Study on surface properties of PDMS microfluidic chips treated with albumin     

Walter Schrott  Zdeněk Slouka  Petr ?ervenka  Ji?í Ston  Marek Nebyla  Michal P?ibyl  Dalimil ?nita 《Biomicrofluidics》2009,3(4)

Electrokinetic properties and morphology of PDMS microfluidic chips intended for bioassays are studied. The chips are fabricated by a casting method followed by polymerization bonding. Microchannels are coated with 1% solution of bovine serum albumin (BSA) in Tris buffer. Albumin passively adsorbs on the PDMS surface. Electrokinetic characteristics (electro-osmotic velocity, electro-osmotic mobility, and zeta potential) of the coated PDMS channels are experimentally determined as functions of the electric field strength and the characteristic electrolyte concentration. Atomic force microscopy (AFM) analysis of the surface reveals a “peak and ridge” structure of the protein layer and an imperfect substrate coating. On the basis of the AFM observation, several topologies of the BSA-PDMS surface are proposed. A nonslip mathematical model of the electro-osmotic flow is then numerically analyzed. It is found that the electrokinetic characteristics computed for a channel with the homogeneous distribution of a fixed electric charge do not fit the experimental data. Heterogeneous distribution of the fixed electric charge and the surface roughness is thus taken into account. When a flat PDMS surface with electric charge heterogeneities is considered, the numerical results are in very good agreement with our experimental data. An optimization analysis finally allowed the determination of the surface concentration of the electric charge and the degree of the PDMS surface coating. The obtained findings can be important for correct prediction and possibly for robust control of behavior of electrically driven PDMS microfluidic chips. The proposed method of the electro-osmotic flow analysis at surfaces with a heterogeneous distribution of the surface electric charge can also be exploited in the interpretation of experimental studies dealing with protein-solid phase interactions or substrate coatings.  相似文献   

工业革命4.0给科技伦理带来的风险与挑战     

Michal  Val?o邢建华 《福建工程学院学报》2019,(5):458-462

2010年以来,以信息化、智能化、物理、数字和生物等领域新技术融合为标志的工业革命4.0,给社会生产生活带来巨大变化和新的机遇,同时,也使人类陷入前所未有的新的伦理困境。工业革命4.0有其深刻的历史根源,西方主要学术流派对工业革命4.0带来的科技伦理风险进行了反思,并提出了有代表性的观点。在此基础上,系统梳理了全球化时代工业革命4.0的科技进步带来的伦理挑战,探讨了新时代科技与工程教育的新视角、新观点与新方法。  相似文献   

Caregivers’ use of metacognitive language in child care centers: Prevalence and predictors   总被引：1，自引：0，他引：1  

Kristen L. Frampton  Michal Perlman  Jennifer M. Jenkins 《Early childhood research quarterly》2009,24(3):248-262

Use of metacognitive language by child care center staff in classrooms that serve preschool-aged children was examined. Staff's use of mental-state talk, perspective-taking talk, and activity-relevant questioning with children were coded in a series of 20-s snapshots taken over the course of one full morning per classroom. A total of 3401 snapshots were observed for 393 teachers in 103 classrooms. Staff used mental-state talk in 22% of the snapshots, activity-relevant questions in 12%, and perspective-taking talk in 3%. Structural and process predictors of staff's metacognitive language were examined for full-time staff (n = 148 in 95 classrooms) using multilevel modeling and ordinary least squares regression. Caregiver positive interaction style predicted caregivers’ engagement in all three types of language. Caregiver punitive interaction style was also a positive predictor of caregivers’ talk about others’ perspectives. In general, structural characteristics of the classroom were not significant predictors of staff's language. However, the proportion of children receiving a child care subsidy in the center negatively predicted perspective-taking discourse. Results indicate the importance of caregiver relational style in providing a more discourse-rich child care context.  相似文献   

The Concept of Nondeterminism: Its Development and Implications for Teaching     

Michal Armoni  Mordechai Ben-Ari 《Science & Education》2009,18(8):1005-1030

Nondeterminism is a fundamental concept in computer science that appears in various contexts such as automata theory, algorithms and concurrent computation. We present a taxonomy of the different ways that nondeterminism can be defined and used; the categories of the taxonomy are domain, nature, implementation, consistency, execution and semantics. An historical survey shows how the concept was developed from its inception by Rabin & Scott, Floyd and Dijkstra, as well as the interplay between nondeterminism and concurrency. Computer science textbooks and pedagogical software are surveyed to determine how they present the concept; the results show that the treatment of nondeterminism is generally fragmentary and unsystematic. We conclude that the teaching of nondeterminism must be integrated through the computer science curriculum so that students learn to see nondeterminism both in terms of abstract mathematical entities and in terms of machines whose execution is unpredictable.

