A point-charge representation of frost-model wave functions

A point-charge representation of Frost-model wave functions is derived from a symmetry-adapted perturbation theoretic expansion. The new point-charge model is simpler than those suggested previously yet gives good estimates of first-order molecular properties. The treatment can easily be extended to deal with second-order properties and, when this is done, formulae similar to those of the Drude theory are obtained. Using these formulae, theoretical expressions for the refractive indices of methane, ethane and water are computed and are in reasonable accord with experiment for the two hydrocarbons but less satisfactory for water.     

Search for R-parity violating supersymmetry in two-muon and four-jet topologies

We present results of a search for R-parity-violating decay of the neutralino chi;01, taken as the lightest supersymmetric particle, to a muon and two jets. The decay proceeds through a lepton-number violating coupling lambda(')(2jk) (j=1,2; k=1,2,3), with R-parity conservation in all other production and decay processes. In the absence of candidate events from 77.5+/-3.9 pb(-1) of data collected by the D0 experiment at the Fermilab Tevatron in pp collisions at sqrt[s]=1.8 TeV, and with an expected background of 0.18+/-0.03+/-0.02 events, we set limits on squark and gluino masses within the framework of the minimal low-energy supergravity-supersymmetry model.     

Search for large extra dimensions in dielectron and diphoton production

We report a search for effects of large extra spatial dimensions in pp collisions at a center-of-mass energy of 1.8 TeV with the D0 detector, using events containing a pair of electrons or photons. The data are in good agreement with the expected background and do not exhibit evidence for large extra dimensions. We set the most restrictive lower limits to date, at the 95% C.L. on the effective Planck scale between 1.0 and 1.4 TeV for several formalisms and numbers of extra dimensions.     

Inclusive jet production in pp(macro) collisions

We report a new measurement of the pseudorapidity (eta) and transverse-energy ( E(T)) dependence of the inclusive jet production cross section in pp(macro) collisions at square root of s = 1.8 TeV using 95 pb(-1) of data collected with the D0 detector at the Fermilab Tevatron. The differential cross section d(2)sigma/(dE(T)d eta) is presented up to eta = 3, significantly extending previous measurements. The results are in good overall agreement with next-to-leading order predictions from QCD and indicate a preference for certain parton distribution functions.     

Predicting total reaction cross sections for nucleon-nucleus scattering

Nucleon total reaction and neutron total cross sections to 300 MeV for 12C and 208Pb, and for 65 MeV scattering spanning the mass range, are predicted using coordinate space optical potentials formed by full folding of effective nucleon-nucleon interactions with realistic nuclear ground state densities. Good to excellent agreement is found with existing data.     

Novel chimeric scaffolds to extend the exploration of receptor space: hybrid beta-D-glucose-benzoheterodiazepine structures for broad screening. Effect of amide alkylation on the course of cyclization reactions

New molecular platforms which are hybrids of two scaffolds-namely, beta-d-glucose and benzodiazepine, each able to bind several proteins-were designed, synthesized and functionalized to serve as probes for broad biological screening. Herein, we describe the syntheses and chemical properties of these novel chimeric scaffolds. Attempted cyclization of the functionalized analogues (-)-96 and (-)-97 afforded the corresponding dimers (-)-98 and (-)-99, respectively, under a variety of reaction conditions, even at concentrations of only 0.001 N. Consideration of factors affecting the conformation of amide bonds and their effects on cyclization reactions led us to alkylate the amide bond. As expected, the cyclization of the N-methyl derivative (-)-110 afforded exclusively the unimolecular cyclization product (+)-111. These compounds are only now undergoing broad screening and represent therefore at present a "prospecting library."     

Spongistatin synthetic studies. evolution of a scalable synthesis for the EF fragment of (+)-Spongistatin 1 exploiting a Petasis-Ferrier union/rearrangement tactic

[structure: see text] An efficient, stereocontrolled, and scalable second-generation synthesis of (+)-3, an advanced EF subtarget for the total synthesis of (+)-spongistatin 1, has been achieved. Highlights of the strategy include preparation of the F-ring pyran via a Petasis-Ferrier union/rearrangement sequence and installation of the chlorodiene side chain employing a cyanohydrin alkylation. The longest linear sequence, 26 steps, proceeds in 8.3% overall yield.     

Structures and vibrational frequencies of the A′and A″ states of the CH3O radical

Analytic gradient and second-derivative methods are used to obtain the equilibrium geometries and vibrational frequencies of the methoxy radical CH₃O. The analytic methods are found to be superior in both speed and accuracy to numerical techniques which for this molecule are qualitatively and quantitatively incorrect. The A′ state is found to be a minimum on the potential-energy surface, whereas the A″ state is a saddle point.