The influence of the preparation conditions and filler content on thermal properties of poly‐l‐lactide and hydroxyapatite/poly‐l‐lactide nanocomposite

Poly‐l ‐lactide (PLLA) and hydroxyapatite/poly‐l ‐lactide (HAp/PLLA) are two widely used biomaterials for three‐dimensional scaffolds, drug release matrices and implantable medical devices for reparation of bone tissue; diversity in the initial preparation and filler content has a significant influence on different properties such as morphology and crystallinity, thus playing a considerable role in most of these applications. For this reason, PLLA and HAp/PLLA samples with a large difference in crystallinity (from below 20% to over 70%) and filler content (up to 86 wt% of HAp nanoparticles with an average diameter of 80 nm) were prepared and consequent dissimilarities in morphology, crystallinity and thermal properties were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), wide angle X‐ray diffraction (WAXD) measurements and Fourier transform infrared (FTIR) spectroscopy. Special attention was devoted to analyzing data obtained from thermal measurements. A three‐phase model was employed in order to describe the heat capacity step decline in the nanocomposite; the evolution in different polymer fractions, the crystalline fraction and the mobile and rigid amorphous fractions, with filler content was determined. © 2017 Society of Chemical Industry     

A Coordinate-Descent-Based Approach to Solving the Sparse Group Elastic Net

Group sparse approaches to regression modeling are finding ever increasing utility in an array of application areas. While group sparsity can help assess certain data structures, it is desirable in many instances to also capture element-wise sparsity. Recent work exploring the latter has been conducted in the context of <i>l</i><sub>2</sub>/<i>l</i><sub>1</sub> penalized regression in the form of the sparse group lasso (SGL). Here, we present a novel model, called the sparse group elastic net (SGEN), which uses an <i>l</i><sub>∞</sub>/<i>l</i><sub>1</sub>/ridge-based penalty. We show that the <i>l</i><sub>∞</sub>-norm, which induces group sparsity is particularly effective in the presence of noisy data. We solve the SGEN model using a coordinate descent-based procedure and compare its performance to the SGL and related methods in the context of hyperspectral imaging in the presence of noisy observations. Supplementary materials for this article are available online.     

GL-88级高铝料的发展状况

简述了GL-88级高铝料的煅烧方法、质量波动和价格变化等。能源结构的变化和降本增效的需要,加之燃气竖窑生产技术的日趋成熟,促使GL-88级高铝料煅烧方式向节能燃气竖窑方向快速发展。铝工业高速发展导致铝矾土生料供不应求,致使十年来GL-88级高铝料价格的快速上涨和质量的波动。     

纳米结构分子吸附引起的表面增强拉曼散射研究

利用模板印刷技术,制备了具有不同局域表面等离子体共振(LSPR)峰的Au纳米空心半球壳结构,并以4-巯基苯胺(4-ATP)为探针分子研究了纳米结构表面吸附分子对表面增强拉曼散射(SERS)强度的影响。结果表明,当纳米结构的LSPR峰位处于激发光波长的短波长或"马鞍型"位置时,SERS强度随吸附分子数的增加而增大;当处于长波长位置时,SERS强度呈现先增大后减小的趋势。利用分子吸附理论和纳米结构表面局域场强度变化,对此现象进行了解释。     

自适应环境变化的RSS室内定位方法

根据定位问题的天然稀疏性,提出一种基于两步字典学习的定位方法,依据测量值动态调整字典,使稀疏模型能够自适应RSS的变化。同时提出一种改进的加权l1范数稀疏重构算法,提高低信噪比情况下的重构精度。实验结果表明该方法可以在目标数量未知的情况下实现多目标定位,并具有较强的抗噪声能力。     

Removal of Cr(VI) ions from waste water by electrocoagulation using iron electrode

The performance of electrocoagulation using iron electrodes for the treatment of aqueous solutions containing chromium hexavalent ions using fixed bed electrochemical batch reactor was studied. A new anode design consisting of hex nuts was connected together with a thin rode of iron. The helical shape in the nuts increases the anode surface area allowing high chromium removal rate within very short coagulation time. The effect of different parameters affecting the electrocoagulation process, such as initial hexavalent chromium concentration, applied current, electrolyte type [sodium chloride and sodium sulfate] concentration and initial pH of the solution was investigated. The optimum conditions for the EC process by using the present cell based on minimum initial hexavalent chromium concentration, energy consumption and operating cost were 100<!-- --> <!-- -->mg of Cr(VI)/l, 0.55<!-- --> <!-- -->A, 1.5<!-- --> <!-- -->g of sodium chloride/land pH of 1.     

多项式分布滞后模型在桥梁挠度预测中的应用

介绍了PDL(多项式分布滞后)模型,并将其应用于某桥梁挠度预测,重点考虑了温度以及车流量对挠度的影响。借助EVIEWS软件对桥梁不同时期的挠度变形值进行预测,并与灰色GM(1,1)模型的预测结果进行对比分析。结果表明,PDL模型具有比灰色模型更高的预测精度,其预测结果更为可靠,对类似工程有一定的借鉴作用。     

The Effect of Surface-Active Phospholipids on the Lubrication of Osteoarthritic Sheep Knee Joints: Friction

The synovial fluid aspirate from human joints that have experienced serious traumatic injury has been shown to have lower concentrations of phospholipids when compared with healthy joints. Previous studies provide evidence that synovial fluid constituents, specifically dipalmitoyl phosphatidylcholine (L<img src="/content/j47p6435l412534q/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-DPPC), are highly surface active, capable of rapidly depositing a layer of phospholipids onto glass. Such research has demonstrated that the adsorbed surface layers of synovial surfactant are excellent lubricants in vitro, significantly reducing the coefficient of friction under physiological loading in human knee joints. This study aimed to investigate the effect of concentration of L<img src="/content/j47p6435l412534q/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-DPPC lubricant solutions on the coefficient of friction of worn articular cartilage on steel. A pin-on-disc apparatus was used to measure the coefficient of friction of sheep-knee articular cartilage on steel under unidirectional sliding at physiological conditions of load and speed. Concentrations of L<img src="/content/j47p6435l412534q/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-DPPC solution between 100 times less and 100 times more than is normally present in synovial fluid were tested. All specimens were tested following a period of unlubricated induced wear. Trials were carried out at ambient temperature and between 33–37°C (representative of in vivo joint temperature). Friction measurement results demonstrated a reduction in the coefficient of friction of worn articular cartilage against steel with increasing concentrations of L<img src="/content/j47p6435l412534q/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-DPPC in lubricant solution.