784 research outputs found

    Self-assembled liquid crystalline nanotemplates and their incorporation in dye-sensitised solar cells

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    Liquid junction dye-sensitised solar cells (DSSCs) suffer from solvent evaporation and leakage which limit their large-scale production. Here, we have prepared DSSC using a simple and cheap fabrication process with improved photovoltaic parameters and stability. A binary mixture of Smectic A (SmA) and Nematic Liquid Crystal (NLC) was used to provide a self-assembled template for a polymerisable reactive mesogen LC. The layered structure of SmA combined with a low viscosity NLC forms a polygonal structure that provides an ordered and continuous template for reactive mesogens. Once the reactive mesogen is polymerised under UV light, the SmA:NLC mixture is washed away, resulting in a polymer network template containing nanochannels. We demonstrate the incorporation of these templates into DSSCs and find that DSSCs containing these nanochannels show improved open-circuit voltage (VOC_{OC}) (0.705 V) and short-circuit current (JSC_{SC}) (13.25 mA cm2^{-2}) compared to that of the liquid electrolyte (VOC_{OC} = 0.694 V and JSC = 10.46 mA cm2^{-2}). The highest obtained power conversion efficiency with Sm-PE was 5.94% which is higher than that of the reference solar cell (5.51%). These can be attributed to the improved ionic conductivity and ionic diffusion of Sm-PE where the presence of the nanochannels aided the ionic conduction in the polymer electrolyte. In addition, it is hypothesized that the light scattering effect of the polymerised reactive mesogen also contributed to the improved performance of the photovoltaic devices. This finding is important because it is known fact that when a polymer is added to liquid electrolyte, the ionic conductivity will decrease although the stability is improved.A.A.K. and G.R. would like to thank the Cambridge Commonwealth Trust for financial support. A.A.K. would also like to thank the HEC (Pakistan) for financial support. C.W would like to thank EPSRC Integrated Photonics and Electronics Systems funding

    CYLINDRICAL OBSTACLE EFFECT ON CONVECTION INSIDE AN INCLINED ENCLOSURE FILLED WITH A NANOFLUID

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    This study investigated the impact of a cylindrical obstacle on convection in an inclined square cavity filled with water-Al2O3 nanofluid. Using the finite volume method, the problem was resolved by having the inner cylinder rotate adiabatically while other walls were thermally insulated. Additionally, the bottom wall was hotter than the top. The study examined the effects of cylindrical obstacle radius (0.1 ≤ R ≤ 0.2), rotation speed (-500 ≤ Ω ≤ 500), Richardson number (0.01 ≤ Ri ≤ 100), volumetric nanoparticle fraction (0.02), and Grashof number (Gr = 104 ) on heat transfer rate or Nusselt number. The results were compared with previous literature, and the influence of the cylindrical obstacle rotational speed on convection flow was evaluated. An increase in the counterclockwise angular rotating speed resulted in higher nanofluid flux. The heat transmission coefficient increased as the Richardson number decreased. The use of nanofluid in the enclosure increased the coefficient of heat flow through mixed convection. Finally, the study showed that the convection heat exchange is enhanced with the increase in the radius. Moreover, an enhancement of the Nusselt number around 46% was reported for the cylinder, under Gr=10000, ∅=0.02, =45° and Ri= 10

    Sensory Electrical Stimulation Improves Foot Placement during Targeted Stepping Post-Stroke

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    Proper foot placement is vital for maintaining balance during walking, requiring the integration of multiple sensory signals with motor commands. Disruption of brain structures post-stroke likely alters the processing of sensory information by motor centers, interfering with precision control of foot placement and walking function for stroke survivors. In this study, we examined whether somatosensory stimulation, which improves functional movements of the paretic hand, could be used to improve foot placement of the paretic limb. Foot placement was evaluated before, during, and after application of somatosensory electrical stimulation to the paretic foot during a targeted stepping task. Starting from standing, twelve chronic stroke participants initiated movement with the non-paretic limb and stepped to one of five target locations projected onto the floor with distances normalized to the paretic stride length. Targeting error and lower extremity kinematics were used to assess changes in foot placement and limb control due to somatosensory stimulation. Significant reductions in placement error in the medial–lateral direction (p = 0.008) were observed during the stimulation and post-stimulation blocks. Seven participants, presenting with a hip circumduction walking pattern, had reductions (p = 0.008) in the magnitude and duration of hip abduction during swing with somatosensory stimulation. Reductions in circumduction correlated with both functional and clinical measures, with larger improvements observed in participants with greater impairment. The results of this study suggest that somatosensory stimulation of the paretic foot applied during movement can improve the precision control of foot placement

    Glucose-induced down regulation of thiamine transporters in the kidney proximal tubular epithelium produces thiamine insufficiency in diabetes

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    Increased renal clearance of thiamine (vitamin B1) occurs in experimental and clinical diabetes producing thiamine insufficiency mediated by impaired tubular re-uptake and linked to the development of diabetic nephropathy. We studied the mechanism of impaired renal re-uptake of thiamine in diabetes. Expression of thiamine transporter proteins THTR-1 and THTR-2 in normal human kidney sections examined by immunohistochemistry showed intense polarised staining of the apical, luminal membranes in proximal tubules for THTR-1 and THTR-2 of the cortex and uniform, diffuse staining throughout cells of the collecting duct for THTR-1 and THTR-2 of the medulla. Human primary proximal tubule epithelial cells were incubated with low and high glucose concentration, 5 and 26 mmol/l, respectively. In high glucose concentration there was decreased expression of THTR-1 and THTR-2 (transporter mRNA: −76% and −53% respectively, p<0.001; transporter protein −77% and −83% respectively, p<0.05), concomitant with decreased expression of transcription factor specificity protein-1. High glucose concentration also produced a 37% decrease in apical to basolateral transport of thiamine transport across cell monolayers. Intensification of glycemic control corrected increased fractional excretion of thiamine in experimental diabetes. We conclude that glucose-induced decreased expression of thiamine transporters in the tubular epithelium may mediate renal mishandling of thiamine in diabetes. This is a novel mechanism of thiamine insufficiency linked to diabetic nephropathy

