Showing 25 results for Akhavan
Volume 3, Issue 1 (11-2012)
Abstract
Probiotics are live microbial feed supplements, which beneficially affect the host by improving its intestinal microbial balance[8].Recently, researches have shown that lactic Acid Bacteria(LAB), especially Bacillus (because of having endospore) remain stable at cooking temperature and retain their probiotic benefits in baked goods [3]. The purposeof this study,was using of Bacillus coagolans, as a resistant probiotic,for enrichment of bread. First, these probiotic bacteria were determined by the tests of salt tolerance, heat resistance, bile tolerance, tolerance of acid and pepcin, resistance of antibiotics, and preventing the growth of pathogenic starins[18].Then a certain number cells of BC were entered in bread dough,before& after baking the number of live bacteria were calculated by colony count in 1g of dough and bread. The number of BC decreased from 108 to 106 units per gram, after baking. Also,the amount of starch decreasd and changed into simple sugers. The pH was estimated about 4.5-5 and TTA (Total Titritable Acidity) was between 6-8. Finally, the enrichment of bread was evaluated by experts and its quality and taste were compared with a control sample. The Results showed this bacterium survives in baked bread and makes good chemical changes on it.
Volume 8, Issue 1 (10-2008)
Abstract
Abstract
In the present work, investigation on flow boiling heat transfer of R-134a inside a horizontal tube and also the tubes with coiled wire inserts has been done experimentally. The experimental setup which was used in this investigation was a well instrumented vapor compression refrigeration system. This set-up consists a test evaporator which all the experiments were carried out on it. Refrigerant which flows inside the tube of test evaporator is electrically heated by the coils around it. The evaporator tube is a copper tube with 7.5 mm internal diameter. The range of some operating parameters are: refrigerant mass velocities 54-136 kg/m2s, vapor qualities 0.2-1.0 and heat fluxes 2-6 kW/m2. The empirical data were collected for plain tube and tubes with seven different coiled wire inserts (different coil pitches and different wire diameters). The results show that the insertion of a helically coiled wire inside the evaporator tube increases the heat transfer coefficient by as much as 83% above the plain tube values on a nominal area basis. An empirical correlation was developed to predict the heat transfer coefficient during flow boiling of R-134a inside horizontal coiled wire inserted tubes.
Volume 9, Issue 2 (Spring 2018)
Abstract
Aims: Today, crude oil is one of the main sources of energy. The combustion of sulfur-containing compounds in fossil fuels leads to the production of sulfur oxides that has adverse effects to human health and the environment. At the moment, the current method for removal of sulfur is Hydrodesulfurization. The aim of this study was to investigate the effect of magnetic nanoparticles and modified carbon nanotubes as nano-adsorbent on improving the biodesulfurization activity of microorganisms (Rhodococcus erythropolis IGTS8).
Materials and Methods: In the current experimental study, the nanoparticles were synthesized by chemical co-precipitation and the carbon nanotubes were initially carboxylated. Multi-layer carbon nanotubes were mixed with 95% sulfuric acid and 52% nitric acid (volume ratio 1:3) and, then, modified by polyethylene glycol. In order to characterize nanoparticles and carbon nanotubes, scanning transmission electron microscopy (STEM), X-ray diffraction, magnetic surveys, analysis of arch Raman, and fourier-transform infrared spectroscopy (FTIR) were conducted.
Findings: The size of nanoparticles was estimated to be 7-8nm and modified carbon nanotubes showed the highest solubility as well as stability in deionized water for two weeks. The growth of microorganisms in the presence of magnetic nanoparticles and carbon nanotubes compared to their absence increased by 40% and 8%, respectively. Moreover the desulfurization activity of microorganisms in the presence of magnetic nanoparticles and carbon nanotubes showed a significant increase compared to their absence.
Conclusion: Nanoparticles with adsorption of sulfur compounds increase their availability for microorganisms.
