جستجوی مقالات مرتبط با کلیدواژه "مایکروویو" در نشریات گروه "علوم پایه"

In response to the increasing color pollution in industrial wastewaters and the need for effective treatment methods, this research investigates the application of the Fenton and microwave-enhanced Fenton processes for color removal. The aim of this study is to compare the effectiveness of these two processes and to identify the optimal conditions for the maximum removal of color pollutants. This study evaluates the efficiency of the Fenton and microwave-enhanced Fenton processes in dye removal from wastewater. To examine the impact of parameters such as pH, dye concentration, Fe2+, and H2O2 on the efficiency of removing the Reactive Red 198 dye and COD, these variables were altered during the experiments. The mechanism of dye molecule removal was analyzed through UV-Vis spectroscopy. The optimal conditions for the microwave-enhanced Fenton process included an initial dye concentration of 300 mg/l, a pH of 3.5, an Fe2+ concentration of 20 mg/l, and an H2O2 concentration of 100 mg/l. Under these conditions, a COD reduction of up to 85% and dye removal of over 98% were observed. The findings suggest that the microwave-enhanced Fenton process can effectively reduce color pollutants and improve the quality of industrial wastewater. This method offers high reaction speed and remarkable efficiency under various treatment conditions, making it a suitable solution for treating wastewater with high dye loads.

Carbon nanotube/polystyrene nanocomposites were synthesized via microwave-assisted in-situ polymerization. Since carbon nanotubes can absorb microwave irradiation, they can form hot spots in the mixture, and the auto thermal polymerization of styrene monomers can be initiated from their surface without using any chemical initiator. In order to investigate the effectiveness of the microwave irradiation on the polymerization process, carbon nanotube/polystyrene nanocomposites were synthesized via heating. Samples were characterized by TEM, FESEM, FT-IR, TGA and Raman spectra, and the electrical conductivity of samples were also measured. The results showed that using microwave irradiation can result in forming a polymeric layer on carbon nanotubes, and the resultant nanocomposite had a few agglomerations. In addition, by increasing the power of microwave irradiation, the thickness of the polymeric layer increased and electrical conductivity decreased.

In this paper, to develop green chemistry, a catalyst based on layered double hydroxides (LDHs) attached by hexamethylene-1,6-diisocyanate (HMDI) and citric acid (LDH-g-HMDI-citric acid) were prepared and characterized by FT-IR, XRD, EDX, SEM, TGA, and DTG analytical methods. The catalytic activity of this recyclable heterogeneous catalyst was evaluated for the synthesis of new imidodicarbonate diamide derivatives (biuret) under microwave conditions. The use of the microwave method led to the use of organic solvents in small amounts, reduced reaction times, and increased yields of products, which was achieved for the development of green chemistry and environmental protection. These biurets were evaluated for inhibitory activity on human immunodeficiency virus type 1 (HIV-1) by HIV-1 p24 antigen ELISA kit and three of them (5b, 5c, and 5f) had moderate activity on HIV -1 virus with IC50 values in the range of 55.1 to 100 μM compared to azidothymidine as the reference drug (IC50 = 0.11 μM). Finally, to investigate the mechanism of the effect of biuret compounds on the virus protease enzyme, docking analysis studies were performed and the results of in vitro test and docking study were in good correlation.

Today, biodiesel is being produced and consumed around the world as one of the main sources for replacing fossil fuels. In current research, cobalt doped zinc oxide was used as nanocatalyst to produce biodiesel from soybean oil by transesterification reaction. The nanocatalysts used were first prepared by microwave method and identified by X-ray diffraction (XRD), scanning electron microscopy (SEM) and x-ray energy dispersive spectroscopy (EDS). In the next step, the prepared catalysts were used in the reaction of biodiesel production from soybean oil. The produced biodiesel was characterized using nuclear magnetic resonance spectroscopy (NMR) and gas chromatography-mass spectroscopy (GC-MS). Optimal reaction conditions of biodiesel production with cobalt doped zinc oxide nanocatalyst obtained, at 3 h, temperature 60 ˚C, catalyst concentration 3% by weight, and molar ratio of oil to methanol 1 to 41 resulted in 98% efficiency. In another part of this research, microwave radiation with a power of 250 W was used as a source of energy in the biodiesel production reaction which in the presence of 4% by weight of catalyst and molar ratio of oil to methanol 1 to 20 resulted in 91% efficiency in 180 s.

