Dynamic behavior of reaction intermediates on catalyst surfaces in the working state: Behavior of formate ion during the decomposition of formic acid on Ni/SiO2 catalyst

The reactivity of the formate ions on Ni/SiO₂ catalyst was examined during the course of the formic acid decomposition. It is of great interest to note that the reactivity was markedly increased by the presence of formic acid in the ambient gas compared to that at the same coverage under vacuum. It is accordingly suggested that the formate ion behaves as reaction intermediate through the interaction between the formic acid molecules in the ambient gas.     

Pathological appearance of the stomach after endoscopic mucosal resection for early gastric cancer

BACKGROUND: The pathological findings of the resected stomach after endoscopic mucosal resection (EMR) for early gastric cancer were reviewed. EMR was indicated when a lesion consisting of well or moderately differentiated adenocarcinoma had a diameter of less than 2 cm. METHODS: Of 39 patients with early gastric cancer were treated with EMR between 1990 and 1995, 11 required additional surgery. RESULTS: Malignant tissue in the gastric wall was completely removed in four patients, while cancer cells remained in the mucosa adjacent to the scar in five and infiltrated into the submucosa in two. Most of these residual cancers were characterized by a lesion with a diameter exceeding 15 mm and by the location in the body or cardia of the stomach. Lymph node metastases were observed in one patient whose carcinoma invaded the deeper submucosal layer. Assessment of the depth of entire invasion from the endoscopically-resected specimen was correct for six of 11 patients. CONCLUSION: Gastric carcinomas to be resected by EMR should be smaller, especially if located in the body or cardia. Accurate diagnosis of the width and depth of invasion is indispensable before proceeding to EMR. Surgery may be the treatment of choice when there is submucosal invasion.     

Primary biliary cirrhosis associated with idiopathic thrombocytopenic purpura

A case of primary biliary cirrhosis (PBC) associated with idiopathic thrombocytopenic purpura (ITP) is reported. The patient is a 59-year-old man. When he was 49 years old, he was diagnosed with ITP and received steroid therapy that successfully increased platelet numbers. However, the steroid therapy failed to normalize the elevated gamma-glutamyl transpeptidase. Ten years after this episode, he suffered from general itching and malaise and exhibited a gradual increase of serum biliary enzyme levels. Immunologically, IgM was increased and anti-mitochondrial antibody was positive. Histological findings of liver needle biopsy showed chronic non-suppurative destructive cholangitis, confirming the diagnosis of PBC. To date, very few PBC cases associated with ITP have been reported. Our case is the second one in Japan. PBC and ITP in our patient seemed to develop simultaneously, but the effect of steroid therapy on the two conditions was different. This result suggests that the autoimmune process may have been different in PBC and ITP in the present patient.     

Propofol inhibits human neutrophil functions

Neutrophils play important roles in the antibacterial host defense mechanism and in the pathogenesis of tissue injury. Propofol has been reported to impair the production of reactive oxygen species from neutrophils. We examined the effect of propofol (2,6-diisopropylphenol), at clinically relevant concentrations and at 10 and 100 times this concentration, on several aspects of human neutrophil functions using an in vitro system. Propofol significantly inhibited chemotaxis, phagocytosis, and reactive oxygen species (ROS) (O2-, H2O2, OH) production of neutrophils in a dose-dependent manner. At clinically relevant concentrations, propofol suppressed these neutrophil functions, but it did not decrease ROS generation by the cell-free (xanthine-xanthine oxidase) system. Increase in intracellular calcium concentrations in neutrophils stimulated by N-formyl-L-methionyl-L-leucyl-L-phenylalanine was dose-dependently attenuated by propofol. This decreasing effect on [Ca2+]i in neutrophils may represent one of the mechanisms responsible for the inhibition of neutrophil functions by propofol. IMPLICATIONS: Neutrophils play a pivotal role in the antibacterial host defense system and tissue injury. We found that at clinically relevant concentrations, propofol impaired neutrophil functions. Further studies may determine whether this impairment, observed in vitro, leads to clinical immunological suppression.     

THE CHARACTERISTIC EFFECTS OF VARIOUS IRON SULFIDE CATALYSTS IN COAL LIQUEFACTION

In order to investigate the effective mechanism of pyrite catalyst, coal liquefaction was conducted using a 500 ml autoclave. When the chemical structure characteristics of products and product yields are considered as a whole, deoxygenation and dealkylation are found to be enhanced in the presence of pyrite catalyst. Further, it is surmised that depolymerization is faster than the removal of heteroatoms.     

