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51.
It is shown that a large class of solutions of Yang's equations for self-dual SU(2) gauge fields can be obtained from the solutions of two-dimensional and four-dimensional Laplace equations. 相似文献
52.
Nadanathangam Vigneshwaran Gopalakrishnapillai Bijukumar Nivedita Karmakar Sneh Anand Anoop Misra 《Macromolecular Symposia》2003,193(1):119-128
Isoelectric focusing (IEF) of glycated hemoglobin (GHb) was carried out in ultra-thin polyacrylamide gels to separate the hemoglobin-advanced glycation endproducts (Hb-AGEs) from the hemoglobin-A1C (HbA1C) fraction. Precast polyacrylamide gels (Ampholine® PAGplate) were used in Pharmacia LKB Multiphor II for this purpose. The separated bands for Hb-AGE and HbA1C based on their isoelectric point (pI), were confirmed with the purifed fractions obtained from the cation exchange chromatographic technique. From the calibration curve, the pI values were found to be 6.748 and 6.495 for HbA1C and Hb-AGE, respectively. The lowering of pI values for glycated hemoglobin, when compared to unglycated hemoglobin (pI = 6.852), can be attributed to the glycation at the amino terminals of the peptide chains. Increased reduction in pI value for Hb-AGE can be attributed to the effect of glycation of amino groups at various sites on the peptide chains, apart from the terminal amino groups. Fluorescence analysis was carried out for the purified fraction of Hb-AGE which showed the formation of a new fluorophor adduct having the excitation and emission maxima at 308 nm and 345 nm, respectively. Time-dependent formation of Hb-AGE under in vitro conditions was monitored by fluorescence (308/345 nm) over a period of 120 days, which showed its formation only after 3 weeks of incubation. 相似文献
53.
I. Banerjee Soumen Karmakar Naveen V. Kulkarni Ashok B. Nawale V. L. Mathe A. K. Das S. V. Bhoraskar 《Journal of nanoparticle research》2010,12(2):581-590
The synthesis of nanoparticles of titanium dioxide (TiO2) with varying percentages of anatase and rutile phases is reported. This was achieved by controlling the operating pressure
in a transferred-arc, direct current thermal plasma reactor in which titanium vapors are evaporated, and then exposed to ambient
oxygen. The average particle size remained around 15 nm in each case. The crystalline structure of the as-synthesized nanoparticles
of TiO2 was studied with X-ray diffraction analysis; whereas the particle morphology was investigated with the help of transmission
electron microscopy. The precursor species responsible for the growth of these nanoparticles was studied with the help of
optical emission spectroscopy. As inferred from the X-ray diffraction analysis, the relative abundance of anatase TiO2 was found to be dominant when synthesized at 760 Torr, and the same showed a decreasing trend with decreasing chamber pressure.
The study also reveals that anatase TiO2 is a more effective photocatalytic agent in degrading methylene blue by comparison to its rutile phase. 相似文献
54.
The neutralization of low energy 7Li+ scattered from Au nanoclusters deposited on TiO2(110) was measured with time-of-flight spectroscopy as a function of cluster size, emission angle, and ion energy. The neutralization shows maxima for cluster diameters approximately 3 nm, and again for thick Au films. The data are compared to previous experiments with Na projectiles. Possible explanations of the observed effects are discussed. 相似文献
55.
Indrajyoti Mukherjee Dipankar Haldar Soumen Ghosh 《Journal of Dispersion Science and Technology》2013,34(10):1430-1441
APSA-80, an useful pesticide spray adjuvant is a mixture of 2-[2-(4-nonylphenoxy) ethoxy] ethanol, 1-butanol and tall oil fatty acids. It is strongly surface active and can decrease the surface tension of water to ~20 mNm?1 at its critical micelle concentration (CMC) of 0.006 g%. APSA-80 itself and its binary mixtures, (APSA-80 + water) and (APSA-80 + isopropylmyristate [IPM]) and ternary mixtures (APSA-80 + water +IPM) can undergo a number of physical changes with rise in temperature; the main changes are in color, turbidity and phases. The ternary mixtures of APSA-80/water/IPM with changing compositions can form mono-, bi-, and triphasic solutions as well as gels and viscous solutions. The gel and viscous phases show characteristic rheological properties of both shear thinning and thickening types. They also show permeation of hydrophilic and oleophilic dyes through them. SEM and optical microscopic measurements have shown interesting surface morphologies of the gels and their vertical projections in three-dimensional pictorial mode. Salts like LiCl, NaCl, KCl, CsCl, MgSO4, and Al2(SO4)3 can have both minor and major effects on the gel consistencies. The alkanols like ethanol, propanol, and isopropanol are also mild to fairly large gel influencing co solvents. The antibacterial properties of APSA-80 have been studied with two Gram positive bacteria and a yeast; the activities found were moderate. 相似文献
56.
