A physical strategy for the preparation of isotactic polypropylene spheres with microsphere and bead–string spherulite morphologies

This study mainly focuses on the formation of isotactic polypropylene (iPP) blend morphologies with microspheres and distinct bead–string spherulites. iPP microspheres have been prepared by a simple and convenient strategy through either an isothermal or a nonisothermal crystallization process based on the macrophase‐separated structure in molten state of iPP/olefin block copolymer (OBC) blend. The dimension of the iPP spheres can be adjusted easily from about 1 µm to >10 µm by controlling the compatibility and annealing conditions. It was found that any of the following three parameters, the molecular structure of OBC (particularly the octene content), molecular weight of iPP, and annealing condition can be rescaled with others in controlling the dimension of the iPP microspheres. The mechanism of the formation of iPP microspheres was studied in detail. Surprisingly, the typical spinodal decomposition morphology with interconnected or thin sheet structure is the precursor of these microspheres. During the subsequent annealing process, it breaks up and further coarsens into spherical structure. In addition, distinct spherulites with a bead–string substructure have been obtained during the isothermal crystallization. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40863.     

除草剂吡草胺的合成

以2,6-二甲基苯胺为原料,与多聚甲醛经亲核消除反应生成希夫碱,再与氯乙酰氯加成反应,最后与吡唑缩合转晶得到除草剂原药吡草胺三斜晶形,总收率达71.5%(以2,6-二甲基苯胺计),含量大于97%,该工艺方法简便、易行,具有工业化应用前景。     

Visible Light‐Initiated C(sp3)?Br/C(sp3)?H Functionalization of α‐Carbonyl Alkyl Bromides through Hydride Radical Shift

A new visible light‐initiated 1,5‐hydride radical shift strategy has been developed to enable the one‐step functionalization of both a C(sp³) Br bond and a C(sp³) H bond adjacent to the same carbon atom. This visible light photoredox catalysis offers a mild and straightforward access to diverse five‐membered carbocyclic ring‐fused polycyclic hydrocarbons with high turnover numbers (TONs; up to 4.93×10³) and broad substrate scope.

     

Efficient Catalyst for Both Suzuki and Heck Cross‐Coupling Reactions: Synthesis and Catalytic Behaviour of Geometry‐ Constrained Iminopyridylpalladium Chlorides

A series of geometry‐constrained iminopyridyl‐palladium chlorides were synthesized and characterized. These phosphine‐free palladium complexes were explored for their catalytic activities in both Suzuki and Heck cross‐coupling reactions, achieving turnover numbers as high as 10⁶ towards various aryl bromides, even those containing various functionalities. In addition, the influence of substituents with steric and electronic factors was reflected by the differences observed in their activities.

     

Fabrication of shish-kebab-structured carbon nanotube/poly(ε-caprolactone) composite nanofibers for potential tissue engineering applications

The electrospinning process was applied to fabricate the nanofibers of biodegradable poly(ε-caprolactone)(PCL) in which different contents of multiwalled carbon nanotubes(MWCNTs) were embedded. Afterward,the electrospun nanofibers were successfully decorated with shish-kebab structure via a self-induced crystallization technique. The topographical features and the mechanical properties of the composite scaffolds were characterized,and the biocompatibility of the material was assessed by using human osteogenic sarcoma osteoblasts(MG-63 cells). The carbon nanotube(CNT) concentration is found to affect the fiber diameter and mechanical properties of electrospun nanofibers and the periodic distance of the shish-kebab architecture. Cellular attachment and proliferation assays reveal that 0.5 wt% CNT-embedded PCL scaffold shows enhanced biocompatibility with MG-63 cells than their counterparts made of neat PCL, and the collagen-like nanotopology provided by the shish-kebab structure further facilitates the cell adhesion and proliferation. The superior interactions between cells and scaffolds demonstrate that the shish-kebab-structured CNTs/PCL nanofibers may be promising candidate for tissue engineering scaffold application.     

