Synthesis and optical characterization of vertically grown ZnO nanowires in high crystallinity through vapor-liquid-solid growth mechanism

The gas-phase growth and optical characteristics of 1-dimensional ZnO nanostructure have been investigated. The ZnO nanowires (NWs) were grown vertically on Au coated silicon substrates by vapor-liquid-solid (VLS) growth mechanism using chemical vapor deposition (CVD). The ZnO NWs were grown in the crystal direction of [0 0 0 1]. The ZnO NWs exhibit the uniform size of less than 100 nm in diameter and up to 5 μm in length. Photoluminescence (PL) spectrum of ZnO NWs shows the strong band-edge emission at ∼380 nm (∼3.27 eV) without significant deep-level defect emission. The exciton lifetime of ZnO NWs was measured to be approximately 150 ± 10 ps.     

Intrinsic ligament and triangular fibrocartilage complex (TFCC) tears of the wrist: comparison of isovolumetric 3D-THRIVE sequence MR arthrography and conventional MR image at 3 T

Purpose

The purpose of the study was to validate the diagnostic performance of high-resolution isovolumetric magnetic resonance arthrography (MRA) for intrinsic ligament and triangular fibrocartilage complex (TFCC) tears of the wrist as compared to conventional MR imaging (MRI).

Materials and methods

Forty-eight patients with traumatic TFCC tears at arthroscopy were enrolled. All patients had underwent proton-density- and T2-weighted MRI before arthrography and three-dimensional T1 high-resolution isovolumetric examination (3D-THRIVE) MRA on a 3-T MR. We assessed the presence of scapholunate interosseous ligament (SLIL)/lunotriquetral interosseous ligament (LTIL) or TFCC tears using the arthroscopy as a gold standard.

Results

Arthroscopy revealed 37 TFCC central tears, 15 TFCC peripheral tears, 20 SLIL tears and 13 LTIL tears. Sensitivities of MRI and MRA were 70.3% and 94.6% for detection of TFCC central tears, 60.0% and 93.3% for detection of TFCC peripheral tears, 65.0% and 85.0% for SLIL tears, and 61.5% and 84.6% for LTIL tears. The specificity of the MRI was 100% for the detection of ligaments and TFCC tears. The specificities of the MRA for detection of TFCC central tears, TFCC peripheral tears, SLIL tears and LTIL tears were 100%, 97%, 96.4% and 100%, respectively.

Conclusion

Isovolumetric 3D-THRIVE wrist MRA provided better results for depiction of intrinsic ligament and TFCC tears than wrist MRI.     

Real Hypersurfaces in Complex Two-plane Grassmannians with {\mathfrak{D}^{\bot}}-Parallel Shape Operator

In this paper we consider a new notion of ${\mathfrak{D}^{\bot}}$ -parallel shape operator for real hypersurfaces in complex two-plane Grassmannians ${G_2(\mathbb{C}^{m+2})}$ and give a non-existence theorem for a Hopf hypersurface in ${G_2(\mathbb{C}^{m+2})}$ with ${\mathfrak{D}^{\bot}}$ -parallel shape operator.     

Hypersurfaces with isometric Reeb flow in complex hyperbolic two-plane Grassmannians

We classify the real hypersurfaces with isometric Reeb flow in complex hyperbolic two-plane Grassmannians _SU2,m/S(_U2⋅_Um)${\mathit{SU}}_{2,m}/S(U_2\cdot U_m)$, m?2$m?2$. Each can be described as a tube over a totally geodesic _SU2,m−1/S(_U2⋅_Um−1)${\mathit{SU}}_{2,m-1}/S(U_2\cdot U_{m-1})$ in _SU2,m/S(_U2⋅_Um)${\mathit{SU}}_{2,m}/S(U_2\cdot U_m)$ or a horosphere whose center at infinity is singular.     

A New Reversible Colorimetric Chemosensor Based on Julolidine Moiety for Detecting F−

Journal of Fluorescence - We synthesized an original reversible colorimetric chemosensor PDJ...     

Photocurrent measurements on GaAs1−xNx epilayers grown by metalorganic chemical vapor deposition

GaAs_1−xN_x epilayers were grown on a GaAs(0 0 1) substrate by metalorganic chemical vapor deposition. Composition was determined by high resolution X-ray diffraction. Band gap was measured from 77 to 400 K by using photocurrent measurements. The photocurrent spectra show clear near-band-edge peak and their peak energies drastically decrease with increasing nitrogen composition due to band gap bowing in the GaAs_1−xN_x epilayers. Those red shifts were particularly notable for low nitrogen compositions. However, the shifts tended to saturate when the nitrogen composition become higher than 0.98%. When the nitrogen composition is in the range 1.68–3.11%, the measured temperature dependence of the energy band gap was nicely fitted. However, the properties for the nitrogen composition range 0.31–0.98% could not be fitted with a single fitting model. This result indicates that the bowing parameter reaches 25.39 eV for low nitrogen incorporation (x=0.31%), and decreases with increasing nitrogen composition.     

The tri-methyl-Sb flow and the surfactant time effect on InGaAsN/GaAs-strained MQWs grown by MOCVD

The tri-methyl-Sb flow and the surfactant time dependence of photocurrent (PC) spectra was studied on InGaAsN/GaAs-strained multiple quantum wells (MQWs) structures grown by using metalorganic chemical vapor deposition (MOCVD). The structural properties of InGaAsN/GaAs-strained MQWs were investigated by using high-resolution X-ray diffraction (HRXRD). In the case of InGaAsN/GaAs-strained MQWs, an increase in compressive strain from an analysis of the satellite peaks in HRXRD was observed on increasing the tri-methyl-Sb flow and the surfactant time. For InGaAsN/GaAs-strained MQWs, the peaks observed in the photocurrent spectra were preliminarily assigned to electron–heavy hole (e₁–hh) and electron–light hole (e₁–lh) fundamental excitonic transitions. Their peaks are red-shifted with increasing tri-methyl-Sb flow and surfactant time. But the photocurrent peak is blue-shifted at the surfactant time of . It seems to be due to the improvement of structure properties at interface owing to a surfactant-suppressing surface diffusion phenomenon during growth. We compared this with the result of the experimental energies for InGaAsN/GaAs-strained MQWs.