Vol. 51 No. 1 (2019)

This paper proposes two new classes of ratio estimators for population mean when information on a known auxiliary variable is available in simple random sampling. A combined family of ratio estimators for estimating population mean by combining the two new estimators together in order to minimize the mean square error (MSE) is then suggested. The expressions for the bias and mean square error of all proposed estimators up to the first order of approximation were obtained. The performance of the proposed estimators was compared with that of existing estimators using both a theoretical and a…

In elimination theory, the matrix method of computing resultant remains the most popular due to its less computational complexity compared to Groebner basis and set characteristics approaches. However, for a matrix method to be effective, the size and the nature of elements of the matrix play an important role, since if the resultant is not an exact resultant, it has to be extracted from the determinant of the corresponding resultant matrix.. In this paper, a new resultant matrix is proposed. The proposed construction consists of four blocks, one of the blocks uses an entry formula of…

Anthocyanins extracted from purple-fleshed sweet potato were encapsulated using emulsification-crosslinking technique with chitosan acted as polymer and sodium tripolyphosphate as cross-linker. The parameters influencing microencapsulation were investigated i.e. stirring intensity and polymer concentration, pH of polymer and crosslinker solution, and also ratio of anthocyanins extract (core) to polymer concentration by characterizing the properties of obtained microcapsules. Stirring intensity of 1600 rpm achieved microcapsules with smaller mean diameter, narrower particle size distribution,…

Indonesian black rice cv Cempo Ireng was evaluated for cancer prevention using a T47D cell line model. Methanolic extract of black rice bran (BRB) showed cytotoxicity with an IC50 of 522.13 µg/ml. This result was in contrast to water extract of BRB, which yielded an IC50 of more than 6000 µg/ml. From the methanolic extract of BRB, its 6 fractions were found from the preparative TLC performance, with Rf values ranging from 0 to 0.97. According to the MTT assay of all fractions, fraction 3 (F3) had the lowest IC50 (60.17 ± 1.72µg/ml), while fraction 2 (F2) had an IC50 of 64.3 ± 0.61µg/ml.…

Eugenol is an alkenyl phenol compound obtained as an essential oil from different parts of the clove such as its leaves and flowers. The essential oil from cloves can contain up to 90% eugenol, which is mainly responsible for its aroma. Eugenol is an interesting compound due to its simplicity and richness in functionalities, making it a valuable building block in synthesis. One of the key steps in eugenol transformation is demethylation to produce a hydroxycavicol. Demethylation is commonly carried out using a nucleophilic or an acidic method. In this study, a simple yet reliable nucleophilic…

Fibroblasts and IL-1α are important components of inflammation and healing in dental caries. This healing allegedly could be enhanced by robusta coffee. The aim of this study was to investigate the effect of varying concentrations of robusta coffee on IL-1α expression and the number of fibroblasts. Wistar rats were used, divided into 4 groups and 3 subgroups (7-, 14"‘, and 21-day rats) with each group containing 4 animals: Control group: untreated group; 25% Coffee Group: cavities + treated with 25% coffee bean paste; 50% Coffee Group: cavities + treated with 50% coffee bean paste; 75%…

As exploration is forced into more difficult areas with complex three-dimensional (3-D) structural environments, the importance of 3-D magnetotelluric (MT) modeling is essential for the correct interpretation of MT data. To reduce the complexity of the calculations introduced by 3-D models, iterative forward calculation of MT response functions is used as basis for inversion of 3-D MT data. This paper proposes an alternative procedure for making reliable 3-D MT modeling codes for forward calculation that is not only effective but also accurate. This is accomplished by using a direct method to…