فهرست مطالب behnaz memar maher

There is an issue with wide particle size distribution during the suspension copolymerization of styrene-acrylonitrile. This results in a lengthy melting time for larger particles and the formation of undesirable small particles that can conglomerate and deposit in the product transfer line and equipment. Therefore, it is necessary to control the size distribution during production. The effect of different variables like the reaction temperature, final reaction temperature, the mixer speed, the monomer-to-water ratio, the initiator concentration, the chain transfer agent concentration, the proportion of styrene to acrylonitrile, as the suspending agent concentration, the proportion of styrene to acrylonitrile on the monomer conversion, the molecular weight and particle size of the product by Taguchi approach was investigated. As the results showed, the best Particle Size Distribution (PSD) was obtained at the temperature of 76°C and a water/monomer 65/35 (wt/wt), 0.016 suspending agent/monomer (wt/wt), 1000 rpm mixer speed, and 0.0095 (DEM) stabilizer /suspending agent (wt/wt).

The frankincense essential oil was successfully incorporated into nano-sized microemulsions systems through low energy self-emulsification technique. The effects of main formulation parameters, namely, surfactant, co-surfactant, essential oil, and water concentrations, as well as the mixing rate and temperature on mean particle size, polydispersity (PDI), turbidity and antioxidant activities of colloidal frankincense essential oil nanoparticles, were investigated. The results show that all studied independent parameters affect the most characteristics of frankincense essential oil microemulsions, significantly. The antibacterial activities of essential oils were also considerably increased as incorporated into nano-sized microemulsions. It resulted that the most desired frankincense essential oil microemulsions, with desired characteristics (less particle size, size distribution, turbidity, and greater antioxidant activity) could be obtained using high concentrations of surfactant (0.7 g), medium concentrations of co-surfactant, essential oil and water (0.2 g, 0.1 g, and 9.2 mL, respectively), and medium levels of mixing rate and temperature (500 rpm and 40 °C). Thus, by tuning the formulation or process parameters the most desired nano-sized essential oils can be prepared as natural preservers or health-promoting agents for various food and beverage applications.

Because of the heavy effects that risk has had on individuals, groups, and societies since the beginning of history, they have developed several methods for risk. In this research, different jobs in the operation of the gas company of Ardabil province and related jobs were identified and after evaluating them, the degree of risk and probability of occurrence was identified for each of the jobs, then the risk was assessed using the JSA method and the results were Modeling was done using Pro-PHA software. The results of the research showed that a total of 121 operations were identified in the process of this evaluation, out of which 22 cases had high risk and the possibility of an accident, 65 cases were within the risk control range, and 34 cases were low risk, that is, 28% had low risk and were under control. It is 54% of it is within risk control and needs action, finally, 18% has high risk and needs self-action.

Ceftriaxone is one of the antibiotics used to treat some infectious diseases. The wide range of applications and sensitivity in the correct use of this drug doubles the necessity of measuring this drug. Many methods including chromatography have been used to measure it. Using the voltammetry method for measuring drugs is considered a bonus because of its accuracy, speed, and reasonable price. In this research work and in the modified electrode design, reduced graphene oxide to increase the sensitivity of the electrode; molecular template polymer made with methacrylic acid and ethylene glycol dimethacrylate to increase selectivity; And the electropolymerization of diphenylamine was used to stabilize the molecular template polymer on the electrode surface and increase the sensitivity. After several optimization steps, the designed electrode was used to measure small amounts of ceftriaxone. The linear range was between 0.025-3.047 μM and the detection limit was 0.008 μM. The designed electrode was successfully used to measure ceftriaxone in pharmaceutical and biological environments.

Hypothesis: Medicinal compounds, pharmaceutical substances and their metabolites enter the environment through hospital, domestic and pharmaceutical industries. Conventional technologies are not able to treat such wastewaters fully and therefore they are abundantly found in water. So far, various chemical, physical and biological methods have been used to remove medicinal compounds from aqueous solutions. In this research, PVDF/g-C3N4/Chitosan as a new and powerful membrane was prepared and removal of cefixime from aqueous solutions was investigated using response surface methodology (RSM).

PVDF/g-C3N4/Chitosan membrane was prepared by immersing the PVDF/g-C3N4 membrane in a solution containing different percentages of chitosan. To evaluate the efficiency of the PVDF/g-C3N4/chitosan membrane in removing cefixime, the response surface methodology was used based on the central composition design and four parameters, i.e., chitosan percentage, g-C3N4 value, pH of solution and cefixime concentration were selected as dependent variables. The quadratic model was used to calculate the four dependent variables.

