Studies on matrix interferences during uranium analysis by extractive liquid scintillation technique

Journal of Radioanalytical and Nuclear Chemistry - The efficiency of ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) in reducing the influence of salinity and...     

A novel eco-friendly on-water protocol for the synthesis of 2,2-disubstituted 2,3-dihydro-1H-perimidines

An efficient green on-water protocol for the synthesis of 2,2-disubstituted 2,3-dihydro-1H-perimidines is demonstrated. The reaction used safer p-toluenesulfonic acid (PTSA) as a catalyst on water at 80°C, for 2 hours affording a novel method for the synthesis of various disubstituted perimidines in moderate to excellent yields.     

Highly regio- and stereoselective Michael addition of pseudouridine with propiolates: An efficient method for the synthesis of (E)-pseudouridine-N1-acrylate

The Michael addition of pseudouridine with various propiolates in the presence of DBU as a base and DMF as a solvent is described. It is noteworthy that the reaction is highly regio- and stereoselective and affords (E)-pseudouridine-N1-acrylate in good yields with high purities.     

Gamma spectrometric analysis of ore samples from Sandur of Bellary, Karnataka, India

In the present paper the gamma spectrometric technique has been used to study the natural radioactivity levels present in the iron ore samples collected from the Sandur of Karnataka, India. This region, a member of Dharwar craton, known as Sandur schist belt is rich in Manganese and Hematite ore (Fe). The entire belt is characterized by numerous bands of banded magnetite and hematite quartzite. The ore samples were collected and prepared as per the ASTM standard procedures. The gamma spectrometric measurements were performed using a HPGe detector (Eurosys) based high-resolution 8k multi channel analyzer. The detector has a relative efficiency of 50% and resolution of 2.0?keV for 1.332?MeV gamma energy of ⁶⁰Co. The output of the detector was analyzed using a PC based 8k channel analyzer system. The mean activity concentrations of the ²³⁸U, ²³²Th and ⁴⁰K in the ore samples were found to be 14.59, 16.54 and 25.29?Bq/kg, respectively. The mean absorbed dose rate and the annual dose equivalent were estimated to be 18.97?nGy?h^?1 and 24.93???Sv?y^?1, respectively, which is lower than the world recommended average of 1?mSv?y^?1. The present work concludes that the natural radioactivity levels in ore samples of this region is within the natural limits and pose no health hazard to the public.     

Efficient synthesis of 3-cyanovinylcarbazole-1′-β-deoxyriboside-5′-triphosphate: a reversible photo-cross-linking probe

We describe an efficient synthesis of 3-cyanovinylcarbazole-1′-β-deoxyriboside-5′-triphosphate containing light-responsive artificial nucleobase 3-cyanovinylcarbazole, which can be used as a reversible photo-cross-linking probe with nucleic acid compounds for various biological applications. A three-step synthesis of 3-cyanovinylcarbazole-1′-β-deoxyriboside starting from 3-cyanovinylcarbazole, followed by ‘one-pot, three-step’ procedure is presented to accomplish the title compound 3-cyanovinylcarbazole-1′-β-deoxyriboside-5′-triphosphate in good yields.     

Self-similar solution of the unsteady mixed convection flow in the stagnation point region of a rotating sphere

An analysis is performed to present a new self-similar solution of unsteady mixed convection boundary layer flow in the forward stagnation point region of a rotating sphere where the free stream velocity and the angular velocity of the rotating sphere vary continuously with time. It is shown that a self-similar solution is possible when the free stream velocity varies inversely with time. Both constant wall temperature and constant heat flux conditions have been considered in the present study. The system of ordinary differential equations governing the flow have been solved numerically using an implicit finite difference scheme in combination with a quasilinearization technique. It is observed that the surface shear stresses and the surface heat transfer parameters increase with the acceleration and rotation parameters. For a certain value of the acceleration parameter, the surface shear stress in x-direction vanishes and due to further reduction in the value of the acceleration parameter, reverse flow occurs in the x–component of the velocity profiles. The effect of buoyancy parameter is to increase the surface heat transfer rate for buoyancy assisting flow and to decrease it for buoyancy opposing flow. For a fixed buoyancy force, heating by constant heat flux yields a higher value of surface heat transfer rate than heating by constant wall temperature.     

Determination of the activity ratios of 231Pa to 235U and 227 Th to 235U in ore samples using gamma-spectrometry

Summary Elérhetoség     

Regioselective nucleophilic addition of methoxybenzene derivatives to the beta-carbon of p-benzoquinone mono O,S-acetal.

Regioselective nucleophilic addition of electron rich aromatics to the beta-position of acetal carbon of p-benzoquinone mono O,S-acetal was achieved by modifying the acetal moiety.     

New efficient approach to 2,2-diaryl-1,1-difluoro-1-alkenes and 1,1-difluoro-2-aryl-1,3-dienes via Suzuki coupling of alpha-halo-beta,beta-difluorostyrenes

[reaction: see text] Alpha-halo-beta,beta-difluorostyrenes [ArCX = CF2; X = Br, I; Ar = aryl, heteroaryl; synthesized by the Pd(0)-catalyzed coupling reaction of the corresponding alpha-halo-beta,beta-difluoroethenylzinc reagents (CF2=CXZnCl, X = Br, I) with aryl iodides] were functionalized at the halogen site with arylboronic acids under Pd(0)-catalyzed Suzuki-Miyaura coupling reaction conditions to obtain 2,2-diaryl-1,1-difluoro-1-alkenes (ArAr'C=CF2, Ar' = aryl, heteroaryl) in 51-91% isolated yield. The corresponding reaction with alkenylboronic acids produced 1,1-difluoro-2-aryl-1,3-dienes in 53-80% isolated yield. Alternatively, 2,2-disubstituted-1,1-difluoro-1-alkenes were synthesized in moderate yield by a zinc-insertion reaction at the halogen site of the alpha-halo-beta,beta-difluorostyrenes, followed by Pd(0)-catalyzed cross-coupling of the zinc reagent with aryl or alkenyl iodides.