Benchmark scenarios for the NMSSM

We discuss constrained and semi--constrained versions of the next--to--minimal supersymmetric extension of the Standard Model (NMSSM) in which a singlet Higgs superfield is added to the two doublet superfields that are present in the minimal extension (MSSM). This leads to a richer Higgs and neutralino spectrum and allows for many interesting phenomena that are not present in the MSSM. In particular, light Higgs particles are still allowed by current constraints and could appear as decay products of the heavier Higgs states, rendering their search rather difficult at the LHC. We propose benchmark scenarios which address the new phenomenological features, consistent with present constraints from colliders and with the dark matter relic density, and with (semi--)universal soft terms at the GUT scale. We present the corresponding spectra for the Higgs particles, their couplings to gauge bosons and fermions and their most important decay branching ratios. A brief survey of the search strategies for these states at the LHC is given.

Boson-fermion duality in SU(m vertical bar n) supersymmetric Haldane-Shastry spin chain

By using the Y(gl(m|n)) super Yangian symmetry of the SU(m|n) supersymmetric Haldane-Shastry spin chain, we show that the partition function of this model satisfies a duality relation under the exchange of bosonic and fermionic spin degrees of freedom. As a byproduct of this study of the duality relation, we find a novel combinatorial formula for the super Schur polynomials associated with some irreducible representations of the Y(gl(m|n)) Yangian algebra. Finally, we reveal an intimate connection between the global SU(m|n) symmetry of a spin chain and the boson-fermion duality relation. (C) 2007 Elsevier B.V. All rights reserved.

Low energy properties of the SU(m|n) supersymmetric Haldane–Shastry spin chain

The ground state and low energy excitations of the SU(m|n) supersymmetric Haldane–Shastry spin chain are analyzed. In the thermodynamic limit, it is found that the ground state degeneracy is finite only for the SU(m|0) and SU(m|1) spin chains, while the dispersion relation for the low energy and low momentum excitations is linear for all values of m and n. We show that the low energy excitations of the SU(m|1) spin chain are described by a conformal field theory of m non-interacting Dirac fermions which have only positive energies; the central charge of this theory is m/2. Finally, for ngreater-or-equal, slanted1, the partition functions of the SU(m|n) Haldane–Shastry spin chain and the SU(m|n) Polychronakos spin chain are shown to be related in a simple way in the thermodynamic limit at low temperatures.

From the LHC to future colliders

Discoveries at the LHC will soon set the physics agenda for future colliders. This report of a CERN Theory Institute includes the summaries of Working Groups that reviewed the physics goals and prospects of LHC running with 10 to 300 fb(-1) of integrated luminosity, of the proposed sLHC luminosity upgrade, of the ILC, of CLIC, of the LHeC and of a muon collider. The four Working Groups considered possible scenarios for the first 10 fb(-1) of data at the LHC in which (i) a state with properties that are compatible with a Higgs boson is discovered, (ii) no such state is discovered either because the Higgs properties are such that it is difficult to detect or because no Higgs boson exists, (iii) a missing-energy signal beyond the Standard Model is discovered as in some supersymmetric models, and (iv) some other exotic signature of new physics is discovered. In the contexts of these scenarios, the Working Groups reviewed the capabilities of the future colliders to study in more detail whatever new physics may be discovered by the LHC. Their reports provide the particle physics community with some tools for reviewing the scientific priorities for future colliders after the LHC produces its first harvest of new physics from multi-TeV collisions.

Self-Assembly of Biopolymers on Colloidal Particles via Hydrogen Bonding

Fabrication of multilayer microcapsules via layer-by-layer approach through hydrogen bonding has attracted enormous interest due to its strong response to pH. In this communication, we have prepared hydrogen-bonded multilayer microcapsule without using any cross-linking agent by using DNA base pair (adenine and thymine) modified biocompatible polymers. The growth of the self-assembly on colloidal (melamine formaldehyde: MF) particles has been monitored with zeta potential measurement. The capsules were obtained on dissolution of MF particles at 0.1N HCl. The capsules were characterized with scanning electron microscopy. Moreover, we have observed the salt induced microscopic change in self-assembly of this system on the surface of colloidal particles.

Electrochemical insertion of Sr2+ ions onto nano delta-MnO2 particles

Manganese dioxide is known to be an important electroactive material for supercapacitors. Generally, delta-MnO2 is subjected to electrochemical characterization studies in aqueous electrolytes of Na2SO4. It exhibits capacitance behaviour in the potential range between 0 and 1.0 V vs. SCE (saturated calomel electrode). In the present study, it is shown that delta-MnO2 exhibits capacitance behaviour in Sr(NO3)(2) electrolytes also. The suitable potential range in this electrolyte is also found to be 0-1.0 V. Specific capacitancemeasured in Sr(NO3)(2) electrolyte is 192 F g(-1). X-ray photoelectron spectroscopy data confirm that Sr2+ ions get inserted onto delta-MnO2 anoparticles. (C) 2010 Elsevier B.V. All rights reserved.

Low-temperature polymer precursor-based synthesis of nanocrystalline particles of lanthanum calcium manganese oxide (La0.67Ca0.33MnO3) with enhanced ferromagnetic transition temperature

We report a simple modified polymeric precursor route for the synthesis of highly crystalline and homogenous nanoparticles of lanthanum calcium manganese oxide (LCMO). The LCMO phase formation was studied by thermal analysis, x-ray powder diffraction, and infrared spectroscopy at different stages of heating. These nanocrystallites (average particle size of 30 nm) possess ferromagnetic-paramagnetic transition temperature (T-c) of 300 K, nearly 50 K higher than that of a single crystal. The Rietveld analysis of the powder x-ray diffraction data of the nanopowders reveals significant lattice contraction and reduction in unit cell anisotropy-these structural changes are correlated to the enhancement in T-c.

