Surface properties and surface patterning of UV-curable coating using perfluorosilane-treated nanosilica

In this work, a one-step film formation method is demonstrated to obtain the patterned surface of an acrylate photocuring coating using nano-silica particles treated with a perfluoroalkoxysilane ((heptadecafluoro-1,1,2,2-tetra hydrodecyl) triethoxysilane) as a nanoadditive. Nanosilica particles were treated with perfluoroalkoxysilane and used in a UV-curable matrix. The typical patterns on the surface of the UV-cured films are revealed in AFM images. The surface properties of the cured films were investigated by measuring water contact angle and surface energy. The degree of conversion of the samples was obtained by FTIR analysis and pendulum hardness was measured using a Konig hardness meter. Scratch resistance of cured films was measured by standard scratch measuring pens. The characteristics obtained from AFM analysis showed that rough surface patterns in this system are controlled linearly by changes in the treated nano-particle concentration. The subtraction of surface energy of the cured film was clear and the water contact angle showed a 60% increase with the addition of a fluorinated nano-particle concentration. Surface hardness decreased and scratch resistance increased as the concentration of treated nanoparticles increased, while the final degree of conversion of the film remained unchanged.     

From ferroelectric to relaxor behaviour in the Aurivillius-type Bi4−xBaxTi3−xNbxO12 (0≤x≤1.4) solid solutions

Solid solutions of the Aurivillius-type compounds with Bi_4−xBa_xTi_3−xNb_xO₁₂ formula were prepared by solid-state reaction of the constitutive oxides at optimised temperatures. The room temperature structural data were obtained from X-ray diffraction (XRD). The solubility limit of (Ba, Nb) was estimated to x=1.4. The dielectric properties of sintered ceramics were investigated in wide temperature (25–800 °C) and frequency (1 kHz–1 MHz) ranges. For low substitution rates (0≤x≤0.4) the compounds behave as normal ferroelectrics with Curie temperature decreasing with increasing x. For x≥0.6, the materials exhibit a ferroelectric relaxor-type behaviour which was correlated to the relaxation of polar clusters induced by the heterovalent substitution on Bi and Ti sites.     

Correlation of miscibility and mechanical properties of polypropylene/olefin block copolymers: Effect of chain composition

This study examines the miscibility and mechanical properties of isotactic polypropylene (iPP) and olefin block copolymer (OBC) blends (70/30 wt %). The blends exhibit phase-separated morphology. The OBC domain size decreases with increasing the 1-octene content in the soft segment. The crystallization, melting behavior, and the long spacing of the iPP component in the blends are nearly the same as those of neat iPP, while the T_g of the iPP component shifts slightly to lower temperature. “Blocky” OBC is immiscible with iPP, while the soft segment rich polymers in OBC could be partially miscible with iPP. The impact strength of the blends is greatly increased with increasing the 1-octene content in the OBC soft segment. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

AZ31镁合金化学转化膜形成的原位成像研究

利用同步辐射X射线实时成像技术,原位研究了处理液组分H3PO4,KMnO4及MnCO3对镁合金/处理液界面无铬化学转化膜形成过程的影响,并结合扫描电镜分析了所生成转化膜的表面形貌.研究结果表明:高能同步辐射X射线可以透过镁合金/处理液界面,利用原位成像技术能够实时观察转化膜的生长过程;KMnO4能够显著促进AZ31镁合金转化膜的形成,所得到的转化膜表面较平整,裂纹较少,而MnCO3对转化膜形成的促进作用有限.     

Creating Atomic Ordering in Electrocatalysis

Catalysis always proceeds in a chaotic fashion. Therefore, identifying the working principles of heterogeneous catalysts is a challenging task. Creating atomic order in heterogeneous catalysts simplifies this task and also offers new opportunities for rationally designing active sites to manipulate catalytic performance. The recent rapid advances in heterogeneous electrocatalysis have led to exciting progress in the construction of atomically ordered materials. Here, the latest progress in electrocatalysts with the periodic atomic arrangement, including intermetallic compounds with long-range order and metal atom-array catalysts with short-range order is summarized. The synthesis principles and the intriguing physical and chemical properties of these electrocatalysts are discussed. Furthermore, the compelling prospects of atomically ordered catalysts in the frontier of catalyst research are outlined.     

Single crystal β-Ga2O3: Cr grown by floating zone technique and its optical properties

β-Ga2O3 Cr single crystals were grown by floating zone technique. Absorption spectra and fluorescence spectra were measured at room temperature. The values of field splitting parameter Dq and Racah parameter B were obtained by the peak values of absorption spectra. The value 10Dq/B=23.14 manifests that in -Ga2O3 crystals Cr3 ions are influenced by low energy crystal field. After high temperature annealing in air, the Cr3 intrinsic emission was enhanced and the green luminescence disappeared. The strong and broad 691 nm emission was obtained at 420 nm excitation due to the electron transition occurred from 4T2 to 4A2. The studies manifest that the β-Ga2O3 crystals have the potential application for tunable laser.     

Electrochemical power sources for unmanned underwater vehicles used in deep sea survey operations

A comparison of available energy from different power sources for unmanned underwater vehicles, discharged at atmospheric pressure or at ambient pressure, has been undertaken. The basis for the comparison has been a neutrally buoyant power source with a total volume of 300 l. For deep diving vehicles, the use of batteries that can operate at ambient pressure is advantageous. This advantage increases as the mean density of the battery decreases and as the mean density of the pressure hull increases. A fuel cell using spherical gas containers is also an attractive power source for deep diving survey underwater vehicles.     

Observation of cavitation and water-refilling processes in plants with X-ray phase contrast microscopy

With the spatial coherence of X-rays and high flux and brightness of the 3rd generation synchrotron radiation facility, X-ray phase contrast microscopy （XPCM） at Shanghai Synchrotron Radiation Facility （SSRF） can provide high resolution dynamic imaging of low electron density materials in principle. In this paper, we investigated the cavitation and water-refilling processes in rice and bamboo leaves utilizing XPCM at SSRF. The occurrence of xylem cavitation was recorded in vivo. The study also revealed that under different dehydration conditions, cavitation occurs in different degrees, and therefore, the refilling process is different. The results demonstrate that SSRF can provide high enough fluxes to study dynamic processes in plants in real-time, and XPCM is expected to be a promising method to reveal the mechanisms of cavitation and its repair in plants nondestructively.     

Pectinesterase extraction from Mexican lime (Citrus aurantifolia Swingle) and prickly pear (Opuntia ficus indica L.) peels

Extracts from Mexican lime (Citrus aurantifolia Swingle) and prickly pear (Opuntia ficus indica L.) peels were tested for their pectinesterase activity. A factorial design was applied in this study as a method for enzyme extraction in which the variables were the source of enzyme (prickly pear and Mexican lime peels) and the NaCl solution concentration (0–3.0 M). In all cases, enzyme extracts obtained using the same NaCl concentration from lime peel showed higher activity than extracts from prickly pear peel. NaCl concentration influenced the pectinesterase extraction process in both cases. Maximum enzyme activities were obtained with NaCl 0.5 M and 1.0 M for Mexican lime and prickly pear peels, respectively.