Note on Schramm-Loewner Evolution for Superconformal Algebras

Theoretical and Mathematical Physics - Using the group-theoretical formulation of Schramm-Loewner evolution (SLE), we propose variants of SLE related to superconformal algebras. The corresponding...     

Field-induced functions of porous Si as a confined system

Electroluminescent porous Si (PS) diodes exhibit various useful functions under a high-electric field. The experimental PS diodes are composed of thin semitransparent metal films, PS layers (about 500 nm thick in minimum), p- or n-type Si substrates and ohmic back contacts. Definite nonlinear electrical behavior (negative resistance and nonvolatile bistable memory effects) and cold electron emission phenomena appear in these PS diodes associated with the EL emission. Both the negative resistance and memory effects are related to the charging of Si nanocrystallites by field-induced carrier injection. The electron emission observed in the PS diodes formed on n+–Si substrates is caused by hot electrons tunnelling through the top contact. By an appropriate structural control of PS, the effective drift length under a high-field conduction is significantly increased, and then electrons are emitted ballistically. These functions reflect the activity of PS as a nanocrystalline confined system.     

Superimpose of images by appending two simple video amplifier circuits to color television (author's transl)

Images are very useful to obtain diagnostic informations in medical fields. Also by superimposing two or three images obtained from the same patient, various informations, for example a degree of overlapping and anatomical land mark, which can not be found in only one image, can be often found. In this paper characteristics of our trial color television system for the purpose of superimposing X-ray images and/or radionuclide images are described. This color television system, superimposing two images in each different color consists of two monochromatic vidicon cameras and 20 inches conventional color television in which only two simple video amplifier circuits are added. Signals from vidicon cameras are amplified about 40 dB and are directly applied to cathode terminals of color CRT in the television. This system is very simple and economical color displays, and enhance a degree of overlapping and displacement between images. As one of typical clinical applications, pancreas images were superimposed in color by this method. As a result, size and position of pancreas was enhanced. Also X-ray image and radionuclide image were superimposed to find exactly the position of tumors. Furthermore this system was very useful for color display of multinuclides scintigraphy.     

Effect of high-pressure water-vapor annealing on energy transfer in dye-impregnated porous silicon

We have studied the effect of high-pressure water-vapor annealing (HWA) on the excitation energy transfer from Si nanocrystals to dye molecules in porous Si layers. Efficient photoluminescence, originating from both RhB molecules and Si nanocrystals, was observed. The behavior of the polarization memory of the photoluminescence showed the presence of energy transfer from the surface-passivated Si nanocrystals to RhB molecules. The fact that HWA, which is an effective method to stabilize and enhance the emission from Si nanocrystals in porous Si, does not suppress the energy transfer is an important result since it makes possible the realization of stable Si/dye-nanocomposite functional devices.     

Determination of localized states in porous silicon

We determined the density of state distribution near the Fermi level in porous silicon from the analysis of the current–voltage (J–V) and the current–thickness (J–T) characteristics in the space-charge-limited-current (SCLC) regime. The distribution exhibits a minimum density at the Fermi level, which is similar to the U-shape-trap-distribution observed in crystalline Si–SiO₂ interface or in amorphous Si. Theoretical analysis well explains both the J–V and the J–L characteristics, which implies that the current flow is entirely controlled by localized states situated at the quasi-Fermi level.     

Free field approach to the Macdonald process

Journal of Algebraic Combinatorics - The Macdonald process is a stochastic process on the collection of partitions that is a (q, t)-deformed generalization of the Schur process. In this...     

Adsorption and valence electronic states of nitric oxide on metal surfaces

Among fundamental diatomic molecules, the adsorption of carbon monoxide (CO) and nitric oxide (NO) on metal surfaces has been a subject of intensive research in the surface science community, partly owing to its relevance to heterogeneous catalysis used for environmental control. Compared to the rather well-defined adsorption mechanism of CO, that of NO is less understood because the adsorption results in much more complex reactions. The complexity is ascribed to the open-shell structure of valence electrons, making the molecule readily interact with the metal surface itself as well as with co-adsorbed molecules. Furthermore, the interaction crucially depends on the local structure of the surface. Therefore, to elucidate the interaction at the molecular scale, it is essential to study the valence state as well as the bonding geometry for individual NO molecules placed in a well-defined environment on the surface. Scanning tunneling microscopy (STM) is suitable for this purpose. In this review, we summarize the knowledge about the interaction of NO with metal surfaces, mainly focused on the valence electronic states, followed by recent studies using STM and atomic force microscopy (AFM) at the level of individual molecules.     

Energy transfer induced Eu3+ photoluminescence enhancement in tellurite glass

In this work, structural, thermal and optical properties of Eu³⁺ doped TeO₂–La₂O₃–TiO₂ glass were investigated. The differential scanning calorimetry (DSC) measurements reveal an important stability factor ΔT=143.52 K, which indicates the good thermal and mechanical stabilities of tellurite glass. From the absorption spectrum, the optical band gap was found to be direct with E_g=3.23 eV. The temperature dependences of photoluminescence (PL) properties of Eu-doped and Eu–Tb codoped tellurite glass are investigated. As the temperature increases from 7 to 300 K, both the PL intensity and the PL lifetime relative to the ⁵D₂→⁷F₀ are nearly constant below 230 K and then an enhancement takes place. This anomalous feature is attributed to the thermally activated carrier transfer process from charged intrinsic defects states to Eu³⁺ energy levels.By co-doping tellurite glasses with Eu and Tb, a strong Eu³⁺ PL enhancement is shown due to excitation transfer from Tb³⁺ and intrinsic defects to Eu ions.     

Biosensor for L-phenylalanine based on the optical detection of NADH using a UV light emitting diode

A biosensor was developed for the detection of L-phenylalanine (Phe) and demonstrated for use in the diagnosis of phenylketonuria (PKU). It consists of L-phenylalanine dehydrogenase (L-PheDH) immobilized on a membrane, an ultraviolet light-emitting diode excitation system, and a photomultiplier tube. The L-PheDH was immobilized on a teflon membrane modified with 2-methacryloyloxyethyl phosphorylcholine and placed at the distal and of an optical fiber. The concentration of Phe was determined by immersing the sensor into a sample solution that also contained NAD⁺ and measurement of the fluorescence of the NADH produced by enzymatic reaction. Two L-PheDHs (from Thermoactinomyces intermedius and Sporosarcina sp.) were studied and compared. The fluorescence intensities of the biosensor are linearly related to the L-Phe concentrations in the range from 10 μmol L^?1 to 10 mmol L^?1. The sensor also was operated in the kinetic mode by differential determination of the slope of the signal within 2 min. The analytical range of the sensor is adequate for application in the genotypic diagnosis of PKU (diagnostic value >600 μmol L^?1). High sensitivity, good cost-benefit ratio, and low power consumption are typical features of this biosensing system that can can be applied to routine screening of newborn.