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The TiO 2 nanofibers containing Au nanoparticles (NPs) were synthesized via one-step electrospinning of TiO 2 precursor, HAuCl 4 ·3H 2 O, and polyvinylpyrrolidone (PVP) in DMF solution followed by pyrolysis. The amount of Au NPs in the Au@TiO 2 nanofibers was varied by the concentration of HAuCl 4 ·3H 2 O in the electrospinning solution. The formation of the Au@TiO 2 nanofibers during the pyrolysis process was characterized by SEM, TEM, TGA, and UV/Vis. Dye-sensitized solar cells (DSSCs) based on composite photoanode of the Au@TiO 2 nanofibers and the TiO 2 nanoparticles were investigated. The results indicated that the efficiency of the DSSC would be enhanced by the optimal amount of Au NPs ( i.e. , 0.5 wt.%) in the Au@TiO 2 nanofibers. [ABSTRACT FROM AUTHOR]

Abstract: In this letter, we report a novel route to prepare stable Pd/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (Pd/PEDOT:PSS) colloid. With addition of PSS, the Pd/PEDOT:PSS aqueous dispersion was formed by simultaneous oxidation–reduction reaction between Pd(NO3)2 and ethylenedioxythiophene (EDOT) at room temperature. The morphologies of the Pd/PEDOT and Pd/PEDOT:PSS nanocomposites were characterized by transmission electron microscope. The Pd nanoparticles in the composites were identified with X-ray powder diffraction and UV/vis/NIR spectrum. The chemical structures of PEDOT were studied using FTIR spectra and UV/vis/NIR spectra. The results confirmed the formation of oxidized PEDOT polymer. The sensing property of the Pd/PEDOT:PSS thin film to the NH3 vapor was investigated. [Copyright &y& Elsevier]

Abstract: We report a study of the fluorescence properties of the conjugated polymer poly [2-methoxy-5-(2′-ethyl hexyloxy)-p-phenylene vinylene] (MEH-PPV) and polyethylene oxide (PEO) nanofibers. MEH-PPV/PEO nanofibers with different compositions have been fabricated by the electrospinning technique. The fluorescence spectra of the nanofibers show that the emission shoulder at ∼630nm blue-shifts ∼45nm, whereas the main emission peak around 590nm blue-shifts ∼15nm with decreasing concentration of MEH-PPV in the nanofiber. In addition, confocal microscopic studies of a single MEH-PPV/PEO electrospun nanofiber indicate that the fluorescence spectra of the nanofiber do not show any polarization dependence. The results are discussed in terms of the aggregation of MEH-PPV in an inert matrix. [Copyright &y& Elsevier]

• A multiscale model is built to analyze the suitable habitats for Siberian cranes. • The hydraulic model is combined with remote sensing to determine habitat features. • The impacts of the Poyang Lake Hydraulic Project on habitat suitability are revealed. • Water level regulation reduces the fragmentation degree of highly suitable habitats. • The spatial characteristics of habitats can guide habitat protection and management. Poyang Lake is located in the middle and lower reaches of the Yangtze River in China. It is the most important wintering area for the endangered Siberian cranes. Identifying the scale characteristics of habitat selection for Siberian cranes is essential for habitat conservation. In this study, a habitat suitability index (HSI) model based on multiscale habitat features was developed to assess the distribution and fragmentation degree of the suitable habitat for Siberian cranes before and after the construction of the proposed Poyang Lake Hydraulic Project (PLHP). The habitat of the entire lake area was divided into four ranks on the basis of HSI values. 2D shallow-water equations (SWEs), combined with remote sensing and geographic information system technology, were utilized to determine the key habitat features. Results indicated that the established HSI model could effectively recognize the potentially suitable habitats for Siberian cranes in Poyang Lake. The highly suitable habitat in the wet year was larger than that in the dry year, and the complexity of patch shapes and patch fragmentation increased. The influence of the PLHP on the suitable habitat for cranes mainly depended on its regulated water level, and this project could promote the formation and reduce the fragmentation degree of the suitable habitat under a properly regulated water level in the dry year. However, a higher regulated water level may cause a considerable negative impact on the distribution of suitable habitats in both years. This study provided a quantitative method to evaluate the potentially suitable habitats for Siberian cranes, and it could serve as a reference for the water level management of the proposed PLHP. [ABSTRACT FROM AUTHOR]

