Showing 58 results for Silver
Volume 0, Issue 0 (1-2024)
Abstract
This study aimed to increase the vase life of cut rose flowers by improving the regulation of Programmed Cell Death (PCD). Experiments were carried out on cut rose (Rosa hybrida cv. Dolce vita+) flowers under either physical treatment of Static Magnetic Field (SMF; 15 and 25 mT) for 3 hours, or chemical treatments of silver nano particle (Nano-Ag; 5 and 10 ppm), 6-Benzyladenine (BA; 25 and 50 mg L-1), 1% sucrose, and combinations of 5 and 10 ppm nano-Ag with 3 and 6% sucrose. Results showed that a 15 mT-SMF significantly increased vase life up to 25 days, compared to the controls and to all chemical treatments. Among the chemicals, 5 ppm Nano-Ag and 1% (w/v) sucrose increased vase life to 23 and 18 days, respectively. The smallest decline in fresh weight was observed in the 15 mT-SMF physical treatment. Markedly, the 15 mT-SMF treatment led to the least reduction in Chlorophyll (Chl) content. On the 17th day of the applied different treatments, both Water Uptake (WU) and Relative Fresh Weight (RFW) showed an inverse significant relationship with PCD in cut rose flowers, verifying there markable delayed PCD which is favored the market. As a whole, the most effective induced treatments (15 mT-SMF, 5 ppm Nano-Ag, and 1% Sucrose) are suggested to be promising for enhancing postharvest quality and prolonged vase life of cut rose flowers.
Volume 1, Issue 1 (3-2013)
Abstract
Uncoated fish burgers were produced in order to expand the variety of products from Silver carp, Hypophthalmichthies molitrix ,and increase the consumption of this fish species. On the other hand in order to compare the effect of ascorbic acid and vacuum packaging on rancidity inhibition and microbial quality, 3 different treatments of fish burger were produced: 1. Burger with common packaging (Control group), 2. Burger with vacuum packaging 3. Burger with 500 ppm ascorbic acid in common packaging. All the treatments were stored in -18 ºC for 6 months after freezing by a spiral freezer in -35 ºC. Chemical, microbiological and sensory evaluations were determined from time 0 and after that monthly until the 6th month. The TVB-N value increased during the storage period but it never passed out of the standard range. The TBA value increased in all treatments but in ascorbic acid treatment it was significantly lower than the other two groups. The pH amounts during storage period decreased in all treatments homogeneously. Microbial counts in all treatments and especially in vacuum packed burgers decreased during the storage period. Organoleptic test demonstrated the preference of burgers treated by ascorbic acid. The shelf life of control group and burgers with vacuum packaging was determined 3 months at least. The shelf life of treated burgers with ascorbic acid was determined about 6 months specially based on the TBA index and sensory evaluation. Vacuum packaging was more effective to protect burgers of chemical and microbial changes compared to common packaging.
Volume 1, Issue 3 (9-2013)
Abstract
Some Biochemical properties of silver carp surimi prepared by application of acid-alkali aided methods were investigated and compared to that of derived by conventional method. In terms of total protein solubility and recovery, lipid reduction, and total pigment extractability and myoglobin removal there was a significant (P<0.05) difference among the treatments. Acid-aided method showed the most efficiency to recover more proteins (86.2%) in comparison to the alkaline-aided (79.8%) and conventional (76.7%) methods. The lipid reduction percentage was recorded as 43.6%, 58.4% and 72.3% for the conventional method, and acid-alkali aided methods, respectively. In terms of total pigment removal, the conventional method showed higher efficiency (P<0.05) compared to the pH-shifting methods. Conversely, fish protein solubilisation by acid-alkali aided techniques was more efficient (P<0.05) compared to the conventional method of making surimi. In conclusion, pH-shifting techniques were superior in comparison with the conventional method in order to recover more functional proteins and to efficiently reduce the lipid and myoglobin content of resultant fish protein isolate.
