PLASMA POLYMERIZATION OF HEXAMETHYLCYCLOTRISILOXANE

In a capacitively coupled RF discharge system with external electrodes ,hexamethyicyclotrisiloxane was polymerized, and the effects of discharge power and plasma gas on polymer deposition rate were studied. The polymer structures and properties were studied by IR spectroscopy, XPS measurement, PGC/MS combined technique, TG analysis and contact angle measuring. The results showed that the polymers prepared in H_2 or O_2 have higher C/Si ratio in comparison with those prepared in inert gases. PGC/MS results revealed the existence of many short carbon chains in the polymer structure .TG analysis suggested that the polymers prepared in the inert gas would possess better thermal stabilities.     

UV Photoionization Study of the Ethyl Radical

Introduction Ashighlyreactivebuildingblocksandfundamen talreactionintermediatesinorganicsynthesis,thealkyl radicalfamilyplaysacentralroleinadiversearrayof importantprocessesrangingfromcombustion[1]toat mosphericchemistry[2].Amongalkylradicals,theeth ylrad…     

(Z)-1[2-(苯基二溴化锡基)乙烯基]-1-环己醇的合成及晶体结构

报道了标题化合物〔C14H18Br2OSn〕的合成及晶体结构。该晶体属于单斜晶系，空间点群为P21/c，晶胞参数a=11.711(2)，b=9．114（2），c=16．864（3）A，β=102.94（1）°，V=1604.55（0）A3，Mr=480．78，Z=4，Dc=1．99g／cm3，u=65．20cm－1，F（000）=919，R=0．050，Rw=0．050．晶体结构由直接法解出。标题化合物分子中的锡原子被配体的2个碳、2个溴和1个氧原子配位，配位原子呈畸变的三角双锥构型，环已基为椅式构象，五员杂环为信封构象。     

Global existence and uniqueness to the Cauchy problem of the BGK equation with infinite energy

The Bhatnagar–Gross–Krook model of the Boltzmann equation is of great importance in the kinetic theory of rarefied gases. Various existence and uniqueness results have been built under the boundedness of energy. In this paper, we will establish several global existence results to the Bhatnagar–Gross–Krook equation with infinite energy. It heavily relies on a new moments lemma and a new existence and uniqueness theorem of weighted velocity‐spatial L^∞ solutions. Copyright © 2015 John Wiley & Sons, Ltd.     

基于改进卡尔曼滤波的水声通信盲自适应多用户检测算法

针对水声通信网络中遇到的多用户检测中目标用户的多址干扰等检测问题,提出了基于改进Kalman算法的盲自适应多用户检测算法,解决了多用户检测中的多址干扰对水声通信信道用户变动时的干扰抑制问题。仿真分析分别针对同步多用户、异步多用户通信过程,对比了传统Kalman算法及改进的Kalman算法的性能差异,通过仿真对比表明,改进后的Kalman检算法不需要训练序列即可以实现同步和异步通信状态下的多水声目标用户的盲自适应检测,改进后的算法目标检测的信干比比传统算法最大可提高6dB。新算法对于水下多用户检测、区分,准确、稳定的实现基于CDMA协议的快速水声通信具有重要意义。     

考查化学学科核心素养的实验题命制——制备氯酸钾和次氯酸钠并探究其氧化能力

整合课程标准和高考评价体系提出考查化学学科核心素养的试题命题流程。以“制备KClO₃和NaClO并探究其氧化能力的实验题”命制为例,针对考试类别与水平确定核心素养测试目标,以2020年全国Ⅲ卷第26题实验题为激发点遴选真实情境,查阅文献资料,基于条件控制初步命制实验探究题。针对初稿中的知识覆盖面不够、能力进阶不够等问题,二次查阅文献,深度挖掘素材创新点,形成试题,并从考查情境、考查内容、考查要求等3个方面对试题进行全面解构,得出命题过程应关注真实情境的科学性、适宜性、包容性;文献资料的权威性、互证性、多元性;必备知识分布的合理性及关键能力考查的层次性。     

Boosting the Activity of Pd Single Atoms by Tuning Their Local Environment on Ceria for Methane Combustion

