Academic literature on the topic 'Filtrage PHD'

Activated manganese dioxide (MnO2) reliably oxidizes acetylenic, allylic, and benzylic alcohols to aldehydes and ketones. Saturated primary and secondary alcohols are also oxidized, albeit more slowly. The two main concerns are the activity of the manganese dioxide and the slow filtration of salts after the reaction. Activated MnO2 is available commercially or may be prepared. To a solution of 15.3 g (37.5 mmol) of the alcohol in 150 mL of hexanes was added 60 g of activated MnO2. The reaction mixture was stirred at 22 °C overnight and filtered, and the solid residue was washed with 30% EtOAc in hexanes solution. The combined filtrates were dried (Na2SO4) and concentrated in vacuo. The residue was purified by chromatography on SiO2 (EtOAc:hexanes, 1:10) to give 13.7 g (90%) of the ketone as a colorless oil. Reference: Wipf, P.; Xu, W. J. Org. Chem. 1996, 61, 6556–6562. Chromium-based oxidations are reliable and well established, but the toxicity associated with chromium salts have meant that they are generally considered the second choice. For a review of chromium–amine complex oxidations, see Luzzio, F. A. Org. React. 1998, 53, 1-221. To a mixture of pyridinium chlorochromate (PCC 339 mg, 1.57 mmol), ammonium acetate (215 mg, 2.62 mmol), and 4 Å molecular sieves (610 mg) in CH2Cl2 (33 mL) was added a solution of the alcohol (208 mg, 1.05 mmol) in CH2Cl2 (14 mL) under argon at 0 °C over a period of 10 min. After the mixture had been stirred at room temperature for 3 h, diethyl ether (200 mL) was added and the mixture was filtered through a short pad of Florisil. The filtrate was washed successively with water (100 mL) and brine (100 mL), dried with Na2SO4, and concentrated. The residue was purified by chromatography on silica gel (hexane 70%, Et2O 30%) followed by distillation to give the aldehyde as a colorless oil (132 mg, 63%).

A big affection of the rock environment and groundwaters occured during the chemical mining of uranium in the years 1966 to 1996 in the neighbourhood of the town Straz pod Ralskem in the Czech Republic. It is necessary to clean the residual technological solutions (RTS) from the underground. The pH of the solutions in some places is still less than 2 and the concentration of sulphates reachs up to 65 g/l. The remedial activities consist of pumping of the RTS from the ground and reprocessing of the RTS in the surface technologies. The implementation of the new neutralization technologies NDS ML

Este artigo trata do controle em cascata de sistemas lineares com atraso vari´avel. Esta abordagem ´e baseada na compensa¸c˜ao de atraso por meio do preditor de Smith filtrado (PSF) para mitigar uma parcela constante deste atraso e a parcela vari´avel ´e tratada pelo crit´erio de estabilidade simplificado baseado no teorema do ganho pequeno. O filtro de robustez presente no PSF ´e usado para recuperar a estabilidade afetada pela presen¸ca de incertezas de modelo epelo atraso vari´avel. Assume-se que a malha interna ´e regulada por um controlador Proporcional Integral Derivativo (PID) local, ao

Anticoagulants usually have no antiplatelet effect and platelet function inhibitors do not interact with the coagulation factors. Since thrombin has a decisive role in thrombus formation (growth and stabilization), inhibitors of the effect of thrombin on platelets may be of special importance in developing a novel type of anticoagulant with antiplatelet properties.D-Phe-Pro-Arg-H /I/ designed and synthetized in our Institute was found to be a highly specific,reversible non-competitive inhibitorgOf thrombin,a specific platelet agonist. (K.= 1x10-8 M). /I/ was administered parenterally and orall

A new peptide thrombin inhibitor was found in the Streptomyces griseus strain 254 isolated from a soil sample from Tongan, Fujian province, China, the inhibitor being a secondary metabolic product. The production of the inhibitor reached a maximum after 3 days culture of bacteria at 28°C in a rotary shaker. The inhibitor excreted in the culture filtrate was purified by absorption on macroporous resin, followed by ion exchange chromatography on DEAE-52, CM-32 cellulose, affinity chromatography on the immobilized thrombin and high performance liquid chromatography. The amino acid composition of