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Low-frequency vibrations can effectively improve natural sandstone permeability, and higher vibration frequency is associated with larger permeability. However, the optimum permeability and permeability evolution mechanism for uranium leaching and the relationship between permeability and the change of chemical reactive rate affecting uranium leaching have not been determined. To solve the above problems, in this study, identical homogeneous sandstone samples were selected to simulate low-permeability sandstone; a permeability evolution model considering the combined action of vibration stress, pore water pressure, water flow impact force, and chemical erosion was established; and vibration leaching experiments were performed to test the model accuracy. Both the permeability and chemical reactions were found to simultaneously restrict U6+leaching, and the vibration treatment increased the permeability, causing the U6+leaching reaction to no longer be diffusion-constrained but to be primarily controlled by the reaction rate. Changes of the model calculation parameters were further analyzed to determine the permeability evolution mechanism under the influence of vibration and chemical erosion, to prove the correctness of the mechanism according to the experimental results, and to develop a new method for determining the optimum permeability in uranium leaching. The uranium leaching was found to primarily follow a process consisting of (1) a permeability control stage, (2) achieving the optimum permeability, (3) a chemical reactive rate control stage, and (4) a channel flow stage. The resolution of these problems is of great significance for facilitating the application and promotion of low-frequency vibration in the CO2 + O2leaching process.

0.5wt%MnO2-doped (1 − x)BaTiO3–xBiCoO3ceramics short as (1 − x)BT–xBC–M sintered in air and reducing atmosphere via solid-state process were investigated. The X-ray diffraction results showed that solid solubility in (1 − x)BT–xBC ceramics sintered in the air was higher than that in reducing atmosphere. (1 − x)BT–xBC–M ceramics sintered in air transformed from tetragonal to pseudo-cubic phase when x≥ 0.1. The scanning electron microscopy results indicated that the average grain size increased with the BC component increasing; however, opposite phenomena occurred in samples sintered in the reducing atmosphere. The dielectric temperature curves of samples sintered in reducing atmosphere were flatted with excellent insulation resistivity of an order of magnitude of 1013Ω·cm, while anomalous dielectric constant and dielectric loss of samples sintered in the air with deteriorated insulation resistivity of an order of magnitude of 107Ω·cm. The anti-reduction mechanism of (1 − x)BT–xBC–M system was explained by the “electron–hole” trapping effect and formation of defect dipoles MnTi″-VO··and 2CoTi′-VO··.

In this study, B4C-Al2O3multiphase ceramic composites were prepared by spark plasma sintering (SPS) and Y2O3was used as a sintering aid. Results show that in the range of 1350–1500°C, nearly full dense B4C-Al2O3multiphase ceramic composites with a high densification rate (4×10−3/s) can be fabricated. Addition of Y2O3can lead to reduce activation energy of densification and plastic flow mechanism during sintering of the ceramic composites. At the same time, Y2O3can react with Al2O3to form liquid Y3Al5O12, which can effectively reduce the densification temperature of the ceramic composites. With the increase of Y2O3content, the temperature was lowered from 1500 °C to 1350 °C. When the Y2O3content was 1.0 vol.%, relative density, hardness, fracture toughness, and flexural strength of the ceramic composites were 98.60%, 23.75 GPa, 4.89 MPa•m1/2, and 464.96 MPa, respectively. The toughening mechanism of the ceramic composites followed particle toughening and micro-crack toughening. The internal grains of the composites were tightly bonded, they were mainly fractured in the transgranular form and the cross section was relatively rough with a high bending strength of 450 MPa.

ABSTRACTResistance spot welding (RSW) process with protective coatings on advanced high-strength steels is a challenge. An ultimate tensile strength (UTS)1500 MPa grade hot stamping sheet steel(22MnB5) with Al–Si coating was employed for the RSW process in the present study. The effects of Al–Si coating on the microstructure of RSW joints and tensile-shear fracture behaviour were investigated. Strip-like Fe-(Al,Si) cladding on the surface of nugget tongues acted as the crack source and initiated the fracture. Two types of fatigue failure mode were observed: nugget pull-out with tearing of base material (BM) and eyebrow-shaped fracture along the BM width direction, corresponding to high and low loading levels, respectively. All fatigue fracture cracks were found to be originated along the Fe-(Al,Si) strip through the heat-affected zone.

Resistance spot welding (RSW) process with protective coatings on advanced high-strength steels is a challenge. An ultimate tensile strength (UTS)1500?MPa grade hot stamping sheet steel(22MnB5) with Al–Si coating was employed for the RSW process in the present study. The effects of Al–Si coating on the microstructure of RSW joints and tensile-shear fracture behaviour were investigated. Strip-like Fe-(Al,Si) cladding on the surface of nugget tongues acted as the crack source and initiated the fracture. Two types of fatigue failure mode were observed: nugget pull-out with tearing of base material (BM) and eyebrow-shaped fracture along the BM width direction, corresponding to high and low loading levels, respectively. All fatigue fracture cracks were found to be originated along the Fe-(Al,Si) strip through the heat-affected zone.

