Dynamical aspects of luminescence from GaAs-AlAs single quantum wells under hydrostatic pressure

Time-integrated and time-resolved photoluminescence studies of GaAs-AlAs single quantum wells under hydrostatic pressure were performed at 77 K. The Γ-point exciton luminescence quenches when the luminescence peak energy approaches 1.83 eV under hydrostatic pressure. The quenching is ascribed to the interlayer Γ-X crossing. Photoluminescence shows anomalously slow decay ranging from several nanoseconds to a few tens of nanoseconds under low hydrostatic pressure. With the further increase of hydrostatic pressure, the luminescence rise decreases drastically and is less than a few tens of picoseconds around the interlayer Γ-X crossover. The appearance of the slow decay component and the sudden decrease in the rise time are explained by the interlayer Γ-X transfer of electrons

Signal from sterile neutrino dark matter in extra U(1)U(1) model at direct detection experiment

We examine the possibility that direct dark matter detection experiments find decay products from sterile neutrino dark mater in $U(1)_{B-L}$ and $U(1)_R$ models. This is possible if the sterile neutrino interacts with a light gauge boson and decays into a neutrino and the light gauge boson with a certain lifetime. This decay produces energetic neutrinos scattering off nuclei with a large enough recoil energy in direct dark matter detection experiments. We stress that direct dark matter detection experiments can explore not only WIMP but also sterile neutrino dark matter.Comment: 12 pages, 3 figures: figures replaced, published in Physics Letters

Obelin mutants as reporters in bioluminescent dual-analyte binding assay

Author Posting. © Royal Society of Chemistry, 2013. This article is posted here by permission of RSC Publishing for personal use, not for redistribution. The definitive version was published in Analytical Methods 5 (2013): 636-640, doi:10.1039/C2AY25976A.Two obelin mutants distinctly different in the color of bioluminescence were successfully applied to simultaneous detection of two analytes in a single well. The flash-type signals were triggered by single injection of Ca2+ and were discriminated by the spectral and time resolutions. The technique was developed in a high-throughput format, and applied to simultaneous immunoassay of two gonadotropic hormones – luteinizing (lutropin or hLH) and follicle stimulating (hFSH) – in clinical sera, and to simultaneous detection of two gene allelic variants at single nucleotide polymorphism genotyping of the human F5 gene encoding factor V Leiden polymorphism 1691 G/A (R506Q). A considerable number of samples were investigated and the results obtained were in good correlation with those obtained by using traditional techniques.This work was supported by the Program of the Government of Russian Federation “Measures to attract leading scientists to Russian educational institutions” (grant no. 11. G34.31.058).2013-11-2

A novel-type luciferin from Siberian luminous earthworm Fridericia heliota : structure elucidation by spectral studies and total synthesis

Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Wiley-VCH Verlag GmbH & Co for personal use, not for redistribution. The definitive version was published in Angewandte Chemie International Edition 53 (2014): 5566–5568, doi:10.1002/anie.201400529.We report structure elucidation and synthesis of the luciferin from the recently discovered luminous earthworm Fridericia heliota. This luciferin represents a key component of a novel ATP-dependent bioluminescence system. The UV, fluorescence, NMR and HRMS spectral studies were performed on 5 mkg of the isolated substance, and gave four isomeric structures, conforming with spectral data. These isomers were chemically synthesized and one of them was found to produce light in the reaction with a protein extract from Fridericia. The novel luciferin was found to have an unusual deeply modified peptidic nature, implying an unprecedented mechanism of action.We acknowledge support from the Program of the Government of the Russian Federation “Measures to attract leading scientists to Russian educational institutions” (grant no. 11. G34.31.0058), the programs MCB RAS, President of the Russian Federation “Leading science school” (grant 3951.2012.4) and the Russian Foundation for Basic Research (grant 14-03-01015). B.M.S. was supported by a stipend from the Program of the President of the Russian Federation.2015-04-1

Discovery of Green Fluorescent Protein, GFP

Nobel Lecture, December 8, 200

Masses of dark matter and neutrino from TeV scale spontaneous U(1)B−LU(1)_{B-L} breaking

We propose a simple testable model with mass generation mechanisms for dark matter and neutrino based on the gauged $U(1)_{B-L}$ symmetry and an exact $Z_2$ parity. The $U(1)_{B-L}$ symmetry is spontaneously broken at the TeV scale, by which $Z_2$-odd right-handed neutrinos receive Majorana masses of the electroweak scale. The lightest one is a dark matter candidate, whose stability is guaranteed by the $Z_2$ parity. Resulting lepton number violation is transmitted to the left-handed neutrinos $\nu_L^i$ via the loop-induced dimension-six operator. Consequently, the tiny masses of $\nu_L^i$ can be generated without excessive fine tuning. The observed dark matter abundance can be reproduced by the pair annihilation via the s-channel scalar exchange due to mixing of neutral components of $\Phi$ and $S$, where $\Phi$ and $S$ respectively represent the Higgs doublet and the additional scalar singlet with the $B-L$ charge. The model can be tested at collider experiments as well as flavor experiments through the discriminative predictions such as two light neutral Higgs bosons with large mixing, invisible decays of the Higgs bosons as well as the $B-L$ gauge boson, and lepton flavor violation.Comment: 5 pages, 4 figures, 1 table; v2: Some discussions added. 2 figures and references added. Typos corrected. Final version to be publishe

Constraints from Unrealistic Vacua in the Next-to-Minimal Supersymmetric Standard Model

We study constraints to avoid deep unrealistic minima in the next-to-minimal supersymmetric standard model. We analyze a scalar potential along directions where all of and one of the three Higgs fields develop their vacuum expectation values, and find unrealistic minima deeper than the electroweak symmetry breaking (EWSB) vacuum. These unrealistic minima threaten the realization of the successful EWSB and therefore should be avoided. Necessary conditions to avoid these minima result in constraints of parameters. We show that a wide and significant region of the parameter space, especially large \lambda, is ruled out by our constraints.Comment: 25 pages, 4 figure