Development of a cloud point extraction and preconcentration method for determination of trace aluminum in mineral waters by FAAS

A cloud point extraction (CPE) method has been developed for the preconcentration of trace aluminum prior to its determination by flame atomic absorption spectrometry (FAAS). The CPE method is based on the complex of Al(III) with Xylidyl Blue (XB) and then entrapped in non-ionic surfactant Triton X-114. The main factors affecting CPE efficiency, such as pH of sample solution, concentration of XB and Triton X-114, equilibration temperature and time, were investigated in detail. An enrichment factor of 50 was obtained for the preconcentration of Al(III) with 50 mL solution. Under the optimal conditions, the detection limit of this method for Al(III) is 1.43 μg L^− 1, and the relative standard deviation is 2.7% at determination of 100 μg L^− 1 Al(III). The proposed method has been applied for determination of trace amount of aluminum in mineral water samples with satisfactory results. Also, the proposed method was applied to the certified reference materials. The results obtained were in good agreement with certified values.     

Thermal and kinetic analysis of uranium salts

In this study the thermal decomposition kinetics of uranyl acetate dehydrate [UO₂(CH₃COO)₂·2H₂O] were studied by thermogravimetry method in flowing nitrogen, air, and oxygen atmospheres. Decomposition process involved two stages for completion in all atmosphere conditions. The first stage corresponded to the removal of two?moles of crystal water. The decomposition reaction mechanism of the second stage in nitrogen atmosphere was different from that in air and oxygen atmospheres. Final decomposition products were determined with X-ray powder diffraction method. According to these data, UO₂ is the final product in nitrogen atmosphere, whereas U₃O₈ is the final product in air and oxygen atmospheres. The calculations of activation energies of all reactions were realized by means of model-free and modeling methods. Kissinger?CAkahira?CSunose (KAS) and Flynn?CWall?COzawa (FWO) methods were selected for model-free calculations. For investigation of reaction models, 13 kinetic model equations were tested. The model, which gave the highest linear regression, the lowest standard deviation, and an activation energy value which was close to those obtained from KAS and FWO equations, was selected as the appropriate model. The optimized value of activation energy and Arrhenius factor were calculated using the selected model equation. Using these values, thermodynamic functions (??H*, ??S*, and ??G*) were calculated.     

Hypergeometric Gaussian beam and its propagation in turbulence

We study propagation characteristics of hypergeometric Gaussian beam in turbulence. In this context, we formulate the receiver plane intensity using extended Huygens–Fresnel integral. From the graphical results, it is seen that, after propagation, hypergeometric Gaussian will in general assume the shape of a dark hollow beam at topological charges other than zero. Increasing values of topological charge will make the beam broader with steeper walls. On the other hand, higher values of hollowness parameter will contract into a narrower shape. Raising the topological charge or the hollowness parameter individually will cause outer rings to appear. Both increased levels of turbulence and longer propagation distances will accelerate the beam evolution and help reach the final Gaussian shape sooner. At lower wavelengths, there will be less beam spreading.     

Central neurocytoma: proton MR spectroscopy and diffusion weighted MR imaging findings

Purpose

To present proton magnetic resonance spectroscopy and diffusion-weighted imaging (DWI) findings of central neurocytoma (CN).

Methods and Materials

Imaging findings of seven patients with the histopathological diagnosis of CN (five male and two female; age range, 21–28 years of age) were evaluated retrospectively. In addition to conventional magnetic resonance imaging features, we also assessed the metabolite ratios and tumor normalized apparent diffusion coefficient (NADC), which was calculated by dividing the tumor apparent diffusion coefficient (ADC) values by normal ADC. Approval from our institutional review board was obtained for this review.

Results

The tumor choline/creatine ratios were 5.17±2.38, while N-acetyl aspartate/choline and N-acetyl aspartate/creatine ratios were 0.33±0.15 and 1.84±1.38, respectively. On DWI, tumors had heterogeneous hyperintense appearances when compared with the contralateral parietal lobe white matter and tumor NADC values were 0.63±0.05.