• A conceptual model is proposed to study the evolution of vegetation patches. • The relationship between final coverage and initial vegetation patches is revealed. • The longitudinal dispersion is usually enhanced during the vegetation evolution. • The effects of critical bed shear stress on the vegetated landscape is explored. Hydrodynamic conditions are important controlling factors in the evolution of vegetation and ecosystems, especially aquatic ecosystems. This study established a conceptual vegetation evolution model to explore the succession law of vegetation patches in the effective area of a channel, including the evolution of vegetation coverage (C e) and the corresponding longitudinal dispersion coefficient (K e). 2D shallow-water equations were implemented to calculate flow variables, and the equivalent Manning coefficient was used to reflect the effects caused by vegetation patches. New vegetation emerged in regions where the bed shear stress is lower than the critical bed shear stress, whereas the original vegetation was removed in regions where the bed shear stress is higher than the critical value. Two typical cross-sections and two initial C e were considered to better understand the succession trend of vegetation patches under different external conditions. The findings showed that C e and K e increased to a constant value with increasing simulation duration, whereas a higher critical bed shear stress, defined by the threshold value (TV), was linked to a higher final vegetation coverage (C f) and final longitudinal dispersion coefficient (K f). Furthermore, different initial vegetation distributions, including coverage and position, caused little effect on the C f in the rectangular channel, but the C f in the parabolic channel was linearly affected by the averaged bed shear stress at the initial patches. The maximum K f in both channels occurred with regularly distributed initial patches on one side of the bank. The vegetation patches in all scenarios evolved from block-shaped to strip-shaped and finally formed a stable vegetated landscape. This conceptual vegetation evolution model will improve our understanding of the influence of hydrodynamic conditions on the vegetation evolution in aquatic ecosystems. [ABSTRACT FROM AUTHOR]

• The three-scale perturbation model is built to study dispersivity in wetland flows. • Extended analytical solution for two-dimensional concentration distribution is given. • Effects of vegetation and bed absorption on environmental dispersion are discussed. Bed absorption and vegetation in natural wetlands exert considerable influence on contaminant transport. A three-scale perturbation method is extended in this work to present an exact analytical solution for the spatial concentration distributions affected by vegetation distribution and bed absorption. Compared with concentration moments-based analytical methods that were adopted previously to solve vertical concentration distribution in wetland flows, the multi-scale method used in this study is more concise without complicate integrated operations. The analytical solution is explicit and applicable without complicated integral form. Moreover, by comparing with the analytical solution obtained by the moments method, the analytical solution given in this work is accurate particularly after the initial stage. This study focuses on a large time scale in investigating spatial concentration distribution. Results show that concentration distribution is not uniform in the vertical direction. Hence, this study recommends the accurate two-dimensional spatial distribution rather than the cross-section averaged concentration distribution to achieve accurate concentration predictions. [ABSTRACT FROM AUTHOR]

Metasurface is extensively studied for generating multicharacteristic orbital angular momentum (OAM) beams. However, designing a highly integrated and independent polarization‐frequency multiplexing metasurface for efficient multiscenario OAM‐related applications is still a challenge. Here, a triple‐band single‐layer shared aperture reflective metasurface for triple‐polarization channels independent OAM modulations is proposed. The specific frequency quantitative customization resonance phase and quasi‐static geometric phase are utilized to manipulate the dual‐band (Ku‐ and K‐band) orthogonal linearly polarized (LP) channel and C&X‐band right‐handed circularly polarized (RHCP) channel. An isolation ring is introduced for eliminating the strong coupling between the structurally compatible RHCP and orthogonal‐LP subunits in a shared aperture meta‐atom. It is revealed that the isolation ring not only helps realize efficient multipolarization, multiband, and multimode OAM generation, but also expands the operation bandwidth of the RHCP channel OAM. A proof‐of‐concept prototype of the designed metasurface is constructed to verify the methodology and the experimental results are in excellent agreement with simulations. The proposed independent OAM modulation scheme for extending the functionality of metasurface offers a novel route to realize multipolarization and multiband OAM beams with high isolation, which may have potential applications in OAM‐based multichannel multiplexing communications. [ABSTRACT FROM AUTHOR]

This work reports a low-temperature seeding process for hydrothermal growth of ZnO nanorods on flexible polymeric materials. The process involved decomposition of zinc (II) amine complex below 100 °C to form ZnO seeds, followed by hydrothermal growth using zinc nitrate hexahydrate and hexamethylenetetramine under 90 °C. The method enabled the growth of ZnO nanorods on the polymeric film (e.g. PET) or the p-type conducting polymer poly(3,4-ethylene dioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) film. The UV response of the ZnO/PEDOT:PSS nanostructure was investigated. [ABSTRACT FROM AUTHOR]

