Showing 12 results for Sahebi
Volume 2, Issue 2 (Number 2 - 2000)
Abstract
ABSTRACT Tomato spotted wilt virus (TSWV) was detected in tomato leaf and fruit samples collected from Viiramin reyion in Tehran province using indicator test plants including Petunia hybrida, Nicatiana glutinosa, N. tabacum cv. Snmsun NN, N. clevelandit and N. benthamiana and seroloyical tests. Small browinsh local necrotic lesions appeared on P. hybrida leaves 2-4 days post-inoculation. Systemic symptoms included concentric ring spots on leaves, stem necrosis, wilting and tissue collapse of plants 7-10 days following the inoculation. Among 145 tomato samples collected from Ghazvin, Hashtgerd, Karaj, Malard, Shahriar and Varamin in Tehran province, only Varamin samples were infected with TSWV using EL1SA, DIBA and SSEM. TSWV host range specificity and symptom expression were tested on Capsicum annuum L., Chenopodium amaranticolor I«, Citrullus vulgaris L., Oicumis melo var. inodorus, C. mela var. reticukUus, C. salivas L., Lycopersicon esculentum Mill., Phasenlus vulgaris L., Solatium melongena 1- and S. tuberosum. Typical symptoms on these plants included concentric ring spots, chlorosis, vein clearing, tissue necrosis, stunting and local lesion formation. Antiserum prepared against a partially purified TSWV preparation cross-reacted with TSWV-infected tomato samples.
Volume 5, Issue 2 (8-2014)
Abstract
β- Xylosidase from Selenomonas ruminantium (SXA) is one of the most important enzyme for the hydrolysis of cell wall hemicellulose. SXA has potential utility in industrial processes especially production of bioethanol from bagasse. However, this xylosidase lose activity drastically above 50 °C. Each monomer of this homotetramer has four free buried cysteine. It seems that cysteine 286 has no role in protein function. In this study, to investigate effects of free buried cysteine on protein thermal stability, Cys 286 was replaced with the same size amino acid, valine. The mutant and native protein have expressed in Pichia pastoris. Kinetic and thermostability parameters of mutant were compared with the wild type enzyme. While pH optimum, temperature profile and catalytic efficiency of recombinant mutant were be found similar to native enzyme, mutant showed about 65% increase in thermostability respect to the wild type at 55 ˚C. Our results showed that free thiol group of cysteine caused the destabilization. Moreover, hydrophobic side chain of valine could involve in a hydrophobic interaction to stabilize SXA. Elimination of a free cysteine enhanced thermal stability without changing the catalytic efficiency of the enzyme that could be very important for biotechnological applications.
Volume 7, Issue 1 (Winter 2022)
Abstract
Aim: Patient safety is one of the most important parameters of quality health care. The role of health care workers in providing safe care is essential, and their positive attitudes towards this issue will positively affect patient safety. This review aimed to investigate the attitudes of health care workers towards patient safety in Iran.
Method and Materials: The Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA) guideline was used to conduct the present review. Data resources including SID, Magiran, Scopus, PubMed, ISC, Web of science, and Google Scholar were chosen to conduct the literature search both in Persian and English without any time limit until the end of January 2021. Inclusion criteria included all English or Persian language studies in which the Safety Attitude Questionnaire (SAQ) was used to assess the attitude of Iranian health care workers towards patient safety.
Findings: In the primary search, 342 studies were obtained, finally 11 of which were reviewed. Among these, 10 studies had cross-sectional designs, and one study was a quasi-experimental research. Overall, 2162 health care workers were analyzed. The results of the present study showed that most health care workers in Iran had unfavorable attitudes towards patient safety.
Conclusion: As upgrading health care workers’ attitudes seems necessary to improve patients’ safety, it is recommended that health organizations provide regular patients’ safety training, both at employment time and during service to the health care workers who are in direct and indirect contact with patients.
