The analysis of alkyl-capped alcohol ethoxylates and alcohol ethoxycarboxylates from alcohol ethoxylates by atmospheric pressure chemical ionization mass spectrometry

Alcohol ethoxylates (AEs) are nonionic surfactants. They are industrially important compounds that have historically been difficult to analyze, with the best results to date achieved through derivatization (e.g., silylation) followed by analysis by gas chromatography/mass spectrometry (GC/MS). Recently, mass spectrometric techniques such as field desorption (FD), time-of-flight secondary ion mass spectrometry (TOF-SIMS), fast atom bombardment (FAB), electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) have been employed to analyze surfynol(R) 4xx. In an effort to produce low-cost alkyl-capped AEs and anionic detergents from AEs, a fast and reliable measure of the product yields and conversions from AEs is required in research. We found that the product yields and conversions from reactions of AEs, obtained by the employment of atmospheric pressure chemical ionization (APCI), were in good agreement with those obtained from proton nuclear magnetic resonance spectroscopy ((1)H-NMR). Therefore, APCI can be used as a validated tool for studying AE reactions. Mixtures that contain either silylated or unsilylated ethoxylates and/or carboxylates yield the same APCI mass spectra. Copyright -Copyright 1999 John Wiley & Sons, Ltd.     

Endocellulase and exocellulase activities of two Streptomyces strains isolated from a forest soil

Two Streptomyces strains, M7a and M23, from a Brazilian forest soil were evaluated for the cellulase production of their superna tants after growth in a microcrystalline cellulose medium, using carboxy methylcellulose and filter paper as substrates at different temperatures and pH values. Endoglucanase and exoglucanase activities were compared to a commercial Trichoderma reesei cellulase using fluorogenic conjugated substrates Similar specific activities were observed for the enzyme preparations of strain M23 and T. reesei. For M7a the activities were about seven times higher than those obtained for T. reesei. Extracellular or cell-associated cellobiase activities were not detected in both strains.

     

Apoptosis mediated by caspase-3 and p53-dependent anticancer effects of 159Gd-DTPA-BMA complex

In this work the apoptosis mediated by caspase-3 and p53-dependent anticancer effects of ¹⁵⁹Gd-DTPA-BMA metal complex were evaluated against RT2 glioblastoma cells. The results showed that the mechanism of cell death involves apoptosis by caspase-3 activation. Furthermore, the involvement of p53 protein triggered by ¹⁵⁹Gd-DTPA-BMA in these cells was verified preliminarily. Considering these finding, the radioactive complex can be considered as potential therapeutic alternative agent against cancer.     

On Galois cohomology of semisimple groups over local and global fields of positive characteristic

We treat a case that was omitted from consideration in our article [2] in Math Zeit, 2007.     

A general mathematical model for the collision between a free-fall hammer of a pile-driver and an elastic pile: Continuous dependence and low-frequency asymptotic expansion

The main goal of this paper is to study with continuous dependence and a low-frequency asymptotic expansion of a unique weak solution to an initial-boundary value problem. This problem is arisen from a general mathematical model for the collision between the free-fall hammer of a pile-driver and an elastic pile whose ends are furnished with a bearing.     

An original ultrasonic reaction with dual coaxial frequencies for biomass processing

An advanced dual frequency ultrasonic coaxial reactor enabling simultaneously low and high frequencies irradiating in the same direction was developed to focus both mechanical and chemical effects on a concentrated area. The prototype was straightforward employed for the conversion of a starch-based industrial waste into sugars.     

Electroactive self-assembled monolayers: Laviron's interaction model extended to non-random distribution of redox centers

The Laviron's interaction model, dedicated to randomly distributed electroactive adsorbed species, was extended to a non-random distribution in order to extract the current–voltage characteristics from any surface distribution of electroactive centers on self-assembled monolayer (SAM). Confronted to electrochemical behaviour of nitroxyl radical SAMs, the agreement observed between theory and experiments provides evidence of a distribution independence of the interaction parameters.