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Showing 25 results for Ahmadian
Volume 0, Issue 0 (in press 2024)
Abstract
Shotcrete, a pneumatically sprayed concrete mixture, has gained significant popularity in the construction industry due to its versatility and adaptability. However, the demand for high-strength shotcrete has intensified, driven by advancements in equipment and admixtures. Fiber-reinforced high-strength shotcrete (FRHSS) offers enhanced quality, adhesion, and construction speed, making it ideal for stabilizing excavations and slopes, strengthening masonry and concrete structures, and reinforcing underground structures. Additionally, the increased strength allows for reduced section dimensions, leading to more economical designs.
This research investigates the effects of aggregate gradation and admixtures, including micro silica, superplasticizer, accelerator, and micro recycled steel fibers (MRSFs), on the strength and performance of FRHSS. The study employs wet-mix and dry-mix shotcrete methods, examining the properties through laboratory and field experiments.
The results demonstrate that achieving high-strength shotcrete is more feasible with the wet-mix method. Fiber-reinforced wet-mix shotcrete attained a 28-day compressive strength of 987 kg/cm², representing an 80% and 77% increase in compressive strength and energy absorption, respectively, compared to conventional fiber-reinforced wet-mix shotcrete. Furthermore, fracture toughness tests revealed that MRSFs effectively prevent microcrack propagation and control deformations. FRHSS incorporating MRSFs exhibited a 28% and 97% increase in compressive strength and energy absorption, respectively, compared to the corresponding mix without fibers.
Volume 0, Issue 0 (Articles accepted for Publication 2024)
Abstract
Aim and Introduction
One of the most important issues in Iran's economy is related to managing the exchange rate, inflation and budget deficit. During tightening of the sanctions, the oil revenues are limited which potentially leads to an increase in the budget deficit as well as a decrease in the currency supply which accelerates the exchange rate. On the other hand, with the increase in the budget deficit, the probability of borrowing from the banking system and also the issuance of bonds increases, which in turn rise the monetary base and liquidity. In addition, inflationary expectations also increase, which can be effective in improving assets prices. With an increase in inflation, based on the inflation-currency spiral, there is a possibility of a grow in exchange rate in order to maintain the competitiveness of domestic production. This can accelerate the price of imported commodities and cause domestic inflation again. With the increase in inflation and households spending, nominal wages will have a higher growth compared to normal conditions in order to maintain minimum purchasing power, which can again face the government with limited resources and more borrowing to meet current expenses. From the monetarists’ point of view and the classical economics, in general, the main stimulator in increasing inflation is the growth of money and liquidity. However, from the post-Keynesian economists’ point of view, inflation increases the demand of money and subsequently liquidity. On the other hand, with an increase in the exchange rate, the government's expenses usually increase more than its income, which can lead to an increase in the government's budget deficit. Also, considering the existence of a monopoly in currency supply by the central bank, the hypothesis of using currency exchange revenues (the difference between free and budget-approved currency) will be applicable and this issue can raise the impact of the budget deficit on the exchange rate. Therefore, there has always been a serious challenge among economists as well as macroeconomic decision-makers about the connectedness between macroeconomic variables. What is the main driver of the network between macro variables? Is there a different way of communication in different thresholds of their growth rate? These cases show that it is very important to examine the time-varying interrelationships between these macroeconomic variables.
Accordingly, there is a complex connection between exchange rate, inflation, budget deficit and liquidity, which can be varied in different years. Therefore, in this research, using the TVP-TVAR technique, the time-varying connectedness across exchange rate, inflation, budget deficit and liquidity is examined during March, 2006 to August, 2023.
Methodology
In the current research, the relationship between exchange rate fluctuations, inflation, government budget deficit and liquidity based on monthly data using the TVP-TVAR technique is investigated. It should be noted that all the required information is extracted from the economic indicators of the central bank, and the government's budget deficit data from 2017 onward are extracted from Iran's Program and Budget Organization.
Findings
The results show that exchange rate and liquidity are, respectively, the largest net transmitter of volatilities in the network. Moreover, inflation rate and government budget deficit, respectively, are the largest net receivers of shocks from network. On average, the TCI is 23%, and more than 70% of this interrelationship between variables is explained by other factors such as political ones. Moreover, if the variables underestimated grow up to 36% annually (3% monthly), the connection between them will be cut off. In the conditions of decreasing the growth rate of variables up to -3% per month, the exchange rate has played a dominant role and its volatilities are transferred more strongly to inflation rate and less strongly to the budget deficit and liquidity.