• The spatial concentration distribution with FVI is illustrated. • The removal process of FVI is studied. • The effect of damping factor on contaminant transport is discussed. • The temporal contaminant residue mass is studied. The fate of the contaminant transport process within wetland flows considering contaminant depletion via a floating vegetation island (FVI) is the focus of this work. To identify the feature of contaminant cloud expansion under an FVI, multiscale theory is extended to obtain a two-dimensional spatial concentration distribution analytical solution. The characteristics of two-dimensional concentration distributions under upper FVI absorption and damping factor within wetland flows are illustrated. The performance of the contaminant depletion process via an FVI is also examined in this work, with discussions on removal efficiency, the absorption ratio, and the nonuniformity of contaminant mass. As FVI removal intensity changes along the stream direction, the analytical solution of removal efficiency is obtained to illustrate the longitudinal variation in the FVI removal intensity. Furthermore, the effects of removal intensity and damping factor on FVI removal efficiency are expressed separately. In addition, the removal intensity variance in the vertical direction is discussed using the defined absorption ratio. Moreover, as residual mass is a fatal issue in the contaminant removal process, temporal residual mass is discussed, and the residual mass proportion within different layers is depicted. Finally, the difference of the mass proportion between layers is employed to explain the transformation of the contaminant cloud. [ABSTRACT FROM AUTHOR]

The objective of this paper is designing a "greener" reinforced material of recycled PET (R-PET) fibers with high performance for cement. To balance the ductility and compression of fiber-reinforced cement composites (FRC), the reinforced fiber should be prepared with high mechanical property and FRC was designed based on micromechanics. First, the preparing processes of R-PET fibers are composed of melt-spinning of recycled PET and post-treatment (drawing, indentation and cutting). The effect of drawing ratio on the mechanical properties of R-PET fiber was studied by three phases model. The results showed that the R-PET fibers prepared has high mechanical properties (strength 736 ± 16 MPa; modulus 7.12 ± 1.6 GPa). Then, R-PET fibers were added in cement to prepare FRC and the results indicated that FRC tailed by micromechanics theoretical basis has high toughness and good compressive strength. Compared with plain cement, the result indicated that the compressive and bending strength of FRC with R-PET-3.1 at 16 kg/m3 content have increased by 41.0% and 113.5%, respectively. This melt spun R-PET fibers prepared by recycled PET bottle chips have the potential application in reinforcing and toughness of the cement mortar composites. [ABSTRACT FROM AUTHOR]

• A SSC distribution model is established in canopy flow based on gravitational theory. • A new formula is proposed to estimate Reynolds stress in vegetation layer. • Transition of SSC distribution types relates with the ratio of gravity to turbulence. Vegetation plays a significant role in river ecosystem, which has a great influence on hydraulic structures and sediment transport. Understanding the vertical distribution of suspended sediment concentration (SSC) in canopy flow is helpful to study the process of riverbed erosion and deposition in vegetated channels. Aiming at the sediment-laden flow in open channel covered with submerged vegetation, this study divides the water depth into two layers along the vertical direction with the vegetation height as the boundary and then proposes a new SSC distribution model based on gravitational theory to estimate the vertical distribution of relative SSC in the free water layer and vegetation layer respectively. In the meanwhile, a new formula is also proposed to evaluate the Reynolds shear stress below the submerged vegetation height, which has been successfully applied in the derivation of the new SSC distribution model. The validation results of the simplified velocity model, the new Reynolds shear stress formula and the new SSC model compare well with the collected experimental data series. On top of that, it is found that the uniformity of SSC distribution profile progressively decreases with the increasing sediment particles diameters. Besides, according to the validation results and discussion, it is believed that the controversy point about gravitational theory would not have obvious influence on the estimation of SSC distribution so that the gravitational theory can be adopted to investigate suspended sediment transport in vegetation flow. That would be benefit for river ecological restoration and better management. [ABSTRACT FROM AUTHOR]

