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Water-soluble carboxymethyl chitin (CMCT) 1a–b, and chitosan (CMCS) 2a–b derivatives were synthesized and evaluated for antibacterial activity. The synthesized compounds were characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Thermal properties of the synthesized compounds were studied by thermogravimetric analysis (TGA) and their surface morphologies examined by scanning electron microscopy (SEM). Antibacterial activity of the chitosan (CS) 2 and the synthesized derivatives were tested against both gram-negative (Shigella flexneri, Enterococcus faecalis, Pseudomonas aeruginosa, Klebsiella pneumoniae, Vibrio paraheamolyticus) and gram-positive (Staphylococcus aureus, Bacillus subtilis, Bacillus cereus) bacterial strains. CS 2 shows antimicrobial activity against all tested pathogenic bacteria, whereas CMCS 2a shows antimicrobial activity against Shigella flexneri, Bacillus cereus, and Bacillus subtilis. CMCS 2b shows antimicrobial activity against Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus. CMCT 1a only shows antimicrobial activity against Bacillus subtilis and 1b shows antimicrobial activity against Vibrio paraheamolyticus and Bacillus cereus.

Abstract This study reports on performance enhancement of a Cu2ZnSnS4 solar cell introducing Sb2S3 as hole transport layer (HTL) along WS2 as buffer layer. We have investigated photovoltaic (PV) characteristics by utilizing SCAPS‐1D. A comparative analysis on PV performances between conventional CZTS/CdS and proposed Ni/Sb2S3/CZTS/WS2/FTO/Al solar cells is presented. It is revealed that “spike like” band structure at the CZTS/WS2 interface having smaller conduction band offset makes it potential alternative to commonly used CdS buffer. This report also evaluates that the Sb2S3 as an HTL inserted at the rear of CZTS enhances performances by reducing carrier recombination at back interface with appropriate band alignment. The impacts of thickness, carrier concentration of different layers, and bulk defect density in CZTS as well as the interface defects on cell outputs are analyzed. The influences of temperature, work function, and cell resistances are also examined. Optimum absorber thickness of 1.0 μm along doping density of 1017 cm−3 is selected. A maximum efficiency of 30.63% is achieved for the optimized CZTS cell. Therefore, these results suggest that Sb2S3 as HTL and WS2 as buffer layer can be employed effectively to develop highly efficient and low‐cost CZTS solar cells.

Abstract Background The safety of health care workers (HCWs) in Bangladesh and the factors associated with getting COVID-19 have been infrequently studied. The aim of this study was to address this gap by assessing the capacity development and safety measures of HCWs in Bangladesh who have been exposed to COVID-19 and by identifying the factors associated with respondents’ self-reported participation in capacity development trainings and their safety practices. Methods This cross-sectional study was based on an online survey of 811 HCWs working at 39 dedicated COVID-19 hospitals in Bangladesh. A pretested structured questionnaire consisting of questions related to respondents’ characteristics, capacity development trainings and safety measures was administered. Binary logistic regressions were run to assess the association between explanatory and dependent variables. Results Among the respondents, 58.1% had been engaged for at least 2 months in COVID-19 care, with 56.5% of them attending capacity development training on the use of personal protective equipment (PPE), 44.1% attending training on hand hygiene, and 35% attending training on respiratory hygiene and cough etiquette. Only 18.1% reported having read COVID-19-related guidelines. Approximately 50% of the respondents claimed that there was an inadequate supply of PPE for hospitals and HCWs. Almost 60% of the respondents feared a high possibility of becoming COVID-19-positive. Compared to physicians, support staff [odds ratio (OR) 4.37, 95% confidence interval (CI) 2.25–8.51] and medical technologists (OR 8.77, 95% CI 3.14–24.47) were more exhausted from working in COVID-19 care. Respondents with longer duty rosters were more exhausted, and those who were still receiving infection prevention and control (IPC) trainings were less exhausted (OR 0.54, 95% CI 0.34–0.86). Those who read COVID-19 guidelines perceived a lower risk of being infected by COVID-19 (OR 0.44, 95% CI 0.29–0.67). Compared to the respondents who strongly agreed that hospitals had a sufficient supply of PPE, others who disagreed (OR 2.68, 95% CI 1.31–5.51) and strongly disagreed (OR 5.05, 95% CI 2.15–11.89) had a higher apprehension of infection by COVID-19. Conclusion The findings indicated a need for necessary support, including continuous training, a reasonable duty roster, timely diagnosis of patients, and an adequate supply of quality PPE.

