a method is described by which it is possible to determine the high barrier to ring inversion and hindered rotation by neat racemization of optically active compounds when the racemization is caused by ring inversion or hindered rotation. the method is based preparation of sufficiently pure enantiomers, mainly by chromatography on swollen microcrystalline triacetylcellulose (tac). by this techn...

In this paper, the effects of horizontal stress and dimensions of barrier pillars on the stability of drifts hr been investigated. An elastoplastic hybrid finite/boundary element program has been used. A plastic analysis of stresses in barrier pillars above the drifts in one of the underground coal mines with inclined seams is examined. Computed stresses and safety factor controur lines around ...

Background Despite successful cloning of many mammalian species, the cloning efficiency is extremely low compared to that of IVF raising the possibility of the existence of epigenetic barrier preventing successful cloning. MaterialsAndMethods Using comparative transcriptome analysis comparing transcriptomes of IVF and SCNT embryos and that of donor cells, we identified epigenetic barrier and fi...

The last decades have seen a lot of work and development on new methods neutron detection that would replace 3He gas-based detectors, device widely used due to its efficiency, which is being phased out the scarcity gas high cost. showed combination inorganic materials (Si, 6LiF) could represent viable basis for generations thermal detectors. This type based silicon detector coupled 6LiF thin fi...

We present investigation of carrier transport and trapping in 4H-SiC single crystals and high-energy radiation detectors. SiC detectors were produced from bulk vanadium-compensated semi-insulating single crystal 4H-SiC and provided with nickel ohmic and titanium Schottky contacts. The prevailing defect levels were revealed by means of thermally stimulated current and thermally stimulated depola...

In this paper, a new algorithm for edge detection based on fuzzyconcept is suggested. The proposed approach defines dynamic membershipfunctions for different groups of pixels in a 3 by 3 neighborhood of the centralpixel. Then, fuzzy distance and -cut theory are applied to detect the edgemap by following a simple heuristic thresholding rule to produce a thin edgeimage. A large number of experime...

the aim of this study was to investigate the barrier properties of cellulose nanocrystals-pvananocomposites. nanocomposite films with different filler loading levels (3, 6, 9 and 12% by wt) weredeveloped by solvent casting method. the effect of cellulose nanocrystals on the barrier properties ofthe nanocomposites was studied. to this end, moisture absorption, water vapor permeability (wvp),oxyg...

The results of electrical characterisation and X-ray detection measurements of two different active area (0.06 mm and 0.5 mm) commercial 4H-SiC Schottky photodiodes at room temperature are reported. The devices exhibited low dark currents (less than 10 pA) even at a high electric field strengths (403 kV/ cm for 0.06 mm diodes; 227 kV/cm for 0.5 mm diodes). The results of the X-ray measurements ...