Simple evaluation of aortic arch calcification by chest radiography in hemodialysis patients

Vascular calcification is associated with a poor prognosis in dialysis patients. It can be assessed with computed tomography but simple inoffice techniques may provide useful information. We compared the results obtained with a simple noninvasive technique with those obtained using multidetector computed tomography for aortic arch calcification volume (AoACV) in chronic hemodialysis (HD) patients. The enrolled study subjects were 63 (32 men and 31 women) maintenance HD patients. Calcification of the aortic arch was semiquantitatively estimated with a AoAC score (AoACS) on plain chest radiology. The AoACV was increased, with a mean value of 6.6 ranging from 0% to 36.5%. The coefficient of intraobserver variation was less than 2.5%. Aortic arch calcification score was highly correlated with AoACV (r=0.635, P<0.001). Multiple regression analysis showed age (F value=12.62, P<0.001) and pulse pressure (F value=4.54, P=0.037) to be significant independent determinants of AoACS. In conclusion, a simple measurement of AoACS may be useful for inoffice imaging to choose a therapeutic regimen in HD patients.     

Properties of Sodium-Lithium Niobate Solid Solution Ceramics with Small Lithium Concentrations

The structural, dielectric, and piezoelectric properties of the solid solution (Na_1-x,Li_x,)NbO₂ were studied. Solid solution ceramics with x values up to 0.14 occur as a single phase. The phase diagram from 0° to 600°C is given. The low-temperature phase has a perovskite pseudo-monoclinic structure and inverts to a pseudotetragonal structure at a temperature that decreases with increasing x. The high-temperature phase is pseudocubic, and the minimum transition temperature from the pseudotetragonal to the pseudocubic structure is 350° C near x = 0.04. Anomalies in the dielectric constant vs. temperature curve agree well with the transition temperatures, although no anomaly was observed at the temperature of transition from the pseudotetragonal to the pseudocubic phase when x was less than 0.06. Lithium ions in the system facilitate the transformation from the antiferro-electric to the ferroelectric state produced by applying an electric field. A new ferroelectric phase becomes stable when x is greater than 0.07. Poled ferroelectric specimens had a planar coupling coefficient of 0.232, a dielectric constant of 220, and a frequency constant of 3352 kc-mm. The piezoelectric properties disappear not at the transition temperature but at the temperature at which strain exhibits an anomaly when x is greater than 0.07. A perovskite phase with a pseudorhombohedral subcell exists as an intermediate phase for x greater than 0.10, the exact value depending on the preparation method. The phase can be easily converted to pseudomonoclinic when the ceramic is fired at 1180° to 1220°C.     

Visualization of BrdU-labelled DNA in cyanobacterial cells by Hilbert differential contrast transmission electron microscopy

We have attempted to observe the native shape of DNA in rapidly frozen whole cyanobacterial cells through 5-bromo-2-deoxyuridine (BrdU) incorporation and visualization with a Hilbert differential contrast transmission electron microscopy (HDC TEM). The incorporation of BrdU into the DNA of Synechococcus elongatus PCC 7942 was confirmed with fluorescently labelled anti-BrdU antibodies and through EDX analysis of ultra-thin sections. HDC TEM observed cells that had incorporated BrdU into their DNA exhibited electron dense areas at the location corresponding to fluorescently labelled BrdU. Since various strings and strands were observed in high contrast with the HDC TEM, we conclude that the method promises to allow us to identify and understand bulk structural changes of the in vivo DNA and the nucleoid through observation at high resolution.     

Formation, Microstructure, and Properties of Barium Zirconium Sulfide Ceramics

The preparation, microstructure, and properties of BaZrS₃ ceramics are described. The compound was prepared by heating either an equimolar mixture of BaS and ZrS₂ or BaZrO₃ alone in CS₂ gas. The reaction of the BaZrO₃−CS₂ system was extremely rapid, as would be expected in an autocatalytic reaction caused by very strong reduction by CS₂. Well-sintered bodies were obtained only by the BaZrO₃−CS₂ reaction. The time dependence of grain growth was affected considerably when reaction and sintering occurred above 1250° C. Non-uniform grain growth which occurs when an excess of Ba is present can be interpreted in terms of secondary recrystallization resulting from segregation of BaS at the grain boundary during sintering. The BaZrS₃ ceramic was stable in air up to 550°C and was oxidized above that temperature.     

Electrical and Magnetic Properties of Iron-Nickel Sulfide Ceramics

Solid solutions of (Fe,Ni)S were prepared by the metal oxide-carbon disulfide reaction sintering method. These ceramics have the hexagonal NiAs structure, and their lattice parameters depend on the Fe-Ni ratio. The magnetization of these ceramics reduces with decreasing Fe content between 100/0 (Fe/Ni) and 50/50, increases between 50/50 and 40/60, and decreases again between 40/60 and 0/100. The electrical resistivity reduces uniformly with decreasing Fe content of the ceramics.     

Phenolic rigid organic filler/isotactic polypropylene composites. I. Preparation

A novel phenolic rigid organic filler (KT) was melt-mixed with an isotactic polypropylene (iPP) to prepare a series of PP/KT composites, with or without maleic anhydride grafted polypropylene (MAPP) as compatilizer. The evolution of filler morphology during melt-mixing and melt-pressure processes was monitored by scanning electron microscope (SEM) and polarized optical microscope (POM). The influences of shear force, pressure time, filler content and MAPP concentration on the final filler dispersion were studied. We found that this rigid organic filler readily melted and dispersed homogenously into the iPP matrix through a fission-fusion process during the melt-mixing process. Thus a balanced dispersion, which was closely related to shear force and MAPP concentration, can be achieved. During the melt-pressure process, parts of the filler particles combined gradually through a coalescence process. However, the incorporation of MAPP can effectively inhibit the tendency to coalesce and refine the filler particles sizes into nanoscale. Thus, a series of PP/KT composites with controllable filler particles size and narrow size distribution can be obtained just by adjusting process conditions and MAPP concentration. In addition, due to the in-situ formation mechanism, the filler phase possessed a typical solid true-spherical shape.     

Sintering of ZnS with a Small Amount of Ba2ZnS3

The effects of alkali and alkali-earth chloride additives on the sintering of ZnS powder compacts in H₂S have been examined. BaCl₂ was found to promote the sintering of ZnS. BaCl₂ reacts with ZnS to form Ba₂ZnS₃, which acts as a flux for sintering.     

Humidity-Sensitive Electrical Conduction of MgCr2O4-TiO2 Porous Ceramics

The crystalline phase, microstructure, semiconduction, and humidity-sensitive electrical conduction of MgCr₂O₄-TiO₂ ceramics were studied. A solid solution with TiO₂ up to 30 mol% occurs as a single phase with a pure MgCr₂O₄-type spinel structure. The humidity-sensitive electrical conduction of the MgCr₂O₄-TiO₂ porous ceramics is the most promising for humidity-sensing devices.     

Formation and Properties of Barium Metaplumbate

The preparation and the physical and electrical properties of BaPbO₃ ceramics are described. The compound was formed by firing an equimolar mixture of BaCO₃ and Pb₃O₄ in oxygen at 880°C. To produce the stoichiometric compound on firing in air at 980°C it was necessary to use an excess of PbO (molar ratio, Pb/Ba = 1.278). A well sintered ceramic was obtained only with a stoichiometric composition with a sintered density of 7.78. Free BaCO₃ was found in the fired bodies including the PbO-rich compositions. The electrical resistively of BaPbO₃ was 8.3 × 10⁻⁴ ohm-cm at 25°C with a temperature coefficient of +0.15%/°C.