The magnetic gradient and curvature drift of energetic ions can form a longitudinal electric current around a planet known as the ring current, that has been observed in the intrinsic magnetospheres ...of Earth, Jupiter, and Saturn. However, there is still a lack of observational evidence of ring current in Mercury's magnetosphere, which has a significantly weaker dipole magnetic field. Under such conditions, charged particles are thought to be efficiently lost through magnetopause shadowing and/or directly impact the planetary surface. Here, we present the observational evidence of Mercury's ring current by analysing particle measurements from MErcury Surface, Space Environment, GEochemistry, and Ranging (MESSENGER) spacecraft. The ring current is bifurcated because of the dayside off-equatorial magnetic minima. Test-particle simulation with Mercury's dynamic magnetospheric magnetic field model (KT17 model) validates this morphology. The ring current energy exceeds Formula: see text J during active times, indicating that magnetic storms may also occur on Mercury.
The synchrotron x-ray absorption near edge structures (XANES) technique was used in conjunction with first-principles calculations to characterize Al-doped ZnO films. Standard characterizations ...revealed that the amount of carrier concentration and mobility depend on the growth conditions, i.e. H(2) (or O(2))/Ar gas ratio and Al concentration. First-principles calculations showed that Al energetically prefers to substitute on the Zn site, forming a donor Al(Zn), over being an interstitial (Al(i)). The measured Al K-edge XANES spectra are in good agreement with the simulated spectra of Al(Zn), indicating that the majority of Al atoms are substituting for Zn. The reduction in carrier concentration or mobility in some samples can be attributed to the Al(Zn)-V(Zn) and 2Al(Zn)-V(Zn) complex formations that have similar XANES features. In addition, XANES of some samples showed additional features that are the indication of some α-Al(2)O(3) or nAl(Zn)-O(i) formation, explaining their poorer conductivity.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
A series of novel Co-free AlxCrFeMnNi (x = 0.5–0.8) high-entropy alloys (HEAs) with trimodal distributions of coherent B2 precipitates was fabricated. A fundamental investigation on the ...microstructural evolution and mechanical properties of these trimodal alloys was conducted. Structural characterization shows that these HEAs possess complex microstructures consisting of a disordered body-centered-cubic (BCC) matrix and trimodal-size distributions of the ordered coherent B2 precipitates, (1) the primary B2 (p-B2) precipitates with a mean length of ∼2 μm located in the interdendritic region, (2) the secondary B2 (s-B2) precipitates with a mean diameter of ∼450 nm, and (3) the tertiary B2 (t-B2) precipitates with a mean diameter of ∼20 nm located in the dendritic region. The trimodal HEAs exhibit a good combination of high compressive yield strengths of 1091–1200 MPa and the large plasticity (>45%). The increments of the yield strengths caused by different strengthening mechanisms have been quantitatively and respectively estimated and compared with the experimental measurements. The study of the present trimodal BCC-B2 HEAs can provide a useful guidance for the future development of multimodal BCC-based HEAs with excellent properties.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
ABSTRACT Solar flares produce radiation that can have an almost immediate effect on the near-Earth environment, making it crucial to forecast flares in order to mitigate their negative effects. The ...number of published approaches to flare forecasting using photospheric magnetic field observations has proliferated, with varying claims about how well each works. Because of the different analysis techniques and data sets used, it is essentially impossible to compare the results from the literature. This problem is exacerbated by the low event rates of large solar flares. The challenges of forecasting rare events have long been recognized in the meteorology community, but have yet to be fully acknowledged by the space weather community. During the interagency workshop on "all clear" forecasts held in Boulder, CO in 2009, the performance of a number of existing algorithms was compared on common data sets, specifically line-of-sight magnetic field and continuum intensity images from the Michelson Doppler Imager, with consistent definitions of what constitutes an event. We demonstrate the importance of making such systematic comparisons, and of using standard verification statistics to determine what constitutes a good prediction scheme. When a comparison was made in this fashion, no one method clearly outperformed all others, which may in part be due to the strong correlations among the parameters used by different methods to characterize an active region. For M-class flares and above, the set of methods tends toward a weakly positive skill score (as measured with several distinct metrics), with no participating method proving substantially better than climatological forecasts.
Chemical reactions typically proceed via stochastic encounters between reactants. Going beyond this paradigm, we combined exactly two atoms in a single, controlled reaction. The experimental ...apparatus traps two individual laser-cooled atoms one sodium (Na) and one cesium (Cs) in separate optical tweezers and then merges them into one optical dipole trap. Subsequently, photoassociation forms an excited-state NaCs molecule. The discovery of previously unseen resonances near the molecular dissociation threshold and measurement of collision rates are enabled by the tightly trapped ultracold sample of atoms. As laser-cooling and trapping capabilities are extended to more elements, the technique will enable the study of more diverse, and eventually more complex, molecules in an isolated environment, as well as synthesis of designer molecules for qubits.
