Microfluidic device capable of medium recirculation for non-adherent cell culture

We present a microfluidic device designed for maintenance and culture of non-adherent mammalian cells, which enables both recirculation and refreshing of medium, as well as easy harvesting of cells from the device. We demonstrate fabrication of a novel microfluidic device utilizing Braille perfusion for peristaltic fluid flow to enable switching between recirculation and refresh flow modes. Utilizing fluid flow simulations and the human promyelocytic leukemia cell line, HL-60, non-adherent cells, we demonstrate the utility of this RECIR-REFRESH device. With computer simulations, we profiled fluid flow and concentration gradients of autocrine factors and found that the geometry of the cell culture well plays a key role in cell entrapping and retaining autocrine and soluble factors. We subjected HL-60 cells, in the device, to a treatment regimen of 1.25% dimethylsulfoxide, every other day, to provoke differentiation and measured subsequent expression of CD11b on day 2 and day 4 and tumor necrosis factor-alpha (TNF-α) on day 4. Our findings display perfusion sensitive CD11b expression, but not TNF-α build-up, by day 4 of culture, with a 1:1 ratio of recirculation to refresh flow yielding the greatest increase in CD11b levels. RECIR-REFRESH facilitates programmable levels of cell differentiation in a HL-60 non-adherent cell population and can be expanded to other types of non-adherent cells such as hematopoietic stem cells.     

Development of flow through dielectrophoresis microfluidic chips for biofuel production: Sorting and detection of microalgae with different lipid contents

In this study, a continuous flow dielectrophoresis (DEP) microfluidic chip was fabricated and utilized to sort out the microalgae (C. vulgaris) with different lipid contents. The proposed separation scheme is to allow that the microalgae with different lipid contents experience different negative or no DEP force at the separation electrode pair under the pressure-driven flow. The microalgae that experience stronger negative DEP will be directed to the side channel while those experience less negative or no DEP force will pass through the separation electrode pair to remain in the main channel. It was found that the higher the lipid content inside the microalgae, the higher the crossover frequency. Separation of the microalgae with 13% and 21% lipid contents, and 24% and 30%–35% lipid contents was achieved at the operating frequency 7 MHz, and 10 MHz, respectively. Moreover, separation can be further verified by measurement of the fluorescence intensity of the neutral lipid inside the sorted algal cells.     

我国小麦族的形态演化与分类、分布的研究

本文以演化形态为基础，结合地理分布和生境条件，研究了中国小麦族的分类和属   间的亲缘关系。 小麦族的穗状花序可认为由雀麦族的圆锥花序和短柄草族的总状花序演化而来，演化路 线可归纳为：1．圆锥花序的各级花序柄缩短直接形成圆锥穗状花序，具不定数小穗或假单生小穗，其颖与外稃的中线及小穗轴不在同一面上。2．圆锥花序简化为总状花序后小穗柄再缩短，形成简单穗状花序，具真单生小穗，其颖、稃的中线与小穗轴处于同一面上。 3．聚伞圆锥花序简缩为聚伞穗状花序，具三联小穗，其居中小穗的颖位于外稃的背面，侧小穗的颖位于外稃 的侧面。据此，根据小麦族颖、外稃的形态和其它性状、生境、分布，国产的和引种的小麦族植物可分为13个属(赖草属、披碱草属、鹅观草属、偃麦草属、山羊草属、小麦属、冰草属、旱麦草属、黑麦属、簇毛麦属、新麦草属、大麦属和猬草属)，本文主要讨论了它们之间的亲缘关系。     

Decentralized adaptive tracking quantized control for interconnected pure feedback time delay nonlinear systems

This paper focuses on the problem of adaptive tracking quantized control for a class of interconnected pure feedback time delay nonlinear systems. To satisfy the requirement of prescribed performance on the output tracking error, a novel asymmetric tangent barrier Lyapunov function is developed. The decentralized adaptive controller is designed via backstepping method. To deal with the uncertain interconnected nonlinear functions, we design a new virtual control input in the first step. Instead of estimating the bound of each unknown function, we use the adaptive method to estimate the bound of the composite function which is composed of the unknown functions. Thus the over parameterization problem is avoided. It is proved that the output of each subsystem satisfies the prescribed performance requirement and other state variables are bounded. Finally, the simulations are performed and the results verify the effectiveness of the proposed method.     

