Bildung von Mischkristallen bei Verbindungen vom Huréaulith-Typ

We investigated to what an extent mixed crystals of phosphates (arsenates) of Mn and Cd, [M₅(HPO₄)₂(PO₄)₂ · 4 H₂O], with Fe(II), Co, Ni, Zn and Cu can be formed.     

Simple Sulfinate Synthesis Enables CH Trifluoromethylcyclopropanation

A simple method to convert readily available carboxylic acids into sulfinate salts by employing an interrupted Barton decarboxylation reaction is reported. A medicinally oriented panel of ten new sulfinate reagents was created using this method, including a key trifluoromethylcyclopropanation reagent, TFCS‐Na. The reactivity of six of these salts towards C? H functionalization was field‐tested using several different classes of heterocycles.     

Noninvasive Assessment of UV-induced Skin Damage: Comparison of Optical Measurements to Histology and MMP Expression

Acute exposure to UV radiation (UVR) causes visible skin damage such as erythema and results in local and systemic immunosuppression while chronic exposure can result in photocarcinogenesis. These deleterious effects can be quantified by histology and by bioassays of key biological markers, including matrix metalloproteinases (MMPs), or tryptophan moieties. We now report our results in quantifying UV skin damage with noninvasive optical methods based on reflectance and fluorescence spectroscopy and compare these noninvasive measurements to histopathology and MMP-13 expression. A solar simulator with spectral output nearly identical to that of solar radiation was developed and used in our experiments. SKH1 hairless mice were exposed to solar-simulated UVR at a total dose of 21 MED delivered over 10 weeks. Changes in oxygenated and deoxygenated hemoglobin were measured by diffuse reflectance spectroscopy, and tryptophan changes were monitored via a fluorescence monitor. Our results show that there is an increase in erythema, skin fluorescence, sunburn cells and MMP-13 after a series of suberythemal doses of UV irradiation on a hairless mouse animal model. Increased skin fluorescence is observed with increasing UV exposure. The levels of MMP-13 increase as the cumulative UV dose increases but their increase does not correspond to noninvasively measured changes.     

Formation of small rhodium metal particles on the surface of a carbon support

A rhodium catalyst supported on a Sibunit graphitized carbon carrier was studied by in situ XAFS spectroscopy. A comparative study of the reduction of rhodium was performed for the following two samples: Rh/C(120) dried at 120°C and Rh/C(350) calcined at 350°C. EXAFS data showed an absence of carbon atoms within the nearest environment of rhodium atoms in the Rh/C(120) uncalcined sample, which implies the absence of direct interaction between rhodium and the carbon support. In the course of the reduction of this sample (200°C), coarse particles with small metal cores were initially formed. These metal particles rapidly agglomerated upon the complete reduction of rhodium (350°C). These reduction of the Rh/C(350) calcined sample at 100–500°C resulted in the formation of small metal particles early in the reduction (100°C). The high dispersity of these particles was retained as the temperature of treatment in hydrogen was increased to 500°C due to metal-support interaction. The conversion of benzene into cyclohexane on the Rh/C(350) catalyst containing small rhodium particles was much higher at the same temperature of hydrogenation.Translated from Kinetika i Kataliz, Vol. 46, No. 1, 2005, pp. 122–130. Original Russian Text Copyright © 2005 by Stakheev, Tkachenko, Klementev, Grünert, Bragina, Mashkovskii, Kustov.     

Bildung von Diphosphaten aus geschmolzenem Natriumtrimetaphosphat, 3. Mitt.

Zusammenfassung Beim Auflösen der Oxide von Ti(IV), Ni und Co in geschmolzenem Na₃P₃O₉ bilden sich die Diphosphate Na₂(TiO) P₂O₇, Na₂NiP₂O₇ und Na₂CoP₂O₇. Beim Auslaugen der erstarrten Schmelze mit Wasser tritt auch Na₂Co₃(P₂O₇)₂·4 H₂O auf; ein entsprechendes Hydrat wird auch bei Mn(II) gefunden. Außerdem bildet Mn (II) ein Polyphosphat [Mn (PO₃)₂] _n . — Beim Auflösen eines Gemisches aus SrO und PbO in wechselnden Mengenverhältnissen entstehen nebeneinander Mischkristalle von Na₂(Sr, Pb) P₂O₇ mit wechselndem Verhältnis Sr,Pb und von einem Ultraphosphat [(Sr, Pb) P₄O₁₁] _n mit dem konstanten Verhältnis Sr,Pb=0,66,0,34. — Die Polyphosphate von Mn und von Sr–Pb werden papierchromatographisch und IR-spektroskopisch untersucht. — Die Bildung von Diphosphaten aus einer Polyphosphatschmelze wird an Hand der hier und früher beschriebenen Befunde zu deuten versucht.

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On dissolving the oxides of Ti(IV), Ni or Co in molten Na₃P₃O₇ the diphosphates Na₂(TiO) P₂O₇, Na₂NiP₂O₇ and Na₂CoP₂O₇ are formed respectively. Mn(II) forms a polyphosphate [Mn(PO₃)₂] _n . On dissolving a mixture of SrO and PbO of varying ratio one obtains at the same time mixed crystals of Na₂(Sr,Pb)P₂O₇ with a variable ratio of Sr,Pb and an ultraphosphate [(Sr,Pb)P₄O₁₁] _n with a constant ratio Sr,Pb=0,66,0,34. An interpretation of the formation of diphosphates from a melt of polyphosphates is attempted, using the present and previous observations.

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Mit 1 Abbildung

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Herrn Prof. Dr.E. Hayek zum 60. Geburtstag gewidmet.     

Cadmium

Ohne Zusammenfassung     

Imperfection of the Sm sublattice and valence instability in compounds based on SmB6

The magnetic susceptibility, electrical resistance, specific heat, and thermal expansion coefficient of SmB₆, Sm_0.8B₆, and Sm_1–x La_xB₆ (x=0.1 and 0.2) are measured in the temperature range T=4–300 K. The dispersion curves of the acoustic phonon branches in lanthanum-doped samples are studied. A combined analysis of the results confirms the existence of an activation gap in the electron density of states in both nonstoichiometric and lanthanum-doped compounds. The anomalies in the electronic component of the thermal expansion coefficient are associated to a considerable degree with the temperature variation of the valence and, like the magnetic susceptibility, reflect features of the f-electron excitation spectrum. It is found that lanthanum doping does not lead to significant changes in the anomalies in the phonon spectrum of SmB₆. It is established that the homogeneous intermediate-valent state of the samarium ion is fairly stable and is maintained when the perfection of the Sm sublattice is violated. Zh. éksp. Teor. Fiz. 115, 1024–1038 (March 1999)     

The special features of the ground state in CeAl3

The temperature (3–60 K) and transferred momentum (0.3–2.3 Å^?1) dependences of the intensity of quasi-elastic magnetic neutron scattering were studied for the polycrystalline heavy-fermion CeAl₃ compound to elucidate the special features of its ground state. Transferred momentum variations caused oscillations of the intensity of quasi-elastic magnetic neutron scattering, which was evidence of magnetic correlations in the f-electron subsystem occurring in a fairly wide temperature range.