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High sensitivity of sensors is extremely significant for precisely monitoring imperceptible changes of motion in real-time, which cannot be achieved by traditional piezoelectric devices. Herein, a hierarchical polyvinylidene fluoride hexafluoropropylene (PVDF-HFP)/ZnO composite nanaofiber piezoelectric sensor with highly sensitivity has been prepared through epitaxial growing ZnO nanosheets on the surface of electrospun PVDF-HFP nanofibers. Systematic investigations have shown that their optimum pressure sensing performance with a sensitivity of 1.9 V kPa−1 and a short response time of 20 ms are achieved for forces from 0.02 to 0.5 N with excellent durability and stability up to 5000 cycles. Moreover, this sensor can precisely detect the imperceptible changes in player’s motions to avoid injury from overtraining. Additionally, a Bluetooth-low-energy that tracks player’s workout and transmits the output signals wirelessly to a smartphone app is utilized. The study provides a feasible approach for high-precision detecting and safety monitoring in the fields of medical, rehabilitation medicine, and workout security.

The effects of Gd3+ ion doping on the lattice structure and magnetism properties of polycrystalline SmFeO3 were investigated by X-ray diffraction (XRD) and magnetic characterization. Both the magnetic susceptibility and saturation magnetization were significantly enhanced due to the larger spin number of Gd3+. The low doping sample of Sm0.95Gd0.05FeO3 showed great enhancement of magnetic energy product, which may be attributed to the local exchange of different grains.

Fine particulate matter (PM) has seriously affected human life, such as affecting human health, climate, and ecological environment. Recently, many researchers use electrospinning to prepare nanofiber air filters for effective removal of fine particle matter. However, electrospinning of the polymer fibers onto the window screen uniformly is only achieved in the laboratory, and the realization of industrialization is still very challenging. Here, we report an electrospinning method using a rotating bead spinneret for large-scale electrospinning of thermoplastic polyurethane (TPU) onto conductive mesh with high productivity of 1000 m2/day. By changing the concentration of TPU in the polymer solution, PM2.5 removal efficiency of nanofiber-based air filter can be up to 99.654% with good optical transparency of 60%, and the contact angle and the ventilation rate of the nanofiber-based air filter is 128.5° and 3480 mm/s, respectively. After 10 times of filtration, the removal efficiency is only reduced by 1.6%. This transparent air filter based on TPU nanofibers has excellent filtration efficiency and ventilation rate, which can effectively ensure indoor air quality of the residential buildings.

Due to a variety of outstanding physical and chemical properties such as wide band gap, low resistance, good catalysis, high surface-to-volume ratio, high sensitivity and strong interaction with gas molecules, one-dimensional (1D) micro- and nanoscale indium oxide (In2O3) structures are capable for high-performance optical, electrical and chemical devices, which have attracted much attention in the last decade. In this paper, we first summarize various fabrication methods of 1D micro- and nanoscale In2O3 structures such as chemical vapor deposition, hydrothermal method, thermal evaporation method and electrospinning, then the interesting electrical and optical properties and their potential applications including gas sensors, field-emission transitions, photocatalysts and ultraviolet detectors are reviewed. At last, in order to fulfill the potential applications of 1D micro- and nanoscale In2O3 structures, some challenges have also been discussed.

Self-activated phosphors are capable of generating optical emissions from the internal ion groups of host lattice before externally introducing luminescent ions. However, numerous self-activated phosphors only show luminescence at low temperature due to the thermally activated energy migration among ion groups at room temperature, severely confining their application conditions. In this letter, we propose a strategy to converting the low-temperature luminescence to a room-temperature one through changing the synthesis conditions to induce structural distortions and thus to limit energy migration. Room-temperature self-activated luminescence of Ca2Nb2O7 was accordingly achieved in submicroplates synthesized using the sol–gel method. By further coupling the blue broadband emission from Ca2Nb2O7 submicroplates with the characteristic luminescence of Ln3+ (Pr3+, Sm3+, and Dy3+) dopants, multicolor emissions were successively tuned through adjusting the concentration of Ln3+. Our results are expected to expand the scope of designing room-temperature self-activated phosphors and tuning multicolor emission.

