Nonlinear transport properties of quantum dots

The influence of excited levels on nonlinear transport properties of a quantum dot weakly coupled to leads is studied using a master-equation approach. A charging model for the dot is compared with a quantum mechanical model for interacting electrons. The currentvoltage curve shows Coulomb lockade and additional finestructure that is related to the excited states of the correlated electrons. Unequal coupling to the leads causes asymmetric conductance peaks. Negative differential conductances are predicted due to the existence of excited states with different spins.     

MIITiO(C2O4)2·4H2O (MII=Mg,Ca, Sr OR Ba) as precursors in the formation of MIITiO3 powders

A synthesis route is described for the preparation of the alkaline earth metal titanyl oxalates M^IITiO(C₂O₄)₂·4H₂O (M^II=Mg, Ca, Sr or Ba). The thermal decompositions of these compounds were studied by means of DTA and TG in comparison with X-ray measurements. The final products M^IITiO₃ were characterized morphologically.

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Zusammenfassung Ein Syntheseweg für die Darstellung der Erdalkalimetalltitanyloxalate M^IITiO(C₂O₄),·4H₂O (M ^II=Mg, Ca, Sr, Ba) wird beschrieben. Die thermische Zersetzung dieser Verbindungen wurde mittels DTA und TG sowie Röntgenbeugungsmethoden untersucht. Die entstehenden Titanate M^IITiO₃ wurden hinsichtlich ihrer morphologischen Eigenschaften charakterisiert.

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- MⁱⁱTiO(C₂O₄)₂ · 4₂, ⁱⁱ = , , . , . ⁱⁱiO₃, .

     

Über Glasbildung und Eigenschaften von Chalkogenidsystemen. XXXIII. [1] Kondensierte Thio- und Selenohypodigermanate und -silicate Na8M4X10 (MSi,Ge) und Na4Ge4X8 (XS,Se)

About Glass Formation and Properties of Chalcogenide Systems. XXXIII. Condensed Thio- and Selenohypodigermanates and -silicates Na₈M₄X₁₀ (M?Si, Ge) and Na₄Ge₄X₈ (X?S, Se) The formation of the compounds Na₈Si₄X₁₀ and Na₈Ge₄X₁₀ (X?S, Se) is reported prepared by reaction of Ge₂S₃ or Ge₂Se₃ with Na₂S or Na₂Se, respectively, in CH₃OH utilizing a mole ratio of 1 to 2 or in the case of the Si compounds by synthesis from the elements. Applying the mole ratio Ge₂X₃:Na₂X = 1 the compounds Na₄Ge₄X₈ (X?S, Se) are obtained. The anion constitution is discussed in relation with cryoscopic mole weight measurements in Glauber-salt melts.     

The classification of doubly transitive affine designs

We classify the doubly transitive affine designs. The proof uses the classification of the multiply transitive permutation groups.     

Comparison of methods for the spectrophotometric determination of phenols in automobile exhaust fumes

Summary The piperonal chloride reaction has been used for the quantitative determination of phenols in raw automobile exhaust fumes. This method is compared with five other methods found suitable for this purpose, and accuracy, sensitivity, and simplicity of the procedures are evaluated. Recommendations are made for the selection of methods.

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Zusammenfassung Die quantitative Bestimmung von Phenolen in rohen Automobilauspuffgasen wurde unter Benutzung der Reaktion mit Piperonalchlorid ausgeführt. Diese Methode wurde mit fünf anderen für diesen Zweck geeignet erscheinenden Verfahren hinsichtlich Genauigkeit, Empfindlichkeit und Handlichkeit verglichen, woraus sich Vorschläge für die Wahl der jeweils geeignetsten Methode ergeben.

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Résumé On a utilisé la réaction au chlorure de pipéronal pour doser les phénols dans les fumées d'échappement brutes des automobiles. On compare cette méthode avec cinq autres que l'on estime satisfaisantes et l'on évalue la précision, la sensibilité et la simplicité des procédés. On donne des recommandations pour la sélection des méthodes.

     

Heat blocking gallium arsenide solar cells

The solar cell industry is witnessing an era of unprecedented growth and this trend is set to continue for the foreseeable future. Here we describe a heat reflection pigment-coated single-junction gallium arsenide solar cell that is capable of reflecting heat-inducing near-infrared radiation. The cell maintains its performance better than non-coated cells when exposed to infrared-rich radiant flux. In situations where solar cells get heated mainly from incident infrared radiation, these cells exhibit superior performance. The heat reflecting pigment, cell structure, coating process and cell performance have been described. PACS 84.60.Jt; 42.70.Km; 42.79.Wc