Spin polarization dynamics and the Hanle effect for a strong exchange interaction in the exciton

The exciton spin dynamics in a quantum well with a magnetic field applied in its plane is analyzed theoretically. The exchange interaction between the electron and the hole is assumed to be strong. The width of the Hanle effect profile is shown to depend on the hole spin relaxation time. The intensity signal obtained under pulsed exciton generation as a function of time is characterized by two decay times, and the polarization signal, by a third time which is strongly dependent on the applied field.     

Stacking reactions of the borole complex Cp*Rh(η5-C4H4BPh) with the dicationic fragments [Cp*M]2+ (M = Rh or Ir)

The reaction of the (borole)rhodium iodide complex [(η-C₄H₄BPh)RhI]₄ with Cp^*Li afforded the sandwich compound Cp^*Rh(η-C₄H₄BPh) (4). The reactions of compound 4 with the solvated complexes [Cp^*M(MeNO₂)₃]²⁺(BF ₄ ⁻ )₂ gave triple-decker cationic complexes with the central borole ligand [Cp^*Rh(η-η⁵:η⁵-C₄H₄BPh)MCp^*]²⁺(BF ₄ ⁻ )₂ (M = Rh (5) or Ir (7)). The structure of complex 4 was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1525–1527, September, 2006.     

(Arene)ruthenium complexes with the monoanionic carborane ligand [9-SMe2-7,8-C2B9H10]–

The ruthenium arene complexes [(-arene)Ru(-9-SMe₂-7,8-C₂B₉H₁₀)]⁺ (arene = C₆H₆ (3a); arene = 1,3,5-C₆H₃Me₃ (3b)) with the monoanionic carborane ligand were synthesized by the reactions of the [9-SMe₂-7,8-C₂B₉H₁₀]^– anion with [(-arene)RuCl₂]₂. The structure of the compound [3a]BPh₄ was established by single-crystal X-ray diffraction analysis.     

Electrochemical behaviour of cobalta-dicarbollide sandwich complexes with different capping units

The redox aptitude of a series of cobalt(III) or cobalt(I) sandwich complexes bearing a charge compensated dicarbollide ligand ([9-L-7,8-C₂B₉H₁₀]⁻) as a constant unit and different counterparts (varying from classical [7,8-C₂B₉H₁₁]²⁻ to charge-compensated [9-L-7,8-C₂B₉H₁₀]⁻ dicarbollides, from cyclopentadienyl [C₅R₅]⁻ (R = Me, H) to cyclobutadiene [C₄Me₄]⁰ ligands) has been studied. All the Co(III) complexes display the reversible sequence Co(III)/Co(II)/Co(I). In contrast, the Co(I) complexes (namely, those capped by tetramethylcyclobutadiene) accede reversibly only to the Co(II) oxidation state, the passage to Co(III) being irreversible. When possible, the Co(II) intermediates have been characterized by EPR spectroscopy. The molecular structures of the monocation [Co(η-9-SMe₂-7,8-C₂B₉H₁₀)₂]⁺ in its DD/LL and meso diastereomeric forms as well as that of heteroleptic (η-7,8-C₂B₉H₁₁)Co(η-9-SMe₂-7,8-C₂B₉H₁₀) have been obtained by single-crystal diffraction. Presented at the 3rd Chianti Electrochemistry Meetings July 3−9, 2004, Certosa di Pontignano, Italy     

Modeling of the kinetics of nickel reduction from a multicomponent oxide melt with a gaseous reducing agent

A model was suggested that allows the kinetics of bubbling of various reducing gases through an oxide melt to be described by thermodynamic equilibrium calculations without the use of experimental data. An algorithm for calculations was developed. The model is tested for the NiO-FeO-Al₂O₃-SiO₂-CaO-Mg-CO-CO₂ system. A comparative analysis of the calculation results and experimental data showed that the suggested technique could be used in a qualitative analysis of interactions between multicomponent oxide melts and gaseous reducing agents of various compositions. Calculations describing the kinetics of reduction of nickel oxide with hydrogen in the NiO-CaO-B₂O₃ system over the temperature range 1473–1973 K were performed.     

