Sharif Digital Repository

In this study, biodegradation of corn starch/glycerol/Na-MMT nanocomposites by soil burial tests were carried out for up to 6 months. Films were prepared by casting method according to central composite design and response surface methodology was applied for analysis of the results. The effects of formulation on the water solubility, contact angle and tensile strength of starch films were investigated. Increasing in Na-MMT content decreased biodegradability; while presence of glycerol, increased it. The effect of nanoparticles content might have been attributed to interactions between starch and Na-MMT that further prevented enzymatic attack on the biopolymer. In addition, the films with... 

A novel implementation of a membrane bioreactor (MBR) has been studied in this paper. It is utilised as combination of rotating biological contractor (RBC) and an external membrane for oily wastewater treatment. The performance of MBR was compared with the standalone RBC. The RBC used in this investigation is the same one combined with the membrane to form the MBR. Wastewater biodegradability has been evaluated by two factors: chemical oxygen demand (COD) and total petroleum hydrocarbon (TPH). They are both compared together for different hydraulic retention times (HRTs) and petroleum pollution concentrations in RBC and MBR. The ratio of TPH to COD of molasses has been varied between 0.2 to... 

Background: In the recent study, optimum operational conditions of cathode compartment of microbial fuel cell were determined by using Response Surface Methodology (RSM) with a central composite design to maximize power density and COD removal. Methods: The interactive effects of parameters such as, pH, buffer concentration and ionic strength on power density and COD removal were evaluated in two-chamber microbial batch-mode fuel cell. Results: Power density and COD removal for optimal conditions (pH of 6.75, buffer concentration of 0.177 M and ionic strength of cathode chamber of 4.69 mM) improve by 17 and 5%, respectively, in comparison with normal conditions (pH of 7, buffer concentration... 

The gelatin/gum arabic microcapsules encapsulating peppermint oil were prepared by complex coacervationusing tannic acid as hardening agent. The effects of various parameters, including concentration of wall material, core material, tannic acid and Tween 80 were investigated on particle size and encapsulation efficiency. For statistical evaluation of the parameters, Taguchi method was concerned. The size of prepared spherical microcapsules was 19-66 micrometers. The results showed that, particle size increased with increasing the core and the wall concentration and decreased with increasing tannic acid and Tween 80 concentraIfd efficiency increased by increasing the core and wall... 

In this research, response surface methodology (RSM) was applied to study the effects of Na-Montmorillonite (Na-MMT) and glycerol on some functional properties of corn starch films. Films were prepared by casting method according to central composite design (CCD). Originally image processing technique was used in order to estimate transparency of the films. It was found that Na-MMT absorbed UV light from 216 to 266. nm. No antimicrobial activities were observed against Escherichia coli and Staphylococcus aureus. Contact angle analysis revealed hydrophilicity of starch films decreased utilizing nanoparticles and increased with plasticizer content. Increase in glycerol content decreased... 

In order to produce bioethanol from agricultural residues such as wheat straw, the decomposition lignocellulosic materials into soluble sugars is necessary. This work focused on the influence of dilute sulphuric acid pretreatment conditions on sugar removal and the enzymatic saccharification of wheat straw. Response surface methodology (RSM) based on rotatable central composite design (RCCD) was used to optimise H 2SO 4-catalysed hydrothermal pretreatment of wheat straw, in respect to acid concentration (0.75-2.25%), treatment time (10-30min) and temperature (120-160°C). The pretreated wheat straw was hydrolysed by a standard blend of Cellusoft CR ®. Enzymatic hydrolysis was also measured to... 

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) was evaluated. The order of antioxidant activity was evaluated by measurement of total phenolic content, antioxidant activity in linoleic acid system, reducing power and scavenging capacity by DPPH radical. The methanolic extract of Fajr rice bran showed a total phenolic content of 3.31 mg Gallic acid/gr rice bran and a DPPH free radical-scavenging activity of 93.91%, achieved at 50 mg/ml concentration, and a percent inhibition of linoleic acid peroxidation... 

