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Room-temperature single-layer 2D van der Waals ferromagnetic-CrXY3 hosting skyrmions
No full textTwo-dimensional (2D) van der Waals magnetic materials that host skyrmions are promising candidates for the next-generation memory devices. Here, we have predicted a class of 2D chromium-based monolayer ferromagnetic semiconducting materials with a Curie temperature (Tc) exceeding 320 K. We systematically studied their ferromagnetism and quantum transport properties by employing a combination of density functional calculations, Monte Carlo simulations, atomic spin dynamics simulations, and non-equilibrium Green function methods. These materials display topological magnetic spin texture, i.e., magnetic skyrmions, resulting from the competitions between magnetic anisotropy and Dzyaloshinskii-Moriya interaction (DMI). Furthermore, we observed the generation and annihilation of Néel skyrmion lattice and asymmetric bimeron lattice in the magnetic field, which can be controlled by an external magnetic field. By tuning the detailed spin configurations and skyrmion density, we can effectively manipulate the signs and magnitudes of the topological Hall conductance. Our results demonstrate the tunable topology and magnetism of the discovered 2D vdW CrXY3 materials, paving the way for skyrmion-based spintronic devices
Urban Agriculture in the Illawarra and Shoalhaven: Community Gardens
No full textThis study provides a situational analysis of community gardens in the Illawarra Shoalhaven, demonstrating a network of community gardens across the region where volunteers gather together to grow and distribute food locally, sharing skills and knowledge along the way
OCTOPUS Database v.2.2 Indo-Pacific Pollen - IPPD
No full textA collection of palaeoecological records containing pollen data and related site and dating information from around Australia and the Indo-pacific region. The data uses the WGS84/Pseudo-Mercator (EPSG: 3857) projected coordinate reference system. Sample metadata is comprehensive and includes bibliographic, contextual, and sample preparation and measurement related information
Using a portable FTIR spectrometer to evaluate the consistency of Total Carbon Column Observing Network (TCCON) measurements on a global scale: the Collaborative Carbon Column Observing Network (COCCON) travel standard
No full textTo fight climate change, it is crucial to have a precise knowledge of greenhouse gas (GHG) concentrations in the atmosphere and to monitor sources and sinks of GHGs. On global scales, satellites are an appropriate monitoring tool. For the validation of the satellite measurements and to tie them to the World Meteorological Organization (WMO) trace gas scale, ground-based Fourier transform infrared (FTIR) networks are used, which provide reference data. To ensure the highest-quality validation data, the network must be scaled to the WMO trace gas scale and have a very small site-to-site bias. Currently, the Total Carbon Column Observing Network (TCCON) is the de facto standard FTIR network for providing reference data. Ensuring a small site-to-site bias is a major challenge for the TCCON. In this work, we describe the development and application of a new method to evaluate the site-to-site bias by using a remotely controlled portable FTIR spectrometer as a travel standard (TS) for evaluating the consistency of columnar GHG measurements performed at different TCCON stations, and we describe campaign results for the TCCON sites in Tsukuba (Japan), East Trout Lake (Canada) and Wollongong (Australia). The TS is based on a characterized portable EM27/SUN FTIR spectrometer equipped with an accurate pressure sensor which is operated in an automated enclosure. The EM27/SUN is the standard instrument of the Collaborative Carbon Column Observing Network (COCCON). The COCCON is designed such that all spectrometers are referenced to a common reference unit located in Karlsruhe, Germany. To evaluate the long-term stability of the TS instrument, it is placed side-by-side with the TCCON instrument in Karlsruhe (KA) and the COCCON reference unit (the EM27/SUN spectrometer SN37, which is operated permanently next to the TCCON-KA site) between deployments to collect comparing measurements. At each of the visited TCCON sites, the TCCON spectrometers collected low-resolution (LR) (0.5 cm-1) and highresolution (HR) (0.02 cm-1) measurements in an alternating manner. Based on the TS as a portable standard, the mea surements are compared to the Karlsruhe site as a common reference. For Tsukuba and Wollongong, the agreement with the reference in Karlsruhe found for XCO2 is on the 0.1 % level for both the LR and HR measurements. For XCH4, the agreement is at the 0.2 % level, with the low-resolution measurements showing a low bias at both sites and for both gases. For XCO, the deviations are up to 7 %. The reason for this is likely to be a known issue with the CO a priori profiles used by the TCCON over source regions. In East Trout Lake (ETL), the TCCON spectrometer broke down while the TS was en route to the station. Hence, no side-by-side comparison was possible there. An important auxiliary value for FTIR retrievals is the surface pressure. Using the pressure sensor in the TS, the surface pressure measurements at each site are also compared. The surface pressure analysis reveals excellent agreement (0.027, 0.135 and 0.094 hPa) for the Tsukuba, ETL and Wollongong sites