Volume 9, Issue 2 (Number 2 - 2007)
Abstract
Zucchini yellow mosaic virus (ZYMV) is a potyvirus with a worldwide distribution. This virus causes serious economic losses in Iran in many cucurbits. During 2002-2003, sam-ples were collected from squash fields in Tehran Province. Five isolates (Z1, Z2, Z3, Z4 and Z5) were inoculated on 27 species of Cucurbitaceae, Chenopodiaceae, Amarantha-ceae,Solanacae, Leguminosae and Ranunculaceae. Chenopodium quinoa and C. amaranti-color showed chlorotic local lesions. Gomphrena globosa developed necrotic local lesions. Systemic symptoms were produced in the members of Cucurbitaceae and Ranunculus sardous. Z2, Z4 and Z5 caused mosaic symptoms on Phaseolus vulgaris cv. Red Kidney and P. vulgaris cv. Khorram but Z1 and Z3 caused chlorotic local lesions.Virus was puri-fied from Cucurbita pepo. Virus particles in immunoelectron microscopy were filamentous flexuous. The molecular weights of coat protein using SDS-PAGE and western blotting were estimated at 32 kDa. Reverse transcription polymerase chain reaction (RT-PCR) was performed using one primer pairs designed by Desbiez et al. An approximately 458 bp fragment was amplified with a specific primer.
Volume 11, Issue 4 (3-2022)
Abstract
With the outbreak of the Covid-19 virus and the critical business environment for both organizations and employees, the issue of organizational support and social organizational behaviors has become increasingly important. Therefore, this study examines the relationship between perceived organizational support and employees' organizational social behaviors during the Covid-19 virus outbreak and also examines intermediate relationships of affective commitment and knowledge sharing behavior. This research is applied in terms of purpose, and in terms of method, it is descriptive-survey and correlational. A questionnaire was used to collect data. After confirming the validity and reliability of the questionnaire, data were collected by selecting 675 samples. The statistical sample was selected by convenience sampling method from the employees of Refah chain store companies and the data were analyzed using structural equation modeling using Smart PLS software. Findings showed that the Covid 19 virus epidemic has led to more organizations paying attention to employees and employees' higher understanding of organizational support. Also, a positive and significant relationship between perceived organizational support and knowledge sharing on
affective commitment was confirmed. affective commitment also had a significant and positive relationship with civic virtue and innovative behavior, but not a significant relationship with altruism. Finally, mediating roles and reinforcing affective commitment and knowledge sharing were endorsed. The results and suggestions of this research are used in recognizing and optimizing human resource management for managers.
Volume 13, Issue 3 (10-2013)
Abstract
Abstract:
A large number of slabs (floor and roof) in industrial and residential buildings were constructed by steel I-beam, brick Jack arch slab in Iran. Jack arch masonry flooring system consists of a number of closely-spaced, parallel steel I-beams and a number of shallow brick arches filling the spaces between the steel beams. The spaces over the arches are then filled to create a flat floor. This kind of slab did not indicate suitable reaction during past earthquakes. Collapse of a large number of these non-homogeneous one-way slabs during past earthquakes has highlighted their poor seismic performance. They do not behave as rigid elements. However, due to their easy construction together with low cost, the jack-arch slab is still widely used in many countries. Thus it is necessary to study the rigidity of this kind of slabs by more accuracy. The objective of this paper is to evaluate the rigidity of the jack arch slab and influence of X-shaped bars and top layer concrete in their rigidity using nonlinear analysis (Ansys software). Finite element numerical analyses are then conducted to investigate the effects of a number of parameters on the rigidity of the slabs. In addition, appropriate tables and figures are presented to facilitate the investigation of the jack arch slabs. For this purpose, several steel-framed structures constructed by jack arch slab with different terms were selected. These terms consist of, number of buildings stories (one, two and three stories), diameter of bars (14, 16, 18 and 20 mm), thickness of top layer concrete (6, 8 and 10 cm) and different areas of slabs (3.6×3.6, 3.6×4.5, 3.6×5.4 and 3.6×6.3 m). To consider the rigidity of slabs, the 2800 standard's regulations were applied. According to the rules and regulations of standard no. 2800, the slab will be rigid if the ratio of relative story displacement and diaphragm displacement to be less than 0.5 and the slab will be flexible, if this ratio to be greater than 0.5. The result of an experimental model was used to clarify the result of this research. It was shown that the result of experimental model was in conformity with this research one. At the end two expressions was suggested for determination of bars diameters and the concrete layer's thickness needed for rigidity of jack arch slab
Volume 14, Issue 2 (summer 2024)
Abstract
In recent decades, digitalization has emerged as a key factor in the transformation of industries. Along with the advances that digitization has brought for industries, environmental and social issues have also been challenged. In this context, Toman's use of lean production principles along with digital technologies has emerged as a sustainable strategy in order to reduce the negative effects on the environment, society and the challenges facing it. But the important point in between is the importance of social aspects along with technical aspects. The underlying importance of the category of culture as a social aspect in the organization is of great importance for the foundation of these principles. For this reason, in this research, the digitization of production has been investigated on sustainable performance with the mediating role of lean production and moderator of lean culture. The statistical sample consisted of 211 companies active in the value chain of automobiles and related parts, and a standard questionnaire was distributed among them using a simple random method. Smart-PLS3 software was used for analysis. The results of the hypothesis test showed that digitization and lean production have a significant effect on the realization of sustainable performance. Also, by using digital technologies and establishing a pure culture, it is possible to improve the performance of industries and reduce environmental and social impacts.