An ultraviolet (UV) sensor consisting of a zinc oxide (ZnO) nanofiber sensing membrane and a quartz crystal microbalance (QCM) was fabricated. ZnO nanofibers were prepared by electrospinning and calcination. The morphology and structure of the nanofiber sensing membrane were characterized by scanning electron microscopy and X-ray diffraction. The QCM sensor based on ZnO nanofibers was found to be sensitive to 254-nm UV light in nitrogen, oxygen and air atmospheres. When the QCM sensor was placed under UV irradiation, the resonant frequency difference rapidly decreased. When the light was removed, the frequency difference recovered until reaching 0 Hz. The stability and repeatability of the proposed ZnO nanofiber-based QCM sensor were demonstrated, and the sensing mechanism was briefly discussed.

Piezoelectric materials such as ZnO semiconductors and polyvinylidene fluoride (PVDF) have been extensively studied to produce flexible wearable devices, providing a viable method for energy collection. In this study, PVDF was mixed with ZnO nanoparticles to prepare PVDF/ZnO devices by electrospinning. The composite ZnO affects the diameter of electrospun fibers and the output performance of the devices. As ZnO was added, the diameter of the fibers decreases, but the output current of the devices increases. Moreover, compared with pristine PVDF, the bending output current and pyroelectric current of the devices were improved after mixed with ZnO. The results indicated that PVDF/ZnO composite was a promising flexible device that can provide power for small electronic devices.

The conventional high-voltage power supply (HVPS) used for electrospinning (e-spinning) is heavy and needs an extra electricity supply, which hinders the portability of the e-spinning apparatus. In this communication, we report on a new simple e-spinning setup using a piezoelectric ceramic (PZT) generator to replace HVPS, which makes the setup very simple, and may be the simplest e-spinning apparatus (small volume 5 × 1 × 1 cm3 and light weight < 10 g). The pulsed voltage generated by a PZT element is about 56 kV, which can meet the requirement for e-spinning. Three kinds of polymer solutions such as polyvinylpyrrolidone (PVP), poly(vinylidene fluoride) (PVDF) and polystyrene (PS) have been electrospun into ultrathin fibers successfully, which confirms the feasibility of this apparatus. The influences of different parameters such as e-spinning distance (1–9 cm) and solution concentration (11–14 wt%) were investigated. This work demonstrates a new approach to design a portable and simple e-spinning apparatus.

Pure n-type ZnO nanofibers and p-type Ce-doped ZnO nanofibers were prepared by electrospinning followed by calcination. Their surface morphology, elemental composition, crystal structure, and optical and electronic properties were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and photoluminescence and UV-visible spectroscopy techniques and by their current–voltage (I–V) curves. The energy-dispersive X-ray spectroscopy and X-ray diffraction spectra showed that Ce was successfully incorporated into the ZnO crystal lattice and that the atomic percentage of Ce to Zn was 1.46%. The photoluminescence integrated intensity ratio of the UV emission to the deep-level green emission for Ce-doped ZnO nanofibers was over twice than that of pure ZnO. The UV-visible absorption edge of the Ce-doped ZnO nanofibers red-shifted by 2.6 nm compared with the pure ZnO nanofibers. The ZnO nanofibers had a good response to ultraviolet radiation. The sensitivity (Imax/I0) of the Ce-doped ZnO nanofibers was 102, which was one order higher in magnitude than that of pure ZnO nanofibers. The field-effect curve suggested that the synthesized Ce-doped ZnO nanofibers were p-type semiconductors. A p–n homojunction device was prepared using the ZnO nanofibers and showed good rectifying behavior. The turn-on voltage reduced by about 10 V under UV irradiation. Both the ZnO nanofibers and the ZnO p–n homojunction had excellent UV sensibilities. These results suggest that Ce-doped ZnO nanofibers may have widespread applications in optical and electronic devices.

