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101.
Electrokinetic geosynthetics in hydraulic applications 总被引:3,自引:0,他引:3
In use most geosynthetics play a passive role. New applications for geosynthetics have been identified if they can provide an active role, initiating biological, chemical or physical change to the matrix in which it is installed as well as providing the established functions. This can be achieved by combining the electrokinetic phenomena of electro-osmosis, electrophoresis and associated electrokinetic functions such as electrolysis with the traditional functions of geosynthetics of drainage, filtration, containment and reinforcement to form electokinetic geosynthetics (EKG). Electrokinetic geosynthetics can be made singly or from combinations of woven, non-woven, needle punched knitted, extruded or laminated materials and can be formed in any 2D or 3D shape.The majority of the uses of EKG are in hydraulic applications or applications with a significant hydraulic component. These can be grouped in separate engineering categories such as civil, mining, and water engineering. The concept of electrokinetic geosynthetics is described and details of applications and case studies are provided in the paper. 相似文献
102.
Bac V. Nguyen Qi Guang Wang Nicola J. Kuiper Alicia J. El Haj Colin R. Thomas Zhibing Zhang 《Journal of the Royal Society Interface》2010,7(53):1723-1733
A chondrocyte and its surrounding pericellular matrix (PCM) are defined as a chondron. Single chondrocytes and chondrons isolated from bovine articular cartilage were compressed by micromanipulation between two parallel surfaces in order to investigate their biomechanical properties and to discover the mechanical significance of the PCM. The force imposed on the cells was measured directly during compression to various deformations and then holding. When the nominal strain at the end of compression was 50 per cent, force relaxation showed that the cells were viscoelastic, but this viscoelasticity was generally insignificant when the nominal strain was 30 per cent or lower. The viscoelastic behaviour might be due to the mechanical response of the cell cytoskeleton and/or nucleus at higher deformations. A finite-element analysis was applied to simulate the experimental force-displacement/time data and to obtain mechanical property parameters of the chondrocytes and chondrons. Because of the large strains in the cells, a nonlinear elastic model was used for simulations of compression to 30 per cent nominal strain and a nonlinear viscoelastic model for 50 per cent. The elastic model yielded a Young''s modulus of 14 ± 1 kPa (mean ± s.e.) for chondrocytes and 19 ± 2 kPa for chondrons, respectively. The viscoelastic model generated an instantaneous elastic modulus of 21 ± 3 and 27 ± 4 kPa, a long-term modulus of 9.3 ± 0.8 and 12 ± 1 kPa and an apparent viscosity of 2.8 ± 0.5 and 3.4 ± 0.6 kPa s for chondrocytes and chondrons, respectively. It was concluded that chondrons were generally stiffer and showed less viscoelastic behaviour than chondrocytes, and that the PCM significantly influenced the mechanical properties of the cells. 相似文献
103.
Boon JP Lewis WE Tjoen-A-Choy MR Allchin CR Law RJ De Boer J Ten Hallers-Tjabbes CC Zegers BN 《Environmental science & technology》2002,36(19):4025-4032
The levels of individual PBDE congeners were investigated in the invertebrate species whelk (Buccinum undatum), seastar (Asterias rubens), and hermit crab (Pagurus bernhardus), the gadoid fish species whiting (Merlangius merlangus) and cod (Gadus morhua), and the marine mammal species harbor seal (Phoca vitulina) and harbor porpoise (Phocoena phocoena). These species are all important representatives of different trophic levels of the North Sea food web. All six major PBDE congeners detected (BDEs 28, 47, 99, 100, 153, and 154) are most prevalent in the commercial Penta-BDE formulation. There is no evidence for the occurrence of the Octa-BDE formulation in the North Sea food web, since its dominant congener, BDE183, was never detected. BDE209, the main congener (> 97%) in the Deca-BDE formulation, was detected only in a minority of the samples and always in concentrations around the limit of detection. Since BDE209 is often the major BDE congener in sediments from the area, the main reason for its low concentrations in biota from the North Sea seems to be a relatively low bioaccumulation potential. This can either be due to a low uptake rate of the very large molecule or a relatively rapid excretion after biotransformation. Since all invertebrates investigated are sentinel species, they are highly representative for the area of capture. The highest lipid-normalized concentrations of PBDEs in the invertebrates occurred near the mouth of the river Tees at the East coast of the UK. The geographical distribution of the PBDEs can be explained by the residual currents in the area. The direction of these currents differs between the summer and the winter season as a result of the presence or absence of vertical summer stratification of the deeper waters north of the Dogger Bank. Summer stratification results in the development of a density-driven bottom water current formed after the onset of vertical stratification of the water column in May leaving the UK coast near Flamborough Head toward the Dogger Bank. In winter, the residual currents run in a more southerly direction and follow the UK coastline. The distribution pattern of the PCBs and p,p'-DDE in the invertebrates was entirely different from that of the PBDEs, which could be expected, since the use of these organochlorines in western Europe peaked in the 1960s and 1970s but has been forbidden more than two decades ago, whereas the production and use of the penta-BDE formulation is of a more recent origin. The higher trophic levels of the North Sea food web were represented by the predatory gadoid fish species whiting and cod and the marine mammal species harbor seal and harbor porpoise. The lipid-normalized levels of the six major PBDE congeners in fish were similar to the levels in the invertebrates, but a biomagnification step in concentrations of generally more than an order of magnitude occurred from gadoid fish to marine mammals. Based on the limited number of samples, no differences could be observed between harbor seal and harbor porpoise. In summary, the results in three species of sentinel invertebrates from a network of stations covering a major part of the North Sea basin showed that the estuary of the river Tees at the UK East coast is a major source for tri- to hexa-PBDEs. Throughout the food-chain, the most marked increase in (lipid-normalized) levels of all six PBDE congeners occurred from predatory (gadoid) fish to marine mammals, agreeing with the transition from gill-breathing to lung-breathing animals. This has serious consequences for the route of elimination of POPs, since their elimination from the blood into the ambient seawater via the gill-membrane is no longer possible. 相似文献
104.
