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Nanocarbons, widely and commonly used as supports for supported Pt-based electrocatalysts in PEMFCs, play a significant role in Pt dispersion and accessibility, further determining their corresponding electrocatalytic performance. This paper provides an overview of the nanoarchitectures and surface physicochemical properties of nanocarbons affecting the electrocatalyst performance, with an emphasis on both physical characteristics, including pore structure, and chemical properties, including heteroatom doping and functional carbon-based supports. This review discusses the recent progress in nanocarbon supports, guides the future development direction of PEMFC supports, and provides our own viewpoints for the future research and design of PEMFCs catalysts, advancing the commercialization of PEMFCs.

The electrochemical oxygen evolution reaction (OER) plays an important role in many clean electrochemical energy storage and conversion systems, such as electrochemical water splitting, rechargeable metal–air batteries, and electrochemical CO2 reduction. However, the OER involves a complex four-electron process and suffers from intrinsically sluggish kinetics, which greatly impairs the efficiency of electrochemical systems. In addition, state-of-the-art RuO2-based OER electrocatalysts are too expensive and scarce for practical applications. The development of highly active, cost-effective, and durable electrocatalysts that can improve OER performance (activity and durability) is of significant importance in realizing the widespread application of these advanced technologies. To date, considerable progress has been made in the development of alternative, noble metal-free OER electrocatalysts. Among these alternative catalysts, transition metal compounds have received particular attention and have shown activities comparable to or even higher than those of their precious metal counterparts. In contrast to many other electrocatalysts, such as carbon-based materials, transition metal compounds often exhibit a surface reconstruction phenomenon that is accompanied by the transformation of valence states during electrochemical OER processes. This surface reconstruction results in changes to the true active sites and an improvement or reduction in OER catalytic performance. Therefore, understanding the self-reconstruction process and precisely identifying the true active sites on electrocatalyst surfaces will help us to finely tune the properties and activities of OER catalysts. This review provides a comprehensive summary of recent progress made in understanding the surface reconstruction phenomena of various transition metal-based OER electrocatalysts, focusing on uncovering the correlations among structure, surface reconstruction and intrinsic activity. Recent advances in OER electrocatalysts that exhibit a surface self-reconstruction capability are also discussed. We identify possible challenges and perspectives for the development of OER electrocatalysts based on surface reconstruction. We hope this review will provide readers with some guidance on the rational design of catalysts for various electrochemical reactions.

Photovoltaic conversion of renewable solar energy into electricity for sustainable energy production requires efficient, stable, and low-cost solar cells. Developing solution-processed all-inorganic solar cells is a practical scenario in virtue of the high charge mobility and good stability of inorganic semiconductors. Here, for the first time, we present a solution-processed all-inorganic planar heterojunction solar cell based on the nanoparticle film of copper indium sulfide (CuInS2) by using an antimony trisulfide (Sb2S3) nanoparticle film as an interfacial layer between the CuInS2 photon-harvesting layer and cathode. All of the component layers in the solar cell are in a superstrate architecture and sequentially in situ grown on a transparent conducting glass acting as anode by solution-processing methods. The dependences of device performance on the thickness of Sb2S3 film and the reduction of hole-trapping centers in the Sb2S3 film by thioacetamide treatment are investigated. The optimized all-inorganic device exhibits the best power conversion efficiency of 4.85% under AM 1.5G illumination and an excellent thermal stability. It is found that the Sb2S3 interfacial layer sandwiched between the CuInS2 photon-harvesting layer and counter-electrode has dual functions, that is, to provide complementary absorption after CuInS2 attenuation and to act as an effective hole-transporting layer to selectively extract photogenerated holes for effective charge collection efficiency.

Efficient, stable and low-cost solar cells are being desired for the photovoltaic conversion of solar energy into electricity for sustainable energy production. Nanorod/nanowire arrays of narrow-bandgap semiconductors are the promising light-harvesters for photovoltaics because of their excellent optoelectrical properties. Here, the array of preferentially oriented antimony trisulfide (Sb2S3) single-crystalline nanorods is grown on polycrystalline titania (TiO2) film by a tiny-seed-assisted solution-processing strategy, offering an Sb2S3/TiO2 nanoarray heterojunction system on a large scale. It is demonstrated that the Sb2S3 nanorod growth follows a tiny-seed-governed orientation-competing-epitaxial nucleation/growth mechanism. Using a conjugated polymer hole transporting layer on the heterojunction, we achieve a power conversion efficiency of 5.70% in the stable hybrid solar cell with a preferred p-type/intrinsic/n-type architecture featuring effectively straightforward charge transport channels and no negative impact of photogenerated electric field on device performance. An architecture-dependent charge distribution model is proposed to understand the unique photovoltaic behavior. Photovoltaic devices require reliable and scalable growth methods to produce the constituent materials. Here, the authors report a tiny-seed-assisted solution processing strategy to grow Sb2S3/TiO2 nanoarray heterojunction of which the hybrid solar cell without negative impact of photogenerated electric field exhibits a power efficiency of 5.70%.

There is an urgent need for an effective and long-lasting ceramic filter for point-of-use water treatment. In this study, silver-diatomite nanocomposite ceramic filters were developed by an easy and effective method. The ceramic filters have a three-dimensional interconnected pore structure and porosity of 50.85%. Characterizations of the silver-diatomite nanocomposite ceramic filters were performed using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Silver nanoparticles were confirmed to be formed in situ in the ceramic filter. The highest silver concentration in water was 0.24 μg/L and 2.1 μg/L in short- and long-term experiments, indicating very low silver-release properties of silver-diatomite nanocomposite ceramic filter. The nanocomposite ceramics show strong bactericidal activity. When contact time with Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) of 105 colony forming units (CFU)/mL exceeded 3 h, the bactericidal rates of the four different silver content ceramics against E. coli and S. aureus were all 100%. Strong bactericidal effect against E. coli with initial concentration of 109 CFU/mL were also observed in ceramic newly obtained and ceramic immersed in water for 270 days, demonstrating its high stability. The silver-diatomite nanocomposite ceramic filters could be a promising candidate for point-of-use water treatment.

