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دسترسی آزاد مقاله
1 - Optical and structural characterization of CdSe:Eu films at different volumes of europium concentration.
Diemiruaye Jeroh Azubike Ekpunobi Donald OkoliCadmium selenide films were prepared at different volumes of dopant (Europium) concentration by electrostatic-spray-pyrolysis technique. Optical results reveal low absorption and reflection with a corresponding high transmission in the visible region. Strong blue-shift چکیده کاملCadmium selenide films were prepared at different volumes of dopant (Europium) concentration by electrostatic-spray-pyrolysis technique. Optical results reveal low absorption and reflection with a corresponding high transmission in the visible region. Strong blue-shift is observed for the band gap energy in all cases of growth, indicating quantum confinement effect. Scanning electron studies reveal relatively smooth surface with small-sized grains on the surface. XRD confirms the crystalline nature of the films having hexagonal (wurtzite) structure with reduction in crystallinity of the film at increased volume of dopant concentration. EDX analysis confirmed the growth of CdSe:Eu film. پرونده مقاله -
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2 - Investigation morphological, electrical, and optical properties of Mn-doped ZnO thin film by sol–gel spin-coating method
Mehmet ÇavaşAbstractIn this study, ZnO was doped with 0.01% Mn and it is grown on p-Si by the sol–gel spin-coating method. Obtained the thin film was studied that to understand the effect of 0.01% Mn-doping ratio on the optical and electrical properties of ZnO structure. In this co چکیده کاملAbstractIn this study, ZnO was doped with 0.01% Mn and it is grown on p-Si by the sol–gel spin-coating method. Obtained the thin film was studied that to understand the effect of 0.01% Mn-doping ratio on the optical and electrical properties of ZnO structure. In this context, first, the morphological structure of the thin film was studied with the use of atomic force microscopy (AFM). The surface structure was obtained homogeneous, and roughness and fiber size were calculated between 27.2–33.6 and 0.595–0.673 nm, respectively. Second, the optical properties were characterized via ultraviolet–visible (UV–Vis) spectrophotometry. Third, the effect of light intensity on junction properties of the photodiode was studied. The current–voltage (I–V) of the photodiode was measured under dark and at the different intensities of illumination. Obtained results showed that the current of photodiode was increased with the intensity of illumination from 6.41 × 10−7 to 5.32 × 10−4 A. These results indicate that photocurrent under illumination is higher than the dark current. After that, the other parameters of the photodiode such as barrier height and ideality factor were determined from forwarding I–V plots using the thermionic emission model that the barrier height and the ideality factor were found 0.74 eV and 5.3, respectively. On the other hand, the capacitance–voltage (C–V) was measured at the different frequencies. The C–V characteristic shown that C–V characteristic of the photodiode was changed depends on increasing frequency. In addition, the interface density (Dit) value was decreased by increasing frequency too. Similarly, the serial resistance of the photodiode was also decreased by increasing frequency. Received all these results indicated that Mn-doped ZnO thin film sensitive to light and due to this property, it can be used for different optoelectronic applications as a photodiode and photosensor. پرونده مقاله -
دسترسی آزاد مقاله
3 - The Effect of Magnetic Nanoparticles along with Magnetic Experimental Modeling for the Desalination of the Caspian Sea Water
Kamran Lari nikoo ostovarIn this study, samples were taken of coastal waters of Kiashahr port. Magnetic desalination consisted of exposing the sample to a Magnetic field and putting the water in physical contact with magnetic nanoparticles which were synthesized with the co-precipitation method چکیده کاملIn this study, samples were taken of coastal waters of Kiashahr port. Magnetic desalination consisted of exposing the sample to a Magnetic field and putting the water in physical contact with magnetic nanoparticles which were synthesized with the co-precipitation method. X-ray diffractometer, Fourier transform infrared spectroscopy and field-emission scanning electron microscopy were used for the characterization of nanoparticles. The results showed nanoparticles have a spherical shape and a diameter less than 20 nm. After modifying the surface of Fe3O4 nanoparticles with SiO2 they maintained their uniform distribution and spherical shape but their size increased by 20 nm. The salinity and electrical conductivity of the sample was measured prior to and following the magnetic treatment. Maximum decrease in the level of salt and electrical conductivity was achieved when 0.1 g of nanoparticles was put in contact with sea water for 2 hours and also when sea water at a flow of 50 ml/min was introduced to a magnetic field of 30 mT for 20 seconds. The amount of salt in the sample was reduced to 9.65 g/l using the above-mentioned method -having an initial value of 11.6 g/l. پرونده مقاله -
