Articles de revues : « Sols – Composition »

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Carcaillet, Christopher, et Brigitte Talon. « Aspects taphonomiques de la stratigraphie et de la datation de charbons de bois dans les sols : exemple de quelques sols des Alpes ». Géographie physique et Quaternaire 50, n^o 2 (30 novembre 2007) : 233–44. http://dx.doi.org/10.7202/033091ar.

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RÉSUMÉ Les phénomènes d'enfouissement et de fragmentation des charbons de bois des sols de montagne sont mis en évidence par l'analyse anthracologique et par des datations absolues au14C de quatre profils pédologiques provenant des Alpes françaises. Ces dernières s'avèrent indispensables mais insuffisantes pour comprendre le mode de stratification. Les datations doivent être précédées d'une analyse des assemblages anthracologiques à la fois qualitative (composition taxonomique) et quantitative lorsque les sols sont suffisamment riche en charbons. Le processus de stratification dans les sols n'est pas comparable à celui que l'on observe dans un lac ou une tourbière; les racines, la pédofaune et les processus d'érosion contribuent à créer une vitesse différentielle d'enfouissement des charbon dans les sols. Cela conduit à une stratification dite « en écailles » des charbons appartenant à un même taxon. Les assemblages et les datations permettent d'identifier des phases d'incendies subies par la végétation sur la station MAUR 6 située en moyenne altitude (1770 m). Quant à QUEYRAS 2, en haute altitude (2670 m), il ne semble pas approprié pour révéler, de par sa composition en charbon, différentes phases d'incendies et surtout les plus anciennes; le réseau racinaire mais surtout les alternances de gel-dégel participent à la réduction de taille des fragments dans les sols.

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Dumoulin, Matthieu, Wael Hamd, Elsa Thune, Cyrille Rochas et René Guinebretiere. « In situ time-resolved small-angle X-ray scattering observation of the fractal aggregation process in tin alkoxide polymeric solution ». Journal of Applied Crystallography 49, n^o 2 (10 février 2016) : 366–74. http://dx.doi.org/10.1107/s1600576716000297.

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SnO2 transparent gels have been synthesized from alkoxide precursor in toluene-2-propanol solvents. The chemical reactivity of transition metal alkoxides must be controlled in order to obtain sols and gels. In tin alkoxide based systems, this control can be achieved through complexation by a chelating agent such as acetylacetone. The gelation of the sols has been studied by in situ small-angle X-ray scattering (SAXS) measurements at the European Synchrotron Radiation Facility in Grenoble on the BM02 beamline. After the addition of water, primary particles are created and stick progressively together to form fractal aggregates. The primary particles are continually created during the aggregation process, which causes an evolution of the fractal dimension of the aggregate during gelation. This evolution is similar whatever the chemical composition is, meaning that the aggregation is ruled by one process which has been identified as reaction-limited cluster aggregation. Nevertheless, the final size of the aggregates is dependent on the chemical composition of the sols.

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Смагин, В. П., А. П. Худяков et А. А. Бирюков. « Люминесценция ионов Eu-=SUP=-3+-=/SUP=- в матрице фторированной алюмоиттриевой композиции ». Физика твердого тела 62, n^o 2 (2020) : 274. http://dx.doi.org/10.21883/ftt.2020.02.48879.566.

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The optical spectra of fluorinated yttrium aluminum compositions activated by Eu3+ ions were studied. The compositions were synthesized by thermal decomposition at 800 °C of fluorine-containing complexes of yttrium, europium, and aluminum nitrate, isolated as sols from ethyl acetate (EA). The main phases of the compositions are (Y1-xEux)OF and (Y1-xEux)AlO3. Photoluminescence is associated with 5D1,2 → 7F0,1,2 and 5D0 → 7F0,1,2,3,4 electronic transitions of 4f - electrons of Eu3+ ions, replacing yttrium ions in its oxide and oxyfluoride. The dependences of luminescence on the composition and synthesis conditions of the compositions, the wavelength of the exciting radiation, and other factors are established.

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Calzada, M. L., M. Algueró, A. Santos, M. Stewart, M. G. Cain et L. Pardo. « Piezoelectric, ferroelectric Pb(Mg1/3Nb2/3)O3–PbTiO3 thin films with compositions around the morphotropic phase boundary prepared by a sol-gel process of reduced thermal budget ». Journal of Materials Research 24, n^o 2 (février 2009) : 526–33. http://dx.doi.org/10.1557/jmr.2009.0045.

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Single perovskite polycrystalline Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) thin films with PMN to PT ratios around the morphotropic phase boundary composition (070PMN-0.30PT, 0.65PMN-0.35PT, and 0.60PMN-0.40PT) have been prepared by chemical solution deposition (CSD). Air-stable and precipitate-free PMN and PT precursor sols were separately synthesized, and PMN-PT sols were obtained by the simple mixture in air of the former. The PMN-PT sols were deposited onto Pt-coated Si substrates and dried on a hot-plate. Crystallization of the films was carried out by rapid thermal processing (RTP) in oxygen, using different temperatures, soaking times, and heating rates. Single perovskite PMN-PT thin films were obtained at low temperatures (650 °C) with short soaking times (6s) and rapid heating rates (200 °C/s). The films show a columnar growth and a uniform thickness. Both the evolution of the perovskite distortion and the electrical properties with the PMN to PT ratio indicate the correct formation of the solid solution. The temperature and frequency dependences of the permittivity and the ferroelectric loops also indicate an increase of the relaxor characteristic of the films as compared with bulk materials. Piezoelectric coefficients were measured across the ferroelectric loop by optical interferometry, and an enhancement of piezoelectricity at the MPB composition was found. A piezoelectric d33 coefficient of ∼55 pC/N was measured in ∼300-nm-thick films of this composition with a saturation polarisation of Ps ∼25 μC/cm2.

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Ko Zaw, Aung, O. Yarovaya, Nyan Htet Lin et M. Donina. « Synthesis and colloidal-chemical properties of manganese dioxide hydrosols synthesized in the presence of sodium thiosulfate ». E3S Web of Conferences 376 (2023) : 01080. http://dx.doi.org/10.1051/e3sconf/202337601080.

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In this paper, the possibility of obtaining manganese dioxide hydrosols by condensation in the presence of sodium thiosulfate is considered. The main properties of hydrosols, including particle size and shape, phase composition, electrophoretic mobility, and the pH range of the dispersion medium in which sols are aggregatively stable, are determined. The sol coagulation thresholds in the presence of potassium chloride, sodium sulfate, and potassium sulfate were determined. It was found that the hydrosols coagulation is reversible. The nature of the aggregative stability of obtained manganese dioxide sols is discussed.

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Skorodumova, Olga, Olena Tarakhno et Olena Chebotaryova. « Improving the Fire-Retardant Properties of Cotton-Containing Textile Materials Through the Use of Organo-Inorganic SiO<sub>2</sub> ; Sols ». Key Engineering Materials 927 (29 juillet 2022) : 63–68. http://dx.doi.org/10.4028/p-jbv49r.