• An analytical solution for describing environmental dispersion under surface wind and bed absorption boundary conditions is derived. • Numerical experiments are conducted and show that the solute concentration is strongly influenced due to bed absorption and surface wind. • The proposed analytical model agrees with the numerical experiment and another limited model in the literature. Both surface wind and bed absorption can greatly impact the pollutant dispersion processes, however, the two factors are not jointly considered in existing models due to the intricacy of analyzing the simultaneous influence of surface wind shear and bottom bed absorption. In this work, a multi-scale approach is employed to formulate the environmental dispersion process with both factors considered jointly within wetland flows. By adopting this method, the effect of wind and bed absorption on vertical concentration distribution and longitudinal concentration distribution are discussed. To visualize the results, the flow velocity contours under different wind conditions (i.e. upstream wind and downstream wind), the pollution concentration distributions versus time and spatial position, and the spatial contaminant cloud contours are presented. Moreover, numerical experiments of the interested scenarios are presented to verify the accuracy of the analytical method. The comparison shows that the results of the proposed multi-scale method agrees well with the dataset generated numerically. Finally, the multi-scale method in this work is compared to the Aris? concentration moment method in the literature by setting the bed absorption rate to zero. The comparison shows that the present model can reduce the substantial integration processes and derive accurate spatial concentration profiles. [ABSTRACT FROM AUTHOR]

The matrix of poly(fluorinated ethylene‐propylene) (FEP) was modified with graphene (GE) as filler, and then the composite fibers were prepared by melt spinning method with a twin‐screw extruder. The effects of both the draw ratio and GE content on the structures and properties of FEP/GE composite fibers were investigated. The results showed that the addition of nanoparticles reduced the crystallization of molecular chains and the orientation of crystalline units in the fibers, while the drafting and heat setting process could effectively improve the crystallinity and orientation of composite fibers. Moreover, the addition of GE improved the mechanical properties of the composite fibers and had no effect on the chemical resistance of the composite fibers. A significant enhancement of mechanical properties of the composite fibers was obtained at low GE content, that, a 35.5% improvement of tensile strength and a 19.5% increase of Young's modulus were achieved at a GE content of only 0.3 wt%. Compared with pure FEP fibers, the oil affinity of composite fibers was also significantly improved. The prepared FEP/GE composite fibers that showed excellent chemical resistance have potential application in oil‐water separation, especially in high temperature resistant fibrous materials. [ABSTRACT FROM AUTHOR]

Carbon nanofibrous nonwoven mats (CNFMs) prepared via electrospinning offer excellent electrical and structural properties and have been used as frameworks for electrodes in electrochemical energy storage devices. However, lack of mechanical strength hinders the broad applications of CNFMs in flexible electronics or industry use. In this work, a rapid stabilization method is developed to prepare high-strength and flexible CNFMs. Studies of the effects of stabilization time on the structures of the stabilized polyacrylonitrile (PAN) nanofibers and the subsequent carbon nanofibers reveal that there is an optimal stabilization time for making high-strength CNFMs. Long stabilization time results in excessive oxidation of the stabilized PAN nanofibers and unwanted defects in the carbon nanofibers. Short stabilization time results in carbon nanofibers with less crystalline structures due to insufficient formation of the thermally stable ladder-like structure. Robust and flexible CNFM with the highest tensile strength of 192.7 MPa is obtained using an optimized total stabilization time of 40 min. To demonstrate the application of the flexible CNFMs, they are fabricated as an electrode framework to load TiO2 nanoparticles without use of organic binders. Lithium ion half-cell based on this electrode demonstrates superior rate cycling performance owning to the porous structure and highly conductive fibrous carbon network of CNFM. [ABSTRACT FROM AUTHOR]