دسترسی آزاد مقاله
4 - Experimental Investigation of Mechanical Behavior of Improved Marly Soil Using Nano Calcium Carbonate
Ali Ohadian Mehdi MokhberiOne of the problematic soil types that is found in wide areas in the world is marl soils. This soil type is more sensitive to erosion and requires modifications in pavement construction processes. In this research, mixed soil-Nano-CaCo3 was considered. For this purpose, چکیده کاملOne of the problematic soil types that is found in wide areas in the world is marl soils. This soil type is more sensitive to erosion and requires modifications in pavement construction processes. In this research, mixed soil-Nano-CaCo3 was considered. For this purpose, 0.3 to 2.7% Nano-CaCo3, by specific dry weight, was combined with marl soils in 0.3% increments. To analyse the geotechnical properties of marl soil, optimum water content for soil compaction, maximum dry density, uniaxial compressive strength, California Bearing Ratio (CBR) and the consolidation test were investigated. The results showed dry unit weight increases with increasing Nano-CaCo3 content up to 2.2%. Furthermore, the CBR of modified marl soil with 2% Nano-CaCo3 is 2.7 times greater than the initial CBR; it increased from 6 to 15.5 by adding up to 2% Nano-CaCo3. Moreover, adding Nano-CaCo3 to marl soil increased the uniaxial compressive stress. The optimum percentage of Nano-CaCo3 was 2%, which increased the compression strength about 1.4 times. Besides, with increasing Nano-CaCo3 up to 2.2%, the amount of void ratio decreases from 0.46 to 0.35. Additionally, the compression index Cc and swelling Index Cs are almost constant and equal to 0.09 and 0.03, respectively. پرونده مقاله -
دسترسی آزاد مقاله
5 - Fabrication of Na-W Co-Doped Exfoliated G-C3N4 Nanoparticles for Methylene Blue Removal
Mohammad Javad Hakimi-Tehrani Seyed Ali Hassanzadeh Tabrizi Narjes Koupaei Ali Saffar Mahdi RafieiBulk g-C3N4 has very poor photocatalytic activity. Many methods have been utilized to increase the photocatalytic performance of this semiconductor. Here, a simple preparation was used to create exfoliated g-C3N4 that was co-doped with sodium and tungsten. The produced چکیده کاملBulk g-C3N4 has very poor photocatalytic activity. Many methods have been utilized to increase the photocatalytic performance of this semiconductor. Here, a simple preparation was used to create exfoliated g-C3N4 that was co-doped with sodium and tungsten. The produced Na-W co-doped exfoliated g-C3N4 was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis spectroscopy, and Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS). The doping samples with Na and W changed the band structure of the g-C3N4 lattice, which increased light absorption and caused a reduction in the band gap. The samples had layered morphology. After exfoliation and sodium and tungsten co-doping of the samples, the methylene blue photodegradation was greatly enhanced. The doping of the samples also had an impact on the dye adsorption capacity. The dye removal activity of the Na-W co-doped exfoliated g-C3N4 sample is higher than those of pure bulk g-C3N4 and pure exfoliated g-C3N4. The rate reaction constant (k) of the Na-W co-doped exfoliated g-C3N4 is up to 3.3 times greater than that of bulk g-C3N4. The produced photocatalyst may be utilized for the treatment of wastewater comprising methylene blue as the pollutant agent. پرونده مقاله -
دسترسی آزاد مقاله
6 - Effect of Nano-MgO Additive on Compressive Strength of Concrete Fabricated by Different Processing Methods
