Fusion around the barrier for 7Li+12C

Fusion cross-sections for the ⁷Li + ¹²C reaction have been measured at energies above the Coulomb barrier by the direct detection of evaporation residues. The heavy evaporation residues with energies below 3 MeV could not be separated out from the α-particles in the spectrum and hence their contribution was estimated using statistical model calculations. The present work indicates that suppression of fusion cross-sections due to the breakup of ⁷Li may not be significant for ⁷Li + ¹²C reaction at energies around the barrier.     

On the convergence of finite difference schemes for the heat equation with concentrated capacity

Summary. We investigate the convergence of difference schemes for the one-dimensional heat equation when the coefficient at the time derivative (heat capacity) is represents the magnitude of the heat capacity concentrated at the point . An abstract operator method is developed for analyzing this equation. Estimates for the rate of convergence in special discrete energetic Sobolev's norms, compatible with the smoothness of the solution are obtained. Received November 2, 1999 / Revised version received July 24, 2000 / Published online May 4, 2001     

Nitrogen-oxygen and oxygen-oxygen alkyl group migrations. synthesis of 1,2,4-triazine hydroxamic acid esters

Novel 1,2,4-triazine hydroxamic acid esters and alkylated 2, 3-dihydro-1,2,4-triazine N-oxides were prepared by rearrangement and selective alkylations of 3-alkoxy and 3-alkylamino-1,2,4-triazine N-oxides.     

Synthesis and crystal structure of 5-methyl-5,10-dihydrophenarsazine

The X-ray crystal structure of 5-methyl-5,10-dihydrophenarsazine, C₁₃H₁₂NAs, has been determined. The crystals are orthorhombic, space group P2₁2₁2₁, a = 8.511(4), b = 5.690(1), c = 23.535(9) Å, V = 1139.7(1.0)A³, and Z = 4. Least-squares refinement converged to R = 0.049 and Rw = 0.045. The central ring is in a boat conformation and the 5-methyl group is in the axial position with respect to the central ring. The folding angle between the planes of the two benzo rings is 154.1(4)°.     

Comprehensive Evaluation of Antioxidant Activity of Ribes berry Fruit Species: A Chemometric Approach

Currant fruit extracts were characterized by (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, 2,2-azinobis-3 ethyl benzothiazoline-6-sulfonic acid cation decolorization activity, total reducing power, cupric ion reducing antioxidant power, and ferric ion reducing antioxidant power (FRAP) assays to evaluate their antioxidant activity. All five antioxidant assays revealed the highest antioxidant activity to be present for the black currants. The highest concentrations of phenolics were present in the black currants (1690?±?10?mg gallic acid equivalents (GAE)/100?g fresh weight), while the lowest value was obtained in the white currants (579?±?5?mg GAE/100?g fresh weight). The correlation between the total phenolic content and antioxidant activity assays was evaluated using regression analysis. A significant positive correlation was obtained between the total phenols and the cupric ion reducing antioxidant power (r?=?0.97, p?r?=?0.93, p?相似文献   

Measuring the performance of quality assurance processes: pharmaceutical industry deviation management case study

This article presents experience from the practice of a successful pharmaceutical company related to design and implementation of performance measures (PMs) for deviation management linked to the analysis of impact on the production cost for the selected product. Case study focuses on PMs within good manufacturing practice (GMP) processes related to quality assurance (QA) and quality management, with the aim of complying with its future requirements proposed by the European Commission. Critical areas were identified based on data gathered from the industrial deviation database. Implementation of the suggested corrective actions showed significant improvement in terms of reducing their number for more than 50% per selected deviation category. The results obtained in the course of this practice-oriented study contribute to further improvement of deviation management in the pharmaceutical industry and performance measurement of other GMP processes. The suggested performance measurement concept and problem-solving techniques may serve both practitioners and the decision-makers within QA and quality control (QC) in order to improve their processes by implementing relevant regulatory requirements for quality management and maintain compliance.     

Radical cation formation and crystal structure determination of 4′-dimethylamino-10-phenylpyrido[3,2-b]benzothiazine

The crystal structure of title compound, 4 , shows that the 10-aryl group is parallel to the plane bisecting the pyridobenzothiazine ring. This structure is in contrast to that normally found for phenothiazines substituted with electron-withdrawing substituents on the 10-phenyl ring. In those compounds, the 10-aryl group is perpendicular to the plane bisecting the phenothiazine ring. The esr spectrum of the cation radical of 4 shows that the radical is located on the hetero ring system which is opposite to that of the cation radical of 4′-dimethylamino-10-phenylphenothiazine in which the radical is located on the 10-aryl ring.     

1D stability analysis of filtering and controlling the solitons in Bose-Einstein condensates

We present one-dimensional (1D) stability analysis of a recently proposed method to filter and control localized states of the Bose–Einstein condensate (BEC), based on novel trapping techniques that allow one to conceive methods to select a particular BEC shape by controlling and manipulating the external potential well in the three-dimensional (3D) Gross–Pitaevskii equation (GPE). Within the framework of this method, under suitable conditions, the GPE can be exactly decomposed into a pair of coupled equations: a transverse two-dimensional (2D) linear Schr?dinger equation and a one-dimensional (1D) longitudinal nonlinear Schr?dinger equation (NLSE) with, in a general case, a time-dependent nonlinear coupling coefficient. We review the general idea how to filter and control localized solutions of the GPE. Then, the 1D longitudinal NLSE is numerically solved with suitable non-ideal controlling potentials that differ from the ideal one so as to introduce relatively small errors in the designed spatial profile. It is shown that a BEC with an asymmetric initial position in the confining potential exhibits breather-like oscillations in the longitudinal direction but, nevertheless, the BEC state remains confined within the potential well for a long time. In particular, while the condensate remains essentially stable, preserving its longitudinal soliton-like shape, only a small part is lost into “radiation”.     

13C NMR spectroscopy of heteroaromatic compounds: A quantitative measure of electron deficiency and excessiveness

A quantitative measure, ^πΔ, for expressing the π-deficiency and π-excessiveness of heteroaromatic compounds has been developed through ¹³C NMR chemical shift studies. An example which correlates electrophilic reactivity in π-excessive systems with ^πΔ of these compounds is given. The following decreasing order of π-excessiveness and increasing π-deficiency of a number of heteroaromatic systems has been established (numbers in parentheses correspond to ^πΔ): tellurophene (1.83), selenophene (1.43), thiophene (1.35), furan (1.31), benzene (1.00), pyrazine (1.00) pyridine (0.89), pyrimidine (0.77), pyridazine (0.71), 1,2,4-triazine (0.64). These correlations also allow the prediction of ¹³C chemical shifts in substituted heteroaromatic compounds, where the ratio of the difference between a given substituted heterocyclic compound and its parent, and the identically substituted benzene derivative, has been determined.