A new generation of microwave sounders, including the Advanced Microwave Sounder Unit (AMSU), on NOAA's polar-orbiting satellites has been providing global, continuous measurements of water vapor and many other atmospheric parameters for more than two decades. In the microwave region, water vapor, oxygen, nitrogen and ozone are active atmospheric gases. All of these gases are not considered in radiation transfer models for calculating radiation in satellite microwave radiometers including AMSU.The aim of this article is to investigate the effect of ozone absorption lines on the brightness temperature of AMSU radiometer. For this purpose, first, using the Atmospheric Radiation Transfer Simulator (ARTS) model, the absorption spectrum of ozone was simulated in the range of AMSU frequencies, and then the location of these channels was placed on the absorption spectrum of ozone. Some AMSU channels are located near the peaks of ozone absorption lines, which can affect the brightness temperature of these channels. For quantitative analysis, the lighting temperature of all 20 AMSU channels, without including ozone and including with ozone was simulated and then the brightness temperature differences (∆TB) was calculated in both cases. The ∆TB values for all channels were negative, that is, the presence of ozone reduces the brightness temperature. The results also showed that ozone has the greatest effect on channels 5, 1, and 8 of AMSU-A and channels 18, 17, and 20 of AMSU-B, respectively. The highest value of ∆TB was obtained for channel 18, with an approximate value of 0.6 degrees Kelvin.

2-Amino-4H-chromene compounds are belonged to an important heterocyclic groups that have extensive important in organic chemistry and medicine. The compounds have anti-cancer, anti-bacterial, anti-coagulation and anti-tumor properties and have applications to produce dye, make up and hygienic materials. Until know, several methods have been reported for the synthesis of the compounds. Most of them, suffers defects such as poisoning and volatile solvents, low yield, high length reaction time, and no reusability of used catalyst. In the present work, Sr2As2O7 pyrochlore material was used as a catalyst for the synthesis of 2-amino-4H-cromens derivatives using a three component one-pot synthesis method under microwave irradiation. The raw materials were aromatic aldehydes, malononitrile and beta-naphtol. Sr2As2O7 was synthesized by an ultrasonic assisted solvothermal method using H2O and C2H5OH solvents mixtures at the 1:1 volumetric ratio. The materials were characterized by PXRD, FESEM and FTIR techniques. Then, the catalytic performance of the synthesized nanomaterial was used for the synthesis of 2-amino-4H-chromene derivatives. To do the process, the reaction parameters such as reaction time, solvent type and catalyst amount were optimized and the reactions were performed under the conditions. It was found that the optimum conditions were 15 mg catalyst, H2O as solvent and 6-9 min reaction time.

In this study, iron-doped tin oxide semiconductor nanoparticles with an iron to tin mole ratio of 0, 1, 2 and 3% synthesized by microwave method. The crystal structure, surface morphology, chemical bonds, and optical properties of the samples were studied by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), infrared fourier transform spectroscopy (FTIR), and UV–Vis spectroscopy. Elements analysis was performed by EDAX. The X-ray diffraction results showed that the samples were polycrystalline, and have the preferred peaks of plates (110), (101), (200), (211), (220), (002), (310), (112), and (301) SnO2 phase with rutile rectangular structure. Increasing the iron impurity density from zero to three percent causes the reducing average size of nanocrystals from 23.53 to 11.03 nm, reducing grain size from 37 to 28 nm, and increasing unit cell volume from 70.61 to 71.40  and the optical band gap from 3.3 to 4.2 eV. The results of FTIR analysis confirm the SnO2 bond in the samples. Investigation of the sensing properties of ethanol gas by the samples showed that the response time of the sensors is in the range of 15.75 to 38.85 s. The sensor made with nanoparticles with a concentration of 1% iron exhibited optimum sensing conditions.