If the growth rate of the variables is up to 24% annually (threshold of +2% monthly growth rate), the exchange rate volatilities are transferred to inflation and no interconnectedness between other variables is observed.
Discussion and Conclusion
Our results show that, on average, the total connectedness index from 2012 to 2016 has been upward, which is caused by the tightening of sanctions and the increase in inflationary expectations, psychological factors and emotions. Moreover, the connectedness between them is increased in 2018 and 2019, which is related to the intensification of sanctions and the reduction of currency supply and the increase in inflation and budget deficit and subsequently the increase in the issuance of debt securities in the capital market in order to manage the budget deficit and as a result increase liquidity. The results show that exchange rate is a main net transmitter of volatilities in most years and the inflation rate is a main net receiver of volatilities in many years. From 2016 onwards, the budget deficit is the net receiver of shocks from network in most periods, except for one period in 2019. It is interesting to note that in 2019, with the increase in the budget deficit and the issuance of debt securities, the budget deficit is transmitter, liquidity is receiver and inflation is more receiver variable than liquidity in the network. Totally, the results show that exchange rate is the major net transmitter of shocks to other macro variables.
Moreover, based on the results of the sensitivity analysis and thresholds effect, if the growth rate of variables is up to 24% annually (threshold of +2% monthly growth rate), the exchange rate fluctuations will be transferred to inflation and no connection between other components is observed. This shows that the macroeconomic management of the economy is very sensitive to the growth rate of the thresholds of the macroeconomic components, and before the political economy and also the factors of expectations and emotions dominated the economy, the macroeconomic management, especially the exchange rate, is required. Otherwise, it is impossible to manage the investigated variables with monetary and fiscal policies. Therefore, the managed floating exchange rate should be taken into consideration and if the goal is to manage the network using macroeconomic theories, the variables should not be allowed to increase by more than 24% annual growth. Other factors such as the political economy, and especially inflationary expectations will get the dominant role in the economy
One of the most important issues in Iran's economy is related to managing the exchange rate, inflation and budget deficit. During tightening of the sanctions, the oil revenues are limited which potentially leads to an increase in the budget deficit as well as a decrease in the currency supply which accelerates the exchange rate. On the other hand, with the increase in the budget deficit, the probability of borrowing from the banking system and also the issuance of bonds increases, which in turn rise the monetary base and liquidity. In addition, inflationary expectations also increase, which can be effective in improving assets prices. With an increase in inflation, based on the inflation-currency spiral, there is a possibility of a grow in exchange rate in order to maintain the competitiveness of domestic production. This can accelerate the price of imported commodities and cause domestic inflation again. With the increase in inflation and households spending, nominal wages will have a higher growth compared to normal conditions in order to maintain minimum purchasing power, which can again face the government with limited resources and more borrowing to meet current expenses. From the monetarists’ point of view and the classical economics, in general, the main stimulator in increasing inflation is the growth of money and liquidity. However, from the post-Keynesian economists’ point of view, inflation increases the demand of money and subsequently liquidity. On the other hand, with an increase in the exchange rate, the government's expenses usually increase more than its income, which can lead to an increase in the government's budget deficit. Also, considering the existence of a monopoly in currency supply by the central bank, the hypothesis of using currency exchange revenues (the difference between free and budget-approved currency) will be applicable and this issue can raise the impact of the budget deficit on the exchange rate. Therefore, there has always been a serious challenge among economists as well as macroeconomic decision-makers about the connectedness between macroeconomic variables. What is the main driver of the network between macro variables? Is there a different way of communication in different thresholds of their growth rate? These cases show that it is very important to examine the time-varying interrelationships between these macroeconomic variables.
Accordingly, there is a complex connection between exchange rate, inflation, budget deficit and liquidity, which can be varied in different years. Therefore, in this research, using the TVP-TVAR technique, the time-varying connectedness across exchange rate, inflation, budget deficit and liquidity is examined during March, 2006 to August, 2023.
Methodology
In the current research, the relationship between exchange rate fluctuations, inflation, government budget deficit and liquidity based on monthly data using the TVP-TVAR technique is investigated. It should be noted that all the required information is extracted from the economic indicators of the central bank, and the government's budget deficit data from 2017 onward are extracted from Iran's Program and Budget Organization.