Volume 1, Issue 3 (9-2013)
Abstract
In order to understand the importance of particle size and agglomeration for nano-eco-toxicological studies in aquatic environments, the acute toxicity of two different types (suspended powder and colloidal) of silver nanoparticles (AgNPs) were studied in alevin and juvenilerainbow trout. Fish were exposed to each type of AgNPs at nominal concentrations of 0.032, 0.1, 0.32, 1, 3.2, 10, 32, and 100 mg/L. Lethal concentrations (LC) were calculated using a Probit analysis. Some physical and chemical characteristics of silver nanoparticles were determined. In the case of colloidal form, particles were well dispersed in the water column and retained their size; but in the case of suspended powder, particles were agglomerated to large clumps and precipitated on the bottom. In alevins, the calculated 96 h LC50 values were 0.25 and 28.25mg/L for colloidal and suspended powder AgNPs respectively. In the case of juveniles, the 96h LC50 of colloidal form was 2.16mg/L, but suspended powder did not caused mortality in fish even after 21 days. The results showed that both in alevin and juvenile stages, colloidal form is much toxic than suspended powder; this shows increase of nanoparticles size due to agglomeration, will reduce the toxicity. Silver nanoparticles are toxic materials and their release into the water environment should be avoided.
Volume 2, Issue 3 (7-2016)
Abstract
Background: This study was performed to determine antifungal activity of silver nanoparticles (nano-Ag) compared to voriconazole on clinical and standard strains of Aspergillus fumigatus.
Materials and Methods: Inhibitory potency of nano-Ag was determined using microtiter broth dilution method. Susceptibility tests were performed against A. fumigatus isolated from BAL (bronchoalveolar lavage) of patients who suffered from respiratory problems and compared with the strain (ATCC: 204305) by broth dilution antifungal susceptibility test of filamentous fungi approved by the Clinical and Laboratory Standards Institute M38-A. In addition, cytotoxicity effect of silver nanoparticles was studied on epithelial cell line by MTT assay.
Results: From 60 BAL samples the following strains were isolated; A. flavus (n=21), A. niger (n=3), and A. fumigatus (n=1). The minimum inhibitory concentration (MIC90) values of nano-Ag were 0.25 and 0.5 μg.mL-1 for standard strain and clinical isolates respectively. The Minimum Fungicidal Concentration (MFC) values of nano-Ag were 0.5 and 1 μg.mL-1for standard strain and clinical isolates respectively. MIC90 values of voriconazole were 0.125 and 0.25 μg.mL-1 for standard strain and clinical isolate respectively. The MFC values of voriconazole were 0.25 and 0 μg.mL-1 for standard strain and clinical isolates respectively. Silver nanoparticles exhibited low cytotoxicity in 0.25 μg.mL-1 concentration.
Conclusion: Our results showed high antifungal activity of silver nanoparticles against Aspergillus isolates. Furthermore, the availability of a wide form of nano-Ag structures can be considered as novel agents to decrease fungal burden in medical application.
Behrooz Mohamadi, Mojtaba Salouti, Ali Haniloo,
Volume 3, Issue 2 (11-2012)
Abstract
In biological methods, microorganisms such as bacteria, fungi, actinomycets and yeasts are used to produce metal nanoparticles. Fungi are extremely good candidates in the synthesis of silver nanoparticles because of their ability to secrete large amounts of enzymes. The aim of this study was the biosynthesis of silver nanoparticles by Penicillium spp. isolated from the soil of plump and zinc mine in Zanjan city (Iran). After culturing, growth of colonies and isolation of Penicillium spp., 15 g of the fungal biomass was mixed into 1 mM silver solution for 72 h incubation. The production of silver nanoparticles was characterized by UV-vis spectroscopy, X-ray diffraction(XRD) and transmission electron microscopy. Among the sixteen kinds of isolated fungi, six species were recognized as Penicillium of which just the fungus Penicilliumbrevicompactum was found to be able to produce silver nanoparticles. The production of silver nanoparticles was preliminarily approved by observing the color change of the reaction solution from colorless to yellowish brown. The synthesis of silver nanoparticles was confirmed by observing the characteristic peak at 406-425 nm. The presence of crystalline silver nanoparticles was confirmed by observing peaks in (111), (200), (220), (311) in the XRD analysis. Transmission electron microscopy images showed that silver nanoparticles were produced in the size range of 50 -100 nm in spherical shape mainly extracellular at the surface of mycelium. The fungus was recognized to be Penicilliumbrevicompactumusing slide culture method, growth on Czapek yeast agar and Keratin-sucrose agar.
