Sequence analysis of thyroid transcription factor-1 gene reveals absence of mutations in patients with thyroid dysgenesis but presence of polymorphisms in the 5'' flanking region and intron

The purpose of this study was to determine the optimal scanning technique for lesion detection in a small bowel phantom and to evaluate the virtual endoscopy (VE) technique in patients. A small bowel phantom with a fold thickness of 7 mm and length of 115 cm was prepared with nine round lesions (3 x 1 mm, 2 x 2 mm, 2 x 3 mm, 2 x 4 mm). Spiral CT parameters were 7/7/4, 3/5/2, 3/5/1, 1.5/3/1 (slice thickness/table feed/reconstruction interval). VE was done using volume rendering technique with 1 cm distance between images and 120 degrees viewing angle. Two masked readers were asked to determine the number and location of the lesions. Seven patients underwent an abdominal CT during one breathhold after placement of a duodenal tube and filling of the small bowel with methyl cellulose contrast solution. VE images were compared with the axial slices with respect to detectability of pathology. With the 7/7/4 protocol only the 4-mm lesions were visualised with fuzzy contours. The 3/5/2 protocol showed both 4-mm lesions, one 3-mm lesion and one false positive lesion. The 3/5/1 protocol showed both 4-mm and both 3-mm (one uncertain) lesions with improved sharpness, and no false positive lesions. One 2-mm and one 1-mm lesion were additionally seen with the 1.5/3/1 protocol. Path definition was difficult in sharp turns or kinks in the lumen. In all patients, no difference was found between VE and axial slices for bowel pathology; however, axial slices showed 'outside' information that was not included in VE. We conclude that the 3/5/2 protocol may be regarded as an optimal compromise between lesion detection, coverage during one breathhold, and number of reconstructed images in patients; round lesions of 4 mm in diameter can be detected with high certainty.     

Secretion of mouse α-amylase from fission yeast Schizosaccharomyces pombe: Presence of chymostatin-sensitive protease activity in the culture medium

We have constructed two secretion vectors for Schizosaccharomyces pombe using an SV40 promoter and the secretion signals of the pGKL killer toxin complex derived from Kluyveromyces lactis. Although indigenous secretory glycoproteins tend to accumulate in the periplasmic space of S. pombe, we have succeeded in the secretion of mouse α-amylase into the culture medium. The efficiency of secretion, processing pattern, stability and culture conditions for mouse α-amylase were studied in S. pombe. The 128 kDa killer secretion signal was more effective in directing secretion of mouse α-amylase than the 28 kDa killer secretion signal. We detected a chymostatin-sensitive protease activity in the culture medium of S. pombe, which digests mouse α-amylase secreted into the culture medium. The addition of 5 μg/ml chymostatin was shown to protect mouse α-amylases from this degradation.     

Performance of a polymer electrolyte fuel cell for automotive applications

The objectives of this study were to fabricate a self‐humidifying fuel cell stack of 10 cells with 104 cm² cell areas humidified with water recovered at cathodes, and to measure and simulate the performance of the stack. This involves the simulation of a three‐dimensional model of the heat and mass transfer of the water and the gaseous reactants in the fuel cell components with a water‐cooling system. The results of the stack experiments indicated a maximum power of 250 kW at a current density of 0.5 A/cm². The simulation showed good agreement with the actual performance of the stack. The performance of the self‐humidifying stack with a vapor‐permeating membrane is comparable to a conventional stack with external humidifiers, and it appears very effective in simplifying stack systems. The modeling analysis indicated that for the gas flow directions, at anode and cathode, a parallel flow is superior to a cross flow, and that one cooling cell is necessary for two to three generating cells in order to maintain the fuel cell temperature below 100 °C. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(6): 421–429, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10041     

Effect of Dopant Species on Tetragonal (t')-to-Monoclinic Phase Transformation of Arc-Melted ZrO2-RO,1.5 (R = Sm, Y, Er, and Sc) in Water at 200°C and 100 MPa Pressure