The effects of temperature and liquid crystalline polymer (LCP) on mechanical properties of a blend of polyphenylene sulphide and LCP

The mechanical properties of polyphenylene sulphide (PPS) and liquid crystalline polymer (LCP) blends were investigated over a range of temperatures. The effect of blend composition on the brittle-ductile transition temperature (B-D) was also studied by differential scanning calorimetry and scanning electron microscopy. Blends of various compositions (PPS/LCP; 90/10, 75/25, 50/50 and 25/75) were prepared and injection moulded. The bending test temperature was varied between –40 and 150 °C. The results showed a rapid load drop at the B-D transition region. The B-D transition temperature occurred in unannealed pure PPS, 90/10, 25/75 and 50/50 blends around 75 °C whilst in the annealed sample it was observed around 100 °C. In pure LCP and 25/75, no transition occurred. Partial miscibility of PPS and LCP was confirmed by SEM observations, bending modulus and thermal properties. The use of LCP, as a good reinforcing agent which can improve processability and modulus, is discussed.     

Ku-band long distance site-diversity (SD) Characteristics using new measuring system

This paper deals with the short (10 km) and long distance (300-1400 km) site-diversity (SD) characteristics by using a newly developed measuring system. In the proposed measuring system, six earth stations transmit 14-GHz band QPSK signals, and one measuring earth station receives 12-GHz band signals and processes them to determine SD characteristics. As a result, easy operation and maintenance, low-cost measuring system construction and highly accurate data have been obtained. By comparing those measured results with the SD joint probability approximation equation in ITU-R Rec.P.618-7, a good agreement can be obtained. Furthermore, the effect of typhoons on SD characteristics were measured.     

Double exposure stabilization of positive photoresist

Positive photoresists appeared to be the most promising material in VLSI microfabrication for ten or more years from now. Thus, processing know-how needs to be accumulated continuously. This work deals with thermal characteristics of positive photoresist. The following facts were declared experimentally. The quinone diazide, photosensitizer, was thermally decomposed at around 140°C to release N₂. Simultaneously the surface layer of resist film was changed into innert state, called as ‘husk’, with low gas permeability and high chemical resistance. These thermal changes in resist film affect the photoresist to SiO₂ adhesion. In this work a noble process, named double exposure stabilization, is developed to get sufficient chemical resistance and good adhesion simultaneously.     

A new numerical modeling for laminated composites

Recently, with increasing interest in the performance of fiber reinforced laminated composites, various behaviors of these materials have been simulated by the finite element method (FEM). However, conventional models are not good enough to simulate behaviors of laminated composites. The main reason is that the laminated composite is modeled by assuming it to be a homogeneous object though it has a heterogeneous nature. In this paper, the new numerical modeling for laminated composites was proposed. In order to check the validity of the proposed model, elementary simulations were performed and compared with theoretical results. Moreover the application of the proposed model to the laminated composites with interlaminar delamination was discussed.     

Strength analysis for three-dimensional fiber reinforced composites

Three-dimensional fiber reinforced composite materials produced by impregnating resin into woven fabric have superior interlaminar and impact strength and are capable of being formed into complex shapes. Consequently it is expected in the future that they will be used for various structural members which have to date been difficult to make with conventional composite materials. With the growth in their fabrication technoloy, the development of a strength analysis method is being demanded. This paper describes a strength analysis method for three-dimensional composite materials on the basis of a micro-mechanical analysis of a unit cell. The unit cell is a small geometrical unit of fiber architecture. A feature of the present analysis method is to represent a unit cell as a rigid frame structure constructed of fiber-beam elements and matrix-beam and matrix-rod elements. Strength analyses are made for orthogonal weave and 5-axial weave three-dimensional carben/epoxy composite materials; the tensile, compressive, and shear moduli and strengths, and Poisson's ratio are calculated. The analytical results show fairly good agreement with experimental results; 11%, 21%, and 20% differences between them on the average for elastic moduli, strengths, and Poisson's ratios, respectively. It is also understood that the present idealized analysis model cannot accurately predict the characteristics of undulated fiber composites, especially in respect to the compressive strength.