This study investigated the prebiotic functions of Konjac root powder (KRP) when added to chocolate milk (ChM) enriched with 2% of free or microencapsulated lactic acid bacteria (FLAB or ELAB). The effects of different concentrations of KRP (0%, 2% and 4%) and refrigerated storage time on the physical, chemical and microbiological characteristics of this chocolate milk were examined. The results show that pH significantly declined (p < 0.05), while titratable acidity increased in all ChM samples with KRP and FLAB or ELAB during refrigerated storage. The pH values ranged from 6.0 ± 0.03 in samples enriched ELAB and 4% KRP to 6.33 ± 0.03 in ChM enriched with FLAB and 2% KRP. Viscosity of ChM was affected mainly by the added amounts of KRP and storage time. The largest viscosity (5500 cP) was observed in all samples containing 4% KPR on day zero and decreased significantly (p < 0.05) over storage time to reach 2800 cP in ChM samples containing 0% LAB and 4% KRP after 21 days of storage. Changes in LAB counts proved the initial hypothesis that KRP could act as prebiotics in the presence of LAB using chocolate milk as a carrier. The initial LAB counts in inoculated samples on day zero of refrigeration storage were not significantly different (p > 0.05) among all treatments. However, ChM enriched with 2% and 4% KRP and ELAB revealed significantly (p < 0.05) larger LAB counts (4.91 ± 0.78 and 5.0 ± 0.57 log CFU/mL, respectively) than the control (3.85 ± 0.55 log CFU/mL) after 21 days of storage.

Pollutant dispersion in urban areas has been a key concern in densely populated cities because pollutants can negatively impact human health and the environment. Topography and urban obstructions, such as buildings, greatly affect the atmospheric fluid flow, leading to the dispersion process. Street canyons are usually formed in highly populous cities due to the close proximity of buildings to streets to serve commercial purposes. It can also be termed as pollutant traps that exact adverse effects on urban life. Street canyons cause changes in pollutant dispersion, particularly in the case of vehicle exhaust air pollutants, which cannot be transported by the wind owing to the presence of buildings acting as impediments regardless of the wind flow. Hence, it is imperative to completely understand the behavior of pollutants within the confined urban surroundings for further improving the urban air quality. This study explores the effects of street canyons on the busiest street of Dhaka city in Bangladesh. The Reynolds-averaged Navier–Stokes based dispersion model is used to investigate the air quality phenomenon. Building height, width, building distance, and road width have been taken into consideration in the simulation. It is expected that the findings of the current study would be helpful for urban planners and designers of Dhaka city.

Abstract Background Improved methods with better separation and concentration ability for detection of foodborne pathogens are in constant need. The aim of this study was to evaluate microplate immunocapture (IC) method for detection of Salmonella Typhi, Shigella flexneri and Vibrio cholerae from food samples to provide a better alternative to conventional culture based methods. Results The IC method was optimized for incubation time, bacterial concentration, and capture efficiency. 6 h incubation and log 6 CFU/ml cell concentration provided optimal results. The method was shown to be highly specific for the pathogens concerned. Capture efficiency (CE) was around 100% of the target pathogens, whereas CE was either zero or very low for non-target pathogens. The IC method also showed better pathogen detection ability at different concentrations of cells from artificially contaminated food samples in comparison with culture based methods. Performance parameter of the method was also comparable (Detection limit- 25 CFU/25 g; sensitivity 100%; specificity-96.8%; Accuracy-96.7%), even better than culture based methods (Detection limit- 125 CFU/25 g; sensitivity 95.9%; specificity-97%; Accuracy-96.2%). Conclusion The IC method poses to be the potential to be used as a method of choice for detection of foodborne pathogens in routine laboratory practice after proper validation.

