Although methionine (Met), the first-limiting dietary amino acid, has crucial roles in growth and regulation of lipid metabolism in ducks, mechanisms underlying are not well understood. Therefore, the objective was to use dietary Met deficiency to investigate the involvement of Met in lipid metabolism and fat accumulation of Pekin ducks.A total of 150 male Pekin ducks  were allocated into 5 groups (6 replicates with 5 birds each) and fed corn and soybean meal-based diets containing 0.28%, 0.35%, 0.43%, 0.50%, and 0.58% Met, respectively, for 4 weeks. Met-deficient  and Met-adequate  groups were selected for subsequent molecular studies. Serum, liver, and abdominal fat samples were collected to assess the genes and proteins involved in lipid metabolism of Pekin ducks and hepatocytes were cultured in vivo for verification.P < 0.05), whereas serum concentrations of total cholesterol, low density lipoprotein cholesterol, total protein, and albumin decreased (P < 0.05) in Met-D ducks compared to those in Met-A ducks. Based on hepatic proteomics analyses, dietary Met deficiency suppressed expression of key proteins related to fatty acid transport, fatty acid oxidation, tricarboxylic acid cycle, glycolysis/gluconeogenesis, ketogenesis, and electron transport chain; selected key proteins had similar expression patterns verified by qRT-PCR and Western blotting, which indicated these processes were likely impaired. In vitro verification with hepatocyte models confirmed albumin expression was diminished by Met deficiency. Additionally, in abdominal fat, dietary Met deficiency increased adipocyte diameter and area (P < 0.05), and down-regulated (P < 0.05) of lipolytic genes and proteins, suggesting Met deficiency may suppress lipolysis in adipocyte.Dietary Met deficiency caused growth depression and excess fat deposition that were ameliorated by feeding diets with adequate Met. Serum triglyceride and non-esterified fatty acid concentrations increased (Taken together, these data demonstrated that dietary Met deficiency in Pekin ducks resulted in stunted growth and excess fat deposition, which may be related to suppression of fatty acids transportation and hepatic catabolism.The online version contains supplementary material available at 10.1186/s40104-022-00709-z. Meat duck production has been increasing annually to support demands . Over paMethionine (Met), an essential amino acid in diets of human and animals, regulates lipid metabolism , 5. IncrProteomics have been used to study major nutrition-associated problems in humans and animals  and can Considering differences among mammals, rodents and poultry in fat metabolism, correlational studies on molecular mechanisms of lipid metabolism and fat deposition in mammals and rodents may not be biologically relevant for ducks. To characterize mechanisms of lipid metabolism and fat accumulation induced by dietary Met deficiency in ducks, proteomics analyses, along with RT-qPCR and Western Blot verification of related genes and proteins, were done in liver or abdominal fat of Pekin ducks fed Met-D and Met-A diets. Furthermore, hepatocytes were cultured in vitro to verify proteomics data. Therefore, this study was expected to produce evidence for the role of Met in regulating lipid metabolism of Pekin ducks.All procedures involving live animals were approved by the Animal Care and Use Committee of Institute of Animal Science, Chinese Academy of Agricultural Sciences (IAS-CAAS) and were performed according to their guidelines (IAS2018-15). A total of 180 1-d-old male Pekin ducklings  were fed conventional duck starter diets  for 14 d. After an overnight fast, all ducks were weighed individually at 15 days of age, and 150 ducks were selected by removing those that were lightest and heaviest. Ducks were randomized into 5 groups, each with 6 replicates and 5 birds per replicate according to similar pen body weight (558.5 ± 4.4 g). These 5 groups were kept in separate plastic-floor pens (200 cm × 75 cm × 40 cm) for 4 weeks (15 to 42 days of age) and fed a basal diet, supplemented with 5 dietary Met levels.All ducks had ad libitum access to feed and water. Water was provided by drip-nipple water supply lines, and pelleted diet by feeders in each pen. Environmental conditions were consistent among birds and similar described previously , includiA single-factor completely randomized trial design was used. Ducks were fed a basal diet supplemented with 5 levels of Met . The basal diets of growing Pekin ducks were comprised mainly of corn and soybean meal (Table At the end of the experiment (42 days of age), the weight of ducks and residual diet from each pen were measured after an overnight (10~12 h) fast. The average daily weight gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR) were determined for ducks from 15 to 42 days of age, with ADFI and FCR corrected for mortality. Total Met intake and Met intake per weight gain (Met intake/ADG) were calculated according to the following formula : Met cong for 15 min at 4 °C) and serum removed and frozen at -20 °C for determination of biochemical parameters. The ducks were sacrificed by neck cutting, and samples of liver and abdominal fat (from consistent locations) were quickly collected, and frozen in liquid nitrogen and stored at -80 °C until further analysis for proteomics, Western blot, and qRT-PCR. Subsequently, liver and abdominal fat tissues (consistent locations) were fixed in 4% paraformaldehyde for histology and remaining tissues were stored at -20 °C for analysis of hepatic lipids.At 42 d, after overnight fasting, 2 ducks from each pen (12 birds/group) were randomly selected from 2 groups: Met-deficient group  and Met-adequate group . Individual blood samples of selected ducks were collected via jugular venipuncture. After 2 h at room temperature, blood samples were centrifuged (3500 × Serum non-esterified fatty acid (NEFA) concentrations were measured with commercial kits  according to the manufacturer’s instructions. Other serum biochemical parameters were determined with an automatic biochemical analyzer , using corresponding kits .After fixation in 4% paraformaldehyde, liver and abdominal fat tissues were dehydrated in increasing concentrations of alcohol and embedded in paraffin. Sections were cut (4-5 μm thickness), stained with Hematoxylin-Eosin (H&E), and observed under light microscopy with 100× or 400× magnification .Hepatic total lipids were extracted by homogenizing minced liver samples in chloroform-methanol , as described . The extThree biological replicates  from each group were used for iTRAQ assays. Hepatic protein was extracted as described  and protP <0.05, as analyzed with a by the paired Student’s t-test. Both GO annotation and KEGG pathway enrichment analysis of differentially expressed proteins were used to determine functional subcategories and metabolic pathways.Data for the original MS/MS files identification and quantification were analyzed against the database Uniprot-taxonomy-Anas-platyrhynchos.fasta using ProteinPilot Software V4.5 . Only unique peptides with ≥ 95% confidence intervals were contained in the iTRAQ labelling quantification and used for further analysis. To identify differentially expressed proteins, relative protein expression values were compared between groups (Met-D vs. Met-A). Proteins were regarded as differentially expressed if the iTRAQ ratios were ≥ 1.2 or ≤ 0.83 with 2 at 37 °C. The HepG2 cells were cultured in 6-well plates and starved for 6 h after reaching 90% confluence. Subsequently, the HepG2 cells were incubated in the Met-free basal DMEM medium  and the basal medium supplemented with 25 or 200 μmol/L L-Met (Sigma) for 24 h, respectively. The duck primary hepatocytes were cultured in 6-well plates in the Met-free basal DMEM medium supplemented with 0, 25 or 200 μmol/L L-Met for 24 h, respectively, after starving for 6 h. Both kinds of hepatic cells were harvested and lysed in PIPA buffer, and frozen at -80 °C for further analysis of ALB protein expressions.Both sources of hepatic cells, including HepG2 cell line (Cell Bank of Chinese Academy of Sciences) and duck primary hepatocytes , were cAnas platyrhnchos). The PCR amplification efficiency for each primer ranged from 90% to 110%, with each sample analyzed in triplicate. Relative mRNA expression of target genes was determined using the 2−ΔΔCt method [Total RNA of liver, abdominal fat, and hepatocyte samples was isolated with RNAiso Plus , following manufacturer’s instructions. The total RNA concentration of each sample was measured by determining absorbance at 260 nm  and RNA integrity was evaluated by agarose gel electrophoresis. Then, RNA samples were reverse-transcribed to complementary DNA (cDNA) according to the manufacturer’s instructions , as follows: incubation at 37 °C for 15 