Transient behavior of a nonequilibrium plasma formed by merged beams

A low density, low temperature plasma formed by two merged beams of electrons and ions at near zero relative velocity is studied by solving a set of time-dependent rate equations. In particular, we investigate the role played by the radiative recombination (RR) and three-body recombination (TBR) on the population of excited states during the initial stage of plasma rearrangement and relaxation. It is found in the case of hydrogenic plasmas that low-lying states are filled predominantly by RR, while high Rydberg states are populated mainly by TBR. As the plasma further relaxes, the collisional excitation and de-excitation, and radiative decays become important, filling the median excited states. The dependence of the TBR and RR rates on ionic chargeZ is discussed to extend the result to plasmas of highZ ions.     

Metastasis-suppressor KAI1/CD82 induces homotypic aggregation of human prostate cancer cells through Src-dependent pathway

To investigate the functional role of KAI1/CD82, a metastasis suppressor for human prostate cancer, in the regulation of homotypic cell adhesion, we transfected KAI1 cDNA into DU 145 human prostate cancer cells and established stable transfectant clones with high KAI1/CD82 expression. The KAI1 transfectant cells exhibited significantly increased homotypic cell aggregation in comparison with the control transfectant cells. This aggregation of the KAI1 transfectants was further enhanced upon exposure to anti-CD82 antibody, suggesting that KAI1/CD82 may be involved in the intracellular signaling for the cell adhesion. Among several signal pathway inhibitors tested, PP1, an inhibitor of Src family kinases, significantly suppressed homotypic aggregation of the KAI1 transfectant cells. Ligation of KAI1/CD82 with anti-CD82 antibody increased endogenous Src kinase activity of the KAI1 transfectant cells. When different types of src expression constructs were retransfected into the KAI1-transfected DU 145 cells, kinase-negative mutant src transfectant cells exhibited much lower homotypic aggregation than the mock cells transfected with an empty vector. Moreover, homotypic aggregation of the mutant src transfectant cells was not enhanced by KAI1/CD82 ligation with anti- CD82 antibody. These results suggest that Src mediates the intracellular signaling pathway of KAI1/CD82 for the induction of homotypic adhesion of human prostate cancer cells.     

Untersuchungen über ternäre Chalkogenide. XXIV. Zur Struktur des TlGaSe2

On Ternary Chalcogenides. XXIV. The Structure of TlGaSe₂ TlGaSe₂ is monoclinic with a = 10.772(3), b = 10.771(5), c = 15.636(8) Å, ß = 100.6(3)°, Z = 16, space group Cc. The refinement yielded an R value of 0.082 for 1366 unique observed reflections (MoKα). The compound crystallizes with a layer structure with two anion layers perpendicular to c* in the unit cell. The structural motive of the layers are large corner-linked Ga₄Se₁₀- tetraeder consisting of four corner-linked GaSe₄ tetrahedra. Two adjacent layers are turned relative to each other by 90°. They are kept together by Tl¹⁺ ions, which are situated on straight lines parallel to the edges of the Ga₄Se₁₀ groups. They are surrounded by six selenium atoms forming trigonal-prismatic TlSe₆ polyhedra. 4₂ screw-axes within the layers are the reason for a strongly pronounced pseudo tetragonal symmetry. Different possibilities of stacking cause a onedimensional disorder along the c* direction. The relations between the TlGaSe₂ type and the TlSe type and also the high-pressure modifications of some compounds with the TlGaSe₂ structure are discussed.     

Beiträge zur Chemie des Phosphors. 105. 1,2,3,4-Tetraphenyl-1,4-bis(trimethylsilyl)-tetraphosphan und 1,2,3,4-Tetraphenyltetraphosphan

Contributions to the Chemistry of Phosphorus. 105. 1,2,34-Tetraphenyl-1,4-bis(trimethylsilyl)-tetraphosphane and 1,2,3,4-Tetraphenyltetraphosphane 1,2,3,4-Tetraphenyl-1,4-bis(trimethylsilyl)-tetraphosphane, Me₃Si? (PPh)₄? SiMe₃ ( 1 ), is obtained by reacting K₂(PPh)₄ with trimethylchlorosilane under suitable conditions. Compound 1 disproportionates almost easier than the corresponding triphosphane (Me₃Si)₂(PPH)₃. Of the six possible diastereomers only 1a (erythro, meso, erythro), 1b (erythro, d,l, erythro), 1 d (threo, d,l, threo), and 1 f (erythro, threo, threo) can be detected in solution by ³¹P-NMR spectroscopy. In consequence of rapid inversion at the P atoms a dynamic equilibrium exists between the different isomers. The assignment of the ³¹P-NMR-spectroscopically observed spin systems to the corresponding diastereomers results from the dependence of the ¹J_PP-coupling constants on the dihedral angle between vicinal free electron pairs as well as on the observed frequency distribution. In the alcoholysis of 1 the corresponding hydride H? (PPh)₄? H ( 2 ) is formed as the main product. It could be isolated in spite of its instability. At room temperature 2 disproportionates rapidly forming mainly (PPh)₄ and H₂(PPh)₂ (ratio 1:2) at first; later on also H₂(PPh)₃, H₂PPh, and (PPh)₅ are found. The corresponding rearrangements follow a four-center mechanism involving predominantly P? P bonds.     

