高居里温度铁电单晶PIN-PT的机电性能

弛豫铁电单晶Pb(In_1/2Nb_1/2)O₃-PbTiO₃(PIN-PT)相较于常用的Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃(PMN-PT)具有更高的居里温度,在高稳定性、高性能的传感器、换能器方面具有应用前景。本工作采用谐振法研究了[001]方向极化的0.66PIN-0.34PT铁电单晶的全矩阵机电性能参数。0.66PIN-0.34PT 单晶的三方-四方相变温度(T_RT)约为160 ℃,居里温度(T_C)约为260 ℃,室温压电系数d₃₃、d₃₁、d₁₅分别为1 340 pC/N、-780 pC/N、321 pC/N,介电常数ε^T₃₃、ε^S₃₃、ε^T₁₁、ε^S₁₁分别为2 700、905、2 210、1 927,机电耦合系数 k₃₃、k₃₁、k₁₅、k_t分别为 87%、58%、38%、61%。其纵向压电常数(d₃₃)和纵向机电耦合系数(k₃₃)小于 PMN-PT 单晶,但是横向压电性能(d₃₁)和剪切压电性能(d₁₅)都略高于PMN-PT单晶。另外,研究了机电耦合性能随温度的变化趋势,发现0.66PIN-0.34PT单晶在150 ℃以下有较好的温度稳定性。     

Syntheses,Crystal Structures and Fluorescence Properties of Three Complexes Based on 2,2'-Quinoline-4,4'-dicarboxylic Ligands

Crystallography Reports - Three new coordination complexes, [Mn(L)(H2O)4⋅(H2O)3]2 (1), [Mg(L)(H2O)4⋅(H2O)3]2 (2), and [Cu(L)(phen)⋅(H2O)4]2 (3) (H2L =...     

Spatiotemporal dynamics induced by nonlocal competition in a diffusive predator-prey system with habitat complexity

Nonlinear Dynamics - In this paper, we study a delayed diffusive predator–prey model with nonlocal competition in prey and habitat complexity. The local stability of coexisting equilibrium is...     

Dynamic thermo-mechanical coupled simulation of statistically inhomogeneous materials by statistical second-order two-scale method

In this paper,a statistical second-order twoscale(SSOTS) method is developed to simulate the dynamic thcrmo-mechanical performances of the statistically inhomogeneous materials.For this kind of composite material,the random distribution characteristics of particles,including the shape,size,orientation,spatial location,and volume fractions,are all considered.Firstly,the repre.sentation for the microscopic configuration of the statistically inhomogeneous materials is described.Secondly,the SSOTS formulation for the dynamic thermo-mechanical coupled problem is proposed in a constructive way,including the cell problems,effective thermal and mechanical parameters,homogenized problems,and the SSOTS formulas of the temperatures,displacements,heat flux densities and stresses.And then the algorithm procedure corresponding to the SSOTS method is brought forward.The numerical results obtained by using the SSOTS algorithm are compared with those by classical methods.In addition,the thermo-mechanical coupling effect is studied by comparing the results of coupled case with those of uncoupled case.It demonstrates that the coupling effect on the temperatures,heat flux densities,displacements,and stresses is very distinct.The results show that the SSOTS method is valid to predict the dynamic thermo-mechanical coupled performances of statistically inhomogeneous materials.     

Thermal Behavior Analysis of Two Synthesized Flavor Precursors of N‐alkylpyrrole Derivatives

To expand the library of pyrrole‐containing flavor precursors, two new flavor precursors—methyl N‐benzyl‐2‐methyl‐5‐formylpyrrole‐3‐carboxylate (NBMF) and methyl N‐butyl‐2‐methyl‐5‐formylpyrrole‐3‐carboxylate (NUMF)—were synthesized by cyclization, oxidation, and alkylation reactions. Thermogravimetry (TG), differential scanning calorimeter, and pyrolysis–gas chromatography/mass spectrometry were utilized to analyze the thermal degradation behavior and thermal degradation products of NBMF and NUMF. The TG‐DTG curve indicated that the maximum mass loss rates of NBMF and NUMF appear at 310 and 268°C, respectively. The largest peaks of NBMF and NUMF showed by the differential scanning calorimeter curve were 315 and 274°C, respectively. Pyrolysis–gas chromatography/mass spectrometry detected small molecule fragrance compounds appeared during thermal degradation, such as 2‐methylpyrrole, 1‐methylpyrrole‐2‐carboxylic acid methyl ester, limonene, and methyl formate. Finally, the thermal degradation mechanism of NBMF and NUMF was discussed, which provided a theoretical basis for their application in tobacco flavoring additives.     

Probing the Catalytic Promiscuity of a Regio‐ and Stereospecific C‐Glycosyltransferase from Mangifera indica

The catalytic promiscuity of the novel benzophenone C‐glycosyltransferase, MiCGT, which is involved in the biosynthesis of mangiferin from Mangifera indica, was explored. MiCGT exhibited a robust capability to regio‐ and stereospecific C‐glycosylation of 35 structurally diverse druglike scaffolds and simple phenolics with UDP‐glucose, and also formed O‐ and N‐glycosides. Moreover, MiCGT was able to generate C‐xylosides with UDP‐xylose. The OGT‐reversibility of MiCGT was also exploited to generate C‐glucosides with simple sugar donor. Three aryl‐C‐glycosides exhibited potent SGLT2 inhibitory activities with IC₅₀ values of 2.6×, 7.6×, and 7.6×10⁻⁷ M , respectively. These findings demonstrate for the first time the significant potential of an enzymatic approach to diversification through C‐glycosidation of bioactive natural and unnatural products in drug discovery.