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Automatic ship detection in SAR images plays an essential role in both military and civilian fields. However, most of the existing deep learning detection methods introduce complex models and huge calculations while improving the detection accuracy, which is not conducive to the application of real-time ship detection. To solve this problem, an efficient lightweight network YOLO-Lite is proposed for SAR ship detection in this paper. First, a lightweight feature enhancement backbone (LFEBNet) is designed to reduce the amount of calculation. Additionally, a channel and position enhancement attention (CPEA) module is constructed and embedded into the backbone network to more accurately locate the target location by capturing the positional information. Second, an enhanced spatial pyramid pooling (EnSPP) module is customized to enhance the expression ability of features and address the position information loss of small SAR ships in high-level features. Third, we construct an effective multi-scale feature fusion network (MFFNet) with two feature fusion channels to obtain feature maps with more position and semantic information. Furthermore, a novel confidence loss function is proposed to effectively improve the SAR ship target detection accuracy. Extensive experiments on SSDD and SAR ship datasets verify the effectiveness of our YOLO-Lite, which can not only accurately detect SAR ships in different backgrounds but can also realize a lightweight architecture with low computation cost. [ABSTRACT FROM AUTHOR]

Solar-induced chlorophyll fluorescence (SIF) observations from space have shown close relationships with terrestrial photosynthesis rates. SIF originates from the light reactions of photosynthesis, whereas carbon fixation takes place during the dark reactions of photosynthesis. Questions remain regarding whether SIF is able to track changes in the efficiency of the dark reactions in photosynthesis. Using concurrent measurements of leaf-scale gas exchange, pulse amplitude-modulated (PAM) fluorescence, and fluorescence spectral radiances, we found that both far-red fluorescence radiances and PAM fluorescence yields responded rapidly to changes in photosynthetic carbon assimilation due to changes in environmental factors or induced stomatal closure under constant light conditions. Uncertainties in outgoing and incoming irradiance mismatch for SIF measurements may very likely obscure the contributions of the dark reactions, thereby causing the inconsistent findings previously reported, which were no change in far-red SIF and PAM fluorescence yields after clear reductions in the photosynthetic carbon assimilation efficiency of dark reactions. Our results confirm that high-quality SIF measurements have the potential to provide insights into the dark reactions of photosynthesis. This study is particularly relevant for better interpreting satellite SIF observations that are obtained under roughly constant overpass times and relatively stable light intensities. [ABSTRACT FROM AUTHOR]

We evaluated the ability of different fluorescent indicators by various analytical instruments, including a laser scanning confocal microscope (LSCM), fluorescence plate reader, and flow cytometer (FCM), to measure the mitochondrial membrane potential (ΔΨm) of cardiac H9c2 cells during oxidative stress-induced mitochondrial injury. The mitochondrial oxygen consumption rate and a transmission electron microscope were used to detect changes in mitochondrial functions and morphology, respectively. Cardiac H9c2 cells were exposed to H2O2 (500, 750, 1000, and 1250 μM) to induce mitochondrial oxidative stress injury, and fluorescent indicators including tetramethyl rhodamine ethyl ester (TMRE), 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolocarbocyanine iodide (JC-1), and rhodamine 123 (R123) were used to detect changes in ΔΨm using an LSCM, fluorescence plate reader, and FCM. The decrease in ΔΨm caused by H2O2 was determined by endpoint and dynamic analyses after staining with JC-1 or TMRE. With the R123 probe, the LSCM could only detect the change in ΔΨm caused by 1000 μM H2O2. Moreover, R123 was less effective than JC-1 and TMRE for measurement of ΔΨm by the LSCM. Our data indicated that an LSCM is the most suitable instrument to detect dynamic changes in ΔΨm, whereas all three instruments can detect ΔΨm at the endpoint. [ABSTRACT FROM AUTHOR]

