417932 research outputs found
Sort by
Insight from perfectly selective and ultrafast proton transport through anhydrous asymmetrical graphene oxide membranes under Grotthuss mechanism
No full textProtons transport profoundly affects diverse fields from proton-exchange membrane fuel cells to storing liquid hydrogen. Recent advances have extended proton-exclusive transport to the two-dimensional channels that use hydrous mechanisms for fast proton transport, where the main challenge is the limited selectivity. However, the physical and chemical properties of 2D nanosheets like GO have the potential to implement full selective and ultrafast proton transport. Here, we uncover the physical potential of anhydrous proton transfer mechanism inside two-dimensional space between graphene nanosheets to exploit the exceptional full proton-selective ability and ultrafast conveyance speed of the Grotthuss mechanism. Reactive molecular dynamics simulations illustrate that the interlayer space between two graphene oxide nanosheets, carpeted with hydroxyl functional groups as additional hopping stages to enable the Grotthuss mechanism, can convey protons without water. Further, we dissect three essential factors that provide a deeper insight into ultrafast proton transport: (i) transitional phase to full anhydrous transport, (ii) outlet size for containing undesired species, and (iii) elastic behavior of the membranes under external strain. Our results show that changes in surface geometry can dramatically increase the diffusion rate in the presence of a small electric field by ~70% compared to hydrous transport. These findings can be used not only to guide the efforts in manufacturing a new generation of sustainable nanochannels but also to advance the pioneering technologies revolving around hydrogen
Key aspects for designing business models for a circular bioeconomy
No full textThe circular bioeconomy represents an opportunity of nearly USD $8 trillion until 2030. However, innovative business models are needed for a circular bioeconomy to succeed. What mostly lacks in the body of research on business models for the circular bioeconomy, and what marks the originality of the present article, is summarizing the key aspects that need to be considered when designing, implementing and managing businesses in a circular bioeconomy. Therefore, this study's aim is twofold (i) to reveal key aspects for implementing and managing business models for a circular bioeconomy; and (ii) to point out the issues that lack further research on the theme, based on the existing literature. A systematic literature review was conducted on the Science Direct, Scopus and Web of Science databases. Key aspects for implementing and managing business models were identified according to the business model Canvas framework. Key aspects are related to the role of innovation and new markets, taking the customer perspective into account in the value creation process and being close to customers, adequate management of logistics and feedstock collection systems, being aware of different routes for valuing biomass, seeking technological development, building resilient value chains, and focusing on value creation to cover costs. Issues that need addressing in the existing literature include product-service-systems, take back-systems, seasonal availability of resources, social impacts, rebound effects, and aquatic activities
Structural basis of wheat starch determines the adhesiveness of cooked noodles by affecting the fine structure of leached starch
No full textThe relationship between the fine structure of original starch, leached starch during cooking, and the adhesiveness of noodles prepared by adding starches separated from different wheat cultivars was analyzed. The adhesiveness of noodles was primarily determined by the chain-length distributions of amylopectin rather than amylose. The adhesiveness of cooked noodles was positively correlated with the amount of short amylopectin chains with the degree of polymerization (DP) of 6–12, but negatively correlated with the amount of long chains with 25\ua
Effects of B2O3 on the structure and properties of blast furnace slag by molecular dynamics simulation
