Chemiluminescence from osmium(II) complexes with phenanthroline, diphosphine and diarsine ligands

The reaction of various [Os(L)(2)(L')](2+) complexes (where L and L' are phenanthroline, diphosphine or diarsine ligands) and organic reducing agents after chemical or electrochemical oxidation of the reactants produces an emission of light corresponding to MLCT transitions. In certain instances, the emission was greater than that of [Ru(bipy)(3)](2+), but the relative signals were dependent on many factors, including reagent concentration, mode of oxidation, reducing agent and the sensitivity of the photodetector over the wavelength range.     

High-performance liquid chromatographic resolution of p-nitrobenzyloxyamine derivatives of brain gangliosides

A new quantitative procedure for the high-performance liquid chromatographic (HPLC) resolution of human brain gangliosides employing reversed-phase chromatography is described. To provide a derivative which can be determined by UV absorption techniques, p-nitrobenzyloxyamine was coupled to the gangliosides. Derivatization involves ozonation and cleavage of the ceramide double bond followed by oxime formation to the nascent aldehyde. Individual gangliosides, as they were resolved by HPLC, were collected. These fractions were then identified by thin-layer chromatography (TLC) and by gas chromatography of their monosaccharides. Quantitative results were obtained along with a marked increase in sensitivity over conventional resorcinol-hydrochloric acid quantitation of TLC-resolved gangliosides.     

Basic hydrolysis of glyceryl nitrate esters. I. 1-glyceryl and 2-glyceryl nitrate esters

Kinetics of the basic hydrolysis of 1-glyceryl mononitrate (1-MNG) and 2-glyceryl mononitrate (2-MNG) were investigated in CO₂-free aqueous calcium hydroxide solutions. The hydrolysis reactions were carried out in a temperature-controlled reactor vessel with provision for continuous N₂ sparging of the reaction mixture. Both glyceryl nitrate esters hydrolyzed via second-order reaction at 25°C. 2-MNG in calcium hydroxide solution isomerized to 1-MNG, which subsequently hydrolyzed to form NO. In strongly basic aqueous solutions of NaOH (30%), 2-MNG is converted to glycidol and NO.     

Fission following complete or incomplete fusion of 135 MeV16O and238U

From measurements of the laboratory angular distribution and the projected range distribution for each of 26 individual radioactive fission products from the interaction of 135 MeV¹⁶O on²³⁸U, we have determined for each product quantities including the average velocity,ν, of the parent fissioning system and the anisotropy,ω, of the fission angular distribution. We have interpreted the results in terms of two competing mechanisms: complete fusion and a process involving transfer of anα-particle from projectile to target followed by fission of²⁴²Pu. The values ofν lie betweenν _cn, the complete fusion value, and 0.3ν _cn, and can be taken as a measure of the relative importance of the two processes competing in populating each observed product. These two contributions to each measured product yield can then be separated, and understood using a simple model of the fission process. The data suggest that approximately 24% of the overall fission yield is due to incomplete fusion processes. The anisotropy,ω, is strongly correlated with the value ofν, indicating anisotropies of 1.4 and 2.8 for the two individual processes.     

Robert Adrian: American mathematician

Robert Adrain immigrated to the United States from Ireland in 1798, when he was about twenty-three years of age. He became a leader in the American mathematical community as a teacher, proposer and solver of problems, and as an editor of mathematical journals. He published two proofs of the exponential law of error independently of Gauss.     

Measuring accuracy in a post-enumeration survey

"The U.S. Bureau of the Census will use a post-enumeration survey to measure the coverage of the 1990 Decennial Census. The Census Bureau has developed and tested new procedures aimed at increasing the accuracy of the survey. This paper describes the new methods. It discusses the categories of error that occur in a post-enumeration survey and means of evaluation to determine that the results are accurate. The new methods and the evaluation of the methods are discussed in the context of a recent test post-enumeration survey."     

CsPb3Bi3Te8 and CsPb4Bi3Te9: low-dimensional compounds and the homologous series CsPbmBi3Te5 + m

Two new thermoelectric materials of quaternary bismuth telluride CsPb3Bi3Te8 and CsPb4Bi3Te9 are reported, which are members of a homologous series featuring anionic slabs [PbmBi3Te5 + m]- (m = 1-4) of monotonically increasing thickness.     

A database of lipid phase transition temperatures and enthalpy changes

The systematic study of the mesomorphic phase properties of synthetic and biologically derived lipids began some 30 years ago. In the past decade, interest in this area has grown enormously. As a result, there exists a wealth of information on lipid phase behavior, but unfortunately, these data have, until now, been scattered throughout the literature in a variety of books, proceedings, and journals. The data have recently been compiled in a centralized database with a view to providing ready access to the same and to the appropriate literature. The compilation facilitates review of what has thus far been accomplished and highlights what remains to be done in this active research area. As such, it represents a convenient summary of the existing data which, when evaluated, will enable us to identify where deficits exist in the data, to reveal the fundamental physicochemical principles upon which lipid phase behavior is based, and to understand more completely lipid phase relations in biological, reconstituted, and formulated systems. The compilation consists of a tabulation of all known mesomorphic and polymorphic phase transition temperatures and enthalpy changes for synthetic and biologically derived lipids in the dry and in the partially and fully hydrated states. Also included is the effect on these thermodynamic values of pH, and of salt and metal ion concentration and other additives such as proteins, drugs, etc. The methods used in making the measurements and the experimental conditions are reported. Bibliographic information includes complete literature referencing and list of authors. As of this writing, the database is current through June 1990 and contains 9500 records. Each record contains 28 fields. Here, we describe how the database originated, its scope and contents, data abstraction procedures, and issues relating to mesophase and lipid nomenclature, data analysis, and evaluation, and database maintenance and distribution.