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Abstract Different colored fibers were blended into yarns by digital rotor spinning to meet the market demand of multi-species and small-batch production. In order to study the color blending effect of spun yarn, two-component and three-component blended yarns were obtained by red, yellow and blue slivers, and woven as fabrics. Parameters of K-M double constant theoretical model were calculated by the color characteristics of fabrics. The absorption coefficient (K) and the scattering coefficient (S) of the monochromatic fiber were calculated by the method of least squares and the method of relative value, respectively. According to the above methods, two Kubelka-Munk double constant color blending models were built. The two models were used to predict colors and blending ratios of fabrics. The results show that the K-M model established by the least squares method can better predict color blending effect and the blending ratio of digital rotor spun yarn. Highlights • A smart and sustainable spinning for colorful textiles was introduced. • K-M model of digital rotor spun yarn were built by the relative value method and the least squares method respectively. • The blended fabric color and blending ratio were calculated and predicted. • Compared with relative value method, K-M model built by least squares method can better predict the color blending effect. [ABSTRACT FROM AUTHOR]

Abstract Activated microporous polyacrylonitrile-based carbon nanofibers (APCFs) were synthesized by a sequential process of electrospinning, carbonization, and KOH activation. The porosity and surface chemistry of the APCFs strongly depended on the activation temperature. The specific surface area and pore volume varied from 15 to 1886 m2 g−1 and 0.021–1.196 cm3 g−1, respectively, as the activation temperature increased; this was accompanied by morphology changes at high temperature. The dominant microstructure and minor mesostructure improved the capacitance of carbon. Compared to the other samples, APCFs activated at an optimum temperature of 1000 °C showed the highest specific capacitance of 103.01 F g−1 at 1 A g−1 in 1 mol L−1 Na 2 SO 4 aqueous electrolyte, and an excellent cycling durability up to 3000 cycles. The improved electrochemical efficiency could be explained by the high specific surface area, suitable pore size, and influence of heteroatoms relative to the increased electrical double-layers. The change in the pore size distribution with activation temperature is also discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract Flange wrinkling is one of the common defects that occur in conventional spinning process, severely restricting the improvement of forming quality and formability. How to universally determine the formability dependent on flange wrinkling is a critical issue in conventional spinning process. For this end, such a determining method for the formability in the process is proposed to rationally design the forming parameters to prevent flange wrinkling. The method is as follows: firstly, the maximum circumferential stress during the process is calculated at the outer edge of the flange, where the circumferential stress is considered as the combining result of the shrinkage of flange diameter and the bending of flange; then, the formability is determined by comparing the maximum circumferential stress to critical circumferential stress for wrinkling defect. Based on the method, a formability analytical model considering wrinkling defect in the first-pass conventional spinning process with a linear roller path is established. The formability model is validated by experiments and FE simulations at different spinning conditions. Sequentially, the influences of forming parameters and their interaction on the formability considering wrinkling defect are systematically analyzed. Furthermore, the forming diagrams considering wrinkling defect for the first-pass conventional spinning are established. It is found that the feed ratio has the most significant effect on the formability, followed by the blank thickness, the hardening exponent, the feed ratio-hardening exponent interaction and the feed ratio-sheet blank thickness interaction. The smaller feed ratio and hardening exponent, thicker sheet blank and greater relative sheet blank radius are helpful to increase the formability. The research results could provide a theoretical basis and guidance for the selection of forming parameters in the actual production of the first-pass conventional spinning. [ABSTRACT FROM AUTHOR]

Highlights • The remarkable biomedical applications of chitosan are discussed. • The electrospinning process for chitosan and a chitosan blend are reported. • The application of films and membranes of chitosan for wound dressings is described. • In vivo, in vitro studies and drug delivery applications of chitosan are reviewed. Abstract This review outlines new developments in the biomedical applications of environmentally friendly ('green') chitosan and chitosan-blend electrospun nanofibers. In recent years, research in functionalized nanofibers has contributed to the development of new drug delivery systems and improved scaffolds for regenerative medicine, which is currently one of the most rapidly growing fields in all of the life sciences. Chitosan is a biopolymer with non-toxic, antibacterial, biodegradable and biocompatible properties. Due to these properties, they are widely applied for biomedical applications such as drug delivery, tissue engineering scaffolds, wound dressings, and antibacterial coatings. Electrospinning is a novel technique for chitosan nanofiber fabrication. These nanofibers can be used in unique applications in biomedical fields due to their high surface area and porosity. The present work reviews recent reports on the biomedical applications of chitosan-based nanofibers in detail. [ABSTRACT FROM AUTHOR]

Abstract ZnO/In 2 O 3 composite nanofibers were fabricated by electrospinning method and effects of process parameters on the distribution and mean diameter of synthesized NFs were investigated. Electrospinning process followed by post calcination was performed at two different temperatures to optimize the synthesis condition of ZnO and In 2 O 3 NFs. Thermal Analysis was done on electrospun fibrocomposites to find calcination temperatures. Electrospinning parameters (Tip to Collector Distance (TCD), feeding rate, and applied voltage), which led to a uniform distribution and thinnest NFs, were used for synthesizing ZnO/In 2 O 3 composite in the co-electrospinning process. Structural, morphological, and chemical studies were also carried out on the NFs. TCD increment led to the improvement of diameter distribution and homogeneity of synthesized NFs. Low voltages (below 20 kV) resulted in thinner fibers without appearing any remarkable beads defect and the optimum feeding rate was found to be 1 ml/h. For further application of NFs in gas sensors, well distributed thinnest fibers were obtained. [ABSTRACT FROM AUTHOR]

Highlights • The electrospinning was developed for fabrication of collagen mimetic scaffold. • With addition of LA, LA assisted formation of 3D cotton-like fibrous structure. • The physicochemical properties of the as-fabricated scaffold were evaluated. Abstract The ability to mimic the topography of aligned collagen fiber bundles (A-CFB) that form the structural basis for the extracellular matrix (ECM) can be an important step in the fabrication of engineered scaffolds. Because the cell adhesion to the surface topography involve cell adhesion localized structures, topographical features, which mimics the A-CFB of the matrix can be a significant factor for cell activities. In this study, we present a novel method for the fabrication of low-density electrospun fibers mimicking A-CFB constructs. The three dimensional (3D) cotton-like A-CFB mimetic scaffold (3D-CACMS) of a mixture of lactic acid (LA) and polycaprolactone (PCL) was prepared by multiple pins rotator electrospinning (MPRES), followed by selective leaching of LA. The results of SEM, FTIR, TGA, and DSC revealed the physicochemical properties of the as-fabricated scaffold. This 3D-CACMS attempt to mimic A-CFB and can potentially meet the requirements for practical use of biomedical engineering. [ABSTRACT FROM AUTHOR]

