Formation of amorphous Al-Cr alloys by mechanical alloying of elemental aluminium and chromium powders

Mechanical alloying (MA) of elemental aluminium and chromium powders has been performed using a conventional ball-mill. The MA process produces composite metal powders and homogeneously alloyed powders. During continuous heating at the rate of 0.33 K sec^–1 Al-15 at% Cr samples ball-milled for 800 and 1000 h showed two exothermal peaks. The first peak which appeared at the lower temperature corresponds to amorphization of the MA powders. It was confirmed by X-ray and transmission electron microscopy that the heattreated powders, quenched from a temperature just above the first peak, were amorphous phase. Amorphous Al-Cr alloys were formed using elemental powders by MA and subsequent heat treatment.     

Dynamic viscoelastic properties in the molten state for cellulose acylates and (cellulose oligo-oxymethylene ether) acylates

The dynamic viscoelastic properties of cellulose acylates, its mixed acylates, and (cellulose oligo-oxymethylene ether) acylates (COM acylates) have been meausured in the molten state over wide ranges of frequency and temperature. The log G′ vs. log ω curves as well as the similar curves for the loss modulus G′ at various temperatures for cellulose acylates could not be superposed into respective master curves by use of the time–temperature superposition principle. This is considered to be caused from the orientation of cellulose acylates main chain in the molten state. In the case of cellulose mixed acylates, rheological simplicity was found but this was only the case on selected combinations of acyl groups. Most cellulose acylates, which were introduced oxymethylene chains (OM chains) in between glucopyranose ring and the acyl group, behaved as thermorheologically simple materials in the molten state. When the acyl groups become large, however, it is necessary to introduce long OM chains in order to get thermorheologically simple COM acylates in their molten state. Several studies have been made concerning the behavior of side chains, both the OM and the acyl chains, of COM acylates in the molten state.     

Direct observation of a stacking fault in Si(1 - x)Ge(x) semiconductors by spherical aberration-corrected TEM and conventional ADF-STEM

Spherical aberration (C(S))-corrected transmission electron microscopy (TEM) and annular dark-field scanning TEM (ADF-STEM) are applied to high-resolution observation of stacking faults in Si(1 - x)Ge(x) alloy films prepared on a Si(100) buffer layer by the chemical vapor deposition method. Both of the images clarify the individual nature of stacking faults from their directly interpretable image contrast and also by using image simulation in the case of the C(S)-corrected TEM. Positions of the atomic columns obtained in the ADF-STEM images almost agree with a projection of the theoretical model studied by Chou et al. (Phys. Rev. B 32(1985): 7979). Comparison between the C(S)-corrected TEM and ADF-STEM images shows that their resolution is at a similar level, but directly interpretable image contrast is obtained in ultrathin samples for C(S)-corrected TEM and in slightly thicker samples for ADF-STEM.     

Dimensional-Crossover of 3He Gas Formed in One-Dimensional Nanometer Tunnel

No Heading We have measured the heat capacity of ³He adsorbed on one-dimensional (1D) nanopores of FSM-16 with different pore-diameters. Dilute ³He atoms on more than one layers of ⁴ He preplated nanotunnels with 22 Å in diameter show a Schottky type peak around 0.25 K, which is similar to our recent report for 28 Å nanotunnels. This behavior of heat capacity is explained as the crossover from 1D to 2D motion of Fermi gas in a confined geometry. The pore-size effect on the temperature and magnitude of the peak is quantitatively reproduced by a simple calculation for non-interacting Fermi gas in the adsorption potential from the substrate.PACS numbers: 67.55.Cx, 67.70.+n, 68.65.–k     

First observation of SiO2/Si(100) interfaces by spherical aberration-corrected high-resolution transmission electron microscopy

SiO2/Si(100) interfaces were for the first time observed by a spherical aberration-corrected high-resolution transmission electron microscope in a cross-sectional mode. As the Fresnel fringes were not contrasted at the interfaces, the interfacial structures were clearly observed without the need for artificial image contrast. Atomic steps and defects on the Si(100) surfaces were accurately identified. Also, image simulations with the target imaging performance revealed oxygen atomic columns between silicon-silicon bonds. The present instrument is of potential use for semiconductor science and technology, even for the analysis of oxygen atoms at interfaces.     