The isothermal gasification kinetics of bituminous coal char was investigated within 1173–1373 K range. Also, the impacts of gasification temperature, gas composition, and gasification time on gasi...

Fabricating low-overpotential materials for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is an important component of current developments in clean energy. Here, we use nickel oxide for its high hydrophilicity and ammonium fluoride to cause the current collector to produce more active sites with increased adhesion to prepare 2D ultrafine Mo-based precursor nanosheets with uniform dimensions and a stable structure on nickel foam (NF). Further phosphorization treatment is performed to obtain porous molybdenum phosphide (MoP) nanosheets on Ni3P/NF. As a freestanding integrated electrode, MoP@Ni3P/NF possess excellent catalytic activity for the HER and OER with low overpotentials (45 mV to reach 10 mA cm−2 for the HER and 331 mV to reach 35 mA cm−2 for the OER). The performance of this catalyst is close to that of some precious metal catalysts. The activity as both an anode and cathode catalyst for overall water splitting can reach 1.67 V at 10 mA cm−2. Due to its scalable preparation and stability, the MoP@Ni3P/NF electrocatalyst is promising for use in practical water-alkali electrolysis.

Numerous studies have focused on the reduction thermodynamics of ordinary iron ore; by contrast, the literature contains few thermodynamic studies on the gas-based reduction of vanadium titano-magnetite (VTM) in mixed atmospheres of H2, CO, H2O, CO2, and N2. In this paper, thermodynamic studies on the reduction of oxidized VTM pellets were systematically conducted in an atmosphere of a C–H–O system as a reducing agent. The results indicate that VTM of an equivalent valence state is more difficult to reduce than ordinary iron ore. A reduction equilibrium diagram using the C–H–O system as a reducing agent was obtained; it clearly describes the reduction process. Experiments were performed to investigate the effects of the reduction temperature, the gas composition, and two types of iron ores on the reduction of oxidized VTM pellets. The results show that the final reduction degree increases with increasing reduction temperature, increasing molar ratio of H2/(H2 + CO), and decreasing H2O, CO2, and N2 contents. In addition, the reduction processes under various conditions are discussed. All of the results of the reduction experiments are consistent with those of theoretical thermodynamic analysis. This study is expected to provide valuable thermodynamic theory on the industrial applications of VTM.

A facile solution-processing method featuring the applications of a stable molecular precursor solution and the repetition of spin-coating and annealing for film growth is reported for the in situ growth of CuInS2 nanoparticle films on TiO2/CdS film to provide TiO2/CdS/CuInS2 ternary superstrate heterojunction films for efficient solar cells. The novel and stable planar solar cells are fabricated using Spiro-OMeTAD as hole transporting material (HTM) and achieved a peak power conversion efficiency of 6.31% under AM 1.5 illumination at the optimized CuInS2 thickness of 200 nm and annealing temperature of 270 °C for CuInS2 formation. The efficiency is the highest among the CuInS2-based planar solar cells derived from molecular precursor methods; in particular, adopting HTM results in the open-circuit voltage up to 0.78 V, much higher than that of the similar devices without HTM. Our results demonstrate a dual nature of excitonic and nonexcitonic charge generation mechanisms in such solar cells. A depletion-...

Compact Cu2ZnSnS4 (CZTS) nanoparticle films are in-situ prepared on ITO-coated glass by a novel molecular precursor solution method at a low temperature (300 °C) and a short annealing time. The CZTS films exhibit a band gap of 1.48 eV and absorption coefficient of > 104 cm−1. It is found that the performance of CH3NH3PbI3 perovskite solar cells with CZTS film as hole transporting material (HTM) strongly depends on CZTS thickness due to that its absorption of photons significantly limits the photon-to-electron transfer below 550 nm, and the CZTS film thinner than 100 nm is a more effective HTM for efficient MAPbI3-based solar cells; furthermore, the CZTS/MAPbI3 solar cells are much more efficient and stable than the counterpart devices with poly(3,4-ethylenedioxy-thiophene):poly(styrene sulfonate) as HTM.

Nowadays, active matrix organic light emitting diodes (AMOLED) with higher resolution and narrower bezel can be achieved by using integrated gate driver on array (GOA) technology. In order to reduce the bezel width of displays more effectively, the width of GOA circuit needs to be reduced. In this paper, we study the transfer characteristics and output characteristics of dual-gate amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) by comparing with single gate TFTs. Dual gate TFTs exhibit high mobility and good PBTS reliability on Gen. 4.5 glass. Subsequently, we propose a gate driver on array (GOA) circuit by using dual gate TFTs to narrowing the width of GOA circuit layout. The GOA circuit was operated for 1020h under accelerating test conditions of 60 degrees Celsius, indicating high reliability of this GOA circuit.

A simple method is provided to achieve in situ surface reconstruction synthesis of a heterostructural NiO/Ni film on carbon cloth (NiO/Ni@CC) for the hydrogen evolution reaction (HER). This ultrafast reconstruction process brings a hydrophilic surface and abundant heterostructures with rich oxygen vacancies exhibiting a low HER overpotential and remarkable stability.

The rational design of electrode structure with catalysts adequately utilized is of vital importance for future fuel cells. Herein, a novel 3D oriented wholly integrated electrode comprising core–shell Fe3O4@N‐doped‐C (Fe3O4@NC) nanoparticles embedded into N‐doped ordered interconnected hierarchical porous carbon (denoted as Fe3O4@NC/NHPC) is developed for the oxygen reduction reaction (ORR). The as‐prepared catalyst possesses novel structure and efficient active sites. In rotating disk electrode measurements, the Fe3O4@NC/NHPC exhibits almost identical ORR electrocatalytic activity, superior durability, and much better methanol tolerance compared with the commercial Pt/C in acidic media. To the authors’ knowledge, this is among the best non‐precious‐metal ORR catalysts reported so far. Importantly, the Fe3O4@NC/NHPC is successfully in situ assembled onto carbon paper by the electrophoresis method to obtain a well‐designed 3D‐ordered electrode. With improved mass transfer and maximized active sites for ORR, the 3D‐oriented wholly integrated electrode shows superior performance to the one fabricated by the traditional method.