Nanocarbon materials (carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, etc.) are considered the ideal toughening phase of ceramic matrix composites because of their unique structures and excellent properties. The strengthening and toughening effect of nanocarbon is attributed to several factors, such as their dispersibility in the matrix, interfacial bonding state with the matrix, and structural alteration. In this paper, the development state of nanocarbon-toughened ceramic matrix composites is reviewed based on the preparation methods and basic properties of nanocarbon-reinforced ceramic matrix composites. The assessment is implemented in terms of the influence of the interface bonding condition on the basic properties of ceramic matrix composites and the methods used to improve the interface bonding. Furthermore, the strengthening and toughening mechanisms of nanocarbon-toughened ceramic matrix composites are considered. Moreover, the key problems and perspectives of research work relating to nanocarbon-toughened ceramic matrix composites are highlighted.

Background: Due to its high toxicity and bioaccumulation, the existence of mercury in the environment is always a big threat to human beings. In order to control mercury pollution, scientists have put great efforts in the past decades. Methods: Precipitation, adsorption, membrane separation, biological treatment and ion exchange are reviewed as a remover for mercury removal. For each material type, we not only reported on the removal mechanism, but also discussed the best areas for it. The correlation method and step-to-step focusing method have been used for references. Results: For better mercury removal, the ways above are compared together. The mechanisms of removing mercury in different ways are summarized in this paper. Conclusion: With the exploration and application of research, people have mastered a variety of mature technologies for the treatment of mercury-containing wastewater. Using inexpensive adsorbents is a cost-effective method for treating low concentrations of heavy metal wastewater. Ion exchange with a fast removal rate has been widely used in the field of heavy metal removal from wastewater. The biological treatment method can effectively treat low-concentration mercurycontaining wastewater. However, there is still a need to develop novel mercury removers with high capacity, fast removal rate, and low removal limit. Nanomaterials with a high specific surface area on substrate with synergistic effects, such as high adsorption and ion exchange, are the future research points.

Background: Photoluminescent materials have been used for diverse applications in the fields of science and engineering, such as optical storage, biological labeling, noninvasive imaging, solid-state lasers, light-emitting diodes, theranostics/theragnostics, up-conversion lasers, solar cells, spectrum modifiers, photodynamic therapy remote controllers, optical waveguide amplifiers and temperature sensors. Nanosized luminescent materials could be ideal candidates in these applications. Objective: This review is to present a brief overview of photoluminescent nanofibers obtained through electrospinning and their emission characteristics. Methods: To prepare bulk-scale nanosized materials efficiently and cost-effectively, electrospinning is a widely used technique. By the electrospinning method, a sufficiently high direct-current voltage is applied to a polymer solution or melt; and at a certain critical point when the electrostatic force overcomes the surface tension, the droplet is stretched to form nanofibers. Polymer solutions or melts with a high degree of molecular cohesion due to intermolecular interactions are the feedstock. Subsequent calcination in air or specific gas may be required to remove the organic elements to obtain the desired composition. Results: The luminescent nanofibers are classified based on the composition, structure, and synthesis material. The photoluminescent emission characteristics of the nanofibers reveal intriguing features such as polarized emission, energy transfer, fluorescent quenching, and sensing. An overview of the process, controlling parameters and techniques associated with electrospinning of organic, inorganic and composite nanofibers are discussed in detail. The scope and potential applications of these luminescent fibers also conversed. Conclusion: The electrospinning process is a matured technique to produce nanofibers on a large scale. Organic nanofibers have exhibited superior fluorescent emissions for waveguides, LEDs and lasing devices, and inorganic nanofibers for high-end sensors, scintillators, and catalysts. Multifunctionalities can be achieved for photovoltaics, sensing, drug delivery, magnetism, catalysis, and so on. The potential of these nanofibers can be extended but not limited to smart clothing, tissue engineering, energy harvesting, energy storage, communication, safe data storage, etc. and it is anticipated that in the near future, luminescent nanofibers will find many more applications in diverse scientific disciplines.

