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Core-shell-structured polyvinyl alcohol (PVA)-poly (lactic acid) (PLA) nanofibers combining the hydrophilic trait of PVA and the biocompatibility of PLA were produced using coaxial electrospinning. This allowed the incorporation of AgN[O.sub.3] in the PVA core of the distinct fibers as shown through transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) showed relatively uniform and bead-free fibers with smooth surfaces. Ag-containing fibers show significantly decreased diameters compared with Ag-free samples as a result of the increased conductivity of the spinning solutions with increasing amounts of AgN[O.sub.3]. In a postsynthetic treatment, the AgN[O.sub.3] was reduced forming silver nanoparticles (Ag NPs). Ag NPs of 45 to 90 nm size were located in the PVA core but also on the surface of the core-shell fibers and as individual, agglomerated, and polymer-coated particles of 100-200 nm. Powder X-ray diffraction (PXRD), energy dispersive X-ray spectroscopy (EDX), and UV-vis absorption spectroscopy confirmed the increasing amounts of Ag in the core-shell fibers when using increasing amounts of AgN[O.sub.3] in the spinning solutions. The antibacterial activity of the nanofiber mats against two prokaryotes Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) increased with increasing amounts of Ag, as expected and produces inhibition zones of 1 to 2 mm. KEYWORDS antibacterial, coaxial electrospinning, core-shell fibers, poly (lactic acid), polyvinyl alcohol, silver nanoparticles, 1 | INTRODUCTION Worldwide, microbial infections are a significant and worrying challenge, and the design and synthesis of antimicrobial products for different applications are eminent fields of research. [1-3] Nanomaterials [...]

Carpeting is one of the most efficient approaches to provide both the acoustic and thermal insulation, and improve the comfort of building inhabitants. In the current research work, the acoustic and thermal properties of handmade carpets as one of the commonly used textile products in several countries, especially in Middle-East countries, have been investigated. Aiming to find the optimum weaving condition to maximize the insulation performance of the handmade wool carpets, the weaving variables of knot type, knot density, and pile height were changed. By performing a set of experiments according to the Response Surface Methodology (RSM), the sound absorption coefficient and thermal resistance values were measured for each sample. The statistical analysis showed that the sound absorption and thermal properties of carpets were appropriately described with the linear model. The pile height was the most effective factor for the both sound absorption and thermal resistance responses. Knot density was marginally significant, while the knot type had a negligible contribution. Increasing the height of the pile and knot density led to an increase in sound absorption and thermal resistance. The optimization procedure suggested that within the experimental range, the best acoustic and thermal insulation, can be obtained at knot density of 35 (per 7 cm), and the pile height of 3 cm. [ABSTRACT FROM AUTHOR]

In this study, the continuous twisted PLLA yarns were produced using an electrospinning device consists of two oppositely charged nozzles. The electrospinning process was performed at different twist rates. The electrospun twisted yarns were drawn at different extension ratios of 50% and 100% and their morphological and mechanical properties of post-drawn yarns were investigated. The morphological studies at all twist rates shown that uniform and smooth fibers without any bead were formed. Increasing the twist rate up to 240 rpm resulted to a decrease in the average diameter of the fibers in the yarn structure. After uniaxially drawing of the yarns, the average diameter of fibers and thus the yarn diameter decreased. The post-drawing process enhanced the crystallinity of the fibers in the yarn structure. Furthermore, by increasing the extension ratio, the tensile strength and modulus of yarns increased, while the elongation at break (%) decreased., INTRODUCTION The traditional industry of textile is an important part of the world manufacturing industry. Apart from the traditional application of textile materials in clothes and fabrics, recently they have [...]

