[en] This paper reports on the infrared optical absorption properties near and above the fundamental absorption edge of MBE grown undoped GaInAsSb quaternary semiconductor alloy deposited on GaSb and GaAs substrates measured and analyzed at room temperature by means of a Fourier Transform Infrared Spectrometer, and were found to be fully characterized by the interband transition theory and Urbach's rule. The optical band gap of MBE-GaInAsSb has been determined using a linear extrapolation of (αhν)² as a function of the photon energy hν, and the refractive index n deduced from the interference pattern, which shows good agreement with the theory of Sadao Adachi's

[en] The Particle Image Velocimetry (PIV) can capture velocity vector fields with high spatial resolution. In this study, the Dynamic PIV system up to 10kHz temporal resolution was developed with combining the High-speed camera and high speed Laser with Double pulse option. The 1024 x 1024 pixel images with frame straddling were captured in 2kHz. Also, PIV data were measured in 512 x 256 pixel in 10kHz. The system had been applied to capture the water droplet flow. The transient characteristics of the droplet flow can be clearly captured using the developed Dynamic PIV System

[en] A kind of novel photonic crystal fiber grating based on structural change was studied, the effective refractive index induced by structural change was computed using Multipole Method, the relationship between the effective refractive index and the shrinkage of air-holes was got. Moreover, the fabrication principle was proved in the mathematics way. A model of photonic crystal fiber grating based on structural change was built, the transmission characteristics were analysed with Coupled Mode Theory. The emphasis of this study was the impacts of the rings of air-holes in the cladding, the rings of air-holes shrinkage and the degree of air-holes shrinkage on the transmission characteristics. The research results indicate that the periodic air-holes shrinkage can form grating, not only the degree of air-holes shrinkage, but also the shrinkage envelope has important effect on the magnitude and the distribution of the effective refractive index; the resonance wavelength, the resonance bandwidth and the intensity have relations to the rings of air-holes in the cladding, the rings of air-holes shrinkage, and the degree of air-holes shrinkage.

[en] Extrahepatic cholangiocarcinoma (CCA) is a primary bile duct malignant tumour with poor prognosis. Familiarity with their varied imaging characteristics can be helpful in developing a correct diagnosis and in optimal treatment planning, and thus contribute to a better prognosis. The purpose of this article is to illustrate the typical appearances of extrahepatic CCA on magnetic resonance cholangiopancreatography (MRCP) and three-dimensional (3D) LAVA (liver acquisition with volume acceleration) sequences at 3 T magnetic resonance imaging (MRI), and to discuss the superiority of the two techniques in the diagnosis of CCA.

[en] Of the 52 known elemental superconductors among the 92 naturally occurring elements in the periodic table, fully 22 only become superconducting under sufficiently high pressure. In the rare-earth metals, the strong local magnetic moments originating from the 4f shell suppress superconductivity. For Eu, however, Johansson and Rosengren have suggested that sufficiently high pressures should promote one of its 4f electrons into the conduction band, changing Eu from a strongly magnetic (J=7/2) 4f⁷-state into a weak Van Vleck paramagnetic (J=0) 4f⁶-state, thus opening the door for superconductivity, as in Am (5f⁶). We report that Eu becomes superconducting above 1.8 K for pressures exceeding 80 GPa, T_c increasing linearly with pressure to 142 GPa at the rate +15 mK/GPa. Eu thus becomes the 53rd elemental superconductor in the periodic table. Synchrotron x-ray diffraction studies to 92 GPa at ambient temperature reveal four structural phase transitions.

[en] Purpose: The clinical management of meningioma is guided by its grade and biologic behavior. Currently, diagnosis of tumor grade follows surgical resection and histopathologic review. Reliable techniques for pre-operative determination of tumor behavior are needed. We investigated the association between imaging features extracted from preoperative gadolinium-enhanced T1-weighted MRI and meningioma grade. Methods: We retrospectively examined the pre-operative MRI for 139 patients with de novo WHO grade I (63%) and grade II (37%) meningiomas. We investigated the predictive power of ten semantic radiologic features as determined by a neuroradiologist, fifteen radiomic features, and tumor location. Conventional (volume and diameter) imaging features were added for comparison. AUC was computed for continuous and χ"2 for discrete variables. Classification was done using random forest. Performance was evaluated using cross validation (1000 iterations, 75% training and 25% validation). All p-values were adjusted for multiple testing. Results: Significant association was observed between meningioma grade and tumor location (p<0.001) and two semantic features including intra-tumoral heterogeneity (p<0.001) and overt hemorrhage (p=0.01). Conventional (AUC 0.61–0.67) and eleven radiomic (AUC 0.60–0.70) features were significant from random (p<0.05, Noether test). Median AUC values for classification of tumor grade were 0.57, 0.71, 0.72 and 0.77 respectively for conventional, radiomic, location, and semantic features after using random forest. By combining all imaging data (semantic, radiomic, and location), the median AUC was 0.81, which offers superior predicting power to that of conventional imaging descriptors for meningioma as well as radiomic features alone (p<0.05, permutation test). Conclusion: We demonstrate a strong association between radiologic features and meningioma grade. Pre-operative prediction of tumor behavior based on imaging features offers promise for guiding personalized medicine and improving patient management.

