Scanning electron microscopy investigations on bis(2-ethylhexyl)phthalate treated Mycobacterium cells

Comparative investigation of steroid transforming activity and ultrastructural changes of bis(2-ethylhexyl)phthalate (BEHP, phthalate) treated Mycobacterium sp. NRRL B-3805 cells was carried out. Transformation of beta-sitosterol into androstenedione (AD) and androstadienedione (ADD) was performed in phthalate medium by resting cells preincubated in the organic solvent for a period from 3 to 24 h. It was observed that a preincubation greater than 12 h leads to the development of dense formations on the cells surface, reduction in the cell turgor, disruption in the cell walls, and formation of zones with reduced electron density. The preincubation for 24 h causes deeper changes in the cell ultrastructure but the treated cells retain their steroid transforming activity, allowing up to 80% of the substrate to be converted into AD and ADD. A preincubation of the resting Mycobacterium cells in BEHP for 6 h might be recommended as it leads to an achievement of stoichiometrical transformation of the substrate into AD and ADD and slightly higher initial rate of the reaction performed.     

Bright fluorescent dsDNA probes: novel polycationic asymmetric monomethine cyanine dyes based on thiazolopyridine‐quinolinium chromophore

Seven tri‐ and tetracationic monomeric and homodimeric monomethine cyanine dyes based on thiazolo[4,5‐b]pyridinium and quinolinium end groups were synthesised and characterised. The dyes were tested as fluorescent DNA intercalating probes to apply in DNA gel electrophoresis. The DNA samples stained with all dyes from the series demonstrated bright fluorescent signals. DNA fragments were successfully visualised under orange and green filters as well as under standard UV transillumination. Two of the studied dyes revealed higher sensitivity to DNA when compared with the commercial dimeric cyanine dye TOTO‐1. Their sensitivity reached that of the commercial dimeric cyanine dye YOYO‐1, but the emission was shifted to longer wavelengths. These qualities make the dyes suitable to apply in a wide range of medical and scientific analytical methods.     

Quantum-mechanics of pyrite flotation

The authors have carried out molecular modeling of clusters of simple structure and ring structure pyrite. It is suggested to analyze bonding of a collecting agent and cluster atoms using the collector capacity forecasting index. It is shown that butyl dixanthate more vigorously connects to cluster atoms than thionocarbamates, e.g., Z 200 and IETNC. Analysis of the charge transfer during interaction of pyrite with the listed collecting agents shows that in monodentate bonding the charge is transferred from the mineral to the collector sulfur atoms and in bidentate bonding the classical transfer of the charge from the collector donor to the mineral acceptor is observed. It is supposed that ferrum xanthate decompounding in an acid medium results in inception of dixanthates that govern pyrite flotation. Pyrite oxidation and elemental sulfur formation also favor pyrite flotation but complicate pyrite depression in an alkaline medium.     

Effect of catalysis and inlet gas on coal gasification

An investigation was carried out to develop a high-speed and low-temperature coal gasification process: the effect of alkali carbonate, Fe and other catalysts was studied.     

Chromatographic determination of the oligomer content in aqueous solutions in caprolactam regeneration

Conclusions -- The qualitative and quantitative analysis for the content of oligomers in aqueous solutions in caprolactam regeneration may be carried out by the liquid-chromatography method after selective extraction of the monomer.-- The decisive role of compactness and of contact surface of the oligomer molecules in hydrophobic-dispersion interaction with chemically modified silica gel and in effect on retention time in the chromatographic system has been demonstrated.-- The proposed procedure is characterized by accuracy and reproducibility of the results and can be recommended for scientific and also for manufacturing purposes.Institute of Pneumatic Tires and Polyamide Fibres (Vidin, Bulgaria). Translated from Khimicheskie Volokna, No. 5, pp. 57–59, September–October, 1992.     

Complexity analysis of sleep and alterations with insomnia based on non-invasive techniques

For the first time, fractal analysis techniques are implemented to study the correlations present in sleep actigraphy for individuals suffering from acute insomnia with comparisons made against healthy subjects. Analysis was carried out for 21 healthy individuals with no diagnosed sleep disorders and 26 subjects diagnosed with acute insomnia during night-time hours. Detrended fluctuation analysis was applied in order to look for 1/f-fluctuations indicative of high complexity. The aim is to investigate whether complexity analysis can differentiate between people who sleep normally and people who suffer from acute insomnia. We hypothesize that the complexity will be higher in subjects who suffer from acute insomnia owing to increased night-time arousals. This hypothesis, although contrary to much of the literature surrounding complexity in physiology, was found to be correct—for our study. The complexity results for nearly all of the subjects fell within a 1/f-range, indicating the presence of underlying control mechanisms. The subjects with acute insomnia displayed significantly higher correlations, confirmed by significance testing—possibly a result of too much activity in the underlying regulatory systems. Moreover, we found a linear relationship between complexity and variability, both of which increased with the onset of insomnia. Complexity analysis is very promising and could prove to be a useful non-invasive identifier for people who suffer from sleep disorders such as insomnia.     

Modification of anthracite sorption properties by thermooxidation with air Physico-chemical characteristics of the thermooxidized anthracite

The pore structure, specific electrical resistance, content of oxyge n-containing functional groups and ion -exchange ability ofspecimens ofoxidized carbon material, obtained through thermooxidative treatment of anthracite, are investigated, and an X -ray structural analysis is performed . Th e results show that by employing a simple method (thermooxidatioe treatment with air at 450°C) and using a cheap raw material it is possible to obtain oxidized carbon products with high ion-exchange abilities and low electrical resistance.     

Picomolar assay of native proteins by capillary electrophoresis precolumn labeling, submicellar separation, and laser-induced fluorescence detection

We report a method for the assay of proteins at concentrations lower than 10(-)(10) M with as little as 200 amol of protein. High sensitivity is accomplished by derivatizing the ε-amino group of the protein's lysine residues with the fluorogenic dye 5-furoylquinoline-3-carboxaldehyde and use of a sheath flow cuvette fluorescence detector. Most proteins have a large number of lysine residues; therefore, a large number of fluorescent molecules can be attached to each protein molecule. In general, precolumn labeling improves sensitivity but degrades resolution due to the inhomogeneity of the reaction products from multiple labeling. However, we demonstrate that, through careful manipulation of the separation and reaction conditions, high sensitivity can be obtained without excessive loss in separation efficiency. Over 190?000 theoretical plates are obtained for fluorescently labeled ovalbumin.     

Wet Etching Study of La0.67(Sr0.5Ca0.5)0.33MnO3 Films on Silicon Substrates

Wet etching of colossal magnetoresistive (CMR) perovskite La_0.67(Sr_0.5 Ca_0.5)_0.33MnO₃ (LSCMO) films on Bi₄Ti₃O₁₂/CeO₂/yttrium-stabilized zirconia (YSZ)-buffered Si substrates was investigated using potassium hydroxide (KOH) and buffered hydrofluoric acid (BHF) solutions. X-ray diffraction (XRD) and scanning spreading resistance microscopy (SSRM) measurements revealed that the morphological roughness of the LSCMO films increases, while the electrical resistance roughness decreases, with increasing KOH etching time. The LSCMO films are highly chemically resistant to KOH solution; however, in the case of BHF etching, an etch rate of 22 nm/min was obtained with high selectivity over a photoresist mask.