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  • articleNo Access

    STRATIFICATION MECHANISM AND INTERFACE CHARACTERIZATION OF (TiN), (TiC)/NiCrBSi COMPOSITE COATINGS SYNTHESIZED BY LASER REMELTING

    TiC/TiN-reinforced composite coatings were fabricated on the substrate of Ti–6Al–4V alloy using laser remelting. X-ray diffraction (XRD) was used to identify the phases in the laser-clad composite coating; the interface characterization of the dilution zone-clad zone (IDC) and the dilution zone-heat-affected zone (IDH) was observed with a scanning electron microscope (SEM). The results show that the microstructure of a cross-section has stratification characterization, and consists of the clad zone (CZ), the dilution zone (DZ), the diffusion layer (DL) and the heat-affected zone (HAZ). The layer-by-layer microstructure results from the boundary layer phenomenon of viscous melt-fluid and diffusion. The kind of reinforced particle has an effect on the interface morphology, microstructure and flow characterization of the melt-fluid. The phase constitution in the clad zone consists of (Cr–Ni–Fe), TiC, Ni4B3, Ti2Ni, Cr2B and M23C6 for TiC+NiCrBSi coating, and (Cr–Ni–Fe), TiN, NiB, Cr2Ti and Ti2Ni for TiN+NiCrBSi coating. The interfaces of the IDC in the NiCrBSi-clad layer is clear and clean; those of TiC+NiCrBSi and TiN+NiCrBSi are illegible. Ti–Ni phases with acicular microstructure link dilution zone and clad zone, and two kinds of phase with acicular microstructure, are similar in composition and shape.

  • articleNo Access

    PREPARATION AND MECHANISM OF CONTROLLABLE MICROPORES ON BIOCERAMIC TiO2 COATINGS BY PLASMA ELECTROLYTIC OXIDATION

    Porous titania coatings with Ca and P elements were synthesized by plasma electrolytic oxidation (PEO). The treatment was carried out in an electrolyte containing calcium acetate monohydrate and disodium phosphate dodecahydrate (Ca/P = 5), and 4–20 μm micropores were prepared on the coatings by applied pulse frequencies of 200–1000 Hz. The surface structure, chemical composition of the TiO2 coatings, and time-dependent variation of electric currents were studied. The result revealed that the coating micropores, which could be controlled in size, increased with higher frequency, and the coatings mainly consisted of anatase and rutile phases with varying fractions. Based on our experiment, the formation mechanism of micropores and phases of the PEO coatings was further discussed in details.

  • articleNo Access

    EFFECT OF GRAPHITE ADDITIVES IN ELECTROLYTES ON CHARACTERISTICS OF MICRO-ARC OXIDATION COATINGS ON 7E04 ALUMINUM ALLOY

    Micro-arc oxidation coatings were fabricated on 7E04 aluminum alloy substrates by micro-arc oxidation (MAO) in the electrolytes with the graphite addition varying from 0 to 8g/L (0, 2, 4, 6, 8g/L). The effect of graphite concentration on the surface morphologies, micro-hardness, thickness, phase composition and corrosion resistance of coatings was investigated. With the graphite powder concentration increasing, the oxidation voltage decreased gradually and the thickness of coatings firstly dropped down and then went up. It is found that the size of micro-pores and sintered discs declined with increase of graphite concentration. The XRD results indicated that MAO coatings mainly consisted of γ-Al2O3, θ-Al2O3, SiO2 and a little α-Al2O3. The corrosion resistance of coatings was improved with the addition of graphite powder. The study reveals that the appropriate graphite powder in the electrolytes is essential to promote the performance of the coatings.