Abstract Background Salmonella spp. is one of the most common pathogens associated with fresh produce related foodborne illness. This study aimed to determine Salmonella spp. contamination level in betel leaf, internalization potential and possible decontamination process. Results A total of 77% betel leaf sample collected from local market was found to be contaminated with Salmonella spp. Of all the Salmonella spp. isolated and identified, 28.5% belong to Salmonella enterica subsp. enterica serovar Enteritidis, 19.5% belong to Salmonella Typhimurium, 15.6% to Salmonella Paratyphi, 10.4% to Salmonella Schottmuelleri, 9.1% to Salmonella Gallinarum, 10.4% to Salmonella Choleraesuis and 6.5% belong to Salmonella Bongori. Internalized Salmonella spp. showed moderate resistance to commonly used antibiotics. Treatment with common surface food disinfectants could not remove Salmonella spp. completely from betel leaf indicating the possibility that the bacteria may be in internal tissue of the leaf. Assessment of internalization potential showed that Salmonella spp. isolated from inner part of betel leaf pose better internalization potential (6.7–7.4 logCFU/gm) comparing with ATCC (American Type Culture Collection) strains (0.86–0.6 logCFU/gm). The isolates also showed better survivability in internalized condition, biofilm formation ability and motility than ATCC strains. Prevalence and expression of invasion (sefA and invA) and type 3 secretion system (TTSS) associated genes (hila, avrA and sopE) were high in internalized Salmonella isolates. Commercial disinfectants as well as H2O2 were found to have poor efficacy (log reduction around 2 CFU/gm) against internalized Salmonella. Ozonated water showed better decontamination efficiency (log reduction around 3 CFU/gm) whereas ethanolic extract of Terminalia arjuna stem bark showed higher decontamination (log reduction around 4.5 CFU/gm) of internalized Salmonella. Conclusion Salmonella spp. can ingress into betel leaf and better decontamination treatment is needed to be established.

Identification and classification of the microorganisms are of utmost importance in the field of environmental, industrial,medical and agricultural microbiology, and microbial ecology. Traditional phenotype-based methods encounter manychallenges and shortcomings which limit their usability. Molecular methods offer better solutions in identifying and characterizing microorganisms. Several DNA fingerprinting methods have been developed and are in use already. In principle, mostof these methods are based on PCR and restriction site analysis. Some of these methods are still not economic in use andrequire huge set-up cost. Continuous research is going on around the world to improve the methodology and applicability ofthese methods as well as to make them economic in use.

This cross sectional study was conducted in different medical college hospitals of Dhaka city during the months of Jan-March 2009. The objective of this study was to find out the awareness level on organ transplantation amongst the teachers, doctors and nurses working in these medical college hospitals and 1st to 5th year students. A structured questionnaire was given to the respondents. The total number of respondents was 462 of which 103 (22.3%) were doctors, 268 (58%) were medical students and 91 (19.7%) were nurses. Among the study group 31.4% knew that there was an organ transplantation law in Bangladesh and 16.5% said that there was no such law whereas 52.2% had no idea whatsoever about the law. Of the respondents 33.8% were willing to donate their organs after death, 41.6% did not want to donate and 24.2% were not sure. This study revealed that there was a lack of understanding regarding the religious views on organ transplantation. Only 37.1% of respondents thought that were was no religious objection to organ transplantation whereas 27.1% felt that there was religious objection while 35.7% were not sure. The study shows that there is significant lack of awareness regarding organ transplantation issues among the health care professionals and medical students in Bangladesh. The dictates of religion on this matter were also not clear to most of the respondents. Ibrahim Med. Coll. J. 2009; 3(2): 55-58

