Design of an indirect-cycle fast breeder reactor cooled by supercritical steam

The neutronic feasibility of a large-sized FBR cooled by supercritical steam is assessed for finding the way to reduce the costs of FBR plants. A negative coolant void reactivity is realized without much deterioration in breeding capability, by our novel concept of inserting thin zirconium-hydride layers between the seed and blanket of the radially heterogeneous core. The gross electric power is 1040 MWe. The estimated equilibrium compound system doubling time is 16 years. The discharge burnup is 78.7 GWd/T and the refueling period is 1 year with a 77% load factor. Compared with the conventional steam cooled FBR, the pumping power fraction is reduced due to the high coolant density of supercritical water. Loeffler boilers for generating steam are not neccessary. The reactor system is simplified and similar to a PWR. The thermal efficiency is 39.6%, improved 15% relatively from PWR's. The pressure vessel is 32.5 cm thick.     

Focus on prevention

Cardiovascular disease in Canada is estimated to cost over $1.2 billion each year. Advances made in the treatment of cardiovascular diseases have decreased the mortality rate associated with them, but the incidence of such diseases may nonetheless be termed epidemic. Leading epidemiologists suggest that control of this epidemic can only be attained through primary prevention....     

Free D-serine, D-aspartate and D-alanine in central nervous system and serum in mutant mice lacking D-amino acid oxidase

We have examined whether D-amino acid oxidase (DAO) regulates free D-serine content using mutant ddY/DAO- mice lacking DAO activity. We find that the content of D-serine in the serum and cerebellum of mutant mice is much higher than that of normal mice, whereas a slight but significant difference in the cerebral D-serine level is observed between the two strains. These results suggest that, although DAO may participate in the catabolism of D-serine in the cerebellum and periphery, there appears to be other mechanisms for catabolism of endogenous D-serine in the brain.     

High-speed InGaP/GaAs transistors with a sidewall base contactstructure

We have fabricated InGaP/GaAs double heterojunction bipolar transistors with a sidewall base contact structure. These transistors operate in both emitter-up and emitter-down modes. Symmetric characteristics of the cutoff frequency f_T=68 GHz and the maximum oscillation frequency f_max=31 GHz were obtained at a base-collector bias V_BC of 0 V. For emitter-down operation, f _T was found to reach a maximum of 78 GHz when the base-collector junction was forward biased at 0.9 V. The product of f _T for emitter-down operation and f_T for emitter-up operation was 5.3×10³ GHz², which is about six times that of previously reported SiGe heterojunction bipolar transistors     

Expression of perforin in nasal lymphoma. Additional evidence of its natural killer cell derivation

Eight patients with nasal lymphoma in whom fresh-frozen tissues were available were studied to elucidate the nature of the lymphoma cells. Two cases were diagnosed as diffuse, large cell lymphoma, and the remaining six cases as diffuse, mixed cell types. Immunohistochemical studies revealed that all of the cases were positive for perforin, which is a specific marker for cytotoxic T or natural killer (NK) cells. As all of the cases were CD8 negative, the perforin-positive finding further confirmed the concept that nasal lymphoma is a distinct neoplastic entity derived from NK or NK-related cells. Light microscopic immunohistochemical studies revealed that these nasal lymphoma cases could be classified into Leu19(CD56)+Leu4(CD3)+ (two cases) and Leu19(CD56)+Leu4(CD3)- (six cases) types according to the phenotypes of the proliferating cells. However, simultaneous staining for perforin and Leu4 (CD3) using immunoelectron microscopy on the Leu19+Leu4+ cases showed that the perforin-positive cells were different from the Leu4-positive cells. This finding suggests that the Leu4-positive cells are not neoplastic NK cells but reactive T cells. Six cases were positive for EBER-1 by in situ hybridization analysis. This finding reconfirms the previous studies that Epstein-Barr virus plays a significant role in the pathogenesis of nasal lymphoma.     

Results of the CCLSG high risk ALL 874 protocol in childhood acute lymphoblastic leukemia. Children's Cancer and Leukemia Study Group

One hundred and eighty eight children with acute lymphoblastic leukemia (ALL) were treated in a Children's Cancer and Leukemia Study Group high-risk ALL 874 study from April, 1987 to September, 1991. These patients received a four-drug induction regimen followed by the early consolidation regimen, cranial irradiation at 6 months of remission and three years of continuation therapy with rotational administration of four drugs. The patients were randomized into two regimens. In regimen A, the consolidation chemotherapy consisted of the intermediate dose cytosine arabinoside (Ara-C), cyclophosphamide (CPM) plus 6MP, and in regimen B, it consisted of high-dose Ara-C plus CPM. Regimen A was given to 106 patients and 82 patients received regimen B. The complete remission induction rate for regimen A and B was 89.4% (93/104) and 98.7% (78/79), respectively. The 3-year event-free-survival (EFS) rate was 70.6% for regimen A, which was higher than the 56.7% for regimen B. The 3-year EFS rate was 44.4% for the 53 patients with an initial leukocyte count > or = 10 x 10(4)/microliters and 72.2% for 132 patients with a leukocyte count < 10 x 10(4)/microliter. We considered that Ara-C plus L-asp, added to the conventional high-risk ALL 811 protocol, improved the prognosis of the high risk ALL patients. However, further intensive chemotherapy was required for improvement of the outcome of the patients with hyperleukocytosis (> or = 10 x 10(4)/microliters).     

Low temperature aging of the freshly formed martensite in an Fe-Ni-C alloy

Aging regime, below and at room temperature, of the martensite formed in an Fe-24.67Ni-0.87C (mass pct) alloy (M _s = 160 K) is studied by using a poly crystalline X-ray diffraction technique. Parameters such as tetragonal axial ratio, unit cell volume, intensity ratios of the tetragonal doublet peaks,etc. are obtained for various degrees of aging. At temperature below ∼200 K, where the carbon atoms can shift only into their neighboring sites, the variation of the parameters indicates some discrepancies with the existing models. At room temperature, a new peak appears in between the tetragonal doublet peaks. This peak and the variation of the parameters at room temperature are explained in terms of carbon cluster formation. Formerly Graduate Student, Tottori University.