In this article, we have proposed memory-type exponential and non-exponential estimators for population variance based on exponentially weighted moving average (EWMA) statistic in stratified sampling. We drive mathematical expressions for mean square errors of the proposed estimators using Taylor and exponential expansions. Our analysis demonstrates that the proposed memory-type estimators outperform the conventional estimators under stratification, particularly, when the information of previous sample is utilized.
View Article and Find Full Text PDFWith the ever-increasing scope of organocuprates, a well-established Gilman reagent has been considered as an unprecedented synthetic tool in modern organic chemistry. The broad research profile of the Gilman reagent (RCuLi in THF or EtO) is owing to its propensity to carry out three kinds of reactions, , epoxide ring opening reactions, 1,4-conjugate addition reactions, and S2 reactions in a regioselective manner. This review examines the applications of Gilman reagent in the total synthesis of both abundant and scarce natural products of remarkable synthetic pharmaceutical profile reported since 2011.
View Article and Find Full Text PDFThe present study suggested memory-type ratio and product estimators for variance estimation in the presence of measurement errors. We applied the exponentially weighted moving averages statistic which simultaneously utilizes the current and prior information for better estimation in surveys based on the time-scale. The expressions of approximate mean square errors of memory-type estimators are derived using Taylor series up to first order.
View Article and Find Full Text PDFImprovements of visible light activity, slow recombination rate, stability, and efficiency are major challenges facing photocatalyst technologies today. Utilizing heterostructures of g-CN (bandgap ∼2.7eV) with NbO (bandgap ∼3.
View Article and Find Full Text PDFIt is estimated that viral infections contribute 15-20% of all human cancers. Several types of human papillomaviruse (HPV) are related to the development of many cancer types and their treatment. About 200 HPV viruses have been identified, and each type of virus is integrated with a certain type of clinical lesions affecting the areas of skin and mucous membranes.
View Article and Find Full Text PDFIn this study, novel hydrothermal ex situ synthesis was adopted to synthesize MoS/WO heterostructures using two different molar ratios of 1:1 and 1:4. The "bottom-up" assembly was successfully developed to synthesize spherical and flaky-shaped heterostructures. Their structural, morphological, compositional, and bandgap characterizations were investigated through XRD, EDX, SEM, UV-Visible spectroscopy, and FTIR analysis.
View Article and Find Full Text PDF