Synthesis and crystal structure of α-NH4(VO2)(HPO4)

1992

Abstract Hydrothermal synthesis starting from β-NH 4 (VO 2 )(HPO 4 ) leads to α-NH 4 (VO 2 )(HPO 4 ): orthorhombic, space group Pb 2 1 a ; Z = 4; a = 6.830(1) A, b = 9.233(2) A, c = 8.817(2) A; R = 0.037 for 3371 reflections. NH + 4 cations connect isolated chains of trans -corner sharing VO 5 square pyramids running along the a -axis. The a -phase transforms irreversibly into the β-form by heating near 200°C. Comparison is made between the two phases.

Proton implanted waveguides in LiNbO3, KNbO3and BaTiO3

1992

Abstract By using a Van De Graaf accelerator, planar waveguides in LiNbO3, KNbO3, and BaTiO3 are fabricated (at 300 K) by thermally controlled proton implantation. The waveguide properties are investigated by dark line mode spectroscopy. The reconstructed profiles closely follow the ion concentration profiles as determined by simulation (TRIM).

Effect of Glufosinate (Phosphinothricin) and Inhibitors of Photorespiration on Photosynthesis and Ribulose-1,5-Bisphosphate Carboxylase Activity

1992

Summary Glufosinate (phosphinothricin) irreversibly inhibits glutamine synthetase and leads to a great decrease in the amino acids glutamine, glutamate, aspartate, serine, glycine and alanine. Due to the lack of glutamate and serine, the transamination of glyoxylate into glycine in the course of photorespiration cannot take place. The inhibition of this part of the photorespiratory process plays the essential role with respect to the photosynthesis inhibition caused by PPT under atmospheric conditions. After addition of different photorespiration or Calvin cycle intermediates to phosphinothricin no decrease in photosynthesis inhibition can be measured. This suggests that photosynthesis inhi…

Monte Carlo simulation of correlated electrons in disordered systems

1992

Abstract The properties of many-electron states in disordered systems with long-range electron-eletron interaction are investigated by means of a Monte Carlo simulation. Using the Metropolis algorithm, three-dimensional systems up to 512 sites are systematically analysed. The low-lying excitations are investigated in order to distinguish between one-particle and many-particle hopping. In the interesting regime in which disorder and correlation effects are equally important we find that variable-range hopping is insignificant for electron transfer when compared with the contribution from nearest-neighbour one-electron hopping processes as well as variable-number hopping.

Interactions of organotins with biological systems

1992

The bonding and structure in the environments of tin atoms in organotin-biological molecules has been investigated by 119Sn Mossbauer spectroscopy, mainly through the rationalization of the nuclear quadrupole splitting parameter by pointcharge model approaches. Organotin moieties R2SnIV and R3SnIV (R = Me, nBu, Ph) generally assume trigonal-bipyramidal type configurations in membranes of human erythrocytes, when incubated with whole erythrocytes and erythrocyte ghosts at the level of micromolar (μmol dm−3) organotin per mg of membrane protein. Corresponding structures are assumed by Me2SnIV and Me3SnIV in the cytoplasm. Ethanolic Me2SnCl2 yielded distorted trans-octahedral species when reac…

<title>Using infrared thermography as a tool to analyze curling and cockling of paper</title>

1992

Paper surface topology analysis with infrared thermography is described. Heat is applied perpendicular to the target. Temperature distribution of the sheet correlates well with the surface height distribution when the sheet is placed on the isothermic plate. Mathematical tools for data analysis and the mechanisms behind the curl and cockles are briefly discussed. Curl in paper and paperboard is defined as deviation from the flat form.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Deviation from Lorenz-type dynamics of an NH3 ring laser

1992

Abstract We show that the differences of the intensity spiral dynamics of an optically pumped NH 3 ring laser from that of the Lorenz model are caused by counterpropagating emission and by three-level coherence effects. In particular we find that under appropriate conditions the differences disappear and the laser emits purely according to the Lorenz model.

