Quantitative analysis modeling for the Chem Cam spectral data based on laser-induced breakdown spectroscopy using convolutional neural network

Laser-induced breakdown spectroscopy(LIBS)has been applied to many fields for the quantitative analysis of diverse materials.Improving the prediction accuracy of LIBS regression models is still of great significance for the Mars exploration in the near future.In this study,we explored the quantitative analysis of LIBS for the one-dimensional Chem Cam(an instrument containing a LIBS spectrometer and a Remote Micro-Imager)spectral data whose spectra are produced by the Chem Cam team using LIBS under the Mars-like atmospheric conditions.We constructed a convolutional neural network(CNN)regression model with unified parameters for all oxides,which is efficient and concise.CNN that has the excellent capability of feature extraction can effectively overcome the chemical matrix effects that impede the prediction accuracy of regression models.Firstly,we explored the effects of four activation functions on the performance of the CNN model.The results show that the CNN model with the hyperbolic tangent(tanh)function outperforms the CNN models with the other activation functions(the rectified linear unit function,the linear function and the Sigmoid function).Secondly,we compared the performance among the CNN models using different optimization methods.The CNN model with the stochastic gradient descent optimization and the initial learning rate?=?0.0005 achieves satisfactory performance compared to the other CNN models.Finally,we compared the performance of the CNN model,the model based on support vector regression(SVR)and the model based on partial least square regression(PLSR).The results exhibit the CNN model is superior to the SVR model and the PLSR model for all oxides.Based on the above analysis,we conclude the CNN regression model can effectively improve the prediction accuracy of LIBS.

Heralded entanglement between error-protected logical qubits for fault-tolerant distributed quantum computing

Quantum error correction is essential for achieving reliable quantum information processing tasks,as it can mitigate the detrimental effects of noise by encoding single-qubit information into a larger quantum system.However,the generation of distributed entanglement between logical qubits located within two spatially separated nodes presents a significant resource-intensive challenge that has yet to be overcome.Here we present a heralded protocol for generating distributed entanglement between two nonlocal error-protected logical qubits.A high-dimensional single photon can evolve physical qubits into a logical qubit that entangles with the photon and then converts logical qubit-photon entanglement into entanglement between two logical qubits,when the photon state is properly tuned and an effective photon-spin interface between single photons and individual spins is exploited.Furthermore,the success of the entanglement generation is heralded by the detection of the photon,and the corresponding efficiency can,in principle,approach unity.These distinguished features make our protocol highly appealing for future large-scale quantum technologies.

Antioxidant biocompatible composite collagen dressing for diabetic wound healing in rat model

Associated with persistent oxidative stress,altered inflammatory responses,poor angiogenesis and epithelization,wound healing in diabetic patients is impaired.N-acetylcysteine(NAC)is reported to resist excess reactive oxygen species(ROS)production,prompt angiogenesis and maturation of the epidermis.Studies have revealed that graphene oxide(GO)can regulate cellular behavior and form cross-links with naturally biodegradable polymers such as collagen(COL)to construct composite scaffolds.Here,we reported a COL-based implantable scaffold containing a mixture of GO capable of the sustained delivery of NAC to evaluate the wound healing in diabetic rats.The morphological,physical characteristics,biocompatibility and NAC release profile of the GO-COL-NAC(GCN)scaffold were evaluated in vitro.Wound healing studies were performed on a 20mm dorsal full-skin defect of streptozotocin(STZ)-induced diabetic rats.The injured skin tissue was removed at the 18th day post-surgery for histological analysis and determination of glutathione peroxidase(GPx),catalase(CAT)and superoxide dismutase(SOD)activity.In diabetic rats,we confirmed that the GCN scaffold presented a beneficial effect in enhancing the wound healing process.Additionally,due to the sustained release of NAC,the scaffold may potentially induce the antioxidant defense system,upregulating the expression levels of the antioxidant enzymes in the wound tissue.The findings revealed that the antioxidant biocompatible composite collagen dressing could not only deliver NAC in situ for ROS inhibition but also promote the wound healing process.This scaffold with valuable therapy potential might enrich the approaches for surgeon in diabetic wound treatment in the future.

