DETERMINATION OF CALCIUM CONTENT IN DIETARY SUPPLEMENTS

Calcium is a macro element that is very important for the human body: its content and circulation in the body is large, it serves as the electrolyte, it has a building role and participates in the process of metabolism. The European Union, the World Health Organization (WHO) and the Ministry of Food and Drug (Food and Drug Administration, FDA) gave the RDA (Recommended Dietary Allowances,) for this macro element. The absorption and bioavailability of the calcium may vary depending on a number of factors, and because all of the foregoing it is consumed by means of different supplements. The aim of this study was to determine the content of calcium in the various diet products using the volumetric analytical method of analysis. Supplements that were analyzed are divided into two groups. The first group consists supplements in which the calcium is present in the form of different chemical compounds, and the second group consists of supplements of a number of different manufacturers in which the calcium is in the form of calcium carbonate. Calcium content, obtained by applying the method above, which ranged from 95.11% to 99.80% compared to the theoretical value. Results were analyzed using the t-test, while not producing a statistically significant difference

Synthesis and Characterization of MnCo2O4 Porous Spinel Oxide

This work presents an investigation on spinel structured material that consist of Mn(II) and Co(II) combined in the formula MnCo2O4, where Mn(II) occupies tetrahedral and Co(II) octahedral sites of crystal structure. Such spinel structured material, MnCo2O4 was synthesized by citrate-gel combustion (CGC) technique, carefully chosen as the method of synthesis is very important for producing a material with desirable physico-chemical characteristics

Predictions for the 21 cm-galaxy cross-power spectrum observable with LOFAR and Subaru

The 21 cm-galaxy cross-power spectrum is expected to be one of the promising probes of the Epoch of Reionization (EoR), as it could offer information about the progress of reionization and the typical scale of ionized regions at different redshifts. With upcoming observations of 21 cm emission from the EoR with the Low Frequency Array (LOFAR), and of high-redshift Ly α emitters with Subaru's Hyper Suprime-Cam (HSC), we investigate the observability of such cross-power spectrum with these two instruments, which are both planning to observe the ELAIS-N1 field at z = 6.6. In this paper, we use N-body + radiative transfer (both for continuum and Ly α photons) simulations at redshift 6.68, 7.06 and 7.3 to compute the 3D theoretical 21 cm-galaxy cross-power spectrum and cross-correlation function, as well as to predict the 2D 21 cm-galaxy cross-power spectrum and cross-correlation function expected to be observed by LOFAR and HSC. Once noise and projection effects are accounted for, our predictions of the 21 cm-galaxy cross-power spectrum show clear anti-correlation on scales larger than ∼60 h−1 Mpc (corresponding to k ∼ 0.1 h Mpc−1), with levels of significance p = 0.003 at z = 6.6 and p = 0.08 at z = 7.3. On smaller scales, instead, the signal is completely contaminated. On the other hand, our 21 cm-galaxy cross-correlation function is strongly contaminated by noise on all scales, since the noise is no longer being separated by its k modes

Voltammetric determination of lead and copper in wine by modified glassy carbon electrode

This paper describes the determination of Pb and Cu with a Nafion-modified glassy carbon electrode and MnCo2O4 nanoparticles as working electrode for anodic stripping voltammetry. Pb and Cu were accumulated in HCl/KCl (0.1 mol dm-3) at a potential of -1.4 V (vs. Ag/AgCl electrode) for 480 s, followed by a linear sweep anodic stripping voltammetry (ASV) scan from -1.0 to +0.5 V. Under optimum conditions, the calibration curves were linear in the range of 0.01 - 8 and 0.01 - 5 mg dm-3 for Pb and Cu, respectively. Effect of sample dilution, accumulation time and potential were optimized. A study of interfering substances was performed. A significant increase in current was obtained at the modified electrode in comparison with the bare glassy carbon electrode. The modified electrode was successfully applied for determination of Pb and Cu in wine samples after a simple preparation procedure. Pb and Cu content in wine was used for estimation of the target hazard quotient (THQ) values for minimal and maximal levels of the metals