Prevalence and Correlates of Adherence to the Global Total Physical Activity Guideline Based on Step Counting Among 3- to 4-Year-Olds: Evidence From SUNRISE Pilot Studies From 17 Countries
No full textBackground: There is limited evidence from globally diverse samples on the prevalence and correlates of meeting the global guideline of 180 minutes per day of total physical activity (TPA) among 3- to 4-year-olds. Methods: Cross-sectional study involving 797 (49.2% girls) 3- to 4-year-olds from 17 middle- and high-income countries who participated in the pilot phases 1 and 2 of the SUNRISE International Study of Movement Behaviours in the Early Years. Daily step count was measured using thigh-worn activPAL accelerometers. Children wore the accelerometers for at least one 24-hour period. Children were categorized as meeting the TPA guideline based on achieving ≥11,500 steps per day. Descriptive analyses were conducted to describe the proportion of meeting the TPA guideline for the overall sample and each of the sociodemographic variables, and 95% CIs were calculated. Multivariable logistic regression was used to determine the sociodemographic correlates of meeting the TPA guideline. Results: Mean daily step count was 10,295 steps per day (SD = 4084). Approximately one-third of the sample (30.9%, 95% CI, 27.6–34.2) met the TPA guideline. The proportion meeting the guideline was significantly lower among girls (adjusted OR [aOR] = 0.70, 95% CI, 0.51–0.96) and 4-year-olds (aOR = 0.50, 95% CI, 0.34–0.75) and higher among rural residents (aOR = 1.78, 95% CI, 1.27–2.49) and those from lower middle-income countries (aOR = 1.35, 95% CI, 0.89–2.04). Conclusions: The findings suggest that a minority of children might meet the TPA guideline globally, and the risk of not meeting the guideline differed by sociodemographic indicators. These findings suggest the need for more surveillance of TPA in young children globally and, possibly, interventions to improve childhood health and development
Critical Nodes Detection: Node Merging Approach
No full textVarious cohesive models are widely employed for the analysis of social networks to identify critical users or key relationships, with the k-core being a particularly popular approach. Existing works, such as the anchor k-core problem, aim to maximize k-core by anchoring nodes (the degree of anchor nodes are set as infinity). However, we find that node merging can also enlarge the k-core size. Different from anchoring nodes, nodes merging can cause both degree increase and decrease which brings more challenges. In this paper, we study the core maximization by node merging problem (CMNM) and prove its hardness. A greedy framework is first presented due to its hardness. To scale for large networks, we categorize potentially influential nodes and provide a detailed analysis of all node merging pairs. Then, based on these analyses, a fast and effective algorithm is developed. Finally, we conduct comprehensive experiments on real-world networks to evaluate the effectiveness and efficiency of the proposed method
Stable anode/separator interface enabled by graft modification of polypropylene separator via electron beam irradiation technique toward high-performance sodium metal batteries
No full textSodium metal batteries (SMBs) are considered as strong alternatives to lithium-ion batteries (LIBs), due to the inherent merits of sodium metal anodes (SMAs) including low redox potential (−2.71 V vs. SHE), high theoretical capacity (1166 mAh g−1), and abundant resources. However, the uncontrollable Na dendrite growth has significantly impeded the practical deployment of SMBs. Separator modification has emerged as an effective strategy for substantially enhancing the performance of SMAs. Herein, for the first time, we present the successful grafting polyacrylic acid (PAA) onto polypropylene (PP) separators (denoted as PP-g-PAA) using highly efficient electron beam (EB) irradiation to improve the cyclability of SMAs. The polar carboxyl groups of PAA can facilitate the electrolyte wetting and provide ample mechanical strength to resist dendrite penetration. Consequently, the regulation of Na+ ion flux enables uniform Na+ deposition with dendrite-free morphology, facilitated by the favorable anode/separator interface. The PP-g-PAA separator significantly enhances the cyclability of fabricated cells. Notably, the lifespan of Na||Na symmetric cells can be extended up to 5519 h at 1 mA cm−2 and 1 mAh cm−2. The stable design of the anode/separator interface achieved through polyolefin separator modification presented in this study holds promise for the further advancement of next-generation advanced battery systems