Findings
The results show that exchange rate and liquidity are, respectively, the largest net transmitter of volatilities in the network. Moreover, inflation rate and government budget deficit, respectively, are the largest net receivers of shocks from network. On average, the TCI is 23%, and more than 70% of this interrelationship between variables is explained by other factors such as political ones. Moreover, if the variables underestimated grow up to 36% annually (3% monthly), the connection between them will be cut off. In the conditions of decreasing the growth rate of variables up to -3% per month, the exchange rate has played a dominant role and its volatilities are transferred more strongly to inflation rate and less strongly to the budget deficit and liquidity.
If the growth rate of the variables is up to 24% annually (threshold of +2% monthly growth rate), the exchange rate volatilities are transferred to inflation and no interconnectedness between other variables is observed.
Discussion and Conclusion
Our results show that, on average, the total connectedness index from 2012 to 2016 has been upward, which is caused by the tightening of sanctions and the increase in inflationary expectations, psychological factors and emotions. Moreover, the connectedness between them is increased in 2018 and 2019, which is related to the intensification of sanctions and the reduction of currency supply and the increase in inflation and budget deficit and subsequently the increase in the issuance of debt securities in the capital market in order to manage the budget deficit and as a result increase liquidity. The results show that exchange rate is a main net transmitter of volatilities in most years and the inflation rate is a main net receiver of volatilities in many years. From 2016 onwards, the budget deficit is the net receiver of shocks from network in most periods, except for one period in 2019. It is interesting to note that in 2019, with the increase in the budget deficit and the issuance of debt securities, the budget deficit is transmitter, liquidity is receiver and inflation is more receiver variable than liquidity in the network. Totally, the results show that exchange rate is the major net transmitter of shocks to other macro variables.
Moreover, based on the results of the sensitivity analysis and thresholds effect, if the growth rate of variables is up to 24% annually (threshold of +2% monthly growth rate), the exchange rate fluctuations will be transferred to inflation and no connection between other components is observed. This shows that the macroeconomic management of the economy is very sensitive to the growth rate of the thresholds of the macroeconomic components, and before the political economy and also the factors of expectations and emotions dominated the economy, the macroeconomic management, especially the exchange rate, is required. Otherwise, it is impossible to manage the investigated variables with monetary and fiscal policies. Therefore, the managed floating exchange rate should be taken into consideration and if the goal is to manage the network using macroeconomic theories, the variables should not be allowed to increase by more than 24% annual growth. Other factors such as the political economy, and especially inflationary expectations will get the dominant role in the economy
Volume 4, Issue 1 ( winter 2021)
Abstract
The purpose of this study is to analyze the challenges of political marketing with the approach of using the soft power of the Islamic Republic of Iran. Categories related to each of them were extracted using content analysis method and these 6 groups were ranked using Friedman test by SPSS26 software. According to the results, the highest ranking was given to the techniques used in international political marketing with the approach of diplomacy, media power, ideological power, cultural power, economic power and management system power. Persuasion and third place became the most prominent dimension of international political marketing, namely national identity. Iran's current position in terms of identity, international prestige and economic identity ranks fourth, restrictions on the use of political marketing ranks fifth with unique ideological approach, financial challenges and theoretical poverty and the most effective Iranian foreign policy discourse ranks sixth with de-escalation and balance discourse approach. Finally, the analytical model of political marketing affected by limitations, necessities and the most significant dimension using effective techniques and the best discourse in promoting Iran's current position in the economic field and strengthening the international image are presented. Practical suggestions are also provided based on research questions for the Ministry of Foreign Affairs, the Economic Deputy of this agency and non-governmental organizations including the Red Crescent and other responsible agencies and organizations.
Volume 5, Issue 2 (summer 2024)
Abstract
Problem: Justice in urban health means the absence of systematic differences in one or more aspects of the health status of citizens or population groups in terms of social, economic and physical environment. In the present study, the city of Urmia has been investigated and analyzed as a focus of studies on the level of realization of the right to health approach to the city and the distribution of health-therapeutic services and functions.
Aims: In terms of its purpose, the current research is in the category of semi-basic, semi-applied research, which is carried out with descriptive and analytical method.
Methods: The methods of collecting information are based on documentary-library methods, observation and field verification (Swara and Cocoso tests).
Findings: Based on the results, the city of Urmia has not acted in a fair manner in terms of the distribution of health-treatment functions and services in accordance with the approach of the right to the city, in spatial planning and allocation.
Conclusion: Regions 4 in the central context and the commercial pole of the city and 2 in the peripheral part of Urmia city have respectively the most favorable and unfavorable environmental conditions and conditions in the matter of enjoying the right to health policies of the city. In the end, based on the findings and the identification of the strengths and weaknesses of the study area in the field of urban development, some targeted and sustainable proposals and actions have been taken to improve the environmental conditions.
