tahereh rohani

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.

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 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).

The BMI reduction, the healthcare centers' socioeconomic status, and the health services provided have potential effects in controlling diabetes.

Addressed herein, Bismuth sulfide (Bi2S3) as a synthetic semiconductor chalcogenide applied in fabrication process of an aptasensor as a signal promoter for ultra-trace detection of aflatoxin B1(AFB1). The analytical signal was improved by using optimized amounts of Bi2S3 for electrode modification. The AFB1 Aptamer single strand type(SSDNA) was simply immobilized on the cross section of a pencil lead through polydopamine layers. A wide concentration range of trace amounts of AFB1(0.3-630nM) was supported by the fabricated aptasensor (pencil/polydopamine@Bi2S3/aptamer) using differential pulse voltammetry. Simple fabrication and no needing to electrode refreshment were part of the advantages of the suggested aptasensor. Finally, very low resulted detection limit(0.04nM) with a great sensitivity (0.076µA/nM) and also appropriate stability and repeatability led to application of the aptasensor in real sample analysis such as wheat flour with brilliant recovery percentages.

Molybdenum disulfide as a transition metal dichalcogenide was prepared by a hydrothermal method and hybridized with graphene oxide (MoS2/GO). The as-prepared materials were investigated by Fourier transform infra-red spectroscopy (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray elemental analysis (EDX) techniques as well transmission electron microscopy (TEM) image. The nanomaterial with its electrocatalytic properties was applied as an electro-nanocatalyst for loading on a glassy carbon electrode (MoS2/GO-GCE) for detection of carbamazepine as an anti-epileptic in real body samples. The simple and low-cost developed electrochemical sensor detected carbamazepine with a vast linear concentration range(30-350nM), very low detection limit about 6.0nM and significant sensitivity equal to 0.134µA/nM.

Herein, the electrooxidation of ascorbic acid and folic acid, as two essential vitamins, on the surface of the carbon ceramic electrode modified by polydopamine and copper (Cu/PDA/CCE) was investigated. Poly dopamine was fabricated by applying electro deposition conditions. Initial electrochemical characteristics were performed to study the behavior of the fabricated electrode for simultaneous detection of two biomolecules. From voltametric studies using the developed electrode, two separated anodic peaks for folic acid and ascorbic acid were found promisingly for concurrent detection of the compounds. Linear calibration diagrams were obtained in the range of 0.5 to 360 μM and 0.83 to 380 μM with detection limits of about 0.031 and 0.057 μM for folic acid and ascorbic acid, respectively. The developed electrode was applied in human urine sample analysis with satisfying results.

In this work, a new method was developed for simultaneous determination of dopamine and rutin at glassy carbon electrode modified with CuO nanoparticles doped multi-walled carbon nanotubes (CuONPs–MWNT/GCE). This modified electrode has shown excellent electrocatalytic activity toward the oxidation of rutin in acetate buffer solution (pH=5). The modified electrode lowered the overpotential of the reaction by ~500 mV, and this advantage of modified electrode made it aproprate to measure trace values of dopamine in the presence of rutin. First, the electrochemical behavior of CuO nanoparticles, incorporated in the modified electrode, was studied. Then, the behavior of oxidation of rutin and dopamine at the modified electrode was investigated by differntial puls voltammetry. A linear calibration plot was obtained over the range of 0.05-580 µmol L–1 rutin and 0.09-600 μmol L–1 for dopamine. Detection limits of 0.013 µmol L–1 rutin and 0.021 μmol L–1 dopamine were obtained. The relative standard deviation of ten replicate measurements for rutin and dopamine was measured 1.2% and 1.53% respectively. The high sensitivity, low detection limit and reproducibility of the modified electrode, made the proposed electrode suitable for the determination of dopamine in the presence of rutin in pharmaceutical samples

In this work, a new method was developed for the catalytic reduction of hydrogen peroxide at glassy carbon electrode modified with silver nanoparticles and multi-wall carbon nanotubes. Silver incorporated in this modified electrode acted as catalyst to reduce hydrogen peroxide. First, the electrochemical behavior of silver, incorporated in modified electrode, was studied. The results illustrated the adsorption-controlled reaction at the modified electrode. Then, the behavior of catalytic reduction of hydrogen peroxide at the modified electrode was investigated. A linear calibration graph was obtained for hydrogen peroxide over the concentration range of 4.04×10−3 – 1.5×10−6 molL-1. The detection limit for hydrogen peroxide was estimated 1.42×10−7 molL-1. The relative standard deviation of ten replicate measurements (performed on a single electrode at hydrogen peroxide concentration of 1.5×10-4  molL−1) was 2.36%. The proposed electrode was used for the determination of hydrogen peroxide in real samples which led to satisfactory results.