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排序方式: 共有192条查询结果,搜索用时 31 毫秒
1.
Shelly Aggarwal Braineard Eladi Paul Amitava DasGupta Dhiman Chatterjee 《Microfluidics and nanofluidics》2017,21(1):2
In this paper, performance of piezoelectrically actuated pyramidal valveless micropumps is studied experimentally in detail. Valveless micropumps based on silicon and glass substrate are fabricated using MEMS technology. Two different sizes of micropumps having overall dimensions of 5 mm × 5 mm × 1 mm and 10 mm × 10 mm × 1 mm are fabricated and characterized. In the fabricated micropumps, the thickness of silicon diaphragm is <20 µm which gives the advantage of operating pump at low voltage with excellent stability and consistency. The performance of micropumps in terms of flowrate and backpressure is evaluated for a wide range of driving frequency and actuating voltages. The maximum flowrate of water in the 10-mm micropump is 355 µl/min and backpressure of 3.1 kPa at zero flowrate for an applied voltage of 80 V at frequency 1.05 kHz. The reported micropumps have low footprint, high flowrate and backpressure. Thus, these micropumps are especially suited for biological applications as these can withstand adequate amount of backpressure. Comparative study of the performance of these micropumps with those available in the literature brings out the efficacy of these micropumps. 相似文献
2.
Impett Emily A.; Gordon Amie M.; Kogan Aleksandr; Oveis Christopher; Gable Shelly L.; Keltner Dacher 《Canadian Metallurgical Quarterly》2010,99(6):948
In 2 daily experience studies and a laboratory study, the authors test predictions from approach-avoidance motivational theory to understand how dating couples can maintain feelings of relationship satisfaction in their daily lives and over the course of time. Approach goals were associated with increased relationship satisfaction on a daily basis and over time, particularly when both partners were high in approach goals. Avoidance goals were associated with decreases in relationship satisfaction over time, and people were particularly dissatisfied when they were involved with a partner with high avoidance goals. People high in approach goals and their partners were rated as relatively more satisfied and responsive to a partner's needs by outside observers in the lab, whereas people with high avoidance goals and their partners were rated as less satisfied and responsive. Positive emotions mediated the link between approach goals and daily satisfaction in both studies, and responsiveness to the partner's needs was an additional behavioral mechanism in Study 2. Implications of these findings for approach-avoidance motivational theory and for the maintenance of satisfying relationships over time are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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4.
The present paper discusses the role of cabs and the presence of other men in the cab in manufacturing respectability for
the unmarried women agents of call centers in India. The night shift, an intrinsic part of work, at call centers in India
demands mobility and access to public space during nights for its women employees. The paper elaborates how the relation between
gender and space is evolving in the backdrop of the presence of someone trusted, through a shift from private patriarchy to
public patriarchy for the women agents while accessing the public space. The paper is based on a total of sixty-one qualitative
interviews conducted with unmarried women call center employees and parents based in Gurgaon, India. 相似文献
5.
Shelly Hogan Hyun Chung Lei Zhang Jianrong Li Yongwoo Lee Yumin Dai Kequan Zhou 《Food chemistry》2010,118(2):208-214
An anthocyanin-rich extract, generated from açai (AEA), was investigated for its antioxidant properties and antiproliferative activity against C-6 rat brain glioma cells and MDA-468 human breast cancer cells. AEA has an ORAC value of 2589 μmoles trolox equivalents (TE)/g dried powder and a DPPH radical-scavenging activity of 1208 μmoles TE/g, suggesting that AEA is an exceptional source of natural antioxidants. In addition, AEA remarkably suppresses proliferation of C-6 rat brain glioma cells, but has no effect on the growth of MDA-468 human breast cancer cells. Further experiments demonstrated that the AEA treatment dose-dependently inhibited the growth of C-6 rat glioma cells with an IC50 of 121 μg/ml. The DNA ladder fragmentation results indicated that AEA induced apoptosis of C-6 rat brain glioma cells. To compare açai with other anthocyanin-rich extracts, a number of berry extracts, including blueberry, strawberry, raspberry, blackberry and wolfberry, were assessed for potential antiproliferative activity against C-6 rat brain glioma cells. However, none of them showed suppressing effect. The results suggest that the active antiproliferative constituents in AEA are unlikely to be anthocyanins normally found in common berries. 相似文献
6.