The results showed that among the studied parameters, chitosan had a major effect on the structural properties of the PVDF/g-C3N4/chitosan membrane due to the conversion of polyvinylidene fluoride membrane to hydrophilic ones. According to the results, the maximum cefixime removal by the PVDF/g-C3N4/chitosan membrane was about 81.34% at a solution pH of 4.42, 3.19% chitosan, 0.11 g g-C3N4 and cefixime concentration of 42.51 mg/L. The numerical optimization results showed a slight difference between the predicted number (81.34%) and the experimentally obtained number (78.21%). Also, the high correlation coefficient (99.41%) showed that the response surface methodology has a high potential for predicting and optimizing the cefixime removal process by PVDF/g-C3N4/chitosan membrane with a small number of experiments.

The present study was done with the aim of evaluating the occupational stress of the treatment staff and comparing it with the occupational stress of the paraclinical and support hospital employeesof Tawheed Sanandaj Hospital. This research is a descriptive-analytical type of study. The statistical population of this research was formed by all the employee of the treatment staff and paraclinical and support units of Tawheed Hospital in the year 1400. According to the inquiry, their number is 421. Cochran's sample number of 201 people was selected as a sample using the available random sampling method. In order to measure the variables of this research, the standard questionnaire of Spivo (1987) was used. Finally, SPSS software was used to perform calculations in this research. The results showed that the occupational stress of treatment staff and staff of paraclinical and support units of Tawheed Sanandaj Hospital is above the average level, and further it was found that the occupational stress of treatment staff and comparing it with the occupational stress of paraclinical and support unit employee dose not have a significant difference.

Natural bioactive compounds, such as essential oils, with antimicrobial or antioxidant activity, have received considerable attention recently, especially with rising concerns on the safety of synthetic food preservatives. However, due to their low water solubility and structural stability, their incorporation into water-based food formulations are limited, as is the other lipophilic functional compounds. Moreover, in order to investigate the possible synergistic effects of the most combinations of the essential oils, the aim of this study was to prepare water-dispersible licorice-garlic-fennel essential oil nanoparticles using nanoemulsion systems through a low-energy self-emulsifying technique. The effects of essential oil proportions in the oil phase on nanoemulsion characteristics were also evaluated using a simplex-centroid mixture design, and various empirical models were developed to predict changes in the obtained nanoemulsion characteristics. Finally, multi-goal optimization was applied to obtain the most desired composite nanoemulsions with the least mean particle size, polydispersity index, turbidity, and the greatest antioxidant and bactericidal activity. Based on this optimization analysis, the most desired product was obtained using 39% licorice, 40% garlic, and 21% fennel essential oil as oil phase. The results also confirmed the synergistic effects of selected essential oils towards one another, which the nanoemulsions with two- and three- components oil phase exhibiting higher antibacterial and antioxidant activity than those with a single-component oil phase. The prepared nanoparticles had reasonable physical stability at 5 ± 1 °C during 40 days of storage.

Polymers have been substituted for metal in many applications due to their good mechanical and chemical properties, but their flammability has limited their use, and many studies have been performed to improve the flame retardancy of polymers. Thermal pyrolysis of polymers leads to the formation of highly reactive radical species • O •, H and • OH [3]. The first two species are mainly converted to hydroxyl radicals (• OH). OH's participation in the exothermic reaction provides the heat needed to spread the flame. Inhibition (• OH) prevents the flame from advancing. Halogen flame retardants, which produce radical halogens, release phosphate inhibitors that release HPO, PO, or PO2, inhibiting OH. To reduce the flammability of polymers, either the polymer structure can be manipulated or the surface coating of the polymer textiles can be barrier-layered. The flame retardant halogen in the produced samples weakens the mechanical properties compared to the observed grade. In flame retardant, as the percentage of halogenated flame retardant compounds in the polymer increases, the polymer flame retardant increases in approximately the same proportion.

Plant essential oils are important in the food industry due to their antimicrobial properties as antioxidants and natural preservatives, as well as flavorings and aromatizers. The main problem is the high volatility and very low solubility of essential oils. Therefore, the dispersion of essential oils in water as nanomaterials, using the techniques presented in nanotechnology, can be an effective solution to these problems. Therefore, in this study, microemulsions of licorice, garlic and fennel essential oils were successfully prepared. Physical and chemical properties, antioxidant activities, antibacterial activities of the prepared microemulsions were investigated. Microbial and turbidity results showed that reducing the particle size of essential oils in the nanoemulsion range using microemulsion systems could increase their antibacterial and antioxidant properties. Because the turbidity of microemulsions is a good indicator of their size or physical stability. Therefore, the stability also increased with decreasing particle size. Therefore, the aim of this work was to prepare licorice, garlic and fennel essential oil nanoparticles and to investigate their physical, chemical, antimicrobial and antioxidant properties.