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The effect of fire-retardant compositions based on organo-inorganic SiO2 sols without the use of flame retardants on increasing the fire resistance of cotton-containing textile materials has been studied. Previous studies have shown that the combined use of silicate coatings and flame retardants of simple structure prevents the ignition of impregnated samples of cotton-containing fabric and the proposed chemistry of this process. These studies did not use flame retardants to obtain more information on the effect of the composition and concentration of experimental organo-inorganic SiO2 sols on the fire resistance of treated tissues. The compositions were prepared by the sol-gel method using a technical product – liquid glass – with a silicate modulus of 2,5 and acetic acid solution. The influence of sols concentration in terms of conditioned SiO2 on their rheological features has been studied. It was found that the optical density, fluidity and survivability of experimental sols depend on the concentration of SiO2 in the sol. The compositions were applied to the fabric by the bath method in layers: each layer of the coating was fixed on the surface of the fabric by thermal shock in an oven at temperatures of 80-100 °C. Untreated cotton fabric caught fire under the influence of fire after 7 seconds. Impregnated tissue samples did not ignite under the action of fire, but gradually charred. To determine the effect of coating thickness and SiO2 concentration in the sol on the fire resistance of impregnated fabric samples, fire tests at a gas pressure of 0,2 MPa were performed for 8 s and the area of damage to the reverse side of the fabric was determined. Prolonged exposure to the flame resulted in a crack in the center of the charred spot. In the absence of flame retardants in the fire-retardant composition after removal of the fire source, decay was observed. The time for which a crack is formed in the sample under the action of fire was determined at the time of onset of tissue destruction. It is shown that in the case of using a sol of 10% concentration it is necessary to apply three layers of coating, which doubles the fire resistance (from 7 s for untreated fabric to 15 s for impregnated fabric), the start time of destruction increases 5 times (from 1 min to 5,5 min). The area of damage to the reverse side of the fabric not treated and impregnated with the experimental coating is reduced from 632 mm2 to 0, respectively.

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Scheurell, Kerstin, et Erhard Kemnitz. « Fluorolytic Sol–Gel Synthesis of Nanometal Fluorides : Accessing New Materials for Optical Applications ». Inorganics 6, n^o 4 (3 décembre 2018) : 128. http://dx.doi.org/10.3390/inorganics6040128.

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The potential of fluorolytic sol–gel synthesis for a wide variety of applications in the field of optical materials is reviewed. Based on the fluorolytic sol–gel synthesis of nanometal fluorides, sols of complex fluorometalates have become available that exhibit superior optical properties over known classical binary metal fluorides as, for instance, magnesium fluoride, calcium fluoride, or strontium fluoride, respectively. The synthesis of transparent sols of magnesium fluoroaluminates of the general composition MgxAlFy, and fluoroperovskites, [K1−xNax]MgF3, is reported. Antireflective coatings fabricated from MgF2, CaF2, MgxAlFy, and [K1−xNax]MgF3 sols and their relevant properties are comprehensively described. Especially the heavier alkaline earth metal fluorides and the fluorperovskites crystallizing in a cubic crystal structure are excellent hosts for rare earth (RE) metals. Thus, the second chapter reflects the synthesis approach and the properties of luminescent systems based on RE-doped alkaline earth metal fluorides and [K1−xNax]MgF3 phases.

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Steudel, Ralf, Thomas Göbel et Gabriele Holdt. « The Molecular Composition of Hydrophilic Sulfur Sols Prepared by Acid Decomposition of Thiosulfate [1] ». Zeitschrift für Naturforschung B 43, n^o 2 (1 février 1988) : 203–18. http://dx.doi.org/10.1515/znb-1988-0212.

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Hydrophilic sulfur sols prepared from sodium thiosulfate and concentrated sulfuric acid and purified by repeated NaCl precipitation and peptization in water have been studied by chemical analysis, vibrational spectroscopy, ion-pair chromatography and reversed-phase HPLC. The composition of the sol is Na1.64S28.6O6 · 5.9/n Sn · 1.0 NaCl. The elemental sulfur Sn (n = 6-14; mainly S 8) accounts for 17% the total sulfur; 83% of the S are present as long-chain polythionates which form micelles in which the Sn molecules are dissolved. On aging of the sol at 20 °C the polythionate micelles decompose to give water-soluble short-chain polythionates and elemental sulfur which precipitates from the solution. The micelle structure of hydrophilic sulfur sols may serve as a model for the so-called sulfur globules (S°) formed intra- or extracellularly by many sulfur bacteria which oxidize reduced sulfur compounds to S°. - ᴛ∙nfrared and Raman spectra of K2SmO6 (m = 3-6) are reported. The photodecomposition of aqueous tetrathionate yields sulfite, thiosulfate, and polythionates with up to 9 sulfur atoms

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Qu, Dan Ni, Hai Feng Cheng, Yong Jiang Zhou, Xin Xing et Dong Qing Liu. « Effect of Templates on the Electrochromic Properties of Tungsten Oxide Thin Films ». Applied Mechanics and Materials 152-154 (janvier 2012) : 519–25. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.519.

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The mesoporous tungsten oxide (WO3) films were derived from the peroxotungstic acid (PTA) sol with templates through sol-gel method. Polyethylene glycol (PEG) 400 and tri-block polymer P123 (HO(CH2CH2O)20(CH2CH(CH3)O)70(CH2CH2O)20H) were chosen as templates. The structural, morphological, optical and electrochromic properties of the WO3 thin films derived from different sols were studied. The composition and crystal phase of the films change at different annealing temperatures. The films derived from the sols containing templates have higher crystallization temperature than those without templates. And the morphologies are distinctly different from different sols. The addition of the templates can improve the electrochromic properties of the WO3 films, and those prepared from the 3% of P123 sol show the best electrochromic properties. The highest transmittance modulation is near 60%, and the largest ion inserted and deinserted diffusion coefficient can reach 5.706×10-12 cm2/s and 1.271×10-11 cm2/s, respectively.

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HARTRIDGE, A., et A. K. BHATTACHARYA. « PREPARATION AND HOMOGENEITY OF LANTHANIDE-DOPED CERIA NANOCRYSTAL DISPERSIONS ». Modern Physics Letters B 14, n^o 03 (10 février 2000) : 79–88. http://dx.doi.org/10.1142/s0217984900000136.

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Aqueous sols of solid solutions of the general formula Ce 1-x Ln x O 2-x/2□x/2 (Ln=entire lanthanide range, x = 0–0.50 and =anion vacancy) were synthesized using inorganic materials. The sols contained single-phase nanocrystals with particle sizes between 7–20 nm from photon correlation spectroscopy and crystallite sizes around 5 nm from X-ray diffraction. The nanocrystals were dispersed on an amorphous silica support and individual crystals examined for composition and structure by high-resolution TEM/EDAX. High-resolution pictures showed the nanocrystals to be between 4–6 nm in size, in agreement with X-ray diffraction results. Conical dark field and bright field pictures of the same area highlighted nanocrystals to be analyzed and microdiffraction of these crystals showed spot patterns of various individual planes of the fcc fluorite lattice giving lattice parameters, depending on dopant, between 5.6–5.9 Å. EDAX analysis of individual crystals compared closely to each other, to that of an average over a large area and to that of the nominal composition.

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Moberg, Jens Peter. « Composition and development of the clay fraction in danish soils. An overview / Composition et évolution de la fraction argileuse des sols danois. Un aperçu ». Sciences Géologiques. Bulletin 43, n^o 2 (1990) : 193–202. http://dx.doi.org/10.3406/sgeol.1990.1854.

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Golobostanfard, Mohammad Reza, Reza Ebrahimifard et Hossein Abdizadeh. « Synthesis of TiO₂/Zno Core/Shell Type Nanocomposite via Sol-Gel Method ». Key Engineering Materials 471-472 (février 2011) : 993–98. http://dx.doi.org/10.4028/www.scientific.net/kem.471-472.993.

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TiO2/ZnO Nanocomposite powders with different Zn/Ti ratios were synthesized via sol-gel method. The as prepared and calcined Titania nanopowders were added to the ZnO sols. Also the as prepared and calcined ZnO nanopowders were separately added to the TiO2 sols. However, in the latter case, the nanocomposite never formed due to the high acidity of the sols. After gelation, the powders were dried and calcined at 500°C for 1h. The phase composition, structure, morphology and optoelectrical properties of the powders were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV-Vis photospectroscopy and photoluminescence spectroscopy (PL). The XRD patterns confirm the presence of TiO2 and ZnO crystalline phases in the TiO2 particles/ZnO sol samples. The FESEM micrographs show that TiO2/ZnO nanocomposites heat treated at 500°C were formed with average diameter of about 250nm with 50nm ZnO particles on clusters of 40nm TiO2 particles. It was found that the optoelectronic properties of the nanocomposites were improved according to the UV-Vis and photoluminescence spectroscopy.

