ANSTO :: Browsing by Author "Wang, S"

Browsing by Author "Wang, S"

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Auto-MatRegressor: liberating machine learning alchemists
(Elsevier, 2023-06-30) Liu, Y; Wang, S; Yang, Z; Avdeev, M; Shi, S
Machine learning (ML) is widely used to uncover structure–property relationships of materials due to its ability to quickly find potential data patterns and make accurate predictions. However, like alchemists, materials scientists are plagued by time-consuming and labor-intensive experiments to build high-accuracy ML models. Here, we propose an automatic modeling method based on meta-learning for materials property prediction named Auto-MatRegressor, which automates algorithm selection and hyperparameter optimization by learning from previous modeling experience, i.e., meta-data on historical datasets. The meta-data used in this work consists of 27 meta-features that characterize the datasets and the prediction performances of 18 algorithms commonly used in materials science. To recommend optimal algorithms, a collaborative meta-learning method embedded with domain knowledge quantified by a materials categories tree is designed. Experiments on 60 datasets show that compared with the traditional modeling method from scratch, Auto-MatRegressor automatically selects appropriate algorithms at lower computational cost, which accelerates constructing ML models with good prediction accuracy. Auto-MatRegressor supports dynamic expansion of meta-data with the increase of the number of materials datasets and other required algorithms and can be applied to any ML materials discovery and design task. © 2023 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.
Combining environmental isotopes with contaminants of emerging concern (CECs) to characterise wastewater derived impacts on groundwater quality
(Elsevier B.V., 2020-09-01) McCance, WG; Jones, OAH; Cendón, DI; Edwards, M; Surapaneni, A; Chadalavada, S; Wang, S; Currell, MJ
The potential for Wastewater Treatment Plants (WWTPs) to cause adverse impacts to groundwater quality is a major global environmental challenge. Robust and sensitive techniques are required to characterise these impacts, particularly in settings with multiple potential contaminant sources (e.g. agricultural vs. site-derived). Stable (δ2HH2O, δ18OH2O, δ15NNO3, δ18ONO3 and δ13CDIC) and radioactive (3H and 14C) isotopes were used in conjunction with three Contaminants of Emerging Concern (CECs) - carbamazepine, simazine and sulfamethoxazole - to discriminate between multiple potential contamination sources at an Australian WWTP. The radioactive isotope tritium provided a sensitive indicator of recent (post-1990s) leakage, with groundwater activities between 0.68 and 1.83 TU, suggesting WWTP infrastructure (activities between 1.65 and 2.41) acted as a recharge ‘window’, inputting treated or partially treated effluent to the underlying groundwater system. This was corroborated by water stable isotopes, which showed clear demarcation between δ18OH2O and δ2HH2O in background groundwater (δ18OH2O and δ2HH2O values of approximately −5 and −28‰, respectively) and those associated with on-site wastewater (median δ18OH2O and δ2HH2O values of −1.2 and −7.6‰, respectively), with groundwater down-gradient of the plant plotting on a mixing line between these values. The CECs, particularly the carbamazepine:simazine ratio, provided a means to further distinguish wastewater impacts from other sources, with groundwater down-gradient of the plant reporting elevated ratios (median of 0.98) compared to those up-gradient (median of 0.11). Distinctive CEC ratios in impacted groundwater close to the WWTP (∼3.0) and further down-gradient (2.7–9.3) are interpreted to represent a change in composition over time (i.e., recent vs. legacy contamination), consistent with the site development timeline and possible changes in effluent composition resulting from infrastructure upgrades over time. The data indicate a complex set of co-mingled plumes, reflecting different inputs (in terms of both quantity and concentration) over time. Our approach provides a means to better characterise the nature and timing of wastewater derived impacts on groundwater systems, with significant global implications for site management, potentially allowing more targeted monitoring, management and remedial actions to be undertaken. © 2020 Elsevier B.V.
