High-pressure Raman study of MgV2O6 synthesized at high pressure and high temperature

A new structural phase of MgV2O6 was obtained by a high-pressure,high-temperature(HPHT) synthesis method.The new phase was investigated by the Rietveld analysis of X-ray powder diffraction data,showing space group Pbcn(No.60) symmetry and a = 13.6113(6) (1 = 0.1 nm),b = 5.5809(1) ,c = 4.8566(3) ,V = 368.93(2) 3(Z = 4).High pressure behavior was studied by Raman spectroscopy at room temperature.Under 22.5 GPa,there was no sign of a structural phase transition in the spectra,demonstrating stability of the HPHT phase up to the highest pressure.     

表面预处理对镁铝水滑石结构性质和缓释性能影响

以Mg-Al-NO₃水滑石（LDHs）为载体,将5-氟尿嘧啶（5-FU）通过离子交换法插入其层间,得5-FU/LDHs缓释材料。并对水滑石表面进行弱酸预处理改性,利用XRD、FTIR、TG-DSC、SEM和零电荷点（pHPZC）等表征手段,考察酸预处理对水滑石表面化学性质及微观结构的影响。结果表明,5-FU/LDHs的层间距从0.858nm扩大到1.064nm,层间5-FU₂阴离子与主体层板通过氢键与静电作用,以呈一定角度单层交替排列于层间。酸预处理的水滑石粒径变小,层板正电荷密度增大。5-FU的释放机理是物理扩散、离子交换和药物溶解等协同作用,酸预处理可提高水滑石的缓释性能和稳定性。     

正铁氧体SmFeO_3高压拉曼研究(英文)

本文主要通过高压拉曼光谱研究了正铁氧体SmFeO3的晶格振动模式在外加压力作用下的行为规律,高压实验中压力最高为29.7GPa。本文采用溶胶凝胶法,制备出具有正交结构,其空间群为Pnma的SmFeO3。在外加压力作用下,所有观察到的拉曼振动模式都呈现出宽化趋势。特别是位于621.1cm-1的FeO6八面体的反弹性振动模式Ag(1)与位于452.7cm-1的FeO6八面体的弯曲振动模式B3g(3),其压力系数出现最大值。与此相反,Sm-O振动模式Ag(7)的压力系数却非常小。这说明外加压力更容易影响到FeO6八面体的晶格变化,而不是SmO12十七面体的改变。SmFeO3的这种高压下晶格振动模式变化行为类似于G型结构的CaSnO3。同时,文中还给出了所有声子零压模式下的格林爱森参数与体弹模量的比值。这些参数可用于进一步测量单轴或者双轴的应变力,可深入理解声子频率在张力作用下移动的表现行为。     

猫眼效应中离焦量对激光回波发散角的影响

平行光束或者激光束在光轴方向上照射焦平面成像系统时会产生猫眼效应,焦平面探测器安装的正交性与离焦量直接影响猫眼回波的光学特性,进而影响基于猫眼效应的探测系统的性能。针对猫眼效应中离焦量与后向反射光束发散角之间关系,利用物理光学进行分析,建立理论模型,对焦距为0.18 m的焦平面探测成像系统进行数值计算得到:在离焦量为0.16 mm时,发散角最小（0.019 mrad）。搭建实验系统,测试离焦量与猫眼回波发散角,测得离焦量在0.15 mm附近存在最小的发散角为0.025 mrad,与计算结果0.019 mrad基本吻合。研究表明:1） 负离焦对发散角的影响大于正离焦;2） 猫眼回波发散角基本上随着离焦量绝对值的增加而变大,但是变化曲线并不关于零离焦量点对称,而是在某个正离焦处存在一个最小发散角。     

Ultra-lightweight and wide field of view augmented reality virtual retina display based on optical fiber projector and volume holographic lens

A novel see-through virtual retina display(VRD) system is proposed in this Letter. An optical fiber projector is used as the thin-light-beam source, which is modified from a laser scan projector by separating the laser sources and the scan mechanical structure. A synthetic aperture method is proposed for simple, low-cost fabrication of a volume holographic lens with large numerical aperture. These two key performance-enhanced elements are integrated into a lightweight and ordinary-glasses-like optical see-through VRD system. The proposed VRD system achieves a weight of 30g and a diagonal field of view of 60°.     

