Highly Selective and Responsive Visible to Near‐IR Ytterbium Emissive Probe for Monitoring Mercury(II)

A new lanthanide probe based on the fluorescence resonance energy transfer (FRET) process with the combination of ytterbium porphyrinate complex and a rhodamine B derivative unit was synthesized to detect the Hg²⁺ ion with responsive emission in the visible and near‐IR region with a detection limit of 10 μM     

Fe/Cr磁性多层膜的制备及其磁电阻测定

利用磁控溅射制备了不同非磁性层厚度的Fe/Cr多层磁性薄膜系统,利用四探针法测定了该多层膜系统在不同磁场下磁电阻效应,用饱和场法给予佐证,溅射制备的多层膜系统饱和场明显地随Cr层厚度增加而衰减振荡,得出了Fe/Cr多层膜的铁磁反铁磁耦合的交换耦合强度随非磁性层厚度变化的物理规律.     

High‐resolution separation of homogeneous chitooligomers series from 2‐mers to 7‐mers by ion‐exchange chromatography

Highly purified chitooligomers with single degree of polymerization are of significance for studying bioactivity of chitooligomers. However, there are few reports on high‐resolution preparative separation of chitooligomers, especially for those oligomers with degree of polymerization higher than 4. This study developed a high‐resolution chromatography for the preparative separation of a pure fully deacetylated chitooligomer series. A glucosamine oligomer mixture with low degree of polymerization was prepared by acid hydrolysis of a highly deacetylated chitosan. Then, six fractions were separated from the prepared oligomer mixture by ion‐exchange chromatography and analyzed by HPLC and ESI/MS, which primarily contained glucosamine dimers, trimers, tetramers, pentamers, hexamers, and heptamers, respectively, with chromatographic purities over 98% for dimers to hexamers and a purity of 93% for heptamers. The yields of a single round of separation were 75, 60, 60, 55, 35, and 20 mg for glucosamine dimers, trimers, tetramers, pentamers, hexamers, and heptamers, respectively. Furthermore, a chromatographic separation model for GlcN homomers was established. The capacity factor (k) of glucosamine oligomers and their degrees of polymerization (DPs) exhibited a good correlation, lnk = 0.786 + 0.846 lnDP, (R² = 0.997). Based on this equation, glucosamine octamers are expected to be separated by this system.     

江淮梅雨降水云顶光谱信息与降水强度关系研究

云顶的光学和微观物理特征是基于卫星光谱定量反演降水强度的关键信息.基于1998-2007年江淮梅雨期内热带测雨卫星的光谱和雷达融合观测资料,建立了基于降水云顶光谱信息反演降水强度的随机森林算法模型,进一步探究了梅雨降水云顶微物理特征与降水强度变化的关系.研究表明,在随机森林模型反演降水强度的测试集中,预测降水强度与观测降水强度的相关系数R为0.67,均方根误差为4.06 mm/h,测试集具有较高的降水预测精度.随机森林模型中的云水含量(CWP,即云水质量浓度)在所有输入的云微物理变量重要性排序中位于前列.进一步分析表明:当CWP小于1.0 kg·m-3时,江淮梅雨期降水主要以小雨等级为主,而当CWP大于1.5 kg·m-3时,大雨和暴雨等级的降水概率明显增大;降水的云粒子有效半径(CER)大小主要位于10 μm以上,且降水概率总体上随着CER的增大而单调递增;各等级降水概率随着云光学厚度(COT)的增大而不断增大,当COT大于120时,各级降水的概率显著增强,尤其是强降水.     

First-Principles Study of Structural,Elastic and Electronic Properties of OsSi

First-principles study of structural, elastic, and electronic properties of the B20 structure OsSi has been reported using the plane-wave pseudopotential density functional theory method. The calculated equilibrium lattice and elastic constants are in good agreement with the experimented data and other theoretical results. The dependence of the elastic constants, the aggregate elastic modulus, the deviation from the Cauchy relation, the elastic wave velocities in different directions and the elastic anisotropy on pressure have been obtained and discussed. This could be the first quantitative theoretical prediction of the elastic properties under high pressure of OsSi compound. Moreover, the electronic structure calculations show that OsSi is a degenerate semiconductor with the gap value of 0.68 eV, which is higher than the experimental value of 0.26 eV. The analysis of the PDOS reveals that hybridization between Os d and Sip states indicates a certain covalency of the Os-Si bonds.     