Effect of a traditional Chinese medicine, Bu-zhong-yi-qi-tang on the protection against an oral infection with Listeria monocytogenes

Gene therapy for vascular disease is in the beginning stages. Each year investigators are increasing our understanding of the molecular and cellular biology of vascular disease and its complications. Our genes exert exquisite control over the expressed molecular pattern that results in biological function and pathology. Gene transfer techniques can be used to affect the pattern of gene expression. Gene therapy is a powerful tool that will allow specific manipulation of the genetic cascade that determines biological function. Gene transfer techniques should help to define the molecular mechanisms involved in vascular pathology, such as atherosclerosis and its complications. Currently, gene therapy has only reached clinical trials, but this new technology will likely play a major role in our treatment of vascular problems in the future. An understanding of the significance of this new technology is important for both health care providers and patients.     

Studies of Atomic Structure and Physical Properties of Metal Clusters in MgO by HREM and Nano-probe Methods

Nanometer-sized metal clusters were prepared inside single crystalline MgO films by vacuum co-deposition of metals and MgO. The atomic structure was studied by high-resolution electron microscopy (HREM) and nm-area electron diffraction. The size of the clusters is ranging from 1 nm to 3 nm without those larger than 5 nm, and most of them have definite epitaxial orientations with the MgO matrix films. The character of the composite films is very much useful for the studies of various kinds of physical properties with anisotroPy. The physical properties such as electric transport, magnetic, optical absorption, sintering and catalytic ones were thus measured on the same samples analyzed by HREM by using high sensitivity apparatus with interest of clarifying the retationship between the atomic structure and physical properties     

Presence of anti-FKBP12 autoantibodies in patients with liver allografts: its association with allograft rejection

BACKGROUND: It was reported that autoantibodies against cyclophilin are present in sera from systemic lupus erythematosus. We hypothesized that autoantibodies against FKBP12, another immunophilin, may be present in the plasma of liver allograft recipients, which may affect the clinical outcome of liver allografts. METHODS: We investigated the relationship between the presence of anti-FKBP12 autoantibodies and rejection episodes in 47 patients treated with FK506 after living-related partial liver transplantation (LRLT). The patients consisted of two groups: 22 with rejection [R(+) group] and 25 without rejection [R(-) group]. The autoantibodies were measured by an indirect ELISA, and the specificity was confirmed by absorption with antigen and immunoblotting. RESULTS: The autoantibodies were detected in 13 of 22 in the R(+) group (IgG: 5; IgM: 6; both: 2) and in 6 of 25 in the R(-) group (IgG: 2; IgM: 3; both: 1) before LRLT (P=0.0193). After LRLT, they were also detected more frequently in the R(+) group (12 of 22; IgG: 1; IgM: 8; both: 3) than in the R(-) group (2 of 25; IgG: 1; IgM: 1) (P=0.001). In the R(+) group, the mortality of the patients who were positive and negative for the autoantibodies was 6 of 12 and 2 of 10, respectively. The autoantibodies were detected in all four patients with chronic or refractory acute rejection. The autoantibodies were not detected in any of the 34 healthy subjects. CONCLUSIONS: These results suggest that the presence of the autoantibodies in patients before transplantation is related to rejection, and the presence after transplantation may be associated with patient outcome.     

Alteration of human platelet protein kinase C with normal aging

Using a two-site enzyme immunoassay, we determined the content of type II protein kinase C (PKC) in human platelets from 24 donors of various ages without any neurological, hematological or malignant disorders. The content of type II PKC in the membranous fraction was positively correlated with aging. The content of PKC in the cytosolic fraction tended to decline with aging, but the correlation was not significant. The total amount of PKC also had no significant correlation with aging. Age-related changes in platelet protein content were not observed. These results suggested that the subcellular distribution of type II PKC in human platelets is altered with normal aging.