Yellowfin seabream (Acanthopagrus latus) is a hermaphroditic fish with male prematurity, which is also an economically important mariculture species in coastal areas of China. Although the production yield has been increasing in recent years, artificial breeding of this species remains imperfect due to the lack understanding of its sex differentiation mechanism. In this study, we conducted transcriptomic sequencing to screen for sex-related genes in different stage of the testis, ovotestis, ovary, hypothalamus, and pituitary tissues of yellowfin seabream. During gonad development (from intersex to mature stage), Gnrh3, Kiss2, and Dbhwere expressed in the hypothalamus and Lhband Fshbwere expressed in the pituitary. Sex-related genes such as Hsd11b1, Foxl2l, Amh, and Gsdfwere among the top 10 downregulated genes in the intersex testis compared with the mature testis. The expression of Hsd11b, Wnt, and Soxfamilies genes differed significantly in the sex change process among functional mature gonads. In addition, treatment with estradiol resulted in feminizing of the ovotestis. Inhibition of androgens or estrogens promoted ovarian or testicular steps of ovotestis development. In summary, we systematically evaluated gene expression profiles during yellowfin seabream gonad development from intersex to functional male or female. Our results confirmed that regulation by the hypothalamus-pituitary-gonad (HPG) axis and the promotion of sex steroid hormones acted on this process, and they provide a reference for further studies of the involvement of the HPG axis in sex change and of sex induction methods in yellowfin seabream.

The concentration of 210Po in the desulfurized waste water can be affected by the operation of the wet desulfurization system in the coal fired power plant (CFP). However, this correlation is poorly studied and documented in current literature. The aim of this study was to report 210Po concentration level in desulfurized waste water from a CFP using wet desulfurization system. The average concentration of 210Po in the waste water samples from wet desulfurization system was measured 2.4 ± 0.3E-3 Bq/L, 4 times higher than the concentration of 210Po in our control samples (sea water), which is 6.1 ± 1.4 E-04 Bq/L. The annual total discharge of 210Po by the waste water of desulfurization system was estimated to be 7.03 × 108Bq/GWa, which is much higher than the total release of 210Po in air from stack of a modern CFP.

A sub-rapidly solidified LaFe 11.6 Si 1.4 plate was fabricated directly from liquid by centrifugal casting method. The phase constitution, microstructure and magnetocaloric effect were investigated using backscatter scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and physical property measurement system. When the plate was annealed at 1373 K, τ 1 phase was formed by a solid-state peritectoid reaction. A first-order magnetic phase transition occurred in the vicinity of 188 K, and the effective refrigeration capacities reached 203.5 J/kg and 209.7 J/kg in plates annealed for 1 h and 3 h, respectively, under a magnetic field change of 3 T. It is suggested that centrifugal casting may become a new approach to prepare high-performance La–Fe–Si magnetocaloric plates for practical applications, which could largely accelerate the formation of τ 1 phase during high-temperature heat-treatment process due to refined and homogeneous honeycombed microstructure. [ABSTRACT FROM AUTHOR]

Background: Since the discovery of X-rays by Röntgen in 1895, X-rays have been widely applied in multiple disciplines and industries. Since the X-rays are well beyond human visibility, materials are used for the high-energy X-ray detections. This review focuses on the X-ray detection using nanomaterials. Methods: X-rays can be detected by (1) X-ray films, which is a traditional method for imaging; (2) phosphor- or scintillator-based detectors, which are used as an indirect detection method to convert the X-rays into visible lights; (3) semiconductor-based detectors, which are used as a direct detection method for X-ray imaging and X-ray exposure measurements; and (4) gas detectors, which are used for X-ray exposure measurements. Results: Materials for X-ray detection were summarized, including phosphors, scintillators, and semiconductors. Their characteristic properties were compared. Nano size effects on the X-ray detection were discussed. X-rays can be detected using random nanomaterials (nanoparticles, nanofibers and nanowires, nanocomposites). The scintillator and phosphor nanoparticles were found to exhibit enhanced luminescence and shortened decay time, while luminescence suppression was also observed. Assembly of a core/shell structure was suggested as a strategy to increase such luminescence intensity. Nanofibers and nanowires have been prepared for improved spatial resolution. Since it is expensive and also technically challenging to grow high-quality single crystal scintillators, alternative ways have been developed to fabricate nanocomposites with scintillator or phosphor nanoparticles that demonstrated high performance. For X-ray imaging, it is preferable to vertically align scintillator material to reduce light cross scattering and to achieve higher spatial resolution; ideally by confining the scintillator inside of walls with light guides. Finally, scintillators have been made in nanochannels for improved spatial resolution and light output. Conclusion: The application of nanomaterials for X-ray detection is limited when compared to other applications using nanomaterials. The research on X-ray detection using nanomaterials is an open field for conducting studies of excitation mechanisms, exploration of new scintillator materials, and applications of active compounds.

