Search results for " Silica"

showing 10 items of 418 documents

Determination of the chemical warfare agents Sarin, Soman and Tabun in natural waters employing fluorescent hybrid silica materials

2017

[EN] A novel mesoporous silica material containing boron-dipyrromethene (BODIPY) moieties (I) is employed for the detection of nerve agent simulants (NASs) and the organophosphate nerve or chemical warfare agents (CWAs) Sarin (GB), Soman (GD), and Tabun (GA) in aqueous environments. The reactive BODIPY dye with an optimum positioned hydroxyl group undergoes acylation reactions with phosph(on)ate substrates, yielding a bicyclic ring. Due to aggregation of the dyes in water, the sensitivity of the free dye in solution is very low. Only after immobilization of the BODIPY moieties into the silica substrates is aggregation inhibited and a sensitive determination of the NASs diethyl cyanophosphon…

010402 general chemistry01 natural sciencesFluorescence detectionchemistry.chemical_compoundQUIMICA ANALITICAMaterials ChemistrymedicineOrganic chemistryReactivity (chemistry)Electrical and Electronic EngineeringInstrumentationNerve agentTabunAqueous solutionQuenching (fluorescence)010405 organic chemistryChemistryQUIMICA INORGANICAMetals and AlloysMesoporous silicaCondensed Matter Physics0104 chemical sciencesSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsDiethyl chlorophosphateNerve agent simulantsMesoporous silica materialsBODIPYmedicine.drugNuclear chemistry
researchProduct

Melt inclusions track melt evolution and degassing of Etnean magmas in the last 15 ka

2019

We present major elements compositions and volatiles contents of olivine-hosted melt inclusions from Etna volcano (Italy), which extend the existing database with the aim of interpreting the chemical variability of Etnean magmas over the last 15 ka. Olivine phenocrysts were selected from the most primitive Fall Stratified (FS) eruptive products of picritic composition (Mg# = 67–70, Fo 89–91 ), the Mt. Spagnolo eccentric lavas (Mg# = 52–64, Fo 82–88 ) and among the more recent 2002–2013 eruptive products (Mg# = 33–53, Fo 68–83 ). Crystal fractionation and degassing processes were modeled at temperatures of 1050–1300 °C, pressures <500 MPa, and oxygen fugacity between 1 and 2 log units abo…

010504 meteorology & atmospheric sciencesGeochemistryVolatile contentengineering.material010502 geochemistry & geophysics01 natural sciencesMantle (geology)Mineral redox bufferDegassingGeochemistry and PetrologySilicate melt inclusionPlagioclase0105 earth and related environmental sciencesMelt inclusionsFractional crystallization (geology)OlivineSpinelMelt differentiationGeologyEtna Silicate melt inclusions Volatile contents Melt differentiation Degassing13. Climate action[SDU]Sciences of the Universe [physics]engineeringPhenocrystEtnaGeology
researchProduct

Consolidation of earthen building materials: a comparative study

2019

The consolidation and protection of mud bricks are a challenge in the field of conservation of archeological sites. One of the solutions is represented by the coverage of the entire excavation that assures a protection against mud dissolution. Unfortunately, this is not always feasible, both for economical and practical issues. For these reasons, alternative solutions are needed. In this work, laboratory experimentation has been carried out in order to test the efficacy of some products to slow down the dissolution process and increase the brick toughness. Three typologies of raw materials taken from different outcrops (one from the Republic of Azerbaijan and two from Calabria region, Italy…

010506 paleontologyArcheologyBrickPotassium hydroxide060102 archaeologyWaste managementConsolidation (soil)Alkaline solutions Consolidation Laboratory test Mud bricks06 humanities and the artsRaw material01 natural sciencesSilicatechemistry.chemical_compoundchemistrySodium hydroxideAnthropologyEnvironmental science0601 history and archaeologyDissolutionSettore GEO/09 -Georis. Miner.e Appl.Mineral.-Petrogr. per l'Ambi.ed i B.Cult.Potassium silicate0105 earth and related environmental sciencesArchaeological and Anthropological Sciences
researchProduct

Loading and release of the complex [Pt(DTBTA)(DMSO)Cl]Cl·CHCl3 with the 2,2′-dithiobis(benzothiazole) ligand into mesoporous silica and studies of an…

2018

Abstract Synthetic delivery systems have great potential for overcoming problems associated with systemic toxicity that accompanies chemotherapy with the use of cisplatin and family of platinum anticancer drugs. Mesoporous silicates have been studied in context of drug delivery and drug targeting. In this paper we report the studies of loading and release of a platinum complex, [Pt(DTBTA)(DMSO)Cl]Cl∙CHCl3 (1) where DTBTA = 2,2′-dithiobis(benzothiazole), that was recently synthesized and structurally characterized. Evaluation in vitro of antitumor activity against a human breast cancer cell line (MCF-7) showed a very potent activity of complex(1). Therefore, we thought to incorporate this co…