Color manipulation of intense multiluminescence from CaZnOS:Mn2+ has been realized by adjusting Mn2+ concentration. Not only the photoluminescence (PL) of Mn2+ emission from 4T1(4G) to 6A1(6S) shows a red shift from yellow to red with increasing Mn2+ concentration, which is in contrast to the fixed PL emission reported by Hintzen et al. (Chem. Mater., 2009), but also mechanoluminescence (ML) and cathodoluminescence (CL) have a similar variation. More attractively, the brightness of multiluminescence is surprisingly intense for all the CaZnOS:Mn2+ with a large-scale Mn2+ doping (0.1–10 mol %). Based on the investigation of crystal field, various spectral results, and PL lifetimes, the red-shift mechanism of multiluminescence reported here has been proposed to arise from the exchange interaction effect of Mn2+ pairs at higher concentrations. In addition to correcting the previous misunderstanding on the emission of CaZnOS:Mn2+, these findings extend the tunable emission window, opening up new opportunities ...

La-doped ZnO nanofibers were fabricated via electrospinning and calcination at 800°C. The surface morphology and crystal structure of the La-doped ZnO nanofibers were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The photoelectric properties of La-doped ZnO nanofibers were also investigated. It was found that the photoelectric current increased obviously under light illumination (308 nm and 365 nm). However, the photocurrent reduced with increasing La-doping level, which may be ascribed to the increased defects inducing by La-doping.

A metal-semiconductor-metal photoconductive detector was fabricated using Ce-doped ZnO nanofibers synthesized by electrospinning and calcinations. UV photocurrents were carried out to study optoelectronic properties of Ce-doped ZnO nanofibers. The current-voltage (I–V) characteristics of photodetector device were analyzed under different wavelength UV illumination. The photocurrent increased by about 300 times under UV illumination. Results showed that the photocurrent of the device increased with the decrease of the wavelengths. A maximum photocurrent and photo-responsivity was observed at 365 nm, 308 nm, 254nm, respectively, under 30 V bias. The response and recovery time of the nanofibers was 16 s and 16 s at 365 nm, 10 s and 12 s at 308nm, 4 s and3 s at 254nm under 30 V bias, respectively.

Electrospinning (e-spinning) still has certain limitations in flexible practicability because its conventional setup is usually quite bulky and excessively dependent on a plug (electric supply). In this article, we report on a battery-operated e-spinning apparatus (BOEA) based on miniaturization and integration. The new device gets liberated from the conventional heavy power supply, achieves the tight integration of functional parts and can be operated by a single hand due to its small volume (10.5 × 5 × 3 cm(3)) and light weight (about 120 g). Different polymers such as polyvinylpyrrolidone (PVP), polycaprolactone (PCL), polystyrene (PS), poly(lactic acid) (PLA) and poly(vinylidene fluoride) (PVDF) were electrospun into fibers successfully, which confirms the stable performance and good real-time control capability of the apparatus. These results demonstrate that the BOEA could be potentially applied in many fields, especially in biomedical fields such as skin damage, wound healing, rapid hemostasis, etc.

A conventional electrospinning setup cannot work without a plug (electricity supply). In this article, we report a self-powered electrospinning setup based on a hand-operated Wimshurst generator. The new device has better applicability and portability than a typical conventional electrospinning setup because it is lightweight and can work without an external power supply. Experimental parameters of the apparatus such as the minimum number of handle turns to generate enough energy to spin, rotation speed of the handle and electrospinning distance were investigated. Different polymers such as polystyrene (PS), poly(vinylidene fluoride) (PVDF), polycaprolactone (PCL) and polylactic acid (PLA) were electrospun into ultrathin fibers successfully by this apparatus. The stability, reliability, and repeatability of the new apparatus demonstrate that it can be used as not only a demonstrator for an electrospinning process, but also a beneficial complement to conventional electrospinning especially where or when without a power supply, and may be used in wound healing and rapid hemostasis, etc.

