Starch coated titanium dioxide nanoparticles as a challenging sorbent to separate and preconcentrate some heavy metals using graphite furnace atomic absorption spectrometry

In this study, a challenging nanosorbent was described for preconcentration/separation method based on the sorption of cadmium, cobalt, copper, nickel, lead on starch coated titanium dioxide nanoparticles and its analysis by graphite furnace atomic absorption spectrometry. Optimum conditions were investigated for quantitative sorption. By using the proposed technique, the analyte elements were determined in spiked tap-water samples in the range of 95% confidence level. Limit of detection (3δ) was 0.05, 0.28, 1.90, 3.10 and 0.11 µg/L (3σ, N = 10) for cadmium, cobalt, copper, nickel and lead, respectively. The optimised technique is fast, easy handled, simple and environmental friendly.     

Theoretical investigation of the Anti-Parkinson drug rasagiline and its salts: conformations and infrared spectra

The conformational analysis of rasagiline [N-propargyl-1(R)-aminoindan] was performed by the density functional theory (DFT) B3LYP method using the 6–31++G (d,p) basis set. A single point energy calculations based on the B3LYP optimized geometries were also performed at MP2/6-31++G (d, p) level. The vibrational frequencies of the most stable conformer of rasagiline was calculated at the B3LYP level and vibrational assignments were made for normal modes on the basis of scaled quantum mechanical force field (SQM) method. The influence of mesylate and ethanedisulfonate salts on the geometry of rasagiline free base and its normal modes are also discussed.      

The Contribution of Conceptual Change Texts Accompanied by Concept Mapping to Students' Understanding of the Human Circulatory System

The present study was conducted to investigate the contribution of conceptual change texts accompanied by concept mapping instruction to 10^th— grade students' understanding of the human circulatory system. To determine misconceptions concerning the human circulatory system, 10 eleventh-grade students were interviewed. In the light of the findings obtained from student interviews and related literature, the Human Circulatory System Concepts Test was developed. The data were obtained from 26 students in the experimental group taught with the conceptual change texts accompanied by concept mapping, and 23 students in the control group taught with the traditional instruction. Besides treatment, previous learning in biology and science process skills were other independent variables involved in this study. Multiple Regression Correlation analysis revealed that science process skill, the treatment, and previous learning in biology each made a statistically significant contribution to the variation in students' understanding of the human circulatory system. It was found that the conceptual change texts accompanied by concept mapping instruction produced a positive effect on students' understanding of concepts. The mean scores of experimental and control groups showed that students in the experimental group performed better with respect to the human circulatory system. Item analysis was carried out to determine and compare the proportion of correct responses and misconceptions of students in both groups. The average percent of correct responses of the experimental group was 59.8%, and that of the control group was 51.6% after treatment.     

One-step hydrothermal synthesis of nitrogen doped reduced graphene oxide-silver nanocomposites: Catalytic performance

The aim of this study is to efficiently utilize catalytic properties of silver nanoparticles and nitrogen doped graphene and their combined synergistic effect. For this purpose, nitrogen doped reduced graphene oxide-silver (NrGO-Ag) nanocomposites were synthesized by a facile, environmentally friendly, one-pot hydrothermal method for the first time and characterized by UV–Vis, FTIR, XRD, XPS, SEM, and TEM. Catalytic activity of the synthesized nanocomposites was tested against 4-nitrophenol (4-NP) and methylene blue (MB) reduction reactions in the presence of NaBH₄. Total degradation was achieved in both reactions in 210 and 44 s, and pseudo first order reaction rate constants were calculated as 0.0071 and 0.0322 s⁻¹ for 4-NP and MB reduction reactions, respectively.