Volume 11, Issue 2 (Spring 2020)
Abstract
The combustion of fossil fuels containing sulfur results in the release of sulfur dioxide into the atmosphere and environmental pollution. Hence, the researchers focused on the biological desulfurization method. Dibenzothiophene is used as the model molecule to study the ability of the desulfurization of microorganisms. The most suitable sources of carbon, nitrogen and sulfur concentration optimized by response surface method to obtain the highest cell growth and biological desulfurization activity. The performance of iron nanoparticles on the growth and biodesulfurization activity of thermophilic bacterium Bacillus thermoamylovorans strain EAMYO was investigated. Characterization of starch-modified iron nanoparticles was performed by TEM, SEM. The images of TEM and SEM of starch / Iron nanoparticles showed that the Fe3O4 and Fe0 nanoparticles were 20 and 30 nm, respectively. The investigating the growth of microorganism in the presence of iron nanoparticles showed that these nanoparticles not only did not have a toxic effect on microorganism growth, but also increased the growth of microorganism in 96 h (OD 660 = 1.864, 1.896 respectively in the presence of nanoparticles Fe0 and Fe3O4), while the highest rate of growth in the absence of nanoparticles in 96 h (OD660 = 1.51). Also, the activity of desulfurization in the presence of starch/Fe0 nanoparticles and starch/Fe3O4 / starch increased by 26.52% and 10.75%, respectively, compared to the cells without the coating of iron nanoparticles.
Volume 11, Issue 3 (9-2011)
Abstract
In this paper, free vibration analysis of moderately thick smart FG rectangular plate is presented on the basis of Mindlin plate theory. This structure is composed of a host FG plate and two bonded piezoelectric layers. The plate has two opposite edges simply supported (i.e., Levy-type rectangular plates). The closed circuit piezoelectric layers can be used as an actuator. According to a power-law distribution of the volume fraction of the constituents, material properties vary continuously through the thickness of host plate. Using Hamilton's principle and Maxwell electrostatic equation, six complex coupled equations are introduced. These equations are exactly solved introducing the new potential and auxiliary functions as well as using separation of variables method. The accuracy of the frequencies is verified by the available literature and the finite element method. The present exact solution can accurately predict not only the out of plane, but also the in-plane modes of FG plate. Finally, the effects of various parameters such as boundary conditions, gradient index and thickness of piezoelectric layers on the natural frequency are investigated.
Volume 12, Issue 1 (12-2020)
Abstract
Biosurfactants are produced by microorganisms. Surfactin is one of the main lipopeptide biosurfactants produced by different species of Bacillus subtilis. This study aims to analyze the effect of starch-coated Fe0and Fe3+nanoparticles on the biosurfactant production of Bacillus subtilis. Out of 70 soil samples, 20 Bacillus were isolated and genome sequenced by biochemical methods and 16S rRNA gene. Quantitative and qualitative screening methods were used to isolate and detect biosurfactant production. For the aim of this study, 61 and 63 (Bacillus subtilis subsp. Inaquosorum) were selected. Then, hemolytic activity, surfactant production and reduction of surface tension in Minimal Salt Medium containing Fe0 and Fe3+ nanoparticles were examined after 48h, 72h and 96h of culture. The binding of the nanoparticles to the surfactant was confirmed by SEM. Strain 61 was the best bacterium and Fe3+ was the best nanoparticle and it was cultured. The results were compared with the results of non-nanoparticle bioreactor. Surfactin from strain 61 culture in the Fe3+ nanoparticle bioreactor after 72 hours of growth showed higher production than the same strain culture after 72 hours without Fe3+, if continuing the research, this strain can be commercialized in the future.
Volume 12, Issue 49 (10-2015)
Abstract
In present study, dried pomegranate peel of three dominant Iranian varieties was extracted by soxhlet extraction (SE) method via four solvents. In this study Five anthocyanins were identified and quantified in the extracts by high performance liquid chromatography (HPLC) coupled with ultraviolet-visible (UV-Vis) spectrometric detector at wavelength of 517 nm according to their retention times and external standard method. According to the results extraction yield of Poost Siyahe Shirine Ardestan (PSSA) variety is more than other two varieties and extraction yield of ethanolic extracts is more than other solvents in p≤0.05. HPLC analysis was indicated pomegranate peel include of more mono glucoside anthocyanins than di glucoside anthocyanins also the most of anthocyanins particularly mono glucoside anthocyanins were detected in ethanolic extract obtained from dried peel of PSSA variety.
