A-type antiferro-orbital ordering with I4(1)/a symmetry and geometrical frustration in the spinel vanadate MgV2O4

We conduct a detailed structural analysis of the S=1 pyrochlore antiferromagnet MgV2O4, which exhibits an antiferromagnetic ordering marginally at TN=40  K, triggered by a structural transition from cubic to tetragonal symmetry at TS=62  K, using high resolution synchrotron x-ray diffraction and convergent beam electron diffraction. We reveal that the tetragonal phase below TS has the symmetry of I4(1)/a and that the distortion pattern of VO6 octahedra is consistent with A-type antiferro-orbital ordering with alternating stacking of layers with yz/xy orbital chains and zx/xy orbital chains along the tetragonal c axis. This implies that an anisotropic coupling of V moments produced by the orbital ordering below TS primarily brings about the antiferromagnetic ordering.

Functional variants in the thromboxane A2 receptor gene are associated with lung function in childhood-onset asthma

BACKGROUND

The thromboxane A2 receptor (TBXA2R) gene is associated with asthma, but no functional genetic variations are known to associate with the disease or its related phenotypes.

OBJECTIVE

To investigate the association of TBXA2R polymorphisms with asthma susceptibility and related phenotypes and to identify functionally relevant polymorphisms.

METHODS

We performed comprehensive sequencing of the TBXA2R gene in 48 Japanese control subjects and found a set of variants (SNP1 G>T rs2238634, SNP2 T>G rs2238633, SNP3 C>T rs2238632 and SNP4 G>A rs2238631) in intron 1 in linkage disequilibrium with c.795 T>C rs1131882, which was previously reported to be associated with asthma and related phenotypes. To investigate the effect of four common haplotypes (H1, H2, H3 and H4) on transcriptional activity, we performed a luciferase assay in primary bronchial smooth muscle cells (BSMCs) and human airway epithelial cells (BEAS-2B). We also studied the haplotype association with lung function, TBXA2R mRNA levels, and eosinophil fraction/count in peripheral blood in childhood-onset asthma patients and/or controls.

RESULTS

H2 and H4, containing minor alleles of SNP2 and SNP3, had significantly higher transcriptional activities than H1 consisting of major alleles (P < 0.001 in BSMCs and BEAS-2B). Homozygotes for redefined haplotype h2 corresponding to minor alleles of SNP2 and SNP3 were associated with lower lung function in childhood-onset asthma patients compared to other zygotes (baseline Forced expiratory volume in one second (FEV1)/ Forced vital capacity (FVC) and Forced expiratory flow between 25% and 75% of the FVC (%FEF(25-75%)): P = 0.00201 and 0.0128, respectively, and post-bronchodilator FEV1/FVC and %FEF(25-75%): P = 0.00224 and 0.0393 respectively). Haplotype h2 was also associated with higher mRNA levels in control peripheral blood cells and higher blood eosinophil fractions and counts in female controls.

CONCLUSIONS AND CLINICAL RELEVANCE

Genetic variants were identified in the TBXA2R gene that influenced transcriptional activity and were associated with asthma-related phenotypes. Thromboxane pathways may therefore play important roles in airway inflammation and remodelling in asthma patients.

Effects of interocclusal distance on bite force and masseter EMG in healthy participants

The aim of this study was to investigate effects of interocclusal distance (IOD) on bite force and masseter electromyographic (EMG) activity during different isometric contraction tasks. Thirty-one healthy participants (14 women and 17 men, 21·2 ± 1·8 years) were recruited. Maximal Voluntary Occlusal Bite Force (MVOBF) between the first molars and masseter EMG activity during all the isometric-biting tasks were measured. The participants were asked to bite at submaximal levels of 20%, 40%, 60% and 80% MVOBF with the use of visual feedback. The thickness of the force transducer was set at 8, 12, 16 and 20 mm (= IOD), and sides were tested in random sequence. MVOBF was significantly higher at 8 mm compared with all other IODs (P < 0·001). Only in women, IOD always had significant influence on the corresponding root-mean-square (RMS) value of EMG (P < 0·011). When biting was performed on the ipsilateral side to the dominant hand, the working side consistently showed higher masseter EMG activity compared with the balancing side (P < 0·020). On the contralateral side, there was no difference between the masseter EMG at any IODs. The results replicated the finding that higher occlusal forces can be generated between the first molars at shorter IODs. The new finding in this study was that an effect of hand dominance could be found on masseter muscle activity during isometric biting. This may suggest that there can be a general dominant side effect on human jaw muscles possibly reflecting differences in motor unit recruitment strategies.

