فهرست مطالب a. hassani

This paper investigates the quasi-static compressive strength of two sandwich structure designs in which cores consist of trapezoidal corrugated panels. In one design, the core consists of a steel cross-corrugated two-layered structure, while in the other design, the core consists of a single layer of bidirectional interconnected corrugated core made of ST37 steel sheets. To investigate the energy absorption capacity of these sandwich structures quasi-static compression is performed numerically and experimentally. First, from each design, a test specimen is constructed and tested under quasi-staticcompressive load. Following that, the finite element models of the designs are constructed and their crushing process is simulated and the FEM method results were compared with the test results and the FE model is verified. After verification of the numerical model, for each design, three different trapezoidal wave profiles are modeled and, the mechanical behavior of the other bidirectional interconnected corrugated cores is evaluated numerically. The results showed that the maximum force and energy absorption capacity of the sandwich structures with the single-layered bi-directional interconnected corrugated core is higher than the strength and energy absorption capacity of their counterparts with the same weight in the two-layered bi-directional corrugated core group with the same weight. It was also found that, inthe single-layered bi-directional interconnected corrugated core group, the failure mode is plasticity near the welding joints, while for the single-layered bi-directional interconnected corrugated core, the failure mode is plastic buckling of the corrugated core under compressive load and some local plastic deformation in the connection of the layers.

Oregano (Origanum vulgare L.) is a perennial herbaceous plant belonging to the fam. lamiaceae that is used as a spice for flavoring foods and also for medicinal purposes as carminative, diaphoretic, expectorant, sedative, stomachic, diuretic, antitussive, and antirheumatic. To evaluate the effects of salinity stress on some growth and physiological parameters, essential oil content, and nutrients absorption in two oregano subspecies, a factorial pot experiment was conducted in a completely randomized design with three replications. The experimental factors included two subspecies of oregano (ssp. vulgare and ssp. gracile) and salinity stress at four levels (0, 25, 50, and 100 mM of NaCl). The results showed that the salinity stress had a significant effect on the measured parameters. With increasing the salinity level, the growth characteristics (plant height, stem diameter, number of leaves, and dry matter yield), leaf relative water content (RWC), chlorophyll index (SPAD), percentage and essential oil yield, N, P, and K content and K/Na ratio in leaves and roots decreased, while Na and Cl content in leaves and roots of both subspecies increased. The two subspecies response to the different levels of salinity stress was different. The higher Na accumulation in the roots and higher K/Na ratio in the leaves compared to the roots indicated the ability of oregano subspecies to limit the transfer and accumulation of Na+ ions in their shoots. Overall, the findings of this study showed that the ssp. vulgare had higher tolerance to the salinity stress than ssp. gracile due to the less accumulation of Na and Cl ions, higher K/Na ratio, and lower reduction in chlorophyll index and dry matter yield.

This paper studies the mechanical behavior of a polymeric degradable vessel subjected to internal pulsatile pressure, external pressure, and axial elongation. Two deformation-induced evolution laws are selected to investigate time-position-dependent material properties of the polymeric vessel. The vessel is subjected to the neo-Hookean constitutive model and an axisymmetric condition. To simulate finite deformation in the degradable vessel, FlexPDE commercial software is invoked in which the governing equations are solved by Standard Galerkin Finite Element Method (SGFEM). Results show that stresses pulsationally increase during degradation. Deformation response of the degradable vessel against time reveals the creep-like behavior of degradable polymers. Degradation rate begins from an initial peak value and decreases over time. The impact of degradation on invariants of the deformation tensor versus time and the vessel radius is discussed. Degradation evolution is higher in the outer radius of the vessel because of higher deformation in this region.

Qualitative and quantitative variations in the essential oil of wild growing Origanum vulgare L. ssp. gracile plants were studied in response to different phenological stages (pre, full and post-flowering). The essential oil of air-dried leaves was isolated by water distillation using a Clevenger-type apparatus and was analyzed by Gas Chromatography (GC) and Gas Chromatography–Mass Spectrometry (GC/MS). The highest (1.87%) and the lowest (1.01%) essential oil content were obtained from post-flowering and pre-flowering stages, respectively. In total, 24 components were identified and quantified in three phenological stages representing 96.75, 97.63, and 98.59% of the oil, respectively. Carvacrol (46.62, 46.5 and 27.6%), ρ-cymene (7.76, 13.54 and 37.08%) and γ-terpinene (21.54, 13.91 and 6.82%) were the main constituents of essential oils in pre, full, and post-flowering stages, respectively. Oxygenated monoterpenes (43.35-61.32%) and monoterpene hydrocarbons (30.81-48.02%) were the main classes of identified compounds in three essential oils. According to the findings of this research, the post-flowering stage can be considered as the most appropriate time for obtaining the highest essential oil content, but to achieve the highest rate of phenolic compounds, the pre-flowering and full-flowering stages can be recommended.

