fluorescence chemical sensors for the highly sensitive and selective determination of pb2+ , hg2+, co2+ and fe3+ ions in aqueous solutions are described. the ion sensing system was prepared by incorporating lipophilic ligand (l) as a neutral ion-selective fluoroionophore in the plasticized pvc membrane containing sodium tetraphenylborate or potasium tetrakis (p-chlorophenyl) borate as a liphoph...

abstract: the present study was undertaken to investigate whether 1) there is any significant correlation between iranian efl/eap learners’ l2 writing proficiency and their willingness to communicate, 2) there is any significant difference between efl and eap learners in terms of willingness to communicate, 3) there is any significant difference in wtc of iranian efl/eap learners with 1- nati...

abstract amino acids are building blocks of proteins, and play a vital role in living beings existence and their functionality. the interaction of these compounds with metal ions is of great importance to biochemists, and chemists, because their functions can be utilized as a model in understanding enzymes mechanism for transport of metal ions to tissues. among twenty essential amino acids w...

introduction acetic acid bacteria are large group of obligate aerobic gram negative bacteria with the ability to oxidize ethanol to acetic acid (1). they are widely distributed in natural habitats and classified in family acetobacteraceae. members of this family are useful in industrial production of vinegar(2). acetic acid bacteria (aab) can use substrates as glucose, ethanol, lactate or glyc...

according to coates’s (2004, as cited in zhang, 2010) definition of "conversational dominance" (p.111), it refers to the phenomenon of a speaker dominating others in interaction. specifically, it means how a speaker makes use of certain strategies to get the floor and maintain the floor. thus, the amount of talk is the main measurement for the dominance of the conversation. whether a speaker do...

assigning premium to the insurance contract in iran mostly has based on some old rules have been authorized by government, in such a situation predicting premium by analyzing database and it’s characteristics will be definitely such a big mistake. therefore the most beneficial information one can gathered from these data is the amount of loss happens during one contract to predicting insurance ...

the central purpose of this study was to conduct a case study about the role of self monitoring in teacher’s use of motivational strategies. furthermore it focused on how these strategies affected students’ motivational behavior. although many studies have been done to investigate teachers’ motivational strategies use (cheng & d?rnyei, 2007; d?rnyei & csizer, 1998; green, 2001, guilloteaux & d?...

some new water-soluble schiff base complexes of na2[m(5-so3-1,2-salophen)].nh2o; (5-so3-1,2-salophen = n,n’-bis(5-sulphosalicyliden)-1,2-phenylendiamine); na2[m(5-so3-2,3-salpyr)(h2o)n].2h2o; (5-so3-2,3-salpyr = n,n’-bis(5-sulphosalicyliden)-2,3-diaminopyridine); and na2[m(5-so3-3,4-salbenz)(h2o)n].nh2o; (5-so3-3,4-salbenz = n,n’-bis(5-sulphosalicyliden)-3,4-diaminobenzophenon); where m = cu, n...

the main objective in sampling is to select a sample from a population in order to estimate some unknown population parameter, usually a total or a mean of some interesting variable. a simple way to take a sample of size n is to let all the possible samples have the same probability of being selected. this is called simple random sampling and then all units have the same probability of being ch...

the ability to speak two languages in the world is a remarkable achievement. there is a good reason to believe that bilingualism is the norm for the majority of people in the world because 70% of the earth’s population are supposed to be bilingual or multilingual. various investigations have shown that the native language impacts foreign word recognition, and this influence is adapted by the de...