Search

This study aims to identify a theoretical fair value of the Sharpe ratio. For this purpose, we propose a formula with a closed-form solution to estimate a fair, expected, or ex ante value for the Sharpe ratio by framing it in the option pricing model. We find that firm value, growth rate, return volatility, risk-free rate, and the maturity and face value of the debt contract are determinants of the Sharpe ratio. In particular, a firm’s investing and financing policies can affect the firm stock’s Sharpe ratios. Contrary to what might reasonably be expected, our results show that a firm with a higher equity value tends to have a lower Sharpe ratio value. The results show the potential and feasibility of integrating three fields in future research: performance evaluations, option pricing, and corporate finance.

Bisphenol A (BPA) in wastewater has high risks of causing biological feminization. During the wastewater treatment process, large amounts of BPA are accumulated in activated sludge. However, the mechanisms of BPA interacted with activated sludge are still unclear. Especially, the roles of extracellular polymeric substances (EPS), which are major components of activated sludge, in the removal of BPA have never been concerned. In this study, the binding interactions between sludge EPS and BPA are explored combining fluorescence spectroscopy and dynamic light scattering. The thermodynamic mechanisms driving the binding behavior of BPA to EPS are illustrated by isothermal titration calorimetry. The results indicate that the binding interaction between BPA and EPS is spontaneous. BPA mainly binds with the proteins of EPS by hydrophobic association. The random-coiled structure of EPS transforms into relatively condensed cores after binding with BPA. A neutral pH, high ionic strength, and high temperature promote the binding process, facilitating to stabilize BPA in sludge EPS. This study provides new insights into the roles of sludge EPS in the migration and removal of BPA in activated sludge system.

Treatment of coking wastewater is a great challenge due to their instinct characteristics of high concentration, complex composition and biological toxicity. In this work, a novel integrated system comprising three-dimensional electrochemical reactors (3DERs) and three-dimensional biofilm electrode reactors (3DBERs) in series is developed for coking wastewater treatment. Results indicate that 79.63% of COD as well as 76.30% of total nitrogen could be removed at the low energy consumption of 15.6 kWh/m3. 3DERs mainly contribute to COD and nitrogen removal through electrochemical oxidation/reduction, while 3DBERs are responsible for nitrification process by enriched functional microbes. After treating by the integrated system, only long-chain alkanes are left in the wastewater and the toxicity of effluent is significantly reduced. This integrated 3DERs-3DBERs system exhibits capability of simultaneously eliminating carbonaceous and nitrogenous contaminants in coking wastewater, and greatly saves the energy with synergy of electricity and biofilm.

Three-dimensional biofilm electrode reactors (3D-BERs) represent a novel technology for wastewater denitrification. Formation of mature electroactive biofilm on particle electrodes is crucial to realize successful denitrification in 3D-BERs. However, long start-up time and low electroactivity of the biofilm formed on particle electrodes limit the further application of 3D-BERs in wastewater treatment. In this work, self-assembled hybrid biofilms (SAHB) was cultivated on granular activate carbon particle electrodes of the 3D-BER by assembling nano ɑ-Fe2O3 into the biofilm. ɑ-Fe2O3 was selected due to its high affinity to bacterial outer-membrane cytochromes, an important mediator for microbial electron transfer. SAHB formed on particle electrodes were characterized and the denitrification performance of 3D-BERs was also investigated. Results indicate that nano ɑ-Fe2O3 plays positive roles in the start-up of 3D-BER, which captures more microbes into SAHB and constructs thick biofilm on particle electrodes. Special microorganisms with denitrification function related with genera of Hydrogenophaga and Opitutus are distinctively enriched in SAHB. Nano ɑ-Fe2O3 induced SAHB exhibit superior denitrification performance compared to natural biofilm. The average denitrification rate increases from 0.62 mg total nitrogen/L/h for natural biofilm to 1.73 mg total nitrogen/L/h for SAHB, mainly ascribed to accelerated nitrites reduction. Our work provides new technical solution to enhance nitrates removal in 3D-BERs and brings deep insights into application of bio-electrochemical system in wastewater treatment. Keywords: Hydrogen autotrophic denitrification, Nano ɑ-Fe2O3, Self-assembled hybrid biofilm (SAHB), Three-dimensional biofilm electrode reactors (3D-BERs)

