Showing 55 results for Medium
Volume 0, Issue 0 (2-2024)
Abstract
The practice of English as a medium for learning academic subjects in academic settings is becoming more popular all over the world. However, its application in music in countries where English is not the first language is controversial. Indeed, English Medium Instruction (EMI) is growing promptly in various territories such as the Middle East and North Africa as a part of internationalization. The application of EMI plays a crucial role in improving learners’ English skills and subject matter which can also affect learners’ achievement. The most important predictor of learners’ performance and success is self-efficacy which is also a relevant concept in the area of music performance. Although self-efficacy is significant, its contribution to music learning and academic accomplishment in EMI courses seems critical. Indeed, it should be taken into consideration as it is in direct relation to learners’ academic achievement. As a result, the main objective of this review is to inspect the contribution of self-efficacy to music students’ academic achievement in a context where English is used as the medium of instruction. In a nutshell, the current paper ends up with some suggestions and recommendations to be used by teaching participants in scholastic situations.
Volume 1, Issue 1 (3-2013)
Abstract
In order to determine effects of chicken and cattle manures in culture of Chlorococcum, an experiment was designed in six treatments including; 0.1, 0.4, 0.8 g/l of chicken manure and 0.1, 0.4, 0.8 g/l of cattle manure as completely randomize design with three replicates for 28 days. Results showed that the mean maximum density (87.1 × 105 cell/ml), specific growth rate (0.054 day-1), algal dry biomass (0.644 g/l), and chlorophyll a (9.42 mg/l) were obtained with 0.8 mg/l chicken manure. In order to compare performance of these manures with other culture media, second experiment with five treatments including; BBM (control) (Bold’s Basal Medium), BBM + soil extract, 0.8 g/l chicken manure, 0.8 g/l cattle manure and mixture of all treatment (BBM, BBM + soil extract, chicken manure and cattle manure) was designed as completely randomize design with three replicates for 15 days. Comparative results showed that BBM + soil extract had highest algal density (11.6 x 106 cells/ml), highest algal dry biomass (0.81 mg/ml), maximum SGR (0.13 /day), highest chlorophyll a (10.15 mg/l) and minimum doubling time (4.97 days). In conclusion, performance of BBM + soil extract was better in terms of biomass and growth parameters of Chlorococcum.
Volume 3, Issue 2 (9-2019)
Abstract
The use of genetic engineering tools to produce industrial strains, especially from non-model microorganisms such as cyanobacteria, is always subject to limitations. In this research, a system-oriented method was used to design a culture medium instead of strain designing and its ability to increase ethanol production by Synechocystis sp. PCC 6803 was experimentally evaluated. In this method, compounds are added to the medium to regulate the activity of target enzymes not for the purpose of being consumed by the cells, and thus, the designed culture medium eliminates the intracellular constraints on the production. A metabolic model was used to determine the minimum level of ethanol production and to identify genes that increase or decrease of their expression increase this minimum level. Then, regulators of the enzyme expressed by the target genes were extracted from the Brenda database and their effect on the production was evaluated experimentally and design of experiment was performed to optimize the concentration of the selected compounds. Among the compounds identified, two inhibitors (salicylic acid and mercuric chloride) and one activator (pyruvate) were selected to be added to the medium and their concentration was optimized using the central composite design method. The proposed regulatory medium increased the production of ethanol from 352 to 1116 mg/l, indicating the effectiveness of the added regulatory compounds on the cyanobacteria metabolism. The proposed system-oriented method can be used to design medium culture for other important bio-products such as recombinant proteins.
Volume 3, Issue 3 (12-2013)
Abstract
Developments, changes and increased competition in the field of industry in recent years, has forced organizations to focus on gaining competitive advantage. In general, many experts believe that organizational performance improvement will increase profitability, and therefore the organization's competitive position relative to other competitors will be dramatically enhanced. It can be accomplished through environmental conditions, resources and practices required. As results, organization can enhance its ability to value creation and achieve profitability. In this study, regarding to resources in achieving high level performance, the key sources of influence on organization performance is derived by reviewing the results of previous researches and according to experts’ points of view. Using the experimental design method, appropriate framework of factors presented. The results show that contribution percentage of following factors: total number of employees, inventory levels, the value of capital assets, the ratio of manufacturing employment to total employment and the cost of advertising on firm performance.
