Search results for "phosphate"
showing 10 items of 1874 documents
Simultaneous Endo- and Exo-Complex Formation of Pyridine[4]arene Dimer with Neutral and Anionic Guests
2017
The formation of complexes between hexafluorophosphate (PF6−) and tetraisobutyloctahydroxypyridine[4]arene has been thoroughly studied in the gas phase (ESI‐QTOF‐MS, IM‐MS, DFT calculations), in the solid state (X‐ray crystallography), and in chloroform solution (1H, 19F, and DOSY NMR spectroscopy). In all states of matter, simultaneous endo complexation of solvent molecules and exo complexation of a PF6− anion within a pyridine[4]arene dimer was observed. While similar ternary complexes are often observed in the solid state, this is a unique example of such behavior in the gas phase. peerReviewed
Characterization of Rabbit Mesenchymal Cell Attachment on Calcium Phosphate Surface
2014
In the current study, the effect of three different treated surfaces of hydroxyapatite and β-tricalcium phosphate on mesenchymal cell attachment has been investigated. Calcium phosphate powders have been synthesized, uniaxially pressed, polished and sintered. Mesenchymal cells have been seeded onto unpolished, polished and polished-thermally etched ceramic samples. The ceramic samples have been characterized by XRD, FTIR and SEM. Results have shown that the best cell attachment and morphology are on the unpolished surface indicating that relatively rough surface is better for cell application.
Fe and Zn co-substituted beta-tricalcium phosphate (β-TCP): Synthesis, structural, magnetic, mechanical and biological properties
2020
This work was supported by the European Social Fund under the No. 09.3.3- LMT-K-712 “Development of Competences of Scientists, other Researchers and Students through Practical Research Activities” measure. AK would like to express sincere gratitude for Fellowship administrated by The Japan Society for the Promotion of Science (JSPS). Fellow’s ID No.: L12546. Authors are grateful to R. Vargalis (Vilnius University) for taking SEM images. © 2020. This work is licensed under a CC BY-NC-ND license.
Uranium speciation in plants
2002
The chemical characterization of the radionuclide species is essential for a reliable assessment of the migration of radionuclides and heavy metals into the geological and biological environment on the load pathway soil - plant - animal - human. Only a few is known about the speciation of uranium in plants. Therefore we investigate the change of speciation during the transfer of uranium from initial solution into plant. Various plants (lupins, dandelion e.g.) were grown in an agricultural test field and in the laboratory on contaminated soils (up to concentration of 1g U/kg soil) and as hydroponics in the uranium containing solutions (uranium concentration: 10-5 M - 10-2 M, pH: 3 - 8). For …
Enrichment and activation of smectite-poor clay
2011
A new method of smectite clay enrichment has been developed. The method is based on dispersing clay in a phosphate solution and sequential coagulation. The product of enrichment is characterized with X-ray powder diffraction, wavelength dispersive X-ray fluorescence spectrometry, differential thermal analysis and thermogravimetry. Sorption of methylene blue and hexadecylpyridinium bromide on raw and purified clays was studied.
Redox modulation of Rubisco conformation and activity through its cysteine residues
2008
Treatment of purified Rubisco with agents that specifically oxidize cysteine-thiol groups causes catalytic inactivation and increased proteolytic sensitivity of the enzyme. It has been suggested that these redox properties may sustain a mechanism of regulating Rubisco activity and turnover during senescence or stress. Current research efforts are addressing the structural basis of the redox modulation of Rubisco and the identification of critical cysteines. Redox shifts result in Rubisco conformational changes as revealed by the alteration of its proteolytic fragmentation pattern upon oxidation. In particular, the augmented susceptibility of Rubisco to proteases is due to increased exposure…
Complexation of Uranium by Cells and S-Layer Sheets of Bacillus sphaericus JG-A12
2005
ABSTRACT Bacillus sphaericus JG-A12 is a natural isolate recovered from a uranium mining waste pile near the town of Johanngeorgenstadt in Saxony, Germany. The cells of this strain are enveloped by a highly ordered crystalline proteinaceous surface layer (S-layer) possessing an ability to bind uranium and other heavy metals. Purified and recrystallized S-layer proteins were shown to be phosphorylated by phosphoprotein-specific staining, inductive coupled plasma mass spectrometry analysis, and a colorimetric method. We used extended X-ray absorption fine-structure (EXAFS) spectroscopy to determine the structural parameters of the uranium complexes formed by purified and recrystallized S-laye…
Synthesis and preliminary in vivo evaluation of well-dispersed biomimetic nanocrystalline apatites labeled with positron emission tomographic imaging…
2015
In recent years, biomimetic synthetic apatite nanoparticles (AP-NPs), having chemical similarity with the mineral phase of bone, have attracted a great interest in nanomedicine as potential drug carriers. To evaluate the therapeutic perspectives of AP-NPs through the mechanisms of action and organs they interact with, the noninvasive monitoring of their in vivo behavior is of paramount importance. To this aim, here the feasibility to radiolabel AP-NPs ("naked" and surface-modified with citrate to reduce their aggregation) with two positron emission tomographic (PET) imaging agents ([F-18]NaF and Ga-68-NO(2)AP(BP)) was investigated. [F-18]NaF was used for the direct incorporation of the radi…
Synergistic Anticancer Therapy by Ovalbumin Encapsulation-Enabled Tandem Reactive Oxygen Species Generation
2020
Abstract The anticancer efficacy of photodynamic therapy (PDT) is limited due to the hypoxic features of solid tumors. We report synergistic PDT/chemotherapy with integrated tandem Fenton reactions mediated by ovalbumin encapsulation for improved in vivo anticancer therapy via an enhanced reactive oxygen species (ROS) generation mechanism. O2 .− produced by the PDT is converted to H2O2 by superoxide dismutase, followed by the transformation of H2O2 to the highly toxic .OH via Fenton reactions by Fe2+ originating from the dissolution of co‐loaded Fe3O4 nanoparticles. The PDT process further facilitates the endosomal/lysosomal escape of the active agents and enhances their intracellular deliv…
Reversible inhibition of CO2fixation by ribulose 1,5-bisphosphate carboxylase/oxygenase through the synergic effect of arsenite and a monothiol
2013
The activity of the photosynthetic carbon-fixing enzyme, ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), is partially inhibited by arsenite in the millimolar concentration range. However, micromolar arsenite can fully inhibit Rubisco in the presence of a potentiating monothiol such as cysteine, cysteamine, 2-mercaptoethanol or N-acetylcysteine, but not glutathione. Arsenite reacts specifically with the vicinal Cys172-Cys192 from the large subunit of Rubisco and with the monothiol to establish a ternary complex, which is suggested to be a trithioarsenical. The stability of the complex is strongly dependent on the nature of the monothiol. Enzyme activity is fully recovered through …