高效抗菌Cu2+-壳聚糖季铵盐/丙烯酸复合物的制备

以过硫酸铵为引发剂,在壳聚糖季铵盐（HACC）上接枝丙烯酸（AAc）并络合Cu²⁺,制备了具有高效抗菌性能的HACC-g-PAAc-Cu²⁺复合物.采用红外光谱（FTIR）和核磁共振波谱（¹H NMR）表征了壳聚糖季铵盐接枝改性前后的化学结构变化;利用紫外-可见吸收光谱（UV-Vis）、Cu²⁺选择电极和热失重分析（TGA）表征了壳聚糖季铵盐接枝前后负载Cu²⁺的能力;测定了HACC-Cu²⁺和HACC-g-PAAc-Cu²⁺对金黄色葡萄球菌及大肠杆菌的最小抑菌浓度,并对小鼠经口摄入毒性和兔皮肤敷涂刺激性进行了考察.研究结果表明,在壳聚糖季铵盐上负载Cu²⁺能够有效提高其抗菌性;接枝丙烯酸能提高HACC负载Cu²⁺的能力和抗菌性,Cu/HACC结构单元的摩尔比由接枝前的3：7提高到接枝后的1：1;对金黄色葡萄球菌的最小抑菌浓度由60 mg/L下降到9.2 mg/L,对大肠杆菌的最小抑菌浓度由37 mg/L下降到6.3 mg/L,无摄入毒性和皮肤刺激性.     

In-situ high-pressure behaviors of double-perovskite Sr_2ZnTeO_6

Structural and spectroscopic properties of Sr 2 ZnTeO 6 (SZTO) were investigated by angle-dispersive synchrotron X-ray powder diffraction and Raman spectroscopy in a diamond anvil cell up to 31 GPa at room temperature. Although SZTO remained stable up to the highest pressure, the different pressure coefficients of the normalized axial compressibility were obtained as βab =8.16×10-3 GPa-1 and βc =7.61×10-3 GPa-1 . The bulk modulus B0 was determined to be 190(1) GPa by fitting the pressure-volume data using the Birch-Murnaghan equation of state. All the observed Raman modes exhibited a broadening effect under high pressure. The vibrational band υ1 around 765 cm-1 , which is associated with the Te-O stretching mode in the basal plane of the TeO6 octahedron had the largest pressure coefficient, and the Grüneisen parameters for all the observed phonon modes were also calculated and presented. These parameters could be used to measure the amount of uniaxial or biaxial strain, providing a fundamental tool for monitoring the magnitude of the shift of phonon frequencies with strains.     

Doping effects on structural and magnetic evolutions of orthoferrite SmFe（1-x） Alx O3

The structural and magnetic properties of SmFeO3 with B site substitution of non-magnetic atom A1 are investigated. The x-ray diffraction patterns show that SmFe（1-x）AlxO3 remains an orthorhombic structure within the whole doping range, and the unit-cell volume decreases monotonically with the increase of doped A1 concentration. Besides, the octa- hedral tilting distortions of FeO6 are found to be alleviated while the tolerance factor increases. However, the relationship between the lattice parameters and Al concentration is observed to deviate from Vegard＇s rule, and this may be caused by magnetostriction effects. For the doping content values in a range 0 〈 x 〈 0.6, the ferromagnetism, antiferromagnetism, and paramagnetism are observed to occur continuously. Moreover, the magnetization and the spin reorientation temperature （Tk） decrease monotonically as Al content value increases. With the doping content values being x = 0.8 and 1.0, these compounds only show paramagnetic behavior.     

元素分析仪-同位素比质谱仪系统CN模式的日常维护及使用

介绍了元素分析仪-同位素比质谱仪（EA-IRMS）系统CN模式的组成、功能及工作原理,总结了日常维护、常规操作步骤,以期为相关人员提供参考。