A new strategy to prepare temperature-sensitive poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide) microgels

In this study, a new method was developed to prepare temperature-sensitive poly(N-isopropylacrylamide) microgels by free radical precipitation polymerization using siloxane coupling agent as the new crosslinker. Ammonium persulfate acted as the initiator for the radical copolymerization as well as the catalyst for the hydrolysis/condensation of the siloxane groups. The particle diameter and polydispersity of the microgels were measured by photon correlation spectroscopy and the results display that the microgels are monodisperse. The microgels exhibit temperature sensitivity and the phase transition temperature is approximately 31 °C. Furthermore, the diameter of the microgels changes upon heating and cooling processes. These were observed to be reversible. The novel crosslinking method described herein is the condensation of siloxane groups, which is totally different from the traditional double-vinyl crosslinkers. This innovative approach offers an alternative path to prepare functional core–shell particles and inorganic/organic hybrid materials.     

A Modified Nonmonotone Hestenes–Stiefel Type Conjugate Gradient Methods for Large-Scale Unconstrained Problems

In this article, by slightly modifying the search direction of the nonmonotone Hestenes–Stiefel method, a variant Hestenes–Stiefel conjugate gradient method is proposed that satisfies the su?cient descent condition independent of any line search. This algorithm also possesses information about the gradient value and the function value. We establish the global convergence of our methods without the assumption that the steplength is bounded away from zero. Numerical results illustrate that our method can e?ciently solve the test problems, and therefore is promising.     

快速响应恢复的PI-SiO2/NiI2比色湿度传感器

有机-无机杂化型比色湿度传感器可通过电学信号和颜色变化获取环境湿度,并因其特征颜色区分度高、稳定性好、制备工艺简单等优点,在湿度监测领域具有广阔的应用前景,但其通常响应恢复时间长,从而不利于湿度实时监测.本文在聚酰亚胺(PI)-碘化镍(NiI₂)有机无机杂化材料中掺杂纳米SiO₂微球制备得到PI-SiO₂/NiI₂复合薄膜及比色湿度传感器,对其表面形貌和湿敏特性进行了研究.结果显示, PI-SiO₂/NiI₂薄膜具有蜂巢状的表面形貌,传感器的特征颜色显著,湿度响应时间小于1.5 s,恢复时间小于18 s.研究表明,纳米SiO₂微球掺杂能够较为显著地改善有机-无机杂化型比色湿度传感器的响应恢复特性,这对于传感器性能的提升具有一定参考意义.     

脉冲星信号的经验模态分解模态单元比例萎缩消噪算法

针对脉冲星信号的消噪问题, 提出了一种基于模态单元比例萎缩的经验模态分解(EMD)消噪方法. 利用经验模态分解将含噪脉冲星信号分解为一组内蕴模态函数(IMF), 将IMF中两个过零点间的部分定义为模态单元, 以模态单元为基本单位构造最优比例萎缩因子, 对IMF中的每个模态单元进行比例萎缩去噪, 进而建立基于模态单元比例萎缩的脉冲星信号滤波模型.对含噪脉冲星信号进行了消噪实验分析, 实验结果表明, 与小波硬阈值消噪法、比例萎缩小波消噪法和基于模态单元阈值的EMD消噪法相比, 该方法可以更有效地去除脉冲星信号中的噪声, 同时更好地保留了原信号中的有用细节信息. 关键词： 经验模态分解 脉冲星信号 模态单元比例萎缩 消噪     

In掺杂h-LuFeO3光吸收及极化性能的第一性原理计算

h-LuFeO3是一种窄带隙铁电半导体材料,已被证明在铁电光伏领域有较好的应用前景.然而,较低的极化强度使光生电子-空穴对复合率大,限制了h-LuFeO3基铁电光伏电池效率的提高.为改善h-LuFeO3的极化强度,提高光吸收性质,本文利用第一性原理计算方法研究了In原子在h-LuFeO3不同位置的掺杂形成能,得到最稳定...     

