196746 research outputs found
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Unsupervised detection of fetal brain anomalies using denoising diffusion models
No full textCongenital malformations of the brain are among the most common fetal abnormalities that impact fetal development. Previous anomaly detection methods on ultrasound images are based on supervised learning, rely on manual annotations, and risk missing underrepresented categories. In this work, we frame fetal brain anomaly detection as an unsupervised task using diffusion models. To this end, we employ an inpainting-based Noise Agnostic Anomaly Detection approach that identifies the abnormality using diffusion-reconstructed fetal brain images from multiple noise levels. Our approach only requires normal fetal brain ultrasound images for training, addressing the limited availability of abnormal data. Our experiments on a real-world clinical dataset show the potential of using unsupervised methods for fetal brain anomaly detection. Additionally, we comprehensively evaluate how different noise types affect diffusion models in the fetal anomaly detection domain
X-ray induced grain boundary formation and grain rotation in Bi<sub>2</sub>Se<sub>3</sub>
No full textOptimizing grain boundary characteristics in polycrystalline materials can improve their properties. Many processing methods have been developed for grain boundary manipulation, including the use of intense radiation in certain applications. In this work, we used X-ray free electron laser pulses to irradiate single-crystalline bismuth selenide (Bi2Se3) and observed grain boundary formation and subsequent grain rotation in response to the X-ray radiation. Our observations with simultaneous transmission X-ray microscopy and X-ray diffraction demonstrate how intense X-ray radiation can rapidly change size and texture of grains.</p
Microplastics removal from a hospital laundry wastewater combining ceramic membranes and a photocatalytic membrane reactor:Fouling mitigation, water reuse, and cost estimation
No full textThe release of microplastics (MPs) through industrial laundry wastewater accounts for 35 % of global MPs emissions into the environment and it is a significant environmental problem, especially because MPs can absorb contaminants of emerging concern (CECs) from garments. This study is the first to evaluate and perform a cost estimation of the MP removal from hospital laundry wastewater (HLWW) using a combination of ceramic membranes and a pilot-scale photocatalytic membrane reactor (PMR) as a fouling mitigation strategy. The HLWW, from a hospital in Copenhagen, Denmark, contained a total organic carbon (TOC) of 345 mg L-1 and 1.4 × 106 MP L−1, mainly of polyethylene terephthalate (PET) ranging between 100 and 200 μm in size. The pre-treatment with an ultrafiltration (UF) ZrO₂ membrane successfully removed 96 % of MPs and over 98 % of suspended solids and turbidity at an estimated cost of 0.45 US per m3 of permeate, which is lower than the cost of fresh water in Denmark. In conclusion, this innovative treatment strategy offers a sustainable and cost-effective solution for HLWW management, not only reducing water consumption by enabling water reuse in the hospital laundry but also advances towards achieving net-zero liquid discharge and contributing to the UN Sustainable Development Goals for clean water (Goal 6) and climate action (Goal 13)
Divergences in classical and quantum linear response and equation of motion formulations
No full textCalculating molecular properties using quantum devices can be performed through the quantum linear response (qLR) or, equivalently, the quantum equation of motion (qEOM) formulations. Different parameterizations of qLR and qEOM are available, namely naïve, projected, self-consistent, and state-transfer. In the naïve and projected parameterizations, the metric is not the identity, and we show that it depends on redundant orbital rotations. This dependency may lead to divergences in the excitation energies for certain choices of the redundant orbital rotation parameters in an idealized noiseless setting. Furthermore, this leads to a significant variance when calculations include statistical noise from finite quantum sampling.</p
Impact of freestream turbulence integral length scale on wind farm flows and power generation
No full textThe impact of freestream turbulence integral length scale on wind farm flow and power production is investigated by conducting Large Eddy Simulations on wind farms with two spacings, Sx = 8R and Sx = 12R (turbine radius R). The integral length scale of inflow turbulence Lu is varied, Lu ∈ [3.2R, 12.0R], while maintaining identical turbulence intensity and velocity. Shorter integral length scales lead to a faster near wake breakdown and improved wake recovery in the wake of the first turbine, causing substantial increases in the second turbine power output; 42% and 18% for the two spacings. Over the first four turbines, total power output increases by 8.6% and 6.0% respectively. Spectra, cross-correlations and entrainment scales are also examined and show that the first turbine breaks down inflow scales and wake-generated turbulence dominates the inflow to the second turbine. Further into the turbine row, dominant flow structures and entrainment scales are associated with both wake turbulence and larger wind farm-generated structures matching the turbine spacing. These results show that the freestream turbulence integral length scale has a significant impact on wind farm flows and power generation, mainly by impacting the development of wakes in the farm entrance
Enhancing wind turbine blade protection: Solid particle erosion resistant ceramic oxides-reinforced epoxy coatings
No full textIn recent days, it is crucial for the globe to shift fossil fuel energies to renewable energies such as hydroelectric, wind, solar, tidal, geothermal, etc. to mitigate global warming issues. Wind energy has been regarded as one of the renewable energy sources to rely on in the future. In this aspect, wind turbine blade maintenance is quite a challenge in tropical areas like India. One of the main reasons why wind turbine blades get damaged and produce less energy is solid particle erosion. In the present work, epoxy nanocomposite coatings reinforced with Al2O3, ZrO2, and CeO2 nanoparticle fillers have been applied on glass fiber reinforced polymer (GFRP) substrates using a simple spray coating method. These nanoparticles have been prepared in-house by solution combustion synthesis (SCS) route using urea, glycine, and oxalyl dihydrazide fuels, respectively. X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy have been used to characterize the materials and coatings. Epoxy coatings with different Al2O3, ZrO2, and CeO2 nanoparticle concentrations have been subjected to solid particle erosion resistance tests at impinging angles of 30°, 60°, and 90°. ZrO2 and CeO2 nanoparticle-reinforced epoxy coatings show much better resistance to solid particle erosion than Al2O3-reinforced coatings. Estimated average erosion rates are 17 and 11.3 × 10−3 mm3 g−1, respectively, for epoxy coatings with 20 and 40 wt% ZrO2 nanoparticles. However, GFRP substrate and neat epoxy (EP) coating show much higher erosion rates with respect to nanoparticles-reinforced epoxy coatings. To ascertain a correlation between H3/E2 and the solid particle erosion rates of the coatings, nanoindentation tests have been carried out. Tensile strength and initial modulus of all the coatings are found to be directly proportional to the average erosion rates, whereas, elongation at break shows an inverse relationship with the average erosion rate. This correlation of mechanical properties with solid particle erosion performance can play a critical role in the development of realistic simulation of protective coatings for wind turbine blades
Is underweight associated with poorer diet, nutrient status, bone and cardiometabolic health, and school performance in Danish 8-11-year-olds?
