Aspects of Structural and Multiferroic Properties of A- (15% Gd) and B-Site (5–15% Cr) Doped Perovskite BiFeO3 Nanoparticles

M. N. Hossain,M. A. Matin,M. A. Islam,M. M. Rhaman,M. A. Hakim,M. F. Islam 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.4

This report focuses on the investigation of multiferroic properties of 15% Gd and (5–15) % Cr co-doped Bismuth Ferrite (BFO) nanoparticles prepared by sol–gel method. The synthesized pure BFO has shown to be R3c rhombohedral crystal structure which partially transforms to Pnma orthorhombic crystal structure with increasing Cr dopant in co-doped samples. The crystallite size was found to vary from 68 to 22 nm depending on doping level. SEM images exhibited uniform nanoparticles and the average size of particles was shown to vary from 263 to 114 nm which is comparatively higher than that obtained from XRD results due to agglomeration eff ects. Ferroelectric tests exhibited a signifi cant reduction in polarization in doped BFO under an applied fi eld of ± 15 kV/cm. In contrast, the magnetic measurement showed a substantial improvement in ferromagnetic properties of the synthesized samples compared to un-doped one. A prominent exchange anisotropy eff ect was also observed in all the samples at room temperature. In addition, co-doped BFO samples demonstrated a signifi cant reduction in band gap energy from 1.88 to 1.68 eV.

Enhanced Enzymatic Transformation of 1-Naphthol in the Presence of Catechol by Peroxidase

A. K. M. Mydul Islam,이성은,김장억 한국응용생명화학회 2014 Applied Biological Chemistry (Appl Biol Chem) Vol.57 No.2

Effect of catechol on 1-naphthol transformation byhorse radish peroxidase (HRP) was examined. The impact ofcatechol to 1-naphthol ratio, enzyme activity, pH, and reactiontime in solution were studied. The results obtained indicated that,in the presence of catechol, 1-naphthol transformation byperoxidase shows enhancement greater than that in an equivalentcatechol free system. Only 27% of 1-naphthol (0.3 mM) was ableto transform when catechol was absent in solution, but reached79% in its presence (3.0 mM) in 0.1M sodium phosphate buffer(pH 7.0), and 0.3 mM H2O2 by peroxidase (0.5 unit/mL) after 3 h. The 1-naphthol transformation rate was accelerated by increase ofpH or HRP concentration. High-performance liquid chromatographyanalysis was performed to characterize transformation productsbased on their relative polarities, and molecular weights of productswere identified by mass spectrometry. The transformation productswere found to be (hydroxy) naphthoquinones, 1-naphthol:hydroxy-naphthoquinone, and 1-naphthol oligomers (dimer, trimer,tetramer) with the molecular weights (m/z) ranging 100–600. Liquid chromatography-tandem mass spectrometry technique, tothe best of our knowledge, was used for the first time to elucidatethe product structure at m/z 191. The study shows that 1-naphtholis transformed rapidly by peroxidase when catechol is present,which could be useful information for improving the efficienciesof decontamination techniques.

Enhanced Enzymatic Transformation of 1-Naphthol in the Presence of Catechol by Peroxidase

Islam, A.K.M. Mydul,Lee, Sung-Eun,Kim, Jang-Eok The Korean Society for Applied Biological Chemistr 2014 Applied Biological Chemistry (Appl Biol Chem) Vol.57 No.2

Effect of catechol on 1-naphthol transformation by horse radish peroxidase (HRP) was examined. The impact of catechol to 1-naphthol ratio, enzyme activity, pH, and reaction time in solution were studied. The results obtained indicated that, in the presence of catechol, 1-naphthol transformation by peroxidase shows enhancement greater than that in an equivalent catechol free system. Only 27% of 1-naphthol (0.3 mM) was able to transform when catechol was absent in solution, but reached 79% in its presence (3.0 mM) in 0.1M sodium phosphate buffer (pH 7.0), and 0.3 mM $H_2O_2$ by peroxidase (0.5 unit/mL) after 3 h. The 1-naphthol transformation rate was accelerated by increase of pH or HRP concentration. High-performance liquid chromatography analysis was performed to characterize transformation products based on their relative polarities, and molecular weights of products were identified by mass spectrometry. The transformation products were found to be (hydroxy) naphthoquinones, 1-naphthol: hydroxy-naphthoquinone, and 1-naphthol oligomers (dimer, trimer, tetramer) with the molecular weights (m/z) ranging 100-600. Liquid chromatography-tandem mass spectrometry technique, to the best of our knowledge, was used for the first time to elucidate the product structure at m/z 191. The study shows that 1-naphthol is transformed rapidly by peroxidase when catechol is present, which could be useful information for improving the efficiencies of decontamination techniques.

