9 research outputs found

    Enabling Complex Fibre Geometries Using 3D Printed Axon-Mimetic Phantoms

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    Purpose: To introduce a method to create 3D-printed axon-mimetic phantoms with complex fibre orientations to characterise the performance of diffusion magnetic resonance imaging (MRI) models and representations in the presence of orientation dispersion. Methods: An extension to an open-source 3D printing package was created to produce a set of five 3D-printed axon-mimetic (3AM) phantoms with various combinations of bending and crossing fibre orientations. A two-shell diffusion MRI scan of the five phantoms in water was performed at 9.4T. Diffusion tensor imaging (DTI), diffusion kurtosis imaging (DKI), the ball and stick model, neurite orientation density and dispersion imaging (NODDI), and Bingham-NODDI were all fit to the resulting diffusion MRI data. A ground truth map of that phantom’s crossing angles and/or arc radius was registered to the diffusion-weighted images. Metrics from each model and representation were compared to the ground-truth maps, and a quadratic regression model was fit to each combination of output metric and ground-truth metric. Results: The mean diffusivity (MD) metric defined by DTI was insensitive to crossing angle but increased with fibre curvature. Axial diffusivity (AD) decreased with increasing crossing angle. DKI’s diffusivity metrics replicated the trends seen in DTI, and its mean kurtosis (MK) metric decreased with fibre curvature, except in regions with high crossing angles. The estimated stick volume fraction in the ball and stick model decreased with increasing fibre curvature and crossing angle. NODDI’s intra-neurite volume fraction was insensitive to crossing angle, and its orientation dispersion index (ODI) was correlated to crossing angle. Bingham-NODDI’s intra-neurite volume fraction was also insensitive to crossing angle, while its primary ODI (ODIP) was also correlated to crossing angle and its secondary ODI (ODIS) was insensitive to crossing angle. For both NODDI models, the volume fractions of the extra-neurite and CSF compartments had low reliability with no clear relationship to crossing angle. Conclusion: Inexpensive 3D-printed axon-mimetic phantoms can be used to investigate the effect of fibre curvature and crossings on diffusion MRI representations and models of diffusion signal. The dependence of several representations and models on fibre dispersion/crossing was investigated. As expected, Bingham-NODDI was best able to characterise planar fibre dispersion in the phantoms

    State-of-the-art technologies for building-integrated photovoltaic systems

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    Advances in building-integrated photovoltaic (BIPV) systems for residential and commercial purposes are set to minimize overall energy requirements and associated greenhouse gas emissions. The BIPV design considerations entail energy infrastructure, pertinent renewable energy sources, and energy efficiency provisions. In this work, the performance of roof/façade-based BIPV systems and the affecting parameters on cooling/heating loads of buildings are reviewed. Moreover, this work provides an overview of different categories of BIPV, presenting the recent developments and sufficient references, and supporting more successful implementations of BIPV for various globe zones. A number of available technologies decide the best selections, and make easy configuration of the BIPV, avoiding any difficulties, and allowing flexibility of design in order to adapt to local environmental conditions, and are adequate to important considerations, such as building codes, building structures and loads, architectural components, replacement and maintenance, energy resources, and all associated expenditure. The passive and active effects of both air-based and water-based BIPV systems have great effects on the cooling and heating loads and thermal comfort and, hence, on the electricity consumption

    A statistical analysis of life cycle assessment for buildings and buildings’ refurbishment research

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    This study aims to examine the literature related to environmental Life Cycle Assessment (LCA) for buildings and buildings' refurbishment from 1994 to 2022 by implementing a statistical analysis based on 'Web of Science' databases. LCA is viewed as a consolidated process that measures the environmental performance of buildings and their services, aiming to address the potential environmental impacts over the life cycle of buildings. A total of 1336 retrieved journal publications for LCA for buildings and 169 journal publications for LCA in building refurbishment. The articles' patterns were investigated in terms of subject categories, journals, countries, and the most highly cited articles. The findings reveal that LCA publications for buildings and building refurbishment have increased over the period 1994–2022, with China being the leading country contributing to the largest number of articles and possessing the most significant influence, followed by the USA for LCA in buildings. While Portugal is the leading country, followed by Italy, for LCA Buildings' Refurbishments. 97.08% of the publications were written in English, 2.04% in German, and 0.68% in Spanish. French and Japanese were the remaining languages, each with one publication, accounting for 0.2% of the 1336 building LCA publications. In contrast to refurbishment, LCA publications were written in only two languages, English (98.7%) and German (1.3%). Results show that the subject area differs depending on the type of LCA publication, with building LCA focusing on construction engineering while refurbishment focused on environmental topics. According to the IF, the most influential journal was renewable & sustainable energy for buildings and refurbishment LCA. However, journal distribution within LCA is still limited, and assessment methods and theme analysis still need to catch up with a clear gap in LCA in environmental impact mitigation and analysis methodologies, which will be a prominent direction of future building LCA research

