWe observed low- and high-temperature-dependent synergistic effects in inhibiting bacterial growth, suggesting antibiotic-specific off-target effects that only affect the bacteria once they enter a certain temperature range. This is in line with emerging literature on antibiotic mixing and temperature ,14,23 th50 values of single antibiotics decreased with temperature and explanations for this pattern include that both uptake [50 values of ciprofloxacin and ofloxacin compared to the experiment with lower bacterial densities. Density-dependent effects in bacteria could therefore be explored more when it comes to antibiotic assays and studies, as is indeed the case for other driving forces of evolution in bacteria such as time, space or disturbance . Furtheh uptake ,28. Cruzh uptake . A furthe, e.g., ).Interactions among different stressors  are at tWe found that temperature increased the efficacy of ciprofloxacin and ofloxacin and, further, our results point to low- and high-temperature-dependent synergistic effects in inhibiting bacterial growth. To date, fundamental ecological questions regarding the effects of antibiotics and temperature on freshwater communities remain unanswered, and a general assessment of their contribution to community and ecosystem functioning is also required. In particular, we need to know how antibiotic mixtures and temperature affect bacterial growth and adaptation and in turn the food web that is fueled by bacterial production.


The underlying density distributions of the data were visually explored using violin plots overlaid with box and whisker plots. A multivariate analysis of variance (MANOVA) was then used to model the main effect of birth quartile (four levels) on the physical and anthropometric scores. Results showed that physical and anthropometric test scores did not significantly differ according to birth quartile . We conclude that the physical and anthropometric profiles of high-level junior Australian Football players were similar according to birth year quartile across the modeled period. Therefore, how players utilize their physical and anthropometric attributes during game-play via contextualized, representative assessments, such as small-sided games, should be considered when examining potential causes of a RAE.The aim of this study was to explore differences in the physical fitness and anthropometric profiles between birth year quartiles of players attending the Australian Football League (AFL) National Draft Combine. Date of birth, anthropometric, 20 m sprint, vertical and running vertical jump, AFL planned agility, and 20 m Multi-Stage Fitness Test (MSFT) data were obtained for players selected to attend the Combine between 1999 and 2019 (n = 1549; M Annual age-grouping policies are common across most team sports and involve organization of athletes into defined chronological age groups. The Australian Football League (AFL) participation pathway has two competition streams: the local participation pathway and the talent pathway that flows into the elite competition. The local participation pathway consists of age-grouped levels from Under (U) 10 years old to open age competition, with the talent pathway encompassing regional and development squads, state squads at the U14–U16 levels, and national squads at the U16–U18 levels, with players then potentially selected for a professional senior club. Players identified as talented within the local participation pathway are selected by coaches and talent managers to join their regional team to compete in state-level competitions  between 1999 and 2019. National player data were available for all years between 1999 and 2019. Players were classified into the following birth quartiles: Q1: January–March, N = 1396, 34%; Q2: April–June, N = 1068, 26%; Q3: July–September, N = 913, 23%; Q4: October–December N = 694, 17%. In 2003 and 2008, changes to age eligibility policies were imposed at the National U18 level to target the RAE of players invited to attend the AFL National Draft Combine. Specifically, between 1999 and 2003 players were required to turn 17 years of age by June 30, with this cut-off date shifting to April 30 in 2008. Player birth quartiles of those attending National U18 drafts in these years were classified based on the first month of the new age eligibility date . All players 17 years of age were excluded from analysis between 2010 and 2013, as during these years the acquisition of these players was limited to trades, given the introduction of two new AFL teams [This study used a 20-year retrospective cross-sectional design to examine differences in the physical and anthropometric profiles between male Australian footballers born in differing age-group quartiles. Date of birth (DOB), physical fitness, and anthropometric data were obtained for U18 players who were selected to attend the AFL National Draft Combine , Typical Error (TE) = 1.0 cm; body mass (kg), TE = 1.0 kg); 20-m sprint (s), TE = 0.03 s; stationary vertical and running vertical jump (cm), TE = 1.4 cm; AFL planned agility (s), TE = 0.04 s; and aerobic endurance ; with the best of three efforts recorded for all tests except the 20 m MSFT ,35. The First, the underlying distribution of each assessment relative to each year was visually inspected using overlaid density distribution plots in the ggplot2 package  in the R computing language . This step enabled us to confidently pool the dataset. Next, to explore the underlying density distributions of the data, violin plots with an overlaid box and whisker plot  were developed for all physical and anthropometric tests relative to birth quartile. This analysis was completed using the ggplot2 package , with the plots arranged and annotated using the cowplot package  in the R computing language . A multivariate analysis of variance (MANOVA) was then used to model the main effect of birth quartile (four levels) on the physical and anthropometric test scores. This modeling was completed using the “manova” function, with significance set α < 0.05. Pending the outcomes of the MANOVA (noted via a significant Pillai’s Trace), univariate analysis of variance was planned to identify which (if any) of the physical and/or anthropometric tests differed significantly according to birth quartile.p = 0.631), indicating the physical and anthropometric profiles of players were similar across all four birth quartiles. Given this outcome, follow up univariate analysis was not performed on the data. Mean data for the physical and anthropometric characteristics relative to birth quartile are provided in the online Visual inspection of the density distributions of the data using the violin plots  indicateThe aim of this study was to explore if the physical and anthropometric attributes of players attending the AFL National Draft Combine differed according to birth quartile. Results did not yield a significant effect of birth quartile, with all players at this U18 level possessing a relatively homogenous physical and anthropometric profile. Therefore, it appears that players are largely selected for the AFL National Draft Combine based on relatively homogenized physical and anthropometric profiles, supporting previous studies which have suggested this occurs in professional adult populations ,39. TherSeveral studies have investigated the prevalence of RAE within talent development programs and elite senior competitions of invasion sports ,5,19,40.While the AFL National Draft Combine provides a detailed assessment of the physical and anthropometric qualities of talented U18 players ,42, theyWhile this study examined the influence of physical and anthropometric profiles on RAE at the National Draft Combine over a substantial time period, the outcomes should be considered with respect to limitations. A key limitation of the current study is the representativeness of the cohort analyzed. We acknowledge that the athletes assessed at the National Combine are selected to attend this event by coaches and selectors. Therefore, there is potential for an inherent bias within the sample based on how the players were invited to participate in the testing Combine. Further, while not a specific aim of this study, future research should examine whether the current findings are replicated between the local competition levels , and the entry levels of the talent development pathway . This work will establish whether players who do not exhibit a physical profile within the associated bandwidths are discriminated against in relation to selection for more high-level talent development programs.This study examined the physical and anthropometric profiles of high-level junior Australian football players attending the AFL National Draft Combine according to birth year quartile over a 20-year period. There were no significant differences in the physical and anthropometric profiles across the birth year quartiles, despite there being a known RAE across the same cohort. Therefore, it appears that players are selected for the AFL National Draft Combine based on relatively homogenized physical and anthropometric profiles, and that the RAE is influenced through other aspects of performance, such as technical and tactical skill. We recommend that future work examines the performance of players attending the National Combine via contextualized, representative assessments, such as small-sided games, when examining potential causes of a RAE.


In this research, high strength fiber reinforced concrete (HSFRC) was used to replace the normal strength concrete (NSC) in steel-concrete composite beams to improve their working performance, which might change the static performance of stud connectors. Firstly, push-out tests were conducted to investigation on the static performance of stud connectors in steel-HSFRC composite beams and compared with steel-NSC composite beams. Studs of 8 sizes, 13 mm, 16 mm, 19 mm and 22 mm in diameter and 80 mm and 120 mm in height were adopted to study the influence of stud dimension. The test phenomenon shown that the crack resistance of HSFRC was better than that of NSC, and there were some splitting cracks on NSC slabs whereas no visible cracks on HSFRC slabs when specimens failed. Next, the load-slip curves of studs were analyzed and a typical load-slip curve was proposed which was divided into four stages. In addition, the effects of test parameters were analyzed according to the characteristic points of load-slip curve. Compared with NSC slab, HSFRC slab could provide greater restraining force to the studs, which improved the shear capacity and stiffness of studs while suppressed the ductility of studs. The shear capacity, stiffness and ductility of studs would significantly increase with the increasement of stud diameter and the studs with large diameter were more suitable for steel-HSFRC composite beams. The stud height had no obvious influence on the static performance of studs. Finally, based on the test results, the empirical formulas for load-slip curve and shear capacity of stud connectors embedded in HSFRC were developed which considered the influence factors more comprehensively and had better accuracy and applicability than previous formulas. In recent years, the steel-concrete composite beams have been widely used in engineering structure because of the superior performance and the better comprehensive benefits ,2. In stGenerally, concrete slabs of steel-concrete composite beams are made of NSC, so there is muc research on the static performance of studs in steel-NSC composite beams. Through push-out test, Buttry et al.  indicateHowever, it has been found that in the practical use of steel-NSC composite beams, such as cracking of concrete slab in negative moment area, poor fatigue resistance, weak durability in extreme environment and so on . A numbeEven though replacing NSC with FRC and UHPC would improve the working performance of steel-concrete composite beams to a certain extent, it still has some limitations. The compressive strength of FRC was similar to that of NSC, so the performance improvement of steel-FRC composite beam was not very great . The UHPIn order to research the static performance of stud connectors in steel-HSFRC composite beams, 4 steel-NSC and 8 steel-HSFRC push-out specimens with different dimensions of studs were tested. Firstly, the failure modes of specimens and the shear capacity, stiffness and ductility of stud connectors were described and analyzed. Next, in accordance with the load-slip curves, the influence law of concrete type, diameter and height of studs on the static performance of stud connectors was revealed. Finally, empirical formulas for load-slip curve and shear capacity of stud connectors in steel-HSFRC composite beams were developed by test results fitting. This study provided a new method to improve the performance of steel-concrete composite beams. In addition, the mechanical behavior of steel-HSFRC composite beams was studied in detail, and the relevant calculation formulas were proposed. The research results could provide reference for the design and application of the new type of composite beam.A total of 12 composite beam specimens were prepared in this push-out test to investigate the effect of concrete type and the diameter and height of headed stud on the static behavior of stud connectors. According to Eurocode-4  and mode3 cubic specimens and 100 × 100 × 500 mm3 dog bone specimens were fabricated to test the compressive and tensile strengths of concretes. The elastic modulus of concretes was obtained by DT-2 Dynamic elastic modulus tester. The measured material properties of concretes were shown in The NSC and HSFRC used in this test were commercial concrete directly purchased from Zhongde Xinya Building Materials Co., Ltd, Xinmi, China. The mixture proportions of NSC and HSFRC are summarized in The H-shaped steel girder and the steel plate at the top of the push-out specimen were made by Q345D steel, whose yield strength, tensile strength and elastic modulus were 345 MPa, 470 MPa and 209 GPa, respectively. The reinforcement bars in concrete slabs were HRB400 bar with diameter of 8 mm, and they yield strength, tensile strength and elastic modulus were 400 MPa, 470 MPa and 200 GPa, respectively. All stud connectors were grade ML15, but they had different dimensions. The mechanical properties of studs were provided by merchant, as shown in The push-out test was conducted by a microcomputer-controlled compression-shear fatigue test loading system (PLU-1000) with a load capacity of 1000 t. Before formal loading, the specimen was preloaded for 3 times with a load of 20% of the elastic bearing capacity obtained by theory and finite element calculation. During the preloading period, the influence of the nonlinear force and the gap between the various parts of the test system was reduced and the working conditions of loading system and the LVDTs were checked. After the end of the preloading 10 min, the data of each measuring point were recorded as the initial state of the test, and the formal test loading began. The specimen was loaded generally according to the increment of 15 kN, while the load increment was reduced to 5 kN when the specimen stepped into the elastoplastic critical stage. The loading rate was contained at 5 kN/min. After completion of every stage loading, the load was maintained for 5 min to make the specimen fully deformed. When the breakout of concrete and fracture of studs occurred, it was considered that the specimen had been damaged, and the test was finished. After the specimen failure, the failure surfaces of the specimen were observed, and the visible cracks on the concrete slab were marked. In the end, the concrete slabs were broken, and the studs were taken out to observe they deformation.Some previous studies on push-out shown that there were three modes of failure of composite beams with stud connectors: concrete breakout, stud failure and combine failure of concrete and studs, among which stud failure can be divided into failure from shank and from weld . In thisFor the NSC specimens, the failure modes were combined failure of concrete and studs as shown in It can be seen from In addition, some common damage characteristics were observed in NSC and HSFRC specimens. There was a small area below every stud on all the concrete slabs where the concrete was crushed, but the crushed areas on HSFRC slabs were smaller than NSC slabs. This phenomenon indicated that the concrete below the stud would receive great compressive stress and the HSFRC had better damage resistance than NSC. It also can be found that all the studs only had a small deformation at the shank root, and the remaining parts of shanks embedded in the concrete slabs remain upright. It manifested that NSC and HSFRC both had a good embedding effecting on the studs, which limited the deformation of studs at a certain extent.The load-slip curve is an important basis for analyzing the mechanical behavior of stud connector, and which could completely reflect the variation of mechanical