Search results for "54"

Diagnosis and therapeutic management of primary headache in an emergency setting

2013

Bridging rigidity and flexibility : modulation of supramolecular hydrogels by metal complexation

2021

The combination of complementary, noncovalent interactions is a key principle for the design of multistimuli responsive hydrogels. In this work, an amphiphilic peptide, supramacromolecular hydrogelator which combines metal-ligand coordination induced gelation and thermoresponsive toughening is reported. Following a modular approach, the incorporation of the triphenylalanine sequence FFF into a structural (C3EG ) and a terpyridine-functionalized (C3Tpy ) C3 -symmetric monomer enables their statistical copolymerization into self-assembled, 1D nanorods in water, as investigated by circular dichroism (CD) spectroscopy and transmission electron microscopy (TEM). In the presence of a terpyridine …

Long-ranged and soft interactions between charged colloidal particles induced by multivalent coions

2015

Forces between charged particles in aqueous solutions containing multivalent coions and monovalent counterions are studied by the colloidal probe technique. Here, the multivalent ions have the same charge as the particles, which must be contrasted to the frequently studied case where multivalent ions have the opposite sign as the substrate. In the present case, the forces remain repulsive and are dominated by the interactions of the double layers. The valence of the multivalent coion is found to have a profound influence on the shape of the force curve. While for monovalent coions the force profile is exponential down to separations of a few nanometers, the interaction is much softer and lo…

Radical addition to iminium ions and cationic heterocycles

2014

Carbon-centered radicals represent highly useful reactive intermediates in organic synthesis. Their nucleophilic character is reflected by fast additions to electron deficient C=X double bonds as present in iminium ions or cationic heterocycles. This review covers diverse reactions of preformed or in situ-generated cationic substrates with various types of C-radicals, including alkyl, alkoxyalkyl, trifluoromethyl, aryl, acyl, carbamoyl, and alkoxycarbonyl species. Despite its high reactivity, the strong interaction of the radical’s SOMO with the LUMO of the cation frequently results in a high regioselectivity. Intra- and intermolecular processes such as the Minisci reaction, the Porta react…

Anthropogenic soils: general aspects and features

2015

In recent decades man's role in soil formation has become a matter of great concern among soil scientists. Man is now considered a soil-forming factor and anthrosolization is recognised as a soil-forming process that consists of a collection of geomorphic and pedological processes resulting from human activities. These human activities include deep working, intensive fertilization, the addition of extraneous materials, irrigation with sediment-rich waters and wet cultivation. In this paper we review the influence of man as a soil forming factor stressing also some peculiar aspects linked to their classification.

José Capuz Mamano (1884-1964), maestro de Helena Sorolla García (1895-1975)

2014

Release of choline in the isolated heart, an indicator of ischemic phospholipid degradation and its protection by ischemic preconditioning: No eviden…

2003

Abstract The release of choline as a water-soluble product of phospholipid hydrolysis was measured in the perfusate of rat hearts to monitor ischemic membrane degradation and its protection by ischemic preconditioning (IPC). Hearts were subjected to global ischemia (GI; 30 min of no-flow) followed by 60 min of reperfusion. To induce IPC, GI was preceded by four no-flow episodes of 5 min each. Deleterious consequences of GI and reperfusion, namely coronary flow reduction, incidence of arrhythmias and release of cardiac troponin T, were significantly attenuated by IPC. The release of choline increased during reperfusion in a biphasic manner: a first phase peaked immediately after GI and was f…

Genetic diversity in populations of asexual and sexual bag worm moths (Lepidoptera: Psychidae).

2004

Abstract Background Despite the two-fold cost of sex, most of the higher animals reproduce sexually. The advantage of sex has been suggested to be its ability, through recombination, to generate greater genetic diversity than asexuality, thus enhancing adaptation in a changing environment. We studied the genetic diversity and the population structure of three closely related species of bag worm moths: two strictly sexual (Dahlica charlottae and Siederia rupicolella) and one strictly asexual (D. fennicella). These species compete for the same resources and share the same parasitoids. Results Allelic richness was comparable between the sexual species but it was higher than in the asexual spec…

Searches for small-scale anisotropies from neutrino point sources with three years of IceCube data

2015

Recently, IceCube found evidence for a diffuse signal of astrophysical neutrinos in an energy range of $60\,\mathrm{TeV}$ to the $\mathrm{PeV}$-scale. The origin of those events, being a key to understanding the origin of cosmic rays, is still an unsolved question. So far, analyses have not succeeded to resolve the diffuse signal into point-like sources. Searches including a maximum-likelihood-ratio test, based on the reconstructed directions and energies of the detected down- and up-going neutrino candidates, were also performed on IceCube data leading to the exclusion of bright point sources. In this paper, we present two methods to search for faint neutrino point sources in three years o…

Les motivations des administrateurs des coopératives : une question de gouvernance revisitée par les approches de la proximité

2016

National audience; Comprendre les motivations des acteurs de gouvernance peut contribuer à favoriser la réussite et la pérennité de l’entreprise. L’article s’intéresse aux motivations des administrateurs pour mieux appréhender ce qui les incite à exercer pleinement leur rôle et à s’impliquer pour contribuer à l’atteinte des objectifs de la société. L’étude porte sur un type spécifique d’organisation, les coopératives, dont l’engagement des membres est souvent cité comme particulièrement fort. Les approches de la proximité sont mobilisées pour analyser les quatre principales motivations identifiées chez les administrateurs des coopératives : l’envie d’accroître leurs compétences, celle de dé…