Abstract Nowadays, aloe-vera (AV) is exploited extensively in nanofibrous structures for skin substitutes. However, the lack of electrospinnability and appropriate mechanical characteristics are the key limitations for this natural extract to be used in the form of nanofibrous mats. In this study, two commercially available biopolymers, gelatin (Gel) and poly(ε‑caprolactone) (PCL), were chosen to improve these issues and double-nozzle electrospinning technique was used to fabricate hybrid scaffold from Gel/AV blend and PCL solutions. Response surface methodology was utilized to investigate the effect of electrospinning parameters (Gelatin concentration, Aloe-vera concentration and Gel/AV feed-rate) on the mechanical properties, morphology and hydrophilicity of nanofibers and the optimized scaffold was chosen for further studies. In order to verify the application of this scaffold in bioapplications, the chemical, thermal and biological features of scaffold were analyzed using FTIR, DSC, biodegradability, bactericidal, biocompatibility and drug-delivery. The results revealed that the presence of aloe-vera improved the antibacterial activity (>99% and 85.63% against Gram-positive and Gram-negative bacteria, respectively), and led to adequate in-vitro biodegradation. Furthermore, it was found that incorporation of aloe-vera increased the cell viability without any toxicity. Graphical abstract Unlabelled Image Highlights • Aloe vera extract was produced successfully without any change in chemical and biological nature. • Aloe vera nanofibers were produced using double nozzle electrospinning. • MTT assay shows that fabricated scaffold doesn't have any toxicity. • FESEM images of cell cultured scaffold states that cells can proliferate on this biomaterial. • Tests show higher antibacterial activity for gram positive and gram negative bacterias. [ABSTRACT FROM AUTHOR]

Mass fabrication of sodium alginate nanofibers using single-nuzzle electrospinning process is an open challenge mainly due to its inter- and intramolecular hydrogen bonding, rigid chain conformation and low solubility. In this regards, we synthesized sodium sulfated alginate (SSA) through sulfation of hydroxyl functional groups of alginate. Not only decreases the hydrogen bonding density through the sulfation reaction, but the sulfated alginate also demonstrates more solubility in aqueous media compared to the pristine alginate. Beside the sulfation of alginate, its electrospinnability in combination with polyvinyl alcohol (PVA) significantly improves. In contrast to the neat alginate, concentrated aqueous solutions of sulfated alginate, 10 wt%, can be easily prepared and electrospun to obtain nanofibers of sulfated alginate. In this regards, facile fabrication of electrospun nanofibers of alginate derivatives with 50 wt% content in dry electrospun mat of SSA/PVA using single-nuzzle electrospinning and flow rate of 5 mL h −1 was developed for the first time. [ABSTRACT FROM AUTHOR]

Traditionally, the carrageenan fibers were prepared by process of extracting, drying, dissolving of carrageenan power and wet spinning process of fibers. However, in this study, carrageenan fibers were prepared by carrageenan solution directly from the extraction of Chondrus , without the steps of precipitation, and drying. The properties of carrageenan powder, spinning solution and carrageenan fibers were characterized with zeta potential, NMR, FTIR, dynamic light scattering (DLS), SEM, tensile testing and energy dispersive spectrometer (EDS). The results showed that the Chondrus contained mainly iota-carrageenan. The extraction of Chondrus was a uniform liquid with good properties of a solution, which was suitable as a spinning solution. The so prepared carrageenan fibers possessed good morphology and tensile properties. The excellent tensile properties of the carrageenan fibers were attributed to the combination of sulfate ester in the carrageenan and barium ions in the coagulation and then form a three-dimensional network structure. [ABSTRACT FROM AUTHOR]

It is an important approach to prevent the damage mechanisms that cause sudden fractures during fatigue loading in bonding joints by modifying the matrix with nanostructured materials. The aim of this study is to examine the effect of graphene nanoplates (GNPs) doped nylon 66 (N66) nanofiber mats reinforcement on the fatigue life of composite to aluminum single lap joint. For this purpose, 1 wt%, 3 wt% and 5 wt% GNPs doped N66 nanofibers were produced by electrospinning method. The morphological characteristics, chemical bond structures and % crystallinity of these nanofiber mats was investigated by SEM, TEM, FTIR, DSC analysis. The fatigue tests of the bonding joints with single axis periodic cycle loading were performed at five different load levels as 20%, 30%, 40%, 50% and 60% of the maximum shear strength of each samples. Fatigue life of bonding joints was assessed by S-N curves plotted according to the fatigue results. Damage mechanisms of fractured surface in the bonding joints were investigated with the macro and micro images. The results show that, these composite nanofiber mats have increased the fatigue life of bonding joints in all case. [ABSTRACT FROM AUTHOR]

The present study describes the fabrication of Tripolyphosphate (TPP)-crosslinked nanofibrous mats based on chitosan for use as a floating gastro-retentive delivery system. TPP-crosslinked chitosan (CH)/poly (ethylene oxide) (PEO)- ranitidine hydrochloride (RH) electrospun nanofibers (75.27 ± 2.10 nm) were prepared by electrospinning 70% v/v acetic acid solutions, and followed by crosslinking by TPP anions. The mechanical, structural and morphological properties of the prepared nanofibers were evaluated via tensile testing, XRD, FT-IR, TGA, NMR, AFM and SEM experimental techniques. The prepared nanofibrous mats showed a pH sensitive swelling profile with maximum water absorbing at pH 1.2. Results obtained from above experimental techniques indicated that crosslinking process did not significantly altered morphological property of nanofibers but rather decreased their diameter and swelling degree, and increased their mechanical properties, thermal stability and bioadhesive strength. Viscosity measurements showed that the addition of PEO and RH to the chitosan solution, depending to its concentration lead to decrease in the viscosity of its solution. Also, floating test showed that the prepared nanofibrous mats remain floated onto surface of the dissolution medium for more than 48 h. Based on in- vitro drug release data analysis, TPP-crosslinked CH/PEO nanofibrous mats decreased initial burst release and it was exhibited a sustained release profile for the RH from the TPP-crosslinked CH/PEO-RH electrospun nanofibrous mats. [ABSTRACT FROM AUTHOR]

