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1.
Stefanie Demming Gena Peterat Andreu Llobera Hannah Schmolke Alexander Bruns Michael Kohlstedt Ala‘aldeen Al-Halhouli Claus-Peter Klages Rainer Krull Stephanus Büttgenbach 《Biomicrofluidics》2012,6(3)
This paper presents a vertically positioned microfluidic system made of poly(dimethylsiloxane) (PDMS) and glass, which can be applied as a microbubble column (μBC) for biotechnological screening in suspension. In this μBC, microbubbles are produced in a cultivation chamber through an integrated nozzle structure. Thus, homogeneous suspension of biomass is achieved in the cultivation chamber without requiring additional mixing elements. Moreover, blockage due to produced carbon dioxide by the microorganisms—a problem predominant in common, horizontally positioned microbioreactors (MBRs)—is avoided, as the gas bubbles are released by buoyancy at the upper part of the microsystem. The patterned PDMS layer is based on an optimized two-lithographic process. Since the naturally hydrophobic PDMS causes problems for the sufficient production of microbubbles, a method based on polyelectrolyte multilayers is applied in order to allow continuous hydrophilization of the already bonded PDMS-glass-system. The μBC comprises various microelements, including stabilization of temperature, control of continuous bubble formation, and two optical configurations for measurement of optical density with two different sensitivities. In addition, the simple and robust application and handling of the μBC is achieved via a custom-made modular plug-in adapter. To validate the scalability from laboratory scale to microscale, and thus to demonstrate the successful application of the μBC as a screening instrument, a batch cultivation of Saccharomyces cerevisiae is performed in the μBC and compared to shake flask cultivation. Monitoring of the biomass growth in the μBC with the integrated online analytics resulted in a specific growth rate of 0.32 h−1, which is almost identical to the one achieved in the shake flask cultivation (0.31 h−1). Therefore, the validity of the μBC as an alternative screening tool compared to other conventional laboratory scale systems in bioprocess development is proven. In addition, vertically positioned microbioreactors show high potential in comparison to conventional screening tools, since they allow for high density of integrated online analytics and therefore minimize time and cost for screening and guarantee improved control and analysis of cultivation parameters. 相似文献
2.
Microbial fermentation process development is pursuing a high production yield. This requires a high throughput screening and optimization of the microbial strains, which is nowadays commonly achieved by applying slow and labor-intensive submerged cultivation in shake flasks or microtiter plates. These methods are also limited towards end-point measurements, low analytical data output, and control over the fermentation process. These drawbacks could be overcome by means of scaled-down microfluidic microbioreactors (μBR) that allow for online control over cultivation data and automation, hence reducing cost and time. This review goes beyond previous work not only by providing a detailed update on the current μBR fabrication techniques but also the operation and control of μBRs is compared to large scale fermentation reactors. 相似文献
3.
Microfluidic technology provides precise, controlled-environment, cost-effective, compact, integrated, and high-throughput microsystems that are promising substitutes for conventional biological laboratory methods. In recent years, microfluidic cell culture devices have been used for applications such as tissue engineering, diagnostics, drug screening, immunology, cancer studies, stem cell proliferation and differentiation, and neurite guidance. Microfluidic technology allows dynamic cell culture in microperfusion systems to deliver continuous nutrient supplies for long term cell culture. It offers many opportunities to mimic the cell-cell and cell-extracellular matrix interactions of tissues by creating gradient concentrations of biochemical signals such as growth factors, chemokines, and hormones. Other applications of cell cultivation in microfluidic systems include high resolution cell patterning on a modified substrate with adhesive patterns and the reconstruction of complicated tissue architectures. In this review, recent advances in microfluidic platforms for cell culturing and proliferation, for both simple monolayer (2D) cell seeding processes and 3D configurations as accurate models of in vivo conditions, are examined. 相似文献
4.