Kinetic studies of the aminolysis of [methyl(thiomethyl)carbene]pentacarbonyl chromium(0),(CO)5CrC(CH3)(SCH3) (1-Cr(S)) and [methyl(thiomethyl)carbene]pentacarbonyltungsten(0), (CO)5WC(CH3)(SCH3) (1-W(S)), with morpholine, a secondary amine, in 50% acetonitrile-50% H2O (v/v at 25 °C) is reported. The second-order rate constant (kA in m−1 s−1) increases with amine concentration, giving a linear dependence with an intercept on the rate axis and a tendency towards leveling off at higher amine concentration. The reaction was found to undergo general base catalysis. The mechanism proposed is very similar to those for ester reactions, involving a nucleophilic addition of amine to the substrate to yield a zwitterionic tetrahedral intermediate in the first step, followed by deprotonation to form in the second step, which, in the third step, converted to product by H2O and/or conjugate acid of the base (BH+), assisted MeS− expulsion. The reactivity (k1) of 1-W(S) was found to be higher than that of 1-Cr(S), whereas, comparable , water catalyzed and , BH+ catalyzed, leaving group departure were found for both the carbenes complexes. All these observations have been explained successfully. 相似文献
57.
Chloramphenicol and thiamphenicol have been enantioselectively synthesized using an asymmetric halohydrin reaction as a key step. In particular, halomethoxylation reaction was used, where O-methyl functions as a hydroxyl protecting group and eliminates an additional protection step. 相似文献
58.
Subhasis Mallick Subala Mondal Arup Mandal Biplab K. Bera Parnajyoti Karmakar Alak K. Ghosh 《国际化学动力学杂志》2011,43(9):498-506
The kinetics of the interaction of three glycine‐containing dipeptides, namely, glycine‐L‐leucine (Gly‐Leu), glycine‐L‐isoleucine (Gly‐Ile), and glycine‐valine (Gly‐Val) with [Pt(en)(H2O)2](ClO4)2 has been studied spectrophotometrically as a function of [substrate complex], [dipeptides] and temperature at a particular pH(4.0), where the substrate complex exists predominantly as the diaqua species and the dipeptides as a zwitterion. The substitution reaction shows two consecutive steps; the first is the ligand‐assisted anation and the second is the chelation step. The activation parameters for both the steps were evaluated using Eyring's equation. The low ΔH1≠ and large negative value of ΔS1≠ as well as ΔH2≠ and ΔS2≠ indicate an associative mode of activation for both the aqua ligand substitution processes. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 498–506, 2011 相似文献
59.
Chakraborty TK Roy S Koley D Dutta SK Kunwar AC 《The Journal of organic chemistry》2006,71(16):6240-6243
Cyclic oligomers of tetrahydrofuran amino acids, cyclo-(Taa1-Leu-Val)2 (left), cyclo-(Taa2-Leu-Val)2 (middle), and cyclo-(Taa2-Phe-Leu)2 (right), displayed well-defined intramolecularly hydrogen-bonded structures with distorted "beta-beta corner" motifs similar to the tennis ball seam. 相似文献
60.
Two Ru(II) complexes, [Ru(bpy)2L](ClO4)2 (1) and [Ru(bpy)2L'](BF4)2 (2), where bpy is 2,2'-bipyridine, L is diacetyl dihydrazone, and L' 1:2 is the condensate of L and acetone, are synthesized. From X-ray crystal structures, both are found to contain distorted octahedral RuN(6)(2+) cores. NMR spectra show that the cations in 1 and 2 possess a C2 axis in solution. They display the expected metal-to-ligand charge transfer (1MLCT) band in the 400-500 nm region. Complex 1 is nonemissive at room temperature in solution as well as at 80 K. In contrast, complex 2 gives rise to an appreciable emission upon excitation at 440 nm. The room-temperature emission is centered at 730 nm (lambda(em)(max)) with a quantum yield (Phi(em)) of 0.002 and a lifetime (tau(em)) of 42 ns in an air-equilibrated methanol-ethanol solution. At 80 K, Phi(em) = 0.007 and tau(em) = 178 ns, with a lambda(em)(max) of 690 nm, which is close to the 0-0 transition, indicating an 3MLCT excited-state energy of 1.80 eV. The radiative rate constant (5 x 10(4) s(-1)) at room temperature and 80 K is almost temperature independent. From spectroelectrochemistry, it is found that bpy is easiest to reduce in 2 and that L is easiest in 1. The implications of this are that in 2 the lowest (3)MLCT state is localized on a bpy ligand and in 1 it is localized on L. Transient absorption results also support these assignments. As a consequence, even though 2 shows a fairly strong and long-lived emission from a Ru(II) --> bpy CT state, the Ru(II) --> L CT state in 1 shows no detectable emission even at 80 K. 相似文献