In this study a thermo-sensitive switching membrane was prepared through grafting, using a click reaction, of an N -isopropylacrylamide (NIPAAm) derivative onto an electrospun poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) fibrous membrane (EPFM). The PPO was first electrospun into a fibrous membrane, then brominated and reacted with NaN 3 to generate the azido-terminated EPFMs. A propargyl-terminated poly( N -isopropylacrylamide) (PNIPAAm) was synthesized and grafted onto the azido-terminated EPFMs. The surface roughness of PPO fibers was increased due to the presence of PNIPAAm grafts, such that the thermoresponse of the static water contact angle (SWCA) of PNIPAAm-grafted EPFMs between 25 and 45 °C was significantly greater than that of the same PNIPAAm grafted on a flat surface. Thermo-sensitive affinity of the membrane with water resulted the average pore dimension responded to temperature changes. Taking advantage of this temperature-responsive affinity, we applied the membranes as protein valves that blocked and released an antibody. At 25 °C, the collection efficiency was 90% for antibody concentrations of up to 5 ng/mL. Increasing the temperature to 45 °C caused the collection efficiency to decrease abruptly, to 7.5%, when the antibody concentration was greater than 1.5 ng/mL. Accordingly, this system of PNIPAAm-grafted PPO fibers functioned as a protein valve, allowing the blocking and release of proteins. [ABSTRACT FROM AUTHOR]

The electrospun polyvinylidene fluoride (PVDF) based modified boron nitride (m-BN) composite with high thermal conductivity and flexible mechanical property was successfully fabricated by electrospinning method. The uniform dispersion and ordered orientation of m-BN in the m-BN/PVDF composites form a hot string, denoted as a series of thermal conduction fillers, in the direction of the fiber. Hence, the thermal conductivity of the m-BN/PVDF film could reach to 7.29 W m −1 K −1 with the addition of 30 wt% m-BN. Besides, the obtained composites also show improved mechanical properties with the tensile strength of 24.06 MPa, low dielectric permittivity of 2.45 and dielectric loss of 0.0242 @ 10 3 Hz. Therefore, this work provides a new route to prepare the high thermal conductivity films with potential application as flexible power devices. [ABSTRACT FROM AUTHOR]

Quite recently, the Ioncell-F process, a novel and promising Lyocell fibre process, has been developed. The ionic liquid 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH]OAc) utilized in this process, was identified as an excellent cellulose solvent for dry-jet wet fibre spinning. Fibres spun from cellulose-[DBNH]OAc solution have shown excellent mechanical properties. Herein, various structural features of these ionic liquid-based fibres were analyzed and correlated with their mechanical properties. The highest slope of tenacity increase of these Ioncell-F fibres (from birch wood) observed at low draw ratios (DRs), while a continuous but slower increase occurs to partly very high draws. The improvements in the mechanical properties do not seem to correlate with changes in the crystallite size or the crystalline orientation based on wide-angle X-ray scattering (WAXS) results. More significant differences were seen for the sample crystallinity, the amorphous orientation (measured by birefringence), the orientation of the voids, the specific surface (measured by small-angle X-ray scattering (SAXS)), and the sorption/desorption properties of the fibres. [ABSTRACT FROM AUTHOR]

Motivated by the extensive application of agar, this work developed a wet-spinning process to fabricate micro-scale fibers using the gelation process of agar. The effect of three vital spinning parameters, namely dope concentration, coagulation bath composition, and fiber post-processing on morphological properties, tensile properties and chemical structure of the fiber have been discussed. The concentration of agar was determined by the results of rheological measurement. The addition of barium chloride in the coagulation process improved the mechanical properties of fibers as compared to deionized water as coagulation. The agar fibers immersed in amino silicone demonstrated significantly showed better mechanical properties compared to the agar fibers only immersed in ethanol. The physical and chemical properties of agar fibers were characterized by X-ray diffraction, FTIR, tensile testing, and SEM. The results showed that excellent agar fibers with several potential applications can be produced with amino silicone modification in optimum coagulation bath. [ABSTRACT FROM AUTHOR]

Man-made lignocellulosic fibres were successfully prepared from unbleached birch kraft pulps by using the Ioncell-F technology. Pulps with different lignin content were produced by tailored kraft pulping with varying intensity. The degree of polymerization of the pulps was adjusted by acid-catalyzed hydrolysis and electron beam treatment. All substrates were completely soluble in 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH]OAc) and the respective solutions were spinnable to yield fibres with good to excellent mechanical properties despite the use of only mildly refined wood pulp. The tensile properties decreased gradually as the lignin concentration in the fibres increased. Changes in the chemical composition also affected the structure and morphology of the fibres. Both the molecular orientation and the crystallinity decreased while the presence of lignin enhanced the water accessibility. The effects of the crystallite size and lignin content on monolayer water adsorption are discussed. [ABSTRACT FROM AUTHOR]

The linear stability of a bilayer fiber spinning process is analyzed for axisymmetric disturbances under isothermal conditions. The co-extruded fiber consists of two concentric layers of rheologically stratified polymeric fluids. While the core fluid is an entangled polymer melt described using the eXtended Pom-Pom (XPP) model, the sheath layer is a low molecular weight unentangled polymer modeled as an Upper Convected Maxwell (UCM) fluid. The analysis indicates that, for fast extensional flows, such an arrangement enhances the critical draw ratio of the process over that found from the spinning of XPP fluid alone, thus delaying the onset of draw resonance and stabilizing the system. Further, the range of flow Deborah number for stable spinning is found to be much broader than that for the UCM fluid alone. For low to moderately elastic flows, the stability behavior is governed mainly by the rheology of the more-elastic core layer (XPP fluid), whereas for the highly elastic flows, the stability behavior is dominated by the less-elastic sheath layer (UCM fluid). The sensitivity of the stability diagram with respect to various spinning flow parameters, like the relative fraction of core and sheath layers, the rheological stratification of two fluids, and the spine-line dimensions, has also been examined in order to identify the region of enhanced stability such that the draw resonance is suppressed. [ABSTRACT FROM AUTHOR]

