Search results for "DIOXIDE"
showing 10 items of 1250 documents
Surface Morphology of Single and Multi-Layer Silicon Nitride Dielectric Nano-Coatings on Silicon Dioxide and Polycrystalline Silicon
2019
Silicon nitride (Si3N4) in a form of single and multi-layer nanofilms is proposed to be used as a dielectric layer in nanocapacitors for operation in harsh environmental conditions. Characterization of surface morphology, roughness and chemical bonds of the Si3N4 coatings has an important role in production process as the surface morphology affects the contact surface with other components of the produced device. Si3N4 was synthesized by using low pressure chemical vapour deposition method and depositing single and multi-layer (3 – 5 layers) nanofilms on SiO2 and polycrystalline silicon (PolySi). The total thickness of the synthesized nanofilms was 20 – 60 nm. Surface morphology was investi…
One-dimensional nanostructures of lead and lead dioxide for application in lead-acid batteries
2010
Fabrication of Pb and PbO2 nanostructures was undertaken with the aim of building low cost lead acid micro-batteries with high performance. Despite environmental problems and the relatively low specific energy in comparison with other galvanic generators, lead acid batteries are still extensively used in the field of energy accumulation, owing to a well known and reliable technology. Thus, it is of high technological interest to develop procedures for fabricating these devices at a micrometer scale or less. PbO2 nanowires were grown in different electrochemical deposition conditions leading to pure -PbO2, pure -PbO2 and mixture [1-2]. Several parameters, like temperature, electrolyte…
Experimental evidence for a liquid-liquid crossover in deeply cooled confined water.
2014
International audience; In this work we investigate, by means of elastic neutron scattering, the pressure dependence of mean square displacements (MSD) of hydrogen atoms of deeply cooled water confined in the pores of a three-dimensional disordered SiO 2 xerogel; experiments have been performed at 250 and 210 K from atmospheric pressure to 1200 bar. The " pressure anomaly " of supercooled water (i.e., a mean square displacement increase with increasing pressure) is observed in our sample at both temperatures; however, contrary to previous simulation results and to the experimental trend observed in bulk water, the pressure effect is smaller at lower (210 K) than at higher (250 K) temperatur…
The boson peak of deeply cooled confined water reveals the existence of a low-temperature liquid-liquid crossover.
2014
International audience; The Boson peak of deeply cooled water confined in the pores of a silica xerogel is studied by inelastic neutron scattering at different hydration levels to separate the contributions from matrix, water on the pore surfaces and "internal" water. Our results reveal that at high hydration level, where the contribution from internal water is dominant, the temperature dependence of the Boson peak intensity shows an inflection point at about 225 K. The complementary use of differential scanning calorimetry to describe the thermodynamics of the system allows identifying the inflection point as the signature of a water liquid-liquid crossover.
Biogenic Fenton process - A possible mechanism for the mineralization of organic carbon in fresh waters.
2020
To explore the mechanisms that mineralize poorly bioavailable natural organic carbon (OC), we measured the mineralization of OC in two lake waters over long-term experiments (up to 623 days) at different pH and iron (Fe) levels. Both the microbial and photochemical mineralization of OC was higher at pH acidified to 4 than at the ambient pH 5 or an elevated pH 6. During 244 days, microbes mineralized up to 60% of OC in the 10-mu m filtrates of lake water and more than 27% in the 1-mu m filtrates indicating that large-sized microbes/grazers enhance the mineralization of OC. A reactivity continuum model indicated that the acidification stimulated the microbial mineralization of OC especially i…
Natural acidification changes the timing and rate of succession, alters community structure, and increases homogeneity in marine biofouling communiti…
2017
Ocean acidification may have far-reaching consequences for marine community and ecosystem dynamics, but its full impacts remain poorly understood due to the difficulty of manipulating pCO2 at the ecosystem level to mimic realistic fluctuations that occur on a number of different timescales. It is especially unclear how quickly communities at various stages of development respond to intermediate-scale pCO2 change and, if high pCO2 is relieved mid-succession, whether past acidification effects persist, are reversed by alleviation of pCO2 stress, or are worsened by departures from prior high pCO2 conditions to which organisms had acclimatized. Here, we used reciprocal transplant experiments al…
Plasma membrane glycoproteins covalently bound to silica beads as a model for molecular studies of cell-cell interactions in culture.
1987
Abstract In previous studies, we have shown that plasma membrane glycoproteins are of major importance in the density-dependent regulation of growth of normal diploid fibroblasts. Due to the hydrophobic portions of these molecules, functional studies in cell culture are often diffucult to perform and to interpret. Specially, the addition of these molecules in soluble form to cell culture, after depletion of detergents needed for their solubilization, leads to aggregation and internalization. Therefore, we developed a method for the covalent immobilization of the solubilized plasma membrane proteins to derivatized silica beads for further investigations on the molecular nature of the active …
Effect of low SO2 postharvest treatment on quality parameters of ‘Italia’ table grape during prolonged cold storage
2018
Table grape is a non-climacteric fruit with a low rate of physiological activity, very sensitive to water loss and fungal infection (Botrytis cinerea) during postharvest handling and cold storage. Gray mold is the most aggressive postharvest disease, because of its ability to develop at low temperatures, for that reason, it is standard practice to fumigate with sulfur dioxide (SO2) immediately after packing. ‘Italia’ table grape boxes were stored at 2°C for 4 months in a storage room with low concentrations of SO2 (0.20%) to extend their postharvest shelf life. Every 15 days, a sample of ‘Italia’ table grapes boxes was moved to 20°C for 3 days for the shelf life simulation. During storage, …
Mesoporous Silica-Based Materials with Bactericidal Properties
2019
[EN] Bacterial infections are the main cause of chronic infections and even mortality. In fact, due to extensive use of antibiotics and, then, emergence of antibiotic resistance, treatment of such infections by conventional antibiotics has become a major concern worldwide. One of the promising strategies to treat infection diseases is the use of nanomaterials. Among them, mesoporous silica materials (MSMs) have attracted burgeoning attention due to high surface area, tunable pore/particle size, and easy surface functionalization. This review discusses how one can exploit capacities of MSMs to design and fabricate multifunctional/controllable drug delivery systems (DDSs) to combat bacterial …
Assessment of the cardiostimulant action of propionyl-L-carnitine on chronically volume-overloaded rat hearts.
1993
Chronic volume overload was induced in young rats of Wistar strain by surgical opening of the aorto-caval fistula. Three months later, during in vitro perfusion with exogenous palmitate, left ventricular function and energy turnover (QO2) of hypertrophied hearts were severely depressed. This seemed to be related to impaired long-chain fatty acid utilization, as reflected by decreased 14CO2 production from U-14C-palmitate and decreased tissue levels of L-carnitine. Another group of rats exposed to chronic volume overload was pretreated for 2 weeks before sacrifice with propionyl-L-carnitine (250 mg/kg/day), and the hearts were perfused with 1.2 mM palmitate and 10 mM propionyl-L-carnitine. I…