Liver-infiltrating T helper cells in autoimmune chronic active hepatitis stimulate the production of autoantibodies against the human asialoglycoprot…

1992

SUMMARYAutoantibodies against the human asialoglycoprotein receptor (ASGPR) occur in the sera orpaticnts with autoimmune liver disorders. Live-nfiltrating T cell clones that specifically recognize the ASGPR have been described in patients with autoimmune chronic active hepatitis (A-AH) and primary biliary cirrhosis (PBC). Recently, we have shown that peripheral blood mononuclcar cells (PBMC) from patients with A-AH or PBC but not chronic viral hepatitis secreted ant-SGPR antibodies in vitro. In this study we characterized the influence of live-nfiltrating T cells on the secretion of ASGP-pecific autoantibodies by autologous B cells in cell culture supernatants. T cell clones from liver biop…

Forebrain specialization and the olfactory system in anseriform birds. An architectonic and tracing study.

1992

In anseriform birds the mediodorsal part of the rostral forebrain is covered by a corticoid (= layered) structure, establishing a unique feature of this avian group since in other birds the non-cortical accessory or dorsal hyperstriatum occupies the corresponding surface area of the hemisphere. The efferents of the olfactory bulb are shown to reach this region, which thus can be identified as a heavily enlarged retrobulbar area. The large expansion of this olfactory representation may indicate an important biological function. In comparison to the mammalian olfactory system the three stratified olfactory projection centers of birds should be regarded as retrobulbar, prepiriform and periamyg…

Molecular recognition in biotin-streptavidin systems and analogues at the air-water interface

1992

Abstract Specific interaction between biotin and the protein streptavidin in monolayers of synthetic lipids with biotin headgroups has been shown to lead to formation of highly ordered two-dimensional streptavidin crystals. The same behaviour is observed when using desthiobiotin as lipid headgroup which exhibits a significantly lower binding constant compared with biotin (5 × 10 13 M -1 compared with 10 15 M -1 ). This offers the possibility of detaching competetively the 2D crystalline streptavidin layer by addition of free biotin to the aqueous phase. Use of lipoic acid as lipid headgroup ( K a = 7 × 10 7 M −1 ) leads to formation of small snisotropic protein domains indicating a crystall…

Thickness and temperature dependent structure of Cd arachidate Langmuir-Blodgett films

1992

Abstract The structure of monolayers of Cd arachidate on water and on solid support, and the thickness dependent changes when building up a multilayer via the LB technique are studied by means of grazing incidence diffraction of X-ray. In monolayers the perpendicularly oriented amphiphilic molecules are arranged in a hexagonal lattice, whereas for thicker layers (even for three layers) they crystallize in an orthorhombic unit cell with a reduced molecular are ( A = 18.2 A 2 ) compared to that of the monolayer ( A = 19.7 A 2 ). In-plane diffraction measurements with wave vector transfer perpendicular to the surface (rod scans) could prove for multilayers a maximum tilt angle of 2°. The data …

Local-porosity theory for flow in porous media

1992

A recently introduced geometric characterization of porous media based on local-porosity distributions and local-percolation probabilities is used to calculate dc permeabilities for porous media. The disorder in porous media is found to be intimately related to the percolation concept. The geometric characterization is shown to open a possibility for understanding experimentally observed scaling relations between permeability, formation factor, specific internal surface, and porosity. In particular, Kozeny's equation k\ensuremath{\propto}\ensuremath{\varphi}\ifmmode\bar\else\textasciimacron\fi{} $^{\mathit{b}}$ between effective permeability and bulk porosity and the relation k\ensuremath{\…

Female choice in the kestrel under different availability of mating options

1992

Abstract Mate choice in relation to its fitness consequences on females was studied in kestrels, Falco tinnunculus , in western Finland. The breeding season is short with rapidly declining prospects of successful breeding, suggesting that females should make their mating decision quickly. On average, males arrived a few days before females, but late males arrived much later than early females. Pairs were usually formed within 2 days of male arrival, and only early males were available to early females. Options for female choice differed considerably in years of different kestrel density. In a good vole year, 1988, females had many males to choose from, but in poor vole years, 1989 and 1990,…

Structural and surface characterization of the polycrystalline system CrxOy · TiO2 employed for photoreduction of dinitrogen and photodegradation of …

