Electrical power free, low dead volume, pressure-driven pumping for microfluidic applications     

Moscovici M  Chien WY  Abdelgawad M  Sun Y 《Biomicrofluidics》2010,4(4):46501

This paper presents a simple-to-construct, low dead volume pump capable of generating a wide range of positive and negative pressures for microfluidic applications. The pump generates pressure or vacuum by changing the volume of air confined inside a syringe and is able to generate pressures between -95 and +300 kPa with a resolution as high as 1 Pa. Different from syringe pumps and electrokinetic pumping, which are capable of controlling flow rates only, our pump can be used to generate constant flow rates or constant pressures, which are required for certain applications such as the aspiration of biological cells for biophysical characterization. Compared to syringe pumps, the new pump has almost zero dead volume and does not exhibit pulsatile flows. Additionally, the system does not require electrical power and is cost effective (～$100). To demonstrate the capabilities of the pump, we used it to aspirate osteoblasts (MC3T3-E1 cells) and to determine Young's modulus of the cells, to generate a concentration gradient, and to produce variable-sized droplets in microchannels using hydrodynamic focusing.  相似文献   

Effectiveness of antigraffiti treatments in connection with penetration depth determined by different techniques     

Paula María Carmona-Quiroga  Sagrario Martínez-Ramírez  Santiago Sánchez-Cortés  Mohamed Oujja  Marta Castillejo  María Teresa Blanco-Varela 《Journal of Cultural Heritage》2010,11(3):297-303

The elimination of spray paint using traditional (chemical and mechanical) methods inevitably entails altering surface characteristics. Hence, the impact and deterioration caused by graffiti in heritage buildings and monuments have led to the development and application of preventive systems in the form of antigraffiti coatings (which prevent paint from seeping into the pores of the surface material and facilitate cleaning). The effectiveness of two of these treatments, a commercial product (fluoroalkyl siloxane, protectosil, marketed by Degussa) and a hybrid organic-inorganic material (Ormosil), was evaluated in five construction materials (limestone, granite, cement mortar, lime mortar and brick), in terms of their penetration into the substrate. A number of techniques were used to determine the penetration depth (SEM/EDX, micro-Raman and LIBS), because a comparative analysis showed that none was universally valid for all types of treatments. The results show that the presence of the coating on the surface of less porous materials only ensures effective cleaning when the surface is fairly smooth. In granite, for instance, the CF₃ terminals in the fluorinated treatment hinder spray paint bonding more effectively than Ormosil, but not efficiently enough to ensure complete removal of the paint from granite surfaces.  相似文献   

Management of inclusive education in Oman: A framework for Action     

Mahmoud Mohamed Emam 《Support for Learning》2016,31(4):296-312

Inclusive education (IE) and the special education services related to it are relatively new in Oman. Efforts to manage special/inclusive education face many challenges due to a number of culturally rooted factors. Further, empirical research on IE in Oman is scarce and there is a need to advance IE discourse based on empirically validated perspectives. This article examines how IE is managed in schools from the perspective of school leaders in order to develop a framework for action. The author conducted a preliminary qualitative inquiry into how IE is understood and managed in Key stage 1 schools in Oman. The inquiry was based on a focus group interview with a cohort of 25 school leaders who were completing a two year bachelor in educational administration, an endorsement‐like programme at Sultan Qaboos University. Findings showed a number of challenges and tensions between theory and practice, highlighted by school leaders. These challenges and tensions were analysed in order to map out strengths and difficulties. A three level prism shaped framework for action was developed based on the analysis. The framework for action could potentially serve to guide policy‐ and decision‐makers, researchers, practitioners, and is advocated to develop a model of best practice for the successful implementation and management of IE in Oman.  相似文献   

Developing a road performance index using a Bayesian belief network model     

Mohamed A. Ismail  Hamid R. Soleymani 《Journal of The Franklin Institute》2011,348(9):2539-2555

There is a high demand to develop and incorporate decision support tools, by the transportation sectors and other concerned agencies, to improve their infrastructure assets management under shrinking budgets and increasing demands. This paper develops a proof-of-concept Bayesian belief network (BBN) model to rank roads in a network system based on several key performance indicators (KPI) using a probabilistic framework. For a given road network, the proposed tool is capable of ranking or prioritizing the segment of roads for high level management objectives. To demonstrate the application of the proposed model, various scenarios are elaborated and discussed in detail. Finally, the sensitivity analysis is carried out to evaluate the effects of different KPIs.  相似文献   

