Preparation of chitosan derivative and its application in papermaking.

To improve the paper strength, a number of resins and polymeric materials are being used, which is not environmental friendly and sustainable. Therefore, bio-based paper additives for the papermaking industry are essential. In this investigation, a water soluble biopolymer like carboxymethyl chitosan (CMCh) was prepared. The degree of substitution of the prepared CMCh was 2.49. The solubility of the prepared CMCh was 2.0 (w/v) % at 50 °C, and the conductivity increased with the increase of CMCh concentration in water. The prepared CMCh was applied as dry and wet strength agent of unrefined and refined softwood pulps. Both pulp increased dry and wet strength with increasing CMCh dose. An addition of 2.0 % CMCh increased dry strength by 125 % and wet strength by 293 % of unrefined pulp. On the other hand, the dry and wet tensile index of refined pulp increased from 59.48 N·m/g to 66.11 N·m/g and 2.48 N·m/g to 3.47 N·m/g, respectively, with the addition of 1.0 % CMCh. The CMCh was also used in filler modification. The precipitated calcium carbonate (PCC) modified with CMCh increased the ash content in paper with improved strength properties. The CMCh can be used in papermaking both for improving paper strength and filler retention.

4P Model for Dynamic Prediction of COVID-19: a Statistical and Machine Learning Approach.

Around the world, scientists are racing hard to understand how the COVID-19 epidemic is spreading and growing, thus trying to find ways to prevent it before medications are available. Many different models have been proposed so far correlating different factors. Some of them are too localized to indicate a general trend of the pandemic while some others have established transient correlations only. Hence, in this study, taking Bangladesh as a case, a 4P model has been proposed based on four probabilities (4P) which have been found to be true for all affected countries. Efficiency scores have been estimated from survey analysis not only for governing authorities on managing the situation (P(G)) but also for the compliance of the citizens ((P(P)). Since immune responses to a specific pathogen can vary from person to person, the probability of a person getting infected ((P(I)) after being exposed has also been estimated. And the vital one is the probability of test positivity ((P(T)) which is a strong indicator of how effectively the infected people are diagnosed and isolated from the rest of the group that affects the rate of growth. All the four parameters have been fitted in a non-linear exponential model that partly updates itself periodically with everyday facts. Along with the model, all the four probabilistic parameters are engaged to train a recurrent neural network using long short-term memory neural network and the followed trial confirmed a ruling functionality of the 4Ps.

Biological and quantitative-SAR evaluations, and docking studies of (E)-N -benzylidenebenzohydrazide analogues as potential antibacterial agents.

A series of 15 (E)-N'-benzylidenebenzohydrazide analogues were evaluated for their antimicrobial activities against eleven pathogenic and food-borne microbes, namely, S. aureus (G(+)), L. monocytogenes (G(+)), B. subtilis (G(+)), K. pneumonia (G¯), C. sakazakii (G¯), C. freundii (G¯), S. enterica (G¯), S. enteritidis (G¯), E. coli (G¯), Y. pestis (G¯), and P. aeruginosa (G¯). Most of the compounds exhibited selective activity against some Gram-negative bacterial strains. Of the compounds tested (3a-o), 3b and 3g were most active against C. freundii (MIC = ~19 µg mL(-1)). Whereas, compounds 3d, 3i, 3k and 3n exhibited MIC values ranging from 37.5 to 75 µg mL(-1) against C. freundii, and compounds 3e, 3l and 3n had MIC values of ~75 µg mL(-1) against K. pneumonia. Quantitative structure-antibacterial activity relationships were studied using physicochemical parameters and a good correlation was found between calculated octanol-water partition coefficients (clogP; a lipophilic parameter) and antibacterial activities. In silico screening was also performed by docking high (3b and 3g) and low (3n) activity compounds on the active site of E. coli FabH receptor, which is an important therapeutic target. The findings of these in silico screening studies provide a theoretical basis for the design and synthesis of novel benzylidenebenzohydrazide analogues that inhibit bacterial FabH.

Potassium hydroxide pulping of rice straw in biorefinery initiatives.

Rice straw is supposed to be one of the most important lignocellulosic raw materials for pulp mill in Asian countries. The major problem in rice straw pulping is silica. The present research is focused on the separation of silica from the black liquor of rice straw pulping by potassium hydroxide (KOH) and pulp evaluation. Optimum KOH pulping conditions of rice straw were alkali charge 12% as NaOH, cooking temperature 150°C for 2h and material to liquor ratio, 1:6. At this condition pulp yield was 42.4% with kappa number 10.3. KOH pulp bleached to 85% brightness by D0EpD1 bleaching sequences with ClO2 consumption of 25kg/ton of pulp. Silica and lignin were separated from the black liquor of KOH pulping. The amount of recovered silica, lignin and hemicelluloses were 10.4%, 8.4% and 13.0%. The papermaking properties of KOH pulp from rice straw were slightly better than those of corresponding NaOH pulp.

Effect of Sphingosine 1-Phosphate on Cyclo-Oxygenase-2 Expression, Prostaglandin E2 Secretion, and ß2-Adrenergic Receptor Desensitization.

