The contribution of different vinyl sulphone-reactive dyes to an effluent

AbstractThree types of vinyl sulphone dyes were measured in the effluent in this study. The selected dyes were Remazol Yellow RR (mono-functional), Remazol Blue RR (homo bi-functional) and Remazol Red RR (hetero bi-functional). The extinction coefficients of these dyes were measured by creating absorbance versus concentration curves. The absorbance values were obtained by testing standard solutions of each dye in a UV–visible spectrophotometer. The dyeing process was carried out at 4 different dye concentrations (0.025g/40ml, 0.05g/40ml, 0.10g/40ml and 0.15g/40ml) on a 5-g fabric sample for each of the dyes. The post-dye liquors and post-wash liquors were tested in an UV–visible spectrophotometer, and their concentrations were calculated using the Beer–Lambert law. The contribution of these dyes to the effluent was calculated and compared, and their adsorption isotherms (Langmuir and Freundlich isotherm) were analysed. The homo bi-functional dye (Blue RR) performed well in the dye bath, but it contributed significantly to the effluent during the washing stages. The mono-functional dye (Yellow RR) was able to adsorb, but it did not perform well due to its greater heterogeneity. The hetero bi-functional Red RR dye was found to be the most environmentally friendly in comparison with the other vinyl sulphone dyes

Effect of chemical treatments and coupling agents on the properties of unidirectional jute fiber reinforced polypropylene composite

Due to different chemical nature of jute and polypropylene, their blended composite materials often show failures behavior when applied in load bearing purposes. The aim of the research is to improve the properties of unidirectional jute fiber (JF) reinforced polypropylene (PP) composite. Unidirectional fiber composite was produced by simple hot press molding method according to weight percentage of 30wt% filler (JF), 2wt% coupling agent (compatibilizer) degraded PP (DgPP) and maleated PP (MAPP) and 68 wt% matrix (PP). To improve the interfacial interactions between the fiber and PP, the fiber was chemically modified with 10w/v% NaOH, 6w/v% dicumylperoxide (DCPO), 0.05 w/v% K2Cr2O7 and 5 w/v% H2O2 solution. The water absorption, tensile and thermal properties of raw and surface treated fibers composites were compared in particular coupling agent. It has found that the fiber treatments and addition of coupling agents, composites showed better properties. Among the composites, 10 wt/v% NaOH treated jute reinforced PP composite by using MAPP compatibilizer was presented better water absorption and mechanical properties. The positive change of the treated fiber composites was also found in case of the thermal stability that investigated by the TG, DTA and DTG tests

Sustainable adsorbents from plant-derived agricultural wastes for anionic dye removal: a review

The extensive use of dyes in numerous industries results in massive dye discharge in the wastewater, which is a major cause of water pollution. Globally, the consumption of dyes is near seven hundred thousand tons across different sectors, of which around 10–15% goes into the wastewater. Among the dye kinds, anionic dyes make up the main proportion, having a 32–90% share in the wastewater. Different plant-derived wastes, which are sustainable given their natural abundance, effectiveness, and low cost, are frequently proposed for dye separation. However, these adsorbents are inherently more suitable for cationic dyes than anionic dyes. In recent years, the modification of these wastes has been progressively considered to suit them to anionic dye removal. These modifications involve mechanical, thermal, or chemical treatments, or combinations. These attempts propose two-way benefits, as one abundant waste is being used to cure another severe problem, and eventually both could be diminished. This review has a key focus on the evaluation of plant-derived adsorbents and their modifications, and particularly for anionic dye adsorption. Overall, the mechanism of adsorption and the suitability of the current methods are discussed, and their future potential is explored

Mechanical, thermal and morphological studies of microfibrillated jute/PLA biocomposites