Mahdi Sahebi, Ahmad Reza Azimian,
Volume 15, Issue 10 (1-2016)
Abstract
Thermal creep is often associated with the flowing of a rarefied gas via the effect of temperature difference in solid boundaries. Recently the feasibility of such flow in dense fluids becomes a challenge. This paper deals with simulating the thermal creep flow in liquids confined in nanotubes. The investigations are carried on by molecular dynamics simulation method. The goal of this work is providing a clean picture of the thermal creep phenomenon mechanism in liquids. Simulation results show the existence of such flow in liquids in nanotubes. The thermal creep effect is stronger in nanotubes with narrower cross sections. Molecular data provided by the simulations shows there is a fluid layering phenomenon near the solid wall. The fluid layering together with the wall temperature gradient develops a pressure gradient near the wall. This pressure gradient acts as a planar force and is assumed to be responsible for the thermal creep effect. This force causes the fluid to flow toward the hot side of the tube. The mechanism of thermal creep phenomena is justified by the use of molecular principles and molecular data which are obtained from the molecular dynamics simulations.
Volume 17, Issue 2 (Summer 2013)
Abstract
آشکارسازی تغییرات پوشش اراضی اهمیت بسزایی در برنامهریزیهای محیطی توسعه پایدار دارد. در این زمینه، آنالیز تصاویر چندزمانه سنجش از دور روشی کارآمد در استخراج این تغییرات است. بدین منظور، روش مقایسه پس از طبقهبندی، روشی رایج در استخراج تغییرات پوشش اراضی شناخته شده است. باوجود این، این روش به دلیل بهرهگیری از طبقهبندی کنندههای سخت، دقت مناسبی در حضور پیکسلهای مخلوط ندارد و عدم قطعیت بسیار زیادی در ماتریس تغییرات حاصل از آن وجود دارد. در تحقیق حاضر، ابتدا روشهای مختلف آشکارسازی تغییرات دستهبندی شده و روشی مبتنی بر استفاده از نقشههای نسبتی حاصل از طبقهبندی نرم، برای استخراج اطلاعات دقیق تغییرات پیشنهاد شده است. این روش علاوه بر استخراج مناطق تغییر یافته/ نیافته، ماتریس کامل تغییرات (میزان تبدیل کلاسهای مختلف به یکدیگر) را نیز با دقت زیرپیکسل امکانپذیر ساخته است. با پیادهسازی این روش بر تصاویر چندزمانه منطقه مورد مطالعه، نتایج حاصل با نتایج به دست آمده از روش مقایسه پس از طبقهبندی مقایسه و ارزیابی شده است. از دستاوردهای مهم تحقیق این است که روش مقایسه پس از طبقهبندی میزان تغییرات را به طور متوسط 2/9 درصد کمتر از روش پیشنهادی برآورد کرده است. همچنین، تفاوت نتایج دو روش درمورد پوشش اراضی غیرهمگن نسبت به پوشش همگن، به مراتب بیشتر است. به طور کلی، به دلیل درنظر گرفتن سهم کلاسها در سطح پیکسل، روش پیشنهادی با دقت بالایی ماتریس تغییرات پوشش اراضی را تولید کرده است و میتواند در مدیریت منابع طبیعی مورد استفاده قرار گیرد.
Mohammad Mahdi Sahebifard, Alireza Shahidi, Saeed Ziaei-Rad,
Volume 17, Issue 4 (6-2017)
Abstract
This article aims to study the effect of membrane initial configuration and the membrane spontaneous curvature (local asymmetry of layers) on the shape transformation of lipid bilayer vesicles. Since the evolutionary models are considered as a generalization to the equilibrium methods, the used model is developed based on the dynamic equilibrium between the membrane bending potential and the environmental fluid friction in each domain of two-phase vesicle. The effect of membrane inertia on the dynamics of the system is ignored. Key parameters are the size of each phase and different combinations of protein distribution as the local spontaneous curvature. Assumed initial conditions are simple shapes such as dumbbell, biconcave and oblate that free vesicles are usually visible in these shapes. Previously published experimental observations are used to evaluate the numerical results. Some situations of homogeneous and multi-phase vesicles and red blood cells under the influence of the spontaneous curvature induction mechanisms (for example the composition of the membranes, membrane proteins such as albumin, environmental solution concentration changes) are simulated and the results presented in details. The possibility of the membrane deformation and the relation of membrane phenomena with the primary form and various curvature distributions are discussed.
