The open-circuit potential of HDG samples in cement paste with various additions of MnO4− was monitored in order to follow a transfer of zinc from activity to passivity. Furthermore, the influence of the addition of these anions on the physicochemical properties of normal-strength concrete or cement paste was evaluated by means of hydration heat measurements, X-ray diffraction analysis, and compressive strength. The effective concentration of MnO4− anions prevents the corrosion of the coating with hydrogen evolution and ensures that the bond strength is not reduced by their action, which was determined to be 10−3 mol·L−1. Lower additions of MnO4− anions (10−4 mol·L−1) are ineffective in this respect. On the other hand, higher additions of MnO4− anions (10−2 mol·L−1), although they ensure the corrosion of the coating in fresh concrete without hydrogen evolution, but affect the hydration process of the cement paste that was demonstrated by slight water separation.In this paper, the effect of gradually increasing amounts of KMnO The carbon (0.11 wt.%) and phosphorus (0.01 wt.%) content in the steel do not affect the structure of the excluded coating 2·2H2O (CHZ—see Equations (3)–(5)) 2·2H2O) and other zinc-based corrosion products (ZnO and Zn(OH)2). It is clear that the bond strength of reinforcement with concrete can be influenced not only by the presence of specific types of corrosion products but also by their morphology. In the case where hydrogen evolution has been prevented due to the presence of a sufficient amount of MnO4−, the presence of specific corrosion products can significantly affect the bond strength of hot-dip galvanized reinforcement with concrete a·b(H2O) complexes and, thus, retard the hydration process. It can also be ruled out that the phases formed were capable of forming gel layers around the clinker phase grains preventing the grains from hydrating themselves. These facts would be more significantly reflected in the evolution of the hydration heat.It is clear that the actual hydration process of Portland cement is only slightly affected by the highest additions of KMnO4− additions seem to affect the hydration of tricalcium silicate (C3S) and tricalcium aluminate (C3A) only marginally [Compared to, for example, chloride anions (which significantly promote the hydration process), MnOrginally .−2 mol·L−1 KMnO4 is more likely due to the already significant bleeding effect of concrete, which will be more significant, especially in the center of the test samples and in areas with locally increased concentration of dissolved MnO4− anions. It is clear that different real w/c ratios affect the hydration process [4− reduction reactions described above.The described decrease in the maximum measured temperature (maximum measured heat) of concrete samples with the addition of 10 process . On the 3A grains [Other cement setting retardants also include (besides the above-mentioned) organic substances based on humic acids , polypheA grains .4 additions, a comparative XRD analysis was performed on the paste samples after 28 days of maturation. The results of the actual X-ray diffraction analysis are summarized in −2 mol·L−1 (Mn(3)) to the premixed water. In situ X-ray diffraction has been successfully used to evaluate the retardation effect of polymeric substances on cement hydration [To verify possible changes in the composition of the hydrated phases of the cement paste in the case of KMnOydration .4− anions can only be consumed during the actual corrosion process of the hot-dip galvanized steel in the concrete (RDHE retardation) and not during the hydration of the cement. Respectively, it can be concluded that even the highest additions of this substance to the cement paste reported in this study do not significantly affect the hydration of the cement. No new phases are formed, nor can it be discussed that there is a significant reduction in the formation of conventional hydration phases.In all likelihood, the added MnO4− anions present will gradually leach out of the cementitious sealant (concrete), and with regard to the hydration of the cement (concrete) and its subsequent hardening and curing, the inactive KMnO4 will be leached out by any flowing water. It cannot be ruled out that less soluble reducing forms of MnVII, such as MnO2, MnO(OH), etc., will accumulate as inactive particles in the cement paste (concrete).It is very likely that the MnO4− on the mechanical properties of normal strength concrete (NSC), compressive strength tests were also carried out on a group of parallel cube specimens after the addition of graded amounts of KMnO4 to the mortar water  and Mn(2) substitutions does not significantly affect the compressive strength of the resulting samples. At an addition of 10−2 mol·L−1 KMnO4 to the water (Mn(3)), a statistically slight decrease in the compressive strength of the resulting concrete is already observed. It is very likely that the slight dewatering in the case of Mn(3) admixture may already affect the w/c value, especially at the surface of the concrete cubes, which may result in a slight decrease in the compressive strength of the concrete bodies, thus formed [4− and the formation of the very stable MnO2 phase described above cannot be expected to affect the hydration process of silicate cement with an impact on the compressive strength of the concrete samples. To date, it has not been satisfactorily explained how conventional silicate cement hydrates in the presence of KMnO4 additions. It is essential that further research focuses on this topic.The results of this test are shown in the bar graph in s formed ,96. The 4 to the mortar water. The effective concentration of the added MnO4− anions to the premixed water was experimentally determined to be 10−3 mol·L−1, since it was found that no corrosion under hydrogen evolution of the hot-dip galvanized steel occurs during the entire exposure time in fresh cement paste. It was further confirmed for this addition of KMnO4 that the group of samples of plain hot-dip galvanized steel showed the highest values of ultimate bond strength and the lowest values of slip in the cement paste compared to the reference group (without MnO4−). In this case, the formation of specific corrosion products on the surface of the hot-dip galvanized steel can also have a positive effect on bond strength.The results of this paper directly in real cement mixtures confirm the conclusions on the retardation of RDHE (rapid dissolution and hydrogen evolution) for hot-dip galvanized steel in the case of the addition of graded amounts of KMnO4− anions to concrete in the range of 10−4 mol·L−1 are insufficient in terms of limiting the corrosion of HDG specimens under hydrogen evolution and ensuring an undiminished bond strength value compared to the reference group.Additions of MnO4 in the range of 10−2 mol·L−1 cause a decrease in the bond strength of hot-dip galvanized plain bars steel with cement paste. Under such high addition of potassium permanganate, the composition of corrosion products on the surface of the hot-dip galvanized steel is likely to change in favor of MnII/MnIII-rich phases, which negatively affect the overall bond strength with cement paste.Conversely, additions of KMnO4− in the range of 10−2 mol·L−1 already had a slightly negative effect on the hydration of the cement and also on the evolution of the compressive strength of the resulting concrete. These additions already lead to a slight water separation, which results in a slight bleeding of the concrete. This can also have a negative effect on the bond strength. By measuring the time evolution of the hydration heat of the concrete samples and also by measuring the compressive strength of the concrete samples, it was verified that the addition of MnO4 is partially consumed during the actual corrosion process (RDHE limitation) without significant changes in the composition of the hydrated phases of the cement. It is very likely that the added KMnO4 as a concrete additive to increase the efficiency of the use of hot-dip galvanized concrete reinforcement (RDHE limitation) is apparently complicated by the need to ensure a sufficient concentration of this additive and, at the same time, to avoid excessive dosage . At the same time, it cannot be ruled out that the release of manganese oxo-hydroxides from the concrete by leaching may occur.The use of KMnO


This study aimed to assess the socio-demographic factors associated with knowledge of antibiotics and antibiotic resistance in Malaysia. (2) Methods: A cross-sectional study was carried out between April 2022 and March 2023. Malaysian adults aged ≥18 years old and able to understand English or Malay were recruited. During data collection, the WHO questionnaire “Antibiotic Resistance, Multi-Country Public Awareness Survey” was used. Data were collected across 14 states in Malaysia. (3) Results: A total of 517 participants completed the questionnaire. Most participants were females (67.9%), aged 30–49 (46%), and from central Malaysia (69.8%). Most participants (98.5%) reported taking antibiotics. A misconception presented was that sore throats, fevers, colds, and flu can be treated with antibiotics. A total of 58.8% of participants had high knowledge of antibiotic usage (scores 12–15), while 64% had high knowledge of antibiotic resistance (scores 9–14). Findings indicate that increasing age, income, and education were associated with higher knowledge. (4) Conclusions: This study highlights the knowledge deficiency of antibiotic resistance among Malaysians. Educational programs should engage a younger and lower socio-economic population to increase awareness. Antibiotics typically function by binding to specific target sites of bacteria to disrupt their activity. However, throughout evolution, bacteria have developed resistance to antibiotics, causing the medication to be ineffective in fighting infections . IncreasKlebsiella pneumoniae, Acinetobacter baumannii, Carbapenem-Resistant Enterobacteriaceae (CRE), and Vancomycin-Resistant Enterococci (VRE) have been increasing, while the rates of Methicillin-resistant Staphylococcus aureus show no change from previous years. A total of 23% of the clinical isolates reported came from the community, while 77% came from healthcare-associated infections [The threat of antibiotic resistance is worldwide. The estimated global mortality rate from drug resistance in 2019 was 4.95 million, with Southeast Asia accounting for over a thousand deaths . The Minfections . There iAs antibiotic misuse is the cause of antibiotic resistance, there is an urgent need to raise public awareness regarding antibiotic misuse. A previous systematic review found that the public has an incomplete understanding of antibiotic resistance and its causes. Even though 70% of participants were familiar with the term “antibiotic resistance,” the majority (76%) thought it meant changes in the human body . PreviouThis study was a cross-sectional study carried out to assess the public’s knowledge of antibiotics and antibiotic resistance in Malaysia for a span of 11 months, from April 2022 to March 2023. The WHO questionnaire, “Antibiotic Resistance, Multi-Country Public Awareness Survey,” was used for this study . The queThe sample size was