Volume 6, Issue 3 (Summer 2020)
Abstract
Aims: 16S ribosomal RNA methyltransferases (RMTases) confer high-level resistance to aminoglycosides and are increasingly reported among Gram-negative bacilli, especially Klebsiella pneumoniae isolates. The objectives of the present study were to assess the resistance to aminoglycosides, the presence of RMTase genes, and the multilocus sequence typing (MLST) in urinary K. pneumoniae isolates.
Materials & Methods: In this study, 100 K. pneumoniae isolates were tested for susceptibility to amikacin and gentamicin by broth microdilution test according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Then the prevalence of RMTase genes was determined, and alleles and ST type of two selected isolates were identified by MLST. Finally, the isolates were genetically typed using Enterobacterial Repetitive Intergenic Consensus (ERIC) method.
Findings: Broth microdilution assay showed that resistance to amikacin and gentamicin was 70 and 52%, respectively. In addition, 40% of the strains were resistant to both aminoglycosides. Also, rmtC (59.8%) gene was the most common type of RMTase genes investigated, followed by rmtA (51.2%), rmtD (47.6%), rmtF (43.9%), rmtE (41.5%), armA (41.5%), and rmtB (7.3%). K. pneumoniae isolates were assigned into two sequence types: ST51 and ST149. Using ERIC-PCR method, 3-7 different bands and 21 ERIC-PCR profiles were detected among the studied isolates.
Conclusion: The high frequency of aminoglycoside resistance and the increased presence of 16S RMTases in K. pneumoniae strains are of great concern in Iran. Molecular typing showed high genetic diversity among the studied isolates. However, ST51 and ST149 were reported for the first time in Iran and could be considered as emerging strains.
Volume 9, Issue 1 (Winter 2018)
Abstract
Aims: Emerging sciences and technologies have huge potential in the field of innovation; therefore, they should be protected against large uncertainties caused by unknown. The aim of this study was to evaluate biotechnology forecasting innovation pathways based on its convergence with other technologies.
Information and Methods: In this systematic review, by the future-oriented assessment of biotechnology innovation pathways, future biotechnology strategies were developed at the national level. All potential applications of the future innovation pathways of this technology were identified in the combination and convergence with nanotechnologies, information, and cognitive science and technology. The strength and weakness of the effects and barriers in all areas of biotechnology were considered in terms of the short-, mid-, and long-term; in the same timeframe, the barriers to these technologies were identified in the field of combined dual technologies and ultimately for biotechnology itself, and future strategies for biotechnology were proposed based on 4 strategies, including ignorance, investment, exploitation, and opportunism.
Findings: In the field of biotechnology- information technology- in the mid-term, the greatest impact was on improving the quality of human life, improving social outcomes, and increasing the level of innovation, and in the field of biotechnology- nanotechnology and biotechnology- cognitive science on improving the quality of human life, increasing security and defending power, and improving the positive social consequences.
Conclusion: The highest number of applications is the mid-term. The "exploitation" strategy should be used in biotechnology- cognitive science and biotechnology- nanotechnology, respectively. The "investment" strategy should be the most widely used in the common areas of biology with information technology. In the common areas of biotechnology with nanotechnology and cognitive sciences, the most application is the “opportunism" strategy.
Information and Methods: In this systematic review, by the future-oriented assessment of biotechnology innovation pathways, future biotechnology strategies were developed at the national level. All potential applications of the future innovation pathways of this technology were identified in the combination and convergence with nanotechnologies, information, and cognitive science and technology. The strength and weakness of the effects and barriers in all areas of biotechnology were considered in terms of the short-, mid-, and long-term; in the same timeframe, the barriers to these technologies were identified in the field of combined dual technologies and ultimately for biotechnology itself, and future strategies for biotechnology were proposed based on 4 strategies, including ignorance, investment, exploitation, and opportunism.
Findings: In the field of biotechnology- information technology- in the mid-term, the greatest impact was on improving the quality of human life, improving social outcomes, and increasing the level of innovation, and in the field of biotechnology- nanotechnology and biotechnology- cognitive science on improving the quality of human life, increasing security and defending power, and improving the positive social consequences.
Conclusion: The highest number of applications is the mid-term. The "exploitation" strategy should be used in biotechnology- cognitive science and biotechnology- nanotechnology, respectively. The "investment" strategy should be the most widely used in the common areas of biology with information technology. In the common areas of biotechnology with nanotechnology and cognitive sciences, the most application is the “opportunism" strategy.
