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...

the aim of this paper is eliminating cr(vi) by natural hap. hap is a inexpensive material which is used from bovine critical bone ash in order to remove heavy metal ions like cr(vi). some experiments in different ph are performed (ph=2,3,7). maximum adsorption was appeared at ph=2, dosage=0.3 gr, c0=10 mg/l. cr(vi) removal depends on ph value and initial amount of cr(vi) result of experiments w...

abstract in this thesis at first we comput the determinant of hankel matrix with enteries a_k (x)=?_(m=0)^k??((2k+2-m)¦(k-m)) x^m ? by using a new operator, ? and by writing and solving differential equation of order two at points x=2 and x=-2 . also we show that this determinant under k-binomial transformation is invariant.

this study was intended to analyze the listening tapescripts of the elementary and pre-intermediate levels of total english textbooks from the pragmatic dimension of language functions and speech acts in order to see whether the listening tasks are pragmatically informative or not. for this purpose, 8 conversations from the two books were selected randomly, and then, the two pragmatic models of...

in this thesis, barium ferrite nano particles were prepared by sol-gel method. their structural and magnetic properties of samples have been investigated using thermo gravimetric analysis (tg-dta), x-ray powder diffractometer (xrd), fourier transform infrared (ftir), scanning electron microscopy (sem), field emission scanning electron microscopy (fesem), ac susceptometer, vibrating sample magne...

abstract this study aimed at investigating the impact of etymology strategy instruction on the development of vocabulary of iranian intermediate efl learners. etymology, knowledge of origin of words, roots, and affixes, has proved to be a controversial issue and a question of long debate with regard to its impact on the process of vocabulary learning. this study employed etymology strategy in ...

this thesis examines the significances and implications of inflicted physical pain in waiting for the barbarians (1980) by john maxwell coetzee (1940 - ). the researcher tries to show how body becomes a site for exercising violence. in this way, the government’s representatives turn bodies of the barbarians into blank pages through torturing in order to create the truth of the empire. in this p...

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...

cement is an essential ingredient in the concrete buildings. for production of cement considerable amount of fossil fuel and electrical energy is consumed. on the other hand for generating one tone of portland cement, nearly one ton of carbon dioxide is released. it shows that 7 percent of the total released carbon dioxide in the world relates to the cement industry. considering ecological issu...

until now many studies have been done over recent decades throughout the world to show the right age to start english. in iran, research is still at an early stage in terms of evaluating teachers’ beliefs about teaching children english. the problem of at what age to start teaching english and how to teach english to elementary school children has not been solved neither in this country nor els...