Many studies have been conducted on the role of essential elements in various aspects of medicinal plant production. However, the role of silicon (Si) as a quasi-essential or beneficial element in the growth and development, quantity and quality of essential oil of many medicinal plants is unknown. In this regard, different concentrations of silicic acid including 0 (control), 25, 50, 75, 100, and 125 mg l-1 were added to the standard Hoagland and Arnone nutrient solution, and morphophysiological reactions and secondary metabolites production of lemon balm (Melissa officinalis L.) were evaluated in soilless cultivation (hydroponic system). The fresh and dry weight of leaves and roots increased with the addition of Si to the nutrient solution compared to the control. The percentage of biomass changes varied depending on the concentration of Si, so that the plant fresh weight at 125 mg l-1 of Si increased by 41% compared to the control (without Si). However, the percentage of essential oil (fresh materials) in plants fed with Si increased significantly compared to control. Accordingly, the percentage of essential oil in different Si concentrations including 0, 25, 50, 75, 100 and 125 mg l-1 were 0.16, 0.21, 0.31, 0.33, 0.34 and 0.34(%), respectively. The reaction of lemon balm essential oil compounds to Si also indicated the important role of this element in the quality of the essential oil produced. The highest amounts of geraniol (21.27%) and citral (58.71%) were obtained in concentrations of 50 and 125 mg l-1 of Si, respectively. Also, the most important main compounds in various concentrations of Si (mg l-1) included citral+geraniol (Conc.0), citral+neryl (Conc.25), citral+linalool (Conc.50), citral+caryophyllene oxide (Conc.75), citral+geranyl acetate (Conc.100) and citral+geranyl (Conc.125). Based on the results of the experiment, Si as a beneficial element has a significant effect on the growth and development parameters, yield, and quality of essential oil of lemon balm.

Mullein (Verbascum L.) is a biennial herbaceous medicinal plant belonging to the Scrophulariaceae family. The flowers of this plant are used to treat respiratory disorders. In this study, the genetic diversity of different mullein species from different regions of West Azerbaijan province was investigated based on some phytochemical markers to domesticate this valuable plant. Phytochemical diversity among different species of mullein was evaluated based on the content of carotenoid, beta-carotene, total phenol, total flavonoid, and antioxidant activity (by FRAP and DPPH methods), and identification of phenolic compounds (gallic acid, caffeic acid, chlorogenic acid, rutin, coumaric acid, quercetin, cinnamic acid, and apigenin) by HPLC in leaf. The results showed that all phytochemical characteristics studied were significantly different among species (P<0.01). The highest content of carotenoid (76.27 mg g-1 DW), beta-carotene (5.88 mg 100g-1 DW), total phenol (32.83 mg GAE g-1 DW), total flavonoid (7.13 mg QE g-1 DW) and antioxidant activity by DPPH method (34.66 µg AA mL-1) was observed in V. sinuatum. The results showed that V. erianthum leaves had the highest content of chlorogenic acid, quercetin, cinnamic acid, and apigenin, while the highest content of gallic acid and caffeic acid was observed in V. saccatum. In general, the findings of this research showed that there was a wide variation of mullein species in West Azerbaijan province. Species V. erianthum and V. saccatum had unique phytochemical properties that can be used to design breeding programs and use them in the pharmaceutical industry.

In this article, the anti-plane deformation of an orthotropic sector with multiple defects is studied analytically. The solution of a Volterra-type screw dislocation problem in a sector is first obtained by means of a finite Fourier cosine transform. The closed form solution is then derived for displacement and stress fields over the sector domain. Next, the distributed dislocation method is employed to obtain integral equations of the sector with cracks and cavities under anti-plane traction. These equations are of Cauchy singular kind, which are solved numerically by generalizing a numerical method available in the literature by means of expanding the continuous integrands of integral equations with different weight functions in terms of Chebyshoff and Jacobi polynomials. A set of examples are presented to demonstrate the applicability of the proposed solution procedure. The geometric and force singularities of stress fields in the sector are also studied and compared to the earlier reports in the literature.

