Search results for "PHOSPHATE"
showing 10 items of 1874 documents
Modelling biological and chemically induced precipitation of calcium phosphate in enhanced biological phosphorus removal systems
2011
The biologically induced precipitation processes can be important in wastewater treatment, in particular treating raw wastewater with high calcium concentration combined with Enhanced Biological Phosphorus Removal. Currently, there is little information and experience in modelling jointly biological and chemical processes. This paper presents a calcium phosphate precipitation model and its inclusion in the Activated Sludge Model No 2d (ASM2d). The proposed precipitation model considers that aqueous phase reactions quickly achieve the chemical equilibrium and that aqueous-solid change is kinetically governed. The model was calibrated using data from four experiments in a Sequencing Batch Rea…
Degradation and acute toxicity of Methidathion and Trichlorfon onProcambarus clarkii,in experimental conditions
1991
Routine applications of organophosphate pesticides may adversely affect many nontarget organisms. Static toxicities in mature crayfish Procambarus clarkii were determined, in laboratory, for two organophosphate insecticides using 24, 48, 72 and 96‐h static tests. Three groups of 10 crayfish were exposed to 0.75 to 6 ppm for Trichlorfon and 0.2 to 0.9 ppm for Methidathion. The 24 to 96‐h LC50 values for Trichlorfon and Methidathion were from 5.14–0.99 ppm and 0.73–0.28 ppm respectively. Studies of degradation of Methidathion and Trichlorfon have been made using 1 ppm for Methidathion and 0.1 ppm for Trichlorfon. Both insecticides were degradated gradually until 96‐h. Results show that Methid…
Sulfonation of Triphenylphosphines and Separation of Sulfonated Triphenylphosphines by Crystallization and Solvent Extraction
2007
Abstract The effect of sulfonation conditions on the formation of sulfonated triphenylphosphines and their separation from the post‐reaction mixture, containing concentrated sulphuric acid, was studied. The solvent extraction was found to be a suitable technique to separate sulfonated triphenylphosphines from concentrated sulphuric acid, and the purity and yield was higher than obtained by crystallization from various solvents. Tributyl phosphate was a suitable extractant. Sodium salts of sulfonated triphenylphosphines could then be recovered as precipitates by treating the organic phase with the sodium hydroxide solution and separation by crystallization. The solvent extraction simplified …
Effect of hydrothermal time on the forming specific morphology of YPO4:Eu3+ nanoparticles for dedicated luminescent applications as optical markers
2023
A way to control the desired shape and microstructure of YPO4:Eu3+ nanoparticles through the precipitation method followed by a hydrothermal treatment is reported. This method is useful for achieving very high control over the YPO4:Eu3+ formation process with the selection of appropriate synthesis parameters. In detail, the autoclave processing time allows control of the shape and size of nano-needle-shaped particles independently in both directions, as confirmed by X-ray powder diffraction, FT-IR Spectroscopy and Electron Transmission Microscopy. In order to analyse the effect of the nanoparticles’ surroundings on the excitation and relaxation processes of luminescent ions, Eu3+ ion was us…
Novel path to apoptosis: small transmembrane pores created by staphylococcal alpha-toxin in T lymphocytes evoke internucleosomal DNA degradation.
1994
Peripheral-blood human T lymphocytes were treated with Staphylococcus aureus alpha-toxin. Membrane permeabilization was assessed by measuring efflux of K+ and Rb+ and influx of Na+, Ca2+, and propidium iodide. Cellular ATP and [3H]thymidine incorporation following lectin stimulation were measured as parameters for cell viability. Internucleosomal cleavage characteristic of programmed cell death was assessed by agarose gel electrophoresis and by quantifying low-molecular-weight, [3H]thymidine-labeled DNA fragments. Nanomolar concentrations of alpha-toxin evoked protracted, irreversible ATP depletion in both activated and resting T lymphocytes. Toxin-damaged cells also lost their ability to i…
Cytocidal effects of Escherichia coli hemolysin on human T lymphocytes.
1993
Escherichia coli hemolysin is the prototype of a large family of pore-forming toxins produced by gram-negative organisms. Besides its known cytotoxic activities against granulocytes, monocytes, endothelial cells, and renal epithelial cells, we now demonstrate that the toxin potently kills human T lymphocytes. Evidence based on different and independent approaches indicates that lymphocidal activity is due to formation of transmembrane pores. Additionally, cells prestimulated with phytohemagglutinin respond to low doses of E. coli hemolysin with DNA fragmentation similar to that observed in cells undergoing programmed cell death. Kinetic considerations lead us to conclude that DNA degradatio…
Influence of organophosphate poisoning on human dendritic cells.
2013
Organophosphourus compounds (OPC, including nerve agents and pesticides) exhibit acute toxicity by inhibition of acetylcholinesterase. Lung affections are frequent complications and a risk factor for death. In addition, epidemiological studies reported immunological alterations after OPC exposure. In our experiments we investigated the effects of organophosphourus pesticides dimethoate and chlorpyrifos on dendritic cells (DC) that are essential for the initial immune response, especially in the pulmonary system. DC, differentiated from the monocyte cell line THP-1 by using various cytokines (IL-4, GM-CSF, TNF-α, Ionomycin), were exposed to organophosphourus compounds at different concentrat…
Interferons increase cell resistance to Staphylococcal alpha-toxin.
2007
ABSTRACTMany bacterial pathogens, includingStaphylococcus aureus, use a variety of pore-forming toxins as important virulence factors. Staphylococcal alpha-toxin, a prototype β-barrel pore-forming toxin, triggers the release of proinflammatory mediators and induces primarily necrotic death in susceptible cells. However, whether host factors released in response to staphylococcal infections may increase cell resistance to alpha-toxin is not known. Here we show that prior exposure to interferons (IFNs) prevents alpha-toxin-induced membrane permeabilization, the depletion of ATP, and cell death. Moreover, pretreatment with IFN-α decreases alpha-toxin-induced secretion of interleukin 1β (IL-1β)…
Autophagy-Dependent Anticancer Immune Responses Induced by Chemotherapeutic Agents in Mice
2011
Antineoplastic chemotherapies are particularly efficient when they elicit immunogenic cell death, thus provoking an anticancer immune response. Here we demonstrate that autophagy, which is often disabled in cancer, is dispensable for chemotherapy-induced cell death but required for its immunogenicity. In response to chemotherapy, autophagy-competent, but not autophagy-deficient, cancers attracted dendritic cells and T lymphocytes into the tumor bed. Suppression of autophagy inhibited the release of adenosine triphosphate (ATP) from dying tumor cells. Conversely, inhibition of extracellular ATP-degrading enzymes increased pericellular ATP in autophagy-deficient tumors, reestablished the recr…
New ionic liquid-modified silica gels as recyclable materials for L-proline- or H-Pro-Pro-Asp-NH2-catalyzed aldol reaction
2007
l-proline and the tripeptide H-Pro-Pro-Asp-NH2 (1) have been supported, by adsorption, onto the surface of modified silica gels functionalized with a monolayer of covalently attached 1,2-dimethyl-imidazolium chloride, tetrafluoroborate or hexafluorophosphate ionic moieties, respectively. Three different linkers were used to attach the ionic liquid moiety to the surface of these supports. The resulting materials have been used as catalysts for the aldol reaction between acetone and several substituted benzaldehydes. Good yields and enantioselectivities, comparable to or better than those obtained under homogeneous conditions, were obtained. These materials are easily recovered by filtration,…