Volume 13, Issue 2 (Issue 2 (Tome 61)- 2009)
Abstract
This research was designed to identify the critical success factors of business process reengineering in an Iranian defense industries case study based on multivariate data analysis. Through developing a business process reengineering model and implementing it on the case study, the business processes were be managed and then its success was be analyzed, by a questionnaire. This analysis initially, represents the success of applied changes, and then follows the critical success factors of process reengineering in three main factors.
Subsequently, by multiple regression tool, the business process reengineering success as dependent variable was estimated by the above three factors. The results, showed goodness and validity of the regression model. Accordingly, belief to change, change of infrastructures, participation of people in changing programs and decreasing of the resistance against the changes are the critical success factors of business process reengineering in the respective organization.
Volume 16, Issue 13 (Conference Special Issue 2017)
Abstract
Volume 16, Issue 13 (Conference Special Issue 2017)
Abstract
Volume 16, Issue 86 (4-2019)
Abstract
The aim of this study was to investigate the effect of Aloe vera gel (50 and 100% w / w), salicylic acid (0 and 2 mM) and thyme extract (0, 0.1 and 0.5% v / v) on shelf life of fresh pistachios. Disk diffusion test was done in a completely randomized design and the percentage of Aspergillus development, microbial count, sensory evaluation and color tests were assessed in a factorial based on a completely randomized design. The results showed that the mold growth development (in disk diffusion test) and total counts of mold, yeast and aerobic mesophilic bacteria were lower in the samples containing Aloe vera gel, salicylic acid and thyme extract. Also, the highest score and color parameters in color and sensory evaluation tests were found for the samples with above mentioned coating, which had a significant difference with the control (P <0.05). Control and treatment with Aloe vera gel of 50% concentration (a) were identified as the worst coatings, and Aloe vera gel coating containing thyme extract and salicylic acid at high concentrations (AST) were found to be the best treatment with the ability to improve the shelf life of fresh pistachios.
Volume 16, Issue 87 (5-2019)
Abstract
Date fruit (Phoenix dactylifera L.) is a rich source of sugar, fiber, some vitamins, minerals and antioxidant phenolic compounds. The physico-chemical, biochemical and microbial changes occurring in this fruit reduce its quality properties during storage time. In the present study, the effects of polyethylene film containing 1 and 2% zinc oxide nanoparticles as nanocomposite packaging and film without nanoparticles as a control were evaluated in order to maintain some quality characteristics of Mazafati date fruit in two storage temperatures of 4 and 25 °C for 120 days. The results of analysis of variance showed that the effects of nanocomposite film, temperature and storage time on the studied parameters of Mazafati date were significant (p <0.05). The least changes in quality parameters of weight loss, pH, titratable acidity, total soluble solids, total phenolic content and total and reducing sugar contents were observed in date samples packed in 2% nanocomposite film stored at 4 °C. The change in control sample stored at 25 °C was significantly higher than other samples. In addition, the use of nanocomposite packaging reduced the microbial growth rate (total aerobic mesophilic bacteria, and mold and yeast) compared to the control sample. With increasing storage temperature from 4 to 25 °C, an increasing trend was observed in microbial growth and changes in the quality parameters of all samples, which indicated a decrease in the quality characteristics of the date fruit. Considering the studied parameters, nanocomposite packaging containing 2% zinc oxide had better performance than nanocomposite packaging containing 1% zinc oxide. In general, the use of nanocomposite film containing 2% zinc oxide nanoparticles is suggested to maintain the quality characteristics of Mazatifi dates at a temperature of 4 °C.
Volume 16, Issue 88 (6-2019)
Abstract
The Mazafati date is one of the most important export products of Kerman province, which their quality characteristics may change during storage. The use of edible coatings is a new technique for increasing the shelf life of various agricultural products. The aim of this study was to investigate the effect of Aloe vera containing salicylic acid (2 mM) and green tea extract (0.5%) on physicochemical, microbial and sensory properties of stored dates at 4 and 25 °C for 150 days. The results of analysis of variance showed that the coating, temperature and time of storage had significant effects on the evaluated parameters (p <0.05). According to the results, the lowest weight loss was observed in samples coated with Aloe vera containing green tea extract and salicylic acid. This type of coating prevented significant changes in pH, acidity, total soluble solids (°brix), total and reducing sugar contents of date samples compared to the control during the storage period. During the storage period, the pH and total sugar content decreased, and acidity, total soluble solids and reducing sugar content increased. Total phenolic content did not have a clear trend during the storage period and its amount in the coated samples was significantly higher than the control. Aloe vera containing green tea extract and salicylic acid also effectively prevented microbial growth. In addition, panelists gave higher scores to dates coated with Aloe vera containing green tea extract and salicylic acid. The changes in physicochemical, microbial and sensory parameters in the stored dates at 25 °C were significantly higher than that stored at the temperature of 4 °C. In general, the use of Aloe vera containing green tea extract and salicylic acid, and storage at 4 °C is recommended due to the reduction of microbial growth and maintaining the quality characteristics of Mazafati date.