Efficient delivery of Cre-recombinase to neurons in vivo and stable transduction of neurons using adeno-associated and lentiviral vectors

Background

As development proceeds the human embryo attains an ever more complex three dimensional (3D) structure. Analyzing the gene expression patterns that underlie these changes and interpreting their significance depends on identifying the anatomical structures to which they map and following these patterns in developing 3D structures over time. The difficulty of this task greatly increases as more gene expression patterns are added, particularly in organs with complex 3D structures such as the brain. Optical Projection Tomography (OPT) is a new technology which has been developed for rapidly generating digital 3D models of intact specimens. We have assessed the resolution of unstained neuronal structures within a Carnegie Stage (CS)17 OPT model and tested its use as a framework onto which anatomical structures can be defined and gene expression data mapped.

Results

Resolution of the OPT models was assessed by comparison of digital sections with physical sections stained, either with haematoxylin and eosin (H&E) or by immunocytochemistry for GAP43 or PAX6, to identify specific anatomical features. Despite the 3D models being of unstained tissue, peripheral nervous system structures from the trigeminal ganglion (~300 μm by ~150 μm) to the rootlets of cranial nerve XII (~20 μm in diameter) were clearly identifiable, as were structures in the developing neural tube such as the zona limitans intrathalamica (core is ~30 μm thick). Fourteen anatomical domains have been identified and visualised within the CS17 model. Two 3D gene expression domains, known to be defined by Pax6 expression in the mouse, were clearly visible when PAX6 data from 2D sections were mapped to the CS17 model. The feasibility of applying the OPT technology to all stages from CS12 to CS23, which encompasses the major period of organogenesis for the human developing central nervous system, was successfully demonstrated.

Conclusion

In the CS17 model considerable detail is visible within the developing nervous system at a minimum resolution of ~20 μm and 3D anatomical and gene expression domains can be defined and visualised successfully. The OPT models and accompanying technologies for manipulating them provide a powerful approach to visualising and analysing gene expression and morphology during early human brain development.     

Polymorphous transformations of rubidium-lithium and cesium-lithium double sulphates

Anhydrous double salts of rubidium sulphate and cesium sulphate with lithium sulphate have been prepared, and polymorphous transformations at+60° and +200° for Rb₂SO₄ · Li₂SO₄ and at –75° for Cs₂SO₄ · Li₂SO₄ have been disclosed by means of differential thermal analysis. These findings were confirmed by dilatometric measurements and X-ray phase analysis at various temperatures.

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Zusammenfassung Mit Hilfe differentialthermoanalytischer Untersuchungen konnten polymorphe Umwandlungen in den wasserfreien Doppelsalzen Rubidiumsulfat-Lithiumsulfat bzw. Cäsiumsulfat-Lithiumsulfat festgestellt werden. Die entsprechenden Temperaturen betragen bei Rb₂SO₄ · Li₂SO₄ +60° und +200°, bei Cs₂SO₄ · Li₂SO₄ –75°. Diese Befunde wurden durch dilatometrische Messungen und weiterhin durch röntgenographische Phasenanalyse bei verschiedenen Temperaturen bekräftigt.

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Résumé On a observé, lors de l'examen par ATD de Rb₂SO₄ · Li₂SO₄ et Cs₂SO₄ · Li₂SO₄ anhydres, des transformations polymorphiques à + 60° et à + 200° dans le cas de la première combinaison et à –75° dans le cas de la seconde. Ces observations ont été confimées par les résultats dilatométriques et d'analyse de phase par rayons X.

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. +60° +200° Rb₂SO₄. Li₂SO₄ –75° Cs₂SO₄. Li₂SO₄. .

     

Synthesis of asymmetrical bis(arene) iron complexes

Visible light irradiation of the [(η-C₆H₇)Fe(η-C₆H₆)]⁺ cation (1) in CH₂Cl₂ in the presence of alkyl-substituted benzenes results in arene exchange forming the [(η⁵-C₆H₇)Fe(η-C₆R₆)]⁺ cations (2a–d: C₆R₆ is toluene, p-xylene, mesitylene, and durene). The mixed bis(arene) [(η-C₆H₆)Fe(η-C₆R₆)]²⁺ iron complexes (3a–d) were synthesized by hydride ion abstraction from 2a–d by [Ph₃C]⁺. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1864–1865, September, 2007.