1992

The polycrystalline system CrxOy-TiO2, used as a catalyst for photoreactions, was studied by X-ray diffractometric method, visible-ultraviolet diffuse reflectance and infrared spectroscopic methods, surface area determination, and porosimetry to characterize its structural and surface features. Two series of catalysts were prepared by two different methods, namely by coprecipitation and by impregnation. The first series was tested as photocatalysts for the dinitrogen photoreduction in a gas-solid regime and for the phenol photodegradation in a liquid-solid regime. The results indicate that the interaction of chromium ions with OH groups modifies the surface properties of the supports and co…

Cooperative effects on the HS→LS relaxation in the [Fe(ptz)6](BF4)2 spin-crossover system

1992

Abstract The high-spin to low-spin (HS→LS) relaxation in the [Fe(ptz) 6 ](BF 4 ) 2 spin-crossover system deviates strongly from first-order kinetics because of cooperative effects of elastic origin. The shift in horizontal and vertical displacement of the potential wells of the initial and final state relative to each other due to the build-up of an “internal” pressure is estimated from spectroscopic measurements. The HS→LS relaxation as such is described by the theory of nonadiabatic multiphonon relaxation in the strong-coupling limit, with a Huang—Rhys factor S ≈ 45 which is much larger than the reduced energy gap p . The sigmoidal relaxation curves in [Fe(ptz) 6 ](BF 4 ) 2 result when a …

Molecular hybridization techniques in current diagnosis of chronic hepatitis B in childhood.

1992

Following the cloning and sequencing of the hepatitis B virus genome, molecular hybridization techniques have been established to detect hepatitis B virus (HBV) DNA in serum and liver tissue. Analyses can be performed by dot blot, Southern blot and in situ hybridization. HBV DNA is regarded to be the most sensitive marker of viral replication and infectivity which was previously related to the presence of hepatitis B e antigen in serum and hepatitis B core antigen in liver cells. In liver tissue different molecular patterns can be recognized as free viral DNA and integrated sequences. Furthermore, introduction of the polymerase chain reaction allows the detection of very small amounts of vi…

Identification and characterization of a monoclonal antibody to the membrane fatty acid binding protein

1992

A monoclonal antibody to the rat liver membrane fatty acid binding protein (MFABP) was prepared by immunizing mice with purified MFABP isolated from solubilized rat liver plasma membrane proteins by oleate-agarose affinity chromatography technique. The monoclonal antibody K15/6 identified a single 40 kDa protein in rat liver plasma membranes with pI values of 8.5, 8.8 and 9.0, which is identical to the authentic MFABP, but clearly distinct from rat mitochondrial GOT. The antibody K15/6 selectively inhibited cellular influx as well as membrane binding of fatty acids, but not of cholesterol or vitamin E. The same antibody was used in immunofluorescence, ELISA and Western blot analysis to dete…

A SURVEY ON THE ACOUSTICAL CONDITIONS IN A SPANISH SECONDARY SCHOOL

1992

The present paper reports on a study of the acoustical conditions in a secondary school of Gandia (Spain). Our data include a complete information on noise levels, reverberation times and speech intelligibility of classrooms, together with the results of two social surveys adressed to teachers and students in order to know their attitudes towards this problem.

Funktionelle Biochemie des Menschen. Band 1 und 2. (Reihe: Wissenschaftliche Taschenbücher.) VonE. Hofmann. Akademie Verlag, Berlin. Band 1: 1990, 31…

1992

Characterization of Membrane-Bound Cyclic Nucleotide Phosphodiesterases from Bovine Aortic Smooth Muscle

1992

This study reports the isolation and characterization of cyclic nucleotide phosphodiesterases (PDEs) associated with membrane fraction in comparison to cytosolic forms from bovine aorta. DEAE-Sephacel chromatography of a solubilized membrane fraction from a homogenate, prepared under isotonic conditions in the presence of protease inhibitors, yielded one major peak of PDE activity that specifically hydrolyzed cAMP and was not stimulated by calmodulin: It appeared to contain two subtypes of PDE. The first subtype belonged to the cyclic GMP (cGMP)-inhibited PDE family, (PDE III): It had an apparent Km value of 0.4 microM and was potently inhibited by cGMP, LY186126, and cilostamide. The secon…

