Search results for "thermal treatment"

showing 10 items of 146 documents

Effects of thermal treatments in controlled atmosphere on the Ce oxidation state in Ce-Ti-Eu doped SiO2 sol-gel glasses

2011

We report an experimental study by optical absorption, photoluminescence and Raman spectroscopies of the modifications induced on Ce–Ti-Eu doped SiO2 glasses by thermal treatments in controlled atmosphere. Samples with Ce content varying up to 5,000 part per million by weight (ppm) and with Ti and Eu content fixed at 40 and 300 ppm respectively, have been investigated. The treatments were done in inert atmosphere of He and in O2 atmosphere at 390 C and 100 bar. Our experiments show that only Ce4? ions are affected by He treatments, whereas both Ce4? and Ce3? ions are affected by O2 treatments. The obtained results are interpreted on the basis of microstructural changes induced by the therma…

Settore FIS/01 - Fisica SperimentaleSilica optical properties thermal treatments
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EXTENDED VALIDATION OF DYNAMIC IRREVERSIBLE THERMOPORATION: A NOVEL THERMAL PROCESS FOR MICROBIAL INACTIVATION

2017

A novel thermal treatment for microorganism inactivation, characterized by a very rapid temperature increase (up to 30C/s) and a low final temperature (up to 65C) maintained for a relatively short holding time, has been recently presented and tested by the authors, showing microbial load reduction greater than 5 log units against several common bacteria and yeasts. With the aim of extending the possible use of the new thermal treatment to a wider microorganisms class, in this work the dynamic irreversible thermoporation (DIT) treatment was further tested on a well-known thermoresistant strain, the Enterococcus hirae: The results of these new experimental tests confirmed the reliability of t…

Settore ING-IND/08 - Macchine A FluidoSettore MED/42 - Igiene Generale E ApplicataSettore ING-IND/13 - Meccanica Applicata Alle MacchineMicroorganisms inactivation thermal treatment beverages Enterococcus hirae SEM analysis
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Cathodoluminescence decay kinetics in Ge+, Si+, O+ implanted SiO2 layers

2003

Abstract Cathodoluminescence spectral shapes and respective band decay times show no similarity between luminescence centers in different crystal and amorphous modifications of SiO2 and GeO2. On the other hand, the additionally produced red luminescence centers (650 nm) by oxygen implantation into SiO2 layers are of the same nature as in stoichiometric SiO2 and are attributed to the non-bridging oxygen hole center (NBOHC). On the other hand, the elevated blue luminescence (460 nm) in Si implanted SiO2 belongs to the silicon related oxygen deficient center (SiODC) as in stoichiometric layers also. Ge implantation into SiO2 and thermal post-annealing leads to a huge violet luminescence (400 n…

SiliconRadiochemistryAnalytical chemistrychemistry.chemical_elementnanoclusterCathodoluminescenceThermal treatmentCondensed Matter PhysicsOxygenElectronic Optical and Magnetic MaterialsAmorphous solidCrystalchemistryCathodoluminesenceMaterials ChemistryCeramics and Compositesion implantationExponential decayLuminescenceglassJournal of Non-Crystalline Solids
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Water and temperature contribution to the structuration of starch matrices in the presence of flavour

2015

The effect of hydrothermal treatments and flavours addition on starch structure and its physical properties were studied. Native wheat starch was treated at 2 different hydrations (water-starch ratios: 50/50 and 80/20 g w/w) and temperatures (65 and 85 °C) in the presence of flavours (ethyl hexanoate and 2-hexanone). The freshly prepared samples were subjected to DSC and flavour analysis. Flavour inclusion complex could not be detected by DSC, however the result of flavour analysis proved that there were flavours interactions with starch. Both ethyl hexanoate and 2-hexanone interacted with starch at similar rates. The highest flavour loss was found in the samples at high hydration and heate…

Starch structureWheat starchEthyl hexanoateTraitement hydrothermiqueHydrothermal treatmentSAXSArôme[SDV.IDA] Life Sciences [q-bio]/Food engineeringAmidon de bléHexanoate d’éthyleRVAStructure d’amidonPartial gelatinisationWAXSAmidon partiellement gélatiniséFlavour2-Hexanone
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Steviol glycosides and bioactive compounds of a beverage with exotic fruits and Stevia rebaudiana Bert. as affected by thermal treatment

2020

The aim of this study was to investigate the effects of thermal processing on physicochemical properties, steviol glycosides, bioactive compounds, and antioxidant capacity degradation of a beverage based on exotic fruit juices, orange juice, açaí, and oat and sweetened with Stevia rebaudiana water extracts at different concentrations. The experimental design comprised a response surface methodology according to a central composite face-centered design. The variable ranges were 60–99°C, 0.25–15 min, 0–2.5% Stevia percentage. This design was used to determine the optimal thermal processing-Stevia concentration in order to obtain the best retention of bioactive compounds and physicochemical pr…

Steviollcsh:TX341-641Thermal treatmentphysicochemical properties01 natural scienceschemistry.chemical_compound0404 agricultural biotechnologyFood sciencethermal processingsteviol glycosideschemistry.chemical_classificationbioactive compoundslcsh:TP368-456stevia rebaudiana bertoni010401 analytical chemistryGlycoside04 agricultural and veterinary sciences040401 food science0104 chemical sciencesStevia rebaudianaAntioxidant capacitylcsh:Food processing and manufacturechemistrytotal antioxidant capacityexotic fruitslcsh:Nutrition. Foods and food supplyFood ScienceInternational Journal of Food Properties
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Rapid and eco-friendly synthesis of graphene oxide-silica nanohybrids

