Fractional composition of partly hydrolysed polyvinyl acetate and its compatibility with hydroxypropyl methylcellulose in aqueous solutions

Fractionation of partly hydrolysed polyvinyl acetate (PVA) was performed by warming of its aqueous solutions. The following properties of the obtained fractions were determined: viscosity, molecular weight and molecular weight distribution, surface tension, and absorbance in the IR range. The blockiness of the polymer molecules, characterized by their behaviour towards iodine-containing systems such as I₂,-H₃BO₃ and I₂,-KI, was estimated. Fractionation of the aqueous solutions of PVA by warming is based mainly on the different internal molecular structure of the separated products, i.e. on the length of the vinyl acetate blocks in the PVA molecules and, to a lesser extent, on the degree of hydrolysis and the degree of polymerization. The more blocklike are the PVA molecules, the less compatible are the polymers in the PVA-hydroxypropyl methylcellulose (HPMC)-water system. At phase separation in this sytem the PVA molecules which are not compatible with HPMC are, in the first place, those of the highest blockiness.     

A unified formulation for Chebyshev and Legendre superdirective endfire array design

Contents A unified formulation for superdirective end-fire arrays by using Chebyshev and Legendre Polynomials and their maximum directivities as well as the corresponding efficiency index and theQ factor are found. Several examples show the simplicity of the formulation.

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Eine einheitliche Formulierung zum Design von Supergain-Längsstrahlern mit Tschebyscheff- und Legendre-Polynomen

Übersicht Es wird eine einheitliche Formulierung für Supergain-Längsstrahler mit Tschebyscheff- und Legendre-Polynomen vorgestellt. Die Strahlergruppen werden für unterschiedliche Kombinationen dieser Polynome angegeben, ebenso ihre optimalen Richtgewinne wie auch der dazugehörige Strahlungs- Wirkungsgrad in der Hauptrichtung und der GütefaktorQ. Einige Beispiele belegen die Einfachheit der Formulierung.

     

Determination of the intensity of emission of a radioactive contaminant from the ventilation pipes of a nuclear power plant

All-Union Scientific-Research Institute of Nuclear Power Plants NIIP. Translated from Atomnaya énergiya, Vol. 77, No. 5, pp. 392–402, November, 1994.     

Thrombolysis for evolving myocardial infarction in a rural primary care clinic

Early thrombolytic therapy gives maximum benefit in acute myocardial infarction. In remote rural areas with no mobile intensive care service there is a significant delay between onset of symptoms and administration of thrombolytic therapy which has a critical impact on revascularization. Thrombolytic therapy with streptokinase 1,500,000 U was given in a primary care rural clinic to 2 patients with evolving myocardial infarction 45-50 minutes from onset of symptoms. In both patients, who were transported to hospital after the therapy, there were clinical signs of reperfusion. There were no complications during treatment or transportation. We conclude that thrombolytic therapy given for evolving myocardial infarction in a rural primary care clinic is possible and safe.     

Three-week hepatitis B vaccination provides protective immunity

To determine whether a 3-week hepatitis B (HB) vaccination could achieve protective immunity, 89 healthy non-immunized young adults received three doses of 20 micrograms each of HBs antigen (GenHevac B, Pasteur) and were randomly assigned to schedule A (n = 44): two doses at day 0, one dose at day 21; or schedule B (n = 45): one dose at days 0, 10 and 21. Seroprotection rates (anti-HBs > or = 10 mIU ml-1) for groups A and B respectively were: 23 and 40% at day 21; and 77 and 91% at day 82 (not significant). Anti-HBs geometric mean titres were higher in group B than in group A (p < 0.05) at days 21 (6.4 versus 3.8) and 82 (77.6 versus 33.5). One year after primary vaccination, the seroprotection rate remained as high as 90% in the vaccinees of group B; after boosting all vaccinees had protective levels of anti-HBs antibodies. Thus 3-week HB vaccination with GenHevac B allowed early and durable protective immunity.     

The Effects of Fatty Acids and Their Derivatives on the Intestinal Absorption of insulin in Rat

Insulin solution (25 U/ml/kg, pH 8.0) was administered with 50 mM of various C8-Cl8 fatty acid and derivative absorption enhancers to the duodenum, colon and rectum of fasted normal rats under sodium pentobarbital anesthesia. Solutions were administered directly into ligated or sealed intestinal segments. Blood was sampled periodically from the jugular vein and blood glucose levels determined. The maximum decrease in blood glucose level and area under the depression curve were used to estimate bioavailability. Enhancing effects rectally were further investigated in streptozotocin-induced diabetic rats in both the fasted and non-fasted states. Blood glucose levels and serum insulin concentrations were determined.     

Analysis of secretion and expression of platelet-derived growth factor in cultured endothelial cells from stroke-prone spontaneously hypertensive rat

1. We characterized the endothelial cell-derived growth factors of SHRSP and Wistar Kyoto rats (WKY), respectively and found that platelet-derived growth factor (PDGF)-B chain related growth factor constituted a major portion of the mitogenic activity of the conditioned media of endothelial cells from both animals. There were no remarkable qualitative differences between the endothelial cell-derived growth factors of SHRSP and WKY. 2. Northern analysis revealed that the expression of PDGF-B chain was 2-4-fold enhanced in cultured aortic endothelial cells of SHRSP. This enhanced expression of PDGF-B chain, which may be induced under chronic hypertensive conditions, is suggested to contribute to the increase in endothelial cell-derived growth factors reported in this animal.