min, followed by 85 °C for 5 s. Quantitative Reverse Transcription (qRT) PCR analysis was performed in a fluorescence detection system , with these cycling conditions: 30 s at 95 °C for denaturation, 5 s at 95 °C, 34 s at 60 °C (40 cycles), 15 s at 95 °C, and a final step for 1 min at 60 °C. Primers were designed using Primer Premier 6 software , and syng at 4 °C for 15 min, and supernatant collected. Total protein concentrations were determined using a BCA protein assay kit . Equal quantities of total protein (25 μg per lane) were separated on 10% SDS-PAGE gels, and blotted onto polyvinylidene difluoride membrane . After being blocked in 5% skim milk for 2 h, the membrane was incubated with primary antibodies overnight at 4 °C. Thereafter, the membrane was incubated with the appropriate HRP-labeled secondary antibody for 1.5 h at room temperature. Immuno-reactive proteins were visualized using a chemiluminescence detection kit . An imaging system (Tanon Gis) and ImageJ software  were used to determine the blot signal and protein density. Primary antibodies against medium-chain specific acyl-CoA dehydrogenase (ACADM) , NADH dehydrogenase (ubiquinone) Fe-S protein 1 (NDUFS1) , albumin (ALB) , lactate dehydrogenase (LDH) , fatty acid-binding protein 1 (FABP1) , fatty acid synthase (FASN) , adipose triacylglyceride lipase (ATGL) , hormone-sensitive lipase (HSL) , and phosphor-hormone-sensitive lipase at Ser563 (p-HSL-S563)  were used. All results were expressed as the abundance of each protein relative to beta-tubulin , and relative expression was normalized.Total proteins from liver, abdominal fat, and hepatocytes were lysed in PIPA buffer containing 1% protease inhibitor and 1% phosphorylase inhibitors, centrifuged at 12,000 × t-test (SAS Version 9.4). Values were considered significant if P < 0.05. For growth performance and carcass traits, Duncan’s multiple comparison tests were used to compare differences among means if there were differences in dietary Met level, whereas linear or quadratic effects of dietary Met level were analyzed by orthogonal polynomials only when the main effect was significant (P < 0.05). A Student’s t-test was used to analyze serum biochemistry, qRT-PCR, and Western Blot. All data were expressed as Mean ± standard deviation.Data were analyzed by the one-way ANOVA with GLM procedure or Student’s P < 0.05), whereas the FCR decreased in linear and quadratic manners (P < 0.05) as dietary Met content increased. Meanwhile, Met intake increased in a linear manner and the ratio of Met intake to ADG (Met intake/ADG) increased in linear and quadratic manners as dietary Met increased.Dietary Met content of basal diet was analyzed to be 0.28% Table , consistP < 0.05) as dietary Met increased. Furthermore, abdominal fat weight and percentage, skin and subcutaneous fat percentage had linear and quadratic declines (P < 0.05) in response to increasing dietary Met. However, dressing percentage was not affected (P > 0.05) by dietary Met supplementation.A basal diet without Met supplementation had negative effects on carcass traits of growing ducks Table , althougThe Met requirements of growing Pekin ducks were estimated by broken-line regression models Table . DietaryP < 0.05), and lower serum TCHO and LDLC concentrations (P < 0.05) compared to birds in the Met-A group , and LDH content was increased (P = 0.05) in the Met-D group.Ducks fed a Met-deficient diet had greater TG and NEFA , and a decrease in cell count (P < 0.05) of abdominal adipocytes from Pekin ducks fed a Met-deficient diet , including 56 up-regulated proteins and 117 down-regulated proteins, after comparing relative abundance of proteins in livers of Pekin ducks fed Met-D and Met-A diets , glycolysis/gluconeogenesis (P = 4.36E-8), fatty acid metabolism (P = 4.86E-6), tricarboxylic acid cycle , pyruvate metabolism (P = 3.64E-5), and cysteine and Met metabolism (P = 0.005). Furthermore, PPAR signaling pathway closely related to lipid metabolism was enriched (P = 5.0E-3). Since lipid metabolism and energy generation were mainly impacted by dietary Met deficiency, differentially expressed proteins related to both above-mentioned processes were classified into 6 categories that were associated with fatty acid transport, fatty acid oxidation, electron transport chain, TCA cycle, glycolysis/gluconeogenesis, and ketoplasia processes, respectively , fatty acid transport protein 5 , albumin , long-chain acyl-CoA dehydrogenase , and long-chain acyl-CoA synthase 5  were diminished, whereas lactate dehydrogenase A  was enhanced in liver of Pekin ducks fed a Met-deficient diet, which suggested that the majority of key proteins had similar expression patterns at both transcriptional and protein levels , ACADM (P < 0.001) and ALB (P < 0.01) were diminished, whereas fatty acid binding protein1  and LDH (P < 0.01) were enhanced in Pekin ducks fed a Met- deficient diet, consistent with the results of iTRAQ proteomics  and adipose triglyceride lipase  mRNA expression , hormone-sensitive lipase , phosphorylated HSL at Ser563 , and the ratio of p-HSL-S563 to HSL  were all decreased in abdominal fat in ducks fed a Met-deficient diet  compared to the Met-adequate group (200 μmol/L)  when lower Met supplementation  were added to DMEM medium  were decreased (/L) Fig. a. Equallium Fig. b. These As Met is considered the first limiting amino acid in corn-soybean meal diets for ducks, crystalline Met sources, e,g. DL-Met and L-Met are routinely used as supplements to meet requirements , 32. In Carcass traits have been considered crucial parameters to evaluate dietary amino acid status , 32, 37,L-FABP mRNA expression by qRT-PCR was discrepant (no difference between Met-D and Met-A groups), which suggested that dietary Met regulated hepatic L-FABP expression at the translational level. By analogy, in previous studies, FABP3 (H-FABP) expression was translationally rather than transcriptionally regulated in skeletal muscle of finishing pigs [Dietary Met has critical roles in protein and lipid metabolism in ducks. In the present study, the relationship between dietary Met level and lipid metabolism, and mechanisms of fat deposition caused by dietary Met deficiency were explored. Dietary Met deficiency increased of yield of abdominal and subcutaneous fat Table , accompaing pigs , 49. As LPL mRNA expression in abdominal fat was significantly decreased in Pekin ducks fed a Met-D diet (Fig. Fat in animals is mainly derived from intestinal absorption and fat synthesis. However, in poultry, fat is synthesized mainly in liver  and traniet Fig. , accountiet Fig. , which dPPARα could be largely expressed in liver; high expression contributes to decreased fat deposition and increased fatty acid oxidation and glycogen synthesis [PPARα in the nucleus of primary hepatocytes [PPARα [PPARα mRNA expression was diminished (PPARα mRNA activated by fatty acids in the liver of Met-D ducks.ynthesis . In fibrynthesis ; therefoynthesis . In addiatocytes , which ms [PPARα . In our minished , whereasminished . TherefoHepatic proteomics analysis revealed that key proteins involved in fatty acid oxidation, electron transport chain, TCA cycle, glycolysis/gluconeogenesis, and ketoplasia processes were impaired in Met-D ducks Table , which pIn the present study, dietary Met deficiency resulted in growth depression and excess fat deposition in Pekin ducks. Dietary Met deficiency affected gene and protein expressions associated with lipid metabolism and fatty acid transportation. The down-regulated genes and proteins related to lipid metabolism caused insufficient ATP production and stunted growth of Pekin ducks. Additionally, decreased expressions of ALB in liver and lipolytic genes and proteins in abdominal fat may have impaired of fatty acid transportation and further caused excessive fat deposition. We concluded that dietary Met deficiency stunts growth and increases fat deposition that might be related to suppression of fatty acid transportation and hepatic catabolism in Pekin ducks. Therefore, the present study provided new evidence regarding effects of dietary Met status on regulation of lipid metabolism in Pekin ducks.Additional file 1: Table S1. Sequences of primers for RT-qPCR. Table S2. Methionine requirements of Pekin ducks from 15 to 42 days of age based on linear broken-line models.Additional file 2: Table S3. Differentially expressed proteins in livers of Pekin ducks at 42 days of age induced by dietary methionine deficiency. Table S4. The KEGG signal pathway of differentially expressed proteinsAdditional file 3: Fig. S1. Effects of dietary methionine deficiency on hepatic lipid deposition in Pekin ducks at 42 days of age. Fig. S2. Effects of dietary methionine deficiency on PPAR genes expression in liver and abdominal fat of Pekin ducks at 42 days of age.