    An investigation of mercury distribution in the soils around gold mining area at Dar-Mali locality, river Nile State, Sudan

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    An artisanal gold mining region located in North of Atbara (Dar-Mali locality), River Nile State, Sudan (17.82289 to 17.82389N and 33.99974 to 34.02127E) has been studied with the aim to evaluate the soil contamination with mercury (Hg) using two parameters; (i) Comparison of the Hg concentration with the mean concentrations in world soils, (ii) Enrichment Factor (EF). The results revealed that, the concentrations of the Hg are varying in the studied area and the highest concentrations were obtained inside the mining basins used for gold extraction (2.62 mg kg-1 soil) it is around 29 times more than mean Hg concentration in world soils, while the lower concentrations are found at recent Nile River terrace (0.10 mg kg-1 soil). The results also indicated that the soil samples collected from inside mining basins had a highest E.F value (352.84) that means, this site must be closed and remediation process should be started immediately. While the E.F value of recent Nile River terrace site was 8.74, means, all studied sites have significant contamination with Hg. The mobility of Hg may have influenced by northeast wind, or water runoff from mining zone to nearest areas at same wind direction or water flow direction

    Influence of the artisanal gold mining on soil contamination with heavy metals: A case study from Dar-Mali locality, North of Atbara, River Nile State, Sudan

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    Twenty soil samples were collected from North of Atbara (Dar-Mali locality),River Nile State, Sudan (17.82289 to 17.82389N and 33.99974 to 34.02127E) inside and outside gold mining area in order to assess the influence of the gold mining on the concentrations of selected heavy metals (Co, Cu, Fe, Mn, Ni, Pb, Zn, Hg) in study area. The soil contamination by heavy metals of study area was studied using two parameters; (i) Comparison of the heavy metals concentrations with mean concentrations in most world soils, (ii) Enrichment Factor (EF). Results revealed that the concentrations of heavy metals were varying in the study area, the highest concentrations were obtained at the center of mining area particularly inside the mining basins of gold extraction. The concentrations of Cu, Fe, Mn, Zn, Co, Ni, and Pb were ranged from (4.85 to 34.65 mg kg-1 soil), (6,355 to 14,635 mg kg-1 soil), (37.35 to 655 mg kg-1 soil), (11.85 to 42.7 mg kg-1 soil), (0 to 16.5 mg kg-1 soil,) (2.5 to 47.3 mg kg-1 soil) and (2.65 to 823.5 mg kg-1 soil), respectively. The results also indicated that the soil samples which collected from inside mining basins have a highest EF for most heavy metals particularly Pb, which showed EF value of (676.3), suggesting that the Pb may be derived from anthropogenic source. This study recommends regular monitoring of heavy metals in the soils around the Artisanal gold Mining for conservation and protection from pollution

    Retrofitting residential buildings in the University of Sharjah

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    The aim of the research is to investigate best retrofitting strategies that minimizing energy consumption within the context of thermal comfort. The research has targeted two residential compounds in the University of Sharjah: Al Khwarizmi and Al Baironi. Climate Consultant and ECOTECT were used in the simulation process in order to select best passive strategies and tools for the retrofitting. Several parameters such as building orientation, shading devices, and glazing types, were tested during the simulation process. As a result, the study determined the most suitable tools for the existing compounds. The study showed that the use of double glazing with shading devices reduced cooling loads in Al Baironi with 5.42 MWh and 8.13 MWh in Al Khwarizmi. Also, addressed that U-shaped residential layout is more efficient than liner-shaped layout

    The effects of light distribution, color temperature, and Illuminance on the drawings’ quality of fine arts and Design students

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    This study was performed to analyze the light from a psychological point of view and explore how different types of light affect the emotions and performance of students of the College of Fine Arts and Design (CFAD) when illuminance and color temperature were changed. With deep interest in the feature of lighting environments, that effectively increase positive moods and the quality of drawings produced by students. The techniques used for evaluation were field survey, and simulation lighting measurement tool (light meter). The experimental conditions consist of two types of artificial light and daylight. Participants rated their emotions of the lighting environment and draw to test their performance on each condition. The findings showed that students who participated felt more relaxed and more pleasant and performed better in fluorescent artificial light and all artificial lights with natural light conditions. A DIALux evo simulation was used for the comparison study. Finally, some guidelines were highlighted to provide a suitable lighting environment for higher-quality drawings by fine arts and design students

