abstract in aggregate, active forms of reactive silica with mineral names are sometimes associated with sand and gravel in concrete mixture. alkali hydroxides originated from alkalis in the cement or other resources form an alkaline silica gel with this reactive silica which becomes swallowed and expanded during time causing damage to concrete. there have been growing researches on alkaline r...

abstract: the potato tuberworm, phthorimaea operculella (zeller), is an important insect pest of potato (solanum tuberosum l.) in the storage and field in most parts of the world especially in tropical and subtropical regions due to its close relationship with the host, high reproductive potential and high economic losses. information on host preference, life table parameters and digestive en...

this study aimed at examining the effects of iranian efl learners’ anxiety, ambiguity tolerance, and gender on their preferences for corrective feedback (cf, henceforth). the effects were sought with regard to the necessity, frequency, and timing of cf, types of errors that need to be treated, types of cf, and choice of correctors. seventy-five iranian efl students, twenty-eight males and forty...

nowadays,tourism industry considered as one of the main sources of income of a country.unfortunately and despite of owning plenty of cultural historical and natural attractions, iran has not reached to a proper position in this field. besides, the historical cities of a country are considered as the income resource and national wealth of it. qazvin with a rich cultural precedent, have suitable ...

sange siyah dam is located two kilometers down the kabod khani village. the environ of ghorrve city in kurdestan province. this is an clay core dam. in this dam instrumentation is performed in three section and consist of electrical piezometers, total pressure cells, settlement cells and so on. the main objective of instrumentation is to control the behavior of dam body and foundation, end else...

the importance of writing as a complex skill in applied linguistics has drawn the attention of many researchers to evaluate textbooks in order to help learners gain self-sufficiency and autonomy in the field of language use and communication. investigations have shown that developments in textbooks evaluation can promote the quality of pedagogies and consequently the learning. this study attemp...

in this project, some new polyaspartimides, (pas)s, have been synthesized form michael addition reaction between new synthetic bismaleimide (bmi) and some aromatic diamines. a characteristic property of this polyaspartimides is a pendent carboxylic group, which introduced to these polymers from new bismaleimide. bismaleimides (bmi) is one of the interesting compounds, which can be self-polymeri...

growing demands and requires of high data rate systems cause significant increase of high frequency systems for wideband communication applications. as mixers are one of the main blocks of each receivers and its performance has great impact on receiver’s performance; in this thesis, a new solution for ku-band (12-18 ghz) mixer design in tsmc 0.18 µm is presented. this mixer has high linearity a...

introruction khawf in(iran)-herat and mazaresharif and shirkhan bandar in (afghanistan)-dushanbe in (tajikistan)_(kirgizstan)-kashghar in(china) project railway network is under construction that it is as a significant corridor for revitalizing silk road corridor in the region .at the present there are three different gauge in the region central asia with 1,520 mm gauge and turkey-islamic repu...

in this thesis, a better reaction conditions for the synthesis of spirobarbiturates catalyzed by task-specific ionic liquid (2-hydroxy-n-(2-hydroxyethyl)-n,n-dimethylethanaminium formate), calcium hypochlorite ca(ocl)2 or n-bromosuccinimide (nbs) in the presence of water at room temperature by ultrasonic technique is provided. the design and synthesis of spirocycles is a challenging task becaus...