排序方式： 共有95条查询结果，搜索用时 656 毫秒
31.
Mohammad Sadegh Cheri Hamidreza Shahraki Jalal Sadeghi Mohammadreza Salehi Moghaddam Hamid Latifi 《Biomicrofluidics》2014,8(5)
Measurement and control of pressure-driven flow (PDF) has a great potential to enhance the performance of chemical and biological experiments in Lab on a Chip technology. In this paper, we present an optofluidic flow sensor for real-time measurement and control of PDF. The optofluidic flow sensor consists of an on-chip micro Venturi and two optical Fabry-Pérot (FP) interferometers. Flow rate was measured from the fringe shift of FP interferometers resulted from movement fluid in the on-chip micro Venturi. The experimental results show that the optofluidic flow sensor has a minimum detectable flow change of 5 nl/min that is suitable for real time monitoring and control of fluids in many chemical and biological experiments. A Finite Element Method is used to solve the three dimensional (3D) Navier–Stokes and continuity equations to validate the experimental results. 相似文献
32.
Jing-qing Liu Zhi-feng Luo Ke Liu Yi-fu Zhang Hong-xi Peng Bao-lan Hu Hong-xing Ren Xiao-yan Zhou Shang-de Qiu Xiao-fang He Ping Ye Hamid Bastani Li-ping Lou 《浙江大学学报(A卷英文版)》2017,18(4):313-328
Biofilm detachment caused by flushing can result in secondary contamination in drinking water distribution systems (DWDSs). To evaluate the impact of flushing on biofilm detachment, actual water supply pipes including ductile cast iron pipes (DCIPs), gray cast iron pipes (GCIPs), and stainless steel compound pipes (SSCPs) were used in this study. Real-time quantitative polymerase chain reaction and 454 pyrosequencing were used to quantify bacteria and analyse microbial community composition, respectively. The results showed that the pipe material greatly influences the resistance of a biofilm to flushing. Biofilms attached to DCIPs were able to resist quite strong flushing, while those attached to GCIPs and SSCPs were sensitive to flushing. Both flush-resistant and flush-sensitive bacteria were present in all the biofilms, but their frequency differed among the different metal pipes. Thus, the resistance to flushing of bacteria is related not only to the nature of the bacteria, but also to the pipe material. Although flushing can remove some of the biofilm and may be a good way to clean the DWDS, the shear stress needed to remove the biofilm differs among different pipe types. The results of this study provide technical support for the management and operation of DWDS. 相似文献
33.
Lin Tang Wei-jun Luo Zhen-li He Hanumanth Kumar Gurajala Yasir Hamid Kiran Yasmin Khan Xiao-e Yang 《Journal of Zhejiang University. Science. B》2018,19(2):147-158
Vegetables are important constituents of the human diet. Heavy metals and nitrate are among the major contaminants of vegetables. Consumption of vegetables and fruits with accumulated heavy metals and nitrate has the potential to damage different body organs leading to unwanted effects. Breeding vegetables with low heavy metal and nitrate contaminants is a cost-effective approach. We investigated 38 water spinach genotypes for low Cd and nitrate co-accumulation. Four genotypes, i.e. JXDY, GZQL, XGDB, and B888, were found to have low co-accumulation of Cd (<0.71 mg/kg dry weight) and nitrate (<3100 mg/kg fresh weight) in the edible parts when grown in soils with moderate contamination of both Cd (1.10 mg/kg) and nitrate (235.2 mg/kg). These genotypes should be appropriate with minimized risk to humans who consume them. The Cd levels in the edible parts of water spinach were positively correlated with the concentration of Pb or Zn, but Cd, Pb, or Zn was negatively correlated with P concentration. These results indicate that these three heavy metals may be absorbed into the plant in similar proportions or in combination, minimizing the influx to aerial parts. Increasing P fertilizer application rates appears to prevent heavy metal and nitrate translocation to shoot tissues and the edible parts of water spinach on co-contaminated soils. 相似文献
34.
David NICHOLAS Ian ROWLANDS Anthony WATKINSON David BROWN Hamid R. JAMALI 《Learned Publishing》2012,25(3):195-206
Digital repositories have been with us for more than a decade, and despite the considerable media and conference attention they engender, we know very little about their use by academics. This paper sets out to address this by reporting on how well they are used, what they are used for, what researchers' think of them, and where they thought they were going. Nearly 1,700 scientific researchers, mostly physical scientists, responded to an international survey of digital repositories, making it the largest survey of its kind. High deposit rates were found and mandates appear to be working, especially with younger researchers. Repositories have made significant inroads in terms of impact and use despite, in the case of institutional repositories, the very limited resources deployed. Subject repositories, like arXiv and PubMed Central, have certainly come of age but institutional repositories probably have not come of age yet although there are drivers in place which, in theory anyway, are moving them towards early adulthood. 相似文献
35.