  • articleNo Access

    SURFACE STRENGTHENING TECHNOLOGY FOR MECHANICAL PARTS

    This paper has summarized five surface strengthening methods, and these methods could to improve the surface properties of materials. The selection of mechanical parts materials has determined according to their working conditions. The work-piece in using cannot avoid defects in the material. This paper has introduced surface deformation enhancement, surface phase transformation enhancement, ion implantation technology, surface diffusion and infiltration technology, chemical transformation technology and surface coating technology. And has also included the principle of every surface technology, various technologies, parameters, strengthening characteristics, as well as strengthening effect and matters needing attention. The hardness, residual stress and corrosion resistance off mechanical parts could be improved through these surface strengthening methods. It is convenient to find the strengthening method and parameters in this paper when strengthening mechanical parts.

  • articleNo Access

    SPINAL DISPLACEMENT DURING THORACIC SPINAL MANIPULATIVE THERAPY

    Background: Vertebrae are linked together with facet and intervertebral joints. The application of a force to a spinal segment therefore impact adjacent areas of the spine. Objective: This study aimed to investigate the posteroanterior (PA) displacement of the thoracocervical spine during the application of thoracic PA mobilization. Methods: Forty-one healthy males were recruited. The participants were asked to lie prone and hold their breath at the end of normal expiration while a therapist applied a grade III of central PA mobilization to the T6 spinous process for 30s. The PA spinal displacements of C3, C5, C7, T2, T4 and T6 were investigated using a motion capture system. Descriptive statistics and Pearson’s correlation coefficient were used to analyze the PA spinal displacement and correlation between PA spinal displacement at T6 and the PA displacement of the thoracocervical spines, respectively. Results: The PA displacement of the T6 and the PA displacement of the marked spines (T4, T1, C7, C5 and C3) correlated well with r being 0.83, 0.69, 0.63, 0.63 and 0.54 (p<0.01), respectively. A trend toward a decrease in spinal displacement was noted when the distance from T6 spine increased. It showed that the mobilization force could be transferred from the local area to an adjacent area. Conclusions: These findings may provide plausible evidence that can explain the mechanism of how thoracic spinal manipulative therapy affects neck pain reduction.

  • articleNo Access

    EYE ON CHINA

      Amplified detection of nucleic acid by G-quadruplex based hybridization chain reaction.

      Dow opens Photovoltaics Films Application Lab in Shanghai.

      Researchers discover molecular mechanisms of left-right asymmetric control in the sea urchin.

      China mulls new rule on human genetic research.

      China to phase out organ donation from executed criminals.

      Charles River Laboratories to expand research models business in China.

      Chinese Science Academy Chief urges seizing on new technological revolution.

      BGI contributes genome sequencing and bioinformatics expertise.

      Taiwan government to encourage formation of smaller biotech funds.

    • articleNo Access

      BIOBOARD

        AUSTRALIA – Origins of plague: Scientists reveal the cause of one of the most devastating pandemics in human history.

        AUSTRALIA – Admedus releases interim phase I results for Herpes study.

        CAMBODIA – Study tags cause of malaria drug resistance in Cambodia.

        JAPAN – Discovery of mechanism by which sex hormone regulates aggressive behavior.

        SINGAPORE – Singapore's first influenza vaccines demonstrates favorable immunogenicity and tolerability in clinical testing.

        SINGAPORE – Scientists from Genome Institute of Singapore and Stanford University show RNA architecture expanding understanding of human genetics.

        SINGAPORE – “Bio-Timer” that synchronizes growth.

        SINGAPORE – Researchers make new discovery of protein as a promising target for treatment of anaplastic thyroid carcinoma.

        AFRICA – African project aims to stop rats in their tracks.

        AFRICA – African monsoon project to benefit crops and healthcare.

        CANADA – Cancer researchers discover pre-leukemic stem cell at root of AML relapse.

        EUROPE – Understanding heart failure at the cellular level.

        INDIA – Africa and India cultivate agricultural research ties.

        UNITED STATES – Three major genes set feather hue in pigeons.

        UNITED STATES – Mouse study shows gene therapy may be possible cure for Hurler syndrome.

        UNITED STATES – The ultimate decoy: Scientists find protein that helps bacteria misdirect immune system.

      • articleNo Access

        BIOBOARD

          INDIA – Plastic bricks could protect Indian homes from monsoon.