Volume 16, Issue 92 (october 2019)
Abstract
In this study, the effect of the inlet air temperature and milk flow rate on the physical properties of the milk powder obtained from the spouted bed dryer was investigated. Milk samples were dried at three levels of inlet air temperature (80, 100 and 120 ○C) and three levels of milk flow rate (1.333, 2.500, 3.556 ml/min). The effect of these factors on the physical properties (bulk density, tapped density, flowability, color, and moisture content) of the powders was evaluated. The effects of the mentioned factors on the physical properties of milk powder were determined and modeled using response surface methodology. The optimum inlet air temperature and the milk flow rate was obtained 93.82 ○C and 1.333 ml/min, respectively. Under these conditions, the desired values for each physical parameter were predicted and compared with the experimental data.
Volume 16, Issue 97 (March 2020)
Abstract
Wheat bran as a by-product of milling contain various compounds such as pentosans which have health promoting effects and functinal properties in industrial applications. In this study the extraction yield of pentosans by hot water 80oC, 0.01 mM sodium hydroxide and 2% alkaline hydrogen peroxide solutions as the conventional methods for pentosan extraction was evaluated. Then, the effects of pretreatments such as cellulase, ultrasound, autoclave and microwave in the presence of sodium hydroxide and water to increase the pentosan extraction yield were studied. Finally, in order to increase the extraction yield of the pentosans, pretreatments with the highest extraction yield (sonication, cellulase enzyme, hot water, sodium hydroxide, hydrogen peroxide) were evaluated as combined treatments. The results showed that the purity of pentosans extracted with sodium hydroxide was significantly higher than the hot water and hydrogen peroxide solution (p<0.05). Also, among the pretreatments of cellulase enzyme, ultrasound, autoclave and microwave in presence of water or sodium hydroxide, the combination of cellulase-sodium hydroxide and ultrasound-sodium hydroxide treatments resulted in the higher yields. The combined treatment of hot water (80oC)+cellulase enzyme+(0.1%)+ultrasound power (560 w, 2 minutes) and the combined treatment of hot water (80oC)+hydrogen peroxide (4%, pH=11.5) were identified respectively as the best combination factors to maximize extraction yield and pentosans purity from wheat bran.
Volume 17, Issue 66 (8-2024)
Abstract
Most Iranian paintings in the Islamic period were used to illustrate manuscripts, and most of the illustrated manuscripts are literary books. Poetry and literature have been in the history of Iranian thought as a system of knowledge and epistemology. Therefore, the issue that is raised is that in Iran, what was the relationship between the history of painting and the history of literature and what effect did the change of literary discourses have on the history of painting? To clarify aspects of this issue, in this article, a section of a period has been discussed in which the literary discourse has changed in the history of literature. In this regard, the illustrations of Jami's Haft Awrang, illustrated in the court of Sultan Ibrahim Mirza, have been analyzed. In this research, Tartu-Moscow School of Cultural Semiotics and concepts of Inter-Semiotic Translation have been used. The results of this article showed that with the change of literary discourse, from the time of Jami to Ibrahim Mirza, Iranian painting has changed in terms of form and content. Haft Awrang, unlike Jami, is not a tool for conveying the concepts of Sufism for Sultan Ibrahim Mirza, but rather a literary and artistic text, and the literary and aesthetic aspects of the work were his priority. These literary and aesthetic aspects are also formed based on the attitudes and concepts of the Voqu School.