Arc-melted specimens of rare-earth-doped zirconia (ZrO₂- X mol% RO_1.5; X = 4–10 for R = Sm, Y, Er, and X = 4–18 for Sc) were hydrothermally treated at 200°C, 100 MPa to investigate the dependence of the tetragonal-to-monoclinic transformation on dopant species and its content. The volume fraction of monoclinic phase Vm ( t ) increased from Vm (0) to a certain saturated value Vm (ω), following [ Vm ( t ) − Vm (0)]/[ Vm ( t ) − Vm (ω)] = 1 − exp(− k·t ), where t is the annealing time at 200°C, 100 MPa. The transform-abilities, Vm (0), Vm (ω), and k decrease with increasing dopant content. The Vm (ω) decreased with an increase of ionic radius of dopants. The relation 0 < Vm (ω) < 1 suggests that apparent noncompositional inhomogeneity exists in the hydrothermally treated sample.     

电镀非晶铬与热处理

研究多种镀液在不同工艺参数条件下其镀铬层的结构特征,把20(Cu·ka)角的测定由文献上用X射线方法测列的85°扩大到145°,并在135°附近发现了新的结构特性,最后讨论了非晶镀层的形成原因及其耐蚀性。     

High Oxide-Ion Conductivity through the Interstitial Oxygen Site in Sillén Oxychlorides

Oxide-ion conductors are gaining attention as future materials in energy applications, such as solid oxide fuel cells. Many Bi-containing compounds exhibit high oxide-ion conductivity via conventional vacancy mechanism. However, interstitial oxide-ion conduction is rare in Bi-containing materials. Herein, high oxide-ion conductivity is reported through interstitial oxygen sites in Sillén oxychlorides, LaBi_2−xTe_xO_4+x/2Cl (Bi₂LaO₄Cl-based oxychlorides). Oxide-ion conductivity of LaBi_1.9Te_0.1O_4.05Cl is 20 mS cm⁻¹ at 702 °C, and higher than best oxide-ion conductors as Bi₂V_0.9Cu_0.1O_5.35 below 201 °C. Despite of the presence of Bi and Te species, LaBi_1.9Te_0.1O_4.05Cl shows extremely high chemical and electrical stability at 400 °C from oxygen partial pressure 10⁻²⁵ to 0.2 atm and high chemical stability under CO₂ flow, wet 5% H₂ in N₂ flow, and air with natural humidity. Neutron scattering length density analysis, DFT calculations, and ab initio molecular dynamics simulations indicate that the extremely high oxide-ion conduction is attributed to cooperative diffusion through interstitial oxygen sites (interstitialcy diffusion mechanism) in triple fluorite-like layers. The present findings demonstrate the ability of LaBi_2−xTe_xO_4+x/2Cl as superior oxide-ion conductors, which can open new horizons for oxide-ion conductors.     

Temperature Dependence of Lattice Parameters and Anisotropic Thermal Expansion of Bismuth Oxide

Temperature dependence of lattice parameters of bismuth sesquioxide (Bi₂O₃) has been obtained between 26° and 778°C by the Rietveld method using neutron powder diffraction data. Lattice parameters     and unit-cell volume of α and δ phases increased, while the β angle of α phase decreased with an increase of temperature. Here the     denotes the lattice parameter a of the α phase on the basis of pseudo-fluorite lattice. The thermal expansion coefficients of α phase were 26.7, 6.6, and 9.0 (× 10⁻⁶°C⁻¹) for     and     axes, respectively, indicating a large anisotropy. The α- to -δ phase transition of Bi₂O₃ was confirmed between 721° and 760°C on heating. At the α–δ transition point, the lattice parameters and unit-cell volume discontinuously changed, indicating that the transition is of the first order.     

Oxygen Tracer Diffusion in Polycrystalline Calcium-Doped Lanthanum Chromites

Oxygen tracer diffusion in polycrystalline (La,Ca)CrO_3−delta was studied by the gas-solid isotope exchange reaction in combination with a depth-profiling technique using secondary-ion mass spectroscopy, which allowed determination of coefficients of lattice and grain-boundary diffusion separately. A significant contribution of fast grain-boundary diffusion was confirmed. The lattice diffusion coefficient increased with increased acceptor content and decreased oxygen partial pressure, which was consistent with the currently established point defect model and, thereby, suggested that the lattice oxide ions diffused by a vacancy mechanism.