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1.
A catalyst-free green methodology for the synthesis of pharmacologically important spirooxindole derivatives has been developed by a three-component domino reaction between isatin, various amino compounds, and 1,3-dicarbonyl or 3-phenylisoxazolone compounds in ethyl l-lactate medium at room temperature. This new efficient synthetic method facilitated the formation of a wide range of biologically significant spirooxindole derivatives (including 17 new spirooxindoles) under very mild conditions. The cytotoxic activity of one of the isoxazole-fused spirooxindoles was evaluated in MDA-MB 468 breast cancer cell line. It was found that cell survivability decreases with increasing concentration of the selected compound in MDA-MB 468 breast cancer cells. 相似文献
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Masum SM Li SJ Awad TS Yamazaki M 《Langmuir : the ACS journal of surfaces and colloids》2005,21(12):5290-5297
To elucidate the stability and phase transition of cubic phases of biomembranes with infinite periodic minimal surface is indispensable from biological and physicochemical aspects. In this report, we investigated the effect of positively charged peptide-3K (LLKKK) and poly(L-lysine) on the phase stability of monoolein (MO) membranes containing negatively charged dioleoylphosphatidic acid (DOPA) (i.e., DOPA/MO membranes) using small-angle X-ray scattering. At first, the effect of peptide-3K on 10% DOPA/90% MO membrane in excess water, which is in the Q229 phase, was investigated. At 3.4 mM peptide-3K, a Q229 to Q230 phase transition occurred, and at >3.4 mM peptide-3K, the membrane was in the Q230 phase. Poly(L-lysine) (M(w) 1K-4K) also induced the Q230 phase, but peptide-2K (LLKK) could not induce it in the same membrane. We also investigated the effect of peptide-3K on the multilamellar vesicle (MLV) of 25% DOPA/75% MO membrane, which is in L(alpha) phase. In the absence of peptide, the spacing of MLV was very large (11.3 nm), but at > or = 8 mM peptide-3K, it greatly decreased to a constant value (5.2 nm), irrespective of the peptide concentration, indicating that peptide-3K and the membranes form an electrostatically stabilized aggregation with low water content. Poly(L-lysine) also decreased greatly the spacing of the 25% DOPA/75% MO MLV, indicating the formation of a similar aggregation. To compare the effects of peptide-3K and poly(L-lysine) with that of osmotic stress on stability of the cubic phase, we investigated the effect of poly(ethylene glycol) with molecular weight 7500 (PEG-6K) on the phase stability of 10% DOPA/90% MO membrane. With an increase in PEG-6K concentration, i.e., with an increase in osmotic stress, the most stable phase changed as follows; Q229 (Schwartz's P surface) --> Q224 (D) --> Q230 (G). On the basis of these results, we discuss the mechanism of the effects of the positively charged short peptides (peptide-3K) and poly(L-lysine) on the structure and phase stability of DOPA/MO membranes. 相似文献
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Sohan Md. Sohanur Rahman Hasan Mahedi Hossain Md. Forhad Sajib Salek Ahmed Miah Md. Masum Iqbal Md. Asif Karmakar Sumon Alam Md. Jahangir Khalid-Bin-Ferdaus Khandaker Md. Kabir Ahmad Humayan Rashid Md. Mamunur Talukder Mamunur Rashid Reza Md Abu 《Plasma Chemistry and Plasma Processing》2021,41(3):923-944
Plasma Chemistry and Plasma Processing - Plasma agriculture is an emerging field. In this report, we studied the effect of medium pressure (~?10 torr) low-frequency... 相似文献
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Huseyin Masum Sayipjamal Dulat Mutallip Tohti 《International Journal of Theoretical Physics》2017,56(9):2724-2737
The energy levels of hydrogen-like atom on a noncommutative phase space were studied in the framework of relativistic quantum mechanics. The leading order corrections to energy levels 2S 1/2, 2P 1/2 and 2P 3/2 were obtained by using the ?? and the \(\bar \theta \) modified Dirac Hamiltonian of hydrogen-like atom on a noncommutative phase space. The degeneracy of the energy levels 2P 1/2 and 2P 3/2 were removed completely by ??-correction. And the \(\bar \theta \)-correction shifts these energy levels. 相似文献
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Okamoto Y Masum SM Miyazawa H Yamazaki M 《Langmuir : the ACS journal of surfaces and colloids》2008,24(7):3400-3406