近年来,随着我国教育改革的不断深化实践,教育也越来越重视对人的创新精神和创造能力的培养。独特的创新精神是推动一个人不断向前发展的动力,对于艺术设计行业而言,创新是成为一个合格的设计师必须要拥有的能力。本文基于当前艺术设计教育过程中对学生创新意识的培养情况,结合艺术设计对学生创新能力的培养要求,对艺术设计创新人才教育的培养模式进行深入的探讨。 相似文献
5.
Droplet-based microfluidic systems enable a variety of biomedical applications from point-of-care diagnostics with third world implications, to targeted therapeutics alongside medical ultrasound, to molecular screening and genetic testing. Though these systems maintain the key advantage of precise control of the size and composition of the droplet as compared to conventional methods of production, the low rates at which droplets are produced limits translation beyond the laboratory setting. As well, previous attempts to scale up shear-based microfluidic systems focused on increasing the volumetric throughput and formed large droplets, negating many practical applications of emulsions such as site-specific therapeutics. We present the operation of a parallel module with eight flow-focusing orifices in the dripping regime of droplet formation for the generation of uniform fine droplets at rates in the hundreds of kilohertz. Elevating the capillary number to access dripping, generation of monodisperse droplets of liquid perfluoropentane in the parallel module exceeded 3.69 × 105 droplets per second, or 1.33 × 109 droplets per hour, at a mean diameter of 9.8 μm. Our microfluidic method offers a novel means to amass uniform fine droplets in practical amounts, for instance, to satisfy clinical needs, with the potential for modification to form massive amounts of more complex droplets. 相似文献
6.
随着我国大学毕业生人数的不断增加,教育过度也日趋大众化。造成毕业生就业难的矛盾和原因很多,其问题的本质在于高等教育的人才培养模式如何与社会发展实现数量和规模上的匹配。为更好解释教育过度现象的症结点所在,本文将从劳动力区域分割角度、高校专业设置和层次结构以及文化角度方面来作详细说明。通过对原因的深层次分析,要解决大学毕业生就业难的问题就要合理设置高校内部的学科与专业,建立人才培养新机制;建立市场招聘信息互联共享机制和转变个人教育和就业观念,鼓励毕业生自主创业。 相似文献
7.
三本院校的培养方式一直在探讨摸索中前进,培养侧重于应用型教学,工学结合人才培养模式对于三本院校里土木工程专业人才的培养无疑是指明灯。而大项目教学法正是在工学教学模式的背景下提出的,是工学教学模式在土木工程专业上的具体应用,大项目教学法就是要突破传统的教学方法,以就业为导向,切实做到＂教、学、做＂三合一的教学应用模式。 相似文献
8.
微孢子虫孢子发芽机理 总被引：2，自引：0，他引：2
内部渗透压的升高是微孢子虫孢子发芽的直接驱动力，海藻糖酶催化海藻糖水解为葡萄糖或果糖是水生型微孢子虫孢子发芽的生化基础，PH值，离子种类及浓度、温度、射线等均能影响孢子发芽，陆栖型微孢子虫和水生型微孢子发芽过程中的糖代谢存在差异。 相似文献
9.
10.
贵州高职院校的办学宗旨是服务贵州地方经济社会的发展,其旅游专业人才培养的目标是服务地方旅游经济的发展。因此,贵州高职旅游专业的人才培养要从培养模式、课程体系、教学方法、实践训练、师资队伍、教学规模等方面进行改革,以满足商旅服务业的发展需求。 相似文献
11.
In vitro sensitivity testing of tumor cells could rationalize and improve the choice of chemotherapy and hormone therapy. In this report, a microfluidic device made from poly(dimethylsiloxane) and glass was developed for an assay of drug induced cytotoxicity. We evaluated the apoptotic and proliferation-inhibitory effects of anticancer drugs mitomycin C (MMC) and tamoxifen (TAM) using MCF-7 breast cancer cells. MMC and TAM both induced apoptosis and inhibited proliferation of MCF-7 cells in a concentration-dependent manner. MMC caused the expression of antiapoptotic protein Bcl-2 a dose-dependent reduction in MCF-7 cells. The expression of Bcl-2 did not change significantly in MCF-7 cells treated by TAM. The results in the microfluidic device were correlated well with the data obtained from the parallel experiments carried out in the conventional culture plates. The developed microfluidic device could be a potential useful tool for high content screening and high throughput screening research. 相似文献
12.
