不变形双滴的热毛细迁移及相互作用

对微重力下不变形双滴的非定常热毛细迁移运动进行了数值模拟,采用了有限差分方法对动量方程和能量方程进行离散,使用波前追踪法捕捉运动的不变形液滴界面.研究显示双滴的排列方式对它们的迁移规律和相互作用影响很大,其中影响任一个液滴运动的最主要的因素是另一个液滴的存在所引起的温度场的扰动

Plant-mediated synthesis of silver nanoparticles and application in antibacterial fabric

纳米银是以纳米技术为基础研制而成的新型抗菌产品,由于量子效应和尺寸效应具有普通银系抗菌剂无法比拟的抗菌效果。本研究以黄芩、丁香、洋浦桃、芳樟4种植物质提取液制备银纳米颗粒,并借助于uV-VIS、TEM以及Xrd对产物进行表征,结果表明增加植物质提取液浓度或增大nA OH加入量,均有利于制得粒径较小的银纳米颗粒。SEM图片表明采用浸渍法可将所得纳米银颗粒负载于纯棉织物上,通过考察浸渍时间、温度、浴比对织物上载银量的影响,确定较优的浸渍条件为时间30 H,温度55℃,浴比为1:25。分别考察了银纳米颗粒粒径和植物质种类对所得载银织物抗菌性能的影响,发现负载到织物上的纳米银粒径越小,织物抑菌效果越好;利用本身具有抑菌效果的黄芩、丁香来制备银纳米颗粒,有利于增强所得载银织物的整体抗菌性能;4种植物质中以黄芩制得的载银织物抗菌效果最优,对金黄色葡萄球菌、大肠杆菌等实验菌株均有强烈的抑制作用。Nano silver, based on the nanoscience and nanotechnology, exhibits excellent antibacterial ability due to the quantum effect and size effect.In this work, the plant-mediated synthesis of silver nanoparticles(Ag NPs) was reported from four plants, including Scutellaria baicalensis, Syzygium aromaticum, Syzygium samarangense and Cinnamomum camphora.The as-synthesized Ag NPs were characterized by UV-Vis, TEM and XRD techniques.The results indicated that the Ag NPs tended to be smaller with the increase of biomass concentration or Na OH adding amounts.SEM images verified that the Ag NPs can be loaded onto cotton fabric through impregnation, and the optimal conditions were time of 30 h, temperature of 55℃ and liquor ratio of 1:25.Furthermore, the effects of Ag NPs size and plant species on the antibacterial ability of the resulting Ag-coated fabrics were investigated, respectively.Ag NPs loaded on the fabrics with smaller size displaied superior antibacterial activity against Escherichia coli.Moreover, Ag-coated fabrics prepared from Scutellaria baicalensis and Syzygium aromaticum extracts, which possessed own antibacterial ability, showed the cooperative antibacterial effect between biomass and nano-silver.The as-prepared fabric by the extract of Scutellaria baicalensis exhibited the best antibacterial ability with high inhibition ratio against various bacteria such as Staphylococcus aureus and Escherichia coli.国家自然科学基金项目(21206140); 厦门市科技计划项目(3502Z20133006)~

微波辅助萃取-大孔树脂分离纯化芳樟叶黄酮

为了综合利用芳樟叶精油提取过程中产生的大量残渣,该文利用微波辅助萃取和大孔树脂选择性吸附来分离纯化芳樟叶黄酮。采用L9(34)正交试验,考察了萃取剂、微波辐射功率、辐射时间及料液比对黄酮得率的影响,确定了微波辅助萃取的优化工艺条件:以60%乙醇做萃取剂,微波功率320W,间歇辐射2次,每次1min,料液质量体积比1:12,在此条件下,芳樟叶黄酮的提取得率为2.97%,与乙醇热回流提取方法相比,得率提高了6.83%,时间缩短了98.89%;为进一步纯化萃取所得的黄酮提取物,选择6种大孔吸附树脂,测定芳樟叶黄酮在树脂上的吸附量和解吸率,筛选出了吸附剂HPD-450,其对芳樟叶黄酮有较好的静态吸附和解吸效果。经装填有大孔树脂HPD-450的固定床纯化后黄酮纯度由22.49%提高到51.28%,纯化倍数2.3倍

Numerical simulations on thermocapillary migrations of nondeformable droplets with large Marangoni numbers

In this paper, the study on isolated spherical drops in thermocapillary migrations in zero gravity is carried out with a novel numerical scheme to accomplish long-tank simulations in a very short computing domain, and the full migrating phenomena with fairly large Marangoni numbers (up to 400) are discussed in detail. Larger Marangoni numbers lead to more complicated migrating processes, and longer distances for the drops to reach their final stable migrating velocities (U-F). There is nontrivial difference between the U-F values in theoretical analysis, numerical simulations, and space experiments, and the most possible reason is the assumed different migrating distances to reach steady states in different investigations

