we develop a two phase sampling procedure to determine the sample size necessary to estimatethe population mean of a normally distributed random variable and show that the resulting estimator has preassigned variance and is unbiased under a regular condition. we present a necessary and sufficient condition under which the final sample mean is an unbiased estimator for the population mean.

in order to study the cu(ii) ion selective electrode, an optimized membrane was prepared by mixing of 30 mg of pvc powdered, 5 mg of considered ionophore, 60 mg of plasticizer and 5 mg of additive. the sensor showed a near nernstian response for cu(ii) ions over a concentration range from 1.0×0-6 –1.0×0-2 m with a slope of 28.90.5 mv per concentration decade with a working ph range of 3.5-6.3. ...

a new, simple, rapid, and cheap method for determination of trace amounts of nitrite ion is reported.determination is based on reduction of bromate ion by nitrite ion, in the presence of murexide inacidic media. during reaction of bromate ion with nitrite ion, the reaction mixture is decolorized.the absorbance changes is then monitored spectrophotometricaly at 520 nm, at 25 °c. dynamicrange of ...

iron is quantitatively retained on an adsorbent made by coprecipitation of 1,2-dihydroxybenzene-3,5-disulfonic acid (tiron) and tetradecyldimethylbenzylammonium choride (tdba) an microcrystalline naphthalene as a slurry or packed in a column, in the ph range 6.0-9.0 from a large volumes of aqueous solutions (up to 200 ml on microcrystalline naphthalene and up to 500 ml of aqueous solutions in t...

introdouction: age estimation is an important issue in forensics, particularly for treatment planning and determining patients’ rights. radiographic evaluation of the third molar developmental stage is a significant criterion for age estimation. the pattern of tooth development is largely heritable and varies from race to race. the objective of this study was to radiographically examine and com...

rice bran sterols have antioxidant activity as well as physiological and biological effects. because of these benefits, the aim of this study is evaluating the quantity and quality of iranian rice bran sterols. three widespread iranian rice cultivars (khazar, hashemi, and alikazemi) were used for determination of their sterol contents. two methods of sample preparation were compared and the bet...

the electrochemical oxidation of sulfamethazine (smz) has been studied at a multi-walled carbon nanotubes modified glassy carbon electrode (mwcnt-gce) by cyclic voltammetry. this modified electrode (mwcnt-gce) exhibited excellent electrocatalytic behavior toward the oxidation of smz as evidenced by the enhancement of the oxidation peak current and the shift in the anodic potential to less posit...

determination of terazosin hydrochloride dihydrate (trz) in drug substance and tablets was studied by fluorimetric techniques. the fluorimetric methods are based on: (1) measurement of the native fluorescence of the drug in water at 750 nm after excitation at 330 nm. (2) sensitizing the native fluorescence by formation a binary complex of drug with aqueous uranyl acetate (0.1% w/v) at the same ...

The Paper presents a corpus based study of Löbner’s theory of determination types. According to Löbner, nouns prefer a syntactic determination mode that is congruent to their inherent type of lexical determination. The study applies machine learning methods to a large corpus of German texts for detecting the determination modes of nouns automatically and addresses the problem of inducing the le...