48080 research outputs found
Sort by
Unveiling the oxidation mechanism of CrTaTiMo refractory medium-entropy alloys: A synergy of density functional theory and ab initio molecular dynamics
No full textThe demand for advanced materials capable of withstanding extreme high-temperature conditions has led to the development of novel High-Entropy Alloys (HEAs). Recent works indicate that forming a CrTaO4 protection layer gives HEAs excellent long-term oxidation resistance. In this study, the high-temperature oxidation resistance properties of CrTaTiMo Refractory Medium-Entropy Alloys (RMEAs) were assessed by Density Functional Theory (DFT) and ab initio Molecular Dynamics (AIMD). Through the oxygen adsorption and diffusion calculations, we demonstrated the preferential oxygen adsorption sequence on the surface of the RMEA as Ti, Ta, Cr, and Mo. Furthermore, our analysis identified the sites featuring Ta as subsurface atoms were the weakest locations for oxygen atom diffusion. The dynamic oxidation mechanism of oxygen molecules on CrTaTiMo RMEA was investigated by AIMD simulations. The results confirmed that the adsorption and dissociation of O2 molecules on the alloy surface. Additionally, the diffusion of the O atom took place at temperatures greater than 873 K and confirmed the O-attracting feature of Ta atoms. Moreover, electronic structure calculations confirmed the bonding of oxygen atoms with those four metal elements. This study could serve as a valuable reference for the strategic development of the CrTaTiMo-based RMEAs or RHEAs for high-temperature, long-term oxidation resistance applications.</p
Data-driven surrogate optimization for deploying heterogeneous multi-energy storage to improve demand response performance at building cluster level
No full textEnergy storage such as battery and thermal energy storage is an effective approach to shift building peak load and alleviate grid stress at a building cluster level. However, due to the heterogeneous performance of different types of storage (e.g., response speed, charge/discharge efficiency and rate, storage capacity) and highly diversified energy use patterns of individual buildings, the multi-energy storage should be properly selected and optimally designed for individual buildings to achieve effective load shifting. The optimal deployment of multi-energy storage at a cluster level is a challenging optimization problem due to the nonlinear dynamic performance of the multi-energy storage and the high dimensionality as a result of a large number of buildings. To tackle the challenges, this study proposes a data-driven surrogate optimization method that optimally deploys multi-energy storage at a cluster level to minimize the building cluster energy bill under demand response programs. The method utilizes data-driven surrogate models to accurately predict demand response performance of individual buildings with multi-energy storage. An iterative optimization with automated energy-storage-option screening is developed to optimize the multi-energy storage configurations and design parameters. For a case study including 21 buildings, by optimally deploying multi-energy storage including battery, cooling TES tank, and building-integrated TES, the method reduced the building cluster energy bill by 8%–181% as compared to baseline cases. The optimal deployment method effectively identifies the buildings with better potential to adopt demand-side management and balances the pros and cons of the energy storage options, increasing demand response incentives by 12%–31%. The proposed method can be used in practice to facilitate the deployment of energy storage and improve engagement of buildings in demand response
On-site catalytic wastewater remediation by sustainably produced H2O2 via scalable single-atomic Fe-incorporated Janus membrane
No full textElectrosynthesis of hydrogen peroxide (H2O2) from oxygen is a green and sustainable route toward on-site wastewater treatment. Nevertheless, the performance mismatch of the catalyst species and gas-diffusion components gives rise to low O2 utilization efficiency and limited H2O2 production rate in a practical cell. Herein, we propose a flexible and scalable Janus electrode comprising hydrophilic single-atomic Fe-incorporated catalytic layer and hydrophobic gas-attraction layer. The hydrophobic layer enables efficient oxygen diffusion, and the hollow-structured catalysts allow oxygen gas trapping with a high local oxygen concentration, resulting in a high Faradaic efficiency and fast H2O2 production rate. Accordingly, an 80 h electrocatalytic H2O2 synthesis could be gained at 80 mA cm−2. The Janus electrode delivers a H2O2 selectivity of 92% and a yield of 592 mmol g−1 h−1 in a flow cell. The thus-produced H2O2 allows for an in situ antibiotic removal, with the potential for on-site eco-restoration
Early human occupation of Australia’s eastern seaboard
