In this report, nanoporous anodic nickel-based thin film was prepared by a facile electrochemical approach in a fluoride containing electrolyte. The morphology, crystalline structure and electrochemical performance of the as-anodised film were investigated by scanning electron microscope, X-ray diffraction and an electrochemical workstation. The influence of processing conditions such as anodisation voltage, fluorine ion concentration and acid concentration were studied and found to have a significant effect on the capacitance of as-anodised nickel-based film. Meanwhile, the time of the anodisation is also a key factor in the performance of the nickel-based film. The specific capacitance of anodic nanoporous thin film prepared at optimised condition (1 wt-% NH4F + 80 wt-% H3PO4, 3·5 V for 45 minutes) reached 225 mF cm−2 at the scan rate of 100 mV s−1.
Nanosized Ni_(0.5)Zn_(0.5)Fe_2O_4 ferrite powder was prepared by co-precipitation method.The spinel phase transition was observed by X-ray diffraction(XRD) after sintering at 900 ℃.Magnetic measurements show that the saturation magnetization of NiZn ferrite is σ_s=68 emu/g,residual magnetization σ_r=2.36 emu/g,coercive force H_C=50 Oe by vibrating sample magnetometer(VSM).The saturation magnetization σ_s=68 emu/g of the nanosized ferrite is one time higher than that of commercial ferrite,which indicates the ferrite may have an important role in application.
Cu/Si composite is an ideal material for electronic packaging owing to its excellent thermophysical and mechanical properties.Especially,its high thermal conductivity can fulfill the requirements of quick elimination of heat of high power devices.However,because of the severe diffusion and reaction between Cu and Si,the Cu-Si compound replaces the Cu and Si phases during the powder metallurgy fabrication at elevated temperature.Therefore,the crucial issue of Cu/Si composite fabrication is to control the Cu-Si diffusion and reaction.In this paper,the Cu/Si composites were fabricated using pretreated films on Si powder formed in Al_2O_3/TiO_2 sol as a diffusion barrier to prevent Cu-Si reaction.The phases,microstructures and properties of Cu/Si composites were investigated. The results indicate that Cu/Si composites on which Si powders are pretreated by sol-gel are primarily composed of Cu,Si,and a few Cu_3Si phases.The hardness of the composite is 147HV0.1,and the thermal diffusivity at room temperature is 26.4 mm~2/s.Cu and Si atoms diffuse via.the defects in film and react to form Cu Si compound in local regions at Cu/Si interface during sintering.However,only Cu_3Si phase is detected in the composite on which the Si powder is not pretreated,and no Cu or Si trace is found.The hardness is as high as 399HV0.1,but the thermal diffusivity at room temperature is only 3.0 mm~2/s.Therefore,sol-gel pretreatment on Si powders can effectively reduce the Cu-Si reaction and protect the Cu and Si phases in composites so as to elevate the thermal conductivity.
While online shopping has various forms and is convenient and fast, the harm to consumers' online shopping rights is endless, and there is a clear need for reasonable and effective online shopping risk assessment. At present, the uneven distribution of commodity related indicator data in e-commerce platforms and the differences in risks contained in different data intervals pose challenges to online shopping risk assessment. This article first divides online shopping products into risk levels through data consistency processing and K-means clustering. Then, an improved Bayesian evaluation based on indicator grading weighting is used to evaluate online shopping risks. The weight is calculated using the Jaccard coefficient according to the impact of each evaluation indicator on the evaluation results at different risk levels, and the average weight for the same risk level is 1. Finally, using data related to a smartphone from an e-commerce platform for evaluation and verification, and comparing the accuracy of evaluation with other algorithms, this article can effectively analyze the correlation between evaluation indicators and online shopping risk assessment results, reduce the impact of introducing weights on classification results, and improve the accuracy of the model in classifying minority samples.
This paper based on wavelet transform and non-wavelet transform established ARMA models to fit the daily closing price of Shanghai and Shenzhen 300 index and do a short-term forecast. It also compared their normalized mean square error (NMSE). Results display that due to the characte- ristics of wavelet transform which are good time frequency localization and its multi-resolution features, combined forecast model for short-term forecast of Shanghai and Shenzhen 300 index is superior to single forecast model.
Abstract Objective —To determine the prevalence of Mycoplasma suis infection in swine, swine-farm workers, and swine veterinarians in Shanghai, China. Sample Population —172 swine and 65 workers and veterinarians from 19 commercial swine farms. Procedures —Blood samples were collected from all study subjects. Blood samples were examined for the presence of M suis by means of compound and scanning electron microscopy. A species-specific PCR assay was developed for detection of M suis DNA extracted from blood samples. Relationships between infection status of swine and sex, age, geographic location, and clinical signs of disease were evaluated by use of a C 2 test. The phylogenetic relationship between partial 16S ribosomal RNA (rRNA) sequences from swine and human isolates of M suis was determined. Results —86% (148/172) of swine and 49% (32/65) of humans had positive PCR assay results for M suis infection. Swine infection status was not associated with any variable, with the exception of pyrexia and subcutaneous bleeding. The partial 16S rRNA sequences from human and swine isolates of M suis were 98% homologous and in the same phylogenetic cluster as a previously identified swine isolate of M suis . Conclusions and Clinical Relevance —A large proportion of swine and humans in close contact with those swine were infected with M suis in Shanghai, China. The close phylogenetic relationship between swine and human isolates of M suis suggested possible interspecies transmission; however, additional research is required to better assess that possibility.
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