Chemically enhanced primary sedimentation (CEPS) technology has been widely applied in Hong Kong, exhibiting excellent performance in contaminants removal from sewage. The generated CEPS sludge contains abundance of organics which could be recovered as volatile fatty acids (VFAs) by fermentation for further utilization. In this work, the effect of calcium peroxide (CaO2) on the fermentation of FeCl3 based CEPS sludge was investigated. The feasibility of utilizing the fermentation liquor as substrate for polyhydroxyalkanoates (PHAs) biosynthesis was also evaluated. Results demonstrated that CaO2 addition facilitated the disintegration of CEPS sludge and enhanced VFAs production. The maximum VFAs yield of 455.8 mg COD/g VSS was obtained with the dosage of 0.1 g CaO2/g SS, improving by 44.7% compared with the control sludge. Acetic and propionic acid were the predominant components of the VFAs. Microbial analysis indicated that CaO2 induced microbial reduction of Fe(III), accelerating the initial disintegration of FeCl3 based CEPS sludge. Microbial communities with hydrolysis and acidogenesis functions were enriched effectively. CaO2 treatment had no significant influence on the release of ammonia nitrogen (NH4+-N), while reduced the concentration of orthophosphate (PO43−-P) and ferrous (Fe2+) in fermentation liquor, that was beneficial to the further utilization as substrate for PHAs biosynthesis. The VFA-rich fermentation liquor was proved to be a suitable substrate for PHAs biosynthesis. After cultivation, the PHAs content in activated sludge reached 22.3%, which was comparable to those obtained using waste materials as carbon source. This integrated technology could be a superior alternative of realizing sludge disposal and bioplastic production simultaneously.

Antibiotics residuals in the environments receive wide concerns due to the high risk of generating antibiotic resistance. Natural organic matters (NOM) existed in the environments are considered to have the capacity of binding with organic contaminants, consequently influencing their speciation and transformation in the natural environments. To assess the migration of antibiotics in the environments, it is crucial to understand the binding mechanisms between NOM and antibiotics, which is still unclear due to the limit of available research methods. In this study, the interaction between fulvic acids (FA), one of the main components of NOM, and sulfamethazine (SMZ) was characterized by nuclear magnetic resonance (NMR) combined with surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC) technology. The parameters related to kinetics and thermodynamics of the interaction were determined, and the possible mechanisms driving the interaction were also proposed. In addition, density functional theory (DFT) was used to predict the binding mode between FA and SMZ to reveal the interaction mechanism. Results indicate that FA can effectively bound with SMZ to form a stable complex with a binding constant at the level of 103 L/mol. The kinetic parameters including association and dissociation constants were 29.4 L/mol/s and 6.64 × 10−3 1/s, respectively. Hydrophobic interaction might play significant roles in the binding interaction with ancillary contribution of π-π conjunction arising from the aromatic rings stacking of FA and SMZ.

Three-dimensional biofilm electrode reactors (3D-BERs) represent an environmentally acceptable and cost effective technology for refractory wastewater treatment. Previous studies on 3D-BERs primarily focused on treatment performance, and little information is available about the microscopic mechanisms of contaminant degradation. The reactions occurred on particle electrodes, the core units of the 3D-BERs served as both electrodes and biofilm carriers, are still unclear. This study comprehensively elucidated the synergistic effects of electricity and biofilm on Rhodamine B (RhB) removal in 3D-BERs from both macroscopic and microcosmic aspects. Continuous-flow 3D-BERs were operated to evaluate overall treatment performance. Batch experiments were conducted to explore the kinetics of RhB degradation as well as the contributions of various physical, chemical, and biological processes to RhB removal. The biofilm formed on the particle electrodes was characterized by imaging and microbial analyses. The results indicated that applying voltage promoted degradation of RhB. Three processes, including electro-adsorption, electrochemical oxidation and electro-biodegradation, were identified to contribute to RhB degradation. Microorganisms in the Rhodanobacter and Thiomonas genera were distinctively enriched under acclimation voltage, which was attributed to the accumulation of intermediates generated by electrochemical oxidation. This study demonstrated that the synergistic effects of electricity and biofilm were dependent on applying voltage, that would be beneficial to comprehensively understand the contaminants removal process in 3D-BERs.

The removal of high-concentration rhodamine B (RhB) wastewater was investigated in a three-dimensional electrochemical reactor (3DER) packed with granular activated carbon (GAC) particle electrodes. Response surface methodology (RSM) coupled with grey relational analysis (GRA) was used to evaluate the effects of voltage, initial pH, aeration rate and NaCl dosage on RhB removal and energy consumption of the 3DER. The optimal conditions were determined as voltage 7.25 V, pH 5.99, aeration rate 151.13 mL/min, and NaCl concentration 0.11 mol/L. After 30 min electrolysis, COD removal rate could arrive at 60.13% with an extremely low energy consumption of 6.22 kWh/kg COD. The voltage and NaCl were demonstrated to be the most significant factors affecting the COD removal and energy consumption of 3DER. The intermediates generated during the treatment process were identified and the possible degradation pathway of RhB was proposed. It is worth noting that 3DER also showed an excellent performance in total nitrogen (TN) removal under the optimal condition. The activated chlorine generated from chloride had great contributions to eliminate carbon and nitrogen of RhB wastewater. The treatment effluent had a good biodegradability, which was suitable for subsequent biological treatment.