Sediment grain size in the deltaic environment of the Luanhe River (LR), Liaoning, China, contains sediment transport pathway information useful in elucidating the shoreline change and fluvial-marine interaction. In this study, we utilized numerical partitioning of the sedimentary components and geostatistical grain size trend analysis (GSTA) to define the sediment transport pattern in the Luanhe River delta (LRD) and interpolated the sediment transport pattern using content changes of end numbers (EM). EM1 (the mean grain size 7.12 Φ, fine silt), EM2 (2.37 Φ, fine sand), and EM3 (1.27 Φ, medium sand) components were identified by the numerical partitioning by GSTA. Kriging interpolation method was used to interpolate the parameters of the grain size for the regular grid, and the interpolation radius was 0.015 decimal degree. We chose 0.09 decimal degree as the characteristic distance for GSTA in the semi-variogram model using the geostatistical method. The FB(−) case (finer, better sorted and more negatively skewed) was adopted in GSTA for its satisfaction in the Global Moran's I test. The result of the GSTA shows that the sediments in the south barriers (SBs) were transported to the southwest of the study area. The sediments in the north, in the SE direction of sediment transport trend from the river mouth, indicated that the sediments in the north of the study area were transported from the LR to the northern beaches, and to the south and east of the study area. The sediment transport trend that simplified by GSTA as the FB(−) case was approved by the content changes of sedimentary components (i.e. EM1, EM2, and EM3). In addition, the turbulent jet diffusion pattern indicated that the coarse sediments (EM3) were delivered by LR during the flood season, and the EM2 and EM1 were from wave and tide, respectively. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Highly porous HNTs sponges were prepared via a facile while innovative approach. • Short electrospun nanofibers acted as skeleton while PVA acted as binding agent. • The HNTs sponges with nanofibers-to-HNTs ratio of 1:8 possessed the best properties. • (1:8) HNTs sponges showed high performances as dye adsorbent and catalyst support. • This work would expand the applications of 3D sponges made of electrospun nanofibers. Abstract Naturally existing Halloysite nanotubes (HNTs) are promising dye adsorbent and catalyst support; however, to directly use the HNTs powder encounters a practical problem related to separation and regeneration. In this work, highly porous HNTs sponges (with weight ratios of nanofibers-to-HNTs being 1:2, 1:4, 1:6, and 1:8) were prepared via a facile while innovative approach (i.e. , homogenizing the HNTs-PVA-nanofibers suspension, fast freezing, freeze drying, and thermal stabilization). In these sponges, short electrospun polyacrylonitrile and polyimide nanofibers acted as skeletons, supported HNTs, and provided mechanical elasticity and stability, while poly(vinyl alcohol) was utilized as binding agent. The HNTs sponges with nanofibers-to-HNTs weight ratio of 1:8 had low density (43.4 mg/cm3), high porosity (97.9%), large BET surface area (25.0 m2/g), excellent mechanical elasticity, good thermal stability, and high HNTs loading amount (88.9%), and they demonstrated high performances as novel dye adsorbent and catalyst support. This work would not only provide a novel approach for the preparation of HNTs sponges but also expand the applications of three-dimensional sponges/structures made of short electrospun nanofibers. [ABSTRACT FROM AUTHOR]

Abstract This paper reports the effects of hydrogen bonding on the starch granule dissolution, spinnability of the starch solution, and the properties of the electrospun starch fibers. Dissolution behaviors of the starch granules in dimethyl sulfoxide (DMSO) and water mixed solvents are characterized by confocal laser microscope, differential scanning calorimetry (DSC), and rheologic measurement. The starch granules are dissolved in the 100%DMSO or 6%H 2 O/94%DMSO solvent, resulting in good electrospinnability. On the other hand, the gelatinization behavior is observed for the starch granules in the 22%H 2 O/78%DMSO solvent, resulting in poor fiber formation during electrospinning. Infrared spectroscopy, DSC, x-ray diffraction, and mechanical property characterizations of the electrospun starch nanofibers suggest that the water content in the solvent plays an important role in the properties of the nanofibers. The dissolution behavior, electrospinnability, and the properties of the electrospun nanofibers are explained by the effects of the DMSO and H 2 O molecules on the ubiquitous hydrogen bonds in starch. Highlights • Ratio of dimethyl sulfoxide and water in the mixed solvent affects dissolution of starch. • High water content results in gelatinization and poor electrospinnability of the starch solution. • Aprotic dimethyl sulfoxide dissociates hydrogen bonds of starch, resulting in uniform nanofiber. • Water in solvent affects formation of hydrogen bonds and properties of the electrospun nanofibers. [ABSTRACT FROM AUTHOR]

A one-way water transport (also called OWT) cotton fabric is prepared by depositing a thin layer of hydrophobic polymer microspheres/nanospheres formed during one-step electrospray on one side of the hydrophilic cotton fabric. Rough surface resulted from the deposited microspheres/nanospheres mainly contributes to the hydrophobicity of electrosprayed layer and the layer thickness plays an important role in determining the water transport ability. OWT ability is observed in the cotton fabric with the electrosprayed layer thickness between 11 μm and 26 μm; when the layer is thinner than 11 μm or over 26 μm, the fabric shows a two-way or blocked water transport ability. This novel OWT fabric can be used in “smart” textiles for various applications. [ABSTRACT FROM AUTHOR]

Three-dimensional, cost-effective, and renewable/recyclable absorbent materials with high capacities on absorption of organic compounds are urgently in demand. Herein, a facile while innovative approach is reported to develop ultralight electrospun cellulose sponge (UECS). The prepared UECS exhibits super-high absorption capacity (up to 232 times of its own weight) towards absorption of organic compounds due to high porosity (99.57%), low density (6.45 mg/cm 3 ), and hydrophobic surface feature (with water contact angle of 141.2°). Furthermore, the UECS is mechanically robust thus can be readily cut into different shapes; and it also possesses excellent stability against various organic compounds. Intriguingly, upon absorption of an organic compound, the shape-stable UECS organic gel can be formed. Hence, the developed UECS would be promising as environmental friendly absorbent on high-performance separation of organic compounds from aqueous systems; while the UECS organic gel could be utilized for the applications such as drug delivery and sensor. [ABSTRACT FROM AUTHOR]

