A single-phase three-wire watt-to-pulse frequency converter usingsimple PWM and its accuracy analysis

Many types of electronic watthour meters have been developed; however, they are complicated and expensive for household meters. Therefore, cutting cost of the meters has been required especially for the most popular single-phase three-wire (one-phase three-wire) system in Japan. For this purpose, the authors developed a very simple one-phase three-wire watt-to-pulse frequency converter (W-F converter) for the watthour meter. In this new converter, a general-purpose one-chip quad operational-amplifier (op-amp) IC is used as a main component of the converter, for lower initial cost without a custom IC. As the one-chip quad op-amp IC has four op-amps, two op-amps are used for two watt sensors, and the other two op-amps for a de current-to-pulse frequency converter (I-F converter). The watt sensor uses a multiplier using an approximate pulse-width modulation (APWM) with only a comparator with hysteresis and a CR circuit, replacing the conventional Miller integrator which needs an op-amp. Therefore, the total number of op-amps of the developed one-phase three-wire W-F converter is reduced to four, obtained by one one-chip IC. Although the APWM has nonlinearity, it is negligible without instability. As the converter developed does not need any special custom IC or component and is very simple, the total cost can be very low     

Preoperative diagnosis of the thoracic aortic aneurysm by three-dimensional CT angiography

Serial eight patients with thoracic aortic aneurysms were evaluated by a newly developed three-dimensional CT angiography (3D-CT) from December 1992 to January 1993. The patients include 3 aortic dissections, 3 aortic arch aneurysms, one descending aortic aneurysm and one thoracoabdominal aortic aneurysm. The surgical treatment was performed after the evaluation of 3D-CT, and the operative findings were compared to the three-dimensional images reconstructed by 3D-CT in all patients. Three-dimensional displays were achieved using the unique method of data collection of the helical (spiral) scanner with continuous tube rotation and continuous table feed. A intravenous contrast material was used to image the thoracic aorta and major aortic branches with the single-breath-hold technique. Two and three-dimensional images reconstructed by 3D-CT were displayed within 10-20 minutes after the scanning. These three-dimensional images of the aortic lesions could be displayed in any angle we chose. Three-dimensional structures of the thoracic aorta and major aortic branches were clearly visualized and easily recognized by 3D-CT. These images were similar to the intraoperative findings and were quite useful to determine the operative procedure. The successful repair of thoracic aortic aneurysm was achieved in all cases. 3D-CT is a new and attractive modality to assess the vascular system. Although our experience is limited, 3D-CT may be a useful and powerful diagnostic method for the surgical treatment of thoracic aortic aneurysm.     

Chemical constituents of original plants of Cimicifugae rhizoma in Chinese medicine

Cimicifugae Rhizoma have been used as an anti-inflammatory, analgesic and antipyretic remedy in the traditional Chinese medicines. Many 9,19-cyclolanostane glycosides have been isolated from Cimicifuga and related genera. Two biogenetically key compounds, acetylshengmanol xyloside and cimicifugoside H-1, were isolated and their chemical structures were elucidated by our group. The former compound seems to be the parent component of the other glycosides such as cimigenol xyloside from C. dahurica, C. iaponica and C. acerina. The latter glycoside, cimicifugoside H-1 was isolated together with cimicifugosides H-2-H-6 from commercial Cimicifugae Rhizoma. They are novel glycosides having a hydroxyl group ay C-11, and cimicifugosides H-3, H-4 and H-6 were trinor-triterpenol glycosides. Cimicifugoside H-1 changed into H-2, H-3 and H-4 under acidic or alkaline conditions. In this review, the structure elucidation of the above glycosides and their chemical transformation into other Cimicifuga glycosides are described.     

Fabrication of broad-area laser diodes on a three-inch wafer by asolid-phase diffusion method

We have developed extremely uniform Zn diffusion on a three-inch GaAs-AlGaAs QW laser wafer by an open tube solid-phase diffusion technique and have applied it to fabrication of broad-area laser diodes (LD's) for the first time using 3-inch full-wafer processing. Excellent uniformity of device characteristics have been obtained on a 3-inch wafer; threshold current distribution along the radial direction of a wafer is 356.2±8.3 mA (1σ), emission wavelength is 879.7±0.6 nm (1σ). Such high uniformity is caused by not only uniform Zn diffusion but also uniform epitaxial layer thickness over a three-inch wafer     

Primary hyperparathyroidism associated with multiple myeloma

A 73-year-old woman was diagnosed as primary hyperparathyroidism. Hypercalcemia recurred after parathyroidectomy, though serum calcium concentration temporarily resumed to normal. Hypercalcemia was eventually shown to be due to multiple myeloma. In spite of the frequent association of hypercalcemia with malignant disease and the relative frequency of primary hyperparathyroidism as a cause of hypercalcemia, primary hyperparathyroidism accompanied by multiple myeloma has been considered in only a limited number of reports. Here, the cases in the literature are reviewed and discussed.     

CW operation of 1.5 ?m InGaAsP/InP BH lasers with a reactive-ion-etched facet

The reactive-ion-etching (RIE) technique utilising a TiO2 mask and Cl2-Ar gas is successfully applied to facet mirror fabrication of 1.5 ?m InGaAsP/InP buried-heterostructure (BH) lasers. Room-temperature CW operation has been achieved with a structure having one etched and one cleaved facet. A threshold current value of 30 mA at 25°C has been achieved for a laser with a 380 ?m cavity length.