1. Introduction
Iranian painting has had a strong relationship with Persian literature due to its use in book illustration. The relationship between Iranian painting and Persian literature is important from two aspects: First, Iranian painting has a direct relationship with literary texts and has tried to translate literature into visual language. Secondly, due to the high costs and the presence of a large number of artists in the preparation of exquisitely illustrated manuscripts, only the court and the centers of power could carry out these projects. Based on this, painters, like poets and writers, were in the service of the royal court and libraries, and this closeness between artists and poets has led to a close relationship between painting and literature. So far, the relationship between Iranian painting and Persian literature has been investigated mostly at the text level. The case studies that have been done on an illustrated version have investigated the relationship between the literary text and the images added to that specific version. The subject of this article is reading the history of Iranian painting about the history of literature, and perhaps in this new perspective, we can search for new horizons in the history of Iranian painting and answer unknown questions. A comprehensive and accurate understanding of the relationship between the history of painting and the history of literature requires a diachronic and comparative study of the equivalence of the history of literature and the history of painting, which is not possible in the form of an article. In this article, to clarify aspects of the claim raised, in a synchronic study, the illustrated manuscript of Jami's Haft Awrang, which was prepared in the court of Sultan Ibrahim Mirza during the Safavid era, will be discussed. In this article, the images of this manuscript have been selected as a case study and analyzed to show the relationship between the history of Iranian painting and the history of Persian literature based on literary developments. Also, the influence of literary discourses on the form and content of Iranian painting has been studied.
2. Data and Method
In this article, to formulate the relationship between Persian literature and Iranian painting, literature as a discourse is considered. Discourse is defined here according to the theory of Michel Foucault, who introduced this concept about the concept of "power/knowledge". Iranian painting is also defined in this article based on the concept of "Inter-Semiotic Translation". Since Inter-Semiotic Translation refers to the translation from one Sign System to another, such as the translation from written signs to images, Iranian painting in the field of text illustration can be studied in the field of Inter-Semiotic Translation. In this article, the selected images are studied based on their relationship with the written text and their translation from the written sign system to the image.
To formulate and explain the relationship and difference between the two discourse spaces or the sign spaces in which the written text and the visual text are created, the theory of "Semiosphere" proposed in the cultural semiotics of the Tartu School has been used. According to this pattern, the discourse space in which the written text of Haft Awrang was produced represents a Semiosphere, and the discourse space in which the pictures are added represents another semiosphere. Jami's text has crossed the border between these two Semiospheres and based on the mechanisms of translation, it has been translated and internalized into the sign system of the new space (the discursive space that governs Ibrahim Mirza's library). With this theoretical approach, painting is not only an objective translation of the written text, but several factors are involved in this translation mechanism, which will lead to the formation of new layers of meaning in the text.
3. Results and Discussion
Abd-Al Rahman Jami, the author of the Haft Awrang Masnavi, had a Sufi attitude, so the poetic form and the narrations he narrated in his work all arose from his beliefs and the origin of Sufism. But Sultan Ibrahim Mirza and the artists of his library had a different attitude towards Jami poems. By adding illustrations to this manuscript, they have expressed their different approach to converting the written sign system of the Jami text into a visual sign system and have used mechanisms in this translation. For Sultan Ibrahim Mirza, Haft Awrang was not a tool to convey the concepts of Sufism, but a literary and artistic text, and the literary and aesthetic aspects of the work were his priority. The reason for this difference in attitude can be seen in the change of literary discourse at the beginning of the Safavid period.
In the first quarter of the 10th century of the Hijri (16th century CE), a new school of Persian poetry emerged, which took the lyric poem out of the dry and soulless format of the previous century. This new school was called "Voqu" and its purpose was to express love situations from reality and what happens between the lover and the beloved. Sultan Ibrahim Mirza was a poet and most of his poems are dedicated to expressing real situations and relationships between lovers. The editors of Ibrahim Mirza's poems in the introduction of the book of his poems that they have published have pointed out his tendency towards the school of Voqu, especially in his lyric poetry. Jami's period was the era of dominance of "imitative discourse" in poetry. However, in the case of Ibrahim Mirza, the literary discourse underwent a transformation and the "Voqu School" became the dominant literary discourse. Therefore, in the new conditions, the attitude of the elite towards literature and attention to the previous poets has also changed.
