Dielectric and Electromechanical Properties of Textured Niobium-Doped Bismuth Titanate Ceramics

Textured Nb-doped bismuth titanate ceramics (Bi₄Ti_{3− x /5}- Nb _{x /5}O₁₂, where x = 0.02) were fabricated by templated grain growth. It was found that the use of a fine precursor powder led to enhanced densification of the ceramic, while Nb doping reduced electrical conduction and dielectric loss, which enabled poling at high temperatures and high electric fields. Sintered tapes showed anisotropic dielectric and piezoelectric properties when measured parallel and perpendicular to the casting plane (e.g., the remanent polarization differed by more than a factor of 15 in the two directions). The piezoelectric constant parallel to the casting plane of the tape was ∼30 pC/N, or ∼77% of the single-crystal value. Thermal depoling studies demonstrated that high-temperature piezoelectric applications are possible up to ∼450°C in textured, doped bismuth titanate.     

Phase I clinical study of the recombinant oncotoxin TP40 in superficial bladder cancer

Many previous studies evaluating various hormone levels in males with subnormal semen analyses were performed when the normal semen parameters were considerably higher than now. This study evaluated sera levels of follicle stimulating hormone (FSH), luteinizing hormone (LH), total testosterone (TET), free TET, and prolactin (PRL) in 60 males with oligospermia and decreased motility according to recent World Health Organization standards. Three separate groups were evaluated: group 1, motile density (MD) < 5 x 10(6)/mL (but not azoospermia); group 2, 5 < or = MD < 10 x 10(6)/mL; group 3, MD > 10 x 10(6)/mL, but % motility < 30%. There were no significant differences in mean FSH levels between groups. Overall FSH was increased in 47.1% of the cases. In contrast, mean LH levels were normal in all three groups. Only 17.3% of the entire group had elevated LH levels. The TET level was below normal in 32.3% of the entire group, with a fairly equal distribution between the three groups. Overall, only 7.8% had elevated PRL levels, with the highest percentage found in group 3 (22.2%). Only a small minority of patients with increased FSH had low TET levels compared to 48.0% of those with normal FSH. These data demonstrate that when using the lower semen parameters, the most common serum hormone abnormality is increased FSH; men with MD < 5 x 10(6)/mL do not have a higher incidence of elevated FSH than those with higher MDs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Urinary nuclear matrix protein as a marker for transitional cell carcinoma of the urinary tract

PURPOSE: The purpose of this trial was to evaluate an immunoassay for urinary nuclear matrix protein, NMP22, as an indicator for transitional cell carcinoma of the urinary tract. MATERIALS AND METHODS: Three groups of subjects participated in this trial of NMP22: 1-175 with transitional cell carcinoma, 2-117 with benign urinary tract conditions and 3-375 healthy volunteers. Each subject provided a single (3 voids) urine sample for analysis at the time of study entry. Each sample was assayed for the level of NMP22. RESULTS: In normal healthy volunteers and in subjects with benign conditions median NMP22 levels were 2.9 and 3.3 units per ml., respectively. Median urinary NMP22 levels in patients with transitional cell carcinoma were significantly greater than in comparison subjects. Patients with active transitional cell carcinoma had significantly greater median urinary NMP22 levels than those with no evidence of disease (6.04 versus 4.11 units per ml., p = 0.027, 1-tailed Mann-Whitney U test). We noted no effect of tumor grade, extent of disease or exposure to intravesical therapy on urinary NMP22 levels. CONCLUSIONS: NMP22 is a promising urinary tumor marker for monitoring transitional cell carcinoma. Nuclear matrix proteins are a new class of tumor markers that represent the basis for the development of assays with increased efficacy for the detection and treatment of cancer.     

