Energies and Atomic Structures of Grain Boundaries in Diamond: Comparison With Grain Boundaries in Silicon

Fairly different features of grain boundaries in diamond from those in Si were experimentally observed in diamond thin films. As the first step in order to understand the fundamental properties of grain boundaries in diamond, the energy and atomic structure of the {122} σ=9 tilt boundary have been calculated for the first time by using the tight-binding electronic theory. The results have been compared with the calculations of the same boundary and the {111} σ=3 boundary in Si. It has been shown that the σ=9 boundary in diamond has a very large interfacial energy caused by the large bond rigidity as compared with the boundaries in Si and the {111}σ=3 boundary in diamond. This point should be related to the observation that the {122}σ =9 boundary is rarely found in diamond thin films.

Atomic and Electronic Structures of Grain Boundary in Chemical Vapor Deposited Diamond Thin Film

High resolution electron microscopy and electron energy-loss spectrometry were used to investigate both atomic and electronic structures of grain boundaries in diamond thin films grown by chemical vapor deposition. The atomic structures of {112}σ3 and {114}σ9 <110= tilt boundaries in diamond show different features from those in other diamond structure semiconductors. The electron energy-loss spectra recorded from the grain boundary regions show extra intensity near the energy-loss corresponding to carbon 1s-to-π*; transition, as compared to the spectra recorded from neighboring crystalline regions. This gives the evidence that the dangling bonds are not fully reconstructed along <110= direction in the boundary structure. Atomic models are constructed for these boundaries with the presence of non-tetracoordinated atoms. The stability of the boundary structure is explained by the π-like bonding between the nontetracoordinated atoms.

Structural and Optical Characterization of High-Quality Cubic GaN Epilayers Grown on GaAs and 3C-SiC Substrates by Gas-Source MBE Using RHEED In Situ Monitoring

By monitoring RHEED reconstruction patterns during gas source molecular beam epitaxy growth, the optimization of the growth for cubic GaN was carried out successfully. Cubic GaN epilayer having a X-ray diffraction width of 16min and a low temperature photoluminescence emission width of 19meV was obtained on a 3C-SiC substrate by adjusting the effective III/V ratio in-situ during the growth, which can be inferred from the surface reconstruction transitions. It was found that the surface reconstructions of cubic GaN surfaces are good indices for the optimization of growth parameters.

Pseudogap of metallic layered nickelate R(2-x)Sr(x)NiO4 (R = Nd, Eu) crystals measured using angle-resolved photoemission spectroscopy

We have investigated charge dynamics and electronic structures for single crystals of metallic layered nickelates, R(2-x)Sr(x)NiO4 (R = Nd, Eu), isostructural to La(2-x)Sr(x)CuO4. Angle-resolved photoemission spectroscopy on the barely metallic Eu(0.9)Sr(1.1)NiO4 (R = Eu, x = 1.1) has revealed a large hole surface of x2-y2 character with a high-energy pseudogap of the same symmetry and comparable magnitude with those of underdoped (x<0.1) cuprates, although the antiferromagnetic interactions are 1 order of magnitude smaller. This finding strongly indicates that the momentum-dependent pseudogap feature in the layered nickelate arises from the real-space charge correlation.

Drug susceptibility and clonality of methicillin-resistant Staphylococcus epidermidis in hospitalized patients with hematological malignancies

PURPOSE

To evaluate the clonal relatedness and drug susceptibility of Streptococcus epidermidis isolated from hematological patients.

METHODS

All S. epidermidis isolated from hematological patients who developed bloodstream infections between June 2005 and December 2007 were included. The clonal relationship was tested by means of pulsed-field gel electrophoresis (PFGE) analysis.

RESULTS

Fifteen methicillin-resistant S. epidermidis (MRSE) isolates were examined from patients' blood culture samples. Two subgroups that differed approximately by 40% in their PFGE banding were identified. In clinical practice, two cases were cured with cephalosporin only, thus demonstrating sensitivity of the strains to beta-lactam antibiotics.

CONCLUSIONS

Our results represent two significant findings. One is the major capability of MRSE to colonize patients. The other is that some MRSE isolates proved to be sensitive to clindamycin, minocycline, and cephalosporin, so that using antibiotics to which MRSE is sensitive as first-line therapy can avoid the need for vancomycin in clinical settings.

Orbital-dependent modifications of electronic structure across the magnetostructural transition in BaFe2As2

Laser angle-resolved photoemission spectroscopy (ARPES) is employed to investigate the temperature (T) dependence of the electronic structure in BaFe2As2 across the magnetostructural transition at T{N} approximately 140 K. A drastic transformation in Fermi surface (FS) shape across T{N} is observed, as expected by first-principles band calculations. Polarization-dependent ARPES and band calculations consistently indicate that the observed FSs at k{z} approximately pi in the low-T antiferromagnetic state are dominated by the Fe3d{zx} orbital, leading to the twofold electronic structure. These results indicate that magnetostructural transition in BaFe2As2 accompanies orbital-dependent modifications in the electronic structure.