obtained using the Raosoft sample size calculator. The margin of error used was 5%, with a confidence level of 95% for a Malaysian population of 32.7 million in 2021 . Hence, The sections covered in the questionnaire consisted of section A, participant demographics (Q2–Q9); section B, use of antibiotics (Q10–Q13); section C, knowledge about antibiotics (Q14–Q17); section D, knowledge about antibiotic resistance (Q18–Q25); section E, participant opinions on antibiotic resistance (Q26–Q27); and section F, use of antibiotics in agriculture (Q28). All the questions used a closed-question methodology to maintain consistency in the answers provided. The demographics that were asked consisted of gender, age, residence, education, household income, ethnicity, and household composition. The survey consisted of multiple-choice questions with single-select, multiple-select answer options, and 5-point Likert scale questions. Participants’ names and personal identifiers were not requested to maintain anonymity. Before answering the survey, a summary of this study was presented to the participants. Consent was electronically obtained when participants clicked on “I consent” before starting the survey.p-value of less than 0.1 was considered statistically significant. For sections C and D, scores were calculated to indicate the knowledge of antibiotics and antibiotic resistance among participants. A score of “1” was given for each correct answer and “0” for an incorrect answer. To categorize the scores of the participants, the median scores for the knowledge of antibiotics and the knowledge of antibiotic resistance were calculated, respectively. Participants that had a lower score than the median were grouped as having “low knowledge,” while those that had scores higher than the median were grouped as having “high knowledge.” To understand the association between demographic factors and the knowledge of participants, regression analysis was carried out. The degree of correlation between knowledge of antibiotics and knowledge of antibiotic resistance was analyzed using Spearman’s rank-order correlation coefficient.Data were analyzed using the Statistical Package for Social Sciences (SPSS) version 29 . The data obtained were analyzed using descriptive analysis and Pearson’s chi-square or Fisher’s exact tests. A During data collection, a total of 517 survey responses were obtained from participants around Malaysia. The socio-demographic data are shown in In terms of education, most participants have pursued higher education, which includes having a Bachelor’s degree, Master’s degree, or Doctorate . As for the monthly household income, responses were divided into three primary groups based on the Malaysian income classification, which are the below 40 group (poor income), the middle 40 group (average income), and the top 20 group (rich income) .A large proportion  recall taking antibiotics at some point in their life, while only 8 (1.5%) reported never having antibiotics. Out of those who have taken antibiotics before, 465 participants (91.4%) obtained a prescription and were also given directions on how the medication is to be taken. Most of these participants (95.1%) obtained their medication at a medical store or pharmacy. The data are shown in 2 = 33.464, p = 0.000), with rich household income , and those with higher education . Evaluation of the scores also revealed that only 42 participants (8.1%) obtained a complete score of 15. The association between the socio-demographics of participants and their level of knowledge of antibiotics is shown in The scores in this section were categorized into the “0–11” group or the “12–15” group based on the median split, which was calculated to be 12.0. Most participants received a “high knowledge” score , while 213 (41.2%) received a “low knowledge” score. Moreover, a better antibiotic knowledge level was noted in participants aged 30–49  wrongly think antibiotics should be stopped once they feel better, while 4 participants (0.8%) do not know. When asked if it is acceptable to take antibiotics given by friends or family, 22 participants agreed (4.3%), while 22 (4.3%) did not know. The misconception of buying or requesting an antibiotic when having similar symptoms as previous illnesses was noted, as 72 participants (13.9%) agree that this is acceptable, while 47 (9.1%) do not know. Participants were also asked about health conditions that can be treated with antibiotics, as shown in 2 = 5.457, p = 0.065), male , rich income , and those living in the Southern region  received a high knowledge score. The association between the socio-demographics of participants and their level of knowledge of antibiotic resistance is shown in Based on the median score of 9.0 in this section, a median split divided scores of “0–8” and “9–14” into the “low knowledge” and “high knowledge” groups, respectively. Most participants obtained a high score , while 186 (36.0%) obtained a low score. Interestingly, there were no participants that obtained a full score of 14, and only one (0.2%) participant obtained the next highest score of 13. Participants of age 30–49  and Antibiotic Resistance” (19.6%) were most heard, with only a negligible difference in their values. This is followed by the phrases “Antibiotic-resistant Bacteria” (18.5%), “Superbugs” (15.6%), “Antimicrobial Resistance” (15.2%), and the abbreviation “AMR” (11.4%). A total of 63 participants (12.2%) have not heard any of these terms. To investigate the knowledge level of participants about antibiotic resistance, participants were also provided with a set of statements and asked whether they were true or false. Although most of these statements were answered correctly, a common misunderstanding of how antibiotic resistance works was observed, as 451 participants (87.2%) wrongly agreed that the body becomes resistant to antibiotics, leading to antibiotic resistance.A multivariate logistic regression analysis was performed to ascertain the effects of significant socio-demographic characteristics such as gender, age, race, household income, education level, and region on the likelihood of having a high knowledge of antibiotics and antibiotic resistance . The unsFor “Knowledge of Antibiotics,” age and education level have a significant impact on the higher possibility of achieving a high knowledge level, as indicated by the adjusted odds ratio and confidence interval. As for “Knowledge of Antibiotic Resistance,” the socio-demographic characteristics of household income, education level, and geographical region indicate a higher tendency to have an outcome of high knowledge.Spearman’s rank-order correlation indicated a weak positive monotonic correlation between knowledge of antibiotics and knowledge of antibiotic resistance  participants agreed, 20 (3.9%) disagreed, and 173 (33.5%) were unsure about this statement.This cross-sectional study was able to recruit 517 participants from different parts of Malaysia. This overall response rate exceeded our expectations in providing important data on knowledge of antibiotic usage and resistance in Malaysia, as well as possibilities to decrease the misuse of antibiotics. Antibiotic resistance is a prevalent issue in Malaysia, as rates of antibiotic-resistant bacteria have shown a rise in resistance patterns . A compaBased on the results of this study, 41.2% have a low knowledge score on antibiotic usage. Most of the participants correctly answered that all antibiotics are to be taken as directed, even if symptoms subside (91.9%). This overall result is better compared to the previous studies carried out in Malaysian cities such as Pahang, Putrajaya, and Shah Alam ,29. As fResponses on knowledge of antibiotic resistance indicate that 36% have low knowledge. Consistent with results from other studies, “Drug Resistance” and “Antibiotic Resistance” are terms that people are most familiar with. A reason for this could be because these terms are more self-explanatory compared to others like “Superbugs” and “AMR.” Our data demonstrate that healthcare professionals have played a key role in informing patients about antibiotic resistance. This shows that the stringent efforts of the Malaysian government to implement policies and guidelines for infection control and prevention in healthcare settings have been successful . Our finUpon post-hoc analysis, a significant association was highlighted between socio-demographic characteristics and high knowledge levels. Education level was the only common factor associated with high knowledge of antibiotics and antibiotic resistance. This pattern is replicated in other studies conducted in Bhutan, Hong Kong, and Cyprus ,34,35. TFurthermore, there was a lack of understanding of the seriousness of antibiotic resistance and individual roles in combating it. Less than half (40.0%) of the participants agreed that there is not much that they can do to stop antibiotic resistance. The WHO survey to assess the knowledge and awareness of antibiotic resistance across 12 countries in 2015 also had similar findings, with 57% saying they do not have a role . PreventEducational initiatives should investigate these knowledge gaps to develop a more apprehensive way to address this issue. There is evidence that targeted educational intervention raises awareness of antibiotic resistance, as presented by a local study in the state of Perak . AccordiThere are several limitations to this study. First, most participants were from the Malaysian metropolitan cities of Selangor and Kuala Lumpur. This may cause an underrepresentation of the whole Malaysian population. Second, there is a possibility of recall bias in answers such as household income and participants’ prior use of antibiotics. Third, it is difficult to monitor the understanding of participants as this study has been conducted using an online questionnaire due to the possible cost imposed by the geographical factors of an in-person survey. Nonetheless, an online questionnaire allows us to reach a larger group of respondents, as most Malaysians use smartphones. The anonymous nature of the questionnaire could encourage honesty because participants would not feel judged or self-conscious during the public awareness survey.To our knowledge, this study is one of the first assessments of knowledge of antimicrobial resistance conducted on a national scale after COVID-19. Despite the high usage of antibiotics in the country, our results indicate that the knowledge of antibiotic use and antibiotic resistance among the Malaysian public is still poor. Younger individuals, as well as those with a low education level and low household income in particular, present lower knowledge. The gaps in knowledge highlighted in this study could be used to plan educational interventions to raise awareness about antibiotic resistance across the country. When the public understands their roles in combating antibiotic resistance and the seriousness of the issue, the spread of antibiotic-resistant infections could slow down. This could lessen the strain on the healthcare system and maintain the efficacy of already available antibiotics. To identify the underlying causes of human attitudes toward and perceptions of antibiotic resistance, a qualitative analysis is necessary.