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Gribanyov, D. A., E. V. Rudakova et E. G. Zavyalova. « A systematic study of SERS spectra of cationic Raman dyes adsorbed on citrate-stabilized silver nanoparticles ». Известия Российской академии наук. Серия физическая 87, n^o 2 (1 février 2023) : 194–200. http://dx.doi.org/10.31857/s0367676522700363.

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The adsorption (kinetics and signal stability) of cationic triarylmethane dyes and an acridine derivative with various counter-ions on citrate-stabilized hydroxylamine-reduced silver sols was studied using SERS spectroscopy. The influence of the method of nanoparticle synthesis, as well as the composition and ionic strength of the medium on the stability of nanoparticle–dye complexes was investigated.

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Shilova, O. A., N. N. Gubanova, A. G. Ivanova, M. Yu Arsent’ev et V. A. Ukleev. « Composition and structure of platinum-containing thin composite films prepared from silica sols ». Russian Journal of Inorganic Chemistry 62, n^o 5 (mai 2017) : 645–53. http://dx.doi.org/10.1134/s0036023617050230.

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Evstrop'ev, S. K., V. M. Volynkin, A. S. Saratovskiy, D. P. Danilovich, V. V. Demidov, K. V. Dukel'skiy, D. V. Bulyga et S. O. Sysolyatin. « Modification of Quartz Ceramics by Applying a Sol-Gel Composition of MgO–Al2O3–ZrO2–SiO2 System ». Журнал прикладной химии, n^o 2 (15 décembre 2023) : 200–208. http://dx.doi.org/10.31857/s0044461823020081.

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Composite sol-gel materials of the MgO–Al2O3–ZrO2–SiO2 system were synthesized and the processes of their thermal evolution and crystallization were studied. Application of sol-gel compositions of the MgO–Al2O3–ZrO2–SiO2 system to the surface of quartz ceramics leads to a significant increase in the mechanical strength of the material. The processes of thermal evolution of the sol-gel composition were studied using IR spectroscopy, X-ray diffraction, electron microscopy, and energy dispersive analysis. It was shown that the formation of the oxide composite structure of materials begins at the stage of wet gels. Treatment of quartz ceramics with composite sols followed by drying and heat treatment up to 1200°C results in modification of the surface layers of the material, which makes it possible to increase the mechanical strength of the material by more than 20%. Sol-gel modifying compositions, upon drying and subsequent heat treatment, form polycrystalline structures bonded to quartz ceramic particles and consisting of various oxide crystals.

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Anh Tuyet, Ngo Thi. « CHARACTERIZATION OF FLUORIDATED HYDROXYAPATITE (FHA) SOL-GEL COATINGS ON TITANIUM SUBSTRATE ». Vietnam Journal of Science and Technology 55, n^o 5B (24 mars 2018) : 40. http://dx.doi.org/10.15625/2525-2518/55/5b/12208.

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In this paper, FHA coatings [FHA, Ca10(PO4)6(OH)2-x Fx] (wherein 0 ≤ x ≤ 2) were deposited on titanium substrate by sol-gel method with heat treatment at 900 oC for 4 hours. Different concentrations of F- were incorporated into the apatite structure during the sols preparation. The FHA sols were prepared using various amounts of ammonium fluoride [NH4F] with the [P]/[F] molar ratios of 12, 6, 4, 3 in order to have the corresponding compositions of Ca10(PO4)6(F0.5 OH1.5), Ca10(PO4)6 FOH, Ca10(PO4)6(F1.5 OH0.5) and Ca10(PO4)6F2, respectively. The fabricated FHA coatings were assessed by various methods, namely: morphological structure and chemical composition of coatings were studied by scanning electron microscopy (SEM) and Energy dispersive spectrometry (EDS). The anti-corrosion properties of samples were evaluated by Potentiodynamic polarization curves and Nyquist impedance spectrum. The biocompatibility of FHA coatings on titanium substrates were evaluated by in-vitro tests in simulated body fluid (SBF) solution during 21 days, and ICPMS (Inductively Coupled Plasma Mass Spectrometry) analysis method has been used. The results showed that with dense structure, FHA coatings expressed higher anti-corrosion and biocompatibility performance as compared with that of HA coating.

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Aust, Undine, et Gerhard Tomandl. « Development of Non-Silicate Microporous Membranes with High Chemical Resistance ». Advances in Science and Technology 45 (octobre 2006) : 2043–48. http://dx.doi.org/10.4028/www.scientific.net/ast.45.2043.

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TiO2-ZrO2 mixed-oxide membranes were prepared via polymeric sol-gel technique. The final composition is already predefined during the preparation of the sols by using the corresponding quantities of the starting alkoxides. The mixed-oxide membranes were characterized by Xray diffraction, nitrogen sorption, and field emission scanning electron microscopy as well as filtration and corrosion tests. The observed results prove the positive influence on the investigated properties by addition of a second oxide. Depending on the composition of the mixed-oxide membranes, a remarkable increase in the crystallization temperatures is demonstrated. Using mixed-oxide systems, the retardation of grain growth is confirmed.

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Salissou Ibrahim, Jamilou, Ibrahim Doka Dahiratou, Baradje Moussa, Harouna Maidoukia Abdoul Razack, Addam Kiari Saidou, Mahamane Sabiou, Mohamadou Youssouf, Barral Maria Teresa et Paradelo Nunez Remigio. « EFFET DES FUMURES ORGANIQUES ET DES PRATIQUES AGRICOLES SUR LES PROPRIETES PHYSICO-CHIMIQUES DES SOLS EN CULTURE PURE ET ASSOCIEE DE TOMATE DANS LARRONDISSEMENT V DE NIAMEY (NIGER) ». International Journal of Advanced Research 11, n^o 04 (30 avril 2023) : 963–75. http://dx.doi.org/10.21474/ijar01/16748.

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La pauvretes des sols en nutriments au Niger figure parmi les contraintes majeures a la culture maraichere.Dans ce contexte, la gestion efficace des ressources en eau et la fertilisation des sols saverent necessaires pour maintenir, rebondir les rendements des cultures et ameliorer la fertilite des sols.Lobjectifvise a ameliorerla production de la tomate, element nutritionnel de base dans lalimentation nigerienne et a une bonne gestion durable de la fertilite des sols et didentifier le modele ideal damelioration des conditions de culture de cette plante.Un dispositif experimental de Ficher a ete mis en place dans la zone de Saguia a Niamey et les traitements a base des fumures organiques (bouse des vaches, bouse de chevres et fiente des volailles), a des differentes doses ont ete appliques sur les proprietes des sols de culture de tomate.La granulometrie,le pH, la composition du complexe dechange cationique, la presence delements en trace metalliques, la stabilite des agregats, la glycoproteine de la glomaline ont ete analyses sur le sol de la couche 0-20 cm par les methodes danalyses physico-chimiques. Les resultats ont montre que les sols etudies presentent une texture sablo-limono-argileuse et un pH optimal de 8,2 favorable a la culture de tomate, du taux eleve en matiere organique. Les bases echangeables analysees ont montre quil y a une quantite importante en calcium (Ca2+) et magnesium (Mg2+). Ensuite, les teneurs en potassium (K+) et sodium (Na+) du sol presentent des valeurs acceptables pour lensemble des echantillons de solLutilisation des fumures organiques et des pratiques agricoles permettait de reduire lacidite et dameliorer lactivite biologique du sol.En occurrence lassociation et la fertilisation organique a une dose adequate sont des solutions envisageables pour ameliorer la productivite de la tomate au Niger et en particulier dans la zone de Saguia.

