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排序方式: 共有337条查询结果,搜索用时 187 毫秒
91.
Kumar Sundaravel Vivek Rani Gandhi Uma Divyalakshmi Manohar Bhuvanesh Nattamai Muthusubramanian Shanmugam Perumal Subbu 《Molecular diversity》2019,23(3):669-680
Molecular Diversity - Expedient synthesis of benzosuberone-tethered spirooxindoles was accomplished by a three-component 1,3-dipolar cycloaddition reaction between azomethine ylide (generated in... 相似文献
92.
S Uma Sankar 《Pramana》2000,54(1):27-33
I discuss the status of the accepted solutions to the solar neutrino problem in light of the super-Kamiokande data. 相似文献
93.
Uma Sharma Rajiv R. Singh Vineet Ahuja Govind K. Makharia Naranamangalam R. Jagannathan 《Magnetic resonance imaging》2010
Background
The histological extent of inflammatory bowel disease (IBD) is greater than that evident by colonoscopic evaluation. We hypothesized that metabolic profile in macroscopically un-involved colonic mucosa in IBD is similar to that of controls with healthy colon. We thus assessed the differences in metabolic profile in macroscopically involved and un-involved colonic mucosa of IBD patients to further substantiate the extent of disease.Patients and Methods
Colonic mucosal biopsies were obtained and snap frozen from both the macroscopically un-involved and involved colonic mucosa of IBD patients and macroscopically normal colonic mucosa of controls and were subjected to in-vitro high-resolution proton (1H) magnetic resonance (MR) spectroscopy and the concentrations of metabolites were determined.Results
Thirty-two metabolites were assigned in the proton MR spectrum of colonic mucosa of IBD patients. The concentrations of amino acids (isoleucine, leucine, valine, arginine, lysine, glutamine/glutamate, alanine), membrane metabolites (choline, glycerophosphorylcholine/phosphorylcholine), glycolytic product (lactate) and short chain fatty acid (formate) were significantly lower while significantly high level of glucose were observed in the macroscopically un-involved colonic mucosa of IBD patients compared to the macroscopically normal mucosa of controls. There was no significant difference in the concentrations of metabolites in macroscopically involved and un-involved colonic mucosa of IBD patients.Conclusions
The metabolic profile in macroscopically un-involved colonic mucosa of IBD patients is similar to that of macroscopically involved mucosa but different from colonic mucosa of controls. This suggests that even macroscopically un-involved colonic mucosa is metabolically abnormal and may explain the increase in extent of disease with time. 相似文献94.
Bidisha Banerjee Uma Sharma Krithika Balasubramanian M. Kalaivani Veena Kalra Naranamangalam R. Jagannathan 《Magnetic resonance imaging》2010
Randomized, placebo-controlled single blinded study was carried out to evaluate the effect of oral creatine supplementation on cellular energetics, manual muscle test (MMT) score and functional status in steroid-naive, ambulatory boys suffering with Duchenne muscular dystrophy (DMD; n=33). Eighteen patients received creatine monohydrate (Cr; 5 g/day for 8 weeks), while 15 received placebo (500 mg of vitamin C). Phosphorus metabolite ratios were determined from the right calf muscle of patients using phosphorus magnetic resonance spectroscopy (31P MRS) both prior to (baseline) and after supplementation of Cr or placebo. In addition, metabolite ratios were determined in normal calf muscle of age and sex matched controls (n=8). Significant differences in several metabolite ratios were observed between controls and DMD patients indicating a lower energy state in these patients. Analysis using analysis of covariance adjusted for age and stature showed that the mean phosphocreatine (PCr)/inorganic phosphate (Pi) ratio in patients treated with Cr (4.7; 95% CI; 3.9–5.6) was significantly higher (P=.03) compared to the placebo group (3.3; 95% CI; 2.5–4.2). The mean percentage increase in PCr/Pi ratio was also more in patients <7 years of age compared to older patients after Cr supplementation indicating variation in therapeutic effect with the age. In the placebo group, significant reduction in PCr/Pi (P=.0009), PCr/t-ATP (P=.05) and an increase in phosphodiester (PDE)/PCr ratios was observed after supplementation. Further, in the placebo group, patients <7 years showed reduction of PCr/t-ATP and Pi/t-ATP compared to older patients (>7 years), after supplementation. These results imply that the significant difference observed in PCr/Pi ratio between the Cr and the placebo groups after supplementation may be attributed to a decrease of PCr in the placebo group and an increase in PCr in the Cr group. Changes in MMT score between the two groups was significant (P=.04); however, no change in functional scale (P=.19) was observed. Parents reported subjective improvement on Cr supplementation versus worsening in placebo (P=.02). Our results indicated that Cr was well tolerated and oral Cr significantly improved the muscle PCr/Pi ratio and preserved the muscle strength in short term. However, this study provides no evidence that creatine will prove beneficial after long-term treatment, or have any positive effect on patient lifespan. 相似文献
95.
