2‐(1‐Ethynylpyrene)‐Adenosine as a Folding Probe for RNA—Pyrene in or out

A series of short RNA duplexes containing one or two 1‐ethynylpyrene‐modified adenine bases was synthesised. The melting behaviour of these duplexes was examined by monitoring temperature‐dependent pyrene fluorescence. In the singly modified RNA duplexes, the bases flanking the ethynylpyrene‐rA were varied to examine the sequence specificity of the fluorescence change of pyrene upon RNA hybridisation. Because an increase in pyrene fluorescence upon melting of the duplex can be correlated with intercalation of pyrene, and a decrease is usually associated with the position of pyrene outside the strand, a relationship between the flanking bases and the tendency of the dye to intercalate has been established. It was found that pyrene intercalation is less likely to take place if the modified base is flanked only by A–U base pairs. Flanking G–C base pairs, even only in the 5′‐direction of the modified base, will favour intercalation. In addition, we examined a doubly modified compound that had a pyrene located on each strand. The spectra indicated that the two pyrenes were close enough for interaction. Upon melting of the strand, a fluorescence blue shift corresponding to the dissociation of the pyrene–pyrene complex could be observed in addition to the intensity effect already known from the singly modified compounds. Two melting curves based on the different properties of the fluorophore could be extracted, leading to different melting points corresponding to the global duplex melting and to the change of local pyrene environment, respectively.     

A highly luminescent organic crystal with the well-balanced charge transport property: The role of cyano-substitution in the terminal phenyl unit of distyrylbenzene

1,4-bis(2-cyano styryl)benzene (2-CSB) crystal with cyano substituent groups introduced to the terminal phenyl rings of distyrylbenzene (DSB) has been prepared and its luminescence efficiency could be as high as ∼55%. Based on the analyses of cyclic voltammetry and crystal structure, cyano substituents not only lower the LUMO level but also result in a change of the packing mode from the herringbone arrangement to the face-to-face slipped π stacking motif. Then field-effect transistors (FETs) based on high-quality 2-CSB crystals grown by the physical vapor transport method have been fabricated and the highest hole and electron mobilities were measured as 0.66 and 0.29 cm²/Vs, which enhanced the corresponding values of DSB crystal by up to one and two orders of magnitude, respectively. 2-CSB crystal simultaneously combined the high luminescence and the well-balanced mobility is expected to be of interest for the fundamental research of organic light-emitting devices.     

X-ray photoemission spectrum, electronic structure, and magnetism of UCu2Si2

The room temperature X-ray photoemission spectrum of the ferromagnetic compound UCu₂Si₂ (T_C = 100 K) was measured using an Al K_α source. Related theoretical spectra were computed from densities of electronic states obtained in the local density approximation (LDA), the generalized gradient approximation (GGA), and using the GGA + U method. The calculated spectrum is in a good agreement with the experimental one. The spin polarized calculations based on the GGA + U approach as well as GGA/LSDA with orbital polarization (OP) corrections taken into account provide values of the total magnetic moment in reasonable agreement with the experimental values ranging between 1.6 and 2.0 μ_B/U atom.     

Magnetocaloric effect in the Ce2Fe17−xMnx helical magnets

The Ce₂Fe_17−xMn_x (x = 0-2) compounds demonstrate a complex temperature dependence of the magnetocaloric effect MCE, which is inverse in a narrow temperature interval just below Néel temperature T_N and normal at higher or lower temperatures. The normal MCE exhibits two peaks in the vicinity of temperatures of ferromagnetic ordering Θ_T and T_N for compositions x = 0-0.35, 1.3-2 or one peak near T_N for antiferromagnets with x = 0.5-1. The maximal change of the peak entropy −S_M is about 3 J/kg K in a field of 5 T for the compounds with x = 0-0.5 at T ∼230 K close to T_N. The drastic decrease of the MCE, by half, in the Ce₂Fe_17−xMn_x system is traceable to a decrease of the spontaneous magnetization and the helical type of magnetic states in the compounds.     

用新型稀土-铝有序介孔纳米复合材料削减PM2．5的创新研究

新《环境空气质量标准》已经出台，其中的PM2．5指标已被列入相关的国标，并纳入各省市强制监测范畴，作为导致PM2．5主要因素的汽车尾气控制势在必行。本文创新性地使用“前置装置”，即将稀土-铝纳米复合材料，通过油路上的1个滤网，以缓释的方式添加到汽油中，利用纳米材料的特性，对汽油催化助燃，并促使其充分燃烧，从燃烧源头上削减尾气中PM2．5的产生，克服以往单纯依靠“后处理装置”无法有效防治PM2．5产生的问题。拟通过微观调控及优化组装，研发催化助燃效果良好的稀土-铝有序介孔纳米复合材料，分析评定其降低PM2．5尾气排放的功效。本研究可丰富纳米微观基础理论，促进纳米环保交叉学科的发展；同时，对解决全球关注的环境保护问题及生态文明建设，也具有重要的现实意义，体现了纳米材料的时代效应。     

永磁感应子式步进电动机转子铁心迭片系数的影响及其修正方法

介绍了混合式步进电动机转子铁心迭片系数产生的影响和修正方法，以及利用提高转矩的有关结构。     

Progressive viewing and sharing of sensitive images

The paper proposes a progressive viewing method useful in sharing a sensitive image. As in visual cryptography, this method characterizes its ability to recover the image by stacking transparencies without any computation. However, the method balances the sensitivity and the daily-processing convenience of the image. The text was submitted by the authors in English. Wen-Pinn Fang was born in 1971 in Taiwan, Republic of China. He received his BS degree in mechanical engineering from National Sun-Yet-Sans University in 1994, and MS degree in mechanical engineering from National Chiao Tung University in 1998. In 2006 he received his PhD in Computer Science Department of National Chiao Tung University. His recent research interests include image sharing and image processing. Ja-Chen Lin was born in 1955 in Taiwan, Republic of China. He received his BS degree in computer science in 1977 and MS degree in applied mathematics in 1979, both from National Chiao Tung University, Taiwan. In 1988 he received his PhD in mathematics from Purdue University, United States. In 1981–1982, he was an instructor at National Chiao Tung University. From 1984 to 1988, he was a graduate instructor at Purdue University. He joined the Department of Computer and Information Science at National Chiao Tung University in August 1988 and is currently a professor there. His recent research interests include pattern recognition and image processing. Dr. Lin is a member of the Phi-Tau-Phi Scholastic Honor Society.