نتایج جستجو برای: 99 standard method with hexane and acetone solvents
تعداد نتایج: 18593444 فیلتر نتایج به سال:
The objective of this research was to investigate the influence four solvents on hydrotreatment hydrothermal liquefaction (HTL) biocrude derived from municipal sewage sludge. HTL sludge performed at 350 °C in a 1.8 L batch reactor. then extracted reaction mixture using dichloromethane (DCM), hexane, toluene, and acetone as solvents. Solvent extraction DCM, resulted 38%, 12%, 18%, 10% yields (dr...
Terpenoids, naturally occurring compounds derived from isoprene units present in pine oleoresin, are a valuable source of chemicals used in solvents, fragrances, flavors, and have shown potential use as a biofuel. This paper describes a method to extract and analyze the terpenoids present in loblolly pine saplings and pine lighter wood. Various extraction solvents were tested over different tim...
the methods which are used to analyze microstrip antennas, are divited into three categories: empirical methods, semi-empirical methods and full-wave analysis. empirical and semi-empirical methods are generally based on some fundamental simplifying assumptions about quality of surface current distribution and substrate thickness. thses simplificatioms cause low accuracy in field evaluation. ful...
abstract present research considered to examine and compare shahrray 14 years girls and boys narrative concerning with their responsibilities in this research, statistical society are 14 years girls and boys of shahrry . for performing this research. first, 14 years of 50 boys and 50 girls were selected in accidental method and have filled memati hormaled adolescents responsibility questioner...
The South Pacific islanders have consumed kava beverage for thousands of years. The quality of kava and kava beverage is evaluated through determination of the content of six major kavalactones including methysticin, dihydromethysticin, kavain, dihydrokavain, yangonin and desmethoxyyangonin. In this study, we determined contents of kavalactones in and chemotype of kava beverages prepared from r...
abstract part one: the electrode oxidation potentials of a series of eighteen n-hydroxy compounds in aqueous solution were calculated based on a proper thermodynamic cycle. the dft method at the level of b3lyp-6-31g(d,p) was used to calculate the gas-phase free energy differences ,and the polarizable continuum model (pcm) was applied to describe the solvent and its interaction with n-hydroxy ...
In this method for determining fecal lipids, feces are saponified with ethanolic potassium hydroxide, the ethanol is evaporated, and the acidified residue extracted with hexane. An aliquot of the hexane solution is then titrated with ethanolic sodium hydroxide, the solvents are evaporated, and the residue (soaps and unsaponifiable matter) is weighed. The unsaponifiable matter is extracted with ...
a solid-phase extraction (spe) method for sample clean-up and preconcentration followed by reversed-phase high-performance liquid chromatography (rp-hplc) with uv detection is reported for determination of polycyclic aromatic hydrocarbons (pahs) in the caspian seawater. a good resolution was obtained using acetonitrile:water (40:60) as mobile-phase for separation of these compounds. the effect ...
the following question poped up: is there any relationship between iranian high school efl learners reading comprehension and listening comprehension? then the following null hypothesis (ho) was developed to the test the above, mentioned question. "there is no relationship between high school efl learners reading comprehension and listening comprehension. for nearly 16 weeks, the experimental g...
abstract objectives gradual increase length and complexity of utterance (gilcu) therapy method is a form of operant conditioning. this type of treatment is very precise and controlled that is done in 54 steps in 3 speech situations consisted of monologue, reading and conversation. this study aimed to examine the effects of gilcu treatment method on reduction of speech dysfluency of school-age...
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