in this thesis, a new optically active poly(amide-imide) (pai) was synthesized by the indirect polycondensation reaction of the l-phenylalanine based diacid chloride and 4,4?-diaminodiphenylether in the presence of triethylamine in n-methyl-2-pyrrolidone. the formation of pai was confirmed by ftir, 1h nmr and elemental analysis. in next step, the surface of titanium dioxide (tio2) nanoparticles...

Introduction: light intensity and duration are physical factors that affect hormone secretion and circadian rhythms. This study aimed to determine the effects of various light intensities on serum melatonin and cortisol levels.  Materials and methods: This experimental study was carried out on 32 male rats: Group 1 as the control group, received a brightness of 150 lux, and groups 2, 3, and ...

Introduction: In modern societies, shift work is an essential component of daily life. Since the beginning of research in shift work, researchers have been engaged in the identification of factors predicting adjustment and adaptation to shift work. The concept of adaptation and tolerance refers mainly to the biological response in terms of circadian rhythms and performance efficiency as well as...

the present study was conducted to investigate the role of summary in teaching grammar process on pre-university students. to this end, 48 male pre-university students in semnan were participants. they were math class that we called experimental group and science class as control group. in order to make sure there was no significant difference in proficiency level of two groups. a pre-test wa...

esl/efl books play a crucial role in shaping language learners worldview of gender roles in society. the present study investigated the status of sexism in two sets of efl textbooks, one developed by non-native iranian authors (ili series) and the other by native authors (top notch series). first, two books from each series was selected randomly. then, a quantitative analysis was carried out wi...