An efficient cascade reaction of propargyl amines with AgSCF3 and KBr is developed, affording allenyl thiocyanates at room temperature in high yields. This transformation proceeds via the in situ formation of isothiocyanate intermediates, followed by a [3,3]-sigmatropic rearrangement. The resulting allenyl thiocyanates bearing 3-(electro-donating phenyl) substitutions without isolation can then be reacted with di-tert-butyl peroxide and AgSCF3 under reflux to generate novel allenyl trifluoromethylthioether compounds in moderate to good yields via a “one-pot” three-step process.

V-Cr-Ti alloys are promising structural materials for future nuclear systems. In this study, a laser melting deposition process has been applied to the fabrications of V-5Cr-5Ti alloys. Laser powers of 1200W, 1400W and 1600W, scanning speeds of 400 mm/min and 600 mm/min, and scanning strategies of single directional scanning and dual directional scanning have been applied to investigate the effects on the morphologies and microstructures of formed individual deposits and thin walls. The dual directional scanning is favored for fabricating thin walls with regular shape, comparing to the single directional scanning. Microstructures of the deposits and walls consist of columnar grains and equiaxed grains. Due to the effects on temperature gradients, both the laser powers and deposition duration show significant effects on the microstructural evolutions of the thin wall samples. As the laser power and deposition duration increase, columnar to equiaxed transitions have been observed. The regions containing columnar grains and equiaxed grains have a fiber texture and a random texture, respectively.

In this work, granular activated carbon (GAC) supported TiO2-SiO2 oxide (TiO2-SiO2/GAC) was prepared and packed in a three-dimensional electrochemical reactor (3DER) for the removal of acid orange 7 (AO7) dyeing wastewater. The characteristics and the electrocatalytic performance of the prepared TiO2-SiO2/GAC were investigated to verify the feasibility of TiO2-SiO2/GAC application as particle electrodes. Results show that the TiO2-SiO2/GAC could significantly improve the AO7 removal efficiency, extend service life of particle electrodes, and enhance the stability of 3DER system. Orthogonal array was designed to optimize the operation parameters of 3DER, which was determined as electric field intensity 1 V/cm, filling amount of TiO2-SiO2/GAC particles 200 g/L, electrolytic concentration (Na2SO4) 0.07 mol/L, pH 3, treatment time 120 min. Under the optimal condition, the AO7 decolorization rate and COD removal efficiency are 83.20% and 48.95% respectively. The possible intermediates generated in 3DER during AO7 decomposition were identified and the biodegradability of the effluent was also estimated. Results suggest that the 3DER with TiO2-SiO2/GAC particle electrodes could be an alternative for the pretreatment of dyeing wastewater before biological treatment.

To study the effects of the anthocyanin single component cyanidin-3-O-glucoside (Cy-3-glu) on the proliferation and migration of mouse melanoma cells and to elucidate the underlying mechanisms, B16-F10 cells were treated with different concentrations of Cy-3-glu. Cell viability was analyzed by a CCK-8 method. Cell migration was determined by the callus scratching technique. Cell cycle was measured by the flow cytometry. The expression levels of genes involved in cell cycle regulation were detected by real-time PCR. Protein expression levels of p-AKT, E-cadherin, N-cadherin and vimentin were analyzed by Western blot. The growth and migration of B16-F10 cells in C57BL/6J mice were monitored by the cryogenically cooled IVIS-imaging system. The results showed that Cy-3-glu significantly inhibited the growth (P0.001) and migration (P0.01) of B16-F10 cells, and arrested the cell cycle in the S phase. After Cy-3-glu treatment, the expression levels of p-AKT (P0.05), N-cadherin and vimentin (P0.001) were decreased significantly, and the expression level of E-cadherin was dramatically increased (P0.05). The size and weight of tumors and tumor metastasis in mice fed with a diet containing Cy-3-glu were significantly reduced (P0.05). In conclusion, Cy-3-glu inhibits proliferation and migration of B16-F10 cells by inhibiting the PI3K/AKT signaling pathway, cell adhesion and migration signals.

