107 research outputs found

    Representing space: the development, content and accuracy of mental representations by the blind and visually impaired

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    This thesis reports on two studies on the perception and cognition of space by individuals who are blind and visually impaired. Research was conducted with students from Dorton College at the Royal London Society for the Blind (RLSB) in Kent. The first experiment examined the content and accuracy of mental representations of a well-known environment. Students walked a route around the RLSB campus and learned the position of ten buildings and structures. They were then asked to make pointing judgments, estimate distances and complete a spatial cued model of the campus. The second experiment considered the wayflnding strategies and spatial coding heuristics used to explore a complex novel environment. Students were asked to explore a maze and learn the position of six different locations. Their search patterns were recorded and analyzed using Geographic Information Systems (GIS) software. Students were tested using the same methods as in the previous experiment and their performance was related to the type and frequency of strategies used during exploration. Results were complemented with a mobility questionnaire, a low vision quality of life questionnaire and data from a literacy and numeracy assessment as well as ethnographic material collected by the author during the two years spent working and living at the RLSB. The thesis begins with a discussion of disability and society framed within the context of geography, urban planning and design. The concepts of blindness and visual impairment are then examined with particular attention given to the psychosocial implications of visual loss. This is followed by a discussion of growth and development, and in-depth review of research on the development, content and accuracy of mental representations by the blind and visually impaired. Finally, the methods used to collect and analyse data for both experiments are considered in light of individual differences and the inadequacy of some statistical techniques to account for the heterogeneous nature of visual impairment. Results from the first experiment revealed significant differences in the accuracy and content of mental representation between the sighted, visually impaired and blind groups for the pointing and model construction tasks. Performance in the distance estimation task was similar across groups. Large individual differences were identified, with the performance of individuals in the same group varying according to the type and requirement of the task. Results from the second experiment also revealed significant differences between the different groups, this time for all three tasks. Here again, large individual differences were found within each group. An analysis of distortions revealed that despite a disparity in accuracy, the blind and visually impaired shared many of the systematic distortions typically found in the mental representation of sighted individuals further confirming their ability develop functional mental representations of space. Performance in the pointing, distance estimation and model construction tasks were also related to the type and frequency of strategies used to explore the maze with the best performers using a combination of egocentric and allocentric strategies. In general, results from the two experiments support the amodal notion that the construction of accurate mental representations of space is not limited to any particular sensory modality but facilitated by the visual system. It also emphasizes the need for mutually supportive techniques that incorporate both quantitative and qualitative methods in the collection and analysis of cognitive data

    Electrospun Microfibrous Membranes Based on PIM-1/POSS with High Oil Wettability for Separation of Oil–Water Mixtures and Cleanup of Oil Soluble Contaminants

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    A series of PIM-1/POSS microfibrous membranes were fabricated by electrospinning technology. The addition of POSS particles could greatly enhance the hydrophobicity, and a superhydrophobic–superoleophilic membrane was obtained as the POSS concentration increased to 40 wt %. The scanning electron microscopy images indicate that the incorporation of POSS particles results in formations of hierarchical structures on the surface of the PIM-1/POSS fibers. Both the intrinsic hydrophobic nature of POSS and the increase in the fiber surface roughness led to the superhydrophobicity and superoleophilicity. The 40 wt % PIM-1/POSS fibrous membrane could not only separate a wide range of immiscible oil–water mixtures with efficiencies higher than 99.95% but also separate water-in-oil emulsions with efficiencies higher than 99.97%. Furthermore, because of the ultrahigh intrinsic microporosity of the PIM-1 polymer, the PIM-1 fibrous membrane exhibited the ability to adsorb a large amount of contaminants such as oil red O and solvent blue 35 from oils. Therefore, these membranes are multifunctional and can be applied to treating immiscible water–oil mixtures, water-in-oil emulsions, and cleanup of oil soluble contaminants

    Effects of Spinning Temperature on the Morphology and Performance of Poly(ether sulfone) Gas Separation Hollow Fiber Membranes

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    In this study, we demonstrated that poly­(ether sulfone) (PES) hollow fiber membranes with almost defect-free surfaces could be prepared at low PES concentrations if the hollow fibers were spun at low temperatures by dry-jet wet spinning. A series of hollow fiber membranes were spun at different coagulation batch temperatures (<i>T</i><sub>c</sub>) and dope solution temperatures (<i>T</i><sub>d</sub>). Effects of <i>T</i><sub>c</sub> and <i>T</i><sub>d</sub> on the membranes’ morphologies and gas separation performances were investigated. Membrane morphologies characterized by using a scanning electron microscope (SEM) showed that the skin layer thicknesses increased with the decreases in <i>T</i><sub>c</sub> and <i>T</i><sub>d</sub>. Moreover, mean surface pore sizes of the membranes, which were evaluated by using the gas permeation method, significantly decreased as <i>T</i><sub>c</sub> or <i>T</i><sub>d</sub> decreased. PES hollow fiber membranes spun at the lowest temperatures (<i>T</i><sub>c</sub> = 7 °C, <i>T</i><sub>d</sub> = 3 °C) showed O<sub>2</sub> and CO<sub>2</sub> permeances of 18.9 and 53.5 GPU, respectively. And selectivities of O<sub>2</sub>/N<sub>2</sub>, CO<sub>2</sub>/N<sub>2</sub>, and CO<sub>2</sub>/CH<sub>4</sub> gas pairs were 1.15, 3.26, and 1.24, respectively. After silicone coating, the selectivities increased to 7.24, 47.7, and 39.4, respectively, but O<sub>2</sub> and CO<sub>2</sub> permeances decreased to 4.85 and 31.9 GPU, respectively. To our best knowledge, the gas separation performance was the test among all PES hollow fiber membranes

