Stress in Thin Films;Diffraction Elastic Constants and Grain Interaction

Untextured bulk polycrystals usually possess macroscopically isotropic elastic properties whereas for most thin films transvers isotropy is expected,owing to the limited dimenionlity .The usually applied models for the calculation of elstic constants of polycrystals from single crystal elastic contants(so-called grain interaction models)erroneously predict macroscopic isotropy for an(untextured) thin film.This paper presents a summary of recent work where it has been demonstrated for the first time by X-ray diffraction analysis of stresses in thin films that elastic grain interaction can lead to macroscopically anisotropic behaviour (shown by non-linear sin^2φ plots).A new grain interaction model,predictin the macroscopically anisotropic behaviour of thin films,is proposed.     

Psychosomatic aspects of sudden deafness

PURPOSE: In patients with septic shock, the cardiac index is often increased. Maldistribution of blood flow and regional hypoperfusion has been implicated as a key factor in the pathogenesis of organ dysfunction in these patients. We have investigated the relationship between cerebral blood flow and cardiac index in patients with septic shock. MATERIALS AND METHODS: We used Doppler ultrasound techniques to investigate limb and carotid blood flow in 15 patients with septic shock and 9 nonseptic controls. RESULTS: In the nonseptic control patients, common femoral and brachial blood flow were proportional to cardiac index (r=0.73 and 0.76; P=.038 and .017, respectively) reflecting a protective redistribution of flow to more vital organs. However, this relationship was absent in patients with septic shock (r=0.23 and 0.21). Furthermore, in the septic patients but not the nonseptic controls, cerebral blood flow was correlated with the cardiac index (r=0.66, P < .05 vs r=-0.36, NS in nonseptic controls). Carotid flow was independent of mean arterial pressure, PaCO2 and PaO2 in patients with septic shock. CONCLUSIONS: These data are consistent with a loss of autoregulation of cerebral blood flow and a change in the control of limb blood flow in humans with septic shock.     

Wet oxidation of glucose

Wet oxidation is used to oxidize organic substances at a controlled rate in an aqueous medium at elevated temperatures and pressures. Aqueous glucose solutions were oxidized with pure oxygen at four different temperatures in the range 176.7°C to 260.0°C, and at an oxygen pressure of 2.3 MPa. Three distinct stages of wet oxidation were found — induction, rapid oxidation, and slow oxidation. During the rapid oxidation period the reaction was assumed to be confined to a thin liquid layer next to the gas-liquid interface. The activation energy for the rapid oxidation period was estimated to be 130 ± 20 kJ/mol. Acetic acid was found to accelerate the rate of wet oxidation of glucose only slightly.     

Electron microscopy and X-ray diffraction studies of rapidly quenched Zr---Ni and Hf---Ni ribbons with about 90 at.% Ni

The structure of melt-spun ribbons of the alloys Zr₉Ni₉₁, Zr₁₀Ni₉₀ and Hf₁₁Ni₈₉ was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Ribbons of the Zr₉Ni₉₁ and Zr₁₀Ni₉₀ alloys prepared at a high cooling rate (ribbon thickness d=11 μm) were characterized by an amorphous matrix with a few per cent of quenched-in crystallites. The ribbon of the Hf₁₁Ni₈₉ alloy prepared with the same thickness (i.e. at the same cooling rate) exhibited a nanocrystalline grain structure of the HfNi₅ phase. Thicker ribbons of the Zr₉Ni₉₁ alloy (d=17–22 μm), for which the quench rate was correspondingly lower, were obtained as a b.c.c. Ni(Zr) solid solution phase with a grain size of nearly 1 μm. A high resolution (HR) TEM study of one of the Zr₉Ni₉₁ crystalline ribbons revealed a fine structure of the interior of the crystallites which can be attributed to an ordering on the Zr sublattice over distances of several nanometres within the b.c.c. grains.     

Short-Range and Medium-Range Order in Lithium Silicate Glasses, Part II: Simulation of the Structure by the Reverse Monte Carlo Method

The results of X-ray and neutron diffraction experiments with (Li₂O) _x (SiO₂)_{100_x} glasses (x = 0, 20, 33.3, and 40) are discussed using the Reverse Monte Carlo method to produce atomic clusters, which are analyzed with respect to the O-O distribution, the angular correlations within the first and higher coordination spheres, and the bond-orientational multipole moments. Within Li₂O-containing silicate glasses, each lithium atom is surrounded by a ring of six SiO₄ tetrahedra in such a way that four oxygen atoms lie at the joints of a tetragonal cell centered by lithium. Thus, the lithium atoms increase the order of the glass.     

Fully-automated system for dissolution rate of solid oral dosage forms according to the paddle method

This paper describes a fully-automated system (AUTO DISS^®) for the determination of active ingredient release of solid oral dosage forms according to the paddle method of the US Pharmacopoeia (USP) and European Pharmacopoeia.Twenty batches can be tested continuously, with the six individuals (tablets, capsules etc.) of one batch being examined synchronous. The components of the AUTO DISS^® system are presented and the operating steps of automatic filling with dissolution medium, dropping in of tablets, sampling and cleaning of vessels are described. Suitability for testing controlled-release drugs by means of automated buffer change from simulated gastric fluid to simulated intestinal fluid according to USP is also demonstrated. On-line determination of active ingredient concentration, as well as evaluation and documentation of measured values, is possible using an integrated automatic sampler in combination with various measuring instruments.The AUTO DISS^® system is shown to be both rugged and accurate.     

Recombinant phytochrome of the moss Ceratodon purpureus: heterologous expression and kinetic analysis of Pr-->Pfr conversion

The phytochrome-encoding gene Cerpu;PHY;2 (CP2) of the moss Ceratodon purpureus was heterologously expressed in Saccharomyces cerevisiae as a polyhistidine-tagged apoprotein and assembled with phytochromobilin (P phi B) and phycocyanobilin (PCB). Nickel-affinity chromatography yielded a protein fraction containing approximately 80% phytochrome. The holoproteins showed photoreversibility with both chromophores. Difference spectra gave maxima at 644/716 nm (red-absorbing phytochrome [Pr]/far-red-absorbing phytochrome [Pfr]) for the PCB adduct, and 659/724 nm for the P phi B-adduct, the latter in close agreement with values for phytochrome extracted from Ceratodon itself, implying that P phi B is the native chromophore in this moss species. Immunoblots stained with the antiphytochrome antibody APC1 showed that the recombinant phytochrome had the same molecular size as phytochrome from Ceratodon extracts. Further, the mobility of recombinant CP2 holophytochrome on native size-exclusion chromatography was similar to that of native oat phytochrome, implying that CP2 forms a dimer. Kinetics of absorbance changes during the Pr-->Pfr photoconversion of the PCB adduct, monitored between 620 and 740 nm in the microsecond range, revealed the rapid formation of a red-shifted intermediate (I700), decaying with a time constant of approximately 110 microseconds. This is similar to the behavior of phytochromes from higher plants when assembled with the same chromophore. When following the formation of the Pfr state, two major processes were identified (with time constants of 3 and 18 ms) that are followed by slow reactions in the range of 166 ms and 8 s, respectively, albeit with very small amplitudes.     

Estimating the value of co-operation approaches for multi-hop ad hoc networks

In multi-hop ad hoc networks, each node may be involved in forwarding data acting as a router. Unfortunately, in civilian scenarios with usually an open community, it is not obvious why nodes should forward foreign data and waste their battery power, CPU cycles, etc. Some work has already been done in proposing approaches to intensify participation in ad hoc networks. However, it is more or less a question of belief whether these approaches really benefit the community. This work gives a rational estimation of the effect of approaches that intensify participation in ad hoc networks. We present essential results assuming in particular low-dense networks that use on-demand routing protocols by applying some fundamental statistics to the problem.