performance of stud during the process of push-out test. The load-slip curves of all the push-out specimens in this test are shown in Elastic deformation stage (O-A): The load was proportional to the relative slip and the relative slip was quite small. Generally, the slope of the curve at this stage was taken as the initial shear stiffness of the stud. There was no visible change and crack in all the specimens. Since the studs and concrete slabs of specimens were in elastic stage, and the specimens did not reach normal use state.Yield stage (A-B): The slop of load-slip curve started to decrease, and it changed from a slanting straight line to a convex curve. The part of concrete in contact with the shank root entered the plastic deformation stage, which caused the lateral support of concrete to the stud to decrease gradually. With the continuous increase of load, the studs gradually yielded, and some cracks occurred in NSC slabs. It was these reasons that resulted in the increasement relative slip accelerating. The secant slope at the end point of this stage could be considered to be the average stiffness of the entire deformation process of the stud.Plastic strengthening stage (B-C): The rising rate of load-slip curve further decreased, and the curve gradually rose to the peak point and then tended to be stable. The concrete in a certain area under the stud root had completely crushed. The studs entered the plastic strengthening stage from the yield stage, during which their deformation increased continuously. In this stage, some diagonal and splitting cracks would occurr and developed on NSC slab, while there was no visible crack on HSFRC slabs. It could be seen that there was a significant displacement between the H-shape steel and the concrete slabs.Failure stage (C-D): The load on the stud decreased gently with increase in the relative slip after the stud reached the maximum. In the end, the load decreased sharply and suddenly, indicating the failure of the specimen. The load-slip curves here did not show the final steep decline section, because the specimens had failed at this time, which was not of research significance. All the specimens made a loud noise when they were broken, and the studs were cut off.The load-slip curves were divided into four stages in according to the characteristic points and the deformation process of steel and concrete under stress ,33. In or(Pu), r(Su) and r(k2) represent the change rate of shear capacity, ultimate interfacial slip and shear stiffness of stud. Combined the load-slip curves with specific test results in These load-slip curves were processed, and test results were obtained to analyze the static performance of these studs. It was considered that each stud was subjected same force in the test, so the shear capacity of per stud was 1/8 the ultimate load of the specimen. According to the previous research, the push-out specimen was in the elastic deformation stage when the slip is 0.2 mm, and it was in the elastic-plastic deformation stage when the slip reaches 2 mm. Hence, the secant slope of the load-slip curve at the interfacial slip of 0.2 mm and 2 mm could be used to calculate the shear stiffness . The ultIt can be found from As can be seen from The comparison of the load-slip curves of studs with different height embedded in HSFRC slabs is shown in The load-slip curve is the most important representation of the static shear behavior of stud connectors, which plays a significant role in analyzing the shear capacity, stiffness and ductility of studs. If the load-slip curve of stud could be correctly predicted by mathematical expression, the development of steel-concrete composite beam design and evaluation of the structural performance of existing similar structure would be greatly promoted. At present, based on the results of push-out tests, many researchers have put forward some equation to express the load-slip curve of stud connectors by mathematical fitting. Majority of these studies have focused on the studs embedded in NSC, and minority of them have given the equations for the stud in HPC and UHPC. However, there is little research has been studied on the studs in steel-HSFRC composite beam.P represents the load on per stud; S represents the interfacial slip.Ollgaard et al.  carried To study the influence of the different properties of concrete type, An and Cederwall  tested tXue et al.  conductedstud represents the stud diameter, and its unit is mm.It can be seen that the stud diameter was not taken into account in the above expressions. However, it was found in this study that the stud diameter had a great influence on the variation trend of load-slip curve. Similarly, Wang et al.  also disTong et al.  studied S is inch, while in Equations (2)–(6), the unit of S is mm.In Equation (1), the unit of The test results indicated that the concrete type had an importance effect on the performance of stud connectors. Hence, the above load-slip formulas for NSC and UHPC specimen could not be well applied to the HSFRC specimens. In accordance with the previous research and the experiment results of HSFRC specimens in this study, an empirical prediction formula for the load-slip curves of the studs in steel-HSFRC composite beams was proposed. Next, the coefficients were derived by linear regression analysis. The formula is as follows:P/Pu less than 1 were used. Since the descending section of the curve had little significance for the static performance characterization of the stud connectors.It was noted that in the fitting of Equation (7), only the test point with P/Pu = 0.4, 0.6 0.8 and 1.0) obtained by test results and Equations (1)–(7) are listed in The experimental