Novel fluorosilicone triblock copolymers prepared by two-step RAFT polymerization: Synthesis, characterization, and surface properties

Well-defined poly(dimethylsiloxane)-b-poly(2,2,3,3,4,4,4-heptafluorobutyl methacrylate-b-poly(styrene) (PDMS-b-PHFBMA-b-PS) triblock copolymers were prepared by two-step reversible addition-fragmentation chain transfer (RAFT) polymerization. The two-step RAFT polymerization proceeded in a controlled manner as demonstrated by the macromolecular characteristics of the blocks and corresponding polymerization kinetic data. Furthermore, surface properties and morphologies of the polymers were investigated with static water contact angle (WCA) measurement, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and atomic force microscopy (AFM) which showed low surface energy and microphase-separation surfaces.     

Crystal Structure of 9α,11-Epoxy-7α-(methoxycarbonyl)-3-oxo-17α-pregn-4-ene-21,17-carbolactone

Abstract  The title compound (common name eplerenone), C₂₄H₃₀O₆, is an aldosterone receptor antagonist. From the isopropyl acetate solution the compound crystallizes in monoclinic space group P 21 with a = 8.811(1) ?, b = 11.250(1) ?, c = 11.079(1) ?, β = 93.822(12)°, Z = 2. The molecule contains three six membered rings, two five membered rings and one three membered ring. Both five membered rings display envelope conformation, whereas three six membered rings show different conformation: chair, half-chair and envelope. In the crystal the eplerenone molecules link to one another via intermolecular weak C–H···O hydrogen bonding to form the smaller cavity of 12.0(1) ?³ between eplerenone molecules, no solvent molecule filled in this cavity. Index Abstract  In the title molecule three six-membered rings show different conformation. Weak C–H···O hydrogen bonding links adjacent molecules to form the small cavity 12.0(1) ?³, no solvent molecule filled in the cavity.      

Synthesis and crystal structure of a pyrroline nitroxide radical, (N-2,2,5,5-tetramethyl-1-oxo-3-pyrroline-3-carbonyl) (N,N′-diisopropyl)urea

The title compound including a stable nitroxide radical was synthesized by a reaction of N,N-diisopropylcarbondiimide (DIC) with 2,2,5,5-tetramethyl-1-oxo-3-pyrroline-3-carboxylic acid (TPCO) in an EtOAc solution under nitrogen atmosphere. From 1:1 EtOAc/hexane the compound crystallizes in triclinic space group P with a = 11.078(2), b = 11.970(2), c = 15.746(3) Å, = 105.41(3), = 103.47(3), = 106.52(3)°, and Z = 4. In an asymmetric unit two molecules assemble with each other in similar bond distances and angles but show crystallographically independent conformation. A normal single C–N bond is observed in the title compound, other than the partial double C=N bond shown in the parent urea. A longer N–O distance of 1.26 Å implies the existence of a single electron bond between N and O atoms, which stabilizes the radical molecule.     

求解二次Lagrangian有限元方程的代数两水平方法

基于矩阵图集的粗化算法,构造一种新的插值算子,提出了瀑布型代数两重网格法;然后结合部分几何信息,提出了求解二次Lagrangian有限元方程的代数两水平方法.数值实验表明该算法稳健性强、计算量更少.     

金属诱导低温制备多晶硅薄膜工艺新进展

多晶硅薄膜由于兼具稳定性、高光敏性、便于大面积沉积等优势成为目前光伏领域的研究热点.本文综述了近几年金属诱导非晶硅薄膜晶化的新工艺,介绍了各种工艺条件对多晶硅薄膜材料的结构、金属含量的调控规律.最后展望了未来的发展趋势.     

Bi-2223/Ag高温超导带临界电流各向异性的实验测量及分析

本文介绍了Bi-2223/Ag高温超导带临界电流各向异性的实验测量方法及原理,指出了在不同磁场方向(与超导带面夹角)下,Bi-2223/Ag带临界电流随直流背景磁场的变化规律以及实验应注意的问题.Bi-2223/Ag带材的各向异性决定了其临界电流对垂直于带材表面的磁场非常敏感,这是该带材在高温超导磁体等强电应用方面的不利因素.     

用光学差分吸收光谱监测大气中污染气体浓度

在实验室内模拟测量了实际大气中污染气体的差分吸收光谱 (DOAS) .本文在介绍差分吸收光谱技术同时 ,分析计算了污染气体的浓度 .实验设计中被测气体为大气中的 2种主要污染气体 :工业锅炉的主要排放物SO2 和机动车尾气的主要成分NO .用氘灯作为光源测量其在紫外波段的特征吸收 ,并通过光纤束连接光栅光谱仪 ,由计算机自动采集和处理数据 .     

SF-10深海复合棒振子的设计及其布阵应用

本文介绍采用“外预应力筒”结构代替“中心预应力螺杆”结构的复合棒振子设计;从而得到一种无障板、无去耦材料、自身形成单向辐射指向性、水密性能良好的深水复合棒振子。能灵活方便地应用于水面或深水声阵中。
最后用此振子设计了一个无障板的圆环形深海发射阵,并给出了实验数据。     

Effect of Pretreatment of TaN Substrates on Atomic Layer Deposition Growth of Ru Thin Films

The polycrystalline ruthenium films are grown on TaN substrates by atomic layer deposition （ALD） using bis（cyclopentadienyl） ruthenium [RuCp2] and oxygen as ruthenium precursor and reactant respectively at a deposition temperature of 330℃. The low-energy Ar ion bombardment and Ru pre-deposition are performed to the underlying TaN substrates before ALD process in order to improve the Ru nucleation. X-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy are carried out to characterize the properties of ALD Ru films. The results show that the nucleation density of Ru films with Ar^＋ bombardment to the underlying TaN substrates is much higher than that of the ones without any pretreatment. The possible reasons are discussed.