In the present study, biocomposites based on microfibrillated jute (MFJ) fibre and polylactic acid (PLA) have been prepared by solvent-assisted compression moulding techniques. The MFJ is obtained by a sequence of alkali, chlorite and acid treatments of jute fibre. The biocomposites are fabricated by loading of 10, 20 and 30 wt% of MFJ fibre into the PLA matrix. The effect of MFJ fibre loading on the mechanical, thermal, and morphological properties of the composites is also studied. Among these composites, it is observed that 10 wt% fibre-filled biocomposite shows improved tensile strength andtensile modulus compared to virgin PLA film. Similarly, storage modulus and loss modulus are also found improved for the composites. These composites exhibit higher water absorption capacity and lower thermal stability than virgin PLA. The fibre-matrix adhesion is evaluated by scanning electron microscopy. The results are attributed to the improved interfacial adhesion between MFJ and PLA matrix for 10 wt% fibre-filled biocomposites

Kinetics of Oxygen Reduction Reaction of Polymer-Coated MWCNT-Supported Pt-Based Electrocatalysts for High-Temperature PEM Fuel Cell

Sluggish oxygen reduction reaction (ORR) of electrodes is one of the main challenges in fuel cell systems. This study explored the kinetics of the ORR reaction mechanism, which enables us to understand clearly the electrochemical activity of the electrode. In this research, electrocatalysts were synthesized from platinum (Pt) catalyst with multi-walled carbon nanotubes (MWCNTs) coated by three polymers (polybenzimidazole (PBI), sulfonated tetrafluoroethylene (Nafion), and polytetrafluoroethylene (PTFE)) as the supporting materials by the polyol method while hexachloroplatinic acid (H2PtCl6) was used as a catalyst precursor. The oxygen reduction current of the synthesized electrocatalysts increased that endorsed by linear sweep voltammetry (LSV) curves while increasing the rotation rates of the disk electrode. Additionally, MWCNT-PBI-Pt was attributed to the maximum oxygen reduction current densities at −1.45 mA/cm2 while the minimum oxygen reduction current densities of MWCNT-Pt were obtained at −0.96 mAcm2. However, the ring current densities increased steadily from potential 0.6 V to 0.0 V due to their encounter with the hydrogen peroxide species generated by the oxygen reduction reactions. The kinetic limiting current densities (JK) increased gradually with the applied potential from 1.0 V to 0.0 V. It recommends that the ORR consists of a single step that refers to the first-order reaction. In addition, modified MWCNT-supported Pt electrocatalysts exhibited high electrochemically active surface areas (ECSA) at 24.31 m2/g of MWCNT-PBI-Pt, 22.48 m2/g of MWCNT-Nafion-Pt, and 20.85 m2/g of MWCNT-PTFE-Pt, compared to pristine MWCNT-Pt (17.66 m2/g). Therefore, it can be concluded that the additional ionomer phase conducting the ionic species to oxygen reduction in the catalyst layer could be favorable for the ORR reaction

Seroprevalence of SARS-CoV-2 infection and associated factors among Bangladeshi slum and non-slum dwellers in pre-COVID-19 vaccination era: October 2020 to February 2021

