Heterostructured bimetallic phosphide nanowire arrays with latticetorsion interfaces for efficient overall water splitting

Designing cost-effective and high-efficiency electrocatalysts is critical to the water splitting performance during hydrogen generation.Herein,we have developed Fe_(2)P-Co_(2)P heterostructure nanowire arrays with excellent lattice torsions and grain boundaries for highly efficient water splitting.According to the microstructural investigations and theoretical calculations,the lattice torsion interface not only contributes to the exposure of more active sites but also effectively tunes the adsorption energy of hydrogen/oxygen intermediates via the accumulation of charge redistribution.As a result,the Fe_(2)P-Co_(2)P heterostructure nanowire array exhibits exceptional bifunctional catalytic activity with overpotentials of 65 and 198 mV at 10 mA cm^(-2) for hydrogen and oxygen evolution reactions,respectively.Moreover,the Fe_(2)P-Co_(2)P/NF-assembled electrolyzer can deliver 10 mA cm^(-2) at an ultralow voltage of1.51 V while resulting in a high solar-to-hydrogen conversion efficiency of 19.8%in the solar-driven water electrolysis cell.

Nickel release rate of 18KW gold alloy for ornaments

Nickel is widely used as a bleaching element in white gold alloys, but it is a potential allergen. In this paper, a popular 18 KW gold alloy, often called "safe nickel," was chosen as the experimental material; its nickel release rates under six different processing conditions were evaluated according to the EN1811 standard. The results reveal that both the surface processing method and heat treatment technology significantly affect the nickel release rate. A coarse surface releases more nickel ions than a smooth surface. The sample normalized at 700℃ in the single region has a lower nickel release rate than the one treated at 550℃ in the two-phase phase region, while high temperature normalizing at 800℃ will accelerate it. All the measured nickel release rates of the experimental material under various processing conditions exceed the permitted threshold value in the Nickel Directive, which indicates that there exists the potential risk of nickelinduced allergy when it is used to make jewelries, especially for piercing types.

Study of Ce-modified antibacterial 316L stainless steel

316L stainless steel is widely used for fashion jewelry, but it can carry a large number of bacteria and bring the risk of infection since the steel has no antimicrobial performance. In this paper, the effects of Ce on the antibacterial property, corrosion resistance and processability of 316L were studied by microscopic observation, thin- film adhering quantitative bacteriostasis, and electrochemical and mechanical tests. The results show that a trace of Ce can distribute uniformly in the matrix of 316L and slightly improve its corrosion resistance in artificial sweat. With an increase in Ce content, the Ce is prone to form clustering, which degrades the corrosion resistance and the processability. The Ce-containing 316L exhibits Hormesis effect against S. aureus. A small Ce addition stimulates the growth of S. aureus. As the Ce content increases, the modified 316L exhibits an improved antibacterial efficacy. The more Ce is added, the better antibacterial capability is achieved. Overall, if the 316L is modified with Ce alone, it is difficult to obtain the optimal combination of corrosion resistance, antibacterial performance and processability. In spite of that, 0.15 wt.%-0.20 wt.% Ce around is inferred to be the best trade-off.

Polar Mixing Optical Phonon Spectra in Wurtzite GaN Cylindrical Quantum Dots: Quantum Size and Dielectric Effects

混合 quasi-zero-dimensional (QoD ) 的声子模式的 interface-optical-propagating (IO-PR ) wurtzite 圆柱的量点(QD ) 结构被雇用宏观的绝缘的连续统模特儿导出并且学习。混合模式的 IO-PR 的分析声子状态被给。有混合声子模式的 IO-PR 的二种类型，这被发现，即混合在 QoD wurtzite QD 存在的模式的 -IO/z-PR 混合模式和 z-IO/-PR。并且各， IO-PR 混合模式也有对称并且 antisymmetrical 表格。经由领域量子化的一个标准过程， Fr ? 电子的 hlich Hamiltonians --(IO-PR ) 混合声子相互作用被获得。wurtzite 上的数字计算轧了圆柱的 QD 被执行。结果表明光线方向的尺寸和轴方向的尺寸以及绝缘的矩阵在混合声子模式的 IO-PR 的散频率上有大影响。这些声子模式的散曲线的限制特征深入地被讨论。减少的声子模式“ wurtzite 量的行为限制了系统在结构显然被观察了。而且，在 wurtzite Q2D QW 和 Q1D QWR 系统在 wurtzite QoD QD 混合声子模式到 IO 模式和 PR 模式的 IO-PR 的堕落行为物理和数学的观点从两个深深地被分析。