Central endogenous vasopressin induced by central salt-loading participates in body fluid homeostasis through modulatory effects on neurones of the paraventricular nucleus in conscious rats

Peripherally secreted arginine vasopressin (AVP) plays a role in controlling body fluid homeostasis, and central endogenous AVP acts as a neurotransmitter or neuromodulator. The limbic system, which appears to exert an inhibitory effect on the endocrine hypothalamus, is also innervated by fibres that contain AVP. We examined whether central endogenous AVP is also involved in the control of body fluid homeostasis. To explore this possibility, we examined neuronal activity in the paraventricular nucleus of the hypothalamus (PVN), periventricular parts of the PVN and limbic brain areas, as well as AVP mRNA expression in the PVN and the peripheral secretion of AVP after central salt-loading in rats that had been pretreated i.c.v. with the AVP V(1) receptor antagonist OPC-21268. Neuronal activity in the PVN evaluated in terms of Fos-like immunoreactivity (FLI), especially in the parvocellular subdivisions, was suppressed. On the other hand, FLI was enhanced in the lateral septum, the bed nucleus of the stria terminalis and the anterior hypothalamic area. Similarly, AVP mRNA expression was enhanced in the magnocellular subnucleus of the PVN, despite the lack of a significant difference in the peripheral AVP level between OPC-21268- and vehicle-pretreated groups. We recorded renal sympathetic nerve activity (RSNA) as sympathetic nerve outflow during central salt-loading. The suppression of RSNA was significantly attenuated by i.c.v. pretreatment with OPC-21268. These results suggest that the suppression of RSNA during central salt-loading might be the result of a decrease in neuronal activity in the parvocellular subdivisions of the PVN via the inhibitory action of central endogenous AVP. The parvocellular and magnocellular neurones in the PVN might show different responses to central salt-loading to maintain body fluid homeostasis as a result of the modulatory role of central endogenous AVP.

Spectroscopic evidence for competing reconstructions in polar multilayers LaAlO3/LaVO3/LaAlO3

We have studied the valence redistribution of V in LaAlO(3)/LaVO(3)/LaAlO(3) trilayers, which are composed of only polar layers grown on SrTiO3 (001) substrates, by core-level photoemission spectroscopy. We have found that the V valence is intermediate between V3+ and V4+ for thin LaAlO3 cap layers, decreases with increasing cap-layer thickness, and finally recovers the bulk value of V3+ at approximately 10 unit-cell thickness. In order to interpret these results, we propose that the atomic reconstruction of the polar LaAlO3 surface competes with the purely electronic V valence change so that the polar catastrophe is avoided at the cost of minimum energy.

The significance of urine NMP22 in the screening of urothelial cancer (comparison of ELISA and immunochromatography method)

e16024

Background: The early diagnosis of urothelial cancer allows for effective local treatment and optimizes the success of surgical therapy. Urine nuclear matrix protein 22 (NMP22) was introduced for the detection of transitional cell carcinoma. Add to old NMP22 (ELISA), new NMP22 (immunochromotography method : BladderChek) can be available from 2004. The objective of this study is to determine whether there are any correlation between urine NMP22 (two methods) and the grade or stage of urothelial cancer, and whether it can serve as a biochemical marker of urothelial cancer. Methods: A total of 246 patients with hematuria or followed up after TUR-BT, from March 2007 to December 2007,visited our hospital and subsequently underwent cystoscopy. The 246 patients provided voided urine samples. We immediately examined urine cytology and NMP22 (two methods). We set the cut off value on 12.0U/ml for NMP22 (ELISA). NMP22 (BladderChek) was judged by qualitative analysis. We decided that in urine cytology, classI,II,III were negative, while IV,V were positive by Papanicolaou classification. Results: Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) were 66.7 %, 98.3 %, 81.8 %, 96.3 % in urine cytology, 40.7 %, 75.9 %, 16.2 %, 91.8 % in NMP22 (ELISA), 59.3 %, 79.3 %, 24.6 %, 94.5 % in NMP22 (BladderChek). In 9 cases with false negative of urine cytology, 4 cases were picked up by NMP22 (ELISA), and 5 cases by NMP22 (BladderChek). Sensitivity of grade 1 was 33.3 % in urine cytology, while 66.7 % in NMP22 (BladderChek). By adding NMP22 (BladderChek) to urine cytology, sensitivity rose about 18 %. Conclusions: The sensitivity of urine cytology was unexpectedly high. NMP22 (BladderChek) is more useful than NMP22 (ELISA) because of higher sensitivity, specificity and advantage of simplicity, rapidity. It seems that the addition of NMP22 (BladderChek) to urine cytology is beneficial.

No significant financial relationships to disclose.

Precision measurement of the hyperfine structure of laser-cooled radioactive 7Be+ ions produced by projectile fragmentation

The ground state hyperfine splitting of (7)Be+ has been measured by laser-microwave double-resonance spectroscopy in the online rf trap of RIKEN's slow RI-beam facility. Be ions produced by projectile fragmentation of 13C at approximately 1 GeV were thermalized in a rf ion guide gas cell and subsequently laser cooled in the ion trap to approximately 1 microeV. This 10(15)-fold reduction of the kinetic energy allows precision spectroscopy of these ions. A magnetic hfs constant of A=-742.772 28(43) MHz was measured for 7Be+, from which a nuclear magnetic moment of mu(I)=-1.399 28(2)mu(N) was deduced.