Adsorption of methylene blue onto activated carbon produced from tea (Camellia sinensis L.) seed shells: kinetics, equilibrium, and thermodynamics studies

Tea (Camellia sinensis L.) seed shells, the main byproduct of the manufacture of tea seed oil, were used as precursors for the preparation of tea activated carbon (TAC) in the present study. A high yield (44.1%) of TAC was obtained from tea seed shells via a one-step chemical method using ZnCl₂ as an agent. The Brunauer-Emmett-Teller (BET) surface area and the total pore volumes of the obtained TAC were found to be 1 530.67 mg²/g and 0.782 6 cm³/g, respectively. The equilibrium adsorption results were complied with Langmuir isotherm model and its maximum monolayer adsorption capacity was 324.7 mg/g for methylene blue. Adsorption kinetics studies indicated that the pseudo-second-order model yielded the best fit for the kinetic data. An intraparticle diffusion model suggested that the intraparticle diffusion was not the only rate-controlling step. Thermodynamics studies revealed the spontaneous and exothermic nature of the sorption process. These results indicate that tea seed shells could be utilized as a renewable resource to develop activated carbon which is a potential adsorbent for methylene blue.     

Focusing-enhanced mixing in microfluidic channels

A focusing-based microfluidic mixer was studied. The micromixer utilizes the focusing process required for cytometry to reduce the diffusion distance of molecules to be mixed in order to facilitate the passive diffusion-controlled mixing process. It was found that both the high flow rate ratio of the sheath flow to the flows to be mixed and the low flow rate of the mixing fluids resulted in the short mixing length required within the microfluidic channel. It was shown that a complete mixing was achieved within a distance of 4 mm in the micromixer for the focused mixing fluids at a flow rate of 2 μl∕min and a flow rate ratio of the sheath flow to the flows to be mixed at 4:1. The mixer described here is simple and can be easily fabricated and controlled.     

高强度的环境规制能够促进国内大气科技创新吗？——以〖SO〗_2排放控制技术为例

从理论上来说,波特弱假说涉及双重外部性问题,即大气污染的负外部性和技术创新的正外部性,环境规制和知识产权保护合力才能予以切实彻底解决,而后者并没有得到普遍重视。本文认为,波特弱假说需要考虑知识产权保护强度。以SO_2排放控制技术为例,本文运采用2000-2013年省际省份面板数据,结合固定效应模型进行实证研究检验了知识产权保护对于波特弱假说的作用。结果发现,当知识产权保护较弱时,环境规制对大气科技创新具有呈现负向影响;。只有当知识产权保护较强时力度超过一定阈值时,环境规制才会对大气科技创新产生正向影响,波特弱假说成立。此外,环境规制和知识产权保护影响大气科技创新的交叉效应主要出现在企业,而非科研院所和个人,创新主体存在明显的差异性。     

企业技术创新在世界科技强国建设中的地位和作用

2016年5月30日,习近平总书记作了"为建设世界科技强国而奋斗"的重要讲话,在新中国成立100年时使我国成为世界科技强国。之后,引起社会各界热烈讨论,为了实现这一战略目标,企业必须把技术创新放在长远发展的头等重要位置。在发展过程中,腾讯公司始终把技术创新放在第一位,并采取了一系列举措,取得了一定成效。文章最后从企业角度提出了加快世界科技强国建设的几点建议。     

项目型组织成员知识转移动机实证研究—与组织情境的跨层次作用

知识是项目型组织(project-based organizations,PBOs)持续发展的关键资源,其有效地转移和共享不但有助于项目的成功,更有利于PBOs的长远发展。本研究运用多层线性模型,通过采集和分析来自中国建筑第*工程局有限公司的480个项目型组织样本问卷数据,探讨组织情景对项目型组织成员知识转移动机和知识转移效果的跨层次影响。结果表明:知识转移动机是决定知识转移行为的关键所在;组织情境差异化影响成员的知识转移动机和知识转移效果。这一发现揭示了组织情景影响成员知识动机和知识转移效果的内在机理,拓展了主流文献的相关研究,并为项目型组织知识管理实践提供借鉴。     

科研信息化发展态势和思考

文章分析了科研信息化发展态势,认为当前科研信息化发展将进入第三阶段即"一体化"阶段,并将发展态势凝练为"五新":大数据驱动科研范式变革成为"新亮点",开放科学借力科研信息化成为"新趋势",科研移动应用成为科研创新的"新动力",科研信息化基础设施性能及规模加速发展和升级成为"新常态",科研信息化推动企业创新和产学研协同创新成为"新模式"。指出了我国在科研信息化基础设施与应用领域面临的挑战;介绍了中科院在科研信息化基础设施、科学大数据、科研信息化应用3个方面的发展部署;提出了针对我国科研信息化的发展建议,包括建立国家科研信息化发展体系,实施国家级科研信息化工程,建设面向全国科技界提供科技资源和信息化资源的综合服务平台等。     

Stability analysis for switched genetic regulatory networks: An average dwell time approach

In this correspondence, the problem of exponential stability for switched genetic regulatory networks (GRNs) with time delays is investigated. The GRNs are composed of N modes and the network switches from one mode to another. By employing the piecewise Lyapunov functional method combined with the average dwell time approach and by using a novel Lyapunov–Krasovskii functional (LKF), sufficient criteria are given to ensure the exponential stability for the switched GRNs with constant and time-varying delays, respectively. These criteria are proved to be much less conservative than the most recent results, since the results reported in this paper not only depend on the delay bounds, but also depend on the partitioning. All the conditions presented here are in the form of matrix inequalities which are easy to be verified via the Matlab toolbox. Two examples are provided in the end of this paper to illustrate the effectiveness of the obtained theoretical results.     

重庆第三产业R&D投入产出效应的实证研究

本文构建了二级三要素CES生产函数,把要素投入分为R&D投入与非R&D投入两个部分,计算了重庆第三产业五个主要行业的R&D投入与非R&D投入的替代弹性和产出弹性。研究发现这些行业目前都处于规模报酬递增阶段,人力投入与资本投入之间的替代弹性平均约为1,R&D资本投入替代弹性比R&D人力投入替代弹性小,非R&D投入的产出弹性高于R&D投入的产出弹性。最后根据研究结论提出了对策建议。     

露天矿高边坡爆破振动监测与衰减规律分析

露天矿山爆破开采过程中会产生一系列的危害,严重威胁地表建筑物及人员的安全.通过现场实时监测采集了露天矿山远距离建筑物的质点振动速度及主振频率,并且根据萨道夫斯基公式对监测结果进行线性回归,推导出爆破振动波的衰减规律.试验结果表明:爆破振动质点振速与爆心距有关,随着爆心距的增大,质点振动速度逐渐减小;质点振动的三向振速中,水平径向振速最大;监测点的峰值振速均在安全允许范围之内,一般情况下对周围建筑物没有影响;爆破地震波衰减系数K=248.05,α=1.52,即爆破振动质点振速衰减规律公式为:V=248.05(3√Q/R)1.52.爆破振动监测结果和衰减规律对类似地形和地质的露天矿爆破开采具有一定的参考价值.     

名词复数拼法问题

根据词汇学基础理论,英语词汇中名词复数的拼法由于历史原因以及拼读体系与拼写体系的差异,使得名词复数形式的拼读与拼写不尽相同,这给学习名词单复数形式转换带来了一定的困难。本文拟介绍一些可以借鉴的常见复数拼法规则,以便有助于大家学习与实践。