Cubic biomembranes, nonbilayer membranes with connections in three-dimensional space that have a cubic symmetry, have been observed in various cells. Interconversion between the bilayer liquid-crystalline (L(alpha)) phase and cubic phases attracted much attention in terms of both biological and physicochemical aspects. Herein we report the pH effect on the phase and structure of dioleoylphosphatidylserine (DOPS)/monoolein (MO) membranes under a physiological ion concentration condition, which was revealed by small-angle X-ray scattering (SAXS) measurement. At neutral pH, DOPS/MO membranes containing high concentrations of DOPS were in the L(alpha) phase. First, the pH effect on the phase and structure of the multilamellar vesicles (MLVs) of the DOPS/MO membranes preformed at neutral pH was investigated by adding various low-pH buffers into the MLV suspension. For 20%-DOPS/80%-MO MLVs, at and below pH 2.9, a transition from the L(alpha) to cubic (Q(224)) phase occurred within 1 h. This phase transition was reversible; a subsequent increase in pH to a neutral one in the membrane suspension transformed the cubic phase into the original L(alpha) phase. Second, we found that a decrease in pH transformed large unilamellar vesicles of DOPS/MO membranes into the cubic phase under similar conditions. We have proposed the mechanism of the low-pH-induced phase transition and also made a quantitative analysis on the critical pH of the phase transition. This finding is the first demonstration that a change in pH can induce a reversible phase transition between the L(alpha) and cubic phases of lipid membranes within 1 h. 相似文献
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Md. Masum Haider Tahmina Ferdous Syed S. Duha 《Central European Journal of Physics》2014,12(9):701-706
The nonlinear propagation of small but finite amplitude dust-ion-acoustic solitary waves in a magnetized, collisionless dusty plasma is investigated theoretically. It has been assumed that the electrons are trapped following the vortex-like distribution and that the negatively and positively charged ions are mobile with the presence of charge fluctuating stationary dusts, where ions mass provide the inertia and restoring forces are provided by the thermal pressure of hot electrons. A reductive perturbation method was employed to obtain a modified Korteweg-de Vries (mK-dV) equation for the first-order potential and a stationary solution is obtained. The effect of the presence of trapped electrons, negatively and positively charged ions and arbitrary charged dust grains are discussed. 相似文献
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Sajib Salek Ahmed Billah Mutasim Mahmud Shafi Miah Masum Hossain Forhad Omar Farjana Binta Roy Nepal Chandra Hoque Kazi Md Faisal Talukder Mamunur Rashid Kabir Ahmad Humayun Reza Md Abu 《Plasma Chemistry and Plasma Processing》2020,40(1):119-143
Plasma Chemistry and Plasma Processing - Chemical fertilization in agriculture is threatening to the ecosystem. Therefore, the use of eco-friendly stimulant for crop revolution is highly desirable.... 相似文献
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M. Masum Haider Suraya Akter Syed S. Duha Abdullah A. Mamun 《Central European Journal of Physics》2012,10(5):1168-1177
The basic features and multi-dimensional instability of electrostatic (EA) solitary waves propagating in an ultra-relativistic degenerate dense magnetized plasma (containing inertia-less electrons, inertia-less positrons, and inertial ions) have been theoretically investigated by reductive perturbation method and small-k perturbation expansion technique. The Zakharov-Kuznetsov (ZK) equation has been derived, and its numerical solutions for some special cases have been analyzed to identify the basic features (viz. amplitude, width, instability, etc.) of these electrostatic solitary structures. The implications of our results in some compact astrophysical objects, particularly white dwarfs and neutron stars, are briefly discussed. 相似文献
10.
Mahmudul H. Khandker Nazifa T. Arony A. K. F. Haque M. Maaza M. Masum Billah 《Molecular physics》2020,118(14)
The differential, integrated elastic, inelastic, total, momentum transfer, viscosity, and ionisation cross sections for electron and positron scattering from the homonuclear diatomic nitrogen molecule over an incident energy range of 1?eV–10?keV are calculated using the additivity rule. Dirac partial wave analysis is employed to calculate the cross sections of the constituent atoms of molecules, using a complex optical model potential (OPM). Comparison of our results of the additivity rule with the available experimental data and other theoretical predictions is presented. Our findings produce reasonable results in intermediate and high energies. 相似文献