Investigating the Cytotoxic Effect of Pinoresinol and Lariciresinol on Breast Cancer Cell Line SKBr3
Volume 11, Issue 1 (Winter 2020)
Abstract
Aims: Breast cancer is the most common malignancy in women throughout the world. Among the various methods for preventing and treating cancer, plant natural compounds have more benefits than chemical drugs and have less side effects. Recently, many studies have been carried out on the antioxidant, anticancer, antiproliferation, and antiinflammatory properties of plant lignans, indicating the importance of these compounds in the prevention and treatment of various diseases. In the present study, the cytotoxic effects and inducing apoptosis of pinoresinol and lariciresinol lignans were investigated on SKBr3 breast cancer cell line.
Materials & Methods: SKBr3 cells were treated with different concentrations of both pinoresinol and lariciresinol, separately for 72 hours. Then, cell viability and cells morphological changes were determined using MTT assay and inverted light microscope, respectively. Also, apoptosis induction was analyzed by flow cytometry using an Annexin V-FITC apoptosis detection kit.
Findings: Both pinoresinol and lariciresinol treatments induced morphological changes, decreased cell growth, survival, proliferation and a significant increase in apoptosis induction in SKBr3 cell line compared to control cells in a concentration-dependent manner.
Conclusion: Inducing apoptosis and preventing the growth and proliferation of cancer cells are important mechanisms in the treatment of cancer. Pinoresinol and lariciresinol can be used to reduce cell proliferation and increase apoptosis induction in prevention and treatment of breast cancer.
Materials & Methods: SKBr3 cells were treated with different concentrations of both pinoresinol and lariciresinol, separately for 72 hours. Then, cell viability and cells morphological changes were determined using MTT assay and inverted light microscope, respectively. Also, apoptosis induction was analyzed by flow cytometry using an Annexin V-FITC apoptosis detection kit.
Findings: Both pinoresinol and lariciresinol treatments induced morphological changes, decreased cell growth, survival, proliferation and a significant increase in apoptosis induction in SKBr3 cell line compared to control cells in a concentration-dependent manner.
Conclusion: Inducing apoptosis and preventing the growth and proliferation of cancer cells are important mechanisms in the treatment of cancer. Pinoresinol and lariciresinol can be used to reduce cell proliferation and increase apoptosis induction in prevention and treatment of breast cancer.
Nahid Ahmadian,
Volume 12, Issue 47 (Fall 2019)
Volume 12, Issue 47 (Fall 2019)
Abstract
Among the plays of Rezā Kamāl, three works, Shab-e Hezār-o Yekom, Abāseh Khāhar-e Amir and Aziz-o Azizeh, are known as his adaptations of One Thousand and One Nights stories. These works aim to introduce a new appraoch to thetrical expression by utilizing the potentialities of the orginal texts. The present study reads Kamāl’s adaptations of One Thousand and One Nights stories in the light of Linda Hutcheon’s adaptation theory in order to show the extend to which his plays provide theatrical affordances in the dramatic texts. As a result, the study shows how far these adaptations have succeeded in articulating the requirements of the stage while being in conversation with the original text.
Volume 13, Issue 2 (4-2010)
Abstract
Objective: Cryptosporidiosis is a parasitic disease that is causing small protozoan genus Cryptosporidum and transmission take place through fecal- oral by direct contact or indirectly through food or drink. The aim of this study was detection of anti-Cryptosporidum parvum Immunoglobulin IgG, in newborn BALB/c infected with C. parvum. Materials and Methods: Oocysts of C. parvum were obtained from the feces of diarrheic lambs and following purification they were suspended in 2.5% aqueous potassium dichromate solution and stored at 4°C. Forty suckling BALB/c (3–4 days old) were divided in 8 groups (4 case groups and 4 control groups) each group consist of 5 suckling BALB/c. The mice in case groups were infected oraly with 105 C. parvum oocysts, and the mice in control groups served as non-infected. Blood samples were collected at 6, 9, 12 and 16 days post-infection (pi). Immunoglobulin IgG were extracted by salting out method and confirmed with SDS-PAGE. Results: Antibodies were analyzed by western blot and increased secretion of IgG was confirmed in neonatal mice infected with Cryptosporidum oocysts. Mean OD of Immunoglobulin IgG increased from 0.350 ± 0.099 to 0.6776 ± 0.099 in case groups but in control groups the increase was from 0.244 ± 0.016 to 0.322 ± 0.16 (P<0.05). Conclusion: The type of antibody in neonetal mice infected with Cryptosporidum oocysts was IgG which is secreted against external memberane of oocysts. Significant differences in neonatal mice case groups as compared with the control groups were observed.
