Search results for "Phosphates"
showing 10 items of 273 documents
Effects of high-pressure on the structural, vibrational, and electronic properties of monazite-type PbCrO4
2012
We have performed an experimental study of the crystal structure, lattice dynamics, and optical properties of PbCrO 4 (the mineral crocoite) at ambient and high pressures. In particular, the crystal structure, Raman-active phonons, and electronic band gap have been accurately determined. X-ray-diffraction, Raman, and optical absorption experiments have allowed us also to completely characterize two pressure-induced structural phase transitions. The first transition is from a monoclinic structure to another monoclinic structure. It maintains the symmetry of the crystal but has important consequences in the physical properties; among others, a band-gap collapse is induced. The second one invo…
The Yeast RNA Polymerase II-associated Factor Iwr1p Is Involved in the Basal and Regulated Transcription of Specific Genes
2009
RNA polymerase II (RNA pol II) is a multisubunit enzyme that requires many auxiliary factors for its activity. Over the years, these factors have been identified using both biochemical and genetic approaches. Recently, the systematic characterization of protein complexes by tandem affinity purification and mass spectroscopy has allowed the identification of new components of well established complexes, including the RNA pol II holoenzyme. Using this approach, a novel and highly conserved factor, Iwr1p, that physically interacts with most of the RNA pol II subunits has been described in yeast. Here we show that Iwr1p genetically interacts with components of the basal transcription machinery …
Polyphosphoinositide Metabolism and Golgi Complex Morphology in Hippocampal Neurons in Primary Culture is Altered by Chronic Ethanol Exposure
2012
Aims : Ethanol affects not only the cytoskeletal organization and activity, but also intracellular trafficking in neurons in the primary culture. Polyphosphoinositide (PPIn) are essential regulators of many important cell functions, including those mentioned, cytoskeleton integrity and intracellular vesicle trafficking. Since information about the effect of chronic ethanol exposure on PPIn metabolism in neurons is scarce, this study analysed the effect of this treatment on three of these phospholipids. Methods : Phosphatidylinositol (PtdIns) levels as well as the activity and/or levels of enzymes involved in their metabolism were analysed in neurons chronically exposed to ethanol. The level…
Chromatin remodeling regulation by small molecules and metabolites.
2010
The eukaryotic genome is a highly organized nucleoprotein structure comprising of DNA, histones, non-histone proteins, and RNAs, referred to as chromatin. The chromatin exists as a dynamic entity, shuttling between the open and closed forms at specific nuclear regions and loci based on the requirement of the cell. This dynamicity is essential for the various DNA-templated phenomena like transcription, replication, and repair and is achieved through the activity of ATP-dependent chromatin remodeling complexes and covalent modifiers of chromatin. A growing body of data indicates that chromatin enzymatic activities are finely and specifically regulated by a variety of small molecules derived f…
Pressure-Induced Hexagonal to Monoclinic Phase Transition of Partially Hydrated CePO4
2019
We present a study of the pressure dependence of the structure of partially hydrated hexagonal CePO 4 up to 21 GPa using synchrotron powder X-ray diffraction. At a pressure of 10 GPa, a second-order structural phase transition is observed, associated with a novel polymorph. The previously unknown high-pressure phase has a monoclinic structure with a similar atomic arrangement as the low-pressure phase, but with reduced symmetry, belonging to space group C2. Group-subgroup relations hold for the space symmetry groups of both structures. There is no detectable volume discontinuity at the phase transition. Here we provide structural information on the new phase and determine the axial compress…
Application of a fuzzy algorithm for pH control in a struvite crystallisation reactor
2006
A struvite crystallisation process is highly dependent on pH. To achieve a high phosphorus recovery as struvite it is important to have an accurate control of pH in the reactor. The high non-linear response of pH value makes manual pH control difficult. Therefore, a software based on fuzzy logic control (FLC) has been developed to maintain the pH at a set value in a stirred reactor to crystallise struvite. The FLC developed has been based on Larsen's inference. In order to confirm the improvement of the pH stability using FLC software, different experiments have been carried out with manual control of the pH value, and with the FLC software. It has been demonstrated that using FLC software …
Modelling the metabolic shift of polyphosphate-accumulating organisms
2014
Enhanced biological phosphorus removal (EBPR) is one of the most important methods of phosphorus removal in municipal wastewater treatment plants, having been described by different modelling approaches. In this process, the PAOs (polyphosphate accumulating organisms) and GAOs (glycogen accumulating organisms) compete for volatile fatty acids uptake under anaerobic conditions. Recent studies have revealed that the metabolic pathways used by PAOs in order to obtain the energy and the reducing power needed for polyhydroxyalkanoates synthesis could change depending on the amount of polyphosphate stored in the cells. The model presented in this paper extends beyond previously developed metaboli…
An extension of ASM2d including pH calculation
2003
This paper presents an extension of the Activated Sludge Model No. 2d (ASM2d) including a chemical model able to calculate the pH value in biological processes. The developed chemical model incorporates the complete set of chemical species affecting the pH value to ASM2d describing non-equilibrium biochemical processes. It considers the system formed by one aqueous phase, in which biochemical processes take place, and one gaseous phase, and is based on the assumptions of instantaneous chemical equilibrium under liquid phase and kinetically governed mass transport between the liquid and gas phase. The ASM2d enlargement comprises the addition of every component affecting the pH value and an i…
Treatment of a submerged anaerobic membrane bioreactor (SAnMBR) effluent by an activated sludge system: the role of sulphide and thiosulphate in the …
2014
This work studies the use of a well-known and spread activated sludge system (UCT configuration) to treat the effluent of a submerged anaerobic membrane bioreactor (SAnMBR) treating domestic waste-water. Ammonia, phosphate, dissolved methane and sulphide concentrations in the SAnMBR effluent were around 55 mg NH4-N L-1, 7 mg PO4-P L-1, 30 mg non-methane biodegradable COD L-1, and 105 mg S2- L-1 respectively. The results showed a nitrification inhibition caused by the presence of sulphur compounds at any of the solids retention time (SRT) studied (15,20 and 25 days). This inhibition could be overcome increasing the hydraulic retention time (HRT) from 13 to 26 h. Among the sulphur compounds, …
Towards the design of organocatalysts for nerve agents remediation: The case of the active hydrolysis of DCNP (a Tabun mimic) catalyzed by simple ami…
2015
We report herein a study of the hydrolysis of Tabun mimic DCNP in the presence of different amines, aminoalcohols and glycols as potential suitable organocatalysts for DCNP degradation. Experiments were performed in CD3CN in the presence of 5% D2O, which is a suitable solvent mixture to follow the DCNP hydrolysis. These studies allowed the definition of different DCNP depletion paths, resulting in the formation of diethylphosphoric acid, tetraethylpyrophosphate and phosphoramide species as final products. Without organocatalysts, DCNP hydrolysis occurred mainly via an autocatalysis path. Addition of tertiary amines in sub-stoichiometric amounts largely enhanced DCNP depletion whereas non-te…