Search results for "solution"

showing 10 items of 5638 documents

Preparation and Characterisation of Alendronate-Loaded Chitosan Microparticles Obtained Through the Spray Drying Technique

2009

Microparticles of chitosan (CHT) containing alendronate sodium (AL) were prepared in four drug:polymer ratios (1:1, 1:2, 1:4, 1:6) using the spray drying technique. The efficiency of the method was evaluated by determining production yield (about 70 %) and microencapsulation efficiency, which was almost 100 % in the case of all four of the formulations studied. Particles had a mean size of between 3.6 and 4.6 microm, and a near-spherical shape. The formulations with the highest content of AL (drug:polymer ratio 1:1 and 1:2) showed an asymmetrical distribution of particles, which were larger in size, and had a higher proportion of irregular particles than the other formulations. FT-IR analys…

Thermogravimetric analysisMaterials scienceSpectrophotometry InfraredSurface PropertiesBiological AvailabilityChitosanchemistry.chemical_compoundDifferential scanning calorimetryPolymer ratioDrug DiscoveryHumansThermal stabilityParticle SizeDissolutionchemistry.chemical_classificationChitosanDrug CarriersAlendronateCalorimetry Differential ScanningPolymerHydrogen-Ion ConcentrationMicrosphereschemistrySpray dryingThermogravimetryMicroscopy Electron ScanningNuclear chemistryMedicinal Chemistry
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Facile Fabrication of Natural Polyelectrolyte-Nanoclay Composites: Halloysite Nanotubes, Nucleotides and DNA Study

2020

Complexation of biopolymers with halloysite nanotubes (HNTs) can greatly affect their applicability as materials building blocks. Here we have performed a systematic investigation of fabrication of halloysite nanotubes complexes with nucleotides and genomic DNA. The binding of DNA and various nucleotide species (polyAU, UMP Na2, ADP Na3, dATP Na, AMP, uridine, ATP Mg) by halloysite nanotubes was tested using UV-spectroscopy. The study revealed that binding of different nucleotides to the nanoclay varied but was low both in the presence and absence of MgCl2, while MgCl2 facilitated significantly the binding of longer molecules such as DNA and polyAU. Modification of the nanotubes with DNA an…

Thermogravimetric analysisNanotubeclay/polymer compositesPharmaceutical Sciencehalloysite nanotubesengineering.materialHalloysiteArticleAnalytical Chemistrylcsh:QD241-441chemistry.chemical_compoundlcsh:Organic chemistryDrug DiscoveryNucleotidePhysical and Theoretical ChemistryDissolutionMechanical Phenomenachemistry.chemical_classificationNanotubesNucleotidesOrganic ChemistrySorptionDNAnucleotidenanoclay self-assemblyPolyelectrolytesPolyelectrolytenanoclayChemical engineeringchemistryUltrasonic WavesChemistry (miscellaneous)engineeringMolecular MedicineClayThermodynamicsDNAMolecules
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A new approach to the synthesis of intermetallic compounds: mild synthesis of submicrometric CoxMy (M = Mo, W; x∶y = 3∶1 and 7∶6) particles by direct…

2002

A simple processing route to cobalt–molybdenum and cobalt–tungsten intermetallics (CoxMy, where M = Mo and W, and x∶y = 3∶1 and 7∶6) has been developed, on the basis of the use of precursors resulting from freeze-drying of aqueous solutions of the appropriate common metal salts. The influence of the preparative variables on the outcomes of this procedure is examined. These compounds are prepared as single phases by thermal reduction of amorphous freeze-dried powders under a hydrogen–argon atmosphere (8% H2), followed by slow cooling of the samples. The materials have been characterised by X-ray powder diffraction, metal analysis, scanning electron microscopy and thermogravimetry under an ox…

ThermogravimetryAqueous solutionMaterials scienceScanning electron microscopePowder metallurgySlow coolingMetallurgyMaterials ChemistryIntermetallicGeneral ChemistryPowder diffractionNuclear chemistryAmorphous solidJournal of Materials Chemistry
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Cadmium(II) complexes of cytosine

1990

Complexes of cadmium(II) with cytosine obtained from aqueous or physiological solutions at room temperature are reported. The complexes were characterized by spectroscopic, conductometric,1H-NMR, and13C-NMR measurements and also by thermogravimetry.