Volume 3, Issue 3 (12-2019)
Abstract
Superabsorbent hydrogel is a three-dimensional hydrophilic polymer that can absorb and store large amounts of water and aqueous solutions. Among various polymers, the chitosan as a biodegradable and non-toxic polymer has been widely used to fabricate superabsorbent hydrogels. In this research, a nanohydrogel composed of chitosan, acrylic acid and silver nanoparticles was synthesized by radical polymerization at 60 Co. Swelling properties of chitosan/nanosilver/acrylic acid hydrogel were studied and then this hydrogel was treated under ultrasonication. Finally, this hydrogel was coated on paper samples with 0, 1, 1.5 and 2 w % of hydrogel. FTIR spectroscopy was used to determine the functional groups and dynamic light scattering method (DLS) was applied to identify the size of hydrogel’s nano and microparticles The images of scanning electron microscopy (SEM) showed a hydrogel coating on paper and water stress tests revealed that adding 0% to 1.5 w% of nanohydrogels to the paper surface increased its water absorption from 64.3% to 95.5%. Other worthwhile fact was that that the addition of silver nanoparticles effectively facilitated the formation of a three-dimensional hydrogel structure and increased the water swelling in nanohydrogel from 130 ± 10 g / g to 232 ± 7 g / g.
Volume 4, Issue 3 (12-2015)
Abstract
The effect of ice-storage duration (0, 3, 6, 9, 12, and 15 days) of silver carp (Hypophthalmichthys molitrix) on qualitative properties of its surimi powder was assessed by analyzing proximate composition, color changes, density, oil adsorption capacity, protein solubility, emulsifying capacity, emulsion stability, gel forming ability, and thiobarbituric acid. Increase in ice-storage duration increased the density and thiobarbituric acid of surimi powder(p<0.05); proximate composition, color indices, protein solubility, oil adsorption and gel forming decreased significantly (p<0.05); emulsifying capacity and emulsion stability decreased with storage duration, although no regular trends were detected (p<0.05). The present study indicated that long-term ice-storage of silver carp led to reduction of qualitative properties of the surimi powder.
Volume 4, Issue 4 (3-2016)
Abstract
Carboxymethyl cellulose (CMC) and tragacanth gums at 0.5 and 1% levels % were added to the fish balls from silver carp to improve the its texture and sensory characteristics. The proximate composition, physical factors (batter pick-up, product yield, shrinkage and oil absorption reduction), sensory analysis and textural properties of fried balls were compared with the control treatment. All treatments showed less fat and oil absorption rate (p> 0.05) compared to the control treatment. Treatment containing 1% tragacanth gum showed the highest levels of wet, lightness, hardness and springiness, while treatment containing 1% CMC showed the highest product yield and lowest amounts of expressible water, fat, lightness, oil absorption and springiness (p>0.05). Overall, the performance of tragacanth gum on the texture characteristics was more desirable than CMC gum. All textural index decreased in treatments containing 1% gum. Hence, the use of low levels of the gums is recommended.
Volume 4, Issue 4 (3-2016)
Abstract
The effects of frozen storage (-20°C) of silver carp (Hypophthalmichthys molitrix) for periods of 0 (control), 2, 4 and 6 months on the qualitative properties of surimi powder was investigated. Qualitative characteristics were assessed through analysis of proximate composition, sensory evaluation, color changes, density, oil adsorption capacity, water holding capacity, protein solubility, emulsifying capacity, emulsion stability, foam capacity and stability, gel forming ability, and thiobarbituric acid value. Most of the qualitative indices decreased significantly (p<0.05) in the treatments, including the water holding capacity and the percentage of protein solubility that, respectively, decreased from 13.4ml/g and 7.42% in the control to 10.46 ml/g and 4.82% after 6 months of frozen storage. Besides, the treatments didn’t show foam. The density and thiobarbituric acid increased significantly with time (p<0.05). Based on the analyses as well as sensory assessment, quality of silver carp surimi powder was maintained in -20°C frozen storage up to four months.
