Pressure-Induced Change in the Long-Period Stacking Sequence of the Close-Packed Layers in Mg_3In(Physics)

Samples of the alloy Mg_3In were annealed at 200-250℃ in the Bridgman-anvil-type press under pressures between 20 and 100 kbar. After being quenched to ambient pressure and temperature, the crystal structure was studied by X-ray diffraction. The number of close-packed layers in one repeating unit of the alloy structure is twelve with the stacking sequence (31)_3 when annealed under the atmospheric pressure, but at 20, 35 and 55 kbar it increases to eighteen with the sequence (3111)_3, and at 75 and 100 kbar a 24-layered structure with the sequence (311111)_3 has been found to form. The pressure-induced change in the layer-stacking sequence in Mg_3In is similar to the change with the decrease in the electron-atom ratio previously observed for the ternary alloys Mg_3(In_, Cd_x)

Composition Dependence of the Long-Period Layer Stacking Sequence in the Structure of the Ternary Alloy Mg_3In_<1-x>Cd_x(Physics)

The effect of the replacement of some fraction of the indium atoms with cadmium atoms on the structural stability of the long-period layer stacking sequence in Mg_3In has been studied by means of X-ray and electron diffraction experiments. The observed changes in electron diffraction patterns can be described by Kakinoki\u27s equation and suggests that when the cadmium content is increased the stacking sequence changes from (31)_3 to (11), passing through (3111)_3, with increasing amount of stacking disorder, while the atomic arrangement in the close-packed plane remains unchanged irrespective of the composition. Structural changes observed in the present investigation have been found similar to the pressure effects in Mg_3In previously reported. The stability of the long-period layer stacking structure is briefly discussed by application of the pseudo-potential theory

An X-ray Investigation of Thermal Mean-Square Atomic Displacements in Magnesium, Cadmium and Mg_3Cd

Measurements have been made of integrated intensities of X-ray symmetrical reflections from single crystals of magnesium, cadmium and Mg_3Cd, kept at temperatures ranging from room temperature to about 90°K. It is observed that the thermal mean-square atomic displacements along two directions, the one parallel to the hexagonal c-axis u_z^2 and the other perpendicular to the c-axis u_x^2, are nearly the same in Mg_3Cd, showing little anisotropy. The result suggests that thermal vibrational amplitudes in the alloy can not be a simple average of those in magnesium and cadmium. No appreciable difference is observed between the mean-square displacements of an ordered and an imperfectly ordered Mg_3Cd. The mean-square atomic displacements is calculated for magnesium and cadmium applying Zener\u27s theory of thermal vibration in hexagonal crystals and is compared with the observed displacements. Discussions are given on the correlation between u_z^2 / u_x^2 and the axial ratio, c/a, of hexagonal close-packed metals and also on the thermal mean-square displacements in alloys

Comparison of the Choice Effect and the Distance Effect in a Number-Comparison Task by fMRI

Behavioral and neurophysiological studies of numerical comparisons have shown a “distance effect,” whereby smaller numerical distances between two digits are associated with longer response times and higher activity in the parietal region. In this experiment, we introduced a two-choice condition (between either the smaller/lower or the larger/higher of two digits) and examined its effect on brain activity by fMRI. We observed longer response times and greater activity with the choice of smaller numbers (“choice effect”) in several brain regions including the right temporo–parietal region, (pre)cuneus, superior temporal sulcus, precentral gyrus, superior frontal gyrus, bilateral insula, and anterior cingulate cortex. These regions correspond to areas that have been suggested to play a role in attentional shift and response conflict. However, brain activity associated with the distance effect disappeared even though the behavioral distance effect remained. Despite the absence of the distance effect on brain activity, several areas changed activity in relation to response time, including regions that were reported to change activity in both a distance effect and a reaction-time-related manner. The result suggested that the level of task load may change the activity of regions that are responsible for magnitude detection

Detection of RBM15-MKL1 Fusion Was Useful for Diagnosis and Monitoring of Minimal Residual Disease in Infant Acute Megakaryoblastic Leukemia

Acute megakaryocytic leukemia (AMKL) with t(1;22)(p13;q13) is a distinct category of myeloid leukemia by WHO classification and mainly reported in infants and young children. Accurate diagnosis of this type of AMKL can be difficult, because a subset of patients have a bone marrow (BM) blast percentage of less than 20% due to BM fibrosis. Therefore, it is possible that past studies have underestimated this type of AMKL. We present here the case of a 4-month-old female AMKL patient who was diagnosed by presence of the RBM15-MKL1 (OTT-MAL) fusion transcript by RT-PCR. In addition, we monitored RBM15-MKL1 fusion at several time points as a marker of minimal residual disease (MRD), and found that it was continuously negative after the first induction chemotherapy even by nested RT-PCR. Detection of the RBM15-MKL1 fusion transcript thus seems to be useful for accurate diagnosis of AMKL with t(1;22)(p13;q13). We recommend that the RBM15-MKL1 fusion transcript be analyzed for all suspected AMKL in infants and young children. Furthermore, monitoring of MRD using this fusion transcript would be useful in treatment of AMKL with t(1;22)(p13;q13)