Volume 4, Issue 3 (9-2015)
Abstract
Effects of three nutritional levels of beet root molasses, cheese permeate, wheat bran extract, rice bran extract and Sabouraud,s Dextrose Broth (SDB) were evaluated for blastospore production by two isolates of Beauveria bassiana sensu lato. at an interval of 24 h for seven days. Depending on the isolate, maximum blastospore production was obtained in 12% rice bran extract and 20% cheese permeates on the 7th day. Both isolates produced the fewest blastospores in 4% cheese permeate. Virulence of blastospores, produced in liquid media containing beet root molasses, permeate, wheat bran extract and SDB (as control), on third instar larvae of brown tail moth Euproctis chrysorrhoea indicated that there were no significant differences among these nutritional media for either one of the isolates. Considering blastospore quantity and quality in terms of virulence and local accessibility, cheese permeate was found to be the best medium for mass production of B. bassiana blastospores.
Volume 6, Issue 1 (4-2014)
Abstract
Abstract
This article that has studied the causes of the formation of Motalefeh before the Islamic revolution of Iran was codified on the basis of placing Motalefeh in the model of categorical base of its members, namely "stratum of urban traditional medium". Thus, at first, the characteristics of the aforesaid stratum were regarded. Then by separation of the traits of this stratum, namely traditionalism and severe tendency to religion, sensitivity in sexual issues and household affairs, opposition with luxury-oriented ness, pessimism to alien symbols, negative attitude toward modern financial Institutions, threat of economic position, decadence of social situation and finally, close relation with shia clergy, these characteristics has been studied with regard to the Motalefeh in that time period. Thereby the causes establishing of this religious-political group has been analyzed.
Volume 6, Issue 1 (12-2006)
Abstract
In this paper the reflection coefficient of electromagnetic wave incidence on the walls of the buildings and obstacles that occurs in mobile communication path was modified by solving the Riccati nonlinear equations. For this purpose, the building walls are assumed inhomogeneous layers where their permittivity changes as function of the wall thickness. Using this reflection coefficient, a new propagation model based on urn and GID (uniform geometrical theory of diffraction and geometrical theory of diffraction) for multiple diffraction paths is proposed. Using this model, the diffraction loss as well as the path loss for a row of buildings with two in homogeneous faces is calculated and compared with measured data. Comparison of theoretical and measured results reveals that the modified reflection coefficient can adequately predict the reflective properties of the building walls. Moreover, results obtained with the proposed UID model are in good agreement with the measurement data. Therefore, the modified reflection coefficients well as the new UID model can be used for estimation of multipath signals strength, diffraction loss and also path delay in ray tracing algorithms used in mobile communication, radar and radio links.
Volume 7, Issue 3 (12-2017)
Abstract
one of the most important ways to realize the resistive economy is to support the small and medium industries and create a sustainable capacity in them to deal with the environmental changes and threats. In the management science, achieving such a goal is manifested in the concept of the organizational resilience. Therefore, the present study is aimed to identify and rank the most important affecting factors of the resilience of small and medium industries in order to provide practical solutions for managers and relevant authorities. For this purpose, 10 experts and managers of these industries have been interviewed and with the help of the theme technique, the affecting factors on resilience have been identified and Then 14 experts have ranked these factors by questionnaire method and using the analytic hierarchy technique. The results have shown that the intra-organizational factors have a greater effect on the resilience of the company than the extra-organizational factors. Among the intra-organizational factors, the management factor with the sub-criteria of attitude to change has the highest priority, Also, among the extra-organizational factors, the factor of organizations and trade associations with the sub-criteria of amendments, and the factor of governmental support with the sub-criteria of exemptions and tax rebates are respectively in the first and second ranks.
Volume 7, Issue 3 (11-2023)
Abstract
Research subject: Aspergillus niger stands as a versatile filamentous fungus renowned for its industrial significance in producing various organic acids, notably citric acid and oxalic acid. Low sugar concentration as substrate leads to the production of oxalic acid, therefore, this article delves into the intricate metabolic machinery orchestrating the synthesis of these acids within A. niger, shedding light on the pivotal role of culture media composition and metabolic activity.
Research approach: Through a comprehensive review of A. niger metabolism, this study elucidates the pathways involved in the biosynthesis of citric acid and oxalic acid, unraveling the intricate interplay of enzymatic cascades and regulatory mechanisms governing their production. Furthermore, it explores the impact of small molecules on metabolic flux through regulatory media, offering insights into strategies for controlling metabolic flux in order to eliminate oxalic acid production and amplify the citric acid production considering low sugar content of 30 g/l.
