Experimental identification of the phenomenon triggering the net vapor generation in upward subcooled flow boiling of water at low pressure

Observation of the bubble behavior was made using a high-speed camera to investigate the mechanisms to cause the net vapor generation in subcooled flow boiling. In the experiments, water was used as the test fluid, the flow direction was vertical upward, and the pressure was kept close to the atmospheric pressure. At high liquid subcooling close to the condition of the onset of nucleate boiling, all the bubbles were lifted off the heated surface immediately after the nucleation to disappear quickly in the subcooled bulk liquid due to condensation. It was found that the void fraction did not increase significantly unless the liquid subcooling became low enough for some bubbles to be reattached to the heated surface after the lift-off. When the reattachment took place, the bubble lifetime was substantially elongated since the bubbles slid up the vertical heated surface for a long distance after the reattachment. The reattachment therefore contributed to an increase in the void fraction. It was concluded that in the experimental conditions tested in this work, the bubble reattachment to the heated surface was a key phenomenon to cause the sharp increase of the void fraction at the point of net vapor generation.     

Development of novel Ru catalyst of preferential CO oxidation for residential polymer electrolyte fuel cell systems

CO preferential oxidation on a novel Ru catalyst greatly improved in activity and selectivity over a wide temperature range by the pre-treatment of H₂ reduction was characterized. The high performance was obtained by increasing the population of surface Ru(0) which improved O₂ activation at low temperatures. Methanation of CO on the catalyst can also contribute to the final CO clean-up from ca. 100 to <1 ppm at low temperatures where the influence of CO₂ methanation can be ignored.     

Digital input filters for measurement,control and protection in electric power systems

Power system control and protection equipment is subject to especially stringent sensitivity and operational reliability requirements. Projected digital signal processing systems suitable for electric power systems fulfill these requirements by means of fast sampling and digital filtering by a 32-bit floating point DSP (Digital Signal Processor). The sampling rate of 3 kHz is carefully selected in order to separate the power spectra of the A-D conversion output errors from the signal bandwidth. The new 12-bit A-D conversion unit equipped with a recursive-type digital filter achieved a high resolution equivalent to 14-bit conversion. This paper describes the design concept and the operating characteristics and illustrates applications to current differential relays, distance relays and power system controllers.     

Hyperattenuating rim on noncontrast CT of the liver: probable peritumoral sparing of fatty infiltration

CT scans showing a hyperattenuating rim within the liver were retrospectively evaluated in 10 patients to clarify the character, aetiology and clinical significance. All patients had hepatic tumours (7 cavernous haemangiomas in 6 patients, 3 metastatic tumours and 1 hepatocellular carcinoma) as well as fatty infiltration of the liver. Typical features of the hyperattenuating rim on noncontrast CT of the liver included (1) attenuation similar to that of the spleen, (2) a circular or semicircular shape, (3) a width of a few millimeters, (4) peritumoral localization and (5) loss of visualization with contrast enhancement. No such rims were noted around hepatic tumours unassociated with fatty infiltration. Peritumoral sparing of fatty infiltration was inferred. A hyperattenuating rim on noncontrast liver CT, although rare, suggests the presence of a hepatic tumour in fatty liver.     

Significant improvement of luminance and stability of a red electroluminescent device using nanocrystalline silicon

An electroluminescent (EL) device using nanocrystalline silicon (nc-Si) was fabricated by annealing after cosputtering of Si chips and silicon dioxide target and subsequent hydrofluoric acid solution treatment. The device emitted a red light with a peak at 670 nm by applying a low direct current (DC) operating voltage of 4.5 V. The external quantum efficiency (EQE) of red luminescence at 4.5 V was 0.35%. Moreover, the intensity of red luminescence was very stable for an operating time of 15000 min. These results are a strong indication that the HF-treated device can be adapted to future light-related devices.     

国外技术人员资格和技术人员教育认定制度的现状

世界贸易组织（WTO）制订了关于专门技术服务的协定（GATS）.为了便于技术人员的国外服务,有必要建立国际间技术人员资格和教育体制的相互承认制度.本文概述各地区和国家的技术人员教育认定工作和相互承认的现状,并作为实例简要介绍了美国技术人员教育程序认定工作的考察情况.     

亲肿瘤显像剂5-18F-Fluorouracil(18F-FU)的标记合成研究

用^18/F2Uracil直接标记法合成了5－^18F-Fluorouracil,探索^18F-FU-PET显像对结肠直肠肝转移病人化疗前后疗效评价的意义。产品的放射化学纯＞95％,放射性得率为60％,pH值为7,无菌性试验和热源性试验为阴性,这一结果为临床应用提供了保证。     

Development of bullous pemphigoid after change of dialysis membrane

A 75‐year‐old Japanese man presented with pruritic blisters and macules on his trunk and extremities. He had been on hemodialysis for 4 years because of chronic renal failure, and in recent months, a polymethylmethacrylate membrane had been used for dialysis. After a change in dialysis membrane to a cellulose triacetate membrane, pruritic tense blisters developed on the extremities in combination with marked blood eosinophilia. Physical examination showed erythematous macules and tense blisters on the trunk and extremities. A biopsy specimen of an erythematous macule showed subepidermal vesicles and eosinophils that attached to the dermal–epidermal junction. Serum level of eosinophilic cationic protein was elevated. From clinical, histological, and immunological findings, a diagnosis of bullous pemphigoid was made. New blisters continued to erupt during the period in which the patient used the cellulose triacetate membrane dialyzer, and even after the use of clobetasol propionate. It resolved only after the patient came back to the use of a synthetic membrane dialyzer. We discontinued the use of clobetasol propionate, and neither bullous eruptions nor blood eosinophilia recurred. These observations suggest that cellulose membrane may be involved in the development of bullous pemphigoid through activation of eosinophils in the blood and the skin lesion, as in the present case.