硅碳烷树枝状液晶的研究

树技状化合物具有规整的结构，其分子体积、形状和功能基团可在分子水平上精确控制[1]，迄今国内只有综述报道[2]．传统的液晶分子为刚性棒状，按经典液晶理论，树枝状分子难以存在液晶态，迄今仅见3例多技聚合物显示热致或液致液晶性D－“．nercec［’咱称首次合成热致液晶树枝状聚合物TPD－bx，但据Ringsdorf［51分类，因其未采用逐步发散或收敛法，而用一锅煮法合成，产品结构不规整，分子量不单一．故仍属于多技聚合物．本文首次合成了液晶硅碳烷树技状化合物．1硅碳烷树技状化合物的结构树枝状化合物的结构见图1，主干为硅碳烷，含12…     

近晶C(Sc)相串型液晶高分子的合成与表征

以２，５ 二（对烷氧基苯甲酰氧基） 对苯二酚和不同结构的脂族二酰氯为单体，采用低温溶液缩聚的方法，合成了一系列新的液晶基元垂直于分子主链的Ｓｃ相串型液晶高分子．单体的结构通过元素分析、ＩＲ、１Ｈ ＮＭＲ和ＭＳ等方法确证．聚合物通过ＧＰＣ、ＤＳＣ、ＴＧ、ＷＡＸＤ和偏光显微镜等方法测试表征．研究发现，所有的聚合物加热至各自的熔点以上都能形成液晶态，在液晶态可以观察到纹影或焦锥织构．通过变温Ｘ 射线衍射证明它们为Ｓｃ相．所有聚合物的熔点（Ｔｍ）和液晶态的清亮点（Ｔ１）随分子中末端烷氧基增大和柔性间隔段长度增加逐渐降低，液晶态温度范围变窄．     

测量误差、不确定度与真理的相对性——实验教学的一个难点及课程思政

课程思政离不开具体的教学内容，思政观点必须与课程内容有较强的相关性；大学阶段的课程思政既要有较强的政治性，又要有较高的层次性。本文将真理的相对性(及相关原理、观点)融入误差与不确定度教学，在帮助学生深入学习理解不确定度概念及应用的同时，进一步熟悉和理解唯物辩证法相关原理和观点，引导他们坚定政治信仰，强化投身科学事业探索未知的信心和决心，并试图以此作为理工学科课程思政建设视角、思路和方法的一次实践探索，供同行诸贤参考。     

高亏格曲面上地图的计数

本文给出了可定向曲面(亏格2,3)和不可定向曲面(亏格5)上根瓣丛以边数为参数时相应的计数显式.与此同时,考虑一类与瓣从拓扑等价的地图类: (无环,简单)近2-正则地图,通过一种组合方法,给出了多参数下平面近2一正则地图的计数显式,亦得到了任意亏格曲面上该类地图的具体个数.     

Symmetry dependence of x—ray absorption near—edge structure at rhe metal K edge of 3d transition metal compounds

The pre-edge features in system with “even” symmetry,apart from quadrupolar tranition contribution,are mainly dipolar in character,associated with the existence of unoccupied states made up of mixed cation np with higher-neighboring cation-(n-l)d orbitals,and reflect the density of states due to the medium-range order of the system,while in “ood” symmetry materials these pre-edge features are the result of a transition from the 1s to final denisty of states of p symmetry due to an unsymmetrical mixing of the ligand wave functions with the central cation d orbitals.In the latter case,they contain not only the p but also the d base of orbitals,similar to a tetrahedral configuration.These results are validated for Fe as a photoabsorber by comparing x-ray absorption near-edge spectra of Fe2SiO4(fayalite) and Fe2O3(hematite) to ab initio full multiple scattering calculations at the Fe K edge,but pertain to all systems containing sixfold-coordinated cations.     

多参数高次扰动的平面近Hamilton系统的极限环个数

本文研究带参数高次扰动的平面近Hamilton系统Melnikov函数,利用一阶Melnikov函数来确定其在Hopf分支中极限环的个数.     

Investigation of sulfur speciation in particles from small coal-burning boiler by XANES spectroscop

Sulfur K-edge X-ray absorption near-edge structure （XANES） spectroscopy was employed to study the speciation of sulfur in raw coal, ash by-product and fine particulate matter from a small coal-burning boiler. By means of least square analysis of the XANES spectra, the major organic and inorganic sulfur forms were quantitatively determined. The results show that about 70% of the sulfur in raw coal is present as organic and a minor fraction of the sulfur occurs as other forms： 17% of pyrite and 13% of sulfate. While in bottom ash, fly ash, and PM2.5, the dominant form of sulfur is sulfate, with the percentage of 80,79 and 94, respectively. Moreover, a number of other reduced sulfur including thiophenic sulfur, element sulfur and pyrrhotite are also present. During coal combustion, most of organic sulfur and pyrite were oxidized and released into the atmosphere as SO2 gas, part of them was converted to sulfate existing in coal combustion by-products, and a small part of pyrite was probably reduced to elemental sulfur and pyrrhotite. The results may provide information for assessing the pollution caused by small boiler and developing new methods for the control of SO2 pollution.     

Luminescent Characteristics of LiSrBO3：Eu3＋ Phosphor for White Light Emitting Diode

LiSrBO3 ：Eu3＋ phosphor is synthesized by a high solid-state reaction method, and its luminescent characteristics are investigated. The emission and excitation spectra of LiSrBO3：Eu3＋ phosphors exhibit that the phosphors can be effectively excited by near ultraviolet （401 nm） and blue （471 nm） light, and emit 615nm red light. The effect of Eua＋ concentration on the emission spectrum of LiSrBO3：Eu3＋ phosphor is studied; the results show that the emission intensity increases with increasing Eu3＋ concentration, and then decreases because of concentration quenching. It reaches the maximum at 3mol%, and the concentration self-quenching mechanism is the dipoledipole interaction according to the Dexter theory. Under the conditions of charge compensation Li＋, Na＋ or K＋ incorporated in LiSrBO3, the luminescent intensities of LiSrBO3 ：Eua＋ phosphor are enhanced.