Showing 5 results for Ehteram
Volume 11, Issue 2 (Spring 2020)
Abstract
Abstract. Phycocyanine (PC) belongs to a group of protein receptor proteins called phycobiliprotein. All of the phycobiliprotein are multi-chain proteins made up of apoproteins. Which are covalently attached to the phyclobilins. This experimental study was carried out on strain of native Anabaena doliolum, Isolated from soils and waters of south Iran were Masjed Soleyman area. The cyanobacteria were grown and stored in BG11 medium. Then, the amount of phycocyanin produced under different light treatment and the amount of phycocyanin extracted using different ratios of multi-buffer and at two different temperatures were evaluated. The results of this study showed that the highest growth rate is when the sample is exposed to green light for three to five days. The best amount of extraction for distilled water and at a refrigerator temperature (0◦C) with a ratio of 3:1 biomass/solvent is equal to 0.03 ± 15 µg/ml. Also, at the environment temperature, phosphate buffer is a more suitable solvent for extracting phycocyanine at a ratio of one to two with a value of 0.05 ± 8 µg/ml. In general, it can be said that the growth rate, pigment production and optimum extraction conditions for each species are quite different, and the optimal extraction of phycocyanin in a species is also dependent on various factors such as time, temperature, solvent and the ratio of biomass to solvent.
, Hamidreza Ehteram, Alireza Aghaei,
Volume 13, Issue 10 (1-2014)
Abstract
Abstract- The present study aims to investigate numerically the natural convection of various nanofluids inside a square enclosure with a central heat source at different aspect ratio. Also, some correlations are presented in order to calculate the Nusselt number in terms of Rayleigh number and volume fraction of nanoparticles. The heat source and cavity walls are kept at constant temperatures of Th and Tc, respectively. The nanofluids are considered to be water as the base fluid and different nanoparticles such as Cu, CuO, Ag, Al2O3, or Tio2. To discretize the governing equations, the control volume method and SIMPELER algorithm have been employed. The study has been carried out for aspect ratios from 0.2 to 0.8, Rayleigh numbers from 1e3 to 1e6 and the volume fractions of nanoparticles ranging in 0-0.05. The results indicated that the Nusselt number increases with increasing the volume fraction of nanoparticles as well as the aspect ratio. Furthermore, by increasing the Rayleigh number, some eddies, of kind of Rayleigh-Benard, are developed in the space between the heat source and the upper wall of the enclosure. Based on the obtained results, several correlations with high accuracy have been present in order to evaluate the Nusselt number.
Arian Ehterami, Payam Saraeian, Shahram Etemadi Haghighi, Mahmoud Azami,
Volume 17, Issue 12 (2-2018)
Abstract
The main purpose of using scaffolds replacement tissues of the body. The most important part is to choose the type and steel scaffolding so that eventually will replace the damaged tissue. One of the mechanisms proposed to reshape the bone is based on its piezoelectric properties. It seems that the use of piezoelectric materials is an option for use in the body, is a unique privilege. Therefore, the ceramic barium titanate (BaTiO3) having good piezoelectric properties, Curie temperature of about 125˚C and laboratory observations that non-toxic in the body, as a candidate to replace and simulate the performance of bone tissue, has been proposed. In this study, the design and produce of barium titanate piezoelectric ceramic as a bone scaffold with foam casting method and become coated with gelatinous and nanostructured HA composite for bone tissue engineering. Then test its properties by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and mechanical properties were studied. In the end, it was concluded that the barium titanate scaffold produse with foam casting method coated with gelatin nano hydroxyapatite composite structure suitable for use in bone tissue engineering.
Volume 18, Issue 116 (October 2021)
Abstract
Introduction: Colors are among the food additives that are added to increase the attractiveness of food and are very important in the industry to attract customers. Colors can have asthma-like effects, hyperactivity in children, weakened immune systems, anaphylactic reactions, or even cancerous effects. The purpose of this study is to investigate the status and abundance of artificial colors used in various meat products offered in Yazd.
Materials and methods: 299 samples of meat products were randomly sampled and after extracting the dye with hydrochloric acid and purification according to the national standard of Iran No. 2634, they were analyzed by chromatography with a thin layer of color type.
Result: The results showed that out of 38.127% of the samples that had color, 47.37% of the samples had artificial colors, 44.74% of the samples had unauthorized colors and 7.89% of the samples had both colors.
Discussion: The unauthorized use of artificial colors in food preparation has raised many health concerns. Knowing the reasons for using these colors, especially the unauthorized color of tartarazine, as well as raising public awareness, especially those related to the production of products and food, can facilitate planning and management and control measures and be an important step to maintain community health.
A. Heidary, M.a. Ehteram,
Volume 20, Issue 2 (February 2020)
Abstract
In the present paper, the performance of a shell and tube heat exchanger in which its cold working fluid is water and its hot working fluid is flue gases from natural gas-fueled internal combustion engine with working power of 15.4 kW was investigated. At first, with changing temperature and flow rate of inlet water, the performance of heat exchanger in both condensation and non-condensation situations was experimentally studied in the laboratory in order to have a criterion for validation of the simulations results in future. By comparing different simulation models in Aspen B-JAC software, the least error simulation model was chosen to do the other costly and impossible analyzes numerically in the laboratory environment. The study of the effect of the tube’s inner diameter on the heat exchanger’s performance in condensation situation showed 5.4% increase in the heat transfer while inner diameter decreases from 7 to 6 mm. The separation of the different heat transfer stages showed 26.4% of the latent heat transfer in the maximum discharge experiments for the inner diameter of 6 mm. Finally, the engine/heat exchanger set was assessed as micro combined heat and power and assumed that the heat exchanger is used for providing hot water for a 4-person family house in Tehran and the combustion engine is used for generating electrical power. This set was able to provide hot water during 9 warm months of a year by 1-hour work per day with 29% decrease of fuel consumption in comparison with traditional burners and at the same time, this set provides almost twice the electrical power requirements.
