Phosphine-free conversion of alcohols into alkyl thiocyanates using trichloroisocyanuric acid/NH4SCN

A convenient and efficient phosphine-free procedure for the one-pot conversion of primary,secondary and tertiary alcohols into the corresponding alkyl thiocyanates or alkyl isothiocyanates is described using trichloroisocyanuric acid/NHUSCN.     

Applications of calixarene nano-baskets in pharmacology

Calixarene nano-baskets enable to encapsulate the guest drugs and show different biological activities. This review deals with the behavior of calixarene-based drugs and illustrates their potentials in the pharmacological sciences. The role of calixarene’s scaffolds and substitutions in aspects of anti-cancer, anti-mycobacterial, anti-proliferativity, catalytic and inhibitory activities as well as solubility control, drug analysis, drug purification, drug supports and structural studies is reviewed.     

Non-asymptotic superlinear convergence of standard quasi-Newton methods

Mathematical Programming - In this paper, we study and prove the non-asymptotic superlinear convergence rate of the Broyden class of quasi-Newton algorithms which includes the...     

Three dimensional numerical study of the effect of large Grashof number on HEM crystal growth

Heat transfer and fluid flow in HEM crystal growth of silicon in cylindrical cavity is studied numerically. The walls of the crucible are heated to a fixed temperature. The exchanger that causes and induces natural convection is seated at the middle‐bottom of the crucible. The finite‐volume method is employed to solve the governing equations with proper boundary conditions. The effects of transport mechanism on the temperature distribution, melt flow, pressure and stream function are presented. We focus our work on the pressure field which has not yet been studied in HEM crucible. Also, we extend our work on a wide range Grashof number and for large numbers until 10¹² not yet studied in HEM furnace. It is found that the onset of flow fluctuations appears at Gr = 10¹⁰. Uniform temperature is observed in the entire melt at high Grashof number with development of a thermal boundary layer close to the exchanger. The thermal boundary layer thickness is calculated for strong buoyancy regime. Besides, for very high Gr number, buoyancy has less effect on temperature and then on melt‐crystal interface shape. During enlarging Gr, pressure evolution is related to temperature variation more than flow pattern.     

Chelator-free radiolabeling of dextran with 68Ga for PET studies

Journal of Radioanalytical and Nuclear Chemistry - The possibility of 68Ga-dextran complex formation was analyzed in an HEPES-buffered (pH = 4.5) as well as in an alkaline...     

Determination of lewisite metabolite 2-chlorovinylarsonous acid in urine by use of dispersive derivatization liquid-liquid microextraction followed by gas chromatography–mass spectrometry

The purpose of this study was to develop a sensitive and simple method, based on dispersive derivatization liquid-liquid microextraction–gas chromatography–mass spectrometry (DDLLME–GC–MS) in scanning and selected-ion-monitoring (SIM) modes, for detection of 2-chlorovinylarsonous acid (CVAA) as a hydrolysis product and urinary metabolite of lewisite in urine samples. Chloroform (65 μL), methanol (500 μL), and ethanedithiol (10 μL) were used as extraction solvent, dispersive solvent, and derivatizing reagent, respectively. Critical conditions of the proposed method were optimized. The nucleophilic reactions of dithiol and monothiol compounds with CVAA were also studied using a competitive method. In view of the high affinity of trivalent arsenic for sulfhydryl groups, the interaction between CVAA and bis(2-chlorovinyl)arsonous acid (BCVAA) and free cysteine (Cys) was also investigated using liquid chromatography–electrospray ionization mass spectrometry (LC–ESI-MS). The interference of Cys, present in human urine, with the detection of CVAA was evaluated using dithiol and monothiol chemicals as derivatization agents. The developed method provided a preconcentration factor of 250, and limits of detection of 0.015 and 0.30 μg L^?1 in SIM and scanning modes, respectively. The calibration curves were linear over the concentration range of 1–400 μg L^?1 in full-scan mode. The relative standard deviation (RSD) values were calculated to be 5.5 and 3.2 % at concentrations of 20 and 100 μg L^?1, respectively. Collision-induced dissociation studies of the major electron-impact (EI) ions were performed to confirm the proposed fragment structure of CVAA-dithiols derivatives. Results indicated that the developed method for analysis of CVAA is suitable not only for verification of human exposure to lewisite, but also for quantification of CVAA in urine samples.