Aromatic polyimides (PIs) are high-performance polymers with rigid heterocyclic imide rings and aromatic benzene rings in their macromolecular backbones. Owing to excellent mechanical properties and thermal stability, as well as readily adjustable molecular structures, PIs have been widely adopted for many applications related to electronics, aerospace, automobile, and other industries. In recent years, PI fibers prepared by electrospinning of polyamic acid (PAA) precursor nanofibers followed by imidization (commonly known as electrospun PI nanofibers) have attracted growing interests. Herein, the preparation, evaluation, and application of electrospun PI nanofibers are reviewed. PI polymers and the electrospinning technique are introduced first followed by the preparation of electrospun nanofibers of homo-PI, co-PI, blend-PI, and PI composite. Subsequently, the mechanical and thermal properties of electrospun PI nanofibers are presented; in particular, the mechanical properties of individual electrospun PI nanofibers are highlighted. Thereafter, various applications of electrospun PI nanofibers are outlined, including reinforcement of composites, Li-ion battery separators, fuel cell proton exchange membranes, sensors, microelectronics, high-temperature filtration media, super-hydrophobic PI nanofibers, and PI-based carbon nanofibers. In the final section of conclusions and perspectives, future research endeavors and high-value applications of electrospun PI nanofibers are discussed. [ABSTRACT FROM AUTHOR]

• Keratin-based solution has good fiber-forming ability. • Post-functional strategy by glutaraldehyde (GTA) has two functions. • A novel keratin-based separator with high ionic conductivity and good stability. • Device with keratin-based separator exhibits outstanding electrochemical performance. Keratin is one of natural polymers with super wettability, which is an alternative sustainable polymer to fabric separators for high-performance supercapacitors (SCs). However, the extracted keratin has poor fiber-forming ability, and it remains challenging to prepare high performance keratin-based separators. In this study, to overcome the conflict between good mechanical strength and high ionic conductivity, keratin-based nanofiber membranes were prepared by electrospinning and glutaraldehyde (GTA) post-function strategy, which endow high mechanical strength (7.87 MPa) and high ionic conductivity (2.21 mS/cm) to keratin-based membranes (KMs-8). The FTIR and XRD approved that GTA treatment has two functions, i.e., cross-linking reaction and oxidation reaction, which endow the membranes with connected crosslinking sited structure and with hydrophilic groups in comparison with unfunctionalized membrane. As expected, the SCs with KMs-8 separator exhibit outstanding electrochemical performances with high specific capacitance (173.68F g−1) and good cyclic stability (98.1% at 8000 cycles). This research provides new insight into the design of keratin-based separator for SCs, which will broaden the application range of keratin and suggest a sustainable natural polymer for the utility for energy-related devices. [ABSTRACT FROM AUTHOR]

A flexible felt consisting of electrospun anatase TiO 2 and amorphous SiO 2 nanofibers together with anatase TiO 2 nanoparticles was explored as an innovative anode material for lithium ion battery. The electrochemical characterization of the half-cell of the composite felt ( vs. Li metal) showed that the felt had a high initial discharge capacity of 170 mAh/g and an excellent rate capability; furthermore, the capacity was retained at 84% of initial value after 100 cycles at fast charge/discharge rate of 1 A/g. The binder-free composite felt maintained superior flexibility/robustness and good electrochemical performance after 5,000 continuous bending cycles. [ABSTRACT FROM AUTHOR]

Abstract: A hybrid mat consisting of anatase-phase TiO2 nanofibers (~75wt.%) and structurally amorphous SiO2 nanofibers (~25wt.%) was prepared for the first time by electrospinning with dual spinnerets followed by pyrolysis in air at 500°C. Unlike many other TiO2 nanostructures, the TiO2/SiO2 hybrid mat was mechanically flexible; after being sensitized with N719 dye, the dye-sensitized mat was then assembled as a photo-detector for visible light. The fabricated photo-detector was also flexible; it exhibited excellent sensitivity and reproducibility/reversibility under varied light intensities, and it also showed high performance under the bending condition. Additionally, it is envisioned that the reported method could be a general approach for the preparation of flexible hybrid mats with different electrospun nanofibers of semiconducting metal oxides (e.g., TiO2 and ZnO) for various applications. [Copyright &y& Elsevier]