Aligned poly(methyl methacrylate) (PMMA) fibers were fabricated by electrospinning and then nanostructured polyaniline (PANI) was grown on the surface of the parallel PMMA fibers via in situ solution polymerization. The structure and morphology of the aligned PANI/PMMA composite fibers were characterized by scanning electron microscopy (SEM) and Raman spectrometry. The gas sensing properties of the composite fibers were investigated under ultra-low ammonia concentrations at room temperature. It is found that the arranged fibers exhibited high sensitivity and fast response upon exposure to ammonia vapor of 1–30 ppm. The normalized resistance R/R0 increased linearly with the ammonia concentration increasing. The sensing mechanism was also discussed. The results indicate that aligned PANI/PMMA composite fibers are promising candidate for fast detection of toxic ammonia gas.

Titanium dioxide (TiO2) nanorods with anatase phase were successfully fabricated by electrospinning and followed calcination. The TiO2 nanorods were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and UV-visible spectroscopy. The diameter of the TiO2 nanorods was about 60–150 nm and the length was 200 nm–2 μm. Electrical properties under bending were investigated by fixing the device to a curved surface with different curvatures, and the device showed a fast and stable resistance response to curvature changing. Photoelectric properties were studied by irradiation with different light intensities. The device exhibited a short response time (∼10 s) and a high sensitivity (∼103) which increased with the light intensity increasing. These results indicate that electrospun anatase TiO2 nanorods have potential applications in flexible photodetectors and solar cells.

For large scale electrospun (e-spun) nanofibre production, a variety of electrospinning (e-spinning) techniques such as multi-needle e-spinning and needleless e-spinning have been developed recently. In this paper, we propose a new design of efficient needleless e-spinning for fabrication of polymer nanofibres. A circular rotary bead wire driven by a DC motor is used as needleless electrode. When e-spinning, numerous solution jets are generated from the bead wire electrode through wrapping the electrode with solution from the solution brush. The design, construction and testing of the novel needleless e-spinning from rotary bead wire electrode are described in detail. The average diameter of the resultant polyvinyl pyrrolidone (PVP) fibres produced under 15–30 kV is around 200 nm. This needleless e-spinning technique may be promising for mass production of nanofibres.

Ultrathin indium oxide (In2O3) microtubes were successfully fabricated by electrospinning, magnetron sputtering and followed calcination. The hollow In2O3tubes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-visible spectroscopy. Outer diameter of the microtubes was in the range of 700-900 nm, and inner diameter was about 400-600 nm. Optoelectronic properties of the In2O3tubes were investigated by irradiation of UV light with different wavelengths (254, 308 and 365 nm). It was found that the In2O3microtubes had a fast and strong response to UV irradiation.

Background Only four cases of primary intracerebellar paragangliomas have been reported in the literature to date. Because of its rarity, primary intracerebellar paraganglioma still presents a diagnostic challenge for both radiologists and neurosurgeons, and the optimal therapeutic modality is still debatable for its hypervascularity and location. Patients We report a 16-year-old boy with pathology-proven primary intracerebellar paraganglioma who presented with dull headache, dizziness, and gait disturbance, and underwent gross total resection. Further, we review all reported cases of primary intracerebellar paraganglioma in the English literature and discuss its clinical profile, neuroradiological features, and treatment modalities. Results His symptoms improved following tumor removal without radiotherapy, and postoperative neuroimaging thirteenth months after surgery showed no recurrence. In the literature, all four patients were stable in the follow-up period including three with complete resection and one with partial resection plus adjuvant radiotherapy. Conclusion Surgical resection is the treatment modality most often used for primary intracerebellar paraganglioma; radiation therapy may be used when there is residual tumor or recurrence. Angiography may help to clarify the vessel architecture for reducing intraoperative bleeding when primary intracerebellar paraganglioma is considered.

Besides the conductive patterning substrate, spatially well-defined microfibrous architectures can also be electrospun by using an insulating topographically structured collector (e.g.a nylon fabric). In both cases, it is proposed that the formation of the electrospun microfibrous patterns can be ascribed to the re-distribution of static electric field whenever collectors with different topography are introduced. Moreover, a series of simulation of the static electric field for various collectors (e.g.flat Al foil, conductive and insulating patterned substrates) have been systematically made to illustrate the formation mechanism, respectively. Our results are considered to warrant further scientific understanding on the formation of electrospun microfibrous patterning constructs, and helpful for easy generation of spatially defined architectures which have applications in a variety of areas such as tissue engineering, cell adhesion, proliferation and migration,etc.