Background: Despite of the fact that nanocarbon can effectively improve mechanical properties and reduce mass density of Cu-matrix composites, there are lacking comprehensive reviews on preparation and properties of nanocarbon-reinforced Cu-matrix composites synthesized with carbon nanotubes (CNTs) or graphene nanoplates (GNPs). This review presents research on interfaces between nanocarbon/Cu and strengthening mechanisms of nanocarbon-reinforced Cumatrix composites, and existing problems in the research on these nanocomposites. Methods: Research articles in open literature related to nanocarbon-reinforced Cu-matrix composites were critically reviewed. Original research on this topic was also presented in this article. Results: Research results have shown that Cu-matrix composite materials have advantages of high strengths while retaining sufficient thermal and electrical conductivities. Nanocarbon can effectively improve mechanical properties, and reduce mass density of the Cu-matrix composites. Effective mechanical lock is formed between nanocarbon and Cu matrix, which enhances the properties of the composites. Since CNTs and GNPs have different characteristics, and consequently, Cu matrix can be enhanced to maintain its high conductivity, high mechanical properties and high wear resistance. Conclusion: Nanocarbon-reinforced Cu-matrix composites have been studied for the new energy applications, and these composites possess the potentials to reach the requirements for being light weighted and with enhanced mechanical and physical properties. Designed nanocarbon-reinforced Cu-matrix composites should satisfy application and environmental requirements in the new energy field with enhanced mechanical, physical and chemical properties.

As abnormal acidic pH symbolizes dysfunctions of cells, it is highly desirable to develop pH-sensitive luminescent materials for diagnosing disease and imaging-guided therapy using high-energy radiation. Herein, we explored near-infrared-emitting Cr-doped zinc gallate ZnGa2O4nanoparticles (NPs) in colloidal solutions with different pH levels under X-ray excitation. Ultrasmall NPs were synthesized via a facile hydrothermal method by controlling the addition of ammonium hydroxide precursor and reaction time, and structural characterization revealed Cr dopants on the surface of NPs. The synthesized NPs exhibited different photoluminescence and radioluminescence mechanisms, confirming the surface distribution of activators. It was observed that the colloidal NPs emit pH-dependent radioluminescence in a linear relationship, and the enhancement reached 4.6-fold when pH = 4 compared with the colloidal NPs in the neutral solution. This observation provides a strategy for developing new biomaterials by engineering activators on the nanoparticle surfaces for potential pH-sensitive imaging and imaging-guided therapy using high-energy radiation.

Development of three-dimensional nanoarchitectures on current collectors has emerged as an effective strategy for enhancing rate capability and cycling stability of the electrodes. Herein, a new type of three-dimensional porous iron vanadate (Fe0.12V2O5) nanowire arrays on a Ti foil has been synthesized by a hydrothermal method. The as-prepared Fe0.12V2O5nanowires are about 30 nm in diameter and several micrometers in length. The effect of reaction time on the resulting morphology is investigated and the mechanism for the nanowire formation is proposed. As an electrode material used in lithium-ion batteries, the unique configuration of the Fe0.12V2O5nanowire arrays presents enhanced capacitance, satisfying rate capability and good cycling stability, as evaluated by cyclic voltammetry and galvanostatic discharge–charge cycling. It delivers a high discharge capacity of 293 mAh·g–1at 2.0–3.6 V or 382.2 mAh·g–1at 1.0–4.0 V after 50 cycles at 30 mA·g–1.

Ultrafine iron-palladium (FePd) nanoalloys deposited on γ-Fe2O3, FePd–Fe2O3, further anchored on carboxyl multiwalled carbon nanotubes (MWNTs–COOH), FePd–Fe2O3/MWNTs, were successfully synthesized by a facile one-pot solution based method as thermally decomposing palladium acetylacetonate (Pd(acac)2) and iron pentacarbonyl (Fe(CO)5) in a refluxing dimethylformamide solution in the presence of MWNTs–COOH. A 3.65 fold increase of peak current density was observed in cyclic voltammetry (CV) for ethanol oxidation reaction (EOR) compared with that of Pd/MWNTs after normalizing to Pd mass. The greatly enhanced tolerance stability toward poisoning species and largely reduced charge transfer resistance were also obtained in chronoamperometry and electrochemical impedance spectroscopy due to the downward shifted d-band center of FePd alloy, easily formed oxygen containing species on Fe2O3, and the stabilizing role of the MWNTs.

Carboxyl multi-walled carbon nanotubes (MWNTs-COOH) decorated with different palladium (Pd) nanoparticle loadings were synthesized by thermally decomposing different amounts of palladium acetylacetonate (Pd(acac)2) in a refluxing xylene solution with a fixed amount of dispersed MWNTs-COOH. The increased ratio of D band/G band and the decreased area ratio of oxygen containing groups (COOH, C-O and C=O) to C-C group suggested an increased occupation of defects on MWNTs. Transmission electron microscope (TEM) revealed different distributions of Pd NPs on the MWNTs with the variation of Pd(acac)2 amount and the particle size increased with increasing the Pd loading. A relatively higher conversion of Pd(acac)2 to Pd (76.21%) was achieved when the initial precursor ratio of Pd(acac)2 to MWNTs was 2 : 1 (product denotes as Pd/MWNTs-(2:1)). The Pd/MWNTs-2:1 catalysts were demonstrated to exhibit the most efficient performance toward ethanol oxidation reaction (EOR) among all the precursor ratios, which is evaluated by the highest Pd mass-based peak current density (1.23 A/mg Pd) and stable current density (0.175 A/mg Pd) in cyclic voltammetry (CV) and chronoamperometry (CA). In addition, both reduced charge-transfer resistance and increased reaction kinetics with increasing the Pd loading were obtained from electrochemical impedance spectroscopy (EIS) and Tafel characterization.

