On‐line determination of sarcosine in biological fluids utilizing dummy molecularly imprinted polymers in microextraction by packed sorbent

Several years ago, sarcosine received attention as a prostate‐cancer marker. Prostate cancer is one of the most widespread types of tumor diseases in men. The prostate‐specific antigen is normally used as a marker, and it can only be detected in blood with a sensitivity of approximately 80%. In the present study, dummy molecularly imprinted polymers in microextraction by packed sorbent with on‐line liquid chromatography coupled to tandem mass spectrometry was used for the determination of sarcosine in human plasma and urine samples. The polymer network glycine was used for the dummy molecularly imprinted polymers. The selectivity of the method was evaluated using similar prostate‐cancer biomarkers. In addition, various parameters affecting the extraction performance were investigated. The method limits of detection and quantification in the plasma and urine were 1.0 and 3.0 ng/mL, respectively. The values of the coefficient of determination were over 0.99 for all runs in the studied concentration range (3.0–10 000 ng/mL). The method recovery was 87 and 89% in plasma and urine, respectively. The intraday and interday precisions of sarcosine in the plasma and urine samples were in the ranges of 4.0–7.1, 3.0–6.3, 2.9–4.7, and 5.0–6.7, respectively.     

A collocated grid,projection method for time‐accurate calculation of low‐Mach number variable density flows in general curvilinear coordinates

A time‐accurate algorithm is proposed for low‐Mach number, variable density flows on curvilinear grids. Spatial discretization is performed on collocated grid that offers computational simplicity in curvilinear coordinates. The flux interpolation technique is used to avoid the pressure odd–even decoupling of the collocated grid arrangement. To increase the stability of the method, a two‐step predictor–corrector time integration scheme is employed. At each step, the projection method is used to calculate the hydrodynamic pressure and to satisfy the continuity equation. The robustness and accuracy of the method is illustrated with a series of numerical experiments including thermally driven cavity, polar cavity, three‐dimensional cavity, and direct numerical simulation of non‐isothermal turbulent channel flow. Copyright © 2012 John Wiley & Sons, Ltd.     

Si-decorated graphene: a superior media for lithium-ions storage

The characteristics of lithium adsorption on Si-decorated graphene are investigated using first-principles density functional theory calculations. It is found that the Si atom is strongly adsorbed at the bridge site of the C–C bond with binding energy of about ?26.75 kcal/mol. We show that Si decorating turns Si:graphene complex into an electron-deficient system and significantly enhances the Li-storage capacity on the graphene. The obtained results indicate that up to eight Li-ions being adsorbed onto the Si-decorated graphene can form the stable complex. It is found, interestingly, that two Si atoms coated onto double-side of the graphene can strongly adsorb sixteen Li-ions. The analyses of electronic structures show a strong interaction between Li-ions and Si-decorated graphene leading to a high exothermicity. The stability of the sixteen Li-ions adsorbed on the Si:graphene system was evaluated with ab initio molecular dynamics simulation which have been carried out at room temperature. Our first-principles results are relevant to identify the potential applications of Si-decorated graphene as superior media for Li-ions storage.     

Production of cationic 198Au3+ and nonionic 198Au0 for radionuclide therapy applications via the natAu(n,γ)198Au reaction

¹⁹⁸Au (??_max?=?0.96?MeV (98.6?%), ??_max?=?0.412?MeV (95.5?%) and T _1/2 ?=?2.7?days) is a radionuclide with very appealing characteristics. ¹⁹⁸Au has been widely used to treat the uterus, bladder, cervix, prostate, melanoma, breast, skin and other cancers. In the present study, cationic ¹⁹⁸Au⁺³ and nonionic ¹⁹⁸Au⁰ are prepared following thermal neutron irradiation of commercially available natural gold compounds in Tehran Research Reactor via the ^natAu(n,??)¹⁹⁸Au reaction. The prospects in the production of pure ¹⁹⁸Au⁰ and ¹⁹⁸Au⁺³ for radionuclide therapy are discussed and effect of reduction on the activity of radioactive gold is evaluated. Au⁰ particles were synthesized via NaBH₄ reduction of aqueous solutions of hydrogen tetrachloroaurate trihydrate. Then two quartz tubes were charged with cationic ¹⁹⁸Au³⁺ and nonionic ¹⁹⁸Au⁰. After irradiation by thermal neutrons, the samples were analyzed for a period of 1?month by liquid scintillation counter and high purity germanium detector. As a result, ^natAu³⁺ reduction process had no significant effect on the activity of the ¹⁹⁸Au sample. In conclusions, natural gold thermal neutron activation cross section is reasonably high for medical application.     

Synthesis,X‐ray structure,characterization and catalytic activity of a polymeric manganese(II) complex with iminodiacetate

A polymeric manganese(II) complex with the general formula [Mn(O₂CCH₂NH₂CH₂CO₂)₂(H₂O)₂]_n from reaction of iminodiacetatic acid and manganese(II) perchlorate under nitrogen in water, was synthesized and characterized. The structure of the complex was determined using single‐crystal X‐ray diffraction, elemental analysis, IR and UV‐vis spectra. This complex exhibited excellent catalytic activity and selectivity for oxidation of various alcohols and sulfides to the corresponding aldehydes/ketone and sulfoxides using urea hydrogen peroxide and oxone (2KHSO₅·KHSO₄·K₂SO₄), respectively, as oxidants under air at room temperature. The easy preparation, mild reaction conditions, high yields of the products, short reaction time, no over‐oxidation products, high selectivity and inexpensive system make this catalytic system a useful method for oxidizing various alcohols and sulfides. Copyright © 2011 John Wiley & Sons, Ltd.     

Numerical investigation of particle separation in Y-shaped bifurcating microchannels

In this study the Zweifach-Fung effect is investigated in a Y-shaped bifurcation when the clearance between the rigid spherical particle and the walls is small ...