Supported Pd single atom catalysts (SACs) have triggered great research interest in methane combustion yet with contradicting views on their activity and stability. Here, we show that the Pd SAs can take different electronic structure and atomic geometry on ceria support, resulting in different catalytic properties. By a simple thermal pretreatment to ceria prior to Pd deposition, a unique anchoring site is created. The Pd SA, taking this site, can be activated to Pd^δ+ (0<δ<2) that has greatly enhanced activity for methane oxidation: T₅₀ lowered by up to 130 °C and almost 10 times higher turnover frequency compared to the untreated catalyst. The enhanced activity of Pd^δ+ site is related to its oxygen-deficient local structure and elongated interacting distance with ceria, leading to enhanced capability in delivering reactive oxygen species and decomposing reaction intermediates. This work provides insights into designing highly efficient Pd SACs for oxidation reactions.     

Engineering a Self-Grown TiO2/Ti-MOF Heterojunction with Selectively Anchored High-Density Pt Single-Atomic Cocatalysts for Efficient Visible-Light-Driven Hydrogen Evolution

A photocatalyst TiO₂/Ti-BPDC-Pt is developed with a self-grown TiO₂/Ti-metal–organic framework (MOF) heterojunction, i.e., TiO₂/Ti-BPDC, and selectively anchored high-density Pt single-atomic cocatalysts on Ti-BPDC for photocatalytic hydrogen evolution. This intimate heterojunction, growing from the surface pyrolytic reconstruction of Ti-BPDC, works in a direct Z-scheme, efficiently separating electrons and holes. Pt is selectively anchored on Ti-BPDC by ligands and is found in the form of single atoms with loading up to 1.8 wt %. The selective location of Pt is the electron-enriched domain of the heterojunction, which further enhances the utilization of the separated electrons. This tailored TiO₂/Ti-BPDC-Pt shows a significantly enhanced activity of 12.4 mmol g⁻¹ h⁻¹ compared to other TiO₂- or MOF-based catalysts. The structure-activity relationship further proves the balance of two simultaneously exposed domains of heterojunctions is critical to fulfilling this kind of catalyst.     

聚合过程中原位生成助稳定剂的细乳液聚合

以甲基丙烯酸十二氟庚酯(DFMA)、甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)为共聚单体,不加任何传统的助稳定剂进行细乳液聚合.在共聚体系中,由于DFMA在初期反应生成的聚合物中占有较高比例,初期形成的少量低聚物可以起到助稳定剂作用,因此DFMA作为反应单体的同时,又可以原位生成助稳定剂,维持单体液滴或乳胶粒子的稳定,以细乳液聚合的方式进行聚合.分别采用油溶性引发剂(AIBN)和水溶性引发剂(KPS)引发聚合,考察细乳液聚合过程中乳胶粒子粒径的变化规律,粒径由初始时刻的400nm左右减少到80nm左右,最终与使用传统的助稳定剂得到的粒径相当.提出了原位生成助稳定剂的细乳液聚合机理,并使用交联剂验证了提出的原位生成助稳定剂的细乳液聚合机理.     

二乙基锌的同步辐射真空紫外光电离光解离

利用同步辐射光源和反射式飞行时间质谱, 在超声冷却条件下对二乙基锌(ZnC4H10)进行真空紫外(VUV, 能量范围为8-22 eV)光电离光解离研究. 实验获得ZnC4H10的光电离质谱图; 通过测量各碎片离子的光电离效率(PIE)曲线, 获得ZnC4H10的电离势(IP=8.20±0.05 eV)及其碎片离子(ZnC2H5+、ZnH+、Zn+、C2H5+、C2H3+等)的出现势. 根据实验结果, 并结合相关文献所给的热力学数据, 推导出这些主要碎片离子的生成焓, 并分析它们可能的解离通道和主要离子的分支比. 结果表明, 其主要解离通道是母体离子发生Zn—C 键的断裂形成ZnC2H5+和C2H5+离子, ZnC2H5+离子再进一步解离形成Zn+离子, 并且含锌碎片离子的丰度占75%以上.