Structural phase transition and magnetic-field effect on the modulated structure in GdBaCo2O5+δ (δ < 0.5)

We investigated the crystal structures of an ordered perovskite-type cobaltate, GdBaCo2O(5+δ) (δ < 0.5), at elevated temperatures by transmission electron microscopy. Above the magnetic ordering temperature, we observed a first-order structural phase transition between the low-temperature tetragonal 3a(p) × 3a(p) and high-temperature orthorhombic 1a(p) × 2a(p) superstructure phases (where a(p) is the perovskite-unit cell). Upon the application of a magnetic field, an incommensurate phase emerges around the structural phase-transition temperature, which indicates a magnetic-field-induced structural phase transition via no magnetic ordering in the ordered perovskite-type cobaltate.

Diffusion of Technetium in Compacted Bentonites in the Reducing Condition with Corrosion Products of Iron

In the vicinity of a high-level waste repository, corrosion of carbon steel overpacks will create a reducing environment. Reducing conditions are expected to retard the migration of redox-sensitive radionuclides such as technetium.

The apparent diffusion coefficients of technetium were measured in compacted bentonites (Kunigel VI® and Kunipia F®, JAPAN) in contact with carbon steel and its corrosion products under reducing conditions or without carbon steel under oxidizing conditions for comparison. The apparent diffusion coefficients measured were 10-12 to 10-13 m2/s under oxidizing conditions and 10-12 to 10-13 m2/s under reducing conditions. There were significant effects of redox condition, dry density (0.2 to 2.3 g / cm3) and montmorillonite content (50% for Kunigel VI or 100% for Kunipia F) on the apparent diffusion coefficients. Montmorillonite density could be a good index to explain density dependence of the diffusion coefficients under both reducing and oxidizing conditions.

Tetrahedral magnetic order and the metal-insulator transition in the pyrochlore lattice of Cd2Os2O7

Cd2Os2O7 shows a peculiar metal-insulator transition at 227 K with magnetic ordering in a frustrated pyrochlore lattice, but its magnetic structure in the ordered state and the transition origin are yet uncovered. We observed a commensurate magnetic peak by resonant x-ray scattering in a high-quality single crystal. X-ray diffraction and Raman scattering experiments confirmed that the transition is not accompanied with any spatial symmetry breaking. We propose a noncollinear all-in-all-out spin arrangement on the tetrahedral network made of Os atoms. Based on this we suggest that the transition is not caused by the Slater mechanism as believed earlier but by an alternative mechanism related to the formation of the specific tetrahedral magnetic order on the pyrochlore lattice in the presence of strong spin-orbit interactions.

Two-dimensional Heisenberg behavior of J(eff)=1/2 isospins in the paramagnetic state of the spin-orbital Mott insulator Sr2IrO4

The dynamical correlations of J(eff)=1/2 isospins in the paramagnetic state of spin-orbital Mott insulator Sr2IrO4 were revealed by resonant magnetic x-ray diffuse scattering. We found a two-dimensional antiferromagnetic fluctuation with a large in-plane correlation length exceeding 100 lattice spacings at even 20 K above the magnetic ordering temperature. In marked contrast to the naive expectation of the strong magnetic anisotropy associated with an enhanced spin-orbit coupling, we discovered an isotropic isospin correlation that is well described by the two-dimensional S=1/2 quantum Heisenberg model. The estimated antiferromagnetic coupling constant as large as J∼0.1  eV that is comparable to the small Mott gap (<0.5  eV) points out the weak and marginal Mott character of this spin-orbital entangled system.