Eisa Mahmoudsaleh Ali Heidari Farshid Fathi Seyed Ali HassanzadehTabriziThe effects of adding different nano-MgO dosages (0, 1, 2, 3, and 4 wt.% with respect to cement) on microstructural, compressive strength, and phase evaluation of concrete were investigated. Two different post-treatment conditions with water and CO2 gas were used to stu چکیده کاملThe effects of adding different nano-MgO dosages (0, 1, 2, 3, and 4 wt.% with respect to cement) on microstructural, compressive strength, and phase evaluation of concrete were investigated. Two different post-treatment conditions with water and CO2 gas were used to study the processing method on the samples. The specimens were characterized via SEM and XRD analysis. The mechanical properties of the samples were also investigated. The results showed that compressive strength significantly improved after the addition of magnesium oxide nanoparticles. However, this improvement was more remarkable in the case of post-treatment with CO2 compared to the samples fabricated with water. SEM results showed that the samples treated under CO2 gas had irregular and needle-like morphology. The samples prepared by normal processing had CaCO3 and SiO2 phases, whereas the ones fabricated under CO2 gas contained CaCO3, SiO2, and Ca(OH)2. With the addition of nano-MgO, the density of concrete decreases in the samples post-treated with water, whereas it increases for the samples post-treatment with CO2 gas. Adding 4 wt.% nano-MgO to concrete and further post-treatment with CO2 for 45 days could increase the mechanical properties from ~ 23 MPa to ~ 55 MPa. پرونده مقاله -
دسترسی آزاد مقاله
7 - AB INITIO MATERIAL MODELING STUDY ON LiO ADSORBED BY PALLADIUM-COBALT (PdCo) NANOPARTICLES
mikail aslanPdCo nanoalloy particles have been commonly used as catalytic material in some important chemical reactions, involving in fisher-tropsch reactions, and oxygen reduction reactions. In terms of understanding the role of catalysis, these smallest bimetallic nanoparticles p چکیده کاملPdCo nanoalloy particles have been commonly used as catalytic material in some important chemical reactions, involving in fisher-tropsch reactions, and oxygen reduction reactions. In terms of understanding the role of catalysis, these smallest bimetallic nanoparticles provide the simplest prototypes of Pd-Co bimetallic catalysts for different compositions. In this study, the effect of LixO (x=1,2) on PdCo nanoalloys has been investigated comprehensively employing the density functional theory (DFT) to identify the mechanism of structural, electronic, and energetic properties of the studied species. Binding energies are calculated for stability analysis which is very important for nanoparticles. Results show that lithium oxides are generally adsorbed by cobalt sites on the Pd-Co substrate. This is important for determining active sites of the catalytic material. Furthermore, the structures have low symmetric properties. Hence, this study might provide an initial structural evaluation step for future studies related to the possible new catalytic material of Li-air batteries. پرونده مقاله -
دسترسی آزاد مقاله
8 - Ab initio (first principle) material modeling study on Lio adsorbed by palladium-cobalt (PdCo) nanoparticles
Mikail AslanPdCo subnanoalloys have been commonly used as a catalytic material in some important chemicalreactions, involving in fisher-tropsch reactions, and oxygen reduction reactions. In terms ofunderstanding the role of catalysis, these smallest bimetallic nanoparticles provide چکیده کاملPdCo subnanoalloys have been commonly used as a catalytic material in some important chemicalreactions, involving in fisher-tropsch reactions, and oxygen reduction reactions. In terms ofunderstanding the role of catalysis, these smallest bimetallic nanoparticles provide the simplestprototypes of Pd-Co bimetallic catalysts for different compositions. In this study, the effect ofLixO (x=1,2) on PdCo nanoalloys has been investigated comprehensively employing the densityfunctional theory (DFT) to identify the mechanism of structural, electronic, and energeticproperties of the studied species. Binding energies are calculated for stability analysis, whichis very important for nanoparticles. Results show that lithium oxides are generally adsorbed bycobalt sites on the Pd-Co substrate. This is important for determining active sites of the catalyticmaterial. Furthermore, the structures have low symmetric properties. Hence, this study mightprovide an initial structural evaluation step for future studies related to the possible new catalyticmaterial of Li-air batteries. پرونده مقاله -
دسترسی آزاد مقاله
9 - Deformation of Al Alloy during Integrated Extrusion and ECAP: A Simulation Research