Phonon States and Dispersive Spectra of Polar Optical Phonons in Quasi-One-Dimensional Nanowires of Wurtzite ZnO and Zinc-Blend MgO Semiconductors

在宏观的绝缘的连续统模型和 Loudon 的框架以内是单轴的水晶模型， wurtzite/zinc-blende 的声子模式一个维(1D ) 圆柱的 nanowire (NW ) 被导出并且学习。声子模式的分析声子状态被给。在那里存在，这被发现极的声子模式的二种类型，即接口光(IO ) 声子模式并且限制伪(质量管理) 声子模式在 1D wurtzite/zinc-blende NW 存在。经由地量子化的标准过程， Fr ? hlich 电子声子相互作用 Hamiltonians 被获得。wurtzite/zinc-blende ZnO/MgO NW 上的这些声子模式的散行为的数字计算被执行。ZnO/MgO NW 的 IO 和质量管理声子模式的频率范围被分析并且讨论。IO 模式仅仅在一个频率范围存在，这被发现，当质量管理模式可以出现在三个频率范围时。免费波浪数字 kz 和方位角的量数字 m 上的 IO 和质量管理模式的散性质被讨论。这里获得的电子声子相互作用的分析 Hamiltonians 为进一步在 wurtzite/zinc-blende 1D NW 结构的光电子性质上调查声子影响是相当有用的。

Learning-based joint UAV trajectory and power allocation optimization for secure IoT networks

Non-Orthogonal Multiplex Access(NOMA)can be deployed in Unmanned Aerial Vehicle(UAV)networks to improve spectrum efficiency.Due to the broadcasting feature of NOMA-UAV networks,it is essential to focus on the security of the wireless system.This paper focuses on maximizing the secrecy sum rate under the constraint of the achievable rate of the legitimate channels.To tackle the non-convexity optimization problem,a reinforcement learning-based alternative optimization algorithm is proposed.Firstly,with the help of successive convex approximations,the optimal power allocation scheme with a given UAV trajectory is obtained by using convex optimization tools.Afterwards,through plenty of explorations of the wireless environment,the Q-learning networks approach the optimal location transition strategy of the UAV,even without the wireless channel state information.

3D-printed MoS_(2)/Ni electrodes with excellent electro-catalytic performance and long-term stability for dechlorination of florfenicol

Here,we report the production of 3D-printed MoS_(2)/Ni electrodes(3D-MoS_(2)/Ni)with longterm stability and excellent performance by the selective laser melting(SLM)technique.As a cathode,the obtained 3D-MoS_(2)/Ni could maintain a degradation rate above 94.0%for forfenicol(FLO)when repeatedly used 50 times in water.We also found that the removal rate of FLO by 3D-MoS_(2)/Ni was about 12 times higher than that of 3D-printed pure Ni(3D-Ni),attributed to the improved accessibility of H^(*).In addition,the electrochemical characterization results showed that the electrochemically active surface area of the 3D-MoS_(2)/Ni electrode is about 3-fold higher than that of the 3D-Ni electrode while the electrical resistance is 4 times lower.Based on tert-butanol suppression,electron paramagnetic resonance and triple quadrupole mass spectrometer experiments,a“dual path”mechanism and possible degradation pathway for the dechlorination of FLO by 3D-MoS_(2)/Ni were proposed.Furthermore,we also investigated the impacts of the cathode potential and the initial pH of the solution on the degradation of FLO.Overall,this study reveals that the SLM 3D printing technique is a promising approach for the rapid fabrication of high-stability metal electrodes,which could have broad application in the control of water contaminants in the environmental field.

