Molar extinction coefficients of some carbohydrates in aqueous solutions

Molar extinction coefficients of some carbohydrates viz. l-arabinose (C₅H₁₀O₅), d-glucose (C₆H₁₂O₆), d-mannose (C₆H₁₂O₆), d-galactose (C₆H₁₂O₆), d(-) fructose (C₆H₁₂O₆) and maltose (C₁₂H₂₄O₁₂) in aqueous solutions have been determined at 81, 356, 511, 662, 1173 and 1332 keV by gamma ray transmission method in a narrow beam good geometry set-up. These coefficients have been found to depend upon the photon energy following a 4-parameter polynomial. These extinction coefficients for different sugars having the same molecular formula have same values varying within experimental uncertainty. Within concentration ranges studied, Beer-Lambert law is obeyed very well.     

Similarity in the metabolic profile in macroscopically involved and un-involved colonic mucosa in patients with inflammatory bowel disease: an in vitro proton (H) MR spectroscopy study

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.     

Homoconjugation in the adamantane cage: DFT/IGLO studies of the 1, 3-dehydro-5-adamantyl cation, its isoelectronic boron analogue 1, 3-dehydro-5-boraadamantane, and related systems(1)(,)

The structure of 1,3-dehydro-5-adamantyl cation and its isoelectronic boron analogue 1,3-dehydro-5-boraadamantane as well as some related adamantane systems, hitherto unknown as persistent long-lived species, were investigated by using the density functional theory (DFT) method. (13)C and (11)B NMR chemical shifts of the compounds were also calculated using the IGLO method. Stabilization of the systems due to homoconjugation is discussed.     

Theoretical study of relative width of photonic band gap for the 3-D dielectric structure

Calculations for the relative width (Δω/ω₀) as a function of refractive index and relative radius of the photonic band gap for the fcc closed packed 3-D dielectric microstructure are reported and comparison of experimental observations and theoretical predictions are given. This work is useful for the understanding of photonic crystals and occurrence of the photonic band gap.     

Metabolism of the colonic mucosa in patients with inflammatory bowel diseases: an in vitro proton magnetic resonance spectroscopy study

Metabolism of the colonic mucosa of patients with ulcerative colitis (UC; n=31) and Crohn's disease (CD; n=26) and normal mucosa (control, n=26) was investigated using in vitro high-resolution proton magnetic resonance spectroscopy. Of the 31 UC patients, 20 were in the active phase and 11 were in the remission phase of the disease. Out of 26 CD patients, 20 were in the active phase, while 6 were in the remission phase of the disease. Twenty-nine metabolites were assigned unambiguously in the perchloric acid extract of colonic mucosa. In the active phase of UC and CD, significantly lower (P相似文献   

离子液体作为溶剂/催化剂用于卤代烃对胺的选择性烷基化反应

在三乙胺存在下,在离子液体([bmim]I和[bmim]PF6)中进行了各种卤代烃对胺类化合物中氨基的选择性烷基化反应.反应在相对温和的条件下进行,转化率和选择性优异.离子液体可以回收并重复使用.     

High quality beam shaping by square soft-edge diaphragm combined with liquid crystal spatial light modulator

<正>The square soft-edge diaphragm with round angle is designed by Matlab,and is sent to a liquid crystal spatial light modulator by the computer.In order to obtain precompensation for the following laser system, local diaphragm transmission can be adjusted by feedback signals of surface-channel charge-coupled device (SCCD).This method can reduce the diffraction effect and realize no modulation,high stability,high homogeneity,and large scale laser beam.Several parameters of soft-edge diaphragms which affect the laser beam quality are studied systematically,and the optimized values are obtained.The method can avoid the serious modulation of hard edges and provide soft-edge diaphragms of different shapes in a fast and convenient way for the large scale laser beam system.