The use of self-assembling monolayers (SAM) of long chain carboxylic acids has a potential for designing specific interface architectures in degradable implants technology. In this paper, the native and anodically formed oxide films on the Mg-alloy (AZ91D) surface were modified with the SAMs of palmitic acid (PA) and stearic acid (SA) to protect the alloy degradation in a physiological solution. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) were used to evaluate chemical composition, bonding modes of acids to the substrate, and structural properties (ordering and close-packing) of the surface layers. The results obtained by electrochemical impedance spectroscopy (EIS) have shown a beneficial effect of anodization and especially of the oxide layer modification by forming SAMs of PA and SA on the corrosion properties of AZ91D alloy in physiological solutions.Magnesium and its alloys are ideal structural materials for the lightweight engineering applications due to their remarkable properties such as low density, high specific strength, high thermal conductivity, and electromagnetic interference resistance. But so far, their application has been limited mostly due to the poor corrosion and wear resistance. 1 As a potential biodegradable implant material, magnesium shows many advantages over current metallic materials as well as biodegradable polymeric and ceramic materials because it is an essential element and in the human body its concentration is high . 1-3 However, in a solution containing Cl − ions like body fluids magnesium and its alloys easily corrode, and their successful application as degradable orthopedic implants has been mainly inhibited due to the high degradation rates and a consequent loss of the mechanical integrity. 2-6 Various surface treatments have been applied to Mg and its alloys to improve their corrosion resistance and the lifetime of implants including anodization, 7, 8 deposition of chemical conversion layers, 9 treatments based on the sol-gel application, 10 and the surface modification by formation of SAMs of long-chain carboxylic acids. 11, 12 The chemisorption of saturated long-chain (C 16 , C 18 ) carboxylic acids has been also studied on many surfaces such as aluminum oxide, 13-15 iron, 16, 17 zinc, 17 and steel. 18 As endogenous compounds and the main components of fats, fatty acids are very biocompatible substances. According to the Food and Agriculture Organization of the United Nations (FAO) recommendation, the intake of saturated fatty acids by adults should not exceed 10% of the total energy consumption. 19 However; the results on the interaction of carboxylic acids with the magnesium/AZ91D alloy surface are not consistent. While the theoretical studies predict that the most stable adsorbed configuration is one in which the carboxyl group is attached by its each oxygen atom to two separate magnesium ions, 20 the experimental results have confirmed the existence of monodentate bonding, 11 and even the electrostatic attraction of magne...

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The focus of this work was to develop a simple electrochemical method for the determination of vitamin C (VitC) by using a specially constructed microelectrode made from pyrolytic graphite sheet (PGS). A procedure for quantifying VitC in a real sample was established. VitC shows a single quasi-reversible reaction. The method was optimized, and analytical determination was performed by using cyclic voltammetry and square wave voltammetry for electroanalytical purposes. The obtained results show a linear response of the PGS electrode in a wide concentrations range. For the lower concentration range, 0.18–7.04 µg L−1, the sensitivity is 11.7 µAcm−2/mgL−1, while for the higher concentration range, 10.6–70.4 µg L−1, the sensitivity is 134 µAcm−2/mgL−1, preserving the linearity of 0.998 and 0.999. The second objective was to determine the effect of the addition of five different types of “green” biowaste on plant growth, VitC content, and antioxidant activity in arugula (Eruca sativa L.) using the developed method. After three weeks of cultivation, small differences in growth and large differences in certain nutritional characteristics were observed. The addition of black coffee makes the soil slightly alkaline and causes a significant increase in VitC content and antioxidant activity.