02 engineering and technologyMesoporous silica010402 general chemistry021001 nanoscience & nanotechnology01 natural sciencesControlled release0104 chemical sciencesInorganic ChemistryAntiproliferative activityControlled releaseLoadingMCM41Platinum(II) complexchemistry.chemical_compoundTargeted drug deliveryBenzothiazolechemistrySettore CHIM/03 - Chimica Generale E InorganicaDrug deliveryMaterials ChemistryPhysical and Theoretical Chemistry0210 nano-technologyCytotoxicityMesoporous materialConjugateNuclear chemistrySettore CHIM/02 - Chimica Fisica
researchProduct

Onset of cohesion in cement paste

2004

It is generally agreed that the cohesion of cement paste occurs through the formation of a network of nanoparticles of a calcium-silicate-hydrate ("C-S-H"). However, the mechanism by which these particles develop this cohesion has not been established. Here we propose a dielectric continuum model which includes all ionic interactions within a dispersion of C-S-H particles. It takes into account all co-ions and counterions explicitly (with pure Coulomb interactions between ions and between ions and the surfaces) and makes no further assumptions concerning their hydration or their interactions with the surface sites. At high surface charge densities, the model shows that the surface charge of…

0211 other engineering and technologiesCementNanoparticleIonic bonding02 engineering and technologyDielectricCSHIonchemistry.chemical_compound021105 building & constructionElectrochemistryGeneral Materials ScienceSurface chargecalcium silicate hydrateCalcium silicate hydrateionic correlationsSpectroscopyMonte Carlo simulation[CHIM.MATE] Chemical Sciences/Material chemistryIonic radiusatomic force microscopySurfaces and Interfaces[CHIM.MATE]Chemical Sciences/Material chemistry021001 nanoscience & nanotechnologyCondensed Matter PhysicsC-S-HcohesionchemistryChemical physics[ CHIM.MATE ] Chemical Sciences/Material chemistryCohesion (chemistry)nanoparticlesAFM0210 nano-technology
researchProduct

Post-tilleyite, a dense calcium silicate-carbonate phase

2019

Scientific reports 9(1), 7898 (2019). doi:10.1038/s41598-019-44326-9

0301 basic medicineMaterials scienceINITIO MOLECULAR-DYNAMICSTRANSFORMATIONSCoordination numberAnalytical chemistrylcsh:MedicineZONEArticle03 medical and health sciencessymbols.namesakechemistry.chemical_compoundRAMAN0302 clinical medicineX-RAY-DIFFRACTIONPhase (matter)HIGH-PRESSUREGALUSKINITElcsh:ScienceCondensed-matter physicsMultidisciplinaryREFINEMENTlcsh:R600MineralogyEQUATION-OF-STATESPURRITE030104 developmental biologyCalcium carbonatechemistryCalcium silicatesymbolsCarbonatelcsh:QRaman spectroscopyddc:600Spurrite030217 neurology & neurosurgeryEarth (classical element)Scientific Reports
researchProduct

Target Transportation of Auxin on Mesoporous Au/SiO2 Nanoparticles as a Method for Somaclonal Variation Increasing in Flax (L. usitatissimum L.)

2017

Development of methods for direct delivery of different bioactive substances into the cell is a promising and intensively approached area of research. It has become a subject of serious research for multidisciplinary team of scientists working in such areas as physics, biology, and biotechnology. Plant calluses were grown on medium supplemented with different nanoparticles to be used as a model for biotechnological research. Gold nanoparticles with mesoporous silica coating were used as hormone carriers, since they possess many of critical properties required for cellular transportation instrument. Some of those properties are great biocompatibility and controlled release of carried molecul…

0301 basic medicinechemistry.chemical_classificationMaterials scienceBiocompatibilitybiologyArticle SubjectNanoparticleNanotechnology02 engineering and technologyMesoporous silica021001 nanoscience & nanotechnologybiology.organism_classificationControlled releaseSomaclonal variation03 medical and health sciences030104 developmental biologychemistryAuxinColloidal goldlcsh:Technology (General):NATURAL SCIENCES:Physics [Research Subject Categories]lcsh:T1-995General Materials SciencePlant hormone0210 nano-technologyJournal of Nanomaterials
researchProduct

Could the Calcium Silicate-Based Sealer Presentation Form Influence Dentinal Sealing? An In Vitro Confocal Laser Study on Tubular Penetration