Development of MoS_(2)-stainless steel catalyst by 3D printing for efficient destruction of organics via peroxymonosulfate activation

Herein,a novel MoS_(2)-stainless steel composite material was first synthetized via a 3D printing method(3DP MoS_(2)-SS)for peroxymonosulfate(PMS)activation and organics degradation.Compared with MoS_(2)-SS powder/PMS system(0.37 g/(m^(2)/min)),4.3-fold higher k_(FLO)/S_(BET)value was obtained in 3DP MoS_(2)-SS/PMS system(1.60 g/(m^(2)/min),resulting from the superior utilization of active sites.We observed that 3DP MoS_(2)-SS significantly outperformed the 3DP SS due to the enhanced electron transfer rate and increased active sites.Moreover,Mo^(4+)facilitated the Fe^(2+)/Fe^(3+)cycle,resulting in the rapid degradation of florfenicol(FLO).Quenching experiments and electron paramagnetic resonance spectra indicated that·OH,SO_(4)·^(-),O_(2)·^(-)and^(1)O_(2)were involved in the degradation of FLO.The effect of influencing factors on the degradation of FLO were evaluated,and the optimized degradation efficiency of 98.69%was achieved at 1 mM PMS and pH of 3.0.Six degradation products were detected by UPLC/MS analyses and several possible degradation pathways were proposed to be the cleavage of C-N bonds,dechlorination,hydrolysis,defluorination and hydroxylation.In addition,3DP MoS_(2)-SS/PMS system also demonstrated superior degradation performance for 2-chlorophenol,acetaminophen,ibuprofen and carbamazepine.This study provided deep insights into the MoS_(2)-SS catalyst prepared by 3DP technology for PMS activation and FLO-polluted water treatment.

Au nanoclusters anchored on TiO_(2) nanosheets for high-efficiency electroreduction of nitrate to ammonia

Electrocatalytic nitrate reduction reaction(NO_(3)RR)offers a unique rationale for green NH_(3) synthesis,yet the lack of high-efficiency NO_(3)RR catalysts remains a great challenge.In this work,we show that Au nanoclusters anchored on TiO_(2) nanosheets can efficiently catalyze the conversion of NO_(3)RR-to-NH_(3) under ambient conditions,achieving a maximal Faradic efficiency of 91%,a peak yield rate of 1923μg·h^(-1)·mgcat.-1,and high durability over 10 consecutive cycles,all of which are comparable to the recently reported metrics(including transition metal and noble metal-based catalysts)and exceed those of pristine TiO_(2).Moreover,a galvanic Zn-nitrate battery using the catalyst as the cathode was proposed,which shows a power density of 3.62 mW·cm^(-2) and a yield rate of 452μg·h^(-1)·mgcat.-1.Theoretical simulations further indicate that the atomically dispersed Au clusters can promote the adsorption and activation of NO_(3)-species,and reduce the NO_(3)RR-to-NH_(3) barrier,thus leading to an accelerated cathodic reaction.This work highlights the importance of metal clusters for the NH_(3) electrosynthesis and nitrate removal.

Excellent energy storage properties realized in novel BaTiO_(3)-based lead-free ceramics by regulating relaxation behavior

BaTiO_(3)(BT)has attracted extensive attention among advanced lead-free ferroelectric materials due to its unique dielectric and ferroelectric properties.However,the enormous remanent polarization and coercive field severely impede the improvement of its energy storage capabilities.Here,the BaTiO_(3)e-Bi(Zn_(0.5)Hf_(0.5))O_(3)(BT-BZH)ceramics with high breakdown field strength and remarkable relaxation characteristics can be obtained by introducing the composite component BZH in BT to regulate the phase structure and grain size of the ceramics.The findings demonstrate that the improvement of energy storage performance is related to the increase of relaxation behavior.A large energy storage density(Wrec~3.62 J/cm^(3))along with superior energy storage efficiency(h~88.5%)is achieved in 0.88BT-0.12BZH relaxor ceramics only at 240 kV/cm.In addition,the sample suggests superior thermal stability and frequency stability within 25e115℃and 1e500 Hz,respectively.Furthermore,the outstanding chargedischarge properties with an ultrafast discharge time(100 ns),large discharged energy density(1.2 J/cm^(3)),impressive current density(519.4 A/cm^(2))and power density(31.1 MW/cm^(3))under the electric field of 120 kV/cm are achieved in studied ceramics.The excellent energy storage performance of BT-BZH ceramics provides a promising platform for the application of lead-free energy-storage materials.

