Electronic structure of red amorphous phosphorus studied by X-ray spectroscopy

A SXS study of occupied and unoccupied 3p states of semiconducting red amorphous phosphorus is presented. It is shown that in the upper part of the valence band, partially hybridized sp spates are present among p pure states, whereas the bottom of the valence band is almost s-like. The results are discussed in connection with theoretical data available for black phosphorus.     

Preorganization in highly enantioselective diaza-Cope rearrangement reaction

Crystal structure and activation entropy data indicate that H-bond directed diaza-Cope rearrangement of chiral diimines takes place with a high degree of preorganization. CD spectroscopy and HPLC data show that there is inversion of stereochemistry for the reaction with excellent enantioselectivity.     

Multitiered Supply Chain Networks: Multicriteria Decision—Making Under Uncertainty

In this paper, we present a supply chain network model with multiple tiers of decision-makers, consisting, respectively, of manufacturers, distributors, and retailers, who can compete within a tier but may cooperate between tiers. We consider multicriteria decision-making for both the manufacturers and the distributors whereas the retailers are subject to decision-making under uncertainty since the demands associated with the product are random. We derive the optimality conditions for the decision-makers, establish the equilibrium conditions, and derive the variational inequality formulation. We then utilize the variational inequality formulation to provide both qualitative properties of the equilibrium product shipment, service level, and price pattern and to propose a computational procedure, along with convergence results. This is the first supply chain network model to capture both multicriteria decision-making and decision-making under uncertainty in an integrated equilibrium framework.     

Structural studies in main group chemistry III. Tin-119m mössbauer investigation of some tin-nitrogen bonded compounds

The tin-119m Mössbauer data are presented for several classes of organotin- nitrogen bonded compounds, including N-stannylamines, -imines, -amides, and -carbamates. Thc structures of the N,O-bis(trialkylstannyl)carbamates are discussed. Those derivatives possessing the Sn-NR-C(O)X group are intermolecularly associated via carbonyl→tin coordination, the strength of the coordination varying with X in the manner H ≈ OSnR₃ > OR.     

Optimal stopping in terminating one-sided processes with unbounded reward functions

Summary We examine the problem of optimal stopping in terminating one-sided processes. The Markov and the semi-Markov cases are considered. Applications to reliability theory are given.

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Zusammenfassung Thema dieses Beitrages ist die Bestimmung eines optimalen Stoppzeitpunktes für zwei spezielle Markov-Prozesse sowie die Betrachtung von zwei zugehörigen Anwendungen in der Zuverlässigkeitstheorie.

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On leave to the J.L. Kellogg Graduate School of Management, Northwestern University, Evanston, Illinois 60201, USA.     

Efficiency of electrostatic air moving devices

An ion-driven gas flow is characterized by the breakdown of a gas into ions in the presence of a high electric potential. Ions flow due to the potential gradient. Mass transfer motivates bulk airflow. In the current study, an ionic air moving device was constructed using needles as ion sources, and a ring as collector. Airflow and efficiency were evaluated at various ring widths and with various numbers of ionization sites. Efficiency was seen to increase with ring width if airflow and distance was held constant and also increased with the number of ionization sites when airflow was held constant.     

The hilbert function and the minimal free resolution of some gorenstein ideals of codimension 4

We give a construction for Gorenstein ideals of codimension 4 which we believe have maximal graded Betti numbers for their Hilbert function.