Preparation and Characterization of Jute Cellulose Crystals-Reinforced Poly(L-lactic acid) Biocomposite for Biomedical Applications

Crystalline cellulose was extracted from jute by hydrolysis with 40% H2SO4 to get mixture of micro/nanocrystals. Scanning electron microscope (SEM) showed the microcrystalline structure of cellulose and XRD indicated the Iβ polymorph of cellulose. Biodegradable composites were prepared using crystalline cellulose (CC) of jute as the reinforcement (3–15%) and poly(lactic acid) (PLA) as a matrix by extrusion and hot press method. CC was cellulose derived from mercerized and bleached jute fiber by acid hydrolysis to remove the amorphous regions. FT-IR studies showed hydrogen bonding between the CC and the PLA matrix. The X-ray diffraction (XRD) and differential scanning calorimetry (DSC) studies showed that the percentage crystallinity of PLA in composites was found to be higher than that of neat PLA as a result of the nucleating ability of the crystalline cellulose. Furthermore, Vicker hardness and yield strength were found to increase with increasing cellulose content in the composite. The SEM images of the fracture surfaces of the composites were indicative of poor adhesion between the CC and the PLA matrix. The composite with 15% CC showed antibacterial effect though pure films but had no antimicrobial effect; on the other hand its cytotoxicity in biological medium was found to be medium which might be suitable for its potential biomedical applications

Advanced CNC/PEG/PDMAA Semi-IPN Hydrogel for Drug Delivery Management in Wound Healing

A Semi Interpenetrating Polymer Network (semi-IPN) hydrogel was prepared and loaded with an antibiotic drug, gentamicin, to investigate the wound healing activity of this system. The semi-IPN hydrogel was synthesized by combining natural polymer cellulose nanocrystal (CNC) and synthetic polymer polyethylene glycol (PEG) and poly (N,N0-dimethyl acrylamide) (PDMAA), which was initially added as a monomer dimethyl acrylamide (DMAA). CNC was prepared from locally obtained jute fibers, dispersed in a PEG-NaOH solvent systemand then mixed with monomer DMAA, where polymerization was initiated by an initiator potassium persulphate (KPS) and cross-linked by N,N0-methylenebisacrylamide (NMBA). The size, morphology, biocompatibility, antimicrobial activity, thermal and swelling properties of the hydrogel were investigated by different characterization techniques. The biocompatibility of the hydrogel was confirmed by cytotoxicity analysis, which showed \u3e95% survival of the BHK-21, Vero cell line. The drug loaded hydrogel showed antimicrobial property by forming 25 and 23 mm zone of inhibition against Staphylococcus aureus (gram-positive) and Escherichia coli (gram-negative) bacteria, respectively, in antimicrobial analysis. At pH 5.5, 76% of the drug was released from the hydrogel within 72 h, as observed in an in vitro drug release profile. In an in vivo test, the healing efficiency of the drug loaded hydrogel was examined on a mice model with dorsal wounds. Complete healing of the wound without any scar formation was achieved in 12 days, which revealed excellent wound healing properties of the prepared drug loaded semi-IPN hydrogel. These results showed the relevance of such a system in the rapid healing of acute wounds

Dose-response relationship between arsenic exposure and the serum enzymes for liver function tests in the individuals exposed to arsenic: a cross sectional study in Bangladesh

<p>Abstract</p> <p>Background</p> <p>Chronic arsenic exposure has been shown to cause liver damage. However, serum hepatic enzyme activity as recognized on liver function tests (LFTs) showing a dose-response relationship with arsenic exposure has not yet been clearly documented. The aim of our study was to investigate the dose-response relationship between arsenic exposure and major serum enzyme marker activity associated with LFTs in the population living in arsenic-endemic areas in Bangladesh.</p> <p>Methods</p> <p>A total of 200 residents living in arsenic-endemic areas in Bangladesh were selected as study subjects. Arsenic concentrations in the drinking water, hair and nails were measured by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The study subjects were stratified into quartile groups as follows, based on concentrations of arsenic in the drinking water, as well as in subjects' hair and nails: lowest, low, medium and high. The serum hepatic enzyme activities of alkaline phosphatase (ALP), aspartate transaminase (AST) and alanine transaminase (ALT) were then assayed.</p> <p>Results</p> <p>Arsenic concentrations in the subjects' hair and nails were positively correlated with arsenic levels in the drinking water. As regards the exposure-response relationship with arsenic in the drinking water, the respective activities of ALP, AST and ALT were found to be significantly increased in the high-exposure groups compared to the lowest-exposure groups before and after adjustments were made for different covariates. With internal exposure markers (arsenic in hair and nails), the ALP, AST and ALT activity profiles assumed a similar shape of dose-response relationship, with very few differences seen in the higher groups compared to the lowest group, most likely due to the temporalities of exposure metrics.</p> <p>Conclusions</p> <p>The present study demonstrated that arsenic concentrations in the drinking water were strongly correlated with arsenic concentrations in the subjects' hair and nails. Further, this study revealed a novel exposure- and dose- response relationship between arsenic exposure metrics and serum hepatic enzyme activity. Elevated serum hepatic enzyme activities in the higher exposure gradients provided new insights into arsenic-induced liver toxicity that might be helpful for the early prognosis of arsenic-induced liver diseases.</p

