Determination of copper, iron, lead, cadmium, cobalt and nickel by atomic absorption spectrometry in baking powder and baking soda samples after preconcentration and separation

The contents of copper, iron, lead, cadmium, cobalt and nickel in baking powder and baking soda samples have been determined by atomic absorption spectrometry after separation and preconcentration. Two different separation/preconcentration methods including APDC-Chromosorb 102 solid phase extraction method and Ce(OH)(4) coprecipitation method have been used for this purpose. The effects of main components of the baking soda and powder were examined. The methods were successfully applied for the determinations of Cu, Fe, Pb, Cd, Co and Ni in the baking soda and baking powder samples purchased from the local markets in Kayseri City-Turkey (recoveries greater than 95%). The results found the two preconcentration methods generally agree with each other. The levels of the analytes in the samples were below the allowed limit values given by Turkish Authorities

A strategy based on the dispersive liquid-liquid microextraction of cadmium in environmental samples prior to ıts determination by flame atomic absorption spectrometry

This work has been supported by the Scientific Research Projects of Karadeniz Technical University (Project no: 1223), Turkey.A simple method was developed by combining dispersive liquid-liquid microexraction (DLLME) and flame atomic absorption spectrometry (FAAS). For the pre-concentration of trace amounts of cadmium, a new complexation chelate of 2-[(4-phenylpiperazine-5-Thioxo- 4,5-dihydro-1 ,3,4-oxadiazole-2- yl)methyl]-5-methyl-4-[2-(1H-indol e-3-yl)ethyl]-2,4-dihydro-3H-1, 2,4-Triazole-3-one (PPTOMDT) was used and mixed with the solvents of chloroform and methanol. The mixture of the extraction solutions was then directly injected into an aqueous solution containing Cd2+ ions. After centrifugation, the settled phase was diluted with 500 mu L of ethanol/nitric acid and aspirated into the FAAS. The limit of detection (LOD) was found at 0.69 mu g L-1 under optimum conditions. The relative standard deviation (RSD) for 15 replicates at a 3.75 mu g L-1 Cd2+ concentration level was 3.21%. The calibration plot was linear within the range of 2.5-15 mu g L-1 of Cd2+. After the analytical characteristics were determined, the CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C, both certified reference materials, were analyzed in order to validate the method. The application of the DLLME method has been successfully tested for the determination of cadmium in solid and liquid samples. The recoveries of the spiked sample ranged between 92-96%

Relative importance of anxiety and motivational variables in predicting language achievement for college learners of Chinese

The growing worldwide enthusiasm in learning Chinese calls for more research on learner characteristics in Chinese classrooms to better inform teaching practice. Language anxiety, which falls under the umbrella of learner’s affect, is considered an important affective aspect that negatively influences language learning and acquisition. As research on language anxiety mainly focused on the learning of Western languages, this study constitutes an initial attempt to investigate anxiety in the learning of Chinese through the testing of a structural model. The purpose of the study was to examine the relative importance of language anxiety in predicting Chinese achievement when motivation, integrativeness, and attitudes toward the learning situation were controlled. The study took place in a Southwestern university in China. Adopting a correlational design, this study measured 14 variables from which five constructs were formed—anxiety, motivation, integrativeness, attitudes toward learning situation, and Chinese achievement. The anxiety measures were from the Chinese language learning anxiety scale. The motivational measures were adapted from the international attitude and motivation test battery. The achievement measures included a HSK listening test, a HSK reading test, and students’ final course grades. A total of 223 students from the International College participated in this study. Students completed a written survey containing all the anxiety and motivational measures. Then they took the HSK listening and reading test. Students’ course grades in the Comprehensive Chinese course were collected at the end of the spring semester. The findings of structural equation modeling suggested that language anxiety negatively predicted Chinese achievement when motivation and attitudes toward the learning situation were controlled. Students’ attitudes toward the learning situation predicted their motivation, but motivation did not predict Chinese achievement. The follow-up analysis showed that motivation predicted student’s course grades but not their performance on the HSK tests. It can be concluded that language anxiety had a negative effect on language achievement for international learners of Chinese. Teachers were recommended to have an awareness of the nervousness and discomfort experienced by their students in language classrooms and to take measures to create a low-anxiety learning environment

Determination of rhodamine b in cosmetics, candy, water, and plastic by a novel multiwalled carbon nanotube (mwcnt)@zinc oxide@magnetite nanocomposite for magnetic solid-phase extraction (mspe) with spectrophotometric detection

A new magnetic solid phase microextraction method (MSPE) was developed for the preconcentration of rhodamine B from plastics, cosmetics, and environmental samples before spectrophotometric analysis. A nanocomposite adsorbent containing ZnO nanoparticles (NPs), multi-walled carbon nanotubes (MWCNTs) and Fe3O4 nanoparticles was synthesized by a hydrothermal procedure. The new magnetic nanocomposite (MWCNTs@ZnO@Fe3O4) was characterized by Fourier-transform infrared spectroscopy (FT-IR), x-ray diffraction (XRD), and scanning electron microscopy (SEM). The pH, sample volume, eluent type, adsorbent mass, influence of foreign species, and analyte-adsorbent and eluent contact times were optimized. The optimum pH was 3; adsorbent mass, 20 mg; sample volume, 50 mL; and eluent, 0.7 mL of ethanol. Recovery values exceeding 95% were obtained. The developed vortex assisted magnetic solid phase extraction method (VA-MSPE) was applied to practical analysis. The limits of detection (LOD) and quantification (LOQ) were 0.83 & mu;g L-1 and 2.77 & mu;g L-1, respectively. The addition/recovery experiments were carried on several water samples to demonstrate acceptable recoveries

Cloud point extraction for the determination of copper in environmental samples by flame atomic absorption spectrometry

A simple cloud point extraction procedure is presented for the preconcentration of copper in various samples. After complexation by 4-hydroxy-2-mercapto-6-propylpyrimidine (PTU), copper ions are quantitatively extracted into the phase rich in Triton X-114 after centrifugation. Methanol acidified with 0.5 mol L-1 HNO3 was added to the surfactant-rich phase prior to its analysis by flame atomic absorption spectrometry (FAAS). Analytical parameters including concentrations for PTU, Triton X-114 and HNO3, bath temperature, centrifugation rate and time were optimized. The influences of the matrix ions on the recoveries of copper ions were investigated. The detection limits (3SDb/m, n=4) of 1.6 ng mL-1 along with enrichment factors of 30 for Cu were achieved. The proposed procedure was applied to the analysis of environmental samples

Development of a Novel Helmet System to Prevent Head and Neck Injuries

The use of helmets is an important requirement in today's use of land and aircraft due to the safetyof the user and sometimes additional requirements. The helmet is the primary protective equipmentfor safety purposes, especially for motorcycle and bicycle users. In situations that require thecommon use of this protective equipment by more than one person, incompatibility occurs becausethere are different sized head structures and the helmet leaves the user's head in the event of anaccident. In this case, the helmet loses its protection. In this case, head and brain injuries and deathsoccur. The same happens when the single-user helmet is incompatible with the user head sizes. Inthis study, a completely new system has been developed for the prevention of injuries and deathscaused by dimensional mismatch in helmet use. The developed system will be an economicalsolution source with its pneumatic structure. It has been determined that with the use and spread ofthe developed system, it is possible to prevent accidental damage, especially head injuries.</p