Craniofacial Pain and Jaw-muscle Activity during Sleep

This study compared the jaw-muscle electromyographic (EMG) activity during sleep in patients with craniofacial pain (n = 63) or no painful conditions (n = 52) and between patients with tension-type headache (TTH: n = 30) and healthy control individuals (n = 30). All participants used a portable single-channel EMG device (Medotech A/S) for four nights. There was no significant difference in EMG activity between craniofacial pain (24.5 ± 17.9 events/hr) and no painful conditions (19.7 ± 14.5), or between TTH (20.8 ± 15.0) and healthy control individuals (15.2 ± 11.6, p >.050). There were positive correlations between EMG activity and number of painful muscles (r = 0.188; p = 0.044), characteristic pain intensity (r = 0.187; p = 0.046), McGill Pain Questionnaire (r = 0.251; p = 0.008), and depression scores (r = 0.291; p = 0.002). Patients with painful conditions had significantly higher night-to-night variability compared with pain-free individuals (p < 0.050). This short-term observational study suggests that there are no major differences between patients with different craniofacial pain conditions and pain-free individuals in terms of jaw-muscle EMG activity recorded with a single-channel EMG device during sleep. However, some associations may exist between the level of EMG activity and various parameters of craniofacial pain. Longitudinal studies are warranted to further explore the relationship between sleep bruxism and craniofacial pain.

Displacement-type ferroelectricity with off-center magnetic ions in perovskite Sr(1-x)Ba(x)MnO3

We report a ferroelectric transition driven by the off-centering of magnetic Mn(4+) ions in antiferromagnetic Mott insulators Sr(1-x)Ba(x)MnO(3) with a perovskite structure. As x increases, the perovskite lattice shows the typical soft-mode dynamics, as revealed by the momentum-resolved inelastic x-ray scattering and far-infrared spectroscopy, and the ferroelectricity shows up for x ≥ 0.45. The observed polarization is comparable to that for a prototypical ferroelectric BaTiO(3). We further demonstrate that the magnetic order suppresses the ferroelectric lattice dilation by ∼70% and increases the soft-phonon energy by ∼50%, indicating the largest magnetoelectric effects yet attained.

Large topological Hall effect in a short-period helimagnet MnGe

We have observed an unconventional, likely topological, Hall effect over a wide temperature region in the magnetization process of a chiral-lattice helimagnet MnGe. The magnitude of the topological Hall resistivity is nearly temperature-independent below 70 K, which reflects the real-space fictitious magnetic field proportional to a geometric quantity (scalar spin chirality) of the underlying spin texture. From the neutron diffraction study, it is anticipated that a relatively short-period (3-6 nm) noncoplanar spin structure is stabilized from the proper screw state in a magnetic field to produce the largest topological Hall response among the B20-type (FeSi-type) chiral magnets.

The correlation between the clinical laboratory data and the telomere length in peripheral blood leukocytes of Japanese female patients with hypertension

OBJECTIVE

This study investigated the correlation between the chronological age, telomere length in peripheral blood leukocytes and blood laboratory data of female patients with mild hypertension to identify laboratory data that reflect the biological aging of individuals.

DESIGN

Cross-sectional population-based study.

SETTING

Outpatient clinic of the Department of Cardiovascular, Respiratory, and Geriatric Medicine Kyushu University Hospital at Beppu in Japan.

PARTICIPANTS

Outpatients with mild hypertension treated with a low dose of amlodipine.

MEASUREMENTS

The laboratory data of female patients were collected and the telomere length parameters in their peripheral blood leukocytes were determined by Southern blotting. Any correlations between the laboratory data and the telomere length parameters were assessed.

RESULTS

The patients showed a positive correlation between the telomere length and the high density lipoprotein, albumin, creatinine, hemoglobin levels, red blood cell counts, and a negative correlation with the globulin level. The extent of subtelomeric methylation of long telomeres tended to correlate negatively with the telomeric attrition. Only the creatinine level correlated with subtelomeric methylation, but not with telomeric length.

CONCLUSION

HDL and the albumin/globulin ratio were potential indicators for individual somatic genomic aging. Creatinine may therefore be a useful indicator for a predisposition for telomeric attrition.

Diffusion of Uranium in Compacted Bentonites in the Reducing Condition with Corrosion Products of Iron

In high-level waste repository, a carbon steel overpack will be corroded after closure. This will create a reducing environment in the vicinity of the repository. Reducing conditions are expected to retard the migration of redox-sensitive radionuclides such as uranium.

