CoFe2O4 decorated graphene/C18-functionalized mesoporous silica nanocomposites prepared for magnetic enrichment and electrochemical detection of promethazine in beef

Promethazine(PHZ) is used as a sedative in veterinary medicine, and its residue can threaten the health of human. The electrochemical detection of PHZ is suitable method for application in the field. However,the traditional electroanalysis is difficult to perform directly in meat samples due to matrix interference. This work integrates magnetic solid-phase extraction and differential pulse voltammetry for highly sensitive and selective determination of PHZ in beef and beef liver for the first ti...     

High-strain InGaAs/GaAs quantum well grown by MOCVD

High-strain InGaAs/GaAs quantum wells （QWs） are grown by low-pressure metal-organic chemical vapor deposition （LP-MOCVD）. Photoluminescence （PL） at room temperature is applied for evaluation of the optical property. The influence of growth temperature, V/III ratio, and growth rate on PL characteristic are investigated. It is found that the growth temperature and V/III ratio have strong effects on the peak wavelength and PL intensity. The full-width at half-maximum （FWHM） of PL peak increases with higher growth rate of InGaAs layer. The FWHM of the PL peak located at 1039 nm is 20.1 meV, which grows at 600 ℃ with V/ III ratio of 42.7 and growth rate of 0.96 μm/h.     

Tunable spectral shift of high-order harmonic generation in atoms using a sinusoidally phase-modulated pulse

High-order harmonic generation (HHG) from an atom illuminated by a sinusoidally phase-modulated pulse is investigated by solving the time-dependent Schrödinger equation. The spectral shift that occurs in atomic HHG can be achieved easily using our laser pulse. It is shown that the photon energy of the generated harmonics is controllable within the range of 1 eV. The shift of the frequency peak position is rooted in the asymmetry of the rising and falling parts of the laser pulse. We also show that by varying the phase parameters in the frequency domain of the laser one can adjust and control the shift in atomic harmonic spectra.     

First-principles study of stability of point defects and their effects on electronic properties of GaAs/AlGaAs superlattice

When the GaAs/AlGaAs superlattice-based devices are used under irradiation environments, point defects may be created and ultimately deteriorate their electronic and transport properties. Thus, understanding the properties of point defects like vacancies and interstitials is essential for the successful application of semiconductor materials. In the present study, first-principles calculations are carried out to explore the stability of point defects in GaAs/Al_0.5Ga_0.5As superlattice and their effects on electronic properties. The results show that the interstitial defects and Frenkel pair defects are relatively difficult to form, while the antisite defects are favorably created generally. Besides, the existence of point defects generally modifies the electronic structure of GaAs/Al_0.5Ga_0.5As superlattice significantly, and most of the defective SL structures possess metallic characteristics. Considering the stability of point defects and carrier mobility of defective states, we propose an effective strategy that Al_As, Ga_As, and Al_Ga antisite defects are introduced to improve the hole or electron mobility of GaAs/Al_0.5Ga_0.5As superlattice. The obtained results will contribute to the understanding of the radiation damage effects of the GaAs/AlGaAs superlattice, and provide a guidance for designing highly stable and durable semiconductor superlattice-based electronics and optoelectronics for extreme environment applications.     

Microwave absorption properties regulation and bandwidth formula of oriented Y2Fe17N3-δ@SiO2/PU composite synthesized by reduction-diffusion method

As concepts closely related to microwave absorption properties, impedance matching and phase matching were rarely combined with material parameters to regulate properties and explore related mechanisms. In this work, reduction-diffusion method was innovatively applied to synthesize rare earth alloy Y$_{2}$Fe$_{17}$. In order to regulate the electromagnetic parameters of absorbers, the Y$_{2}$Fe$_{17}$N$_{3-\delta }$ particles were coated with silica (Y$_{2}$Fe$_{17}$N$_{3-\delta }$@SiO$_{2}$) and absorbers with different volume fractions were prepared. The relationship between impedance matching, matching thickness, and the strongest reflection loss peak (${\rm RL}_{\rm min}$) was presented obviously. Compared to the microwave absorption properties of Y$_{2}$Fe$_{17}$N$_{3-\delta }$/PU absorber, Y$_{2}$Fe$_{17}$N$_{3-\delta }$@SiO$_{2}$/PU absorbers are more conducive to the realization of microwave absorption material standards which are thin thickness, light weight, strong absorbing intensity, and broad bandwidth. Based on microwave frequency bands, the microwave absorption properties of the absorbers were analyzed and the related parameters were listed. As an important parameter related to perfect matching, reflection factor ($\sqrt {ărepsilon_{\rm r}/\mu_{\rm r}}$) was discussed combined with microwave amplitude attenuation. According to the origin and mathematical model of bandwidth, the formula of EAB (${\rm RL}<-10$ dB) was derived and simplified. The calculated bandwidths agreed well with experimental results.     