R2 value of 0.818 and a S-value of 21.7 g/L. The large S-value shows that a digital Brix refractometer should not be used in a model to predict colostrum IgG concentration. However, %Brix scores of 19.0, 22.0, 25.0 and 30.0 percent can be used to estimate minimum colostral IgG concentrations of 25, 50, 75 and 100 g/L. These four cutoffs can be used to strategically feed smaller volumes of colostrum to newborn calves. Smaller volumes may reduce unwanted side effects and shorten the time interval in which calves refuse to nurse, while still delivering an adequate mass of IgG to have successful transfer of passive immunity.Many dairy operations uses a Brix refractometer to assess the quality of first-milking colostrum. This study investigated whether a digital Brix refractometer could be used in a model to predict colostrum IgG concentration and whether more than one %Brix threshold could be used for different colostrum IgG concentrations. Colostrum from 182 animals was tested using a digital Brix refractometer and by single radial immunodiffusion. Statistical analysis, using simple linear regression to relate %Brix results with corresponding colostral IgG concentration, and receiver operating characteristic (ROC) analysis were used to identify %Brix cutoffs that had no false positive results. Colostral IgG concentrations from digital Brix refractometry had a  Newborn calves are born agammaglobulinemic and are dependent on the successful transfer of passive immunity (TPI) for optimal health and wellbeing , 2. CurrFeeding colostrum using an esophageal tube feeder to a newborn calf is not risk-free. One complication is aspiration pneumonia, which is caused by improper technique or excessive calf movement when the colostrum is delivered. Abdominal distension, colic, and occasionally death are other potential complications of feeding large volumes of colostrum in the first 24 h of life. As such, some dairy calf-care providers and practicing veterinarians have inquired about the possibility of implementing site-specific colostrum management programs. The calf-care providers and veterinarians wish to feed smaller volumes of first milking colostrum but still deliver a sufficient mass of colostral IgG to have excellent TPI. It is hypothesized that feeding smaller quantities of colostrum may improve abomasal health, reducing the likelihood of abdominal distension and colic post-colostrum feeding. The aim of this study was to compare %Brix results to the IgG concentrations of bovine colostrum at first milking and determine four different %Brix thresholds for 25, 50, 75, and 100 g/L of bovine colostral IgG.Four Holstein dairy farms located in the Midwestern region of the United States submitted first-milking colostrum samples for testing and analysis at an accredited American Association of Veterinary Laboratory Diagnosticians (AAVLD) laboratory, the Wisconsin Veterinary Diagnostic Laboratory (WVDL). Power calculations based on the correlation between the Brix score and IgG concentration using the Power procedure in SAS  were used to calculate the sample size needed for each of the five different sampling strata. With an alpha of 0.05 and a power of 0.80, the projected minimum sample size for each of the five strata was 7 when the correlation was 0.65 or higher. Sampling kits were sent to each farm with instructions on how many samples should be collected from each of the five different sampling strata . One hunFrozen (−80°C) colostrum samples were thawed in a bead bath. Testing commenced when the colostrum samples reached a temperature of 38.5°C to mimic the average normal bovine body temperature. The samples were thoroughly vortexed and tested in duplicate using a digital Brix refractometer, the same instrument model used in the on-farm collections. The Brix refractometer was calibrated by laboratory personnel using deionized water before testing commenced and repeated after 10 colostrum samples were tested. The samples were tested for IgG concentration using a commercially available single radial immunodiffusion (SRID) test  using the same methodology as previously described (R2) and standard error of the regression (S) were calculated, and a residual plot was constructed. Receiver operating characteristic (ROC) analysis using the ROCR package  was used to calculate the cutoffs for colostral IgG concentrations of 25, 50, 75, and 100 g/L such that there were no false positive (FP) results for each %Brix value and the corresponding IgG result. An FP was defined as a %Brix value that caused the model to overestimate the true colostral IgG concentration.The %Brix results were compared with their matching SRID results using simple linear regression . The %Brix was the independent variable, and the colostral IgG concentration, measured by SRID, was the dependent variable. The regression model was used to predict colostral IgG concentration from each of the 182 %Brix results. As previously described, the model was also used to calculate residual values for each of the 182 colostrum samples  when used to feed smaller volumes of colostrum to newborn calves is an intriguing concept that warrants further study.The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.Ethical review and approval was not required for the study on animals in accordance with the local legislation and institutional requirements.DS: study design, data analysis, testing, writing—original draft, and editing. RB: writing—review, editing, and assistance with document submission. LS: laboratory testing supervision, writing—review, and editing. NK: statistical and data analysis, writing—review, and editing. TE: study design, writing—review, and editing. All authors contributed to the article and approved the submitted version.


Antimicrobial prescription audits were often carried out to reduce the overuse of antibiotics. Usually, audits were performed over periodical intervals. Daily antibiotics audits were time consuming and labour intensive. Though it"s practically impossible, we tried. However, we conducted this audit over a three-month period as daily audit and the cases were regularly followed. It is the prospective case-control study of antibiotic utilizations from prescriptions on ID and non-ID department.This Prospective Case-Control study was conducted in tertiary care hospital in India for a period of 3months (Jan-mar2023). Data regarding demographics, antibiotic therapy, diagnosis, rational antibiotic usage (indications mentioned or not), type of therapy  and 48hrs review of antibiotic prescriptions  of both groups were collected by Pharm-D interns from the medical records and analysed using SPSS version 26.0.During the study period, 899 subjects’ medical records were audited for antibiotic usage from the prescriptions. The comparative data were shown in table-1.rd of the cases acquired ID opinion which is significantly less than the non-ID department. Predominantly ID opinion is acquired when culture shows positive results. In most cases, the indications were mentioned only by the ID and not by the non-ID team. Discontinuation (28.1%) and de-escalations (18.7%) done by the ID was found to be significantly higher than non-ID. Based on this, we conclude that ID opinion play a crucial role in selection of antibiotics, both in terms of definitive and empirical choices. This study has certain limitations where, outcomes will be followed further.1/3All Authors: No reported disclosures


As societal attitudes toward narcotics have changed, harm reduction strategies have emerged which make it safer to inject intravenous drugs. Diamorphine (heroin) is commonly sold as its free base—better known as brown—which has extremely poor aqueous solubility. As such, it needs to be chemically modified (cooked) to enable administration. Needle exchange programmes commonly supply citric or ascorbic acids which facilitate intravenous administration by increasing heroin solubility. If heroin users mistakenly add too much acid, the low solution pH can cause damage to their veins and, after repeated injury, could result in the loss of that injection site. Currently, advice cards supplied with these exchange kits suggest that the acid should be measured in pinches, which could result in considerable error. This work employs Henderson–Hasselbalch models to analyse the risk of venous damage by placing solution pH within the context of the buffer capacity of the blood. These models also highlight the significant risk of heroin supersaturation and precipitation within the vein, an event that has the potential to cause further harm to the user. This perspective closes with a modified administration method which could be included as part of a wider harm reduction package.The online version contains supplementary material available at 10.1186/s12954-023-00758-1. Diamorphine (heroin) consumption can have negative impacts on the individual and society . Much ofWhile the former items are more obvious, supplying acids in these kits facilitates the dissolution of poorly water-soluble heroin that is found in the street (brown heroin). Although one cannot assume the purity of street heroin , this su+) into solution, lowering the pH. The nitrogen containing morphinan group in heroin will react with these H+, enabling the heroin to ionize and ultimately dissolve in water. White pharmaceutical grade heroin—which is also sold illegally—is the heroin free base combined with an acid such as hydrochloric acid (HCl) which makes a salt (known as white heroin).Heroin is a sparingly water-soluble compound (0.6 mg/mL)  which deThis salt (diamorphine hydrochloride) is 1000 times more soluble than heroin free base and does not need pH adjustment as it will readily dissolve in water (600 mg/mL) . Heroin There are many methods of preparation or cooking heroin with acids such as ascorbic and citric acid, and some methods are more harmful than others , 13. ProThis work addresses three aspects of heroin administration to improve safety: (1) What is the minimum quantity of acid required to dissolve heroin? (2) How do we instruct users to add this small quantity of acid? (3) How quickly should users inject this infusion?