Comparative analysis of indentation and magnetic resonance elastography for measuring viscoelastic properties

Acta Mechanica Sinica - Measurement the viscoelastic properties is important for studying the developmental and pathological behavior of soft biological tissues. Magnetic resonance elastography...     

燃放烟花爆竹对空气污染的调查和研究

燃放烟花爆竹是一个历史悠久的民间习俗,在它带来的安全隐患被人们广泛关注的同时,其燃放过程造成的空气污染也不容忽视。本研究通过实验室模拟,测定了燃放一枚鞭炮产生的二氧化硫气体量,并通过收集、分析杭州市区近几年来春节期间空气状况的数据,验证了燃放烟花爆竹造成空气污染的设想,并提出了科学燃放烟花爆竹的方法。     

Columnar Self‐Assembly in Electron‐Deficient Heterotriangulenes

A series of soluble carbonyl‐bridged heterotriangulenes, in which flexible n‐dodecyl chains are attached through different spacers to the planar nitrogen‐centered polycyclic core, have been synthesized. The introduction of triisopropylsilylethynyl moieties enabled, for the first time, the characterization of single‐crystal columnar packing of a substituted heterotriangulene by X‐ray crystallography. Electrochemical studies disclosed the carbonyl‐bridged heterotriangulene core as a reasonably strong acceptor for a reversible two‐electron transfer. The tendency of substituted heterotriangulenes to self‐assemble in solution, on surfaces, and in the bulk appeared to sensitively depend on the nature of the lateral substituents, their steric demand, and the applied solution processing conditions. It can be concluded that 1) additional phenylene moieties between the heterotriangulene core and the n‐dodecyl chains facilitate self‐assembly by extending the π‐conjugated polycyclic disc, 2) the rod‐like ethynylene spacers introduce some additional flexibility and hence lower the overall aggregation tendency, and 3) the combination of both features in the phenylene–ethynylene moieties induces thermotropic liquid crystallinity.     

Microstructure evolution and device performance in solution-processed polymeric field-effect transistors: the key role of the first monolayer

Probing the role of the first monolayer in the evolution of the film polymer microstructure is essential for the fundamental understanding of the charge carrier transport in polymeric field-effect transistors (FETs). The monolayer and its subsequent microstructure of a conjugated polymer [poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene), PBTTT] film were fabricated via solution deposition by tuning the dip-coating speed and were then studied as accumulation and transporting layers in FETs. Investigation of the microstructure of the layers prepared at different coating velocities revealed that the monolayer serves as an important base for further development of the film. Significant improvement of the charge carrier transport occurs only at a critical multilayer network density that establishes the required percolation pathways for the charge carriers. Finally, at a low dip-coating speed, the polymer chains are uniaxially oriented, yielding pronounced structural anisotropy and high charge carrier mobilities of 1.3 cm(2) V(-1) s(-1) in the alignment direction.     

Making benzotrithiophene a stronger electron donor

A new member of the benzotrithiophene family, benzo[2,1-b:-3,4-b':5,6-c″]trithiophene (3a), and its alkyl substituted derivatives (3b-e) were synthesized and characterized. Their photophyscial, electrochemical, crystallographic, and self-assembly properties were described. Thin film structures varied widely with the exact nature of the alkyl substitution pattern, with decreasing self-assembly propensity with increasing alkyl chain length. The high HOMO levels and the coplanarity of these molecules show their potential as organic semiconductors and as donor components in donor-acceptor copolymers.     

Effect of (3‐glycidyloxypropyl)trimethoxysilane (GOPS) on the electrical properties of PEDOT:PSS films

Poly(3,4‐ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) has been reported as a successful functional material in a broad variety of applications. One of the most important advantages of PEDOT:PSS is its water‐solubility, which enables simple and environmental friendly manufacturing processes. Unfortunately, this also implies that pristine PEDOT:PSS films are unsuitable for applications in aqueous environments. To reach stability in polar solvents, (3‐glycidyloxypropyl)trimethoxysilane (GOPS) is typically used to cross‐link PEDOT:PSS. Although this strategy is widely used, its mechanism and effect on PEDOT:PSS performance have not been articulated yet. Here, we present a broad study that provides a better understanding of the effect of GOPS on the electrical and electronic properties of PEDOT:PSS. We show that the GOPS reacts with the sulfonic acid group of the excess PSS, causing a change in the PEDOT:PSS film morphology, while the oxidation level of PEDOT remains unaffected. This is at the origin of the observed conductivity changes. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 814–820     

聚苯硫醚超疏水复合涂层的制备与性能

利用工业原料聚苯硫醚微粉和疏水性二氧化硅纳米粉末,采用喷涂法在瓷砖表面制备了疏水复合涂层.研究了热处理温度、组分配比对涂层表面形貌、粗糙度和接触角的影响,发现随着热处理温度升高,涂层表面粗糙度增大,随着疏水性二氧化硅含量的增加,由于表面聚集的疏水性二氧化硅增多,涂层疏水性增强,在热处理温度为280℃、疏水性二氧化硅与聚苯硫醚质量比为1∶1时,可获得超疏水涂层,涂层的接触角大于150°,滚落角小于4°,pH值为1～14的水溶液在其表面都具有很高的接触角.超疏水涂层具有良好的自清洁效果,并且经落沙法实验测定,超疏水涂层耐刮伤性能良好.     

新课程背景下化学课堂教学设计的实践与思考

化学课程标准下的化学课堂教学怎样才能体现出课程改革的新理念?从课堂教学的理念、课堂教学的宗旨、课堂教学的资源、课堂教学的过程等角度,探讨了新课程背景下化学课堂教学的设计与实施的准则与案例。