Oligomeric PLA coupling agents for phosphate glass fibres/PLA composites

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Modifiable and nonmodifiable factors associated with anxiety, depression, and stress after one year of the COVID-19 pandemic

Background People worldwide have experienced various mental health issues during the COVID-19 pandemic. This study investigates the modifiable and nonmodifiable predictors of anxiety, depression, and stress among Bangladeshi participants after one year of the pandemic. Method A large group of adult participants (N = 1897), recruited from eight administrative divisions in Bangladesh, completed an online survey in May and June 2021 when the Movement Control Order was in place. We used the Beck Anxiety Inventory, Patient Health Questionnaire-9, and Perceived Stress Scale-4 to assess the participants’ anxiety, depression, and stress. We also gave the Mindful Attention Awareness Scale and Life-Orientation Test-Revised to assess mindfulness and optimism. Results The results revealed that the prevalence rates for anxiety and depression were 62.5% and 45.3%, respectively. Multivariate analyses showed that several nonmodifiable factors, such as those who were students, unmarried and females, and those living in the Northern region (Rajshahi and Mymensingh division) and dwelling in the rural areas, suffered from worse mental health (accounted for 5%-23% of the variances in the mental health outcome scores). Modifiable factors accounted for an additional 10%-25% of the variances in the same outcome variables. Adults with higher mindfulness and optimism, living in the country’s Southern region (Chattogram division) and those who took both vaccine doses and had no history of mental illness reported better mental health. Conclusion Anxiety, depression, and stress remained high in Bangladeshi adults after one year of the pandemic. The community-based interventions should aim to increase the mindfulness and optimism levels among the sufferers. More accelerated vaccination programs across the country could protect people from suffering from overall mental distress

Modifiable and nonmodifiable factors associated with anxiety, depression, and stress after one year of the COVID-19 pandemic.

BackgroundPeople worldwide have experienced various mental health issues during the COVID-19 pandemic. This study investigates the modifiable and nonmodifiable predictors of anxiety, depression, and stress among Bangladeshi participants after one year of the pandemic.MethodA large group of adult participants (N = 1897), recruited from eight administrative divisions in Bangladesh, completed an online survey in May and June 2021 when the Movement Control Order was in place. We used the Beck Anxiety Inventory, Patient Health Questionnaire-9, and Perceived Stress Scale-4 to assess the participants' anxiety, depression, and stress. We also gave the Mindful Attention Awareness Scale and Life-Orientation Test-Revised to assess mindfulness and optimism.ResultsThe results revealed that the prevalence rates for anxiety and depression were 62.5% and 45.3%, respectively. Multivariate analyses showed that several nonmodifiable factors, such as those who were students, unmarried and females, and those living in the Northern region (Rajshahi and Mymensingh division) and dwelling in the rural areas, suffered from worse mental health (accounted for 5%-23% of the variances in the mental health outcome scores). Modifiable factors accounted for an additional 10%-25% of the variances in the same outcome variables. Adults with higher mindfulness and optimism, living in the country's Southern region (Chattogram division) and those who took both vaccine doses and had no history of mental illness reported better mental health.ConclusionAnxiety, depression, and stress remained high in Bangladeshi adults after one year of the pandemic. The community-based interventions should aim to increase the mindfulness and optimism levels among the sufferers. More accelerated vaccination programs across the country could protect people from suffering from overall mental distress

Assessment of physicochemical and bacteriological parameters in surface water of Padma River, Bangladesh

Abstract In the present study, surface water samples were collected during three seasons (summer, monsoon and winter) from four different study sites (T-dam, Padma Garden, I-dam and Talaimari point) of Padma River at Rajshahi, Bangladesh, and various physicochemical and bacterial parameters were analyzed based on standard methods. Significant differences (p < 0.05) in physicochemical parameters were observed among the seasons and sites except for water temperature. However, except for fecal coliform, other bacterial parameters such as total heterotrophic bacteria, total coliform and Vibrio cholerae counts showed significant differences (p < 0.05) among the seasons, while difference among the sites was insignificant (p < 0.05). The result also showed that all the bacterial parameters were maximum during summer and minimum during monsoon season. Untreated sewage and industrial effluents together with reduced water flow and water level were found to increase bacterial counts during summer at Site 2 (Padma Garden). Although the present situation is not serious and alarming enough, the river water requires intensive monitoring to improve its quality for better and sustainable management

Enhancement of thermal and mechanical properties of PMMA composites by incorporating mesoporous micro-silica and GO

The application of polymer-based composite materials is on the rise due to their enhanced thermal and mechanical properties compared to polymers themselves. For the first time in this study, the combination of graphene oxide (GO) and mesoporous micro-silica particles (with varying pore sizes) was used as fillers into PMMA matrices via in-situ bulk polymerization with ultrasonication. Two types of mesoporous silica were used at a fixed amount of 3 wt% with varying GO composition from 0.1 wt% to 1.2% to investigate the synergistic effect of GO and silica and increment of pore size of silica filler on the thermomechanical properties of the composites. The glass transition temperature Tg, thermal stability (the temperature at 10% and 60% weight loss) Td10 and Td60 of the same composite were increased by 21.5 °C, 46.5 °C, and 32.3 °C, respectively, compared to that of neat PMMA. Its tensile strength was increased remarkably by 329% compared with the PMMA. This work offers the possibility of further enhancement of thermal and mechanical properties of polymer-based composites by incorporating more than one filler with diverse properties