Dielectric and ionic conduction properties in LiYF4 single crystals

A LiYF₄ single crystal was grown by the Czochralski technique in an Ar-gas atmosphere. The complex dielectric constants and complex impedances are measured in the range of 100 Hz–10 MHz and up to 200°C for a c-plate of a LiYF₄ single crystal. The LiYF₄ reveals a strong low frequency dielectric dispersion below 300 kHz, from room temperature to 200°C. It is believed that the strong dielectric dispersion is related to the ionic hopping conduction, which arises mainly from the jumping of Li⁺-ions between neighboring sites, with an activation energy of Δ=0.49 eV. The conduction mechanism seems to be the non-interacting Debye type and the relaxation times satisfy the Arrhenius relation.     

Efficient morphological segmentation using a new connected operator

An efficient segmentation algorithm for region-based coding is proposed. A new connected operator based on both size and contrast is presented and an efficient region merging algorithm which preserves high quality in terms of the number of regions is proposed. Experimental results show that the proposed algorithm achieves a good performance in terms of the image quality and the number of regions     

Effectiveness of remote control for a concrete surface grinding machine

Concrete surface grinding is usually executed in hazardous work environments. The operation needs to be given a certain degree of automated capabilities to overcome the hazards, and to increase operational effectiveness. The objective of this research is to provide a CAD-based path planner for the REmotely controlled Machine for COncrete Grinding (REMCOG). The planner generates a desired path that the machine needs to follow. The path displayed on screen was in turn used as a guide for the Man–Machine Interface (MMI) during the operation. GPS data were acquired to determine whether the machine was following the planned path. Field experiments demonstrated that operators can compare the planned and actual paths to gain a better understanding of whether the remotely controlled machine is moving in the right direction during the operation. As a result, the production rate showed a significant increase compared with the existing manually operated machine for concrete surface grinding.     

Structural and optical properties of epitaxial ZnO thin films on 4H–SiC (0 0 0 1) substrates prepared by pulsed laser deposition

Epitaxially grown ZnO thin films on 4H–SiC (0 0 0 1) substrates were prepared by using a pulsed laser deposition (PLD) technique at various substrate temperatures from room temperature to 600 °C. The crystallinity, in-plane relationship, surface morphology and optical properties of the ZnO films were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and photoluminescence (PL) measurements, respectively. XRD analysis showed that highly c-axis oriented ZnO films were grown epitaxially on 4H–SiC (0 0 0 1) with no lattice rotation at all substrate temperatures, unlike on other hexagonal-structured substrates, due to the very small lattice mismatch between ZnO and 4H–SiC of ～5.49%. Further characterization showed that the substrate temperature has a great influence on the properties of the ZnO films on 4H–SiC substrates. The crystalline quality of the films was improved, and surfaces became denser and smoother as the substrate temperature increased. The temperature-dependent PL measurements revealed the strong near-band-edge (NBE) ultraviolet (UV) emission and the weak deep-level (DL) blue-green band emission at a substrate temperature of 400 °C.     

Hybrid copper complex-derived conductive patterns printed on polyimide substrates

We synthesized new copper complexes that can be readily converted into highly conductive Cu film. Mechanochemical milling of copper (I) oxide suspended in formic acid resulted in the submicron-sized Cu formate together Cu nanoparticles. The submicrometer-sized Cu formates are reactive toward inter-particle sintering and metallic Cu seeds present in the Cu complexes assist their decomposition and the nucleation of Cu. The hybrid copper complex film printed on polyimide substrate is decomposed into dense and uniform Cu layer after annealing at 250 °C for 30 min under nitrogen atmosphere. The resulting Cu film exhibited a low resistivity of 8.2 ???·cm and good adhesion characteristics.     

基于甲基化DNA分离方法的甲基化DNA检测和全基因水平的甲基化分析

已知异常的DNA甲基化对基因表达有明显影响并且涉及包括癌症等的疾病以及正常状态,因此从非甲基化DNA中鉴定甲基化DNA的分析技术是非常必须的。本文介绍了一种利用甲基化DNA结合域对甲基化DNA的亲和性质将甲基化DNA从全基因中成功提取的甲基化DNA分离技术（MeDIA）。结合MeDIA的PCR和CpG芯片技术分别实现了局部位置甲基化DNA状态的评估以及全基因的甲基化分析。     

Atomistic Simulation of Frictional Sliding Between Cellulose Iβ Nanocrystals

Sliding friction between cellulose Iβ nanocrystals is studied using molecular dynamics simulation. The effects of sliding velocity, normal load, and relative angle between sliding surface are predicted, and the results analyzed in terms of the number of hydrogen bonds within and between the cellulose chains. We find that although the observed friction trends can be correlated with hydrogen bonding, it may not be the most significant factor in determining frictional behavior on cellulose nanocrystal surfaces.