In Situ Observation of Zirconia Particles at 1200°C by High-Resolution Electron Microscopy

Zirconia (ZrO₂) particles (average diameter, 30 nm) were observed in an in situ heating experiment up to 1200°C using a 400-kV high-resolution electron microscope. Thermal vibration of atoms on a (001) surface plane was observed at 1100°C. At 1200°C, grain growth and sintering phenomena were recorded on a videotape, showing (100) lattice planes migrating on a surface of a particle. Direct observation of the sintering process on a lattice level was accomplished for the first time.     

Pre-treatment of sperm reduces success of ICSI in the pig

In pigs, although ICSI is a feasible fertilization technique, its efficiency is low. In general, injected pig sperm are insufficient to induce oocyte activation and embryonic development. Pretreatments for disrupting sperm membranes have been applied to improve the fertility of ICSI oocytes; however, we hypothesize that such pretreatment(s) may reduce the ability of the sperm to induce oocyte activation. We first evaluated the effects of sperm pretreatments (sonication (SO) to isolate the sperm heads from the tails, Triton X-100 (TX), and three cycles of repeated freezing/thawing (3×-FT) for disrupting sperm membranes) on the rate of pronucleus (PN) formation after ICSI. We found that oocytes injected with control (whole) sperm had higher rates of PN formation than those obtained after subjecting the sperm to SO, TX, and 3×-FT. The amounts of phospholipase Cζ (PLCζ), which is thought to be the oocyte-activating factor in mammalian sperm, in sperm treated by each method was significantly lower than that in whole untreated sperm. Furthermore, using immunofluorescence, it was found that in pig sperm, PLCζ was localized to both the post-acrosomal region and the tail area. Thus we demonstrated for the first time that sperm pretreatment leads to a reduction of oocyte-activating capacity. Our data also show that in addition to its expected localization to the sperm head, PLCζ is also localized in the tail of pig sperm, thus raising the possibility that injection of whole sperm may be required to attain successful activation in pigs.     

Effect of tylosin tartrate on humoral immune responses in chickens

This article examines the 50-year struggle of osteopathic physicians to gain entry into the US Military Medical Corps on the same basis as allopathic physicians. The author explores various arguments put forth by both physician groups, as well as those arguments presented by the respective surgeons general and relevant government officials.     

Temperature dependence of the vortex nucleation field of thin-film,type II superconductors

The critical supercurrent versus applied field parallel to the surface of Pb-20 wt % In thin films was measured at various temperatures. The temperature dependence of the first vortex nucleation field (the lower critical field of a thin-film superconductor) suggests that the vortex structure is distorted due to surface effects.     

Self-assembly of a silica-surfactant nanocomposite in a porous alumina membrane

A mesoporous membrane composed of nanochannels with a uniform diameter has a potential use for precise size-exclusive separation of molecules. Here, we report a novel method to form a hybrid membrane composed of silica-surfactant nanocomposite and a porous alumina membrane, by which size-selective transport of molecules across the membrane becomes possible. The nanocomposite formed inside each columnar alumina pore was an assembly of surfactant-templated silica-nanochannels with a channel diameter of 3.4 nm; the channel direction being predominantly oriented along the wall of the columnar alumina pore. Molecules could be transported across the membrane including the silica-surfactant nanocomposite with a capability of nanometre-order size-exclusive separation. Our proposed membrane system has a potential use not only for separation science, but also catalysis and chip technologies.     

Thermoelectric properties of p- and n-type FeSi2 prepared by spray drying, compaction and sintering technique

FeSi₂ alloys doped with Mn and Co (p-type Fe_0.926Mn_0.074Si₂, n-type Fe_0.980Co_0.020Si₂) were prepared by vacuum induction melting. The ingots were pulverized in a jet-mill, and the powders were granulated by spray drying method using aqueous polyvinyl alcohol (PVA) binder in order to investigate the possibility of production on a large scale. The powders granulated exhibited excellent characteristics of flowability, leading to the smooth feeding into a die cavity in compacting. The powders obtained were compacted at a pressure of 98 MPa. It was debindered at 723 K for 1 h and sintered at 1423 K for 5 h in a hydrogen atmosphere, so that the residual carbon and oxygen contents in a sintered body approached to those in the starting powder. Subsequently it was annealed at 1113 K for 100 h in an argon atmosphere, to produce the semiconducting -FeSi₂ phase. The thermoelectric figures of merit (Z) for optimum p- and n-type FeSi₂ are 1.75 × 10^–4 (K^–1) and 2.0 × 10^–4 (K^–1) at about 900 K, respectively, which agree roughly with those obtained by Tani and Kido for FeSi₂ materials prepared by the spark plasma sintering method. It indicates that the spray drying method leading to the production on a large scale is available for the fabrication of the thermoelectric FeSi₂ materials.