No full textBO has the advantages of reducing the liquidus temperature and enhancing the fluidity of slag, while its influence mechanism in atomic scale has not yet been fully understood. Molecular dynamics simulation was conducted to investigate the influence of BO on the structure and properties of SiO[sbnd]CaO-AlO-BO blast furnace slag system at 1773 K. Results showed that a large number of [SiO]-[BO] structures are generated in the system after BO added, Si ions mainly exist in the form of [SiO] tetrahedrons and B ions mainly exist in the form of [BO] planar triangular structures and [BO] tetrahedrons. With the increase of BO content, the proportion of [BO] planar triangular structures increase. In addition, the content of bridge oxygen in the microstructure of slag increases obviously, the content of non-bridge oxygen decreases, and the polymerization degree of the system increases somewhat. Through the analysis of microscopic mechanism and the modified NPL viscosity model, combined with experimental data, the truth that the slag viscosity decreases with the increase of BO contents were known in the simulated concentration range
A protective superhydrophobic Mg–Zn–Al LDH film on Surface-Alloyed Magnesium
No full textA novel approach was developed to fabricate a protective superhydrophobic LDH film on a Zn–Al alloyed surface of AZ31 Mg alloy. The alloyed surface layer not only provided essential divalent and trivalent cations and a base for the direct growth of a Mg–Zn–Al LDH film in a sodium nitrate hydrothermal solution, but also offered additional corrosion and mechanical protection for the substrate magnesium alloy. Further modification with low surface energy lauric acid (LA) could change the micro/nano hierarchical topographic surface of the LDH film from hydrophilicity to super-hydrophobicity. The long-term anti-corrosion performance, super-hydrophobicity, wear resistance, chemical stability and adhesion strength of the LA-modified LDH film on the surface-alloyed AZ31 were experimentally verified
Structural changes in model compounds of sludge extracellular polymeric substances caused by exposure to free nitrous acid
No full textPrevious studies demonstrate that free nitrous acid (FNA i.e. HNO) detaches sewer biofilms, breaks down flocs of waste activated sludge (WAS) and enhances biogas production from WAS. This suggests possible interactions of FNA with organic extracellular polymeric substances (EPS) that bind the cells into biofilms or sludge flocs. This study evaluates the chemical interactions and reaction mechanisms between FNA and molecules representative of key EPS in biofilm and sludge flocs. Molecules chosen to represent components found in the extracellular polymeric matrix were treated with FNA at 6.09 mgN/L (NO\ua0=\ua0250 mgN/L, pH\ua0=\ua05.0 ± 0.2, T\ua0=\ua022 °C) for 24 hours (conditions typically used in applications) so as to consider the hypothesized chemical interactions and the consequent reaction pathways. A number of analytical techniques were employed to measure the molecular changes in the EPS molecules including; proton (H) nuclear magnetic resonance spectroscopy (NMR), electrospray ionisation mass spectrometry (ESI-MS) and gel permeation chromatography (GPC). The results demonstrated that FNA broke down a range of large EPS molecules including carbohydrates, protein and lipids to smaller molecules. Two mechanistic pathways have been proposed including electrophilic substitution, whereby the nitrosium ion (NO) was the reactive electrophile, and oxidative radical reactions, through which the nitrogen radicals (NO, NO) and reactive nitrogen intermediates (RNIs) (e.g. NO and NO) formed from the decomposition of FNA became part of the reaction products. Larger, more complex organic molecules such as humic acid, required higher concentrations of FNA (6.09 mgN/L or greater) to cause molecular breakdown, whereas smaller molecules, such as calcium alginate, was broken down at lower concentrations (3.04 mgN/L). The study contributes to the understanding of the fundamental mechanisms behind the application of FNA for biofilm control and flocular sludge disintegration
Formation and partitioning behaviour of perfluoroalkyl acids (PFAAs) in waste activated sludge during anaerobic digestion
No full textThe formation and fate of perfluoroalkyl acids (PFAAs) in sludge during anaerobic digestion (AD) is of global importance since the sludge is a significant source of PFAAs to the environment. The formation of PFAAs from polyfluorinated compounds, namely PFAA precursors, is poorly understood in AD. This study aims to investigate the formation of PFAAs from precursors and their partitioning behaviour in waste activated sludge (WAS) during AD process. To achieve this, three isotope-labelled PFAAs were spiked and monitored along with indigenous PFAAs and precursors over eight weeks in a laboratory-scale anaerobic digester, fed with sludge from a local wastewater treatment plant and operated with a hydraulic retention time of 12 days under 35 ℃. In addition to isotope-labelled PFAAs, twelve native PFAAs and eight polyfluorinated compounds were detected in the feed and digested sludges. A mass-balance model, validated by the spiking experiment, was applied to predict the concentrations of PFAAs and precursors assuming