Near-ultraviolet light-emitting diodes based on σ-conjugatedlinear silicon-backbone polymers

We report the basic device characteristics of light-emitting diodes (LEDs) based on linear silicon-backbone polymers, polysilanes, with a view to the possibility of employing them as an emissive material in a solid-state light source in the near-ultraviolet (NUV) or ultraviolet (UV) region. The LEDs we fabricated have a single-layer structure consisting of a thin film of polysilane polymer, together with an indium-tin-oxide (ITO) and metal electrode for the injection of holes and electrons, respectively. The device characteristics of these LED's depend strongly on the nature of the polysilane, reflecting its chemical, optical and electronic properties. Efforts to optimize the emissive polysilane have led to the successful fabrication of single-layer LEDs that emit NUV light of 407 nm (3.05 eV) with a quantum efficiency of 0.1% photons/electron and a spectral bandwidth of less than 15 nm (0.11 eV) at room temperature (RT). Future improvement in the device characteristics of NUV-LEDs or UV-LEDs based on polysilanes are discussed in terms of the fundamental properties of polysilanes and the device structure     

汽车发动机用温压粉末冶金链轮的开发

自1994年推广温压以来，已开发了几个新的温压粉末冶金零件，可是，迄今主要用途一直局限于机械工具与农业机具零件，仅开发了几个用温压制造的汽车零件。特别是尚未开发出发动机零件。在这种情况下，我们研究了温压粉末冶金材料的力学性能与耐磨性，并开发出了温压粉末冶金发动机链轮。还说明了控制粉末温度的方法。     

Aneurysm of a branch of the subclavian artery with multiple arteriovenous fistulae

A rare case is reported of an 83-year-old woman with an aneurysm of a branch of the subclavian artery with multiple arteriovenous fistulae. The patient was admitted to our hospital with a pulsatile mass in the supraclavicular space and a prominent continuous murmur which radiated to the anterior chest, right forearm and right neck. She first noticed a pulsatile 2 cm mass in 1972, 1 year following a subtotal gastrectomy. At that time, she had intravenous therapy through a right neck vein. In 1993, the mass became larger, and she developed a shunt murmur. Digital subtraction angiography (DSA) demonstrated an aneurysm of the right subclavian artery and an arteriovenous fistula between the right subclavian artery and vein. The right common carotid artery and right subclavian artery arose from the aortic arch separately. The aneurysm arose from a branch of the subclavian artery which may be the costocervical trunk. The 5 x 4 cm aneurysm was resected and the arteriovenous fistula was divided. On postoperative day 5, a new murmur was ausculated. A repeat DSA detected a new fistula between the axillary artery and vein. Reoperation was performed to ligate and divide the fistula. Pathological examination revealed an atherosclerotic aneurysm.     

Selective detection of biogenic amines using capillary electrochromatography with an on-column derivatization technique

A selective detection method for biogenic amines present in highly complex matrixes was devised by employing both electrokinetic injection and on-column-derivatization capillary electrochromatographic methods. The on-column derivatization capillary electrochromatography system was evaluated by use of a capillary column (total length of 45 cm, effective length of 25 cm) fabricated using a 100-mcirom (i.d.) fused-silica capillary tube packed with 5-microm (i.d.) ODS particles that were tolerant of an alkaline environment. The column was filled with a run buffer consisting of a derivatization reagent, o-phthalaldehyde/2-mercaptoethanol, in a mixture of borate buffer (pH 10). After electrokinetic injection of a mixture of five biogenic amines (histamine, serotonin, tyramine, putrescine, cadaverine) as a test sample, the free amines entered into the anodic site of the capillary column and started to travel along the column, during which time the analytes reacted with the derivatization reagent, separated out, and were detected with an absorbance at 340 nm when high voltage was applied to the column. When this system was applied to a mixture containing 5 biogenic amines and 17 amino acids, the 5 biogenic amines plus arginine selectively entered into the capillary with the electrokinetic injection and were observed on the electrochromatogram, but none of the amino acids lacking arginine were detected. The designated method was also tested for its ability to determine the presence of biogenic amines in the crude extracts obtained from two types of aged fish.     

Queueing-Delay Formula for Common-Channel Signaling Systems

An approximate queueing model for common-channel signaling systems has been developed and the queueing-delay distribution has been obtained. As a special case, the approximate average queueing-delay formula for common-channel signaling systems has been derived. By simulation, it has been ascertained that this formula is reasonably accurate.     

Field survey of pollutants discharged from different types of residential area in the Yamuna River Basin, India

The Ganges River, one of the most heavily populated and urbanized river basins in Asia, is polluted by increasing wastewater influent and water-borne diseases are caused in the metropolitan area. This study focused on the Yamuna River, a major tributary of the Ganges. We determined the pollutant load per unit of urban area classified by the income of the residents to help design an appropriate sewerage system. In addition, a simple method of estimating runoff pollutant load was examined using data on pollutant load per unit and runoff coefficient.