There were many advantages of high power single mode fiber lasers, such as near-diffraction-limitation beam quality, high power, high electro-optical conversion efficiency and high stability. In this paper, high power continuous-wave single mode fiber laser with master oscillator power amplifier configuration was reported. The fiber laser contained one seed laser and one-stage amplifier. The seed laser was a linear oscillator cavity structure with YDF-20/400 as gain fiber. The power of the seed laser was 200 W with the center wavelength of 1080 nm. One back pumped fiber amplifier with YDF-25/400 as gain fiber was built to boost the average power of the seed laser. The pump laser wavelength was 915 nm. The maximum output power is 3.3 kW at the pump power of 4.3 kW. The optical to optical efficiency of the amplifier was 72.6%. The beam quality at maximum output power was Mx2~1.29, My2~1.26. The near-diffraction-limitation beam quality would make this fiber laser become potential source for military defense, industry and medicine.

Increasing evidence shows that mechanical stresses are critical in regulating cell functions, fate, and diseases. However, no methods exist that can quantify isotropic compressive stresses. Here we describe fluorescent nanoparticle-labeled, monodisperse elastic microspheres made of Arg-Gly-Asp-conjugated alginate hydrogels (elastic round microgels, ERMGs). We generate 3D displacements and calculate strains and tractions exerted on an ERMG. Average compressive tractions on an ERMG are 570 Pa within cell layers and 360 Pa in tumor-repopulating cell (TRC) colonies grown in 400-Pa matrices. 3D compressive tractions on a 1.4-kPa ERMG are applied by surrounding cells via endogenous actomyosin forces but not via mature focal adhesions. Compressive stresses are substantially heterogeneous on ERMGs within a uniform cell colony and do not increase with TRC colony sizes. Early-stage zebrafish embryos generate spatial and temporal differences in local normal and shear stresses. This ERMG method could be useful for quantifying stresses in vitro and in vivo., Increasing importance is placed upon the effect of mechanical forces on cell regulation, fate and disease states. Here, the authors describe a deformable fluorescent nanoparticle labeled elastic microsphere which can be used to calculate strain and traction forces in vitro and in vivo.

As a convenient preparation technique, a two-step method, which is normally done by spin-coating CH3NH3I onto PbI2 film followed by a thermal annealing, is generally used to prepare solution-processed CH3NH3PbI3 films for planar perovskite solar cells. Here, we prepare the compact CH3NH3PbI3 thin films by the two-step method at a low temperature (

Sb2S3-based bulk/nano planar heterojunction (BnPHJ) films are promising photoelectric conversion materials for photovoltaics. Here, a solution-processing polymer/graphene composite film is employed as hole transporting layer in Sb2S3/TiO2-BnPHJ solar cells for the first time. The morphology and hole mobility of the composite film is investigated by SEM, AFM, SCLC techniques, and IMVS and EIS are applied to study the charge transport and recombination mechanism in the solar cells. The Sb2S3/TiO2-BnPHJ solar cells delivers a power conversion efficiency of 5.72% and a good stability.

Highly-condensed thin films of Cu 2 FeSnS 4 (CFTS) nanoparticles are prepared on FTO substrates by spin-coating CFTS precursor solution followed by a short thermal annealing at low temperature for the first time. The CFTS film has a band gap of 1.53 eV and an absorption coefficient higher than 10 4 cm −1 in the wavelength range of 300–1100 nm. The thin film solar cells structured as FTO/CFTS/CdS/Al are fabricated and it is demonstrated that the optimized CFTS film thickness for such devices is around 125 nm.

Photovoltaic conversion of solar energy into electricity is an alternative way to use renewable energy for sustainable energy production. The great demand of low-cost and efficient solar cells inspires research on solution-processable light-harvesting materials. Antimony trisulfide (Sb2S3) is a promising light-harvester for photovoltaic purposes. Here we report on the in situ grown monolayer of preferentially oriented, large Sb2S3 single-crystalline cuboids on a polycrystalline titania (TiO2) nanoparticle film. A facile, oriented seed-assisted solution-processing method is used, providing the Sb2S3/TiO2-based bulk/nano-planar heterojunction with a preferred structure for efficient planar solar cells. An orientation-competing-epitaxial nucleation/growth mechanism is proposed for understanding the growth of the Sb2S3 single-crystalline cuboids. With an organic hole transporting material, the stable solar cell of the heterojunction yields a power conversion efficiency of 5.15% (certified as 5.12%). It is found that the [221]-oriented Sb2S3 cuboids provide highly effective charge transport channels inside the Sb2S3 layer.

The isotope effect on impurities and bulk ion particle transport is investigated by using the deuterium, hydrogen, and isotope mixture plasma in the Large Helical Device (LHD). A clear isotope effect is observed in the impurity transport but not the bulk ion transport. The isotope effects on impurity transport and ion heat transport are observed as a primary and a secondary effect, respectively, in the plasma with an internal transport barrier (ITB). In the LHD, an ion ITB is always transient because the impurity hole triggered by the increase of ion temperature gradient causes the enhancement of ion heat transport and gradually terminates the ion ITB. The formation of an impurity hole becomes slower in the deuterium (D) plasma than the hydrogen (H) plasma. This primary isotope effect on impurity transport contributes the longer sustainment of the ion ITB state because the low ion thermal diffusivity can be sustained as long as the normalized carbon impurity gradient R/L n,c, where L c =-(∇n c/n c) -1 is above the critical value (∼-5). Therefore, the longer sustainment of the ITB state in the deuterium plasma is considered to be a secondary isotope effect due to the mitigation of the impurity hole. The radial profile of H and D ion density is measured using bulk charge exchange spectroscopy inside the isotope mixture plasma. The decay time of H ion density after the H-pellet injection and the decay time of D ion density after D-pellet injection are almost identical, which demonstrates that there is no significant isotope effect on ion particle transport.