This paper discusses the studies carried out for the optimal production of enzyme l-asparaginase (l-asparagine amidohydrolase, EC 3.5.1.1) from Escherichia coli (ATCC 11303). It was found that inoculum age of 18 h and inoculum size of 10% were the most favorable operating conditions for enzyme production. Lactose, yeast extract and KH 2PO 4 were found to be the best carbon, nitrogen and ion sources, respectively. Statistical method was used to survey how various medium conditions affect the enzyme production. By response surface methodology, the values of lactose, tryptone, yeast extract, KH 2PO 4 and l-asparagine concentration were investigated to obtain the maximum enzyme activity. The... 

Palm oil (PO) and sunflower oil (SFO) blends with varying proportions were subjected to enzymatic interesterification (EIE) using a 1,3-specific immobilised lipase. The interesterified blends were evaluated for their slip melting point (SMP), solid fat content (SFC) at 10-40°C, p-anisidine value, peroxide value, free fatty acids (FFA), induction period of oxidation at 110°C (IP110) and composition of fatty acids by gas chromatography. Under EIE treatment, the blends of PO and SFO in different proportions (20:80, 40:60, 50:50, 60:40 and 80:20) had saturated and unsaturated fatty acid content in the range of 37.6-52.0% and 48.0-62.4%, respectively. The blends showed a considerable reduction in... 

L- asparaginase enzyme is a renown enzyme because of its chemotherapeutic properties. This enzyme may also be employed in food processing technology. The present study aimed, optimizing the agitation and aeration rate in L-asparaginase production, using C. utilis, ATCC 9950 in batch fermentation system. Beet molasses used as the carbohydrate source for enzyme production. A maximum asparaginase activity of 245.6 U/ml obtained after 20h of fermentation under optimal condition of 1.25 vvm aeration rate and 300 rpm agitation speed. Purification of the enzyme was also done by Acetone Precipitation and column chromatograph. Purified L-asparaginase revealed molecular weight 75 kDa and 82.7 % yield... 

An effective process for reducing milk cholesterol by enzymatic treatment was investigated in this study. Cholesterol oxidase from Nocardia erythropolis was used for this purpose. The target of this investigation was to obtain the optimum operational conditions for bioconversion of milk cholesterol by cholesterol oxidase (COD). The bioconversion process was investigated first, to obtain basic information about the process, and was further optimised by analysing the parameters, including temperature, pH, incubation time and enzyme content, by using the Taguchi Approach, which is a statistical method for optimisation. Also the direct effect of each parameter on cholesterol bioconversion rate... 

Doxorubicin-loaded nanocarriers were produced employing folate-modified polyethylene glycol (PEG)-functionalized gold nanoparticles for targeted delivery to positive folate-receptor cancer cells. Doxorubicin and folate were, respectively, conjugated to activated-folate and activated-PEG. The conjugates formed doxorubicin nanocarrier with an average size of 12 nm in diameter. The drug release response of functionalized gold nanoparticles was characterized by an initial rapid drug release followed by a controlled release. The doxorubicin nanocarriers showed higher cytotoxic effect on folate-receptor-positive cells (KB cells) than folatereceptor-negative cells (A549 cells). Cell viability in... 

Partial purification of plant peroxidase from turnip (Brassica rapa) was optimized. Aqueous two phase system and precipitation by ammonium sulfate (as two parallel purification methods) were used. Polyethylene glycol/ammonium sulfate/NaCl (25:7:3%, w/v) system followed by gel-filtration chromatography gave a purification factor of about 36 fold. On the other hand, ammonium sulfate precipitation (60-80% deg) followed by gel filtration gave only about 13 purification fold. Hence, the aqueous two-phase system was more efficient and useful method as a primary purification step since it was less laborious, less time-consuming, and led to more purification factor. The partially purified turnip... 

Conjugated Linoleic Acid (CLA), Glycerol (G) and sunflower oil blends with varying concentration were subjected to enzymatic esterification using a 1, 3-specific immobilized lipase. CLA was used as acyl due to its purported health benefits. The transesterified lipids were evaluated for free fatty acids (FFA) and composition of fatty acids by gas chromatography. Lipozyme RM IM is preferred for enzymatic esterification because of more CLA incorporation and less free fatty acids at the end of reaction than Lipozyme TL IM. Response surface methodology (RSM) was used to determine the effects of three variables Glycerol concentration, reaction temperature, and amount of enzyme on the lipase... 

