A. Esmailpour, M. Hassanzadehdelouei and A. Madani
Integrated nutrient management strategies involving chemical and biologic fertilizer is a real challenge to stop using the high rates of agrochemicals and to enhance sustainability of crop production. In order to study the effects of livestock manure, chemical nitrogen, and biologic (Azotobacter) fertilizers on yield and yield components of wheat, an agricultural experiment in the form of split factorial design with three replications was conducted in Elam region, Iran. The aim of this research was assessment of the effects of these fertilizers separately and in integrated forms; and setting out the best fertilizer mixture. The results showed that treatment with livestock manure, Azotobacter and chemical nitrogen increased plant height, biological and grain yield. Using livestock manure and Azotobacter increased biologic yield through increase in plant height which cause to increase in grain yield without any significant changes in harvest index and other yield components, but the use of chemical nitrogen caused an increase in plant height, No. of spikelete/spike, No. of grain/spike, one thousand grain weight and harvest index, biologic and grain yield. In the light of the results achieved, we may conclude that using livestock manure and chemical nitrogen fertilizer together with the Azotobacter had the maximum impact on yield; and that we can decrease use of chemical fertilizers through using livestock manure and biologic fertilizers and to reach to the same yield when we use only chemical fertilizers.
A buckling analysis of temperature-dependent embedded plates reinforced by single-walled carbon nanotubes (SWCNTs) subjected to a magnetic field is investigated. The SWCNTs are distributed as uniform (UD) and three types of functionally graded nanotubes (FG), in which the material properties of the nano-composite plate are estimated based on the mixture rule. The surrounding temperature-dependent elastic medium is simulated as Pasternak foundation. Based on the orthotropic Mindlin plate theory, the governing equations are derived using Hamilton's principle. The buckling load of the structure is calculated based on an exact solution by the Navier method. The influences of elastic medium, magnetic field, temperature and distribution type, and volume fractions of SWCNT are shown on the buckling of the plate. Results indicate that CNT distribution close to the top and bottom are more efficient than that distributed near the mid-plane for increasing the stiffness of the plates.
The use of various additives (admixtures) in concrete and cement products has been considered by various researchers in recent years. Microsilica (Silica fume) can also be considered as one of the most widely used additives (admixtures) in this section. In this study, 120 concrete specimens were constructed using a mix design based on ACI in the laboratory with an overview of records and advantages of using microsilica in concrete. The microsilica used in concrete specimens has been considered 2%, 5.5% and 7.5% by weight of cement. Finally impact permeability, tension and uniaxial compressive strength tests were done on concrete specimens and their mechanical properties were evaluated. The results show that microsilica improves the mechanical properties of concrete. The results also show that the use of microsilica in ordinary concrete has a very positive effect in controlling the surface cracks and increasing some strength parameters such as tensile and compressive strength of concrete.