Floating zone crystal growth and magnetic properties of bilayer manganites Pr(Sr1−xCax)(2)Mn2O7
(Elsevier Science BV, 2012-08-15) Deng, G; Thiyagarajan, R; Radheep, DM; Pomjakushina, E; Medarde, M; Krzton-Maziopa, A; Wang, S; Arumugam, S; Conder, K
Single crystals of a bilayer manganite series Pr(Sr1-xCax)(2)Mn2O7 (x=0, 0.4, 0.9, 1) have been grown using traveling solvent floating zone technique under various oxygen partial pressure. It was found that the crystal quality is very sensitive to oxygen partial pressure applied during growth and highly Ca doped crystals could only be obtained at elevated oxygen pressure. Whereas a secondary phase was observed for PrCa2Mn2O7 grown at oxygen partial pressure below 1 bar, a pure phase can be achieved at 8 bar of oxygen. This was evidenced studying composition mapping by X-ray fluorescence spectroscopy. X-ray Laue diffraction and X-ray powder diffraction have been carried out on the samples for the quality check of the grown crystals. Susceptibility measurements indicate that all samples are antiferromagnetic at low temperature. They also reveal the existence of two anomalies at similar to 320 K and 370 K, which coincide with the charge ordering/orbital ordering transitions described in the literature. © 2012, Elsevier Ltd.
High oxygen pressure single crystal growth of highly Ca-doped spin ladder compound Sr(14-x)Ca(x)Cu(24)O(41) (x > 12)
(Elsevier, 2011-07-15) Deng, G; Radheep, DM; Thiyagarajan, R; Pomjakushina, E; Wang, S; Nikseresht, N; Arumugam, S; Conder, K
Large size high-quality Ca-doped Sr14âˆ’xCaxCu24O41 (x=12.2, 12.6 and 13) spin ladder superconducting single crystals were grown using a modified mirror floating zone furnace with oxygen pressure up to 35 bar. The qualities of the as-grown single crystals were confirmed by polarized optical microscopy, neutron diffraction and X-ray diffraction methods. The sample compositions and homogeneity were measured using micro-X-ray fluorescence spectroscopy. The lattice parameters of each sample have been refined using the Rietveld method. The oxygen stoichiometry measurements which were performed by hydrogen reduction/thermogravimetry method show that all the three samples are slightly oxygen deficient even though high oxygen pressure was applied during growth. The high oxygen pressure is indispensible for growing highly Ca-doped Sr14âˆ’xCaxCu24O41 single crystals. The susceptibility was measured along c-axis for all three compositions, fitting well with the one dimensional dimer model, consistent with the reported values of undoped Sr14Cu24O41 parent compounds.(C) 2011 Elsevier B.V.
Identifying the source of atmospheric moisture over arid deserts using stable isotopes (2H and 18O) in precipitation
(John Wiley & Sons, Inc, 2018-01-03) Rao, WB; Zhang, WB; Yong, B; Tan, HB; Meredith, KT; Jin, K; Zheng, FW; Wang, S
Precipitation is a major component of the hydrologic cycle in arid desert areas. To date, however, few studies have been conducted on investigating the isotope characteristics and moisture sources of precipitation in arid desert environments. The Alxa Desert Plateau is a critical arid desert area in North China. This study is the first to analyse the stable isotopic composition of precipitation to identify the sources of atmospheric moisture over this plateau. Our results show that the δD and δ18O values of precipitation across the plateau change greatly at both daily and monthly timescales, and exhibit seasonal variations. Among the main meteorological parameters, atmospheric temperature is the most predominant factor controlling the isotopic composition and the δD–δ18O relationship of local precipitation. Analyses of the precipitation isotopes with the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model reveal that (a) the westerly and polar moisture sources are the dominant controls on summer and winter precipitation and (b) the evaporation of local lake water significantly affects winter precipitation even though it only represents a small amount. Based on the isotope data of 2013–2016 precipitation, a local meteoric water line (LMWL) is derived: δD = (8.20 ± 0.22)·δ18O + (8.15 ± 2.16)‰ for the study site. Compared to the global meteoric water line, the LMWL has a greater slope and lower d-excess. This can be explained by admixing of atmospheric moisture resulting from the evaporation of local lake water. Based on this LMWL, we are able to trace that groundwater of the Badain Jaran Desert originates from the surrounding mountains with altitudes of <4,000 m. The newly derived LMWL shows that the recharge altitudes of desert groundwater are overestimated on the basis of the previous LMWLs. This study not only provides insights into the hydrological cycle but also offers guidance for water resource management in arid desert areas of China. Additionally, this study provides techniques that can be applied to the analyses of precipitation isotopes in similar arid regions of the world. © 2018 John Wiley & Sons, Ltd.