Synthesis,DNA binding and oxidative cleavage studies of an asymmetric tridentate copper(II) complex

An asymmetric tridentate Cu^II complex, [Cu(ptp)Cl₂] (ptp = 3-(1,10-phenanthrolin-2-yl)-as-triazino[5,6-f]-phenanthrene), has been synthesized and characterized by elemental analysis, FAB-MS, i.r. and u.v.–vis. spectra. The DNA binding behavior of the complex has been examined by fluorescence quenching, cyclic voltammetric and viscosity measurements. The results suggest that [Cu(ptp)Cl₂] binds to DNA in the intercalative mode. This complex is also found to produce cleavage of pBR 322 DNA in the presence of reducing agents such as ascorbate/H₂O₂, and the hydroxyl radical (OH^•) is suggested to be the reactive species responsible for the cleavage.     

锰(III)5,10,15-三(五氟苯基)-Corrole配合物的DFT计算

在6-31G*水平上采用DFT(UB3LYP)方法对锰(III)5,10,15-三(五氟苯基)-corrole [(TPFC)MnIII]及其咪唑轴向配位加合物(TPFC)MnIII(Im)进行了几何结构全优化. 计算结果表明, 咪唑的配位作用不会改变其基态的高自旋(s=2)特性. (TPFC)MnIII与咪唑配位形成轴向加合物后, 其中心金属Mn原子偏离平面结构, 与corrole大环N4平均平面的距离达到0.02734 nm. NBO分析显示(TPFC)MnIII和(TPFC)MnIII(Im)中心金属锰的电子组态为(dxz)1(dyz)1(dz2)1(dx2-y2)1(dxy)0. (TPFC)MnIII(Im)前线分子轨道能级明显上升, 从其β-(LUMO+3)轨道可见咪唑配位N原子的py轨道与中心金属Mn原子dyz轨道形成了d-pπ轨道. TD-DFT计算发现, (TPFC)MnIII和(TPFC)MnIII(Im)电子光谱Q带的“四轨”特征比B 带明显; (TPFC)MnIII的CT带主要源自β-(HOMO-1)→β-(LUMO+5)和β-HOMO→β-(LUMO+4)的跃迁, (TPFC)MnIII(Im)的CT带则主要源自β-(HOMO-1)→β-(LUMO+3)和β-HOMO→β-(LUMO+4)的跃迁.     

蚕沙叶绿素锌配合物对DNA的光断裂作用

利用从蚕沙中提取的叶绿素(CHL)制得了锌叶绿素(Zn-CHL)配合物.采用紫外-可见光谱、CD光谱和黏度法研究了Zn-CHL与小牛胸腺DNA(ct-DNA)的相互作用,并采用琼脂糖凝胶电泳研究了光照条件下Zn-CHL对pBR322 DNA的切割能力.结果表明,Zn-CHL与ct-DNA的作用方式属于外部结合模式,其结合常数为2.32×105L/mol,Zn-CHL在可见光照射下具有切割DNA的能力.     

Spatial anisotropy: a method to study anisotropic flow in heavy ion collisions

We introduce a method to study anisotropic flow parameter v_n as a collective probe to Quark Gluon Plasma in relativistic heavy ion collisions. The emphasis is put on the use of the Fourier expansion of initial spatial azimuthal distributions of participant nucleons in the overlapped region. The coefficients ε_n of Fourier expansion are called the spatial anisotropy parameter for the n-th harmonic. We propose that collective dynamics can be studied by v_n/ε_n. In this paper, we will discuss in particular the second (n=2) and the fourth (n=4) harmonics.     

Electronic structure and magnetic properties of （Mn,N）-codoped ZnO

The electronic structures and magnetic properties of（Mn, N）-codoped Zn O are investigated by using the firstprinciples calculations. In the ferromagnetic state, as N substitutes for the intermediate O atom of the nearest neighboring Mn ions, about 0.5 electron per Mn^2＋ion transfers to the N^2-ion, which leads to the high-state Mn ions（close to ＋2.5）and trivalent N3-ions. In an antiferromagnetic state, one electron transfers to the N2-ion from the downspin Mn2＋ion,while no electron transfer occurs for the upspin Mn^2＋ion. The（Mn, N）-codoped Zn O system shows ferromagnetism,which is attributed to the hybridization between Mn 3d and N 2p orbitals.