Formation of self-organized Zircaloy-4 oxide nanotubes in organic viscous electrolyte via anodization

This work reports the formation of self-organized Zircaloy-4 (Zr-4) oxide nanotubes in viscous organic ethylene glycol (EG) electrolyte containing a small amount of fluoride salt and deionized (DI) water via an electrochemical anodization. The structure, morphology, and composition of the Zr-4 oxide nanotubes were studied using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), EDX, and XPS. SEM results showed that the length of the nanotubes is approximately 13 μm, and TEM results showed that the inner diameter of the Zr-4 oxide nanotubes is approximately 20 nm with average wall thickness of approximately 7 nm. XRD and selected area electron diffraction pattern (SAED) results confirmed that the as-anodized Zr-4 oxide nanotubes have cubic crystalline structure. Both cubic and monoclinic phases were found after annealing of Zr-4 oxide nanotubes. The tubular structure morphology of Zr-4 oxide nanotubes did not remain intact after annealing which is attributed to the elimination of F species from the annealed nanotubes.     

Preparation of Lung-Targeting,Emodin-Loaded Polylactic Acid Microspheres and Their Properties

Emodin (1,3,8-trihydroxy-6-methylanthraquinone) has been identified to have the potential to improve lung fibrosis and lung cancer. To avoid the liver and kidney toxicities and the fast metabolism of emodin, emodin-loaded polylactic acid microspheres (ED-PLA-MS) were prepared and their characteristics were studied. ED-PLA-MS were prepared by the organic phase dispersion-solvent diffusion method. By applying an orthogonal design, our results indicated that the optimal formulation was 12 mg/mL PLA, 0.5% gelatin, and an organic phase:glycerol ratio of 1:20. Using the optimal experimental conditions, the drug loading and encapsulation efficiencies were (19.0 ± 1.8)% and (62.2 ± 2.6)%, respectively. The average particle size was 9.7 ± 0.7 μm. In vitro studies indicated that the ED-PLA-MS demonstrated a well-sustained release efficacy. The microspheres delivered emodin, primarily to the lungs of mice, upon intravenous injection. It was also detected by microscopy that partial lung inflammation was observed in lung tissues and no pathological changes were found in other tissues of the ED-PLA-MS-treated animals. These results suggested that ED-PLA-MS are of potential value in treating lung diseases in animals.     

广东省自然保护地暗夜公园建设选址 适宜性评价

快速城市化引起的光污染使得黑暗的夜空逐渐稀缺。暗夜公园作为暗夜保护的主要类型之一,在国内外受到越来越多的关注。具有优越本底环境的自然保护地是暗夜公园建设选址的重要备选对象。根据国际暗夜协会对暗夜公园的认证要求,初步筛选出广东省具有暗夜公园建设潜力的备选保护地,将NPP-VIIRS夜间灯光数据作为暗夜资源识别的依据,从观星质量制约条件、游客吸引程度和政府投资可行性三方面出发,构建暗夜公园建设选址适宜性综合评价指标体系;应用GIS空间分析法和层次分析法,探讨广东省建立暗夜公园最适宜的自然保护地。结果表明：广东省适合建设暗夜公园的自然保护地数量占比仅约为3%,其中2/3集中在经济发展落后于珠三角地区的粤西、粤东和粤北地区,1/3分布于珠三角地区的惠州市和江门市。暗夜公园建设最优选址为梅州五华天堂山市级自然保护区,该自然保护地具有晴天率高、与城镇距离适中、周边旅游景点多等优势,且具有丰富的山区生态资源与深厚的客家文化底蕴,有利于打造具有地方特色的暗夜公园。通过制定一套自然保护地暗夜公园选址适宜性评价的方法和流程,为广东省自然保护地暗夜公园建设提供了重要的选址参考。     

APS与传统CRP的能力需求分析比较

通过编制传统的CRP,由最后生成的工作中心的负荷图发现了人力资源的浪费并提出了裁员和增加新设备的解决方案.在APS的编制过程中,首先寻找总体关键路径作为生产的主要路径,并确定辅助关键路径来充分利用生产资源,以顺排和倒排相结合的方法进行排程并计算出总定额工时,从而选择出最优方案,对资源浪费现象提出了不同程度地裁员和增加新设备的解决措施.最后,归纳总结了高级计划与排程相比较于传统能力需求计划的特点.