Comb-like ZnO nanostructures are prepared by chemical vapor deposition in a quartz vial and characterized by a scanning electron microscope. The comb-like ZnO structures are several tens of micrometers. The lengths of the branches (nanowires) gradually decrease along the growth direction of the comb-like ZnO structures. The branches have uniform diameters and are evenly distributed on the belt-stem. Electrical measurements indicate that the comb-like ZnO is intrinsic n-type semiconductor. Moreover, the nanostructures have good sensing properties. It is found that an individual ZnO comb exhibits fast and large response to ppm-level CO gas even at room temperature. The sensing mechanism is also discussed briefly. These results demonstrate that comb-like ZnO nanostructures have potential application in gas sensors without an external heater.

Mixed-valence Eu-doped CaZr(PO4)2 was prepared in air atmosphere by a two-step solid-state reaction for the first time. The reduction of Eu3+ to Eu2+ in air atmosphere was observed in the second synthesis step via the use of NH4H2PO4 and the first-step product CaZrO3:Eu3+ to synthesize CaZr(PO4)2:Eu, which strengthens the evidence linking the tetrahedral anion groups PO4 with the Eu reduction. This reduction mechanism is explained by a charge compensation model. The luminescence measurements indicate that the obtained phosphors exhibit a broad bluish-green fluorescence of Eu2+ and a sharp orange-red emission of Eu3+ on 200–350 nm ultraviolet (UV) excitations. A tunable white luminescence covering the whole visible spectrum is realized based on the gradual reduction of Eu3+ to Eu2+ with increasing the sintering time. The optimal white luminescence excited at 247 nm presents the CIE color coordinates of (0.322, 0.305), a correlated color temperature of 6243 K, and a good thermal stability. Furthermore, energy transfer from Eu2+ to Eu3+ is found in CaZr(PO4)2:Eu. Our investigation of CaZr(PO4)2:Eu may provide a practical basis to design and fabricate novel phosphors for white light-emitting diodes (W-LEDs).

Due to a variety of outstanding properties, such as large surface area, high length-to-diameter ratio, flexible surface functionality, tunable surface morphologies and superior mechanical performance, electrospun ultrathin fibers are suitable for flexible and stretchable devices, which have aroused much attention nowadays. In this review, we aim to summarize recent developments in the fabrication of flexible/stretchable electronic devices via electrospinning, including strain and pressure sensors, supercapacitors, organic field-effect transistors, and transparent electrodes, which are the key components of flexible/stretchable devices. Moreover, in order to further improve the performance of these devices, some challenges facing electrospun fibers (e.g. production on large scale, precise deposition and flexibility improvement of electrospun inorganic fibers) and subsequent integration for flexible/stretchable electronic devices have also been discussed.

Self-activated phosphors are capable of generating optical emissions from the internal ion groups of host lattice before externally introducing luminescent ions. However, numerous self-activated phosphors only show luminescence at low temperature due to the thermally activated energy migration among ion groups at room temperature, severely confining their application conditions. In this letter, we propose a strategy to converting the low-temperature luminescence to a room-temperature one through changing the synthesis conditions to induce structural distortions and thus to limit energy migration. Room-temperature self-activated luminescence of Ca

Soft conductive elastomer materials have wide potential applications in material science and electronic engineering. Through electrospinning and in-situ polymerization, a kind of well-organized coaxial polyaniline/polyvinylidence fluoride (PANI/PVDF) microfibers with conductivity about 0.6 S/cm were fabricated, which combined the advantages of conducting polymer and elastic material. It is found that the resistance of the fibers was changed with the curvature variation. The results indicate that the PANI/PVDF microfibers could be used as strain sensor with high flexibility, high sensitivity, and stable repeatability.