The objective of the present study was to investigate the extraction of Ferulago angulate essential oil using the two methods of Clevenger-microwave and ultrasound, and to examine their effects on the quantity and quality of the essential oil of this medicinal plant. In the Clevenger-microwave method, the plant to water ratios of 1:10 and 1:20 and the microwave power of 330, 660 and 990 w (30,60 and 90%) were taken into account as the independent variables, while in the ultrasound method, the indirect ultrasound pretreatment (at 20 and 45°C) was considered as the affecting factors for the extraction of the essential oil of Ferulago angulate. In order to identify the chemical compounds, gas chromatography-mass spectrometry was employed and the impact of other parameters, including the efficiency, specific gravity, color, refractive index and antioxidant power of the essential oil were also valuated. It was found out that application of microwave and the rise in its power led to a decrease in the extraction initial time as well as a reduction in the extraction completion time and the time needed for the extraction curve to get constant from 4 h to 1 h. β-phellandrene had the largest content (approximately 35%). Extraction time in the microwave treatment was significantly lower than that of Clevenger.Ultrasound pretreatment at various temperatures, utilization of the Clevenger-microwave extraction method at different microwave powers and the change in the plant to water ratio did not have considerable effects on the essential oil refractive index, antioxidant activity and specific gravity

Effects of diets containing microwave-irradiated canola meal were evaluated on growth, nutrition performance, carcass composition and digestibility of nutrients in Huso huso fry with 31.18 ± 1.43 g in initial weight during 8-week experiment in a factorial design 4 × 2 with 8 treatments, each with 3 replications. Treatments included T1: %20 canola meal without irradiation; T2, T3 and T4: 20% irradiated-canola meal at 800 watts for 5, 10 and 15 min respectively; T5: 40% canola meal without irradiation; T6, T7, and T8: %40 800 watt – radiated canola meal at 5, 10 and 15 min respectively. At the end of the experiment, according to the results, the effects of diet containing microwave-irradiated canola meal on the final weight, weight gain, specific growth factor, feed conversion ratio and daily growth in H. huso fry were significant (p<0.05). The highest final weight, percentage of weight gain, daily growth and specific growth rate were found in T4, while the lowest ones in T5 (p<0.05). Food conversion ratio increased significantly in T5 compared to the other treatments (p<0.05). The results of analysis of variance exhibited that the effects of both canola meal rate (%) and irradiation time and also their interactions caused significant differences in the growth indices except for the coefficient of conversion (p<0.05), but only irradiation time displayed significant effect on food conversion ratio (p <0.05). During the experiment, survival rate was 100%. Microwave-irradiated canola meal diet did not significantly affect the protein and fat contents of the fish carcasses (p>0.05), but showed significant effect on the carcass ash content (p<0.05). According to these results, by increasing irradiation time, the protein digestibility increased (p<0.05). Microwave-irradiated canola meal exhibited no significant effects on fat digestibility and dry matter content (p>0.05). So, it can be added to the diet up to 40% without any unfavorable effect on protein digestibility and growth rate.

In this research, the structural modification of nano bentonite carried out to create a porous clay intercalated by Al, Fe-polyoxocations into basal spacing of bentonite layers. In this way, to increase pillars and to improve the adsorption and catalytic properties of pillared samples, the effect of ultrasonic waves and microwave irradiation in both aging and intercalation steps was investigated for a first time. The incorporation of ultrasonic and microwave techniques significantly reduced the synthetic time and water consuming. In this research the effect of calcination temperature for the formation of stable pillars from FexAl13-x oxides was also evaluated at 300, 500, 700 and 900°C. The obtained results of UV-Vis, FTIR, XRD, N2 adsorption-desorption showed the increase of d001, the increase of micro and mesopore volume, and the increase of Al and Fe content in pillared samples due to formation of polyoxocations in the interlayer space of bentonite. The obtained results from calcination effect illustrated the high stability of pillared samples until 700°C, and increased the destruction effect on clay structure at 900°C.

