Crude fibre as a parameter in the quality evaluation of tea

Tea is one of the oldest beverages known to mankind. Its quality is determined, among other things, by aroma and taste properties. We have paid attention herein to the fact that crude fibre is an important parameter in the quality evaluation of tea and influences its sensory properties. The elucidation of role and meaning of crude fibre in tea is attempted in this paper; therefore its content in tea from various places of origin has been determined. A significant correlation between crude fibre content and tannins content of tea samples was found (R² = 0.72).     

The role of ledges in vapor/solid phase transformations observed by low-energy electron microscopy and photoemission electron microscopy

Adsorption at monatomic ledges was observedin situ, in real time, during the epitaxial growth of Cu deposited from the vapor phase onto Mo{110}. Migration of monatomic ledges of Cu was followed during both growth and sublimation near equilibrium conditions and was independent of crystallographic direction in accord with fundamental theories of crystal growth. Evidence is presented showing that the two-dimensional (2-D) vapor pressure of Cu Actatoms on the terraces near curved ledges differs from that near straight ledges. Formerly with the Technical University of Clausthal.This paper is based on a presentation made in the symposium “The Role of Ledges in Phase Transformations” presented as part of the 1989 Fall Meeting of TMS-MSD, October 1–5, 1989, in Indianapolis, IN, under the auspices of the Phase Transformations Committee of the Materials Science Division, ASM INTERNATIONAL.     

Harmonics Generation in 4HeII by Femtosecond Laser Excitation

Non-resonant laser excitation of superfluid He by means of sub-picosecond pulses (=776 nm, 160 fs, 1 kHz) at intensities below the optical breakdown (I<4.5×10¹³ W/cm²) results in a strong emission at 258.7 nm corresponding to the third harmonic of the pump beam. Above a threshold of 0.75×10¹³ W/cm² the intensity and halfwidth of this collinear emission show a nearly linear dependence on the input pulse energy. Absolute UV energies up to 10 nJ and a conversion efficiency of about 10^–4 are observed. The emission intensity shows a significantg instability around 2.17 K.     

Convergence of an inexact generalized Newton method with a scaled residual control

The inexact generalized Newton method is an iterative method for solving systems of nonsmooth equations. In this paper, the iterative process with a relative residual control is presented and the conditions for local convergence to a solution are provided. These results can be applied to solve Lipschitz continuous equations under some mild assumptions. Moreover, a globally convergent version of the algorithm with a damped approach based on the Armijo rule is considered.     

On the effect of yttrium promotion on Ni-layered double hydroxides-derived catalysts for hydrogenation of CO2 to methane

Ni-containing mixed oxides derived from layered double hydroxides with various amounts of yttrium were synthesized by a co-precipitation method at constant pH and then obtained by thermal decomposition. The characterization techniques of XRD, elemental analysis, low-temperature N₂ sorption, H₂-TPR, CO₂-TPD, TGA and TPO were used on the studied catalysts. The catalytic activity of the catalysts was evaluated in the CO₂ methanation reaction performed at atmospheric pressure. The obtained results confirmed the formation of nano-sized mixed oxides after the thermal decomposition of hydrotalcites. The introduction of yttrium to Ni/Mg/Al layered double hydroxides led to a stronger interaction between nickel species and the matrix support and decreased nickel particle size as compared to the yttrium-free catalyst. The modification with Y (0.4 and 2 wt%) had a positive effect on the catalytic performance in the moderate temperature region (250–300 °C), with CO₂ conversion increasing from 16% for MO-0Y to 81% and 40% for MO-0.4Y and MO-2.0Y at 250 °C, respectively. The improved activity may be correlated with the increase of percentage of medium-strength basic sites, the stronger metal-support interaction, as well as decreased crystallite size of metallic nickel. High selectivity towards methane of 99% formation at 250 °C was registered for all the catalysts.