Main results: After careful review of previous researches, key reactions and genes was found and introduced for future researches in order to control the A. niger products. Examination of small molecule as a regulator in culture media not only elucidated the importance of culture media composition but also employing them helped us to redirect flux from oxalate toward citrate. NH4, Leucine, Cysteine, NaF, Glutathione, and Metformin were all found to be effective in the elimination of oxalic acid. In this regard, employing them leads to the production of 1868, 1530, 2093, 2250, 787, and 675 mg/L oxalic acid in comparison to the control culture media in which 5560 mg/L oxalic was produced. In addition, elimination of oxalic acid in some cases leads to the production of more acids like the culture containing NH4, Cysteine and Metformin.
Volume 8, Issue 1 (6-2018)
Abstract
Aims: From the beginning of the modernism, when architects began to use the aesthetic characteristics of steel and concrete structures in the building, new seismic configuration problems appeared; despite the existence of seismic codes, sometimes safety level in buildings is not achieved due to lack of attention in design and implementation. The aim of this study was to evaluate the role of architects in the seismic performance of conventional medium-rise buildings by using the experiences of past earthquakes.
Information and methods: In the present empirical study, regarding the broad view approach of the research, an experimental laboratory was used by observing damages of RC and steel structure buildings in past earthquakes. All the analytical data in 5 areas, including soil and site conditions, geometry and configuration of architectures, geometry and configuration of structures, architectural details, and structural details were adapted with the process of study, design, and implementation through logical argumentation method. Finally, all potential damages were set as a basic control matrix for use by architects.
Findings: According to the 5-part spectral model, unlike the initial impression that only the structural engineer is responsible for seismic resistant design of RC and steel structure buildings, and contrary to the view of some other researchers who consider that the role of architects is limited to the basic design of buildings form, architects play a decisive role on a wide range of factors affecting the seismic performance of buildings in the study, design, and implementation process.
Conclusion: Architects play a decisive role on a wide range of factors affecting the seismic performance of buildings in the study, design, and implementation process.
Volume 8, Issue 2 (10-2017)
Abstract
Background: wrongs in experiments and laboratories are inevitable particularly if used non-standard methods and tools. In routine disc diffusion test used optical method for pouring media in petri dishes that create non negligible errors in experiments. Goal of this research is design and produce a standard petri dish for this tests and eliminate the wrongs.
Methods: According CLSI standards about sensitivity tests medium standard thickness is 4 millimeters. According these data designed a standard petri dish that determined this standard thickness exactly.
Results: Results of this research showed existing Petri dishes produce wrong and different reports about non-growth haloes even for identical antibiotics that cause to antibiotic unfit administration significantly (P<0.05). In addition, medium waste rate was 33-50% for different petri dishes.
Conclusion: Designed standard petri dish standardized disc diffusion tests and other sensitivity tests and makes accuracy, non- growth haloes uniformity in identical tests, and antibiotics fit choose. Also decrease medium waste rate significantly.
A. A. Safari Sinegani, G. Emtiazi, S. Hajrasuliha,
Volume 9, Issue 1 (1-2007)
Abstract
Various basidiomycetes and deuteromycetes, grown in liquid and solid culture media, were compared for their laccase-producing ability and for the inducing effect of soil and agricultural residues on laccase production. Laccase activity in extracts of all solid media was higher than that of the liquid media. In liquid cultures, fungal laccase activity in ex-tracts of pea (Pisum sativum) straw-treated media compared with the other agricultural residue-treated media was significantly low. The laccase-producing ability of Polyporus sp. compared with the other fungi was significantly high whereas that of Trichoderma reesei was markedly low. Laccase activity of Phanerochaete chrysosporium under liquid conditions was strikingly low, however, under solid conditions it increased more than that of the other fungi. With the addition of soil to wheat and rice straw-treated solid media, fungal laccase activity increased significantly.
Volume 12, Issue 4 (1-2013)
Abstract
Science and technology can have a major role in growth and creating value added of communities. Research and development are important economic issue that cause technological changes and therefore have a significant role in development of technology and increasing production capacities. Although recently developing countries have realized the importance of R&D, their production units are unable to invest more in R&D section. It is also believed that in the early stages of development, the existing technological gap between these countries and technology leaders decrease the success possibility of R&D efforts and as a result, these communities don’t have reasonable technological basis for innovation. So in the early stages of development, in addition to R&D efforts, import of capital goods can also be effective in developing technology and increasing production capacities of developing countries. In this study, the effect of internal R&D capital stock and external capital stock on value added of the Iranian medium and large industries is investigated over the period of 1994-2007 by applying panel data approach. The results indicate that internal and external capital stock, human capital and internal R&D capital stock have a significant and positive effect on added value of the Iranian medium and large industries during the mentioned period. The research findings have also revealed that although the number of labor force has a positive impact on added value of these industries, it is not statistically significant.