Volume 13, Issue 4 (1-2023)
Abstract
Evaluating the response of the stem cells to different mechanical stimulation is an important issue to obtain control over cell behavior in the culture environment. One of the effective parameters in the mechanoregulation of stem cells is the microstructure of scaffolds. Evaluating the effect of microstructure of scaffold in the lab environment is very complicated. Therefore, in this study, the effect of scaffold architecture on mechanical factors in the scaffold was investigated under oscillatory fluid flow by using numerical modeling. In this study, distribution of shear stress and fluid velocity in three types of scaffolds with spherical, cubical and regular hexagonal pores with length of 300, 350, 400, 450 and 500 micrometers were investigated by using computational fluid dynamics method. The results of the computational fluid dynamics model showed that the scaffold with spherical and cubic pores shape with length of 500 micrometers and scaffold with hexagonal pores with length of 450 micrometers experienced shear stress in the range of 0.1-10 mPa. This range of the shear stress is suitable for differentiation of the stem cell to bone cells. Moreover, the result of exerting oscillatory fluid flow to these scaffolds indicated that dead zones of the scaffold, where isn’t suitable for cell seeding, was decreased due to the access of fluid flow to the different area of scaffold. The results of this study can be used in a laboratory to achieve optimal stem cell culture to provide suitable environment culture for differentiation of stem cells toward the bone cell.
Volume 14, Issue 1 (5-2014)
Abstract
Transmission network expansion planning is a challenging problem with the aim to determine the type, location, and time of the equipment to be added to the existing transmission network in order to desirably meet the increasing load demand. On the other hand, reactive power sources are the other important components of the power system, which are used improve voltage profile and maintain the system stability. This paper, presents a comprehensive AC load flow based framework for concurrent expansion planning of transmission networks and reactive power resources. Although major advances have been made in optimization techniques, finding an optimal solution to a problem of this nature is still challenging. Using some linearization techniques, a mixed-integer linear programming (MILP) model for transmission expansion and reactive power planning is proposed. In order to show the influence of the concurrent transmission network expansion and reactive power resources planning in reducing investment costs, simulation studies and analysis of the numerical results are carried out on the Garver 6-Bus and the standard IEEE 24-bus test system.
Volume 15, Issue 1 (March & April (Articles in English & French) 2024)
Abstract
While different models and questionnaires have been devised and used to measure learners’ willingness to communicate in a second language (L2 WTC), to date, few scales, if any, can be found to measure foreign language teachers’ L2 WTC (FLT WTC). Therefore, the current project was designed to address this gap in the literature through an empirical investigation of the factors affecting FLT WTC. Consistent with an inclusive review of the literature and expert panel consultations, a model of contributing factors to FLT WTC was hypothesized, a representative questionnaire was devised and went through Exploratory Factor Analysis and Confirmatory Factor Analysis. A large scale of 1044 foreign language teachers participated in different stages of the study. The statistical indices of the study confirmed that the model was fit and the questionnaire established appropriate levels of reliability, and face, content, construct, convergent, and discriminant validity. It was found that teacher perceptions, student traits, classroom atmosphere, classroom settings, and discussion topics play significant roles in FLT WTC. The study can draw the teachers’ / institutes’ attention to the factors affecting FLT WTC, and the validated questionnaire can be used as an instrument to measure FLT WTC in future studies.
Volume 15, Issue 3 (10-2012)
Abstract
Objective: The goals of the study are evaluation the effect(s) of food deprivation as a social stress on testis structure. We also investigated the effects of melatonin treatment as an antioxidant component and inequality on the effect(s) of food deprivation. Methods: We investigated the improving effects of melatonin and social stress (food deprivation) on 42 male rats in 7 groups including control, sham, melatonin received (M), food deprivation (1/3 of control daily food) plus observation (FD), FD + melatonin (FDM), isolated FD (FDi), and FDi + melatonin (FDMi) groups. After 14 days, rats' testes were studied using immuno histochemistry and TUNEL assays to determine the number of apoptotic cells. Biochemical evaluation was taken on malodialdehide (MDA) and glutathione (GSH). ANOVA and Tukey's tests were done to analyse the data. PResults: The results of sham group was declined for similarity to results of control group. In FD group, MDA was increased significantly (PConclusion: Food deprivation can induce oxidative stress which is associated with increasment of apoptotic cells in testis. Isolation can compensate these effects. These results refer to inequality. Since melatonin is recognized for its anti-oxidative and improving effects, we have shown involvement of oxidative stress mechanisms on the stress of food deprivation with inequality.