IFN-γ-induced signal-on fluorescence aptasensors: from hybridization chain reaction amplification to 3D optical fiber sensing interface towards a deployable device for cytokine sensing
(Royal Society of Chemistry, 2019-04-29) Zhang, FY; Deng, F; Liu, GJ; Middleton, RJ; Inglis, DW; Anwer, A; Wang, S; Liu, GZ
Interferon-gamma (IFN-γ), a proinflammatory cytokine, has been used as an early indicator of multiple infectious diseases or tumors. In order to explore the detection capability of a commonly used anti-IFN-γ aptamer, a simple target induced strand-displacement aptasensing strategy was tested by introducing three different complementary strands and two different signal/quencher pairs. The Texas red/BHQ2-based sensor showed the best affinity constant (Kd) of 21.87 ng mL−1. It was found that the strand-displacement aptasensing strategy was impacted by the complementary position and length of the complementary strands. Additionally, the hybridization chain reaction (HCR) amplification strategy was introduced, yielding a 12-fold improved sensitivity of 0.45 ng mL−1. In order to further explore the sensing platform for spatially localized cytokine detection, the Texas red/BHQ2-based strand-displacement aptasensor was successfully fabricated on the 3D optical fiber surface to achieve a deployable sensing device for monitoring IFN-γ based on the fluorescence spots counting strategy. Finally, the three developed aptasensing strategies (strand-displacement strategy, HCR amplification strategy, 3D optical fiber aptasensor) were applied for detection of IFN-γ secreted by PBMCs with comparable results to those of ELISA. The deployable 3D optical fiber aptasensor with the superior sensitivity is potential to be used for detection of spatially localized IFN-γ in vivo. © 2019 The Royal Society of Chemistry
New insights on the mechanism of acid degradation of pea starch
(Elsevier, 2012-02-14) Wang, S; Blazek, J; Gilbert, EP; Copeland, L
The degradation of pea starch granules by acid hydrolysis has been investigated using a range of chemical and structural methods, namely through measuring changes in amylose content by both the iodine binding and concanavalin A precipitation methods, along with small angle X-ray scattering (SAXS), wide angle X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The relative crystallinity, intensity of the lamellar peak and the low-q scattering increased during the initial stages of acid hydrolysis, indicating early degradation of the amorphous regions (growth rings and lamellae). In the first 2 days of hydrolysis, there was a rapid decline in amylose content, a concomitant loss of precipitability of amylopectin by concanavalin A, and damage to the surface and internal granular structures was evident. These observations are consistent with both amylose and amylopectin being located on the surface of the granules and attacked simultaneously in the early stages of acid hydrolysis. The results are also consistent with amylose being more concentrated at the core of the granules. More extensive hydrolysis resulted in the simultaneous disruption of amorphous and crystalline regions, which was indicated by a decrease in lamellar peak intensity, decrease in interhelix peak intensity and no further increase in crystallinity. These results provide new insights into the organization of starch granules. (C) 2011 Elsevier Ltd.
A novel graphene oxide wrapped Na2Fe2(SO4)3/C cathode composite for long life and high energy density sodium‐ion batteries
(Wiley, 2018-08-06) Chen, MZ; Cortie, DL; Hu, Z; Jin, H; Wang, S; Gu, QF; Hua, WB; Wang, E; Lai, WH; Chen, L; Chou, SL; Wang, XL; Dou, SX
The cathode materials in the Na‐ion battery system are always the key issue obstructing wider application because of their relatively low specific capacity and low energy density. A graphene oxide (GO) wrapped composite, Na2Fe2(SO4)3@C@GO, is fabricated via a simple freeze‐drying method. The as‐prepared material can deliver a 3.8 V platform with discharge capacity of 107.9 mAh g−1 at 0.1 C (1 C = 120 mA g−1) as well as offering capacity retention above 90% at a discharge rate of 0.2 C after 300 cycles. The well‐constructed carbon network provides fast electron transfer rates, and thus, higher power density also can be achieved (75.1 mAh g−1 at 10 C). The interface contribution of GO and Na2Fe2(SO4)3 is recognized and studied via density function theory calculation. The Na storage mechanism is also investigated through in situ synchrotron X‐ray diffraction, and pseudocapacitance contributions are also demonstrated. The diffusion coefficient of Na+ ions is around 10−12–10−10.8 cm2 s−1 during cycling. The higher working voltage of this composite is mainly ascribed to the larger electronegativity of the element S. The research indicates that this well‐constructed composite would be a competitive candidate as a cathode material for Na‐ion batteries. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA.
