Search results for "Density"
showing 10 items of 4402 documents
Synthesis and characterization of ethylene-1-hexene copolymers prepared by using MgCl2(THF)2-supported Ziegler-Natta catalysts
2000
Ethylene was copolymerized with 1-hexene over vanadium (VOCl3 and VCl4) and titanium (TiCl4) catalysts supported on MgCl2(THF)2 and activated with Et2AlCl. So far these catalyst systems have not been known as initiators of ethylene-1-hexene copolymerization. The vanadium catalysts were more active than the titanium catalyst and, at identical comonomer concentrations in the feed, gave rise to a greater incorporation of 1-hexene into the copolymer. Even at relatively low fractions of 1-hexene, the MgCl2(THF)2-supported catalysts affected much the copolymer properties like density, melting point and crystallinity.
Habitat Determinants and Density of the Endemic Sicilian Rock Partridge Alectoris graeca whitakeri on Mt. Etna, Sicily, Italy
2022
The assessment of the conservation status of a species is the first step to prevent local extinction and to plan appropriate, effective and scientifically sound conservation actions, hence knowledge of the distribution, population trends and characteristics of preferred habitat is crucial for the conservation of a species. Galliformes are facing increasing threats related to overhunting, habitat loss and fragmentation, and human disturbance. The Sicilian Rock Partridge (hereafter Rock Partridge) Alectoris graeca whitakeri is a significant conservation unit endemic to Sicily (Italy) classified as Near Threatened by the IUCN due to a decreasing population. Few studies have been conducted on t…
Experimental study of $^{100}$Tc $\beta$ decay with total absorption $\gamma$-ray spectroscopy
2017
International audience; The β decay of Tc100 has been studied by using the total absorption γ-ray spectroscopy technique at the Ion Guide Isotope Separator On-Line facility in Jyväskylä. In this work the new Decay Total Absorption γ-ray Spectrometer in coincidence with a cylindrical plastic β detector has been employed. The β intensity to the ground state obtained from the analysis is in good agreement with previous high-resolution measurements. However, differences in the feeding to the first-excited state as well as weak feeding to a new level at high excitation energy have been deduced from this experiment. Theoretical calculations performed in the quasiparticle random-phase approximatio…
Détection robuste de mouvement par histogrammes quasi‐continus
2012
National audience; Dans cet article, nous proposons d'utiliser la représentation de distributions de valeurs par histogrammes quasi-continus pour réaliser une détection temps réel de mouvement dans une séquence d'images. Nous comparons les résultats de cette détection à deux méthodes de référence de la littérature.
Are all denumerable sets of numbers order-isomorphic?
2018
International audience; In this paper we study cognitive conflicts on the issue of number sets being dense, ordered and denumerable. We first provide historical-epistemological background related to these notions. Then we consider the cognitive conflicts under the lenses of concept image and concept definition, which we use to analyse empirical data collected in order to understand better the didactical and cognitive issues at stake.
Time-Frequency Characteristics of In-Home Radio Channels Influenced by Activities of the Home Occupant
2019
While aging is a serious global concern, in-home healthcare monitoring solutions are limited to context-aware systems and wearable sensors, which may easily be forgotten or ignored for privacy and comfort reasons. An emerging non-wearable fall detection approach is based on processing radio waves reflected off the body, who has no active interaction with the system. This paper reports on an indoor radio channel measurement campaign at 5.9 GHz, which has been conducted to study the impact of fall incidents and some daily life activities on the temporal and spectral properties of the indoor channel under both line-of-sight (LOS) and obstructed-LOS (OLOS) propagation conditions. The time-frequ…
B‐DNA structure and stability: the role of nucleotide composition and order
2022
Abstract We have quantum chemically analyzed the influence of nucleotide composition and sequence (that is, order) on the stability of double‐stranded B‐DNA triplets in aqueous solution. To this end, we have investigated the structure and bonding of all 32 possible DNA duplexes with Watson–Crick base pairing, using dispersion‐corrected DFT at the BLYP‐D3(BJ)/TZ2P level and COSMO for simulating aqueous solvation. We find enhanced stabilities for duplexes possessing a higher GC base pair content. Our activation strain analyses unexpectedly identify the loss of stacking interactions within individual strands as a destabilizing factor in the duplex formation, in addition to the better‐known eff…
Oligophenyls with Multiple Disulfide Bridges as Higher Homologues of Dibenzo[c,e][1,2]dithiin: Synthesis and Application in Lithium-Ion Batteries.
2020
Abstract Higher homologues of dibenzo[c,e][1,2]dithiin were synthesized from oligophenyls bearing multiple methylthio groups. Single‐crystal X‐ray analyses revealed their nonplanar structures and helical enantiomers of higher meta‐congener 6. Such dibenzo[1,2]dithiin homologues are demonstrated to be applicable to lithium‐ion batteries as cathode, displaying a high capacity of 118 mAh g−1 at a current density of 50 mA g−1.
Tailoring oxide properties: An impact on adsorption characteristics of molecules and metals
2014
Abstract Both density functional theory calculations and numerous experimental studies demonstrate a variety of unique features in metal supported oxide films and transition metal doped simple oxides, which are markedly different from their unmodified counterparts. This review highlights, from the computational perspective, recent literature on the properties of the above mentioned surfaces and how they adsorb and activate different species, support metal aggregates, and even catalyse reactions. The adsorption of Au atoms and clusters on metal-supported MgO films are reviewed together with the cluster׳s theoretically predicted ability to activate and dissociate O 2 at the Au–MgO(100)/Ag(100…
Detection of spatio-temporal local structure on seismic data
2017
For the description of the seismicity of an area, the comparison between local features of background and induced events could be a new perspective of research. In spatio-temporal point process, local second-order statistics provide information on the relationships of each event and its nearby events. In this paper, we use a test based on local indicators of spatio-temporal association (LISTA functions) for identifying different local structures comparing the two previous sets of events. We present a simulation study on the test and show the main results of the application on Greece earthquake data.