The localised corrosion due to the galvanic couples between the precipitated particles and matrix in a new aluminium alloy 2519A was investigated by scanning electronic microscopy, transmission electronic microscopy and scanning Kelvin probe force microscopy. Topography and Volta potential differences relative to the matrix in 3·5%NaCl solution were examined for two kinds of Al2Cu and Al7Cu2Fe particles. Almost the particles showed positive Volta potential difference relative to the matrix. A series of particles nobility was detected with Al7Cu2Fe being less noble than Al2Cu. The potential difference of Al2Cu particles from the matrix was 702 mV in average, while Al7Cu2Fe particles 526 mV. Both of the particles act as cathode and localised corrosion originated mainly from the periphery of coarse ones. The more obvious the particles, the more severe the corrosion pits are.

A modified electrospinning setup with two-grounded-frame collector is proposed to fabricate aligned fiber arrays and fiber ropes. In this setup, two frames are placed under the spinneret, with the outer frame rotated with an electromotor and the inner frame hold still in a horizontal direction. Aligned nanofiber arrays can be collected rapidly on the inner frame. Influence of included angle and motor rotating speed on the arrays is discussed. In addition, through rotating one side of the inner frame, twisted fiber ropes with diameter 30~40 μm and length of 12 cm are obtained. Mechanical properties of the individual nanofiber ropes are also measured and discussed.

Nanocrystalline and porous barium titanate (BaTiO3) nanofibers with diameter 200-400 nm were synthesized via electrospinning and followed calcinations. The morphology and microstructure of the nanofibers were characterized using field emission scanning electron microscope, X-ray diffractometer and transmission electron microscope, respectively. And the electrical and humidity sensing properties of the nanofibers were also measured. The results reveal that the BaTiO3 nanofibers have a conductivity of about 0.3 S/cm, and show an ultrafast response time (~0.7 s) and a recovery time (~0.4 s) to humidity at room temperature. In addition, the sensing mechanism was also discussed briefly based on its nanocrystalline and porous microstructure of the electrospun material.

Isolated schwannoma arising from the oculomotor nerve occurs rarely, and only 12 children with oculomotor nerve schwannoma without neurofibromatosis have been sufficiently documented. This article presents a 3-year-old boy in which a large isolated parasellar oculomotor nerve schwannoma causing parent nerve dysfunction. Complete resection of the tumor was achieved via a right pterion approach, but he developed complete palsy of the third nerve postoperatively, which had an incomplete recovery in 12-month follow-up. We review the pertinent literature about pediatric oculomotor nerve schwannoma and discuss its clinical features and management.

Residual stresses in ultrathin La0.9Sr0.1MnO3 (LSMO) films with various thicknesses of 8-40 nm were measured quantitatively via synchrotron radiation X-ray diffraction. By fitting the strain versus sin(2)psi plots the residual stresses in the nanofilms were obtained. With increasing film thickness, both the in- and out-of-plane stresses decreased for strain relaxation. The strains of LSMO nanofilms on miscut SrTiO3 (STO) substrates were weaker than those on exact-cut ones with same thickness, which indicates that the crystallization in nanofilms on miscut SrTiO3 was more perfect than that on exact-cut SrTiO3. The mechanism is discussed briefly based on the minimization of surface energy and strain energy. (C) 2012 Elsevier B.V. All rights reserved.

Uniaxially aligned and cross-aligned arrays of ultrafine polymer fibers have been fabricated by a novel and effective centrifugal electrospinning setup with rotating polymer solution jets. Comparing with conventional electrospinning (10–30 kV) and centrifugal spinning (4,000–12,000 rpm), this technique only requires a lower working voltage (2.8–6.0 kV), a slower rotational speed (360–540 rpm), and a shorter spinning distance (2.0–4.0 cm). In addition, the influences of experimental parameters such as working voltage, rotational speed, collecting distance, and solution concentration on the alignment of the as-spun fibers are investigated using image analysis techniques. It is found that the working voltage and rotational speed mainly influence the perpendicular and linear velocities of the fibers, respectively. The polymer fibers tend to show higher alignment degree when these two velocities are very close. Optimum conditions (working voltage 3.0 kV, rotational speed 420 rpm, collecting distance 2.5 cm, and solution concentration 18 wt%) to maximize alignment degree (~97%) of polystyrene fibers are also obtained.