No full textPurpose: Underweight, i.e. low body mass index for age and sex, may indicate undernutrition, but despite high prevalence, this aspect is largely overlooked in children in high-income countries. We explored if dietary intake, nutrient status, body composition, bone mineralization, cardiometabolic markers and school performance differed in schoolchildren with underweight compared to normal- and overweight. Methods: We used cross-sectional data from 815 Danish 8-11-year-old children collected in 2011. Intake of foods, macronutrients and key micronutrients (vitamin D, vitamin B12, calcium, iron, zinc and selenium) was assessed by 7-day dietary records. Measurements included anthropometry, dual-energy X-ray absorptiometry and tests of attention and reading skills. Fasting blood samples were analyzed for biomarkers of iron, long-chain n-3 fatty acids and vitamin D status as well as blood lipids, insulin and growth markers. Results: Eighty-three (10.2%) children had underweight and were shown to have a lower intake of energy, red meat, protein and zinc and higher intake of added sugar than children with normal- and overweight. They also had higher fish intake relative to overweight, but blood biomarkers did not differ between groups. Children with underweight had lower fat percent and bone mineralization compared to peers with normalweight, but apart from lower insulin, they did not differ in overall cardiometabolic health or school performance. Conclusion: Although we found some differences in diet, there were no considerable differences in nutrient status, cardiometabolic health or school performance between children with underweight and their normalweight peers. However, the lower bone mineralization is a concern and needs further investigation
Mechanism of maltogenic α-amylase modification on barley granular starches spanning the full range of amylose
No full textAmylopectin (AP)-only (APBS), normal (NBS), and amylose (AM) only (AOBS) barley starches were selected here to investigate catalysis pattern of maltogenic α-amylase (MA) on hydrolyzing AP and AM granular starches. MA shortened starch side chains with degree of polymerization (DP) 11–30. MA-treated APBS exhibited porous granular structures and dramatically increased degree of branching (DB, 17–20 %), and reduced ordered degrees, suggesting high hydrolysis and transglycosylation activities of MA. MA-treated NBS showed less pronounced porous structures and slightly increased DB (2–4 %), indicating high hydrolysis but low transglycosylation activities. AOBS displayed minimal changes in DB (0.2–0.3 %) and starch structures, implying low hydrolysis and transglycosylation activities. Therefore, MA preferred to attack the AP molecules with abundant glucan substrates with DP 11–30, while AM restricted MA activity likely by creating ineffective binding sites and undergoing rapid reorganization. These findings deepened the understanding of the mechanisms of MA in modifying granular starches with varying AM content.</p
Theory-guided development of a barium-doped cobalt catalyst for ammonia decomposition
No full textThe efficiency of the catalytic decomposition of ammonia is a central challenge for the use of ammonia as a potential hydrogen vector and fuel for heavy-duty applications. In this study, we explore the promotional effect of alkali and earth-alkaline metals on cobalt and nickel catalysts for ammonia decomposition in a computational screening. We elucidate the strong influence of the recently proposed spin promotion effect on catalytic activity and identify barium as a promising and stable promoter of Co under the relevant reaction conditions. The predictions are validated experimentally through the study of a BaCo catalyst, ultimately yielding a metal-based hydrogen productivity of 12.2 mol gCo−1 h−1 at 500 °C, common for state-of-the-art ruthenium catalysts. This work not only reports the successful development of a novel catalyst but also provides validation for the spin-promotion effect and its substantial influence on catalyst performance.</p
Biomass: Digestion
No full textAnaerobic digestion is a waste management process catalyzed by bacteria that converts organic material to a gaseous mixture of methane and carbon dioxide, often referred to as biogas. This process involves an intricate dependence on different bacteria groups and can be divided into four main steps: hydrolysis, acidogenesis, acetogenesis, and methanogenesis. Additionally, organic waste usually contains sulfur and, therefore, supports the development of sulfur-reducing bacteria. Methane produced via anaerobic digestion can be used as a renewable fuel for cogeneration or for the production of chemicals such as hydrogen or methanol. In addition, the residual waste from digestion can be used as a liquid fertilizer. In recent years, due to the low cost of organic waste, anaerobic digestion has been sought as a biological source of carbon and renewable energy. The development and expansion of technologies such as pyrolysis, gasification, and electrolysis can offer interesting synergies to boost renewable energy production and carbon conversion. Thus, this chapter provides an overview of anaerobic digestion technology and applications