          THE PHILIPPINES – Philippines aims for better basic sanitation practices.

          SINGAPORE – A*STAR scientists discover gene critical for proper brain development.

          AFRICA – Project to conserve indigenous crops launched in Kenya.

          AFRICA – Cellphone voice and SMS tech developed to fight Ebola.

          AFRICA – Scientists say Kenya’s GMO ban stalling biotech R&D.

          AFRICA – Scientists unveil a plan to fight deadly banana disease.

          AFRICA – Drug resistance to kill 10 million a year by 2050.

          BANGLADESH – Aflatoxin threat in Nepal and Bangladesh.

          BANGLADESH – Daily multivitamin improves pregnancy outcomes in South Asia.

          EUROPE – New study describes, for the first time, a fundamental mechanism regulating a protein’s shape.

          UNITED STATES – Cells identified that enhance tumor growth and suppress anti-cancer immune attack.

          UNITED STATES – Scripps Research Institute scientists uncover new, fundamental mechanism for how resveratrol provides health benefits.

          UNITED STATES – Canopus BioPharma Inc. achieves positive results from an in vitro live Ebola virus study.

        • articleNo Access

          BIOBOARD

            SINGAPORE – NUS Researchers Uncover Potent Parasite-killing Mechanism of Nobel Prize-Winning Anti-Malarial Drug.

            SINGAPORE – Robotic Glove Invented by NUS Researchers Helps Patients Restore Hand Movements.

            UNITED STATES – Study Reveals Environment, Behavior Contribute to Some 80 Percent of Cancers.

            UNITED STATES – Probing the Mystery of How Cancer Cells Die.

            UNITED STATES – Liver Hormone Works Through Brain's Reward Pathway to Reduce Preference for Sweets & Alcohol.

            UNITED STATES – How Three Genes You've Never Heard of May Influence Human Fertility.

            UNITED STATES – Researchers Find Link between Processed Foods and Autoimmune Diseases.

            UNITED KINGDOM – Is Evolution More Intelligent Than We Thought?

            UNITED KINGDOM – Unravelling the Genetics of Pregnancy and Heart Failure.

            SWITZERLAND – New Global Framework to Eliminate Rabies.

            CANADA – Droughts Hit Cereal Crops Harder Since 1980s.

            TAIWAN – Discovery of Key Autophagy Terminator that Contributes to Cell Survival and Muscle Homeostasis.

          • articleNo Access

            Optimization for Harmonics Reduction and Path Generation of Linkage Mechanisms

            The optimal design of linkage mechanisms for path generation and motions with reduced harmonic content is investigated. The designs are carried out using a two-objective optimizer based on the fuzzy theory. As an illustration, the present approach is applied to the optimization of a five-bar hybrid mechanism driven by a constant speed motor and a servo motor. The dynamic characteristics of the servo motor are improved, as the harmonics in the servo motion are reduced.

          • articleNo Access

            ARSENIC REMEDIATION USING SURFACE FUNCTIONALIZED ULTRAFINE NANOPARTICLES

            Ultrafine nanoparticles owing to their increased surface to volume ratio, coupled with the ability to tune their surface properties through molecular modification have made them ideal for their detection and remediation of broad range of environmental contaminants. Arsenic contamination has become a worldwide epidemic and remediation of this problem needs the development of technology with improved materials and systems with high efficiency. In the present study, we have demonstrated a simple and efficient method using surface functionalized ultrafine iron oxide nanoparticles for absolute removal of arsenic from arsenic treated water with low contact time period and low adsorbent dose. The efficiency of arsenic removal has been drastically improved by considering nanoparticles of size 10 nm and subsequent surface engineering of the nanoparticles resulting more adsorption sites being exposed to arsenic. The mechanism for adsorption was identified through electron microscopic and spectroscopic studies. The adsorption equilibrium data were well fitted to Freundlich isotherm.