A novel technique based on fiber-optic evanescent-wave spectroscopy is proposed for the detection of bacterial activity in human saliva. The sensor determines th e specific concentration of Streptococcus mutans in saliva, which is a major causative factor in dental caries. In this design, one prepares the fiber-optic bacterial sensor by replacing a portion of the cladding region of a multimode fiber with a dye-encapsulated xerogel, using the solgel technique. The exponential decay of the evanescent wave at the core-cladding interface of a multimode fiber is utilized for the determination of bacterial activity in saliva. The acidogenic profile of Streptococcus mutans is estimated by use of evanescent-waveabsorption spectra at various levels of bacterial activity. 相似文献
7.
The measurement of minute samples is desirable in many areas of research and analysis, including biological, environmental, and forensic sciences. The use of manual solution direct deposition, combined with surface evaporation, is a very useful and convenient method for the transfer of many analytes to a spectroscopic sampling window. For Fourier transform infrared (FT-IR) spectrometric analysis, high quality attenuated total reflection (ATR) and transmission analyses are possible with suitable solution deposits. If the sample area is very small, placement of the analyte deposit on the active area of the sampling accessory must be done carefully. To achieve this, a novel direct deposition system has been developed. This system, a series of valves attached to a glass nebulizer, generates deposits that are reproducible, and placement of the deposits is precise. The valves allow the sample to be loaded, helium airflow to expel the sample, and the nebulizer to be cleaned after deposition. To help contain the sample to a small area once deposition has taken place, a vacuum line is attached to the nebulizer. This simple semiautomated deposition system allows for higher sensitivity and run-to-run reproducibility for minute sample analysis. 相似文献
8.
Interoperation and information sharing among databases independently developed and maintained by different organizations is today a pressing need, if not a practice. Governmental, military, financial, medical, and private institutions are more and more required to become part of a distributed infrastructure and selectively share their data with other organizations. This sharing process inevitably opens the local system to new vulnerabilities and enlarges the space of possible threats to the data and resources it maintains. As a complicating factor, in general, data sources are heterogeneous both in the data models they adopt and in the security models by which protection requirements are stated. We present a modeling and architectural solution to the problem of providing interoperation while preserving autonomy and security of the local sources based on the use of wrappers and a mediator. A wrapper associated with each source provides a uniform data interface and a mapping between the source's security lattice and other lattices. The mediator processes global access requests by interfacing applications and data sources. The combination of wrappers and mediator thus provides a uniform data model interface and allows the mapping between restrictions stated by the different security policies. We describe the practical application of these ideas to the problem of trusted interoperation of health care databases, targeted to enforcing security in distributed applications referring to independent heterogeneous sources protected by mandatory policy restrictions. We describe the architecture and operation of the system developed, and describe the tasks of the different components. 相似文献
9.
María E. Len-Ríos Shelly Rodgers Esther Thorson Doyle Yoon 《The Journal of communication》2005,55(1):152-168
This study uses a feminist framework of masculine cultural hegemony to examine the representation of women in two newspapers—a medium-sized newspaper (Study 1) and a larger newspaper (Study 2). Surveys gauged news staff and news reader perceptions of female representation in news content to determine if perceptions matched content-analysis findings. Content-analysis results revealed a greater proportion of males than females in both content and photos for both studies. Female staffers were more likely than their male counterparts to perceive this disparity, and news readers perceived an even greater disparity than the news staff. News staffs were less likely to perceive disparities in the editorial, travel, and entertainment sections. We discuss the findings in relation to cultural hegemony and the representation of women in the news. 相似文献
10.
In Experiment 1, male and female subjects were given an opportunity to snack as they participated in a "get-acquainted study" with a same-sex or opposite-sex partner (confederate) whose social desirability was manipulated. Consistent with the hypothesis that women may eat less when motivated to present themselves in a feminine light, female subjects ate significantly less with a desirable male partner than in the remaining three conditions. In contrast, male subjects did not eat more (or less) with a desirable woman, although they did show an overall tendency to eat less with female (vs. male) partners. In Experiment 2, female subjects snacked as they got acquainted with a desirable male partner (confederate). Before this interaction, subjects received feedback indicating that they had either very masculine or very feminine interests. In addition, subjects believed either that their male partner was aware of their gender feedback or that he was unaware. Consistent with predictions derived from Schlenker's (1982) analytic-identity theory of social conduct, subjects in the partner-aware conditions ate less when they had received masculine (vs. feminine) feedback, whereas subjects in the partner-unaware conditions ate less when they had received feminine (vs. masculine) feedback. Implications for understanding eating disorders such as anorexia and bulimia are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献