Highly efficient electromagnetic field absorption at gigahertz (GHz) was reported in the novel magnetic polymer nanocomposites (MPNCs) with in-situ synthesized Fe@Fe2O3core@shell nanoparticles (NPs) or their decorated multiwall carbon nanotubes (MWNTs) dispersed in the polypropylene (PP) matrix through a one-pot bottom-up method. PP grafted maleic anhydride (PP-g-MA) with different molecular weights served as surfactant to stabilize the in-situ-formed NPs and simultaneously as compatibilizer to enhance the bonding at the PP–filler interfaces. Because of the strong magnetization of the PP MPNCs filled with 20.0 wt % Fe@Fe2O3NPs stabilized by PP-g-MA (Mn= 800), a minimum reflection loss (RL) of −31.5 dB was observed at 18.0 GHz, and the frequency bandwidth with RL lower than −10.0 dB was 3.1 GHz (from 16.9 to 20.0 GHz) in the MPNC sample with a thickness of 5.5 mm. However, due to the lack of magnetic loss, only a weak RL of 4.3 dB was found at frequency of 16.8 GHz for the PP/PP-g-MA (Mn= 800)/1.0 wt % MWNTs nanocomposites sample with a thickness of 5.5 mm. When the PP MPNCs filled with Fe@Fe2O3NPs decorated MWNTs (sample thickness of 5.0 mm) in the presence of low molecular weight PP-g-MA (Mn= 800), the RL of −24.5 dB at 20.0 GHz was observed. Through simply changing Mnof PP-g-MA from 800 to 8000, more oxidized iron resulted in a decreased permeability and smaller RL in the high frequency range. The in-situ-formed nanofillers significantly reduced the flammability of PP for potential wide applications.

A small external magnetic field of 0.072T was reported to significantly influence the specific capacitances of the supercapacitor with magnetic carbon - metal (iron, cobalt or nickel) oxides microtubular nanocomposite fabrics as flexible electrodes. The decorated metal oxide species and annealing method (microwave-assisted vs. conventional tubular annealing) were discovered to play important roles in the increase or decrease of the capacitance. All the electrodes demonstrated excellent cycling retention performances, for example, upto ~350% for nickel oxide doped carbon nanocomposite electrodes. The corresponding mechanism for the magnetic field influence on the capacitance has been interpreted in term of a synergistic effect of three internal resistances, solution resistance in electrolyte solution, charge transfer resistance at electrode/electrolyte interface and leakage resistance in electric double layer region. The applied magnetic field is able to change the solution resistance due to the magnetohydrodynamic phenomena as well as the electrode resistance (directly corresponds to charge transfer resistance) by the magnetoresistance (MR) behavior.

Abstract

A silver inserted metal oxide (Ag–TiO2) has been demonstrated to be an effective biocidal agent against prokaryotic microbes found in water. Transmission electron microscopy and electron energy loss spectroscopy indicated cellular damage after co-incubation with the nanocomposite, showing concomitant leakage of ions, which are critical for cell survival.

The binary indium–thallium (In–Tl) alloy is a classic type of shape memory alloy with a low melting temperature. In–Tl nanowires (NWs) were prepared by a simple mechanical injection of liquid metal method using anodized aluminum oxide (AAO) as a template. Sample preparation procedures are given in detail, including the AAO fabrication and mechanical injection techniques. Transmission electron microscopy (TEM) was utilized to characterize the NWs. It was revealed that the NWs were composed of polycrystals with high crystallinity. By in situ heating the NWs in the TEM, reversible transformations between the parent and the martensite phases were observed in both large and small NWs.The binary indium–thallium (In–Tl) alloy is a classic type of shape memory alloy with a low melting temperature. In–Tl nanowires (NWs) were prepared by a simple mechanical injection of liquid metal method using anodized aluminum oxide (AAO) as a template. Sample preparation procedures are given in detail, including the AAO fabrication and mechanical injection techniques. Transmission electron microscopy (TEM) was utilized to characterize the NWs. It was revealed that the NWs were composed of polycrystals with high crystallinity. By in situ heating the NWs in the TEM, reversible transformations between the parent and the martensite phases were observed in both large and small NWs.