Quantifying moisture recycling of a leeward oasis in arid central Asia using a Bayesian isotopic mixing model
(Elsevier, 2022-10) Wang, S; Wang, L; Zhang, MJ; Shi, Y; Hughes, CE; Crawford, J; Zhou, J; Qu, D
Locally recycled moisture from transpiration and surface evaporation is of great importance in the terrestrial hydrological cycle, especially in the widely distributed oases across arid central Asia. Quantitative assessment of the proportional contribution of recycled moisture to local precipitation, i.e., the recycling ratio, is useful to understand the land-air interaction as well as the anthropogenic impact on the regional water cycle. Here we analyzed the stable hydrogen and oxygen isotopes in precipitation samples collected at six stations across the Kaxgar-Yarkant Oasis in the western Tarim Basin of central Asia from April 2018 to June 2020. Using this data, the moisture recycling ratio in this typical oasis was assessed using a Bayesian three-component isotopic mixing model. For the plain stations, the annual weighted mean δ18O value in precipitation ranged from −5.94 ‰ to −1.46 ‰, and the mountain station has a lower annual mean precipitation isotopic ratio. The average recycling ratio during the summer months ranged between 17.0 % and 63.9 % for each sampling station in the Kaxgar-Yarkant Oasis, and the proportional contribution from transpiration ranged from 15.1 % to 61.3 %. The contribution of plant transpiration to local precipitation is much larger than that of surface evaporation. The recycled portion in total precipitation amount may increase the local precipitation under an oasis expansion background but is insufficient to change the arid background. In addition, the Bayesian isotopic mixing model is promising to determine the recycling ratio in an arid setting, and provides more spatial details than the climate reanalysis-based calculation. © 2022 Elsevier B.V.
Spatial and seasonal isotope variability in precipitation across China: monthly isoscapes based on regionalized fuzzy clustering
(American Meteorological Society, 2022-06-01) Wang, S; Lei, S; Zhang, MJ; Hughes, CE; Crawford, J; Liu, ZF; Qu, D
The spatial patterns of stable hydrogen and oxygen isotopes in precipitation (precipitation isoscapes) provide a geographic perspective to understand the atmospheric processes in modern environment and paleoclimate records. Here we compiled stable isotope data in modern precipitation at 223 sites across China and 48 in surrounding countries, and used regionalized fuzzy clustering to create monthly precipitation isoscapes for China (C-Isoscape). Based on regressions using spatial and climatic parameters for 12 months, the best-fitting equations were chosen for four climate clusters, and then the four layers were weighted using fuzzy membership. The moisture transportation path, controlled by the westerlies and the monsoon, results in different spatial and seasonal diversity of precipitation isotopes. Based on C-Isoscape, we determined a nationwide meteoric water line asδ2H = 7.4δ18O + 5.5 using least squares regression orδ2H = 8.0δ18O + 10.2 using precipitation weighted reduced major axis regression. Compared with previous global products, the C-Isoscape usually shows precipitation more enriched in18O and2H in summer and more depleted in winter for northwest China, while the C-Isoscape values are more enriched in heavy isotopes in most months for southwest China. The new monthly precipitation isoscapes provide an accurate and high-resolution mapping for Chinese precipitation isotopes, allowing for future intra-annual atmospheric process diagnostics using stable hydrogen and oxygen isotope in precipitation in the region. Ó 2022 American Meteorological Society.
