M. Mizanur Rahman

Improvement of Mechanical Properties of Coir Fiber (Cocus nucifera) with 2-Hydroxyethyl Methacrylate (HEMA) by Photocuring

Coir fiber was cured under, ultraviolet radiation with 2-hydroxyethyl methacrylate (HEMA) in order to improve the mechanical properties with reduced water absorption character. A series of solutions of different HEMA concentrations in methanol, along with photoinitiator Irgacure 907, were prepared. The radiation dose, monomer (HEMA) concentration and soaking time were optimized with the extent of grafting of monomer and mechanical properties of cured fiber. five percent HEMA, 10-min soaking time, and a seventh pass of radiation produced the higher tensile strength (65%) and elongation at break (250%) than those of virgin fiber, as well as the highest grafting value (4.4%). For further improvement of the mechanical properties, the fibers were treated with alkali (Potassium Hydroxide) solution of various concentrations for one hour before curing. A 10% alkali-treated fiber showed the increased properties such as grafting (5.3%), tensile strength (95%), and elongation at break (320%) over raw fiber. The effect of additives (1%), such as acrylamid, urea, and silane [3-(triethoxy)propyl methacrylate] on the properties of coir fiber was) studied. Among the additives used, silane showed the best performance. The effect of simulating weathering on the degradable properties of samples was also performed. The silane-treated fiber produced the minimum loss of the properties, as well as a lower water uptake than those of the untreated one.

Genes and Enzymes of Lysine Catabolism in Pseudomonas aeruginosa

Pseudomonas aeruginosa strain PAO1 cannot utilize L-lysine effectively as a carbon source for growth but grows on cadaverine and glutarate. Strains PAO1 and PAO1632 (Hut-Ami-) have low activities for L-lysine uptake and for L-lysine decarboxylase but both strains gave rise to mutants that grew well on L-lysine. Strain PAO2087, isolated from PAO1, had an active L-lysine uptake system and an inducible L-lysine decarboxylase. Strain PAO2070, isolated from strain PAO1632, had an active L-lysine uptake system and a constitutive L-lysine decarboxylase. We suggest that the genetic defect of strain PAO1 (and PAO1632) that prevents growth of L-lysine is in a regulatory gene controlling the expression of linked genes for L-lysine permease and L-lysine decarboxylase. Mutants unable to utilize L-lysine as a carbon source, isolated from strain PAO2070, exhibited four distinct growth phenotypes. Transductional analysis showed that the genetic defects of these mutants could be distinguished from each other and from that of strain PAO1. Group I mutants, unable to utilize glutarate, formed a single transduction linkage group and were mapped at about 20 min on the chromosome. The mutations of groups II, III and IV appeared to be in separate but linked genes. The group II mutants had no detectable L-lysine decarboxylase activity and the gene locus was mapped by interrupted mating in the 50 to 60 min region of the chromosome. The group III mutants possessed all the early enzymes of the L-lysine decarboxylase pathway and lacked only an active L-lysine uptake system.

Deoxynivalenol Exposure Assessment for Pregnant Women in Bangladesh

The trichothecene mycotoxin deoxynivalenol (DON) is a contaminant of crops worldwide and known to cause adverse health effects in exposed animals and humans. A small survey reported the presence of DON in maize samples in Bangladesh, but these data are insufficient to assess human exposure, and also, biomonitoring data are still scarce. The present study applied biomarker analysis to investigate the DON exposure of pregnant women in Bangladesh. Urine samples were collected from pregnant women living in a rural (n = 32) and in a suburban (n = 22) area of the country. Urines were subjected to enzymatic hydrolysis of glucuronic acid conjugates and to immunoaffinity column clean-up prior to LC-MS/MS analysis of DON and its de-epoxy metabolite DOM-1. The limits of detection (LOD) for DON and DOM-1 in urine were 0.16 ng/mL and 0.10 ng/mL, respectively. DOM-1 was not detected in any of the urines, whilst DON was detectable in 52% of the samples at levels ranging from 0.18–7.16 ng/mL and a mean DON concentration of 0.86 ± 1.57 ng/mL or 2.14 ± 4.74 ng/mg creatinine. A significant difference in mean urinary DON levels was found between the rural (0.47 ± 0.73 ng/mL) and suburban (1.44 ± 2.20 ng/mL) cohort, which may be related to different food habits in the two cohorts. Analysis of food consumption data for the participants did not show significant correlations between their intake of typical staple foods and DON levels in urine. The biomarker concentrations found and published urinary excretion rates for DON were used to estimate daily mycotoxin intake in the cohort: the mean DON intake was 0.05 µg/kg b.w., and the maximum intake was 0.46 µg/kg b.w., values lower than the tolerable daily intake of 1 µg/kg b.w. These first results indicate a low dietary exposure of pregnant women in Bangladesh to DON. Nonetheless, further biomonitoring studies in children and in adult cohorts from other parts of the country are of interest to gain more insight into DON exposure in the population of Bangladesh.