Antibiotics have been the bedrock of modern medical care, particularly bacterial infections. However, globally, antimicrobial resistance has become a well-recognized public health threat in recent years, and interventions to reduce its burden have been launched worldwide.The present study evaluated antibiotic utilization in both hospitalized patients and outpatients in a University Hospital in Nigeria.In a 3 year retrospective study between January 2017 and December 2019, 246 case files of patients were selected for the study based on inclusion and exclusion criteria. In addition, the antibiotic consumption rate for hospitalized and outpatients was determined.P values for the years were 0.019, 0.195 and 0.001 for 2017, 2018 and 2019, respectively.The total antibiotic consumption for hospitalized patients in this study was 260.9 DDD/100 bed-days, while the outpatient department’s patients were 72.3 DDD/1000 inhabitants per day. Peptic ulcer disease was the most frequent indication for antibiotic use for outpatients, with the fluoroquinolones and macrolides being the most prescribed antibiotic class and antibiotic class with the highest DDD, respectively. The most frequent indication for antibiotic use for hospitalized patients was chronic kidney diseases, with the fluoroquinolones and second-generation cephalosporins being the most prescribed antibiotic class and antibiotic class with the highest DDD, respectively. DDD per 100 bed-days and DDD per 1000 patient-days were highest in 2018. The Our findings revealed irrationality in antibiotic use. Therefore, antimicrobial stewardship programmes should be implemented. The intervention is vital in developing countries, which usually have a combination of poor antimicrobial prescribing practices, unregulated over-the-counter sale of antibiotics and increasing rates of antimicrobial resistance.6To combat the marked rise in antimicrobial resistance, WHO advocates the adoption of antimicrobial stewardship by healthcare providers to check and reduce the burden of antibiotic resistance.7 However, most studies on antibiotic utilization focused on antibiotic use in specific departments or compared antibiotic utilization between hospitals.Due to the change in prescribing patterns and in the face of newer drug formulations and ever-emerging antibiotic resistance, it is pertinent that data be obtained on antibiotic utilization in different geopolitical zones of the country. In addition, accurate information about prescribing patterns in hospitals is valuable in improving the quality of antimicrobial utilization.It is necessary to carry out a retrospective study on how antibiotics are used in our tertiary hospitals using the ATC/DDD methodology as a basis of comparison and subsequently use the findings to develop and implement tailored strategies and interventions towards promoting appropriate use of antimicrobials in the future.This study aims to evaluate the utilization of antibiotics in hospitalized patients and patients visiting the general outpatient department of Lagos University Teaching Hospital using a retrospective study.A 3 year retrospective study from January 2017 to December 2019 focused on antibiotic utilization in the hospitalized patients and outpatients at Lagos University Teaching Hospital, Southwestern Nigeria.This survey also includes descriptive variables of the ward- and patient-level data to describe the extent of antibiotic use in the hospital.The method used for reviewing the medical records was primarily active search of presence of antibiotics in the records of patients meeting the inclusion criteria. Th system for medical recording used in the hospital was paper based. The records were reviewed by the authors K.F.S. and F.A.O. The process was verified by senior officials of the Health Records Department, Lagos University Teaching Hospital.8 The Z value of 1.96 and 5% level of significance was used to calculate the sample size using the formula below:The reported prevalence of antibiotic use in both inpatient and outpatient settings is more than 80% in Kenya.N = 246 patients.Where; p = prevalence; q = (1 − p); d = level of significance. Hence, A total number of 246 case notes and medical records of patients who either visited the general outpatient department or were hospitalized and met the inclusion criteria were reviewed.Antibiotics which were classified as J01 category (antibiotics for systemic use) under the ATC classification system were included in this study. The number of antibiotics dispensed for 36 consecutive months was consulted, and data were extracted from medical records using a table with the antibiotic’s name, strength, amount dispensed and date dispensed.Adults admitted to the hospital and those visiting the outpatient department for both genders on antibiotic therapy in the medicine department were included.Surgical patients, pregnant and nursing mothers, patients on chemotherapy, paediatric patients, emergency cases and short-stay cases were excluded.Potential datasets for the study shall include the following: (i) details of the wards for data collection; and (ii) dose, frequency, route of administration and length of treatment of all antibiotics prescribed for each patient.The number of DDDs was calculated by first converting the total amount of antibiotics dispensed into grams divided by the standard WHO DDD value given in grams. For example, DDD/100 bed-days is given by dividing the number of DDDs by patient-days and multiplying by 100.2 was used to evaluate categorical associations (P < 0.05 was considered significant).Data analysis was undertaken using Microsoft Excel 2010 and statistical software SPSS version 23. The analysis of variance (ANOVA) was used for continuous variables as appropriate, while χEthical clearance to carry out the study was obtained from the Ethics Committee of the Lagos University Teaching hospital (CMUL HREC), Idi-araba, Lagos, Nigeria, with an assigned number: ADM/DCST/HREC/APP/3970.Of the 246 patients selected, 60 were hospitalized patients and 186 were patients who visited the general outpatient department. For outpatients, 124 were female and 62 were male, with the IQR of antibiotics per prescription being 1–2 antibiotics.For patients admitted, 35 were female and 25 were male. The median age for outpatients was 43 years, while that of hospitalized patients was 45 years. At least one person received a prescription of six antibiotics during the entirety of their stay. Eight people received only one antibiotic, 15 patients received two antibiotics, 11 patients received three antibiotics, 18 patients received four antibiotics and 7 received five antibiotics. The IQR of antibiotics per prescription for the hospitalized patients is in the range of 2–4 , followed by bilateral vestibular failure (n = 13). Five persons were treated with antibiotics for back pain with cholelithiasis, malaria, gastroenteritis and gluteal ulcer, having the same number of hospitalized patients on antibiotics (n = 4)  received amoxicillin and clavulanic acid combination drugs, followed by ciprofloxacin (n = 34), amoxicillin (n = 28), clarithromycin (n = 26), metronidazole (n = 25), levofloxacin (n = 17), azithromycin (n = 15) and cefuroxime (n = 12) followed by the other antibiotics as shown in Table Findings revealed the majority of the patients n = 6 receiven = 27) received metronidazole in the course of their stay, followed by ceftriaxone (n = 24); 24 patients received levofloxacin infusion with 22 patients discharged with oral levofloxacin as their take-home drugs. In addition, amoxicillin and the clavulanic acid combination were received by 22 patients, with 19 patients taking oral amoxicillin and clavulanic acid combination as their take-home drugs  and outpatients (n = 57). Penicillin and β-lactamase inhibitor belonging to the ATC code, J01CR, was next in both study groups with (n = 42) and (n = 52) for hospitalized patients and patients visiting the outpatient department, respectively. This was followed by the third-generation cephalosporins (n = 30) with the ATC code J01DD for hospitalized patients and macrolides (n = 41) for the general outpatient department  was prescribed mainly by the general outpatient department as part of combination therapy for gastritis and peptic ulcer disease. This treatment regimen is in line with Nigeria’s national standard treatment guidelines. According to Egwuenu et al.,9 there is a high prevalence of peptic ulcer disease in Nigeria, and this is due to lifestyle habits such as smoking and excessive alcohol intake, which contributes to the corrosion of the gut lining.Peptic ulcer disease was the most frequent cause of hospital visits for patients who visited the outpatient department Table . Clarithet al. in 2020.10 Therefore, these groups need to make adequate dose and dosing regimen adjustments. The doses must be modified such that adequate therapeutic concentrations reach the kidney and, subsequently, the urine.11 Failure of these enhances the possibility of resistance emerging to the antibiotics used. Therefore, therapeutic drug monitoring is crucial for these groups.Our findings also detected irrational prescribing of antibiotics in hospitalized patients. Instances such as using antibiotics for patients admitted for chronic kidney diseases, bilateral ventricular failure, nephrotic syndromes and malaria all indicate irrationality Table . The natStreptococcus pneumoniae, increasing their risk of mortality and morbidity. This is due to the loss of immune proteins, including immunoglobulin G (IgG) and alternative pathway complement components.12 This may be a suitable explanation of why antibiotics were used for these patients observed in this study. Antibiotics can be used to treat malaria, specifically co-trimoxazoles, macrolides, tetracyclines, fluoroquinolones and nalidixic acid derivatives. However, their uses are limited to severe and complicated malaria or in special groups with uncomplicated malaria.13 The class of antibiotics used were the third-generation cephalosporins, and there is no indication for their use clinically for this purpose.Patients with nephrotic syndrome are at high risk of infection such as sepsis caused by A look at the indications for antibiotic use for outpatients also revealed several cases of irrational prescribing, although not as prominent as for hospitalized patients.5 WHO went further to classify the antibiotics as prioritization factors 2 and 3. Prioritization factor 2 (P2) due to its high frequency of use of the antimicrobial class for any indication in human medicine or certain high-risk groups, since users may favour the selection of resistance and prioritization factor 3 (P3) due to the antimicrobial being used to treat infections in people for which there is already extensive evidence of transmission of resistant bacteria from non-human sources. WHO has also classified the antibiotic using the AWaRe classification under the Access group.14Amoxicillin and clavulanic acid combination drugs were the most prescribed by the outpatient department. This is due to the ability of the antibiotic to treat a variety of infections. WHO has classified it a critically important antimicrobial for human use.Clostridioides (Clostridium) difficile, a bacteria transmitted from an infected patient to others through healthcare staff via improperly cleansed hands, is one of the causes of these infections.15Bacteria, viruses or fungi can cause nosocomial infections. For example, 14 is used to treat anaerobic infections, including those caused by Bacteroides and Clostridium.16 Metronidazole is also an antiprotozoal agent, and it is active against several protozoa, including Giardia, Entamoeba histolytica and Trichomonas vaginalis.16 Fluoroquinolones possess a broad spectrum of activity against many organisms, including aerobic Gram-negatives, such as Enterobacteriaceae, Haemophilus spp., Neisseria spp. and Moraxella catarrhalis.17 The effectiveness of