Über ternäre Thalliumchalkogenide mit Thalliumselenidstruktur

On Ternary Thallium Chalcogenides with Thallium Selenide Structure. By means of single crystal investigations, it has been confirmed that the compounds TlGaTe₂, TIInSe₂, and TIInTe₂ crystallize in the TISe type (B37). As an univalent cation thallium is surrounded by eight chalcogen atoms. Gallium and indium are trivalent with tetrahedral coordination and covalent bonds. The interatomic distances as well as coordination and bonding resulting from them are discussed.     

Über Silicid- und Germanidchalkogenide des Thoriums

On Thorium Silicide and Germanide Chalcogenides The compounds ThSiS, ThSiSe, ThSiTe, ThGeS, ThGeSe, and ThGeTe were synthetized from the elements at temperatures ranging from 800 to 1050°C. For structural X-ray investigation single crystals of the compound ThGeS were grown. ThGeS is tetragonal, space group I4/mmm with a = 3.9411(7), c = 17.1395(40) Å, and Z = 4. In order to refine the structure parameters intensity measurements were carried out by means of a four-circle single crystal diffractometer. By indexing the Debye-Scherrer diagrams the remaining ternary thorium chalcogenides were proved to be isostructural with ThGeS. This structure type is identical with the anti-Ti₂Bi-type structure and closely related to the PbFCl structure in the sense of a transposition structure. The interatomic distances, the relations to comparable structures and possible reasons for the formation of the anti-Ti₂Bi-type structure by ternary chalcogenides of the actinides are discussed.     

Beiträge zur Chemie des Phosphors. 167 [1, 2]. Konstitutions- und Konfigurationsisomere von Pentaphosphan(7), P5H7

Contributions to the Chemistry of Phosphorus. 167. Constitutional and Configurational Isomers of Pentaphosphane(7), P₅H₇ Phosphane mixtures containing 10—15 P-% of pentaphosphane(7), P₅H₇, are obtained by thermolysis of diphosphane, P₂H₄, or as residue from distillation of crude diphosphane [3]. According to the complete analysis of the ³¹P{¹H}-NMR spectrum on the basis of selective population transfer experiments, P₅H₇ exists as a mixture of three diastereomers of n-P₅H₇ — 1a (erythro, erythro), 1b (erythro, threo), 1c (threo, threo) — and of the constitutional isomer 2-phosphinotetraphosphane 2 (iso-P₅H₇, largest relative isomeric abundance). The correlation between the diastereomers and the observed spin systems results from the preferred gauche orientation of neighboring free electron pairs, the dependence of ¹J(PP) on dihedral angles, and the ³J(PP) long range couplings. From the ³¹P-NMR data of the phosphane molecules P_nH_n+2 with n = 1—5 general relationships for the δ(³¹P) values and the ¹J(PP) coupling constants of chain-type phosphorus hydrides as a function of their structural parameters are derived.     

Potentiometric titration of milligram quantities of uranium in the presence of iron

A method is described for the potentiometric titration of milligram quantities of the uranium(IV) ion in the presence of iron. This is accomplished by complexing the iron with 1.10-phcnanthroline. The uranium can then be titrated with standard ceric sulfate without interference from the iron.     

Beiträge zur Chemie des Phosphors. 143. Li4P26 und Na4P26, die ersten Salze mit Hexacosaphosphid(4−)-Ionen

Contributions to the Chemistry of Phosphorus. 143. Li₄P₂₆ and Na₄P₂₆, the First Salts with Hexacosaphosphid(4?) Ions The hexacosaphosphides Li₄P₂₆ ( 1 ) and Na₄P₂₆ ( 2 ) are formed besides other polyphosphides in the reaction of white phosphorus with lithium dihydrogenphosphide or sodium. 1 also results from the decomposition of Li₂HP₇ in tetrahydrofuran at room temperature and can be obtained pure as a crystalline solvent adduct Li₄P₂₆ · 16 THF. According to 2D?³¹P-NMR spectroscopic investigations the P₂₆^4? ion is a conjucto-phosphane of two P₇(5)^?-and two P₉(3)^?-unit groups with structures analogous to norbornane and deltacyclane, respectively.