2021

Dentinal tubule penetration influences root canal treatment sealing. The aim of this study was to compare dentinal penetration of two clinical presentations of silicate-based sealers using confocal laser. Sixty single-rooted human teeth from 50–70 year-old patients extracted for orthodontic/periodontal reasons were used. Canals were prepared using Mtwo system up to 35/0.04, with 5.25% NaOCl irrigation and final irrigation using 17% EDTA. Teeth were randomly assigned into study groups (ni = 20): EndoSequence BC sealer (ES, group 1), BioRoot RCS (BR, group 2); and a control group (nc = 20) with AH Plus (AHP). Root canals were obturated with 35/0.04 gutta-percha (single-cone technique). The sa…

0303 health sciencesmedicine.medical_specialtyChemistrybusiness.industryConfocalRoot canalDentistry030206 dentistryPenetration (firestop)Endodontics03 medical and health scienceschemistry.chemical_compound0302 clinical medicineDentinal Tubulemedicine.anatomical_structureCalcium silicatemedicineGeneral Materials ScienceStatistical analysisPenetration depthbusiness030304 developmental biologyMaterials
researchProduct

Thermomineral waters of Greece: geochemical characterization

2020

75 °C). In terms of pH most results vary from 5.5 to 823 °C) ii) warm (23 40 °C) iii) thermal (40 75 °C) and iv) hyperthermal (&gtfew springs show either very low pH (&lt10) proposing serpentinization processes. Regarding TDS concentrations collected waters can be subdivided into low salinity (up to 1.5 g/L) brackish (up to 20 g/L) and saline (up to 43 g/L). The medium high salinities can be justified by mixing with sea water and/or strong waterrock interaction processes. Isotope composition of O and H ranges from 12.7 to +2.7 ‰ SMOW and from 91 to +12 ‰ SMOW respectively and is generally comprised between the Global Meteoric Water Line and the East Mediterranean Meteoric Water Line. Only few water samples show a positive shift for δ18O possibly related to high temperature waterrock interaction processes. Carbon dioxide (18 997000 μmol/mol) or N2 (1100 989000 μmol/mol) or CH4 (&ltMany geothermal areas of Greece are located in regions affected by Miocene or Quaternary volcanism and in continental basins characterised by elevated heat flow. Moreover the majority of them is found along the coast as well as in islands of the Aegean Sea and thus thermal water is often brackish to saline due to marine intrusion into costal aquifer. In the present study almost 300 thermal and cold mineral water samples were collected along the Hellenic territory with their physicochemical parameters (temperature pH electrical conductivity and Eh) and the amount of bicarbonates (titration with 0.1N HCl) being determined in situ. Additionally gases found either in free or dissolved phase were sampled. Both water and gas samples were analysed at the INGVPa laboratories for major ions (Ion Chromatography) silica (Inductively Coupled Plasma Optical Emission Spectrometry) chemical composition of free and dissolved gases (Gas Chromatography) water isotopes (O and H) and carbon and helium isotopes of free and dissolved gases (Mass Spectrometry). The temperature of the investigated waters ranges from 6.5 to 98°C pH from 1.96 to 11.98 whilst Total Dissolved Solids (TDS) from 0.06 to 43 g/L. Based on the temperature parameter waters can be divided into four groups: i) cold (&lt0.5 913000 μmol/mol) are the prevailing gas species found in the studied sites. The δ13CCO2 values ranged from 20.1 to +8.5 ‰ whilst the isotope ratio of He from 0.21 to 6.71 R/RA.4) suggesting interaction with H2Srich gases or very high pH values (&gtSettore GEO/08 - Geochimica E Vulcanologia
researchProduct

Irradiation effects on the OH-related infrared absorption band in synthetic wet silica.

2007

The effects of b-irradiation on the OH-related infrared (IR) absorption band in synthetic wet silica samples have been investigated by Fourier transform infrared spectroscopy. Depending on the accumulated doses, b-irradiation affects different zones of the IR composite band at about 3670 cm 1 , assigned to the OH stretching modes of silanol groups. These modifications are independent of the original OH content. The results are discussed considering possible radiation-induced changes of the silanol bonding configuration and of the glass network. These are monitored by revealing the IR band a 2260 cm 1 , which is related to the distribution of Si–O–Si bond angle. We have identified the existence of…

Absorption spectroscopyChemistryInfraredPoint defects in silicaAnalytical chemistryInfrared spectroscopyCondensed Matter PhysicsElectronic Optical and Magnetic MaterialsSilanolchemistry.chemical_compoundAbsorption bandMolecular vibrationMaterials ChemistryCeramics and CompositesDynamic properties of vitreous systemsIrradiationFourier transform infrared spectroscopy
researchProduct