The gasification kinetics of bituminous coal char was investigated in a mixture of CO2, H2O, CO, H2, and N2 under isothermal conditions. In addition, the impacts of gasification temperature, gasification time, and gas composition on the gasification process were analyzed. As the experimental results suggest, there is a significant increase of the carbon conversion degree of bituminous coal char not just when gasification temperature and time increase, but also when H2 and CO concentration decreases. The kinetics of bituminous coal char in the gasification process was successfully modeled as a shrinking unreacted core. It is concluded that the gasification of bituminous coal char is controlled by an internal chemical reaction in the early stage and diffusion in the later stage. The activation energies of bituminous coal char gasification for different stages were studied. Moreover, it is proposed for the first time, to our knowledge, that the diffusion-control step is significantly shortened with the decrease of the CO2/H2O ratio. As scanning-electron-microscopy results suggest, bituminous coal char gasified in CO2/H2O = 1/3 atmosphere has numerous inner pores (0&ndash, 5 m). Therefore, in the process of gasification, the inner pores provide a gas channel that reduces the gas diffusion resistance and thus shortens the diffusion-control step. These results can serve as a reference for industrialized application of the technology of coal gasification direct reduced iron.

Vanadium titano-magnetite (VTM) is a significant resource in China&mdash, analysis shows that China possesses approximately 10 billion tons of VTM. In this study, we characterize VTM&rsquo, s isothermal reduction mechanisms in the mixture of H2, CO, and N2 where the variables considered include reduction time, reduction temperature, gas composition, and pellet size. The kinetics of the reduction process were studied following a shrinking core model. The results indicate that the reduction degree of oxidized VTM pellets increases with increases of reduction time and reduction temperature but decreases with increasing pellet size. Moreover, we found that an increase of H2/(H2 + CO) ratio induced an increase of the reduction degree. We discuss the transformation of main Ti-bearing mineral phases, and we consider the most probable reaction mechanism. For the entire reduction process, the kinetic results confirm the existence of an early and later stages that are controlled by interface chemical reaction and diffusion, respectively. Furthermore, the results show that the diffusion-control step can be observably shortened via decreased pellet size because a thinner product layer is formed during the reduction process. Our study thus provides a valuable technical basis for industrial applications of VTM.

A bulk charge exchange spectroscopy (BCXS) system using a grism (grating prism) spectrometer has been applied to measure the profile of the deuterium (D) fraction in deuterium and hydrogen (H) mixture plasma in the Large Helical Device. The observed spectrum can be fitted with four Gaussian functions successfully by reduction of free parameters for the least-squares fit. The plasma flow velocity and ion temperature profile measured by charge exchange spectroscopy using carbon impurity are used for estimation of the wavelength shift of hot components to reduce the free parameter. The ion temperature is used to estimate the apparent wavelength shift due to the energy dependent emission cross section only and is not used to set the Doppler width for H and D in the fitting. The sensitivity of the evaluated D fraction on the velocity is increased for a higher D fraction. The error of the D fraction is calculated from the error in the fitted parameter and sensitivity on the velocity of the hot component. The difference in the profile and time trace of the D fraction with D pellet and H pellet injection was observed clearly by BCXS using a grism spectrometer.

In2S3 is a promising electron transporting material for solar cells. In this paper, In2S3 nanosheet arrays are grown on TiO2 films by a facile molecular precursor solution method for the first time. The composition, morphology and chemical valance states of the In2S3 nanosheet arrays are investigated by XRD, SEM, TEM and XPS techniques. Upon the in situ growth of CuInS2 nanoparticles into the In2S3 nanosheet arrays, the novel CuInS2 bulk heterojunction solar cells are obtained with a peak power conversion efficiency of 2.58% depending on the In2S3 nanosheet array height.

A melamine-based carbon foam was obtained from a melamine foam (2×2×2 cm3), which was then coated with graphene by immersing it in 400 mL of a suspension of reduced graphene oxide in water with concentrations of 25 to 100 mg/L. MoS2/graphene/carbonized melamine foam composites for use as catalysts for the hydrogen evolution reaction were synthesized by the hydrothermal growth of MoS2 nanosheets on the graphene-coated carbon foams in a mixed solution of molybdic acid disodium salt and thiourea. Results indicate that MoS2 nanosheets with a thickness of 15–20 nm were uniformly distributed on the three-dimensional carbon foam substrates coated with different amounts of graphene. The amount of graphene coating has a great influence on the hydrogen evolution performance. The composite prepared with a graphene concentration of 25 mg/L has the best electrochemical performance, its initial overpotential at a 10 mA cm–2 current density is 163 mV, and the corresponding Tafel slope is 76 mV dec–1. It has also the lowest impedance, which shows that coating the carbon foam with an appropriate amount of reduced graphene oxide accelerates electron migration and improves the hydrogen evolution performance.