Volume 13, Issue 2 (1-2023)
Abstract
Poly-γ-glutamic acid (γ-PGA) is a beneficial, biocompatible, and biodegradable biopolymer. These properties have been led to the development of the use of this compound in various industries such as bio-medicine, biopharmaceutical, biotechnology, and tissue engineering. The limitation of the industrial development of γ-PGA is the high cost of its production. To reduce γ-PGA production costs, various strategies are used, such as culture medium optimization using inexpensive compounds, the development of efficient cultivation processes of batch and fed-batch. In this research, first, an efficient batch culture medium was developed to produce γ-PGA of
Bacillus licheniformis ATCC 9945
a. Then, the γ-PGA production increased by the pulsed feeding method and its optimization. By optimal culture medium development, the production of this product in batch culture was increased from 11 g/L to 47 g/L. Then, using the optimized pulsed feeding strategy of citrate (γ-PGA precursor), γ-PGA production was increased to 59.5 g/L, which is one of the highest production values reported with this strain. To optimize two-pulse feeding, the effect of feeding times, stock citrate solution concentration, and time of calcium and manganese solutions addition on γ-PGA production were investigated and optimized. Finally, FTIR confirmed the chemical structure of poly gamma glutamic acid, and the study of γ-PGA morphological properties with SEM showed a nanostructure ideal for biological applications.
Volume 13, Issue 58 (0-0)
Abstract
Short and medium infrared radiation implemented as an energy source in drying process under vacuum conditions. Any comparative study was not carried out between these two energy sources in drying process of agricultural products. In this study, effects of short and medium wave of infrared were evaluated and compared on drying behavior of peach slices under vacuum condition. Drying of the samples was implemented under both the energy sources at the absolute pressures of 20, 40 and 60 kPa and drying temperatures of 50, 60 and 70°C. Drying behavior of peach slices as well as the effect of drying conditions on moisture loss trend, effective diffusion coefficient, color and shrinkage of peach slices, dried in an infrared-vacuum dryer were examined. Effective diffusion coefficient of peach slices under medium wave infrared at different drying conditions was more than short wave infrared in the ranges of 2.6×10-11 to 1.4×10-10 m2/s. Total color difference and shrinkage of peach slices under short wave infrared at different drying conditions was less than medium wave infrared in the range of 6.6 to 8.7 and 7.8% to 9.7%, respectively. Minimum total color difference of peach slices under short and medium wave of infrared were obtained 8.2 and 14.8 and minimum shrinkage of peach slices under short and medium wave infrared were achieved 46.7% and 55.9% respectively.
Volume 14, Issue 1 (2-2025)
Abstract
This study investigated the impact of different nitrogen (sodium nitrate, urea, ammonium chloride, and ammonium nitrate) and carbon (sodium bicarbonate, sodium carbonate, and glucose) sources on the growth characteristics, biomass production, pigments, and polysaccharide content of the halophilic cyanobacterium Cyanothece sp. Growth trends were determined by cell density counting, and biomass was assessed by dry weight measurement. Pigment extraction and quantification were performed using spectrophotometry. Polysaccharide extraction was conducted using a hot water bath method at 80 °C. Based on the results, different nitrogen and carbon sources had no significant effect on the growth trend and biomass production of Cyanothece sp. However, the pigment profile and polysaccharide content of Cyanothece sp. biomass were significantly influenced by the different nitrogen and carbon sources in the culture medium. Among the tested treatments, the highest content of chlorophyll a and phycocyanin was obtained in the presence of sodium nitrate and potassium bicarbonate. The highest production of carotenoids and beta-carotene was observed in culture media containing urea or ammonium nitrate along with potassium carbonate. Comparison of the polysaccharide content in Cyanothece sp. biomass among different treatments showed that the culture medium containing sodium nitrate and potassium bicarbonate significantly increased biomass polysaccharide synthesis. Based on the results of this study, for producing Cyanothece sp. biomass rich in phycocyanin pigment with high polysaccharide content, it is recommended to use sodium nitrate and potassium bicarbonate as nitrogen and carbon sources, respectively.