no formation/degradation in AD. The measured concentrations of short-chain PFAAs (perfluoroalkyl carboxylates (PFCAs): C < 8; perfluoroalkane sulfonates (PFSAs): C < 6) in the AD sludge were significantly (p\ua0< 0.05) higher than the model-predicted concentrations, indicating the formation of these PFAAs from precursors in AD. In contrast, the formation of long-chain PFAAs (PFCAs: C ≥ 8; PFSAs: C ≥ 6) was not observed. Moreover, the degradation of two polyfluoroalkyl phosphates (PAPs) (6:2 PAP and 6:2/8:2 diPAP) occurred, evidenced by their measured concentrations that were statistically lower than the mass-balance predictions. Further, the AD process reduced the amount of PFAAs absorbed/adsorbed to sludge, particularly for the long-chain ones, due to the breakdown of solids
Why safety knowledge cannot be transferred directly to expected safety outcomes in construction workers: the moderating effect of physiological perceived control and mediating effect of safety behavior
No full textThe construction industry is notorious for its high accident and workplace injury rates. High rates of construction workplace injuries, including fatalities, occur worldwide in both developed and developing nations. Our study examines the effects of safety behavior and physiological perceived control (PPC) on the relationship between safety knowledge and outcomes. We examined this relationship by focusing on the mediating role of safety behavior and the moderating role of PPC. We employed a time-lagged design to collect data. Field survey results from 385 site workers from construction sites in the Yangtze region of China show that safety behavior mediated the positive relationship between safety knowledge and outcomes. Furthermore, PPC strengthens the relationship between safety knowledge and safety behavior. The results indicate that workers’ safety knowledge may not transform into expected safety behavior and performance if they experience low levels of PPC. These findings provide new insights into levels of PPC as a boundary condition for understanding the relationships among safety knowledge, safety behavior, and safety outcomes. We discuss the theoretical and practical implications of our findings
The influence of Ca and Cu additions on the microstructure, mechanical and degradation properties of Zn–Ca–Cu alloys for absorbable wound closure device applications
No full textNovel ternary Zn–Ca–Cu alloys were studied for the development of absorbable wound closure device material due to Ca and Cu's therapeutic values to wound healing. The influence of Ca and Cu on the microstructure, mechanical and degradation properties of Zn were investigated in the as-cast state to establish the fundamental understanding on the Zn–Ca–Cu alloy system. The microstructure of Zn-0.5Ca-0.5Cu, Zn-1.0Ca-0.5Cu, and Zn0.5Ca-1.0Cu is composed of intermetallic phase CaZn13\ua0distributed within the Zn–Cu solid solution. The presence of CaZn13\ua0phase and Cu as solute within the Zn matrix, on the one hand, exhibited a synergistic effect on the grain refinement of Zn, reducing the grain size of pure Zn by 96%; on the other hand, improved the mechanical properties of the ternary alloys through solid solution strengthening, second phase strengthening, and grain refinement. The degradation properties of Zn–Ca–Cu alloys are primarily influenced by the micro-galvanic corrosion between Zn–Cu matrix and CaZn13\ua0phase, where the 0.5% and 1.0% Ca addition increased the corrosion rate of Zn from 11.5\ua0μm/y to 19.8\ua0μm/y and 29.6\ua0μm/y during 4 weeks immersion test
Corticosteroids and circadian rhythms in the cardiovascular system
No full textThe mineralocorticoid receptor (MR) plays a central role in cardiac physiological function and disease and is thus an attractive therapeutic target for patients with heart failure. However, the incidence of significant side effects from mineralocorticoid receptor antagonist (MRA) treatment has led to investigation of new mechanisms that may enhance MR targeted therapies. Recent studies have identified the circadian clock as a novel, reciprocal interacting partner of the MR in the heart. While the closely related glucocorticoid receptor (GR) and its ligand, cortisol (corticosterone in rodents), are established regulators of the circadian clock, new data suggest that the MR can also regulate circadian clock gene expression and timing. This review will discuss the role of the MR and its ligands in the regulation of the circadian clock in the heart and the implications of dysregulation of these systems for cardiac disease progression, and for MR activation
Data sources:
Access Repository Dashboard
Do you manage University of Queensland eSpace? Access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard!