A novel method with quaternary ammonium salts as internal additives has been applied to the mass scale calibration of time-of-flight secondary ion mass spectrometry (TOF-SIMS). Five kinds of quaternary ammonium salts, octyltrimethylammonium bromide (C8TMA), tetradecyltrimethylammonium chloride (C14TMA), octadecytrimethylammonium chloride (C18TMA), cetylpyridinium chloride (CPC) and benzyldimeth...

In view of the spacious scope of structural information and the molecular interactions between ammonium-based ionic liquids (ILs) and molecular solvents in various applications including chemical and pharmaceutical that are crucial for all aspects of scientific community, the knowledge of the molecular mechanisms, in particular, the thermodynamic basis of the structure-breaking/making interacti...

Tris[bis(triphenylphosphoranylidene)ammonium] pyrophosphate (PPN pyrophosphate) was used in the SN2 displacements of the tosylate ion from 5'-tosylnucleosides to afford nucleoside-5'-diphosphates. Selective precipitation permitted the direct isolation of nucleoside-5'-diphosphates from crude reaction mixtures.

Two novel calix[6]cryptamides bearing a tren-based cap have been synthesized and their host-guest properties have been investigated by (1)H and (19)F NMR spectroscopy. One of them behaves as a remarkable heteroditopic receptor toward either polar neutral guests, anions or contact ion pairs. It has been shown that only F(-) can be encapsulated into the tris-amido cap of this host. Moreover, the ...

Lipases are diversified enzymes in their properties and substrate specificity, which make them attractive tools for various industrial applications. In this study, an alkaline thermostable lipase producing bacteria were isolated from soil of different regions of Isfahan province (Iran) and its lipase was purified by ammonium sulfate precipitation and ion exchange chromatography. To select a the...

Vulnerability of water resources to nutrients led to progressively stricter standards for wastewater effluents. Modification of the conventional procedures to meet the new standards is inevitable. New technologies should give a priority to nitrogen removal. In this paper, ammonium chloride and urine as nitrogen sources were used to investigate the capacity of a microbial electrolysis cell (MEC)...

The aqueous gelation of a quaternary ammonium oligo(propylene oxide)-based ionic liquid yields ion gels with a reverse thermoresponsive behavior (i.e., mechanical moduli and viscosity increase with temperature) and enhanced ionic conductivities.

Electrospray mass spectrometry was used to investigate the mechanism of tetramolecular G-quadruplex formation by the DNA oligonucleotide dTG(5)T, in ammonium acetate. The intermediates and products were separated according to their mass (number of strands and inner cations) and quantified. The study of the temporal evolution of each species allows us to propose the following formation mechanism...