Demand for healthy and high-quality fruits has increased in the markets, and compositions such as vitamins, sugars, and anti-oxidant properties of fruits have attracted many consumers. Grapes contain phenols, flavonoids, anthocyanins, tannins and vitamins with high antioxidant properties. Antioxidants support biological systems such as proteins, amino acids, lipids, and DNA against oxidative damage produced by active oxygen species of ROS, resulting in reduction of cell damage and death, cardiovascular disease and cancers in the human body. Selenium is essential for humans and animals and should be fed through a diet, for this reason, FAO recommends entering selenium to agricultural products (especially fruits and vegetables). In recent years, selenium has been recognized as a useful element for plants that have been toxic at high concentrations but at desirable concentrations, it has positive antioxidant effects, increases growth and significantly affects seed germination. Selenium protects plants from several abiotic stresses such as heavy metal and arsenic, ultraviolet radiation, and biotic stress such as pathogens and pests. Selenium neutralizes oxidative stress interfering with lipid peroxidation, and accelerates gluthatione peroxidase (GSH-Px) activity, this phenomenon delay plant senescence and diminish postharvest losses. This element increases the yield and improves the quality of the fruits and vegetables. When Camelia oleifera plants were treated with selenium, cellular content of linoleic acid and sterol were elevated but oleic acid content diminished. Selenium treatment had a significant effect on preserving the sensory and the postharvest quality by decreasing respiration rate and ethylene biosynthesis in broccoli by diminishing phenylalanine ammonia-lyase (PAL) activity and ethylene production in lettuce and chicory. Foliar application of peach and pear trees with selenium, decelerated fruit softening rate and elongated shelf-life. Therefore, treatment of agricultural products with the appropriate amount of selenium can have a positive effect on the increase of the quality and enrichment of selenium in fruits and also play an important role in human health.

In order to investigate the effect of selenium as foliar application (0, 1, 2 and 3 mg L-1) on quality traits, antioxidant compounds and enrichment of grape cv. Fakhri, an experiment based on randomized complete block design with three replications in a vineyard (Kurdistan Povince, Ghorveh town) was performed. The 15-year-old vines were sprayed with selenium solution plus 0.1% of Twin 20 as surfactant until the leaves were completely wet (for each vine about 0.5 liter) at three stages of berry growth and development: Berry formation, Lag phase and veraison. A 1000 mg L -1 stock solutions (Made by the Belgian company CHEM-Lab, containing selenium ion Se+6) was used to prepare the desired solutions. At commercial fruit maturity stage (20° Brix), samples of fruits and leaves randomly were collected from treated and control vines and were immediately transferred to the postharvest physiology laboratory. Traits such as total chlorophyll, carotenoid, nitrogen, potassium, selenium  content of leaves and fruits, and also, total soluble solids, soluble sugars, titrable acidity, acidity (pH), vitamin C, phenol and flavonoids, antioxidant capacity in fruits and the berry weight were evaluated. Data were analyzed using SAS statistical software (SAS V.9.4), and means were compared by Duncan’s multiple range tests at the 5% of probability level.

Results showed positive effects of selenium treatment on evaluated traits. As a result, 2 mg L-1 of selenium increased photosynthetic pigments, nitrogen and leaf potassium, soluble solids, soluble sugars, vitamin C, total phenol, antioxidant capacity of fruits in comparison with untreated vines. The highest amount of titrable acidity, total fruit flavonoid and leaf selenium was recorded in vines treated with 3 mg L-1 selenium, whereas, this treatment had less effect on other traits. The highest amount of berry weight was obtained in 1 mg L-1 of selenium. However, none of the selenium treatments had significant effect on the juice acidity (pH). In general, the results showed a positive effect of selenium on improvement of antioxidant properties, quality and enrichment of grape, and 2 mg L-1 selenium with the highest effect on traits was identified as the best treatment. According to other researchers, foliar application of selenium in "Starking Delicious" apple cultivar was effective in enhancement of fruit selenium content and nutritional properties, postponing the flesh firmness decrease, and delaying fruit ripening resulting from less ethylene production, therefore significantly affecting apple fruit quality and storage life.

