Quantitative study of the resolving power of arrays of carbon black-polymer composites in various vapor-sensing tasks

A statistical metric, based on the magnitude and standard deviations along linear projections of clustered array response data, was utilized to facilitate an evaluation of the performance of detector arrays in various vapor classification tasks. This approach allowed quantification of the ability of a 14-element array of carbon black-insulating polymer composite chemiresistors to distinguish between members of a set of 19 solvent vapors, some of which vary widely in chemical properties (e.g., methanol and benzene) and others of which are very similar (e.g., n-pentane and n-heptane). The data also facilitated evaluation of questions such as the optimal number of detectors required for a specific task, whether improved performance is obtained by increasing the number of detectors in a detector array, and how to assess statistically the diversity of a collection of detectors in order to understand more fully which properties are underrepresented in a particular set of array elements. In addition, the resolving power of arrays of carbon black-polymer composites was compared to the resolving power of specific collections of bulk conducting organic polymer or tin oxide detector arrays in a common set of vapor classification tasks.     

The Certification of the Identity of Individual Sterols in Three BCR Oil and Fat Reference Materials by GC-MS

The sterols of three Reference Materials: a vegetable oil (RM162: a mixture of Soya oil and Maize oil) and two animal fats (RM163: a blend of Pig and Beef fats and RM164: Milkfat) were identified by GC-MS in two experienced laboratories. The techniques used were practically the same nevertheless, Lab. 1 and 2 used respectively an HPLC and a classical TLC method to isolate the sterols from the unsaponifiable matter. Many minor components were detectable when the high efficient HPLC fractionation technique was used but the only molecules similarly identified by the two Labs were considered for the certification of sterol identities. In this article, we present the results of the certification study together with the interpretation of mass spectra.     

Formation of glucosyl-deoxyosones from Amadori compounds of maltose

Summary Amadori compounds obtained from maltose were heated witho-phenylenediamine. The main reaction products were found to be the quinoxalines5b,6b, and7a. From the structures of the quinoxalines, it can be deduced that the deoxyosones2b,3b, and4a are formed from maltose. From the determination of some transformation products, it was found that the degradation of glucose in the presence of propylamine does not proceed exclusively with Amadori compound1a as an intermediate. On heating Amadori compound1d, the furane derivative11a was detected, confirming the formation of4a.

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Bildung von Glucosyl-Desoxyosonen aus Amadoriverbindungen der Maltose

Zusammenfassung Amadori-Verbindungen aus Maltose wurden mito-Phenylendiamin umgesetzt. Als wesentliche Reaktionsprodukte konnten die Chinoxaline5b,6b und7a isoliert und identifiziert werden. Die Versuche zeigten, daß bei der Maillard-Reaktion aus Maltose die Substanzen2b,3b und4a als Zwischen-stufen gebildet werden. Durch die Bestimmung von Folgeprodukten ließ sich zeigen, daß der Abbau von Glucose in Gegenwart von Propylamin nicht ausschließlich über das Amadoriprodukt1a erfolgt. Erhitzen der Aminoketose1d führte u. a. zur Bildung des Furanderivates11a, was die Bildung von4a bestätigt.

     

STRUCTURAL STUDIES OF SHORT PATH DISTILLATES AND SUPERCRITICAL FLUID EXTRACT OF PETROLEUM SHORT RESIDUE BY NMR SPECTROSCOPY

Four short-path distillates obtained at different evaporator temperatures (240, 270, 300, and 330° C) and a supercritical fluid extract (with CO₂ as solvent) of petroleum short residue (North Gujarat Mix) have been separated into saturates and aromatics. Each fraction of all the said samples has been studied by ¹H- and ¹³C-NMR spectrometry and the distributions of various types of hydrogens and carbons are reported. Several reliable average structural parameters have been computed and their relative variation is discussed.     

Analysis of boundary layer control by heat transfer strips using an asymptotic approach to the PSE

The effect of heating strips on the stability of boundary layer flow over a flat plate is investigated. Heating strips alter the flow stability through the temperature dependence of the fluid properties. A stability study is carried out using the parabolized stability equations (PSE) that calculates the effects of temperature dependent fluid properties in terms of asymptotic expansions based on the total heat input. The leading order influence is obtained as a general result and, for the particular Prandtl number taken, is independent of any special set of property laws. In a fluid for which the intrinsic viscosity increases with temperature and the density decreases with temperature (such as air) the results show that the optimal location for a heating strip to stabilise the flow is upstream of the neutral point. The optimal location moves further upstream as the total heat input level is increased. For a given heat input widening the heating strip further stabilises the flow. Finally, the potential of the asymptotic method as a tool for further analysis of the flow is discussed.     

THE USE OF FACTOR ANALYSIS IN SOURCE DETERMINATION OF PARTICULATE EMISSIONS

The development of multivariate statistical approaches to receptor models have focussed on factor analysis. Target transformation factor analysis (TTFA) offers the possibility of determining the number of sources and their elemental composition as well as their mass contributions. In this current work, a new approach is presented for calculating the mass contributions of each source to each sample. In addition an approach to estimating the uncertainties in the analysis is introduced. The method is applied to a subset of the Regional Air Pollution Study (RAPS) particulate composition data set for site 203 in July and August 1976. The data is divided into subsets covering the daylight (6 AM to 6 PM) or night (6 PM to 6 AM) samples. Similar source profiles are obtained for these subsets.     

Bildung eines Pyridon-Derivates aus Maltose und Lactose

European Food Research and Technology - Maltose und Lactose reagieren mit Methylammoniumacetat in heißer, wäßriger Lösung rasch unter Bräunung. Aus dem Gemisch der...     

Role of muscle pyruvate dehydrogenase histidine residues in thiamine pyrophosphate binding

The interaction of diethylpyrocarbonate (DEP) with the pyruvate dehydrogenase component (PDH) isolated from the pyruvate dehydrogenase complex (EC 1.2.4.1) results in a modification of 3-5 histidine residues per mole of enzyme, which simultaneously decreases the enzyme activity. After PDH inhibilion by DEP in the presence of dithiothreitol almost complete reactivation (94%) under the effect of neutral hydroxylamine is observed. In the absence of SH-groups protection incomplete reactivation by hydroxylamine (79%) is found. In the latter case titration with 5,5-dithio--bis-(2-nitrobenzoic acid) in 8 M urea showed that the DEP-modified protein contains less quantity of SH groups (by 4-8) as compared to the native enzyme. It is assumed that the DEP-modified SH-groups are not responsible for the enzyme activity. The differential spectrum of the modified and native PDH showed no changes within the range of 260-300 nm. TPP in combination with Mg2+ (10(-3) M) protectes PDH from being inactivated by DEP. TPP (10(-2) M) reactivates PDH by 70% after its complete inhibition by DEP. Similar protective action is manifested by ATP, ADP and inorganic pyrophosphate in the presence of Mg2+. A kinetic study showed a competitive type of PDH inhibition by DEP with respect to TPP. it is concluded that the histidine residues of PDH are involved in TPP binding.