          • articleNo Access

            A BIO-INSPIRED POLYDOPAMINE APPROACH TO PREPARATION OF GOLD-COATED Fe3O4 CORE–SHELL NANOPARTICLES: SYNTHESIS, CHARACTERIZATION AND MECHANISM

            Nano18 Nov 2013

            A biomimetic and facile approach for integrating Fe3O4 and Au with polydopamine (PDA) was proposed to construct gold-coated Fe3O4 nanoparticles (Fe3O4@Au–PDA) with a core–shell structure by coupling in situ reduction with a seed-mediated method in aqueous solution at room temperature. The morphology, structure and composition of the core–shell structured Fe3O4@Au–PDA nanoparticles were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and X-ray photoelectron spectrometry (XPS). The formation process of Au shell was assessed using a UV-Vis spectrophotometer. More importantly, according to investigating changes in PDA molecules by Fourier transform infrared spectroscopy (FTIR) and in preparation process of the zeta-potential data of nanoparticles, the mechanism of core–shell structure formation was proposed. Firstly, PDA-coated Fe3O4 are obtained using dopamine (DA) self-polymerization to form thin and surface-adherent PDA films onto the surface of a Fe3O4 "core". Then, Au seeds are attached on the surface of PDA-coated Fe3O4 via electrostatic interaction in order to serve as nucleation centers catalyzing the reduction of Au3+ to Au0 by the catechol groups in PDA. Accompanied by the deposition of Au, PDA films transfer from the surface of Fe3O4 to that of Au as stabilizing agent. In order to confirm the reasonableness of this mechanism, two verification experiments were conducted. The presence of PDA on the surface of Fe3O4@Au–PDA nanoparticles was confirmed by the finding that glycine or ethylenediamine could be grafted onto Fe3O4@Au–PDA nanoparticles through Schiff base reaction. In addition, Fe3O4@Au–DA nanoparticles, in which DA was substituted for PDA, were prepared using the same method as that for Fe3O4@Au–PDA nanoparticles and characterized by UV-Vis, TEM and FTIR. The results validated that DA possesses multiple functions of attaching Au seeds as well as acting as both reductant and stabilizing agent, the same functions as those of PDA.

          • articleNo Access

            Novel α-FeOOH Nanorods/Ag3PO4 Semiconductor Composites with Enhanced Photocatalytic Activity and Stability

            Nano01 Jun 2016

            The composite α-FeOOH nanorods/Ag3PO4 photocatalyst has been successfully fabricated through a facile hydrothermal process combined with a successive in situ precipitation technique. The SEM and TEM images show that Ag3PO4 particles have been successfully loaded on the surface of FeOOH nanorods. The photocatalytic activities of the α-FeOOH/Ag3PO4 composite were investigated for their efficiency on the degradation of Rhodamine B (RhB) under ultra-violet light and visible light irradiation, and the results showed that the α-FeOOH/Ag3PO4 composite possessed remarkable photocatalytic activities. The enhanced photocatalytic activity can be attributed to the strong absorption in visible light and the effective separation of photogenerated hole–electron pairs between Ag3PO4 and α-FeOOH.

          • articleNo Access

            Preparation of N-Doped Graphene by Hydrothermal Method and Interpretation of N-Doped Mechanism

            Nano01 Feb 2017

            Nitrogen-doped graphene (NG) was generated by hydrothermal method, using GO as the raw material and formamide as the reducing-doping source. The composite material was characterized by Fourier transform infrared (FTIR) spectrum, X-ray diffraction (XRD) spectrum, X-ray photoelectron spectroscopy (XPS). The results showed that Nitrogen was successfully doped in the graphene. Through regulating the reaction temperature, time and the ratio of graphite oxide and formamide, the different nitrogen contents were obtained, the highest nitrogen content was 5.67%. NG was also synthesized by urea or ammonia, characterizing by XPS. The characterization results showed that for taking urea and ammonia as nitrogen source, pyrrolic-N was the main form of nitrogen existing, taking formamide as a nitrogen, pyridinic-N was the main form of nitrogen existing. Based on these experimental results by different nitrogen source, the N-doped graphene mechanism was interpreted.