Sheppard CJ 《Applied optics》2002,41(28):5951-5955
Phase can be retrieved from intensity measurements with the intensity transport equation. Three-dimensional image formation of weak phase objects based on this method is investigated. It is shown that, although the refractive index of a thin object can be measured, the three-dimensional variation of refractive index of an arbitrary object cannot, in general, be reconstructed, as spatial frequencies with a zero-axial component are not detected. However, this may not be a problem if regions with known refractive index are present in the sample. 相似文献
105.
Mitoxantrone is an anticancer agent for which it is important to know the concentration in blood during therapy. Current methods of analysis are cumbersome, requiring a pretreatment stage. A method based on surface-enhanced resonance Raman scattering (SERRS) has been developed using a flow cell and silver colloid as the SERRS substrate. It is simple, sensitive, fast, and reliable. Both blood plasma and serum can be analyzed directly, but fresh serum is preferred here due to reduced fluorescence in the clinical samples available. Fluorescence is reduced further by the dilution of the serum in the flow cell and by quenching by the silver of surface-adsorbed material. The effectiveness of the latter process is dependent on the contact time between the serum and the silver. The linear range encompasses the range of concentrations detected previously in patient samples using HPLC methods. In a comparative study of a series of samples taken from a patient at different times, there is good agreement between the results obtained by HPLC and SERRS with no significant difference between them at the 95% limit. The limit of detection in serum using the final optimized procedure for SERRS was 4.0 x 10(-11) M (0.02 ng/mL) mitoxantrone. The ease with which the SERRS analysis can be carried out makes it the preferred choice of technique for mitoxantrone analysis. 相似文献
106.
Davies W. Hobart; Satter Ellyn; Berlin Kristoffer S.; Sato Amy F.; Silverman Alan H.; Fischer Elizabeth A.; Arvedson Joan C.; Rudolph Colin D. 《Canadian Metallurgical Quarterly》2006,20(3):409
The feeding of young children is fundamentally a relational and multisystemic process. Successful treatment of clinically significant feeding problems involves careful assessment of the full range of influences on the feeding relationship and integrated treatment approaches. However, current diagnostic approaches to feeding disorders tend to be reductionistic, exclusively focused on the child as an individual, and overly concerned with exclusionary criteria. Criteria are proposed for "Feeding Disorder Between Parent and Child" that address these limitations and embrace the complexity of feeding problems. A multiaxial diagnosis that describes the child (including medical, developmental, and behavioral characteristics); the parent; the parent-child relationship; and the social and nutritional context of feeding will more accurately speak to treatment planning in this population. The proposed diagnostic criteria were developed and refined on the basis of the available literature and many years of treatment experience across the authors of this article. The proposed diagnosis will support the development and evaluation of treatment packages with components specifically targeted to issues of the child, parent, parent-child interaction, and the broader environment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
107.
McQuiston-Surrett Dawn; Malpass Roy S.; Tredoux Colin G. 《Canadian Metallurgical Quarterly》2006,12(2):137
A considerable amount of empirical research has been conducted on ways to improve the eyewitness identification process, with emphasis on the use of lineups. Public policy changes are currently underway with respect to lineup procedures: Sequential lineups are being recommended to police as the best practice. This may be premature because the conditions under which sequential lineups are superior to simultaneous lineups are not well understood given the current literature: Many studies are reported with insufficient detail needed to judge the adequacy of the research design, new data show that the sequential superiority effect may vary as a function of study methodology, theoretical assumptions have not been adequately tested, and important comparisons that may rule out the ostensible superiority of the sequential lineup have not been studied. This review summarizes the literature, presents new data, and identifies the need for further empirical work before appropriately grounded recommendations as to the superiority of sequential lineups can be made. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
108.
Predictions derived from the interactive activation (IA) model were tested in 3 experiments using the masked priming technique in the lexical decision task. Experiment 1 showed a strong effect of prime lexicality: Classifications of target words were facilitated by orthographically related nonword primes (relative to unrelated nonword primes) but were inhibited by orthographically related word primes (relative to unrelated word primes). Experiment 2 confirmed IA's prediction that inhibitory priming effects are greater when the prime and target share a neighbor. Experiment 3 showed a minimal effect of target word neighborhood size (N) on inhibitory priming but a trend toward greater inhibition when nonword foils were high-N than when they were low-N. Simulations of 3 different versions of the IA model showed that the best fit to the data is produced when lexical inhibition is selective and when masking leads to reset of letter activities. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
109.
110.