Increasing environmental crises caused by exploring and using fossil fuels have compelled human being to develop innovative technologies to utilize renewable and sustainable energy sources. For this purpose, photovoltaic conversion of solar energy into electricity with solar cells is a promising and attracting way in that solar energy is clean and inexhaustible. Nowadays, the bottleneck in the application of solar cells on a large scale to sustainable energy generation still lies in lacking an efficient, stable and low-cost materials system for photon-to-electricity conversion. Perovskite materials are a class of materials widely applied in solar cells. Many evidences showed that the perovskite materials have both ferroelectric and photovoltaic properties, offering a special system called photoferroelectric materials. A built-in electric field established in these materials due to the ferroelectric property is more helpful for the separation of e-h pairs and enhancing the power conversion efficiency during photovoltaic process in solar cells. Here, we review the recent photoferroelectric perovskite solar cells (PPSCs). After giving a brief description of the structure and property of photoferroelectric perovskite materials, the device structures, working principles and characterization of PPSCs are introduced, followed by the state-of-the-art advances and the insights for the PPSCs based on oxide and halide perovskite materials. Finally, the main challenges in developing efficient PPSCs are discussed.

Hybrid solar cells are novel photovoltaic devices combining the advantages from organic and inorganic components. This paper mainly reviews our recent research advances in hybrid polymer-based solar cells (HPSCs) that have organic conjugated polymers as main electron donor and nanostructures of metal oxides (ZnO and TiO 2 ) as main electron acceptor in photoactive layer, with emphasis on the theoretical models for studying charge carrier transport dynamics by intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS), the preparation of nanomaterials for efficient devices, and the device performance related to nanostructural characteristics; a few examples of other hybrid solar cells that have a similar architecture but a different photovoltaic principle in respect to HPSCs are also included. Finally, main challenges in basic researches and practical applications of these solar cells are discussed.

Segregation of alloying solute toward clusters and precipitates can result in hardening and embrittlement of ferritic and ferritic/martensitic steels in aging nuclear power plants. Thus, it is essential to study the segregation of solute in α -Fe. In this study, the segregation of eight kinds of alloying solutes (Al, Si, P, S, Ga, Ge, As, Se) in defect-free system and at vacancy, divacancy, and self-interstitial atom in α -Fe has been systematically studied by first-principles calculations. We find that it is energetically favorable for multiple solute S or Se atoms to segregate in defect-free system to form solute clusters, whereas it is very difficult for the other solute atoms to form the similar clusters. With the presence of vacancy and divacancy, the segregation of all the solutes are significantly promoted to form vacancy-solute and divacancy-solute clusters. The divacancy-solute cluster is more stable than the vacancy-solute cluster. The most-stable self-interstitial atom 〈110〉 dumbbell is also found to tightly bind with multiple solute atoms. The 〈110〉-S is even more stable than divacancy-S cluster. Meanwhile, the law of mass action is employed to predict the concentration evolution of vacancy-Si, vacancy-P, and vacancy-S clusters versus temperature and vacancy concentration.

Purpose This research aims to provide a theoretical method and data supports for a future study on interfacial reaction mechanism and spreading mechanism between molten solder and V-shaped substrate, which also gives guidance for those complicated welding operation objects in brazing technique. Design/methodology/approach Wetting experiments were performed to measure the contact angles at different temperatures of molten Sn-3.0Ag-0.5Cu wetting on the quartz substrate with an included angle of 90°. According to the experimental results, the theoretical spreading morphology of molten solder on V-shaped substrate at corresponding temperature was simulated by Surface Evolver. Findings The theoretical morphology profiles of the molten solder sitting on the V-shaped substrate are simulated using Surface Evolver when the molten solder reaches spreading equilibrium. The spreading mechanisms as well as the impact of surface tension and gravity on interfacial energy of the molten solder wetting on the V-shaped groove substrate are also discussed where theoretical results agree well with experiment results. The contact area between the gas and liquid phases shows a tendency of first increasing and later decreasing. Otherwise, the spreading distance and the height of the molten solder increases as the droplet volume increases as the included angle and the contact angle are given as constants, and both the interfacial energy and the gravitational energy increase as well. This research has a wide influence on predicting the outcomes in commercial impact and also gives guidance for those complicated welding operation objects in brazing technique. Research limitations/implications It is of very important significance in both science and practice to investigate the differences between the flat surface and V-shaped surface. Some necessary parameters including intrinsic contact angle and surface tension need to be directly measured when the droplet spreads on the flat surface. The relevant simulation conclusions on the inherent characteristics can be given based on these intrinsic parameters. Compared with the flat surface, the V-shaped substrate is chosen for further discuss on the effects of gravity on the droplet spreading behavior and the changes of apparent contact angle which can only occurs as the substrate is inclined. Therefore, this research provides theoretical method and data supports for a future study on interfacial reaction mechanism and spreading mechanism between molten solder and substrate. Practical implications The research is developed for verifying the accuracy of the model built in Surface Evolver. Based on this verified model, other researches on the spreading distance along y-axis and the contact area that are especially difficult to be experimentally measured can be directly simulated by Surface Evolver, which can provides a convenient method to discuss the changes of horizontal spreading distance, droplet height and contact area with increasing the included angle of V-shaped substrate or with increasing the droplet volume. Actually, the modeling results are calculated for supplying the theoretical parameters and technical guidance in the welding process. Social implications This research provides theoretical method and data supports for a future study on interfacial reaction mechanism and spreading mechanism between molten solder and substrate, which has a wide influence on prediction the outcomes in commercial impact and also gives guidance for those complicated welding operation objects in brazing technique. Originality/value Surface Evolver, can also be used to discuss the structure and spreading mechanism of droplets on V-shaped substrates, which have not been discussed before.

The effects of Bi addition on the properties of Sn-3.0Ag-0.5Cu molten alloy on Cu substrates are discussed using wettability and interface microstructure analysis. The changes of the contact angles between Sn-3.0Ag-0.5Cu-xBi and Cu substrates with the spreading time are described by Dezellus model. It indicates that the spreading process is governed by the interfacial reaction during the dwelling time. The interface microstructure is observed to clarify the effects of reactions on the spreading behavior. It is found that Cu6Sn5 is formed adjacent to the solder and Cu3Sn appears over the substrate with Bi added at 613K, indicating that Bi exists between the intermetallics and the addition of Bi can hinder the diffusion of copper towards the interior of the solder. Therefore the existence of Bi decreases the agglomeration of Cu-Sn grains. The growth of intermetallics is thus limited and the shape of intermetallics transforms from scallop to zigzag consequently. However, the segregation phenomenon appears when the additive amount of Bi is more than 5.5mass %, which could lead to the occurrence of fracture and degrade the performance of Sn-3.0Ag-0.5Cu-xBi alloy. The results of the present study provide basic physical and chemical data for the application of lead-free solder in the future microgravity space environment.