Seed extracts of a Bangladeshi medicinal plant Abrus precatorius L. show antifertility activity in female rats

Hannan, M.A.,Hossain, M.A.,Islam, M.T. Kyung Hee Oriental Medicine Research Center 2010 Oriental pharmacy and experimental medicine Vol.10 No.2

The seed powder of Abrus precatorius L. has traditionally been used as oral contraceptive agent by the women in some rural areas in Bangladesh. The present study aimed to examine the antifertility activity of A. precatorius seed extracts in experimental female rats. Finely ground seeds were extracted with aqueous acetone followed by successive partitioning with n-hexane, ethyl acetate (EtOAc), methanol (MeOH) and water. Water suspended crude seed powder, organic fractions of acetone extract and a standard contraceptive drug ($Nordette^{(R)}28$) were separately administered orally to the female rats for 30 days. n-Hexane, EtOAc and MeOH solubles at the doses of 2, 4 and 6 mg/rat/day, respectively and crude seed powder at 100 mg/rat/day exhibited 100% antifertility activity with lowest levels of serum luteinizing hormone (LH), follicle stimulating hormone (FSH) and $17{\beta}$-estradiol. Histological study of ovary and uterus of these rats exhibited reduced number of developing follicles and increased number of atretic follicles in the ovary, and fewer uterine glands with shrunken morphology, reduced endometrial height, poor vascularity and compact stroma in uterus. However, the activities of serum glutamate oxaloacetate transaminase and serum glutamate pyruvate transaminase and the body weight of the rats remained almost unaffected in all the seed extract treated rats compared to control. These results suggest that A. precatorius seed extracts reduced the levels of serum FSH, LH and $17{\beta}$-estradiol probably by affecting hypothalamic-pituitary-gonadal axis. The reduced levels of these hormones might have affected the oestrous cycle, follicular development, and subsequently the establishment of pregnancy in treated rats.

Molecular characterization and functional annotation of a hypothetical protein (SCO0618) of Streptomyces coelicolor A3(2)

Ferdous, Nadim,Reza, Mahjerin Nasrin,Emon, Md. Tabassum Hossain,Islam, Md. Shariful,Mohiuddin, A.K.M.,Hossain, Mohammad Uzzal Korea Genome Organization 2020 Genomics & informatics Vol.18 No.3

Streptomyces coelicolor is a gram-positive soil bacterium which is well known for the production of several antibiotics used in various biotechnological applications. But numerous proteins from its genome are considered hypothetical proteins. Therefore, the present study aimed to reveal the functions of a hypothetical protein from the genome of S. coelicolor. Several bioinformatics tools were employed to predict the structure and function of this protein. Sequence similarity was searched through the available bioinformatics databases to find out the homologous protein. The secondary and tertiary structure were predicted and further validated with quality assessment tools. Furthermore, the active site and the interacting proteins were also explored with the utilization of CASTp and STRING server. The hypothetical protein showed the important biological activity having with two functional domain including POD-like_MBL-fold and rhodanese homology domain. The functional annotation exposed that the selected hypothetical protein could show the hydrolase activity. Furthermore, protein-protein interactions of selected hypothetical protein revealed several functional partners those have the significant role for the bacterial survival. At last, the current study depicts that the annotated hypothetical protein is linked with hydrolase activity which might be of great interest to the further research in bacterial genetics.