"Angels Bring Light to Saadi" is one of the paintings in this manuscript that specifically refers to a poet and is the first painting from the Masnavi of Sobha al-Abrar of Haft Awrang. In this story, a "Sufi" has a negative attitude towards a "poet" and it becomes clear to him that a verse from Saadi's poem has brought him a high position that a Sufi may not achieve this position. The same issue shows that literature is higher than Sufism and the position of poets is higher than Sufi. Understanding why, among a text with these characteristics, Ibrahim Mirza and his court artists chose the story related to Saadi for illustration as the first image of this part and translated it into a visual text with the mentioned mechanisms, only through establishing the relationship between the history of Persian literature and the history of Iranian painting is possible.
In another picture, which is about the story of Lily and Majnoon, the place of the text and the margin have been changed, and marginal elements have come to the center, and Majnoon has been marginalized as the main focus of this narrative. The use of this mechanism has led to the creation of the meaning that the whole narrative of Majnoon is represented in the painting as a literary narrative. So, the specific narrative of Jami, in which the Sufi purposes have priority, is marginalized as a macro-narrative. Beloved in Persian Sufi poetry is an expression of the perfect human being or absolute truth. She is a holy goddess and her will is above the lover's will. Such a lover was the high point of the lyrical imaginations of mystics from the Sana'i period to the Jami era for about four centuries. This complete and absolute goddess disappeared from Shah Ismail in the Safavid era. The most common type of Persian poetry during the formation of the Safavid state was the simple romantic lyric. Lyric poems mainly have no theme other than love that is virtual love or real love of the poet for his fellow man.
As another example, "Salaman and Absal" in Haft Awrang narrates a romantic story that contains mystical and moral references along with anecdotes and parables. If Sultan Ibrahim Mirza had an attitude similar to Jami's towards this narrative, he could have chosen characters or scenes for illustration that have mystical connotations. But all these elements have been removed and only the scene of two lovers connecting in a heavenly land is depicted, far from any signs that have a mystical meaning. Therefore, in this painting, by removing mystical symbols, the possibility of understanding the meaning of Jami has been distorted. With this mechanism, based on the concept of "love" which is derived from Voqu School, the story of Salaman and Absal has been translated into a Semiosphere of the Safavid period.
4. Conclusion
The results of this article show that with the change of literary discourse in the Safavid period, painting also changed in terms of form and content. Since Ibrahim Mirza and his court poets were inclined towards the Voqu School, the characteristics and principles of this literary movement have influenced the way of illustrating Haft Awrang. Although Jami had a completely Sufi attitude in Haft Awrang, based on the literary discourse of the 9th century Hijri, the poetic form and the narratives he narrated in his works were tools for expressing his ideas. But Sultan Ibrahim Mirza and his artists had a different attitude from Jami and by adding pictures to this manuscript, they expressed their different approach in transforming the written sign system of Jami text into a visual sign system. For Sultan Ibrahim Mirza, Haft Awrang was not a tool for conveying Sufi concepts, but a literary and artistic text, and the literary and aesthetic aspects of the work were his priority. These literary and aesthetic aspects are also formed based on the attitudes and concepts of the Voqu School, the most important of which is the concept of love. This difference in the attitude towards the concept of love in the era of Jami and Sultan Ibrahim Mirza can be seen in the difference in the representation of love in Haft Awrang text and illustrated manuscript. As a result of paying attention to the real world in the literary discourse, Ibrahim Mirza established similarities between his life and the narrative inside the paintings and used Haft Awrang as a medium to reflect his personal life. By analyzing based on the Semiosphere pattern, it can be concluded that during the time of Sultan Ibrahim Mirza, Haft Awrang was translated into a visual sign system based on the literary discourse of the Voqu School using different mechanisms. The change in literary discourse and its effect on the illustration of manuscripts show that Persian literature had a discourse role in Iranian painting. For a precise understanding of Iranian painting, the history of Iranian painting can be considered a function of the history of Persian literature and studied about the history of literature.
Volume 17, Issue 98 (April 2020)
Abstract
There are different ways to reduce the risk of spoilage and increase the shelf life of agricultural products, one of which is ultraviolet radiation. The UV irradiation system has seven UV-C lamps, that for microbial deactivation, the effects of lamps number (3, 5 and 7), the distance of lamps from pistachio kernels (10, 20 and 30 cm), and the UV-C radiation time (15, 20 and 30 minutes) were evaluated. Based on Aspergillus flavus inactivation, the application of 3 lamps, the distance of 10 cm, and the irradiation time of 30 minutes were selected as the best treatment for irradiation of dry pistachio kernels. The results indicated that UV-C irradiation had no significant effect on peroxide and acidity values (p <0.05), but UV-C irradiation caused a significant (p<0.05) increases of the total phenolic content in pistachio kernels. According to the panelists scores, the texture of irradiated sample obtained a higher score than the control sample. However, no significant difference was observed in terms of other sensory characteristics (appearance, aroma, and taste) between the irradiated and control samples.