Volume 5, Issue 1 (6-2016)
Abstract
Silver nanoparticles (AgNPs) are widely used in consumer products mainly due to their antimicrobial action. The rapid increase in the use of nanoparticles has driven more attention to their possible ecotoxicological effects. In this study: first, acute effects of colloidal AgNPs during embryonic stage of Persian sturgeon and Starry sturgeon were investigated and then in Starry sturgeon, their short-term effects during early life stages (before active feeding commences) were analyzed. Based on the obtained results from the acute toxicity tests, AgNPs induced a dose-dependent toxicity in both species during early life stages. The short-term toxicity test was performed using 0, 0.025, 0.05 and 0.1 mg/l of colloidal AgNPs. Silver accumulation in larvae exposed to 0.1 mg/l AgNPs was recorded significantly higher than the control treatment (P<0.05). However, the obtained survival rate data did not indicate any significant differences among treatments.
Volume 5, Issue 2 (9-2016)
Abstract
In this study the effect of edible coating containing pomegranate peel extract (PPE) on the quality and shelf life of silver carp (Hypophthalmichthysmolitrix)fillet was investigated during refrigerated storage at 4 Cº. The total phenolic content (262.5 mg tannic acid/g sample) and DPPH free radical scavenging activity (87%) of PPE using methanol as solvent were determined. The mixture of edible coating was prepared (60% cool water + 30% wheat flour + 10% corn flour). Freshly fish fillet were assigned to three treatments: control (fillet without PPE); fillet treated with 5% PPE (T1) and 10% PPE (T2). Chemical (pH, and thiobarbituric acid (TBA)) and microbiological (total viable count (TVC) and psychrotrophic count (PTC)) analysis were used to evaluated the effect of PPE during refrigerated storage. The results show that addition of PPE considerably delayed lipid oxidation in silver carp fillet in T1 and T2 compared with control samples. According to microbiological assay, T1 and T2 samples on 12th of storage reached to maximum acceptability limit (7 log10 CFU/g) while it was happened on 9th of storage for control samples.
Volume 5, Issue 3 (12-2021)
Abstract
Research subject: Biodegradable compounds with high mechanical and thermal properties are one of the intersting research topics. Polylactic acid is an aliphatic polyester with high biodegradability and flexibility. It, however, suffers from several weaknesses such as high permeability to water vapor and gases, low glass transition temperature, poor thermal stability and brittleness which can be improved by the incorporation of nano-scale fillers giving rise to bionanocomposites. The aim of this study was to investigate the effect of the simultaneous incorporation of cellulose nanocrystals and nanosilver on the mechanical, thermal and water vapor permeability behavior of polylactic acid-based films.
Research approach: Polylactic acid films and their bionanocomposites containing different levels of cellulose nanocrystals (0.01, 0.03 and 0.05 g) and nanosilver (0.01 g) were prepared by solution casting method. To improve compatibility and miscibility of the polymer, cellulose nanocrystals were reacted with acetic anhydride and modified. FTIR spectroscopy, tensile test, thermal properties (DSC), migration test and antibacterial properties were used to study the properties of the samples. The water vapor permeability of the samples were also measured.
Main results: The addition of cellulose nanocrystals, increased the glass transition temperature (Tg) and melting point (Tm) of the samples. The presence of cellulose nanocrystals increased the tensile strength and modulus of elasticity of the bionanocomposite relative to pure polylactic acid. With the addition of cellulose nanocrystals, permeability was reduced by about 25%. As the amount of cellulose nanocrystals increased, the swelling and water absorption of the samples increased significantly. The migration rate of the samples also decreased after the addition of nanocellulose.
Taher Mohasseli, ,
Volume 6, Issue 1 (10-2015)
Abstract
Nanotechnology involves technological research and development in spaces at the range of 1 to 100 nanometers, and in this technology, very small and atomic scale particles are created and handled. Plant extracts can be used as a green method for the synthesis of silver nanoparticles. In this study, the biosynthesis of silver nanoparticles was performed using extracts of sesame (Sesamum indicum) seeds. Silver nitrate was added to the seed extract, and then it was incubated at 30 ° C. The effects of three concentrations (1mM, 2mM and 3mM) of silver nitrate on the synthesis of silver nanoparticles were studied. The analyses of absorption spectroscopy UV-Visible, Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD) and Inductively Coupled Plasma (ICP) were conducted to assess the production of nanoparticles. UV-Visible spectroscopy analysis and the peak at 420 nm indicated the occurrence of nanoparticles in the extract. TEM image determined that the nanoparticles were spherical with average size of about 14 nm. XRD analysis showed the nano-crystals synthesized by the extract, and Inductively coupled Plasma (ICP) determined the conversion percentage of silver ion into silver nanoparticle as approximately 99.61 percent.
