Constraining new physics with B→K ∗ μ + μ − in the early LHC era

We investigate the observables available in the angular distribution of B→K ^? μ ⁺ μ ^? to identify those suitable for measurements in the first few years of LHC data taking. There are three observables that may be extracted by counting signal events as a function of one or two decay angles and correspond to large features of the full angular distribution in the Standard Model: A _FB, F _L, and S ₅. Two of these are well known in the experimental community; however, we show that measuring S ₅ adds complementary sensitivity to physics beyond the Standard model. Like A _FB, it features a zero-crossing point with reduced hadronic uncertainties at leading order and in the large recoil limit. Due to the high gradient of S ₅ at this point, we find it would be possible for LHCb to measure it to high precision. Current experimental model independent constraints on parameter space are presented and predictions made for the values of the A _FB and S ₅ zero-crossing points. The relative impact of early LHCb measurements of A _FB, F _L, and S ₅ is assessed. These issues are explored with a new model of the decay that can be used with standard simulation tools such as EvtGen.     

Hydrolase-mediated resolution of the hemiacetal in 2-chromanols: The impact of remote substitution

Hydrolase-catalysed dynamic kinetic resolutions of chroman-2-ol and 3-methyl chroman-2-ol can be effected with up to 88% conversion and 92% ee through the use of organic solvents. Extension to the resolution of the tolterodine precursor 1 proved more challenging. The presence of the remote phenyl substituent had a significant impact on the resolution and it was not possible to achieve high enantioselectivity together with efficient conversion from the focussed panel of enzymes screened.     

Self assembled monolayers on silicon for molecular electronics

We present an overview of various aspects of the self-assembly of organic monolayers on silicon substrates for molecular electronics applications. Different chemical strategies employed for grafting the self-assembled monolayers (SAMs) of alkanes having different chain lengths on native oxide of Si or on bare Si have been reviewed. The utility of different characterization techniques in determination of the thickness, molecular ordering and orientation, surface coverage, growth kinetics and chemical composition of the SAMs has been discussed by choosing appropriate examples. The metal counterelectrodes are an integral part of SAMs for measuring their electrical properties as well as using them for molecular electronic devices. A brief discussion on the variety of options available for the deposition of metal counterelectrodes, that is, soft metal contacts, vapor deposition and soft lithography, has been presented. Various theoretical models, namely, tunneling (direct and Fowler-Nordheim), thermionic emission, Poole-Frenkel emission and hopping conduction, used for explaining the electronic transport in dielectric SAMs have been outlined and, some experimental data on alkane SAMs have been analyzed using these models. It has been found that short alkyl chains show excellent agreement with tunneling models; while more experimental data on long alkyl chains are required to understand their transport mechanism(s). Finally, the concepts and realization of various molecular electronic components, that is, diodes, resonant tunnel diodes, memories and transistors, based on appropriate architecture of SAMs comprising of alkyl chains (sigma- molecule) and conjugated molecules (pi-molecule) have been presented.     

Preparation, structure, and properties of new ternary rhenium arsenides and phosphides with metal-metal bondings

The M₂Re₅As₁₂ arsenides (M = Fe, Co, Ni) and the Co₂Re₅P₁₂ phosphide were synthesized. The unit cell is orthorhombic with space group Pnnm and contains two formula units. The X-ray structure of Ni₂Re₅As₁₂ was studied from three-dimensional single-crystal counter data and was refined down to R = 0.048 for 637 independent reflections. The structure can be described as built up from two different structural domains; the first one is the marcasite type and shows As---As pairs and linear Re---Re chains, the second one consists of Re₄ clusters with common edges linked to terminal Ni atoms. A nearly temperature-independent paramagnetism and p-type metallic conduction were observed from the magnetic and electrical measurements. Also observed in this new family of compounds were the resistivities along and perpendicular to the c axis and their anisotropic behavior.     

Multielemental speciation of As, Se, Sb and Te by HPLC-ICP-MS

An anion exchange HPLC-ICP-MS procedure allowing the simultaneous multielemental speciation analysis of arsenic, selenium, antimony and tellurium has been developed. Four arsenic species (As^III, As^V, monomethylarsonic acid and dimethylarsinic acid), two selenium species (Se^IV and Se^VI) may be determined in a single run as well as one antimony (Sb^V) and one tellurium species (Te^VI). Alternatively Sb and/or Te may be used as internal standards for As and Se speciation studies. Optimisation of ICP-MS conditions led to satisfactory relative (0.01 (Sb^V) to 1.8 (Se^VI) ng ml⁻¹) and absolute detection limits (1–180 pg). Reproducibility ranged from 3.1 to 5.6% and the linearity was verified in the 0–200 ng ml⁻¹ range.     

Multielemental speciation of As, Se, Sb and Te by HPLC-ICP-MS

An anion exchange HPLC-ICP-MS procedure allowing the simultaneous multielemental speciation analysis of arsenic, selenium, antimony and tellurium has been developed. Four arsenic species (As^III, As^V, monomethylarsonic acid and dimethylarsinic acid), two selenium species (Se^IV and Se^VI) may be determined in a single run as well as one antimony (Sb^V) and one tellurium species (Te^VI). Alternatively Sb and/or Te may be used as internal standards for As and Se speciation studies. Optimisation of ICP-MS conditions led to satisfactory relative (0.01 (Sb^V) to 1.8 (Se^VI) ng ml⁻¹) and absolute detection limits (1–180 pg). Reproducibility ranged from 3.1 to 5.6% and the linearity was verified in the 0–200 ng ml⁻¹ range.     

Speciation of arsenic and selenium compounds by HPLC hyphenated to specific detectors: a review of the main separation techniques

This review deals with liquid phase separation of major arsenic and selenium species followed by element specific detection. It concerns papers published since 1980 and describing only currently used methods that were or could be applied to As and Se speciation in environmental matrices. Methods performances are compared on the basis of efficiency, rapidity, absolute and concentration detection limits and applicability to real world environmental samples.     

Polymerisation stereoelective en phase homogene du methyl-2 thiiranne amorcee par des semences optiquement actives

Optically active seeds have been prepared by polymerization of the laevorotatory enantiomer of 2-methylthiirane with cadmium thiolate; they have been used for the polymerization of the racemic monomer, which is stereoelective. These results are explained by the formation of two types of chiral sites in unequal numbers, each type of site choosing only one enantiomer.     

Experimental and numerical POD study of the Coanda effect used to reduce self-sustained tones

The two-dimensional flow along an inclined plate may be detached or reattached to the plate by Coanda effect. Experimentally, we explore the influence of the inclination angle and of the Reynolds number on the attachment and detachment phenomena, and on the hysteresis loop. A proper orthogonal decomposition (POD) of the flow is applied to a LES simulation resulting data. A low-dimensional dynamical model is obtained using by Galerkin projection of the Navier–Stokes equations upon the POD basis functions. We show that this model represents qualitatively the characteristics of the flow.