Volume 18, Issue 2 (4-2018)
Abstract
In this study, the performance of direct absorption solar collector is experimentally investigated using Fe3O4/Silica hybrid nanofluid based on deionized water. First, stability of prepared nanofluids is considered using spectral absorbency method. Then, spectrophotometry method is used for measuring optical properties of nanofluids. A prototype of this new type of collector was built with applicability for solar water heating systems. The procedure of EN 12975-2 standard was used for testing the thermal performance of the collector. Results show that collector efficiency is enhanced by nanofluid concentration, so that collector maximum efficiency is 73.9%, 79.8% and 83.7%using nanofluid with concentration of 500 ppm, 1000 ppm and 2000 ppm, respec/tively. This vaule is 63% using the base fluid as working fluid. Regarding very low volume fractions of nanofluids used in direct absorption solar collectors, the viscosity of the base fluid experience insignificant increase, therefore, pumping power will not increase significsantly. Such increase in efficiency show that direct absorption solar collector performance using hybrid nanofluid is much better than that of using the water at the same operating conditions. Application of stable hybrid nanofluid results in higher conversion efficiency of solar energy to useful energy.
Volume 18, Issue 117 (November 2021)
Abstract
Ultraviolet radiation was used in the present study to process lemon juice. The designed UV system had five UV-C lamps and irradiation was performed based on the distance of the lamps (10, 20, and 30 cm) from the fluid layer and the circulation time (10, 20, and 30 minutes) of lemon juice in the system. Non-irradiated sample was also considered as a control treatment. The control and irradiated samples were filled in dark polyethylene bottles and stored at ambient temperature for 90 days. Immediately after irradiation and during the storage period, parameters such as pH, titratable acidity, total soluble solids, ascorbic acid content, color indices (L*, a*, and b*), browning index, as well as sensory attributes were evaluated. The pH, acidity, and total soluble solids did not show a definite trend. The results showed that among the color indices, L* decreased significantly, but a* and b* increased significantly during the storage period. The rate of color changes in irradiated samples from a distance of 10 cm was higher than other treatments. Irradiation also significantly reduced the ascorbic acid content of irradiated samples from a distance of 10 cm compared to other samples and control. However, the browning of irradiated samples from 10 cm distance was significantly less than that of irradiated samples from 20 and 30 cm distance. The score of the panelists indicated that irradiation and storage time altered the quality characteristics of lemon juice. The panelistschr('39') scores showed more acceptance of irradiated samples from 20 and 30 cm distance compared to irradiated samples from 10 cm distance. In general, the designed system in this study is not recommended for lemon juice processing due to the destructive effect of UV-C radiation on the content of ascorbic acid.
Volume 19, Issue 2 (9-2016)
Abstract
Introduction: Squamous cell carcinoma comprises approximately 94% of all oral cavities. One reasons for this cancer is Human Papilloma Virus (HPV) with different genotypes .Finding the most common genotypes will be helpful to control and prevent of spreading this cancer.
Materials and Method: 70 Paraffinated blocks were collected from cancer department of Imam Khomeini hospital in Tehran. All of these samples included histopathological report of dysplastic lesions .They weredeparaffinated.4 primers were designed for PCR .Then they were transferred to electrophoresis tank. Positive samples were sequenced by Mega 5.
Results: 8 HPV+ samples include of 3 HPV+6 and HPV+16 were found . HPV6 is the cause of genital warts that can spread by skin contact or oral- sexual behavior. 3 positive samples were found in women and the others were in men. (2% more in men) . People between 30 to45 are more sensitive for HPV than the other group. People up to 60 years old are sensitive too. All the samples were collected from different cities of Iran but most of the positive samples were found in Tehran and Islam Shahr.
Conclusion: These data confirm that HPV infection with high risk types (6, 16) could be one of the risk factors for oral cancer and it can spread by genital warts.