Volume 14, Issue 1 (2-2025)
Abstract
Using nutrient-rich aquaculture effluent as a growth medium for cultivating microalgae can help reduce dependence on chemical culture media. In a 14-day study, the effect of replacing a standard culture medium (control) with shrimp farming effluent (10%, 25% and 50%) on the cell growth of microalgae Nannochloropsis oculata was investigated. The results showed that in the early days (up to the sixth day), different concentrations of wastewater increased cell growth more than the control medium. From the eighth to the tenth day, the amount of cell growth in 10% concentration with 2190 cells per milliliter (day ten) was similar to the control medium, but in higher concentrations of 25% and 50%, a significant decrease in cell growth was observed (p˂0.05). On the twelfth day, the cell growth rate in the effluent concentration of 10% was higher than the control medium (p˂0.05). This shows the potential of shrimp farm effluents for microalgae cultivation in different concentrations, although the optimization of ratios is necessary to avoid the negative effects of toxic substances. Also, the results showed that with the passage of time, the ability of shrimp farming effluent to stimulate cell growth varies. In general, the findings emphasize the importance of using wastewater as a source of cell culture and can lead to the optimization of culture conditions and commercial applications in the cultivation processes of microorganisms.
Volume 14, Issue 4 (3-2011)
Abstract
Entrepreneurship is a general term that is used to both organizations and
individuals. Therefore, we cannot imagine an entrepreneur organization that its
people do not accurately understand about their ability and creativity.
Entrepreneurship acts as a driving force towards people and firms development.
We cannot expect an organization’s development without consideration of its
people. SMEs want that profitable companies should use all of their capacities
and it is easy with entrepreneurship. This paper focuses on the main factors as
management, organizational structure, strategic components, financial and
budgeting systems, evaluation of performance and cultural aspects in SMEs and
surveying of their roles on entrepreneurship filed in companies. The data
required were collected through questionnaires that offered to the employees and
managers of 25 companies in Kurdistan province. The research method was
casual comparative. Findings of the paper showed that entrepreneur firms
mangerial skills have a meaningful difference to those of non entrepreneur
mangers. This result is true for the financial and budgeting systems and
evaluation of performance and cultural characteristics in the studied groups.
There was no significant difference in the structural variables (concentration and
formality) and the strategic aspects (goal setting and policy making) in the two
firms. The results also showed that entrepreneur organizations are more complex
than others. Consequently, the innovators of small and medium enterprises have
a good mission statement in comparison to non entrepreneur firms.
Volume 14, Issue 4 (3-2012)
Abstract
Objective: This study investigated the effects of adipose-derived mesenchymal stem cells (MSCs) and conditioned medium injection on cell infiltration in the brains of an experimental C57BL/6 mice model of autoimmune encephalomyelitis (EAE).
Methods: EAE was induced with myelin oligodendrocyte glycoprotein (35-55 peptides) in 20 mice. MSCs were obtained from the adipose tissue of C57BL/6 mice and cultured with Eagle’s minimum essential medium/alpha medium (DMEM) after removal of non-adherent cells. After 2 to 3 passages, 15 days after induction of EAE, 4 groups (n=5) of C57BL/6 mice were treated as follows: i) MSCs were injected intraperitoneally, ii) MSCs were injected intravenously, iii) conditioned medium was administrated intraperitoneally, and iv) the control group received no treatment. After day 60, the mice brains were removed and the effect of adipose-tissue MSCs and administration of conditioned medium was investigated.
Results: Leukocyte infiltration and clinical scores were significantly reduced in animals that received MSC and conditioned medium compared to untreated animals. Body weight increased significantly in the treated groups compared to the control group. Percentage of survival also increased in the animals that received MSCs and conditioned medium as compared to the control group.
Conclusion: MSCs had immunomodulatory and neurogenerative functions which reduced leukocyte infiltration and improved clinical scores in the EAE animals that received MSC and conditioned medium compared to untreated animals with EAE.
Volume 14, Issue 7 (10-2014)
Abstract
In this paper, the nonlinear behavior, instability and bifurcation phenomena in the response of a cylindrical shallow shell under lateral white noise excitation are studied. The structure interacts with a general non aging viscous medium that can be modeled by relaxation or creep kernels. Using the powerful FPK equation and some practical and logical simplifications, an exact solution for such complex system including nonlinearity, viscoelasticity and randomness is obtained. Since all statistical properties of response such as mean, variance, statistical moments, central moments, etc. can be obtained from the probability density function, the behavior of this function including the number and sign of its roots and their effects on the stability, bifurcation phenomenon and the type of bifurcation is investigated and studied. In this process, using some non dimensional quantities, the governing equation and the probability density function are rearranged such that the results of simulations can be used for a broad band of cylindrical shallow shells. Finally, using some examples, the variations of the non dimensional quantities on the whole behavior, stability and bifurcation type of response are studied.
