جستجوی مقالات مرتبط با کلیدواژه « نانو الیاف » در نشریات گروه « مواد و متالورژی »

The human body process can spontaneously repair small bone defects, while large bone defects cannot be repaired without medical interventions. Efforts to eliminate these shortcomings have led to the foundation of bone tissue engineering. In this research, polycaprolactone/keratin scaffold and Polycaprolactone/keratin/hydroxyapatite scaffold were fabricated using electrospinning method and were evaluated. Then, in order to evaluate the cellular differentiation, adipose tissue-derived mesenchymal stem cells were cultured on scaffolds and the process of differentiation of mesenchymal stem cells into bone cells for 7 and 14 days was investigated by alkaline phosphatase and alizarin red test. Increase of the activity of the enzyme alkaline phosphatase, the presence of the minerals and the red-orange-color extended on the scaffolds containing hydroxyapatite nanoparticles that confirmed the presence of Ca + 2 , demonstrated the differentiation of mesenchymal cells into bone cells. Therefore, the results of this study suggest that the polycaprolactone/keratin/hydroxyapatite scaffold is a suitable substrate for proliferation and differentiation of stem cells for bone tissue engineering.

Industrial wastewater treatment and recycling the treated water are drawn to attention. In this study, the removal of heavy metal cations (e.g. Cu, Ni, Co) as an important pollutants, has been investigated by applying the Nylon6/zirconia nano-composite absorbent. Nano-composite membranes containing different amount of zirconia nano-particles (NPs) were synthesized via electrospinning method. To study the microstructure and functional molecule groups of nano-absorbent, SEM and FTIR techniques were used, respectively. The results showed that the average diameter size of fibers and surface porosity decreased from 387 to 105 nm and 83.1 to 65.6 % with increasing the zirconia content, respectively. Furthermore, zirconia NPs were distributed heterogeneously and also electrospinning defects such as zirconia agglomerates were observed in the mat. Adding the zirconia NPs did not affect the functional molecule groups of Nylon6. According to the homogenous distribution and also creation of active sites by zirconia NPs, the ratio of zirconia to Nylon6 equals to 0.88 (g/g) was selected as the optimized composition. Water contact angle variations on the surface of nano- absorbent indicated that the mentioned surface had hydrophobic behavior at the beginning time of contact and then it switched to the hydrophilic manner. Kinetic study on the adsorption of heavy metal cations showed that it was followed by first-pseudo order model. The maximum adsorption was recorded 9.6, 8.7 and 4.8 mg/cm2 respect to the Cu, Ni, and Co cations. It suggests that the Nylon6/zirconia nano-composite has high efficiency to adsorb heavy metal pollutants. Eventually, the water recycling will be achieved by development of polymer-ceramic nano-composite.

Considering the importance of nanotechnology, especially nanofibers and nanocomposites ; as its most eligible products and the vast applications of polyvinyl alcohol (PVA) and nanoclay ( modified organo-clay), the main objective of this work was study on effect of polymer blends (PVA as matrix) and nano-filler ( organo-clay as disperse phase) concentrations and electrospinning parameters , on morphology of resulted nanocomposite nanofibers. It is noteworthy that bead less nanofibers with even diameter distributions can make the final products application more valuable. In order to investigate the microstructure and morphology and the miscibility and chemical bonding of polyvinyl alcohol / organo-clay nanocomposite nanofibers , the scanning election microscope (SEM), and the Fourier transform infrared spectrometer (FTIR) were used , respectively. Also, the thermal gravimetric analysis (TGA) was employed to investigate thermal behavior of nanocomposite nanofiber samples. The X-Ray Diffraction (XRD) data demonstrated the exfoliation of organo-clay layers in poly vinylalcohol matrix and nanofibers nanocomposite were electrospun with diameter about 300 nm.

In this study, the polyacryliamodoxime (PAAO) powder was synthesized by treating the polyacrylonitrile (PAN) powder through chemical procedures, and used to hydrolyze the simulated nerve agent, i.e., dimethoate. GC-MS spectroscopy technique demonstrated the ability of PAAO powder to hydrolysis over 95% of dimethoate pesticide within 12 hours. Since the properties of substances in nano scale are improved, it was planned to synthesize PAAO nano fibers via two (i) conversion of PAN powder to PAAO powder and preparing its nanofiber; (ii) preparation of PAAO nanofibers from PAN nanofibers. Successful operation of the amidoximation was confirmed by FTIR technique. Thermal behavior of PAN and PAAO powders were investigated by thermogravimetric analyzer (TGA). SEM technique was used to study the morphology of PAAO nanofibers. SEM images revealed that PAAO nanofibers is uniform and bead-less, hence, it could be used as a coating for self–decontamination procedure.

In this study Nanofibers of polycaprolactam (Nylon 6) /zinc doped hydroxyapatite (HAP) were synthesized via electrospinning method. Hydroxyapatite nanoparticles containing 4 at % zinc were synthesized via chemical precipitation method. XRD and FTIR of the synthesized powders indicated that non-stoichiometric and single phase hydroxyapatite was formed. The results also showed that Zn cations have been incorporated in atomic structure of HAP. The average of particle size and crystallite were calculated 43 and 16 nm respectively. Polymeric solution was prepared throughout dissolving of 20 wt% polycaprolactam in formic acid. To synthesize the composite nonofibers، 2 wt% of synthesized ceramic powders were added to polymeric solution. Influence of voltage (15-30 kV) and flow rate (0. 1-0. 5 ml. h-1) on diameter and morphology of nanofibers were investigated. The results of SEM images showed that fibers with average diameter of 100-300 nm were formed، and also zinc doped hydroxyapatite particles were homogenously distributed between nano fibers. The results indicated that increasing of the applied voltage over 30 kV caused to romaine ticker fibers as ribbon shaped. Results also showed that the average of fiber diameter increased with decreasing the flow rate resulting in heterogeneous distribution of HAp nanoparticles. The agrigate of Zn doped HAP was formed separately when the flow rate was set to 0. 1 ml. h-1.