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/polyvinylpyrrolidone (PEDOT:PSS/PVP) composite nanofibers were successfully fabricated via electrospinning and used as a quartz crystal microbalance (QCM) sensor for detecting CO gas. The electrical property of individual PEDOT:PSS/PVP nanofibers was characterized and the room temperature resistivity was at the magnitude of 105 Ω·m. The QCM sensor based on PEDOT:PSS/PVP nanofibers was sensitive to low concentration (5–50 ppm) CO. In the range of 5–50 ppm CO, the relationship between the response of PEDOT:PSS nanofibers and the CO concentration was linear. Nevertheless, when the concentration exceeded 50 ppm, the adsorption of the nanofiber membrane for CO gas reached saturation and the resonant frequency range had no change. Therefore, the results open an approach to create electrospun PEDOT:PSS/PVP for gas sensing applications.

Color manipulation of intense multiluminescence from CaZnOS:Mn2+ has been realized by adjusting Mn2+ concentration. Not only the photoluminescence (PL) of Mn2+ emission from 4T1(4G) to 6A1(6S) shows a red shift from yellow to red with increasing Mn2+ concentration, which is in contrast to the fixed PL emission reported by Hintzen et al. (Chem. Mater., 2009), but also mechanoluminescence (ML) and cathodoluminescence (CL) have a similar variation. More attractively, the brightness of multiluminescence is surprisingly intense for all the CaZnOS:Mn2+ with a large-scale Mn2+ doping (0.1–10 mol %). Based on the investigation of crystal field, various spectral results, and PL lifetimes, the red-shift mechanism of multiluminescence reported here has been proposed to arise from the exchange interaction effect of Mn2+ pairs at higher concentrations. In addition to correcting the previous misunderstanding on the emission of CaZnOS:Mn2+, these findings extend the tunable emission window, opening up new opportunities ...

Conducting polyaniline (PANI) was in situ polymerized at the surface of electrospun poly(methyl methacrylate) (PMMA) fibers to obtain flexible composite fibers. The electrical conductivity of an individual PANI/PMMA composite fiber was estimated to be 2.0 × 10−1 S cm−1at room temperature. The ammonia sensing properties of the samples were tested by impedance analysis. The PANI/PMMA fibers could obviously respond to low concentration of ammonia at ppb level and could respond to relatively high concentration of ammonia at 10 ppm level quickly. In addition, the sensitivity exhibited a good linear relationship to the ammonia concentration. Particularly, the flexible PANI/PMMA fibers showed a reversible change in electrical resistance with repeated cycles of bending and relaxing, and the electrical resistance decreased with the increase of curvature. These results indicate that the flexible PANI/PMMA composite fibers may be used in toxic ammonia gas detection, strain sensing, and flexible electronic devices.

Electrospinning is a simple and practical method for fabricating uniform fibers with diameters range from several micrometers down to a few nanometers. In order to achieve highly ordered arrays of nanofibers, a novel and feasible approach, named contact-transfer printing of electrospun fibers, is reported in this paper. Via this method, large-scale aligned nanofibers on various rigid or flexible substrates can be assembled. This technique is demonstrated to be efficient on transferring of electrospun nanofibers with a high degree of alignment (~88.2%) on a SiO2 substrate. In addition, it is found that the printing outcome highly depends on the pressure between collecting and receiving substrate.

Polyaniline (PANI) is a promising functional polymer in the field of toxic gas detection. In this paper, nano-branched coaxial PANI fibers were grown on electrospun poly(methyl methacrylate) (PMMA) nanofibers by an in situ chemical oxidative polymerization method. The resultant PANI/PMMA fibers were characterized by scanning electronic microscopy and Raman spectrum analysis. The conductivity of an individual coaxial PANI/PMMA fiber is about 2.123 S/cm and that of the conducting PANI coating layer is about 21.8 S/cm. The ammonia sensing properties of the samples were tested by means of impedance analysis. The nano-branched PANI fibers can response significantly to low concentration of ammonia due to large specific surface area, and the sensitivity shows good linear relationship to the ammonia concentration of ppm level. These results indicate that nano-branched coaxial PANI fibers are promising candidate for detection of toxic ammonia gas.