Phorbol ester or epidermal growth-factor-induced MUC5AC mucin gene expression and production from airway epithelial cells are inhibited by apigenin and wogonin.

In this study, we investigated whether apigenin and wogonin affect MUC5AC mucin production and gene expression induced by phorbol ester (phorbol 12‐myristate 13‐acetate, PMA) or epidermal growth factor (EGF) from human airway epithelial cells. Confluent NCI‐H292 cells were pretreated with each agent for 30 min and then stimulated with PMA or EGF for 24 h, respectively. MUC5AC mucin gene expression and mucin protein production were measured by reverse transcription polymerase chain reaction (RT‐PCR) and enzyme linked immunosorbent assay (ELISA). The results were as follows: (i) apigenin and wogonin were found to inhibit the production of MUC5AC mucin protein induced by PMA or EGF; (ii) both compounds also inhibited the expression of MUC5AC mucin gene induced by PMA or EGF. These results suggest that apigenin and wogonin can inhibit mucin gene expression and production of mucin protein, by directly acting on airway epithelial cells. Copyright

GRAFTING OF DIFFERENT MONOMERS ONTO JUTE YARN BY IN SITU UV-RADIATION METHOD: EFFECT OF ADDITIVES

Jute yarn was improved through in situ grafting under UV radiation technique using three different types of bulk monomers [methyl methacrylate (MMA), butyl acrylate (BA), and styrene (ST)]. For almost all cases, bulk monomer was mixed with methanol to swell the cellulose backbone of jute for better impregnation of monomer solution. The effects of variation in irradiation time, monomer concentration, and additives on the extent of grafting were studied. Various physico-mechanical properties like grafting water uptake, tensile strength, elongation at break for both treated and untreated jute yarns were performed. The properties of the treated jute yarn with different monomers were also compared. The highest polymer loading was found for the monomer BA but MMA showed better tensile properties amongst the monomers investigated. Five types of additives (1%) of different chemical nature, such as 2-hydroxyethylmethacrylate, ethylhexylacrylate, acrylamide, N-vinylpyrrolidine, and urea (U) were added into the bulk monomer solution to study the effects on grafting and mechanical properties of jute yarn. Among all additives, only U showed better properties in system. Water uptake of the treated and untreated samples was also performed and BA-grafted samples showed lower water uptake to that of virgin as well as other treated samples.

Effect of the Incorporation of PVC on the Mechanical Properties of the Jute-Reinforced LLDPE Composite

Jute fabrics-reinforced linear low density polyethylene (LLDPE) matrix composites (50 wt% fiber) were prepared by compression molding and mechanical properties were studied. Polyvinyl chloride (PVC) matrix was incorporated instead of LLDPE in the jute based composites and their mechanical properties were investigated and compared with the control composites. It was found that with the increase of PVC in the LLDPE based composites, the mechanical properties were found to improve significantly. Degradation tests of the composites for upto 24 weeks were performed in soil medium. Water uptake and Thermo-mechanical properties of the composites were also studied.

The Catabolism of Arginine by Pseudomonas aeruginosa

Mutants isolated from Pseudomonas aeruginosa strain PAO1632 (Hut-Ami) were unable to utilize L-arginine or L-ornithine as the carbon source for growth. Arginine deiminase (AD), catabolic ornithine carbamoyltransferase (cOTC) and N2-acetylornithine 5-aminotransferase (ACOAT) were present in the mutants but these enzymes were not induced to higher levels by exogenous L-arginine. One group of mutants could utilize L-ornithine but not L-arginine and in these strains L-arginine induced the synthesis of ACOAT but not AD or cOTC. The mutations of the arginine utilization-negative mutants were all in genes of the same transductional linkage group and mapped in the 45 to 50 min region of the chromosome. Revertants isolated on L-arginine or L-ornithine plates were derepressed for the synthesis of ACOAT. It is suggested that L-arginine is normally catabolized by the wild-type strain via the arginine deiminase pathway and requires a threshold level of ACOAT. The regulatory factors controlling the functioning of the divergent arginine deiminase and arginine carboxylase pathways are discussed.

