Rm Values, retention times and π values of a series of potentially mutagenic nitroimidazo[2,1-b]thiazoles

The R_m values and retention times of a series of nitroimidazo[2,1-b]thiazoles were obtained by means of thin-layer and high-performance liquid chromatography, respectively. Extrapolated R_m and log k′ values were correlated in a statistically significant way with π values calculated according to the literature.     

Beryllium(II) complexes of the Kläui tripodal ligand cyclopentadienyltris(diethylphosphito-p)cobaltate(-)

The interactions of the beryllium(II) ion with the cyclopentadienyltris(diethylphosphito-P)cobaltate monoanion, L(-), have been investigated, in aqueous solution, by synthetic methods, potentiometry, ESMS, and (1)H, (31)P, and (9)Be NMR spectroscopy. L(-) has been found able to displace either two or three water molecules in the beryllium(II) coordination sphere, to form mononuclear, dinuclear, and trinuclear derivatives, in which the metal ion is pseudotetrahedrally coordinated. The species [BeL(H(2)O)](+) and [Be(2)L(2)(mu-OH)](+) have been identified in solution while complexes of formula BeL(2) and [Be(3)L(4)](ClO(4))(2) have been isolated as solid materials. The species [BeL(OPPh(2))](+), closely related to [BeL(H(2)O)](+), has been characterized in acetone solution and isolated as tetraphenylborate salt. The structure of the unusual trimeric complex [Be(3)L(4)](2+) has been elucidated by an unprecedented 2D (9)Be-(31)P NMR correlation spectrum showing the presence of a single central beryllium nucleus and two equivalent terminal beryllium nuclei. The three beryllium centers are held together by four cobaltate ligands, which display two different bonding modes: two ligands are terminally linked with all the three oxygen donors to one terminal beryllium, and the other two bridge two metal centers, sharing the oxygen donors between central and terminal beryllium atoms.     

Dioxomolybdenum(VI) Complexes with New Enantiomerically Pure Amino Diol Ligands

(R)-Phenylglycinol is shown to be an efficient building block for the synthesis of chiral amino diols in pure diastereomeric form by epoxide ring-opening reactions. The reaction with rac-trans-stilbene oxide gives [HOCH(2)-(R)-PhCH]NH[(S)-PhCH-(R)-PhCHOH] [2(R)-3(R)-4(S)-HNO(2)H(2)] in 32% yield, which can be methylated at nitrogen to give enantiomerically pure [HOCH(2)-(R)-PhCH]NCH(3)[(S)-PhCH-(R)-PhCHOH] [2(R)-3(R)-4(S)-MeNO(2)H(2)]. These amino diol ligands have been used to prepare chiral dioxomolybdenyl complexes of the formula N(R)-2(R)-3(R)-4(S)-(HNO(2))MoO(2) (1) and N(R)-2(R)-3(R)-4(S)-(MeNO(2))MoO(2) (2). The absolute configuration at each stereocenter in the Mo(VI) complexes has been established by (1)H NOESY spectroscopy. The configuration determined for 1 has been confirmed by an X-ray analysis. Crystal data: orthorhombic P2(1)2(1)2(1), a =7.620(3), b = 13.589(2), c = 20.339(3) ?, Z = 4, R = 0.0336. The structure consists of a polymeric chain of N(R)-2(R)-3(R)-4(S)-(HNO(2))MoO(2) molecules connected through unsymmetrical Mo=O --> Mo bridges. Each metal center is coordinated in a distorted octahedral geometry by a cis dioxo unit and by two trans alkoxo atoms. The coordination polyhedron is completed by a nitrogen atom and by a bridging oxo oxygen atom from an adjacent molecule. Compound 2 catalyzes the oxidation of PPh(3) to OPPh(3) by DMSO through a mechanism that involves the intermediacy of a Mo(IV) species.     

A multi-moment vortex method for 2D viscous fluids

In this paper we introduce simplified, exact, combinatorial formulas that arise in the vortex interaction model found in [33]. These combinatorial formulas allow for the efficient implementation and development of a new multi-moment vortex method (MMVM) using a Hermite expansion to simulate 2D vorticity. The method naturally allows the particles to deform and become highly anisotropic as they evolve without the added cost of computing the non-local Biot–Savart integral. We present three examples using MMVM. We first focus our attention on the implementation of a single particle, large number of Hermite moments case, in the context of quadrupole perturbations of the Lamb–Oseen vortex. At smaller perturbation values, we show the method captures the shear diffusion mechanism and the rapid relaxation (on Re^1/3 time scale) to an axisymmetric state. We then present two more examples of the full multi-moment vortex method and discuss the results in the context of classic vortex methods. We perform numerical tests of convergence of the single particle method and show that at least in simple cases the method exhibits the exponential convergence typical of spectral methods. Lastly, we numerically investigate the spatial accuracy improvement from the inclusion of higher Hermite moments in the full MMVM.     

Geographical influences of an emerging network of gang rivalries

We propose an agent-based model to simulate the creation of street gang rivalries. The movement dynamics of agents are coupled to an evolving network of gang rivalries, which is determined by previous interactions among agents in the system. Basic gang data, geographic information, and behavioral dynamics suggested by the criminology literature are integrated into the model. The major highways, rivers, and the locations of gangs’ centers of activity influence the agents’ motion. We use a policing division of the Los Angeles Police Department as a case study to test our model. We apply common metrics from graph theory to analyze our model, comparing networks produced by our simulations and an instance of a Geographical Threshold Graph to the existing network from the criminology literature.     

Search for new heavy particles in the WZ0 final state in pp collisions at square root[s] = 1.8 TeV

We present the first general search for new heavy particles, X, which decay via X --> WZ0 --> e(nu)+jj as a function of M(X) and Gamma(X) in pp collisions at square root[s] = 1.8 TeV. No evidence is found for production of X in 110 pb(-1) of data collected by the Collider Detector at Fermilab. General cross section limits are set at the 95% C.L. as a function of mass and width of the new particle. The results are further interpreted as mass limits on the production of new heavy charged vector bosons which decay via W' --> WZ0 in an extended gauge model as a function of the width, Gamma(W'), and mixing factor between the W' and the standard model W bosons.