Different histological types of non-small cell lung cancer have distinct folate and DNA methylation levels

金沢大学がん研究所分子標的がん医療研究開発センターAberrant DNA methylation is a commonly observed epigenetic change in lung cancer. Folate has been suggested to play a role in the homeostasis of DNA methylation and has also been implicated in cancer chemotherapy. We investigated a possible role for folate in DNA methylation by measuring folate concentrations in tumors and adjacent normal tissues from 72 non-small cell lung cancer (NSCLC) patients. These were compared to DNA methylation levels and to clinicopathological features. Folate concentrations were determined as the sum of 5,10-methylenetetrahydrofolate and tetrahydrofolate. The MethyLight assay was used to quantitate methylation in promoter regions of P16(CDKN2A), APC, CDH13, RARB, RASSF1, RUNX3, and MYOD1. Methylation of LINE-1 repeats was used as a surrogate for global methylation. Folate levels in tumors correlated positively with LINE-1, CDH13, and RUNX3 methylation. Folate concentrations and methylation of LINE-1, RASSF1, and RUNX3 were significantly higher in adenocarcinoma compared to squamous cell carcinoma (SCC). Two sets of array-based data retrieved from the Gene Expression Omnibus consistently showed that expression of FOLR1, a folate transport enzyme, and GGH, an enzyme that prevents folate retention, were higher and lower, respectively, in adenocarcinomas compared to SCC. This was independently validated by quantitative RT-PCR in 26 adenocarcinomas and 13 SCC. Our results suggest that folate metabolism plays a role in aberrant DNA methylation in NSCLC. The histological subtype differences in folate concentration and DNA methylation observed here were associated with distinct expression patterns for folate metabolizing enzymes. These findings may have clinical applications for histology-directed chemotherapy with fluoropyrimidine and anti-folates in NSCLC. © 2009 Japanese Cancer Association

A high harmonic gyrotron with an axis-encircling electron beam and a permanent magnet

A gyrotron with an axis-encircling electron beam is capable of high-frequency operation, because the high-beam efficiency is kept even at high harmonics of the electron cyclotron frequency. We have designed and constructed such a gyrotron with a permanent magnet. The gyrotron has already operated successfully at the third, fourth, and fifth harmonics. The frequencies are 89.3, 112.7, and 138 GHz, respectively, and the corresponding cavity modes are TE/sub 311/, TE/sub 411/, and TE/sub 511/. The permanent magnet system is quite novel and consists of many magnet elements made of NbFeB and additional coils for controlling the field intensities in the cavity and electron gun regions. The magnetic field in the cavity region can be varied from 0.97 to 1.18 T. At the magnetic field intensities, the output powers at the third and the fourth harmonics are 1.7 and 0.5 kW, respectively. The gyrotron is pulsed, the pulse length is 1 ms and the repetition frequency is 1 Hz. The beam energy is 40 kV and the beam current is 1.2-1.3 A. Beam efficiencies and emission patterns have also been measured. In this paper, the experimental results of the gyrotron are described and compared with computer simulations

Roles of PsbI and PsbM in photosystem II dimer formation and stability studied by deletion mutagenesis and X-ray crystallography

PsbM and PsbI are two low molecular weight subunits of photosystem II (PSII), with PsbM being located in the center, and PsbI in the periphery, of the PSII dimer. In order to study the functions of these two subunits from a structural point of view, we crystallized and analyzed the crystal structure of PSII dimers from two mutants lacking either PsbM or PsbI. Our results confirmed the location of these two subunits in the current crystal structure, as well as their absence in the respective mutants. The relative contents of PSII dimers were found to be decreased in both mutants, with a concomitant increase in the amount of PSII monomers, suggesting a destabilization of PSII dimers in both of the mutants. On the other hand, the accumulation level of the overall PSII complexes in the two mutants was similar to that in the wild-type strain. Treatment of purified PSII dimers with lauryldimethylamine N-oxide at an elevated temperature preferentially disintegrated the dimers from the PsbM deletion mutant into monomers and CP43-less monomers, whereas no significant degradation of the dimers was observed from the PsbI deletion mutant. These results indicate that although both PsbM and PsbI are required for the efficient formation and stability of PSII dimers in vivo, they have different roles, namely, PsbM is required directly for the formation of dimers and its absence led to the instability of the dimers accumulated. On the other hand, PsbI is required in the assembly process of PSII dimers in vivo; once the dimers are formed, PsbI was no longer required for its stability