Development of a nano-modified glassy carbon electrode for the determination of 2,6-diaminotoluene (TDA)

The objective of this study was to improve the overall performance of a glassy carbon electrode (GCE) for the detection of 2,6-diaminotoluene (TDA), a possibly carcinogenic primary aromatic amines (PAAs) that poses a serious risk for the consumer’ health because they can transfer from multilayer food packages including adhesives based on aromatic polyurethane (PU) systems, to the food. The modification of the electrode surface was made by means of multi-walled carbon nanotubes (MWCNTs) and mesoporous carbon nanoparticles (MCNs). The MWCNTs-MCNs/GCE allowed achieving the best performance in terms of sensitivity, as revealed by cyclic voltammetry – CV, with an oxidation peak of 20.95 μA over 0.079 μA of the bare GCE. The pH of the medium influenced the oxidation of 2,6-TDA, with highest sensitivity at pH ∼7. Amperometry experiments led to an estimated detection limit of 0.129 μM, and three linear ranges were obtained for 2,6-TDA: 0.53–11.37 μM, 11.37–229.36 μM, and 229.36–2326.60 μM. Chronoamperometry experiments combined with Cottrell's theory allowed estimating a diffusion coefficient of 2,6-TDA of 1.34 × 10−4 cm2s−1. The number of electrons (n∼1) involved in the catalytic oxidation of 2,6-TDA was determined according to the Laviron's theory. Real sample tests demonstrated that the modification of the sensor using nanoparticls allowed to obtain a highly sensitive and selective sensor, which can possibly used as an alternative analytical device for the rapid, easy, and reliable determination of 2,6-TDA

A screen-printed electrode modified with gold nanoparticles/cellulose nanocrystals for electrochemical detection of 4,4′-methylene diphenyl diamine

Developing simple, cost-effective, easy-to-use, and reliable analytical devices if of utmost importance for the food industry for rapid in-line checks of their products that must comply with the provisions set by the current legislation. The purpose of this study was to develop a new electrochemical sensor for the food packaging sector. More specifically, we propose a screen-printed electrode (SPE) modified with cellulose nanocrystals (CNCs) and gold nanoparticles (AuNPs) for the quantification of 4,4′-methylene diphenyl diamine (MDA), which is one of the most important PAAs that can transfer from food packaging materials into food stuffs. The electrochemical performance of the proposed sensor (AuNPs/CNCs/SPE) in the presence of 4,4′-MDA was evaluated using cyclic voltammetry (CV). The modified AuNPs/CNCs/SPE showed the highest sensitivity for 4,4′-MDA detection, with a peak current of 9.81 μA compared with 7.08 μA for the bare SPE. The highest sensitivity for 4,4′-MDA oxidation was observed at pH = 7, whereas the detection limit was found at 57 nM and the current response of 4,4′-MDA rose linearly as its concentration increased from 0.12 μM to 100 μM. Experiments using real packaging materials revealed that employing nanoparticles dramatically improved both the sensitivity and the selectivity of the sensor, which can be thus considered as a new analytical tool for quick, simple, and accurate measurement of 4,4′-MDA during converting operations

ALTERNATE DAYS TREATMENT WITH TERIPARATIDE IN POSTSURGICAL HYPOPARATHYROIDISM

The conventional treatment of hypoparathyroidism consists of vitamin ID analogues in combination with oral calcium supplementation. This treatment modalities induce chronic hypercalciuria which leads to nephrocalcinosis, nephrolithiasis and renal insufficiency. Here we report the case of a 32-year-old woman who developed hypocalcemia and hypercalciuria under treatment with high doses of vitamin D analogs and oral calcium. She had cerebral calcification, nephrocalcinosis under this treatment. Stable calcium levels were achieved with synthetic human parathyroid hormone treatment that was given in alternate days. PTH appears to be an alternative and effective treatment in hypoparathyroidism

Quality Characteristics of Drip Irrigated Carnation (Dianthus caryophyllus L. cv. "Eilat") under Protected Conditions

International Symposium on Strategies Towards Sustainability of Protected Cultivation in Mild Winter Climate -- JAN 31, 2009 -- Antalya, TURKEYWOS: 000305334500042The interest in cut flower cultivation is increasing gradually because of internal market demand, climate advantages of our country and increase on the production of cut flower for export in recent years. 52% of the total cut flower production in Turkey consists of carnation. This study aims to determine the effects of different irrigation levels on flowering and flower quality of carnation (Dianthus caryophyllus L. cv. "Eilat") grown in plastic greenhouse and irrigated by a drip irrigation system under Mediterranean (Antalya) conditions. In the study, two irrigation intervals (I-1: 10 mm pan evaporation and I-2: 20 mm pan evaporation) and four pan coefficient levels (K-1=0.60 Epan, K-2=0.90 Epan, K-3=1.20 Epan and K-4=1.50 Epan) were applied based on the amount of evaporation measured by a Class A pan located in the greenhouse. Additionally, the effects of different irrigation levels on flowering and flower quality of carnation were statistically analyzed. Results showed that high frequency irrigations using high pan coefficients increased flower stem length, flower stem diameter, stem weight, flower diameter, vase life and yield compared to low frequency irrigation with lower pan coefficients.Scientific and Technological Research Council of Turkey (TUB.TAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK)The authors would like to thank the Scientific and Technological Research Council of Turkey (TUB.TAK) for financial support of the study and to Tempo Tarim Ltd. Company for providing carnation seedling