Stabilization of anti-aromatic and strained five-membered rings with a transition metal

1981年诺贝尔化学奖获得者、美国康奈尔大学RoaldHoffmann教授评价该项工作说：'The　paper is an excellent one--it's　quite a mazing that the parent Os　system,molecule 1,chooses to give the osmapentalyne'。德国化学家Uwe Rosenthal教授等在同期《自然—化学》杂志的《News and Views》栏目以《Breaking the rules》为题撰文评述了这一研究成果。全文地址：http://www.nature.com/nchem/journal/vaop/ncurrent/pdf/nchem.1702.pdfAnti-aromatic compounds, as well as small cyclic alkynes or carbynes, are particularly challenging synthetic goals. The combination of their destabilizing features hinders attempts to prepare molecules such as pentalyne, an 8π-electron anti-aromatic bicycle with extremely high ring strain. Here we describe the facile synthesis of osmapentalyne derivatives that are thermally viable, despite containing the smallest angles observed so far at a carbyne carbon. The compounds are characterized using X-ray crystallography, and their computed energies and magnetic properties reveal aromatic character. Hence, the incorporation of the osmium centre not only reduces the ring strain of the parent pentalyne, but also converts its Hückel anti-aromaticity into Craig-type Möbius aromaticity in the metallapentalynes. The concept of aromaticity is thus extended to five-membered rings containing a metal–carbon triple bond. Moreover, these metal–aromatic compounds exhibit unusual optical effects such as near-infrared photoluminescence with particularly large Stokes shifts, long lifetimes and aggregation enhancement

《四元玉鉴》校改札记

朱世杰《四元玉鉴》是中国传统数学的杰作之一。清代数学家沈钦裴、罗士琳（1789-1853年）、戴煦（1805-1860年）分别为之补演细草。其中，罗士琳《四元玉鉴细草》三卷（1835年）影响最大。文章依据罗草逐题演算，指出《四元玉鉴》原文尚有十一题存在失校、误校及存疑等问题，同时参考沈草、戴草予以校改和说明，并对卷下之六的五个题目的校改，提出新的意见

《四元玉鉴》校改札记

朱世杰《四元玉鉴》是中国传统数学的杰作之一。清代数学家沈钦裴、罗士琳（1789-1853年）、戴煦（1805-1860年）分别为之补演细草。其中，罗士琳《四元玉鉴细草》三卷（1835年）影响最大。文章依据罗草逐题演算，指出《四元玉鉴》原文尚有十一题存在失校、误校及存疑等问题，同时参考沈草、戴草予以校改和说明，并对卷下之六的五个题目的校改，提出新的意见

城郊观光农业生态旅游发展研究——以新疆独山子观光农业园区为例

旅游业的蓬勃发展为农业资源开发利用带来了新的机遇,观光农业是一种以农业为载体的新兴生态旅游业。观光农业是城市化、工业化的产物,它的出现拓展了旅游业的发展空间,对区域农业经济的发展具有很强的推动作用,具有广阔的发展前景。阐述了观光农业的内涵及其国内外发展概况,并以新疆独山子观光农业园区为例,在分析其发展条件的基础上,依据可持续发展原则探讨了观光农业园区生态旅游的发展思路与开发内容,进而提出了若干对策建议

专业化城市的工业旅游开发研究——以独山子为例

工业旅游作为新兴的旅游产品,具有观赏性、知识性、参与性和趣味性等多种特点和优势,正以其独特的魅力,发展成为重要的旅游方式,具有广阔的发展前景,近几年逐步成为一个新的开发热点。专业化城市是我国数量众多的一类城市群体,其工业旅游开发的主要特征是工业与其所在的城市融为一体,形成典型的工业和城市复合型旅游产品。本文以独山子为例,通过对其工业旅游开发条件、现状及存在问题的分析,从开发思路、旅游产品、宣传促销、企业与政府间合作等方面探讨了这类城市的工业旅游开发策略

忆峥嵘岁月 探学史新元——李兆华教授访谈录

作为我国著名数学史家,李兆华教授追忆了从小学到研究生阶段的求学经历,回顾了1978年以来从事中国数学史研究的情况,讲述了在天津师范大学创办数学史学科的往事与中国数学史研究心得.这篇访谈录展现了一位数学史家在社会变迁中的成长历程与他的学术成就、治学思想,反映了他对天津师范大学数学系发展与数学史人才培养做出的贡献