Eco-friendly approach for preparation of hybrid silica aerogel via freeze drying method

Journal of Materials Science - In this paper, an eco-friendly method of producing hybrid silica aerogels by freeze-drying method (FD) is proposed. In the freeze-drying system, deionized water was...     

自制实验视频在流变学教学中的应用实践

非牛顿型流体在简单流动条件下可以表现出有趣的流变现象。文章介绍了流变学课程教学中引入流变实验短视频制作,让学生组队自行设计实验并制作视频,演示非牛顿流体与牛顿流体在一定流场和流动条件下的不同行为,并用于课堂实例分析的实践。这种将理论与实践相结合,制作系统性和科普性的视频作品的方式,可以培养学生的创造力,使其更好地理解课本上的知识并用于实践,同时有助于增强学生的团队合作意识和沟通能力,提高学生学习流变学的兴趣。     

火灾初期消防贮水设施探讨

火灾初期的消防给水一般是由设在建筑物最高处的消防水箱提供,但由于建筑物外形、构造或规划等原因,某些工程不能设置消防高位水箱,必须采取其它方式来满足规范要求,本文通过工程实例,对两种用于替代消防高位水箱的气压供水设备进行比较分析,说明采用气体顶压消防供水设备保证火灾初期用水的实用性及优点。     

日本社区营造经验及其对我国公众参与的启示

公众参与在当今社会发展中越发重要,中国目前的公众参与还处于一个过渡阶段,可以从社区基层开始发展。文中通过对日本多个县市网站社区营造的案例总结和知网、CINII、J-stage等论文网站的文献综述,对日本的社区营造的经验进行综合性总结并结合中国目前的公众参与情况提出建议。未来要加强中国公众参与的发展,需要加强分权与基层组织建设,完善法律体系,发挥乡村、大学的潜力,关注弱势群体,打破单独的社区壁垒,让居民与社会和谐相处,互相促进。     

水淹油气藏改建储气库注采工艺联合运行技术

由水淹油气藏改建的地下储气库受油田注水开发和水侵的双重影响,气藏主力产层水淹严重,储层内部油气水三相分布混乱,注采井生产回压高,单井注采气生产能力差,延缓了储气库的达容速度。为此,通过综合分析储气库的注气工艺和采气工艺特点,提出了储气库注气工艺和采气工艺联合运行的新技术,并应用HAZOP方法对该技术进行了风险分析和识别,制订了生产运行风险控制措施。该新技术的成功应用解决了注采井储层水淹和生产回压高的难题,有效改善了单井的注采气生产能力,加快了储气库的达容速度,丰富了水淹油气藏改建地下储气库的达容措施,进一步提高了储气库的管理水平,对我国储气库的生产运行管理具有一定的指导作用。     

北京琉璃渠村公共空间浅析

门头沟区作为北京的西部屏障,历史悠久,＂京西古驿道＂从该区穿过,依托古驿道形成了很多极具历史文化与艺术价值的古村落。琉璃渠村于2007年被评为＂中国历史文化名村＂。该文旨在通过相关文献的查阅及实地调研测绘等方法研究北京琉璃渠村公共空间构成要素及公共空间形态的特征,同时通过对相关资料的整理及研究来发掘古村落的历史与科学价值,探索人的行为活动与村落空间之间的互动关系。     

The architecture of hydroxy‐functionalized aPS‐b‐random copolymer‐b‐PE via one‐pot strategy combining living free radical polymerization with coordination polymerization

The copolymerization of styrene with ethylene was promoted by CpTiCl₃/BDGE/Zn/MAO catalyst system combining free radical polymerization with coordination polymerization via sequential monomer addition strategy in one‐pot. The effect of polymerization conditions such as temperature, time, ethylene pressure, and Al/Ti molar ratio on the polymerization performance was investigated. The hydroxy‐functionalized aPS‐b‐random copolymer‐b‐PE triblock copolymer was obtained by solvent extraction and determined by GPC, DSC, WAXD, and ¹³C‐NMR. The DSC result indicated that the aPS‐b‐random copolymer‐b‐PE had a T_g at 87°C and a T_m at 119°C which attributed to the T_g of aPS segment and the T_m of PE segment, respectively. The microstructure of the hydroxy‐functionalized aPS‐b‐random copolymer‐b‐PE was further confirmed by WAXD, ¹³C‐NMR, and ¹H‐NMR analysis; and these results demonstrated that the obtained block copolymer consisted of aPS segment, S‐E random copolymer segment, and crystalline PE segment. The connection polymerization of the hydroxy‐functionalized aPS with random copolymer‐b‐PE was revealed by GPC results. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

二阶线性非散度型抛物方程解的局部正则性估计

发展了Acerbi等的方法,得到了一类具有小BMO系数的二阶线性非散度型抛物方程解的二阶偏导数在Orlicz空间中的局部正则性估计.这种正则性估计可以应用于W2P,1解的存在性问题.     

The effect of osmosis pretreatment on hot‐air drying and microwave drying characteristics of chili (Capsicum annuum L.) flesh

Chili flesh pretreated with or without osmotic dehydration (OD) was dried in the hot‐air drying (AD) oven at 50–80 °C or in the microwave drying (MD) oven at 60–180 W. Results showed that the samples osmotically treated in mixed solution (10% salt + 50% sucrose) had the best dehydration effect as compared with single salt or sugar solutions. During the drying process, osmotically treated samples had one falling‐rate period and their effective moisture diffusivities (D_eff) showed a rapidly linear increase with the decrease in moisture content, while directly drying samples showed a three‐phase falling‐rate period and their D_eff increased gradually at the initial period and then rapidly at the final period. When the moisture content decreased, the activation energy increased gradually; however, for AD after OD, it decreased. Among all the processes, MD at 60 W after OD presented the largest vitamin C retention rate and the best colour difference, needing less drying time.     

Synthesis of well‐defined comblike hydroxy‐functionalized atactic polystyrene promoted by metallocene/tin/poly(phenyl glycidyl ether)‐co‐formaldehyde

Well‐defined comblike atactic polystyrene functionalized with hydroxyl groups was synthesized via living/controlling radical polymerization promoted by metallocene complexes in the presence of poly(phenyl glycidyl ether)‐co‐formaldehyde as the initiator and Sn as a reducing agent. The effect of the polymerization conditions, such as the ratio of initiator to monomer, temperature, and polymerization time, and the structure of the metallocene complex on the polymerization process were investigated. The resulting polymers were characterized by gel permeation chromatography, multiangle laser light scattering, ¹H‐NMR, and ¹³C‐NMR. The results show that the polymer had a narrow molecular weight distribution in the range 1.1–1.4 and the number‐average molecular weight of the polymer linearly depended on the monomer conversion within the polymerization timescale, which confirmed that living radical polymerization characteristics prevailed in the polymerization process. Both the number of arms and the number of hydroxyl groups in each polymer molecule were about four, which suggested that they arose from the epoxy functional groups of the initiator. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010