Na3V2(PO4)3 owns stable three-dimensional open framework and delivers a theoretical capacity of 117.6 mAh/g with a voltage plateau at 3.4 V (vs. Na+/Na). However, the voltage plateau at 1.6 V (vs. Na+/Na) corresponding to the V2+/V3+ redox couple can also deliver a theoretical capacity of 59 mAh/g. Herein, the operating voltage window of Na3V2(PO4)3 is extended to fully utilize V2+/V3+/V4+ redox couples. In 1.0–4.0 V (vs. Na+/Na), Na3V2(PO4)3 shows a high initial capacity but an inferior cycling stability, which is different from the scenario (low capacity but high stability) of 2.5–4.0 V (vs. Na+/Na). In comparison, Na3V2(PO4)3 delivers an initial capacity of 140.3 mAh/g at 200 mA/g in 1.4–4.0 V (vs. Na+/Na) and maintains a reversible capacity of 106.2 mAh/g after 600 cycles. At 20 mA/g, Na3V2(PO4)3 shows a reversible capacity of 135 mAh/g in 1.4–4.0 V (vs. Na+/Na) after 100 cycles. Meanwhile, operando X-ray diffraction is utilized to explore storage mechanisms of Na3V2(PO4)3 in different voltage ranges. The results show that the cathode reactions follow a biphasic mechanism at both 3.4 and 1.6 V (vs. Na+/Na), associated with the reversible transformation of Na3V2(PO4)3 ↔ NaV2(PO4)3 and Na3V2(PO4)3 ↔ Na4V2(PO4)3, respectively. [ABSTRACT FROM AUTHOR]

The statistic short-range order (SRO) structure parameters of the Ga-Sn alloy melt are obtained with the X-ray diffractometer. The local atomic and electronic structures around the absorption atoms of Ga and Sn elements are detected by X-ray absorption fine structure spectrum. Centered on the absorption atom, the atom cluster structure was dissected and the atom cluster model was established. Unlike the ordinary liquid metal structure, the local atomic structure demonstrates that the liquid Ga-Sn alloy is not characterized by a dominant icosahedral short-range order. Specially, Sn atoms aggregate in Ga91.6Sn8.4 alloy, giving rise to a phase separation that exhibits compositional disorder. [ABSTRACT FROM AUTHOR]

Viscosities and liquid structures of Ag100-xSix (x=5, 7, 9, 11, at.%) melts were studied by an oscillating viscometer and an X-ray diffractometer. Temperature dependence of viscosity and the correlation length D all can be fitted well by Arrhenius equation. The activation energy for viscous flow Ea,V and the activation energy for structural evolution Ea,D all increase with increasing Si content. Above the liquidus temperature, the coordination number Ns, the correlation radius rc, the atom numbers in the cluster Nc and the correlation length D all increase with decreasing temperature. Among them, rc and Nc show a significant increase near the liquidus temperature. In the liquid-solid interval, the structural parameters show different behaviors with temperature due to the influence of the liquid-solid equilibrium reaction of the precipitation phase. Based on the investigated viscosity and structure, the fragility parameter of superheated melts M and the structural fragility parameter Fs were calculated. Both M and Fs increase with increasing silicon content. This work provides us a further understanding of the liquid-solid transition from the perspective of liquid structure and dynamics. [ABSTRACT FROM AUTHOR]

We investigated the influence of minor additions of B, Al and Nb that have representative atomic sizes on the glass forming ability (GFA) and stability of Zr-Ni amorphous alloys during mechanical alloying. The results show that the minor addition of B, Al or Nb does not shorten the initial time of the full amorphization reaction or improve the glass forming ability of the Zr-Ni alloys at a low rotation speed. However, B addition can effectively improve the mechanical stability of the amorphous phase against mechanically induced crystallization. Furthermore, the amorphous phase gradually transforms into a metastable fcc-phase with increasing milling time. The addition of Al and Nb that have similar atomic sizes has a similar effect on the GFA and the mechanical stability of the Zr-Ni amorphous phase. Moreover, Al and Nb addition can alter the crystallization behavior and improve the thermal stability of the Zr-Ni amorphous phase. [ABSTRACT FROM AUTHOR]