Mohsen JahangirianAuthor Vitae Tillal EldabiAuthor Vitae 《International Journal of Information Management》2011,31(3):234-243
While literature reviews with a large-scale scope are nowadays becoming a staple element of modern research practice, there are many challenges in taking on such an endeavour, yet little evidence of previous studies addressing these challenges exists. This paper introduces a practical and efficient review framework for extremely large corpora of literature, refined by five parallel implementations within a multi-disciplinary project aiming to map out the research and practice landscape of modelling, simulation, and management methods, spanning a variety of sectors of application where such methods have made a significant impact. Centred on searching and screening techniques along with the use of some emerging IT-assisted analytic and visualisation tools, the proposed framework consists of four key methodological elements to deal with the scale of the reviews, namely: (a) an incremental and iterative review structure, (b) a 3-stage screening phase including filtering, sampling and sifting, (c) use of visualisation tools, and (d) reference chasing (both forward and backward). Five parallel implementations of systematically conducted literature search and screening yielded a total initial search result of 146 087 papers, ultimately narrowed down to a final set of 1383 papers which was manageable within the limited time and other constraints of this research work. 相似文献
13.
柬埔寨可耕地资源丰富,温度适宜,水稻生产极具潜力。及时监测水稻种植时空格局对于区域水稻生产管理、灾害风险评估和粮食政策制定具有重要意义。传统的水稻遥感监测研究大多只提供年际尺度的水稻空间分布,缺乏年内尺度水稻种植与收获信息。本文首先利用一年内所有可获取的MODIS影像,构建基于像元的MODIS NDVI年时间序列曲线;然后,选取最大值、最小值、均值和标准差逐像元计算时序统计参数特征,采用FastDTW算法计算像元时序曲线与水稻参考时序曲线的相似性特征,将时序统计特征与时序曲线相似度特征相结合,利用随机森林分类器,通过机器学习进行监督分类,提取水稻熟制信息;最后,结合时序曲线提取水稻物候特征,生成水稻收获时间信息,并对水稻耕作类型进行识别。研究表明：①柬埔寨水稻种植主要集中在洞里萨湖周围的低地平原和南部的湄公河下游。尽管柬埔寨全年热量条件适宜,但水资源获取限制对柬埔寨水稻种植时空格局具有显著影响。②水稻熟制以单季稻为主,约占全年水稻种植面积的80%,且分布区域稳定;双季稻面积约占20%,年际种植空间分布变化较大。雨季稻是柬埔寨水稻的主要种植类型,种植面积约占全年水稻面积的70%左右,年际变化不大;旱季稻和前雨季稻面积约占30%,年际空间分布差异显著。③对2011年和2016年水稻种植模式分析可知,灌溉条件和洪水对柬埔寨水稻种植时空具有重要影响。本文通过对柬埔寨年内水稻种植时空格局的高精度监测,识别其主要影响因素,为制定因地制宜和有弹性的水稻种植制度、保障柬埔寨粮食安全提供借鉴。 相似文献
14.
