Graphene oxide: an efficient and reusable carbocatalyst for aza-Michael addition of amines to activated alkenes

Graphene oxide was found to be a highly efficient, reusable and cost-effective organocatalyst for the aza-Michael addition of amines to activated alkenes to furnish corresponding β-amino compounds in excellent yields.     

Static permittivity and molecular interactions in binary mixtures of ethanolamine with alcohols and amides

The relative static permittivity at 1 MHz and high frequency limit permittivity at wavelength of sodium-D line of the binary mixtures of ethanolamine (2-aminoethanol) with alcohols (ethyl alcohol, ethylene glycol and glycerol) and amides (formamide, N,N-dimethylformamide and N,N-dimethylacetamide) have been investigated over the entire concentration range at 30 °C. The excess permittivity and Kirkwood correlation factor of the binary mixtures were determined to explore the hydrogen-bonded hetero-molecular interactions and their dependence on the number of hydroxyl groups of alcohols molecules and the extent of substitution in amides molecules. Results confirm that ethanolamine form weak H-bond interactions with alcohols, N,N-dimethylformamide and N,N-dimethylacetamide, but the dipolar alignments in these mixtures vary with number of hydroxyl group of alcohols and their molecular size. Comparatively strong H-bond interactions were found between ethanolamine and formamide molecules with reduce in number of parallel aligned effective dipoles.     

Sulfated polyborate: An efficient and reusable catalyst for one pot synthesis of Hantzsch 1,4-dihydropyridines derivatives using ammonium carbonate under solvent free conditions

A simple and efficient method for the synthesis of four-component 1,4-dihydropyridines of various aldehydes, β-ketoesters and ammonium carbonate catalyzed by sulfated polyborate with high yields under a solvent free condition at 90 °C is described. The key advantages of the present method are high yields, short reaction time, solvent free condition, easy workup, recyclability of catalyst and ability to tolerate a variety of functional groups which gives economical as well as ecological rewards.     

A green one-pot multicomponent synthesis of 4H-pyrans and polysubstituted aniline derivatives of biological, pharmacological, and optical applications using silica nanoparticles as reusable catalyst

A one-pot practical, efficient, and environmentally benign multicomponent synthesis of 4H-pyrans and polysubstituted aniline derivatives of biological, pharmacological, and optical applications has been developed using a very mild, neutral, and reusable silica nanoparticles as catalyst. The 4H-pyran derivatives were synthesized by a three component reaction of an aldehyde, malononitrile, and 5,5-dimethyl-1,3-cyclohexanedione or ethyl acetoacetate at room temperature or refluxing in ethanol. Alternatively, polysubstituted anilines were synthesized via a four component reaction of an aldehyde, a ketone, and two equivalents of malononitrile in ethanol.     

Few-Nucleon System Dynamics Studied via Deuteron–Deuteron Breakup Reactions at 160 MeV

An experiment, with the deuteron beams at energy of 160 MeV impinging on the liquid deuterium target, was carried out using the BINA detector at KVI, in Groningen, the Netherlands. Data were collected for the purpose of obtaining high precision differential cross-sections for the deuteron break-up reaction. The elastic scattering channel was also measured alongside for the purpose of cross-section normalization.     

Test for a specified signal when the noise covariance matrix is unknown

In the univariate case it is well known that the one sided t test is uniformly most powerful for the null hypothesis against all one sided alternatives. Such a property does not easily extend to the multivariate case. In this paper, a test derived for the hypothesis that the mean of a vector random variable is zero against specified alternatives, when the covariance matrix is unknown. This test depends on the given alternatives and is more powerful than Hotelling's T². The results are derived both for real and complex vector observations and under normal and spherical distributions. The properties of the proposed tests are investigated in detail when a single alternative is specified.