Recent policy of trade liberalization in Bangladesh and issues of regional cooperation in South Asia

Abstract In recent years Bangladesh has pursued a proactive policy of trade liberalization, characterised by removal of Quantitative Restrictions, rationalisation of tariff rates, a flexible exchange rate policy, and an active incentive structure for promoting the export sector and enhancing export sector performance. Such policy reforms have also been carried out by all of Bangladeshs neighbours in South Asia, although with non-uniform phasing and sequencing of the respective reform programs. In the backdrop of the above mentioned policy shifts, the issue of greater regional cooperation in the field of trade and commerce among South Asian countries has attained prominence both at political and at academic levels. This article focuses on the critical issues of concern within this context, and argues that South Asian countries should put more emphasis on enhancing intra-regional trade and promoting regional cooperation in the field of trade and investment. The countries of South Asia should explore the various avenues to make the South Asia preferential trade area (SAPTA) effective, although the option of joining other trade blocs should not be excluded. ( JEL: F12, F13, F14, O.53)

Decolorization of textile wastewater by gamma irradiation and its reuse in dyeing process

AbstractThis paper describes the scope of employing high-energy gamma irradiation for textile wastewater treatment and the possibility of using the treated wastewater in the dyeing of knitted cotton fabric. The treatment was carried out in Cobalt-60 gamma radiation source at different irradiation doses (3, 5, 8, and 12 kGy). Then, the irradiated wastewater was used for dyeing of cotton fabric with reactive dye. The performance of the fabric dyed with treated wastewater was compared to that of the fabric dyed with freshwater. Hence, the dyeing performance was evaluated by comparing the depth of shades of both types of dyed fabrics from the analysis of absorption spectrum (K/S value vs. wavelength). The absorption curves of irradiated wastewater dyed fabric in light, medium, and dark shade of three different colors have shown close match to their corresponding freshwater dyed fabric. Variation of shade between the dyed fabrics, representing by ∆E values, were also found within the maximum acceptable limit a...

Evaluation of selectivity for l-glutamide-derived highly ordered assemblies in reversed-phase high-performance liquid chromatography

Two dioctadecyl L-glutamic acid derivatives with amide and ester type bondings have been synthesized and immobilized from 3-aminopropyltrimethoxysilane (APS) grafted silica (Sil-APS) to be used in reversed-phase high-performance liquid chromatography (RP-HPLC). Subsequent studies showed that dioctadecyl-L-glutamide derivative (GLN) can self-assemble into highly ordered structures by forming three-dimensional fibrillar aggregates as observed in scanning and transmission electron microscopes (SEM and TEM). Variable temperature (1)H NMR and FT-IR spectra of organogel revealed that the special aggregation morphology shown by GLN was stabilized by inter and or intra molecular hydrogen bonding among amide moieties. However, such ordered aggregated or self-assembled structures were not observed for the dioctadecyl-L-glutamate (GLU) derivative. The stationary phases Sil-GLN and Sil-GLU were characterized by DRIFT, elemental analysis, TGA, and (13)C and (29)Si CP-MAS NMR spectroscopic measurements. The chromatographic selectivity for both stationary phases was evaluated from the retention studies of different size and shape polycyclic aromatic hydrocarbons (PAHs). The chromatographic experiment for PAHs and geometrical isomers in RP-HPLC showed that Sil-GLN demonstrated extremely enhanced selectivity than Sil-GLU. The higher selectivity attributed by Sil-GLN has been brought by multiple pi-pi interactions among the pi-electrons of the grafted organic phase and pi-electrons of the guest PAHs molecules. Thermodynamic studies for linear and nonlinear PAHs revealed that the retention behavior does not change over a temperature range from 10 to 60 degrees C for both stationary phases.