TEM observations of diamond films produced by hot filament thermal CVD

Diamond films were provided by a hot filament thermal chemical vapour deposition method with an H₂-CH₄ gas mixture under various reaction conditions: CH₄/H₂ ratios of 0.5% and 1.0%, Si and Cu substrates, a substrate temperature of 750 °tC, a pressure of 7 torr and a reaction time of 12 h. TEM observation showed that the films produced have many defects such as twins, stacking faults and large distortion of lattices. These defects, which increase with increasing CH₄ concentration, seem to be introduced during the crystal growth process. Fivefold symmetry twinned crystals were often observed in the diamond films.     

Synthesis, Atomic Structures, and Electronic States of Boron Nitride Nanocage Clusters and Nanotubes

Boron nitride (BN) nanocage clusters (B_nN_n: n = 12-60), endohedral BN clusters Y@B_nN_n, and BN nanotubes were synthesized by an arc-melting method, and characterized by mass spectrometry and high-resolution electron microscopy. The BN clusters consisted of 4-, 6-, 8-, and 10-membered BN rings satisfying the isolated tetragonal rule, which was optimized by molecular orbital calculations. Total energy calculation showed that some elements stabilize and expand the B₃₆N₃₆ structure. Bandgap energies of the B₃₆N₃₆ clusters were found to be reduced by introducing a metal atom inside the cluster, which indicates controllability of the energy gap. Chiralities of BN nanotubes with zigzag- and armchair-type structures were directly determined from high-resolution images, and structure models are proposed. Total energies of BN nanotubes with a zigzag-type structure were lower than those of armchair-type structure, and these results agreed well with the experimental data of disordered tube structure. BN nanotubes encapsulating BN clusters and a yttrium nanowire were also found. This article indicates that the new BN nanocage fullerene materials with various atomic structures and properties can be produced, and a guideline for designing the BN fullerene materials is summarized.     

The effect of nonlinear stress-strain relationship on the bend strength of isotropic graphite

Four-point bend tests on rectangular specimens of several different sizes of isotropic graphite 7477PT were made to study the effect of nonlinear stress-strain relationship on bend strengths. The measurements showed that the tensile and compressive strains at the outer fibers had a nonlinear relationship with the bending load and that the tensile fiber strains at fracture were 0.4–0.7%, as compared with the uniaxial tensile fracture strains 0.25–0.45%. From the observations the nonlinear stress-strain curves were determined for tension and compression, nonlinearity being larger in the former than in the latter. The true bend strengths were 10–15% smaller than the elastic ones. In calculations on Weibull's statistical theory, the probability distributions of bend fracture in terms of true bend strength agreed better with experiments than those in terms of elastic bend strength.     

Digital high-resolution electron microscopy of atomic disordering in YB56

Despite of the difficulty in determining the atomic arrangement of light elements and doping atoms in the solid clusters, it is believed that the high-resolution images should have 'some' information on disordering, ordering, and doping atomic positions in these materials. In the present work, the information for disordering of atomic positions in YB56 was obtained from digital high-resolution images. The arrangement of Y atoms was also directly imaged and quantified. The present work indicates that the atomic detection by digital high-resolution images is very useful for evaluation of local structure in the ceramic materials with light elements such as boron.     

Elastic modulus and bend strength of a nuclear graphite at high temperature

The elastic modulus of a nuclear graphite was measured in the range from room temperature to 1400°C by the ultrasonic pulse echo method. Little or no change in the elastic modulus was observed up to 450°C. Above 500°C, however, it increased almost linearly with increasing temperature. The fractional increase was about 10% at 1000°C and 24% at 1400°C. The four-point bend test was also measured at temperatures between room temperature and 1200°C. Changes in bend strength with temperature were found to parallel to those of the elastic modulus. The mechanism for the correlation between the bend strength and the elastic modulus, as well as the effect of moisture on the strength, was discussed.     

