On the Extreme Oxidation States of Iridium

It has recently been suggested that the oxidation states of Ir run from the putative ?III in the synthesized solid Na₃[Ir(CO)₃] to the well‐documented +IX in the species IrO₄⁺. Furthermore, [Ir(CO)₃]^3? was identified as an 18‐electron species. A closer DFT study now finds support for this picture: The orbitals spanned by the 6s,6p,5d orbitals of the iridium are all occupied. Although some have considerable ligand character, the deviations from 18 e leave the orbital symmetries unchanged. The isoelectronic systems from Os^?IV to Au^?I behave similarly, suggesting further possible species. To paraphrase Richard P. Feynmann “there is plenty of room at the bottom”.     

Determination of wear metals in lubrication oils: a comparison study of ICP-OES and FAAS.

Certain wear metals (Fe, Cr, Ni, Cu and Zn) of various lubrication oils were determined by means of ICP-OES and FAAS. The kerosene dilution method, which is used widely together with ICP-OES, was applied with both methods here. Calibration standards were made from a commercial organo-metallic standard. Our aim was to clarify the possibility of using the quick kerosene dilution method together with FAAS for a rapid check for certain indicator metals. Metal determinations with FAAS were accurate enough for quantitative work in machine condition diagnostics and waste oil characterization, when compared with those with ICP-OES.     

Rapidity gap correlations in short range order models

We show that short range order models relate the multiplicity distribution produced in a rapidity interval R of the central region, to the distribution of such intervals which all contain a fixed multiplicity N. This is an asymptotic result which furthermore implies that the asymptotic behavior of the Mueller moments be related to certain rapidity gap correlation moments. The behavior of these gap correlations in specific models depends in a direct way on the assumptions made about clustering and about the range of the interaction.     

Quantum theory of measurement and the modal interpretations of quantum mechanics

Several variants of the modal interpretation of quantum mechanics have been introduced and discussed in recent years. In this paper we present a study of the mathematical foundations of such an interpretation in the framework of the quantum theory of measurement.     

Diastereoselective cobalt-catalyzed reductive aldol cyclizations using diethylzinc as the stoichiometric reductant

[reaction: see text] Cobalt catalysis enables a new method for the generation of zinc enolates using diethylzinc to reduce alpha,beta-unsaturated amides. This method has been applied to a high-yielding diastereoselective reductive aldol cyclization.     

Water Activity and Freezing Points in Aqueous Solutions of Manganese Nitrate: Experimental and Modeling

The water activities of manganese nitrate solutions were measured using a humidity sensor instrument up to almost the saturation molality at 298.15 K; the thermodynamic properties of the system were described by the Pitzer model and specific interaction theory (SIT). The evaluation of the ion interaction parameters for the Pitzer model and SIT were carried out using experimental freezing points and osmotic coefficients of manganese nitrate aqueous solutions, collected from the open literature, and the water activity data measured in this work. A set of Pitzer and SIT parameters were estimated using a temperature dependency, that enables us to cover wider temperature ranges, and consequently calculate system properties to higher molalities. Both approaches represent very satisfactorily, and with similar accuracy, the experimental data and the calculated manganese nitrate molal activity coefficients are comparable to those already published for analogous systems. Additionally, the Pitzer model was also able to calculate the ice curve and the solubility branch of manganese nitrate hexahydrate up to a salt solution 6.5 mol·kg^?1.     

Deuteron quadrupole coupling in benzene: librational corrections using a temperature-dependent Einstein model, and summary. The symmetries of electric field gradients and conditions for eta = 1

Librational corrections are added to previous single-crystal and polycrystalline measurements of the deuteron quadrupole coupling constant in benzene. The results are related to gas-phase and liquid-crystal measurements and to theoretical values. A 'temperature-dependent Einstein model' is introduced for the purpose. The group-theoretical relations of the electric field-gradient (EFG) tensor to the nuclear site symmetry are discussed. The conditions for eta = 1 for reorientational processes are identified.     

Large-scale differential display analysis of T helper cell differentiation

We have developed a novel large-scale multicapillary fluorescent differential display (FDD) platform amenable to further automation. The power of the method is demonstrated by the analysis of T helper cell differentiation. Eight RNA samples from wild type, Stat4 knockout and Stat6 knockout mice were analyzed with 16 anchoring primers and 24 arbitrary primers, resulting in 285 294 sample peaks. Visually selected patterns of differential expression suggest two major regulatory mechanisms: activation and Stat4 genotype. A subset of the findings is reproduced in the confirmatory differential display (DD) that included technical and biological replicates. In a small fragment identification pilot study, we identify Ifi27 and Cct8 to be up-regulated by T cell activation. We present a method for the analysis of electropherogram similarity across large datasets, based on correlation of low-resolution representations of electrophoretic data. We show how it can be applied to analyze experimental and technical variables. Using this method, we demonstrate the effect of activation and genotype. In addition, agreement of our real experimental data to the theoretical basis of DD, as well as issues in anchoring primer selectivity, are studied.     

Radioactivity in the Baltic Sea: inventories and temporal trends of <Superscript>137</Superscript>Cs and <Superscript>90</Superscript>Sr in water and sediments

The Baltic Sea is ecologically unique as one of the world’s largest brackish water basins. It was significantly contaminated by radioactivity following the Chernobyl accident in 1986, the major contaminant being long-lived ¹³⁷Cs. Due to the slow exchange of water between the Baltic Sea and the North Sea and the relatively rapid sedimentation rates, radionuclides have prolonged residence times in the Baltic Sea. ¹³⁷Cs levels are consequently still clearly higher than in other water bodies around the world. In addition to the Chernobyl accident, artificial radionuclides in the Baltic Sea originate from the global fallout following nuclear weapons testing in the 1950s and 1960s, while discharges into the Baltic Sea from nuclear power plants and other facilities are of minor importance. Here, inventories and the temporal evolution of radionuclides both in seawater and sediments of the Baltic Sea are presented and discussed.