Volume 15, Issue 7 (9-2015)
Abstract
Traumatic brain injury (TBI) has long been known as one of the most unspecified reasons for death around the world. This phenomenon has been under study for many years and yet questions remain due to its physiological, geometrical and computational complexity. Because of the limitations in experimental study on human head, the finite element human head model with precise geometric characteristics and mechanical properties is essential. In this study, the visco-hyperelastic parameters of bovine brain are extracted from experimental data and finite element simulations which are validated by experimental results. Then a 3D human head including brain, skull, and the meninges is modeled using CT-scan and MRI data of a 30-years old human. This model is named “Sharif University of Technology Head Trauma Model (SUTHTM)”. After validating SUTHTM, the model is then used to study the effect of G acceleration. Damage threshold based on consciousness in terms of acceleration and time duration is developed using HIC and Maximum Brain Pressure criteria. Results revealed that Max. Brain Pressure ≥ 3.1 KPa and HIC ≥ 30 are representative of loss of consciousness. Also, 3D domains for the loss of consciousness based on Max. Brain Pressure and HIC criteria are developed.
Volume 16, Issue 3 (5-2016)
Abstract
In this paper, a new model called connective layer is developed for simulation of linear dynamical behavior of bolted lap joints and model updating in 3D models. Connective layer unifies neighboring zones on sides of common surfaces of substructures in joint region. The constitutive relation of connective elements is defined by decomposing it into its normal and shear components. Unknown and different elastic properties with respect to the neighboring solid elements are defined for connective layer and the unknown parameters of the model are identified by a finite element model updating technique using modal test data. The frequency response of the structure is measured by exciting the structure using an impact hammer. Using an optimization algorithm in ANSYS, the difference between the experimentally measured frequencies and the predictions of the parametric model is minimized as objective function. The connective element performance is demonstrated by application to an actual structure containing a single lap bolted joint coupling two identical aluminum alloy 7075-T651 beams and finally comparison of results to those of interface elements. The outcomes of presented model have good correlation with experimental results. The proposed method predicts the higher mode frequencies which don’t have participation in model updating process with minimum error in comparison to those of interface element. Due to simplicity, accurate and computationally efficient manner, this model can be incorporated into commercial finite element codes to simulate bolted joints in large and complex structures.
Volume 16, Issue 11 (1-2017)
Abstract
As regards to daily developments in technology, applications of carbon nano tubes (CNTs) in manufacturing of many devices and equipment are widely promoted. Many sensors, nanomachines, and enhancement of oil, petrochemical and aerospace technologies are some of CNTs applications. With regard to importance and a wide range of these applications, recognition and investigation of CNTs behavior is extremely significant. CNTs have a little curvature naturally, hence they are predominantly subjected to different transverse loads. In this research, based on nonlocal elasticity theory, possibility of snap_through and bifurcation behaviors of arch shaped CNTs due to sinusoidal load distribution and on elastic foundation, are investigated and corresponding graphs are plotted. To obtain buckling critical loads, essential stability equations are derived. Finally the results of classic theory are compared with the results of nonlocal theory and it is indicated that the dimensionless scale parameter(λ), has a key effect on possibility of happening of the buckling and its type. According to the results and plotted graphs, in most cases, increase in dimensionless scale parameter(λ) has leaded to increase the possibility of bifurcation phenomena and some other cases, helped to transition from snap_through to bifurcation, meaning that the possibility of happening of the snap_through phenomena has been declined.
Volume 16, Issue 86 (4-2019)
Abstract
Kefir is a traditional beverage that is produced by fermented milk with kefir grains, Kefir grains are complex mixture of bacteria, yeasts, and polysaccharides produced by this micro flora. The initial amount of kefir grains used to produce kefir drinks affects the quality of the beverage in terms of pH, viscosity and microbial characteristics of the final beverage. In this study, the effects of different levels of starter (4, 6 and 8%, containing Streptococcus thermophilus, Lactobacillus delbrueckii subsp. Bulgaricus, Bifidobacterium), yeast Saccharomyces cerevisiae (2, 3 and 4%) and storage time (24, 48 and 72 hours after inoculation) on the physicochemical and microbiological properties of kefir beverage was studied using a central composite design and response surface methodology, in order to produce a product with higher probiotic bacteria than yeast. Physicochemical properties including acidity, pH, ethanol, apparent viscosity and flow behavior parameters, as well as microbial counting was performed. According to the results of the tests, the amount of yeast had the most effect on apparent viscosity and by increasing the amount of yeast and during of storage time, the apparent viscosity and consistency coefficient decreased. In addition, the viscosity increased with increasing starter rates. Regarding the amount of ethanol, the amount of produced ethanol increased by increasing the amount of yeast and during the storage time due to the increase in the amount of yeast and finally the microbial count decreased during storage. Optimization results showed that the sample containing 2% yeast and 4% starter in time 38 hours after inoculation had the lowest amount of ethanol and was suitable for rheological properties.