Deformation and friction of MoS2 particles in liquid suspensions used to lubricate sliding contact

Tribology of a well known solid lubricant molybdenum disulphide is studied here in water and oil medium, over a large range of contact dimensions. Lateral force microscopy is used to identify the deformation modes, intra-crystalline slip, plastic grooving, fragmentation and fracture, of single particles The medium and agglomeration were found to dictate the deformation mode Steel on steel tribology lubricated by suspensions of these particles in liquid media was conducted over a range of contact pressure and sliding velocity. A scrutiny of the frictional data with the aid of Raman spectroscopy to identify the transfer film, suggested that the particle size, as it is at contact, is an important tribological parameter Ultrasonication of the suspension and dispersion of the particle by surfactants were used to control the apriori particle size fed into the suspension.Correspondence of friction data of the gently sonicated suspension with that of the ultrasonicated suspension with dispersants indicated the importance of liquid ingestion by these particles as it controls their mode of deformation and consequent tribology. (C) 2010 Elsevier B V All rights reserved.

Preparation and characterization of silane-stabilized, highly uniform, nanobimetallic Pt-Pd particles in solid and liquid matrixes

Highly uniform, stable nanobimetallic dispersions are prepared in a single si ep in the form of sols, gels, and monoliths, using organically modified silicates as the matrix and the stabilizer. The Pt-Pd bimetallic dispersions are characterized by W-vis, TEM, SEM, and XRD measurements. The evolution of silicate was followed by IR spectroscopy. XPS and CO adsorption studies reveal that the structure of the particles consists of a palladium core and a platinum shell. Electrocatalysis of ascorbic acid oxidation has been demonstrated using thin films of silicate containing the nanobimetal particles on a glassy carbon electrode.

Oxidative activities in mitochondria-like particles from Setaria digitata, a filarial parasite

The oxidative metabolic potential of Setaria digitata, a filarial parasite found in the intraperitoneal cavity of cattle, was investigated. These worms showed active wriggling movements which were not affected by respiratory poisons such as cyanide, rotenone and malonate. They also possessed cyanide-insensitive and glucose-independent oxygen consumption pathways. By differential centrifugation of sucrose homogenates, a fraction containing mitochondria-like particles was obtained in which the activity of the marker enzyme, succinate dehydrogenase, was recovered. This fraction catalysed succinate- and NADH-dependent reduction of both cytochrome c and dyes. Oxygen uptake found with succinate, NADH and ascorbate as substrates was not sensitive to cyanide. Cytochromes could not be detected in either this fraction or homogenates of the worms. H2O2 generation with a number of substrates and lipid peroxidation by measuring malondialdehyde formed as well as by accompanying oxygen uptake were demonstrated in the mitochondria-like particles. A lipid quinone, possibly with a short side chain and related to ubiquinone, was detected in the worms. The results suggested the existence of two cyanide-insensitive oxygen-consuming reactions in Setaria: one respiratory substrate-independent lipid peroxidation, and a second substrate-dependent reaction that requires an auto-oxidizable quinone but not a cytochrome system.

Superconformal transformations of theN=4 supersymmetric Yang-Mills theory

We obtain the superconformal transformation laws of theN=4 supersymmetric Yang-Mills theory and explicitly demonstrate the closure of the algebra.

Antimicrobial activity of highly stable silver nano particles embedded in agar-agar matrix as a thin film

Highly stable silver nanoparticles (Ag NPs) in agar-agar (Ag/agar) as inorganic-organic hybrid were obtained as free-standing film by in situ reduction of silver nitrate by ethanol. The antimicrobial activity of Ag/agar film on Escherichia coli (E. coil), Staphylococcus aureus (S. aureus), and Candida albicans (C albicans) was evaluated in a nutrient broth and also in saline solution. In particular, films were repeatedly tested for antimicrobial activity after recycling. UV-vis absorption and TEM studies were carried out on films at different stages and morphological studies on microbes were carried out by SEM. Results showed spherical Ag NPs of size 15-25 nm, having sharp surface plasmon resonance (SPR) band. The antimicrobial activity of Ag/agar film was found to be in the order, C. albicans > E. coil > S. aureus, and antimicrobial activity against C. albicans was almost maintained even after the third cycle. Whereas, in case of E. coil and S. aureus there was a sharp decline in antimicrobial activity after the second cycle. Agglomeration of Ag NPs in Ag/agar film on exposure to microbes was observed by TEM studies. Cytotoxic experiments carried out on HeLa cells showed a threshold Ag NPs concentration of 60 mu g/mL, much higher than the minimum inhibition concentration of Ag NPs (25.8 mu g/mL) for E. coli. The mechanical strength of the film determined by nanoindentation technique showed almost retention of the strength even after repeated cycle. (C) 2010 Elsevier Ltd. All rights reserved.

Trajectories of charged particles in the static Ernst space-time

The authors study the trajectories of charged particles in Ernst's space-time representing a static black hole immersed in a magnetic field. They find bound orbits always exist for realistic magnetic field strengths. A similar investigation is carried out for the case of Melvin's magnetic universe and for a corresponding test field superposed on a flat space-time.