模式耦合理论在圆周对称长周期光纤光栅建模中的应用

长周期光纤光栅是不同于光纤Bragg光栅的一种光纤光栅器件 ,根据模式耦合理论 ,长周期光纤光栅表现为前向传播的纤芯导模和同向的各阶次包层模式之间的耦合。分析研究了长周期光纤光栅轴向的模场变化。忽略轴向的模式耦合以及包层模式之间的相互耦合作用 ,并认为折射率指数的调制只存在于纤芯中 ,建立了简化的长周期光纤光栅数学模型。对圆周对称轴向均匀型长周期光纤光栅谱特性进行了仿真 ,其结果与实验结果基本吻合 ,表明了简化的数学模型的合理性     

低密度稀土氧化物基气凝胶靶的研制

低密度的高原子序数元素氧化物气凝胶由于前驱体形成端基双键而易于收缩和开裂。通过调控配位环境结合无机分散溶胶凝胶法,制备了稀土氧化物气凝胶。氧化镧基气凝胶和氧化钇基气凝胶块体的成型性好,最低密度分别为0.05g·cm-3和0.06g·cm-3。其成分分别为六方相的La(OH)3和六方相的Y(OH)3,而聚丙烯酸中的羧基与稀土离子之间以桥接的方式进行配位。两种气凝胶均存在明显的多级结构,氧化镧基和氧化钇基气凝胶的初级粒子分别为纤维状和片/球混合形貌,而其二级粒子均为球形。两种气凝胶的比表面积分别为229.1m2·g-1和229.6m2·g-1。该方法制备的稀土氧化物气凝胶具有低的密度和纳米尺度的均匀性,在背光源中有潜在的应用。     

Structure and electrochemical performance of LiCoO2 cathode material in different voltage ranges

LiCoO₂ sample prepared by high-temperature solid state calcination shows a typical hexagonal structure with a single phase and fine particle size distribution. The high-voltage electrolyte with additive fluoroethylene carbonate (FEC) has been used. Electrochemical results show that the initial discharge capacities of the prepared LiCoO₂ cathode are 157.7, 169.5, 191.0, and 217.5 mAh g^?1 in the voltage ranges of 3.0–4.3, 3.0–4.4, 3.0–4.5, and 3.0–4.6 V, respectively. The capacity increases, while the initial coulombic efficiency and capacity retention decrease with increasing the charge cutoff voltage. The capacity retention is only 10.4 % after 200 cycles at 1C rate in the voltage range of 3.0–4.6 V. X-ray diffraction measurements confirm structural changes of the layered material in the different voltage ranges. A phase transition from the O3 to the H1-3 phase can be observed when LiCoO₂ is charged above 4.5 V. The AC impedance analysis indicates that the resistances (R _(sf+b), R _ct) of the prepared LiCoO₂ rapidly increase when the cell is charged to higher voltage. The amount of dissolved Co into the electrolyte also greatly increases with increasing the charge cutoff voltage.     

Kadison-Singer代数研究综述

回顾了建立KS-代数的研究背景,系统介绍了KS-代数的定义和性质以及超有限KS-代数、非超有限KS-代数、KS-格的构造和强KS-代数的研究结果,同时分析了KS-代数和经典的不变子空间、Kadison可迁代数、von Neumann代数生成元等问题之间的联系;讨论了非自伴代数的运算,给出了两种不同构造非自伴代数的运算法则;在此基础上,提出了未来学科发展有待研究的16个问题.     

广义KdV--BO方程的Cauchy问题的局部适定性的改进结果

In this paper we prove that the Cauchy problem associated with the generalized KdV-BO equation ut ＋ uxxx ＋ λH（uxx） ＋ u^2ux = 0, x ∈ R, t ≥ 0 is locally wellposed in Hr^s（R） for 4/3 〈r≤2, b〉1/r and s≥s（r）= 1/2- 1/2r. In particular, for r = 2, we reobtain the result in [3].     

