فهرست مطالب babak shokri

Plasma technology is one of the newest methods used for energy production and waste treatment. The addition of plasma technology to gasification has created a new method for waste management. However, the plasma gasification process is one of the complex thermochemical processes in which many reactions occur simultaneously, therefore it is very difficult to study the theory of this process. Therefore, having approximate and simulated results before launching and implementing the proper system of this process for biomass waste is essential in order to reduce operational costs and time. In order to study this complex process, a model based on the minimization of Gibbs free energy in Aspen Plus software environment has been developed. The created model, that is based on thermodynamic equilibrium, was evaluated with the results reported in scientific sources, which gained the necessary credibility to study important operating parameters such as temperature, equilibrium ratio and vapor ratio on syngas components. The effect of equivalence ratio on the components of the gas product was investigated and it was concluded that the parameter is very effective in the plasma gasification process, the increase of which causes the process to proceed rapidly towards combustion. The highest amount of hydrogen production for steam as a gasifying agent was obtained at a temperature of 900°C which is much more than the amount of hydrogen produced for the air. Also, the equivalence ratio showed the greatest effect on the value of the lower heating value of syngas compared to the temperature parameter. The effect of temperature was significant up to about 800°C and after this temperature, the effect decreased.

The current study aimed to assess the effect of non-thermal plasma (NTP) on the pushout bond strength (PBS) of epoxy resin and tricalcium silicate-based endodontic sealers.

Forty single-canal extracted teeth were decoronated at the coronal region, underwent root canal preparation, and were assigned to four groups (n = 10) for the application of AH26 sealer, NTP + AH26 (P-AH26), Endoseal TCS sealer, and NTP + Endoseal TCS sealer (P-TCS). The root canals were sectioned into 1 mm slices, and the PBS value was measured in a universal testing machine. Data were analyzed by the Friedman, Kruskal-Wallis, and Dunn tests (P < 0.05).

The PBS of TCS and P-TCS groups was not significantly different (P > 0.05). The PBS of the P-AH26 group was significantly lower than that of the AH26 group in the middle third (P < 0.05). The PBS of the AH26 group was higher than the other groups in all sections. The PBS in the apical third was lower than other sections in all groups (P < 0.05).

NTP had no significant effect on the PBS of Endoseal TCS. NTP significantly decreased the PBS of AH26 sealer in the middle third but had no significant effect on its bond strength in other sections.

Industrial and research use of thermal plasma technology for a wide range of applications such as material processing, gasification, and disposing of hazardous waste. In this research, we have designed and manufactured a plasma torch for the gasification of liquid carbon-based materials. In particular, these materials must be sprayed at a certain angle into the plasma. The plasma torch is one of the components of a liquid waste gasification device, in this research, we have only studied the thermodynamic and electrical characteristics of the plasma torch. The plasma torch has been tested in two cases Finally, the electrical and thermodynamic characteristics of the plasma torch were measured and compared to each other. According to the results, the plasma torch has a maximum electrical voltage of 210 V and thermal efficiency of 86.2%. The maximum plasma enthalpy value is 21.5 MJ/kg and the maximum plasma jet temperature at the nozzle outlet is 3400 K. Plasma torch at a distance of 20 mm from the nozzle outlet has a temperature above 3000 degrees Celsius, which can be completely gasified the organic compounds and carbonaceous materials.

Carboxymethyl cellulose-coated polypropylene film containing Satureja hortensis Essential Oil (SEO) was developed based on the casting method as a novel composite bilayer film intended for food packaging. Polypropylene films were initially treated with an atmospheric plasma system to improve adhesion properties. The films were incorporated with 1-4% Satureja hortensis essential oil and were characterized for physical (thickness, moisture content, and water solubility), mechanical (Tensile Strength (TS), and elongation at break), optical, as well as Water Vapor . Permeability (WVP), and microstructure (SEM) properties. The antimicrobial activity of the films against five selected bacteria including S. aureus, B. cereus, E. coli, S. Typhimurium, and P. aeruginosa was also examined with direct contact and vapor phase methods. Results showed that higher SEO incorporation dosage led to significantly lower solubility and permeability of bilayer film (P<0.05). Additionally, by increasing SEO concentration, more opaque and stretchable films with less resistance to breakage were obtained. Films incorporated with 2-4% SEO effectively inhibited all tested microorganisms both in direct contact and vapor phase. Results of the present study suggest that SEO incorporated PP/CMC films as a novel structure of biopolymer coatings on common plastics that can be potentially used as active packaging for food products.

In this study, a fluorinated silicate film was produced by plasma polymerization using a radio frequency plasma system. In order to reduce the refractive index of the films, structured porosity was created in the film. The amount of impurities, optical absorption coefficient, surface roughness, the leakage current density and the threshold of the breakdown field were investigated. To investigate the effect of plasma polymerization process, fluoride gas type and working pressure, as well as placing the base for substrates were tested. The chemical bonding states of the films and the morphology of the films surface were investigated using the infrared Fourier transform spectrometer and atomic force microscope, respectively. In addition, the study of refractive index and absorption coefficient were also performed by spectroscopic ellipsometry. The results showed that the high purity fluorinated silicate film having structured porosity has ultra-low refractive index and the extinction coefficient lower than 10-4 , and increasing the pressure as well as placing the stand for silicon substrates causes to increase organic impurities, especially carbon bonds, thereby eliminating the structured porosity, which in total led to increase the refractive index (1.37 and 1.39) and the extinction coefficient (0.004 and 0.0005) of the films.