A hybrid featuring the CuInS 2 quantum dots (CuInS 2 -QDs) on reduced graphene oxide (rGO) sheets is synthesized by a facile one-pot solvothermal approach with thiourea as S source, in which graphene oxide (GO) sheets are reduced into rGO sheets in course of the CuInS 2 -QDs aggregate growth. The growth mechanism of the hybrid is elucidated. It is found that adsorption of Cu 2+ cations mainly takes place at epoxy/hydroxyl groups on GO sheets at room temperature and the adsorbed Cu + cations resulting from the Cu 2+ reduction at solvothermal temperature act as the nucleation for the surface growth of CuInS 2 -QDs into three-dimensional aggregates on GO sheets that are simultaneously reduced into rGO sheets. Our results demonstrate that the rGO/CuInS 2 -QDs hybrid is an effective electron acceptor with a complementary absorption property for polymer-based solar cells. The solar cells based on rGO/CuInS 2 -QDs hybrid and poly(1-methoxy-4-(2-ethylhexyloxy)-p-phenylene vinylene) exhibit an efficiency of 1.5%, much higher than the counterpart devices of rGO sheets. The effects of CuInS 2 -QDs aggregates on device performance are discussed. In the long run, this work provides a potential hybrid electron acceptor for low-cost and efficient solar cell fabrication.

The accumulation of H at the small-angle tilt grain boundary (GB) in the W(001) surface is investigated, on the basis of the first-principles calculations. By exploring the solution and diffusion behaviors of H at the GB, we find that the small-angle GB can capture the H atoms nearby, serving as a nucleation site of H bubbles. With the increasing number of trapped H atoms, the GB expands gradually, and the GBs can be unripped with an areal density of H up to 5.0 × 1015 H atoms per cm2, leading to the formation of H bubbles. Moreover, H2 molecules are observed, when the areal density of H atoms in GB is over 6.6 × 1015 atoms per cm2. According to our calculations, we propose a possible formation mechanism of H bubbles observed in the experiment, which is valuable for improving the service performance of W as a plasma-facing material in nuclear fusion reactors.

Vanadium titano-magnetite is a significant resource in China, and in this study, we characterize its isothermal reduction mechanisms in the mixture of H2, CO, and N2 where the variables considered here include reduction time, reduction temperature, gas composition, and pellet size. The kinetics of the reduction process are mainly studied, which follows a shrinking core model. The results indicate that the reduction degree of oxidized VTM pellets increases with the increase of reduction time, reduction temperature but decreases with the increase of pellet size. Moreover, we found that an increase of H2/(H2+CO) ratio induces an increase of the reduction degree. Then the transformation of main Ti-bearing mineral phases is discussed, and the most probable reaction mechanism is revealed. In the whole reduction process, the kinetic results confirm the existence of an early stage and a latter stage, which are controlled by interface chemical reaction and diffusion, respectively. Furthermore, the results show that the diffusion-control step can be observably shortened with the decrease of pellet size because a thinner product layer is formed during the reduction process. Our study thus provides a valuable technical basis on the VTM industrial application.

To study the structural characteristics and physical properties of droplets sitting on the inclined substrates and cylindrical surfaces, wetting experiments are conducted in different cases. The profile curves of the droplets are recorded and extracted by a CCD camera and image processing, respectively. Contact angles are figured out by fitting the profile curves and taking the derivative at the front and rear triple points. Based on the experimental results, a Surface Evolver is employed to simulate the morphological changes by minimizing the total energy of the system. Furthermore, theoretical shapes and feature parameters, including the heights and the spreading distances of the droplets, which are hard to obtain by normal experimental measurements are provided. The contact-angle hysteresis when the heavy droplet sitting on the inclined substrate is discussed. Meanwhile, the evolutions of the contour of the three-phase contact line are predicted when heavy droplets spread on the convex and concave cyli...

CH3NH3PbBr3-based bulk perovskite solar cells with core/shell nanoarray as electron transporter are fabricated for the first time, and an efficiency of 4.31% under AM 1.5 illumination (100 mW/cm2) was achieved. It is found that the open-circuit voltage in the CH3NH3PbBr3/nanoarray devices is determined by the difference between the conduction band of ZnO core and the highest occupied molecular orbital of CH3NH3PbBr3, but significantly correlates with the quasi-Fermi levels of the electrons in ZnO and the holes in CH3NH3PbBr3; thermal annealing is an effective way to enhance the device short-circuit current density by increasing charge generation and reducing interfacial charge recombination. In the CH3NH3PbBr3/nanoarray devices, interfacial characteristics are vitally important to the device performance, which is mainly embodied by the existing CdS shell that provides additional absorption contribution, passivates ZnO surface defects, reduces interfacial charge recombination, and eliminates the decomposition of CH3NH3PbBr3 on ZnO surface during the thermal annealing treatment for improving perovskite crystallinity to increase photocurrent. Our major findings are expected to provide a guide to design the effective interfaces for spatial separation of photogenerated charge carriers in efficient perovskite solar cells.

