The pKa of the over-all basicity of 4-aminoazobenzene and derivatives has been re solved in pKam and pK^, which represent the pKa of the two basic centers, the amino nitrogen and the /3-azo nitrogen. This resolution has made possible for the first time a comparison of the carcinogenic activity of these dyes with a property related to electron density at these centers. It appears that excessive ...

Clues to the mechanism of biological nitrogen fixation have been sought through experiments aimed at defining the substances specifically required by organisms to effect the process. The nitrogen-fixing sequence in bacteria is known to proceed through ammonia (Zelitch et al., 1951; Newton et al., 1953; Wilson and Burris, 1953; Virtanen, 1953). Thus, the effect of adding ammonium salts to a fixi...

Nitrogen-rich porous carbons (NPCs) were synthesized from 1,5-dihydroxynaphthalene, urea, and formaldehyde based on benzoxazine chemistry by a soft-templating method with KOH chemical activation. They possess high surface areas of 856.8-1257.8 m(2) g(-1), a large pore volume of 0.15-0.65 cm(3) g(-1), tunable pore structure, high nitrogen content (5.21-5.32 wt%), and high char yields. The amount...

Extensive modelling studies on nitrogen (N) dynamics in flooded soil systems have been published. Consequently, many N dynamics models are available for users to select from. With the current research trend, inclined towards multidisciplinary research, and with substantial progress in understanding of N dynamics in flooded soil systems, the objective of this paper is to provide an overview of t...

We present calculations for possible configurations of nitrogen-containing single-walled carbon nanotubes and their electronic properties obtained with the ab initio tight-binding FIREBALL method. It is found that nitrogen atoms can be energetically incorporated into the carbon network in three forms: Substitution, substitution with formation of a vacancy structure, and chemical adsorption. The...

Iron-sulfur (Fe-S) clusters are required for critical biochemical pathways, including respiration, photosynthesis, and nitrogen fixation. Assembly of these iron cofactors is a carefully controlled process in cells to avoid toxicity from free iron and sulfide. Multiple Fe-S cluster assembly pathways are present in bacteria to carry out basal cluster assembly, stress-responsive cluster assembly, ...

The effect which nitrogen has upon boron diffusion through oxynitride gate dielectrics has been studied with secondary ion mass spectroscopy of polycrystalline silicon–oxynitride–silicon structures, and with x-ray photoelectron spectroscopy of silicon–boron–oxynitride–silicon structures. These studies show that the indiffusion of boron results in removal of nitrogen from the oxynitride. This in...

i Abstract Statistical Entropy Analysis (SEA) is a quantitative evaluation method that determines the extent of concentration respective, dilution of a substance caused by a process or system. SEA has been repeatedly used for the assessment of losses of heavy metals from waste treatment facilities leading to a better understanding of the significance of concentration processes for sustainable m...