Polyaniline (PANI)/tungsten oxide (WO3) nanocomposite films were fabricated by electropolymerization of aniline monomers onto WO3coated indium tin oxide (ITO) glass slides, which were prepared by spin coating technique and followed by annealing at 500 °C for 2 h. The morphology and crystalline structure of the composite films were studied using Fourier transform infrared (FT-IR) spectroscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results confirm chemical interactions between the polymer matrix and the WO3particles and reveal a well crystallized PANI/WO3nanocomposite structure. The optical properties and electrochemical capacitive behaviors of the composite films for electrochromic (EC) and energy storage devices applications were investigated using spectroelectrochemistry (SEC), cyclic voltammetry (CV) and galvanostatic charge–discharge measurements. The composite films show dual electrochromism at both positive and negative potentials arising from PANI and WO3, respectively. A coloration efficiency of 98.4 cm2C–1was obtained for the composite film, which was much higher than that of WO3(36.3 cm2C–1) and PANI (50.0 cm2C–1) thin film. An areal capacitance of 0.025 F cm–2that is comparable to that of pure PANI (0.075 F cm–2) is derived from CV at a scan rate of 5 mV/s with a broader working potential window of 1.3 V. The cyclic stability studies reveal that the composite films exhibit much more enhanced durability and retain significant charge storage or discharge capacity after 1000 charge–discharge cycles. However, pure PANI loses most of the charge storage or discharge capacity after 350 cycles. The chemical bonding between PANI matrix and WO3particles is believed to play an important role in enhancing the stability of the nanocomposite film.

Magnetic epoxy polymer nanocomposites (PNCs) reinforced with magnetite (Fe3O4) nanoparticles (NPs) have been prepared at different particle loading levels. The particle surface functionality tuned by conductive polyaniline (PANI) is achieved via a surface initiated polymerization (SIP) approach. The effects of nanoparticle loading, surface functionality, and temperature on both the viscosity and storage/loss modulus of liquid epoxy resin suspensions and the physicochemical properties of the cured solid PNCs are systematically investigated. The glass transition temperature (Tg) of the cured epoxy filled with the functionalized NPs has shifted to the higher temperature in the dynamic mechanical analysis (DMA) compared with that of the cured pure epoxy. Enhanced mechanical properties of the cured epoxy PNCs filled with the functionalized NPs are observed in the tensile test compared with that of the cured pure epoxy and cured epoxy PNCs filled with as-received NPs. The uniform NP distribution in the cured epoxy PNCs filled with functionalized NPs is observed by scanning electron microscope (SEM). These magnetic epoxy PNCs show the good magnetic properties and can be attached by a permanent magnet. Enhanced interfacial interaction between NPs and epoxy is revealed in the fracture surface analysis. The PNCs formation mechanism is also interpreted from the comprehensive analysis based on the TGA, DSC, and FTIR in this work.

Peptide-based hydrogels are attractive biological materials. Study of their self-assembly pathways from their monomer structures is important not only for undertaking the rational design of peptide-based materials, but also for understanding their biological functions and the mechanism of many human diseases relative to protein aggregation. In this work, we have monitored the conformation, morphological, and mechanical properties of a hydrogel-forming peptide during hydrogelation in different dimethylsulfoxide (DMSO)/H2O solutions. The peptide shows nanofiber morphologies in DMSO/H2O solution with a ratio lower than 4:1. Increased water percentage in the solution enhanced the hydrogelation rate and gel strength. One-dimensional and two-dimensional proton NMR and electron microscopy studies performed on the peptide in DMSO/H2O solution with different ratios indicate that the peptide monomer tends to adopt a more helical structure during the hydrogelation as the DMSO/H2O ratio is reduced. Interestingly, at the same DMSO/H2O ratio, adding Ca2+not only promotes peptide hydrogelation and gel strength, but also leads to special shear-thinning and recovery properties of the hydrogel. Without changing the peptide conformation, Ca2+binds to the charged Asp residues and induces the change of interfiber interactions that play an important role in hydrogel properties.

Polyaniline (PANI) polymer nanocomposites (PNCs) filled with barium titanate (BaTiO3) were synthesized by a surface initiated polymerization method. Two different particle sizes (100 and 500 nm) were studied. By varying the loading level, size of BaTiO3nanoparticles (NPs) and stirring method for the polymerization process, a series of PNCs were obtained and the effects of these parameters on the crystalline structure, thermal stability, morphology, electrical conductivity and dielectric permittivity were systematically studied. FT-IR analysis indicated a strong interaction between the formed PANI and the BaTiO3NPs, and TEM observations showed that the BaTiO3NPs are well coated with a PANI layer, however, the thickness of the PANI layer decreased with increasing the BaTiO3particles loading. The XRD reflection patterns indicated that the crystallinity of the polyaniline part in the PNCs depends on the nanoparticle loading. However, the resistivity does not increase with increasing the crystallinity, and the temperature dependent resistivity result reveals a 3-d variable range hopping (VRH) electron transport mechanism. The BaTiO3loading dependent resistivity is interpreted from the dominating space charge on the BaTiO3/PANI interface and the ferroelectric nature of BaTiO3for the PNCs with different particle loadings. Compared with the positive real permittivity for the PNCs prepared from physical mixing, all the chemically synthesized PNC samples show negative dielectric permittivity and the permittivity change is related to the instinct metallic state in PANI. In addition, positive magnetoresistance (MR) is observed in all kinds of PNCs and analyzed theoretically from the wave function shrinkage model.