2014

The increasing interest in Graphene oxide (GO) is due to many issues: the presence of both sp2-conjugated atoms and oxygen-containing functional groups provides a strong hydrophilicity and the possibility to further functionalize it with other molecules (i.e. π-π interactions covalent attachment etc.) [1]. Furthermore since the GO is biocompatible and noncytotoxic many studies have been recently focused on the development of GO-based nanodevices for bioimaging DNA detection drug delivery. Due to their low cytotoxicity and large internal surface area silica nanoparticles have been taken into account as promising material for biolabeling and drug loading/delivery. Particular consideration has recently been demonstrated for GO-silica composites because of the potentialities for electrical applications their chemical inertia and stability toward ions exposure. The possibility to combine the extraordinary properties of GO and silica offers several advantages for the realization of nanoprobes for biological applications and of biosensor [12]. The strategy for the fabrication of GO-nanosilica nanohybrids can be schematized as follows: (i) synthesis of GO by oxidizing graphite powder with the method described by Marcano et al. [3] (ii) Preparation of oxygen-loaded silica nanoparticles by thermal treatments in controlled atmosphere in order to induce high NIR emission at 1272 nm from high purity silica nanoparticles. (iii) preparation of GrO-silica nanohybrid films via rapid solvent casting in water. The nanohybrids were tested by XPS FTIR Raman analysis UV photoluminescence analysis TGA Zeta potential measurements electrical tests AFM and SEM. Several nanohybrids were prepared by combining two different typologies of GO and two different samples of silica.
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Experimental Evaluation of a New Thermal Process for Microorganisms Inactivation

2015

A new thermal process for the inactivation of microorganisms in beverages has been studied and is presented in this paper. The treatment, not yet studied in the scientific literature, mainly consists of a thermal shock characterized by temperature increases up to 30°C/s, with final temperatures up to 65°C. This study presents the first experimental results obtained by the application of the new thermal treatment, with different combinations of the process parameters (rate of temperature rise, final temperature and holding time), on separate suspensions of Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Listeria innocua and Candida albicans. The required rapid temperature in…

Thermal shockMaterials sciencebusiness.industryGeneral Chemical EngineeringBeverage industryMicroorganismPasteurizationThermal treatmentContaminationPulp and paper industrylaw.inventionBiotechnologylawScientific methodAseptic processingbusinessFood ScienceJournal of Food Process Engineering
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Covalent and Ionic Functionalization of HLN Layered Perovskite by Sonochemical Methods

2017

We describe the functionalization of the layered perovskite HLaNb2O7 with n-propanol, n-decanol, 3-mercaptopropyl-trimethoxysilane, imidazole, n-decylamine, and histamine. The use of sonication is found to significantly improve the reaction yield and to reduce the reaction time, compared to conventional thermal treatment under reflux. The obtained intercalates are thoroughly characterized through the use of several complementary experimental techniques (scanning electron microscopy, IR spectroscopy, X-ray diffraction, thermogravimetric analysis, magic-angle spinning NMR), clarifying their structure and chemical bonding. The implications for the design of inorganic–organic composite material…

Thermogravimetric analysisChemistryInfrared spectroscopyIonic bonding02 engineering and technologyThermal treatment010402 general chemistry021001 nanoscience & nanotechnology01 natural sciences0104 chemical sciencesInorganic ChemistryChemical bondChemical engineeringCovalent bondOrganic chemistrySurface modificationPhysical and Theoretical Chemistry0210 nano-technologyPerovskite (structure)
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Thermo-oxidative ageing of an organo-modified clay and effects on the properties of PA6 based nanocomposites

2013

a b s t r a c t In this work a careful investigation on the degradation of an organically modified montmorillonite sample (Cloisite 15A) thermal treated under different atmospheres, namely nitrogen, air and oxygen enriched atmosphere was performed. The exposure time of the thermal treatment ranged between 5 and 300 min. The chemical composition evolution as function of the thermal treatment conditions of the clay organic modifier was monitored by means of combined thermogravimetry/Fourier transform infrared spectroscopy (TGA-FTIR). Moreover, the morphological behaviour of treated Cloisite 15A sam- ples as function of the time and of the decomposition atmosphere was investigated by X-ray dif…

Thermogravimetric analysisMaterials scienceNanocompositeMontmorillonite Organic modifier Degradation Nanocomposites TGA–FTIRThermal treatmentCondensed Matter PhysicsThermogravimetrychemistry.chemical_compoundMontmorillonitechemistryLimiting oxygen concentrationPhysical and Theoretical ChemistryFourier transform infrared spectroscopyComposite materialThermal analysisInstrumentation
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Synthesis of Dirhodium(II) Complexes with Several Cyclometalated Thienylphosphines

2006

The thermal reaction of dirhodium tetraacetate with tris(3-thienyl)phosphine (3TP), diphenyl(3-thienyl)phosphine (3TPPh2), and diphenyl(2-thienyl)phosphine (2TPPh2) gives rise to mono-cyclometalated and bis-cyclometalated compounds; the latter can have a head-to-head (H−H) or head-to-tail (H−T) configuration. Bis-cyclometalated compounds with H−T configuration can be prepared in high yield under photochemical conditions or by combining irradiation with subsequent thermal treatment in acetic acid. The reactivity order of aromatic ring C−H activation is phenyl < 2-thienyl ≪ 3-thienyl, which leads to a selective activation of the thienyl ring. Thus, only one mono-cyclometalated compound is obt…

TrisOrganic ChemistryThermal treatmentRing (chemistry)PhotochemistryMedicinal chemistryInorganic Chemistrychemistry.chemical_compoundAcetic acidchemistryYield (chemistry)Reactivity (chemistry)IrradiationPhysical and Theoretical ChemistryPhosphineOrganometallics
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