Implications of a light Higgs scalar

Phenomenological consequences of a light neutral Higgs scalar S (mass < 3.7 GeV) are explored in various two-Higgs-doublet models where some of the couplings are strongly enhanced. In one class of models the two-gluon decay mode is predominant, and decays into two muons are quite suppressed. A detailed analysis of the decay b → s + S is given. The consequences a light scalar for supersymmetric models are discussed.     

A simple solution to the strongCP-problem

We suggest soft breaking of Peccei-Quinn symmetry as a simple solution to the strongCP problem without the presence of the axion. In the context of theSU(2) _L ×U(1) model, it is shown how settingθ _tree=0 keeps θ calculable and, furthermore, extremely small: θ?10^?16. Unlike in the case of the axion the model is free from the cosmological domain wall problem. Possible extension of this idea to grand unification is discussed.     

Synthesis, characterization and cytotoxicity of surface amino-functionalized water-dispersible multi-walled carbon nanotubes

Surface functionalization of multi-walled carbon nanotubes (MWCNTs), with amino groups via chemical modification of carboxyl groups introduced on the nanotube surface, using O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (N-HATU) and N,N-diisopropylethylamine (DIEA) is reported. The N-HATU coupling agent provides faster reaction rate and the reaction occurs at lower temperature compared to amidation and acylation-amidation chemistry. The amines, 1,6-hexanediamine (HDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and 1,4-phenylenediamine (PDA) were used. The resulting materials were characterized with different techniques such as FTIR, XRD, elemental analysis, TGA, TEM, UV-vis spectroscopy and cyclic voltammetry. MWCNTs functionalized with PDA posses the best dispersibility and electron transfer properties in comparison to the others amines. Functionalized MWCNTs, at the concentrations between 1 and 50 μg ml⁻¹, were not cytotoxic for the fibroblast L929 cell line. However, the concentrations of MWCNTs higher of 10 μg ml⁻¹ reduced cell growth and this effect correlated positively with the degree of their uptake by L929 cells.     

Comparison of Fe-AlPILC and Fe-ZSM-5 catalysts used for degradation of methomyl

Catalytic performances of Fe-AlPILC (14 wt.% Fe) and Fe-ZSM-5 (5 wt.% Fe) catalysts are compared in the wet oxidative degradation of methomyl. Fe-ZSM-5 exhibits outstanding whereas Fe-AlPILC shows only mediocre activity. Positions of iron are analysed in the two catalysts by Mössbauer spectroscopy. Iron is in highly dispersed state in Fe-AlPILC whereas in the other case a hematite/ZSM-5 composite is formed. The catalytic activity is attributed to iron located and stabilized in ionic dispersion.     

Tetraaquabis(d‐camphor‐10‐sulfonato)calcium(II)

The structure of the title compound, [Ca(C₁₀H₁₅O₄S)₂(H₂O)₄], is the first example in which two d ‐camphor‐10‐sulfonate anions are coordinated to a metal ion, in this case with direct Ca—O bonding. The molecule has crystallographically imposed twofold symmetry with the Ca atom on the twofold axis. Hydrogen bonds are formed between the coordinated water molecules and the O atoms of the SO₃⁻ groups of adjacent molecules, leading to the formation of a two‐dimensional layered network. The compound displays sharp wavelength‐selective transparency in the UV–visible spectrum, offering the potential for application as an optical filter.     

Nonlinear magnetotransport in a two-dimensional electron system with anisotropic mobility

Nonlinear magnetotransport of two-dimensional electrons in modulation-doped GaAs/AlAs heterostructures with anisotropic mobility is investigated. The mobility attains its maximum and minimum values in the $\left[ {1\bar 10} \right]$ and [110] directions, respectively. It is found that, upon an increase in the direct electrical current I _dc though Hall bars oriented along the [110] direction, the transition of the two-dimensional system to the state with differential resistance r _xx ≈ 0 in a magnetic field occurs at a lower value of I _dc and is accompanied by a more pronounced “plunge” into the region of negative r _xx values as compared to bars oriented along the $\left[ {1\bar 10} \right]$ direction. The results are explained by the impact of mobility on the spectral diffusion of nonequilibrium charge carriers.     

Simple cubic packing of gold nanoparticles through rational design of their dendrimeric corona

The first simple-cubic liquid crystal was obtained by coating monodisperse Au nanoparticles (NPs) with a thick corona of amino-substituted organic dendrons. This unusual structure was determined by grazing-incidence diffraction and electron density reconstruction and explained by analyzing the radial density profile of the corona. Another novel structure is proposed for the phase preceding the cubic one: a hexagonal superlattice composed of alternating dense and sparse strings of Au NPs.