Tumor‐Targeting W18O49 Nanoparticles for Dual‐Modality Imaging and Guided Heat‐Shock‐Response‐Inhibited Photothermal Therapy in Gastric Cancer

Photothermal therapy (PTT) is an emerging noninvasive and precise localized therapeutic modality; however, it is deeply limited by its poor tumor accumulation, inadequate photothermal conversion efficiency, and the thermoresistance of cancer cells. Aimed at these shortcomings, tumor‐targeting nanoparticles (iRGD‐W₁₈O₄₉‐17AAG) comprising carboxyl‐group‐functionalized W₁₈O₄₉ nanoparticles, integrin‐targeting peptide iRGD, and HSP90‐inhibitor 17AAG are developed. The W₁₈O₄₉ nanoparticles act as excellent PTT carriers and computed tomography (CT) imaging contrast agents. The ring type polypeptide iRGD promotes the accumulation of nanoparticles in the tumour and further penetration into cancer cells. The introduction of 17AAG can inhibit the heat‐shock response and overcome the thermoresistance, thus increasing the curative effect of PTT and reducing the chance of tumor recurrence. The W₁₈O₄₉ nanoparticles can also be used to monitor and guide the phototherapeutic through CT and near‐infrared fluorescence imaging after modification with Cy5.5. In addition, superior biosafety is also indicated in both preliminary in vitro and in vivo assessments. The potential of iRGD‐W₁₈O₄₉‐17AAG in tumor targeting, dual modality imaging‐guided and remarkable enhanced PTT of gastric cancer with ignorable side effect both in vitro and in vivo, which may be further applied in clinic, is highlighted.     

Influence of annealing temperature on the formation, microstructure and magnetic properties of spinel nanocrystalline cobalt ferrites

Nanocrystalline cobalt ferrites were synthesized by a simple, general, one-step sol–gel auto-combustion method. An interpretation based on the measurement of the adiabatic flame temperature and the amounts of gas evolved during reaction had been proposed for the nature of combustion. The influence of annealing temperatures on the magnetic properties was investigated. The microstructure was characterized by means of X-ray diffractometer (XRD) and transmission electron microscopy (TEM). It was found that the particle size and magnetic properties of the as-prepared ferrite samples showed strong dependence on the annealing temperature. The coercivity initially increased and then decreased with increasing annealing temperature whereas the particle size and saturation magnetization continuously increased.     

高阶非线性Schrdinger方程的自相似解

研究非线性项的形式为|u|~pu,p>0的2m阶非线性Schrdinger方程的自相似解.利用scaling和压缩映象原理证明了当初值满足一定条件时Cauchy问题解的整体存在性,据此给出了当初值的形式为U(x/(|x|))|x|~(-(2m)/p)时,自相似解的存在性.     

基于强混合数据的半参数平滑转换回归模型

本文基于严平稳强混合数据和带确定性趋势的强混合数据序列,推广了文献[20]中提出的半参数平滑转换回归模型。对含于平滑转换函数中的未知光滑有界函数应用级数估计方法,并基于非线性最小二乘估计和级数估计理论证明了模型参数估计量的相合性和渐近正态性等大样本性质,简要讨论了其协方差矩阵的估计以及假设检验问题。最后,应用该模型重新研究了我国年度通货膨胀率的平滑转换结构。     

Enhanced photoactivity of CdS nanorods by MXene and ZnSnO3: Application in photoelectrochemical biosensor for the effect of environmental pollutants on DNA hydroxymethylation in wheat tissues

The photoactivity of CdS nanorods was greatly improved by amino functionalized accordion-like MXene and spherical ZnSnO₃. MXene possesses good electron transfer capability and ZnSnO₃ presents matched energy band with CdS, which deeply accelerate the electron transfer and prevent the recombination of photogenerated electron-hole pair, leading to a strong photoelectrochemical (PEC) response. Taking the merit of the improved photoactivity of CdS nanorods, a novel PEC biosensor was constructed for DNA hydromethylation detection based on immune recognition of target molecule, where 5-hydroxymethyl-2′-deoxycytidine triphosphate (5hmdCTP) was employed as detect target, CdS/MXene was used as photoactive material, and ZnSnO₃ was adopted as signal amplification unit. Under enzymatic covalent reaction of –CH₂OH of 5hmdCTP with –NH₂ of MXene, 5hmdCTP was specifically recognized and captured. Then, taking advantages of the covalent reaction between phosphate group of 5hmdCTP and ZnSnO₃, the signal amplification unit was captured. Under the optimum conditions, this PEC biosensor presents wide linear range of 0.008–100 nM and low detection limit of 4.21 pM (3σ). The applicability of the developed method was evaluated by investigating the effect of Cd²⁺ and perfluorohexane compound pollutant on 5-hydroxymethylcytosine content in the genomic DNA of the roots and leaves of wheat seedlings.