No full textSecure archaeological evidence for human occupation on the eastern seaboard of Australia before ~ 25,000 years ago has proven elusive. This has prompted some researchers to argue that the coastal margins remained uninhabited prior to 25 ka. Here we show evidence for human occupation beginning between 30 ± 6 and 49 ± 8 ka at Wallen Wallen Creek (WWC), and at Middle Canalpin Creek (MCA20) between 38 ± 8 and 41 ± 8 ka. Both sites are located on the western side of Minjerribah (North Stradbroke Island), the second largest sand island in the world, isolated by rising sea levels in the early Holocene. The earliest occupation phase at both sites consists of charcoal and heavily retouched stone artefacts made from exotic raw materials. Heat-treatment of imported silcrete artefacts first appeared in sediment dated to ~ 30,000 years ago, making these amongst Australia’s oldest dated heat-treated artefacts. An early human presence on Minjerribah is further suggested by palaeoenvironmental records of anthropogenic burning beginning by 45,000 years ago. These new chronologies from sites on a remnant portion of the continental margin confirm early human occupation along Sahul’s now-drowned eastern continental shelf
Ethical Challenges of Disaster Management Faced by Humanitarian Populations: Empirical Insights from a Developing Country
No full textDisaster management in Pakistan has been merely focusing on managing medical, food, and rehabilitation resources, but not so much on the humanitarian ethics during the relief efforts. The National Disaster Management Framework in Pakistan focuses on documenting the ethical approaches but fails to practically incorporate them when administering relief and recovery services in Pakistan. There is not so much knowledge, awareness, and practical implications about standards of conduct, which could guide the disaster management team and social service providers about actions and behaviors conforming to morals and professional values throughout the disaster recovery phase. This study is one of the first to explore the ethical issues faced by disaster survivors after relief providers respond to their needs in the posthumanitarian fields of Pakistan. It aims to identify the gaps that exist in ethical practices required in disaster management, particularly in the relief and recovery stages of humanitarian crises in Pakistan. This study gathered data from flood victims in the Pakistani cities of Sambhrial, Hafizabad, and Rajanpur. The data collection activities were funded by the Humanitarian Innovation Initiative, Brown University, and conducted in collaboration with the Pakistan Red Crescent Society (PRCS). Our results indicate that relief workers are trained technically but not on the humanitarian ethics in terms of handling humanitarian populations on equitable and rights-based disaster management grounds
Associations between wastewater gut microbiome and community obesity rates: Potential microbial biomarkers for surveillance
No full textGut microbes are crucial for human health, which are usually accumulated in urban wastewater systems. Seven wastewater treatment plants in Australia with distinct population obesity rates between 18% and 33% were selected for wastewater sampling and analysis. Human gut microbiome were detected using metagenomic sequencing to investigate their associations with the community obesity rate. To unravel this complex relationship, a range of algorithm models, including linear discriminant analysis effect size (LEfSe), similarity percentage analysis (SIMPER), statistical analysis of metagenomic profiles (STAMP), linear models for microarray and RNA-Seq data analysis (LIMMA), Relief, ratio approach for identifying differential abundance (RAIDA), least absolute shrinkage and selection operator (LASSO), support vector machine (SVM), Boruta, DESeq2 and analysis of compositions of microbiomes with bias correction (ANCOM-BC), were used to identify potential bacterial biomarkers for obesity in the wastewater microbiome. Among these algorithm models, LEfSe, LIMMA, SIMPER and SVM are effective in identifying multiple microbial biomarkers. Specific human gut microbes, including Ruminococcus_E, Agathobacter, Fusicatenibacter, Anaerobutyricum, Blautia_A and Neisseria, were identified as potential consensus microbial biomarkers for obesity in the population. A high obesity rate is mainly characterized by a high abundance of pathogenic bacteria and microorganisms associated with xenobiotic biodegradation and metabolism, endocrine and metabolic diseases, and transcription pathways. This study underscores the innovative potential of leveraging human gut microbes in wastewater as biomarkers for monitoring obesity levels across communities, offering a novel, cost-effective, and indirect approach to public health surveillance
Half a century after their discovery: Structural insights into exonuclease and annealase proteins catalyzing recombineering
