Search results for "INTERFACE"
showing 10 items of 2139 documents
Study of the phase composition of iron-containing Langmuir-Blodgett layers before and after thermal and chemical treatment
1992
Iron-containing Langmuir–Blodgett mono- and multilayers were prepared by depositing ferric stearate onto silicon wafers. Particular care should be taken in order to avoid the presence of alkali ions, which may replace iron ions in the deposited film. By a subsequent heating in air, the fatty acid chains were thermodesorbed. This results in a rather homogeneous coating of the samples by an iron oxide, most probably in the form of crystalline and amorphous γ-FeOOH, as found by conversion electron Mossbauer, photoelectron and microprobe studies. By a subsequent heating in hydrogen gas or exposure to nascent hydrogen, a partial reduction of the iron oxide layer is possible up to the metallic st…
Hydrogen induced metallization of ZnO (11̅00) surface: Ab initio study
2014
Abstract Results of first principles hybrid calculations are presented for hydrogen atoms adsorbed upon non-polar ZnO (1100) surface. The energy of surface atomic relaxation, H adsorption energy, electronic density redistribution and modification of the electronic structure are discussed. It is shown that hydrogen is adsorbed mainly on the surface oxygen ions and forms a strong bonding with them (2.7 eV). Adsorption of hydrogen on the surface zinc ions is energetically unfavorable (− 4.4 eV). It also shown that surface hydrogen atoms are very shallow donors, thus, contributing to the electronic conductivity, and ZnO metallization.
A conceptual dynamic vegetation-soil model for arid and semiarid zones
2007
Plant ecosystems in arid and semiarid zones show high complexity from the point of view of water resources, since they depend on water availability to carry out their vital processes. In these climates, water stress is the main factor controlling vegetation development. The available water in the system results from a water balance where the soil, vegetation and the atmosphere are the key issues; but it is the vegetation which modulates (to a great extent) the total balance of water and the mechanisms of the feedback between soil and atmosphere, being the knowledge about soil moisture quite relevant for assessing available water and, as a consequence, for growth and plants maintenance and t…
Les Hypogées d'Arles-Fontvieille et leur environnement : nouvelles perceptions, nouvelles perspectives
2014
Due to their unique architecture and the exceptional dimensions of the largest monument in the group, the Arles-Fontvieille hypogea are among the most remarkable megalithic monuments in Europe and the western Mediterranean region. A collective research program was launched in 2013 to study these well-known monuments which have, paradoxically, been the subject of relatively few field studies since the 19th century. The research program consisted of an inventory and analysis of the grave goods and associated artefacts, as well as a number of field studies providing an improved archaeological context of a megalithic group too often thought of only in terms of funerary monuments. Various traces…
Handover performance in the IEEE 802.16 mobile networks
2012
The IEEE 802.16 standard provides a full mobility support for stations moving across cell borders. In addition, the WiMAX Forum Network Working Group defines a set of procedures to support handovers in the mobile access network. One of the main characteristics of mobility support is fully controlled and optimized handover (HO), in which a mobile station (MS) migrates from the air interface of one base station (BS) to another one. It is vital to keep the BS transition phase as short as possible to decrease delays and data loss, which is especially crucial for real-time applications, such as VoIP. In this paper we analyze ASN-anchored mobility performance and provide advisable handover relate…
Experimental Assessment of the Backoff Behavior of Commercial IEEE 802.11b Network Cards
2007
It has been observed that different IEEE 802.11 commercial cards produced by different vendors experience different performance, either when accessing alone the channel, as well as when competing against each other. These differences persist also when thorough measurement methodologies (such as RF shielding, laptop rotation, etc) are applied, and alignment of the environmental factors (same laptop models, traffic generators, etc) is carried out. This paper provides an extensive experimental characterization of the backoff operation of six commercial NIC cards. It suggests a relevant methodological approach, namely a repeatable, well defined, set of experiments, for such a characterization. …
Correlation between optical properties and barrier composition in InxGa1−xP/GaAs quantum wells
1998
9 páginas, 11 figuras.
Gated mesoporous silica nanoparticles for the controlled delivery of drugs in cancer cells
2015
In recent years, mesoporous silica nanoparticles (MSNs) have been used as effective supports for the development of controlled-release nanodevices that are able to act as multifunctional delivery platforms for the encapsulation of therapeutic agents, enhancing their bioavailability and overcoming common issues such as poor water solubility and poor stability of some drugs. In particular, redox-responsive delivery systems have attracted the attention of scientists because of the intracellular reductive environment related to a high concentration of glutathione (GSH). In this context, we describe herein the development of a GSH-responsive delivery system based on poly(ethylene glycol)- (PEG-)…
Poly(N-isopropylacrylamide)-gated Fe3O4/SiO2 core shell nanoparticles with expanded mesoporous structures for the temperature triggered release of ly…
2015
Core-shell nanoparticles comprised of Fe3O4 cores and a mesoporous silica shell with an average expanded pore size of 6.07 nm and coated with a poly(N-isopropylacrylamide) (PNIPAM) layer (CS MSNs EP PNIPAM) were prepared and characterized. The nanoparticles was loaded with (Ru(bipy)3 2+) dye or an antibacterial enzyme, lysozyme, to obtain CS MSNs EP PNIPAM Ru(bipy)3 2+ and CS MSNs EP PNIPAM Lys, respectively. The lysozyme loading was determined to be 160 mg/g of nanoparticle. It was seen that Ru(bipy)3 2+ and lysozyme release was minimal at a room temperature of 25 ºC while at physiological temperature (37 º C), abrupt release was observed. The applicability of the CS MSNs EP PNIPAM Lys was…
Depth profiles of aggregate centers and nanodefects in LiF crystals irradiated with 34 MeV 84Kr, 56 MeV 40Ar and 12 MeV 12C ions
2018
I. Manika, J. Maniks and R. Zabels acknowledge the national project IMIS2. A. Dauletbekova, A. Akilbekov, M. Zdorovets and A. Seitbayev acknowledge the GF AP05134257of Ministry of Education and Science the Republic of Kazakhstan.