Memory function for cyclotron resonance of two-dimensional electron systems

Coulomb effects on cyclotron resonance in two-dimensional electron systems are investigated based on a self-consistent approach which improves the random-phase approximation. The memory function in the dynamic magnetoconductivity depends on the electron density not only through the filling factor v but also on its combination with the dimensionless density parameter r_s in the form $\text{r}{}_{\mathrm{s}}\text{v}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$. The memory function reproduces the data of Wilson, Allen and Tsui for intermediate densities.     

Specular reflectivity studies of the electrosorption of aromatic hydrocarbons on gold electrode in 2-methoxyethanol solution

Electrosorption of some aromatic hydrocarbons on gold electrode has been studied by the measurement of the specular reflectivity change in 2-methoxyethanol containing about 0.2 M NaClO₄. In the presence of the hydrocarbons, the reflectivity decrease was found to be enhanced in the positive side of the potential region, the decrease being ascribed to the taking place of adsorption. With the assumption that the reflectivity decrease is proportional to the coverage, the observed change was analysed by varying the concentrations of the hydrocarbon at varied potentials. The observed values could fairly be elucidated on the basis of the modified Langmuir isotherm in which the potential dependent term is included and the adsorption is assumed to proceed through the replacement of an adsorbed solvent molecule. Regarding a larger molecule, a larger number of solvent molecules was replaced and a larger negative value of the energy of adsorption was obtained. This is in accordance with the mechanism that the hydrocarbons are adsorbed by lying flat on the surface through the π-electron interaction. The rate of adsorption was examined at a lower concentration range and could be elucidated in terms of the diffusion controlled mechanism. Extension of the McIntyre-Aspnes theory to the multilayer system has been attempted and the net reflectivity change was shown to be the sum of the change due to each layer. The major cause of the reflectivity change was examined by comparing the observed wavelength dependence of the change with those calculated on the basis of the increase in the refractive index in the double layer or the electroreflectance. Both of the calculated curves were not in accordance with the observed curve, indicating that the other mechanism might play an important role.     

Risks of Muscle Atrophy in Patients with Malignant Lymphoma after Autologous Stem Cell Transplantation

Objective: Muscle atrophy is associated with autologous stem cell transplantation (ASCT)-related outcomes in patients with malignant lymphoma (ML). However, the impact of ASCT on muscle mass remains unclear in patients with ML. The aims of this study were to investigate changes in muscle mass and risk profiles for muscle atrophy after ASCT. Method: We enrolled 40 patients with refractory ML (age 58 [20-74] years, female/male 16/24, body mass index (BMI) 21.1 kg/m² [17.1-29.6]). Psoas muscle mass was assessed using the psoas muscle index (PMI) before and after ASCT. Statistical analysis used: Independent factors associated with a severe decrease rate of change in PMI were evaluated by decision-tree analysis, respectively. Results: PMI was significantly decreased after ASCT (4.61 vs. 4.55 cm²/m²; P=0.0425). According to the decision-tree analysis, the regimen was selected as the initial split. The rates of change in PMI were −5.57% and −3.97% for patients administered MCEC and LEED, respectively. In patients who were administered LEED, the second branching factor was BMI. In patients with BMI < 20.3 kg/m², the rate of change in PMI was −7.16%. On the other hand, the rate of change in PMI was 4.05% for patients with BMI ≥ 20.3 kg/m². Conclusion: We demonstrated that muscle mass decreased after ASCT in patients with ML. Patients who received MCEC and patients with low BMI were at risk for a decrease in muscle mass.     

Relative population of S-form and F-form conformers of bryonolic acid and its derivatives in equilibrium in CdCl3 solutions

Relative populations of S-form (D-E rings: boat-boat form) and F-form (D-E rings: chair-chair form) conformers, in equilibrium in CDCl3 solutions, of 20 derivatives (2-21) of bryonolic acid (D:C-friedoolean-8-en-3beta-ol-29-oic acid) (1) were calculated from NMR spectral data (J-values and chemical shifts), with the aid of molecular mechanic calculation using a MM2/CONFLEX program system. The principal deciding factor of the population ratio was found to be whether the functionality at C-29 is trigonal or tetrahedral; the S-form: F-form was 0:100-32:68 for the "trigonal" type and 48:52-100:0 for the "tetrahedral." The reliability of the results is discussed.     

