Charged Higgs boson in the economical 3-3-1 model

The SU(3) _C ⊗ SU(3) _L ⊗ U(1) _X gauge model with two Higgs triplets (the economical 3-3-1 model) is presented. The minimal Higgs potential is considered in detail, and new Higgs bosons with the mass proportional to the bilepton mass are predicted. In the effective approximation, the charged Higgs bosons H ₂ ^± are scalar bileptons, while the neutral scalar bosons H ⁰ and H ₁ ⁰ do not carry a lepton number. The couplings of the charged Higgs bosons to leptons and quarks are given. We show that Yukawa couplings of H ₂ ^± to ordinary leptons and quarks are lepton-number violating. The pair production of H ₂ ^± at high-energy e ⁺ e ⁻ colliders with the polarization of the e ⁺, e ⁻ beams is studied in detail. A numerical evaluation shows that, if the Higgs mass is not too heavy, then the reaction can give an observable cross section in future colliders at a high degree of polarization. The reaction e ⁺ e ⁻ → H ₂ ^± W ^∓ is also examined. We show that the production cross sections of H ₂ ^± W ^∓ are very small, much below the pair production of H ₂ ^± , and, therefore, the associated production of H ₂ ^± and W ^∓ is, in general, not expected to lead to easily observable signals in the e ⁺ e ⁻ annihilation. The text was submitted by the authors in English.     

Enhancement of the Photoresponse in Organic Field‐Effect Transistors by Incorporating Thin DNA Layers

A mechanistic study of the DNA interfacial layer that enhances the photoresponse in n‐type field‐effect transistors (FET) and lateral photoconductors using a solution‐processed fullerene derivative embedded with disperse‐red dye, namely PCBDR, is reported. Incorporation of the thin DNA layer simultaneously leads to increasing the electron injection from non‐Ohmic contacts into the PCBDR active layer in dark and to increasing the photocurrent under irradiation. Such features lead to the observation of the enhancement of the photoresponsivity in PCBDR FETs up to 10³. Kelvin probe microscopy displays that in the presence of the DNA layer, the surface potential of PCBDR has a greater change in response to irradiation, which is rationalized by a larger number of photoinduced surface carriers. Transient absorption spectroscopy confirms that the increase in photoinduced carriers in PCBDR under irradiation is primarily ascribed to the increase in exciton dissociation rates through the PCBDR/DNA interface and this process can be assisted by the interfacial dipole interaction.     

Chemical Constituents and Biological Activities of the Leaves of Knema saxatilis

Chemistry of Natural Compounds -     

Optimality conditions under relaxed quasiconvexity assumptions using star and adjusted subdifferentials

A set-constrained optimization problem and a mathematical programming problem are considered. We assume that the sublevel sets of the involving functions are convex only at the point under question and hence these functions are not assumed quasiconvex. Using the two star subdifferentials and the adjusted subdifferential, we establish optimality conditions for usual minima and strict minima. Our results contain and improve some recent ones in the literature. Examples are provided to explain the advantages of each of our results.     

Molecular solubility and hansen solubility parameters for the analysis of phase separation in bulk heterojunctions

Although the fabrication procedures for bulk heterojunction (BHJ) solar cells are routinely optimized to accommodate new organic materials, the influence of solvent properties and cohesive forces on the film‐forming process and the self‐assembly of donor and acceptor molecules on the nanoscale are poorly understood. In this study, we measure the solubility of a variety of organic semiconductors in a range of solvents and calculate cohesive forces including dispersion forces, dipole interactions, and hydrogen bonding via Hansen Solubility Parameters (HSPs). HSPs were calculated by measuring the solubilities of various organic semiconductors in 27 solvents and the influence of solvent identity on film morphology of different BHJ mixtures was explored via atomic force microscopy (AFM). The possibility of correlations between HSPs and film morphology was considered; however, it is apparent that the HSP values alone do not play a critical role in determining the morphology of the films of conjugated polymers and molecules. This collection of solubility data constitutes the first of its type for organic semiconducting materials, and may act as a useful reference for the organic semiconductor community to aid in the understanding and selection of solvents for donor–acceptor BHJ mixtures. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Selective functionalization of 2-oxoallobetulin derivatives

A new series of 2-oxoallobetulin derivatives has been synthesized by using various unique reactions. Site-specific or regio-selective functionalization of those compounds has been investigated. In all cases, the reactions only happened at C-3 position except the synthesis of lactam happened at C-1 position. The intermediates leading to the novel allobetulin derivatives have also been described.     

Synthesis and characterization of some new 1,2,3-thiadiazole and 1,2,3-selenadiazole triterpene derivatives from allobetulone and 2-oxoallobetulin

Abstract

The synthesis of new 1,2,3-thiadiazole and 1,2,3-selenadiazole derivatives from triterpenoid ketones has been investigated via the corresponding semicarbazones. The intermediates 5, 8 have also been isolated, separated and their structures identified. The Hurd–Mori reaction and Lalezari method have been applied to synthesize a series of new substances 6 and 7. The regioselectivity of the functionalization mostly was centered at the C-3 position for the products 9 and 10. The structures of these compounds were confirmed by 2D-NMR spectroscopy.     

Static and vibration analysis of functionally graded beams using refined shear deformation theory

Static and vibration analysis of functionally graded beams using refined shear deformation theory is presented. The developed theory, which does not require shear correction factor, accounts for shear deformation effect and coupling coming from the material anisotropy. Governing equations of motion are derived from the Hamilton’s principle. The resulting coupling is referred to as triply coupled axial-flexural response. A two-noded Hermite-cubic element with five degree-of-freedom per node is developed to solve the problem. Numerical results are obtained for functionally graded beams with simply-supported, cantilever-free and clamped-clamped boundary conditions to investigate effects of the power-law exponent and modulus ratio on the displacements, natural frequencies and corresponding mode shapes.