Conclusion

Significantly increased choline/creatine and decreased N-acetyl aspartate/choline ratios with lower NADC values in CN resemble high-grade gliomas and complicate the diagnosis. Familarity its physiologic features would help to presurgical diagnosis of ventricular and exraventricular CNs.     

Neural network study of hidden-charm pentaquark resonances

Recently,the LHCb experiment announced the observation of hidden-charm pentaquark states P,(4312),P_c(4440),and P_c(4457)near Σ_cD and Σ_cD~* thresholds.In this present work,we studied these pentaquarks in the framework of the nonrelativistic quark model with four types of potential.We solved five-body Schrodinger equation by using the artificial neural network method and made predictions of parities for these states,which are not yet determined by experiment.The mass of another possible pentaquark state near the D~*Σ_c~* with J~P=5/2~-is also calculated.     

AgNOR increase in buccal epithelial cells of trisomy 21 infants

The aim of this study is to compare the Argilophilic Nucleolus Organizer Regions (AgNORs) level between Down syndrome (DS) patients and controls in a tissue sharing the same embryonic origin with the central nervous system and compare the results with those obtained recently by us from DS's lymphocytes. For this, buccal desquamating epithelial cells well known as the ectodermic origin were used. Since the AgNOR staining intensity is an indicator of the ribosomes biosynthesis rate, comparison of the image analysis values of the AgNOR area/total nuclear area (NORa/TNa) in buccal desquamating epithelial cells of DS patients and controls provided a plausible conclusion about the regulation/deregulation of the rRNA genes (rDNA) in these cells of DS babies/infants. The (NORa/TNa) proportion was calculated using an in-house computer program. Fifty buccal desquamating cells were analysed for each individual to determine the average NORa/TNa value per individual. In contrast to healthy controls, NORa/TNa proportion value of buccal epithelial cells from DS patients found significantly higher than that of the controls: (4.08 ± 1.16)% and (2.13 ± 0.55)%, respectively. This 92% increase is far higher than the expected value due to the extra rRNA genes on the extra-chromosome 21. Finally DS babies/infants exhibit very higher AgNOR expression increase in their buccal epithelial cells compared to controls. This is the first study that is available on the comparison of AgNOR expression levels in buccal epithelial cells between DS infants and their controls.     

Evolution of the degree of polarization of an electromagnetic Gaussian Schell-model beam in a Gaussian cavity

The interaction of an electromagnetic Gaussian Schell-model (EGSM) beam with a Gaussian cavity is analyzed. In particular, the evolution of the degree of polarization of the EGSM beam is investigated. The results show that the behavior of the degree of polarization depends on both the statistical properties of the source that generates the EGSM beam and the parameters of the cavity.     

Straightforward access to chiral diol bidentate ligands: their efficient enantioselective induction in the addition of diethylzinc to aromatic aldehydes

Enantiopure C₂‐symmetric diol bidentate ligands have been synthesized in a straightforward manner through a three‐step reaction with good yields. The synthesized C₂‐symmetric diol bidentate ligands were used in the addition of diethylzinc to various aromatic aldehydes, a general catalytic benchmark reaction, in order to assess their enantioselective induction properties. The enantioselective addition of diethylzinc to 1‐naphthaldehyde and 3‐chlorobenzaldehyde was achieved with an enantiomeric excess (ee) of up to 98%. All synthesized ligands were also evaluated in the addition of diethyzinc to aromatic aldehydes including an extra metal such as Ti(IV) (up to 99% ee). Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of surfactant on electrokinetic properties of polyindole/TiO2-conducting nanocomposites in aqueous and nonaqueous media

In this study, polyindole (PIN)/TiO₂ nanocomposites were synthesized with and without the presence of sodium dodecylsulfate, anionic surfactant, with two different PIN contents. The synthesized materials were subjected to various characterizations namely: particle size, apparent density, conductivity, dielectric constants, magnetic susceptibility, elemental analysis, Fourier transform infrared spectroscopy spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Characterization results revealed the successful preparations of PIN/TiO₂ hybrid nanocomposites. Electrokinetic properties of all the materials were determined by zeta (ζ)-potential measurements in aqueous and nonqueous media. Effects of pH, temperature, presence of various electrolytes, and surfactants on electrokinetic properties of the materials were examined.