Hamid Sadeghi 《Interactive Learning Environments》2016,24(3):382-395
Group formation task as a starting point for computer-supported collaborative learning plays a key role in achieving pedagogical goals. Various approaches have been reported in the literature to address this problem, but none have offered an optimal solution. In this research, an online learning environment was modeled as a weighted undirected complete graph in which each learner was implied as a node and the relationship between them was denoted as a weighted arc. The weight of each link indicated the similarity degree between the corresponding individuals. The similarity between two students was measured as the mean of their absolute interest levels. The graph was also represented through a symmetric adjacency matrix. Then, a novel binary integer programming formulation was proposed to model the group formation problem and optimally assign each learner to the most appropriate group. The method was utilized to divide an online class of 32 learners into 8 groups of size 4. Findings indicated that the suggested model was successful in optimally solving the problem in 20.53 seconds, on average. The performance of the method was also compared with a modified version of K-means clustering algorithm. Although, the running time of the suggested technique was not as good as the clustering algorithm, it generated better outcomes in theory and in practice. 相似文献
36.
ABSTRACTHafez’s tomb was constructed on the grave of the well-known Iranian poet in Shiraz, in the 1930s. The dome of this monument is made of copper metal and has been exposed to the urban environment for 80 years. In this study, corrosion mechanisms and conservation conditions of the metallic dome of the Hafez’s tomb are investigated by analytical methods including optical microscopy, ICP-MS, SEM-EDX, and X-ray diffraction. The results showed that the dome is constructed from many copper sheets that are hammered to shape the dome. The corrosion products formed on the surface of copper sheets include copper oxide and copper trihydroxichlorides. In fact, the corrosion mechanism occurring in the metallic dome consists of copper oxidation and redeposition of copper II products because of reaction with air pollutants. 相似文献
37.
Hamid R. Ekbia 《The Information Society》2013,29(2):121-122
Abstract The U.S. Department of Agriculture has been mandated to “acquire and diffuse among the people of the United States useful information on subjects connected with agriculture in the most general and comprehensive sense of that word. …” With this authority the department has taken advantage of continuing advances of communications and computer technologies by initiating several programs related to the electronic dissemination of agricultural information. For example, the Foreign Agricultural Service has begun testing the release of agricultural trade leads through the University of Nebraska's AGNET computer‐based network. The Agricultural Marketing Service disseminates updated market data on more than 150 farm commodities over its leased wire market news network; the system has 140 terminals linked by some 14,500 miles of leased wires. Additional projects described in the article include a pilot project to deliver market news information to farmers via public television, programs testing the electronic marketing of livestock, and the electronic mail network operated by the department's Office of Governmental and Public Affairs. 相似文献
38.
Emey Suhana Mohd Azamai Suhaniza Sulaiman Shafina Hanim Mohd Habib Mee Lee Looi Srijit Das Nor Aini Abdul Hamid Wan Zurinah Wan Ngah Yasmin Anum Mohd Yusof 《Journal of Zhejiang University. Science. B》2009,10(1):14-21
Chlorella vulgaris (CV) has been reported to have antioxidant and anticancer properties. We evaluated the effect of CV on apoptotic regulator
protein expression in liver cancer-induced rats. Male Wistar rats (200∼250 g) were divided into eight groups: control group
(normal diet), CDE group (choline deficient diet supplemented with ethionine in drinking water to induce hepatocarcinogenesis),
CV groups with three different doses of CV (50, 150, and 300 mg/kg body weight), and CDE groups treated with different doses
of CV (50, 150, and 300 mg/kg body weight). Rats were sacrificed at various weeks and liver tissues were embedded in paraffin
blocks for immunohistochemistry studies. CV, at increasing doses, decreased the expression of anti-apoptotic protein, Bcl-2,
but increased the expression of pro-apoptotic protein, caspase 8, in CDE rats, which was correlated with decreased hepatoctyes
proliferation and increased apoptosis as determined by bromodeoxy-uridine (BrdU) labeling and terminal deoxynucleotidyl transferase
mediated dUTP nick-end labeling (TUNEL) assay, respectively. Our study shows that CV has definite chemopreventive effect by
inducing apoptosis via decreasing the expression of Bcl-2 and increasing the expression of caspase 8 in hepatocarcinogenesis-induced
rats.
Project supported by Department of Biochemistry, Faculty of Medicine, UKM Medical Center, Universiti Kebangsaan Malaysia,
and the Malaysian Ministry of Science and Technological Innovation (MOSTI) 相似文献
39.
40.
This article investigates the e-print depositing behavior of physicists and astronomers. Fifty-six PhD students and staff at the Department of Physics and Astronomy at the University College London were interviewed. A survey was also carried out (47.1% response rate). The study investigates the relation between variables such as research area, type of research (theoretical, experimental and so on), and the amount of reading on the patterns of e-print depositing. The findings showed that clear intradisciplinary differences exist among different subfields of physics and astronomy. 相似文献