Conjugated Linoleic Acid (CLA) was produced from castor oil using washed cells of Lactobacillus plantarum PTCC 1058 and Lactobacillus plantarum subsp. plantarum PTCC1745 as the catalyst. Under the optimal reaction conditions, the washed cells of Lactobacillus plantarum PTCC1058 produced 1661.26 mg of CLA/L reaction mixture (36% yield of production) from 4.6 mg/ml of castor oil after using 15% (w/v) cell for 121 h. The resulting CLA was a mixture of two CLA isomers, cis-9, trans-11 (or trans-9, cis-11)-octadecadienoic acid (CLA1, 44% of total CLA) and trans-10, cis-12-octadecadienoic acid (CLA2, 46% of total CLA). The total production of CLA is extracellular in all of the reactions performed... 

In this study, anti-leukemic enzyme L-asparaginase (E.C.3.5.1.1) from Escherichia coli ATCC 11303 was modified by the microencapsulation technique onto calcium alginate beads. Using response surface methodology (RSM), a three-level full factorial design, the values of concentration of sodium alginate, concentration of calcium chloride, and enzyme loading were investigated to obtain the highest residual L-asparaginase (L-ASNase) activity % (immobilized enzyme activity/free enzyme activity). The effects of the studied factors on immobilization were evaluated The predicted values by the model were close to the experimental values, indicating suitability of the model. The results presented that... 

Background and Objective: Since ancient times, it has been said that drinking green tea brings relaxation. The substance that is responsible for a sense of relaxation is theanine. Theanine (γ-glutamylethylamide) is a unique non-protein amino acid. It gives an umami taste and a unique flavor to the tea, and has many physiological and pharmaceutical effects such as anti-tumor, anti-cancer, neuro-protective, anti-hypertensive and anti-obesity effects; it may further help in relaxation and increase focus. So this compound is essential for human body; however, it is not synthesized in the body and should be administrated orally. In the present study, the enzymatic biosynthesis of theanine was... 

In the present study, Lactobacillus plantarum PTCC 1058 was microencapsulated in Alginate-chitosan blended beads based on ionically dual cross-linking by Na-tripolyphosphate (Na-TPP). The homogenous solution of bacteria and alginate was dripped into the gelling bath of calcium chloride. After 30 min hardening, filtrate beads were transferred into the solution of chitosan. Dual cross-linked gel beads were prepared by employing Na-TPP solution to the chitosan coated beads. Morphology, particle size, alginate-chitosan interaction, characterizing the structure of single and dual cross-linked beads were determined by using scanning electron microscopy SEM, FTIR and XRD analysis. FTIR analysis... 

Background and Objective: Acrylamide as a toxic substance for human beings is produced by Maillard reaction at high temperatures. In this research, this reaction can be inhibited based on using aspariganse enzyme, controlling the cooking time and temperature during baking in yeast-leavened bread. Materials and Methods: In this study, a response surface methodology 5-level-3-factor central composite design was applied to study the effects of asparaginase (300-900 U Kg-1 of flour), baking temperature (230-280°C) and baking time (13-16 min) on acrylamide formation in yeast-leavened wheat bread. Results and Conclusion: Added asparaginase showed a reducing effect on acrylamide formation... 

In this study, synthesis of conductive metal nanowires by using aligned and immobilised DNA strand on solid substrate is reported. The nanoporous gold film was prepared by electrostatic self assembly of gold nanoparticles capped with tryptophan. Tryptophan would improve surface properties of gold nanoparticles for strongly attaching to DNA. Fourier transform infrared (FTIR) spectroscopy confirmed that gold nanoparticles have been capped by tryptophan. Also measured zeta potential shows that there are positive charges on the surface of gold nanoparticles. Investigations by AFM observati on substantially confirm that tryptophan-capped gold nanoparticles can be bonded to DNA template...