To develop solution-processed and novel device structures is of great importance for achieving advanced and low-cost solar cells. In this paper, we report the solution-processed solar cells based on inorganic bulk heterojunctions (BHJs) featuring a bulk crystalline Sb2S3 absorbing layer interdigitated with a TiO2 nanoarray as an electron transporter. A solution-processed amorphous-to-crystalline transformation strategy is used for the preparation of Sb2S3/TiO2-BHJs. Steady-state and dynamic results demonstrate that the crystalline structure in the Sb2S3 absorbing layer is crucial for efficient devices, and a better Sb2S3 crystallization favors a higher device performance by increasing the charge collection efficiency for a higher short-circuit current, due to reduced interfacial and bulk charge recombinations, and enhancing the open-circuit voltage and fill factor with the reduced defect states in the Sb2S3 layer as well. Moreover, an evident contribution to photocurrent generation from the photogenerated holes in the Sb2S3 layer is revealed by experimental and simulated dynamic data. These results imply a kind of potential non-excitonic BHJ for energy conversion.

High-purity Cu2ZnSnS4 quantum dots (CZTS-QDs) with a size of 3–5 nm and a band gap of 1.67 eV are synthesized by a facile solvothermal method using simple chemicals in ethanol solvent. The CZTS-QDs have an ionization potential (IP) of −5.96 eV and an electron affinity (EA) of −4.33 eV, which are almost not changed after removal of capping molecules on them. Due to the favorable IP and EA positions with respect to those of poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene) (MEH-PPV), the CZTS-QDs act as effective electron acceptors for hybrid solar cells based on polymer/CZTS blends with MEH-PPV as the polymer. CZTS-QDs and MEH-PPV form type-II heterojunctions to enable the solar cells to have a promising open-circuit voltage of 0.63 V, and the efficient charge separation for neutral excited states produced either on the polymer or on the CZTS-QDs makes the solar cells have a wide spectral response extending to 900 nm. It is revealed that removal of capping molecules on the quantum dots mainly leads to a reduced polymer exciton diffusion effect on the electron transport dynamics due to the formation of wider CZTS charge transport channels and an increased short-circuit current (Jsc) in the solar cells, where the enhanced Jsc dominantly correlates with the increased charge transfer and collection efficiencies due to the improved charge transport property in CZTS channels.

Cells and tissues can undergo a variety of biological and structural changes in response to mechanical forces. Only few existing techniques are available for quantification of structural changes at high resolution in response to forces applied along different directions. Three dimensional-Magnetic Twisting Cytometry (3D-MTC) is a technique for applying local mechanical stresses on living cells. Here we describe a protocol for interfacing 3D-MTC with confocal fluorescence microscopy. In 3D-MTC, ferromagnetic beads are bound to the cell surface via surface receptors followed by their magnetization in any desired direction. A magnetic twisting field in a different direction is then applied to generate rotational shear stresses in any desired direction. This protocol describes how to combine magnetic field-induced mechanical stimulation with confocal fluorescence microscopy and provides an optional extension for super resolution imaging using stimulated emission depletion (STED) nanoscopy. This technology allows for rapid real time acquisition of a living cell’s mechanical responses to forces via specific receptors and for quantifying structural and biochemical changes in the same cell using confocal fluorescence microscopy or STED. The integrated 3D-MTC – microscopy platform takes around 20 days to construct and the experimental procedures require ~4 days when carried out by a life sciences graduate student.

Bare nonprecious metal oxides are generally considered to have low HER activity, but they have the advantages of abundant resources and low cost. Herein, a facile strategy to construct abundant oxygen vacancies with heterogeneous structures of oxygen-vacancies CoFe2O4/oxygen-vacancies cobalt oxides/nickel foam (Ov-CoFe2O4/CoOx/NF) is developed using gas-phase cation exchange. Benefiting from abundant oxygen vacancies, the strong interfacial coupling effects between oxygen-vacancies CoFe2O4 (Ov-CoFe2O4) and oxygen-vacancies cobalt oxides (Ov-CoOx), a nanorod structure and the highly conductive nickel foam support, Ov-CoFe2O4/CoOx/NF exhibits a low overpotential of 59 mV and achieved a current density of 10 mA cm−2 in a 1 M KOH solution. Ov-CoFe2O4/CoOx/NF//Ov-CoFe2O4/CoOx/NF exhibits a low water splitting voltage of 1.51 V at 10 mA cm−2. Density functional theory calculations suggest that oxygen vacancy and interfacial coupling effects can both improve conductivity of electrocatalysts. This study provides a facile design for simultaneous realization of oxygen vacancy modification and heterostructure, which may become a simple strategy to use oxides to improve HER performance.

The attainment of long-pulse, high-performance, fully non-inductive plasma is one of the major scientific objectives of EAST, using the ITER-like tungsten upper divertor. Understanding and optimizing the fast-ion behaviors is the critical issue to extending the performance of EAST. Recently, using both neutral beam injection (NBI) and radio frequency (RF; low hybrid, electron cyclotron, and ion cyclotron) heating, fully non-inductive high-βP scenarios with extension of fusion performance at high density and low rotation have been achieved, with βP up to 2.5, βN up to 2.0, H98y 2 > 1.1, and bootstrap current fraction (f BS) up to 50%. For previous long-pulse H-mode plasma at medium density, when NBI is added into RF plasma, βP is increased from 1.2 to 2.0 compared with RF-only discharges. In fact, f BS for both discharges is nearly the same, at ~22%. Analysis shows that the increase in βp is mostly due to fast ions which do not contribute significantly to the neoclassical bootstrap current. Thus, to obtain high-performance plasmas with improved bootstrap current fraction, key parameters (e.g. density, beam energy, etc.) must be further optimized. Experimental results show that high density improves bootstrap fraction also by reducing fast-ion slowing-down time and loss. The lower beam energy also mitigates fast-ion loss, which is better for heating and CD performance. The extension of high-performance, fully non-inductive experiments on EAST at high density and zero/low NBI torque can potentially offer unique contributions towards ITER and CFETR.