Composition-tailor induced electrocaloric effect near room temperature in(Pb,Ba)HfO_(3)films

More and more researchers start to pay attention to the electrocaloric temperature change(DT)in polar materials,which is caused by an applied electric field.In this paper,Ba-doped PbHfO_(3)(PBH)films were prepared by sol-gel method.Their components,microstructures,dielectric polarization and electro-caloric effects(ECEs)were investigated.With the addition of Ba^(2+),PBH films went from antiferroelectric(AFE)to ferroelectric(FE).At the same time,their dielectric peaks shifted toward lower temperature.The maximum DT obtained in Pb_(0.8)Ba_(0.2)HfO_(3)FE film is 41.1 K,which is an order of magnitude larger than PbHfO_(3)film(△T<4 K at 50℃)and Pb_(0.9)Ba_(0.1)HfO_(3)film(△T<4 K at 120℃).In order to explain this phenomenon,the Landau-Devonshire theory was adopted.Our analysis shows that the rapid variation of energy barrier height near the phase transition temperature is beneficial to obtain large polarization change and high△T,which is needed in solid-state cooling devices.

加拿大魁北克社区学院通识教育的实践与启示——以维尼尔学院为例

加拿大魁北克社区学院通识教育强调双语教育是实施公民教育的主要途径,以知识、世界观及伦理道德为核心的人文教育课程体系,以自由选择理念、健康体格训练的内嵌与推进,侧重组织管理、名师工程作用的发挥。国内高职院校应强化通识教育理念的价值诉求、构建与专业教育相协调的通识教育课程体系、加强通识教育的组织管理与有效实施。

Cutting Performance and Wear Behavior of AITiN-and TiAlSiN-Coated Carbide Tools During Dry Milling of Ti-6Al-4V

Machining,especially dry machining of titanium alloys,has been one of the most significant challenges for carbide cutting tools.In this study,aluminum-rich AlTiN coating,as well as TiAlSiN nanocomposite coating,were successfully employed for dry milling of Ti-6 A1-4 V alloy with high efficiency and long tool life.At the cutting speeds of 150 m/min and 200 m/min,the tool life of the TiAlSiN-coated tool exceeds that of AlTiN-coated tool by 32 and 66%,respectively.The wear modes for both coated tools include the uniform flank wear,smooth wear,chipping,coating and substrate flaking,crater and notch wear,and the wear mechanisms include adhesion,diffusion,oxidation and crack.Among them,the wear mechanism is dominated by the adhesion and oxidation wear.As compared with AlTiN coating,TiAlSiN coating exhibits better mechanical properties and oxidation resistance,which contribute to a better cutting performance,fewer thermal cracks and smaller and uniform workpiece chips during the dry milling of Ti-6 A1-4 V alloy.

Change Rules of Γ_2 Particles in Hot-dipped Zn-Ti Coating

Hot-dip Zn-Ti galvanizing can restrain the excess growth of the coating which has better corrosion resistances than hot-dip pure Zn.The change rules ofΓ2intermetallic compound in hot-dip Zn-Ti galvanizing is investigated by immersion time,titanium content and the slag test using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD).And the mechanism of nucleation and growth ofΓ2intermetallic compound is analysed.The results show that,when adding 0.05mass%titanium to the zinc bath,theΓ2particles form in theηlayer,which nucleate by obtaining Ti atoms from theηphase and Fe atoms from the dissolvingζphase layer.Moreover,the more titanium is added into the bath,the more and biggerΓ2 particles appear.TheГ2particles in the coatings grow up noticeably with prolonging the immersion time.