ThermogravimetryCadmiumchemistry.chemical_compoundAqueous solutionChemistryInorganic chemistrychemistry.chemical_elementGeneral ChemistryCytosineMonatshefte f�r Chemie Chemical Monthly
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Synthesis of new vanadium–chromium and chromium–molybdenum oxynitrides by direct ammonolysis of freeze-dried precursors

2000

Interstitial vanadium–chromium and chromium–molybdenum oxynitrides in the solid solution series V1 − zCrz(OxNy) and Cr1 − zMoz(OxNy) (z = 0.0, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0) have been obtained by direct ammonolysis of precursors resulting from the freeze-drying of aqueous solutions of the appropriate metal salts. A study of the influence of the preparative variables on the outcomes of this procedure is presented. Compounds in the V1 − zCrz(OxNy) series are prepared as single phases by nitridation at 1073 K, followed by fast cooling of the samples. Compounds in the Cr1 − zMoz(OxNy) series are prepared as nearly single phases by nitridation at different temperatures, optimized for each composi…

ThermogravimetryChromiumchemistryMolybdenumInorganic chemistryMaterials ChemistryVanadiumchemistry.chemical_elementGeneral ChemistryCrystal structureNitridePowder diffractionSolid solutionJournal of Materials Chemistry
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Solubility of some calcium-carboxylic ligand complexes in aqueous solution

1994

Insoluble species were identified in the systems Ca(2+)-hemimellitate, Ca(2+)-1,2,3,4-butanetetracarboxylate and Ca(2+)-citrate, and their solubilities were determined in aqueous solution at T = 25 degrees C. Values of pK(s0) were obtained for the species CaLH (L = benzene-1,2,3-tricarboxylate or hemimellitate), Ca(2)L (L = 1,2,3,4-butanetetracarboxylate), CaLH and Ca(3)L(2) (L = citrate), together with their dependence on ionic strength. Solid compounds were also characterized by thermogravimetry. The complex formation in solution for the system Na(+) - and Ca(2+)-hemimellitate was studied too.

Thermogravimetrychemistry.chemical_compoundAqueous solutionLigandIonic strengthChemistryInorganic chemistryProtonationQualitative inorganic analysisCarboxylateSolubilityAnalytical ChemistryNuclear chemistryTalanta
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Experimental assessment of reverse electrodialysis in closed loop configuration fed by NH4HCO3-water solutions

2018

Closed loop reverse electrodialysis is a novel technology for converting low-temperature waste heat into electric energy. This innovative heat engine consists of two units: (i) a reverse electrodialysis unit where power is produced exploiting the concentration difference between a diluted and a concentrated salt solution and (ii) a thermally driven regeneration unit where low-grade waste heat is used to re-establish the original salinity gradient between the two salt solutions. Among all the possible salt solutions suitable as working fluid in such application, Thermolytic salts solutions, in particular Ammonium bicarbonate solutions, may be promising thanks to their characteristic thermall…

Thermolytic salts Ammonium Bicarbonate solutions Reverse electrodialysis Heat Engine.
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Research data supporting "Antiferromagnetism and p-type conductivity of non-stoichiometric nickel oxide thin films"

2019

Raw data for the manuscript. The dataset contains the files used for the figures and tables in the Article and its Supporting Information. See the Readme file for a detailed description of the dataset.

Thin FilmsNickel OxideChemical Vapor DepositionAtomic Layer DepositionData_FILESSolution Deposition
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Epistemic and didactic values of the demonstrative process in different cultures: a case study in Geometry with Chinese and Italian students

2011

This paper presents same key findings of the research project conducted by G.R.I.M. of Palermo on the approaches to justification and proof in Geometry by investigating how Chinese and Italian teachers and students taught particular geometrical topics refereed to different epistemic and didactic values related to own culture. It was found that Chinese teachers and students emphasized justification of the proof by a stressed visual verification based on some metarules linked with the structure of their own written language and defined as historical Chinese modus operandi in the Jiuzhang Suanshu. The Italians paid close attention to mathematical proof by a hypoxemic deductive system defined on the Euclide’ Elements. The geometrical problem discussed on the paper was defined and presented as “one problem multiple solution problems” and “one problem multiple changes”. Important aspect of the case study discussed in the paper focus on the mediation of knowledge between Chinese and Italian students involved in multicultural class. According to us these kind of activities can establish possibilities for the students to confront their self with different cultural social and educational prospective of knowledge discovering the power of mathematics as tool of negotiation in multicultural class?Settore MAT/04 - Matematiche Complementari
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Three solutions for a Neumann boundary value problem involving the p-Laplacian

2005

In this note we prove the existence of an open interval ]λ', λ"[ for each λ of which a Neumann boundary value problem involving the p-Laplacian and depending on λ admits at least three solutions. The result is based on a recent three critical points theorem.

Three solutionslcsh:Mathematicsp-LaplacianNeumann problemCritical pointslcsh:QA1-939Le Matematiche
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