Hydrogels are porous biomaterials widely used in tissue engineering (TE), but they require a mechanism to enhance their mechanical properties. Electrospun nanofibrous yarn (EN yarn) can be a suitable candidate for reinforcing hydrogels. In this study, aiming to improve mechanical performance, hydrogel-based scaffolds reinforced by EN yarns (yarn reinforced hydrogel) were fabricated. The morphological characterization, swelling measurement, and tensile tests were performed to evaluate the physical, mechanical, and biological function of the designed yarn reinforced hydrogel. The measured mechanical properties were used as inputs in the mathematical model of the modified rule of mixtures to predict the mechanical behavior of different yarn reinforced hydrogels, which could be used as scaffolds for different tissues. Cell-scaffold interactions were also evaluated by in vitro assays. This study indicated that adding EN yarns to the neat hydrogel decreased the porosity and swelling, while the tensile strength and Young's modulus were improved. In vitro assays showed that cells had better adhesion and spread on the surface of the yarn reinforced hydrogel than those on the surface of the neat hydrogel. Regarding the improvement in mechanical and cellular properties, the yarn reinforced hydrogel has the potential to be used as a novel scaffold in TE. [ABSTRACT FROM AUTHOR]

Nitrate, as one of the primary pollutants, is found in agricultural drainage water, and human and animal excrement. Nitrate causes damage to water environments and endangers human health. It is clear that the research is very important for the development and improvement of existing methods for treating water containing high concentrations of nitrate. This study was conducted aimed to investigate the possibility of using a batch system of nanoclay modified with the organic surfactant hexadecyltrimethylammonium bromide (HDTMA-Br) to remove nitrate anion as a model pollutant from drinking water containing this pollutant. This study was conducted on laboratory and batch reactor scale. Removal efficiency of different pH 4-9, contact time 15-60 min, nanoclay adsorbent concentration modified with organic surfactant HDTMA-Br 0.5-1.5 g/dL and nitrate concentration 25-75 mg/L was investigated. Nitrate concentration was measured by ultraviolet spectrophotometer. Based on the scanning electron microscopy, the particles have a uniform shape with high porosity and the diameter of the nanoclay particles modified using the organic surfactant HDTMA-Br was 1.6 nm. Based on the X-ray diffraction analysis, the modification process changed the base distance in the nanoclay structure from 17 to 24 Å. The best conditions for removal of 25 mg/L of nitrate (100% efficiency) included contact time of less than 15 min, optimum temperature of 20°C, optimum pH 4 and concentration of 1 g/dL of nanoclay modified using organic surfactant HDTMA-Br with the surface of the surfactant was 40% of the cation exchange capacity. The maximum nitrate adsorption capacity was 94.33 mg/g by following the Langmuir isotherm (correlation coefficient of 0.9960) and second-order adsorption kinetic (correlation coefficient of 0.9988). The results showed that the modified nanoclay adsorbent is a suitable, cheap and efficient method for removing nitrate from drinking water. Nanoclay adsorbent modified with the organic surfactant HDTMA-Br is used as a strong adsorbent to remove nitrate from aqueous media due to its high adsorption capacity and reusability for at least 4 cycles of recycling. [ABSTRACT FROM AUTHOR]

The delivery of drugs through the skin barrier at a predetermined rate is the aim of transdermal drug delivery systems (TDDSs). However, so far, TDDS has not fully attained its potential as an alternative to hypodermic injections and oral delivery. In this study, we presented a proof of concept of a dual drug-loaded patch made of nanoparticles (NPs) and ultrafine fibers fabricated by using one equipment, i.e., the electrospinning apparatus. Such NP/fiber systems can be useful to release drugs locally through the skin and the tympanic membrane. Briefly, dexamethasone (DEX)-loaded poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) fiber meshes were decorated with rhodamine (RHO)-loaded poly(lactic-co-glycolic acid) (PLGA) NPs, with RHO representing as a second drug model. By properly tuning the working parameters of electrospinning, DEX-loaded PHBHV fibers (i.e., by electrospinning mode) and RHO-loaded PLGA NPs (i.e., by electrospray mode) were successfully prepared and straightforwardly assembled to form a TDDS patch, which was characterized via Fourier transform infrared spectroscopy and dynamometry. The patch was then tested in vitro using human dermal fibroblasts (HDFs). The incorporation of DEX significantly reduced the fiber mesh stiffness. In vitro tests showed that HDFs were viable for 8 days in contact with drug-loaded samples, and significant signs of cytotoxicity were not highlighted. Finally, thanks to a beaded structure of the fibers, a controlled release of DEX from the electrospun patch was obtained over 4 weeks, which may accomplish the therapeutic objective of a local, sustained and prolonged anti-inflammatory action of a TDDS, as is requested in chronic inflammatory conditions, and other pathological conditions, such as in sudden sensorineural hearing loss treatment. [ABSTRACT FROM AUTHOR]