Convective stability of hot matter in ultrarelativistic heavy-ion collisions

1992

Abstract The convective stability of strongly interacting matter undergoing hydrodynamic flow in ultrarelativistic heavy-ion collisions is studied in both the quark-gluon plasma and hadron gas phases. We find that this stability depends on the form of the initial conditions assumed for the hydrodynamic flow. In the case of initial conditions corresponding to partial transparency the flow of the quark-gluon plasma is stable whereas the flow of the hadron gas is convectively unstable. The timescale for hydrodynamic oscillations around the (stable or unstable) equilibrium state is found to be larger than the expected lifetime of the system, suggesting that the flow in either case is close to n…

Buildup of ultrathin multilayer films by a self-assembly process: III. Consecutively alternating adsorption of anionic and cationic polyelectrolytes …

1992

A solid substrate with a positively charged planar surface is immersed in a solution containing an anionic polyelectrolyte and a monolayer of the polyanion is adsorbed. Since the adsorption is carried out at relatively high concentrations of polyelectrolyte, a large number of ionic residues remain exposed to the interface with the solution and thus the surface charge is effectively reversed. After rinsing in pure water the substrate is immersed in the solution containing a cationic polyelectrolyte. Again a monolayer is adsorbed but now the original surface charge is restored. By repeating both steps in a cyclic fashion, alternating multilayer assemblies of both polymers are obtained. The bu…

The apolipoprotein(a) moiety of lipoprotein(a) interacts with the complement activation fragment iC3b but does not functionally affect C3 activation …

1992

A previous study has shown that complement component C3 binds to recombinant apolipoprotein(a) (r-apo(a)). In the present report we have investigated the interactions between lipoprotein(a) (Lp(a)), r-apo(a) and C3 in relation to complement activation and degradation. Neither Lp(a) nor r-apo(a) affected complement activation as indicated by sheep and rabbit red blood cell hemolytic assays, and by assessment of the amount of C3a generated in zymosan-activated human serum in the presence or absence of Lp(a). Crossed immunoelectrophoretic analyses indicated that Lp(a) retarded the migration of iC3b in complement-activated serum but had no effects on C3, C3b, C3c or C3dg. Recombinant apo(a) exh…

Transgressions‐regressions and echinoid morphoclines

1992

Tumor in the Horseshoe Kidney: Clinical Implications and Review of Embryogenesis

1992

We report on 3 patients with tumor in a horseshoe kidney, 1 of whom had bilateral tumor (renal cell cancer on the right side and urothelial cancer on the left side). Tumors that arise predominantly in the bridge of a horseshoe kidney can mimic the symptoms of an intra-abdominal disease process. Besides routine diagnostic procedures, angiography is essential to plan the surgical approach, which in principle should be organ-sparing. The literature of the embryology of the horseshoe kidney was reviewed for a relationship between the abnormal renal development and the site of tumorigenesis, and for development of a key for the wide variation of blood supply. Recently reported data suggest that …

Protective Groups in Organic Synthesis. 2. Auflage. Herausgegeben vonT. W. Greene undP. G. M. Wuts. Wiley, Chichester. 1991. XVI, 473 S., geb. £47.50…

1992

On the automorphism group of the integral group ring of Sk wr Sn

1992

Abstract Let G = SkwrSn be the wreath product of two symmetric groups Sk and Sn. We prove that every normalized automorphism θ of the integral group ring Z G can be written in the form θ = γ ° τu, where γ is an automorphism of G and τu denotes the inner automorphism induced by a unit u in Q G.

Optimization of a conversion electron Mössbauer spectroscopy gas flow He/CH4 proportional counter

1992

A new detector for CEMS has been built and optimized with respect to the statistical quality of spectra obtained. The optimization has been performed by measuring Mosbauer and pulse height spectra at in- and off-resonance. Single channel analyzer settings were calculated by a new optimization routine. A comparison of different detector designs has been performed using the statistical utility rate of spectra obtained from a stainless steel foil. A procedure for determining optimal operating parameters for ICEMS gas flow proportional counters is proposed.