LiMn2O4 nanofibers were prepared via electrospinning and followed by calcination. The surface morphology of as-spun and pure LiMn2O4 nanofibers was characterized by a scanning electron microscope (SEM) with an average diameter of 180 nm. After calcination at 800 °C in air for 5 h, charge/discharge capacity of pure LiMn2O4 nanofibers was measured in the potential range of 3.0 to 4.3 V. Battery testing showed that LiMn2O4 have a high discharge capacity of 80 mAh/g and 85% of the initial charge capacity was maintained for 5 cycles.

In this paper, non-woven micro-/nanofibers and wavelike micro-ribbons were produced by a low-voltage near-field electrospinning with working voltage less than 2.8 kV and spinning distance less than 8 mm. A series of experiments were carried out to explore the influence of processing variables on the formation of near-field electrospun nanofibers (polyvinyl pyrrolidone (PVP) as an example), including concentration, humidity and spinning distance. The formation mechanism of helical fibers and wavelike micro-ribbons was also discussed, which can be ascribed to electrical driven bending instability and/or mechanical jet buckling when hitting the collector surface. The results indicate that the morphology of the electrospun fibers can be controlled by experimental variables. And the low-voltage near-field electrospinning is a promising technique which may be used in precision deposition of nanofibers for nanodevices, direct-write nanofabrication, etc.

Electrospinning (e-spinning) is a versatile technique to fabricate ultrathin fibers from a rich variety of functional materials. In this paper, a modified e-spinning setup with two-frame collector is proposed for the fabrication of highly aligned arrays of polystyrene (PS) and polyvinylidene fluoride (PVDF) nanofibers, as well as PVDF/carbon nanotube (PVDF/CNT) composite fibers. Especially, it is capable of producing fibrous arrays with excellent orientation over a large area (more than 14 cm × 12 cm). The as-spun fibers are suspended and can be easily transferred to other rigid or flexible substrates. Based on the aligned fibrous arrays, twisted long ropes are also prepared. Compared with the aligned arrays, twisted PVDF/CNT fiber ropes show enhanced mechanical and electrical properties and have potential application in microscale strain sensors.

The side effects or toxicity of cyanoacrylate used in vivo have been argued since its first application in wound closure. We propose an airflow-assisted in situ precision electrospinning apparatus as an applicator and make a detailed comparison with traditional spraying via in vitro and in vivo experiments. This novel method can not only improve operational performance and safety by precisely depositing cyanoacrylate fibers onto a wound, but significantly reduce the dosage of cyanoacrylate by almost 80%. A white blood cell count, liver function test and histological analysis prove that the in situ precision electrospinning applicator produces a better postoperative outcome, e.g., minor hepatocyte injury, moderate inflammation and the significant ability for liver regeneration. This in situ precision electrospinning method may thus dramatically broaden both civilian and military applications of cyanoacrylates.

Barium titanate (BTO, BaTiO3) nanofiber was prepared via electrospinning and followed annealing process. The as-spun and calcined BTO nanofibers were characterized by a scanning electron microscope (SEM). After annealing at 800 °C in air for 3 h, polycrystalline BTO nanofibers with 120-200 nm in diameter were successfully obtained. I-V characteristic curves of single BTO nanofiber were measured. The p-type semiconducting fiber shows a room-temperature conductivity of about 0.3 S/cm. In addition, the small humidity hysteresis demonstrates the application prospects of electrospun BTO nanofibers in the fabrication of a high-sensitive humidity sensor.

The Fe 78 Si 9 B 13 glassy ribbons were compressed at room temperature with different pressures. The thermal and corrosion behaviors were investigated using various experimental techniques. The X-ray diffraction (XRD) and dilatometer (DIL) results show that the Fe 78 Si 9 B 13 ribbons are in full amorphous state after pressing and the amount of free volume increases monotonically with increasing pressure. The corrosion resistance of the glassy alloys in various solutions decreases after compression at 10 MPa, but increases after compression at 20 MPa. The non-monotonic change of corrosion resistance is consistent with the result of electrical resistivity, which can be explained by the combining action of free volume that is introduced by the compression and the segregation of Si atoms in the samples.