metronidazole and levofloxacin against these organisms made them the right drug of choice for treating nosocomial infections, as observed in our study. However, levofloxacin has been classified by WHO under the Watch group, which means although it is included in the essential drugs list, it should be reserved for strictly MDR organisms.14Metronidazole, also classified by WHO into the Access group,18 and Iliyasu et al., 201519 on inpatient antibiotics prescription in Nigeria shows that less than 60% of patients received antibiotics for a bacterial infection. The most frequently prescribed antibiotic drug classes, as observed in their studies, were imidazole derivatives, cephalosporins, fluoroquinolones and β-lactams.18 The results of this study were no exception. This study also observed low generic prescription of antibiotics and high use of parenteral formulations as with previous studies. A finding supported by Iliyasu et al. in 2015.19Our result compared with studies by Abubakar, 202020 Therefore, it should be reduced where possible.Generic prescription is necessary to reduce out-of-pocket expenditure, especially in Nigeria, where the patients bear the cost of medication. The use of parenteral formulations is costly and increases the risk of infection.19 Lack of prescribers’ trust in generic substitutes and presumed therapeutic failure has been shown to influence generic prescribing.21Most antibiotics prescribed for both study groups were in brand names and not generic names; this finding agrees with similar studies.22 Sadly, many developing countries, including Nigeria, are yet to implement such measures, hence a rise in bacterial resistance.Antimicrobial resistance is a universal problem and a disaster waiting to happen; it is necessary to prevent antimicrobial resistance by methods such as rational prescription through institutionalized prescription audits or drug utilization studies.23The flow of antimicrobial resistance from hospitals into communities and vice versa makes it challenging to differentiate between community-acquired MDR infectious organisms and hospital-acquired ones.24 the DDD/100 bed-days for this study was higher. Our findings are slightly similar to studies by Sözen et al. in Turkey25 and Amaha et al. in Asmara, Eritrea.26 However, it was inconsistent with a study by Gutema et al.,10 who conducted a study in three medical wards of one of the largest tertiary hospitals in Ethiopia and reported that their antibiotic consumption was 91.8 DDD/100 bed-days. The higher figure obtained in this study reflects the large number of antibiotics that are being used in our hospitals.The total antibiotic consumption for hospitalized patients in this study was 260.9 DDD/100 bed-days , followed by second-generation cephalosporins (1.83) for patients visiting the outpatient department, while for hospitalized patients, second-generation cephalosporins were highest (17.5), followed closely by macrolides.27 A multidisciplinary approach can improve the quality of antibiotic prescription, reducing cost and curbing infection/resistance.28 Interventions such as setting up antimicrobial stewardship committees; continuing in-service face-to-face medical education as a licensure requirement; and supervision, audit, and feedback systems effectively promote the rational use of antibiotics.20Most prescribers understand that overprescribing antibiotics may lead to antibiotic resistance; however, they admit to the overuse of antibiotics and the prescription of antibiotics in the absence of bacterial infection.According to our study, the antibiotic consumption rate for people visiting the outpatient department was highest in 2018 (Figure P values for antibiotic utilization for the 3 years indicated statistically significant differences between the antibiotic utilization in the years 2017 and 2019, but that there is no statistically significant difference in the antibiotic utilization for the year 2018 (Figure The We conclude that indiscriminate use of antibiotics is still being observed to be ongoing in the environment; not only are antibiotics misused, abused and overused, caution is not being used in the prescribing and use of these molecules. Instead, more antimicrobial molecules are being combined to tackle resistance without ensuring proper utilization of various programmes that help curb the emergence of resistance, such as antimicrobial stewardship programmes and the use of the national standard treatment guidelines.A possible recommendation for good antibiotic stewardship includes the adoption of a pre-prescription approach, that is, antibiotics should not be dispensed without a prescription and should not be used in the hospital without informing the antibiotics steward or the infection specialist.


Misuse and inappropriate disposal of antibiotics as identified may lead to a higher risk of antibiotic resistance, increasing the disease burden in the informal settlements.The use and abuse of antibiotics are directly related to the development of drug resistance, a global public health problem. Whereas the majority of research focus is on the use and misuse of antibiotics in drug resistance development, little is known about improper disposal, as a source of contamination in the environment that includes groundwater, especially in informal settlements. This study sought to determine antibiotic use and disposal in informal settlements in Kisumu, Kenya. A random cross-sectional sample of 447 households in selected informal settlements of Kisumu, Kenya was studied. A structured questionnaire was issued to persons heading households. The prevalence of antibiotic use was 43% (n = 193). Among these people, 74% (n = 144) had consulted a health worker in a healthcare facility for a prescription. Respondents did not always complete doses but kept the remainder for the next time they would become ill (54%). About 32% disposed of the remainder of the antibiotics in pit latrines and compost pits (10%) while 4% disposed through burning. Antibiotic use was fairly high despite a low level of awareness of the health effects of consuming water contaminated with antibiotics (35%) (n = 156);  Bacterial infections are a leading cause of morbidity and mortality around the world. Antibiotics continue to be a low-cost solution to current human and animal health problems both in treatment and prophylaxis ,2. They Antibiotic consumption increased by 39% globally between 2000 and 2015 ,11,12, bAntibiotic use has been prevalent in hospital settings, where treatment guidelines recommend optimal antibiotic use in order to reduce the threat of antibiotic resistance, which worsens the burden of infectious diseases ,13. AntiThe World Health Organization reported the prevalence of antibiotic consumption in defined daily dosages for four Sub-Saharan African countries: the Republic of Tanzania, Burkina Faso, Cote d’Ivoire, and Burundi, with defined daily dosages of 27.3, 13.8, 10.7, and 4.4 per 1000 inhabitants per day, respectively . HoweverAntibiotics are used for the treatment of infection and for prophylaxis among different populations , especiaAntibiotic misuse has been categorized as both community- and healthcare-provider-driven owing to a lack of understanding and awareness of the dangers of antibiotic abuse in the community, availability of antibiotics without a prescription, and consumption of leftover medications, even though prescibers and dispensers were found to have adequate knowledge on antibiotic use ,21. The Environmental contamination with antibiotics has been linked to a number of sources, including pit latrines, sewage, wastewater, and animal and hospital waste disposal ,26,27,28An increased urban population has resulted in the expansion of informal settlements, which has a negative influence on water supplies . ResidenSince there exists a complex interaction between humans, animals, and the environment , health 2, of which roughly 567 km2 is water. The county is located on the beaches of Lake Victoria, the world’s third-biggest freshwater lake, which also borders Kenya, Uganda, and Tanzania. The research sites are located in the Kisumu East and Kisumu Central sub-counties. There are eight informal settlements in the county, five of which were studied: Obunga, Manyatta A, Manyatta B, Nyalenda A, and Nyalenda B.The study was conducted in Kisumu County, which is located in Kenya’s western area, 350 km from the capital city of Nairobi, at longitudes 33°20’ E and latitudes 0°20’ S and 0°50’ S [The population density of the informal settlements is projected to be 567,983 , with anA cross-section of households in the chosen informal settlements was studied in September 2019. The AF-RIWATSAN project site, which included a number of components, was purposively selected . Prior tA structured questionnaire was administered by trained interviewers using the Swahili language which was understood by the respondents. To verify that the translation from English to Swahili was not lost, the validity of the questions was maintained, and the possibility for introducing information bias was reduced, the questionnaire was piloted among residents of a different informal community within Kisumu. Groundwater use and the use of antibiotics were outcome variables. Sociodemographic traits, the source of the antibiotics, the completion of the antibiotic dose, and the disposal of leftover drugs were all predictor variables. Version 20 of IBM* SPSS* Statistics was used to enter the data, and also conduct descriptive analysis and cross tabulations whereas STATA 14 was used for logistic regression analysis. Continuous data were summarized using descriptive statistics, whilst associations and linkages in categorical variables were evaluated using chi-square tests. To find predictors of antibiotic use, logistic regression analysis was utilized.Ethical clearance to conduct this research was obtained from the Health Research Ethics Committee of the University of the Witwatersrand, Johannesburg South Africa (HREC. Protocol Number M190412); the Kenyatta National Hospital and University of Nairobi Ethics and Research Committee (KNH/UoN-ERC. Ref. No. P71910/2018); and the National Commission for Science and Technology and Innovation. Ref No. NACOSTI/P/19/3232/28732). To protect privacy, study areas were coded. In the five informal communities, 447 households were investigated. Of these, 75% (n = 337) of responders were female, whereas 25% (n = 110) were male. Antibiotic use in the selected households during the previous month from the day of the interview was reported to be 43%. (193). Among individuals who consumed antibiotics, 70% (n = 137) reported getting the antibiotic through a prescription, whereas the rest did not consult a doctor for the antibiotic prescription. Further examination in the households that reported self-medication revealed that antibiotics were either used based on previous experience (76%) or on the advice of friends (26%). p = 0.003) of households who reported using antibiotics were aware of the health risks of drinking antibiotic-contaminated water. p < 0.000) among informal settlements. Additionally, the level of awareness of the health implications of drinking antibiotic-contaminated water was evaluated and it was discovered that only 35% . Participants aged 45 years and older showed a higher likelihood of using antibiotics compared to younger participants . In terms of geographical location, the situation differs among different settlements, with the use of antibiotics decreasing in only one informal settlement  (odds ratio =0.42). z = 1.07, SEM = 1.726156, the observations were judged to be within one standard deviation of the mean.Furthermore, to comprehend the amount of health consciousness The odds of employing antibiotics were calculated using a 95% confidence interval, and no statistically significant difference was observed . Female Proper disposal of leftover antibiotics is regarded as a major concern and has been