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...

دسته ای از ترکیبات شیمیائی که مخصوصا با گسترش زندگانی جدید (ماشینی)اهمیت فرآینده ای پیدامی کنند، افزودنیهای مختلف غذائی میباشند که در صنایع مربوطه بکار گرفته می شوند بکارگیری بخشی از این موا تحت عنوان طعم دهنده ها بمنظور تامین طعم و مزه طبیعی درفرآورده های صنعتی تقریبا اجتناب ناپذیر گشته و همگام با توسعه تولیدات روبه توسعه می رود. یک شناخت سیستماتیک و جامع از خواص و آثار اینگونه مواد طبیعتا مست...

rivers and runoff have always been of interest to human beings. in order to make use of the proper water resources, human societies, industrial and agricultural centers, etc. have usually been established near rivers. as the time goes on, these societies developed, and therefore water resources were extracted more and more. consequently, conditions of water quality of the rivers experienced rap...

abstract the current study sets out 1) to investigate the strategic needs of iranian efl learners in reading literary and non-literary texts; 2) to shed some light on the differences between reading literary and non-literary texts; and 3) to specify the differences in the interaction of participants with texts while reading two literary subgenres ( i.e., short story and literary essays). to ...

the caspian sea contains great resources of oil and gas. the caspian sea is a 700- mile- long body of water in central asia, land located between azerbaijan, iran, kazakhstan, russia and turkmenistan. iran was challenges and opportunities in the caspian region. key question in this thesis includes three section that first question, opportunities of iran in the caspian region, second question ch...

nowadays in trade and economic issues, prediction is proposed as the most important branch of science. existence of effective variables, caused various sectors of the economic and business executives to prefer having mechanisms which can be used in their decisions. in recent years, several advances have led to various challenges in the science of forecasting. economical managers in various fi...

abstract the influence of cation?? and anion?? interactions on the strength and nature of n…h hydrogen bond has been investigated by quantum chemical calculations in s-triazine…3hf complex. ab initio calculations were performed at mp2/6-311++g(d,p) level of theory. the natural bond orbital (nbo) analysis and the bader’s quantum theory of atoms in molecules (aim) were also used to elucidate t...

a novel and ultra low cost isfet electrode and measurement system was designed for isfet application and detection of hydronium, hydrazinium and potassium ions. also, a measuring setup containing appropriate circuits, suitable analyzer (advantech board), de noise reduction elements, cooling system and pc was used for controlling the isfet electrode and various characteristic measurements. the t...

this study investigated how group formation method, namely student-selected vs. teacher-assigned, influences the results of the community model of teaching creative writing; i.e., group dynamics and group outcome (the quality of performance). the study adopted an experimental comparison group and microgenetic research design to observe the change process over a relatively short period of time. ...