In this study, silica and carbon doped silica thin films were deposited on silicon substrates by plasma polymerization using capacitively coupled system in radio frequency. Organo-silicon TEOS vapor was used as a precursor for synthesizing the films which were mixed by specific flow rate of oxygen gas.In order to combine carbon elements into the silica films, acetylene gas was also added into the plasma gas mixture. The effect of acetylene gas flow rates on thickness and refractive index of the films was studied by spectroscopic ellipsometry. Furthermore, in order to investigate the films transparency, the optical absorption was also determined using the same analysis. Morphological investigation of the films using atomic force microscopy was shown that increasing acetylene into the plasma, causes to increase the surface roughness of the films from 0.1 nm to 5.3 nm. Furthermore, the results of optical analysis were shown that increasing acetylene concentration in the plasma led to increase the films refractive index from 1.447 to 1.485 as well as increase their optical absorption from 0.8% to 9.3%. Moreover, for adding carbon elements into the silica films and changing their properties, the effect of increasing acetylene flow rate was compared by decreasing oxygen flow rate.

Cancer is the second leading cause of death in the world and third in Iran. Various methods have been investigated for cancer treatment in which the use of cold atmospheric plasma and plasma-activated medium (PAM) are two new research methods in the field of cancer therapy. This study aimed to evaluate the inducing of apoptosis as cell death mechanism by cold atmospheric plasma in cervix cancer cell line (Hela)

At first, the effects of helium and helium + oxygen atmospheric plasma and PAM on the viability of Hela cell line were investigated. Then, the rate of H2</sub>O2</sub> in the medium, and the levels of caspase-3, caspase-8, Bcl-2-associated X (Bax), and B-cell lymphoma protein 2 (Bcl2</sub>) proteins in both direct plasma and PAM treatments were evaluated using MTT assay, medium H2</sub>O2</sub> assay, and Western Blot analysis, respectively.

The decrease of cells viability in direct plasma treatment group was more than PAM group (P < 0.001), and adding oxygen to plasma increased the rate of cell death. The H2</sub>O2</sub> level in medium in direct method was more than PAM (P < 0.001). Moreover, the expression of caspase-3 and caspase-8 proteins in direct plasma were higher than PAM (P < 0.010). Higher ratio of Bcl-2/Bax showed the induction of apoptosis in cancer cells (P < 0.001).

 Cold atmospheric plasma is a source of oxygen and nitrogen reactive species, which can produce free radicals such as H2</sub>O2</sub> in medium that plays an important role in the treatment of cancer. Moreover, direct plasma and PAM induce apoptosis in cancer cells, as a probable mechanism of cell death.

Increasing of global warming mainly refer to increase in greenhouse gases and many other pollutant gas (like benzene) emission from companies’ outlet gases. This is the main reason of doing this research in which plasma technology is used for converting such pollutant gases. In recent study a gliding arc reactor is used to investigate the performance of it on Methane, CO2 and Benzene decomposition. The effect of main parameters like discharge power, gas flow rate, and different kind of carrier gas is investigated. Ar is used as carrier gas for Benzene conversion, however in case of Methane and CO2 splitting Ar and N2 are used as carrier gas. The results show the highest conversion rate for Benzene is around 70% which is comparable with other similar works. In Methane and CO2 dissociation, the main product is syngas (H2+CO) and small amount of O2.

There are many reports published about the use of cold atmospheric plasma in cancer treatment recently. In this way, the selective effects of cold plasma on the breast (MDA-MB-231) and cervical (Hela) cancer cells were studied as a new cancer treatment method.

In this study, cold atmospheric pressure plasma was generated using a plasma jet reactor and also optical emission spectroscopy (OES) was used to investigate the free radicals produced by the plasma. Futhermore, the effects of helium and helium-oxygen gas mixtures and the time of plasma radiation on the viability of MDA-MB-231 and Hela cells immediately, 24 and 48 hours after radiation were determined by MTT assay. In this account, in order to investigate the selective effects of plasma, direct treatment method was used to evaluate the viability of normal fibroblast cell line.

The results of optical emission spectroscopy showed that decreasing the sample distance from the plasma jet nozzle and increasing operating voltage increased the free radicals produced by plasma. Increasing the time of direct plasma radiation from one to five minutes reduced the vitality of the cancer cells. The most anti-cancer response was observed 48 hours after plasma irradiation and in the helium-oxygen gas mixture. Also, the results showed that cancer cells are more sensitive than normal fibroblast cells to plasma treatment.

According to the promising results of this study, reducing the viability of cancer cells and fewer toxic effect on normal cells, cold plasma therapy can be considered as a new method for cancer therapy.

In the present work, we have reported the in situ oxidation of manganese (II) acetate to MnO2 nanoparticles through the thermal plasma carbonized natural hydroxyapatite (MnO2/TP-NHAp) as a neoteric sustainable method. Interestingly, the thermal plasma-processed surface of the NHAp shows a great ability for oxidation of the manganese (II) without need of any external oxidizing agents. The catalyst was characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), thermogravimetric analysis (TGA), flame atomic absorption spectroscopy (FAAS), Fourier transform infrared (FT-IR), scanning electronic microscopy (SEM), and energy dispersive spectroscopy (EDS). The catalytic activity of MnO2/TP-NHAp was investigated in the selective aerobic oxidation of alcohols and benzylic alkyl arenes at 80 °C in toluene under an atmospheric pressure of air as a source of oxidant. Since the catalyst can be easily recovered and reused at least for four consecutive cycles without losing significant activity and selectivity, it showed admirable potential in reusable catalysis.