Ectodermal dysplasia (ED) is a hereditary disease that affects ectodermal tissues. Its oral manifestations include hypodontia or oligodontia, which cause the reduction of the height and width of the alveolar ridge. Considering numerous difficulties that these patients encounter with regard to facial appearance, talking, and chewing, their rehabilitation has a major influence on their quality of life. Implantation therapy is considered as a successful therapeutic protocol for substitution of such teeth. This article is a review of implant rehabilitation of ED patients and the related management procedures. In the present review article, the English articles in PubMed, ScienceDirect, MEDLINE, and Google Scholar databases from January 2000 to December 2017 have been investigated using the following keywords: anodontia, dental implants, ectodermal dysplasia, and hypodontia. There is a multilateral approach to the treatment of ED patients according to their age, the status of oral soft and hard tissues and the remaining teeth. Implantation therapy for such patients is similar to that of non-ED patients.

Previous studies have shown that cement production leads to the loss of natural resources such as limestone and fossil fuels and to the environmental pollution by greenhouse gas emissions, such as carbon dioxide. Therefore, durability of concrete structures is of particular importance. Using additives and also replacing conventional materials applied in concrete with new materials, has always been of great consideration. Nanomaterials are one of the new series of materials which have improved the mechanical and durability properties of concrete. In the present research, in order to evaluate the effect of freeze-thaw durability of concrete containing different percentages of nanocarbon cement structures on its flexural strength, weight loss test and three-point bending strength test were conducted. These nanostructures have been grown on Portland cement type II by chemical vapor deposition method. The results indicated that samples with 10% nanocarbon cement structures have led to the best performance of concrete pavement exposed to freeze-thaw cycles. Using of nanocarbon cement structures reduced weight loss and loss of flexural strength in the concrete pavements, and thereby improved the durability of concrete pavements exposed to freeze-thaw cycles.

A pot experiment in randomized complete block design was conducted to investigate theinfluence of zinc application methods (soil and foliar application) and concentrations (1 and 2 mg kg-1 in soil application and 1 and 3 g l-1 in foliar application methods) on the growth parameters, essential oil contents, yield and composition in costmary (Tanacetum balsamita L.). The aerial part of plants was harvested at flowering stage and air dried under shade condition. The essential oil of air dried organs was extracted by hydrodistillation method using a Clevenger type apparatus and analyzed by GC and GC/MS. The results showed that the effect of zinc application on growth parameters wassignificant. Zinc application caused an increase in fresh and dry weight of aerial parts and leaf area and the highest increase was observed with soil application of 2 mg kg-1. The effect of zinc application on essential oil content was not significant but increased essential oil yield significantly. The highest increase in essential oil content and yield was belonged to 2 mg kg-1 of soil application. The results of essential oil analysis showed that 20 components were identified in the costmary essential oil. Carvone and α-thujone were main components of essential oil and they showed little variation under zinc application.

In order to study the effect of arbuscular mycorrhizal fungi (AMF) under drought stress on some physiological characteristics (leaf temperature, chlorophyll index, compatible solute accumulation) of basil (Osmium basilicum L.), a pot experiment was conducted as a factorial trial based on randomized complete block design with four replications. Treatments included application of two mycorrhizal fungi (Glomus mosseae and Glomus intraradices) plus a control check (non-application) and three irrigation regimes (4, 8 and 12 days intervals). Results showed that drought stress had a significant effect on all evaluated parameters, so that reducing soil water content decreased chlorophyll index while increased accumulation of proline and total soluble sugars in leaves as well as leaf temperature. Moreover mycorrhiza colonization had significant effects on all evaluated parameters except proline. The highest and the lowest amount of leaf chlorophyll index and total soluble sugars in leaves were observed in inoculated plants with G. mosseae and control (non-application of mycorrhizal) treatments, respectively.

