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Open Access Article
1 - DFT comparison of structural and electronic properties of (5, 0) zig-zag GaAs nanotube and (5, 0) zig-zag GaSb nanotube
Monir KamalianAbstract. The structural, electronic and transport properties of the (5, 0) zig-zagGaAs nanotube and (5, 0) zig-zag GaSb nanotube have been studied by usingDensity Functional Theory (DFT) combined with Non-Equilibrium Green’s Function(NEGF) formalism with TranSIES MoreAbstract. The structural, electronic and transport properties of the (5, 0) zig-zagGaAs nanotube and (5, 0) zig-zag GaSb nanotube have been studied by usingDensity Functional Theory (DFT) combined with Non-Equilibrium Green’s Function(NEGF) formalism with TranSIESTA software. The electronic band structure (EBS),density of states (DOS), band gap (BG), current-voltage (I-V) characteristics andquantum conductance curves (dI/dV) of these two structures were studied underlow-bias conditions. The obtained results demonstrate that these two structuresexhibit semiconducting behavior, but the (5, 0) zig-zag GaSb nanotube has asmaller band gap and the highest value of the electron density of states, henceit is an important candidate in the field of infrared-radiation detectors, resonanttunnelling devices and laser diodes. Instead the (5, 0) zig-zag GaAs nanotubeshowed the amazing property of Negative Differential Resistance (NDR) that it hasplayed a vital role in high frequency oscillators, reflection amplifiers, memoriesand switching devices. Manuscript profile -
Open Access Article
2 - The effect of slope and number of arms on the structural properties of square tower-like manganese thin films
Mahsa FakharpourIn this work, square tower-like manganese (STMn) thin films on glass substrates using were obtained using Glancing Angle Deposition “GLAD” technique. Three types of nanostructures are prepared with different number of arms and different slopes by placing a s MoreIn this work, square tower-like manganese (STMn) thin films on glass substrates using were obtained using Glancing Angle Deposition “GLAD” technique. Three types of nanostructures are prepared with different number of arms and different slopes by placing a shadowing block in the center of the substrate holder. The structural characterization of the obtained thin films was investigated using field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). Results showed that the slope angle (a), the grain size, porosity and surface roughness of the films decreases with increasing distance from the edge of the shadowing block (decreasing the slope of nanostructure). Structural properties of thin films were obtained using X-ray diffraction (XRD). The intensity of the main peak of STMn with 8 arms and 10 arms increases and STMn with 9 arms decreases with increasing the edge of the shadowing block. The results show that the strain on the nanostructures of the STMn with 8 arms and STMn with 10 arms decreases with increasing distance from the edge of the shadowing block due to the increase in the intensity of the main peak. While strain on the nanostructure of the STMn with 9 arms increases with increasing distance from the edge of the shadowing block. Manuscript profile -
Open Access Article
3 - Macro-and micromechanical modelling of HA-Elastin scaffold fabricated using freeze drying technique
Matin Mohammadzadeh Rad Saeed Saber-Samandari Mojtaba Sadighi Lobat Tayebi Mohammad Mohammadi Aghdam Amirsalar KhandanSince osteomyelitis is a serious and dangerous disease, it requires immediatetreatment with antibiotics or bone substitute replacement in orthopedic surgeries.Therefore, a porous polymeric-ceramic was fabricated using hydroxyapatite(HA) and polymethylmethacrylate (PMMA) MoreSince osteomyelitis is a serious and dangerous disease, it requires immediatetreatment with antibiotics or bone substitute replacement in orthopedic surgeries.Therefore, a porous polymeric-ceramic was fabricated using hydroxyapatite(HA) and polymethylmethacrylate (PMMA) composed with elastin as an idealscaffold for bone tissue engineering applications. The current study is aimed atinvestigating the effects of various amounts of elastin biopolymer on porous bionanocompositescaffold using the freeze-drying (FD) technique. The morphologyand phase analysis of the prepared scaffold are analyzed using scanning electronmicroscope (SEM) and X-ray diffraction (XRD) techniques. The biologicalperformance of the porous tissue is evaluated in simulated body fluid (SBF) andsodium chloride (SC) solution. The tensile test is used to measure the elasticmodulus and tensile strength of the porous tissue before soaking in the SBF. Theobtained result is simulated using micromechanical model from the experimentalvalues. The elastic modulus of samples decreases from 1.18 MPa to 0.69 MPa,and porosity evaluation is in the range of 70-85% with addition of 10 wt% and 15wt% elastin to PMMA-HA bio-nanocomposite. The biological behavior indicatesthat a thick apatite layer precipitate on the surface of the sample with 10 wt%elastin beside increases alkaline group with constant pH concentration. Accordingto the obtained porosity and elastic modulus results, suitable micromechanicalmodel is assessed. The comparison of micromechanical model is assessed, anderror rate was less than 10%; therefore, optimum model is introduced as the bestmicromechanical model for porous bone substitute. Manuscript profile -
