Thermodynamics of Nitrogen in B2O3, B2O3─SiO2, and B2O3─CaO Systems

The BN solubilities for B₂O₃, B₂O₃─SiO₂, and B₂O₃─CaO systems have been measured mainly at 1823 K using a graphite crucible. The capability of the systems for nitrogen dissolution is compared with that of silicate systems in terms of nitride capacity. The dependence of nitrogen solubility in molten CaO containing 15 mol% of B₂O₃ on oxygen and nitrogen partial pressures is also investigated. It has been found that there are two mechanisms for nitrogen dissolution, namely as chemically bonded nitrogen and as physically dissolved nitrogen gas.     

Heat transfer in channel flow around a rectangular cylinder

Heat transfer and flow visualization experiments have been made in a channel with a rectangular cylindrical section having various width-to-height ratios. Vortices were observed to shed periodically from the cylinder and then reattach to the channel wall. This reattachment of the vortices induces a periodic fluctuation in heat flux at the wall and enhances the heat transfer in the downstream region of the cylinder. The streamwise position of the maximum Nusselt number moves downstream with decreasing width-to-height ratio, b/h, of the cylinder. When b/h = 2.0, however, the heat flux periodicity disappears because the wake narrows intermittently owing to reattachment of the separated flows to the upper and lower surfaces of the cylinder. © 1998 Scripta Technica. Heat Trans Jpn Res, 27(1): 84–97, 1998     

Endoplasmic reticulum is missing in dendritic spines of Purkinje cells of the ataxic mutant rat

Dilute-opisthotonus (dop) is a spontaneous ataxic mutation in the rat, regulated by an autosomal recessive gene. Immunohistochemical staining with anti-inositol 1,4,5-trisphosphate receptor antibody and electron microscopic examinations revealed that the endoplasmic reticulum in dendritic spines of Purkinje cell was missing in the ataxic rat. This could impair the intracellular signal transduction in the parallel fiber-Purkinje cell synapse, and be a cause of the severe ataxic movement.     

A novel isoform of the neurofibromatosis type-1 mRNA and a switch of isoforms during murine cell differentiation and proliferation

There are different recommendations for the handling of blood samples for analyses of the kallikrein-kinin or complement system, respectively. C1 inhibitor (C1-INH) takes a crucial part in both systems. In order to establish recommendations for blood specimen collection and transport for making the diagnosis of hereditary angioedema (HAE), the effect of time, temperature and different additives on C1-INH function and antigen was determined. We used blood samples from normals and patients suffering from HAE type I. Plasma containing EDTA, heparin, sodium citrate or polybrene-EDTA, and serum were assayed after incubations at 4 degrees C or 37 degrees C for 6 or 24 h. In addition, pooled serum was incubated for up to 5 days at room temperature. A modest decrease in C1-INH function was observed as an effect of storage-time in samples from normals (p = 0.039) and a substantial decrease was seen for the HAE patients (p = 0.0002). No significant effect of temperature (4 degrees C or 37 degrees C) was found. Clotting did not reduce C1-INH activity. Plasma containing heparin or polybrene interfered with the functional assay, yielding falsely high and low values, respectively. C1-INH functional assay performed within 24 h in serum, EDTA-treated or citrated plasma discriminated well between HAE patients and normals. This was also the case for serum kept at room temperature for up to 5 days, although a modest fall in C1-INH function was seen in the incubation period. For practical purposes we recommend serum as the sample of choice, preferably received within 48 h.     

Continuous hyperthermic peritoneal perfusion for peritoneal dissemination of gastric cancer

BACKGROUND/AIMS: We investigated the histological and clinical effectiveness of continuous hyperthermic peritoneal perfusion (CHPP) for treating peritoneal dissemination (therapeutic CHPP) and for the prevention of peritoneal recurrence (prophylactic CHPP). METHODOLOGY: In 5 patients with gastric cancer and peritoneal dissemination, the apoptosis index of the cancer cells on in situ end-labeling for detection of apoptotic cells was 3.0+/-1.2% before CHPP, and had increased to 52.9+/-8.3% after CHPP. The survival curve of the therapeutic CHPP group was significantly better than that of the control group. The therapeutic CHPP group was classified as miliary type or nodular type. The survival curve in the miliary type was significantly better than that in the nodular type. RESULTS: In prophylactic CHPP, there was no improvement in prognosis, but a prophylactic effect against peritoneal recurrence was demonstrated in the patients who were n4 negative when the mean intraperitoneal temperature during CHPP (MIT) was maintained above 42 degrees C. CONCLUSIONS: These results indicated that an improved prognosis can be expected after therapeutic CHPP in patients with peritoneal spread. The beneficial effects are especially marked in patients with the miliary type. Moreover, prophylactic CHPP exerts a prophylactic effect against peritoneal recurrence in patients with n4 negative, providing that the MIT can be maintained above 42 degrees C.     

Catalytic reforming of gasoline to hydrogen: Kinetic investigation of deactivation processes

Catalytic reforming of gasoline to a hydrogen-rich gas is a possible route to feed a fuel cell for electricity production on-board a vehicle. To properly design a fuel processor system, knowledge about the kinetics of the different reactions involved in the reforming is needed. Kinetic studies are hampered by the fact that sulfur compounds present in commercial gasoline may lead to a progressive deactivation of the catalyst. We have undertaken such a study with an optically accessible catalytic channel flow reactor enabling concentration profiles and catalyst surface temperatures to be measured. The concentration profiles measured at different times on stream revealed a progressive deactivation of the catalyst. Isothermal reaction rate constants, depending on the time on stream, were derived by fitting a Langmuir–Hinshelwood kinetic model to the experimental species concentration profiles. The modeling results indicated that the steam reforming of higher hydrocarbons was more strongly affected by the presence of sulfur in the feed than the water gas shift reaction and the steam reforming of methane. Carbon formation was inferred from changes in surface emissivity during the experiments. It is suggested that the primary reason for the observed deactivation is due to the presence of sulfur compounds in the feed. The deactivated catalyst would then promote the formation of coke at the surface, i.e. coke formation is probably a consequence of the deactivation and not a cause for it. Although the variability in preparing the coated catalytic plates affected the measured kinetic rate parameters, the observed trends were in general consistent for all runs.     

Nucleation kinetics of a Li2O·2SiO2 glass based on a liquid model

A liquid model was proposed wherein crystal embryos should exist in equilibrated melts at temperatures even above the melting point or liquidus temperature and the number density of embryos should decrease as the melting temperature increases. Crystallization behavior of a Li₂O·2SiO₂ glass was studied. Secondary heat-treatment (600 °C for 20–60 min) of the Li₂O·2SiO₂ glass induced different number of crystals depending upon the melting temperature in the range 1040°–1300 °C and duration of heat-treatment t. The number density of crystals N decreased with increasing temperature of melting. The number density of pre-existing embryos was estimated from (N – t) diagram and was found consistent with what the proposed model claims.     

Preparation of rhodium niobate compound by chemical mixing methods: Effect of preparation method on SMSI behavior of RhNbO4/SiO2 catalysts

Rhodium niobate was prepared as a complex oxide supported on silica via tetra-alkyl ammonium and citrate complexation. After calcination at 750 °C, the complex oxide was formed essentially in the monophasic columbite structure as determined by means of XRD. The two silica-supported RhNbO₄ catalysts were tested for their activity toward ethane hydrogenolysis, and a large difference in SMSI behavior was observed for the two preparations.