          • articleNo Access

            Photocatalytic Activity of Reduced Graphene Oxide-SnSe Nanohybrids with Efficiency Interface Effect

            Nano01 Mar 2017

            Reduced graphene oxide-SnSe (rGO-SnSe) nanohybrids were synthesized with a solution chemical reaction at room temperature. The nanohybrids were characterized by various techniques for their microstructural and photocatalytic activities in photodegradation of alkaline dye malachite green in the water. The effects of rGO/SnSe ratio, initial solution pH, and H2O2 concentration on the photodegradation efficiency were studied. The SnSe nanocrystallines with nanoscale size and narrow bandgap were formed and uniformly adhered on the rGO surface. Raman analysis confirmed the reduction of GO. The experimental results indicated that the nanohybrids showed excellent sunlight-excited photocatalytic activity in degrading malachite green in the water. Significantly, the nanohybrids showed remarkable photo-Fenton-like catalytic activity. The photodegradation rates of the hybrids were greater than that of SnSe nanoparticles, increased with increasing rGO/SnSe ratio, and related to operation parameters. High photocatalytic activities were ascribed to the efficiency interface effect that was confirmed by the calculations of band energy level and photoconductivity. The TOC measurement further verified the photodegradation results. The nanoparticles and nanohybrids also showed excellent reusability.

          • articleNo Access

            Fabrication of Novel n-SrTiO3/p-BiOI Heterojunction for Degradation of Crystal Violet Under Simulated Solar Light Irradiation

            Nano01 Jun 2018

            Novel n-SrTiO3/p-BiOI heterojunction composites were successfully fabricated by loading SrTiO3 particles onto the surface of BiOI nanoflakes via a two-step method. The as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), energy-disperse X-ray spectroscopy (EDS), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), diffuse reflectance spectroscopy (DRS) and electrochemical measurements. The results show that the n-SrTiO3/p-BiOI heterojunction composites are composed of perovskite structure SrTiO3 and tetragonal phase BiOI. The composites exhibit excellent photocatalytic performance for the degradation of crystal violet (CV) solution under simulated solar light irradiation, which is superior to that of pristine BiOI and SrTiO3. The 30wt.%SrTiO3/BiOI composite is found to be the optimal composite, over which the dye degradation reaches 92.5% for 30min of photocatalysis. The photocatalytic activity of the 30wt.%SrTiO3/BiOI composite is found to be 3.94 times and 28.2 times higher than that of bare BiOI and SrTiO3, respectively. The reactive species trapping experiments suggest that O2 and holes are the main active species responsible for the CV degradation. In addition, the electrochemical measurements elucidate the effective separation of photoinduced electron–hole pairs. Moreover, on the basis of experimental and theoretical results, a possible mechanism for the enhanced photocatalytic performance of the SrTiO3/BiOI heterojunction composites is also proposed.

          • articleNo Access

            Experimental and Mechanism Investigation on Boiling Heat Transfer Characteristics of Alumina/Water Nanofluid on a Cylindrical Tube

            Nano01 Oct 2019

            Nucleate pool boiling heat transfer experiments have been conducted to nanofluids on a horizontal cylinder tube under atmospheric pressure. The nanofluids are prepared by dispersing Al2O3 nanoparticles into distilled water at concentrations of 0.001, 0.01, 0.1, 1 and 2wt.% with or without sodium, 4-dodecylbenzenesulfonate (SDBS). The experimental results showed that: nanofluids at lower concentrations (0.001wt.% to 1wt.%) can obviously enhance the pool boiling heat transfer performance, but signs of deterioration can be observed at higher concentration (2wt.%). The presence of SDBS can obviously enhance the pool boiling heat transfer performance, and with the presence of SDBS, a maximum enhancement ratio of BHTC of 69.88%, and a maximum decrease ratio of super heat of 41.12% can be found in Group NS5 and NS4, respectively. The tube diameter and wall thickness of heating surface are the influential factors for boiling heat transfer coefficient. Besides, we find that Rohsenow formula failed to predict the characteristics of nanofluids. The mechanism study shows that: the decrease of surface tension, which leads to the decrease of bubble departure diameter, and the presence of agglomerates in nanofluids are the reasons for the enhanced pool boiling heat transfer performance. At higher concentration, particle deposition will lead to the decrease of distribution density of the vaporization core, and as a result of that, the boiling heat transfer performance will deteriorate.