    Memory, post-socialism and the media: nostalgia and beyond

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    While research on the mediation of post-socialist memory has gained momentum in recent years, the field remains fragmented and limited to small-scale case studies, with little attempt to develop a more general reflection on the nature of the processes investigated. Engagement with the wider literature on the mediatisation of memory has been limited as well, with research typically applying established conceptual frameworks rather than using post-socialist materials to generate new theoretical insights. Given the state of the field, this article has a double aim. First, it offers a critical review of the main trends in existing research, focussing on four key issues: the fascination with nostalgic modes of remembering, the dominance of national frames of analysis, the lack of research on the mediation of personal and vernacular remembering, and the privileging of descriptive over explanatory modes of analysis. Second, the article outlines a new agenda for the field, and proposes three main research trajectories. The first pays attention to how mediated memories at local and national levels interact with transnational processes of remembering the Cold War, the second focusses on to the intersections between personal and public modes of mediated remembering, and the last moves the discussion from description to explanation, using comparative approaches to advance explanations of different modes of mediated post-socialist memories

    How do you say ‘hello’? Personality impressions from brief novel voices

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    On hearing a novel voice, listeners readily form personality impressions of that speaker. Accurate or not, these impressions are known to affect subsequent interactions; yet the underlying psychological and acoustical bases remain poorly understood. Furthermore, hitherto studies have focussed on extended speech as opposed to analysing the instantaneous impressions we obtain from first experience. In this paper, through a mass online rating experiment, 320 participants rated 64 sub-second vocal utterances of the word ‘hello’ on one of 10 personality traits. We show that: (1) personality judgements of brief utterances from unfamiliar speakers are consistent across listeners; (2) a two-dimensional ‘social voice space’ with axes mapping Valence (Trust, Likeability) and Dominance, each driven by differing combinations of vocal acoustics, adequately summarises ratings in both male and female voices; and (3) a positive combination of Valence and Dominance results in increased perceived male vocal Attractiveness, whereas perceived female vocal Attractiveness is largely controlled by increasing Valence. Results are discussed in relation to the rapid evaluation of personality and, in turn, the intent of others, as being driven by survival mechanisms via approach or avoidance behaviours. These findings provide empirical bases for predicting personality impressions from acoustical analyses of short utterances and for generating desired personality impressions in artificial voices

    Validity and reliability of Turkish version of "Hospital Survey on Patient Safety Culture" and perception of patient safety in public hospitals in Turkey

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    <p>Abstract</p> <p>Background</p> <p>The Hospital Survey on Patient Safety Culture (HSOPS) is used to assess safety culture in many countries. Accordingly, the questionnaire has been translated into Turkish for the study of patient safety culture in Turkish hospitals. The aim of this study is threefold: to determine the validity and reliability of the translated form of HSOPS, to evaluate physicians' and nurses' perceptions of patient safety in Turkish public hospitals, and to compare finding with U.S. hospital settings.</p> <p>Methods</p> <p>Physicians and nurses working in all public hospitals in Konya, a large city in Turkey, were asked to complete a self-administrated patient safety culture survey (n = 309). Data collection was carried out using the Turkish version of HSOPS, developed by Agency for Healthcare Research and Quality (AHRQ). Data were summarized as percentages, means, and SD values. Factor analysis, correlation coefficient, Cronbach's alpha, ANOVA, and t tests were employed in statistical analyses. Items on patient safety were categorized into 10 factors. Factor loadings and internal consistencies of dimension items were high.</p> <p>Results</p> <p>Most of the scores related to dimensions, and the overall patient safety score (44%) were lower than the benchmark score. "Teamwork within hospital units" received the highest score (70%), and the lowest score belonged to the "frequency of events reported" (15%). The study revealed that more than three quarters of the physicians and nurses were not reporting errors.</p> <p>Conclusion</p> <p>The Turkish version of HSOPS was found to be valid and reliable in determining patient safety culture. This tool will be helpful in tracking improvements and in heightening awareness on patient safety culture in Turkey.</p

    Detecting natural disasters, damage, and incidents in the wild

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    Responding to natural disasters, such as earthquakes, floods, and wildfires, is a laborious task performed by on-the-ground emergency responders and analysts. Social media has emerged as a low-latency data source to quickly understand disaster situations. While most studies on social media are limited to text, images offer more information for understanding disaster and incident scenes. However, no large-scale image datasets for incident detection exists. In this work, we present the Incidents Dataset, which contains 446,684 images annotated by humans that cover 43 incidents across a variety of scenes. We employ a baseline classification model that mitigates false-positive errors and we perform image filtering experiments on millions of social media images from Flickr and Twitter. Through these experiments, we show how the Incidents Dataset can be used to detect images with incidents in the wild. Code, data, and models are available online at http://incidentsdataset.csail.mit.edu.Comment: ECCV 202
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