[en] Four-point electrical resistivity measurements were carried out on Nd metal and dilute magnetic alloys containing up to 1 at.% Nd in superconducting Y for temperatures 1.5–295 K under pressures to 210 GPa. The magnetic ordering temperature T_o of Nd appears to rise steeply under pressure, increasing ninefold to 180 K at 70 GPa before falling rapidly. Y(Nd) alloys display both a resistivity minimum and superconducting pair breaking ΔT_c as large as 38 K/at.% Nd. The present results give evidence that for pressures above 30–40 GPa, the exchange coupling J between Nd ions and conduction electrons becomes negative, thus activating Kondo physics in this highly correlated electron system. Furthermore, the rise and fall of T_o and ΔT_c with pressure can be accounted for in terms of an increase in the Kondo temperature.

[en] In order to study the vibrational and thermal dynamic properties of materials using the nuclear resonant inelastic X-ray scattering (NRIXS) and the hyperfine interactions and magnetic properties using the synchrotron Mössbauer spectroscopy (SMS) at simultaneously high pressure (multi-Mbar) and low temperature (T< 10 K), a new miniature panoramic diamond anvil cell (mini-pDAC) as well as a special gas membrane driven mechanism have been developed and implemented at 3ID, Advanced Photon Source. The gas membrane system allows in situ pressure tuning of the mini- pDAC at low temperature. The mini-pDAC fits into a specially designed compact liquid helium flow cryostat system to achieve low temperature, where liquid helium flows through the holder of the mini-pDAC to cool the sample more efficiently. The sample temperature as low as 9 K has been achieved. Through the membrane, the sample pressure as high as 1.4 Mbar has been generated from this mini-pDAC. The instrument has been routinely used at 3ID for NRIXS and SMS studies. In this paper, technical details of the mini-pDAC, membrane engaging mechanism and the cryostat system are described, and some experimental results are discussed.

[en] Of the 52 known elemental superconductors among the 92 naturally occurring elements in the periodic table, fully 22 only become superconducting under sufficiently high pressure. In the rare-earth metals, the strong local magnetic moments originating from the 4f shell suppress superconductivity. For Eu, however, Johansson and Rosengren have suggested that sufficiently high pressures should promote one of its 4f electrons into the conduction band, changing Eu from a strongly magnetic (J=7/2) 4f⁷-state into a weak Van Vleck paramagnetic (J=0) 4f⁶-state, thus opening the door for superconductivity, as in Am (5f⁶). We report that Eu becomes superconducting above 1.8 K for pressures exceeding 80 GPa, T_c increasing linearly with pressure to 142 GPa at the rate +15 mK/GPa. Eu thus becomes the 53rd elemental superconductor in the periodic table. Synchrotron x-ray diffraction studies to 92 GPa at ambient temperature reveal four structural phase transitions.

[en] Face centered cubic (fcc) FeHX was synthesized at pressures of 18-68 GPa and temperatures exceeding 1,500 K. Thermally quenched samples were evaluated using synchrotron X-ray diffraction (XRD) and nuclear resonant inelastic X-ray scattering (NRIXS) to determine sample composition and sound velocities to 82 GPa. To aid in the interpretation of nonideal (X≠1) stoichiometries, two equations of state for fcc FeH_X were developed, combining an empirical equation of state for iron with two distinct synthetic compression curves for interstitial hydrogen. Matching the density deficit of the Earth's core using these equations of state requires 0.8-1.1 wt % hydrogen at the core-mantle boundary and 0.2-0.3 wt % hydrogen at the interface of the inner and outer cores. Furthermore, a comparison of Preliminary Reference Earth Model (PREM) to a Birch's law extrapolation of our experimental results suggests that an iron alloy containing approximate to 0.8-1.3 wt % hydrogen could reproduce both the density and compressional velocity (V_P) of the Earth's outer core.