No full textRecombineering is an essential tool for molecular biologists, allowing for the facile and efficient manipulation of bacterial genomes directly in cells without the need for costly and laborious in vitro manipulations involving restriction enzymes. The main workhorses behind recombineering are bacteriophage proteins that promote the single-strand annealing (SSA) homologous recombination pathway to repair double-stranded DNA breaks. While there have been several reviews examining recombineering methods and applications, comparatively few have focused on the mechanisms of the proteins that are the key players in the SSA pathway: a 5′→3′ exonuclease and a single-strand annealing protein (SSAP or “annealase”). This review dives into the structures and functions of the two SSA recombination systems that were the first to be developed for recombineering in E. coli: the RecET system from E. coli Rac prophage and the λRed system from bacteriophage λ. By comparing the structures of the RecT and Redβ annealases, and the RecE and λExo exonucleases, we provide new insights into how the structures of these proteins dictate their function. Examining the sequence conservation of the λExo and RecE exonucleases gives more profound insights into their critical functional features. Ultimately, as recombineering accelerates and evolves in the laboratory, a better understanding of the mechanisms of the proteins behind this powerful technique will drive the development of improved and expanded capabilities in the future
Last Glacial Maximum cooling induced positive moisture balance and maintained stable human populations in Australia
No full textLong-standing interpretations of the Last Glacial Maximum (21,000 ± 2000 years ago) in Australia suggest that the period was extremely cold and arid, during which the Indo-Australian summer monsoon system collapsed, and human populations declined and retreated to ecological refuges to survive. Here, we use transient iTRACE simulations, combined with palaeoclimate proxy records and archaeological data to re-interpret the late Last Glacial Maximum and terminal Pleistocene (21,000 – 11,000 years) in Australia. The model suggests climates during the peak Last Glacial Maximum were cooler than present (−4 to −11 °C), but there is no evidence of monsoon collapse or substantial decreases in moisture balance across Australia. Kernel Density Estimates of archaeological ages show relatively stable and persistent human activity across most regions throughout the late Last Glacial Maximum and terminal Pleistocene, consistent with genetic evidence. Spatial coverage of archaeological sites steadily increased across the terminal Pleistocene; however, substantial population change is not evident
Tribological Properties and Lubrication Mechanisms of Water-Based Nanolubricants Containing TiO2 Nanoparticles during Micro Rolling of Titanium Foils
No full textThe tribological behavior of traditional oil-in-water (O/W) lubricants (1.0 wt.%) and nano-TiO2 additive lubricants (1.0–9.0 wt.%) during micro rolling of titanium foils were analyzed. In this study, the surface morphologies of titanium foils under various lubrication conditions were assessed, and the corresponding lubrication mechanisms were revealed. The tribological behavior of nano-TiO2 additive lubricants during micro rolling of titanium foils was also explored through a series of characterization methods. The utilization of nano-TiO2 additive lubricants in micro rolling reduces the surface roughness of titanium foils. Moreover, it effectively inhibits the generation of indentations and cracks during rolling processes, enhancing the surface quality of rolled specimens. Additionally, owing to the synergism of rolling, tribo-film, mending and polishing effects of the nanoparticles, both the rolling force and surface roughness were minimized by using lubricants containing 3.0 wt.% TiO2 nanoparticles. Overall, an optimal concentration (3.0 wt.%) of TiO2 nanoparticles in water-based nanolubricants was obtained with enhanced tribological properties and lubrication performance during micro rolling of titanium foils
A cross-sectional study of Australian teachers’ health: are work-related factors associated with lifestyle behaviours?
No full textTeacher’s lifestyle behaviours are important because they lead to positive health outcomes for teachers themselves and because teachers model behaviour to their students.This cross-sectional study examined the lifestyle behaviours of a large sample of teachers in New South Wales (NSW), Australia and assessed the association between work-related factors and lifestyle behaviours. From February to October 2021, data were collected on the lifestyle behaviours, work-related factors and socio-demographics of primary and secondary school teachers in NSW, via an online survey. Associations between individual work-related factors and lifestyle behaviours were modelled using logistic regression and adjusted for sex, age, number of children and geographic location. Most of our survey sample (n = 1136) were women (75%) and 53% were reported as having overweight or obesity. Only 23% of teachers met the recommended physical activity guidelines, 39% met fruit intake guidelines, 9% met vegetable intake guidelines and 58% met healthy sleep guidelines. Most teachers (78%) met the recommendation of sugar-sweetened beverage consumption, 89% were not current smokers, but only 46% met the recommended alcohol consumption guidelines. Hours worked, teaching load, school sector and teacher role were associated with one or more lifestyle behaviours after adjusting for the demographic variables. This study highlights the need for additional support to improve the health-related behaviours of teachers in NSW. Policymakers should recognize the negative impact of high workloads on teachers’ health-related behaviours, increasing their risk of chronic disease