Lal UR Tripathi SM Jachak SM Bhutani KK Singh IP 《Natural product communications》2010,5(11):1767-1770
Jirakadyarishta, an Ayurvedic formulation prepared by the fermentation of a decoction of Cuminum cyminum (seeds) is traditionally used for intestinal disorders. RP-HPLC analysis of the decoction and the final processed formulation revealed that apigenin-7-O-[galacturonide (1 --> 4)-O-glucoside] and luteolin-4'-O-glucoside-7-O-galacturonide) were the two major constituents of the decoction of C. cyminum. Selective hydrolysis of 7-O-glucosides of luteolin and apigenin during fermentation resulted in an increase in the amount of luteolin and apigenin. The 4'-O-glucoside-7-O-galacturonide of luteolin and galacturonide derivative of apigenin were not hydrolyzed during fermentation. Monomeric phenolics, together with 5-hydroxymethyl furfural (5-HMF), were also introduced into the formulation through the jaggery and other plant materials during fermentation. This communication highlights the importance of the ancient processing methods used in Ayurveda. 相似文献
96.
New complexes of iron(III) of the type [(μ-Cl)2Fe2{η
2-(opbz)4] (1) and [(Cl)2Fe{η
2-(opbz)] (2) [Hopbz = {2-(o-hydroxyphenyl)}-benzimidazole, η
2 = Number of connectivity sites involved in bonding the metal] have been synthesized by the interactions of iron(III) chloride
with the corresponding ligand (Hopbz) in 1:2 and 1:1 molar ratio(s) in hot EtOH. The complex (1) was further treated with various sodium salts of Schiff bases (sb) [Na(o-smab), Na(p-smab) and Na(sap)], alkoxo-Na(OPri), aryloxo-Na(OAr) and tetraisopropoxyaluminate [Na{Al(OPri)4] in a 1:1 molar ratio (in THF–benzene medium) to produce derivatives of the type: {(η
2-(sb) Fe{η
2-opbz)2] (3), (4) and (5), [(μ-OPri)2Fe2{η-(opbz)4}] (6) [(μ-OAr)2Fe2{η-(opbz)4}] (7) and [(μ-OPri)2Al(OPri)2-Fe{η-(opbz)2}] (8). All these derivatives were characterised by elemental analysis, spectral (IR, UV–visible and FAB-mass) and magnetic susceptibility
measurements. On the basis of these studies, a distorted octahedral (dimeric) geometry around iron(III) for the complexes
(1), (6), (7) and (8) have been suggested. 相似文献
97.
