Formation Of Phosphoric Acid Research Articles

Ultrathin membranes formation via the layer by layer self-assembly of carbon nanotubes-based inorganics as high temperature proton exchange membranes

Layered membranes could be prepared with the layer by layer (LBL) self-assembly technique and they showed the wide application in the field of energy storage and transformation. The aim of this research is to develop high temperature proton exchange membranes (PEMs) through introducing carbon nanotube (CNT) and CNT-based inorganics into polymer systems of polyurethane (PU) and chitosan (CS). Successful formation of the ultrathin and conductive membranes through the alternate deposition of PU as polycations, CS and CNT-based inorganics as polyanions has been demonstrated by the identification of components and structural characterizations of fourier transform infrared spectra, scanning electron microscope, etc. Phosphoric acid (PA) molecules were combined with the formation of PA doped membranes while the prepared LBL membranes were immersed into PA solutions through the formed intermolecular hydrogen bonds. Besides PA conducting protons, the decreased proton conduction resistance owing to the multilayered structure could contribute to proton conductivity of PA doped membranes. Specifically, (PU/CNT-CdTe/PU/CS)150/60%PA membranes exhibited the maximum proton conductivity of 6.82 × 10−2 S/cm at 150 °C with an activation energy of 22.9 kJ/mol. The results revealed that CNT-based inorganics showed the potential to function as efficient proton carriers for the preparation of high temperature PEMs. Furthermore, the LBL self-assembly technique could provide a promising strategy to construct the ultrathin and layered membrane electrolytes.

Constructing multilayered membranes with layer-by-layer self-assembly technique based on graphene oxide for anhydrous proton exchange membranes

Layer-by-layer (LBL) self-assembly technique could nanoscopically construct the layered membranes and it has attracted more attention in the field of bionics, clean energy and microelectronics. The aim of this research to develop the multilayered membranes with the ordered deposition of components using LBL self-assembly technique. Successful preparation of anhydrous proton exchange membranes (PEMs) based on graphene oxide (GO) as polyanions, polyurethane (PU) and poly(diallyldimethylammonium chloride) (PDDA) as polycations have been demonstrated by identification of the ordered distribution of components and compact structure. While the prepared membranes were immersed into phosphoric acid (PA) solution, PA molecules were combined with the formation of PA doped membranes. In spite of PA dominating the proton conduction, the decreased proton conduction resistance is revealed from the lower activation energy owing to the multilayered structure. Specifically, the proton conductivity of 1.83 × 10−1 S/cm at 150 °C was obtained for (PU/GO/PDDA/GO)200/60%PA membranes. Moreover, the proton conductivity stability measurement demonstrated the component and mechanical stability, showing 1.47 × 10−1 S/cm at 120 °C and 1.83 × 10−1 S/cm at 140 °C. The result revealed that LBL self-assembly technique could provide a promising strategy to prepare multilayered membranes as membrane electrolytes using in high temperature proton exchange membrane fuel cells.

Surface modification of CoCr alloy using varying concentrations of phosphoric and phosphonoacetic acids: albumin and fibrinogen adsorption, platelet adhesion, activation, and aggregation studies.

CoCr alloy is commonly used in various cardiovascular medical devices for its excellent physical and mechanical properties. However, the formation of blood clots on the alloy surfaces is a serious concern. This research is focused on the surface modification of CoCr alloy using varying concentrations (1, 25, 50, 75, and 100 mM) of phosphoric acid (PA) and phosphonoacetic acid (PAA) to generate various surfaces with different wettability, chemistry, and roughness. Then, the adsorption of blood plasma proteins such as albumin and fibrinogen and the adhesion, activation, and aggregation of platelets with the various surfaces generated were investigated. Contact angle analysis showed PA and PAA coatings on CoCr provided a gradient of hydrophilic surfaces. FTIR showed PA and PAA were covalently bound to CoCr surface and formed different bonding configurations depending on the concentrations of coating solutions used. AFM showed the formation of homogeneous PA and PAA coatings on CoCr. The single and dual protein adsorption studies showed that the amount of albumin and fibrinogen adsorbed on the alloy surfaces strongly depend on the type of PA and PAA coatings prepared by different concentrations of coating solutions. All PA coated CoCr showed reduced platelet adhesion and activation when compared to control CoCr. Also, 75 and 100 mM PA-CoCr showed reduced platelet aggregation. For PAA coated CoCr, no significant difference in platelet adhesion and activation was observed between PAA coated CoCr and control CoCr. Thus, this study demonstrated that CoCr can be surface modified using PA for potentially reducing the formation of blood clots and improving the blood compatibility of the alloy.