    Fabrication of Superhydrophobic–Superoleophilic Fabrics by an Etching and Dip-Coating Two-Step Method for Oil–Water Separation

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    A dual-scale roughness structure superhydrophobic–superoleophilic fabric was fabricated by first etching the microscale fibers with alkali and then dip-coating in a mixed solution of a polymer of intrinsic microporosity (PIM-1) and fluorinated alkylsilane (PTES). Scanning electron microscopy analysis showed that the etching process created nanoscale pits on the fiber surface and subsequently formed hierarchical structures on the fabric surface. Coating of PIM-1–PTES on the etched fibers significantly lowered the surface energy of the fibers, thus causing the fabric surface to possess superhydrophobicity with a water contact angle of 158° and superoleophilicity with an oil contact angle of 0°. The obtained superwettable fabric was mounted in a leak-proof manner on the open-end glass bottle, like an oil skimmer container. Such a new surface-tension-driven, gravity-assisted, one-step, oil–water separation device was used to separate the oil–water mixture with a separation efficiency as high as 99.96% after 30 recycles

    Carbon Dioxide Capturing by Nitrogen-Doping Microporous Carbon

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    Nitrogen-containing microprous carbon was successfully synthesized by using phloroglucinol and glutaraldehyde as the carbon source and hydrolyzed silk as the nitrogen source. The porous structures and surface chemical compositions of microporous carbon were analyzed and characterized by nitrogen adsorption isotherms, thermogravimetric analysis, Fourier transform infrared spectrum and scanning electron microscope images. The resultant porous carbons had a microporous structure, and the pore size distribution was 0.7–2.0 nm. Phenolic formaldehyde with silk was pyrolyzed and decomposed to condense a cross-linking structure between 230 and 650 °C. The nitrogen-containing groups from silk decomposition were incorporated into a carbon matrix during the carbonization process. The microporous carbon showed good regeneration performance and high adsorption capacities of CO<sub>2</sub> due to its nitrogen-containing groups and developed a micropore structure. Under dynamic conditions, CO<sub>2</sub> could be finely separated from a mixture of CO<sub>2</sub>, N<sub>2</sub> and CH<sub>4</sub> with microporous carbon, which displayed potential application for CO<sub>2</sub> capture

    Effects of Xuezhikang on cGMP level in aorta wall and erythrocyte cytoplasm.

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    <p>Hemoglobin in erythrocyte cytoplasm had been removed by ultrafiltration before the assay. *:<i>P</i><0.05 vs. group C; **:<i>P</i><0.05 vs. group M.</p

    Hydroxycitric acid prevents hyperoxaluric-induced nephrolithiasis and oxidative stress via activation of the Nrf2/Keap1 signaling pathway

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    Nephrolithiasis is a common and frequently-occurring disease in the urinary system with high recurrence. The present study aimed to explore the protective effect and underlying mechanism of hydroxycitric acid (HCA) in hyperoxaluria-induced nephrolithiasis in vitro and in vivo. Crystal deposition and pathophysiological injury in rat models of glyoxylate-induced nephrolithiasis were examined using H&E staining. Cell models of nephrolithiasis were established by oxalate-treated renal tubular epithelial cells. The levels of oxidative stress indexes were determined by ELISA kits. Cell proliferation in vivo and in vitro was evaluated using a cell counting kit-8 (CCK-8) assay and Ki-67 cell proliferation detection kit. Cell apoptosis was measured by flow cytometry and TUNEL staining. The protein levels were examined by western blotting. Our results showed that HCA administration significantly reduced crystal deposition and kidney injury induced by glyoxylate. HCA also alleviated oxidative stress via upregulating the antioxidant enzyme activities of superoxide dismutase (SOD) and catalase (CAT) and reducing the malondialdehyde (MDA) content. Moreover, HCA treatment promoted cell proliferation and inhibited apoptosis of renal tubular epithelial cells exposed to hyperoxaluria. Of note, Nrf2 activator dimethyl fumarate (DMF) exerted the same beneficial effects as HCA in nephrolithiasis. Mechanistically, HCA prevented crystal deposition and oxidative stress induced by hyperoxaluria through targeting the Nrf2/Keap1 antioxidant defense pathway, while knockdown of Nrf2 significantly abrogated these effects. Taken together, HCA exhibited antioxidation and anti-apoptosis activities in nephrolithiasis induced by hyperoxaluria via activating Nrf2/Keap1 pathway, suggesting that it may be an effective therapeutic agent for the prevention and treatment of nephrolithiasis.</p

    Plasma lipids in the four groups of rats (mean±SD).

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    *<p><i>P</i><0.05 vs. group C;</p>**<p><i>P</i><0.05 vs. group M.</p><p>M: atherosclerosis model group, rats were fed with high cholesterol diet (HCD); L: Lovastatin group, rats were fed with HCD+Lovastatin; X: Xuezhikang group, rats were fed with HCD+Xuezhikang. C: control group, rats were fed with regular diet.</p
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