Il rilievo del moderno. Palermo architettura e città 1948-1962

1992

Il lavoro è una riflessione relativa al disegno delle proposte architettoniche che hanno investito la città dal secondo dopoguerra agli anni sessanta. Osservare queste opere attraverso i loro disegni originali e il ridisegno costituisce un'operazione che tende a mettere in evidenza il rapporto, sempre costante, tra mestiere e ricerca intellettuale.

Study of interface diffusion of Ti and TiN PVD layers by Bremsstrahlung-induced AES

1992

The influence of heat treatment in ultrahigh vacuum (UHV) on Ti and TiN layers coated by physical vapour deposition (PVD) has been studied by AES, XPS and bremsstrahlung-induced AES. It could be concluded that up to 500 o C (1 h) the Ti layer does not change significantly. At the TiN/steel substrate interface, however, a counter-diffusion of nitrogen and adventitious oxygen takes place, resulting in partial nitridation of the steel substrate and oxidation of the coating

Methoden der Kern- und Radiochemie. VonP. Hoffmann undK. H. Lieser. VCH Verlagsgesellschaft, Weinheim, 1991. XII, 241 S., geb. DM 88.00. — ISBN 3-527…

1992

Mössbauer investigations on glass-forming organic liquids

1992

Glycerol forms a molecular glass near 180K. Fe2+ dissolved in glycerol allows the study of the dynamics of the system by Mossbauer spectroscopy. Recently it has been shown that the Mossbauer spectra can be understood in a way consistent with the results of dielectric and ultrasonic viscoelastic relaxation measurements. A jump diffusion model of Sinqwi and Sjolander with a jump rate distribution according to Davidson and Cole allowed us to fit the Mossbauer spectra of Fe in glycerol. First attempts to compare mode coupling theory with Mossbauer spectra are reported.

Characterization of vitellogenins in Spilostethus pandurus (Hemiptera): Immunoelectrophoretic studies and short-term labelling experiments

1992

Abstract The haemolymph of Spilostethus pandurus contains three female-specific proteins (I, II and III) as revealed by SDS-PAGE. Antibodies prepared against them recognize three fractions (4, 5 and 6) in ovarian extracts which have similar molecular weights suggesting that I, II and III are vitellogenins. Upon injection of a 14C amino acid mixture into vitellogenic females, labelled proteins first appear in the fat body, then in the haemolymph and next in the ovarian follicles.

ON THE CALCULATION OF THE HEAT CAPACITY IN PATH INTEGRAL MONTE CARLO SIMULATIONS

1992

In Path Integral Monte Carlo simulations the systems partition function is mapped to an equivalent classical one at the expense of a temperature-dependent Hamiltonian with an additional imaginary time dimension. As a consequence the standard relation linking the heat capacity Cv to the energy fluctuations, <E2>−<E>2, which is useful in standard classical problems with temperature-independent Hamiltonian, becomes invalid. Instead, it gets replaced by the general relation [Formula: see text] for the intensive heat capacity estimator; β being the inverse temperature and the subscript P indicates the P-fold discretization in the imaginary time direction. This heatcapacity estimator…

conversion electron Mössbauer study of low carbon steel polarized in aqueous sulfate solution containing sulfite in low concentration

1992

The passivation of low carbon steel was studied in aqueous solution of 0.5 M Na2SO4+0.001 M NaHSO3 at pH=3.5 and 6.5. The found major components at pH-3.5 were: γ-FeOOH and Fe3C, and also FeSO4.H2O could be identified on the surface of the low carbon steel as a minor component. At pH-6.5, the passive film contained only amorphous iron(III)-oxide or oxyhydroxide.

Layer formation on silicon steel by processing in H2/H2O at elevated temperatures

1992

Silicon steel (Fe-3wt%Si), as used for transformers and generators, has been annealed in wet hydrogen at elevated temperatures. The composition, sequence, and thicknesses of the layers found by conversion electron Mossbauer spectroscopy (CEMS) and Auger electron spectroscopy (AES) depth profiling for a 10 minutes anneal in different atmospheres are reported. In the range from 500°C to 720°C we observed carbide formation, indicating that the decarburization is hindered. Above 800°C, the layers consist of fayalite or of fayalite and iron oxides, depending on the oxygen potentialaO. At 843°C, the onset of iron oxide formation was found ataO=0.33.