Effect of TiO<sub>2</sub> and SiO<sub>2</sub> on Surface Reactivity of Calcium Phosphate Glasses in Simulated Body Fluid

This study compares the in vitro behaviour in SBF of glasses from two different systems, TiO2-CaO-P2O5 and SiO2-CaO-P2O5 with the same TiO2 and SiO2 molar content, in order to evaluate the effect of TiO2 and SiO2 on the surface reactivity of those glasses. The glass formation regions in both systems were observed for compositions with less than 40 mol% TiO2 and 40 mol% SiO2, respectively. Four glasses with similar TiO2 and SiO2 molar contents have been selected for comparison. These glasses are equimolar in CaO and P2O5 with TiO2 or SiO2 varying from 4 to 33 mol %. Powder glasses were immersed in Simulated Body Fluid (SBF) and kept at 37°C for different times, up to 14 days. Surfaces were observed by Scanning Electron Microscopy (SEM) and specimen ion leaching to SBF was studied by Inductively Coupled Plasma (ICP) spectroscopy. Preliminary spectroscopic studies by Raman were performed to identify the structure of the glasses. For glasses of the SiO2-CaO-P2O5 system a significant dissolution of all ions was observed together with the formation of phosphoric acid. In opposition, the immersion of TiO2-CaO-P2O5 glasses produced a small Ca consumption and stable Ti and P concentrations, indicating the formation of a Ca-P rich layer on these glasses. The observed differences in the dissolution behaviour are tentatively explained in terms of the glass structures obtained by spectroscopy.

Phosphine and methylphosphine production by simulated lightning—a study for the volatile phosphorus cycle and cloud formation in the earth atmosphere

Phosphine (PH 3 ), was recently found worldwide even in the remote atmosphere (Naturwissenschaften83(1996a)131; Atmos. Environ. 37(2003)24 29). It is of interest to find natural mechanisms which could produce phosphine gas and drive a volatile link of the atmospheric phosphorus cycle and the formation of phosphoric acid as possible condensation nuclei for clouds. Here, we report on simulated lightning exposing sodium phosphate in a reducing medium (methane model atmosphere or organic matter) for 5 s to a spark induced by microwave. The gas product analyzed by gas chromatography contained phosphine (yield up to 0.6 g kg −1 phosphate P) and methylphosphine (CH 3 )PH 2 (yield up to 0.02 g kg −1 phosphate P). We suggest a plasma-chemical formation mechanism where organic compounds or methane or secondary hydrogen thereof reduce phosphate to phosphine of which a small fraction can subsequently react with methyl radicals to form methylphosphine. A small yield of 6 mg phosphine per kg phosphate P was even obtained in methane free medium, by simple plasmatic recombination of inorganic phosphorus. We believe that methane and hydrogen are useful model substances of pyrolytic gases with high reducing power which may form if lightning strikes biomass, soil and aerosol. These results suggest evidence that phosphine and methylphosphine (detectable in the field by intense garlic odor) are produced when atmospheric lightning strikes the ground or aerosol which is containing oxidized forms of phosphorus and chemical reductants. Additional reviewed data show that laboratory lightning was able to reduce a much more significant portion of phosphate to phosphite (up to 25% yield), methylphosphonic acid (up to 8.5% yield) and traces of hypophosphite in a matter of seconds.