This study evaluated the viability of encapsulated Lactobacillus delbrueckii subsp. bulgaricus in chocolate during storage and in-vitro gastrointestinal transit. Flavonoid contents and short chain fatty acids (SCFAs) production during gastrointestinal transit were also assessed. Encapsulated L. delbrueckii subsp. bulgaricus survived well in chocolates >7 logs both after 120 days of storage at 4 °C and 25 °C, and during in-vitro gastrointestinal transit. The release of SCFAs through in-vitro gastrointestinal digestion and colonic fermentation revealed that probiotic-chocolates could be an excellent source of nutrients for the gut microbiota. Encapsulated probiotic in chocolates with 70% cocoa produced significantly (P

This study reports on performance enhancement of a Cu2ZnSnS4 solar cell introducing Sb2S3 as hole transport layer (HTL) along WS2 as buffer layer. We have investigated photovoltaic (PV) characteristics by utilizing SCAPS‐1D. A comparative analysis on PV performances between conventional CZTS/CdS and proposed Ni/Sb2S3/CZTS/WS2/FTO/Al solar cells is presented. It is revealed that "spike like" band structure at the CZTS/WS2 interface having smaller conduction band offset makes it potential alternative to commonly used CdS buffer. This report also evaluates that the Sb2S3 as an HTL inserted at the rear of CZTS enhances performances by reducing carrier recombination at back interface with appropriate band alignment. The impacts of thickness, carrier concentration of different layers, and bulk defect density in CZTS as well as the interface defects on cell outputs are analyzed. The influences of temperature, work function, and cell resistances are also examined. Optimum absorber thickness of 1.0 μm along doping density of 1017 cm−3 is selected. A maximum efficiency of 30.63% is achieved for the optimized CZTS cell. Therefore, these results suggest that Sb2S3 as HTL and WS2 as buffer layer can be employed effectively to develop highly efficient and low‐cost CZTS solar cells. [ABSTRACT FROM AUTHOR]

Solitary waves, inherent in nonlinear wave equations, manifest across various physical systems like water waves, optical fibers, and plasma waves. In this study, we present this type of wave solution within the integrable Mikhailov–Novikov–Wang (MNW) equation, an integrable system known for representing localized disturbances that persist without dispersing, retaining their form and coherence over extended distances, thereby playing a pivotal role in understanding nonlinear dynamics and wave phenomena. Beyond this innovative work, we examine the stability and modulation instability of its gained solutions. These new solitary wave solutions have potential applications in telecommunications, spectroscopy, imaging, signal processing, and pulse modeling, as well as in economic systems and markets. To derive these solitary wave solutions, we employ two effective methods: the improved Sardar subequation method and the (℧′/℧, 1/℧) method. Through these methods, we develop a diverse array of waveforms, including hyperbolic, trigonometric, and rational functions. We thoroughly validated our results using Mathematica software to ensure their accuracy. Vigorous graphical representations showcase a variety of soliton patterns, including dark, singular, kink, anti-kink, and hyperbolic-shaped patterns. These findings highlight the effectiveness of these methods in showing novel solutions. The utilization of these methods significantly contributes to the derivation of novel soliton solutions for the MNW equation, holding promise for diverse applications throughout different scientific domains.

The time-fractional coupled Drinfel’d–Sokolov–Wilson (DSW) equation is pivotal in soliton theory, especially for water wave mechanics. Its precise description of soliton phenomena in dispersive water waves makes it widely applicable in fluid dynamics and related fields like tsunami prediction, mathematical physics, and plasma physics. In this study, we present novel soliton solutions for the DSW equation, which significantly enhance the accuracy of describing soliton phenomena. To achieve these results, we employed two distinct methods to derive the solutions: the Sardar subequation method, which works with one variable, and the Ω′Ω, 1Ω method which utilizes two variables. These approaches supply significant improvements in efficiency, accuracy, and the ability to explore a broader spectrum of soliton solutions compared to traditional computational methods. By using these techniques, we construct a wide range of wave structures, including rational, trigonometric, and hyperbolic functions. Rigorous validation with Mathematica software 13.1 ensures precision, while dynamic visual representations illustrate soliton solutions with diverse patterns such as dark solitons, multiple dark solitons, singular solitons, multiple singular solitons, kink solitons, bright solitons, and bell-shaped patterns. These findings highlight the effectiveness of these methods in discovering new soliton solutions and supplying deeper insights into the DSW model’s behavior. The novel soliton solutions obtained in this study significantly enhance our understanding of the DSW equation’s underlying dynamics and offer potential applications across various scientific fields.