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Michal Armoni (Corresponding author)Email:

Mordechai Ben-AriEmail:

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Michal Armoni   is a postdoctoral fellow at the Department of Science Teaching of the Weizmann Institute of Science. She received her PhD in science teaching from the Tel Aviv University, and her BA and MSc in computer science from the Technion. Her research interests are in the teaching and learning processes in computer science, in particular of fundamental concepts such as reduction and nondeterminism. She is currently on leave from the computer science department of the Open University of Israel. She has extensive experience in developing learning materials in computer science and in teaching the subjects at all levels from high school through graduate students. Mordechai Ben-Ari   is an associate professor in the Department of Science Teaching of the Weizmann Institute of Science. He holds a PhD in mathematics and computer science from the Tel Aviv University. In 2004, he received the ACM/SIGCSE Award for Outstanding Contributions to Computer Science Education. He is the author of numerous computer science textbooks and of Just a Theory: Exploring the Nature of Science (Prometheus 2005). His research interests include the use of visualization in teaching computer science, the pedagogy of concurrent and distributed computation, the application of theories of education to computer science education and the nature of science.  相似文献   

Peer relations of infants and toddlers     

Alice Sterling Honig  Carl DiPerna 《Early Childhood Education Journal》1983,10(3):36-39

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Does entrepreneurship education matter? Business students’ perspectives     

Egerová  Dana  Eger  Ludvík  Mičík  Michal 《Tertiary Education and Management》2017,23(4):319-333

The paper presents the findings of a mixed-methods study investigating the perceptions of business students in the Czech Republic towards entrepreneurship education, and examining the factors influencing their level of intention to be entrepreneurs. The results indicate that family background significantly influences the student’s entrepreneurial intention, and that participation in entrepreneurship-oriented courses positively influences the student’s level of self-efficacy. The study revealed further that business education had some effect on the student’s ability to gain the necessary knowledge for entrepreneurship. Another key finding was that entrepreneurship education specifically for business students has to equip students with entrepreneurial skills, attributes and behaviours. The results also suggest that entrepreneurship education is a contextually determined concept which requires modification of content and methods to meet the specific needs of particular target groups. The study has important implications for higher education institutions in terms of designing and managing effective entrepreneurship education.  相似文献   

Children at risk for learning disorders: multiple perspectives     

Al-Yagon M 《Journal of learning disabilities》2003,36(4):318-335

This study examined the contribution of a multidimensional model of risk factors in explaining adaptive functioning among 5- to 6.5-year-old kindergartners with mild developmental delays who were considered at risk for developing learning disorders. Risk factors included (a) child characteristics, (b) maternal and familial ecological variables, and (c) the child's attachment style as perceived by the mother. The sample included 145 Israeli mother-child dyads: 70 mothers and their children at risk for developing learning disorders (51 boys, 19 girls) and 75 mothers and their typically developing children (46 boys, 29 girls) from the same general education kindergartens. Data were collected from children's self-reports, mothers' narratives, and teachers' ratings. Path analysis examined the multidimensional risk model for the two groups. The study indicated a high fit between the theoretical model and the empirical findings and showed a different pattern of relations between the model's components for the two populations studied.  相似文献   

Dissociations between serial position and number of letters effects in lateralised visual word recognition     

Michal Lavidor  Peter J. Bailey 《Journal of Research in Reading》2005,28(3):258-273

Some previous studies of visual word recognition have reported an interaction between visual field and word length (measured by number of letters), such that recognition is affected more by word length for words presented in the left than for words presented in the right visual field. However, when manipulating serial position of letters in words to measure length effects, there are also reports of symmetrical word length effects in the two visual fields. Here we report two experiments, presenting four‐ and seven‐letter words, suggesting that the serial position and length effects in the hemispheres are separable and task dependent. For tasks that rely more heavily on letter‐level processing such as letter search (Experiment 1), performance in both hemifields showed similar effects of serial position; however, when comparing four‐ and seven‐letter words, an effect of word length was evident only in the left visual field, in line with the well‐established interaction between word length and hemifield. An interaction between word length and hemifield was confirmed for the same stimuli when they were employed in a lexical decision task, which forced whole‐word processing (Experiment 2). We conclude that the effects of serial position and number of letters in the two visual fields are separable, and are selectively affected by task type.  相似文献   

Toilet learning     

Alice Sterling Honig 《Early Childhood Education Journal》1993,21(1):6-9

AitAlice Sterling Honig is Professor of Child Development at Syracuse University and Research Review editor for Day Care and Early Education.Dr. Honig is the author of Playtime Learning Games for Young Children,editor of Risk Factors in Infancy,and coauthor of Infant Caregiving: A Design for Training.  相似文献   

Discrimination of relative numerosity by pigeons     

W. K. Honig  Karen E. Stewart 《Learning & behavior》1989,17(2):134-146

In three experiments, pigeons were trained to discriminate between uniform arrays of two elements that differed in color, form, or size. They were then tested with arrays that contained different proportions of the two elements on these dimensions. In all cases, orderly discrimination gradients reflected these proportions. The discrimination readily transferred to new arrays with similar stimuli, but with different total numbers of elements. In Experiment 4, the pigeons were taught to discriminate between two groups of categorical stimuli: pictures of birds and pictures of flowers. A test with different proportions of each again produced a gradient based on relative numerosity. Experiment 5 demonstrated transfer of stimulus control on the numerosity dimension when pigeons were trained with one set of instances from two categories, and then were tested with new instances from the same categories.  相似文献