Coking wastewater is highly concentrated and extremely toxic, greatly challenging the treatment technologies. Conventional biological technology such as anaerobic-anoxic-oxic (A2O) system is inefficient, since various biological reactions are inhibited by toxicants in coking wastewater. In this work, a pilot-scale three-dimensional electrochemical reactor (3DER) is integrated into the A2O system as a pretreatment unit to improve the treatment efficiency of coking wastewater. The results indicate that 3DER pretreatment increased the biodegradability of coking wastewater, promoting the degradation of coking wastewater in A2O system. The integrated 3DER-A2O system can remove 94.4% of COD and 76.2% of TN from coking wastewater, and the energy consumption was only 0.22 kWh/kg COD and 4.69 kWh/kg TN. The components of coking wastewater were significantly simplified and the acute toxicity was reduced from 99% to 12% after the treatment. The integrated 3DER-A2O system provides a new solution for coking wastewater treatment, showing a promising application potential.

The completely biological degradation of Tetrabromobisphenol A (TBBPA) contaminant is challenging. Bio-electrochemical systems are efficient to promote electrons transfer between microbes and pollutants to improve the degradation of refractory contaminants. In particular, three-dimensional biofilm electrode reactors (3DBERs), integrating the biofilm with particle electrodes, represent a novel bio-electrochemical technology with superior treatment performances. In this study, the electroactive biofilm is cultured and acclimated on two types of particle electrodes, granular activated carbon (GAC) and granular zeolite (GZ), to degrade the target pollutant TBBPA in 3DBERs. Compared to GZ, GAC materials are more favorable for biofilm formation in terms of high specific surface area and good conductivity. The genus of Thauera is efficiently enriched on both GAC and GZ particles, whose growth is promoted by the electricity. By applying 5 V voltage, TBBPA can be removed by over 95% in 120 min whether packing GAC or GZ particle electrodes in 3DBERs. The synergy of electricity and biofilm in TBBPA degradation was more significant in GAC packed 3DBER, because the improved microbial activity by electrical stimulation accelerates debromination rate and hence the decomposition of TBBPA. Applying electricity also promotes TBBPA degradation in GZ packed 3DBER mainly due to the enhanced electrochemical effects. Roles of particle electrode materials in TBBPA removal are distinguished in this work, bringing new insights into refractory wastewater treatment by 3DBERs.

The wide application of bisphenol A (BPA) leads to the emergence of BPA residuals in natural water environments. Dissolved organic matter (DOM) existed in water can bind with BPA, hence influencing the migration and transformation of BPA in aquatic environments. pH is a crucial factor governing the binding interactions between DOM and BPA. However, the mechanisms driven the binding process under different pH conditions are still unclear. In this study, the interactions between BPA and humic acids (HA), a primary component of DOM, are investigated over a wide pH range of 3–12 by integrating fluorescence quenching, dynamic light scattering and microcalorimetry. pH dependence of the binding interactions between HA and BPA are interpreted from a thermodynamic perspective. The results indicate that HA can spontaneously interact with BPA to form a stable HA-BPA complex. With the increasing pH, the binding interactions change from entropy driven to entropy-enthalpy co-driven. Hydrophobic force dominate the binding interactions under acidic condition. The synergy of hydrophobic force and hydrogen bond promotes the binding process under neutral condition. Under alkaline conditions, electrostatic repulsion participates the binding process in addition to hydrophobic force and hydrogen bond, weakening the binding strength. Therefore, neutral pH is favorable for HA to bind with BPA, consequently enhancing the dissolution of BPA in natural water bodies. The results are beneficial to better understand the pH dependent distribution of BPA in aquatic environments.

In this study, zeolitic imidazolate framework-67 (ZIF-67) derived Co3O4/NiCo2O4 double-shelled nanocages (DSNCs) were fabricated and utilized as catalysts to activate peroxydisulfate (PDS) for bisphenol A (BPA) degradation. The results showed that Co3O4/NiCo2O4 DSNCs exhibited superior BPA degradation performance over Co3O4 NCs and NiCo2O4 NCs. PDS combined with the interfaces of both the Co3O4 inner shell and NiCo2O4 outer shell to form complex, inducing the nonradical oxidation of BPA by electron abstraction. The double-shelled hollow structure helped to increase the instantaneous concentration of reactants in the void space of Co3O4/NiCo2O4 DSNCs, thus promoting the decomposition of BPA. The Co3O4/NiCo2O4 DSNCs had high selectivity for BPA degradation and were resistant to halogens and background organic matter in wastewater. Our work indicated that metal-organic framework (MOF)-derived nanomaterials with a hollow structure have a promising application prospect for persulfate-based advanced oxidation technology.

