Papers by Azizollah shafiekhani
The effect of coated diamond-like carbon thin films on polymer tooth based denture: Micro-morphology and fractal feature studies
AIP Advances, Apr 1, 2023
To consider improving the micromorphology study of dentures combined with biocompatibility in rec... more To consider improving the micromorphology study of dentures combined with biocompatibility in recent years, we study hybrid organic–inorganic materials and diamond-like carbon coated on tooth-based dentures by the sol–gel and the RF sputtering method, respectively. Afterward, the effect of such material coating on the surface roughness and surface topography of dentures was evaluated. Aimed at this, 3D atomic force microscope images were analyzed via MountainsMap® Premium software, which divided the surface into peaks and pits through the watershed segmentation algorithm. This method made motif analysis possible by detecting the surface dimensions, curvature, volume, perimeters, shape, structure, etc., and the obtained statistics indicate interesting results for the regular and irregular topography and the surface of the prepared samples. In addition, the energy-dispersive x-ray spectrum illustrates the existence of N, C, O, Na, and Si in all samples, with the maximum value of C in the diamond-like carbon coated sample, which is because of the highest value of carbon in diamond-like carbon. Scanning electron microscope images also present a series of grooves on the surface with small randomly oriented cracks. The linear interpolation type shows that the surface of diamond-like carbon coated on the hybrid-control sample has the most irregular topography while the most regular topography was found in the hybrid coated control sample.
Magnetite nanoparticles embedded on reduced graphene oxide as an anode material for high capacity and long cycle-life Li-ion battery
Journal of energy storage, Nov 1, 2023
arXiv (Cornell University), Mar 31, 1997
Using a unified and systematic scheme, the free field realization of irreducible representations ... more Using a unified and systematic scheme, the free field realization of irreducible representations of $osp(2|2)$ is constructed. The $q$-analogy of this unified scheme is used to construct $q$-free field realization of irreducible representations of $U_q(osp(2|2)$. By using these realization, the correlation functions of $N=2$ super-conformal (q-super-conformal) models based on $os(2|2)$ ($U_q(osp(2|2))$ symmetry and free field representation of ${\widehat{osp(2|2)}}$ currents are calculated. Free field representation of KM currents are used to determine the stress-energy tensor and central charge of the model.
Surface dynamics, fractal features, and micromorphology analysis of kefir biofilms
Microscopy Research and Technique, Jan 19, 2022
We introduce a study of image analysis of kefir biofilms associated with Acai extract prepared by... more We introduce a study of image analysis of kefir biofilms associated with Acai extract prepared by fermentation of fresh kefir grains natural. Atomic force microscopy data were studied, aiming to understand how the concentration of acai berry (Euterpe oleracea Mart.) influences the surface morphology as well as the texture complexity, evaluated by the fractal dimension. The results showed that the superficial morphology was affected by the increase of Acai concentration in the biofilms, as well as the fractal dimension. It has also been observed that the surface of the biofilm presented saturation when concentration changes from 40 to 60 ml. On the other hand, it was observed that the intermediate sample produced with 20 ml of acai berry seems to be the best point for biofilms production that can serve as a skin dressing since other studies related to mechanical properties and in vitro and in vivo tests can confirm this applicability. Thus, the characterization of the surface morphology of kefir biofilms by the evaluation of surface statistical parameters and fractal geometry may provide promising results regarding the applicability of these films.
Optical Materials, Apr 1, 2007
A new polymeric-inorganic cation exchanger acrylonitrile stannic(IV) tungstate composite was synt... more A new polymeric-inorganic cation exchanger acrylonitrile stannic(IV) tungstate composite was synthesized by sol-gel technique by incorporating stannic(IV) tungstate precipitate with acrylonitrile. Composite materials formed by the combination of inorganic ion exchangers of multivalent metal acid salts and organic polymers (acrylonitrile, cellulose acetate, polyaniline, polypyrrole, polythiophene, etc.), providing a new class of 'organic-inorganic' composite exchangers with better mechanical and granulometric properties, good ion exchange capacity, higher stability, reproducibility and selectivity for heavy metals. The physico-chemical characterization was carried out by elemental analysis, TGA, SEM, XRD, FTIR and TEM studies. Ion exchange capacity, pH titrations, elution and distribution behavior were also carried out to understand the ion exchange behavior of the material. The adsorption behavior of heavy metal ions has been reported in nitric acid and two surfactants media by batch processes. The analytical applications of the material have been explored by achieving some analytically important binary separations from aqueous solution on its columns. The practical applicability of acrylonitrile stannic(IV) tungstate was demonstrated in the quantitative separation of Fe 3+ and Zn 2+ contents of a commercially available pharmaceutical sample namely Fefol-Z.
arXiv (Cornell University), May 30, 2020
The current rechargeable battery technologies have a failure in their performance at high pressur... more The current rechargeable battery technologies have a failure in their performance at high pressure and temperature. In this article, we have brought theoretical insights on using boron nitride flakes as a protecting layer for a lithium-ion battery device and extended its application for a spin-dependent photon emission device. Hence, the electronic properties of pristine and lithiumdoped hydrogen-edged boron nitride flakes have been studied by the first principle density functional theory calculations. In this study, we have discussed the stability, adsorption energies, bond lengths, electronic gaps, frontier molecular orbitals, the density of states, charge distributions, and dipole moments of pristine and lithium hydrogen-edged doped boron nitride flakes.
