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A variety of methods have been used to introduce chemicals into a stream or to mix two or more streams of different compositions using microfluidic devices. In the following paper, the introduction of cryoprotective agents (CPAs) used during cryopreservation of cells in order to protect them from freezing injuries and increase viability post thaw is described. Dimethylsulphoxide (DMSO) is the most commonly used CPA. We aim to optimize the operating conditions of a two-stream microfluidic device to introduce a 10% vol/vol solution of DMSO into a cell suspension. Transport behavior of DMSO between two streams in the device has been experimentally characterized for a spectrum of flow conditions (0.7 < Re < 10), varying initial donor stream concentrations, (1% vol/vol < Co < 15% vol/vol) and different flow rate fractions (0.23 < fq < 0.77). The outlet cell stream concentration is analyzed for two different flow configurations: one with the cell stream flowing on top of the DMSO-rich donor stream, and the other with the cell stream flowing beneath the heavy DMSO-laden stream. We establish a transition from a diffusive mode of mass transfer to gravity-influenced convective currents for Atwood numbers (At) in the range of (1.7 × 10−3 < At < 3.1 × 10−3) for the latter configuration. Flow visualization with cells further our understanding of the effect of At on the nature of mass transport. Cell motion studies performed with Jurkat cells confirm a high cell recovery from the device while underscoring the need to collect both the streams at the outlet of the device and suggesting flow conditions that will help us achieve the target DMSO outlet concentration for clinical scale flow rates of the cell suspension. 相似文献
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Prasheeda Chandran Pradeep Garg Chandra S. Pundir 《Indian journal of clinical biochemistry : IJCB》2005,20(2):81-85
Total cholesterol, total bilirubin, calcium, oxalate, inorganic phosphate, magnesium, iron, copper, sodium and potassium were
analyzed quantitatively in gallstones, bile of gall bladder and sera of 200 patients of cholelithiasis (52 cholesterol, 76
mixed and 72 pigment stone patients) and their contents were correlated between calculi and bile and sera and bile in these
three type of stone patients. A significant positive correlation was observed between total cholesterol, total bilirubin of
calculi and bile, copper of bile and sera of cholesterol stone patients, copper of calculi and bile, total bilirubin, oxalate,
magnesium, potassium of sera and bile of pigment stone patients and oxalate and iron of stone and bile, total bilirubin, oxalate,
sodium of sera and bile of mixed stone patients. A significant negative correlation was found between magnesium of serum and
bile of cholesterol stone patients, oxalate of calculi and bile of pigment stone patients and magnesium of serum and bile
of mixed stone patients. 相似文献
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Recent research on the benefits of entrepreneurship education has tended to ignore or “control out” possible demographic differences in outcomes for entrepreneurship graduates. This paper examines demographic differences in the perceived benefits of different components of entrepreneurship education programmes (EEPs), entrepreneurial cognitions and entrepreneurial intentions of EEP graduates. Data were collected by questionnaire from 348 university EEP graduates in Pakistan. All graduates had strong positive attitudes to becoming entrepreneurs and no demographic differences in entrepreneurial intentions were observed. Nonetheless, females in particular, and graduates with no work experience to a lesser extent, exited the EEPs with lower perceived benefits, particularly in terms of inspiration, and slightly weaker perceived control for entrepreneurship, than males and graduates with some experience. No substantial differences were associated with age or entrepreneurial family background. The authors suggest ways in which EEPs can be more inclusive of female students. 相似文献
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M. D. Subash Chandran 《Resonance》1996,1(11):69-75
A beautiful monocarpic palm of the Western Ghats, talipot which through the ages played a silent role in the culture, economy and ecology especially of the west coast of South India, is facing an uncertain future mainly due to negligence. Much could be done to bring back this palm from obscurity into the mainstream of conservation. 相似文献
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INFLUENCE OF PERCEIVED CONTROL OVER TIME ON COLLEGE STUDENTS' STRESS AND STRESS-RELATED OUTCOMES 总被引：2，自引：0，他引：2
Nonis Sarath A. Hudson Gail I. Logan Laddie B. Ford Charles W. 《Research in higher education》1998,39(5):587-605
Assertions that time management results in less stress, healthier employees, and more effective organizations have received little empirical examination. This study investigates the influence of perceived time management (operationalized as perceived control over time) as a stress coping strategy among college students. Also, the influence of perceived time management on valued student outcomes such as academic performance, problem-solving ability, and health are also investigated. Results from a sample of 164 college students found low levels of stress and high levels of academic performance, problem-solving ability, and health for students that perceived high levels of perceived control over time compared to students who perceived low control over time. Discussion of the study findings, implications, and direction for future research is presented. 相似文献
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