Biogenic silica nanoparticles (25–30 nm in diameter) were synthesized from rice husks. The characterizations revealed that the silica nanoparticles were composed of smaller primary particles (ca. 4.2 nm in diameter), and their clustering led to a porous structure with a surface area of 164 m2/g. Under the controlled melting catalyzed by K+, such silica nanoparticle clusters can gradually fuse to form semicrystalline porous silica frameworks with tunable pore size and structural integrity.

Magnetic graphene nanoplatelet composites (MGNCs) decorated with core-shell Fe-Fe2O3 nanoparticles (NPs) have been synthesized using a facile one-pot thermal decomposition method. The graphene nanoplatelets (GNPs) decorated with uniformly dispersed NPs are observed to exhibit a strong magnetization and can be magnetically separated from the liquid mixture by a permanent magnet. These MGNCs demonstrate an effective and efficient adsorption of arsenic(III) in the polluted water due to the increased adsorption sites in the presence of magnetic NPs. The adsorption behavior is well fitted with both Langmuir and Freundlich models, which show a significantly higher adsorption capacity (11.34 mg/g) than the other adsorption values reported on the conventional iron oxide based adsorbents ([?]1 mg/g). The results show a nearly complete As(III) removal within 1 ppb.

The high performance multi-walled carbon nanotubes (MWNTs) reinforced epoxy polymer nanocomposites (PNCs) have been synthesized at different MWNT loading levels. The surface functionalization of MWNTs with conductive PANI was achieved by using a facile surface initiated polymerization method with the aid of the oxidations of CNTs and subsequent anilines by hexavalent chromium (Cr(vi)) oxidant. The effects of MWNT loading, surface functionalization and temperature on the rheological behaviors of liquid epoxy resin nanosuspensions and on the physicochemical properties of cured solid PNCs were systematically investigated. The glass transition temperature (Tg) of the cured epoxy PNCs filled with functionalized MWNTs obtained from the dynamic mechanical analysis (DMA) test was increased about 6–25 °C than that of cured pure epoxy. The PNCs reinforced with functionalized MWNTs demonstrated an enhanced tensile strength than either cured pure epoxy or its PNCs filled with the as-received MWNTs. The electrical conductivity of cured epoxy PNCs with functionalized MWNTs was improved by 5.5 orders of magnitude compared with cured pure epoxy. Thermogravimetric analysis (TGA) revealed an enhanced thermo-stability in the cured epoxy PNCs filled with functionalized MWNTs than that of cured pure epoxy and its PNCs filled with the as-received MWNTs. The observed strong interfacial interaction between MWNTs and the epoxy resin matrix was responsible for the enhanced mechanical tensile strength. The nanocomposite formation mechanism is proposed based on the analysis from Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), Raman and differential scanning calorimetry (DSC) tests.

A facile, reliable, and robust synthetic method to prepare high‐quality Pt3Fe nanocubes is reported. Results of investigation on these Pt3Fe nanocubes in shape‐/size‐distribution, crystallinity, structural characteristics, compositions, electrochemical activity towards small organic molecule oxidation as well as capability of assembling into simple cubic supercrystals are presented, and a possible formation mechanism of the cubic nanocrystals at high temperature in oleylamine/oleic acid solution is also proposed. This study indicates that the catalyst performance may be improved by controlling the shape of particles.

Epoxy resin nanocomposites reinforced with various loadings of core−shell structured nanoparticles (Fe@FeO) are prepared using a surface wetting method. Nanoparticle loading effect on the viscosity of epoxy monomers is well-correlated to Cross’ rheological model. Dynamic mechanical analysis (DMA) results reveal that the glass transition temperature is increased by 10 °C with the addition of nanoparticles, which is surprisingly independent of the particle loadings. The saturation magnetization (Ms) of the 20 wt % Fe@FeO/epoxy nanocomposites is 17.03 emu/g, which is about 15.8% of that of the pure nanoparticles. Meanwhile, the coercivity increases from 62.33 to 202.13 Oe after the nanoparticles are dispersed in the epoxy matrix. The electrical conductivity percolation is found to be around 5−10 wt %, where the resistance of the nanocomposites sharply decreases by 6 orders of magnitude. Thermal stability and tensile properties of the pristine epoxy and nanocomposites are also investigated in this work.