This study extensively explores the Biswas–Milovic equation (BME) with Kerr and power law nonlinearity to extract the unique characteristics of optical soliton solutions. These optical soliton solutions have different applications in the field of precision in optical switching, applications in waveguide design, exploration of nonlinear optical effects, imaging precision, reduced intensity fluctuations, suitability for optical signal processing in optical physics, etc. Through the powerful (G′/G, 1/G)-expansion analytical method, a variety of soliton solutions are expressed in three distinct forms: trigonometric, hyperbolic, and rational expressions. Rigorous validation using Mathematica software ensures precision, while dynamic visual representations vividly portray various soliton patterns such as kink, anti-kink, singular soliton, hyperbolic, dark soliton, and periodic bright soliton solutions. Indeed, a sensitivity analysis was conducted to assess how changes in parameters affect the exact solutions, aiding in the understanding of system behavior and informing decision-making, especially in accurately designing or analyzing real-world optical phenomena. This investigation reveals the significant influence of parameters λ, τ, c, B, and Κ on the precise solutions in Kerr and power law nonlinearities within the BME. Notably, parameter λ exhibits consistently high sensitivity across all scenarios, while parameters τ and c demonstrate pronounced sensitivity in scenario III. The outcomes derived from this method are distinctive and carry significant implications for the dynamics of optical fibers and wave phenomena across various optical systems.

The effluents from textile industries without proper treatment contains a remarkable amount of synthetic dyes which are harmful to the environment and a big challenge globally to degrade it with a eco-friendly way. Conventional methods are extremely energy-consuming, non-effective and generate a toxic sludge impacting the environment. Several microorganisms can be utilized to treat these effluents. The research deals with five bacteria isolated from textile effluent and their consortium for the biodegradation ability of Novacron dyes. The isolates were identified through the Biolog™ identification system and molecular technique. Biodegradation was confirmed by measuring optical density (OD) optimizing conditions (pH 7.0, temperature 37 °C, 10 % inoculums and 100 mg/L dye) under static condition. The isolates started decolourization at 24 h whereas, the consortium started decolourization at 18 h and exhibited a maximum after 72 h. The presence of low molecular weight protein as metabolite supported the biodegradation and non hazardous to environment. This study revealed that these bacteria might have degradation potentials, and research results will help to set up dye removal eco-friendly methods to expose the dye effulents to environment in future.

This experiment was conducted to characterize potential Lactobacillus spp. isolated from mother's milk and infant feces to obtain new and specific probiotic strains. In this study, seven ascendant strains were identified as Lactobacillus spp. based on their morphological characteristics and biochemical properties. Among them, only one (C-1) isolate was identified as Lactobacillus oris through BioLogTM identification. The study further investigated the isolate through probiotic potentiality tests such as pH and bile tolerance, NaCl tolerance test, gastric juice tolerance, antioxidant activity, resistance to hydrogen, reduction of sodium nitrate, antimicrobial activity, and antibiotic susceptibility test. The result showed that the strain is a potential probiotic based on probiotic capability. The identified strain was most acid-tolerant and retained around 80% viability for up to 4 h at pH 1.0 and 2.0. The isolate showed tolerance against up to 1.50% bile concentration and gastric juice and was able to grow 1–6% NaCl concentrations. Lactobacillus oris showed resistance to most antibiotics as well as antagonistic activity against the tested pathogen, good antioxidant properties, reduction of sodium nitrate and H2O2. The isolate exhibited good intestinal epithelial adhesion properties, and SDS page was performed for secreted protein analysis. Moreover, the strain showed promising cholesterol-lowering properties based on the cholesterol level. This present result indicates that L. oris has superior probiotic properties and can be regarded as a potential probiotic candidate.

