The biomechanical mechanisms underlying sex-specific differences in age-related vertebral fracture rates are ill defined. To gain insight into this issue, we used finite element analysis of clinical computed tomography (CT) scans of the vertebral bodies of L3 and T10 of young and old men and women to assess age- and sex-related differences in the strength of the whole vertebra, the trabecular c...

Aquaculture is among the oldest occupations of human being. Over the past quarter of century, the aquaculture industry has grown rapidly. The effect of water containing sodium sulfate on long term compressive strength of concrete of fishing ponds and channels is investigated in this paper. Aim of this paper was to analyze the strength of concrete channels and of aquaculture which are in direct ...

an oil and gas well cementing in gachsaran formation, where sustained annular pressure has been reported in many wells, presents a big challenge in maroon field. the main challenges are preventing gas migration and achieving zonal isolation using a competent cement sealant system which is able to withstand downhole stresses and high temperatures during production cycles. unlike conventional cem...

this article addresses the interplay between heat of hydration and physico-mechanical properties of calcium sulfate hemi-hydrate in the presence of retarding additives such as citric and malic acids and sodium citrate. the heat of hydration was measured using a semi-isothermal calorimeter. results proved that citric and malic acids had superior impact on hydration and mechanical properties. whi...

this study aimed to investigate the effects of tow nanoparticles (nps) on the absorption,accumulation, reproduction of the eisenia fetida. a 4×2×2 factorial experiment in a randomized completeblock design with three replications was conducted. the factors included in the experiment are the content ofnps at four levels (0, 0.4, 0.8, and 1.2gr/kg weight of substrate), the type of nps at two level...

:the aim of this work is to investigate the influence of sodium oxide on properties of fresh and hardened paste of alkali-activated blast furnace slag from isfahan steel plant. the silica modulus (sio2/na2o) of activator was adjusted at 0.6 and a number of mixes were designed in such a way to contain different levels of sodium oxide including 1, 2, 3, 4, 5, and 6% by weight of dry slag. the mos...

according to the iranian code of practice for seismic resistant design of buildings, soft storey phenomenon happens in a storey when the lateral stiffness of the storey is lower than 70% of the stiffness of the upper storey, or if it is lower than 80% of the average stiffness of the three upper stories. in the combined structural systems containing moment frames and shear walls, it is possible ...

the design of cement slurry for horizontal wellbores is challenging as it must present very high quality cement slurry properties e.g. zero free water, less than 50 cc api fluid loss value, appropriate rheology and yield point for effective displacement, adequate compressive strength, which is critical for lightweight slurries, and finally stable cement column behind casing. the main objective ...

abstract due to the importance of using clay soil in many constructive projects such as, road foundation, irrigation canals and related hydraulic structures and etc., improvement of the physical and mechanical soil properties has been the main interest of the geo-technique specialists for years. in this regard different methods such as mixing clay soil with lime or cement have been used. it has...