linked to the development of antibiotic resistance. In this study, all participants were interviewed about the various methods they disposed of leftover medicines. Respondents disposed of antibiotics in a variety of methods, including 51.6% (n = 16) in pit latrines, 16.1% (n = 5) in compost pits, and 6.5% (n = 2) by burning. However, the majority of respondents  did not discard the unfinished antibiotics but preserved them for future use . Antibiop = 0.000), with the majority of HIV-positive respondents completing their antibiotic dose and just a tiny fraction of HIV-negative respondents not completing their antibiotic dose. There was also a difference among the informal settlements (p = 0.001), with a lower proportion of responders in Nyalenda B completing their antibiotic doses than in the other settlements. In terms of age group variations, it was discovered that antibiotic completion rose with age, although there were no significant differences in antibiotic dose completion across the various age groups  and 70% (exit) . AntibioSelf-medication with antibiotics is a major contributor to the development of drug resistance  and is t3 of groundwater was extracted but was used for other domestic purposes than drinking and cooking in the Kisumu informal settlements [An estimated 60% of Kisumu inhabitants live in informal settlements, where they face deficiencies such as a lack of clean water and basic sanitation . Groundwtlements . Anothertlements .The improper disposal of unused, stored, and expired antibiotics is of major concern , as userPeople with weakened immune systems use antibiotics the most to combat opportunistic infections. In this study, the self-reported HIV status was 4.7%, with a higher likelihood of utilizing antibiotics and completing their antibiotic dosage. This study’s location is in a region in Kenya where the HIV prevalence is greater than the national prevalence, which has been reported to be between 16.3%  and 17.5Despite attempts to raise awareness about antibiotic usage and resistance through worldwide annual events, consumers still lack reliable knowledge about proper antibiotic use. To reduce misuse and abuse, it is critically important to design methods that assure measurement of antibiotic consumption by countries and use thereof at individual and household levels.More research on prescribers’ and users’ knowledge of the amount of use and health impacts as a result of antibiotic exposure in the environment owing to inadequate disposal, should be conducted. It is also necessary to devote time to improving understanding through surveillance and study. These measures will reduce the disease burden and promote well-being, particularly in informal settlements, which have similar cross-cutting inequities.Antibiotic disposal practices in informal communities have been found to pollute the environment, including groundwater; the result being environmentally induced antibiotic resistance. Antibiotic use reduction and correct disposal are strategies for combating antibiotic resistance in groundwater. Governments, as well as other relevant organizations and stakeholders, should prioritize the provision of safe water for all, particularly disadvantaged residents of informal settlements. Proper disposal techniques must be prioritized, and hence raising awareness about these among prescribers, providers, and antibiotic consumers should be a top concern.Since this was an academic study with restricted resources, a large sample could not be studied. However, the study’s findings are applicable to and can be generalized to similar settings, because informal settlements have traits that are not necessarily unique to a particular geographical area. To look for differences between informal settlements, a different study approach than descriptive is recommended. For reason that the study was dependent on the response given, the actual HIV status of the respondents may not have been captured. A study targeting HIV patients at the clinic could be a better measure of the burden of disease among the informal settlements, and thus more concrete conclusions could be made on antibiotic use among HIV patients.In Kenya, there is little information on antibiotic use at the household level. This study discovered that antibiotic use is significantly high, with disposal procedures similar to those known to contribute to environmental contamination, including groundwater. There was antibiotic misuse and abuse, as well as improper disposal, along with a lack of awareness of the health risks of antibiotic exposure in the environment, such as drinking antibiotic-contaminated water. The majority of informal settlement dwellers rely on groundwater to fulfill their water demands. As a result, there is a need for studies to increase surveillance of antibiotic usage and disposal. Additionally, governments and other relevant organizations must strengthen their commitment to groundwater resource management in order to offer sustainable universal water distribution free from the inclusion of pollutants such as antibiotics, particularly among disadvantaged communities in informal settlements.


Conclusion. The synergistic effect of carbon nanotubes and steel fibers is more conducive in complementing each other's advantages and improving the performance of concrete.In order to solve the problems of carbon nanotubes, steel fibers, and carbon nanotubes + steel fibers on the compressive strength and impact resistance of concrete, the author proposes a test method for the frost resistance and corrosion resistance of carbon nanofiber bridge concrete. Using carbon nanotubes and steel fibers as reinforcing materials, the effects of carbon nanotubes and steel fibers on the compressive strength and impact resistance of concrete were studied. Experimental results show that incorporating carbon nanotubes and steel fibers can improve the compressive strength of concrete. Compared with the single-doped carbon nanotubes, the single-doped steel fiber has a greater effect on the improvement of the impact resistance of the concrete. The toughness and ductility of carbon nanotubes and steel fiber reinforced concrete are improved again compared with that of single steel fiber reinforced concrete. The effect of adding 1% steel fiber +0.30% carbon nanotubes is the most significant in enhancing the performance of concrete.  The durability of concrete bridges directly affects the safety and service life of long-term service bridges, which is one of the hotspots in bridge research. Due to the complex use environment of bridges, the influence of external environments  and loads will lead to the degradation of the service performance of concrete bridges , 2. The The rapid development of China's highway industry, the rapid increase in highway traffic mileage, and the rapid increase in the number of highway bridges and culverts, while the huge number of highway bridges and culverts bring fresh vitality to economic development, the frequent occurrence of diseases of highway bridges and culverts has become a huge obstacle to the development of highway transportation , 4. The Cement has a long history of application in the field of construction and has been widely used due to its low cost, wide source, and convenient production. It is currently the most widely used building material. However, the tensile strength and shear strength of cement-based materials are much lower than their compressive strength, and they are prone to cracks and spalling when used alone. It is often used in conjunction with steel bars and concrete to increase the performance and service life of cement-based materials, but the addition of steel bars can only inhibit the development of macroscopic cracks. With the continuous development of science and technology and the continuous improvement of use requirements, cement-based materials are developing in the direction of green, high strength, and high durability , 6.In the concrete bridge structure, the load on the components in different parts and a difference in the environment will lead to the difference in the durability of the bridge concrete structure. Defus et al. studied the durability design method of concrete members and proposed a hierarchical modular division method of concrete structures. The individual life design of each component makes the durability of each level meet the requirements, so that the overall design of the concrete structure can be optimized, reducing the construction, maintenance costs of bridges, and prolonging the life of bridge structures . Doyle ePavements and bridges will encounter various dynamic loads during their service life, such as traffic loads and currents, ship impact loads, which will bring severe tests on the service life of concrete. The instantaneous pressure generated by the impact load is often very large, and the concrete is prone to damage and cracks under the action of this load, and the structural safety hazard is relatively large. When there is a defect in the concrete, stress concentration will occur at the tip of the crack, and the microcrack will develop rapidly, so that the concrete will be damaged rapidly. Therefore, the impact load has been widely considered and studied. Studies have shown that adding fibers to concrete can improve its performance , 12.Furthermore, carbon nanotubes have stable chemical properties, high compressive strength, high elastic modulus, strong corrosion resistance, and good electrical conductivity and have high scientific research value. Moreover, carbon nanotubes, as nanoscale materials, have an inhibitory effect on the expansion of microcracks; steel fibers have good bonding properties, which can change the way of load transmission, and the two have a good synergistic effect. Therefore, the authors used carbon nanotubes and steel fibers as reinforcement materials. The effects of carbon nanotubes and steel fibers on the compressive strength and impact resistance of concrete were studied.3; sand: the fineness modulus is 2.6, which meets the construction class II sand standard; steel fiber: shear corrugated steel fiber, diameter 0.8∼1.0 mm, length 32 mm, tensile strength 620 MPa, aspect ratio 30; carbon nanotubes: multiwalled carbon nanotubes, the main performance parameters are shown in Cement: P·O 42.5 grade cement; coarse aggregate: 5–20 mm continuously graded crushed stone, density 2732 kg/mC30 concrete is configured according to the design rules of ordinary concrete mix proportion. According to the existing research, at the same time because the U-shaped specimen was used in this test, the section size is small, and the steel fiber volume ratio is not easy to disperse, so the final determination of the steel fiber content is 1%. The specific mix ratio of the test is shown in Before the preparation of the specimens, the surface of carbon nanotubes was efficiently grafted and polymerized by a SY-DT02 rotating hub low-temperature plasma treatment apparatus produced by a company that makes carbon nanotubes more hydrophilic. The stirring process of each group of specimens is shown in The slump test was carried out with reference to the standard of the performance test method for ordinary concrete mixtures.During the test, it was found that the workability of each group of specimens was good, and the slump was basically in the range of 40∼60 mm. For the single-doped carbon nanotube concrete specimen, with the increase of carbon nanotube content, the slump gradually increases, and when the content is 0.40%, the slump reaches 60 mm. For single-mixed steel fiber concrete, the slump is about 35 mm, which is much lower than that of plain concrete , 14. ForThe size of the specimen is 100 mm × 100 mm × 100 mm. After the specimen is cured in the curing room for 28 days, it is taken out, and the axial compression test is carried out with a hydraulic press. The force loading control is adopted, and the loading rate is 0.5∼0.8 MPa/s. Record the test data during the test until the specimen is destroyed.The author adopts the drop weight impact test method. The mass of the impact ball is 0.8 kg, and the drop height is 40 cm. During the test, the impact ball falls freely along the center line of the specimen, and the specimen is subjected to impact load. After each impact load, check whether the specimen is cracked or damaged, and record the number of impacts N1 for initial cracking and N2 for failure.The criterion for initial cracking is that the concrete specimen be smooth and crack-free up to the first microcracks after impact. During the test, use a magnifying glass to observe whether cracks appear after each impact in the early stages; the criterion for damage is to start from microcracks and penetrate to the upper surface.According to the research on the measurement method of the impact resistance of cement concrete, the U-shaped concrete specimen was used instead of the cube specimen. At the U-shaped concrete specimen, it is easy to determine the initial cracking position of the specimen when it is impacted. At the same time, the middle of the specimen passes through the arc transition to avoid stress concentration , 16.