Chemisorption on supported-metal catalysts

A Gree-function formalism is developed to describe the electronic and chemisorption properties of a supported-metal composite substrate. Within the framework of the tight-binding approximation, the metal catalyst is represented by a finite chain of d-orbitals, while the semi-infinite semiconductor support is characterized by a linear chain of alternating s- and p-orbitals. The Anderson-Newns model is used to calculate the chemisorption energy and adatom charge transfer for hydrogen chemisorption on the Ni/ZnO composite system.     

Algorithms for generalized halfspace range searching and other intersection searching problems

In a generalized intersection searching problem, a set S of colored geometric objects is to be preprocessed so that, given a query object q, the distinct colors of the objects of S that are intersected by q can be reported or counted efficiently. These problems generalize the well-studied standard intersection searching problems and have many applications. Unfortunately, the solutions known for the standard problems do not yield efficient solutions to the generalized problems. Recently, efficient solutions have been given for generalized problems where the input and query objects are iso-oriented (i.e., axes-parallel) or where the color classes satisfy additional properties (e.g., connectedness). In this paper, efficient algorithms are given for several generalized problems involving objects that are not necessarily iso-oriented. These problems include: generalized halfspace range searching in , for any fixed d ≥ 2, and segment intersection searching, triangle stabbing, and triangle range searching in for certain classes of line segments and triangles. The techniques used include: computing suitable sparse representations of the input, persistent data structures, and filtering search.     

Entrance laws for Feller diffusions on (0, ∞) and Doob's h-path transformation

We consider the problem of constructing entrance laws for Feller diffusions on the state space (0, ∞). Our method, based on Feller-McKean theory of one-dimensional diffusions, gives an analytic expression for the entrance density in terms of transition density. Moreover, the entrance density is the density of the first passage time to the left boundary {0}. Also, the entrance density is related to the transition density via Doob's h-path transformation.     

Angular forces in the lattice dynamics of diamond crystal lattices

The lattice dynamics of the diamond lattice has been investigated using a model in which the interatomic forces include, in addition to central forces, the angular forces of the type employed by de Launay and Clark, Gazis and Wallis. The 2 models have been applied to silicon and germanium to investigate the phonon dispersion curves in the three symmetry directions of the Brillioun zone. The results are found to be qualitatively in good agreement with experiments.     

A simple extrusion method for the synthesis of aligned silica nanowires using the template of a rigid surfactant mesophase

Long range alignment of silica nanowires has been accomplished by extrusion of a novel surfactant mesophase prior to silica synthesis.     

The reaction of chromate with diphenylcarbazide. I

The mechanism of the classical colour reaction between chromate and carbazide has been studied in solution from various physicochcmical points of view. It has been established from spectral identity that the same red-violet compound is produced in the 3 different reaction systems, chromate-carbazidc, chromate-carbazone and chromous-carbazonc. This leads to the conclusion that tlie chromate-carbazidc reaction is a composite one involving preliminary oxidation followed subsequently by complex formation. Moreover, the actual constituents involved in the reaction have been identified as Cr⁺² on the one hand and carbazone on the other, giving rise to an intensely coloured inner complex compound. The inner complex nature of the coloured product was gauged independently from migration studies and from extraction of the coloured compound by non-polar solvents.     

Search for ZH → l+ l- bb production in 4.2 fb(-1) of pp collisions at sqrt[s] =1 .96 TeV

We present a search for the standard model Higgs boson produced in association with a Z boson in 4.2 fb(-1) of pp collisions, collected with the D0 detector at the Fermilab Tevatron at sqrt[s] =1 .96 TeV. Selected events contain one reconstructed Z → e+ e- or Z → μ+ μ- candidate and at least two jets, including at least one b-tagged jet. In the absence of an excess over the background expected from other standard model processes, limits on the ZH cross section multiplied by the branching ratios are set. The limit at M(H) = 115 GeV is a factor of 5.9 larger than the standard model prediction.