The production of pure water free of contamination is an urgent issue again today and still is not completely solved. The usage of filtering nanofiber could be a solution to this problem. The article describes the electrospinning device for fabrication of filtering nanofiber material considering various electrospinning plant components. The electrospinning plant can be tuned to produce nanofibres with different characteristics. The main controlled parameters of the electrospinning plant are voltage on the capillary and the collector, the amperage, the distance between the capillary and the collector, collector rotational speed, and the supply solution intensity to the capillary. A filter nanofiber electrospinning method manufacturing technology and the results of the experiment and the dynamic characteristics of electrospinning process are described. Depending on the parameters of nanofiber we analyzed water filtration efficiency. [ABSTRACT FROM AUTHOR]

Polyamic acid (PAA) fiber derived from 3,3′,4,4′-biphenyltetra-carboxylic dianhydride and p -phenylenediamine is prepared via dry-jet wet-spinning method. Polyimide (PI) fibers are obtained by applying two kinds of thermal treatment procedures on the PAA fibers. The evolution of fiber structure during thermal treatments is traced. And the influence of fiber structure on the mechanical properties is also studied. In Procedure I, the PAA fibers are heated from room temperature to 400 °C at 5 °C/min. As temperature increases from room temperature to 125 °C, relaxation behavior of PAA chains happens at first. Then, from 125 to 300 °C, imidization reaction occurs. Meanwhile, before the temperature reaches 250 °C, a significant degradation of PAA chains exists and makes the fibers too weak to measure. Crystals in fiber begin to form as temperature exceeds 250 °C and totally complete at 350 °C. The fracture strength and initial modulus of fiber are significantly improved with the formation of crystals and finally reach 0.83 GPa and 48.4 GPa at 400 °C, respectively. In Procedure II, the PAA fibers are isothermally treated at 250, 300, 350 and 400 °C for different times. When treated at 400 and 350 °C, both imidization and crystallization in fiber can happen simultaneously and complete in tens of seconds because of the high mobility of the polymer chains. While as treated at 300 and 250 °C, both these two processes are slowed down and the formation of crystals lags behind the imidization process. High crystallinity can be obtained under higher treatment temperature in a very short time. The mechanical properties of fiber highly depend on the treatment temperature rather than the treatment time. The fibers treated at 400 °C for 60 s show the highest fracture strength and initial modulus of 1.4 GPa and 70.0 GPa, respectively. [ABSTRACT FROM AUTHOR]

The development of a loose inner-selective polyethersulfone (PES) hollow fiber by one-step spinning process for nanofiltration (NF) has been demonstrated in this study. It is found that the addition of a small amount of sulfonated polysulfone (SPSf) and the use of a specially designed bore fluid made of hydrophilic additives such as polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) are of great importance to fabricate this type of NF membranes. Not only are they able to reduce the pore size but also suppress the formation of finger-like macrovoids. After optimizing both dope solution and spinning conditions, the as-fabricated membrane can have a 70% rejection to PEG 1000 and a pure water permeability (PWP) of 12.8 L m −2 h −1 bar −1 . Its rejection of indigo carmine (MW: 466 gmol −1 ) can reach 96.64%. In addition, it shows good stability in a continuous 76-h operation with good efficiency of dye removal. The newly developed membrane may have great potential in the treatment of textile wastewater. [ABSTRACT FROM AUTHOR]

This study demonstrates a designed multi-stranded helical motif that self-spun naturally by six to eight polyacetylene (PA) chains. The spiral of one end results in the helical behavior of the whole long polymer. We show that six PA chains with length of 1017.2 Å (1 nm) can self-spin continuously to form multiple helical structure. The basic strand-strand interaction, self-spun mechanism, and thermal stability during the natural helix-forming are particularly explained. The formed PA multiple helices are stable at room temperature. It is expected that these findings could stimulate enormous effects on the synthesis of helical polymers to further develop novel PA helix based functional materials and nanoscale devices. [ABSTRACT FROM AUTHOR]

A new facility for the measurement of AC loss in superconductors at high dB/dt has been developed. The test device has a spinning rotor consisting of permanent magnets arranged in a Halbach array; the sample, positioned outside of this, is exposed to a time varying AC field with a peak radial field of 0.566 T. At a rotor speed of 3600 RPM the frequency of the AC field is 240 Hz, the radial dB/dt is 543 T/s and the tangential dB/dt is 249 T/s. Loss is measured using nitrogen boiloff from a double wall calorimeter feeding a gas flow meter. The system is calibrated using power from a known resistor. YBCO tape losses were measured in the new device and compared to the results from a solenoidal magnet AC loss system measurement of the same samples (in this latter case measurements were limited to a field of amplitude 0.1 T and a dB/dt of 100 T/s). Solenoidal magnet system AC loss measurements taken on a YBCO sample agreed with the Brandt loss expression associated with a 0–0.1 T I c of 128 A. Subsequently, losses for two more YBCO tapes nominally identical to the first were individually measured in this spinning magnet calorimeter (SMC) machine with a B max of 0.566 T and dB/dt of up to 272 T/s. The losses, compared to a simplified version of the Brandt expression, were consistent with the average I c expected for the tape in the 0–0.5 T range at 77 K. The eddy current contribution was consistent with a 77 K residual resistance ratio, RR, of 4.0. The SMC results for these samples agreed to within 5%. Good agreement was also obtained between the results of the SMC AC loss measurement and the solenoidal magnet AC loss measurement on the same samples. [ABSTRACT FROM AUTHOR]

A major challenge in developing drug-releasing electrospun nanofibers is obtaining long-term drug release over many weeks with no burst release of drug. Here, we present new methods capable of prolonging the diffusive release of small molecule drugs from electrospun poly- l -lactic acid (PLLA) nanofibers. The methods focus on removal of retained electrospinning solvent through fiber heating, maintaining fibers in a laboratory setting, or a combination of these methods. These post-fabrication methods altered the release characteristics of a model small molecule drug, 6-aminonicotinamide (6AN), from PLLA fibers. Specifically, untreated fibers released 6AN over 9 days, and fibers that underwent a combined treatment of maintenance in a laboratory setting and heating released 6AN over 44 days. The unique and simple method presented here prolongs diffusive release of a small molecule drug from electrospun fibers and has potential to assist in lengthening small molecule drug release from a variety of polymeric nanomaterials. [ABSTRACT FROM AUTHOR]