Journal of theoretical and applied physics, Jun 1, 2018
In this paper, due to the importance and abundant applications of carbon nanotubes doped with bor... more In this paper, due to the importance and abundant applications of carbon nanotubes doped with boron (CNT/B 2 O 3) in various industries with changes in the electrical, mechanical and chemical properties, mode identification and intensity of the Raman spectra of pure and boron oxide molecule-doped spectra have been performed. The main task in this paper is to monitor the alteration of the relevant vibrational mode intensities of the pure and B-doped samples. In experimental approach, by utilizing a simple method we synthesized CNT doped with B 2 O 3 using laser ablation in liquid environment technique. The silver nanoparticles were made by the Lee-Meisel method, and then the spontaneous and surface-enhanced Raman scattering (SERS) spectra of pure and B-doped carbon nanotubes were collected. In simulation approach, using the Gauss View and Gaussian software [basis set 6-31G, computational method DFT (B3LYP)], the spontaneous and SERS spectroscopy of pure and B-doped carbon nanotubes was calculated. Due to the presence of silver nanoparticles in the vicinity of carbon nanotube and boron element, SERS intensity to spontaneous Raman (NR) intensity ratio I SERS = I NR increases in the D, G and boron oxide modes of up to 12-fold were observed. A good agreement is found between the computational and the experimental SERS results for the vibrational spectra of the synthesized composite materials.
Evaluating structural, morphological, and multifractal aspects of n‐ZnO/p‐ZnO homojunctions and n‐ZnO/p‐NiO heterojunctions
Microscopy Research and Technique
We have investigated the evolution of the structure and surface morphology of n‐ZnO/p‐ZnO homojun... more We have investigated the evolution of the structure and surface morphology of n‐ZnO/p‐ZnO homojunctions and n‐ZnO/p‐NiO heterojunctions transparent structures deposited by radio frequency‐sputtering on quartz (Q)/ITO substrates. X‐ray diffraction (XRD) analysis of the as‐deposited and annealed ZnO, n‐ZnO/p‐NiO/Q/ITO, and n‐ZnO/p‐ZnO/Q/ITO thin films showed that ZnO had a wurtzite hexagonal structure and (002) preferred growth direction. The annealing temperature played a key role in improving the crystalline structure of the films, as evidenced by the changes in the intensity and position of the XRD (002) peak. Morphological analysis revealed that the roughness of the film varies with increasing annealing temperature. Particle size dictates the vertical growth of p‐ZnO homojunctions, while particle shape dictated the p‐NiO heterojunctions growth. Fractal analysis showed that p‐ZnO homojunctions have similar spatial complexity, surface percolation, and topographical uniformity and ar...
Surface dynamics, fractal features, and micromorphology analysis of kefir biofilms
Microscopy Research and Technique, 2022
We introduce a study of image analysis of kefir biofilms associated with Acai extract prepared by... more We introduce a study of image analysis of kefir biofilms associated with Acai extract prepared by fermentation of fresh kefir grains natural. Atomic force microscopy data were studied, aiming to understand how the concentration of acai berry (Euterpe oleracea Mart.) influences the surface morphology as well as the texture complexity, evaluated by the fractal dimension. The results showed that the superficial morphology was affected by the increase of Acai concentration in the biofilms, as well as the fractal dimension. It has also been observed that the surface of the biofilm presented saturation when concentration changes from 40 to 60 ml. On the other hand, it was observed that the intermediate sample produced with 20 ml of acai berry seems to be the best point for biofilms production that can serve as a skin dressing since other studies related to mechanical properties and in vitro and in vivo tests can confirm this applicability. Thus, the characterization of the surface morphology of kefir biofilms by the evaluation of surface statistical parameters and fractal geometry may provide promising results regarding the applicability of these films.