+]) from it and this equilibrium can be described by the dissociation constant Ka. Ascorbic acid is known to be less acidic than citric acid and we find that concentrations from 200 to 6.25 mg/mL led to pH values in the range of 1.8–2.8 (ascorbic acid) and of 1.3–2.2 (citric acid) , we can consider just the first deprotonation event as Ka1 >  > Ka2 >  > Ka3. Further, we assume that as heroin has a pKa > 2 units beyond citric and ascorbic acid , we would expect almost all (> 99%) of the heroin to react with the available hydrogen ions ([H+]) donated by the acid, such that we can calculate the pH of a solution of equimolar acid and heroin [Ka = 7.9) in 1 mL is 5.1 and 4.7 mg and should generate a solution of pH 4.6 and 5.4, respectively. Other authors have revealed that 97.46 mg heroin dissolved in 0.7 mL deionized water containing 20 mg citric acid produces a solution of pH 2.55 [This equation is simplified as we assume that ionic strength is > 0.01 M and constant, therefore activity is constant. Although citric acid is polyprotic , in the context of in the peripheral vein blood flow rate (210 mL/min) [βindex values > 1  may increase the risk of causing phlebitis at the injection site.Although pH 4.6 and 5.4 are significantly beyond the pH of the blood , the blood has a mechanism of acid-basic regulation that can compensate for significant pH changes that may occur, known as the buffer capacity. The buffer capacity of blood is expressed in mEq/L/pH and describes the quantity of acid or base required to cause a pH shift of 1 unit in a 1 L solution , 22. Bas mL/min)  and the βindex of 1, potentially causing phlebitis. Although we know that these calculations underestimate the amount of acid required to produce βindex > 1—due to the presence of contaminants—we suggest that because of the small margins of error, ascorbic acid should be preferred over citric acid.When these acidity values are placed in the context of a blood buffer capacity of 73 mEq/L/pH , 22 and βindex. In interviews conducted with heroin users Scott reports, “…about 10 grains… or a small pinch” [Another problem which arises as users attempt to add this small quantity of acid to prevent the dose from exceeding the l pinch”  is a typl pinch” . AccuratWe illustrate in Fig. C*) is above its equilibrium state (Ceq)  into the vein, which is buffered to pH 7.4 Fig. A. Supersca. 2–3 mg/mL). Precipitation  will then occur to restore the drug concentration in solution to equilibrium  and its solubility at pH 7.4 (2 mg/mL) infused within 1 s (blood volume = 3.5 mL) is > 10. This is very likely to result in rapid precipitation of heroin in the vein. Figure 00 mg/mL βindex) that provides a means to reduce the risk of bolus intravenous drug administration, particularly where phlebitis is a risk. The approach proposed could be applied to other intravenous therapies such as the benzodiazepines, diazepam and lorazepam or Iron infusions (Jectofer®) and will be explored in these contexts in future work.We bring the concepts of the Henderson–Hasselbalch equation to the context of blood buffer capacity to propose an index . Sheet 4 contains calculations of heroin solubility as a function of pH.


After high-temperature treatment, both nano-titanium dioxide-modified concrete and ordinary concrete exhibit typical splitting failure. High-temperature heating reduces the mechanical properties and brittleness of concrete and improves the ductility of concrete. The stress–strain relationship of the specimens was obtained through the uniaxial compression test of ordinary concrete and nano-titanium dioxide-modified concrete cube specimens under normal temperature and high-temperature conditions. In addition, the relationship between temperature and damage variables was established, and the unified constitutive model containing damage variables after room temperature and high-temperature treatment of ordinary concrete and nano-titanium dioxide-modified concrete were established. It provides a reference for future research on the mechanical properties of high-performance concrete structures after high temperatures (fire). Under normal room temperature conditions, the general building structure can maintain its intended functionality for an extended period. However, in instances where there exists a substantial temperature differential within the building environment, the structural load-bearing capacity may diminish, leading to a decline in performance and ultimately resulting in structural failure. The incidence of solar radiation on the sun-facing facade during summer months increases the temperature of the exterior surface of the building. However, this temperature generally does not exceed 60 °C, and it will also cause cracks on the surface of the building, affecting the normal use of the building. In addition, some workshops are in a high-temperature environment for a long time, such as some chemical and metallurgical enterprises’ high-temperature workshops, and their structural surface temperature can reach 200 °C or higher. When the chimney emits high-temperature gas, the internal temperature can reach 500~600 °C. In some accidental cases, there will be a short-term high-temperature impact on the building, such as the temperature of the building reaching 1000 °C or higher within one hour during a fire. At high temperatures, the pore pressure and porosity of concrete will change, and phenomena such as thermal expansion, thermal cracking, and thermal creep will occur. These phenomena will destroy the mesoscopic structure of concrete, leading to a gradual decline in its mechanical performance and problems such as cracking and spalling on the surface. In addition, concrete can also cause damage due to bending or stiffness and mass loss, etc. Various studies indicate that the main effect of fire (high temperature) on concrete is a change in its properties, leading to spalling, while the stress–strain behavior under high-temperature exposure is complex.In recent years, the research on high-temperature damage of concrete at home and abroad has mainly focused on the change law of mechanical properties of concrete under high temperatures ,4,5,6,7 Composite materials along with nanoconcrete have been the subject of extensive research by numerous scholars, with a focus on their mechanical properties . Rawat eThis study investigates the effects of various high temperatures on both ordinary concrete and concrete modified with nano-titanium dioxide. Subsequently, an investigation was conducted on the compressive strength of the two distinct categories of concrete subsequent to exposure to elevated temperatures. The damage mechanics approach was utilized to establish the constitutive model for ordinary concrete. In this study, a constitutive model was developed for nano-titanium dioxide-modified concrete to assess its damage. The model utilized the peak strengthening coefficient, and the test data presented in this paper were subjected to comparative and analytical scrutiny. The aforementioned offers a precise point of citation pertaining to the efficacy of concrete constructions subsequent to exposure to elevated temperatures, specifically those resulting from conflagrations.3 with good stability. The chemical composition of the cement is listed in This study used PO42.5  grade ordinary silicate cement with a relative density of 3.12 g/cmNatural and clean river sand was selected and screened with a standard sieve with a pore size of 0.6 mm. The maximum particle size of the test sand is less than 1.2 mm, and most of the particles (more than 99%) are below 900 μm. More than 50% of particles have a particle size of less than 500 μm. The average particle size is 0.46 mm. The gradation curve of river sand is shown in 3. The grading curve of limestone crushed stone is shown in Limestone crushed stone was used, and the particle size is 5–20 mm continuous grading. The crushed stone used for the crushing index test was passed through a 14 mm test sieve and left on a 10 mm sieve. Put the crushed stone on the sieve into a 100–110 °C oven to dry for four hours, then put it into a cylindrical mold to vibrate and compact, and then put the plunger on top of the aggregate. The integral unit was placed on the pressure testing machine, and the plunger was loaded and gradually pressurized to 400 kN within 10 min. After unloading, the crushed stone was taken out and placed in 2.36 mm for screening, and the ratio of the mass of the crushed stone through this screening to the total mass is the crushing index. The crushing index of the coarse aggregate crushed stone used in the test is 4.8%, and the density is 2.7 g/cmThe water-reducing agent adopted was 2651F , which is a modified polycarboxylic acid ether made by a spray drying process, which has good fluidity and uniform color.Nano titanium dioxide  is in the form of white powder, as shown in The mix ratio is listed in (1)Fifteen ordinary concrete and fifteen NTC3 specimens were carefully chosen and subsequently partitioned into five distinct groups.(2)After 28 days of natural conservation, it was subjected to high-temperature heat treatment of 200 °C, 400 °C, 600 °C, and 800 °C, respectively. The heating rate in the high-temperature furnace is 5 °C/min. The temperature is constant for 6 h after reaching the target temperature, and then naturally cooled in the furnace for 24 h.The instrument for the high-temperature treatment of the specimen is a chamber resistance furnace with model SMF1900-50 . The maximum load is 2000 kN and the axial load accuracy is ±1%, as shown in The longitudinal wave velocity test adopts V-METER III ultrasonic pulse velocity tester , as shown in In this paper, the slope between the peak stress and 0.1 times the peak stress of the test piece is approximately close to the secant modulus. The approximate secant modulus of ordinary concrete is shown in V, and the damaged material unit be regarded as various isotropic units. The total volume is composed of two parts, namely the damage zone dV and the undamaged area nV, obtaining:Lamaitre  proposedcd, we obtain:Introducing the damage variable nσ and σ can be expressed asTE is the initial modulus of elasticity after different temperature treatments, and ε is the strain [Thus, the effective stress e strain .eqε isTensile and compressive strains mainly induce microcrack extension and elongation in near-brittle materials; therefore, the damage evolution path can be described in strain space. According to plasticity theory, the direction of strain in a material depends on the stress state of the material and not on the direction of the incremental stress in the material. Therefore, the multi-axial stress state can be converted into an equivalent stress state by combining the stress invariants, i.e., the equivalent strain wheretr, the evolution equation of compression damage cf of ordinary concrete after different temperature treatments. Secondly, the initial modulus of elasticity TE after different temperature treatments can be obtained from the stress–strain curve and the first derivative curve of the stress–strain curve. tκ can be obtained by substituting TE into the Equation (15). Finally, the inflection point ctnκ of the stress–strain curve can be obtained from the first derivative curve of the stress–strain curve. The boundary parameters of concrete compression damage cd after different temperature treatments are shown in From Equations (5), (15), and (16), combined with the damage evolution parameters in According to Equation (11) and considering the relationship between 2 nanoparticles is not significant. The strengthening coefficient can be