Tachyphylaxis of the ß2-adrenergic receptor limits the efficacy of bronchodilatory ß2-agonists in respiratory disease. Cellular studies in airway smooth muscle (ASM) have shown that inflammatory mediators and infectious stimuli reduce ß2-adrenergic responsiveness in a cyclo-oxygenase (COX)-2-mediated, prostaglandin E2 (PGE2)-dependant manner. Herein, we show that sphingosine 1-phosphate (S1P), a bioactive sphingolipid that plays an important role in pathophysiology of asthma, also induces ß2-adrenergic receptor desensitization in bronchial ASM cells and exerts hyporesponsiveness to ß2-agonists. We treated ASM cells with S1P (1 µM) for up to 24 hours and then examined the temporal kinetics of COX-2 mRNA expression, protein up-regulation, and PGE2 secretion. S1P significantly enhanced COX-2 expression and PGE2 secretion, and this was repressed by the selective COX-2 inhibitor celecoxib, the corticosteroid dexamethasone, or small interfering RNA (siRNA) knockdown of COX-2 expression. In combination with another proinflammatory mediator found elevated in asthmatic airways, the cytokine TNF-α, we observed that S1P-induced COX-2 mRNA expression and protein up-regulation and PGE2 secretion from ASM cells were significantly enhanced. Notably, S1P induced heterologous ß2-adrenergic desensitization, as measured by inhibition of cyclic adenosine monophosphate production in response to the short-acting ß2-agonist, salbutamol, and the long-acting ß2-agonist, formoterol. Taken together, these data indicate that S1P represses ß2-adrenergic activity in ASM cells by increasing COX-2-mediated PGE2 production, and suggest that this bioactive sphingolipid found elevated in asthma may contribute to ß2-adrenergic desensitization.

Na+ channels at postsynaptic muscle membrane affects synaptic transmission at neuromuscular junction: a simulation study.

Motor movement is controlled by the brain through transmitting electrochemical signals to the muscle fibers that cause the contraction of the muscles. A motoneuron carrying the impulse creates a synapse with the muscle fiber which is known as Neuromuscular Junction (NMJ). The muscle infolds taking part in the synapse contains large amount of sodium channels. The current that passes through the narrow synaptic cleft affects the adjacent membranes electrical properties in turn modifies the synaptic transmission process. Considering this phenomenon we have studied the effect of sodium channels at the NMJ to find out its effect in the generation of extracellular potentials at the synaptic cleft of the junction. Through simulation results we confirm that the conductivity of the sodium channels present at the postsynaptic muscle membrane and the junction height affect the generation of the extracellular potentials at the junction which modifies the synaptic properties of the NMJ.

Effect of self-gating on action potential firing at neuromuscular junction.

The neuromuscular junction (NMJ) is the place where the axon terminal of motoneuron connects the 'endplate' of a muscle fiber. During this transduction a large depolarization (endplate potential) caused by the nerve impulse opens a large number of voltage-sensitive sodium channels at the post-junctional terminal. As a result, action potentials are generated and propagated along the muscle fiber causing contraction. This work shows simulated results of the voltage-dependent sodium channels' firing behavior at the NMJ using a mathematical model. It is found that the firing behavior of the sodium channels change basing on their activation and inactivation kinetics which are highly influenced by the self-gating behavior of the sodium conductances. The simulation results showed that self-gating of sodium channels increase conduction efficiency at the NMJ and decrease threshold for firing.

Antidiarrhoeal property of the hydroethanolic extract of the flowering tops of Anthocephalus cadamba / Propriedade antidiarréica do extrato hidroetanólico dos topos floridos de Anthocephalus cadamba

A propriedade antidiarréica do extrato hidroetanólico dos topos floridos de Anthocephalus cadamba foi avaliada em animais experimentais. O extrato hidroetanólico seco (250-500 mg/kg massa corpórea, v.o.) exibiu uma diminuição dose-dependente do número total de excrementos na diarréia induzida por óleo de castor em camundongos. O extrato também causou uma redução significativa (p < 0.01) e dose-dependente do acúmulo de fluidos intestinais e do trânsito gastrointestinal de 64,59 por cento e 71,19 por cento nas doses de 250 e 500 mg/kg. As taxas de redução foram de 37,85 por cento e 74,91 por cento, respectivamente, com o grupo controle e da droga padrão.

The antidiarrhoeal property of the hydroethanolic extract of the flowering tops of Anthocephalus cadamba was assessed on experimental animals. The dry hydroethanolic extract (250-500 mg/kg body mass, p.o.) exhibited a dose-dependent decrease in the total number of faecal droppings in castor oil-induced diarrhoea in mice. The extract also produced a significant (p < 0.01) and dose-dependent reduction in intestinal fluids accumulation and in the gastrointestinal transit from 64.59 percent and 71.19 percent at doses of 250 and 500 mg/kg. The reduction rates were 37.85 percent and 74.91 percent, respectively, with the control and standard drug group.

Self-reported asthma symptoms in children and adults of Bangladesh: findings of the National Asthma Prevalence Study.

BACKGROUND: No population-based studies to determine the magnitude of the asthma problem have been carried out in Bangladesh. This study aimed to define the prevalence of asthma as well as to identify the risk factors of asthma in the general population of Bangladesh. METHODS: A cross-sectional study was conducted from January 1999 to August 1999 on 5642 Bangladeshi people. Data were collected from randomly selected primary sampling units of 8 municipality blocks of 4 large metropolitan cities, 12 municipality blocks of 6 district towns and 12 villages of 6 districts chosen randomly from all 64 districts of the country. Face-to-face interviews were performed with the housewives or other guardians at the household level using a structured questionnaire. RESULTS: The prevalence of asthma (wheeze in the last 12 months) was 6.9% (95% CI : 6.2-7.6). The prevalence of other asthma definitions were: ever wheeze (lifetime wheeze) 8.0% (95% CI : 7.3-8.7); perceived asthma (perception of having asthma) 7.6% (95% CI : 6.9-8.3); doctor diagnosed asthma (diagnosis of asthma by any category of doctor either qualified or unqualified) 4.4% (95% CI : 3.9-4.9). The prevalence of asthma in children (5-14 years) was higher than in adults (15-44 years) (7.3% versus 5.3%; odds ratio [OR] = 1.41, 95% CI : 1.09-1.82). Asthma in children was found to be significantly higher in households with