In this study, aiming to improve the mechanical performance of the Poly (lactic acid) (PLA)-based nanofibrous structures, the electrospinning method was employed to develop twisted yarns with core-shell structure. Within this process, a conventional ring-spun cotton yarn fed to the electrical field, where nanofibers covered it by a certain orientation owning to the twisting procedure. This approach combines the excellent biological and physical-mechanical properties of cotton with outstanding features of the PLA nanofibers for biomedical applications. The effects of the core and shell structures on the ultimate properties of the electrospun core-shell yarns were investigated. Scanning electron microscopy (SEM) demonstrated that relatively uniform and bead-free fibers with smooth surfaces were formed. SEM images also confirmed that the nanofibers were arranged around the core with a specific angle to the axis (with the angle range of 8–44 based on the twisting rate) to constitute a twisted core-shell yarn. The diameter of the electrospun yarns decreased (∼ 22%) by increasing the twist rate. The influence of the core on the mechanical behavior of core-shell yarn are also discussed. Improvements in mechanical performance of core-shell yarns were generally perceived at low twist levels of the core yarn (αe = 2.8), and electrospun shell (40 rpm). Graphical Abstract [ABSTRACT FROM AUTHOR]

Poly(lactic acid)(PLA) is an aliphatic polyester that can be derived from natural and renewable resources. Owing to favorable features, such as biocompatibility, biodegradability, good thermal and mechanical performance, and processability, PLA has been considered as one of the most promising biopolymers for biomedical applications. Particularly, electrospun PLA nanofibers with distinguishing characteristics, such as similarity to the extracellular matrix, large specific surface area and high porosity with small pore size and tunable mechanical properties for diverse applications, have recently given rise to advanced spillovers in the medical area. A variety of PLA-based nanofibrous structures have been explored for biomedical purposes, such as wound dressing, drug delivery systems, and tissue engineering scaffolds. This review highlights the recent advances in electrospinning of PLA-based structures for biomedical applications. It also gives a comprehensive discussion about the promising approaches suggested for optimizing the electrospun PLA nanofibrous structures towards the design of specific medical devices with appropriate physical, mechanical and biological functions. [ABSTRACT FROM AUTHOR]

Core‐shell‐structured polyvinyl alcohol (PVA)‐poly (lactic acid) (PLA) nanofibers combining the hydrophilic trait of PVA and the biocompatibility of PLA were produced using coaxial electrospinning. This allowed the incorporation of AgNO3 in the PVA core of the distinct fibers as shown through transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) showed relatively uniform and bead‐free fibers with smooth surfaces. Ag‐containing fibers show significantly decreased diameters compared with Ag‐free samples as a result of the increased conductivity of the spinning solutions with increasing amounts of AgNO3. In a postsynthetic treatment, the AgNO3 was reduced forming silver nanoparticles (Ag NPs). Ag NPs of 45 to 90 nm size were located in the PVA core but also on the surface of the core‐shell fibers and as individual, agglomerated, and polymer‐coated particles of 100‐200 nm. Powder X‐ray diffraction (PXRD), energy dispersive X‐ray spectroscopy (EDX), and UV‐vis absorption spectroscopy confirmed the increasing amounts of Ag in the core‐shell fibers when using increasing amounts of AgNO3 in the spinning solutions. The antibacterial activity of the nanofiber mats against two prokaryotes Escherichia coli (Gram‐negative) and Staphylococcus aureus (Gram‐positive) increased with increasing amounts of Ag, as expected and produces inhibition zones of 1 to 2 mm. [ABSTRACT FROM AUTHOR]

The stereocomplex formation is a promising method to improve the properties of poly(lactide) (PLA)-based products due to the strong interaction of the side-by-side arrangement of the molecular chains. Recently, electrospinning method has been applied to prepare PLA stereocomplex, which is more convenient. The objective of the current study is to make stereocomplexed PLA nanofibers using electrospinning method and compare their properties and structures with pure poly(l-lactide) (PLLA) fibers. The stereocomplexed fibers were electrospun from a blend solution of high molecular weight PLLA and poly(d-lactide) (1:1 ratio). The morphology of the obtained electrospun fibers was examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Differential scanning calorimetry was applied to study their thermal properties and crystallinity. Fourier transform infrared spectroscopy (FTIR) test was conducted on the samples to characterize their chemical properties. The SEM and AFM images indicated that smooth uniform fibers with a cylindrical structure were produced. Besides, the FTIR results and thermal properties confirmed that only stereocomplex crystallites formed in the resulting fibers via the electrospinning method. [ABSTRACT FROM AUTHOR]

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Twisted nylon 6 nanofibre yarns containing microencapsulated phase change materials (MPCMs) were fabricated via electrospinning to prepare thermal regulating nanofibre yarns. Electrospun nanofibre yarns with different contents of MPCMs including 0.375, 0.75, 1.5 and 3 wt% were prepared. The surface morphology, crystallisation and thermal properties of the yarn samples were characterised by scanning electron microscopy (SEM) and differential scanning calorimetry, respectively. SEM results showed that electrospun composite fibres and yarns had good morphology with smooth surface and the MPCMs were randomly distributed on the composite yarn surface, inside the nanofibres and between the fibres in the yarn structure. Additionally, the SEM results suggested that the average diameters of nylon 6/MPCM nanofibres decreased from 0.23 ± 0.03 µm for neat nylon 6 to a minimum of 0.10 ± 0.02 µm for composite yarn containing 3 wt% MPCM. However, nylon 6/MPCM nanofibre yarn diameter displayed a complex behaviour; the average diameters of electrospun composite yarns increased upon addition of MPCM and reached a maximum value of 165.1 ± 5.11 µm for composite yarn containing 0.75 wt% MPCM, then decreased markedly. These changes in nylon 6/MPCM nanofibres and yarn diameters have been discussed in terms of electrospinning solution properties and twist parameter. The melting enthalpy values of MPCM in the composite nanofibre yarns increased as the content of MPCMs increased up to the highest content and higher than 80% of the heat storage capacity of MPCMs was retained after electrospinning. [ABSTRACT FROM AUTHOR]

ABSTRACT Poly ( l-lactide) (PLLA) fibrous yarns were prepared by electrospinning of polymer solutions in 2,2,2-trifluoroethanol. Applying spinning from two oppositely charged needles the spontaneous formed triangle of fibers at a grounded substrate could be assembled into fibrous yarns using a device consisting of a take-up roller and twister. The effect of processing parameters on the morphology, diameter and mechanical properties of PLLA yarns was investigated by the response surface methodology (RSM). This method allowed evaluating a quantitative relationship between polymer concentration, voltage, take-up rate and distance between the needles' center and the take-up unit on the properties of the electrospun fibers and yarns. It was found that at increasing concentrations up to 9 wt % uniform fibers were obtained with increasing mean diameters. Conversely, the fiber diameter decreased slightly when the applied voltage was increased. The take-up rate had a significant influence on the yarn diameter, which increased as the take-up rate decreased. The tensile strength and modulus of the yarns were correlated with these variables and it was found that the polymer concentration had the largest influence on the mechanical properties of the yarns. By applying the RSM, it was possible to obtain a relationship between processing parameters which are important in the fabrication of electrospun yarns. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41388. [ABSTRACT FROM AUTHOR]