A RECURSIVE 4SID FROM THE INPUT-OUTPUT POINT OF VIEW

In this paper, recursive algorithms of subspace state-space system identification (4SID) for multiple-input, multiple-output (MIMO), finite dimensional, linear time-invariant (FDLTI) systems are proposed. These algorithms are derived based on the Matrix Inversion Lemma. The investigation of our algorithms clarifies that a series of 4SID is the extension of the classical least square method to identification for multivariable systems, and also that our algorithms are the direct extension of the recursive least square algorithm to such ones. For PO-MOESP (the ordinary MOESP scheme with instrumental variables constructed from Past input and Output measurements), we show the mechanism of how the effect of the process and measurement noises is eliminated asymptotically by a projection related to the input and regressor matrices. “MOESP” is an abbreviation for “the MIMO output-error state-space model identification.”     

Lipid and fatty acid compositions differentiate between wild and cultured Japanese eel (Anguilla japonica)

The lipid profile and fatty acid composition of muscle, liver, and plasma lipoprotein were examined in wild and cultured Japanese eel (Anguilla japonica). Although, the muscle lipid levels of wild eels (11.6%) were less than those of cultured eels (13.1%), both eels were classified as typical fatty fish. Compared with the liver lipid composition of cultured eels, triacylglycerol (TG) level of the liver decreased in wild eels, whilst phosphatidylcholine and phosphatidylethanolamine levels of the liver increased in wild eels, reflecting the difference of liver lipid levels in both eels. Wild eels contained more cholesteryl ester (CE) and less TG, phospholipid, and free cholesterol in their plasma than cultured eels. The ratio of TG to CE decreased, whilst that of CE to total cholesterol increased in the plasma of wild eels. Different fatty acid compositions were found between wild and cultured eels. Compared with the fatty acid compositions of cultured eels, wild eels contained high percentages of 18:2, 18:3, and 20:4 and low percentages of 22:6, 20:1, and 20:5 in their muscle, liver, and plasma lipoprotein. The lipid profile and fatty acid composition seemed to be useful criteria for distinguishing between wild and cultured eels.     

The role of surgery in the management of small cell lung carcinoma

Small cell lung carcinoma is responsive to chemotherapy and radiotherapy, but long-term survival of patients is rarely seen. We analyzed resected 19 patients with small cell lung carcinoma. The overall 5-year survival rate of resected patients was approximately 30% and mean survival time (MST) was 50 months. 2 patients of them survived more than 5 years. The survivors were received chemotherapy and radiotherapy several times after surgery. When we consider the role of resection in the treatment of small cell lung carcinoma, we can realize multimodality therapy including resection is important to obtain long-term survival. Moreover, the surgical resection can identify mixed type with non-small cell elements or residual tumors after chemotherapy and determine optimal treatment methods from their histopathologic findings.     

Characterization and crystal structure of the thermophilic ROK hexokinase from Thermus thermophilus

We characterized and determined the crystal structure of a putative glucokinase/hexokinase from Thermus thermophilus that belongs to the ROK (bacterial repressors, uncharacterized open reading frames, and sugar kinases) family. The protein possessed significant enzymatic activity against glucose and mannose, with V(max) values of 260 and 68 μmol·min(-1)·mg(-1) protein, respectively. Therefore, we concluded that the enzyme is a hexokinase. However, the hexokinase showed little catalytic capacity for galactose and fructose. Circular dichroism measurements indicated that the enzyme was structurally stable at 90°C. The crystal structure of the enzyme was determined at a resolution of 2.02 ?, with R(cryst) and R(free) values of 18.1% and 22.6%, respectively. The polypeptide structure was divided into large and small domains. The ROK consensus sequences 1 and 2 were included in the large domain. The cysteine-rich consensus sequence 2 folded into a zinc finger, and the bound zinc was confirmed by both electron density and X-ray absorption fine structure (XAFS) spectrum. The overall structure was a homotetramer that consisted of a dimer of dimers. The accessible surface area buried by the association of the dimers into the tetrameric structures was significantly higher in the T. thermophilus enzyme than in a homologous tetrameric ROK sugar kinase.