Differential pulse polarographic determination of l-lactate with a soluble enzyme preparation

Summary An electrochemical method for the determination of l-lactic acid using the specific reaction of lactate oxidase, has been studied and applied to lactic acid beverage and yoghurt. The technique is reasonably rapid and simple to perform. The calibration curve is linear in the concentration range from 1.0 to 20 mol/l, the reproducibility (R.S.D.) at 10 mol/l l-lactic acid is 1.34% (n=6) and the detection limit is 0.29 mol/l (k=2). The method can possibly be used for monitoring l-lactate or l-lactic acid in food industries and clinical laboratories.     

Free field realization of the level-2 elliptic algebra Ux,p ([^(\mathfraks\mathfrakl)]2 )*)U_{x,p} (\widehat{\mathfrak{s}\mathfrak{l}}_2 )*)

We give a level-2 representation of the elliptic algebra in terms of one free boson and one free fermion. We show that -modules have a natural direct sum decomposition into the irreducible (deformed) super-Virasoro modules associated with the coset . Presented at the International Colloquium “Integrable Systems and Quantum Symmetries”, Prague, 16–18 June 2005.     

2D molecular square grid of Cobalt(II) with tridentate phenylglycinate and mandelate: structure and magnetism

The hydrothermal synthesis, single crystal X-ray structures and magnetic properties of two layered cobalt-carboxylate complexes, _∞²[Co^II(O₂C^∗CH(OH)C₆H₅)₂] (1) and _∞²[Co^II(O₂C^∗CH(NH₂)C₆H₅)₂] (2), where O₂CCH(OH)C₆H₅ is mandalate and O₂CCH(NH₂)C₆H₅ is phenylglycinate, are described. Pale pink crystals of 1 and 2 were obtained by the reaction of cobalt nitrate and the enantiomer-pure acids at 120 °C. In each case, the structure consists of stacks of quasi square-grid polymeric sheets consisting of carboxylato- bridges, M-O-C-O-M, and the presence of both d- and l-enantiomers of the ligands segregated on each face of the layer. The ligands exhibit both chelating and bridging functions with the carboxylate group adopting an anti-anti mode. The magnetic properties are characteristic of weakly interacting paramagnets where the moments are elevated by an important orbital contribution via spin-orbit coupling.     

Beam-size measurement with optical diffraction radiation at KEK accelerator test facility

An experiment on the investigation of optical diffraction radiation (ODR) from a slit target as a possible tool for noninvasive electron beam-size diagnostics has been performed at the KEK accelerator test facility. The experimental setup has been installed at the diagnostics section of the extraction line. We have performed the first incoherent ODR observation from a slit target. The measured angular distributions are in reasonable agreement with the theoretical expectation. The beam-size effect onto the ODR angular pattern has been observed. Moreover, the sensitivity to the beam size as small as 14 microm has been achieved.     

A Color Appearance Model Applicable in Mesopic Vision

We propose a color vision model that can be used to predict color appearance in mesopic vision as well as photopic and scotopic vision. It is based on a two-stage model which consists of the cone and opponent stages and it assumes rod intrusion at the opponent stage. The model has the following features to describe the color appearance in mesopic vision. First, it includes a gradual and nonlinear shift in spectral luminous efficiency from V (LD) to V (LD) to cope with the spectral sensitivity difference between photopic and scotopic vision and the nonlinearity of rod influence on the luminance channel. Second, the model assumes decrease of the chromatic component with decreasing illuminance to explain the reduction of saturation at low illuminance levels. Third, it assumes that red/green and yellow/blue components change with illuminance levels independently, thus explaining hue shifts with decreasing illuminance. We applied the model for color appearance simulation of natural scenes in a mesopic visual environment.     

Age-dependent plasticity in the superior temporal sulcus in deaf humans: a functional MRI study

Background  

Sign-language comprehension activates the auditory cortex in deaf subjects. It is not known whether this functional plasticity in the temporal cortex is age dependent. We conducted functional magnetic-resonance imaging in six deaf signers who lost their hearing before the age of 2 years, five deaf signers who were >5 years of age at the time of hearing loss and six signers with normal hearing. The task was sentence comprehension in Japanese sign language.     

Migration analysis of micro-particles in liquids using microscopically designed external fields.

The recent development of new migration methods of micro-particles in liquids using various external fields is reviewed. The combination of a laser scattering force and a photothermal effect produced photothermal-conversion laser-photophoresis. A dielectric field generated in a planer or a capillary quadrupole electrode realized dielectrophoresis. Using a micrometer-scaled magnetic field gradient, the "Magnetophoretic velocimetry" of micro-particles was invented. Furthermore, the Lorentz force generated by combining an electric field and a magnetic field was utilized for electromagnetophoresis. These new methods were overlooked and the advantages in analytical use were discussed.     

Ni-catalyzed, ZnCl(2)-assisted domino coupling of enones, alkynes, and alkenes

A Ni(0)/ZnCl(2) system effectively promotes the coupling of enones and alkene-tethered alkynes. In the reaction with 1,6-enynes, the oxidative cyclization of Ni(0) species on enones across the alkyne part followed by ZnCl(2)-promoted cleavage generates alkenylnickel intermediates. Subsequent migratory insertion of the tethered alkene occurs with 5-exo-cyclization. When the resulting sigma-alkylnickel intermediates have beta-hydrogen atoms, the reaction terminates by beta-hydrogen elimination to provide cyclopentane derivatives. On the other hand, a sigma-alkylnickel intermediate that does not have beta-hydrogen atoms undergoes the insertion of a second alkene unit to cause a domino effect via a three-fold C-C bond formation process with and without the cleavage of one C-C bond.