A bulk charge exchange spectroscopy system has been applied to measure the radial profiles of the hydrogen (H) and deuterium (D) density ratio in the isotope mixture plasma in a large helical device. Charge exchange lines of Hα and Dα are fitted by 4 Gaussian of H and D cold components and H and D hot components with 5 parameters by combining the measurement of plasma toroidal rotation velocity with carbon charge exchange spectroscopy. The radial profiles of the relative density of hydrogen and deuterium ions are derived from H and D hot components measured and the beam density calculated from beam attenuation calculation. A proof-of-principle experiment is performed by the H pellet and the D pellet injections into the H-D mixture plasma.

Recent Experimental Advanced Superconducting Tokamak (EAST) experiments have successfully demonstrated a long-pulse steady-state scenario with improved plasma performance through integrated operation since the last IAEA FEC in 2016. A discharge with a duration over 100 s using pure radio frequency (RF) power heating and current drive has been obtained with the required characteristics for future long-pulse tokamak reactors such as good energy confinement quality (H98y2 ~ 1.1) with electron internal transport barrier inside ρ < 0.4, small ELMs (frequency ~100–200 Hz), and good control of impurity and heat exhaust with the tungsten divertor. The optimization of X-point, plasma shape, the outer gap and local gas puffing near the low hybrid wave (LHW) antenna were integrated with global parameters of B T and line-averaged electron density for higher current drive efficiency of LHW and on-axis deposition of electron cyclotron heating in the long-pulse operation. More recently, a high β P RF-only discharge (β P ~ 1.9 and β N ~ 1.5, /n GW ~ 0.80, f bs ~ 45% at q 95 ~ 6.8) was successfully maintained over 24 s with improved hardware capabilities, demonstrating performance levels needed for the China Fusion Engineering Test Reactor steady-state operation. A higher energy confinement is observed at higher β P and with favorable toroidal field direction. Towards the next goal (≥400 s long-pulse H-mode operations with ~50% bootstrap current fraction) on EAST, an integrated control of the current density profile, pressure profile and radiated divertor will be addressed in the near future.

The identification of stem-cell-like cancer cells through conventional methods that depend on stem cell markers is often unreliable. We developed a mechanical method for selecting tumorigenic cells by culturing single cancer cells in fibrin matrices of ~100 Pa in stiffness. When cultured within these gels, primary human cancer cells or single cancer cells from mouse or human cancer cell lines grew within a few days into individual round colonies that resembled embryonic stem cell colonies. Subcutaneous or intravenous injection of 10 or 100 fibrin-cultured cells in syngeneic or severe combined immunodeficiency mice led to the formation of solid tumours at the site of injection or at the distant lung organ much more efficiently than control cancer cells selected using conventional surface marker methods or cultured on conventional rigid dishes or on soft gels. Remarkably, as few as ten such cells were able to survive and form tumours in the lungs of wild-type non-syngeneic mice.

Tungsten coating as a plasma-facing material on copper alloys is an important issue of a tokamak fusion device. Tungsten tile was created by means of plasma-spraying technology. The properties of t...

The magnetoresistance (MR){=[R(H) - R(0)]/R(0)} properties in ferromagnetic shape memory alloy of NiMnFeGa ribbons and single crystals, and NiFeGa ribbons have been investigated. It is found that the NiMnFeGa melt-spun ribbon exhibited GMR effect, arising from the spin-dependent scattering from magnetic inhomogeneities consisting of antiferromagnetically coupled Mn atoms in B2 structure. In the absence of these magnetic inhomogeneities, Heusler alloys seem to show a common linear MR behavior at around 0.8T(C), regardless of sample structures. This may be explained by the s-d model. At low temperatures, conventional AMR behaviors due to the spin-orbital coupling are observed. This is most likely due to the diminished MR from s-d model because of much less spin fluctuation, and is not associated with martensite phase. MR anomaly at intermediate field (rho(perpendicular to) > rho(parallel to)) is also observed in single crystal samples, which may be related to unique features of Heusler alloys. (C) 2011 Elsevier B.V. All rights reserved.

We report As-75 nuclear quadrupole resonance (NQR) studies on oxypnictide superconductors LaFeAsO1-xFx (x=0.08, 0.15) and LaNiAsO1-xFx (x=0, 0.06, 0.10, 0.12). In LaFeAsO0.92F0.08 (T-c=23 K), nuclear spin-lattice relaxation rate 1/T-1 shows no coherence peak just below T-c and decreases with decreasing temperature accompanied by a hump structure at T similar to 0.4T(c), which is a characteristic of the multigap superconductivity. In the normal state, the quantity 1/T1T increases with decreasing temperature to T-c, indicating that the existence of antiferromagnetic correlation originating from its multiple electronic band structure. On the other hand, LaNiAsO1-xFx shows a clear Hebel-Slichter (coherence) peak just below T-c, evidencing that the LaNiAsO1-xFx is a BCS superconductor. In the normal state, 1/T-1 T is constant in the temperature range 4

SiC@Al2O3 core-shell epitaxial nanowires have been synthesized via one-step process by simply heating evaporating Al source and C source on silicon substrate. Energy dispersive X-ray spectroscopy and transmission electron microscopy analysis of as-fabricated samples indicate that the core-shell nanowires consist of single-crystalline β-SiC core and thin cubic γ-Al2O3 shell. Epitaxial relationship is also observed between SiC core and Al2O3 shell. The corresponding growth model is proposed to describe the growth process of the core-shell epitaxial nanowires. Moreover, field emission measurement reveals the core-shell epitaxial nanowires have the excellent field emission property with low threshold electric field of 13.8 V μm−1.

Partially substituting Sb for In, we found an irreversible transformation of martensite to intermartensite at 90 K in Ni50Mn34In12Sb4 alloy during heating. The reverse transformation of martensite and intermartensite to the parent phase induced by a magnetic field has been investigated. The results indicate that, if a sufficiently high magnetic field is applied, the intermartensite state is no longer necessary as an intermediate state. Thus, a difference of the transformation originating from magnetic and from thermal energies has been found. In this competition, lattice distortions play an important role to promote the occurrence of the intermediate intermartensitic path.