Nitrogen solubility in CaO-CaF2-SiO2 melts

The preceding paper^[5] demonstrated that nitrogen dissolves in silicate melts either as a free ion or complex anion, being incorporated into silicate networks. In the present study, the influence of CaF₂ addition to CaO-SiO₂ melts on the nitrogen solubility was investigated along the liquidus at 1573 K and within the liquidus at 1723 K at constant CaF₂ levels. In the latter case, as the SiO₂ content increases from CaO saturation, the total nitrogen content decreases to reach the minimum and then starts to increase up to the SiO₂ saturation. This is in accord with the abovementioned mechanism of nitrogen dissolution, which is supported by the changing behavior of free and incorporated nitrogen contents with the slag composition. The role of CaF₂ is complicated through the formation of fluorosilicates. The CaF₂ seems not to function simply as a diluent but to enhance the dissolution of nitrogen by releasing oxygen from silicate networks, promoting the formation of free nitride ions. Formerly Graduate Student, Department of Metallurgy, The University of Tokyo.     

Degeneration at the insertion weakens the tensile strength of the supraspinatus tendon: a comparative mechanical and histologic study of the bone-tendon complex

The purpose of this investigation was to determine the relationship between the degree of degeneration at the supraspinatus insertion, the tensile strength, and the site of failure of this tendon. Thirty-three fresh cadaveric shoulders (average age: 62 years; range: 39-83 years) were examined. A tensile load to failure was applied at a constant crosshead speed of 25.4 mm/min to a 10 mm wide strip of the supraspinatus tendon that remained attached to the bone. Preexisting degenerative changes at the insertion were assessed and scored histologically and compared with the ultimate tensile stress. Twenty tendons failed at the insertion (the insertion group), and 11 failed in the midsubstance (the midsubstance group). The histologic score of degeneration for the insertion group was significantly higher than that for the midsubstance group (p = 0.0026). There was a negative correlation between the ultimate tensile stress at the insertion and the degeneration score for the insertion group (r = -0.60; p = 0.013). Histologic observations revealed that disruptions of tendon fibers were located mostly in the articular half of the tendon and that they enlarged during mechanical testing in 90% of the specimens of the insertion group. It seems that degenerative changes at the supraspinatus insertion reduce the tensile strength of the tendon and constitute a primary pathogenetic factor of rotator cuff tear.     

A super-dynamic flip-flop circuit for broad-band applications up to24 Gb/s utilizing production-level 0.2-μm GaAs MESFETs

This paper describes a novel dynamic flip-flop (FF) circuit that can operate 30% faster than conventional clocked inverter-type FFs. A new wideband clock buffer is introduced to cover the FF operation range. An 8- to 24-Gb/s decision circuit and a 9- to 26-GHz 1/2 frequency divider were developed utilizing production-level 0.2-μm GaAs MESFET technology     

Fabrication of damascene Cu wirings using solid acidic catalyst

The copper damascene process is one of the most promising technologies for fabricating Cu wirings for electronic devices such as LSIs. In this research, the fabrication of damascene Cu wirings was conducted using solid acidic catalyst. When a Cu-plated wafer, whose oxide is a basic oxide is dipped into a mixture of oxidizing solution and acidic solution, surface atoms are ionized and etched off into the solution. However, because conventional nonelectrolytic etching does not have a reference surface, it is difficult to utilize for planarization. Therefore, a new nonelectrolytic machining method using a cation-exchange fabric instead of an acidic solution was developed. To be more precise, the planarization of a Cu-plated wafer was carried out by rubbing with the cation-exchange fabric in ozone water. Basically, this method exploits chemical reactions so that the physical properties of the workpiece surface are not deteriorated. Furthermore, this method uses no chemicals except for ozone water, which easily dissociates into water and oxygen molecules; thus, this method is a low-cost, environmentally friendly process. In this paper, as a preliminary experiment, the nonelectrolytic etching of a Cu sample using solutions of O₃ and CO₂ was carried out to inspect the dependence of the etching rate on [O₃] and [H⁺]. The results indicate that the etching rate increased as [O₃] and [H⁺] increased. When [H⁺] was high relative to [O₃], a smooth etch-pit-free surface was achieved. Next, nonelectrolytic etching using a cation-exchange fabric was carried out, and properties similar to those in the case of etching using solutions were obtained. Finally, damascene Cu wirings were fabricated using ozone water and a cation-exchange catalyst.     