中国东部地区春季降水与气温异常型的联合EOF分析 总被引：1，自引：0，他引：1
利用中国东部地区(100°E以东)140个气象观测站1951-2010年的逐月降水和地面气温资料,在去除气温的线性趋势的基础上采用联合EOF分析等方法,对春季(3-5月)的降水异常型和气温异常型之间的关系进行了诊断研究,结果表明:①在第一典型场(方差贡献率为28.13%)中,降水异常型态为南方型,存在3个暖异常区域:华北中部和北部的部分地区、陕西汉中地区以及西南地区;3个冷异常中心:一个位于长江以南地区,一个位于东北地区,一个位于西北地区的内蒙古西部。时间系数存在准3年、4~5年和8年尺度振荡周期;②在第二典型场(方差贡献率为16.57%)中,降水异常型态为中间型,气温异常偏高区基本位于南岭以南地区和西南地区的云南、贵州、四川,气温异常偏低区处在南岭以北地区。时间系数存在3年和18年为明显的时间振荡周期;③在第三典型场(方差贡献率为7.94%)中,降水异常型态近似表现为北方型,气温异常场,从南向北表现为“+-+”交替分布型。时间系数存在24~26年、4年为明显的时间振荡周期。通过3个模态的分析发现降水异常偏多与气温异常偏低、降水异常偏少与气温异常偏高的一致性特征在长江以南地区表现得尤为显著,当降水偏多时,云量增多,地表吸收的太阳辐射减少,再加上异常偏多的降水改变了地表的湿度(增大),进一步使地面放出的长波辐射相应减少,从而导致了地面气温降低。 相似文献
15.
《Information processing & management》2005,41(3):489-506
This paper presents a laboratory based evaluation study of cross-language information retrieval technologies, utilizing partially parallel test collections, NTCIR-2 (used together with NTCIR-1), where Japanese–English parallel document collections, parallel topic sets and their relevance judgments are available. These enable us to observe and compare monolingual retrieval processes in two languages as well as retrieval across languages. Our experiments focused on (1) the Rosetta stone question (whether a partially parallel collection helps in cross-language information access or not?) and (2) two aspects of retrieval difficulties namely “collection discrepancy” and “query discrepancy”. Japanese and English monolingual retrieval systems are combined by dictionary based query translation modules so that a symmetrical bilingual evaluation environment is implemented. 相似文献
16.
广东省重点实验室是广东省科技创新体系的重要组成部分,是广东省组织高水平基础研究和应用基础研究的核心力量。从科技资源配置的视角分析广东省重点实验室建设与发展过程中存在的定位与边界模糊、结构性布局失衡、资源配置方式不合理、绩效评价机制不健全、运行管理监督机制缺失等问题,进而从宏观(重点实验室的顶层设计)、中观(重点实验室的定位和布局)和微观(重点实验室的资源投入、绩效评价和日常运行管理)3个层次对广东省重点实验室的建设与发展进行系统的研究,并提出相应的政策建议。 相似文献
17.
Alician V. Quinlan 《Journal of The Franklin Institute》1980,310(6):325-342
Analysis of the thermal sensitivity of life processes governed by Michaelis-Menten kinetics shows that: (1) a one-parameter family of either isotherms or isoconcentrates is required to describe the thermal sensitivity of such processes; (2) rate maxima cannot exist unless a single parameter condition is satisfied and substrate concentration falls within a well-defined range; (3) optimum temparature increases asthe logarithm of substrate concentration and semi-log plots of optimum temperature (linear scale) versus substrate concentration (logarithmic scale) yield straight lines; (4) the maximum rate corresponding to the optimum temparature increases as substrate concentration raised to a power of value less than unity and log-log plots of maximum rate versus substrate concentration produce straight lines with less-than-unity slopes; and (5) the progression of optimum temperature and maximum rate with substrate concentration is parallel to the infinite-concentration isoconcentrate in semi-log plots, with rate plotted on the logarithmic scale and temperature on the linear scale. 相似文献
18.