A COMPARATIVE STUDY ON THE PERFORMANCES OF F₁ CROSSBRED COWS UNDER RURAL CONDITIONS

Nahar, T.N.,Islam, M.,Hasnath, M.A. Asian Australasian Association of Animal Productio 1992 Animal Bioscience Vol.5 No.3

Data were collected on productive and reproductive performance of different $F_1$ crossbred cows (Deshi cows joined by A.I. to Sindhi, Sahiwal, Jersey or Holstein-Friesian Bull semen) reared by farmers in and around the Bangladesh Agricultural University campus at Mymensingh. The traits considered were birth weight, age at first heat, age at first calving, gestation length, post-partum heat period, milk yield, lactation length, dry period and calving interval. Data were analyzed statistically using a completely randomized design and Duncan's Multiple Range Test to compare and determine the significance of between individual group means. It was observed that the Holstein $\times$ Deshi had the highest birth weight (21.4 kg) followed by Sahiwal (17.6 kg), Jersey (16.7 kg) and Sindhi (16.1 kg). Shortest age at first heat (854 and 920 days) and age at first calving (1002 and 1201 days) were found for the Jersey $\times$ Deshi and Holstein $\times$ Deshi crosses respectively. The post-partum heat period were significantly different between breeds with Jersey and Holstein sired calves having the shortest intervals. There was no difference in the gestation length of the four crosses. Holstein $\times$ Deshi and Jersey $\times$ Deshi cows gave the highest milk yields due to longer lactation periods and higher daily milk production. Similarly, Holstein $\times$ Deshi and Jersey $\times$ Deshi crosses had significantly shorter dry periods and Jersey $\times$ Deshi had a shorter calving interval. From this study it may be concluded that exotic genotypes such as Holstein-Friesian and Jersey can perform very well under rural conditions in Bangladesh.

Secrecy performance of a-k-u shadowed fading channel

A.S.M. Badrudduza,S.H. Islam,M.K. Kundu,I.S. Ansari 한국통신학회 2023 ICT Express Vol.9 No.2

In this paper, the physical layer security aspects of a wireless framework over shadowed (AKMS) fading channel are examined by acquiring closed-form novel expressions of average secrecy capacity, secure outage probability (SOP), and strictly positive secrecy capacity. The lower bound of SOP is derived along with the asymptotic expression of SOP at the high signal-to-noise ratio regime in order to achieve secrecy diversity gain. Capitalizing on these expressions, the consequences due to the simultaneous occurrence of fading and shadowing are quantified. Finally, Monte-Carlo simulations are demonstrated to assess the correctness of the expressions.

Endotoxins of Enteric Pathogens Modulate the Functions of Human Neutrophils and Lymphocytes

Islam, Laila N.,Nabi, A.H.M. Nurun Korean Society for Biochemistry and Molecular Biol 2003 Journal of biochemistry and molecular biology Vol.36 No.6

The locomotor responses of human peripheral blood neutrophils and lymphocytes were measured by the change from spherical to polarized shapes in the presence of endotoxins (lipopolysaccharide, LPS) of enteric pathogens: S. dysenteriae type 1, V. cholerae Inaba 569B, S. typhimurium, and K. pneumoniae. We reported earlier that these endotoxins are chemotactic factors for the neutrophils since they stimulated cell polarization within a few minutes of incubation. Endotoxins had an inhibitory effect upon neutrophil phagocytosis of opsonized yeast and the cells engulfed fewer yeasts. Interestingly, endotoxins increased neutrophil adhesion to clean glass surfaces, but stimulated the cells to exhibit increased random locomotion (chemokinesis) through cellulose nitrate filters and show an enhanced ability to reduce nitroblue tetrazolium (NBT) dye. Unlike neutrophils, lymphocytes direct from blood do not show polarized morphology towards chemotactic factors but the cells acquire locomotor capacity during 24-72 h culture with mitogens such as phytohemagglutinin (PHA), phorbol myristate acetate or concanavalin A. Stimulation of blood lymphocytes with endotoxins did not induce cell polarization in short-term but long-term culture resulted in an increase in the proportion of polarized cells that acquired locomotor morphologies. The majority of these cells were identified as esterase negative B-lymphocytes that migrated through filters. Despite the optimum time of incubation for each of these cell types being different, we found that lymphocytes respond to much lower concentrations of endotoxins than the neutrophils. These findings suggest that endotoxins of enteric pathogens modulate the functions of human blood neutrophils and lymphocytes.