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Čierniková, Marianna, Petra Balážová, Alfonz Plško, Petr Exnar, Jana Pagáčová et Iveta Papučová. « Relation between chemical composition of sols and surface free energy of inorganic-organic films ». Journal of Sol-Gel Science and Technology 88, n^o 3 (27 octobre 2018) : 497–507. http://dx.doi.org/10.1007/s10971-018-4856-y.

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Yang, Hui, Lu Lu Zhang et Chuang Wang. « Preparation and Biocompatibility of Nano-Hydroxyapatite/β-Sheet Silk Protein Composite ». Advanced Materials Research 287-290 (juillet 2011) : 1335–43. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.1335.

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To enhance the mechanical strength of hydroxyapatite (HAP), a nano-HAP/β-sheet fibroin (nano-HAP/SF) composite was synthesized by mixing nano-HAP sols with SF sols. Aβ-sheet structural SF was prepared by a salt-resolving method. The nano-HAP sols was prepared by a co-precipitation method. The phase composition of HAP and nano-HAP/SF composites were investigated by X-ray diffraction and Fourier transform infrared spectroscopy (FTIR). Their morphologies were observed by scanning electron microscopy. The mechanical strength of the nano-HAP/SF composite was measured by a universal material detector. The bioactivity and biocompatibility of the obtained composites were confirmed by tests in simulated body fluid (SBF) and by a culture of rat osteoblasts cell. Results showed that the obtained SF is a typical silk II withβ-sheet conformation. The FTIR spectra analysis indicated that the chemical bonds were formed between SF and HAP in the nano-HAP/SF. The result of SBF test demonstrated that the needle-like crystals of HAP were formed on the surface of the sample and the result of cell culture showed that the rat osteoblasts grown and reproduced well on the surface of the composite. The compression strength of SP/HAP reached 63 MPa.

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Mitrovic, Dejan, Vladimir Panic, Aleksandar Dekanski, Slobodan Milonjic, Radoslav Atanasoski et Branislav Nikolic. « The effect of the composition of the dispersing medium of oxide sols on the electrocatalytic activity of sol-gel obtained RuO2-TiO2/Ti anodes ». Journal of the Serbian Chemical Society 66, n^o 11-12 (2001) : 847–57. http://dx.doi.org/10.2298/jsc0112847m.

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The influence of the addition of methanol, ethanol, 1-propanol and 2-propanol to the dispersing medium of amixture of RuO2 and TiO2 sols on the electrochemically active surface area for proton exchange, as well as on the electrocatalytic activity for the chlorine evolution reaction (CER) of RuO2-TiO2/Ti electrode obtained by sol-gel procedure was investigated. The electrochemically active surface area was examined by cyclic voltammetry, while the analysis of the activity for the CER was performed by polarization measurements. The stability of the obtained anode coatings was also checked by an accelerated stability test. The anode properties depend on the number of C atoms in the alcohol molecule, as well as on the elapsed time between the preparation of the sols/alcohol mixture and its application onto the titanium support. The addition of alcohol increased the activity of the anodes for the CER, compared to those prepared without the addition, but their stability was smaller.

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Xu, Xue Qing, Yu Zhang et G. Xu. « Influences of Stabilizers on the Microstructure and Properties of Sol-Gel Tin Doped Indium Oxide Thin Films ». Materials Science Forum 610-613 (janvier 2009) : 372–77. http://dx.doi.org/10.4028/www.scientific.net/msf.610-613.372.

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The tin doped indium oxide (ITO) thin films were prepared by sol-gel dip-coating process from InCl2.4H2O and SnCl4 in alcoholic solutions. The influences of organic ligands, including acetylacetone (AcAc) and diethanolamine (DEA), on the stability and the composition of the sols, and on the microstructure and properties of the thin films have been investigated. It is indicated that a suitable amount of DEA or AcAc helped to keep the stability of the ITO sols, and helpful for the formation of the homogeneous thin films. The TG-DSC and X-ray diffraction analysis revealed that the organic ligands also had effect on the crystallization temperature and crystal structures of the thin films. The thin films with DEA as coordination ligands had a good crystal quality when heated at 450°C. As a result, it exhibited a better electrical property than that with AcAc as stabilizers.

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Kumar, Amitabh, et Rustum Roy. « RESA—A wholly new process for fine oxide powder preparation ». Journal of Materials Research 3, n^o 6 (décembre 1988) : 1373–77. http://dx.doi.org/10.1557/jmr.1988.1373.

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A new process for making fine (10–1000 nm) oxide powders has been devised. It is based on striking an are between two metallic electrodes submerged in a dielectric liquid, typically water. By controlling the process parameters (voltage, amperage, and composition of liquid), one can obtain fine sols of the anhydrous oxides of Al, Ti, Zr, etc., and exercise some control over the particular phase in variable valence metals such as Cr.

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Aurousseau, P., et J. Pages. « Estimation de la composition chimique d'un phyllosilicate secondaire en equilibre avec une population homogene d'eaux ». Clay Minerals 20, n^o 3 (septembre 1985) : 315–26. http://dx.doi.org/10.1180/claymin.1985.020.3.04.

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ResumeDeux questions sont abordées: (1) Une eau naturelle étant donnée, peut-on considérer qu'elle est en équilibre avec un minéral de formule connue? (2) Un ensemble homogène d'eaux naturelles étant donné, peut-on considérer que ces eaux sont en équilibre avec un minéral? Si oui, Peut-on proposer une estimation de la composition de ce mineral? Nous proposons une méthode pour répondre à chacune de ces deux questions. Cette methode est appliquée à l'estimation de minéraux argileux de formule générale SiaAlbMgcCadKeNafOn(OH)m. Les données utilisées sont des eaux de percolation, dans des colonnes de sols.

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ZHAO, CHANGLEI, ZHIHONG WANG, WEIGUANG ZHU, XI YAO et WEIGUO LIU. « PZT THICK FILMS FABRICATION USING A SOL-GEL BASED 0-3 COMPOSITE PROCESSING ». International Journal of Modern Physics B 16, n^o 01n02 (20 janvier 2002) : 242–48. http://dx.doi.org/10.1142/s0217979202009706.

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A sol-gel based 0-3 ceramic-ceramic composite processing has been applied to fabricate lead zirconate titanate thick films with a composition near the morphotropic phase boundary, PZT53/47. In order to eliminate the effects of humidity on the stability of the sols, solid PZT precursors are prepared from partially stabilized titanium isopropoxide, lead acetate trihydrate and zirconium acetylacetonate without any solvent. Then the solid precursors were dissolved in 2-methoxythanol to form sols. Certain quantum modified PZT ceramic powder was dispersed into this obtained solution. Crack-free thick films with series thickness of 5 ~ 20-μm were fabricated using spin-coating method. The surface morphology and structural properties of the films were studied with Field Emission-SEM and X-ray diffraction techniques respectively. Electrical properties were compared with those of thin films. Thick PZT films should have good perspective in the application of new piezoelectric devices that cannot be achieved using conventional thin film or bulk techniques.

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Urkhanova, L. A., et M. A. Savelyeva. « The effect of different composition sols on change of structure and properties of cement stone ». Nanotechnologies in Construction : A Scientific Internet-Journal 8, n^o 6 (10 décembre 2016) : 20–42. http://dx.doi.org/10.15828/2075-8545-2016-8-6-20-42.

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Shilova, O. A., N. N. Gubanova, V. A. Matveev, V. Yu Bayramukov et A. P. Kobzev. « Composition, structure, and morphology of the surface of nanodimensional platinum-containing films obtained from sols ». Glass Physics and Chemistry 42, n^o 1 (janvier 2016) : 78–86. http://dx.doi.org/10.1134/s1087659616010168.

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Pawlik, Natalia, Barbara Szpikowska-Sroka, Tomasz Goryczka et Wojciech A. Pisarski. « Studies of Sol-Gel Evolution and Distribution of Eu3+ Ions in Glass–Ceramics Containing LaF3 Nanocrystals Depending on Initial Sols Composition ». International Journal of Molecular Sciences 22, n^o 3 (20 janvier 2021) : 996. http://dx.doi.org/10.3390/ijms22030996.