The environmental safe treatment methods were used to improve the penetrability of wool fibers with natural dye (Madder) in the presence of chemical and physical modified natural soybean lecithin. The dyeing conditions of wool fiber with madder were optimized by response surface methodology (RSM). The five independent variables were selected at low and high level values. The ANOVA results of the quadratic model show that the model terms such as dyeing temperature, dyeing time, lecithin concentration, plasma treatment duration, dyeing method, and their interactions are significant. Moreover, the optimum conditions which were proposed for the natural dyeing of LTP-treated wool fibers cause dyeing temperature reach to 76.53°C in the presence of acetylated lecithin. [ABSTRACT FROM AUTHOR]

This study attempts to investigate the pressure behavior of tubular knitted fabrics after a long period of time. For this purpose, two kinds of knitted fabric (plain and interlock) with various stitch lengths were chosen and the interfacial pressure and pressure reduction of fabrics after 48 hours were analyzed at different strain percents. The same tests were performed on the same specimens after repeated washing and repeated usage. Finally, the experimental pressure values were compared with the theoretical results obtained from Laplace's law. The results reveal that the stitch length and strain percent are important factors affecting the interfacial pressure and pressure reduction of both plain and interlock fabrics. As the results of statistical analysis, the repeated washing and repeated usage have significant effect on interfacial pressure and pressure reduction of both fabrics. The comparison between experimental pressure values and theoretical values calculated from Laplace's law shows a considerable difference in both plain and interlock fabrics. [ABSTRACT FROM AUTHOR]

Being designated to protect other tissues, skin is the first and largest human body organ to be injured and for this reason, it is accredited with a high capacity for self-repairing. However, in the case of profound lesions or large surface loss, the natural wound healing process may be ineffective or insufficient, leading to detrimental and painful conditions that require repair adjuvants and tissue substitutes. In addition to the conventional wound care options, biodegradable polymers, both synthetic and biologic origin, are gaining increased importance for their high biocompatibility, biodegradation, and bioactive properties, such as antimicrobial, immunomodulatory, cell proliferative, and angiogenic. To create a microenvironment suitable for the healing process, a key property is the ability of a polymer to be spun into submicrometric fibers (e.g., via electrospinning), since they mimic the fibrous extracellular matrix and can support neo- tissue growth. A number of biodegradable polymers used in the biomedical sector comply with the definition of bio-based polymers (known also as biopolymers), which are recently being used in other industrial sectors for reducing the material and energy impact on the environment, as they are derived from renewable biological resources. In this review, after a description of the fundamental concepts of wound healing, with emphasis on advanced wound dressings, the recent developments of bio-based natural and synthetic electrospun structures for efficient wound healing applications are highlighted and discussed. This review aims to improve awareness on the use of bio-based polymers in medical devices. [ABSTRACT FROM AUTHOR]

The keratin macromolecule in wool fiber may be found in α-helix or β-sheet conformations besides a disordered portion. The physical and chemical treatments may cause transformations between α-helix and β-sheet conformations. The aim of this study was to investigate the influence of lecithin treatment on the wool fiber using the micro-Raman spectroscopy and Fourier transform infrared spectroscopy. Characteristic bands found in the FTIR spectra of wool fibers including the amide A, amide B and amide I–III, which are assigned to the peptide bonds of wool keratin and arise from the amide bonds that link the amino acids. The lecithin treatment didn’t affect the peak position of amide bands and only slightly influenced their intensity. It means that the lecithin treatment didn’t change the chemical structure of wool fibers. The amide I and III regions, C C skeletal vibration region, and S S bonds vibration regions were analyzed with the Raman microscope. The results indicated the peak area of α-conformation increased gradually by lecithin treatment of the wool fiber, while the peak area of β-conformation decreased. Therefore, it seems that lecithin treatment of the wool fiber resulted in transformation of β-sheet to α-helix. [ABSTRACT FROM AUTHOR]