defined to reflect the strength increase effect of nano-titanium dioxide on concrete. The strengthening coefficient can be obtained by fitting the peak strength change value of concrete before and after nano addition. The strengthening coefficient is defined as:fQ reflects the strengthening coefficient brought by the addition of nanomaterials to concrete under different temperatures. cf is the uniaxial compressive strength of ordinary concrete under different temperatures.The test curve and the theoretical curve of the constitutive equation for ordinary concrete established in the preceding section correspond very well. The stress–strain test curve for uniaxial compression of nano-modified concrete demonstrates that the trend of the stress–strain curve is consistent with that of ordinary concrete. The peak strength and high-temperature resistance of concrete were improved after adding nanometers. When the temperature ranges from 20 °C to 600 °C, the peak strength of NTC3 increases by 20%. In comparison, when the temperature exceeds 600 °C, the enhancement of the peak strength of the specimen by the addition of TiOfQ of the peak strength of NTC3 compared with ordinary concrete after different temperature treatments. fQ with respect to the processing temperature. The fitting degree of the quadratic polynomial is good, and the goodness of fit (R2) of the curve is 0.999. Therefore, this relationship can be used to predict the uniaxial compressive strength of NTC3 at different temperatures. The fitting relation is:2 nanopowder is consistent with the stress–strain curve trend of ordinary concrete, it only improves at the peak point. Therefore, the strengthening coefficient can be introduced on the basis of the second and third stages of the ordinary concrete constitutive equation established above, and the damage constitutive equation of NTC3 under different temperatures can be obtained. The damage constitutive model of NTC3 after high temperature and the derivation process of the damage evolution equation have been described in the previous section and will not be described here.Because the uniaxial compressive stress–strain curve of concrete after adding TiOET obtained from the stress–strain curve and the first derivative curve of the stress–strain curve. The tκ can be obtained by substituting it into Equation (15). Finally, the inflection point ctnκ of the stress–strain curve can be obtained from the first derivative curve of the stress–strain curve. The boundary parameters of NTC3 compression damage dc after different temperature treatments are shown in First, the Equation (16) can obtain the damage evolution equation of NTC3 under different temperatures, that isSecondly, the damage constitutive equation of NTC3 under different temperatures can be obtained by substituting (25) into Equation (5).In this paper, the mechanical properties of ordinary concrete and NTC3 after high temperature are analyzed and compared, mainly through experimental and theoretical analysis, and the damage constitutive model of ordinary concrete and NTC3 is established.(1)Ordinary concrete and NTC3 specimens were subjected to various temperatures ranging from 20 °C to 800 °C. Notably, the volume expansion of both materials was not apparent within the temperature range of 200 °C to 600 °C. Additionally, the surface color of the specimens transitioned from gray to brown. At a temperature of 800 °C, the specimen exhibits the formation of black spots on its surface and undergoes volumetric expansion.(2)With the increase of temperature, ordinary concrete’s average peak compressive resistance is further reduced. At 800 °C, the average peak compressive strength of ordinary concrete was 23.120 MPa, which decreased by 44.32% compared with the initial time, and the approximate secant modulus decreased to 13.072 GPa. Similar to ordinary concrete, after high-temperature treatment from 400 °C to 800 °C, the compressive strength of NTC3 decreased, and the average peak compressive strength of NTC3 was 24.610 MPa at 800 °C, a decrease of 50.69% compared with the initial time. It can be seen that the incorporation of nano titanium dioxide at lower than 600 °C can help the high-temperature resistance of concrete, and when it is higher than 600 °C, the mechanical properties of ordinary concrete and NTC3 compression are basically no different.(3)The stress–strain curves exhibited by ordinary concrete specimens subjected to uniaxial compression and titanium nanoconcrete specimens prior to and subsequent to high-temperature exposure exhibit similar shapes and characteristics. A constitutive relationship formula was established for the stress–strain curve of ordinary concrete specimens and NTC3 under uniaxial compression. A constitutive relationship for the uniaxial compressive stress–strain behavior of concrete was established, taking into account the variable of high-temperature damage. The constitutive relationship of concrete under high temperatures has been enhanced in accordance with the law of continuous change.


Finding the solution to the problem of the accumulating waste from the mining and processing industries, as well as reducing their carbon footprint, is among the most important tasks today. Within the construction industry, in the field of the production of building materials such as concrete, these problems may be solved through the use of waste and by saving the binder component. The purpose of this study is to substantiate the feasibility of using waste coal dust (CD) in concrete and cement–sand mortars as a partial replacement for cement. Test samples were made by partially replacing cement with CD in an amount from 0% to 10% in increments of 2% by weight. The following main characteristics were studied: mobility and density of mixtures, as well as density, compressive strength, bending strength and water absorption of concrete and mortars. X-ray diffraction and microscopic analysis methods were used in this work. The introduction of CD to replace part of the cement, up to 10%, did not have a significant effect on the density of concrete and mortar mixtures but reduced their workability. The best values of physical and mechanical characteristics were recorded for concrete and mortar with 4% CD. The increases in the compressive strength of concrete and mortars were 6.6% and 5.7%, and in flexural strength 6.1% and 5.6%, respectively. Water absorption decreased by 9.7% for concrete and by 9.3% for mortar. Currently, in many countries of the world, there is a big problem associated with the accumulation of waste from the mining and processing industries ,2,3,4,5,Coal dust can be classified as an inert mineral additive that does not fully react with the binder component in the concrete mixture. The main purpose of using additives of this type in concrete technology is the additional compaction of cement composites achieved by reducing porosity ,12. ThesIn studies ,26,27,28The use of coal dust in building materials and in particular in cement composites was considered in works ,9,10,34.The relevance of the research being carried out is confirmed by the high degree of risk of violating the environmental agenda due to the accumulation of coal dust. Such dust has a direct impact on the creation of a carbon footprint and the risk of not achieving sustainable development goals. As for the relevance of the scientific research of this work, it should be noted that the natural mechanism for the formation of concrete based on coal dust is complex . Coal duThe purpose of this study is to substantiate the feasibility of using waste coal dust (CD) in concrete and cement–sand mortars as a partial replacement for cement. It is important to prevent a decrease in the characteristics of concrete when using coal dust compared to control samples. This effect can definitely be called positive and, based on this, our scientific hypothesis is formulated as follows. Provided that optimal recipe–technological factors and parameters are observed when achieving the compatibility of the components of concrete containing coal dust and the conditions for the formation of a rational structure, it is possible to achieve high-performance indicators of concrete that are at least not inferior to analogous concrete made without the use of such dust. The environmental effect of this development is achieved by creating ways to dispose of waste such as coal dust. In the same context, there is also an economic effect that makes it possible to reduce the cost of concrete by saving an expensive component—cement. The technological effect should be to prevent a decrease in the technological properties of the created carbon–concrete mixture. The scientific novelty of the ongoing research is the acquisition of new fundamental and applied knowledge about the patterns of formation of the structure and properties of concrete based on coal dust, depending on rational recipe–technological factors and parameters, as well as the achievement of empirical values within certain limits and ranges for the specified parameters.In order to structure this research and present it in the form of a program, we first list the most key objects and parameters to be studied in order to study the effect of coal dust on cement composites. Based on the fact that coal dust is a finely dispersed modifier for cement composites, we will focus on such composites as cement mortars and heavy concrete. The choice of these research objects was made because these composites cover the widest field of application in modern construction. And in particular, in those areas where the extraction of the corresponding raw materials in the form of coal dust occurs, it is advisable to study these types of composites. At the same time, it is important to understand that it is not only hardened composites in finished form that are subject to research but also their fresh mixtures, which have a number of rheological and other technological characteristics. Thus, the experimental research program will include the most important and indicative properties and characteristics of mortar mixtures, cement mortars and concrete mixtures, that is, fresh concrete and hardened concrete. The parameters that determine the most important aspects of the influence of the addition of coal dust on the properties of all these mixtures and composites will be those properties that are strictly regulated in the regulatory and technical documentation and are the most important. These are the mobility of fresh composites and the mechanical strength characteristics of hardened composites.