          • articleNo Access

            A Ratiometric Fluorescent Probe Based on Carbon Dots and Bimetallic Nanoclusters for the Assay of Copper Gluconate and Copper Sulfate

            Nano01 Sep 2021

            Doping Ag-enhanced and glutathione-stabilized Au nanoclusters (GSH–Ag/AuNCs) were prepared by the one-step ultraviolet radiation combined with microwave heating method. The effects of the molar ratio of Au–Ag and different types of energy suppliers on the fluorescent performance of GSH–Ag/AuNCs were studied in detail. After that, a new ratio fluorescent probe (RF-probe) based on the mixing of GSH–Ag/AuNCs with carbon dots (CDs) was designed for sensitive and selective determination of copper gluconate (CG) and cupric sulfate (CS). For the CDs–GSH–Ag/AuNCs RF-probe, the fluorescence (FL) of CDs (at 440nm) and that of alloy nanoclusters (NCs) (at 605nm) were, respectively, unaffected and strongly quenched in the presence of CG/CS at λex=370nm coming from the dynamic quenching process. Corresponding linear ranges and limit of detection (LOD) of the RF-probe for the CG/CS assay were estimated to be 0.17–6.20/0.17–5.62μmol/L and 16.80/15.95nmol/L, respectively. Furthermore, the proposed RF-probe was successfully used for the assays of CG in CG tablets and CG additive, and CS in infant formula and CS additive, respectively.

          • articleNo Access

            Nanoarchitectonics of AgBr/4A Zeolite Composites with Enhanced Photocatalytic Properties Under Visible Light

            Nano01 Feb 2022

            AgBr/zeolite photocatalysts with different mass ratios were synthesized by depositing AgBr on the surface of 4A zeolite via the one-step precipitation method. AgBr/zeolite with mass ratios of 1:1 exhibited the highest photocatalytic activity, resulting in the complete degradation of the methyl orange (MO) dye under visible-light irradiation for 30min. The photocatalysts were characterized by N2 adsorption–desorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–Vis diffused reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The AgBr particles around 4A zeolite were smaller than pure AgBr. The specific surface area of 1:1 AgBr/zeolite was much larger than that of pure AgBr, which indicates that 1:1 AgBr/zeolite possessed more active sites. The photocatalytic stability of 1:1 AgBr/zeolite was investigated, and MO degradation rate of 90.4% was achieved after five cycling runs. The trapping experiments showed that hydroxyl radical (OH), superoxide radical (O2), and hole (h+) were the reactive species responsible for removing MO, and h+ played a key role in MO removal. A possible reaction mechanism in AgBr/zeolite photocatalytic system for MO degradation was proposed.

          • articleOpen Access

            The backbone stereochemistry influences the intracellular distribution and uptake mechanism of oligoarginines

            D-arginine oligomers have been widely used as intracellular delivery vectors both in in vitro and in vivo application. Nevertheless, their internalization pathway is obscure and conflicting results have been obtained concerning their intracellular distribution. In this study, we demonstrate that octa-D-arginine (r8) undergoes diffuse localization throughout the cytoplasm and nucleus even at low concentrations and that r8 (r: D-arginine) enters the cells via direct membrane translocation, unlike R8 (R: L-arginine), of which endocytosis is the major internalization pathway. The observation that R8 and r8 enter the cells through two clearly distinct internalization pathways suggests that the backbone stereochemistry affects the uptake mechanism of oligoarginines.