Abstract: Mechanically flexible mats consisting of electrospun carbon nanofibers (ECNFs) were prepared by first electrospinning aqueous mixtures containing a natural product of alkali lignin together with polyvinyl alcohol (PVA) into composite nanofiber mats followed by stabilization in air and carbonization in an inert environment. Morphological and structural properties, as well as specific surface area, total pore volume, average pore size, and pore size distribution, of the lignin-based ECNF mats were characterized; and their electrochemical performances (i.e., capacitive behaviors) were evaluated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. The lignin-based ECNF mats exhibited outstanding performance as free-standing and/or binder-free electrodes of supercapacitors. For example, the ECNFs made from the composite nanofibers with mass ratio of lignin/PVA being 70/30 (i.e., ECNFs (70/30)) had the average diameter of ∼100 nm and the Brunauer–Emmett–Teller (BET) specific surface area of ∼583 m2 g−1. The gravimetric capacitance of ECNFs (70/30) electrode in 6 M KOH aqueous electrolyte exhibited 64 F g−1 at current density of 400 mA g−1 and 50 F g−1 at 2000 mA g−1. The ECNFs (70/30) electrode also exhibited excellent cycling durability/stability, and the gravimetric capacitance merely reduced by ∼10% after 6000 cycles of charge/discharge. [Copyright &y& Elsevier]

Abstract: Two types of electrospun TiO2 nanotubes were prepared by the technique of co-axial electrospinning followed by pyrolysis of electrospun core–shell nanofibers at 500°C. The SEM/TEM images showed that both types of TiO2 nanotubes were polycrystalline with diameters of ~400–500nm and crystallite/grain sizes of ~10nm. The XRD results indicated that the TiO2 nanotubes possessed the anatase crystalline phase/structure. Upon sonication, both types of TiO2 nanotubes could be shortened; whereas the average lengths were different (i.e., shorter and longer TiO2 nanotubes). The dye-sensitized solar cell (DSSC) with photoanode based on the shorter TiO2 nanotubes had higher short-circuit current density and device efficiency while lower open-circuit voltage than the DSSC with photoanode based on the longer TiO2 nanotubes. The results are discussed in terms of dye loading amount and electron recombination lifetime. [Copyright &y& Elsevier]

Abstract: Electrospun anatase-phase TiO2 nanofibers with desired morphological structure and relatively high specific surface area are expected to outperform other nanostructures (e.g., powder and film) of TiO2 for various applications (particularly dye-sensitized solar cell and photo-catalysis). In this study, systematic investigations were carried out to prepare and characterize electrospun anatase-phase TiO2 nanofibers with different morphological structures (e.g., solid, hollow/tubular, and porous) and specific surface areas. The TiO2 nanofibers were generally prepared via electrospinning of precursor nanofibers followed by pyrolysis at 500°C. For making hollow/tubular TiO2 nanofibers, the technique of co-axial electrospinning was utilized; while for making porous TiO2 nanofibers, the etching treatment in NaOH aqueous solution was adopted. The results indicated that the hollow/tubular TiO2 nanofibers (with diameters of ∼300–500nm and wall-thickness in the range from tens of nanometers to ∼200nm) had the BET specific surface area of ∼27.3m2/g, which was approximately twice as that of the solid TiO2 nanofibers (∼15.2m2/g) with diameters of ∼200–300nm and lengths of at least tens of microns. Porous TiO2 nanofibers made from the precursor of Al2O3/TiO2 composite nanofibers had the BET specific surface area of ∼106.5m2/g, whereas porous TiO2 nanofibers made from the precursor of ZnO/TiO2 composite nanofibers had the highest BET specific surface area of ∼148.6m2/g. [Copyright &y& Elsevier]

Abstract: Carbon nanofibrous mat (nano-felt) surface-attached with Pd nanoparticles was prepared from electrospun polyacrylonitrile nano-felt surface-functionalized with amidoxime groups, and its application for hydrogen sensing was explored. The material consisted of relatively uniform and randomly overlaid carbon nanofibers with diameters of ~300nm, while the attached Pd nanoparticles had sizes in the range from a few to tens of nanometers. The electrospun carbon nano-felt was mechanically flexible/resilient, and the resistance of the material varied upon exposure to H2 at room temperature. The study suggested that electrospun carbon nano-felts surface-attached with metal nanoparticles could be a material of choice for the fabrication of gas- and/or bio-sensors, and the amidoxime-functionalization of electrospun polyacrylonitrile nano-felt could be a general approach for the development of various carbon nano-felts surface-attached with different metal nanoparticles. [Copyright &y& Elsevier]

