Showing 5 results for Pakravan
Volume 18, Issue 110 (April 2021)
Abstract
Nowadays the nutritional specifications of wheat bread have been more considered, this purpose would have done by mixing different materials with wheat flour. The bran is one of the materials that had more been considered by researchers, due to its nutritional and technological properties. Therefore, in current research, the effects of adding different percentages of bran (10 and 20 percent) with different particle sizes (tiny and coarse) on the sangak bread was evaluated. The rheological properties of dough investigated by the farinograph and extensograph and textural properties of bread analyzed using texture analyzer. The results revealed that adding wheat bran resulted a decrease in weight loss and an increase in moisture content of sangak bread. Adding wheat bran increased the water absorption capacity up to 11.35%. The elasticity of dough in samples containing wheat bran varied from 74.87 to 112.62. Dough samples made from whole flour had the highest amount of consistency with 337.5 BE in 50mm. Hardness of bread with 20 percent of tiny bran was 4132g that was the highest comparing with other sangak bread samples. Sensory scores showed that sangak bread made from flour formulated with wheat bran have not been taken into consideration by the panelists group, although adding wheat bran due to better technological properties.
Volume 19, Issue 3 (11-2016)
Abstract
Objective: Cell-derived microvesicles are described as a new mechanism for cell-to-cell communication. Stem cell-derived exosomes have been described as a new mechanism for the paracrine effects of mesenchymal stem cells (MSCs). In this regard, exosomes may play a relevant role in the intercellular communication between MSCs and tumor cells.
Methods: Exosomes were purified from the conditioned medium of MSCs by differential centrifugation. Exosome size and morphology were examined by scanning electron microscope and sized with dynamic light scattering (DLS). Western blot analysis confirmed the exosomes by using CD9 as a marker. Purified exosomes were labeled with a PKH26 red fluorescent labeling kit. The labeled exosomes were incubated with SKOV3 ovarian tumor cells for 12 h at 37°C, and we used an inverted fluorescence microscope to monitor cellular uptake.
Results: Scanning electron microscopy revealed that the purified MSCs-derived exosomes had a spherical shape with a diameter of approximately 30-100 nm. Exosome size measurement by dynamic light scattering analysis also showed a single bell-shaped size distribution with a peak of ~80 nm. Western blot analysis also demonstrated the presence of CD9 (a representative marker of exosomes) in the purified exosomes. These data confirmed that the vesicles isolated from MSCs-conditioned media were the exosomes based on their size and presence of the protein marker CD9. Florescent microscopy showed that PKH26-labeled exosomes could be taken up by SKOV3 tumor cells with high efficiency.
Conclusion: Our approach for isolation, characterization and cellular uptake of exosomes derived from MSCs is valuable and a prerequisite for future studies that intend to discover exosome function in tumor cells. The ability to study the biology of exosome uptake in cancer cells could provide opportunities for functional studies of these natural nanovesicles and their contents in cancer therapy.
Y. Maaref, H.a. Pakravan, Kh. Jafarpur,
Volume 19, Issue 7 (July 2019)
Abstract
During the last 3 decades, different therapeutic methods have been used for cancer treatment. Hyperthermia is one of these methods, which destroys the tumor cells with applying temperatures about 41-46°C. Thermal ablations of hepatic tumors near large blood vessels are affected by the heat sink effect of blood vessels. In this study, the heat sink effect of blood vessels on hepatic mono-polar radiofrequency and microwave ablation was investigated. The simulation is performed by numerical solution of bio-heat transfer equation with equations of electrical current or electromagnetic waves. To analyze the heat sink effect of blood vessels, the tissue is modeled with and without blood vessel. The fraction of necrotic tissue is determined for 3 different diameters of blood vessels including 5, 10, and 15 mm. The results show that when the applicator distance to the blood vessel is less than or equal to 8 mm, the necrotic value significantly decreases and the heat sink effect becomes important; however, for distances larger than 30 mm, the necrotic value does not change and the heat sink effect is diminished. The heat sink effect increases with blood vessel diameter due to the blood flow increase. In addition, the results indicated that
the microwave ablation is less affected by the heat sink effect in comparison with the mono-polar radiofrequency.
M. Pakravan, M. Farahani,
Volume 20, Issue 4 (April 2020)
Abstract
Nowadays, the use of a non-contact digital imaging system for non-destructive testing on composite materials has received much attention because of its advantages. In this research, the shape, position and area of the breakdown region in glass/epoxy samples with blind holes and different depths under tensile loading have been investigated using a non-contact digital imaging system. Specimens with a 10 mm diameter blind, depths of 0.5, 1 and 1.5 mm, and an average thickness of 4 mm have been subjected to the tensile loading. Lateral strain contours for all three samples have been obtained at different loads. By increasing the lateral strain loading, it focuses on an area on the surface of each specimen that corresponds to the position of the blind hole. Then the lateral strain is measured separately in length and width for each specimen. Increasing the amount of loading and the depth of the breakdown have resulted in greater strain concentration in the breakdown area as well as increasing the accuracy of the digital images correlation system. The position, shape, area, and diameter of the blind hole measured by digital image correlation method have been compared with real values, which considering the acceptable consistency of the results of the digital image correlation method with the features of each sample, It can be used as an efficient method for detecting and evaluating failures in composite structures.
Mohammadjavad Pakravan, Mohammadreza Farahani, Amin Barzegar, Mehdi Mahmoudi,
Volume 22, Issue 3 (March 2022)
Abstract
The use of non-destructive tests on composite materials to inspect, identify and observe defects to locate discontinuities or defects has received much attention in recent years. Among the existing methods, the use of a non-contact digital image correlation system for troubleshooting composites has been considered because of its advantages. In this study, using the digital image correlation method, the shape, position, and area of the failure area in six-layer glass/epoxy samples with impact damage with different energies under different loading amounts have been investigated. Five composite specimens with impact energies of 5, 10, 20, 30, and 40 joules were tested. At 5 joules of energy, the damage to the piece was very small, and at 40 joules, the amount of damage to the piece was such that the bullet was stuck inside the piece and the impact site remained as a hole in the piece. The areas obtained for the impact area in the strain contours at 40% load have values close to the actual area of damage. By comparing the area obtained from the strain contour at 40% load and the actual area of damage, for 10 joules, 20 joules, and 30 joules, the difference in areas obtained is about 2.3%, about 2.5%, and 3.1%, respectively.
