Morphological and structural features of polyacrylonitrile fibres spun by the dry-wet method

Conclusions -- A technological regime for the preparation of polyacrylonitrile fibres from binary and ternary copolymers has been chosen; these differ from known specimens in having a more uniform cross-sectional structure and a smoother elementary filament surface.-- A considerable difference in crystalline structure of fibres from binary and ternary copolymers which have been spun into a dimethyl sulfoxide—water bath has been shown.-- Fibres from the binary or ternary copolymer which have been spun into a precipitation bath having a large dimethyl sulfoxide content in water are characterized by a lower degree of swelling.-- Shrinkage of fibres from the binary copolymer in the temperature range 200–220°C is twice as small as the shrinkage of fibres from the ternary copolymer.Deceased.VNIIPV. Translated from Khimicheskie Volokna, No. 3, pp. 19–22, May–June, 1991.     

Presence of genomes of phage PBV-1 in the mycelia of the fungus Penicillium brevi-compactum

Progressive systemic sclerosis may be associated with focal myocardial fibrosis. Electrocardiographic abnormalities including conduction block are common in progressive systemic sclerosis but whether they are due to direct destruction of the specialized conduction tissue of the heart is uncertain. The conduction systems of 35 patients with progressive systemic sclerosis were studied. Of these 35 patients, 17 (50 per cent) had myocardial fibrosis of the type seen in progressive systemic sclerosis. In 10 of the 17, it was severe. Sinus node fibrosis was present in 13 patients and was nearly as frequent in those with as in those without the progressive systemic sclerosis myocardial lesion. Overlying pericarditis may have contributed to the fibrotic changes within the sinoatrial nodes in seven of the 13 patients. The atrioventricular node and main His bundles were normal. However, fibrotic changes were found in the proximal bundle systems in six patients. In three of the six, severe myocardial progressive systemic sclerosis was present, two had focal fibrous atrophy of the left bundle, and one had complete interruption of the right bundle. In only the latter patient was this reflected in the electrocardiogram which showed a right bundle branch block. Three patients without progressive systemic sclerosis myocardial lesions also had fibrous atrophy of a portion of the proximal left bundle branch, and in one the electrocardiogram showed an isolated left anterior hemiblock. Thus, morphologic abnormalities within the conduction system in our patients are difficult to attribute to progressive systemic sclerosis per se. Furthermore, although conduction abnormalities were more frequent in patients with myocardial disease, specific conduction system disease was not the cause in most patients. As has been noted in ischemic heart disease, the conduction system appears to be relatively spared from the myocardial changes of progressive systemic sclerosis, and the high incidence of conduction disturbances in this condition may be a consequence, rather, of damage to working myocardium.     

The effect of Opisthorchis on the manifestations of herpesvirus type 2 in an experiment and their possible participation in the mechanism of the occurrence of primary liver cancer

In a 4 month study, a group of 16 patients with stable renal graft function receiving triple immunosuppressive therapy including cyclosporin A (Cy A) were investigated for the levels of calcium, magnesium and zinc in erythrocytes. The patients were randomized to be converted to the new microemulsion formulation (Sandimmun Neoral) in a 1:1 fashion (n = 8) or to continue with the classical formulation (Sandimmun) (n = 8). The concentrations of creatinine, phosphate, alkaline phosphatase activity, calcium, magnesium and zinc were measured twice a month in blood plasma. The concentration of calcium, magnesium and zinc in erythrocytes was also measured. The concentration of magnesium in blood plasma and erythrocytes during the study showed no deviation from normal values. The level of zinc in erythrocytes was almost twice as high as in normal healthy controls and was not dependent on Cy A formulation. Calcium content in erythrocytes of patients receiving Sandimmun was 27.6% higher than in healthy persons. Conversion of the patients to Sandimmun Neoral normalized the calcium concentration in erythrocytes and caused a transient increase of calcium levels in blood plasma.     

Effect of the nature of silicon oxide structures on the activity of an alumina-chromium catalyst in the reaction of iso-butane dehydrogenation

The formation of silicon oxide structures in the composition of an alumina-chromium catalyst for the dehydrogenation of iso-butane is studied by means of nitrogen adsorption, XRD analysis, solid-state ²⁹Si NMR spectroscopy, temperature-programmed desorption of ammonia, and UV-Vis and Raman spectroscopy. It is established that 0.5–1.2 wt % silicon was distributed on the catalyst surface in the form of Si(OSi)₄ structures. As the silicon content was increased to 2.2–3.6 wt %, Si(OSi)₃(O-) structural elements were present on the surface in addition to Si(OSi)₄. The formation of silicon oxide structures on the catalyst surface was responsible for an increase in the concentration of Cr(III) ions and a decrease in the surface acidity; the activity and selectivity of the catalysts in the reaction of iso-butane dehydrogenation increased.