Coking wastewater is highly toxic and refractory industrial wastewater, and is thus extremely challenging to treat. Currently, most treatment technologies focus on degrading carbonaceous pollutants, while insufficient attention is placed on ammonium nitrogen (NH4+-N), the most important nitrogenous contaminant in coking wastewater and with a high biological toxicity. In the current study, we developed an integrated electrochemical system comprising two three-dimensional electrochemical reactors (3DERs), two three-dimensional biofilm electrode reactors (3DBERs) and one three-dimensional biofilm electrode reactor for denitrification (3DBER-De) to treat coking wastewater rich in NH4+-N. Our integrated system is able to remove 70.7% of total nitrogen (TN) at the low energy consumption of 1.29 kWh m−3, and can reduce COD by 55.8%. The 3DERs primarily degrade NH4+-N, nitrate nitrogen (NO3−-N), and COD by electrochemical redox reactions, while the 3DBERs convert residual NH4+-N to NO3−-N by fusing biofilm and electricity. Moreover, the 3DBER-De further eliminates NO3−-N by bio-electrochemical denitrification. The coking wastewater is purified as it flows through the integrated treatment system, with only a few hydrocarbon residuals detected that are able to be readily biodegraded by conventional biological treatments. The proposed 3DERs/3DBERs/3DBER-De system provides a new solution for coking wastewater with high concentrations of NH4+-N.

Three-dimensional biofilm electrode reactors (3D-BERs) represent a novel technology for wastewater denitrification. Formation of mature electroactive biofilm on particle electrodes is crucial to realize successful denitrification in 3D-BERs. However, long start-up time and low electroactivity of the biofilm formed on particle electrodes limit the further application of 3D-BERs in wastewater treatment. In this work, self-assembled hybrid biofilms (SAHB) was cultivated on granular activate carbon particle electrodes of the 3D-BER by assembling nano ɑ-Fe

Triclosan (TCS) contaminant has aroused wide concerns due to the high risk of converting into toxic dioxin in aquatic environments. During the wastewater treatment process, considerable amounts of TCS are accumulated in activated sludge but the mechanisms are still unclear. Especially, roles of extracellular polymeric substances (EPS), the main components of activated sludge, in TCS removal have never been addressed. In this work, the binding properties of loosely-bound EPS (LB-EPS) and tightly-bound EPS (TB-EPS) of activated sludge to TCS are investigated by fluorescence quenching approach. The influences of aquatic conditions including solution pH, ionic strength and temperature on the interactions between EPS and TCS are explored. Possible interaction mechanisms are discussed as well as the corresponding environmental implication. Results indicate that binding processes of EPS to TCS are exothermic mainly driven by the enthalpy changes. The proteins components in EPS dominate the interactions between EPS and TCS by hydrogen bond and hydrophobic interaction. The binding strength could be improved under the condition of weak alkaline and relative high ionic strength. Generally, LB-EPS exhibit stronger binding ability to TCS than TB-EPS under neutral environment, playing more crucial roles in the binding process. This work highlights the important contributions of EPS to TCS removal, that is beneficial to comprehensively understand the migration of TCS in activated sludge system.

An efficient cascade reaction of propargyl amines with AgSCF

The applications of polypropylene/carbon fiber (PP/CF) composite are hindered by the high flammability of PP substrate. This work reports a facile solvothermal method to modify CF though grafting maleic anhydride (MAH) on its surface, with the goal of enhancing the compatibility of intumescent flame retardant (IFR) with PP substrate, thus enhancing the flame-retardant and mechanical performance of the resulting PP/CF/IFR composite. The effect of maleic anhydride-g-carbon fiber (MAH-g-CF) to IFR ratio on the overall performance of the composite was assessed. The possible interactions between MAH-g-CF and IFR were characterized by dynamic thermomechanical analysis and Fourier-transform infrared spectroscopy. Results show that when 3 wt% MAH-g-CF and 22 wt% IFR were added to the PP substrate, the composite exhibited a much lower heat release rate value and smoke suppression ability. Meanwhile, the composites achieved 26.7 MPa in tensile strength and 50.6 MPa in flexural strength. We propose that MAH on MAH-g-CF acts as a compatibilizer that improves the adhesion and cross-linking between CF and IFR, thereby enhancing mechanical strength and flame-retardancy of the PP/IFR/MAH-g-CF composite.

Functionalized SBA-15 with mesoscopic pore channels was synthesized by co-condensation of tetraethoxysilane and (3-aminopropyl) triethoxysilane (APTES) via hydrothermal process. Small-angle X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy were used to monitor the effect of surface functionalization on the structural and textural features of the SBA-15. The results suggested that the structural ordering of functionalized SBA-15, as well as pore diameters, pore volumes and surface areas, were decreased with increasing the APTES molar ratio. Candida rugosa lipase (CRL) was used as a model enzyme for studying the effect of amino-functionalized on loading amount and enzymatic activity. The effects of pH and temperature on catalytic hydrolysis of tributyrin by immobilized CRL were investigated. The results showed that immobilized CRL had a well adaptability in a wide pH and temperature region, and CRL immobilized on functionalized SBA-15 exhibited much higher enzymatic activity than free CRL, especially, 5 mol% APTES functionalized SBA-15 immobilized CRL displayed the highest activity.

