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41.
Low-cost printing of poly(dimethylsiloxane) barriers to define microchannels in paper 总被引:2,自引:0,他引:2
This paper describes the use of a modified x,y-plotter to generate hydrophilic channels by printing a solution of hydrophobic polymer (pol(dimethylsiloxane; PDMS) dissolved in hexanes onto filter paper. The PDMS penetrates the depth of the paper and forms a hydrophobic wall that aqueous solutions cannot cross. The minimum size of printed features is approximately 1 mm; this resolution is adequate for the rapid prototyping of hand-held, visually read, diagnostic assays (and other microfluidic systems) based on paper. After curing the printed PDMS, the paper-based devices can be bent or folded to generate three-dimensional systems of channels. Capillary action pulls aqueous samples into the paper channels. Colorimetric assays for the presence of glucose and protein are demonstrated in the printed devices; spots of Bromothymol Blue distinguished samples with slightly basic pH (8.0) from samples with slightly acidic pH (6.5). The work also describes using printed devices that can be loaded using multipipets and printed flexible, foldable channels in paper over areas larger than 100 cm2. 相似文献
42.
Derek S. Smith 《Thin solid films》2010,518(14):3772-3777
We report the attainment of surface plasmon-coupled emission (SPCE) from highly uniform thin silver films, solution-deposited on glass substrates by a wet chemistry approach. The surface morphology of these films was characterized by atomic force microscopy. The SPCE emission enhancements, polarization and angularity obtained from solution-deposited silver on BK7 glass were comparable to that achieved from conventional SPCE slides prepared via vapor deposition. This facile, wet chemistry procedure for the deposition of SPCE films provides an inexpensive, low maintenance alternative to vapor deposition for SPCE substrate preparation. This would allow the fluorescence observation technique to become more readily available for high sensitivity, low cost applications. 相似文献
43.
Many solid wastes contain both zinc and nickel at the same time. For recycling or recovery of metals, it is essential to separate materials. Among those materials, zinc and nickel are very difficult to be separated because there is not so much difference in the chemical and physical properties. This paper focuses on the separation of zinc and nickel ions in a diluted aqua regia solution. Liquid-liquid extraction by TBP, Cyanex 272 and Cyanex 301 was used and a distribution coefficient (D), a separation factor (S) and a relative purity (R) were induced to evaluate the degree of separation. All of the extractions were proportional to the concentration of the extractants, and zinc ions were extracted more easily than nickel ions. Among the extractants, Cyanex 301 showed the best characteristics regarding Zn/Ni separation. In particular, the extraction of zinc ions in the range of pH相似文献
44.
The quantities of hazardous wastes generated in New Zealand are relatively small, both in total volume and on a per capita basis: they consist principally of liquids and solids derived from primary industries such as horticulture and forestry, and from the Petroleum, chemical and manufacturing industries. There is no satisfactory inventory of hazardous waste quantities or relative toxicity at the national level, nor is there any central coordinating organisation responsible for the implementation of sound management strategies. Current legislation involves several Government departments in statutory or advisory roles connected with hazardous waste management, but administration of disposal practices devolves to regional and local authorities. The occasional uncontrolled discharge of chemical wastes, unsatisfactory past practices regarding landfill siting and leachate management, and the development of major petrochemical industries, together require better coordinated and enforced policies concerning hazardous waste disposal. The most widely advocated method of hazardous waste disposal for New Zealand is codisposal in appropriately sited and controlled landfills, with particular emphasis on protection of freshwater resources, both surface and subsurface. The secure landfill solution adopted for the Waireka chemical dump site near New Plymouth demonstrates that containment is a necessary management strategy in particular situations: alternative methods of disposal such as incineration of certain intractable wastes should also be promoted as technically feasible and environmentally acceptable. Greater use of replacement, recycling or reprocessing must be encouraged in order to minimise the quantities, and toxicity of hasardous wastes requiring disposal in New Zealand. 相似文献
45.