Abstract: We report the effects of surface modification on the fluorescence properties of conjugated polymer/zinc oxide nanocomposites. Zinc oxide nanoparticle surface was partially capped by poly(vinylpyrolidone) (PVP) during hydrolysis of zinc acetate dihydrate in methanol in ambient condition. The ZnO-capped nanoparticles were characterized by XRD and TEM. The fluorescence properties of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV)/ZnO nanocomposites with different mass ratios were studied by steady-state and time-resolved spectroscopy. The results indicate that the surface-modified ZnO nanoparticles are more effective to quench the emission of MEH-PPV by charge transfer process than the non-capped ZnO. The more effective charge transfer in MEH-PPV/ZnO-capped is attributed to the better dispersion of the nanoparticles in MEH-PPV matrix and THF solvent. [Copyright &y& Elsevier]

Herein, we report the transient photocurrent and photovoltage studies on the charge transport in dye sensitized solar cells (DSSCs) made from the composites of electrospun titanium oxide (TiO2) nanofibers, and conventional TiO2 nanoparticles. The results on charge transport parameters (including the charge recombination lifetime, the electron transport lifetime, and the diffusion length) indicated that the addition of TiO2 nanofibers into composite photoanodes led to substantial improvement on the efficiency of charge collection, suggesting that the composites of nanoparticles and one-dimensional nanostructures are promising materials for the development of DSSCs with high efficiency. [ABSTRACT FROM AUTHOR]

This letter presents studies of several simple integrated circuits—n-channel metal-oxide semiconductor inverters, five-stage ring oscillators, and differential amplifiers—formed on thin, bendable plastic substrates with printed ribbons of ultrathin single-crystalline silicon as the semiconductor. The inverters exhibit gains as high as 2.5, the ring oscillators operate with oscillation frequencies between 8 and 9 MHz at low supply voltages (∼4 V), and the differential amplifiers show good performance and voltage gains of 1.3 for 500 mV input signals. The responses of these systems to bending-induced strains show that relatively moderate changes of individual transistors can be significant for the operation of circuits that incorporate many transistors. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) monolithic structures (i.e. , aerogels/sponges/scaffolds) assembled from fragmented electrospun nanofiber mats/membranes represent an emerging research topic in the electrospinning field. Owing to extremely high porosity, as well as excellent structural flexibility and stability, these 3D nanofibrous structures have attracted significant interests for various applications. In this review, the preparation of 3D monolithic structures are thoroughly discussed; and the properties of 3D structures and their various applications in the fields of environment (e.g. , organic compound removal, dye adsorption, and filtration and separation), energy (e.g. , supercapacitor), electronics (e.g. , pressure sensor), chemical engineering (e.g. , catalyst support, thermal insulator, and Joule heater), and biomedical engineering (e.g. , tissue engineering, hydrogel, and drug delivery) are summarized. Additionally, the future perspectives and challenges are also presented. It is envisioned that, this review will provide important guidance in designing novel 3D electrospun nanofibrous structures and exploring their potential applications. [ABSTRACT FROM AUTHOR]

In this study, we prepared wool keratin/PET composite nanofiber membrane to adsorb the Cr(VI) in acidic solution due to its strong adsorption ability. The adsorption ability of the composite membrane with different ratios of keratin to PET was investigated. The optimum adsorption ability can be obtained when the keratin concentration was 50% in the solution with a pH value of 3. With the higher content of keratin, the membrane possessed higher hydrophilicity, larger pore ratio, and larger extent amino protonation. The maximum adsorption ability of the composite membranes was 75.86 mg/g, while that of the pure PET nanofiber membrane was 27.27 mg/g. The FTIR and XPS analysis results demonstrated that both the disulfide bond of the keratin and the amino were involved in the adsorption process. The process was achieved by the electrostatic adsorption of the amino and the redox reaction of disulfide bond in cystine oxide. The removal property of the electrospun keratin/PET composite membrane was 75.86 mg/g. Unlabelled Image • PET composite nanofiber membrane with keratin extracted from wool was used for Cr(VI) adsorption. • The nanostructured fiber membrane with keratin promotes adsorption and reuse. • The adsorption mechanism has been proposed and explained the full reversibility in the adsorption process. [ABSTRACT FROM AUTHOR]