In this paper, semi-automatic methods based on Gaussian random field (GRF) for online object labeling in video were presented. With a user specified region of interest (ROI), the interested object in all of the frames can be labeled. Two methods, i.e. Updated GRF with fixed SmartLabel (UGFS) method and fixed GRF with fixed SmartLabel (FGFS) method were proposed and compared. Evaluations on object categories have indicated that the UGFS method not only improves the real time performance of object labeling in video, but also has relatively high labeling accuracy.

Three-dimensional electrochemical reactor (3DER) is a highly efficient technology for refractory wastewater treatment. Particle electrodes filled between anode and cathode are the core units of 3DER, determining the treatment efficiency of wastewater. However, particle electrodes deactivation due to catalytic sites coverage seriously impedes the continuous operation of 3DER. In this work, granular sludge carbon (GSC) particle electrodes being resistant to deactivation are fabricated by pyrolyzing the mixture of waste sludge, polymethyl methacrylate (PMMA), and copper tailings, whose performances are evaluated by degrading rhodamine B (RhB) wastewater in a continuous-flow 3DER. Results indicate that hierarchical-pore structure comprising macro-, meso-, and micropores is developed in GSC-10-CTs by doping 10 g PMMA and 5 g copper tailings into 100 g waste sludge. PMMA contributes to construct macropores, which is essential for the mass transfer of RhB into GSC particle electrodes of centimeter-size. Copper tailings promote the formation of meso- and micro-pores in GSCs, as well as improving the electrochemical properties. Consequently, GSC-10-CTs packed 3DER exhibits the highest removal efficiency and lowest energy consumption for RhB treatment. In addition, the compressive strength of GSC-10-CTs is enhanced by copper tails, that is crucial to fill into 3DER as particle electrodes. The high-efficient and cost-effective GSC-10-CTs fabricated by waste materials have the potential of substituting commercial granular activated carbon catalysts in the future, consequently promoting the application of 3DER in wastewater treatment.

The Zr-N alloying layers were prepared on the surface of pure titanium substrates by plasma surface alloying technique to improve the surface properties. The microstructure, chemical composition, and hardness of Zr-N surface alloying layers were analyzed to understand the mechanisms of surface alloying and hardness improvement. The tribological performance of Zr-N surface alloying layers was studied by ball-on-disc wear machine. The results show that Zr-N alloying layers formed are homogeneous and compact. The Zr-N surface alloying layer consists of an outer nitride layer and an inner diffusion zone of zirconium and nitrogen. The surface treatment enhances the hardness of the surface layers of pure titanium substrates greatly and a surfaces hardness of HK1870 is obtained. Though Zr-N surface alloying layer does not show friction-reducing effect, it improves the wear resistance of pure titanium obviously.

Nitrogen doped titanium dioxide (N-TiO2) coatings were fabricated by oxidation of the TiNx coatings in air. TiNx coatings were prepared on stainless steel (SS) substrates by plasma surface alloying technique. The reference TiO2 sample was also deposited by oxidation of the Ti coatings in air. The as-prepared coatings were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and ultra violet-visible absorption spectroscopy (UV-Vis). The formation of anatase type TiO2 is confirmed by XRD. SEM measurement indicates a rough surface morphology with sharp, protruding modules after annealing treatment. The band gap of the N-doped sample is reduced from 3.25 eV to 3.08 eV compared with the undoped one. All the N-doped samples show red shift in photoresponse towards visible region and improved photocurrent density under visible irradiance is observed for the N-doped samples. The photocatalytic activity was evaluated via the photocatalytic oxidation of methylene blue (MB) in aqueous under visible light irradiation. The results reveal that the N-doped samples extend the light absorption spectrum toward the visible region. The degradation rate of N-TiO2 is 20% in visible irradiation for 150 min.

A simple and clean route to synthesize nano-scale mesoporous silver-silica composite aerogels was described here. The composite aerogels were obtained by adding a silver colloid to an about-to-gel silica sol prepared and then dried in supercritical anhydrous ethyl alcohol. The silver colloid and composite aerogels with silver content of 0wt%, 0.5wt%, 1wt% and 3.5wt% were characterized by UV-visible absorption spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD) and N2 Brunauer-Emmett-Teller (BET). The results show that silver nanoparticles with size about 40nm are successfully impregnated into the spongy porous structure of silica. The surface area decreases from 845 to 443m2/g with the increase of silver content. And the nanoscopic surface and bulk properties of each component are retained in the solid composite.