    The Impact of the Building Forms of Tall Buildings on Dust Accumulation and Thermal Performance in Hot Climates

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    This study aims to create an iconic dust-control skyscraper that resembles an environmentally friendly structure, by adapting a new dust simulation design approach. This method seeks to reduce dust dispersion in the air, control dust movement, and siphon it from the ambient air to purify the surrounding environment by implementing design techniques in the skyscrapers of the UAE. To tackle this critical but often overlooked issue, this study focuses on building typologies along the Sheikh Zayed road region in Dubai city due to the area's importance and the existence of numerous renowned skyscrapers. An analytical study was conducted to categorize the typologies, followed by a performance analysis to assess the impact of accumulated dust on solar radiation and the overall thermal performance of the structures. Fourteen cases were evaluated using ANSYS simulation software selected for their basic typologies and their possible existence in reality. The study's design guidelines were set according to the results conducted from running the simulation, as the findings suggested that wind streamlines may easily travel around a circular-shaped structure, while a building's sharp edges act as wind barriers, driving the wind away from the structure and allowing dust to collect on the surfaces. The ideal example, according to the study's conclusions, was the trapezoid form (case 14), which was established by simulation results that demonstrated a 3.4% reduction in roof conduction and a 1.3% reduction in yearly cooling. On the other hand, a biomimetic design approach was also integrated into the study to devise a design concept that effectively responds to nature. Preliminary ideas and potential future avenues for this project are also discussed

    Availability and affordability of blood pressure-lowering medicines and the effect on blood pressure control in high-income, middle-income, and low-income countries: an analysis of the PURE study data

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    Background: Hypertension is considered the most important risk factor for cardiovascular diseases, but its control is poor worldwide. We aimed to assess the availability and affordability of blood pressure-lowering medicines, and the association with use of these medicines and blood pressure control in countries at varying levels of economic development. Methods: We analysed the availability, costs, and affordability of blood pressure-lowering medicines with data recorded from 626 communities in 20 countries participating in the Prospective Urban Rural Epidemiological (PURE) study. Medicines were considered available if they were present in the local pharmacy when surveyed, and affordable if their combined cost was less than 20% of the households' capacity to pay. We related information about availability and affordability to use of these medicines and blood pressure control with multilevel mixed-effects logistic regression models, and compared results for high-income, upper-middle-income, lower-middle-income, and low-income countries. Data for India are presented separately because it has a large generic pharmaceutical industry and a higher availability of medicines than other countries at the same economic level. Findings: The availability of two or more classes of blood pressure-lowering drugs was lower in low-income and middle-income countries (except for India) than in high-income countries. The proportion of communities with four drug classes available was 94% in high-income countries (108 of 115 communities), 76% in India (68 of 90), 71% in upper-middle-income countries (90 of 126), 47% in lower-middle-income countries (107 of 227), and 13% in low-income countries (nine of 68). The proportion of households unable to afford two blood pressure-lowering medicines was 31% in low-income countries (1069 of 3479 households), 9% in middle-income countries (5602 of 65 471), and less than 1% in high-income countries (44 of 10 880). Participants with known hypertension in communities that had all four drug classes available were more likely to use at least one blood pressure-lowering medicine (adjusted odds ratio [OR] 2·23, 95% CI 1·59–3·12); p<0·0001), combination therapy (1·53, 1·13–2·07; p=0·054), and have their blood pressure controlled (2·06, 1·69–2·50; p<0·0001) than were those in communities where blood pressure-lowering medicines were not available. Participants with known hypertension from households able to afford four blood pressure-lowering drug classes were more likely to use at least one blood pressure-lowering medicine (adjusted OR 1·42, 95% CI 1·25–1·62; p<0·0001), combination therapy (1·26, 1·08–1·47; p=0·0038), and have their blood pressure controlled (1·13, 1·00–1·28; p=0·0562) than were those unable to afford the medicines. Interpretation: A large proportion of communities in low-income and middle-income countries do not have access to more than one blood pressure-lowering medicine and, when available, they are often not affordable. These factors are associated with poor blood pressure control. Ensuring access to affordable blood pressure-lowering medicines is essential for control of hypertension in low-income and middle-income countries. Funding: Population Health Research Institute, the Canadian Institutes of Health Research, Heart and Stroke Foundation of Ontario, Canadian Institutes of Health Research Strategy for Patient Oriented Research through the Ontario SPOR Support Unit, the Ontario Ministry of Health and Long-Term Care, pharmaceutical companies (with major contributions from AstraZeneca [Canada], Sanofi Aventis [France and Canada], Boehringer Ingelheim [Germany amd Canada], Servier, and GlaxoSmithKline), Novartis and King Pharma, and national or local organisations in participating countries
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