Zur Reaktion der N-Sulfinylamine mit Isocyaniden und die Synthese von 2,5-Diaryl-3,4-diarylimino-1,2,5-thiadiazolidin-S-oxiden

The Reaction of N-Sulfinylamines with Isocyanides and Synthesis of 2,5-Diaryl-3,4-diarylimino-1,2,5-thiadiazolidin-S-oxides N-Sulfinylamines 1 react with isocyanides 2 to give isocyanates 3 , isothiocyanates 6 , and especially 2,5-diaryl-3,4-diarylimino-1,2,5-thiadiazolidin-S-oxides 7 . This new heterocyclic ring system 7 can also be synthesized in high yields by a cyclization reaction of tetraarylated oxalic amidines 9 with thionyl chloride. The acid catalyzed hydrolysis of the heterocyclic compounds 7 leads to oxalic anilides 8 , the hydrolysis with alkali forms amidines 9 . The amidine 9a reacts with N-sulfinyl-p-toluenesulfonamide 11 to give an open chained adduct 12 .     

Methods used for the isolation, enumeration, characterisation and identification of Enterococcus spp. 2. Pheno- and genotypic criteria

This paper reviews the methodology applied for the identification and characterisation of enterococci and covers phenotypic, genotypic and phylogenetic techniques. Although conventional phenotypic typing schemes are useful for rapid and simple identification of enterococcal species for routine applications, other methods like standardised sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE), multilocus enzyme electrophoresis (MLEE), antimicrobial susceptibility testing, serotyping, pyrolysis mass spectrometry (pyMS) and vibrational spectroscopic methods allow a more in-depth characterisation of enterococci. Many of the recently described enterococcal species exhibit deviations from hitherto so-called classical enterococci with regard to their phenotypical properties. Therefore, genotypic methods have to be used to clarify their possible assignment to the genus Enterococcus. In this review, special emphasis is given on recently developed polymerase chain reaction (PCR)-based typing methods such as random amplified polymorphic DNA (RAPD), amplified fragment length polymorphism (AFLP), specific and random amplification (SARA) and modifications of PCR-ribotyping as well as pulsed-field gel electrophoresis (PFGE) and partial sequence analysis. The use of PCR and probes for genus and species identification of enterococci is also considered like the application of sequence data of conserved DNA regions (e.g., ribosomal ribonucleic acid (rRNA) genes) in the case of species identification.     

The Effect of Sodium Chloride on Catechol Oxidase from Apples

Catechol oxidase from apple chloroplasts and browning of apple slices are strongly inhibited by the chloride anion. The inhibition is non-competitive and reversible. Inhibition is pH-dependent. being observed at pH 5.1 but not at pH 7.3. Activity could be extracted from the particles using CTAB. The extract's activity at the two pH could not be resolved into distinct fractions. The pH-dependence of inhibition is ascribed to a change in the tertiary structure of the enzyme.     

Fatty acid accumulation in the different fractions of the developing corn kernel

In the food industry, the use of the oil is determined by the composition of fatty acids, and this is highly dependent on its natural origin. The fatty acid composition of whole corn kernel was determined in three varieties of corn (Astro, GH2547, and Local). Linoleic acid was the predominant fatty acid in the oil of Astro and Local at all collection dates, whereas it was the major fatty acid in the oil of GH2547 only between 40 and 60 days after pollination (DAP). The fatty acid accumulation in the endosperm, pericarp and germ fractions of the corn kernel during maturation was determined. The accumulation pattern of oil content was different in these three kernel fractions. The highest levels of oil content in the endosperm (2.2%), germ (34.3%) and pericarp (10.8%) fractions were detected at 20, 40 and 30 (DAP), respectively. The fatty acid accumulation patterns were different amongst the analysed kernel parts, indicating a numerous differences between the three corn kernel parts. Throughout the sampling periods, the endosperm fraction was distinguished by the highest and the lowest levels of oleic and linoleic acids, respectively. At all stages of kernel development, the pericarp fraction had the highest levels of total polyunsaturated fatty acids, which has numerous healthy applications. These results may be useful in the understanding of the potential source of the beneficial unsaturated fatty acids amongst the different fractions of the corn kernel during maturation.     

Effects of alkaline and acid pretreatment on the physical properties and nanostructures of the gelatin from channel catfish skins

The objective of this study was to illustrate the correlation between the physical properties and nanostructure of gelatins made of channel catfish (Ictalurus punctatus) skins. The gelatin samples were first pretreated with sodium hydroxide, acetic acid, or water, and then extracted with hot water before the measurement. Physical properties including the yield of protein, viscosity and textural properties were determined on gelatins obtained with different pretreatment conditions. The acid pretreatment group showed the highest gel strength and protein yield, and a reasonable viscosity. The water pretreatment group showed the lowest values for all of the physical properties. Four samples including water, 0.1 M acid and 0.25 and 1.0 M alkaline-pretreated groups’ nanostructures were then studied using atomic force microscopy (AFM). The AFM images showed that the acid-pretreated gelatin was composed of sponge-like aggregates, while the others showed separated individual aggregates. Annular pores were only found in the alkaline pretreatment group. There was no significant correlation between the diameters of the spherical aggregates and the physical properties; however, the different AFM patterns may relate to the gelatin's physical properties.     

An evaluation of the effects of various parameter weights on typical meteorological years used for building energy simulation

In this paper, we evaluate the influence of different parameter weights in creating “typical year” weather data following the typical meteorological year (TMY) methodology, by studying two sets of 3600 alternate weather files created using different parameter weights for Beijing (China) and New York City (USA). A “typical year” weather file consists of twelve distinctive months, each considered typical for that month of the year. Such a typical month, named “typical meteorological month (TMM),” is commonly identified by using a certain combination of parameter weights, such as 4:4:4:12, for dry bulb temperature, dew point temperature, wind speed, and solar radiation as in the TMY weather files developed by US National Climate Data Center (NCDC), or 4:4:2:10 in the newer TMY2 and TMY3 weather files developed by National Renewable Energy Laboratory (NREL). In this study, we investigate the influence of varying the parameter weights on the TMMs and the resultant new TMY weather files (nTMY). We found that the distribution of new 3600 TMMs tend to cluster within one or a few years for each month, and that the probabilities are very high for significant overlap between the new TMMs and the original TMMs chosen using the TMY/TMY2 weighting. Compared to the TMM data in TMY, the deviations of air temperatures and solar radiation values of the new TMMs and nTMYs derived from the 20-year weather data are less than 10% for both Beijing and New York. This confirms that the creation of “typical year” weather data is not very sensitive to the weighting of the different weather parameters, and that most nTMYs created and evaluated in this study are empirically close to the TMY data intended for use of simulating building energy consumption.     

搅拌摩擦点焊

搅拌摩擦点焊(FSSw)是一种最近研究开发出来的新焊接技术.同目前的电阻点焊相比,该方法是具有节能、设备简单、焊点强度高、变形小、焊前表面清理简单,可以焊接厚度差别大的材料,特别适用于高强度铝合金的焊接.重点介绍该技术的基本原理、优缺点、焊接设备,对几种典型铝合金的焊接工艺参数、接头强度和组织等进行了比较详细的分析,从而对该技术有一个全面的了解.