Volume 18, Issue 1 (4-2015)
Abstract
Objective: Organophosphorus (OPs) compounds are widely used in many pesticides, insecticides and chemical nerve agents. These compounds are hazardous for humans and the environment. Organophosphate hydrolase (OPH) is a homodimeric protein initially isolated from Pseudomonas diminuta MG and Flavobacterium species. This enzyme is able to degrade a broad spectrum of toxic OPs compounds. Using immobilized OPH commonly presents a variety of advantages versus the free form of the enzyme. Advantages include an increase in stability, cost reduction by simple recovery and reutilization of the enzyme, quick and easy separation of the reactant and product in the reaction medium. Methods: Plasmid pET-26b (+) was used to generate the OPH protein under the control of the T7lac promoter. E. coli BL21 (DE3) pLysS was used as the host for expression of the OPH enzyme. Recombinant OPH was secreted into the extracellular medium and the purified enzyme was immobilized on the surface of Bacillus subtilis spores by the adsorption method, for the first time. Results: Approximately 42% to 45% enzymatic activity was determined to be associated with spores. Optimal pH and temperature of the enzyme were not altered by the presence of the spores. Thermo and pH stabilities of the immobilized enzyme was higher than the free form of the enzyme. Conclusion: Bacillus subtilis spores are safe for humans and the environment. Therefore this system can be considered an environmentally friendly biocatalyst for degradation of OPs.
Volume 18, Issue 1 (Spring 2018 2018)
Abstract
Natural resources generate the major part of national wealth in resource-rich developing countries. Based on economic theories, if natural resource rents are reinvested continuously in other forms of capital, such countries can benefit from these resources. Thus, examining the mechanism of how to rents affect economic growth through capital accumulation channels is of great importance. Because of the importance of management of resource rents in achieving sustainable growth and development in resource-rich countries, this paper investigates the impacts of resource rents on accumulation of four kinds of capital (foreign, physical, human and social capital) in Iran during 1970-2014. To this end, a simultaneous equations system consisting of various capital forms is designed, and estimated by using Seemingly Unrelated Regression estimator. According to the findings, resource rents have positive effects on accumulation of foreign, human and social capital in Iran. But it is of negative effect on accumulation of physical capital. The results show that physical capital is affected by natural resource rents more than other kinds of capital. This is because of unproductive government investments in physical capital, hence not only resource rents increase physical capital but also they affect physical capital negatively.
Volume 19, Issue 133 (February 2023)
Abstract
Although application of sweeteners and thickeners substituting sugar in food products is effective in reducing the calorie intake, but it is usually accompanied by changing the product texture. Reducing sugar in the formulation of jelly powder using stevia as a strong sweetener composition and quince seed gum with respect to the qualitative properties of the product was analyzed in this study to investigate the possibility of substituting stevia with sugar. Different percentages of stevia (with 0, 25, 50, 75, and 100% sugar) were prepared along with quince seed gum, and the jelly samples were evaluated with regards to the rheological properties by using the strain sweep test measurement at constant frequency of 1 Hz, frequency sweep at the strain of 0.1% and frequency range of 0.1 to 10, as well as the creep test and the power-low equation. The results obtained from adding stevia and quince seed gum to the jelly powder sample showed that increasing the rate of stevia reduced the storage module, while the existence of sugar and quince seed in the jelly powder formula increased the storage module. The Newton viscosity of the samples increased by increasing the rate of stevia, while the immediate and delayed disintegration modulus decreased by increasing the rate of stevia. The results indicated that in addition to reducing the rate of calorie intake, substituting a part of sugar with stevia in the jelly powder can cause main changes in the rheological features of the jelly powder, reduce the elasticity module and increase the viscosity module, and by adjusting the rate of sugar substitution with stevia, it can be used as a commercial replacement in the industry.