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11.
A microbubble-powered bioparticle actuator 总被引:4,自引:0,他引:4
Maxwell R.B. Gerhardt A.L. Toner M. Gray M.L. Schmidt M.A. 《Journal of microelectromechanical systems》2003,12(5):630-640
We present the results of a device that uses controllable microbubble actuation to manipulate bioparticles. In order to create a useful device for controlling the position of bioparticles, predictable microfluidic actuation is crucial. The goal of this project was to develop fundamental technology that can be used to manipulate single bioparticles (e.g., cells). We use a thermal bubble actuation method to accomplish this goal. Microbubbles have the advantages of relatively simple electronics and fabrication but can be difficult to control. In this paper, we describe two specific accomplishments: the use of micromachined nucleation cavities to precisely localize thermal bubbles and to achieve controllable bubble formation temperatures and bubble dissipation and the demonstration of controllable microbubbles in a new device for particle sorting. 相似文献
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Luteinizing hormone releasing hormone (LHRH) stimulates the development of cellular FSH immunoreactivity in the perinatal hamster adenohypophysis. Because neuropeptide Y (NPY) can act directly on rat adenohypophysial cells to stimulate FSH and LH release and potentiate the stimulatory effect of LHRH on FSH and LH release, we investigated the effects of NPY alone and in combination with a low, ineffective dose of LHRH on inducing cellular FSH immunoreactivity in the neonatal hamster adenohypophysis. Neonatal female pituitary glands were grafted beneath the right renal capsules of hypophysectomized-ovariectomized adult hamster hosts with a catheter implanted in the external jugular vein. After treatment, hosts were decapitated and graft tissue was stained for FSH and LH immunoreactivity. The mean percentage of adenohypophysial cells that stained for FSH was low (2.8%) in grafts in hosts infused continuously with heparinized saline vehicle for 7 days. In other hosts, peptides were pulsed through the catheter every 12 h for 7 days. The mean percentage of FSH cells also was low after pulsing 6 ng LHRH or 2 micrograms NPY but increased substantially when the two peptides were pulsed simultaneously. No differences in the mean percentage of LH cells existed between any of the groups. The results demonstrate that NPY and LHRH can synergize to induce cellular FSH immunoreactivity in the neonatal female hamster. 相似文献
15.
Two-dimensional map of Haemophilus influenzae following protein enrichment by heparin chromatography
M Fountoulakis H Langen S Evers C Gray B Takács 《Canadian Metallurgical Quarterly》1997,18(7):1193-1202
Two-dimensional gel electrophoresis separates several hundred protein molecules in one single experiment and is efficiently used to study the products expressed by different genomes. Low-copy-number gene products are invisible on a stained two-dimensional map and must be enriched such that sufficient amounts are present for visualization and identification. We investigated the enrichment of proteins of the bacterium Haemophilus influenzae by chromatography on immobilized heparin which has affinity for growth and protein biosynthesis factors. Total soluble proteins of the microorganism were fractionated on Heparin-Actigel which resulted in enrichment of approximately 160 proteins. The eluates, representing about 40% of the applied proteins, were analyzed by two-dimensional gel electrophoresis and the protein spots were characterized by amino acid composition analysis and matrix-assisted laser desorption ionization mass spectrometry. The proteins enriched by chromatography on the heparin gel were not exclusively low-copy-number gene products and they did not exclusively belong to one single class of proteins. The proteins that bound to the heparin gel are indicated in a two-dimensional protein map which includes more than 110 newly identified proteins. 相似文献
16.
Examines, in the context of cancer illness, S. E. Taylor and J. D. Brown's (see record 1988-16903-001) claim that mental health is to a degree predicated on illusory beliefs about the self, one's control, and the future. The Heroic Model (HM), a stance toward cancer characterized by belief that positive thoughts and feelings, a fighting spirit, and an optimistic outlook will promote cancer remission, is presented as paradigmatic of Taylor and Brown's thesis. Strong and weak formulations of the HM (the former affirming a direct influence of mental states over physical processes, and the latter affirming indirect effects only) are examined with respect to their potential adaptive value as true or false beliefs, with different consequences for well-being. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
17.
DA Gray 《Canadian Metallurgical Quarterly》1997,54(6):1553-1562
This study demonstrates that invertebrate acoustic signals can provide information about male phenotypic attributes, and that females can use this acoustic information in mate choice to select a phenotypically superior mate. I investigated the relationships between a male acoustic sexual signal, the phenotype of the signaller, and the female response to signal variation. I recorded and analysed the calling songs of male house crickets, Acheta domesticus. The analyses showed that chirps convey information about male size. With the exception of amplitude, the mean number of pulses per chirp was the best predictor of male size. I performed a laboratory tape-playback experiment to determine female preference during phonotaxis. Females preferred tapes playing the chirps of large males, specifically chirps with a greater number of pulses per chirp. Selection on the female preference is discussed.Copyright 1997 The Association for the Study of Animal Behaviour 相似文献
18.
We have isolated a putative serine/threonine receptor kinase gene with an expression pattern indicating that it may play a role in the stylar response to pollination. Differential display PCR was used to select tobacco mRNAs with increased accumulation following pollination. NTS16, a cDNA identified by this method, is homologous to a ca. 2.4 kb mRNA primarily expressed in pistil tissues. Levels of this mRNA increase during floral development and are further increased by pollination reaching maximal accumulation 12-18 hours after pollination and then declining. mRNA levels can also be increased by the application of ethylene to unpollinated flowers. A polypeptide encoded by the NTS 16 open reading frame has sequence similarity to the catalytic domain of several receptor protein kinases from plants including the S-receptor kinases implicated in the rejection of self-pollen in Brassica species and the Pto gene product of tomato which confers resistance to a bacterial pathogen. 相似文献
19.
A variant of the boundary element method, called the boundary contour method (BCM), offers a further reduction in dimensionality.
Consequently, boundary contour analysis of two-dimensional (2-D) problems does not require any numerical integration at all.
While the method has enjoyed many successful applications in linear elasticity, the above advantage has not been exploited
for Stokes flow problems and incompressible media. In order to extend the BCM to these materials, this paper presents a development
of the method based on the equations of Stokes flow and its 2-D kernel tensors. Potential functions are derived for quadratic
boundary elements. Numerical solutions for some well-known examples are compared with the analytical ones to validate the
development.
Received 28 August 2001 / Accepted 15 January 2002 相似文献
20.
H Langen C Gray D R?der JF Juranville B Takacs M Fountoulakis 《Canadian Metallurgical Quarterly》1997,18(7):1184-1192
High-resolution two-dimensional (2-D) polyacrylamide gel electrophoresis allows the separation of complex biological mixtures (i.e., several hundred proteins from a bacterial cell lysate) in a single experiment. In this report proteins from Haemophilus influenzae were separated by 2-D gels and analyzed by peptide mass fingerprinting and/or amino acid analysis. By comparing the peptide mass profiles and the amino acid composition with the Haemophilus influenzae database, 119 protein spots were identified. The combination of amino acid analysis and peptide mass fingerprinting is a powerful tool for a rapid and economical identification of a large number of proteins resolved by 2-D gels. Studies on gene regulation and changes of protein expression upon drug treatment require quick and serial analysis techniques to efficiently identify potential new drug targets. 相似文献