Sur la reactivite electrochimique et catalytique des bioxydes de manganese: Differenciation des groupes oh et des molecules d'eau de constitution

The importance of OH groups in the electrochemical reactivity of manganese dioxides is well known. By a kinetic analysis of thermogravimetric curves of decomposition of γ-manganese dioxides, it is possible to evaluate separately the number of OH groups and the number of water molecules in such dioxides. The number of OH groups so evaluated is the total.

It is also possible to determine the number of superficial OH groups, by a chemical method. For two specimens, 1·8 and 3·9% of the OH groups were superficial.

Zusammenfassung

Die Wichtigkeit und die Rolle der OH-Gruppen in der elektrochemischen Reaktivität der Mangandioxide ist bekannt. Die kinetische Untersuchung der thermogravimetrischen Spaltungskurven der γ-Mangandioxide erlaubt in manchen Fällen, die Anzahl OH-Gruppen und die Anzahl H₂O-Moleküle, die solche Dioxide enthalten, zu berechnen. Die so berechnete Zahl der OH-Gruppen stellt die an der Oberfläche liegenden und die in das Gitter eingebauten OH-Gruppen dar. Die an der Oberfläche liegenden OH-Gruppen können durch ein chemisches Verfahren bestimmt werden. Es wird so festgestellt, dass sich bei zwei von den hier untersuchten Proben 1,8% (Probe A5) und 3,9% (Probe E25) der OH-Gruppen an der Oberfläche befinden.     

Methods of estimating the water activity of supersaturated aqueous solutions

Empirical and semi-empirical methods of estimating the water activity of supersaturated aqueous solutions at up to twice the saturation molality are compared for CaCl₂ and Na₂SO₄ at °0C and K₂SO₄, KH₂PO₄, NaCl, KCl, RbCl, CsCl, KNO₃ and mannitol at 25°. An empirical method, applicable to both electrolytes and non-electrolytes, is described.     

A Radioactive Tracer Method for Measuring the Relative Surface Areas of Small Samples

A new method for measuring the relative surface area of small samples is described. The method is based on liquid-sorption theory and uses stearic acid tagged with ¹⁴C. Relative surface area data on alumina samples deposited under various conditions by the anodic spark process are reported. The method was validated successfully using BET data taken on alumina samples .     

20%螨速净乳油防治柑桔红蜘蛛应用研究

经小区试验和大田示范，２０％螨速净（三氯杀螨醇，哒螨酮）乳油，对柑桔产虫活性和持铲时间与单剂哒螨相仿，而农业应用成本相应降低２０％。     

Prenylated Flavonoids from Cudrania tricuspidata Suppress Lipopolysaccharide-Induced Neuroinflammatory Activities in BV2 Microglial Cells

In Korea and China, Cudrania tricuspidata Bureau (Moraceae) is an important traditional medicinal plant used to treat lumbago, hemoptysis, and contusions. The C. tricuspidata methanol extract suppressed both production of NO and PGE₂ in BV2 microglial cells. Cudraflavanone D (1), isolated from this extract, remarkably suppressed the protein expression of inducible NO synthase and cyclooxygenase-2, and decreased the levels of NO and PGE₂ in BV2 microglial cells exposed to lipopolysaccharide. Cudraflavanone D (1) also decreased IL-6, TNF-α, IL-12, and IL-1β production, blocked nuclear translocation of NF-κB heterodimers (p50 and p65) by interrupting the degradation and phosphorylation of inhibitor of IκB-α, and inhibited NF-κB binding. In addition, cudraflavanone D (1) suppressed the phosphorylation of c-Jun N-terminal kinase (JNK) and p38 MAPK pathways. This study indicated that cudraflavanone D (1) can be a potential drug candidate for the cure of neuroinflammation.     

Basic studies of smoke reduction in rigid poly(vinylchloride)

A review of recent results in the literature and from our laboratory lead to drive a general picture of the combustion or rigid PVC as well as to the mechanism by which the most powerful additive can reduce the production of smoke. It is shown that, in smoldering condition the black smoke comes chiefly from direct volatilization of heavy tar molecules from the decomposing residue. The additives change the degradation process of the PVC by catalysis of the intermolecular crosslinking reactions, which compete with the intramolecular reactions leading to formation of benzene. Whatever their initial nature, they are at least partly transformed into chlorides and then into oxides during the combustion process. The oxide of Cu, Fe and also Zn are catalysts of the oxidation of the char residue, which may be partially inhibited by phosphorous compounds. The catalytic effects seem less pronounced in flaming conditions, which cause the productions of soots from the initial tars.