load-slip curves of HSFRC specimens and the load-slip curves calculated by Equations (1)–(7) are shown in The shear capacity of stud connectors is an important parameter in design of steel-concrete composite beams. Relevant codes in some mainstream regions have given several calculation methods of shear capacity of studs in steel-NSC composite beam. Many researchers have also developed some shear capacity prediction formulas for studs in different types of steel-concrete composite beam by push-out test.d is the diameter of stud; fck is the standard compressive strength of concrete; Ec is the elasticity modulus of concrete; γv is the partial safety factor; As is the cross-sectional area of stud; fuk is the standard tensile strength of stud; and α is the influence coefficient of stud aspect ratio which can be calculated by:hs is the height of stud.Combined with the test data of 75 push-out specimens and the calculation model proposed by Ollgaard et al. , the Eurfc′ is the compressive strength of concrete cylinder; fu is the tensile strength of stud; and φsc is the resistance coefficient of stud which is equal to 0.85.In America, the code AASHTO LFRD  provide fc is the cube compressive strength of concrete.In the Chinese code GB50017-2017 , the sheλ is the influence coefficient of stud aspect ratio and calculated as:The formulas for shear capacity of studs given in above codes are mainly taken the strength of concrete crushing as shear capacity of studs in composite beams, and the tensile failure strength of stud shank is regard as the upper limit of stud shear capacity. These formulas only consider the concrete crush and stud fracture separately, while ignoring the interaction between stud connectors and concrete slabs. Hence, according to Equations (9)–(11), the shear capacity of studs with same dimension in NSC and HSFRC specimens are equal, which is not consistent with the actual test results. In view of this deficiency, Xue et al.  developeγ is resistance coefficient.Based on the test results of steel-UHPC with short studs, Shao et al.  proposedft is the tensile strength of concrete and K is a constant which is equal to 95.3.The above formulas were mainly used to calculate the shear capacity of the stud connectors embedded in NSC and UHPC, and they did not consider the concrete tensile strength. In fact, the tensile strength of HSFRC was significantly bigger than that of NSC due to the existence of fiber, which might influence the shear capacity of studs. Hence, a formula for calculating the stud shear capacity was proposed in this paper, which considered the concrete tensile strength and was suitable for studs embedded in different types of concrete. In this formula, the shear capacity of stud connectors was divided into the shear capacity of stud without constraint and the increasement of strength caused by concrete . The shev and γ are assumed to be equal to 1. It can be found that the prediction formulas in the three current codes were conservative and Xue et al. [e et al.  overestiIn order to verify the applicability of the shear capacity formula proposed in this paper, the experimental results in other literatures ,21,33,37(1)In the push-out tests, the steel-NSC and steel-HSFRC composite beams shown different failure modes. The failure modes of steel-NSC specimens were combine failure of concrete and studs, and those of steel-HSFRC specimens were stud failure. Some diagonal and splitting cracks occurred on the surfaces of the NSC slabs, and the number of cracks increased with stud diameter. However, there were no visible cracks on the HSFRC slabs. This indicated that the cracking resistance of steel-HSFRC composite beams was better than that of steel-NSC.(2)The static performance of stud connectors would be influenced by the concrete type and the diameter and height of stud. In comparison with the studs embedded in NSC, the shear capacity and stiffness of studs embedded in HSFRC increased significantly but the ductility would decrease. With the diameter and height of stud increasing, the shear capacity and stiffness of studs increased while the ductility decreased. Among them, the influence of stud height was slight, which could be ignore when the stud diameter was reasonable.(3)Based on the test results, the empirical formulas for the load-slip curve and shear capacity of stud connectors in steel-HSFRC composite beams were proposed. Thereinto, the formula for load-slip curve took the stud diameter into account, and the formula for shear capacity divided the shear capacity of studs into the shear capacity of stud without constraint and the increasement of strength caused by concrete. In addition, the influence of concrete tensile strength was considered in shear capacity formula. These two formulas were more consistent with the actual situation and could more accurately predict the static behavior of steel-HSFRC composite beams.In this study, 12 push-out specimens with the test parameter of concrete type, concrete strength, stud diameter and stud height were tested to research the static performance of stud connectors in steel-NSC and steel-HSFRC composite beams. In accordance with the test results and the above analysis, the following major conclusions can be drawn:


In this paper, the findings of numerical modeling of the composite action between normal concrete and Cold-Formed Steel (CFS) beams are presented. To obtain comprehensive structural behavior, the numerical model was designed using 3-D brick components. The simulation results were correlated to the experimental results of eight push tests, using three types of innovative shear connectors in addition to standard headed stud shear connectors, with two different thicknesses of a CFS channel beam. The proposed numerical model was found to be capable of simulating the failure mode of the push test as well as the behavior of shear connectors in order to provide composite action between the cold-formed steel beam and concrete using the concrete damaged plasticity model. Currently, there is extensive use for Cold-Formed Steel (CFS) sections in the construction industry. They are used as lightweight load-bearing frames . In the However, researchers were excited to conduct investigations on composite CFS concrete members. For example, an innovative lightweight composite bridge girder was investigated . A compoInnovative composite concrete CFS beams were studied. Two CFS sections with different thicknesses  were used. Three innovative shear connectors made of CFS sections were investigated. They are namely SBSC a, DBSC b, and HPTo allow for slippage during the test, all specimens were constructed with an 0.080 m reset between the ends of the concrete slab and the steel beam. The schematic push test specimen is shown in We conducted 3-D nonlinear FE simulations using ABAQUS software , while cThree-dimensional solid elements (C3D8) were used to model the key structural members to obtain detailed structural behavior .Mechanical properties of the steel beams and shear connectors ,21 were The simulation methodology can be summarized as follows: For reinforced concrete elements, the ABAQUS program’s concrete damaged plasticity model for reinforced concrete elements was used, which can reflect the complete inelastic behavior of concrete in stress and compression, including damage characteristics. The concrete damaged plasticity model, which takes into account isotropic elastic damage and plastic behavior of materials, can simulate tensile cracking and compressive crushing of concrete materials ,27.For bolts and nuts, the mechanical properties were assumed to be elastic-perfectly plastic. For Grade 8.8 bolts, the yield strength was 640 MPa and the elastic modulus was 210,000 MPa.The welding between headed stud shear connectors and CFS flange were modeled using the ‘‘tie’’ type constraint in ABAQUS.To prevent the FE model to move or twist, it was restrained from both sides to simulate the actual boundary conditions, as shown in The ABAQUS contact function was used to model the interaction between components, including the interface between the two channels, between the concrete slab and the metal deck, between the metal deck and the beam, between the shear connectors and concrete slab, between the bolt shanks and the web of the beam, between the bolt heads and the web of the beam, and between the web of the channel and the shear connectors.A contact was simulated as a surface-to-surface contact with a small sliding choice. To avoid mutual penetration of the steel and concrete in the normal direction, a “hard contact” was assumed for the normal contact behavior, while a friction contact with a coefficient of m = 0.3 was applied tangentially to the surface of the contact pairs.The loads were applied to the beam at one-point loads . As a consequence of the initial rotation of SBSC and DBSC shear connectors, the shear connector was deformed, as can be seen from In DBSC specimens, For push test specimens with headed stud shear connectors (HSSC), the observed failure mode was caused by deformation of the shank of the stud followed by pulling-out from the thinner flange of steel beam, as shown in The developed finite element models are in good agreement with the experimental results of the push tests and observations. The deformed shapes and the relevant failure modes were accurately captured by the model for all types of shear connectors. For example, the concrete crushing and shear connector rotation in SBSC, DBSC, and HPSC push test specimens were clearly captured by the FE model.The concrete damaged plasticity model in ABAQUS can accurately capture crushing and the longitudinal crack of a concrete slab, which is the common failure mode for SBSC, DBSC, and HPSC.The developed finite element models accurately model the interaction between the metal decking and concrete slab. For DSBC, the separation between the concrete slab and metal deck occurred is clearly captured by the proposed finite element models. This weak connection is due to the DBSC shear connector’s wide flange surface (double of the SBSC) that leads to such separation.The bearing around the bolt of shear connector that is near to the concrete slab (which was the only bolt resisting the rotation after concrete slab crushing) in the test results of SBSC, DBSC, and HPSC specimens is accurately predicted by the model by observed stress concentration around the bolt hole connecting the shear studs to the web of the cold formed beam.The proposed finite element models have clearly captured the failure modes of HSSC specimens being the deformation of the shank and the pulling-out of the stud from the thinner flange of steel beam for HSSC specimens, while no crack was observed in the concrete slab.The finite element results of ultimate loads were found to be in very acceptable agreement with experimental data, ranging between 0.94 and 1.04. However, the results of the section analysis are generally conservative compared to experiments.This study was focused on developing an FE model to simulate the composite CFS beam behavior. A total of eight push tests were modeled using non-linear material properties of concrete and steel and concrete damaged plasticity model in ABAQUS. Four types of shear connectors were modeled  with two different thicknesses of CFS channel beam. The following conclusions may be drawn: