Band structure enhancement of indirect transitions

Indirect and direct transitions in Ga_xIn_1?xP alloys has been studied in modulation spectroscopy, between 10 and 300 K. Deviation from simple indirect absorption has been studied and shown to be consistant with a model which takes into account band structure enhancement of the absorption coefficient at alloy composition values where direct and indirect edges occur, at nearly the same energy. For the first time we observe structures of Δε₁ corresponding to band structure enhanced indirect transitions.     

Chirurgies de Dehn de pente ±1 sur certains nœuds dans lec 3-variétés

Sans résumé     

Accès à quelques gem-méthoxy hydroperoxydes stéroïdes

L'ozonolyse en méthanol permet d'accéder, en série stéroïde, à des méthoxy-hydroperoxydes géminés. Des 20-cétopregnanes ont ainsi fourni des méthoxy-hydroperoxydes en 20, par l'intermédiaire d'un dérivé 20-méthylénique, ou en 17, par l'intermédiaire d'un acétate énolique.     

Das Verhalten des Geschlechts bei Konstantenreduktionen algebraischer Funktionenkörper

Ohne ZusammenfassungInhaltliche Wiedergabe von [8], § 2.     

Routes to Functional Vesicle Membranes without Proteins

Fixation of reaction partners at appropriate distances from one another is a structural prerequisite for vectorial reactions and reaction sequences. In biological systems (e.g. the photosynthetically active thylakoid membrane or membrane receptors) the positions of the reaction centers are fixed by membrane-protein complexes, but little is known about the structure of these complexes. Ordered reactive systems in synthetic vesicle membranes were first obtained by employing amphiphiles with reactive head groups as building units, by regioselective incorporation of foreign molecules into the membrane, by alignment of bolaamphiphiles with two head groups of differing solubility or size, and by the formation of domains. Chiral superstructures have also been observed in membranes, and the first stereoselective reactions have been performed in vesicle membranes. The report concludes with a brief discussion of membranes constructed from non-amphiphilic building blocks and problems which still have to be solved.     

Measurement of enthalpic parameters using a differential calorimetric method: Application to in-Bi alloys

An attempt is made to develop a calorimetric method by taking full advantage of the differential possibilities offered by the Tian-Calvet calorimeter. This method is intended to measure the enthalpic parameter, defined as the limiting value (dilute solutions) of the derivative of the partial enthalpy of mixing with respect to the concentration, in liquid In-Bi alloys. The results, although rather scattered, exhibit a systematic discrepancy when compared with those obtained by the classical direct reaction calorimetry method with the same calorimeter. They are in better agreement with the values estimated from simple thermodynamic models.

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Zusammenfassung Es wurde der Versuch unternommen, ein kalorimetrisches Verfahren zu entwickeln, das die Vorteile der Differentiation beim Tian-Calvet-Kalorimeter voll ausnutzt. Mittels dieser Methode sollte unter Berücksichtigung der Konzentration an flüssigen In-Bi Legierungen ein Enthalpieparameter gemessen werden, der als Grenzwert (verdünnte Lösung) der Ableitung der partiellen Mischungsenthalpie definiert wurde. Die Ergebnisse zeigen trotz größerer Streuung eine systematische Abweichung von den Werten, die auf demselben Kalorimeter mit dem klassischen DRC-Verfahren erhalten wurden und befinden sich in besserer Übereinstimmung mit den Werten, die auf der Basis einfacher thermodynamischer Modelle geschätzt wurden.

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Electrochemical evidences of morphological transformation in ordered mesoporous titanium oxide thin films

We provide the first electrochemical evidence of permeability changes in continuous mesoporous TiO2 thin film electrodes induced by nanocrystallisation.     

45- and 70-base DNA supramolecular polymerizations on quartz crystal microbalance biosensor

Supramolecular polymerizations of 45- and 70- base DNAs on the surface of an in-situ time-resolved 27 MHz quartz crystal microbalance biosensor.     

Jagged Partitions

By jagged partitions we refer to an ordered collection of non-negative integers (n₁, n₂,..., n_m) with n_m≥ p for some positive integer p, further subject to some weakly decreasing conditions that prevent them for being genuine partitions. The case analyzed in greater detail here corresponds to p = 1 and the following conditions n_i≥ n_i+1−1 and n_i≥ n_i+2. A number of properties for the corresponding partition function are derived, including rather remarkable congruence relations. An interesting application of jagged partitions concerns the derivation of generating functions for enumerating partitions with special restrictions, a point that is illustrated with various examples. 2000 Mathematics Subject Classification: Primary—05A15, 05A17, 05A19     

Integrated Planning in a Steelworks: The Choice of Alternative Practices in Previous Processes to Augment Productivity at the Final Rolling Stage

The case study presented in this paper is an example in which the very different contingencies associated, on the one hand, with steel-making and, on the other hand, with cold rolling are considered together in seeking a maximum of profitability. In the works under investigation the steel-making area was a general bottleneck, while the cold mill was a bottleneck specific to the most profitable products, and the solution obtained actually involved a narrowing of the general bottleneck. The methods of calculation used in this study are not original. It is their synthesis leading to the technically important decision to create a new ingot size which deserves attention.