Polymorphonuclear Neutrophil Dysfunctions in Streptozotocin-induced Type 1 Diabetic Rats

Nabi, A.H.M. Nurun,Islam, Laila N.,Rahman, Mohanmmad Mahfuzur,Biswas, Kazal Boron Korean Society for Biochemistry and Molecular Biol 2005 Journal of biochemistry and molecular biology Vol.38 No.6

Since conflicting results have been reported on non-specific immune response in type 1 diabetes, this study evaluates polymorphonuclear neutrophil (PMN) functions in the infection free Long Evan diabetic rats (type 1) by using tests that include: polarization assay, phagocytosis of baker's yeasts (Saccharomyces cerevisiae) and nitroblue tetrazolium (NBT) dye reduction. Polarization assay showed that neutrophils from diabetic rats were significantly activated at the basal level compared to those from the controls (p < 0.001). After PMN activation with N-formyl-methionyl-leucyl-phenylalanine (FMLP), control neutrophils were found to be more polarized than those of the diabetic neutrophils and the highest proportions of polarization were found to be 67% and 57% at $10^{-7}\;M$ FMLP, respectively. In the resting state, neutrophils from the diabetic rats reduced significantly more NBT dye than that of the controls (p < 0.001). The percentages of phagocytosis of opsonized yeast cells by the neutrophils from control and diabetic rats were 87% and 61%, respectively and the difference was statistically significant (p < 0.001). Evaluation of the phagocytic efficiency of PMNs revealed that control neutrophils could phagocytose $381{\pm}17$ whereas those from the diabetic rats phagocytosed $282{\pm}16$ yeast cells, and the efficiency of phagocytosis varied significantly (p < 0.001). Further, both the percentages of phagocytosis and the efficiency of phagocytosis by the diabetic neutrophils were inversely related with the levels of their corresponding plasma glucose (p = 0.02; r = -0.498 and p < 0.05; r = -0.43, respectively), which indicated that increased plasma glucose reduced the phagocytic ability of neutrophils. Such relationship was not observed with the control neutrophils. These data clearly indicate that PMN functions are altered in the streptozotocin (STZ) - induced diabetic rats, and hyperglycemia may be the cause for the impairment of their functions leading to many infectious episodes.

Endotoxins of Enteric Pathogens Modulate the Functions of Human Neutrophils and Lymphocytes

( Laila N. Islam ),( A. H. M. Nurun Nabi ) 생화학분자생물학회 2003 BMB Reports Vol.36 No.6

The locomotor responses of human peripheral blood neutrophils and lymphocytes were measured by the change from spherical to polarized shapes in the presence of endotoxins (lipopolysaccharide, LPS) of enteric pathogens: S. dysenteriue type 1, V.cholerae Inaba 569B, S. typhimurium, and K. pneumoniae. We reported earlier that these endotoxins are chemotactic factors for the neutrophils since they stimulated cell polarization within a few minutes of incubation. Endotoxins had an inhibitory effect upon neutrophil phagocytosis of opsonized yeast and the cells engulfed fewer yeasts. Interestingly, endotoxins increased neutrophil adhesion to clean glass surfaces, but stimulated the cells to exhibit increased random locomotion (chemokinesis) through cellulose nitrate filters and show an enhanced ability to reduce nitroblue tetrazolium (NBT) dye. Unlike neutrophils, lymphocytes direct from blood do not show polarized morphology towards chemotactic factors but the cells acquire locomotor capacity during 24-72 h culture with mitogens uch as phytohemagglutinin (PHA), phorbol myristate acetate or concanavalin A. Stimulation of blood lymphocytes with endotoxins did not induce cell polarization in short-term but long-term culture resulted in an increase in the proportion of polarized cells that acquired locomotor morphologies. The majority of these cells were identified as esterase negative B-lymphocytes that migrated through filters. Despite the optimum time of incubation for each of these cell types being different, we found that lymphocytes respond to much lower concentrations of endotoxins than the neutrophils. These findings suggest that endotoxins of enteric pathogens modulate the functions of human blood neutrophils and lymphocytes.