Enhanced corrosion and wear resistance properties of carbon fiber reinforced Ni-based composite coating by laser cladding

To enhance the wear resistance and corrosion resistance of Ni-based coatings, carbon fibers reinforced nickel-based composite coatings (CFs/Ni) were fabricated on the surface of 1Cr13 stainless steel by laser cladding (LC). The microstructure characteristics, microhardness, wear and corrosion performances of the composite coatings were investigated. The results show that CFs can effectively improve the corrosion and wear resistances of Ni-based coatings. With increasing laser scanning speed, the morphology of CFs in composite coatings is more integral and the corrosion and wear resistances of the composite coatings are improved. Especially, when laser scanning speed is increased to 8 mm/s, the average microhardness of the composite coating reaches up to 405 HV0.2, which is about 1.3 times higher than that of Ni-based coating. Moreover, the corrosion current density and the wear rate of the composite coating are only 7% and 55% of those of the Ni-based coating, respectively, which is attributed to the good properties and homogeneous distribution of CFs and finer microstructure of composite coating

Thermal optimality of net ecosystem exchange of carbon dioxide and underlying mechanisms

It is well established that individual organisms can acclimate and adapt to temperature to optimize their functioning. However, thermal optimization of ecosystems, as an assemblage of organisms, has not been examined at broad spatial and temporal scales. Here, we compiled data from 169 globally distributed sites of eddy covariance and quantified the temperature response functions of net ecosystem exchange (NEE), an ecosystem-level property, to determine whether NEE shows thermal optimality and to explore the underlying mechanisms. We found that the temperature response of NEE followed a peak curve, with the optimum temperature (corresponding to the maximum magnitude of NEE) being positively correlated with annual mean temperature over years and across sites. Shifts of the optimum temperature of NEE were mostly a result of temperature acclimation of gross primary productivity (upward shift of optimum temperature) rather than changes in the temperature sensitivity of ecosystem respiration. Ecosystem-level thermal optimality is a newly revealed ecosystem property, presumably reflecting associated evolutionary adaptation of organisms within ecosystems, and has the potential to significantly regulate ecosystemclimate change feedbacks. The thermal optimality of NEE has implications for understanding fundamental properties of ecosystems in changing environments and benchmarking global models.This is the publisher’s final pdf. The published article is copyrighted by New Phytologist Trust and can be found at: http://www.newphytologist.org/Keywords: Climate change, Temperature acclimation, Optimum temperature, Thermal optimality, Temperature adaptatio

A Simple Polypyrrole/Polyvinylidene Fluoride Membrane with Hydrophobic and Self-Floating Ability for Solar Water Evaporation

The traditional hydrophobic solarevaporator is generally obtained through the modification of alkyl or fluoroalkyl on the photothermal membrane. However, the modified groups can easily be oxidized in the long-term use process, resulting in the poor salt resistance and stability of photothermal membrane. In order to solve this problem, a simple polypyrrole/polyvinylidene fluoride membrane, consisting of an intrinsic hydrophobic support (polyvinylidene fluoride) and a photothermal material (polypyrrole), was fabricated by ultrasonically mixing and immersed precipitation. This photothermal membrane showed good self-floating ability in the process of water evaporation. In order to further improve the photothermal conversion efficiency, a micropyramid structure with antireflective ability was formed on the surface of membrane by template method. The micropyramids can enhance the absorption efficiency of incident light. The water evaporation rate reached 1.42 kg m−2 h−1 under 1 sun irradiation, and the photothermal conversion efficiency was 88.7%. The hydrophobic polyvinylidene fluoride ensures that NaCl cannot enter into membrane during the evaporation process of the brine, thus realizing the stability and salt resistance of polypyrrole/polyvinylidene fluoride in 3.5%wt and 10%wt NaCl solution

Motor Fault Diagnosis Based on Wavelet Transform

The wavelet transform theory is used to motor fault diagnosis in this paper, considering its characteristics of multi-resolution and stronger feature extraction ability than Fourier. The paper emphasizes de-noising and eliminating the singular value point of the wavelet transform in the non-stationary signal. And it makes a detailed and in-depth analysis about how to detect the frequency components of weak signal by using equivalent power spectrum of reconstruction signal, which is acquired by using the wavelet transform. Through the comparison analysis of the simulation signal and motor vibration signal’s experimental data, the corresponding energy of original signal’s equivalent power spectrum and reconstructing signal’s equivalent power spectrum are compared to determine the fault frequency, so as to accurately find out the motor fault. DOI: http://dx.doi.org/10.11591/telkomnika.v11i9.3288

Disrupted Timing of MET Signaling Derails the Developmental Maturation of Cortical Circuits and Leads to Altered Behavior in Mice

The molecular regulation of the temporal dynamics of circuit maturation is a key contributor to the emergence of normal structure-function relations. Developmental control of cortical MET receptor tyrosine kinase, expressed early postnatally in subpopulations of excitatory neurons, has a pronounced impact on the timing of glutamatergic synapse maturation and critical period plasticity. Here, we show that using a controllable overexpression (cto-Met) transgenic mouse, extending the duration of MET signaling after endogenous Met is switched off leads to altered molecular constitution of synaptic proteins, persistent activation of small GTPases Cdc42 and Rac1, and sustained inhibitory phosphorylation of cofilin. These molecular changes are accompanied by an increase in the density of immature dendritic spines, impaired cortical circuit maturation of prefrontal cortex layer 5 projection neurons, and altered laminar excitatory connectivity. Two photon in vivo imaging of dendritic spines reveals that cto-Met enhances de novo spine formation while inhibiting spine elimination. Extending MET signaling for two weeks in developing cortical circuits leads to pronounced repetitive activity and impaired social interactions in adult mice. Collectively, our data revealed that temporally controlled MET signaling as a critical mechanism for controlling cortical circuit development and emergence of normal behavior