Suppression of 3C-Inclusion Formation during Growth of 4H-SiC Si-Face Homoepitaxial Layers with a 1° Off-Angle.

We grew epitaxial layers on 4H-silicon carbide (SiC) Si-face substrates with a 1° off-angle. The suppression of 3C-inclusion formation during growth at a high C/Si ratio was investigated, because a growth technique with a high C/Si ratio is needed to decrease residual nitrogen incorporation. 3C inclusions were generated both at the interface between the substrate and epitaxial layer, and during epitaxial growth. 3C-SiC nucleation is proposed to trigger the formation of 3C inclusions. We suppressed 3C-inclusion formation by performing deep in situ etching and using a high C/Si ratio, which removed substrate surface damage and improved the 4H-SiC stability, respectively. The as-grown epitaxial layers had rough surfaces because of step bunching due to the deep in situ etching, but the rough surface became smooth after chemical mechanical polishing treatment. These techniques allow the growth of epitaxial layers with 1° off-angles for a wide range of doping concentrations.

Clinicopathologic significance of loss of CD19 expression in diffuse large B-cell lymphoma.

To clarify the clinicopathologic significance of a loss of CD19 expression in diffuse large B-cell lymphoma (DLBCL), we evaluated CD19 expression immunohistochemically in frozen sections from 227 patients who had received diagnoses of DLBCL according to the World Health Organization classification between 1987 and 2002. Histopathologic features of patients with CD19- DLBCL were reviewed, and their clinical features, immunophenotypes, and prognoses were compared retrospectively with respect to CD19 expression. CD19 expression was positive in 205 patients (90%). The 22 patients with CD19- DLBCL had a median age of 63 years, and the male-female ratio was 11:11. Compared with patients with CD19+ DLBCL, those with CD19- DLBCL more frequently showed elevated lactate dehydrogenase (LDH) levels (73%, P= .011). Morphologically, 15 (79%) of the 19 CD19- DLBCL patients examined showed plasmablastic/plasmacytoid differentiation. Patients with CD19- DLBCL expressed BCL2 protein less frequently than CD19+ DLBCL (P= .042). Especially noteworthy is that half of the patients with CD19- DLBCL died within 2 years after diagnosis. The CD19- DLBCL group showed a survival curve significantly inferior to that for the CD19+ group (P= .034, generalized Wilcoxon test). Our findings demonstrate that loss of CD19 expression in DLBCL is associated with elevated serum LDH levels and a poor prognosis, especially during the early follow-up period.

CD21S antigen expression in tumour cells of diffuse large B-cell lymphomas is an independent prognostic factor indicating better overall survival.

To evaluate the clinical significance of CD21S expression of diffuse large B-cell lymphoma (DLBCL) tumour cells, we compared their clinical features, immunophenotype, response to therapy and outcome in relation to CD21S expression. Between 1987 and 1999, frozen sections from 240 DLBCL cases were examined for CD21S expression by immunohistochemical methods. CD21S expression was detected on the tumour cells of 87 (36%) cases. The median age of the CD21S(+) DLBCL cases was 65 years (range: 17-84 years), the male-female ratio was 42:45, and they showed the following clinical features: Eastern Cooperative Oncology Group score >1 in 14%, lactate dehydrogenase greater than normal levels in 38%, extranodal sites >1 in 14%, stages III/IV disease at diagnosis in 29%, B symptoms in 17%, and a high/high-intermediate International Prognostic Index (IPI) in 23%. They also showed a better overall survival (P = 0.00001, log-rank test) and a better complete remission rate (P = 0.00004, chi-square test) than CD21S(-) DLBCL. Moreover, CD21S(+) DLBCL showed a better survival than CD21S(-) DLBCL for both low/low-intermediate and high/high-intermediate risk categories of IPI (P = 0.045 and P = 0.0016 respectively). Multivariate analysis identified CD21S expression as an independent factor for survival when compared with the five IPI factors. These findings indicate that CD21S expression of DLBCL tumour cells is a useful prognostic factor for survival.

Synthesis and evaluation of substituted 4-alkoxy-2-aminopyridines as novel neuropeptide Y1 receptor antagonists.

A series of substituted 4-alkoxy-2-aminopyridines 2, which were formally derived from neuropeptide Y1 antagonist 1 by replacing the morpholino portion with alkoxy groups, were synthesized and evaluated as neuropeptide Y Y1 receptor antagonists. Primary structure-activity relationships and identification of potent 4-alkoxy derivatives are described.

Development of a high-performance boiling heat exchanger by improved liquid supply to narrow channels.

A two-phase flow loop is a promising method for application to thermal management systems for large-scale space platforms handling large amounts of energy. Boiling heat transfer reduces the size and weight of cold plates. The transportation of latent heat reduces the mass flow rate of working fluid and pump power. To develop compact heat exchangers for the removal of waste heat from electronic devices with high heat generation density, experiments on a method to increase the critical heat flux for a narrow heated channel between parallel heated and unheated plates were conducted. Fine grooves are machined on the heating surface in a transverse direction to the flow and liquid is supplied underneath flattened bubbles by the capillary pressure difference from auxiliary liquid channels separated by porous metal plates from the main heated channel. The critical heat flux values for the present heated channel structure are more than twice those for a flat surface at gap sizes 2 mm and 0.7 mm. The validity of the present structure with auxiliary liquid channels is confirmed by experiments in which the liquid supply to the grooves is interrupted. The increment in the critical heat flux compared to those for a flat surface takes a maximum value at a certain flow rate of liquid supply to the heated channel. The increment is expected to become larger when the length of the heated channel is increased and/or the gravity level is reduced.