-Portland cement CEM I 52.5N (C)  ;-Crushed sandstone (CS) ;-Quartz sand (S) ;-Coal dust (CD) .The following raw materials were used as components for the manufacture of the experimental samples:The characteristics of the raw materials are presented in ® BV 3M (P)  was used as an additive to regulate the workability of the concrete and mortar mixtures.The plasticizer SikamentThe grain composition and X-ray diffraction pattern of coal dust are presented in According to the granulometric curve presented in Based on the results of XRD analysis of coal dust, we identified muscovite, quartz and chlorite phases, and an amorphous carbon phase was also present.The compositions of experimental concrete mixtures and mortars are presented in The production of concrete and mortar samples included the following main technological steps. First, all raw materials were measured in accordance with the recipe. The production of concrete mixtures was carried out in a laboratory concrete mixer. All raw materials were premixed in dry form, and then mixing water with a plasticizing additive was introduced. Next, the concrete mixture was mixed until homogeneous and placed into molds, which were then additionally vibrated for 60 s.A day later, all samples were removed from the molds and placed in a normal hardening chamber for 27 days at a temperature of 20 ± 2 °C and a relative humidity of 95%. The preparation of mortar samples was carried out in a similar way. After production, the mortar samples were stored in a normal hardening chamber for 27 days.No differences were observed in the quality or macrostructure of the two types of concrete samples and mortar. The only striking difference was the color of the samples. Samples with coal dust had a pronounced black color.-Laboratory concrete mixer BL-10 ;-Forms 2FK-100, 3FK-70, FB-400, 3FB40 ;-Normal curing chamber KNT-1 ;-Laboratory vibration platform .The main technological equipment for the production of the concrete and mortar samples was as follows:The experimental program is presented in A total of 36 cubes and 18 prisms of concrete as well as 18 cubes and 18 prisms of mortar were produced.D is the density of the concrete mixture (kg/m3); m1—mass of the container filled with compacted concrete (kg); m2—empty container mass (kg); V—capacity volume (m3).The fresh properties of the concrete mixture, such as density and workability, were determined in accordance with the methods of ,43. The The essence of the method for determining the settlement of a cone when testing a concrete mixture for mobility was to compact the prepared concrete mixture in the form of a truncated cone, and the measured distance to which the concrete mixture settled after removing the cone indicated the mobility of the concrete mixture.Determination of the compressive strength of concrete was carried out in accordance with the methods in ,47,48,49The density of hardened concrete was determined according to the method ,51 as thwm is the mass of the sample saturated with water (g); dm is the mass of the dry sample (g).The determination of water absorption of concrete samples was carried out in accordance with the requirements of regulatory documents ,53. The The determination of the fresh properties of mortar mixtures, as well as the density of the hardened mortar, their compressive strength, bending strength and water absorption was carried out in accordance following the requirements of ,55.The mobility of the mortar mixture was characterized by the depth of immersion of the reference cone into it, measured in centimeters. The immersion depth of the cone was estimated based on the results of the arithmetic average of two tests on different samples of the mortar mixture from one batch.3.The density of the mortar mixture was characterized by the ratio of the mass of the compacted mortar mixture to its volume and was expressed in kg/mThe strength of the hardened solution was determined using prism samples (bending strength) and then using half-prism samples obtained after destruction (compressive strength). The bending strength was calculated as the arithmetic mean of the two highest test results of three samples. The six prism halves obtained after the bending test were immediately subjected to a compression test. One half of the prism was placed between two plates in such a way that the side faces, which, during manufacturing, were adjacent to the walls of the mold, were on the planes of the plates, and the stops of the plates were tightly adjacent to the smooth end plane of the sample. The sample, together with the plates, was centered on the press base plate. The average rate of load increase during testing was (2.0 ± 0.5) MPa/s. The compressive strength of an individual sample was calculated as the quotient of the breaking load divided by the working area of the plate. The compressive strength was calculated as the arithmetic mean of the four highest test results of six samples.The density of the solution was determined by testing cube samples with an edge of 70 mm. The samples were stored for 28 days in a normal hardening chamber at a relative air humidity of at least 95% and a temperature of (20 ± 2) °C.The water absorption of the solution was determined using samples that were placed in a container filled with water in such a way that the water level was approximately 50 mm above the top level of the laid samples. Samples were weighed after every 24 h of water absorption. In general, the test parameters were the same as when determining the water absorption of concrete samples .Particle size gradations of components of concrete and mortar were determined using a Microsizer model 201C .The chemical composition of fine coal dust was determined in accordance with the requirements of GOST R 55661-2013: Solid mineral fuel. Determination of ash content followed method NSAM 138-X: Chemical methods, Method of quantitative chemical analysis. Accelerated methods for determining rock-forming elements in rocks and ores followed NSAM 3-X methodology. Determination of the total sulfur content in rocks, ores and products of their processing was completed using the gravimetric method. For this purpose, the following equipment was used: analytical balance CAS CAUX-220 , muffle furnace LOIP , low-temperature furnace SNOL  and spectrophotometer UNICO 2100 .X-ray diffraction analysis was performed on an ARLX’TRA diffractometer using the characteristic radiation of a copper anode . The PDF-2 X-ray database was used to identify serpentinite phases and minor minerals.Cured concrete and mortar samples retained a significant difference in color between the control composition and the CD composition. The appearance of the samples did not differ significantly, but in the control mortar samples, there were quite large surface pores.The results of this study of fresh properties of concrete and mortar mixtures are presented in x in equation) presented in R2:The dependence of the density of the concrete mixture on the CD content (The dependence of the mobility of the concrete mixture on the CD content (%) presented in 3 to 2187 kg/m3. As for workability, according to [According to the results of the fresh properties of concrete mixtures, it was found that the density of concrete mixtures with an increase in the percentage of replacing part of the cement with coal dust decreases slightly and varies from 2207 kg/mrding to , it variThe results of studying the fresh properties of mortar mixtures are presented in The dependence of the density of the mortar on the CD content (%) presented in The dependence of mortar mobility on CD content (%) presented in For the properties of fresh mortar, a similar situation is observed here as with concrete mixtures, namely, with an increase in the percentage of replacing part of the cement with coal dust, the density of the mortar mixtures also decreases slightly. The workability parameter of mortar mixtures also decreases but is within the same brand . When th® BV 3M into concrete mixtures and mortars with coal dust allows them to maintain their workability within the same grade.A decrease in the mobility of concrete and mortar mixtures when replacing part of the cement with coal dust is associated with increasing water demand. Fine particles of coal dust in concrete and mortar mixtures act as a filler. And as is known, finely dispersed mineral filler additives in cement composites can significantly increase the water–cement ratio of the mixture, which will subsequently lead to a decrease in strength characteristics. However, the use of these types of mineral additives in combination with a plasticizer will eliminate this problem and maintain the water–cement ratio and workability characteristics of the mixtures within the required limits . Thus, tThe results of determining the physical and mechanical characteristics of concrete and mortars are shown in The dependence of concrete density on CD content (%) presented in The dependence of the density of the cement mortar on the CD content (%) presented in 3 to 2256 kg/m3, and the density of the mortar from 2078 kg/m3 to 2093 kg/m3.From To distinguish between the properties of concrete and mortar, the symbols C (for concrete) and M (for mortar) were added to the designations for equations.CR) on CD content (%) presented in The dependence of the compressive strength of concrete  on CD content (%) presented in The dependence of the compressive strength of the mortar  presented in According to The dependence of water absorption of the mortar on the content of CD (%) presented in The dependence of the water absorption of the mortar on the CD content has a similar trend as the dependence of the change in water absorption of concrete. At CD quantities of 2% and 4%, the water absorption of the mortar decreased by 3.2% and 9.3%, respectively. At quantities of 6%, 8% and 10%, coal dust negatively affected the water absorption of the mortar. At 6% CD, water absorption increased by 3.0%, at 8% CD by 10.4%; and at 10% CD by 16.9%. The decrease in water absorption is associated with compaction of the structure of the hardened cement paste due to an increase in the volume concentration of cementing products of binder hydration and a decrease in pore volume [Changes in the physical and mechanical characteristics of concrete and mortar with different CD contents are presented as a percentage compared to the control composition in XRD analysis of concrete with control composition and concrete with 4% CD was also carried out. X-ray diffraction analysis of the composites is presented in Based on the results of XRD analysis of concrete of the control composition, the phases of portlandite, illite, anorite, calcite and quartz were identified. XRD analysis of concrete with 4% CD identified phases such as larite, albite, portlandite, calcite and quartz. Thus, the introduction of coal dust into concrete contributes to a change in its phase composition and the appearance of such phases as larite and albite.The results obtained during this study indicate a number of achievements and need to be compared with the results of other authors obtained earlier in order to clarify the scientific novelty and scientific and practical value