In order to solve the problems of long-term image acquisition time and massive data processing in a terahertz time domain spectroscopy imaging system, a novel fast terahertz imaging model, combined with group sparsity and nonlocal self-similarity (GSNS), is proposed in this paper. In GSNS, the structure similarity and sparsity of image patches in both two-dimensional and three-dimensional space are utilized to obtain high-quality terahertz images. It has the advantages of detail clarity and edge preservation. Furthermore, to overcome the high computational costs of matrix inversion in traditional split Bregman iteration, an acceleration scheme based on conjugate gradient method is proposed to solve the terahertz imaging model more efficiently. Experiments results demonstrate that the proposed approach can lead to better terahertz image reconstruction performance at low sampling rates. [ABSTRACT FROM AUTHOR]

In order to shorten the long-term image acquisition time of the terahertz time domain spectroscopy imaging system while ensuring the imaging quality, a hybrid sparsity model (HSM) is proposed for fast terahertz imaging in this paper, which incorporates both intrinsic sparsity prior and nonlocal self-similarity constraints in a unified statistical model. In HSM, a weighted exponentiation shift-invariant wavelet transform is introduced to enhance the sparsity of the terahertz image. Simultaneously, the nonlocal self-similarity by means of the three-dimensional sparsity in the transform domain is exploited to ensure high-quality terahertz image reconstruction. Finally, a new split Bregman-based iteration algorithm is developed to solve the terahertz imaging model more efficiently. Experiments are presented to verify the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

The dynamic viscosities of In-Bi and Ag-Yb alloy systems are measured by the torsional oscillation viscometer and the corresponding melt fragilities (M) are calculated from the temperature dependence of viscosities fitted by the Arrhenius equation. It was found that the melt fragility of the intermetallics is larger than that of the alloys with near-intermetallic compositions, but is smaller than that of the alloys with near-intermetallic compositions with a peritectic reaction. From the thermodynamics and kinetics points of view, the origins for the compositions near intermetallics as potential hosts of glass formers were well demonstrated. Our study confirms the universality of melt fragility and gives implications on the physical mechanisms for the glass forming alloys. [ABSTRACT FROM AUTHOR]

The melt structures and viscosities of Ga-In alloys were investigated by an x-ray diffractometer and a torsional oscillation viscometer. A difference in the temperature dependence of the viscosity between the supercooled and the superheated melt of Ga-In alloys was detected. Based on the concept of the melt fragility, we find that the fragility of the supercooled melt is larger than that of the superheated melt in this alloy system. Furthermore, the length of gallium covalent bond is larger in the supercooled melt. The cluster abruptly becomes much bigger, and the ordering degree increases obviously near the liquidus with decreasing temperature. This work provides a further understanding on the liquid-solid transition under the supercooled condition from the point of view of the melt dynamics. [ABSTRACT FROM AUTHOR]

In this work, we have explored the potential applications of pure and various doped Mg(AlH4)2 as Li-ion battery conversion electrode materials using density functional theory (DFT) calculations. Through the comparisons of the electrochemical specific capacity, the volume change, the average voltage, and the electronic bandgap, the Li-doped material is found to have a smaller bandgap and lower average voltage than the pure system. The theoretical specific capacity of the Li-doped material is 2547.64 mAhg−1 with a volume change of 3.76% involving the electrode conversion reaction. The underlying reason for property improvement has been analyzed by calculating the electronic structures. The strong hybridization between Lis-state with H s-state influences the performance of the doped material. This theoretical research is proposed to help the design and modification of better light-metal hydride materials for Li-ion battery conversion electrode applications. [ABSTRACT FROM AUTHOR]

The local structures in the normal and undercooled liquid eutectic Ga-In alloy are investigated by using X-ray absorption spectroscope (XAS), X-ray diffractometer (XRD) and the ab initio molecular dynamics (AIMD) simulations. The results from these three techniques all indicate that the nearest-neighbor coordination number decreases with decreasing temperature in the liquid eutectic Ga-In alloy. Moreover, the nearest-neighbor interatomic distance increases and the local atomic packing density decreases with decreasing temperature. The X-ray absorption near edge structure (XANES) measurement shows that the atomic rearrangement at the undercooled temperature results in the formation of low-coordinated polyhedron clusters with high symmetries. This finding provides a new perspective for understanding the liquid-solid transition in undercooled conditions. [ABSTRACT FROM AUTHOR]