The apparent diffusion coefficients of uranium were measured in compacted bentonites (Kunigel VI® and Kunipia F®, JAPAN) in contact with carbon steel and its corrosion products under reducing conditions or without carbon steel under oxidizing conditions for comparison. The apparent diffusion coefficients measured were 10-12 to 10-14 m2/s under oxidizing conditions and 10-13 to 10-14 m2/s under reducing conditions. There were significant effects of redox conditions, dry density (0.8 to 2.0 g/cm3) and montmorillonite contents (60% for Kunigel VI or 100% for Kunipia F) on the apparent diffusion coefficients. The sorption of uranium on corrosion products of iron was smaller than that on montmorillonite. Montmorillonite density could be a good index to explain density dependence of the diffusion coefficients under the reducing conditions. Uranium would diffuse in free pore water with diffusion coefficients greater than 10-13 m2/s in low density bentonites under both redox conditions because the diffusion coefficients depended on sorption coefficients. Since diffusion coefficients were independent of sorption coefficients in high density bentonites where free pore water is scarce, surface diffusion might occur with coefficients were of about 10-13 m2/s.

Measurement of initial dissolution rate of P0798 simulated HLW glass by using micro-reactor flow-through test method

We applied a new type of flow-through test method using micro-reactor consisting of a simple test apparatus with compact size to measurement of the dissolution rate of a Japanese type of simulated waste glass (P0798 glass). In this test method, a solution flows through a micro-channel (20 mm length, 2 mm width, 0.16 mm depth) in contact with a face of coupon shaped glass specimen, and the output solution is retrieved at certain intervals to be analyzed for determination of the glass dissolution rate. By using this test method the initial dissolution rate of glass matrix or forward dissolution rate was measured as a function of pH (3 to 11) and temperature (25°C to 90°C). The present test results indicated that the initial dissolution rate has ‘V-shaped’ pH dependence, and the effect of pH on the dissolution rate decreases with increase in temperature similar to the results measured by using the Single-pass flow-through (SPFT) method. The present test results also indicated that the dissolution of B is controlled by diffusion process and that of Si is controlled by surface reaction process.

Diffusion of Cs and Sr in Compacted Bentonites Under Reducing Conditions and in the Presence of Corrosion Products of Iron

In high-level waste repositories, a carbon steel overpack will be corroded by consuming oxygen trapped in the repository after closure. Iron corrosion products are expected to interfere with migration of radionuclides by filling the pore in bentonite and sorbing radionuclides. In this study the apparent diffusion coefficients of cesium and strontium were measured in compacted Na-bentonites (Kunigel VI® and Kunipia F®, JAPAN) contacted with carbon steel and its corrosion products under reducing conditions or without carbon steel under oxidizing conditions for comparison. The apparent diffusion coefficients of cesium with and without corrosion product were 2.2 to 13 × 10−12 m2/s. The apparent diffusion coefficients of strontium with and without corrosion product were 3.1 to 25 × 10−12 m2/s. There were significant effects of dry density (0.8 to 2.0 g/cm3) and montmorillonite contents (50% for Kunigel V1 or 100% for Kunipia F). The presence of corrosion product decreased the apparent diffusion coefficients of Cs in both bentonites and that of Sr in Kunigel V1, especially at low dry density. This may be due to corrosion product filling the pore in the bentonite, decreasing the free pore size and density for diffusion.

Effects of Water Redox Conditions and Presence of Magnetite on Leaching of Pu and Np From HLW Glass

The objective of this study is to evaluate the effects of water redox conditions and of the presence of iron corrosion products (magnetite) on the release of actinides from HLW glasses. Static corrosion tests were performed on a simulated HLW glass doped with Pu and Np in deionized water in the presence of magnetite under oxidizing and reducing conditions. The tests under oxidizing conditions were performed in air, while the tests under reducing conditions were performed in mixed gas (Ar+5%H2) atmosphere.

The following results were obtained: (1) The presence of magnetite enhances formation of colloids containing Pu and Np in the leachates under both redox conditions. (2) Redox conditions have no remarkable influence on the release of Pu. (3) The reducing conditions combined with the presence of magnetite cause a decrease in the concentrations of Np dissolved species, which is probably the result of the reduction of Np(V) to Np(IV) at the magnetite surface.