PC4 serves as a negative regulator of skin wound healing in mice

Background:Human positive cofactor 4(PC4)was initially characterized as a multifunctional transcriptional cofactor,but its role in skin wound healing is still unclear.The purpose of this study was to explore the role of PC4 in skin wound healing through PC4 knock-in mouse model.Methods:A PC4 knock-in mouse model(PC4^(+/+))with a dorsal full-thickness wound was used to investigate the biological functions of PC4 in skin wound healing.Quantitative PCR,Western blot analysis and immunohistochemistry were performed to evaluate the expression of PC4;Sirius red staining and immunofluorescence were performed to explore the change of collagen deposition and angiogenesis.Proliferation and apoptosis were detected using Ki67 staining and TUNEL assay.Primary dermal fibroblasts were isolated from mouse skin to perform cell scratch experiments,cck-8 assay and colony formation assay.Results:The PC4^(+/+)mice were fertile and did not display overt abnormalities but showed an obvious delay in cutaneous healing of dorsal skin.Histological staining showed insufficient re-epithelialization,decreased angiogenesis and collagen deposition,increased apoptosis and decreased cell proliferation in PC4^(+/+)skin.Our data also showed decreased migration rate and proliferation ability in cultured primary fibroblasts from PC4^(+/+)mice in vitro.Conclusions:This study suggests that PC4 might serve as a negative regulator of skin wound healing in mice.

China's FDI Net Inflow and Deterioration of Terms of Trade: Paradox and Explanation

Starting from the contradiction between China＇s sustained growth in joreign direct investment （FDI） net inflow and deterioration of the terms of trade, this paper analyzes the characteristics of FDI sectoral structure since the 1990. Moreover, considering the international market competitive environment, this paper gives a concrete analysis of the influence mechanism and concludes that the flowing of FDl into labor-intensive export sectors caused the deterioration of China＇s terms of trade. To improve its terms of trade, China needs to direct FDI inflow into capital- and technology-intensive sectors and service sectors.

Enhancement of Soil Discharge Channels on Potential Surrounding Buried Cables Under Impulsive Currents

Substations have a large number of signal transmission cables beneath the ground.Both the insulation safety and signal reliability of the cables are affected severely by the electromagnetic field.Under high-amplitude impulsive currents,the dispersion of currents can cause soil discharge and thus cause unexpected distortions in an electromagnetic field.This paper focuses on the distortions of the electric field.In general,soil discharge channels occur in the vicinity of the independent rod.Closer development of the channel might enhance the electric field distribution and the potential surrounding the outer insulation of the cables(i.e.the surface potential on the cable).Therefore,this paper establishes a platform for observing the soil discharge channel and measuring the surface potential.Direction characteristic of the channel is extracted from the captured image of soil discharge channels and the surface potential is obtained by the measured coupling capacitive current on the shield experimentally.This paper also presents an improved model considering a dynamic growing discharge channel for the transient analysis of the grounding electrode.Study results show the surface potential increases as the discharge channel approaches the cable.To quantify this enhancement effect,the ratio of the highest to the lowest value of surface potential in different directions is taken as the multiple of the surface potential increase.The calculated multiples of the surface potential increase are in the range of 1 to 1.64 times under different conditions by the improved model.Therefore,taking the soil discharge channel into account is helpful to accurately analyze the impulsive interference of buried cables.

China's Construction Land Expansion and Economic Growth:A Capital-output Ratio Based Analysis

Since 2003, the Chinese Government has included land policy as an important component of macroeconomic policy. The present paper analyzes the impact of the expansion of construction land on economic growth in terms of the capital-output ratio. Using provincial panel data for China from 1999to 2005, we conclude that the excess expansion of China＇s construction land led to an increase in the capital-output ratio. Therefore, expanding construction land has made little contribution to economic growth. This paper argues that contractionary land policy does not deter high economic growth, and is a necessary condition for sustainable economic growth.

Platinum–P(BFPy) 3 -catalyzed regioselective diboration of terminal alkynes with (pin)B–B (aam)

An unsymmetrical diboron,(pin)B–B(aam),is smoothly added across a carbon–carbon triple bond of various terminal alkynes under platinum catalysis,resulting in the regio-and stereoselective formation of cis-vic-diborylalkenes via B(aam)-installation at the terminal carbon.The use of a highly electron-deficient triarylphosphine ligand,P(BFPy)_(3),is indispensable for the regiocontrol,and electron-deficiency in ligands has been proven to be closely correlated with the regioselectivity.