Factors affecting blood sugar changes in diabetic patients using a three-level model in analysis of longitudinal data.

Background: Diabetes, a currently threatening disease, has severe consequences for individuals' health conditions. The present study aimed to investigate the factors affecting the changes in the longitudinal outcome of blood sugar using a three-level analysis with the presence of missing data in diabetic patients. Methods: A total of 526 diabetic patients were followed longitudinally selected from the annual data collected from the rural population monitored by Tonekabon health centers in the North of Iran during 2018-2019 from the Iranian Integrated Health System (SIB) database. In analyzing this longitudinal data, the three-level model (level 1: observation (time), level 2: subject, level 3: health center) was carried out with multiple imputations of possible missing values in longitudinal data. Results: Results of fitting the three-level model indicated that every unit of change in the body mass index (BMI) significantly increased the fasting blood sugar by an average of 0.5 mg/dl (p=0.024). The impact of level 1 (observations) was insignificant in the three-level model. Still, the random effect of level 3 (healthcare centers) showed a highly significant measure for health centers (14.62, p<0.001). Conclusion: The BMI reduction, the healthcare centers' socioeconomic status, and the health services provided have potential effects in controlling diabetes.

Preparation of a carbon ceramic electrode modified by 4-(2-pyridylazo)-resorcinol for determination of trace amounts of silver.

A 4-(2-pyridylazo)-resorcinol (PAR)-modified carbon ceramic electrode (CCE) prepared by the sol-gel technique has been reported for the first time in this paper. By immersing the CCE in aqueous solution of PAR (0.001molL(-1)), after a short period of time, a thin film of PAR was rapidly formed on the surface of the electrode due to its strong adsorption properties. A differential pulse anodic stripping voltammetric (DPASV) method was developed for determination of Ag(I) at the modified carbon ceramic electrode. The analysis procedure consisted of an open circuit accumulation step in a sample solution which was continuously stirred for 12 min. This was followed by replacing the medium with a clean solution where the accumulated Ag(I) was reduced for 15s in -0.6 V. Then, the potential was scanned from -0.2 to +0.2V to obtain the voltammetric peak. The detection limit of silver(I) was 0.123 microg L(-1), and for seven successive determinations of 10, 100 and 200 microg L(-1) Ag(I), the relative standard deviations were 2.1, 1.4 and 1.03%, respectively. The calibration curve was linear for 0.5-300 microg L(-1) silver(I). The procedure was applied to determine silver(I) in X-ray photographic films and super-alloy samples.

A new method for electrocatalytic oxidation of ascorbic acid at the Cu(II) zeolite-modified electrode.

A new method is developed for the catalytic oxidation of ascorbic acid at graphite zeolite-modified electrode, doped with copper(II) (Cu(2+)A/ZCME). Copper(II) exchanged in zeolite type A acts as catalyst to oxidize ascorbic acid. The modified electrode lowered the overpotential of the reaction by approximately 400 mV. First, the electrochemical behavior of copper(II), incorporated in the zeolite type A modified electrode, was studied. The results illustrate that diffusion can control the copper(II)/copper(0) redox process at the Cu(2+)A/ZCME. Then, the behavior of electrocatalytic oxidation reaction for ascorbic acid was researched. The electrode was employed to study electrocatalytic oxidation of ascorbic acid, using cyclic voltammetry and chronoamperometry as diagnostic techniques. The diffusion coefficient of ascorbic acid was equal to 1.028 x 10(-5)cm(2)s(-1). A linear calibration graph was obtained over the ascorbic acid with a concentration range of 0.003-6.00 mmol L(-1). The detection limit (DL) of ascorbic acid was estimated as 2.76 x 10(-7)mol L(-1). The relative standard deviations of 10 replicate measurements (performed on a single electrode at several ascorbic acid concentrations between 3.0 and 200 micromol L(-1)) were measured between 1.0 and 2.4%.

A new method for application of the water-soluble dye SPADNS in a carbon paste electrode for determination of trace amounts of copper.

2-(P-sulfophenylazo)-1,8-dihydroxy-3,6-naphthalene disulfate (SPADNS) was adsorbed on surfactant modified zeolite type A by electrostatic interaction in the aqueous phase. The dye was strongly retained and not easily leached from the surfactant-modified zeolite matrix. This compound was incorporated into a carbon paste electrode for anodic stripping voltammetric determination of trace amounts of copper. The calibration plot was linear over the copper concentration range 2.0-800 microg/L. The detection limit was found to be 0.4 microg/L Cu(II), and for 5 successive determinations of 50 and 150 microg/L Cu(II) the relative standard deviations were 1.6 and 1.2%, respectively. The modified electrode prepared in this study could be used for the determination of Cu(II) in water samples and human hair with good results.