Region-specific cis- and trans-acting factors contribute to genetic variability in meiotic recombination in maize

Understanding the genetic basis for variability in recombination rates is important for general genetic studies and plant-breeding efforts. Earlier studies had suggested increased recombination frequencies in particular F2 populations derived from the maize inbred A188. A detailed phenotypic and molecular analysis was undertaken to extend these observations and dissect the responsible factors. A heritable increase in recombination in the sh1-bz1 interval was observed in these populations. A factor causing an approximate twofold increase mapped to the A188 sh1-Bz1 region, behaved as a dominant, cis-acting factor, affected recombination equally in male and female sporogenesis and did not reduce the well-studied complete interference in the adjacent bz1-wx interval. This factor also did not increase recombination frequencies in the c1-sh1 and bz1-wx intervals, demonstrating independent control of recombination in adjacent intervals. Additional phenotypic analysis of recombination in the c1-sh1 and bz1-wx intervals and RFLP analysis of recombination along chromosomes 7 and 5 suggested that heritable factors controlling recombination in these intervals act largely independently and in trans. Our results show that recombination in these populations, and possibly maize in general, is controlled by both cis- and trans-acting factors that affect specific chromosomal regions.     

Densification of sintered lead zirconate titanate by hot isostatic pressing

The effects of hot isostatic pressing (HIPing) on sintered lead zirconate titanate are presented. Densities up to 98% were obtained by HIPing for 1 h at 1300°C with argon gas pressures of either 20.7 or 138 MPa. The microstructural changes observed after HIPing, and the rapid initial kinetics for densification and pore shrinkage, indicate that prssure-enhanced grain rearrangement and solution-precipitation processes are primarily responsible for densification. The persistance of large voids after HIPing suggests that it may be impossible to completely eliminate gross processing-related defects in lead zirconate titanate by HIPing.     

The role of ceramic and glass science research in meeting societal challenges: Report from an NSF‐sponsored workshop

Under the sponsorship of the U.S. National Science Foundation, a workshop on emerging research opportunities in ceramic and glass science was held in September 2016. Reported here are proceedings of the workshop. The report details eight challenges identified through workshop discussions: Ceramic processing: Programmable design and assembly; The defect genome: Understanding, characterizing, and predicting defects across time and length scales; Functionalizing defects for unprecedented properties; Ceramic flatlands: Defining structure‐property relations in free‐standing, supported, and confined two‐dimensional ceramics; Ceramics in the extreme: Discovery and design strategies; Ceramics in the extreme: Behavior of multimaterial systems; Understanding and exploiting glasses and melts under extreme conditions; and Rational design of functional glasses guided by predictive modeling. It is anticipated that these challenges, once met, will promote basic understanding and ultimately enable advancements within multiple sectors, including energy, environment, manufacturing, security, and health care.     

Mullite Transformation Kinetics in P2O5-, TiO2-, and B2O3-Doped Aluminosilicate Gels

Mullite transformation kinetics of sol-gel-derived diphasic mullite gels doped with P₂O₅, TiO₂, and B₂O₃ were studied using quantitative X-ray diffraction and differential thermal analysis (DTA). The mullite transformation temperature initially increased with P₂O₅ doping because of phase separation and formation of α-alumina and cristobalite. In TiO₂-doped samples, the mullite transformation temperature decreased with TiO₂ doping, and the transformation rate increased with decreasing TiO₂ particle size. Kinetic studies showed that titania reduced the activation energy for both nucleation and growth relative to pure diphasic mullite gels by lowering the glass viscosity and/or enhancing the solid-state mass transport through lattice defects. B₂O₃ doping decreased the mullite transformation temperature and lowered the activation energy for both nucleation and growth but especially affected the mullite nucleation process, as indicated by the much smaller grain size.     

Solid-Phase Epitaxy of Boehmite-Derived α-Alumina on Hematite Seed Crystals

The seeded transformation of boehmite-derived alumina was studied by transmission electron microscopy. Crystallographic analysis confirmed that the growth of α-Al₂O₃ on α-Fe₂O₃ seed crystals occurs by solid-phase epitaxy, with the orientation relationship [0001]_Al2O₃||[0001]_Fe2O₃ and [11 2 0]_Al2O₃||[11 2 0_Fe2O₃.