Layered lithium chromium manganese oxide compounds for high capacity electrode materials in rechargeable lithium batteries

A series of Li[Cr_xLi_(1−x)/3Mn_2(1−x)/3]O₂ cathode materials were prepared by the sol-gel process. The structural characterization was carried out by fitting the XRD data by the Rietveld method. The results of X-ray diffraction show that the crystal structure is similar to that of thelayered lithium transition metal oxides (R3-m space group). The particle morphology and size were observed by SEM, and the elemental content was determined by ICP. The electrochemical performance of the cathode was evaluated in the voltage range of 2.0 ∼ 4.9 V with a current density of 7.947 mA/g. The Li_1.27Cr_0.2Mn_0.53O₂ electrode delivered a high reversible capacity of around 280 mAh/g in cycling. Li[Cr_xLi_(1−x)/3Mn_2(1−x)/3]O₂ was found to be a promising cathode material. Paper presented at the International Conference on Functional Materials and Devices 2005, Kuala Lumpur, Malaysia, June 6 – 8, 2005.     

The Politics of Memory: Otto Hahn and the Third Reich

As President of the Kaiser Wilhelm Society and its successor, the Max Planck Society, from 1946 until 1960, Otto Hahn (1879–1968) sought to portray science under the Third Reich as a purely intellectual endeavor untainted by National Socialism. I outline Hahn’s activities from 1933 into the postwar years, focusing on the contrast between his personal stance during the National Socialist period, when he distinguished himself as an upright non-Nazi, and his postwar attitude, which was characterized by suppression and denial of Germany’s recent past. Particular examples include Hahn’s efforts to help Jewish friends; his testimony for colleagues involved in denazification and on trial in Nuremberg; his postwar relationships with émigré colleagues, including Lise Meitner; and his misrepresentation of his wartime work in the Kaiser Wilhelm Institute for Chemistry.     

The kinetics of the reaction between magnesium and EBT

The kinetics of the reaction between Mg²⁺ and Eriochrome-Black-T (EBT) has been investigated in the pH range between 7.05 and 9.0, in the presence of 12% ethanol. The reaction is found to consist of two parallel paths, one involving the tervalent unprotonated ligand, and one its monoprotonated form. The rate constant for the unprotonated ligand has a “normal” value, whereas that for the protonated form is much lower. The numerical value of the rate constant for the unprotonated ligand obtained from results at a magnesium concentration of 10^?3M and a pH up to 9.0 is, however, inconsistent with that obtained from results at [Mg²⁺] = (1 to 4) × 10^?3M and pH up to 8.1. This can be explained, at least partially, if we assume the intermediate MgHD to lose its proton not only to H₂O, but also to other bases present in the solution.     

Hasse's class number product formula for generalized Dirichlet fields and other types of number fields

In the 1950's Hasse gave a formula that relates the class number of a biquadratic dicyclic number field to the class numbers of its, three quadratic subfields. Similar formulas are derived here for biquadratic dicyclic extensions of more general base fields, in cases where the base fields retain several properties of ℚ. This article was processed by the author using the Springer-Verlag T_EX mamath macro package 1990     

Chromatic polynomials and whitney's broken circuits

The theorem of Hassler Whitney, which gives the chromatic polynomial of a graph in terms of “broken circuits,” is used to derive a new formula for the coefficients of chromatic polynomials.     

Palladium-catalyzed 1,4-acetoxy-trifluoroacetoxylation of 1,3-dienes

Palladium-catalyzed oxidation of conjugated dienes in acetic acid containing CF₃COOH/LiOOCCF₃ results in the formation of 1-acetoxy-4-trifluoroacetoxy-2-alkenes.     

The application of the sulphide contraction to the synthesis of some simple pyrrolidine alkaloids

The alkaloids (±)-hygrine, (±)-dehydrodarlinine, (±)-dehydrodarlingianine, and (±)-N-methylruspolinone have been synthesised by selective reduction of vinylogous amides formed by sulphide contraction of the salts prepared by reaction of N-methyl-2-thiopyrrolidone with the appropriate bromomethyl ketones.