, ,
Volume 6, Issue 2 (11-2015)
Abstract
Introduction: Nanotecnology could solve most of problem of biomedical and cause improve in health and pharmacology field. Also this industrial cause to eliminate food pathogenic bacteria.increase of food pathogenic bacteria and resistance them to different antibiotics caused usage of nanotechnology by researchr and pharmacologiests. Material and Methods:In this reseach is studied antimicrobial effect of nanoparticles of silver,TiO2 against on food pathogenic bacteria such as Staphylococcus aureus PTCC 1431 and Listeria monocytogenes by determination MIC and MBC. Result: Silver nanoparticle was synthezied with 103 nm of size and consentraion of 1 mili molar,nano TiO2 with 21 nm of size and consentrain of 1% have antimicrobial effect against on Staphylococcus aureus PTCC 1431 Listeria monocytogenes . Conclusion: Since that antimicrobial activity of silver ,TiO2 nanoprticles against on food pathogenic bacteria (Staphylococcus aureus PTCC 1431 and Listeria monocytogenes) is proved, is suggested to packaging antimicrobial food. Keywords: Silver nanoparticle,TiO2,,Antimicrobial effect, Staphylococcus aureus PTCC 1431 Listeria monocytogenes
Volume 6, Issue 2 (9-2022)
Abstract
Research subject: In the present study, titanium dioxide/silver nanocomposites (TiO2/Ag) were synthesized by sol-gel method and their performance for photocatalytic removal of metribuzin was compared with commercial TiO2 catalysts P25 Degussa.
Research approach: The synthesized nanocomposites were evaluated using X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray analysis (EDX). The effect of operating parameters including reaction time (0-240 minutes), pH (9-4), catalyst dose (0.005-0.015 g), temperature (10-60 ºC), visible light and UV light radiation, concentration Initial metribuzin (10-25 mg/L), the catalyst effect in the dark, and the amount of silver in TiO2/Ag nanocomposites (0.10-7% by weight) were investigated on the photocatalytic removal of metribuzin from artificial and real aqueous solutions.
Main results: Laboratory investigations showed that TiO2/Ag nanocomposite containing 10% by weight of silver, reaction time of 120 minutes, pH equal to 6, catalyst mass of 0.013 g, and initial concentration of 10 mg/L metribuzin are the best properties to maximize the removal of metribuzin in the presence of UV light. The obtained results showed that the synthesized TiO2/Ag nanocomposite has a higher potential in the degradation of herbicides compared to the commercial TiO2 nano-catalyst. In addition, the proposed method was used to remove metribuzin injected into the water of the Karun and Zohreh rivers and the wastewater of the sugarcane factory under optimal conditions, and successful results were obtained. Also, the results of using and regenerating the titanium dioxide/silver catalyst three times to remove metribuzin show the high efficiency of this photocatalyst in removing metribuzin from water samples. Comparing the methods available in the literature for the removal of metribuzin with the present method showed that the proposed method is better or comparable to the reported methods.
Volume 6, Issue 3 (12-2017)
Abstract
To improve the texture and acceptance capabilities of silver carp burger and increase per capita consumption this product, the pectin was used as texture enhancers. Pectin is a polysaccharide that can be used in food to improve gel texture properties. In this research uses three different treatments, silver carp fried fish burger as control, fried fish burger with 0/3 % pectin as treatment 1, fried fish burger with 0/6 % pectin as treatment 2. Sensory evaluation and texture analysis tests was performed in zero phases and then monthly for six months and the results were compared with texture analysis. According to the results of the texture analysis of fish burger treatments, significant differences in the juiciness,overall acceptance was observed.The sensory evaluation index are also significant differences between fish burger formulated contains 0/3% pectin than the other two treatments was observed after six months storage at-18°C, therefor according to sensory evaluation and texture analysis, formulating fish burger contains 0/3% pectin most stable and acceptable formulation in terms of scoring during storage.
