Synthesis,X-Ray Crystal Structures and Optical Properties of Novel Substituted Pyrazoly 1,3,4-Oxadiazole Derivatives

Novel pyrazoly 1,3,4-oxadiazole derivatives were synthesized and characterized by ¹H NMR, IR, HRMS and X-ray diffraction analysis. UV–vis absorption and fluorescence properties of these compounds in different solutions showed that the maximum absorption wavelength was not significantly changed in different solvents; however, maximal emission wavelength was red-shifted with the increase of solvent polarity. Absorption λ_max and emission λ_max was less correlated with substituent groups on aryl rings.     

一类偶数阶中立型非线性阻尼泛函微分方程的振动准则

本文用不同于原有文献的方法研究了一类偶数阶中立型非线性微分方程的振动性,得到了方程振动的几个新的充分条件。     

Colored Noise Induced Net Voltage of the Underdamped Josephson Junction

The underdamped Josephson junction subjected to correlated colored noises was investigated. The results indicated that: (i) There are two critical phenomena in the system; (ii) Net voltage of the system is induced by multiplicative noise, and exhibits non-monotonic behaviors with noise autocorrelation rate and the Josephson junction capacitance.     

Optical entangled fractional Fourier transform derived via non-unitary SU(2) bosonic operator realization and its convolution theorem

Based on the two mutually conjugate tripartite entangled state representations (TESR), we introduce the 3-mode optical entangled fractional Fourier transform (EFrFT) through a new non-unitary bosonic operator realization of the SU(2) generators and the tripartite squeezing operator. The EFrFT, which is characteristic of the eigenmodes being three-variable Hermite polynomials, is not the direct product of three single-variable FrFTs. We show that the EFrFT adapts to the transform between two mutually conjugate quantum mechanical TESR, i.e., we can recast the EFrFT into the matrix element of in the TESR. In addition, we define the two functions' convolution in the EFrFT scheme and obtain the convolution theorem using the TESR. The derivation is concise and rigorous because our calculation is based on Dirac's powerful representation theory.     

Integration of miniature Fabry-Perot fiber optic sensor with FBG for the measurement of temperature and strain

A sensor has been fabricated by the integration of a fiber Bragg gating sensor (FBGs) with a fiber Fabry-Perot (F-P) sensor fabricated by etching method. In the integrated sensor, the FBG was used to measure temperature, while the fiber Fabry-Perot interferometer sensor (FFPIs) was used for strain measurement. Wavelength decoding for FBG and peak tracking for FFPI was employed for demodulation, respectively. The result showed that the temperature and strain sensitivity for the integrated sensor is ~ 2.7 pm/μεand ~ 9.3 pm/°C, respectively.     

Photoelectrochemical switch based on cis-Azobenzene chromophore modified TiO2 nanowires

Carboxylated-azobenzene chromophore modified TiO₂ nanowire composites were prepared and characterized. Photocurrent measured with monochromatic incident light irradiation results showed that azobenzene modified TiO₂ nanowire electrode had obviously higher photocurrent and broader visible light response covering range of 350-650 nm, and the wavelength position corresponding to the maximum photocurrent was red shift to about 470 nm. After alternate irradiation with UV and visible light, the azobenzene modified TiO₂ nanowire electrode exhibited obvious photoelectrochemical switching properties. Furthermore, the photocurrent under visible light irradiation was much higher than that under UV irradiation due to the cis-to-trans isomerization transformation of azobenzene chromophore.     

Substitutional alloy of Bi and Te at high pressure

Being a best known thermoelectric material and a topological insulator at ambient condition, magic bismuth telluride (Bi2Te3) under pressure transforms into several superconducting phases, whose structures remain unsolved for decades. Here, we have solved the two long-puzzling low high-pressure phases as seven- and eightfold monoclinic structures, respectively, through particle-swarm optimization technique on crystal structure prediction. Above 14.4 GPa, we experimentally discovered that Bi2Te3 unexpectedly develops into a Bi-Te substitutional alloy by adopting a body-centered cubic disordered structure stable at least up to 52.1 GPa. The continuously monoclinic distortion leads to the ultimate formation of the Bi-Te alloy, which is attributed to the Bi→Te charge transfer under pressure. Our research provides a route to find alloys made of nonmetallic elements for a variety of applications.     

Effect of well thickness on the Rashba spin splitting and intersubband spin-orbit coupling in AlGaN/GaN/AlGaN quantum wells with two subbands

By projecting the characteristic equation into the subspace of the conduction band, the Rashba spin splitting coefficient for the first two subbands (α₁, α₂) and the intersubband spin-orbit coupling coefficient (η₁₂) in AlGaN/GaN quantum well structure are obtained. Then sizable α₁, α₂ and η₁₂ in QWs are calculated by solving the Schrödinger and Poisson equations self-consistently. We find that the internal electric field is crucial for considerable spin-orbit coupling effect in III-nitride QWs and the spin-orbit coupling coefficient can be greatly modulated by the well thickness. Compared with the Rashba coefficient, the intersubband spin-orbit coupling coefficient is basically of the same order of magnitude. The results show the great possibility of spin manipulation in low-dimensional semiconductors, and III-nitride QWs are candidates for the design of spintronic devices.     

Diode-pumped efficient continuous-wave Yb:Y3Ga5O12 laser at 1035 nm

An efficient diode-pumped Yb:Y3Ga5O12 (Yb:YGG) laser was demonstrated by using a high-quality Yb:YGG crystal grown by the optical floating zone method. Continuous-wave laser power up to 2.65?W had been obtained under an incident pump power of 6.71?W at 970?nm, corresponding to an optical-to-optical efficiency of 39.5% and maximum slope efficiency of 84.5%. A modeling calculation of the Yb:YGG laser was also performed, and the theoretical results were consistent with the experimental results.     

Diastereoselectively switchable enantioselective trapping of carbamate ammonium ylides with imines

The diastereoselectively switchable enantioselective trapping of protic carbamate ammonium ylides with imines is reported. The intriguing Rh(2)(OAc)(4) and chiral Br?nsted acid cocatalyzed three-component Mannich-type reaction of a diazo compound, a carbamate, and an imine provides rapid and efficient access to both syn- and anti-α-substituted α,β-diamino acid derivatives with a high level control of chemo-, diastereo-, and enantioselectivity.