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1 – 2 of 2Liqun Hu, Tonghui Wang, David Trafimow, S.T. Boris Choy, Xiangfei Chen, Cong Wang and Tingting Tong
The authors’ conclusions are based on mathematical derivations that are supported by computer simulations and three worked examples in applications of economics and finance…
Abstract
Purpose
The authors’ conclusions are based on mathematical derivations that are supported by computer simulations and three worked examples in applications of economics and finance. Finally, the authors provide a link to a computer program so that researchers can perform the analyses easily.
Design/methodology/approach
Based on a parameter estimation goal, the present work is concerned with determining the minimum sample size researchers should collect so their sample medians can be trusted as good estimates of corresponding population medians. The authors derive two solutions, using a normal approximation and an exact method.
Findings
The exact method provides more accurate answers than the normal approximation method. The authors show that the minimum sample size necessary for estimating the median using the exact method is substantially smaller than that using the normal approximation method. Therefore, researchers can use the exact method to enjoy a sample size savings.
Originality/value
In this paper, the a priori procedure is extended for estimating the population median under the skew normal settings. The mathematical derivation and with computer simulations of the exact method by using sample median to estimate the population median is new and a link to a free and user-friendly computer program is provided so researchers can make their own calculations.
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Keywords
Reetu Yadav, Mamta Kushwah, Anna Nikolaevna Berlina and Mulayam Singh Gaur
The purpose of this study is determination of cadmium using silver-gold bimetallic nanoparticles (Ag-Au BMNPs) and an aptamer modified glassy carbon electrode.
Abstract
Purpose
The purpose of this study is determination of cadmium using silver-gold bimetallic nanoparticles (Ag-Au BMNPs) and an aptamer modified glassy carbon electrode.
Design/methodology/approach
The maximum response of modified electrode was obtained with, 50 mV pulse amplitude, 20 mV/s scan rate in phosphate buffer of pH 4.0. Ag-Au BMNPs, as the mediators improved electron transmit during the entire electron transfer process and the aptasensor response. Herein, the authors used aptamer as the capture probe to prepare an aptasensor with enhanced stability.
Findings
The proposed aptasensor exhibited a wide linearity to cadmium in the range of 0.001–0.100 µg/L with a low detection limit of 0.005×10−3 µg/L. The glassy carbon electrodes with Ag-Au BMNPs showed a lower detection limit.
Originality/value
This aptasensor has good reproducibility, stability and repeatability and is cost-effective to regenerate. The specificity and selectivity of the novel modified electrode is tested in the presence of other interfering metal ions such as Fe2+, Mn2+, Mg2+, Sb3+ and Bi3+. The aptasensor shows 10 times more sensitivity and selectivity for Cd2+ ions.
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