of this study.So, in the course of this study, the relationships between the composition and properties of concrete and mortars based on coal dust waste were determined. The structure formation of such concrete largely depends on the following aspects. It is important to understand the role of the carbon modifier in the composition of the cement composite. If the applied carbon modifier is intended to replace part of the binder component, then, on the one hand, there is a risk of not achieving the required strength in such aspects as a decrease in the amount of binder that forms the cement coating of inert particles; an increase in fine components in the material, which additionally require wetting with water; and an increase in the wetting surface, which, in turn, leads to the risk of undercompaction and underformation of the composite structure.Based on the results of experimental studies, it was established that with the optimal amount of replacement of part of the cement with coal dust, it is possible to obtain high-quality and environmentally efficient concrete and mortars. It should be noted that, based on the results of the literature review, no studies were found on the use of coal dust with a similar chemical composition as a partial replacement for binders in the technology of cement composites. However, there are a number of studies ,25,26,27The use of coal dust of similar origin in the study  in smallThus, in terms of replacing the binder, there are two types of risk: the risk of failure to achieve strength indicators and the risk of insufficient wetting of the inert components and hence failure to achieve uniformity of the structure ,60,61, w(1)It was established that coal dust, introduced to replace part of the cement, negatively affects the mobility of concrete and mortar mixtures. However, the introduction of a plasticizing additive allows one to adjust the mobility value of concrete and mortar mixtures and maintain it within the same brand.(2)Replacing part of the cement with coal dust by up to 10% does not have a significant effect on the change in the density of concrete and mortar mixtures or in hardened composites.(3)Compared to the control composition, concrete samples with 4% coal dust showed greater efficiency: increases in compressive and flexural strength were 6.6% and 6.1%, and water absorption decreased by 9.7%.(4)The increases in compressive and flexural strength of the mortar with 4% coal dust content compared to control samples were 5.7% and 5.6%, and water absorption decreased by 9.3%.(5)The most effective amount of coal dust, introduced instead of part of the cement, was 4%. It was possible to use coal dust in an amount of 6% without a significant loss of strength characteristics for both concrete and mortars.(6)The use of coal industry waste is potentially effective in the construction sector due to its mineral activity and geographical accessibility. The prospect of effective use of coal dust in appropriate, rationally selected quantities in concrete production was confirmed.The rheological and physical–mechanical characteristics of concrete and mortar with different contents of coal dust were developed and studied. This study used normative tests and X-ray diffraction analysis. Based on the results obtained in this study, the following conclusions were drawn:


This study presents a novel approach to assessing the setting time of concrete using the electro-mechanical impedance (EMI) sensing technique. The proposed method involves the continuous monitoring of EMI changes by embedding a piezoelectric (PZT) sensor directly in the concrete. A comparative analysis was conducted with the conventional penetration resistance test, which utilizes mortar samples extracted from the concrete. As a result of the experiment, the time deviation rate of the setting time was more than 10% in the penetration resistance test using the mortar sample extracted from the same concrete, whereas the time deviation rate of the setting time was up to 1.77% in the EMI sensing technique using the same concrete specimen. This highlights the effectiveness and potential of the EMI sensing technique for an improved evaluation of concrete setting time. Cement is a material that gradually hardens and becomes a solid structure when it comes into contact with water. During the process of cement hydration, a phase transition occurs from a fluid state to a solid state, which is known as setting . The setThe Vicat needle test  and peneRecently, as part of non-destructive testing, a method for evaluating the setting of cementitious materials using an electro-mechanical impedance (EMI) sensing technique has been proposed ,14,15,16In previous studies ,14,15,16In this study, the EMI evolution of the PZT sensor directly embedded in the concrete was continuously monitored to assess the setting time of the concrete. The setting times assessed using the EMI sensing technique were compared with the setting times assessed using the penetration resistance test method, which is a conventional test method. This investigation explored the limitations of the penetration resistance test in accurately evaluating concrete setting times. Moreover, this study comprehensively assessed the suitability of the EMI sensing technique for evaluating the setting of concrete, which is a more intricate mixture than simple cement paste or mortar.KS L 5201 type I  ordinarThe penetration resistance test was conducted according to ASTM C 403 [A penetration needle with an appropriate cross-sectional area was placed in contact with the surface of the mortar, and the needle was penetrated to a depth of 25 mm. The penetration resistance was calculated by dividing the load applied when the needle penetrates to a depth of 25 mm by the cross-sectional area of the needle. The initial measurement of penetration resistance was conducted 1 h after the contact between cement and water. The penetration resistance was measured every hour until the penetration resistance was less than 3.5 MPa, and the penetration resistance was measured every 30 min from the time when the penetration resistance exceeded 3.5 MPa. The time penetration resistance data obtained from the penetration resistance test was subjected to regression analysis using an exponential curve fitting. Using the equation obtained from the regression analysis, the time when the penetration resistance reached 3.5 MPa was defined as the initial setting time, while the time when the penetration resistance reached 27.6 MPa was defined as the final setting time [In this study, the EMI evolution of the PZT sensor embedded in concrete samples was monitored to assess the setting time of concrete using the EMI sensing technique. The EMI signal was monitored using a buzzer-type PZT sensor . To prevent any short-circuiting caused by ions dissolved in the fresh concrete, a thin coating of acrylic resin was applied to the surface of the PZT sensor . Figure The concrete samples were cast into a cylindrical container with a diameter of 150 mm and a height of 150 mm, and the PZT sensor was embedded in the center of each container. Three concrete samples were prepared from the same batch of concrete.The initial measurement of the EMI of the PZT sensor was conducted 1 h after the contact between cement and water, and subsequent measurements were conducted every 10 min for 12 h. The EMI of the PZT sensor was measured using a commercial LCR (Inductance (L), Capacitance (C), and Resistance (R)) meter , and all measured data were recorded using a personal computer through a GP-IB interface connected to the LCR meter. The measurement frequency range for the EMI of the PZT sensor was set from 20 kHz to 250 kHz, with a measurement frequency interval of 50 Hz. As shown in In previous studies ,14,15,16The disappearance of the EMI resonant peak is attributed to the increased stiffness of material in contact with the PZT sensor, which dampens the free vibration of the PZT sensor ,21. As tThe penetration resistance test, which uses mortar samples extracted from concrete, is not a direct method for measuring the setting time of concrete. As shown in the experimental results, the extraction of mortar from concrete through sieving can result in variations in the water/cement ratio and the cement/fine aggregate ratio, leading to differences in the setting time compared to pure mortar. In contrast, the EMI sensing technique offers a direct approach to assess the setting time of concrete. By embedding a PZT sensor directly into the concrete sample, the EMI sensing technique allows for the change in the stiffness of the concrete itself to be monitored during the hydration process. Through measuring and analyzing the variations in concrete stiffness using the PZT sensor, the EMI sensing technique provides an effective and accurate means of evaluating the setting time of concrete. This direct measurement approach provides valuable insights into the behavior of the concrete during the setting process.This study investigated the evaluation of concrete setting times through two distinct approaches: the conventional penetration resistance test utilizing mortar extracted from concrete, and the electro-mechanical impedance (EMI) sensing technique employing directly embedded piezoelectric (PZT) sensors within the concrete.The penetration resistance test showed limitations due to the procedure of extracting mortar from concrete using sieving. This extraction process has the potential to introduce variations in the ratios of water–cement and cement–fine aggregate, which in turn can result in disparities in setting times when compared to pure mortar samples. The experimental results highlighted that even for mortar extracted from the same concrete batch, the time deviation rate of the setting time exceeded 10%.On the other hand, the EMI sensing technique offers a direct measurement approach that overcomes the limitations of the penetration resistance test, providing more reliable and comprehensive results for evaluating the setting time of concrete. This approach entailed the direct embedding of PZT sensors within concrete samples, enabling the real-time monitoring of stiffness changes during the hydration process. The EMI sensing technique harnessed the phenomenon of resonant peak frequency shifts, which responded to fluctuations in material stiffness. The experimental results revealed that when the curing time of concrete samples from the same batch was evaluated using the EMI sensing technique, the observed time deviation rate fell within the measurement deviation range, with a maximum value of 1.77%.Therefore, the EMI sensing technique with an embedded PZT sensor presents a promising method for accurately evaluating the setting times of concrete. Further research and development in this area can contribute to the advancement of concrete quality control and construction practices.