Parametrization of extended stabilizing controllers for continuous-time descriptor systems     

Yu Feng  Mohamed Yagoubi  Philippe Chevrel 《Journal of The Franklin Institute》2011,348(9):2633-2646

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The development of reading and spelling abilities in the first 3?years of learning Arabic     

Wessam Mohamed  Thomas Elbert  Karin Landerl 《Reading and writing》2011,24(9):1043-1060

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A multilevel model for effects of social capital and knowledge sharing in knowledge-intensive work teams     

Yan Yu  Jin-Xing Hao  Xiao-Ying Dong  Mohamed Khalifa 《International Journal of Information Management》2013

Although it is a widely held belief that social capital facilitates knowledge sharing among individuals, there is little research that has deeply investigated the impacts of social capital at different levels on an individual's knowledge sharing behavior. To address this research gap, this study combines a multilevel approach and an optimal network configuration view to investigate the multilevel effects of social capital on individuals’ knowledge sharing in knowledge intensive work teams. This study makes a distinction between the social capital at the team-level and that of social capital at the individual level to examine their cross-level and direct effects on an individual's sharing of explicit and tacit knowledge. A survey involving 343 participants in 47 knowledge-intensive teams was conducted for testing the multilevel model. The results reveal that social capital at both levels jointly influences an individual's explicit and tacit knowledge sharing. Further, when individuals possess a moderate betweenness centrality and the whole team holds a moderate network density, team members’ knowledge sharing can be maximized. These findings offer a more comprehensive and precise understanding of the multilevel impacts of social capital on team members’ knowledge sharing behavior, thus contributing to the social capital theory, as well as knowledge management research and practices.  相似文献   

Laser cleaning of terracotta decorations of the portal of Palos of the Cathedral of Seville     

Mohamed Oujja  Esther Rebollar  Marta Castillejo  Concepcin Domingo  Concepcin Cirujano  Fernando Guerra-Librero 《Journal of Cultural Heritage》2005,6(4):321-327

Laser cleaning has been used to restore the soiled terracotta statues and decorations of the tympanum of the portal of Palos of the Cathedral of Seville in Spain. A simultaneous laboratory study performed on a representative sample helped to identify the optimum laser conditions to remove the dark soiling layer produced by air pollution. It was found that irradiation at 1064 nm with a Q-switched Nd:YAG laser was more effective than the harmonic wavelengths of 532 or 266 nm. LIBS and Raman microscopy gave information on the composition of terracotta and identified the presence of a protective layer made of gypsum and calcite. As detected by Raman spectroscopy, laser irradiation caused the elimination of the carbon component of the soiling layer and the appearance of an anhydrite component in the laser irradiated gypsum layer applied over the terracotta substrate for protective purposes. Local heating of the surface caused by laser irradiation at 1064 nm, the laser wavelength used for restoration of the portal, might be responsible for a process of partial dehydration of gypsum into anhydrite.  相似文献   

The literacy campaign in rural Morocco: Drawing some lessons     

Mohamed Dardour 《Prospects》2000,30(1):125-142

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Towards a personality understanding of information technology students and their IT learning in UAE university     

Nabeel Al-Qirim  Kamel Rouibah  Ali Tarhini  Mohamed Adel Serhani  Aishah Rashid Yammahi  Maraim Ahmed Yammahi 《Education and Information Technologies》2018,23(1):29-40

This research investigates the personality characteristics of Information Technology students (CIT) in UAE University (UAEU) and how such features impact their IT learning. To achieve this objective, this research attempts to explain the impact of the Big-5 factors on learning using survey research. Results from 179 respondents suggested that agreeableness, extraversion, openness, and conscientiousness respectively were the most important strategies adopted by CIT students. However, neuroticism scored the lowest. Such results could be attributed to personal as well as to cultural reasons as highlighted in this research. The research highlights theoretical as well as professional contributions and implications. Some of challenges in this research could be addressed by designing programs aiming at enhancing student’s learning ability from the perspective of their personal traits.  相似文献