β of the specimens were calculated according to the formula.The following three points should be paid attention to during the impact: ① The impact load on the U-shaped specimen is concentrated in the cross section of the symmetry axis. ② The bottom is made of a steel base, and the U-shaped specimen is similar to the fixed support to avoid the energy dispersion of the connected objects. ③ Clean the cylinder wall to ensure that the steel balls fall along the cylinder wall without friction and impact directly above the U-shaped specimen. Referring to the failure modes of each group of specimens, the toughness coefficient C and ductility ratio N2,fiber and N2,white are the corresponding impact times when the fiber concrete and plain concrete fail, respectively.In the formula: According to the failure mode of each group of specimens, the compressive strength test results are shown in Compared with group A, the compressive strength of group C1 increased by 2.0%, and the increase was not obvious. This is because when the amount of carbon nanotubes was too small, it was difficult to completely disperse into the whole specimen, and the improvement effect on concrete performance was small. Compared with group A, the compressive strength of group C2, group C3, and group C4 increased by 8.0%, 12.0%, and 8.7%, respectively. That is, with the increase of carbon nanotube content, the overall compressive strength showed a trend of first increasing and then decreasing, and the compressive strength reached its maximum when the dosage was 0.30%. The reason is that carbon nanotubes fill the pores on the one hand, and on the other hand, the evenly distributed carbon nanotubes form a grid system in the concrete, which improves the overall structural performance of the concrete and limits the development of tiny cracks.Compared with group B, the compressive strength of group D1 increased by 4.5%; the compressive strength of group D2 increased by 9.7% compared with group B; the compressive strength of group D3 increased by 10% compared with group B, and the compressive strength of group A increased by 23.7%. The reason is that after the carbon nanotubes are incorporated, different gradation structures are formed, which increases the adhesion between the steel fibers and the concrete, thereby improving the strength. In addition, in group D, although the compressive strength of group D3 was the highest, it was not much different from that of group D2, while group D4 was significantly lower than group D1, group D2, and group D3. This shows that the amount of carbon nanotubes has a reasonable range. When the amount is too large, the carbon nanotubes are prone to agglomeration, which reduces the compressive performance of concrete.β are shown in The toughness coefficient C and the ductility ratio When steel fibers and carbon nanotubes are mixed, the impact times of initial cracking and the impact times of failure are increased compared with the single-doped test group, and the toughness coefficient and ductility ratio are also improved.Within the range of carbon nanotube content of 0.05%–0.30%, the toughness coefficients of D1, D2, and D3 groups were increased by 1.5%, 8.3%, and 13.7%, respectively, compared with group B, indicating that the incorporation of steel fibers and carbon nanotubes reduces the brittleness of the concrete matrix, its plastic characteristics are improved, and the larger the content of carbon nanotubes, the more obvious the increase effect. According to the fiber spacing theory, the greater the number of fibers per unit area, the smaller the spacing, and the better the strengthening and toughening effects of concrete materials. Compared with group B, the increase in the number of impacts of initial cracking in group D is lower than that of failure. According to the theory of fracture mechanics, after the concrete is subjected to impact load, initial cracks occur at the interface between the fiber and the matrix. The carbon nanotubes that intersect with the interface can delay the development of initial cracks, thereby increasing the number of shocks to failure, but the effect of carbon nanotubes on preventing the appearance of initial cracks is not obvious.When the content of carbon nanotubes is 0.40% (D4 group), the toughness coefficient of the D4 group is only 7.54, which is much lower than that of the D3 group and even lower than that of the B group. The main reason is that the cross-sectional size of the U-shaped specimen is smaller, and carbon nanotubes are more likely to agglomerate in it than the cubic specimen, which affects the performance of concrete , 20.Both carbon nanotubes and steel fibers alone can improve the compressive strength and impact resistance of concrete, and the toughness and ductility are also improved to a certain extent, and the optimum content of carbon nanotubes is 0.30%. When the steel fiber and carbon nanotubes are mixed, the impact times of the initial crack of the specimen do not increase significantly compared with that of the single-doped steel fiber test group, but the increase in the damage impact times is relatively large. In addition, mixing carbon nanotubes and steel fibers can significantly improve the compressive strength, impact resistance, toughness, and ductility of concrete, and when the steel fiber content is 1%, the optimal content of carbon nanotubes is 0.30%.In summary, the synergistic effect of carbon nanotubes and steel fibers is more conducive to the complementarity oftheir advantages and improves the performance of concrete.The author proposes to test the antifreezing and anticorrosion performance of carbon nanofiber bridge concrete, both carbon nanotubes and steel fibers alone can improve the compressive strength and impact resistance of concrete, and the toughness and ductility can also be improved to a certain extent, and the optimum content of carbon nanotubes is 0.30%. When the steel fiber and carbon nanotubes are mixed, the impact times of the initial crack of the specimen do not increase significantly compared with that of the single-doped steel fiber test group, but the increase in the damage impact times is relatively large. In addition, mixing carbon nanotubes and steel fibers can significantly improve the compressive strength, impact resistance, toughness, and ductility of concrete, and when the steel fiber content is 1%, the optimal content of carbon nanotubes is 0.30%.


To find the anthropometric references that define the optimal body composition, it is essential to first find an optimal body composition for one’s physical preparation. The objective of this study is to describe the anthropometric characteristics of 27 Spanish CrossFit® athletes, 19 males aged 39 years old (24–44) and 8 females aged 28 years old (23–40), and how these characteristics influenced their performance. The athletes performed the Fran, Cindy, and Kelly workouts, establishing minimum marks, and the CrossFit Total workout to assess maximum strength. Significant differences were not found in time and repetitions between sexes in skill training, although there was a positive correlation r = 0.876 (p < 0.001) between muscle mass and the Total CrossFit result. We can conclude that the CrossFit® athlete has a low amount of fat mass and a small relative size, which is an advantage when training with bodyweight exercises, and a high muscle mass that provide benefits when strength training. In addition, despite executing movements from a multitude of disciplines, the physical demands for lifting heavy loads resulted in the anthropometric values of athletes being more similar to elite weightlifting athletes than in other sports.CrossFit Since iin Spain .® workouts, called Workout of the Day (WOD), are extremely varied and can focus on one of the sports modalities that CrossFit® is composed of or be a compendium of them. Thus, an athlete can perform both a WOD with their body weight that lasts no more than 5 min [CrossFitan 5 min  and anotan 5 min . Therefo®, there is a single weight category, and all athletes have to perform the same exercises with the same loads regardless of their size, so it is not easy to find an ideal body composition (BC) as excess fat mass, or even muscle mass, could weigh you down in gymnastic movements, although they could be an advantage in heavy lifting of weightlifting [In competition, unlike in most sports, the athletes do not know which tests they are going to face until a few hours or minutes before it. Therefore, training, rest, feeding, and hydration in the days before and during the competition cannot be oriented towards specific parameters, as it is often found with athletes of more specific sports such as endurance . Thus, ttlifting .Anthropometry is one of the tools used to estimate BC. It is a science that studies size, shape, proportionality, composition, biological maturation, and bodily function in order to understand the processes involved in growth, exercise, nutrition, and sports performance . Today t®, there are no studies that describe their athletes anthropometrically or that refer to BC or somatotype [Despite the growing interest of the sports population for CrossFitmatotype , and thematotype , artistimatotype  or weighmatotype ,16.®.It is considered that establishing anthropometric references that define the body composition of the athletes with the best marks is essential for the physical preparation of elite athletes ; however® athletes from southeast Spain and how these parameters influence the performance of this sport. The main hypothesis of this research is that the studied sample will show differences according to sex and that CrossFit® athletes will have a low amount of fat mass and a high muscle mass.The aim of this study is to describe the anthropometric characteristics, body composition, and somatotypes of CrossFit® athletes from southeast Spain to find a correlation with their results in official WODs.An observational and descriptive pilot study of the anthropometric characteristics, body composition, and somatotype of CrossFit®. In addition, the sample performs an average of 3 training per week. All athletes participated voluntarily, being informed of the entire process and methodology used, providing their consent in writing in accordance with the Declaration of Helsinki 2013 and the Ethics Committee from the University of Alicante (File UA-2020–03–29).The study population was selected through non-probabilistic convenience sampling. The sample was made up of 19 men and 10 women, with an age range between 23 and 44 years, with high physical and technical levels, and an experience of >2 years in the practice of CrossFitFor the selection of athletes, we counted different official boxes that agreed to participate in the study. Athletes who met the inclusion criteria were recruited through the boxes and voluntarily accepted to participate.