Relationships Among Teachers’ Positive Discipline,Students’ Well-being and Teachers’ Effective Teaching: A Study of Special Education Teachers and Adolescent Students With Learning Disabilities in Taiwan

The authors proposed a positive discipline, well-being and teaching effectiveness model that suggested that teachers’ positive discipline would facilitate students’ well-being and effective teaching, and students’ well-being would play a mediating role in the association between positive discipline and teaching effectiveness. The model was tested by including 255 resource room teachers (mean age = 32.71 years, SD = 7.09) and 255 matched adolescent students with learning disabilities (mean age = 14.06 years, SD = .74). Teachers responded to a scale for rating positive discipline strategies, and adolescents completed a students’ well-being questionnaire and a students’ awareness of teachers’ teaching effectiveness questionnaire. To evaluate the fit between the collected data and the proposed model, structural equation modelling was used to analyse the data. The results supported the proposed model and revealed that the link between teachers’ repertoire of positive discipline strategies and their students’ perception of teaching effectiveness was partially mediated by students’ well-being. Thus, the authors suggest that instead of eliminating individual student misbehaviours, teachers should focus more on positive classroom management, which is linked to improved outcomes for students and teachers.     

太阳轮刚度对行星机构浮动量影响规律的研究

目的:以某2K-H型行星齿轮机构为研究对象,建立行星齿轮机构的力学模型并推导其运动微分方程.方法:参照该行星齿轮机构给定的基本参数,研究太阳轮支撑刚度对行星轮系中心件的浮动量的影响.结果:通过数值仿真计算发现太阳轮支撑刚度对太阳轮浮动量有显著影响.太阳轮的的浮动量会随着太阳轮支撑刚度的减小会明显增大.结论:对2K-H型行星齿轮机构的动态优化设计.     

中国针茅属分类、分布和生态的初步研究

 24 species and 4 varietes of genus Stipa L. of China have been studied and des- cribed in this paper.  It has been noted that  these  different  species  have various geographical distributions, depending on the changes of climatic and edaphic factors of their environments.  Based on the study of floral morphology together with ecolo- gical and distributional factors, the genus have been divided into 5 sections: 1.  Sect. Regelia Tzvel. 2. Sect. Leiostipa Dum. 3. Sect. Barbatae Junge 4. Sect. Stipa 5. Sect. Smirnovia Tzvel.       It should be pointed out that the section Regelia as well as two members of sec- tion Barbatae, S. purpurea and S. roborowskyi, belong to frigori-xerophilous ecotype, distributing over Qinghai-Xizang Plateau above the forest line.  The section Leiostipa belongs to euxerophilous and mesoxerophilous ecotype, distributing widely in north- west, southwest, northeast and east and extends to the forest-steppe vegetational Zone of China.  The section Smirnovia and other two members  of section Barbatae,  S. breviflora and S. orientalis, belong to euxerophilous ecotype, with the latitudinal dis- tribution as far as Nei-Mongo and the yellow soil plateau, with the altitudinal distribu- tion as far as the desert steppe of Sinkang and Qinghai-Xizang plateau.  The section Stipa belongs to euxerophilous ecotype, only distributes to the  mountain steppe  of north Xingkang and the last, section Barbatae is an artificial group having plumes overof the awn only, and its four species have already been mentioned above.     

Student involvement in assessment: a project designed to assess class participation fairly and reliably

This article describes a project designed to ensure that class participation in a large introductory commercial law course is assessed fairly and reliably. The subjectivity often associated with this type of assessment is minimized by involving students in the specification of clear criteria and the assessment process as they were asked to assess themselves and their peers. Formative feedback is given mid‐way through the semester so that students have the opportunity to take remedial measures where necessary and teachers can reinforce positive behaviour. The data are analyzed to determine the relationships between the assessments given by the students, their peers and tutors. There is evidence of some gender bias in Week 13 that is not consistent with the final marks. Finally, the combining of the individual assessment of the criteria is shown to be a good estimate of the final class participation mark given by the tutors and the students.     

论高校校园文化育人功能的实效性途径

校园文化建设作为高校大学生教育的有效载体,是高校全面育人不可或缺的重要环节,其＂软约束性＂的教育引导功能日益凸显,研究、分析校园文化育人所面临的新问题、新情况,构建与时俱进、满足师生需求文化育人的实效性途径。这不仅具有理论的探讨意义,更具有现实的实践意义。     

Senegalese Art in U.S. Schools: Transporting Contemporary African Diaspora with Decolonized Perspectives

Abstract

This article investigates the ways in which global art making and cultural practices have been conveyed in U.S. schools and considers questions about how art education can engage in decolonization. This special issue's theme of Diversity, Globalization, and Education is approached through the window of visual art by examining the work of three contemporary Senegalese artists and one U.S. artist in the sociopolitical contexts of history and current events, and asserting ways in which curriculum in U.S. schools may be considered with a decolonizing lens by integrating the artists’ perspectives.