Open Access Article
4 - Investigation of removal efficiency of Cr (VI) from industrial wastewater using chitosan and synthesized chitosan nanoparticles
arezou ghadi Soleiman Mahjoub Mohsen ziyariChromium (VI) is present in the effluents from different industries which maycause serious environmental problems. The aim of this study was to synthesis ofchitosan nanoparticles and their comparison with chitosan for removal of Cr (VI)ions from industrial waste water. MoreChromium (VI) is present in the effluents from different industries which maycause serious environmental problems. The aim of this study was to synthesis ofchitosan nanoparticles and their comparison with chitosan for removal of Cr (VI)ions from industrial waste water. The Synthesizing of the nanoparticle adsorbentswas successfully done by the crosslinking method. The nanoparticles sizes weredetermined between the ranges of 50-100 nm. The effect of the pH solution,adsorbents dosage, initial concentration of chromium ion and contact timefor the absorption of Cr (VI) were investigated by means of atomic absorptionspectroscopy. Maximum adsorption of chitosan nanoparticles and chitosan were44 & 16 mg/g, respectively (p <0.001). The optimum conditions for removal ofCr (VI) were determined to be pH=5 for nanochitosan solution, 1gr/L of theinitial concentration of metal ion, adsorbents dosage of 0.125 g/L and the3-hour contact time. The results showed that nanochitosan possesses a higherabsorption capacity for Cr (VI) compared to the chitosan, which related to theincrease in the nanochitosan effective surface. Manuscript profile -
Open Access Article
5 - Experimental Investigation of Fe3O4-Chitosan Nanocomposite as a Nano-Demulsifier for Water in Crude Oil Separation
Z. Hasanshahi P. Parvasi M. M. Zerafat Samad SabbaghiNowadays chemical and electrostatic demulsification techniques are typically usedto separate water-in-crude-oil emulsions. The need to improve demulsificationtechniques has led to the use of various additives among which nanoparticleshave emerged as a novel alternative. MoreNowadays chemical and electrostatic demulsification techniques are typically usedto separate water-in-crude-oil emulsions. The need to improve demulsificationtechniques has led to the use of various additives among which nanoparticleshave emerged as a novel alternative. Most of the exploited crude oil exists in anemulsion state, where may cause serious problems during processing. Chemicaldemulsifiers, bottle tests, and electrostatic desalters are commonly used toseparate water from crude oil emulsions but there are some issues involved withthese methods. Therefore, using new technologies like nanotechnology can help improve the desalting process. First, Fe3O4 and Fe3O4-chitosan nanocompositewere synthesized via co-precipitation method. Fe3O4-chitosan nanoparticles werecharacterized by X-ray diffraction and Fourier transform infrared spectroscopy.The results showed that ultrafine Fe3O4 nanoparticles were prepared and coatedby chitosan. In this study, Fe3O4 and Fe3O4-chitosan nanocomposite were utilizedto improve emulsion destabilization. The effect of different parameters on theseparation performance was studied and the best conditions were determined.The results showed that the application of certain nanostructures in crude oilemulsions improves the performance of demulsification up to 86% and decreasesthe amount of demulsifier consumption in the desalting process. Manuscript profile -
Open Access Article
6 - Stress-strain behavior of two-layer graphene with different chirality
Mohsen Motamedi A.H. AghiliGraphene is a two-dimensional sheet containing carbon atoms arranged as ahoneycomb lattice. Graphene has been recently the subject of much interest dueto its unique mechanical, thermal, and electrical properties. The experimentalmethod for calculating the mechanical pro MoreGraphene is a two-dimensional sheet containing carbon atoms arranged as ahoneycomb lattice. Graphene has been recently the subject of much interest dueto its unique mechanical, thermal, and electrical properties. The experimentalmethod for calculating the mechanical properties of graphene is complexbecause of its nanoscale lateral dimension, so the use of the theoretical methodfor calculating the properties of monolayer graphene has also received muchattention recently.In this study, two-layer graphene with two different