® boxes, having the possibility of repeating some or all of the WODs, and only delivering the best mark for each of them at the end. Both the training and the anthropometric measurements were carried out in the months of February and March 2020.The training sessions were carried out by the participating athletes at official CrossFit® did not have official regional or national competitions with which to establish the minimum requirements of physical performance and experience in athletes, we decided to use official WODs, also known as Benchmark Workouts [®, both for technical execution and load (Rx). Training sessions were held on Mondays for four consecutive weeks as part of the participants’ pit schedule. This day was chosen since the schedules of these boxes consist of five pieces of training that take place from Monday to Friday, and in this way, it was guaranteed that the athlete carried out the training after having rested two days and not another day of the week when accumulated fatigue would interfere with their performance. For the selection of the official WODs, and considering the objective of this study, WODs chosen did not have high technical demand, and the physical abilities of the athletes were evaluated based on their body composition in addition to their skills or experience. The WODs were selected to cover the full range of CrossFit® 100 workouts. These were: “Kipping Fran” [® through a CrossFit® certified trainer and set the maximum execution times that would ensure an advanced physical level of the athletes in the sample. The data obtained were used to carry out the analysis , age, ethnicity, and country of origin.For taking the anthropometric values, the standards and measurement techniques recommended by the ISAK were used. The measurements were taken by an anthropometrist accredited in the ISAK level 2 who worked under the supervision of a level 3 accredited anthropometrist. We took into account the intraobserver technical error of measurement (ETM) indicated by the ISAK (5% for skinfolds and 1% for girths and diameters). Thus, the anthropometric measurements taken were those established by the ISAK  restrictFor the calculation of BC, a four-component system was used through the application of the equations from Lee et al.  for musc® athlete, for both men and women.To calculate the somatotype, the three-component system  proposed by Heath and Carter  was usedThe proportionality of the athletes in the sample was assessed using the Phantom  methodol2), waist-height index (waist girth/height), relative size and acromio-iliac index  [In addition, the sum of the values of the 8 skinfolds, corrected girth of the relaxed arm, corrected girth of the middle thigh, corrected girth of the leg, body mass index (kg/mbreadth) ,17,26 we®, to ensure that they were performed in compliance with the standards mentioned.The number of times, repetitions performed, and weights used in the WODs were recorded in a sheet, which indicated in detail what the athlete had to do in each training session. The exercises were supervised by trainers or judges, all certified by CrossFitVariables such as diet control, sleeping time, hydration, or use of ergogenic sports supplements were not studied because the aim of the study was to describe anthropometric variables and how they can affect performance, but not to analyze what results were obtained depending on the lifestyles of the athletes.The equipment used for the anthropometric measurements consisted of a Harpenden skinfold caliper (precision 0.2 mm), Cescorf anthorpometric tape (precision 1 mm), Cescorf segmometer (precision 1 mm), RealMet small sliding caliper (precision 1 mm), RealMet large sliding caliper (precision 1 mm), RealMet dermographic pen, Seca standing height rod (1 mm precision), Ozeri scale (100 g precision) and anthropometric drawer (40 × 50 × 30 cm); all of which were approved, correctly calibrated, and checked every six months.The statistical analysis was carried out through a descriptive and association study by sex of the anthropometric variables and the results of the training. Given the sample size, it was assumed that the values obtained did not have a normal distribution. Thus, we obtained the mean, standard deviations, median, minimum, and maximum for all values. Likewise, in order to find a relationship between the anthropometric values and the training results, the Spearman correlation was used. To find the statistical differences between sexes and the results of the WODs Fran, Cindy and Kelly, a Spearman correlation was calculated. All mathematical and statistical analyzes were performed with Microsoft Office Excel 2019  programs for MacOS, and IBM SPSS 24 .Of the initial sample of 19 men and 10 women, 2 women were discarded because they did not meet the minimum physical level requirements (WODs) for participation in the study, finally leaving a sample of 19 men aged 39 (24–44) years old, and 8 women aged 28 years-old (23–40).p > 0.05), so we conclude that there are no differences between sexes. It was not the same with Crossfit Total, in which the significance of the correlation was p < 0.001. In relation to the results of the WODS, to find the statistical differences between sexes and the results of the WODs Fran, Cindy, and Kelly, a Spearman correlation was calculated, and it was observed that the significance between each of the WODs and sex was greater than 0.05 (p < 0.05) between the results that each athlete obtained in the Kipping Fran (r = 0.607), Cindy (r = –0.412), or Kelly (r = 0.572) WODs; however, there was no relationship between these three WODs and CrossFit Total. We must also highlight the relationship for men between the relative size and the results in the Kipping Fran .We also found a correlation  for men, and 2.6 (1.9–3.8) for women; and ectomorphic values of1.1 (0.1–2.6) and 1.86 (1.2–2.8) for men and women respectively.The median value of the percentage of fat mass of the male population in our sample was 11.60%, and for the female population, it was 15.23%, which signifies a lean mass ranging between 60.8 and 79.3 kg in the case of men, and 45.1 and 57.1 kg in the case of women. In relation to body mass index (BMI), the median for men was 25.79 kg/m® athletes, a complete anthropometric description of athletes in this discipline has not yet been established. Therefore, the present study aimed to establish a descriptive basis for this sport for future research.Despite the growing number of CrossFit® [The weight of elite Spanish athletes  is 75.2 ®  athletes® , 59.3 ± ® .2, a figure that would indicate overweightness [2, which would fall into the obesity range. In the case of women, the BMI values were between 20.33 and 24.37 kg/m2, which corresponded to the normal weight range in this index. However, BMI is not the most relevant index to take into account in athletes since it does not take into account which body compartment that mass refers to  [The values obtained from the median BMI in the case of men were above 24.99 kg/mightness , and in ne mass) .Therefore, for the body composition analysis, the four-component model was utilized: muscle mass, fat mass, bone mass, and residual mass. According to this model, the results indicated that both men and women were found in fat mass percentage ranges that would be considered athletic ,17.Comparing these indices, it was found that 9 of the 19 men in the sample had a BMI that indicated overweightness or obesity, as compared to the percentage of fat in which the entire sample demonstrated healthy values. In other studies, in which BMI was compared with the percentage of fat, even greater differences were found, finding results of 97.7% overweight or obese according to the BMI, as compared to 8.9% according to the percentage of fat ; or anotThe Acromio-iliac Index shows us the ratio between the width of the shoulders measured at the point of the acromion and the width of the hip at the height of the iliac crest. It is considered that there is a trapezoidal trunk when the proportion is less than 70% in men and 75% in women; intermediate when it is less than 75% in men and 80% in women; and rectangular in the rest of the cases. In the general population, these figures are 71.78% for men and 80.71% for women . In our ® is composed of a multitude of gymnastic exercises. However, perhaps the physical demands when lifting heavy loads will result in the anthropometric values of CrossFit® athletes becoming more similar to those of weightlifting athletes, with the exercises from artistic gymnastics performed in a more basic manner and with execution based more on strength than technique.We compared our sample with weightlifting and artistic gymnastics athletes according to the study by Victoria Pons et al. , and we If the anthropometric parameters of the studied sample stand out in something, it is in the heterogeneity of their values, which makes sense given the variability of exercises practiced, each with completely different physical demands that gave advantages to some athletes over others but which makes it extremely difficult to find that perfect anthropometric profile for the practice of this particular sport.Although our results showed differences by sex in CrossFit Total when analyzing results from the WODs that required technical skills , we did not find significant differences between sexes. These WODs are adapted for men and women both in the loads lifted  and in the execution of some exercises to try to balance the results between sexes; therefore, the adaptations made in the CrossFit  regulatip < 0.001) was found between a short arm span in men and better results in Kipping Fran, in which the speed of execution of the pull-ups is decisive for the completion time of this workout; which coincides with the results found in a study by Taboada-Iglesias et al. [However, a correlation (r = 0.643, s et al. , in whicIn a study by Butcher et al. , as in o® athlete would have performed one or several times in recent years. Despite not being an objective of this study, if variables such as diet, sleep, hydration, or use of ergogenic aids had been controlled, the relationship between anthropometric variables and sports performance could have been better isolated. Thus, not knowing the training demands or how to manage energy during its execution were no factors that limited the performance of the athletes in each test. Despite all of this, and the limitation of the sample obtained, it is the only study that can be currently found in the scientific literature that provides a complete anthropometric description of CrossFit® athletes and that offers data on how these data influence sports performance. Future research should address how and why anthropometric characteristics and body composition might influence CrossFit performance.The limitations that we have found in the present study were: the small geographical area given the time established for the study and its nature as a pilot study. Another limitation is the sample size of the athletes recruited, and this could influence the statistical analysis carried out. Anyway, small sample sizes characterize the studies carried out so far on this subject in strength sports. Furthermore, the selection of the sample became complex as there were no regional or national competitions where we could find the athletes, and for this reason, we used official WODs that any experienced CrossFit® athlete has a low amount of fat mass and a small relative size, which is an advantage in the WODs, which include exercises performed with body weight, and a high muscle mass that provides benefits in strength training. An acromio-iliac index under 70% in men and around 70% in women seems to be a desirable characteristic for CrossFit® athletes, although there is a lack of evidence about the influence of the AI index on performance.In view of the results, we can conclude that the CrossFit® athletes, it is difficult to compare the results obtained with other studies in similar sports.Given the heterogeneity of the anthropometric data of the CrossFit


The buildup of corrosion products over a reinforcing bar and associated reduction in rib height lead to degradation of the bond between reinforcement and concrete. The authors have previously used digital image correlation (DIC) to visualize and quantify load-induced cracking at the interface in specimens with varying degrees of corrosion. The results obtained in that study are used here to simulate the post-corrosion local bond behavior. A bond degradation model is incorporated into the discrete analysis tool, 3D Rigid Body Spring Model (RBSM) for the simulation. This analysis method allows the shape of the reinforcing bar to be directly modeled, and concrete cracking behavior is simulated by using a randomly shaped mesh. The magnitude of opening and sliding over the tips of ribs in the simulation, in which the reduction in rib height could not be modeled, is significantly lower than observed in the experiment. The results demonstrate that reduction in rib height is an important factor in post-corrosion behavior, and needs to be included in simulation models. It is also understood that in order to gain a better understanding of local post-corrosion bond behavior, de-bonding between reinforcement and concrete needs to be modeled in a discrete analysis framework. The bond between reinforcement and concrete is a crucial factor governing the deformation and resistance of reinforced concrete structures against different types of loading. Various studies have been conducted to understand and model the effect of physical, structural, and material parameters, such as bond length, concrete cover to reinforcing bar diameter ratio, etc. on bond ,2,3. OveHowever, corrosion of the reinforcement over time is manifest as bond degradation. Corrosion reduces the reinforcement rib height, thereby reducing mechanical interaction, while the accumulation of corrosion products at the interface increases slipping. The combination of these behaviors is referred to as rebar damage ,8,9. TheSince bond behavior clearly has a significant impact on the structure, it is important to develop numerical simulation models that predict and help understand the post-corrosion structural response to varied loadings. In the past, various finite element models have been developed to simulate this post-corrosion response ,21,22. FApart from continuum models, there exist various discrete models for simulating the concrete fracture phenomena. Concrete is discretized, and its response to various kinds of loading has been successfully modeled in the past by Cusatis et al. , SchlangDIC has been used to directly observe bond interaction at the interface for uncorroded specimens . DIC is In this section, the details of the 3D RBSM framework utilized to simulate the post corrosion bond degradation has been described.3 to 20 × 20 × 20 mm3, as shown in In 3D RBSM, the concrete and steel are discretized into three-dimensional rigid bodies which are connected to adjacent bodies by one normal and two shear springs, as shown in The mechanical properties of concrete and reinforcement are governed by defining constitutive relationships for the normal and shear springs. The normal springs for concrete do not fail in compression and have a tri-linear tensile characteristic, as shown in normal and Fshear, as shown in The current 3D RBSM framework is able to simulate loss in confinement around the reinforcing bar due corrosion expansion induced concrete cracking ,30,31. Hnormal is applied to normal springs connecting reinforcement and concrete rigid bodies at the interface, which reduces their tensile strength and stiffness, thereby inducing earlier fracture and simulating reduction of mechanical interaction. Furthermore, parameter Fnormal is also applied to reduce the tensile strength of normal springs connecting reinforcement rigid bodies. Since the geometry of the reinforcement cannot be changed, Fnormal reduces the yield strength, thus reducing the yield load and simulating reduction in cross-section. Frictional interaction between corroded reinforcement and undamaged concrete increased, as per the experimental observations by Jiradilok et al. [shear increases the tensile strength of the shear springs at the interface.Fk et al. , and thux is the degree of corrosion (%) represented as a percentage reduction in mass after corrosion.In this study, the computation does not include a corrosion expansion model to simulate corrosion-induced concrete cracking, since in the experimental study being simulated, the corroded reinforcing bar was initially corroded and then re-casted into a new specimen, thus eliminating the effect of corrosion induced cracking on bond interaction.The current section provides background information regarding the details of the experimental study selected for simulation, geometry and boundary conditions of the simulation model, as well as the considered analysis cases.2 until the required degree of corrosion was achieved. Following this, the reinforcement was prepared and re-casted into a new specimen with a 100 mm × 100 mm cross-section and a 400 mm length, with geometry as shown in The simulation model is based on the experiments conducted by Avadh et al. . In the 3 to 20 × 20 × 20 mm3; however, a finer mesh size of 5 mm is used on the surface of the concrete within the window to enable accurate capture of the cracking phenomenon and crack pattern induced by bond interaction, as shown in section D-D. The elements in the center of the window are meshed into finer square-shaped elements, as the specimen had a notch in the center as shown in section C-C, to ensure cracking from the center. The diameter of the reinforcing bar is 25 mm. The material properties used in the simulation are identical to those of the experimental study, as shown in To allow simulated local bond responses to be compared with the experimental study, the exact geometry of the specimen as cast in the experimental study by Avadh et al.  is modelIn the simulation, the steel bar is elongated at a rate of 0.001 mm for the first 100 steps and 0.005 mm for the remaining 980 steps, to cause a total elongation of 5 mm. The initial rate is kept slower, in order to obtain accurate internal stress conditions during the crack initiation phase.The objective of this study is to investigate the effect of a reduction in rib height and the presence of a corrosion product at the interface using the current bond degradation model in 3D RBSM. Hence, to conduct this investigation and identify the improvements required in this bond degradation model, cases with an extreme degree of corrosion were selected. From the experimental study, two specimens are selected for modeling, as shown in This section discusses the findings from simulation of uncorroded and corroded cases, and compares them with the experimental observations.SX1, SX2, CX1, and CX2 are the displacements (in mm) in the X direction for the corresponding rigid bodies representing reinforcement and concrete, as shown in This section discusses the local pullout behavior observed in the simulation, and compares it with the observed experimental behavior. normal. Comparing the uncorroded simulation model SUC-00 and experimental specimen UC-00, the response is seen to be somewhat similar. In the corroded cases, the experimental results show that, with corrosion, the amount of slip with respect to load  is higher, but this phenomenon is not observed in the simulation. On the other hand, the magnitude of the load at failure is similar in the corroded model SUC-20 and experimental specimen C-20. That is, the bond degradation model in 3D RBSM is able to simulate the reduction in ultimate load due to corrosion, but not the local deformation behavior.The load-slip relationships for the two simulation models SUC-00 and SC-20 (solid lines) and the corresponding experimental specimens (dotted lines) are shown in normal and Fshear are used to simulate post-corrosion response. Due to the presence of ribs in corroded model SC-20, diagonal cracks are induced owing to the ongoing mechanical interaction, so its behavior differs from that in the experiments.The diagonal cracks observed in models SUC-00, SC-20 and specimen UC-00 represent mechanical interaction between reinforcement ribs and surrounding concrete. The stiffer response of the corroded model, as discussed in the previous section, can be attributed to the fact that, in the simulation, the de-bonding between concrete and steel elements is different from that observed in the experimental study.normal and Fshear is investigated. In the simulation, the opening and sliding behavior is measured by selecting steel and neighboring concrete rigid bodies, as indicated by points B1 and A1, respectively, in the upper section of In this section, the simulation results are compared with the local opening and sliding behavior, as measured in the experiment. That is, the change in local response due to implementation of modification factors FiXA and iYA are the displacements of point iA in the X and Y directions, respectively, in mm, iXB and iYB are displacements of point Bi in the X and Y directions, respectively, in mm, as extracted from the 3D RBSM simulation framework.The displacement of these points in the X and Y directions was extracted, and opening and sliding were then calculated using Equations (9) and (10) in a similar way to that used in the experimental study. Only the rib tips in the top left segment were selected for comparison.The opening and sliding relationship for uncorroded model SUC-00 and corroded model SC-20 is shown in normal and Fshear used to simulate post-corrosion bond behavior. From the simulations carried out in this study, the following conclusions can be derived:Load-slip results from the simulation are similar to those measured in the experiment for the uncorroded case. However, for the corroded model, the reduction in load at failure is appropriately simulated, but the simulated response was much stiffer than that seen in the experiment.Through DIC-derived strain maps, it was determined from the experiment on a corroded specimen that mechanical interaction had been degraded as a result of the corrosion-induced reduction in rib height. In this case, no diagonal cracking was manifest. However, in the simulated corroded model, since rib height cannot be reduced mid-computation, mechanical interaction continued to take place.Detailed observation of failure at the interface showed that, in the experiment, bond failure occurred due to clear de-bonding between reinforcement and surrounding concrete. On the other hand, in the simulation, no such de-bonding was observed even in the corroded model, as the concrete elements remained attached to their neighboring steel elements.In comparing the opening and sliding relationships obtained from the simulation at the rib tip to the experiment results, it was observed that the simulated maximum value of opening is significantly less than that in the experiment, even for the uncorroded model. It is clear that as concrete elements remain attached to steel elements in the simulation, opening above the tip of the ribs is restricted.This study highlights the need to model corrosion-induced reduction in reinforcement rib height and the debonding process at the interface to better understand the post-corrosion bond behavior. The 3D RBSM framework was used to develop a model with the same geometry as a previous experimental study, with parameters FThese results clarify that to enhance understanding of post-corrosion local bond behavior, it is important to model the corrosion-induced reduction in rib height. However, with regards to the prediction of average post-corrosion bond capacity, the current 3D RBSM model performs satisfactorily.