A new anti-diabetic sesquiterpenoid from Acorus calamus

A new sesquiterpenoid,1β,5α-guaiane-4β,10α-diol-6-one(1),was isolated from 70%EtOH extract of the rhizomes of Acorus calamus.The structure was determined on spectroscopic methods,especially 2D NMR techniques.The absolute configuration of 1 was confirmed by TDDFT quantum chemical calculation of its ECD spectrum.Compound 1 showed promising anti-diabetic activity on a insulin-mediated glucose consumption model of HepG2 cells.     

Preparation,structural characterization of a novel egg-shell palladium sulfide catalyst and its application in selective reductive alkylation reaction

A novel egg-shell Pd-S catalyst with palladium metal as the core and a membrane of palladium sulfide as the surface has been prepared by sulphidizing Pd/C with H₂S.This catalyst is effective for the reductive alkylation of p-amino diphenylamine（PADPA） and methylisobutyl ketone（MIBK） to afford N-（1,3-dimethylbutyl）-N′-phenyl-p-phenylenedianine（DBPPD） with conversion up to 99.42%and selectivity to 97.46%.Comparing with the other common palladium sulfide catalysts,the membrane of palladium sulfide on the surface and the core of palladium metal cause the Pd on the surface of the new catalyst in a lower sulfur coordination, which improves its activity.Our result indicates that this new egg-shell Pd-S/C is an efficient hydrogenation catalyst.     

Preparation of acid-resistant magnetic adsorbent for effective removal of p-nitrophenol

Bilayer-silane-coated Fe₃O₄ nanoparticles with inner layer of tetraethoxy silane（TEOS） and outer layer of vinyltriethoxysilane （VTEO） were generated to enhance their acid resistance.These nanoparticles were copolymerized with vinylbenzyl chloride（VBC） using suspension polymerization,and then post-crosslinked.The resulting hypercrosslinked magnetic resin M150 presented specific bimodal property with large specific surface area of 1109 m²/g.It exhibited more excellent adsorption capacity of p-nitrophenol compared to another two magnetic adsorbents Ql 50 and MIEX^.Moreover,the acid stable property of the magnetite in M150 extended its application at low pH value.     

Oxidation of alcohols to aldehydes and ketones using selenium ionic liquid

A new type of ionic liquid supported selenium reagents were synthesized and found to be an excellent catalyst in the oxidation of alcohols to aldehydes and ketones in the presence of 30%H₂O₂.The predictable solubility of ionic liquids allows an easy separation of the oxidation products from the reaction mixture.Furthermore,the oxidation reaction can be carried out using an ionic liquid as the solvent,and the ionic liquid-supported selenium reagents can be recycled and used for four times with a little decrease in catalytic performance.     

Nb2O5 as a new electron transport layer for double junction polymer solar cells

Nb(2)O(5) as a new electron transport layer (ETL) was used for double junction polymer solar cells. The Nb(2)O(5) ETL was prepared by spin coating a Nb(2)O(5) sol-gel solution onto the active layer of the optical front subcell. The double junction devices using Nb(2)O(5) ETL exhibit an open circuit voltage (V(oc)) of 1.30 V, which is close to the sum of the s of the individual subcells. The current density-voltage (J-V) simulation showed that the double junction device performance using Nb(2)O(5) as ETL could be significantly increased by reducing the series resistance (R(se)) and matching the current densities of the individual subcells.