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In this work, we performed a systematic analysis of the impact of selected chemical reagents used in sol-gel synthesis (i.e., N,N-dimethylformamide) and different catalyst agents (i.e., CH3COOH, HNO3) on the formation and luminescence of Eu3+-doped SiO2–LaF3 nano-glass–ceramics. Due to the characteristic nature of intra-configurational electronic transitions of Eu3+ ions within the 4f6 manifold (5D0 → 7FJ, J = 0–4), they are frequently used as a spectral probe. Thus, the changes in the photoluminescence profile of Eu3+ ions could identify the general tendency of rare earth materials to segregate inside low-phonon energy fluoride nanocrystals, which allows us to assess their application potential in optoelectronics. Fabricated sol-gel materials, from sols to gels and xerogels to nano-glass–ceramics, were examined using several experimental techniques: X-ray diffraction (XRD), transmission electron microscopy (TEM), infrared spectroscopy (IR), and luminescence measurements. It was found that the distribution of Eu3+ ions between the amorphous silicate sol-gel host and LaF3 nanocrystals is strictly dependent on the initial composition of the obtained sols, and the lack of N,N-dimethylformamide significantly promotes the segregation of Eu3+ ions inside LaF3 nanocrystals. As a result, we detected long-lived luminescence from the 5D0 excited state equal to 6.21 ms, which predisposes the obtained glass–ceramic material for use as an optical element in reddish-orange emitting devices.

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Dymnikova, N. S., E. V. Erokhina et A. P. Moryganov. « New approach to use of domestic flaxseed raw materials ». Chemical Engineering 23, n^o 6 (2022) : 250–61. http://dx.doi.org/10.31044/1684-5811-2022-23-6-250-260.

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The conditions for obtaining stable metallic silver hydrosols in the presence of flax fiber extracts have been studied by the method of «green chemistry» and the possibility of using synthesized sols to provide cellulose-containing materials with antimicrobial activity or biosecurity has been proved. The process of synthesis of ultrafine silver particles in the presence of concomitant natural impurities of flax fibers isolated from them during alkaline high-temperature treatment was studied by spectrophotometry, photon correlation spectroscopy and visual observation. The effect of the extract composition on dynamics of the formation of stable silver nanoparticles was determined. IR spectroscopy and potentiometric titration methods proved that an increase in the alkalinity of a cooking solution led not only to an increase in the amount of impurities in the solution, but also to their destruction, and the complex of reducing substances formed in the solution could act as a silver ion reducing agent even at a low extraction temperature. It was proven that antimicrobial activity against test cultures of synthesized sols and cellulose tissue treated with them depended on the conditions of synthesis.

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Baklanova, Natalia I., B. N. Zaitsev et Anatoly Titov. « Improved Oxide-Based Interfacial Coatings for the Next Generation of CMC's ». Advances in Science and Technology 50 (octobre 2006) : 51–56. http://dx.doi.org/10.4028/www.scientific.net/ast.50.51.

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CMC's reinforced by SiC-based fibers achieve high toughness and damage tolerance through the disposal of weak fiber coating which can deflect cracks and promote debonding at the fiber/matrix region. Refractory oxide-based systems are considered as the most promising ones for this purpose. Sols of zirconia, including stabilized zirconia were used as simple and readily processable precursors for obtaining interfacial coatings on SiC tow and cloth. The morphology, composition, topography, roughness, tensile properties of as-prepared and exposed to air at 1000°C coated fibers were evaluated by SEM/EDS, XPS, XRD, AFM, micro Raman analysis. The peculiarities of the behavior of oxide-coated fibers are governed by the properties of initial sols, procedure for coating fabrication, chemical and nanostructural factors. The peculiarities of the behavior of the stabilized zirconia interphase with accurate phase control will be discussed. A monitoring of the t→ m phase transformation within ZrO2 interfacial coating on SiC fiber using micro Raman makes it possible quantitatively to evaluate an ability of ZrO2 as oxidation resistance and readily deformable weak interfacial coating for the next-generation CMC's.

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Minter, J. R. « Characterization of colloidal materials by cryo-TEM ». Proceedings, annual meeting, Electron Microscopy Society of America 51 (1 août 1993) : 728–29. http://dx.doi.org/10.1017/s0424820100149477.

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Many researchers develop products and processes that depend upon colloidal materials. Rheological and other important material parameters are influenced by the morphology of the colloid. The photography industry uses many such colloids including silver halide sols, photographic coupler sols and emulsions surfactants, and gelatin solutions and gels. High-resolution direct electron images of these systems in their native states permit photographic scientists to understand how changes in formulation produce changes in microstructure and, ultimately, to understand the photographic performance of the system.We prepare thin biconcave liquid films spanning the holes in a perforated carbon film supported by an electron microscope grid (see Fig 1). To prevent changes in composition of the colloid caused by evaporation, the films are prepared in an environmental chamber and are propelled through a trap door into a container of liquid ethane. The specimen is cooled at a rate sufficient to prevent crystallization of water. When maintained below -150 °C, these specimens are stable and compatible with the high vacuuary of the electron microscope.

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Kaya, C., et A. R. Boccaccini. « Microstructural variations in mullite ceramics derived from diphasic sols using different forming techniques ». Journal of Materials Research 17, n^o 12 (décembre 2002) : 3000–3003. http://dx.doi.org/10.1557/jmr.2002.0435.

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Mullite ceramics with controlled microstructure in terms of residual glassy phase and density were produced from diphasic silica/boehmite sols using pressure filtration, die-pressing, and extrusion techniques. The effect of the compaction process on the green and sintered densities and on the final mullite microstructure was investigated. It is shown that glassy-phase-free mullite with high green and sintered densities can be produced from engineered diphasic colloidal suspensions using pressure filtration. The results show that the green body formation technique strongly determines the final sintered density, but it has no effect on the final phase composition of diphasic sol-derived sintered mullites.

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Boccaccini, A. R., I. MacLaren, M. H. Lewis et C. B. Ponton. « Electrophoretic deposition infiltration of 2-D woven SiC fibre mats with mixed sols of mullite composition ». Journal of the European Ceramic Society 17, n^o 13 (janvier 1997) : 1545–50. http://dx.doi.org/10.1016/s0955-2219(97)00025-3.

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Panic, Vladimir, et Branislav Nikolic. « Electrocatalytic properties and stability of titanium anodes activated by the inorganic sol-gel procedure ». Journal of the Serbian Chemical Society 73, n^o 11 (2008) : 1083–112. http://dx.doi.org/10.2298/jsc0811083p.

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The properties of activated titanium anodes, RuO2-TiO2/Ti and RuO2--TiO2-IrO2/Ti, prepared from oxide sols by the sol-gel procedure, are reviewed. RuO2 and TiO2 sols were synthesized by forced hydrolysis of the corresponding chlorides in acid medium. The morphology of the prepared sols was investigated by transmission electron microscopy. The chemical composition of the RuO2 sol was determined by X-ray diffraction and thermogravimetric analysis. The loss of electrocatalytic activity of a RuO2-TiO2/Ti anode during an accelerated stability test was investigated by examination of the changes in the electrochemical characteristics in the potential region of the chlorine and oxygen evolution reaction, as well as on the open circuit potential. These electrochemical characteristics were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and polarization measurements. The changes in electrochemical characteristics of the anode prepared by the sol-gel procedure were compared to the changes registered for an anode prepared by the traditional thermal decomposition of metal chlorides. The comparison indicated that the main cause for the activity loss of the sol-gel prepared anode was the electrochemical dissolution of RuO2, while in the case of thermally prepared anode the loss was mainly caused by the formation of an insulating TiO2 layer in the coating/Ti substrate interphase. The results of an accelerated stability test on RuO2-TiO2/Ti and RuO2--TiO2-IrO2/Ti anodes showed that the ternary coating is considerably more stable than the binary one, which is the consequence of the greater stability of IrO2 in comparison to RuO2.