This paper presents a comparison and evaluation of cardiac cell proliferation on poly( l -lactic acid) (PLLA) and polyurethane (PU) nanofibrous mats fabricated by solution blow spinning (SBS). Three different cardiac cell lines: rat cardiomyoblasts (H9C2 line), human (HCM) and rat cardiomyocytes (RCM) were used for experiments. Cell morphology, orientation and proliferation were investigated on non-modified and protein-modified (fibronectin, collagen, gelatin, laminin, poly- l -lysine) surfaces of both types of nanofibers. Obtained results of cell culture on nanofibers surfaces were compared to the results of cell culture on polystyrene (PS) surfaces modified in the same way. The results indicated that in most cases polymeric nanofibers (PLLA and PU) are better substrates for cardiac cell culture than PS surfaces. All types of investigated cells, cultured on nanofibers (PLLA and PU), had more elongated shape than cells cultured on PS surfaces. Moreover, cells were arranged in parallel to each other, according to fibers orientation. Additionally, it was shown that the protein modifications of investigated surfaces influenced on cell proliferation. Therefore, we suggest that the cardiac cell culture on nanofibrous mats fabricated by SBS could be more advanced experimental in vitro model for studies on the effect of various cardiac drugs than traditional culture on PS surface. [ABSTRACT FROM AUTHOR]

We report on magnetism, transport and spin polarization characteristics of the melt-spun Cu 2 MnSn alloy prepared by the rapid quenching technique. The as- cast ribbons showed a relatively well ordered chemical composition (Cu = 50.4%, Mn = 27.1%, Sn = 22.5%). The structural characterization by using X-ray diffraction shows L2 1 /B2 crystalline structure with the lattice parameter a = 6.196 Å. The magnetic and transport measurements show a metallic behavior with the Curie temperature of 530 K and reveal anisotropic character with the easy magnetization plane parallel with respect to the ribbon plane. As-cast Cu 2 MnSn ribbons show the spin polarization measured by using Andreev reflection technique within the range 68–75%. [ABSTRACT FROM AUTHOR]

Antibacterial electrospun fibrous membranes are widely applied as dressings for treatment the wounds and burns. However, developing long-term gelatin-based fibrous membrane is still the main challenge inhibiting their uses for long-term treatments. Novel antibacterial electrospun gelatin-based mats were introduced by combining gelatin, glycerol, glucose and silver nanoparticles (Ag NPs), which together could exhibit optimal physicochemical characteristics as long-term electrospun fibrous mats. Therefore, Ag NPs were synthesized in-situ within the acidic electrospun solutions during preparing electrospun gelatin-glycerol-Ag NPs (GEL-GLY-Ag) and gelatin-glycerol-glucose-Ag NPs (GEL-GLY-GLU-Ag) mats. Conventional spectroscopic techniques based on XRD, FTIR, SEM, DTA, and water uptake-degradation tests and antibacterial studies were used to characterize the preparations. The results showed that the electrospun gelatin-based composites mats revealed free beads dense fibrous textures, and exhibited a high water uptake and long-term degradation behavior. The Ag NPs could be successfully synthesized in-situ within electrospinning solutions and the results confirmed that the in-situ prepared Ag NPs enhanced the antibacterial activity of electrospun mats against positive and negative bacteria. [ABSTRACT FROM AUTHOR]

A type of contamination that has been little studied in cars comes from the extremely low frequency (ELF) magnetic fields generated by the vehicle's electrical devices and the magnetized metal in the tyres. The magnetic fields in cars are frequently analysed with broadband meters sensitive to a frequency range above 30 Hz. This has the disadvantage that they neither detect the magnetic field of the spinning tyres nor give any information on the spectral components, which makes it impossible to adequately assess exposure. The objective of the present study was to perform spectral analyses of ELF magnetic fields in cars, to identify their frequencies, and to assess exposure based on the ICNIRP regulatory guidelines. To do this, a meter and a spectrum analyser sensitive to magnetic fields in the 5 Hz–2 kHz frequency range were used. Spectra were acquired for different seats, heights, and speeds, and spatially averaged exposure coefficients were calculated. The results indicated that the main emissions were detected in the 5–100 Hz range, where the wheel rotation frequencies and their harmonics are found. The intensity of the rest of the emissions were negligible in comparison. The exposure quotient increases with speed, and is approximately twice as great at foot level as at head level. The magnetic field levels are lower than the reference levels (the maximum represents 3% of the ICNIRP standard), but higher than those found in residential environments and than the cut-off threshold used by the IARC to classify ELF magnetic fields in Group 2B [ABSTRACT FROM AUTHOR]

Self-assembling (SAPs) and co-assembling peptides (CAPs) are driving increasing enthusiasm as synthetic but biologically inspired biomaterials amenable of easy functionalization for regenerative medicine. On the other hand, electrospinning (ES) is a versatile technique useful for tailoring the nanostructures of various biomaterials into scaffolds resembling the extracellular matrices found in organs and tissues. The synergistic merging of these two approaches is a long-awaited advance in nanomedicine that has not been deeply documented so far. In the present work, we describe the successful ES of a library of diverse SAPs and CAPs into biomimetic nanofibrous mats. Our results suggest that suitable ES solutions are characterized by high concentrations of peptides, providing backbone physical chain entanglements, and by random coil/α-helical conformations while β-sheet aggregation may be detrimental to spinnability. The resulting peptide fibers feature interconnected seamless mats with nanofibers average diameters ranging from ∼100 nm to ∼400 nm. Also, peptide chemical nature and ES set up parameters play pivotal roles in determining the conformational transitions and morphological properties of the produced nanofibers. Far from being an exhaustive description of the just-opened novel field of ES-assembled peptides, this seminal work aims at shining a light on a still missing general theory for the production of electrospun peptidic biomaterials bringing together the spatial, biochemical and biomimetic of these two techniques into unique scaffolds for tissue engineering. Statement of Significance Construction of peptide hydrogels has received considerable attention due to their potential as nanostructures amenable of easy functionalization and capable of creating microenvironments suited for culturing cells and triggering tissue regeneration. They display a superior biocompatibility unmatched by other known synthetic biomaterials so far. However, their applications are confined to body fillers because most of them do spontaneously form hydrogels, while effective tissue regeneration often requires well-defined fibrous scaffolds. In this work, we developed electrospun fibers of various peptides (cross-beta self-assembling, hierarchically assembling, functionalized, co-assembling) and we provided a deep understanding of the crucial phenomena to be taken into account when peptides fibers fabrication. These results open new venues for exploring novel regenerative applications of peptide nanofibrous scaffolds. [ABSTRACT FROM AUTHOR]