Automatically Controlled 2-Vessel Pressure-Cooker Test-Equipment

A highly accelerated humidity test for plastic encapsulated IC reliability short-term evaluation has been studied. 2-Vessel pressure cooker test (PCT) equipment capable of controlling relative humidity and temperature independently, and of keeping specimens free from water droplet condensation, has been designed. This equipment consists of a test chamber and a vapor chamber. Humidity conditions are set by controlling the temperature difference between the test chamber and the vapor chamber. Humidity levels are controlled with the direct pressure adjustment. The whole test chamber is heated in an oven, thereby obtaining temperature stability and uniformity. Using this equipment, humidity tests were carried out on plastic molded ICs. As a result, good test reproducibility and excellent correlation in test results between PCT and conventional humidity test such as 85°C/85%RH, were obtained. As a consequence, it was found possible, in a short time, to evaluate plastic molded IC reliability quantitatively in humidity ambients using this 2-vessel PCT equipment. This equipment can be used for quality assurance testing of plastic-encapsulated ICs in a short time.     

A 322 MHz random-cycle embedded DRAM with high-accuracy sensing and tuning

A 16 Mb embedded DRAM macro in a fully CMOS logic compatible 90 nm process with a low noise core architecture and a high-accuracy post-fabrication tuning scheme has been developed. Based on the proposed techniques, 61% improvement of the sensing accuracy is realized. Even with the smallest 5 fF/cell capacitance, a 322 MHz random-cycle access while 32 ms data retention time which contributes to save the data retention power down to 60 /spl mu/W are achieved.     

Thermodynamics of antimony,arsenic, and tin in CaO—CaF2 melts

In view of the importance of tramp element contamination of steel products through a large volume of scrap consumption in the near future, the thermodynamic behaviour of Sb, As, Sn and Cu in CaO—CaF₂ melts under reducing conditions was studied by examining the dependences of distribution of each element between Cu, Ag or Sn alloys and CaO—CaF₂ melts on the CaO activity, oxygen partial pressure and temperature around 1 500°C. As a result, the reaction products on treatment by Ca compounds were demonstrated to be Ca₃Sb₂, Ca₃As₂, Ca₂Sn and CaCu. Experimentally obtained distributions were extrapolated to lower oxygen partial pressures less than 10^?18 atm to estimate the feasibility of removing those tramp elements from molten iron. It is thermodynamically indicated that if the prevailing oxygen partial pressure of the environment is below 10^?23 atm, these impurities, except Cu, would be substantially removed from molten steel.     

Low-power 1:16 DEMUX and one-chip CDR with 1:4 DEMUX using InP-InGaAs heterojunction bipolar transistors

Using InP-InGaAs heterojunction bipolar transistor (HBT) technology, we have successfully designed and fabricated a low-power 1:16 demultiplexer (DEMUX) integrated circuit (IC) and one-chip clock and data recovery (CDR) with a 1:4 DEMUX IC for 10-Gb/s optical communications systems. The InP-InGaAs HBTs were fabricated by a nonself-aligned process for high uniformity of device characteristics and producibility. The 1:16 DEMUX IC and the one-chip CDR with the 1:4 DEMUX IC consist of approximately 1200 and 460 transistors, respectively. We have confirmed error-free operation at 10 Gb/s for all data outputs of both ICs. The 1:16 DEMUX IC and the one-chip CDR with the 1:4 DEMUX IC consume only 1 W and 950 mW, respectively. These results demonstrate the feasibility of InP-InGaAs HBTs for low power high-integration optical communication ICs.     

EM574, an erythromycin derivative, is a potent motilin receptor agonist in human gastric antrum

Erythromycin and its derivatives are known to induce phase III-like contractions, which are similar to those induced by motilin, in the human gastrointestinal tract during the interdigestive state, but few detailed in vitro studies have been reported. We evaluated EM574, an erythromycin derivative, as a motilin receptor agonist in the human gastric antrum in vitro, using contraction studies of muscle strips and isolated myocytes, receptor binding assay and tissue section autoradiography. EM574 stimulated contractions of muscle strips in a concentration-dependent manner (10(-7)-10(-5) M), and this contractile effect was unaffected by pretreatment with atropine or tetrodotoxin. Isolated myocytes contracted in response to EM574 with a peak shortening at 10(-7) M, which was comparable to the response to motilin. EM574 displaced specifically 125I-motilin bound to smooth muscle homogenates with a Kd value of 7.8 x 10(-9) M, compared with 4.5 x 10(-9) M for motilin. Film autoradiograms showed that 125I-motilin-binding sites were localized in the muscle layers, and that the labeling disappeared in the presence of a 1000 times molar concentration of EM574. We conclude that EM574 directly stimulates smooth muscle cell contraction by acting on motilin receptors in the human gastric antrum in vitro.     

Malignant mesenchymoma in the scrotum. A case report

A 67-year-old man visited our hospital with the chief complaint of painless swelling of the left scrotal content. An elastic hard mass was palpable in the left scrotum. Resection of the tumor, including the left scrotal skin, was performed. The tumor originated from the scrotal wall and did not communicate with the testis, the epididymis or spermatic cord. Histologically, the tumor was diagnosed as a malignant mesenchymoma composed of liposarcoma, chondrosacoma and osteosarcoma. Malignant mesenchymoma is very rare, especially in the scrotum. Our case that originated from the scrotal wall is the first one reported in Japan.