Nickel Release Rate of Several Nickel-containing Stainless Steels for Jewelries

Nickel-containing stainless steels have been widely applied in watch and jewelry production,and their responses to the Nickel Directive become a universal concern in the industry.The nickel release rates and corrosion behaviors of types 316 L,304,303 and 201stainless steels under the conditions of solid solution and mirror polishing were studied by artificial sweat soaking and electrochemical methods.The results show that the weekly nickel release rates in artificial sweat do not strictly correspond to the nickel contents,which present a descending order as 303 stainless steel of 2.06μg/cm2,201 stainless steel of 1.51μg/cm2,304 stainless steel of 0.08μg/cm2 and 316 L stainless steel of 0.02μg/cm2.Both the nickel release rates of type 303 and 201stainless steels significantly exceed the threshold values regulated in EN1811∶2011;therefore,they should be avoided to be used as watch and jewelry materials owing to the risk of nickel sensitization.The nickel release rates of 316 Land 304stainless steels meet the requirements of the standard.Sulfide inclusions in stainless steel become the sources of pitting and exacerbate the damage of the passivation membrane,which is the significant cause to enhance the nickel release rates.

Recycling of Cristobalite Powder in Casting Mould

Cristobalite SiO2 can be obtained from the fused silica ceramic waste of ploysilicon plant, due to the phase conversion of fused silica to cristobalite during the process of polysilicon ingot. Cristobalite powder materials with high purity are manufactured by milling the discarded waste above. Thermal expansion rate of the cristobalite and gypsum bonding moulds were studied, which show that the thermal expansion of the cristobalite phase transition could effectively compensate for the shrinkage of the gypsum at the temperature between 200 ℃ and 400 ℃. Casting experiments with copper alloy show that the cristobalite can improve the thermal performance of moulds for precise casting of jewelry.

Characterization of the Convoluted 3D Internetallic Phases in a Recycled Al Alloy by Synchrotron X-ray Tomography and Machine Learning

Fe-rich intermetallic phases in recycled Al alloys often exhibit complex and 3D convoluted structures and morphologies.They are the common detrimental intermetallic phases to the mechanical properties of recycled Al alloys.In this study,we used synchrotron X-ray tomography to study the true 3D morphologies of the Ferich phases,Al_(2)Cu phases and casting defects in an ascast Al-5Cu-1.5Fe-1Si alloy.Machine learning-based image processing approach was used to recognize and segment the diff erent phases in the 3D tomography image stacks.In the studied condition,theβ-Al_(9)Fe_(2)Si_(2)andω-Al_(7)Cu_(2)Fe are found to be the main Fe-rich intermetallic phases.Theβ-Al_(9)Fe_(2)Si_(2)phases exhibit a spatially connected 3D network structure and morphology which in turn control the 3D spatial distribution of the Al_(2)Cu phases and the shrinkage cavities.The Al_(3)Fe phases formed at the early stage of solidification aff ect to a large extent the structure and morphology of the subsequently formed Fe-rich intermetallic phases.The machine learning method has been demonstrated as a powerful tool for processing big datasets in multidimensional imaging-based materials characterization work.

A high-precision image classification network model based on a voting mechanism

With the development of satellite remote sensing technology,image classification task,as the basis of remote sensing data interpretation,has received wide attention to improving accuracy and robustness.At the same time,in-depth learning technology has been widely used in remote sensing and has a far-reaching impact.Since the existing image classification methods ignore the feature that the general image semantics are the same as the semantics of a single pixel,this paper presents an algorithm that uses the semantics of an image to achieve high-precision image classification.Based on the idea of partial substitution for global,this algorithm designs a split result voting mechanism and builds a Vgg-Vote network model.This mechanism votes on the semantically segmented result of an image and uses the maximum filtering function to select the category containing the most significant number of pixels as the prediction category of the image.Experiments on UC Merced Land-User complete datasets and five types of incomplete datasets with varying degrees of interference,including noise,data occlusion and loss,show that the Vote mechanism dramatically improves the classification accuracy,robustness and anti-jamming capability of Vgg-Vote.