Multiferroic M-type hexaferrites with a room-temperature conical state and magnetically controllable spin helicity

Magnetic and magnetoelectric (ME) properties have been studied for single crystals of Sc-doped M-type barium hexaferrites. Magnetization (M) and neutron diffraction measurements revealed that by tuning Sc concentration a longitudinal conical state is stabilized up to above room temperatures. ME measurements have shown that a transverse magnetic field (H) can induce electric polarization (P) at lower temperatures and that the spin helicity is nonvolatile and endurable up to near the conical magnetic transition temperature. It was also revealed that the response (reversal or retention) of the P vector upon the reversal of M varies with temperature. In turn, this feature allows us to control the relation between the spin helicity and the M vectors with H and temperature.

The correlation between the telomeric parameters and the clinical laboratory data in the patients with brain infarct and metabolic disorders

OBJECTIVE

To elucidate the correlation between the telomere length and subtelomeric methylated status in peripheral leukocytes and the laboratory data of inpatients with brain infarction and metabolic disorders. This is the first report describing a link between routine clinical laboratory data and genomic aging.

DESIGN

Cross-sectional population-based study.

SETTING

Chronic disease ward of Kyushu University Hospital at Beppu in Japan.

PARTICIPANTS

Inpatients with brain infarction and metabolic disorders.

MEASUREMENTS

The laboratory data of male patients were collected and the telomeric parameters in their peripheral leukocytes were determined by a Southern blot analysis with methylation-sensitive and insensitive isoschizomers. Any correlations between the laboratory data and the telomeric parameters were assessed.

RESULTS

The patients revealed a significant correlation among the fasting blood sugar, HbA1c, serum creatinine and urea nitrogen levels with the mean telomere length, expression of long telomeres ( > 9.4 kb), or the subtelomeric hypermethylation status of long telomeres.

CONCLUSION

Our results suggested that the hyperglycemia and renal function of patients with metabolic disorders correlated positively with the aging-associated telomeric changes.

Orbital dilution effect in ferrimagnetic Fe(1-x)Mn(x)Cr(2)O(4): competition between anharmonic lattice potential and spin-orbit coupling

Magnetic and structural phase diagram in a spinel-type solid solution system Fe(1-x)Mn(x)Cr(2)O(4) has been investigated. The cubic-to-tetragonal transition temperature T(s 1) is gradually reduced by the substitution of Mn(2+) (3d(5)) for Jahn-Teller-active Fe(2+) (3d(6)) ions, implying the long-range nature of the ferroic interaction between orbitals. In the paramagnetic tetragonal phase for x < 0.5, the c parameter is shorter than a because of the anharmonicity of the elastic energy. The crystal structure further changes to orthorhombic at around the ferrimagnetic transition temperature T(N 1). T(s 1) and T(N 1) meet at x = 0.5, and Mn substitution of more than 0.5 gives rise to another tetragonal phase with a < c. The systematic change in crystal structure is discussed in terms of competition between the anharmonic lattice potential and the intra-atomic spin-orbit interaction at Fe(2+).

Comment on 'Calculated chiral and magneto-electric dichroic signals for copper metaborate (CuB(2)O(4)) in an applied magnetic field'

Contrary to a claim by Lovesey and Staub (2009 J. Phys.: Condens. Matter 21 142201), a careful treatment of symmetry shows that the application of a magnetic field along a twofold axis can induce the crystallographic chirality in a tetragonal system with the point group [Formula: see text] like CuB(2)O(4). The chirality is reversed by a 90° rotation of the magnetic field around the c axis.

Magnetic-field-induced polarization flop in multiferroic TmMn2O5

We discovered a reversible electric polarization flop from the a axis (P(a)) to the b axis (P(b)) in multiferroic TmMn2O5 below 5 K by applying a magnetic field of approximately 0.5 T along the c axis. This phenomenon is the first example of the rare-earth (R) compound RMn2O5. This magnetic-field-induced polarization flop corresponds to a magnetic phase transition from one incommensurate magnetic (ICM) P(a) phase to another ICM P(b) phase, which is equivalent to an ICM P(b) phase above 5 K under no magnetic field. The spin chirality in the bc plane, which was observed in the P(b) phase by polarized neutron diffraction, disappeared in the ICM P(a) phase. This indicates that the polarization in the ICM phases of TmMn2O5 was induced by an S(i) x S(j)-type interaction.