Background Seroprevalence studies have been carried out in many developed and developing countries to evaluate ongoing and past infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Data on this infection in marginalized populations in urban slums are limited, which may offer crucial information to update prevention and mitigation policies and strategies. We aimed to determine the seroprevalence of SARS-CoV-2 infection and factors associated with seropositivity in slum and non-slum communities in two large cities in Bangladesh. Methods A cross-sectional study was carried out among the target population in Dhaka and Chattogram cities between October 2020 and February 2021. Questionnaire-based data, anthropometric and blood pressure measurements and blood were obtained. SARS-CoV-2 serology was assessed by Roche Elecsys® Anti-SARS-CoV-2 immunoassay. Results Among the 3220 participants (2444 adults, ≥18 years; 776 children, 10–17 years), the overall weighted seroprevalence was 67.3% (95% confidence intervals (CI) = 65.2, 69.3) with 71.0% in slum (95% CI = 68.7, 72.2) and 62.2% in non-slum (95% CI = 58.5, 65.8). The weighted seroprevalence was 72.9% in Dhaka and 54.2% in Chattogram. Seroprevalence was positively associated with limited years of formal education (adjusted odds ratio [aOR] = 1.61; 95% CI = 1.43, 1.82), lower income (aOR = 1.23; 95% CI = 1.03, 1.46), overweight (aOR = 1.2835; 95% CI = 1.26, 1.97), diabetes (aOR = 1.67; 95% CI = 1.21, 2.32) and heart disease (aOR = 1.38; 95% CI = 1.03, 1.86). Contrarily, negative associations were found between seropositivity and regular wearing of masks and washing hands, and prior BCG vaccination. About 63% of the population had asymptomatic infection; only 33% slum and 49% non-slum population showed symptomatic infection. Conclusion The estimated seroprevalence of SARS-CoV-2 was more prominent in impoverished informal settlements than in the adjacent middle-income non-slum areas. Additional factors associated with seropositivity included limited education, low income, overweight and pre-existing chronic conditions. Behavioral factors such as regular wearing of masks and washing hands were associated with lower probability of seropositivity.https://doi.org/10.1371/journal.pone.0268093pubpu

A systematic review on COVID-19 vaccine strategies, their effectiveness, and issues

COVID-19 vaccines are indispensable, with the number of cases and mortality still rising, and currently no medicines are routinely available for reducing morbidity and mortality, apart from dexamethasone, although others are being trialed and launched. To date, only a limited number of vaccines have been given emergency use authorization by the US Food and Drug Administration and the European Medicines Agency. There is a need to systematically review the existing vaccine candidates and investigate their safety, efficacy, immunogenicity, unwanted events, and limitations. The review was undertaken by searching online databases, i.e., Google Scholar, PubMed, and ScienceDirect, with finally 59 studies selected. Our findings showed several types of vaccine candidates with different strategies against SARS-CoV-2, including inactivated, mRNA-based, recombinant, and nanoparticle-based vaccines, are being developed and launched. We have compared these vaccines in terms of their efficacy, side effects, and seroconversion based on data reported in the literature. We found mRNA vaccines appeared to have better efficacy, and inactivated ones had fewer side effects and similar seroconversion in all types of vaccines. Overall, global variant surveillance and systematic tweaking of vaccines, coupled with the evaluation and administering vaccines with the same or different technology in successive doses along with homologous and heterologous prime-booster strategy, have become essential to impede the pandemic. Their effectiveness appreciably outweighs any concerns with any adverse events

Antimicrobial prescribing confidence and knowledge regarding drug resistance : perception of medical students in Malaysia and the implications

Background: Worldwide, microbes are becoming more challenging by acquiring virulent skills to adapt and develop antimicrobial resistance (AMR). This is a concern as AMR increases morbidity, mortality, and costs. Consequently, physicians need to be trained on appropriate antimicrobial prescribing, starting as medical students. Objective: To evaluate medical students’ confidence in antimicrobial prescribing and AMR. Methods: Cross-sectional study assessing medical students’ knowledge, perception, and confidence in prescribing antimicrobials and AMR in a Malaysian University. A universal sampling method was used. Results: Most responding students believed that educational input regarding overall prescribing was sufficient. Regarding the principle of appropriate and accurate prescriptions, female medical students had less knowledge (odds ratio (OR) = 0.51; 95% confidence interval (CI) 0.25–0.99; p = 0.050). Year-IV and year-V medical students had more excellent knowledge than year-III students regarding confidence in potential antibiotic prescribing once qualified. Year-V students also showed an appreciably higher confidence in the broad principles of prescribing, including antibiotics for infectious diseases, compared to those in other years. Conclusion: Overall, medical students gain more knowledge and confidence regarding the potential prescribing of antimicrobials as their academic careers progress. This is important given concerns with the current excessive use of antimicrobials in Malaysia