Kinetics of iron redox reaction in silicate melts: A high temperature Xanes study on an alkali basalt

focus on communication in iranian high school language classes: a study of the role of teaching materials in changing the focus onto communication in language classes

چکیده ارتباط در کلاس به عوامل زیادی از جمله معلمان، دانش آموزان، برنامه های درسی و از همه مهم تر، مواد آموزشی وابسته است. در تدریس ارتباطی زبان که تاکید زیادی بر توانش ارتباطی دارد، کتاب درسی به عنوان عامل موثر بر پویایی کلاس محسوب میگردد که درس ها را از طریق فراهم آوردن متن ارتباط کلاسی و هم چنین نوع تمرین زبانی که دانش آموزان در طول فعالیت های کلاسی به آن مشغول اند، کنترل می کند. این حقیقت ک...

Structure and dynamics of magnesium in silicate melts: A high-temperature 25Mg NMR study

25Mg NMR spectra for several silicate and aluminosilicate melts were obtained from 1000–1470 8C. The peaks are initially very broad, but narrow with increasing temperature to near 500 Hz at the highest temperatures. The peak positions for most of the melts do not shift noticeably with temperature in the range studied, except for a sodium magnesium silicate composition that was previously studie...

Reaction Kinetics in Polymer Melts

We study the reaction kinetics of end-functionalized polymer chains dispersed in an unreactive polymer melt. Starting from an infinite hierarchy of coupled equations for many-chain correlation functions, a closed equation is derived for the 2nd order rate constant k after postulating simple physical bounds. Our results generalize previous 2-chain treatments (valid in dilute reactants limit) by ...

Studies on the Alkali–Silica Reaction Rim in a Simplified Calcium–Alkali–Silicate System

This work is intended to provide a better understanding about the properties and roles of the reaction rim in an alkali-silica reaction. A simplified calcium-alkali-silicate system was created to simulate the multiple interactions among reactive silica, alkaline solution and portlandite near the aggregate surface during the formation and evolution of the reaction rim in an alkali-silica reactio...

High-precision determination of iron oxidation state in silicate glasses using XANES