Sharif Digital Repository

The most important desire of all researchers in food industry is decreasing the contamination of foods and increasing their shelf life. Due to harmfulness of chemical preservatives their use has been limited and therefore natural antimicrobials have been demanded. Recently spices have been noticed as natural antimicrobial agents. Sumac is a kind of spice which has antibacterial and antioxidant activities.The aim of this project is to investigate effects of water and alcoholic extracts of Iranian red sumac comparatively on three gram positive bacteria (Bacillus coagulans , Bacillus subtilis, Staphylococcus aureus) and one gram negative (Escherichia coli) by well and disk diffusion method.... 

Energy and environmental crises force different countries to consider new clean sources of energy, especially renewable energies. Fortunately, Iran is located on the solar belt and has a great potential to utilize this huge source of clean, sustainable, accessible and cheap energy. One of the applications of the solar energy is desalination of salty and polluted waters. In this regard, the performance of Multiple Active Solar Stills is investigated in this research. To do so, four similar samples of this device with one, two, three and four stages, were constructed on which many experiments were conducted for 24 hours periods. Experiments were conducted in both continuous (several days) and... 

The voice biometric is used in today’s telephone based speaker verification because of its unique feature for remote access. However, there are significant challenges in implementing such systems. One of these challenges is the need for sufficient data in the enrollment phase. In fact, the speaker verification system needs a dataset that covers phonetic variations of the language to be able to discriminate between different speakers. In real applications it’s not easy to ask the speakers to say long utterances. Therefore, an ideal speaker verification system should be able to find imposters without any constraint on the input lexicon whether the utterances are long or short.The results of... 

This practice investigates about the resistance & sustainability of a sample of available microorganisms in fruit juices vs. a natural anti microbe called vanillin. To be more precisely the anti bacterial characteristic of vanillin has been tested against famous pathogenic organism Escherichia Coli in apple juice. The practice has been experienced for different concentrations of Vanillin, controlling & reducing the microbe concentration in apple synthetic juice. The effect has been investigated by measuring sensitivity of results in two different temperatures one in 8 degree of centigrade & other in 15, in each temperature two PH have been tested (PH = 3.5 & 4.5) 0-40-80 m-molar as 3... 

Hydrogels are polymeric three-dimensional networks able to swell in the presence of an aqueous medium. Hydrogels from natural proteins and polysaccharides are ideal scaffolds for tissue engineering since they resemble the extracellular matrices of tissue comprised of various amino acids and sugar-based macromolecules.The biocompatible and biodegradable hydrogel scaffolds are promising materials for tissue engineering. Here, we report a new class of hydrogels derived from oxidized alginate (OA) and gelatin. The prepared oxidized alginate was shown to be efficient in crosslinking gelatin, leading to hydrogel formation. The effect of degree of oxidation and concentration of OA on the mechanical... 

An antioxidant is a molecule capable of preventing the oxidation of other molecules and neutralizing free radicals. Free radicals are the root cause for many human diseases.Rice bran is one of the most important co-products in the rice milling.In this research antioxidant activity of two Iranian rice bran varieties Fajr and Tarem, extracted by three different solvents (methanol, ethanol and ethyl acetate),determined at different time of extraction by measurement of total phenolic content, free radical scavenging, inhabitation of linoleic acid peroxidation and reducing power. The methanolic extract of Fajr rice bran produced strong results in antioxidant activity. The amount of Total... 

Generally, the concept of producing ‘spare parts’ of the body for replacement of damaged or lost organs lies at the core of the varied biotechnological practices referred as tissue engineering. Tissue engineering is an interdisciplinary field that incorporates principles of engineering with the life sciences. Tissue engineering is based on three principle; cells, scaffolds for cells expansion, attachment as an environment like ECM and growth factors. These things together can help tissue engineers to provide microenvironments which are suitable for special cells. The most important thing in this kind of works is the ability to simulate environment for cells the same as body. According to the... 

Food rich in antioxidants plays an essential role in the prevention of diseases and plum is an example of these food .Our objective in this research was to determine the amount of variation in total phenolic compound present in plum fruits, so that it can be utilized in breeding programs to enhance the health benefits.Total phenolic content of the fruits, which were determined in 7 genotypes by using 4 solvents (water , methanol , ethanol , acetone) to extract phenolic compound, ranged from 178 to 497 mg/100 gr for methanol, from 306 to 407.33 mg/100 gr for ethanol , from 300 to 392 mg/100 gr for acetone and from 193 to 281.25 mg/100 gr for water. The results show that the methanol...