The values given in the literature for the ammonia content of the brain show wide variation (l-3). Most of these values are of doubtful reliability, since the methods of estimation have not generally taken into account the presence of labile acid amides such as glutamine, which are now known to occur in the brain and which easily liberate ammonia on treatment with alkalies under the conditions ...

Glutamine synthetase (GSase), the enzyme that catalyses the conversion of glutamate and ammonia to glutamine, is present at high levels in vertebrate brain tissue and is thought to protect the brain from elevated ammonia concentrations. We tested the hypothesis that high brain GSase activity is critical in preventing accumulation of brain ammonia and glutamate during ammonia loading in the ammo...

Ammonia has been suggested as a carbon-free hydrogen source, but a convenient method for producing hydrogen from ammonia with rapid initiation has not been developed. Ideally, this method would require no external energy input. We demonstrate hydrogen production by exposing ammonia and O2 at room temperature to an acidic RuO2/γ-Al2O3 catalyst. Because adsorption of ammonia onto the catalyst is ...

Silver nanoparticles were synthesized in the presence of saccharides and ammonia (NH3) in the concentration range from 10-2 to 103 ppm to develop an optical sensor for NH3 in aqueous solutions. Ammonia affects the features of the nanoparticles obtained in a concentration-dependent manner as determined by UV-vis absorption analysis and TEM observations. Structural and morphological analysis prov...

Ammonia is known to be a potent neurotoxin that causes severe negative effects on the central nervous system. Excessive ammonia levels have been detected in the brain of patients with neurological disorders such as Alzheimer disease (AD). Therefore, ammonia could be a factor contributing to the progression of AD. In this review, we provide an introduction to the toxicity of ammonia and putative...

Addition of ammonium salts to E. coli cells grown on a medium with glutamate as the sole nitrogen source is followed by rapid inactivation of glutamine synthetase (GS) I1 The active form of the enzyme (GSa) and the inactive form (GSb) have been isolated.2 Both forms behave similarly in the analytical ultracentrifuge, electrophoresis, and ion exchange chromatography. 2 In a cell-free system GSa ...

The disproportionate quantity of ammonia presence in water has led to serious drinkable water scarcity worldwide. The abundant source of mineral and superior cations selectivity has made natural zeolite as a good adsorbent for the ammonia removal. This work aims to fabricate natural zeolite based hollow fibre ceramic membrane (HFCM) via extrusion based phase inversion and sintering techniques f...

Hypertexture is a powerful and exible procedural modeling tool that is currently limited only by an ine cient rendering mechanism. We analyze the terms of hypertexture functions to obtain an importance measure, capitalize on spatial and image coherence when possible. These enhancements make a guaranteed algorithm for ray-tracing implicit surfaces signi cantly more e cient for rendering hypertex...