N-doped TiO 2 (N-TiO 2 ) coatings were obtained by oxidation of titanium nitride coatings, which were prepared by the plasma surface alloying technique on stainless steel (SS). The microstructure of N-TiO 2 coatings was characterized by X-ray diffraction (XRD), glow discharge optical emission spectrometry (GDOES), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. Ball-on-disc sliding wear was applied to test and compare the tribological behaviors of the coatings and substrate. XRD patterns showed that anatase type TiO 2 existed in the coatings after oxidation. GDOES showed that the resultant coatings had a layered structure, comprising of N-TiO 2 layer at the top and a diffusion-type interface. Such a hybrid coatings system showed good adhesion with the substrate. According to XPS, residual N atoms partially occupied O atom sites in the TiO 2 lattice. Uniform, continuous and compact coatings were observed by SEM images of coatings after oxidation. Under a load of 7.6 N, the coefficient of friction was in the range of 0.27–0.38 for the N-TiO 2 /Al 2 O 3 systems and the wear rate of the coatings was only one-fourteenth of that for untreated 316L SS. N-TiO 2 coatings displayed much better wear resistance and antifriction performance than SS substrate.

Aiming to the application of high-power LEDs in road lights, this article discusses the requirements of optical properties of LED road lights. It carries out the reflector-based secondary optical design of the selected LEDs, which is simulated with ASAP. The results show that this design can take full advantage of the optical properties of LED light sources, greatly improve the efficiency of LED road lights, and improve the uniformity of road lighting, so as to achieve the effects with which those effects produced from the traditional lights cannot be compared.

A novel process has been developed to improve tribological and corrosion properties of austenitic stainless steel (S. S). Titanium nitride coatings were obtained by plasma surface alloying technique. Nitrogen-doped titanium dioxide was synthesized by oxidative annealing the resulted TiNx coatings in air. The microstructure of TiO2coatings was characterized by SEM, GDOES, XPS and XRD, respectively. Simulated body solution (Hanks’ solution, 37°C) was used to characterize the electrochemical corrosion properties of the coatings and substrate. Ball-on-disc sliding wear was applied to test and compare the tribological behaviors of the coatings and substrate against Al2O3ball. Results reveal that the resultant coatings have a layered structure, comprising of N-doped TiO2layer at the top and a diffuse-type interface. Such a hybrid coatings system shows good adhesion with the substrate. Composition analysis shows that the coatings shield the substrate entirely. The N-doped TiO2coatings are anatase in structure as characterized by X-ray diffraction. The electrochemical measurements show that the corrosion potential positively shifts from -0.267 V for bare S. S to -0.275 V for N-doped TiO2coated S. S, and the corrosion current density decreases from 1.3 × 10-5A/cm2to 4.1 ×10-6A/cm2. Under a load of 7.6 N, the coefficient of friction is in the range of 0.27～0.38 for the N-doped TiO2and the wear rate of the coatings is only one-fourteenth of that for untreated 316L S. S. Duplex-treated N-doped TiO2coatings display much better wear resistance and antifriction performance than that of S. S.

Titanium surface alloyed layer was fabricated on 316L stainless steel substrate at 1000°C by means of the plasma surface alloying technique. The content of element titanium in the surface alloyed layer shows gradually tapering from surface to the inside of the substrate and it means an excellent metallurgical binding between the surface modified layer and 316L stainless steel substrate. The hardness of the titanium surface alloyed Layer is 1305HK0.5, which is much larger than that of the 316L stainless steel substrate. The wear performance of the treated and untreated 316L stainless steel was studied using a ball-on-disc sliding wear machine. Although the titanium surface alloyed layer does not show a friction-reducing effect, it improves the wear resistance of 316L stainless steel significantly and its wear rate is only one-fifteenth of that for untreated 316L stainless steel.

A novel one-dimensional coordination polymer, Catena-poly [bis(4-cyano-pyridyl) copper(II)-di-thiocyanate], 1∞ [CuII-(cypy)2(μN.S-SCN)2] (cypy = 4-cyano-pyridyl), was synthesized in a solution reaction of Cu(NO3)2·3H2O, 4-cyano-pyridine and KSCN in mole ratio of 1:2:2 at room temperature. Its crystal structure was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic crystal system, space group P21/c with cell parameters a = 1.0719(2), b = 1.8441(4), c =0.9144(2) nm, β = 110.49(3)° and Z = 4. A full-matrix least-squares refinement gave R1 = 0. 0393 and wR2= 0.0916 for 1554 reflections having 1 >2σ(I). The crystal is thermally stable up to approximately 170 °C.