In this study, the effects of pretreatment irradiation power and time of microwave on total phenolic content , oxidative stability and the physicochemical properties of Cannabis oil, which included: extraction efficiency, acidity values, refractive and color index were studied by a completely randomized design in the form of 3×3 factorial experiment with three levels of applied microwave irradiation power (180, 540 and 900 W) and three microwave time levels (90, 180 and 270 seconds) and three replications. The hemp seeds were supplied from animal feed store in Gonbad kavous city in early spring of 2017 and oils were obtained by using spiral press .The SAS software was used for data analysis. The results were showed that with increasing microwave power, the oil extraction efficiency, acidity, color index, oxidative stability and total phenol increased significantly (p

Photocatalytic wastewater treatment as an important member of advanced oxidation processes with a high energy efficiency plays important role in wastewater treatment. This method is known as an energy efficient method because of solar light utilization availability. In this work, TiO2 nanophotocatalyst has been synthesized using titanium (IV) butoxide as a Ti precursor. Then, the nitrogen doping was considered to activate the photocatalytic ability in the visible part of the light spectrum. N-TiO2 nanophotocatalysts were synthesized using a hybrid method of hydrothermalmicrowave. The analyses of XRD, FESEM, BET, EDX and UV-vis spectroscopy were carried out to evaluate the physicochemical and optical properties of the catalysts. The XRD analysis has confirmed the successful synthesis of the TiO2 with anatase crystalline phase. FESEM images have confirmed the nano-sized structure of the catalysts. The BET surface area coincided the FESEM results by representation of surface area enhancement after doping with nitrogen. EDX has verified the presence of nitrogen in the sample and demonstrated uniform dispersion and no agglomeration of Nitrogen presented on the catalyst surface. The photocatalytic degradation of dye from the synthetic wastewater was carried out resulting the highest photocatalytic activity for N-TiO2 in comparison to undoped samples. The experiment resulted 90 percent of degradation after 140 min while undoped TiO2 represented just 52 percent of degradation. Also, to have a better comparison, the industrial photocatalyst P25 was used in the same experiment time and operational conditions. The results depicted higher photocatalytic activity for hydrothermal-microwave synthesis of TiO2 compared to industrial TiO2 with 15 percent higher degradation.

Wireless technology is so widespread today that its absence from communication systems would put the future of such systems in uncertainty. The idea that mobile phones, tablets, or even electric vehicles would have the smart charging capability in the not-so-distant future, is very exciting. From a different perspective, however, the thought of the huge impact that a full power loss would have upon human safety, and rescue operations in human adversities and natural disasters, is harrowing. Indeed, all of us have to deal with a much smaller scale of this problem, that is, the need for recharge or replacement of our mobile phone or tablet batteries, on a regular basis; since the operation of these communication systems is essentially limited to the life of their energy source, i.e. batteries. Therefore, considering the infrastructure in place for information transmission and the recent advances in wireless energy transfer, it is perhaps time to conceive a future of more than just a dream for simultaneous wireless information and power transfer (SWIPT). As a key enabling technology for truly perpetual communications, SWIPT offers the potential to build networks with larger throughput, higher robustness, and increased flexibility compared to battery-powered counterparts; though undoubtedly, it also introduces significant research and implementation challenges.

In this work, Cobalt doped Nickel Ferrite nanostructures (Ni1-xCoxFe2O4; (x = 0.0, 0.05, 0.15, 0.2, 0.3) were synthesized by Microwave assisted combustion method and then the powder obtained was pressed to form disk shape sample with 2.5cm in diameter. The samples were annealed at 700°C for 4 h. Structure, surface morphology and gas sensing properties of the samples were studied using X- ray diffraction (XRD), Filed Emission Scanning Electron Microscope (FESEM) and Gas Sensing Reactor (GSR). The XRD spectra of the samples indicate the formation of spinal phase. Sensors response at different temperatures were investigated for acetone gas (2500ppm) and the results indicate that the optimum work`s temperature for samples is about 300°C. The results showed that the as grown samples have the higher response compared to the annealed samples. The maximum response achieved in sample with %5 Cobalt doping.

Due to the wide spread utility of the cell phones in the world, grate concerns exist about the possible effects of its radiation on the well being of the living creatures. Based on the results of many studies, microwave radiation of mobile phones caused different derastic effects such as chromosome damage, single and double-stranded DNA breakage, increas the risk of mutation and variaty of cancers in the animals. Some researchers believe that the electromagnetic waves of mobile phones solely do not cause genetic damage, but it increases the genotoxic effect of other physical and chemical agents as well as environmental pollutants. In this paper, adversed effects of the radiation from mobile phones on human and different animals such as mice, rat and guinea pig have been investigated.