Volume 6, Issue 22 (10-2009)
Abstract
Washing operation with different dilutions of salt water (3,2,1,0.3) at different times (5,10 and 15 minutes) was used to reduce fishery odor from Silver and Big head carp fish pastes. Results showed that elimination of fishery odor increased while extraction of soluble proteins with salt water increased. Sensory analysis was used to determine the best formulae of 50,60 and 70 percent fish meat from the best eliminated fishery odor sample that sample with 70 percent fish meat selected as the best formulae. For determination of quality changes at -18ºC, 2 variable level of BHA antioxidant (0.01 and 0.02 percent) with a blank sample (without antioxidant) were prepared. Results showed that total count of bacteria reduced and reached to 0 after 60 days while TVN and peroxide factors increased in each sample during storage time. So both peroxide and TVN tests could used for determination of storage time.
Volume 7, Issue 4 (12-2018)
Abstract
The use of environmentally friendly methods is one of the new approaches in combating pathogens in aquaculture systems. The purpose of this research was the possibility evaluation of indirect use of Ag-NPs-coated porous ceramic in water filtration of culture system of shrimp post-larvae to control Vibrio harveyi. In this study, Ag-NPs-coated filters were characterized by various analytical techniques such as FTIR, XRD, ICP, and SEM. In this study, the antibacterial activity of Ag-NPs-coated on porous ceramic against mentioned bacteria via in vitro experiments Zone of inhibition test and Test tub test were determined. Then porous ceramic filter media used for water treatment. Therefore, the performance of the Ag-NPs-coated on porous ceramics in removing pathogenic bacteria was studied in two phases: In the first phase, V. harveyi was inoculated to the water and efficacy of filters of inhibition of bacteria was evaluated via total count of bacteria in the test water; in the second phase, the performance of the Ag-NPs-coated on porous ceramic was tested in the presence of shrimp larvae and efficacy of filters in inhibition of bacteria was evaluated via total count of bacteria, mortality rate, clinical signs, and also hepatopancreas and muscle culture. Based on the results, the highest zone of inhibition obtained in presence of Ag-NPs-coated porous ceramic modified by an aminosilane coupling agent, 3-Amino-Propyl-Triethoxysilane (APTES; the samples were immersed in the silver colloidal solution for 24h). The results of the flow test showed the highest bacteria removal efficiency from water with complete removal of the targeted pathogen. In the second phase, the results indicated a significant difference in decreasing of water bacteria, shrimp mortality and disease symptoms in treatment containing silver compounds compare to controls. According to results, Ag-NPs-coated porous ceramic have a high bacteria removal efficiency for the disinfection of water of culture system of shrimp to control Vibrio harveyi.
Omid Azizian Shermeh, Moharam Valizadeh, Jafar Valizadeh, Mozhgan Taherizadeh, Maryam Beigomi,
Volume 8, Issue 1 (4-2017)
Abstract
Microorganisms and plants have high potential for reducing the metal (biosynthesis of nanoparticles) through their metabolic pathways. Apart from the environmental benefits of biosynthesis of nanoparticles, there is the opportunity for production of nanomaterial with new properties in this method. In this study, the fruit aqueous extract of Capparis spinosa L. was used for synthesis of nanoparticles. To evaluate the reducing potential of plant, total phenolic content and antioxidant activities of both aqueous and ethanolic extracts were measured by DPPH and FRAP methods. The aqueous extract showed a lower antioxidant activity than the ethanolic extract; however, it had high potential to reduce the free radicals and metal ions. After preparing the extract, for phytosynthesis of silver nanoparticles, 2 ml of extract was added to 4 ml of 1 mM silver nitrate. The extract was used as a reducing and stabilizing agents of the nanoparticles. The effect of determining parameters for optimizing synthesis of nanoparticles such as: pH of reaction, the amount of extract, concentration of metal ion and time of reaction were evaluated using Ultraviolent-Visible (UV-Vis) spectroscopy and Transmission Electron Microscopy (TEM) .The spectrum of Surface Plasmon Resonance (SPR) of silver nanoparticles showed the maximum absorbance at 415 nm. Fourier Transform Infrared (FT-IR) spectroscopy was used to identify the possible functional groups involved in the synthesis of silver nanoparticles. The Results showed that the nanoparticles were spherical shape and the size of them were about 8-12 nm.