This study evaluated the interaction between probiotics and polyphenols in chocolates (45% and 70% cocoa) fortified with encapsulated probiotics. Cocoa powder was used as the main encapsulation component in a Na-alginate plus fructooligosaccharides formulation. Probiotic-chocolates (PCh) were produced by adding 1% encapsulated probiotics to the final mixture. The chocolate samples were subjected to in vitro gastrointestinal digestion and colonic fermentation. The data revealed that the most bioaccessible polyphenols in both formulations of PCh containing 45% and 70% cocoa were released in the gastric digested supernatant. The bioaccessible polyphenols from PCh with 70% cocoa reached 83.22–92.33% and 8.08–15.14% during gastrointestinal digestion and colonic fermentation, respectively. Furthermore, the polyphenols with higher bioaccessibility during colonic fermentation of both PChs developed with the CA1 formulation (cocoa powder 10%, Na-alginate 1% and fructooligosaccharides 2%) were detected in the presence of Streptococcus thermophilus and Lactobacillus sanfranciscensis. The results showed that PCh with specific probiotics favored the bioconversion of a specific polyphenol. For example, chocolate fortified with Lacticaseibacillus casei released larger quantities of epicatechin and procyanidin B1, while Lactiplantibacillus plantarum released more catechin and procyanidin B1 for Lacticaseibacillus rhamnosus LGG. Overall, the study findings concluded that chocolate polyphenols could be utilized by probiotics for their metabolism and modulating the gut, which improved the chocolates’ functionality.

The nonpathogenic yeast Saccharomyces boulardii (Sb) has beneficial effects on the human intestine, and thus has been prescribed as probiotics for the treatment of diarrhea and gastrointestinal diseases. This is the only commercialized yeast with the purpose of being used as human medicine. Currently, little is known about their multiple mechanisms of actions. The S. boulardii yeast strain is isolated and identified by using the BIOLOGTM microarray identification system and morphologically. To understand its functional roles, the present study investigates the ability of this yeast to tolerate different concentrations of bile salt up to 2.5%, cell hydrophobicity, antioxidants, autoaggregation activity, and simulated gastrointestinal digestion. The effect of temperatures (up to 50°C), pH (up to 8.0), and salinity (at best 7%) was also monitored on the growth and survival of the yeast cell. The physicochemical analyses revealed that S. boulardii could survive in stomach conditions at pH 2.5, temperature 37°C, and 2% bile salt. Antibiotic susceptibility of S. boulardii was carried out using commercial antibiotic discs. The antimicrobial activity of the isolated S. boulardii against bacterial pathogens related to diarrhea diseases was in-vitro determined by the Well Diffusion method. The biosafety assay findings also claimed S. boulardii could be a potential probiotic. The experimental findings suggest that the isolated S. boulardii possesses excellent probiotic capacities as a biotherapeutic agent for antidiarrheal and gastrointestinal disorders.

Nucleic acid amplification is a valuable molecular tool not only in basic research but also in application oriented fields, such as clinical medicine development, infectious diseases diagnosis, gene cloning and industrial quality control. A comperehensive review of the literature on the principles, applications, challenges and prospects of different alternative methods of polymerase chain reaction (PCR) was performed. PCR was the first nucleic acid amplification method. With the advancement of research, a no of alternative nucleic acid amplification methods has been developed such as loop mediated isothermal amplification, nucleic acid sequence based amplification, strand displacement amplification, multiple displacement amplification. Most of the alternative methods are isothermal obviating the need for thermal cyclers. Though principles of most of the alternate methods are relatively complex than that of PCR, they offer better applicability and sensitivity in cases where PCR has limitations. Most of the alternate methods still have to prove themselves through extensive validation studies and are not available in commercial form; they pose the potentiality to be used as replacements of PCR. Continuous research is going on in different parts of the world to make these methods viable technically and economically.