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Hamulić, Damir, Peter Rodič, Matic Poberžnik, Marjan Jereb, Janez Kovač et Ingrid Milošev. « The Effect of the Methyl and Ethyl Group of the Acrylate Precursor in Hybrid Silane Coatings Used for Corrosion Protection of Aluminium Alloy 7075-T6 ». Coatings 10, n^o 2 (13 février 2020) : 172. http://dx.doi.org/10.3390/coatings10020172.

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This study investigated polysiloxane hybrid sol-gel coatings synthesized from tetraethyl orthosilicate (TEOS), 3-(trimethoxysilyl)propyl methacrylate (MAPTMS) and two different precursors, i.e., methyl- or ethyl- methacrylate (MMA or EMA), as corrosion protection of aluminium alloy 7075-T6. The hypothesis was that the additional alkyl group might affect the chemical properties and, consequently, the corrosion properties. Synthesis of the sols proceeded in two steps, each involving either MMA or EMA in the same molar ratio. The resulting sols, siloxane-(poly(methyl methacrylate-co-MAPTMS)) or siloxane-(poly(ethyl methacrylate-co-MAPTMS)), were applied on aluminium alloy followed by characterization in terms of chemical structure and composition, topography, wettability, adhesion and corrosion resistance in 0.1 M sodium chloride solution. The chemical properties of sols, monoliths and coatings were investigated using Fourier transform infrared spectrometry, solid state nuclear magnetic resonance spectrometry, X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Coatings were similar in terms of surface topography, while the wettability of the coating with EMA showed 6° greater water contact angle compared to the coating with MMA. Both coatings were shown, by electrochemical impedance spectroscopy in 0.1 M NaCl solution, to act as barriers to protect the underlying substrate in which coating with EMA exhibits better protection properties after 2 months of immersion. Adhesion tests confirmed the highest grade of adhesion to the substrate for both coatings. Testing in a salt-spray chamber demonstrated excellent corrosion protection, where coatings remaining intact after more than 600 h of exposure.

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Duponnois, Robin, Ezékiel Baudoin, Hervé Sanguin, Jean Thioulouse, Christine Le Roux, Estelle Tournier, Antoine Galiana, Yves Prin et Bernard Dreyfus. « L'introduction d'acacias australiens pour réhabiliter des écosystèmes dégradés est-elle dépourvue de risques environnementaux ? » BOIS & ; FORETS DES TROPIQUES 318, n^o 318 (1 décembre 2013) : 59. http://dx.doi.org/10.19182/bft2013.318.a20519.

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L'utilisation d'essences forestières exotiques et plus particulièrement des arbres à croissance rapide (acacias, pins ou eucalyptus) a été fréquemment recommandée pour réhabiliter et restaurer à brève échéance des milieux dégradés suite à des événements naturels ou à des activités anthropiques. L'incidence sur l'environnement de l'introduction de ces espèces, parfois envahissantes, est surtout évaluée pour leur impact sur la biodiversité végétale et les caractéristiques physico-chimiques des sols, mais rarement en ce qui concerne la composition de la microflore. Les micro-organismes, et plus particulièrement les champignons mycorhiziens, jouent un rôle clé vis-à-vis des mécanismes biologiques régissant la fertilité chimique des sols et leur productivité, facteurs de stabilité des écosystèmes terrestres. L'approche retenue a été de décrire l'incidence de l'introduction d'essences exotiques sur les caractéristiques biologiques des sols, ainsi que les conséquences sur la reconstruction d'un couvert végétal composé par des espèces natives du milieu d'origine. Après avoir rappelé l'importance de l'utilisation des acacias à travers le monde, deux études réalisées au Sénégal et en Algérie ont permis de montrer que deux acacias australiens, Acacia holosericea et Acacia mearnsii, induisent de profondes modifications de la diversité fonctionnelle de la microflore du sol et aussi de la structure des microorganismes symbiotiques (champignons mycorhiziens et rhizobia). Ces acacias entraînent une inhibition de la croissance de deux espèces forestières natives, Faidherbia albida et Quercus suber. Les résultats confirment le besoin de cerner les processus biologiques liés aux actions d'introduction d'essences exotiques afin de moduler leur utilisation. Ainsi, cette connaissance préviendra les risques et assurera les performances des opérations de reboisement, notamment pour la réhabilitation des terrains dégradés.

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Pookmanee, Pusit, et Sukon Phanichphant. « Characterization of Bismuth Titanate Powders ». Advanced Materials Research 26-28 (octobre 2007) : 247–50. http://dx.doi.org/10.4028/www.scientific.net/amr.26-28.247.

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Bismuth titanate was prepared from the sol-gel method. Bismuth nitrate and titanium isopropoxide were used as the starting precursors with the mole ratio of Bi:Ti as 4:3. Solutions were mixed in acetic acid medium and heat at 80 oC for 2h. Sols were obtained after adjusting the final of pH of solution to 2. Gels were formed after drying at 100 oC for 24h. The milled powders were calcined at 500-800 oC for 2h. The phase formation was investigated by X-ray diffractometry (XRD). Single phase with orthorhombic structure of bismuth titanate was obtained after calcination at 700 oC for 2h. The morphology and chemical composition were studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The average particle size was 0.50- 1.5 μm with the irregular shape. The elemental composition of bismuth, titanium and oxygen showed the characteristic X-ray energy values.

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Ruess, Liliane, Anders Michelsen et Sven Jonasson. « Simulated climate change in subarctic soils : responses in nematode species composition and dominance structure ». Nematology 1, n^o 5 (1999) : 513–26. http://dx.doi.org/10.1163/156854199508513.

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Abstract The nematode fauna at two contrasting subarctic sites was studied at Abisko, Swedish Lapland. One site was a dwarf shrub dominated, tree-line heath (450 m a.s.l.) and the other a high altitude fellfield (1150 m a.s.l.). Responses in the composition of the nematode fauna to eight growing seasons with simulated climate change were monitored. The environmental manipulations consisted of temperature increase by using passive greenhouses, NPK fertilization, and a combination of both. A total of 98 species was found at the sites, with twice as many species at the heath compared to the climatically harsh fellfield. Species similarity was low, most likely due to differences in soil type and vegetation cover. The environmental perturbations caused distinct changes in dominance and trophic structure. Taxa common at both sites responded similarly with increases in Aphelenchoides, Filenchus and Plectus , and decreases in Eudorylaimus, Monhystrella and Teratocephalus . Generally, the manipulations changed the trophic composition in favour of fungal and plant feeding species, indicating a shift in the decomposition pathway. Modification provoquee du climat dans des sols subarctiques: reaction de la composition specifique des nematodes et de la structure de la dominance - La faune des nematodes a ete etudiee a Abisko (Laponie suedoise) en deux sites subarctiques contrastes. L'un consistait une vegetation de bruyere dominee par des buissons nains (a 450 m d'altitude) et l'autre etait situe sur un coteau a haute altitude (1150 m). La reaction de la faune nematologique aux modifications provoquees du climat a ete observee. Ces modifications comprenaient une augmentation de la temperature par utilisation de serres passives, une fertilisation NPK et une combinaison des deux. Un total de 98 especes ont ete trouvees dans les deux sites. La similitude des especes etait peu elevee, ce tres probablement du aux differences dans les types de sols et la couverture vegetale. Le nombre d'especes etait deux fois plus eleve sous bruyeres, que pour le coteau au climat rude. Apres huit saisons de croissance ayant comporte des perturbations de l'environnement, de nets changements sont apparus dans la dominance et la structure trophique. Les nematodes communs aux deux sites ont montre une reaction similaire, positive pour les Aphelenchoides, Filenchus et Plectus et negative pour les Eudorylaimus, Monhystrella et Teratocephalus. En general, les modifications ont change la composition trophique en faveur des especes fungivores et herbivores, indiquant par la des changements dans le mode de decomposition des vegetaux.