High-quality ∼16 nm c-In2O3nanoctahedra and ∼6 nm Pd spherical nanoparticles were synthesized viaa high-temperature wet-chemical approach, and their electrophoretic mobilities in toluene were investigated, respectively. Opposite electrical charge-induced 2D binary nanoparticle superlattice patterns containing two such nanocomponents were prepared, for the first time. Three types of c-In2O3-skeleton-structure-contained assembly patterns were identified as well. It was further observed that the vertices of c-In2O3nanoctahedra could have higher electrical charge density than that on edge or plane and the small Pd nanoparticles were “suspended” on the middle plane of the c-In2O3nanoctahedra, apparently well above the substrate surface (support film) rather than sitting on it. The assembly structure study indicates that Coulomb forces resulted from the opposite electrical charges are the dominative driving forces to induce the formation of such nanoctahedra-nanospheres 2D binary nanoparticle superlattices.

A catalyst-coated membrane (CCM) for a proton exchange membrane fuel cell (PEMFC) with Pt loading of 2.8 μg/cm2have been prepared by self-assembling charged Pt particles on a sulfonic acid function group, SO3-, on the membrane surface. Proton conductivity of the as-obtained CCM is 0.0932 S/cm. Half-cell polarisation showed that the self-assembled membrane is electrochemical active. Electrochemical characterisation of the self-assembled electrode showed that the Pt-PDDA nanoparticles were electrocatalytic active. The performance of self-assembled MEA with a Pt loading of 2.8 μg/cm2achieved 2.3 mW/cm2. This corresponds to Pt utilisation of 821 W per 1 g Pt. The results demonstrated the feasibility of the formation of monolayered Pt nanoparticle structure on the membrane interface. Such a monolayered structure could offer a powerful tool in fundamental studies of polymer electrolyte systems.

Carboxyl multi-walled carbon nanotubes (MWNTs-COOH) decorated with different palladium (Pd) nanoparticle loadings were synthesized by thermally decomposing different amounts of palladium acetylacetonate (Pd(acac)2) in a refluxing xylene solution with a fixed amount of dispersed MWNTs-COOH. The increased ratio of D band/G band and the decreased area ratio of oxygen containing groups (COOH, C–O and C=O) to C–C group suggested an increased occupation of defects on MWNTs. Transmission electron microscope (TEM) revealed different distributions of Pd NPs on the MWNTs with the variation of Pd(acac)2amount and the particle size increased with increasing the Pd loading. A relatively higher conversion of Pd(acac)2to Pd (76.21%) was achieved when the initial precursor ratio of Pd(acac)2to MWNTs was 2 : 1 (product denotes as Pd/MWNTs-(2:1)). The Pd/MWNTs-2:1 catalysts were demonstrated to exhibit the most efficient performance toward ethanol oxidation reaction (EOR) among all the precursor ratios, which is evaluated by the highest Pd mass-based peak current density (1.23 A/mg Pd) and stable current density (0.175 A/mg Pd) in cyclic voltammetry (CV) and chronoamperometry (CA). In addition, both reduced charge-transfer resistance and increased reaction kinetics with increasing the Pd loading were obtained from electrochemical impedance spectroscopy (EIS) and Tafel characterization.

This letter describes a facile high temperature microwave assisted process to form the magnetic core-shell carbon nanostructure from polyaniline (PANI)-magnetite (Fe3O4) nanocomposites. The amorphous combined with graphitized carbon shell is observed by the transmission electron microscopy (TEM). The crystalline metallic iron, cementite, Fe3O4and iron oxide (Fe2O3) are observed in the magnetic core in the Mössbauer spectrum measurements. The increased magnetic properties are observed in the formed core-shell carbon nanostructure after microwave annealing. The formed solid carbon nanostructure can protect the material from the acid dissolution and magnetic core favors the recycling of material.

Magnetic graphene nanoplatelet composites (MGNCs) decorated with core-shell Fe-Fe2O3nanoparticles (NPs) have been synthesized using a facile one-pot thermal decomposition method. The graphene nanoplatelets (GNPs) decorated with uniformly dispersed NPs are observed to exhibit a strong magnetization and can be magnetically separated from the liquid mixture by a permanent magnet. These MGNCs demonstrate an effective and efficient adsorption of arsenic(III) in the polluted water due to the increased adsorption sites in the presence of magnetic NPs. The adsorption behavior is well fitted with both Langmuir and Freundlich models, which show a significantly higher adsorption capacity (11.34 mg/g) than the other adsorption values reported on the conventional iron oxide based adsorbents (∼1 mg/g). The results show a nearly complete As(III) removal within 1 ppb.