Although one of the main drivers of antimicrobial resistance is inappropriate antibiotic prescribing, there are limited resources to support the surveillance of antibiotic consumption in low-income countries. In this study, we aimed to assess antibiotic use and consumption among medical patients of two hospitals in different geographic regions of Sierra Leone.This is a cross-sectional study of adult (18 years or older) patients receiving medical care at two hospitals  between March 2021 and October 2021. After admission to the medical or intensive care unit, patients were sequentially recruited by a nurse from each hospital. Demographic and clinical characteristics and information on the dose of antibiotics, their routes, and frequency of administration and duration were collected using a questionnaire adapted from previous studies and encrypted in EpiCollect software . A physician reviews and verifies each completed questionnaire. Data analysis was done using STATA version 16.The mean age of the 468 patients evaluated in this study was 48.6 years. The majority were women  and treated at MGH . Clinical diagnosis of bacterial infection was made in only 180 (38.5%) patients. Regardless of the diagnosis, most  patients received at least one antibiotic. Of a total 813 doses of antibiotics prescribed by the two hospitals, 424 (52.2%) were administered in MH. Overall, antibiotic consumption was 66.9 defined daily doses (DDDs) per 100 bed-days, with ceftriaxone being the most commonly used antibiotic . The ACCESS and WATCH antibiotics accounted for 18.9 DDDs per 100 bed-days (28.2%) and 48.0 DDDs per 100 bed-days (71.7%), respectively. None of the patients were prescribed a RESERVE antibiotics. The antibiotic consumption was lower in MH (61.3 DDDs per 100 bed-days) than MGH (76.5 DDDs per 100 bed-days).Antibiotic consumption was highest with ceftriaxone, followed by levofloxacin and metronidazole. Given the high rate of consumption of antibiotics in the WATCH category of the AWaRe classification, there is a need to initiate surveillance of antibiotic consumption and establish hospital-based antibiotic stewardship in these settings. Owing to its increasing burden, antimicrobial resistance (AMR) is a major threat to the health, social and economic status of countries around the world . The gloAMR is a complex phenomenon that affects human health in community and hospital settings and increases healthcare expenditures, prolongs hospital stays, and worsens morbidity and mortality . One of Even with this development, many LMICs have limited capacity to initiate antimicrobial consumption surveillance and implement antimicrobial stewardship (AMS) activities needed to reduce inappropriate antibiotic consumption –10. The Despite these resources and the fact that previous observational studies in Sierra Leone have identified ingrained challenges in the response against AMR –19, therHence, this study set out to (a) determine the prevalence antibiotic use among patients admitted in medical wards of two hospitals in Sierra Leone (b) evaluate antibiotic consumption using the 2021 ATC/DDD classification, and (c) identify patterns of antibiotic consumption using the AWaRe framework.The study used a cross-sectional design to assess antibiotic use and consumption among patients admitted in the medical wards of two hospitals in Sierra Leone.The study included all adult inpatients aged 18 years or older admitted to the Medical Wards and intensive care units (ICU) of two hospitals between March 2021 and October 2021.We selected 34 Military Hospital (MH) and Makeni Government Hospital (MGH) for the study as they are in two different geographic regions and their level of service provision and infrastructure is likely representative of many secondary or tertiary hospitals in Sierra Leone. Both hospitals provide tertiary services. MH is located in Freetown, the capital of Sierra Leone, with a population of one million and 181 beds. MGH is a regional hospital, located approximately 170 km from Freetown, has a catchment population of 606,544 people (approximately 8.6% of Sierra Leone’s population) and 207 beds . ApproxiThe two hospitals have laboratories with capacity to perform hematology and biochemistry investigations but lacks microbiology diagnostic capacity at the time of data collection. Patients have access to available diagnostic services at out-of-pocket costs despite financial hardship.There are neither Infectious Disease Physicians nor Microbiologists to guide rational antibiotic prescribing in these hospitals. Although there were drugs and therapeutic committees in these hospitals at the time of data collection, they did not provide antimicrobial stewardship interventions such as dedicated leadership, prescriber education, and audit of prescription practices. Furthermore, there are no existing antimicrobial guidelines or formulary to leverage antibiotic prescribing practices.The diagnoses of patients who were prescribed antibiotics were divided into:Clinical bacterial infection: when a patient develops an infection that is clinically suspected to be of bacterial origin and thus requires empiric antibiotics.No clinical bacterial infection/sole diagnosis of tuberculosis; these patients did not require antibiotics because the diagnosis they were being treated for was either unspecified or not a clinical bacterial infection other than tuberculosis. Therefore, it is inappropriate to prescribe antibiotics to patients in these categories. The sub-categories of this group include: ‘No diagnosis’ when there was absence of a diagnosis.‘Non-bacterial process with HIV’ when an HIV patient had either a non-bacterial infective process or non-infective process.‘Non-infective process’ when patient had a non-communicable disease without evidence of infection ‘Non-bacterial infective process’ when patient had an infection which was designated as non-bacterial in origin andSole diagnosis of tuberculosis.The WHO AWaRe framework and the 2021 ATC Classification system was used to evaluate antibiotic use patterns as listed in the WHO Model List of Essential Medicine , 16.The DDDs were calculated by multiplying the quantity field by DDD conversion factor field on the 2022 version of the ATC/DDD index using the formula DDD/100 bed days = Number of units administered in a given period (milligram) ×100/DDD (milligram)×number of days in the period×number of beds×occupancy index . A bed-dAfter admission to the medical or intensive care unit, patients were sequentially recruited by a nurse from each hospital who was trained in the assessment of antibiotic use. Demographic and clinical characteristics were collected at baseline using a questionnaire adapted from a previous study and encrypted in EpiCollect software  , 20. SubAfter collection, the data were extracted into Microsoft Excel, cleaned, coded, and then transferred into Stata version 16 (StataCorp LLC) for analysis. Descriptive statistics such as frequencies and percentages were used to present demographic and clinical characteristics of study participants, as well as antibiotic consumption.Of 468 patients enrolled in the study, 241 (51.7%) were women. The mean age of the patients was 48.6 years . The majority were treated at MGH  (Table Only 180 (38.5%) patients were clinically diagnosed with a bacterial infection, of which pneumonia  and gastroenteritis and other gastrointestinal infections 59, 12.6%) were the most common diagnostic categories for which antibiotics were prescribed  of the two hospitals, 424 (52.2%) were made in MH , metronidazole 235, 28.9%), and levofloxacin  , whereas consumption for WATCH antibiotics was 48.0 DDDs per 100 bed-days (71.7%). No RESERVE antibiotics were prescribed. The antibiotic consumption was lower in MH (61.3 DDDs per 100 bed-days) than MGH (76.5 DDDs per 100 bed-days), but the consumption of the WATCH antibiotics was higher in MH (81.7%) than MGH  and in surgery (92%) . In NigeOnly 38.5% of the reasons for prescribing antibiotics were suspected bacterial diseases. Whether this presumptive diagnosis represents a true bacterial infection is a question that could be answered in future studies. Most importantly, many patients with non-bacterial diseases or without a documented diagnosis have been inappropriately prescribed an antibiotic, similar to studies in Japan and India , 26. AntSimilar to previous studies , 22, theWHO recommends that the narrow-spectrum ACCESS antibiotics should be used more frequently to reduce the selection pressure associated with the broad-spectrum WATCH and RESERVE antibiotics . In our Our study has strengths and limitations. Although the findings of this study are not nationally representative, it is the first study in Sierra Leone to describe antibiotic use patterns and consumption among medical patients at two hospitals in different geographic regions. Hence, its evidence has important policy implications for antibiotic stewardship programs. We did not clinically verify the diagnosis of bacterial and non-bacterial diseases made by the clinicians at the bedside. Therefore, our findings may not represent the true picture of the common diagnoses that lead to antibiotic prescriptions in these hospitals.Our study showed a high prevalence of antibiotic prescribing in two hospitals in different geographic regions of Sierra Leone. Antibiotic consumption was highest with ceftriaxone, followed by levofloxacin and metronidazole. Given the high rate of consumption of antibiotics in the WATCH category of the AWaRe classification, there is a need to initiate surveillance of antibiotic consumption and establish facility-based antibiotic stewardship in these hospital settings.