Alkylthio-substituierte Bis(benzol-1,2-dithiolato)zinkate,Benzol-1,2-dithiole und -1,2-dithiolate – Edukte für Dibenzo[c,g](1,2,5,6)tetrathiocine und Benzo[c](1,2,3)-trithiole; Untersuchungen zu Benzodithieten und ortho-Dithiobenzochinonen

Alkylthiosubstituted Bis(benzene-1,2-dithiolato)zincates, Benzene-1,2-dithioles, and -1,2-dithiolates – Educts for Dibenzo[c,g](1,2,5,6)tetrathiocins, and Benzo[c](1,2,3)trithioles; Investigations on Benzodithietes and ortho-Dithiobenzochinones Using benzenehexathiolate 1 it is possible to synthesize alkylthio-substituted benzo-1,3-dithiole-2-thiones 2 , or -ones 3 and benzo-di(1,3-dithiole-2-thiones) 4 , or -ones 5 , resp., which were cleaved under basic conditions. The generated benzene-1,2-dithiolates 7 were isolated as benzene-dithiolato zincates 8 , benzene-1,2-dithioles 11 , and benzene-1-thiole-2-thiolates 10 . Dibenzo[c,g](1,2,5,6)-tetrathiocins 9 were synthesized by oxidation of 7 or 8 in good yields. For the per(methylthio)-substituted tetrathiocin 9a the twist conformation was proved by x-ray structure analysis. The tetrathiocin 9a was probably formed via the orthodithiobenzoquinone 13a . Photolysis of 3a at room temperature in solution led to 9a and tetrakis(methylthio)benzo[c] (1,2,3)trithiole 12a as the main product, which was also formed by irradiation of 9a . The trithioles 12 were formed from 8 by reaction with sulfur dichloride. 12a was investigated by x-ray structure analysis. ortho-Dithiobenzoquinone 13c can be claimed as an intermediate upon irradiation of benzo-1,3-dithiol-2-one 3c in an argon matrix at 10 K. Depending on the wavelength the equilibrium lies either on the side of dithiobenzoquinone 13c or benzodithiete 14c . The same is true for system 15/16 , which can be reached by flash vacuum pyrolysis of 3c .     

Automatisierte enzymatische Bestimmung von Glucose,Maltose und Stärke auf Mikrotiterplatten

Automated Enzymatic Determination of Glucose, Maltose and Starch on Microtiter Plates. An automated enzymatic method for the determination of sugars and starch is described. The elimination of inherent methodical errors in the optical measurement of microtiter plates and the evalution of 96 raw data is done with the “LBR1993” software. Analysis is based on a 10min hydrolysis by glucoamylase at room temperature and determination of glucose with the GOD-PAP-method. A recovery of greater 99% for maize and potato starch is possible if the starch is transformed at 100°C by α-amylase to α-dextrins and converted in a second step with 8.88 g glucoamylase/g substrate to glucose. Solubilization of potato starch in 1 N sodium hydroxide at room temperature gives a recovery of 93%. Heating (60°C) in 0.5 N sodium hydroxide (AFNOR-method) is not suitable for sugar analysis and certain kinds of starch.     

Wear characteristics of some internally lubricated and reinforced engineering polymer composites

An interesting characteristic of abrasion is the dependence of the wear rate on the particle size of the abrasive grits used to lubricate the abrasive papers. Three types of polymers, PTFE, PA, PI, several of their composites, and three metals were selected for studying the effect of particle size on wear rate. The pins were abraded against Sic abrasive papers of various mesh sizes under constant loading in multi-pass conditions. For some of the polymers and their composites (PA and PEI) the size effect on wear rate was similar to that for the metals. Beyond a critical particle size, no increase in wear was found with increasing particle size. On the other hand, PTFE, PI, and their composites showed the opposite effect. SEM and EDAX were used to investigate the related mechanisms.     

Spektroskopische Untersuchungen an organischen Carbonylverbindungen. VI. NMR-Studien an substituierten β-Diketonen und ihren vinylogen Derivaten

Spectroscopic Investigations on Organic Carbonyl Compounds. VI. N.M.R.-Studies on Substituted β;-Diketones and their Vinyloge Derivatives . ¹³C- and ¹H-n.m.r.-data of substituted β-diketones and their vinyloge derivatives are presented. Most of the compounds exist chiefly in the enol-form. Only in the case of 4-dimethyl-aminodibenzoylmethane a keto-enol-equilibrium is registered. The influence of the substituent A and the chainlength on the position of the enol proton is discussed.     

Ein Beitrag zur Biosynthese amylosereicher Erbsenstärken

Contribution to the Biosynthesis of High-amylose Pea Starches Biosynthesis of starch is a complex process but few details are still unknown. This paper describes an investigation upon pea starch biosynthesis. Peas as a source of starch offer two qualities, a pea starch with 40% amylose content (smooth pea starch) and a pea starch with more than 60% amylose content (wrinkled pea starch). Samples for analysis were taken during growth. According to the quantitative determination of starch and amylose the accuracy of amylose detection was tested. Furthermore a qualitative analysis was carried out by molecular weight estimation of the starch. Both kinds of peas showed a high amylose synthesis during the last few days of growth, whereas amylopectin synthesis was highly in earlier stages. Wrinkled peas have shown only little synthesis activity of amylopectin during maturity. Therefore the amylose content of these peas was higher, instead of equal amylose synthesis quotas of both smooth and wrinkled peas.     

CORRECT MACROMODELLING OF THE COMMON MODE AND POWER SUPPLY REJECTIONS OF OPERATIONAL AMPLIFIERS

The relationship between common mode rejection and positive and negative power supply rejections of operational amplifiers is derived and compared with symmetrical power supply rejection. The results are used to develop a macromodel which provides a correct representation of the terminal voltages at the op amp pins. The performance of the new macromodel is illustrated comparing simulation results with those of the device level model for the standard integrated circuit op amp uA741.