The effect of precipitation on the internal friction (IF) of AZ91 magnesium alloy was investigated by using X-ray diffraction (XRD) analysis, scanning electron microscope (SEM) observation, and dynamic mechanical analysis (DMA). Six different states of alloy were prepared by applying different heat treatment processes: as-cast, in-complete solid solution, complete solid solution, micro-precipitation, continuous precipitation and continuous-discontinuous precipitation. It was found that the internal friction of in-completely solid-solutionized, completely solid-solutionized and micro-precipitated specimens showed a similar characteristic, and the grain boundary relaxation is completed depressed due to the Al atoms supersaturated in the alpha-Mg solution. However, a thermal relaxation internal friction peak was observed for continuously precipitated and continuously-discontinuously precipitated specimens at around 438 K and frequency of about 1 Hz, which was attributed to the grain boundaries relaxation. Furthermore, it was found that the relaxation of the beta-Mg(17)Al(12)/alpha-Mg phase interfaces should give its contribution to the background internal friction in the as-cast, continuously precipitated and continuously-discontinuously precipitated specimens.

Tempering temperature dependence of the amount of the reversed austenite in the range of 570 oC to 680 oC was investigated by means of X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM) in a low carbon Fe-13%Cr-4%Ni-Mo (wt.%) martensitic stainless steel. It was found that the reversed austenite began to form at the tempered temperature slightly above the As temperature. As the tempered temperature increased, the amount of the reversed austenite changed little in the temperature range of 580-595 oC. Then, the amount of the reversed austenite increased sharply with the increased tempered temperature. When the tempered temperature increased to about 620 oC, the amount of the reversed austenite exhibited a peak. Afterward, it decreased quickly at the elevated tempered temperature. The microstructural evolvement of the reversed austenite at different tempering temperature was also observed by TEM.

The promised performance of monolayer molybdenum disulfide (MoS2)-based devices is hindered by the high electrical resistance at the metal-MoS2 contact. Benefitting from the metallic phase of MoS2, 1T-MoS2 is considered a potential electrode material for the semiconducting 2H-MoS2. In this paper, we report a comparative study of the allotropic 1T/2H MoS2 contact with different contact types. The edge-contact interface has a low tunnel barrier, high charge density, and even Ohmic contact with no Schottky barrier, which implies that this contact may overcome the resistance limit for the electrode-MoS2 contact. The outstanding interface properties of the 1T/2H MoS2 edge contact originate from the excess in-plane dangling bonds in the edge position. Based on our results, the edge-contact model is ideal for the 1T/2H MoS2 contact and may solve the problem of MoS2 contact resistance.

One internal friction peak associated with the B2↔B19’ transformation appears on the cooling curve of porous NiTi shape memory alloy and the dense NiTi alloy shows the maximum peak. The tan δ value increased with the increasing of strain amplitude and the decreasing of frequency. Tan δ value of porous alloy mainly comes from the energy absorbing of the matrix at the small strain amplitude, however, if the strain amplitude is large, the tan δ value comes from the energy consumption that overcomes the friction between folds and the plastic contribution.

Titanium alloys are often material of choice for aerospace, chemical and biomedical industries, because of their unusual corrosion resistance, high mechanical strength and low density. However titanium alloys have very poor wear resistance. Hard coatings can be formed on the surface of titanium alloys to improve their tribological property. In this work ion nitriding without hydrogen technique was used to treat Ti-6Al-4V alloy and the nitrided layer was formed on the substrate surface. The fundamental coating properties, such as the phase, component, hardness and elastic modulus were investigated. At the ion-nitriding condition of flux ratio N2/Ar=1:1, pressure 40 pa and substrate temperature 900°C, the nitrided layer was formed. The layer consists of Ti2N and TiN compound. The content of element nitrogen in the nitrided layer gradiently decreases from the the surface to the substrate direction. For a better understanding of the hardness of the nitrided layer, the nano indentation test and microhardness test are both used. The results show that the average values of hardness and elastic modulus for the surface of the nitrided layer are 17.36GPa and 328.81GPa, about 6 times and 3 times respectively as those of Ti-6Al-4V substrate. The hardness of the nitrided layer decreases from the surface to the substrate direction, which corresponding to the content change of element nitrogen. For the result of nano indentation test, when the indentation depth is more than 400nm, the values of hardness and elastic modulus both decrease with the increase of the indentation depth. It is because of the influence of the soft Ti-6Al-4V substrate.