Ankit Sahai Shanti S. Sharma Suren N. DwivediBulk nanomaterial have several applications in automobile, aerospace, medical and manufacturing applications. These are produced by subjecting materials to severe plastic deformation (SPD) and have widely emerged as a technique for grain refinement in Al, Cu, Ti, Mg all چکیده کاملBulk nanomaterial have several applications in automobile, aerospace, medical and manufacturing applications. These are produced by subjecting materials to severe plastic deformation (SPD) and have widely emerged as a technique for grain refinement in Al, Cu, Ti, Mg alloys with improved mechanical properties. Equal Channel Angular Pressing (ECAP) is one such SPD technique employed to produce bulk ultra-fine grained (UFG) materials by introducing a large amount of shear strain into the materials without changing the billet shape or dimensions. FE (Finite Element) modeling of SPD processes has become an important tool for designing feasible production processes, because of its unique capability to describe the complex geometry and boundary conditions. In this proposed work, integrated SPD processes namely Extrusion + ECAP (Ex-ECAP) is proposed and the specimen is subjected to these processes in the same die set-up. The 3D finite element modeling of Al6061 was performed using metal forming software FORGE. The dies used in both the processes during the simulation of Al6061 billet include a channel angle of 900 and outer corner angle fixed at 160 with simulation performed for different plunger velocities. The simulation results depict the change in equivalent strain in the entire specimen on account of these processes. The evolution of strain at different considered cross-sections is analyzed. Also, the variation in extrusion force and energy are studied for the considered process parameters. The FE simulations greatly help in designing the dies for various experimental conditions to produce bulk nanomaterial. پرونده مقاله -
دسترسی آزاد مقاله
10 - کاربرد نانوذرههای استرانسیم فرریت برای اندازهگیری الکتروشیمیایی هیدرازین در سطح نانومولار
محمد علی شیخ محسنی قاسم مرندیبا توجه به اهمیت مقدار هیدرازین در نمونههای آبی متفاوت از نقطه نظرات زیستمحیطی و همچنین، کاربرد فراوان این ماده، نیاز است که غلظت آن در نمونههای متفاوت اندازهگیری شود. در این پژوهش، سعی شده است یک الکترود جدید و درعینحال ساده و ارزان برای اندازهگیری هیدرازین پیشنه چکیده کاملبا توجه به اهمیت مقدار هیدرازین در نمونههای آبی متفاوت از نقطه نظرات زیستمحیطی و همچنین، کاربرد فراوان این ماده، نیاز است که غلظت آن در نمونههای متفاوت اندازهگیری شود. در این پژوهش، سعی شده است یک الکترود جدید و درعینحال ساده و ارزان برای اندازهگیری هیدرازین پیشنهاد و ارائه شود. این الکترود، یک الکترود خمیر کربن اصلاحشده با نانوذرههای استرانسیم فرریت است. این الکترود به دلیل وجود نانوذرهها در ساختمان خود حساسیت و انتخابگری خوبی در الکتروآنالیز هیدرازین دارد. نتایج روشهای ولتاسنجی چرخهای و زمان-آمپرسنجی به خوبی اکسایش کاتالیستی هیدرازین در سطح الکترود پیشنهادی را نشان دادند. حسگر ساختهشده دارای دو گستره خطی، یکی در گستره 5/0 تا 20 میکرومولار و دیگری در گستره 20 تا 600 میکرومولار برای هیدرازین است. این الکترود گزینشپذیری مناسبی در اندازهگیری هیدرازین از خود نشان داد. بررسی تکرارپذیری، تجدیدپذیری و طول عمر الکترود نیز انجام گرفت و نتایج قابل قبولی به دست آمد. اندازهگیری هیدرازین در نمونههای آبی متفاوت مانند آب شهر و آب چاه انجام گرفت. درصدهای بازیابی محاسبهشده در نمونههای حقیقی نشان داد که توانایی الکترود ساختهشده در اندازهگیری نمونههای واقعی خوب و قابلاطمینان است. پرونده مقاله -
دسترسی آزاد مقاله
11 - Comparative Risk Assessment of Tasks Involved with Nanomaterials Using NanoTool & Guidance Methods
Fakhradin Ahmadi Kanrash Soqrat Omari Shekaftik Amirhossein Aliakbar Fatemeh Soleimany Azad Haghighi Asl Wahab Ebrahimi Saeedeh Amini RavandiAssessing the risks related to the advancement of science and technology has always been accompanied by many uncertainties. As a new field of science, nanotechnology faces numerous uncertainties concerning safety, health, and environmental aspects dealing with which req چکیده کاملAssessing the risks related to the advancement of science and technology has always been accompanied by many uncertainties. As a new field of science, nanotechnology faces numerous uncertainties concerning safety, health, and environmental aspects dealing with which requires a proper risk assessment. Accordingly, this study intended to assess the risk of tasks associated with nanomaterials comparatively, examining the risks in eighteen companies in Tehran. The two proposed risk-assessment methods for the activities involving nanomaterials (NanoTool and Guidance) assisted in assessing the risk of their tasks. The results were analyzed using SPSS.22 and the chi-square test and indicated the different outputs of the two methods despite being designed based on the control banding approach. These differences could be attributed to the different risk-assessment parameters that these methods considered. The statistical analysis results also showed no significant relationship between them. Given the large differences and insignificant association between risk assessment results, the guidance method was less effective than the nanotool method. However, straightforwardness and convivence of implementation in the workplace and various research environments make it a helpful method in initial evaluations. پرونده مقاله
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