In this work, we have investigated the influence of Ag-doping on the magnetic and magnetocaloric effect (MCE) of Ni 50-x Ag x Mn 37 Sn 13 ribbons with x = 1, 2, and 4, which were prepared by a melt-spinning method. With increasing Ag concentration, a systematic decrease in the antiferromagnetic interaction and in the magnetic phase transition temperatures was observed. Analyses of the critical behavior based on the Banerjee criterion and scaling hypothesis for M ( H , T ) data near the ferromagnetic-paramagnetic transformation prove an increase of Ag favors establishing long-range ferromagnetic interactions in the austenitic phase. The temperature and magnetic field dependences of magnetic entropy change, Δ S m ( T , H ) were investigated via isothermal magnetization measurements. Interestingly, these samples exhibit a MCE at room-temperature with the Δ S m ( T ) curves distributed over a quite wide temperature range. To enhance the relative cooling power (RCP) value and to extend the magnetic phase transition region, we have prepared the composites in the form of the layered material samples based on ribbons obtained above. Under Δ H = 10 kOe, the maximum value of Δ S m (denoted as |Δ S max |) at around room-temperature is 1.08 J kg −1 K −1 , corresponding to RCP = 51.8 J kg −1 , which is about 10% higher than that obtained from a separate sample. Additionally, we also pointed out that the dependences of |Δ S max | on Δ H at around room-temperature for samples obey a power law, |Δ S max | = a × Δ H n , and all the Δ S m ( T , H ) data obey completely a universal master curve. [ABSTRACT FROM AUTHOR]

A series of misch-metal (MM = 28.27 wt % La, 50.46 wt % Ce, 5.22 wt % Pr, 15.66 wt % Nd)-iron-boron isotropic ribbons with atomic formula (MM) 12+x Fe 82-x-y B 6+y (x = 0, 1, 2, 3, 4, y = 0, 0.5, 1, 1.5, 2) are prepared by melt spinning technique. A large energy product ( BH ) max of 12 MGOe is obtained with the composition of MM 13 Fe 81 B 6 at optimized processing. The ribbons with both coercivity larger than 10 kOe and ( BH ) max larger than 10 MGOe are achieved in a wide composition range. All the samples exhibit the tetragonal crystal structure. The magnetization and Henkel plot (δ M ) measurements indicate that the ribbons have a relatively homogeneous microstructure and strong exchange-coupling interactions. The average grain size of the ribbons is around 30 nm determined via Scherrer's formula. Meanwhile, the transmission electron microscope (TEM) image also verifies that the ribbons have a homogeneous nanoscale microstructure. In addition, the spin reorientation temperature T sr is investigated by ac susceptibility χ ac measurement. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNT) fibres were printed from liquid suspension. The resulting fibres are highly conductive, with conductivity close to the one of standard CNT fibres, flexible and very versatile. The printed fibres are comparable to fibres that can be gained from direct spinning, carpet spinning and spinning from superacids, but offer broader range of composition and are simpler and safer to produce as no high-temperature equipment and dangerous chemicals need to be used. Any CNT material can be implemented, allowing the use of a variety of CNT structures, different densities of the fibres and various shapes for the final product. [ABSTRACT FROM AUTHOR]

A novel magnetic-mechanical spinning method was used to fabricate ultrafine parallel polyaniline/polyvinylidene fluoride/γ-Fe 2 O 3 (PANI/PVDF/γ-Fe 2 O 3 ) fibers. The magnetic field is generated by a permanent magnet which plays a decisive role in the spinning process. Moreover, the resultant fiber is continuous and the length of the fiber can be tens of meters. Additionally, the fibers are well aligned and the alignment can be maintained. The composite fibers show an electrical conductivity of 6.4 × 10 −4 S cm −1 and good superparamagnetism at room temperature. In particular, the strain sensor based on the twisted fibers shows an ultrahigh stretchability up to 440%, and a quick and repeatable response to finger pressure. The electromagnetic functionalized composite fibers may be used in stretchable devices, sensors, or electromagnetic interference shielding. [ABSTRACT FROM AUTHOR]

In this work, we report on the preparation of a novel biodegradable textile scaffold made of palmitoyl-hyaluronan (palHA). Monofilament fibres of palHA with a diameter of 120 μm were prepared by wet spinning. The wet-spun fibres were subsequently processed into a warp-knitted textile. To find a compromise between swelling in water and degradability of the final textile scaffold, a series of palHA derivatives with different degrees of substitution of the palmitoyl chain was synthesized. Freeze-drying not only provided shape fixation, but also speeded up scaffold degradation in vitro . Fibronectin, fibrinogen, laminin and collagen IV were physically adsorbed on the textile surface to enhance cell adhesion on the material. The highest amount of adsorbed cell-adhesive proteins was achieved with fibronectin (89%), followed by fibrinogen (81%). Finally, textiles modified with fibronectin or fibrinogen both supported the adhesion and proliferation of normal human fibroblasts in vitro , proving to be a useful cellular scaffold for tissue engineering. [ABSTRACT FROM AUTHOR]