Teasaponin improves leptin sensitivity in the prefrontal cortex of obese mice
(John Wiley and Sons, 2015-09-21) Yu, YH; Wu, YZ; Szabo, A; Wang, S; Yu, SJ; Wang, Q; Huang, XF
Scope Obesity impairs cognition, and the leptin-induced increase of brain-derived neurotrophic factor (BDNF) and neurogenesis. Tea consumption improves cognition and increases brain activation in the prefrontal cortex. Methods and results This study examined whether teasaponin, an active ingredient in tea, could improve memory and central leptin effects on neurogenesis in the prefrontal cortex of obese mice, and in vitro in cultured prefrontal cortical neurons. Teasaponin (10 mg/kg, intraperitoneal) for 21 days improved downstream leptin signaling (JAK2 and STAT3), and leptin's effect on BDNF, in the prefrontal cortex of high-fat diet (HFD) fed mice. Prefrontal cortical neurons were cultured with teasaponin and palmitic acid (the most abundant dietary saturated fatty acid) to examine their effects on neurogenesis and BDNF expression in response to leptin. Palmitic acid decreased leptin's effect on neurite outgrowth, postsynaptic density protein 95, and BDNF expression in cultured cortical neurons, which was reversed by teasaponin. Conclusion Teasaponin improved the leptin sensitivity of prefrontal cortical neurons in obese mice or when treated by palmitic acid. This in turn increased BDNF expression and neurite growth. Therefore, teasaponin supplementation may be used to prevent obesity-associated neurodegeneration and improve cognitive function. © 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
Turn-on fluorescence aptasensor on magnetic nanobeads for aflatoxin M1 detection based on an exonuclease III-assisted signal amplification strategy
(Multidisciplinary Digital Publishing Institute (MDPI), 2019-01-16) Zhang, FY; Liu, LY; Ni, SN; Deng, JK; Liu, GJ; Middleton, RJ; Inglis, DW; Wang, S; Liu, GZ
In order to satisfy the need for sensitive detection of Aflatoxin M1 (AFM1), we constructed a simple and signal-on fluorescence aptasensor based on an autocatalytic Exonuclease III (Exo III)-assisted signal amplification strategy. In this sensor, the DNA hybridization on magnetic nanobeads could be triggered by the target AFM1, resulting in the release of a single-stranded DNA to induce an Exo III-assisted signal amplification, in which numerous G-quadruplex structures would be produced and then associated with the fluorescent dye to generate significantly amplified fluorescence signals resulting in the increased sensitivity. Under the optimized conditions, this aptasensor was able to detect AFM1 with a practical detection limit of 9.73 ng kg−1 in milk samples. Furthermore, the prepared sensor was successfully used for detection of AFM1 in the commercially available milk samples with the recovery percentages ranging from 80.13% to 108.67%. Also, the sensor performance was evaluated by the commercial immunoassay kit with satisfactory results. © 2019 the Authors
Two-dimensional quantum universality in the spin-1/2 triangular-lattice quantum antiferromagnet Na2BaCo(PO4)2
(Proceedings of the National Academy of Sciences, 2022-12-15) Sheng, JM; Wang, L; Candini, A; Jiang, W; Huang, L; Xi, B; Zhao, J; Ge, H; Zhao, N; Fu, Y; Ren, J; Yang, J; Miao, P; Tong, X; Yu, D; Wang, S; Liu, Q; Kofu, M; Mole, RA; Biasiol, G; Yu, DH; Zaliznyak, IA; Mei, JW; Wu, L
An interplay of geometrical frustration and strong quantum fluctuations in a spin-1/2 triangular-lattice antiferromagnet (TAF) can lead to exotic quantum states. Here, we report the neutron-scattering, magnetization, specific heat, and magnetocaloric studies of the recently discovered spin-1/2 TAF Na2BaCo(PO4)2, which can be described by a spin-1/2 easy axis XXZ model. The zero-field neutron diffraction experiment reveals an incommensurate antiferromagnetic ground state with a significantly reduced ordered moment of about 0.54(2) μB/Co. Different magnetic phase diagrams with magnetic fields in the ab plane and along the easy c-axis were extracted based on the magnetic susceptibility, specific heat, and elastic neutron-scattering results. In addition, two-dimensional (2D) spin dispersion in the triangular plane was observed in the high-field polarized state, and microscopic exchange parameters of the spin Hamiltonian have been determined through the linear spin wave theory. Consistently, quantum critical behaviors with the universality class of d = 2 and νz = 1 were established in the vicinity of the saturation field, where a Bose–Einstein condensation (BEC) of diluted magnons occurs. The newly discovered quantum criticality and fractional magnetization phase in this ideal spin-1/2 TAF present exciting opportunities for exploring exotic quantum phenomena. © 2022 the Author(s). Published by PNAS. This article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND).

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