chirality angles was modeledby molecular dynamics in LAMMPS software. In summary, this research involvesproducing the primary structure, balancing the sample, applying the axial tensiletest, and extracting the stress-strain graph from the sample. The simulatedgraphene has a value of 102.2*100.8 Å and an interlayer distance is 3.4 Å.The results showed that as the number of sheets increased, the amount ofYoung's modulus was more than that of the single-layer graphene. In addition,the fracture strength of the two-layer armchair graphene is greater than thefracture strength of the two-layer zigzag graphene. Then, by increasing thechirality angle, the fracture strength decreases. Finally, it was shown that byincreasing the chirality angle in two-layer graphene from 0 ° (armchair) to 30 °(zigzag), the Young's modulus value increases, while by increasing the chiralityangle in single-layer graphene from 0 ° to 30 °, the Young's modulus does notchange significantly Manuscript profile -
Open Access Article
7 - Mechanical properties improvement and bone regeneration of calcium phosphate bone cement, Polymethyl methacrylate and glass ionomer
Rezvan Fada Niusha Farhadi Babadi Reyhaneh Azimi Majid Karimian mohamad shahgholiAdvancement in nanoscience and biotechnology of bone materials and cement hasbeen increasing over the past several decades. The combination of biomaterialswith trace elements for bone cement has verified their better mechanical strengthand biocompatibility response. Als MoreAdvancement in nanoscience and biotechnology of bone materials and cement hasbeen increasing over the past several decades. The combination of biomaterialswith trace elements for bone cement has verified their better mechanical strengthand biocompatibility response. Also, the ionic replacement has affected thechemical, physical and biological properties of the substance. Pyrophosphate hassupported better absorption of calcium phosphates (CaPs) and bone formation.Bone cement is the ionomer of an important material in tooth repair applicationused in the tooth filling, tooth cover, and to fix adhesions of the tooth and crown.Nanoparticle additives (magnesium oxide (MgO), hydroxyapatite (HA), chitosan(CH), barium sulfate and silica) and alternate monomers can be effective withPolymethyl methacrylate (PMMA) granules and methyl methacrylate monomers(MMAs) to decrease the isothermal temperature. These materials can be used forthe growth and development of bone cements. This paper aims to demonstratea general and different view of the applications of CaP, PMMA, glass ionomer andbone repair cements in various methods under different experiments procedure Manuscript profile -
Open Access Article
8 - Investigation of the stability of PEG stearate-coated Chitosan nanoparticles loaded with levothyroxine
Elham RostamiWe report the formation and characterization of PEG stearate (PEG)-coatedChitosan (CS) nanoparticles. Chitosan nanoparticles were synthesized usingtripolyphosphate (TPP) via the ionic crosslinking method. Preparation of PEGStearate-grafted Chitosan is essential to impro MoreWe report the formation and characterization of PEG stearate (PEG)-coatedChitosan (CS) nanoparticles. Chitosan nanoparticles were synthesized usingtripolyphosphate (TPP) via the ionic crosslinking method. Preparation of PEGStearate-grafted Chitosan is essential to improve the biocompatibility and watersolubility of Chitosan. The size and morphologies of Chitosan nanoparticleswere measured with transmission electron microscopy and scanning electronmicroscopy. Sizes of Chitosan nanoparticles were in the range of 150-200nm. The particle size and zeta potential of PEG Stearate-coated Chitosanhad been measured at 187.5 nm by Photon Correlation Spectroscopy (PCS).Drug entrapment efficiency (EE) was obtained to be 99%. The purpose of thepresent work was to develop a new nanoparticle system, consisting of polymericnanoparticles coated with PEG Stearate. The modification procedure led to areduction in the zeta potential values, varying from +43.3 mV for the uncoatedparticles to +20 mV for that of PEG Stearate-coated Chitosan. PEG Stearatecoated nanoparticles were more stable due to their polymer coating layer whichprevented aggregation of Chitosan nanoparticles. Consequently, it is possible thatthe PEG Stearate surrounds the particles reducing the attachment of enzymesand further degradation of the polymeric cores. Properties nanoparticles wereaffected by the preparation variables and the coating layer. Chitosan nanoparticlesshowed a smooth surface and globular shape. In this study, we explored therelease behavior of levothyroxine was affected by the coating layer. Coatingsurface leads to a decrease in the burst release effect compared to uncoatednanoparticle due to gradual release of adsorbed levothyroxine from PEG coatedChitosan nanoparticles. Manuscript profile
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