Micro- or nanofiber-based materials have extensive applications in biomedical fields due to their capability to mimic many aspects of physiological microenvironment in vivo . Fabricating micro- or nanofibers using biocompatible and biodegradable materials is becoming of great interest in the area of biomaterials and tissue engineering. Among the various technologies, electrospinning and microfluidic spinning are the two promising approaches to produce fibers at micro- and nano-scale. Choosing an appropriate spinning method is critical important for a specific application. Although some review papers on each spinning method have been published, a review comparing these two methods has not been reported yet. In this review, we present an overview of the two spinning methods including the spinning principle, their unique features and materials selections. Several applications of fibers spun by both methods, especially in tissue engineering, organ function regeneration and drug delivery are introduced. The current challenges, future directions and potential applications of these approaches are discussed as well. [ABSTRACT FROM AUTHOR]

Synthetic gel-spun collagen and collagen/nano-carbon fibers were found to exhibit structural mimicry comparable to native tendons. X-ray scattering and microscopy analyses are used to characterize the molecular and fibrillar alignment in the synthetic fibers, where D-banding is observed throughout the spun fibers – consistent with native collagen. For the composite collagen/nano-carbon fibers, the morphology and dispersion quality of the nano-carbons within was found to play a significant role in influencing collagen molecular ordering and fibril alignment. Fibrillar and molecular alignment was also better preserved during elongation of the composites as compared to the control collagen fibers. These results show the structural influence of a rigid inclusion on the collagen fibril structure. Both dry- and wet-state tensile testing were performed on the collagen fibers, and these results show behavior comparable to the native materials. Dry-state tests also reveal interfacial interaction between the nano-fillers and the collagen fibrils through theoretical analysis. Wet-state tensile testing indicates the structure–property behavior of the mimetic hierarchical structure within the synthetic fibers. [ABSTRACT FROM AUTHOR]

In this paper the morphological, mechanical and electrical characteristics of fibers electrospun from a of poly-ε-caprolactone polymer solution with different percentages of graphene nanoplatelets mixed in are reported. The morphology of the fibers was studied under optical and scanning electron microscopes to investigate the interaction of the two phases within the fibers. The scaffolds were characterized to identify the effects of the graphene on the intrinsic properties of the material. The preparation of an optimized suspension of the graphene in the solution was found to be a fundamental factor for enhancing the applicability of the resulting fibers. [ABSTRACT FROM AUTHOR]

By blending cellulose and duck feather in the common solvent 1-allyl-3-methylimidazoloium chloride, a regenerated composite fibre has been developed with improved fibres over regenerated cellulose fibres (RCF). The mechanical properties of composite fibre was shown to be better than RCF with a 63.7% improvement in tensile strain. Here, we thoroughly characterise the composite fibre and show that the composite fibre has many advantages over RCFs both from a spinning perspective and as a regenerated fibre. [ABSTRACT FROM AUTHOR]

The synthesis of two novel catalytic materials based on vanadium mixed oxides has been described in present study. The first material was a Vanadium-Phosphorous mixed oxide (VPO) carbon-supported material with fibrous morphology and a very high surface area, and stable under oxidizing conditions up to 350 °C. The other material is a bulk mixed VPO oxide with fibrous structure obtained after optimizing the calcination of the supported carbon fiber catalyst, which presents a very high surface area. Both materials seem to be very attractive as catalysts in a wide range of partial oxidation processes in both liquid and gas phase based on the structural and chemical characterization data. [ABSTRACT FROM AUTHOR]

Nano and submicrometric fibers of TiO 2 and ZnO were produced for the first time by solution blow spinning (SBS). High surface area, homogenous, crack free TiO 2 and ZnO fibers were successfully spun, as confirmed by BET surface area, X ray diffraction (XRD), transmission electron (TEM) and scanning electron (SEM) microscopy studies. TiO 2 and ZnO fibers presented mean diameters ranging from 300 nm to 600 nm and from 200 nm to 550 nm, respectively. SBS proved to be an efficient method of producing metal-oxide semiconductor nano and submicrometric fibers at high output rates when compared other fiber spinning techniques. [ABSTRACT FROM AUTHOR]

Graphene-based materials are usually expected to be good thermal conductors. Here, we report on the low thermal diffusivity of free-standing graphene fibers (GFs) fabricated by wet-spinning method. The GF sample mainly consists of freestanding graphene oxide. The radiation effect is excluded by measuring GFs of different lengths. The thermal diffusivity of the suspended GF sample is determined at (2.0–2.08)×10 −6 m 2 s −1 , and the corresponding intrinsic thermal conductivity is 1.14–1.18 W/m K. The low thermal conductivity is mainly attributed to the large thermal contact resistance and very strong phonon scattering at grain boundaries. The finding will be beneficial for thermal design of GF-based thermal energy applications. [ABSTRACT FROM AUTHOR]

One-dimensional (1-D) carbon nanofibers anchored with partially reduced SnO 2 nanoparticles (SnO 2 /Sn@C) were successfully synthesized through a simple electrospinning method followed by carbon coating and thermal reduction processes. The partially reduced Sn frameworks, combined with the carbon fibers, provide a more favorable mechanism for sodiation/desodiation than SnO 2 . As a result, SnO 2 /Sn@C exhibits a high reversible capacity (536 mAh g − 1 after 50 cycles) and an excellent rate capability (396 mAh g − 1 even at 2 C rate) when evaluated as an anode material for sodium-ion batteries (SIBs). [ABSTRACT FROM AUTHOR]

Polymer infiltration is an efficient way to strengthen carbon nanotube fibers in the process of spinning. Given the carbon nanotube/polymer composite fibers obtained from this approach possess higher mechanical properties than the ones of their components, the general rule of mixtures for a composite material is not applicable. Accordingly, a novel coarse-grained molecular dynamics model is proposed to investigate the mechanical behavior and microstructural evolution of the composite fibers, in which the carbon nanotubes and polymer chains are represented by mesoscale coarse-grained beads. Then the reinforcing mechanism of the composite fibers is illustrated. Dependence of the mechanical behavior on the microstructure of the composite fiber under different strain rates is revealed as well. Furthermore, the variations of mechanical properties of the composite fibers with cycle numbers under relatively low load are predicted. [ABSTRACT FROM AUTHOR]