Effect of ethylphosphate on azobenzene-containing thermotropic liquid-crystalline polymers

A new series of liquid-crystalline polymers with azobenzene mesogens and an even number of methylene spacers along with phosphorus heterogeneity were synthesized. The structures of the monomers and polymers were characterized with various spectral techniques. The thermal analyses were performed with thermogravimetric analysis and differential scanning calorimetry (DSC). The formation of the liquid-crystalline phase was confirmed with hot-stage optical polarizing microscopy. All the polymers exhibited grainy and nematic textures during melting; this was confirmed by DSC analysis. The char yield of the polymers was quite high and was related to the formation of phosphoric acid. The glass-transition temperature, melting temperature, and isotropization temperature were quite low. The reduction in the transition temperature could be attributed to the incorporation of the phosphorus heterogeneity and pendant ethyl group. Molecular modeling studies supported the experimental data obtained. The suitability of these polymers for optical data storage was studied with ultraviolet spectroscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 455–462, 2004

801. The radiolysis of tri-n-alkyl phosphates

Electron irradiation of trialkyl phosphates leads to the corresponding dialkyl hydrogen phosphate as a major product, the absolute yield decreasing in the series trimethyl to tripentyl ester. Yields of the respective monoalkyl dihydrogen phosphates are less by ten-fold and formation of phosphoric acid is negligible. Hydrocarbon products include alkenes and alkanes, but the yields do not account quantitatively for the loss of organic fragments in acid formation. Yields of hydrogen generally increase with molecular weight of the ester. These results are lnterpreted in terms of reactions involving the parent moleculeion. There is mass-spectral evidence that organic phosphate ions can undergo simple rearrangement accompanied by fragmentation of the alkyl chain; in the liquid state the latter reaction leading to formation of acid phosphate is assumed to compete with other ionic processes leading to hydrogen production. (auth)

The flavor problem of soybean oil. XI. Phytic acid as an inactivating agent for trace metals

SummaryPhytic acid, a natural constituent of cereal grains and oilseeds, is shown to be highly effective in the control of metallic contamination in edible oils. Phytic acid added to regularly processed edible oils at the 0.01% level has shown a marked improvement in the organoleptic and oxidative stability of these oils.We could not establish whether the mode of action of phytic acid was the result of the direct formation of insoluble phytate salts, or the breakdown of phytic acid with the formation of phosphoric acid which would serve as the active agent. Phytic acid solutions all contained some free phosphoric acid. Most phytic acid samples darkened with age and showed a progressive increase in the amount of free phosphoric acid. To be effective, it was necessary to add phytic acid prior to the deodorization process.Evidence is presented to show that a large part of the synergistic effects of many activators can be explained by metallic inactivation. It is suggested that much of the antioxidant effect observed for rice bran, oat “flour”, and cereal brans could be the result of metal inactivation by the phytic acid present in these materials.

TREATMENT OF CANCER WITH THYMUS EXTRACT

ABSTRACT To the Editor: —Work by Walter Jones (Concerning the Enzyme of the Thymus Gland, Ztschr. f. physiol. Chem. 41:101, 1904) showed that the thymus gland contains a soluble enzyme which attaches to the nucleoproteins of the gland when these are separated with acetic acid and dissolved in sodium carbonate. In this manner he was able to separate it from the soluble constituents of the gland and so determine more accurately the products of decomposition that are formed through its action. He found that at body temperature, and in the concentration in which it exists in the gland, the enzyme rapidly decomposes the nucleoproteins by the formation of phosphoric acid and xanthine bases. These xanthine bases differ from those that are formed as the result of the action of boiling acids on thymic nucleic acids. This proteolytic enzyme differs from trypsin in that it is most active in acid liquids