Reaction of Nα-acetyl-dl-tryptophan amide with d-xylose or d-glucose in acidic solution

The reaction of $\text{N}{}^{\mathrm{\alpha }}\text{-}\text{acetyl}\text{-}\text{dl}\text{)-}\text{tryptophan}$ amide (a model for proteinbound tryptophan) with either $\text{d}\text{-}\text{xylose}$ or $\text{d}\text{-}\text{glucose}$ in acidic solution at 75 or 100°C gave the respective $\text{N}{}^{\mathrm{\alpha }}\text{-}\text{acetyl}\text{-1-(β-}\text{d}\text{-}\text{glycopyranosyl}\text{)-}\text{dl}\text{-}\text{tryptophan}$ amides as the main products in 10–20% yield. These results indicate that the indole nitrogen of protein-bound tryptophan may react with reducing carbohydrates during acid hydrolysis of proteins or, to a lesser extent, during food processing in acidic conditions.     

Structure cristalline du spinelle CdEr2S4

The crystal structure of CdEr₂S₄ is solved from single crystal determinations. The R factor is 0.06 for 120 independent reflections. It is normal spinel, with regular occupancy of the sites. Interatomic distances are : 2.67 Å for ErS, and 2.57 Å for CdS.     

Shear strengthening of old concrete beams

In our March-April issue last year, the author described work at the Czech Technical University in Prague on the use of epoxy resins to apply new flat reinforcement to old concrete beams in order to enhance or prolong their service life. Here, some further test results and general conclusions are presented on the application of this technique to shear strengthening. The author is Associate Professor of Civil Engineering at the University.     

Hydrophobic polyelectrolytes and polysoaps. Ionization of weakly basic groups and conformation in aqueous solution of some derivatives of poly(4-vinyl pyridine)

Two different types of cationic polysoaps were prepared in order to study the ionization equilibria of weakly basic groups incorporated in such polymers. A major concern in this work has been an exploration of the effect of temperature on the intrinsic basicity of the ionizable groups, a question of considerable relevance, for example, in the development of thermally regenerable ion exchange resins. The results lead to models that should be helpful in elucidating trends in the basicity of functional groups in polyelectrolytes incorporating hydrophobic residues. A basic resin with greatly enhanced thermal effect has been prepared which provides support for present models of the hydrophobic effect.     

Role of monoamines in the control of hormones of sexual receptivity in the female rat.

Investigated the involvement of indole- and catecholamines in the hormonal regulation of sexual receptivity in ovariectomized Sprague-Dawley rats. Drugs that reduce 5-hydroxytryptamine, dopamine, and adrenaline or increase noradrenaline neurotransmission tended to facilitate the occurrence of estrous behavior in estrogen-treated Ss, and drugs having opposite effects tended to inhibit receptivity induced by estrogen and progesterone. Estrogen decreased noradrenaline turnover in cortex and brain stem; progesterone enhanced this effect in brain stem but prevented it in cortex. Both hormones tended to block noradrenaline uptake in hypothalamus in vitro. In a schedule used to induce receptivity, estrogen accelerated serotonin turnover, an effect prevented by progesterone. Results suggest that a number of monoamines may be involved in the control by hormones of estrous behavior and that hormones affect both amine turnover and uptake mechanisms. (85 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of powder characteristics on pressure sensitivity of powder injection moulding compounds

Pressure effect on the rheological behaviour of powder-polymer compounds intended for powder injection moulding was determined. A single-piston capillary rheometer modified by addition of a second chamber with a restricting needle valve generating backpressure increasing the pressure in the melted material during the flow through the die was employed to determine pressure sensitivity coefficients. The results obtained for three compounds varying in the characteristics of powders used confirmed that compounds at the loading level close to the maximum packing are more sensitive to pressure than polymer binder. It is shown that pressure sensitivity coefficients of these materials are strongly dependent on powder characteristics — particle size and particle size distribution. The highest coefficient (32.9 GPa⁻¹) was found for compound containing broad particle size distributed powder having a perceptible portion of small particles.     

Chronic toxicity of verapamil on juvenile rainbow trout (Oncorhynchus mykiss): effects on morphological indices, hematological parameters and antioxidant responses

In this study, the toxic effects of verapamil (VRP) were studied on juvenile rainbow trout, Oncorhynchus mykiss, by chronic semi-static bioassay. Fish were exposed to sublethal concentrations of VRP (0.5, 27 and 270 μg/L) for 0, 21 and 42 d. Multiple biomarkers were measured, including morphological indices, hematological parameters and antioxidant responses of different tissues (brain, gill, liver, muscle and intestine). Based on the results, there was no significant change in all parameters measured in fish exposed to VRP at environmental related concentration, but VRP-induced stress in fish exposed to higher concentrations reflected the significant changes of physiological and biochemical responses. Through principal component analysis and integrated biomarker response assessment, effects induced by VRP-stress in each test group were distinguished. Additionally, all parameters measured in this study displayed various dependent patterns to VRP concentrations and exposure time using two-way ANOVA statistic analysis. In short, the multiple responses in fish indicated that VRP induced physiological stress and could be used as potential biomarkers for monitoring residual VRP in aquatic environment; but molecular and genetic mechanisms of these physiological responses in fish are not clear and need to be further studied.     

Rapid annealing of reactively sputtered precursors for Cu2ZnSnS4 solar cells

Cu₂ZnSnS₄ (CZTS) is a promising thin‐film absorber material that presents some interesting challenges in fabrication when compared with Cu(In,Ga)Se₂. We introduce a two‐step process for fabrication of CZTS films, involving reactive sputtering of a Cu‐Zn‐Sn‐S precursor followed by rapid annealing. X‐ray diffraction and Raman measurements of the sputtered precursor suggest that it is in a disordered, metastable CZTS phase, similar to the high‐temperature cubic modification reported for CZTS. A few minutes of annealing at 550 °C are sufficient to produce crystalline CZTS films with grain sizes in the micrometer range. The first reported device using this approach has an AM1.5 efficiency of 4.6%, with J_sc and V_oc both appearing to be limited by interface recombination. Copyright © 2012 John Wiley & Sons, Ltd.