Zeinab Sahebi, Majid Yarahmadi,
Volume 18, Issue 2 (4-2018)
Abstract
In this paper, a new hybrid adaptive intelligent controller is introduced to track a dynamic trajectory in finite dimensional closed quantum systems. The problem of inherent singularities in control signals of trajectory tracking in quantum systems leads to a sharp increase in control signal amplitude. As a result, the amplitude of the large signal increases the control cost and control system instability. Consequently, the large control signal amplitude increases the control cost and leads to instability in control system. Firstly, according to the Lyapunov stability theory, an adaptive controller is designed to track the dynamic path. Then, to overcome the singularity drawback, a quantum intelligent controller is designed based on a quantum adaptive wavelet neural network with batch back propagation learning and combined with adaptive controller by a singularity observer. The proposed hybrid adaptive intelligent controller by combining the adaptive and intelligent control signals adjusts the quantum state so that the desired dynamic trajectory is traced effectively and simultaneously eliminates the effects of singularities and reduces the control amplitude. The performance of the hybrid adaptive intelligent controller is checked for step response tracking in a population transfer of a four-level closed quantum system. The simulation results show that the introduced controller reduces the tracking error and significantly decreases the number of singular points. Also, the control cost is reduced by effective adjustment of the control signal’s amplitude.
Volume 23, Issue 4 (10-2023)
Abstract
Two of the important issues in the construction of structures located in seismic coastal areas are the study of the potential of liquefaction phenomenon in saturated sandy soils and seismic structure-foundation-soil interaction (SSFSI). Control of structure damage on the liquefiable soil and large deformations of soil due to seismic loading and, also, the other responses such as: the accelerations at top of the structure/foundation and excess pore water pressure related of this phenomenon are very important. The phenomenon of liquefaction happens due to the occurrence of an earthquake and due to the lack of sufficient opportunity for drainage of excess pore water pressure. One of the effective and useful mitigation methods to control of the liquefaction phenomenon is the usage of dense granular column (DGC) in appropriate dimensions and distances on the ground susceptible to liquefaction. The role of the DGC in controlling the liquefaction phenomenon are follow as: firstly, the DGC is made of materials that are more permeable to sandy soils and cause the excess pore water pressure to be dissipate faster, and secondly, DGC increases the stiffness of the system, which proportionally reduces the excess water pore pressure due to the dilative behavior. To reduce the risks of liquefaction, it is necessary to fully understand its consequences. These consequences depend on permanent soil displacements, structural performance, structural characteristics, foundation and structure dimensions, soil conditions of the structure site, type of loading and earthquake intensity. The presence of the structure and impact of SSFSI affects the intensity of liquefaction and static and dynamic stresses in the soil. Most prior studies (e.g., physical, numerical, or analytical models), ignore the existence of the structure or consider the effect of soil-structure interaction (SSI) on the liquefiable soil layer as an equivalent model. Hitherto, the essence and extend of these interactions are not sufficiently understood. These methods can not properly assess the damage caused by liquefaction; Therefore, these methods cannot be used in the design of structures resistant to liquefaction. Therefore, to accurately study the effect of liquefaction, a method and model is needed that can fully consider the soil, foundation, and structure so that it can be used to correctly estimate the amount of subsidence and displacement of the structure. In this study, to evaluate the seismicity and the mitigation effect of DGCs, using OpenSees finite element software, modeling of DGCs and surrounding soils without structure and models with 5, 10 and 15 storey structures were performed. The three-dimensional soil and DGCs modeled in the software are placed under different earthquakes and the effects of structural layers on the lateral displacement, excess pore water pressure, response of acceleration spectrum, drift and shear force of stories are investigated. The liquefiable soil is modelled through the pressure-dependent multi yield surface soil constitutive law (PDMY02) applied in OpenSees. The results of this study are shown the positive effect of DGC on the reduction of lateral displacement components of soil and structure, foundation subsidence and excess water pore pressure. Also, the presence of the structure on the soil and the increase of its floors have increased the mentioned components except for lateral displacement of soil.