Twist may be introduced accidentally into braided ropes during operations at sea, and it is important to know how this will affect both rope integrity and safety coefficients. This paper describes the use of simulation tools to evaluate how twisting can change the tensile properties of braided ropes. The case of a 300 kN break load 12 strand braided HMPE rope is examined. An original numerical modelling approach is presented, and results are compared with results from tensile tests performed on ropes with different levels of twist. A drop in strength of around 4% per turn per meter, and an increase in elongation, were observed as the number of turns per meter increased, corresponding to progressive removal of the load-bearing capacity of half the braided strands. The model shows how load is progressively redistributed within the braid. However, very high twist levels (>10 T/m) are required to reduce strength below 50% of the initial value. [ABSTRACT FROM AUTHOR]

In the spinning industry, waste yarns are generally forsaken or sale at low prices. The main purpose of this study is to give an added value to this waste and produce a new low cost yarn based on recycled yarn fibers. The first part of this study investigated the effect of the raw material and the recycling process taking into account the cut length (L) and the passage number (N) on the final quality of reclaimed fibers. The effect of different factors on the count of Neps (Neps), mean length (L), short fiber content (SFC), Upper Quartile Length (UQL), and weight yield (R) were examined by using design of experimental method. In the second part of this work, the highest quality fibers (Neps = 260Cnt/g, SFC = 26%, UQL = 23.9 mm, L = 18 mm and R = 61.20%) were selected for this project. They were spun with a ratio cotton/recycling cotton 50/50 into a three account (Ne 10, Ne 15 and Ne 20). Comparing with the 100% cotton yarn, the blended yarn has similar physical and mechanical properties and it has a lower cost yarn since we can increase the total value of the yarn more than 33.5%. [ABSTRACT FROM AUTHOR]

A fluorescent film based on a cholesteryl derivative of perylene bisimide (PTCDI- co -CholDEA) was fabricated via utilization of an electrostatic spinning technique on a glass plate surface. SEM studies revealed that the film was characterized by fibrous network structure. It is the structure and the chemical composition that make the fluorescence emission of the film sensitive to the variation of local environmental humidity. The sensitivity of the sensing is 0.1497 (× 10 4 a.u. of the intensity)/1% RH, of which RH is the abbreviation of relative humidity. The maximum quenching efficiency of the film is 55.4% when humidity reaches 97% RH. Furthermore, the sensing process is fully reversible, and presence of other commonly found liquids shows little effect to the monitoring process. [ABSTRACT FROM AUTHOR]

This work addresses the challenge to produce fibers from the water-soluble polymer poly(vinyl alcohol) (PVA), using solution blow spinning (SBS) with forced solvent evaporation at the point of fiber formation. PVA at two different molecular weights, with different degrees of acetylation, were successfully blow spun into nano- and micro-fiber membranes, across a range of concentrations in water (12–20 w/v%). Fiber spinnability, morphology and size are correlated to precursor solution viscosity and PVA type. PVA with degree of polymerization 1100 and degree of hydrolysis 98–99% was relatively facile to spin into fibers. Difficulties in spinning high molecular weight PVA were overcome by introducing hot air at the point of fiber formation to force water evaporation. The procedure developed here opens SBS to other aqueous-based polymer and composite systems for environmentally benign fiber and membrane formation. [ABSTRACT FROM AUTHOR]

Electrospinning is not only a technique to fabricate macroscopic fiber but also a method to control the microstructure. In this study, high-temperature solution electrospinning was used to prepare isotactic polypropylene (iPP) fibers. Scanning electron microscope (SEM) observation indicates that a single electrospun iPP fiber consists of many nano-fibrils. Based on SEM observation, these nano-fibrils are shish-kebab structure. Electrostatic elongational force involved in the electrospinning process is considered to be responsible for the development of shish-kebab structure. [ABSTRACT FROM AUTHOR]

A novel structure with TiO 2 micro-/nano-spheres embedded in nanofibers was fabricated by coaxial electrospinning. The formation mechanism of the embedded structure and the effects of core flow rates on photocatalytic properties were investigated, and their photocatalytic properties were compared with the photocatalytic properties of nano-spheres and nanofibers. The micro-/nano-spheres were embedded in TiO 2 nanofibers with different physical properties of core and shell spinning solutions. The specific surface area of the nanofibers improved to 23.852 m 2 /g, and the degradation rate for methylene blue increased to 91.56%. The novel structure has large nanofiber gaps. We obtained a high specific surface area for the micro-/nano-spheres, which present a loose structure and are conducive for UV injection to improve photocatalytic efficiency. [ABSTRACT FROM AUTHOR]

Curved and structured membrane geometries are known to have the potential to reduce concentration polarization and fouling rates in membrane filtration and membrane contacting applications. However, their production is cumbersome and often comprises various successive processing steps. We present a new direct fabrication process of two new hollow fiber geometries: Curled and meandering hollow fibers. The phenomenon of liquid rope-coiling is adapted to a membrane spinning process resulting in mostly spiralling curly fiber geometries. Parameters influencing geometric properties are evaluated and experimentally obtained structures are presented. Fibers were prepared from a polyethersulfone-based polymer solution in an air gap spinning process. Prepared structured hollow fibers are investigated regarding geometrical measures and pore structures. A comprehensive analysis of the complex interplay between the influencing parameters is suggested. [ABSTRACT FROM AUTHOR]

The optimum synthesis conditions for carbon nanotube (CNT) fibers were investigated using the Design of Experiment (DOE) technique. Direct spinning processes are governed by a variety of experimental factors: the methane flow rate, ferrocene flow rate, sulfur flow rate, hydrogen flow rate, water flow rate, and reaction temperature. The process was optimized in two stages that addressed first the Fractional Factorial Design (FFD) and then the Response Surface Methodology (RSM). Results from each experiment were classified according to a 6-step rating system: nothing(1), black gas(2), dust(3), ribbon or film(4), fiber(5), or continuous fiber(6). In the first step, three major factors (methane, sulfur, temperature) were identified as important among the six experimental factors tested using FFD. The effects of the major factors and the interactions were analyzed through the main effect plot and the interaction plot. In the second step, the experimental conditions were optimized using a model equation derived from Box-Behnken design experiments. Finally, the CNT fibers were continuously synthesized under the optimum conditions. The synthesized CNT fibers mainly consisted of single-walled CNTs (SWCNTs) 1.2–3.8 nm in diameter. The I G /I D ratio of the CNT fibers was 48. This work provides a useful methodology for synthesizing the CNT fibers. [ABSTRACT FROM AUTHOR]