Roller compacted concrete is distinct from ordinary concrete by virtue of its zero slump. Over the past several years, the increasing usage of RCC for pavement construction has been noted. The use of RCC for pavements is relatively a new technology and is still under development. However, early trials have proven the success of the use of RCCP, which encouraged engineers to apply it in various fields.Although roller compacted concrete pavement (RCCP) has enjoyed numerous applications of roads and large floors in Europe, Canada and United States since 1970s, it has not been used in Iran appropriately.According to ACI 325.10R, RCCP is defined as a relatively stiff mixture of aggregates, cementitious materials, and water, which is compacted by vibratory rollers and the use of aggregate fractions finer than the 75 micrometers (NO. 200) sieve, if non plastic, may be beneficial. Very fine aggregates (smaller than 75 µm) play an influential role in conventional concrete, but its effect on in both the fresh and hardened states of RCC was not investigated. Generally the presence of very fine particles limited in PCC for four main reasons:1. Reducing workability due to large surface area2. Preventing proper bond between cement paste and aggregates3. Absorbing water and reducing strength 4. Increasing cracking resistanceAccordingly, most standards limit the very fines content to only a few percent. ASTM C33 limits the fines content in fine aggregate to 5%. The European standard for aggregates (EN 12620) permits four levels of fines content in fine aggregate (3, 10, 16 and 22%). In addition, specific limits can be established at different location according to different conditions.In the case of sand manufacturing, it is difficult to produce sand with very low fines content and to do so it requires modern washing system and a huge amount of water that is invaluable in hot and dry climates. Also as a result the amount of waste fines that accumulated annually for instance in the U.S alone is in excess of 100 million tons that have considerable environmental impact. In order to extend the usage of RCCP, a comprehensive laboratory investigation was carried out to evaluate the workability and mechanical properties of RCCP containing high-volume and low-volume non-plastic aggregates fractions finer than the 75 µ. After determining the optimum percent of non-plastic natural filler, concrete mixtures were made with 2.5%, 7.5%, 10% and 15% non-plastic aggregates finer than sieve #200, in order to check the possibility of using unwashed aggregates and the effects of these very fine materials on mechanical properties of RCCP. Also the variables such as cement content and superplasticizer have been evaluated and discussed. Various plots and tables showing the interrelations between the studied variables were included in the paper.Results indicated that it is feasible to use unwashed aggregates in RCCP mixes but a few limitations should be carefully considered. Also natural filler caused to improve the mechanical properties of RCC. In addition one of the major findings was that the main factor that controlled most of hardened properties is achieving sufficient compaction and unlike conventional concrete increasing cement content may not result in strength increase. Based on the results, the optimum aggregates proportion and W/C ratio have been found in order to make RCC for pavement applications that meet all specified limits in the ACI 325.10 state-of-the-art report and ACI 211.3R-97. Finally the optimum percentage of super plasticizer was determined.

One of the effective factors in road safety and accident reduction is to combat road surface slipperiness. The greater the coefficient of friction at the contact patch, the greater will be the degree of vehicle control in bringing it to a halt, thus helping reduce accidents.Asphalt pavements are used extensively throughout the world in general, and in Iran in particular. Thus, in this research hot asphalt mixes (3 types) have been studied for their relative performance in skid resistance. In this research, British Skid Resistance Tester (commonly known as the Pendulum) has been used to evaluate the skid resistance of laboratory made samples and the macrotexture of these surfaces have been measured using the sand-patch technique.In this research, by keeping the aggregate type the same, three types of asphalt mixes that is; pervious macadam, stone mastic asphalt and asphalt concrete are made and evaluated that are different in respect of macrotexture, nominal size, aggregate grading and the percentage of large to small aggregate fractions. Samples made measure 30 x 30 cm with a thickness of 5 cm which are the same as a complete wearing course layer in the field. As asphalt pavements are extensively used in Iran and in the world in addition to mechanical specifications of the asphalt mix the skidding resistance should also be considered. The results show that:1.Among the porous asphalt, SMA asphalt, and the asphalt with continuous grading (concrete asphalt), the porous asphalt is advantageous from the skidding resistance point of view.2.The nominal size of the mix affects the skid resistance of the size, and in the range of 4.75 to 19 mm. nominal size that were studied in this research. The less the nominal size of the mix, the more will be its skid resistance.3.Investigations show that the content of aggregates passed through sieve No. 4.75mm. affects the skid resistance of the nominal size measured by the English pendulum and the skid resistance of the aggregates has a reversed relationship with the aggregates passed thought the same sieve.4.In the asphalt with continuous concrete asphalt grading, the reduced skid resistance between nominal size of 4.75 and 9.5 mm. is not considerable, however it is influential on other parameters like Marshall Stability