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BFBNIB, NMLJ, NUK, ODKLJ, PNG, SAZU, UL, UM, UPUK
In this study, the effects of microstructure, temperature and dwell time in a loading cycle on low cycle fatigue (LCF) and stress relaxation behaviours of a powder metallurgy Ni-based superalloy ...(i.e. FGH4098) for aeroengine turbine disc application were studied along with detailed microscopic characterisation of fracture features and deformation substructures. The results indicate that the LCF failure mode of FGH4098 transits from transgranular to intergranular with the increase of temperature and dwell time, and the propensity of intergranular fatigue cracking is higher in fine-grained FGH4098. FGH4098 predominantly shows cyclic hardening behaviour which is mainly related to dislocation interactions. With the increase of temperature and/or dwell time, the cyclic hardening behaviour diminishes to some extent due to the increasing shearing of secondary γ′ precipitates by stacking fault and partial dislocation pairs. Similarly, stress relaxation in FGH4098 is also associated with the shearing of γ′ precipitates and becomes more prominent at high temperature with long dwell period. Micro-twinning may also contribute to stress relaxation at 750 °C.
•Micro-mechanisms of cyclic deformation and stress relaxation behaviours in FGH4098 are investigated by SEM and TEM.•FGH4098 predominantly shows cyclic hardening behaviour due to dislocation interactions.•Cyclic hardening diminishes as temperature and dwell time increases due to the increasing shearing of secondary γ′.•Shearing of γ′ and micro-twinning contributes to stress relaxation at high temperature and long dwell period..
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Accurate and robust pathological image analysis for colorectal cancer (CRC) diagnosis is time-consuming and knowledge-intensive, but is essential for CRC patients' treatment. The current heavy ...workload of pathologists in clinics/hospitals may easily lead to unconscious misdiagnosis of CRC based on daily image analyses.
Based on a state-of-the-art transfer-learned deep convolutional neural network in artificial intelligence (AI), we proposed a novel patch aggregation strategy for clinic CRC diagnosis using weakly labeled pathological whole-slide image (WSI) patches. This approach was trained and validated using an unprecedented and enormously large number of 170,099 patches, > 14,680 WSIs, from > 9631 subjects that covered diverse and representative clinical cases from multi-independent-sources across China, the USA, and Germany.
Our innovative AI tool consistently and nearly perfectly agreed with (average Kappa statistic 0.896) and even often better than most of the experienced expert pathologists when tested in diagnosing CRC WSIs from multicenters. The average area under the receiver operating characteristics curve (AUC) of AI was greater than that of the pathologists (0.988 vs 0.970) and achieved the best performance among the application of other AI methods to CRC diagnosis. Our AI-generated heatmap highlights the image regions of cancer tissue/cells.
This first-ever generalizable AI system can handle large amounts of WSIs consistently and robustly without potential bias due to fatigue commonly experienced by clinical pathologists. It will drastically alleviate the heavy clinical burden of daily pathology diagnosis and improve the treatment for CRC patients. This tool is generalizable to other cancer diagnosis based on image recognition.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A new set of AlFeCoNiCx (x = 0, 0.02, 0.04, 0.08, 0.17) high-entropy alloys (HEAs) were designed and fabricated. The microstructure, phase evolution and mechanical behaviors of the alloys were ...systematically investigated. Results show that the matrix alloy exhibits coarse columnar structure, while the C-doped alloys exhibit typical dendrite microstructure. The dendritic region (DR) is composed of single B2 phase, while the interdendritic region (ID) consists of FCC and E21 phases and presents an ultrafine cellar structure caused by the coexisting of ordering and spinodal decomposition. Interestingly, both the strength and compressive strain greatly increased with the increase of carbon content. Particularly, the AlFeCoNiC0.08 HEA possessed the most excellent mechanical properties, superior to many other HEAs with the yield strength, fracture strength, and fracture strain as high as 1115 MPa, 2517 MPa and 48.8%, respectively. The mechanical properties of the AlFeCoNiC0.17 alloy were weakened by the presence of graphite. Further, it is found that there is close relationship between the fracture morphology and alloy properties. Overall, in this study the improved microstructure and mechanical properties of the AlFeCoNi HEA have been accomplished by carbon doping, and our findings could shed light on a new alloy-design route to achieve bulk ultrafine structure materials with desired properties via the direct solidification.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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