Microstructure and tribological properties of FeNPs@a-CH films by micromorphology analysis and fractal geometry
This paper analyzes the three-dimensional (3D) surface texture of amorphous hydrogenated carbon f... more This paper analyzes the three-dimensional (3D) surface texture of amorphous hydrogenated carbon films with sputtered iron nanoparticles (FeNPs@a-C:H) deposited by a radio-frequency plasma-enhanced chemical vapor deposition method on the quartz substrates. The prepared FeNPs@a-C:H films were used as research materials. The synthesized samples were deposited at four different pressures of 2.5, 3, 3.35, and 3.5 N/m2 in an acetylene gas atmosphere. The Fe and C contents of the thin films were obtained from X-ray photoelectron spectroscopy. The X-ray diffraction profile and electron diffraction pattern indicate that iron nanoparticles with body-centered-cubic crystalline structure are formed in these films. The localized surface plasmon resonance peak that is the signature of the existence of the iron core nanoparticles appears in visible spectra of these films. The sample surface images were recorded using an atomic force microscope operating in a noncontact mode and analyzed to reveal ...
ポリアニリンの光学的および電気的特性に及ぼすポリアニリン膜中の多層カーボンナノチューブの含有量の影響【Powered by NICT】
Chinese Physics Letters, 2016
Nanotechnology, 2021
The current rechargeable battery technologies have a failure in their performance at high pressur... more The current rechargeable battery technologies have a failure in their performance at high pressure and temperature. In this article, we have brought theoretical insights on using boron nitride flakes as a protecting layer for a lithium-ion battery device and extended its application for a spin-dependent photon emission device. Hence, the electronic properties of pristine and lithium-doped hydrogen-edged boron nitride flakes have been studied by the first principle density functional theory calculations. In this study, we have discussed the stability, adsorption energies, bond lengths, electronic gaps, frontier molecular orbitals, the density of states, charge distributions, and dipole moments of pristine and lithium hydrogen-edged doped boron nitride flakes.
Atomic force microscopy studies of enamel, inner enamel, dentin, and cementum in canine teeth
Microscopy Research and Technique, 2021
The main goal of the present work is to explore the three dimensional (3‐D) atomic force microsco... more The main goal of the present work is to explore the three dimensional (3‐D) atomic force microscopy (AFM) images of human teeth and investigating their micromorphology. For this purpose, 10 fresh and permanent canine teeth were selected from a group of 40‐year‐old men who were candidate for the experimental processes. Afterward, they were all applied for studying the morphology of their hard tissues. The tapping mode of AFM was used to characterize the surface micromorphology on the square areas of 1 μm × 1 μm (512 × 512 pts). AFM results and surface stereometric analysis indicate the relationships between the micromorphology of the surface and the structural properties of these tissues across the length scales. As can be seen, the surface of cementum has the most irregular topography (D = 2.87 ± 0.01) while the most regular topography (D = 2.43 ± 0.01) is found in dentin. Furthermore, the more and less regularity of the surface have been found in inner enamel (Sq = 26.26 nm) and de...
Comparison of formation of carbon on aluminum and graphite substrates by a low energy plasma focus device
Surfaces and Interfaces, 2021
Abstract Characterization of carbon structure was studied through deposition of carbon films on t... more Abstract Characterization of carbon structure was studied through deposition of carbon films on three different substrates at various angular positions. The thin films were prepared by a low energy plasma focus device and placed on graphite, aluminum, and magnesium substrates. The deposition process performed in presence of an active, as well as a noble gas, namely nitrogen and argon. The synthesis of thin films deposited at lower angular position shows nano-crystalline graphite and amorphous carbon structures. A carbon crystal has been detected for deposition at higher angular positions. The characterization of the crystal was investigated and it was revealed that the deposited thin film has hexagonal crystal structure. Further study of crystal led to the conclusion that it can be categorized under crystalline aromatic network. The surface of all synthesized films containing crystalline aromatic network was yellowish orange color (golden). The characterization of each structure was verified by x-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), nano-indentation, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) analyses. Raman spectroscopy was used as a base analysis to classify carbon structures. Raman parameters of natural graphite structure, such as G peak position and ID/IG ratio, as well as, those of carbon crystal, nano-crystalline graphite, and amorphous carbon were identified.
Density function theory calculations were carried out to clarify storage states of Lithium (Li) i... more Density function theory calculations were carried out to clarify storage states of Lithium (Li) ions in graphene clusters. The total energy, stability, spin polarization, charge distribution, electronic gap, surface curvature and dipole momentum were calculated for each cluster. Li-ion absorbed graphene, doped by one Li atom is spin polarized, so there would be different gaps for different spin polarization in electrons. Calculated results and thermal effects demonstrated that a storage state in the middle rings is preferable so that it could improve graphene Li-ion batteries; consequently, recommended graphene anode structure is proposed.
