Structure of Vimose

Abstract

The structure of vimose, a novel tetrasaccharide isolated from the dried twigs of Orthenthera viminea (Family: Asclepiadaceae) has been established as O-β-L-diginopyranosyl-(1 →4)-O-β-L-diginopyranosyl-(1 →4)-O-β-L-diginopyranosyl-(1 → 4)-α-L-diginopyranose 1 on the basis of spectral and chemical evidence.     

Generalised strip-saturation zone models for piezoelectric strip weakened by non-centric semi-permeable crack

Meccanica - In this paper, we have proposed generalised strip-saturation zone models for non-centric semi-permeable straight hairline crack weakening a piezoelectric strip. Strip-saturation zone...     

Highly adequate oxidative esterification of α-carbonyl aldehydes with alkyl halides in TBAI/TBHP mediated system

An efficient and viable synthesis of α-ketoesters from alkyl halides and α-carbonyl aldehydes has been reported under metal-free conditions. The present method involves oxidative esterification of α-carbonyl aldehydes with alkyl halide using TBAI as a promoter and TBHP as an oxidant to form α-ketoesters in good to excellent yields with versatile structural diversity. Use of commercially accessible and inexpensive substrates, broad substrate scope and good functional group tolerance are the key features of this protocol.     

Amplitude death in nonlinear oscillators with indirect coupling

We investigate the effect of frequency mismatch in two indirectly coupled Rössler oscillators and Hindmarsh–Rose neuron model systems. While identical systems show in-phase or out-of-phase synchronization states when coupled through a dynamic environment, mismatch in the internal frequencies of the systems drives them to a fixed point state, i.e., amplitude death. There is a region in the parameter space of the frequency mismatch and coupling strength where system shows amplitude death. The numerical results of Rössler system are also experimentally verified using piece-wise Rössler circuits.     

Elevations of diffusion anisotropy are associated with hyper-acute stroke: a serial imaging study

Diffusion tensor imaging (DTI) studies of human ischemic stroke within 24 h of symptom onset have reported variable findings of changes in diffusion anisotropy. Serial DTI within 24 h may clarify these heterogeneous results. We characterized longitudinal changes of diffusion anisotropy by analyzing discrete ischemic white matter (WM) and gray matter (GM) regions during the hyperacute (2.5-7 h) and acute (21.5-29 h) scanning phases of ischemic stroke onset in 13 patients. Mean diffusivity (MD), fractional anisotropy (FA) and T2-weighted signal intensity were measured for deep and subcortical WM and deep and cortical GM areas in lesions outlined by a > or =30% decrease in MD. Average reductions of approximately 40% in relative (r) MD were observed in all four brain regions during both the hyperacute and acute phases post stroke. Overall, 9 of 13 patients within 7 h post symptom onset showed elevated FA in at least one of the four tissues, and within the same cohort, 11 of 13 patients showed reduced FA in at least one of the ischemic WM and GM regions at 21.5-29 h after stroke. The fractional anisotropy in the lesion relative to the contralateral side (rFA, mean+/-S.D.) was significantly elevated in some patients in the deep WM (1.10+/-0.11, n=4), subcortical WM (1.13+/-0.14, n=4), deep GM (1.07+/-0.06, n=1) and cortical GM (1.22+/-0.13, n=5) hyperacutely (< or =7 h); however, reductions of rFA at approximately 24 h post stroke were more consistent (rFA= 0.85+/-0.12).     

An Efficient Algorithm for Euclidean Shortest Paths Among Polygonal Obstacles in the Plane

We give an algorithm to compute a (Euclidean) shortest path in a polygon with h holes and a total of n vertices. The algorithm uses O(n) space and requires time. Received March 30, 1993, and in revised form August 26, 1994, and May 1, 1997.     

A mononuclear cobalt(II) hydroxo complex: synthesis,molecular structure,and reactivity studies

A novel Co(II) hydroxo complex Co{HB(3-^tBu-5-ⁱPrpz)₃}(OH) 4 {where HB(3-^tBu-5-ⁱPrpz)₃ = hydrotris(3-tert-butyl-5-isopropylpyrazol-l-yl)borate} has been prepared and its molecular structure has been determined by X-ray crystallography. This complex is mononuclear with distorted tetrahedral geometry. The reaction of CO₂ with Co{HB(3-^tBu-5-ⁱPrpz)₃}(OH) resulted in the formation of a μ-carbonato bridged binuclear complex [Co{HB(3-^tBu-5-ⁱPrpz)₃}]₂(CO₃) wherein the carbonate group is bound to both metal centers in an asymmetrical manner. In order to explore the role of labile metal complexes in promoting ester hydrolysis, complexes [Co{HB(3,5-ⁱPr₂pz)₃}]₂(OH)₂ and Co{HB(3-^tBu-5-ⁱPrpz)₃}(OH) have been used as catalysts in the hydrolysis of both carboxylate as well as phosphate esters. The product of 4-nitrophenylacetate hydrolysis with Co{HB(3-^tBu-5-ⁱPrpz)₃}(OH) was isolated as four coordinate Co{HB(3-^tBu-5-ⁱPrpz)₃}(OC₆H₄-4-NO₂) 6, whereas the reaction of 4-nitrophenyltrifluoroacetate with [Co{HB(3,5-ⁱPr₂pz)₃}]₂(OH)₂ resulted the formation of the six coordinate Co{HB(3,5-ⁱPr₂pz)₃}(OC₆H₄-4-NO₂)(MeCN)₂ species. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

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A glycan shield for bacterial sphingolipids

In this issue of Chemistry & Biology, Kinjo et al. (2008) propose that the addition of oligosaccharides to the core outer membrane glycosphingolipid in Sphingomonas spp. may be an adaptation that allows bacteria to evade recognition by Natural Killer T cells, thus suggesting a remarkable process of host/pathogen coevolution.     

Dye Degradation and Sulfur Oxidation of Methyl Orange and Thiophenol via Newly Designed Nanocomposite GQDs/NiSe-NiO Photocatalyst Under Homemade LED Light

Photocatalytic processes triggered by graphene-based photocatalysts under solar light have sparked interest as a new sort of instrument for solar chemical synthesis. Herein we investigated self-assembled graphene quantum dots (GQDs)/NiSe-NiO composite photocatalyst for organic transformation as well as dye degradation. The synthesized GQDs/NiSe-NiO composite photocatalyst has an excellent suitable band gap, high molar extinction coefficient, low toxicity and chemical/thermal stability. The GQDs/NiSe-NiO composite photocatalyst emerges as a new standard for sulfur oxidation and dye degradation reactions under homemade LED light with high yield.