Development and investigation of the flexible hydrogen sensor based on ZnO-decorated Sb2O3 nanobelts
Natarajan Pradeep Gopal Tamil Selvi Uma Venkatraman Quyet Van Le Soon Kwan Jeong Saravanan Pandiaraj Abdullah Alodhayb Muthumareeswaran Muthuramamoorthy Andrews Nirmala Grace 《Materials Today Chemistry》2021
Hydrogen is regarded as the next-gen fuel for vehicles to avoid the emission of toxic gases, which needs a continuous monitoring of the concentration level. In the design of the H2 sensor, especially of flexible type, a sensing layer will be blended, which affects the sensing performance of the device. Based on this concern, the present investigation is carried out to understand the effect of the bending angle toward the sensing performance of bare and ZnO (n-type)-decorated Sb2O3 (p-type) nanobelt–based sensors for hydrogen gas. The sensing element was prepared by the thermal chemical vapor deposition followed by the drop-casting method. Furthermore, the role of the zinc precursor (molar concentration—1 M–3 M) on the preparation of ZnO-decorated Sb2O3 nanobelts was studied. Various techniques were used to confirm the formation of ZnO-decorated nanobelts such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), and Fourier transform infrared spectroscopy (FTIR). From these analyses, 1 M concentration of the zinc precursor shows uniform distribution of nanoparticles over the surface of Sb2O3 nanobelts. However, agglomeration was observed when the concentration of the zinc precursor increases from 1 M to 3 M. Later, the prepared nanobelts were deposited on the OverHead Projector (OHP) sheet by the doctor blade method for sensing hydrogen gas at 100 °C at a concentration of 1000–3000 ppm. In addition to it, the effect of the substrate bending angle (0°, 45°, 60°, and 90°) was analyzed at a fixed concentration of H2 gas (1000 ppm). From this study, it is clear that the highest sensing response was achieved for 1 M decorated nanobelts compared with bare as well as other concentrations because of uniform distribution of nanoparticles on the surface of nanobelts. Moreover, the prepared sample demonstrates better sensing performance with the bending of substrates, which suggests that the prepared sensor could be used for flexible electronic devices. The prepared nanobelts show a good H2 gas–sensing response even with bending of the substrates. The work suggests that the prepared sensor is applicable for flexible electronic devices. 相似文献
98.
An advanced inorganic cation exchange material of the class of tetravalent metal acid (TMA) salt, zirconium titanium phosphate
(ZTP), has been synthesized by a modified sol-gel technique. ZTP has been characterized by elemental analysis (ICP-AES), thermal
analysis (TGA), FTIR and X-ray diffraction studies. The Nernst-Planck equation has been used to study the forward and reverse
ion exchange kinetics of Mg (II), Ca (II), Sr (II) and Ba (II) with H (I) at four different temperatures. The mechanism of
exchange is particle diffusion, as confirmed by the linear τ (dimensionless time parameter) vst (time) plots. The exchange process is thus controlled by the diffusion within the exchanger particles for the systems studied
herein. Further, various kinetic parameters like self-diffusion coefficient (D0), energy of activation (E
a
) and entropy of activation (ΔS*) have been evaluated under conditions favouring a particle diffusion-controlled mechanism. 相似文献
99.
S. Krishna Prasad K. L. Sandhya Geetha G. Nair Uma S. Hiremath C. V. Yelamaggad S. Sampath 《Liquid crystals》2006,33(10):1121-1125
The behaviour of the anisotropic electrical conductivity of liquid crystal-gold nanoparticle (LC-GNP) composites consisting of a commercially available room temperature nematic compound doped with alkylthiol-capped GNPs has been investigated. The nematic-isotropic transition of the composite decreases nearly linearly with increasing X, the concentration of GNP (in weight %) at a rate of about 1°C /weight %. The inclusion of GNPs increases the electrical conductivity of the system with the value increasing by more than two orders of magnitude for X = 5%. However, the anisotropy in conductivity, defined as the ratio of the conductivity along (σ∥) and orthogonal (σ⊥) to the director shows a much smaller but definite decrease as X increases. 相似文献
100.
Weakly nonlinear stability analysis of a falling film with countercurrent gas–liquid flow has been investigated. A normal
mode approach and the method of multiple scales are employed to carry out the linear and nonlinear stability solutions for
the film flow system. The results show that both supercritical stability and subcritical instability are possible for a film
flow system when the gas flows in the countercurrent direction. The stability characteristics of the film flow system are
strongly influenced by the effects of interfacial shear stress when the gas flows in the countercurrent direction. The effect
of countercurrent gas flow in a falling film is to stabilize the film flow system. 相似文献