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Shilova, Olga A. « Heterogeneous Sol-Gel Systems – Derived Ceramics ». Advances in Science and Technology 63 (octobre 2010) : 131–40. http://dx.doi.org/10.4028/www.scientific.net/ast.63.131.

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Heterogeneous sol-gel systems (suspensions), synthesized by mixing sols and fillers of various dispersity (oxides, minerals, etc.), are successfully used to prepare glass-ceramic coatings. Sol composition (precursor, catalyst, solvent, dopants), filler dispersity and a homogenization mode for obtained suspensions essentially influence the properties of coatings formed. Here ways of the control of properties of heterogeneous sol-gel systems (by using various dopants, additives of organic low- and high-molecular compounds, as well as ultrasound) to reach set electro-physical and mechanical characteristics of coatings are considered in details. A number of examples of applications of glass-ceramic and hybrid coatings as well as ‘skin’ - layers are resulted.

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Manso, M., J. M. Martínez-Duart, M. Langlet, C. Jiménez, P. Herrero et E. Millon. « Aerosol-gel-derived Microcrystalline Hydroxyapatite Coatings ». Journal of Materials Research 17, n^o 6 (juin 2002) : 1482–89. http://dx.doi.org/10.1557/jmr.2002.0220.

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Highly porous microcrystalline hydroxyapatite (HAP) coatings have been prepared from calcium nitrate and phosphoric acid based sols by the aerosol-gel process. The coatings were studied after sintering at different temperatures with the use of Fourier transform infrared spectroscopy, x-ray diffraction, energy disperse x-ray microanalysis, scanning electron microscopy, and transmission electron microscopy. The composition, structure, and morphology of the coatings sintered at 650 °C fit fairly well highly porous HAP. These coatings were reproduced onto TiO2/Si substrates and studied by Rutherford backscattering. It is shown that even after chemical etching, an adherent calcium phosphate phase remains attached to the TiO2/Si substrate.

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Gilliot, Jean-Marc, Emmanuelle Vaudour, Joël Michelin et Sabine Houot. « Estimation des teneurs en carbone organique des sols agricoles par télédétection par drone ». Revue Française de Photogrammétrie et de Télédétection, n^o 213 (26 avril 2017) : 105–15. http://dx.doi.org/10.52638/rfpt.2017.193.

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La matière organique (MO) est un élément important de la fertilité des sols cultivés. Les mesures de réflectance ont déjàété utilisées avec succès pour prédire la teneur en carbone organique (CO) des sols agricoles, soit au laboratoire surdes échantillons de sols séchés, soit directement au champ à l'aide de spectro-radiomètres de terrain ou grâce à desimages satellitaires. Cette étude propose une méthode de prédiction spatialisée du CO des sols, à partir d'imageriedrone. Une parcelle agricole de 13 ha « la Grande Borne », située dans la plaine de Versailles (78), a été suivie en avril2013, peu avant le semis alors qu'elle était encore en sol nu. Le drone AIRINOV® utilisé était équipé de la caméramultispectrale quadri-bande multiSPEC 4C® (550nm, 660nm, 735 nm et 790 nm) et évoluait à une altitude de 150 m.Vingt-trois placettes de contrôle au sol, réparties dans la parcelle, ont été délimitées par des cibles géolocaliséescentimétriquement par DGPS et ont fait l'objet de mesures synchrones au vol drone : mesures spectrales de terrain(ASD FieldSpec 3®), mesures de rugosité par une méthode photogrammétrique, prélèvements d'échantillons de solpour analyse de la composition chimique et de la teneur en eau. Les images obtenues d'une résolution de 15cm ont étégéoréférencées avec une précision infra-pixellaire. Les spectres de terrain ont été agrégés sur les bandes spectrales de2la multiSPEC® 4C afin de valider par régression linéaire la qualité des données de réflectance du drone. Les Robtenus, entre 0,8 et 0,9 selon les bandes, ainsi que l'erreur comprise entre 1 et 3% en réflectance, ont montrés lafiabilité du capteur multiSPEC 4C®. La teneur en CO a ensuite été estimée par régression des moindres carrés partiels(PLSR) à partir des mesures spectrales sur les 23 placettes. L'erreur quadratique moyenne de validation croisée(RMSECV) par la méthode LOO (Leave One Out) était de 1,97 g de CO par kg de sol. Un second modèle intégrant lacorrection des effets de l'humidité et de la rugosité sur la réflectance, a permis d'améliorer la qualité de la prédiction de18% avec une RMSECV de 1,61 g/kg. Le modèle a enfin été spatialisé sous SIG et comparé à de simples interpolationsspatiales des analyses de sol.

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GHANASHYAM KRISHNA, M., A. HARTRIDGE et A. K. BHATTACHARYA. « STRUCTURE AND OPTICAL PROPERTIES OF NANOCRYSTALLINE GADOLINIUM DOPED ZIRCONIA THIN FILMS ». International Journal of Modern Physics B 16, n^o 26 (20 octobre 2002) : 4017–25. http://dx.doi.org/10.1142/s0217979202014619.

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Transparent sols of crystalline gadolinium doped zirconia particles with the general formula Zr 1 - x Gd x O 2 - x/2 (where x = 0–0.20), were prepared by a hydrothermal sol-gel method using cheap inorganic precursors. The composition, structure, crystallite size and lattice parameters of the crystalline dried sol particles and heated powders were studied. Thin films were deposited on quartz substrates using a simple dipping process and the structure, composition and crystallite size found to be identical to the powders with respect to the variation in temperature. Spectral transmittance studies showed that the films were transparent in the region between 400 and 1100 nm. The refractive index increased with the increase in annealing temperature, varying between 1.56 and 1.74. Optical band gap calculations gave band of 5.52 to 5.55 eV. Refractive indices and optical band gaps were compared with those of films containing other lanthanide dopants previously reported in the literature.

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MIGNON-GRASTEAU, S., M. BOURBLANC, B. CARRE, J. Y. DOURMAD, H. GILBERT, H. JUIN, J. NOBLET et F. PHOCAS. « La réduction des rejets avicoles et porcins par la sélection ». INRAE Productions Animales 23, n^o 5 (19 décembre 2010) : 415–26. http://dx.doi.org/10.20870/productions-animales.2010.23.5.3320.

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Du fait de leur forte concentration dans certaines zones en France, les productions avicoles et porcines sont associées à de nombreux problèmes environnementaux dus à l’épandage de leurs rejets. Outre la quantité brute de rejets, leur composition, notamment en azote, phosphore et oligoéléments, est une source de pollution des eaux et des sols. Jusqu’ici, les solutions envisagées pour réduire ces rejets portaient soit sur le traitement a posteriori des rejets, soit sur la réduction des rejets en amont, essentiellement en modifiant les régimes alimentaires des animaux. La sélection d’animaux produisant moins de rejets n’était en revanche envisagée que comme un sous-produit de l’amélioration de l’efficacité alimentaire de l’animal. Le but de cette synthèse est donc de faire un tour d’horizon des différentes voies d’amélioration génétique permettant de réduire quantitativement les rejets ou d’améliorer leur composition pour produire un fertilisant organique écologique. La sélection indirecte de caractères liés à l’efficacité de la digestion ou au métabolisme de l’animal est abordée dans un premier temps. Dans un deuxième temps, nous présentons les premiers résultats montrant qu’il est possible de sélectionner directement sur la composition des rejets.