Electron-transport and gas sensing in armchair graphene nanoribbons by density functional method
Materials Science in Semiconductor Processing
Abstract Findings regarding the application of gas sensing on graphene based material have led to... more Abstract Findings regarding the application of gas sensing on graphene based material have led to jump in nanotechnology. Hence, producing the high-efficiency materials in this technology is a priority. Recent development in graphene based material shows that it can be a good candidate for this tar-get. With this in mind, we theoretically studied the effect of different gas molecule absorption on armchair graphene nanoribbon. In order to identify, the electronic transport of armchair graphene nanoribbons AGNR (8) by using non-equilibrium Green’s function technique, the TRANSIESTA package was used. In order to study the geometry relaxation of device, Spanish Initiative for Electronic Simulations with Thousands of Atoms (SIESTA) package was applied. Also, the generalized gradient approximation of Perdew, Burke and Ernzerhof (PBE) were chosen for the exchange correlation density function. For studying the gas sensing properties of AGNR numerical computations for CO, NO, CO2, and NH3gas molecules were adsorbed on the AGNR (8). Besides, the average local density of states (LDOS) and the transmission spectra T (E, V) for gas molecules adsorbed on the AGNR (8) were plotted. The current was measured as a function of the voltage of applied bias and the transmission spectra was investigated to see the effects of all configurations in the presence of gas molecules. Our results are encouraging and leading experimental research to develop high-quality graphene materials for well-organized applications base on gas sensing.
Free Radical Biology and Medicine, 2018
It is now well established that intracellular reactive oxygen species (ROS) mediate the regulatio... more It is now well established that intracellular reactive oxygen species (ROS) mediate the regulation of many signaling cascades that define cell fate. The delicate balance between the production and elimination of ROS is essential for maintaining normal cell functions. Disruption of this balance caused by the antioxidant treatment can disturb various intracellular processes controlled by the systemic signaling. In the present study, we investigate the response of the mesenchymal stem cells (MSCs) to the sub-cytotoxic treatment with various antioxidants (tempol, NAC, resveratrol, DPI). We show that exposure of the proliferating MSC cultures to the antioxidants at concentrations which are widely used in the cell studies to protect cells from the oxidative stress, can cause replication stress and initiate the program of stress-induced preliminary senescence. We demonstrate that these effects can be explained by the disturbance of the ROS-depended degradation of the key proteins regulating DNA replication, e.g. cyclin A, Emi1, geminin. Our data show that enhanced intracellular elimination of ROS resulted from the pharmacologic manipulations can cause the antioxidant-induced damage of cells.
Fabrication of Cu-Ni core-shell nanoparticles by co-deposition of RF-PECVD and RF-Sputtering
AIP Advances
In this study, multiwall carbon nanotubes (MWCNTs)/polyaniline nanocomposites deposited on ITO co... more In this study, multiwall carbon nanotubes (MWCNTs)/polyaniline nanocomposites deposited on ITO coated glass as substrate by the spin-coating technique were applied to the investigation of the effect of different contents of MWCNTs on the optical and electrical properties of polyaniline. Micrographs from an atomic force microscope were taken to analyze the 3-D microtexture parameters of surface texture factors and fractal dimension. By using optical spectroscopy of samples with different concentrations of MWNCTs in visible and ultraviolet regions, the transmission variations vs photon wavelength, optical bandgap, absorption coefficient, and skin depth were studied. The variation in the resistance of nanocomposite films exposed to 0.4 %vol of H2 gas at room temperature was monitored, and the results indicated that the sensitivity and responsibility of the composites increased with an increase in the MWCNT amount.
مجله علوم و فنون هسته ای, 2018
In this paper due to the abundant and also different applications of carbon nanotubes doped with ... more In this paper due to the abundant and also different applications of carbon nanotubes doped with boron, molecular vibrations related to boron element were identified and investigated in B-doped carbon nanotubes by experimental, computational and simulation methods. In the experimental approach, Raman spectra of MWCNTs and B-doped MWCNTs were recorded and the Raman active modes assigned to the relevant specific vibrations. In the computational approach, the vibrational frequencies of CC and C-B (pure carbon chains and doped with boron) oscillators were simulated using simple harmonic oscillator model and shift of vibrational frequencies toward lower wavenumbers was observed. Finally, by software simulation approach, vibrational frequencies of carbon-carbon and carbon-boron were investigated using the Gaussian software. The D-band intensity increased as the boron concentration reached to 3% while the center of the peak downshifted by 8 cm-1 (1336 cm-1 1328 cm-1). Doping of carbon nanotubes with the boron concentration in the range of 4 to 10% upshifted the D-band central position by 18 cm-1 (1328 cm-1 1346 cm-1). The ID-IG ratio (the intensity of the disorder D mode divided by the intensity of the graphite G mode) was increased by B-doping of carbon nanotubes (0.751.5). In conclusion, the results of the present article reveals that the intensity and frequency variations of D and G modes in the pure and the B doped MWCNT structures were approved with acceptable accuracy by the experimental, computational and simulation methods.
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Papers by Azizollah shafiekhani