480—Redox and adsorption behaviour of some redox coenzymes involved in an electron-transport chain studied by the electro-optical technique

The redox and adsorption behaviour of some redox coenzymes involved in an electron-transport chain, i.e. ubiquinone-10 (CoQ), flavocoenzymes [flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD)] and nicotinamide adenine dinucleotide (NAD⁺), has been studied at a gold electrode by cyclic voltammetry and specular reflectivity measurement. All the coenzymes investigated were found to participate in electron transport in adsorbed states on the electrode surface. Adsorbed CoQ and flavocoenzymes are reduced and the resulting products remain adsorbed at the surface. Contrary to them, adsorbed NAD⁺ is reduced and then desorbed immediately. Possible models for the surface orientation of adsorbed molecules were proposed based on the experimental data.Some analogies can be noted between the interfacial behaviour of these coenzymes at the electrode and that in mitochondria.     

On the scattering properties of a weakly charged polymer gel

A phenomenological model is presented to describe weakly charged polymer gels based on the classical elasticity theory. The structure factor of the gel is calculated considering both thermal and frozen concentration fluctuations as well as the screened Coulomb interaction. In agreement with the recent experimental finding the result shows anomalous crosslink-density dependence of the scattering profiles. Received: 28 March 1997 / Revised: 4 September 1997 / Accepted: 23 October 1997     

Cooperative diffusion in weakly charged polyelectrolyte gels

A general expression for the cooperative diffusion constant of weakly charged gels is derived as a function of the thermodynamic parameters such as polyelectrolyte concentration, salt concentration, ionic strength, and the degree of crosslinking. In the low concentration range it decreases with the monomer concentration. Received: 30 January 1998 / Revised: 4 May 1998 / Accepted: 6 May 1998     

Spectrophotometric determination of phosphate using lanthanum chloranilate

The spectrophotometric determination of phosphate using lanthanum chloranilate has been investigated. It is possible to determine 3–300 ppm of phosphate with an accuracy of ±2%, if suitable conditions are chosen. Chloride or nitrate ions do not interfere up to 400 ppm. Interference from sulphate ion can be compensated for by adding a large amount of sulphate both to the sample and to the standard solutions. This method is simpler, has less critical reaction conditions, and develops a much more stable coloration than the conventional heteropolyacid methods.     

Construction of pyrimido[5,4-e]-as-triazine,purine, v-triazolo-[4,5-d]pyrimidine and pyrazolo[3,4-d]pyrimidine ring systems from 5-arylazo-6-arylidenehydrazino-1,3-dimethyluracils

Reaction of 5-arylazo-6-arylidenehydrazino-1,3-dimethyluracils (II), prepared by the treatment of 6-aryl-idenehydrazino-1,3-dimethyluracils (I) with diazotized arylamines, with dimethylformamide dimethylacetal resulted in the formation of pyrimido[5,4-e]-as-triazine (V) system, while the thermolysis of II resulted in the formation of purine (X), v-triazolo[4,5-d]pyrimidine (XII), and pyrazolo[3,4-d]pyrimidine (XIV, XIX) systems in lieu of the expected V. Reasonable mechanisms have been proposed for the formation of the various ring systems in these reactions.     

Binuclear Copper(II) Complexes. N,N′-bis(3-aminopropyl)-oxamidatocopper(II) coordinated as a bidentate ligand

Four new binuclear copper(II) complexes having sub-normal magnetic moment have been synthesized by reaction of N, N′-bis(3-aminopropyl)-oxamidatocopper(II) with another copper(II) compound such as mono- and bis-(2,2′-bipyridine)-copper(II) nitrate, cupric mono-malonate, or cupric chloride. One of them, [Cu₂(APxd)(bipy)₂](NO₃)₂(cf. Fig. 2), was recognized to be a binuclear complex in which each copper(II) ion has a five-coordinated environment. The data from analyses, IR and electronic spectra, magnetic susceptibility measurements, and conductivity measurements were used to establish the structures.