β-DDB及其衍生物的结构与红外光谱特征

总结归属了肉豆寇醚酸甲酯、6－Br肉豆寇醚酸甲酯、β-DDB（6,6′－二甲氧基－4,5,4′,5′－二次甲二氧基－2,2′－二甲氧羰基联苯）及其5种衍生物的主要红外吸收谱带和特征,讨论了其红外吸收频率随化合物结构变化的规律。 结果表明分子中酯基的改变主要对羰基的伸缩振动频率有较大的影响,而对苯环的骨架振动影响较小;当苯环上H原子被其他取代基取代时,羟基及苯环的骨架吸收均发生显著变化。     

Fe、Ni共掺杂ZnO薄膜的溶胶-凝胶法制备及性能研究

采用溶胶-凝胶法在玻璃基片上旋涂生长了ZnO、Fe, Ni单掺杂及(Fe,Ni)共掺杂ZnO薄膜.产物的显微照片及XRD图谱结果表明, 该方法所制备的ZnO薄膜表面均匀致密,都存在(002)择优取向,具有六角纤锌矿结构,晶粒尺寸平均在13 nm 左右,振动样品磁强计(VSM)测试结果显示掺杂ZnO薄膜均存在室温铁磁性.光致发光(PL)测量表明所有样品薄膜的PL谱主要由较强的紫外发光峰(394 nm)、蓝光峰(420 nm)、绿光峰(480 nm)组成.Fe、Ni单掺杂和共掺杂并不改变ZnO薄膜的发光峰位置,但掺杂后该紫外发光峰减弱,420 nm处的蓝光峰增强.     

Finite element analysis on stress-induced birefringence of polarization-maintaining optical fiber

Influence of thermal-mechanical properties on the features of the panda polarization-maintaining optical fiber (PMF) in fabrication process is studied in detail by finite element method (FEM). The stress birefringence is 2.13443×10-4 obtained by the static analysis and 2.1269×10-4 by dynamic analysis. The difference in simulation by two methods is around 0.4%. The non-uniformity of stress birefringence in the fiber core is about 1.6%. Predicted results demonstrate that effect of the thermal conductive parameter on fiber thermal stress dominates. The high and uniform stress birefringence in the fiber core is obtained by appropriately selecting suitable stress region area and position.     

A Monotonicity Result for the Range of a Perturbed Random Walk

We consider a discrete time simple symmetric random walk on \(\mathbb{Z }^d,\,d\ge 1,\) where the path of the walk is perturbed by inserting deterministic jumps. We show that for any time \(n\in \mathbb{N }\) and any deterministic jumps that we insert, the expected number of sites visited by the perturbed random walk up to time \(n\) is always larger than or equal to that for the unperturbed walk. This intriguing problem arises from the study of a particle among a Poisson system of moving traps with sub-diffusive trap motion. In particular, our result implies a variant of the Pascal principle, which asserts that among all deterministic trajectories the particle can follow, the constant trajectory maximizes the particle’s survival probability up to any time \(t>0.\)      

Donor and Ring-Fusing Engineering for Far-Red to Near-Infrared Triphenylpyrylium Fluorophores with Enhanced Fluorescence Performance for Sensing and Imaging

Fluorescent probes have become an indispensable tool in the detection and imaging of biological and disease-related analytes due to their sensitivity and technical simplicity. In particular, fluorescent probes with far-red to near-infrared (FR-NIR) emissions are very attractive for biomedical applications. However, many available FR-NIR fluorophores suffer from small Stokes shifts and sometimes low quantum yields, resulting in self-quenching and low contrast. In this work, we describe the rational design and engineering of FR-NIR 2,4,6-triphenylpyrylium-based fluorophores ( TPP-Fluors ) with the help of theoretical calculations. Our strategy is based on the appending of electron-donating substituents and fusing groups onto 2,4,6-triphenylpyrylium. In contrast to the parent TPP with short emission wavelength, weak quantum yields, and low chemical stability, the obtained novel TPP-Fluors display some favorable properties, such as long-wavelength emission, large Stokes shifts, moderate to high quantum yields, and chemical stability. TPP-Fluors demonstrate their biological value as mitochondria-specific labeling reagents due to their inherently positive nature. In addition, TPP-Fluors can also be applied to develop ratiometric fluorescent probes, as the electron-donating ability of the 2,6-phenyl substituents is closely correlated with their emission wavelength. A proof-of-concept ratiometric probe has been developed by derivatizing the amino groups of TPP-Fluor for the detection and imaging of nitroreductase in vitro and in hypoxic cells.