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Mitkova, Eva, Irina Stambolova, Daniela Stoyanova, Vesislava Toteva et Ognian Dimitrov. « CORRELATION BETWEEN AGING TIME PERIOD OF METAL PRECURSOR SOL – PHASE COMPOSITION AND TEXTURAL PROPERTIES OF ZIRCONIA NANOPOWDERS ». Journal of Chemical Technology and Metallurgy 59, n^o 1 (3 janvier 2024) : 223–30. http://dx.doi.org/10.59957/jctm.v59.i1.2024.26.

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This article investigates the effect of the time of aging of ZrO2 powders, obtained from zirconium butoxide sols, stabilized using complexating agents on the volume phase fractions tetragonal phase (T) and baddeleyite crystalographic phase (B), pore size distribution and pore volume. It was proved that the aging time period influences ratio between these two polymorphs of zirconia. The sample Zr3d possesses the largest content of baddeleyite phase having the greatest crystallites in comparison to another two powders. The increasing of aging period leads to a gradual increase in (101) peak intensity of T phase, while all the samples are microporous regardless of the aging time. The longest time aged sample possesses higher pore volume and higher average pore diameter than the other two powders. The physico-chemical features of the prepared ZrO2 nanosized powders could be beneficial as catalysts/photocatalysts in different catalytic reactions, corrosion inhibition particles, etc.

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Ellateif, Tayseir M. Abd, Saikat Mitra, T. Murugesan et Khairun Azizi Azizli. « Preparation and Characterization of Hydrophobic Silica Zirconium Nanoparticles ». Applied Mechanics and Materials 625 (septembre 2014) : 503–8. http://dx.doi.org/10.4028/www.scientific.net/amm.625.503.

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Hydrophobic silica nanoparticles were synthesized by silica sols modified with different percentage of zirconium sol using liquid modification. The hydrophobicity test demonstrated that silica zirconium nanoparticles are more hydrophobic as they showed 1% to 5% weight gain compared to 8% for pure silica nanoparticles. The synthesized silica nanoparticles were characterized using different techniques to investigate the effect of zirconium modification on silica nanoparticles characteristics. Structure and composition of unmodified silica nanoparticles and modified one were studied using FTIR; the results showed that the zirconium oxide was anchored to the surface of silica nanoparticles. TEM and BET analysis showed that the percentage of zirconium added to silica had distinct effect on the particle distribution and surface area of silica nanoparticles.

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Pivinskii, Yu E., et P. V. Dyakin. « Cement free castable. Part 5. CFC on alumina hydraulic binder ». NOVYE OGNEUPORY (NEW REFRACTORIES), n^o 7 (18 septembre 2020) : 25–35. http://dx.doi.org/10.17073/1683-4518-2020-7-25-35.

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Cement free castables (CFC) based on alumina hydraulic binders by the hardening mechanism are similar to low-cement castables (LCC) and ultra-low-cement castables (ULCC). They are characterized by significant strengthening in the heat treatment temperature range of 200‒300 °C and sharp softening in the 600‒1000 °C range. By introducing silica sols or microsilica into their composition, it is possible not only to reduce or eliminate the softening effect, but also to increase their strength after firing due to the process of mullite formation. Compared to LCC, CFC based on alumina binders are characterized by improved thermomechanical properties. A comparative assessment of CFC based on hydraulic binders with other types of refractory concretes is given.

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Steudel, Ralf, Thomas Göbel et Gabriele Holdt. « The Molecular Nature of the Hydrophilic Sulfur Prepared from Aqueous Sulfide and Sulfite (Selmi Sulfur Sol) ». Zeitschrift für Naturforschung B 44, n^o 5 (1 mai 1989) : 526–30. http://dx.doi.org/10.1515/znb-1989-0504.

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Hydrophilic sulfur sols prepared by reaction of aqueous sulfide and sulfite at low pH have been studied by chemical analysis, ion-pair chromatography, and reversed-phase HPLC. The approximate composition of the sol is x(NaHSO4/Na2SO4) ·ySn · zNa2SmO6 with n = 6-10 and m = 4-16. The elemental sulfur Sn accounts for 17% and the polythionate sulfur for 10% of the dry weight (sulfate: 18%). On aging of the sol at 20°C the long-chain polythionates decompose to elemental sulfur and tetrathionate as well as pentathionate. The higher chemical reactivity of this sol compared to S8 is explained by the fact that 45% of the zero oxidation state sulfur (S°) are present as non-S8 molecules.

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Balabanov, S. S., E. M. Gavrishchuk, V. V. Drobotenko, A. D. Plekhovich et E. E. Rostokina. « Effect of the composition of starting yttrium aluminum hydroxide sols on the properties of yttrium aluminum garnet powders ». Inorganic Materials 50, n^o 10 (23 août 2014) : 1030–34. http://dx.doi.org/10.1134/s0020168514100033.

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Frossard, E., M. Brossard, C. Feller et J. Rouiller. « Pouvoir fixateur vis-à-vis des ions phosphate de sols tropicaux à argile 1:1 ». Canadian Journal of Soil Science 72, n^o 2 (1 mai 1992) : 135–43. http://dx.doi.org/10.4141/cjss92-013.

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This study was aimed to clarify the influence of secondary mineral constituents (iron and aluminium oxides, kaolinite) and organic matter on the determination of the phosphate-fixing capacity (PFIX) of well-drained low-activity clay soils. This study was done on soil samples (0–2 mm) and on their particle size fractions. The phosphate-fixing capacity, estimated by an isotopic exchange method, was highly related to the total iron content of the soils. The phosphate-fixing capacity of the particle size fractions was related to their mineralogical composition, and to the organisation of their constituents. H2O2 strongly increased the phosphate-fixing capacity of the soils and of their particle size fractions. Two hypotheses were proposed to explain this. Either H2O2 caused the formation in vitro of amorphous constituents with a high phosphate fixing capacity; or the destruction of organic matter by H2O2 caused the apparition of new surfaces previously masked by organo-mineral aggregation and/or caused the apparition on surfaces of fixation sites previously occupied by organic compounds. Key words: Phosphate-fixing capacity, low-activity clay soils, particle size fractionation, mineralogy, organic matter, H2O2 effect

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Bechchari, A., A. El Aich, H. Mahyou, M. Baghdad et M. Bendaou. « Analyse de l’évolution du système pastoral du Maroc oriental ». Revue d’élevage et de médecine vétérinaire des pays tropicaux 67, n^o 4 (2 octobre 2015) : 151. http://dx.doi.org/10.19182/remvt.20557.

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Le système pastoral des hauts plateaux du Maroc oriental est caractérisé par l’étendue des parcours (3,2 millions d’hectares) et la dominance de l’élevage ovin (1,2 million de têtes). Ce travail, mené à Béni Mathar au nord et à Maâtarka au sud, traite la question des changements d’occupation des terres de parcours et de conduite des troupeaux, à partir de l’hypothèse d’une dégradation des parcours suivie d’une baisse de la pression de pâturage. Cette dynamique est perçue par l’étude de l’occupation des sols en 1970, 1988 et 2013. Les modes de conduite sont identifiés au travers d’enquêtes (85) et lors d’ateliers participatifs. L’analyse de l’occupation des sols montre la régression des bonnes formations végétales et leur substitution par des formations de moindre valeur, et une baisse des apports fourragers sur parcours. Parallèlement, on note une augmentation des effectifs d’animaux de moins en moins mobiles et de plus en plus supplémentés (20 à 40 p. 100 de satisfaction des besoins, essentiellement par l’orge et le son de blé), et un changement progressif dans la composition raciale des troupeaux en faveur de la race Ouled Djellal (à valeur commerciale compétitive) au détriment de la race locale Béni Guil. L’histoire de la société pastorale étudiée témoigne d’une capacité d’adaptation malgré les perturbations socio-économiques et climatiques relevées depuis l’indépendance. Les grands éleveurs (plus de 200 brebis) profitent davantage des pâturages et savent mieux spéculer lors de la commercialisation que les petits éleveurs (moins de 50 brebis) qui sont davantage menacés par l’abandon de l’élevage.

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