Comprehensive pollutant emission prediction models from hydrogen-enriched methane combustion in a gas-fired boiler based on box-behnken design method
No full textHydrogen-enriched methane (HEM) combustion is an effective method for reducing the consumption of carbonaceous fuels. However, high adiabatic flame temperature of H2 can cause large NO emissions. To reduce the NO and CO2 emissions from HEM combustion, the Box-Behnken design (BBD) method combining response surface experimental design, analysis of variance, and multi-nonlinear regression models was adopted. The effects of the H2 doping ratio (XH2), preheated air temperature (Tair), excess air coefficient of burners arranged at the bottom (Ex,b), and their interactions on the NO, N2O, and CO2 emissions of a gas-fired boiler were investigated. According to the BBD method, the NO, N2O, and CO2 emissions prediction models with R2 exceeding 0.98 were proposed, respectively. The results showed that the increase of Tair had a positive effect on reducing NO emissions, as the NO exhausted from HEM combustion is mainly thermal NO. Compared with Tair and Ex,b, XH2 was the most significant factor affecting N2O and CO2 emissions, indicating that an increase in XH2 can significantly reduce greenhouse gas emissions. Additionally, the formation and consumption of N2O emissions presented a competitive mechanism at XH2 increased from 0 to 0.8, and CO2 emissions reduced with the increase of XH2, Tair, and Ex,b. Furthermore, a comprehensive emission prediction model with NO, N2O, and CO2 emissions was proposed. With the target of minimizing total NO, N2O and CO2 emissions, three groups of combinations for XH2, Tair, and Ex,b were obtained from the equal weight, entropy weight method, and criteria importance through the inter-criteria correlation method as 1:1:1, 24:9:17, and 21:11:18. The results showed that for minimize emissions, there is not much difference in the results calculated based on the optimal boundary conditions under different weights. For various reduction targets for nitrogen, carbon, and greenhouse gases, three groups of optimal combinations of XH2, Tair, and Ex,b were obtained and their accuracies were verified based on numerical calculations with relative errors below 6%. The proposed comprehensive pollutant emission prediction models are conducive to calculating the pollutant emissions of HEM combustion and guiding the investigation of prediction models considering other operating conditions
Curvature-Dependent Electrochemical Hydrogen Peroxide Synthesis Performance of Oxidized Carbon Nanotubes
No full textSurface oxidized carbon nanotubes (o-CNTs) can produce sustainable hydrogen peroxide (H2O2) by the two-electron transferred oxygen reduction reaction (2e-ORR). The C atoms neighboring to surface epoxy (C-O-C) groups are recognized as active sites. Herein, we report the CNT curvature, or diameter, dependent ORR activity of o-CNT catalysts. Computation modeling suggests that the curvature can alter epoxy group geometry, exerting greater strain on the C-O bond in smaller diameter o-CNTs that leads to improved activity. This theoretical prediction is further experimentally validated by five o-CNTs of different diameters but comparable oxygenous groups. The o-CNT with the smallest diameter (8 nm) delivers the highest H2O2 Faradaic efficiency (>85%, or molar selectivity >90%) and a mass activity of 161 A g-1 at 0.65 V. This curvature effect provides a strategy to design and synthesize efficient electrocatalysts for peroxide production and beyond
Improving Acoustic-Based Slag Foam Control Systems in the BOF
No full textThe control of slag foaming is vital to optimizing BOF performance. Acoustics systems have been applied to BOF monitoring but there is limited information about their accuracy and reliability. Improved understanding of the fundamental behavior of sound in slag foam will help resolve issues pertaining to reliability. The present study is based on physical modelling experiments using scaled models and acrylic vessels. Foams heights were experimentally manipulated, and acoustic transmission was monitored by transmitting pure tone sine waves through the bottom of the foam and measuring acoustic response via microphones. The results showed that acoustic frequencies above 1000 Hz were more sensitive and had greater precision to varying foam heights. This highlights the importance of examining frequency bandwidths that optimize the sensitivity and reliability of the measurement. The prospective application of this knowledge to industrial systems aimed at improving their accuracy and reliability will be discussed