Search results for "OXIDE"
showing 10 items of 6424 documents
Functionalized poly(butylene succinate) by nitroxide radical coupling
2014
In recent years there has been a growing interest in developing sustainable alternatives to oil-based plastics. In particular, biodegradable aliphatic polyesters, such as poly(lactic acid) (PLA) and poly(butylene succinate) (PBS), are becoming increasingly important due to their valuable properties including thermoplastic processability and thermo-mechanical properties. Nonetheless, these materials present several drawbacks, such as the lack of reactive functionalities that are limiting their applications, versatility and successful use as commodity plastics. In this work it was investigated for the first time a new method of preparation of functionalized PBS by a post-polymerization approa…
INTERACTIONS BETWEEN FUNCTIONALIZED THERMOPLASTIC ELASTOMER AND LAYERED DOUBLE HYDROXIDES
2016
Results coming from rheological analysis clearly suggest that in SEBS-g-MA-based nanocomposites, containing high amount of o-LDH, the formation of strong interactions between the dispersed nanoparticles and maleic functionalities of matrix occurs. A significant modification of the rheological behaviour can be noticed due to the formation of gel-like structures.
The Effect of a Nucleation Layer on Morphology and Grain Size in MOCVD-Grown β-Ga2O3 Thin Films on C-Plane Sapphire
2022
This research is funded by the Latvian Council of Science project “Epitaxial Ga2O3 thin films as ultrawide bandgap topological transparent electrodes for ultraviolet optoelectronics” No. lzp-2020/1-0345. S.O. was supported by the European Union’s Horizon 2020 program, under Grant Agreement No. 856705 (ERA Chair “MATTER”). Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART².
Preliminary geochemical characterization of gas manifestations in North Macedonia
2020
<p>Like most of the Balkan Peninsula, North Macedonia is a geodynamically active area. As such it has many hydrothermal features and gas manifestations. Until now, no systematic study about the geochemical characterization of the geogenic gases was made before in this country. In August 2019, 24 gas samples were collected in the study area. All, except one collected at Duvalo (soil gas), are gases bubbling or dissolved in thermomineral waters (temperatures from 12 to 66 °C). They were analysed in the laboratory for their chemical (He, Ne, Ar, O<sub>2</sub> , N<sub>2</sub> , H<sub>2</sub&…
Hazard connected to endogenous gas emissions in Greece
2016
Like other geodynamically active areas, Greece is also affected by a large number of geogenic gas manifestations that occur either in form of point sources (fumaroles, mofettes, bubbling gases) or as diffuse soil gas emanations. Geogenic sources could have strong impact on human health. CO2 and H2S are the main gases responsible for acute mortality due to their asphyxiating and/or toxic properties. Gas hazard is often disregarded because in fatal episodes the death cause is often not correctly attributed. Geodynamic active areas can release geogenic gases for million years over wide areas and it is therefore important not to underestimate potential risks. A preliminary estimation of the gas…
Quantum Mechanical Co-Adsorption Modelling of Real Electrically Controlled Semiconductor Gas Sensors
2009
Abstract Co-adsorption of several gases is still a challenge due to the variety of reaction paths at the sensitive surface, and their competition for the adsorption sites. With an extended Wolkenstein model and the gas kinetic theory, we find that for specific paths their sequence of exposition has an important influence on the layer resistance as well as on the time required to achieve equilibrium. Whilst only processes that involve charge transfer can be electrically detected, a good correlation between model and electrical measurements needs weakly chemisorbed (physisorbed) layers to be taken in account. Our study presents a SnO2 nano-film sensor with electrical control electrodes expose…
Preliminary Experimental Study on Double Fuel HCCI Combustion
2015
AbstractThis paper regards an experimental study on a particular internal combustion engine process which combines Double Fuel combustion with Homogeneous Charge Compression Ignition (HCCI) using mixtures of natural gas (NG) and gasoline. The tests performed on a CFR engine demonstrate that HCCI combustion can be achieved using NG-gasoline mixtures without knocking occurrence for low to medium engine load varying the proportion between the two fuels. The main advantage of this new combustion process relies on the noticeable higher engine efficiency obtained with respect to conventional spark ignition operation, and on the strong reduction of NOX emissions.
CO2-Based Non-ionic Surfactants: Solvent-Free Synthesis of Poly(ethylene glycol)-block-Poly(propylene carbonate) Block Copolymers
2013
Copolymerization of carbon dioxide (CO2) and propylene oxide (PO) is employed to generate amphiphilic polycarbonate block copolymers with a hydrophilic poly(ethylene glycol) (PEG) block and a nonpolar poly(propylene carbonate) (PPC) block. A series of poly(propylene carbonate) (PPC) di- and triblock copolymers, PPC-b-PEG and PPC-b-PEG-b-PPC, respectively, with narrow molecular weight distributions (PDIs in the range of 1.05–1.12) and tailored molecular weights (1500–4500 g mol−1) is synthesized via an alternating CO2/propylene oxide copolymerization, using PEG or mPEG as an initiator. Critical micelle concentrations (CMCs) are determined, ranging from 3 to 30 mg L−1. Non-ionic poly(propylen…
Effect of two different tooth bleaching techniques on microhardness of giomer
2016
Background Tooth bleaching is a safe and conservative treatment modality to improve the esthetic appearance of discolored teeth. One of the problems with the use of bleaching agents is their possible effect on surface microhardness of resin-based materials. The present study was carried out to evaluate the effect of in-office and at-home bleaching on surface microhardness of giomer. Material and Methods Seventy-five disk-shaped giomer samples (Beautifil II) were prepared and cured with a light-curing unit. The samples were randomly assigned to three groups (n=25). In group 1 (control), the samples were stored in distilled water for 14 days. The samples in groups 2 and 3 underwent a bleachin…
Geogenic degassing from active tectonic areas of the Balkan Peninsula
2021
During the last decades, great interest of the scientific community has been addressed to the estimation of geogenic Carbon degassing from tectonically active areas (Tamburello et al., 2018). Due to its high solubility in water, CO2 can be dissolved, transported and released to the atmosphere by groundwater. The quantity released by such process is probably of the same order of magnitude as that directly emitted from active volcanoes. The quantification of this contribution has a substantial implication for the modelling of the global atmospheric carbon cycle. The Balkan peninsula, one of the geodynamically most active regions in Europe, is characterized by intense geogenic degassing. Until…