Enteric vascular endothelial response to bacterial endotoxin

The response of enteric vasculature to endotoxin was examined at the ultrastructural level using a murine model of endotoxin-induced acute diarrhoea. Morphological changes indicative of endothelial damage were evident as early as 15 minutes following endotoxin challenge. These changes, characterized by widening of intercellular spaces, increased microvillous projections and the appearance of stress fibres, preceded the leucocytic response. Endothelial damage increased with time, being associated with progressive degenerative changes in the plasma membrane, cytoplasm and organelles, ultimately leading to desquamation. These latter changes were temporally associated with margination of neutrophils and platelet adhesion to the denuded subendothelium. The venules were the primary site of these changes while the capillaries were the least affected. The arterioles were markedly constricted with minimal endothelial damage. These changes suggest that the enteric vascular endothelium may be an important target organ, and the resultant endothelial injury may have implications in host responses to endotoxin.     

Ionization current in N2 gas: XI. three‐dimensional analysis for loss processes of metastable particles affected by the reflection at the boundary

Loss of the metastable nitrogen molecule N₂(A³Σ⁺_u) in plane parallel electrodes has been investigated by us previously by solving the diffusion equation. Our procedure is based on an analysis using the third kind of boundary condition, which can take account of finite values for the density of N₂(A³Σ⁺_u) at the electrode surfaces. The values of the effective lifetime of N₂(A³Σ⁺_u) calculated from this analysis were reasonably consistent with our experiments. This paper describes the behavior of the effective lifetimes of RN₂(A³Σ⁺_u) in a cylindrical cavity. The analytical treatment of the diffusion equation for N₂(A³Σ⁺_u) proposed by us is extended to three‐dimensional space. We systematically report the effective lifetimes of metastable molecules in a cylindrical cavity. © 2000 Scripta Technica, Electr Eng Jpn, 130(4): 1–8, 2000     

Effect of Interlayer Thickness of Ion-Plated Pb-Coating on Its Life (SUS440C Substrates)

High-precision ball bearings (SUS440C) used in spacecraft mechanisms that are exposed to deep space vacuum are solid lubricated by thin, adherent Pb ion-plated coatings. The high reliability requirements with long endurance life of these mechanisms solely depend on the tribological aspects of this solid-lubrication coating. Since ion-plated, soft metallic coatings have a graded coating–substrate interface structure, a gradual change in mechanical, chemical and thermal properties is expected across the depth of the coating. This aspect of the interlayer plays a major role in determining the extent of optimum tribological properties of the coating. By improving the interlayer, both in terms of increased thickness and concentration of Pb, a corresponding improvement in the lubricity and endurance life of this Pb ion-plated coating on AISI 440C stainless steel (bearing material) can be assured. For this, a detailed examination of the interlayer of the ion-plated Pb film on the nano-micro level is mandatory. This report is focused on the cross-sectional examination of the interlayer by scanning electron microscopy. SUS440C steel disk specimens having similar properties as the bearing material and with a thin, ion-plated Pb coating processed under two different substrate bias conditions of ion-plating are used. The thickness of the Pb/steel interlayer and the elemental composition are analyzed using SEM and EDS respectively. The endurance life of the coatings is measured by repeated sliding wear tests with a pin-on-disk tester in vacuum. It is confirmed that with an increased thickness of the graded interfacial layer of the Pb ion-plated coating, the coating endurance life is extended remarkably.     

The Difference in Running-In Period and Friction Coefficient Between Self-Mated Si3N4 and SiC Under Water Lubrication

Running-in periods and friction coefficients of SiC and Si₃N₄ sliding against themselves under water lubrication were investigated with a pin-on-disk apparatus at sliding speed of 120 mm/s and a normal load of 5 N under ambient conditions. It was found that the running-in period of self-mated Si₃N₄ is much shorter than that of self-mated SiC, and also that the steady-state friction coefficient of self-mated Si₃N₄ was lower (0.0035) than that of self-mated SiC (0.01). The difference in mechanism was analyzed from the point of view of electronic structure and surface chemistry.     

Dependences of the Oxygen Reduction Reaction Activity of Pd–Co/C and Pd–Ni/C Alloy Electrocatalysts on the Nanoparticle Size and Lattice Constant

Carbon-supported Pd-based binary alloy electrocatalysts (Pd–Co and Pd–Ni) with different particle sizes for polymer electrolyte fuel cells were prepared by a NaBH₄ reduction method and investigated to examine effects of the size and lattice constant of the Pd alloy nanoparticles on the oxygen reduction reaction (ORR) activity. The particle size and lattice constant were controlled in the wide ranges 4.2–12.1 and 0.3802–0.3948 nm, respectively by heating the catalysts in specific atmospheres. The alloy structures were characterized by X-ray diffraction, transmission electron microscopy and X-ray absorption fine structure. The electrochemical tests of the Pd–Co/C and Pd–Ni/C catalysts were performed by cyclic voltammetry and rotating disk electrode in 0.1 M HClO₄. Nearly linear relationship between the lattice constant and nanoparticle size was observed with the Pd–Co and Pd–Ni nanoparticles. The nanoparticle sizes and lattice constants of the Pd–Co/C and Pd–Ni/C electrocatalysts, which influence the Pd d-band center, showed positive and inverse relations with the ORR specific activities, respectively. The mass activities of the Pd–Co/C and Pd–Ni/C electrocatalysts showed an increasing trend with the lattice expansion.     

Comparative studies on the distribution of quinoidal chalcone pigments in the extracts from insect wastes and intact tissues of dyer''s saffron florets

Summary Distribution of quinoidal chalcone pigments in aqueous extracts from insect wastes and intact tissues of dyer's saffron (C. tinctorius) florets was compared by applying HPLC techniques. The analytical data indicated that the polyoxychalcone constituents are not seriously changed even after exposed to the insect digestion. The findings endorse the possibility that the spoiled florets can be used safely as raw materials for preparation of red and/or yellowCarthamus dyes.

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Vergleichende Studien über die Verbreitung von Chininchalcon-Pigmenten aus Insektenabfall und intakten Geweben von Safranblütenfarben

Zusammenfassung Die Verbreitung von Chininchalcon-Farbstoffen aus Insektenabfall und intakten Safranblütenfarben (C. tinctorius) wurde mit der HPLC-Technik verglichen. Die analytischen Daten weisen darauf hin, daß die Polyoxychalcon-Bestandteile nach der Verdauung durch Insekten nicht wesentlich verändert worden sind. Dieser Befund bekräftigt die Möglichkeit, daß die geraubten Blüten als Rohmaterial für die Herstellung von roten bzw. gelben Carthamus-Farbstoffen dienen können.

     

Loads carrying capacity map for the surface texture design of SiC thrust bearing sliding in water

Water lubricated silicon carbide is expected to be widely used for sliding bearings and mechanical seals in hydraulic systems since it is environmentally friendly and saves energy. The purpose of this study is to find the optimum surface texture to improve the load carrying capacity of SiC bearings working in water. Micro-pits, evenly distributed in a square array, were selected as the texture pattern, and formed on one of the contact surfaces by reactive ion etching. Experiments, which simulate the working condition of thrust bearings, were carried out to evaluate the effects of the micro-pits on the critical load of the transition of the lubrication mode from hydrodynamic to mixed. The results are summarized in the form of a load carrying capacity map. It was found that an optimum geometric and distributive range of micro-pits exists, where the load carrying capacity can be increased at least twice over that of an untextured surface.