Brefeldin A (BFA) has been reported to cause disassembly of the Golgi. We have used three-dimensional (3-D) high-resolution scanning electron microscopy (HRSEM) to investigate these effects in human skin fibroblast cells. The spontaneous reassembly during prolonged exposure to BFA and some effects of forskolin were observed. A BFA concentration of 5μg/ml caused Golgi complexes to become vesicular, resulting in a progressive decrease in the size of the Golgi. Morphologic changes were visible within 2 min of BFA incubation, and by 30 min no identifiable Golgi could be found. Spontaneous reassembly of the Golgi apparatus upon the removal of the BFA or with continued long-term exposure with BFA could not be confirmed. Preliminary experiments with forskolin were not effective in reversing or inhibiting the effects of BFA in human fibroblast cells grown in culture. This inability for spontaneous reassembly and nonreversal by forskolin may reflect a differential effect of BFA in various cell types. HRSEM has proven to be useful for observing 3-D morphologic effects of BFA in Golgi. 相似文献
46.
Individuals with a positive visual attention bias may use their gaze to regulate their emotions while under stress. The current study experimentally trained differential biases in participants' (N = 55) attention toward positive or neutral information. In each training trial, one positive and one neutral word were presented and then a visual target appeared consistently in the location of the positive or neutral words. Participants were instructed to make a simple perceptual discrimination response to the target. Immediately before and after attentional training, participants were exposed to a stress task consisting of viewing a series of extremely negative images while having their eyes tracked. Visual fixation time to negative images, assessed with an eye tracker, served as an indicator of using gaze to successfully regulate emotion. Those participants experimentally trained to selectively attend to affectively positive information looked significantly less at the negative images in the visual stress task following the attentional training, thus demonstrating a learned aversion to negative stimuli. Participants trained toward neutral information did not show this biased gaze pattern. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
47.
Virtually all theories of visual word recognition assume (typically implicitly) that when a pathway is used, processing within that pathway always unfolds in the same way. This view is challenged by the observation that simple variations in list composition are associated with qualitative changes in performance. The present experiments demonstrate that when reading aloud, the joint effects of stimulus quality and word frequency on response time are driven by the presence/absence of nonwords in the list. Interacting effects of these factors are seen when only words appear in the experiment, whereas additive effects are seen when words and nonwords are randomly intermixed. One way to explain these and other data appeals to the distinction between cascaded processing (or interactive activation) on the one hand versus a thresholded mode of processing on the other, with contextual factors determining which mode of processing dominates. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
48.
Recent evidence suggests that the processes responsible for generating a phonological code from print are flexible in skilled readers. An important goal, therefore, is to identify the conditions that lead to changes in how a phonological code is computed. Five experiments are reported that examine whether phonological processes change as predicted by the pathway control hypothesis when reading aloud words and nonwords. Changes in reading processes were assessed by measuring the effect of predictable switches between stimulus categories across trials. The results of the present experiments are argued to be consistent with the pathway control hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
49.
Daryl Letto Derek Webb Mark Rupke Brian Herner 《中国给水排水》2007,23(24):103-108
对采用天然有机滤料和合成无机滤料的生物除臭滤池在加拿大多伦多市Ash-bridge’s Bay污水厂污泥处理站的干化和转运段的应用效果进行了分析。详细介绍了污泥脱水工艺、臭气的产生及其组分,进而对软木树皮滤料和矿物合成永久性滤料的除臭效果进行了比较。还讨论了一些具体的运行经验,并采用动态模型对不同条件下的运行数据进行了分析。 相似文献
50.
Derek G. Land Malcolm G. Gee Jennifer M. Gee Christopher A. Spinks 《Journal of the science of food and agriculture》1975,26(10):1585-1591
Two unknown components in extracts of broiler house litter were identified as 2,4,6-trichloroanisole and 2,4,6-trichlorophenol; the latter compound was also found in extracts of fresh wood shavings. Experiments with pure cultures of fungi isolated from the litter demonstrated that these microorganisms were capable of methylating 2,4,6-trichlorophenol to the chloroanisole. A musty taint in broiler chickens was shown to be due to the presence of 2,4,6-trichloroanisole. 相似文献