菰黑粉菌科(Yeniaceae)的确认问题 总被引：2，自引：0，他引：2
余永年 《中国科学院研究生院学报》1974,12(3):317-328
菰黑粉菌科(Yeniaceae)是刘慎谔(1949)根据阎玫玉(1935)对菰黑粉菌(Yenia esculenta)
冬孢子**萌发方式的研究结果而建立的。但是20多年来,似还没有得到有关工作者的承认,
主要是由于黑粉菌冬孢子萌发方式受环境因素的影响很大,性状不太稳定的缘故。 为了确认
此科建立的必要性和合理性,在前人研究的基础上,对菰黑粉菌冬孢子的萌发方式和条件作了
进一步的研究。结果表明：菰黑粉菌冬孢子在形态上和生理上几乎同时成熟,孢子形成后便
可立即大量萌发。冬孢子的存活力较短暂,在室温下10个月完全丧失萌发力。
菰黑粉菌冬孢子在9-33℃下均能萌发,萌发的适温范围为24-30℃,30℃下8小时便
开始萌发。孢子在pH 2.0-11.0均能萌发,以pH3.5-7.0较好,最适pH为4.0-5.0。合
成培养基和植物性煎汁培养基有利于孢子的萌发,在动物性煎汁培养基和缺乏养料的蒸馏水
培养基上萌发较差。冬孢子在完全光照和完全黑暗下均能萌发。孢子萌发时对氧的需要量不
大,纯氧或过量的氧对萌发似有抑制作用。菰黑粉菌这种对萌发条件要求不严格的特性,表明
它具有广泛的适应性和顽强的生命力。这种特性是它在长期历史发展过程中所形成的,也是
长期人工选择和自然选择的结果。对这些生物学性状的了解,为在生产实践上争取茭白的丰
产奠定了理论基础。
温度、光照、氢离子浓度、营养条件和氧的供应,对菰黑粉菌冬孢子的萌发方式有一定的影
响,特别是对孢子原菌丝影响较大。但是对短的无隔担子原菌丝影响却不大,一般都没有引起
形态上的较大改变。刘慎谔(1949)根据这一性状所建立的菰黑粉菌属(Yenia)和菰黑粉菌科
(Yeniaceae),是有一定根据的,似应给予承认。 本文还对黑粉菌目的演化和分科问题进行了讨论。 相似文献
19.
Seeking potential toxic and side effects for clinically available drugs is considerably beneficial in pharmaceutical safety evaluation. In this article, the authors developed an integrated microfluidic array system for phenotype-based evaluation of toxic and teratogenic potentials of clinical drugs by using zebrafish (Danio rerio) embryos as organism models. The microfluidic chip consists of a concentration gradient generator from upstream and an array of open embryonic culture structures by offering continuous stimulation in gradients and providing guiding, cultivation and exposure to the embryos, respectively. The open culture reservoirs are amenable to long-term embryonic culturing. Gradient test substances were delivered in a continuous or a developmental stage-specific manner, to induce embryos to generate dynamic developmental toxicity and teratogenicity. Developmental toxicity of doxorubicin on zebrafish eggs were quantitatively assessed via heart rate, and teratological effects were characterized by pericardial impairment, tail fin, notochord, and SV-BA distance ∕body length. By scoring the teratogenic severity, we precisely evaluated the time- and dose-dependent damage on the chemical-exposed embryos. The simple and easily operated method presented herein demonstrates that zebrafish embryo-based pharmaceutic assessment could be performed using microfluidic systems and holds a great potential in high-throughput screening for new compounds at single animal resolution. 相似文献
20.
《Journal of The Franklin Institute》2022,359(2):1385-1402
The tracking problem of high-order nonlinear multi-agent systems (MAS) with uncertainty is solved by designing adaptive sliding mode control. During the tracking process, node failures are possible to occur, a new agent replaces the failed one. Firstly, a distributed nonsingular terminal sliding mode(NTSM) control scheme is designed for the tracking agents. A novel continuous function is designed in the NTSM to eliminate the singularity and meanwhile guarantee the estimation of finite convergence time. Secondly, the unknown uncertainties in the tracking agents are compensated by proposing an adaptive mechanism in the NTSM. The adaptive mechanism adjusts the control input through estimating the derivative bound of the unknown uncertainties dynamically. Thirdly, the tracking problem with node failures and agent replacements is further investigated. Based on the constructed impulsive-dependent Lyapunov function, it is proved that the overall system will track the target in finite time even with increase of jump errors. Finally, comparison simulations are conducted to illustrate the effectiveness of proposed adaptive nonsingular terminal sliding mode control method for tracking systems suffering node failures. 相似文献