Search results for "complex"
showing 10 items of 5889 documents
An ab initio potential energy surface for the C2H2-N2 system
2012
International audience; An ab initio potential energy surface determined at the CCSD(T) level of theory is presented for the van der Waals complex C2H2-N2. Additional calculations performed with the HF- and DFT-SAPT methods compare well with the CCSD(T) results and allow a better understanding of the main features of this interaction potential surface. An expansion of this surface over spherical harmonics has also been performed. The global energy minimum of the complex is obtained for the linear conformation. The T conformations are the least attractive. Such characteristics mainly arise because of the variation, in sign and in absolute value of the electrostatic energy between all these c…
TORC1 coordinates the conversion of Sic1 from a target to an inhibitor of cyclin-CDK-Cks1
2017
Eukaryotic cell cycle progression through G(1)-S is driven by hormonal and growth-related signals that are transmitted by the target of rapamycin complex 1 (TORC1) pathway. In yeast, inactivation of TORC1 restricts G(1)-S transition due to the rapid clearance of G(1) cyclins (Cln) and the stabilization of the B-type cyclin (Clb) cyclin-dependent kinase (CDK) inhibitor Sic1. The latter mechanism remains mysterious but requires the phosphorylation of Sic1-Thr(173) by Mpk1 and inactivation of the Sic1-pThr(173)-targeting phosphatase (PP2A(Cdc55)) through greatwall kinase-activated endosulfines. Here we show that the Sic1-pThr(173) residue serves as a specific docking site for the CDK phospho-a…
TORC1 controls G1–S cell cycle transition in yeast via Mpk1 and the greatwall kinase pathway
2015
The target of rapamycin complex 1 (TORC1) pathway couples nutrient, energy and hormonal signals with eukaryotic cell growth and division. In yeast, TORC1 coordinates growth with G1–S cell cycle progression, also coined as START, by favouring the expression of G1 cyclins that activate cyclin-dependent protein kinases (CDKs) and by destabilizing the CDK inhibitor Sic1. Following TORC1 downregulation by rapamycin treatment or nutrient limitation, clearance of G1 cyclins and C-terminal phosphorylation of Sic1 by unknown protein kinases are both required for Sic1 to escape ubiquitin-dependent proteolysis prompted by its flagging via the SCFCdc4 (Skp1/Cul1/F-box protein) ubiquitin ligase complex.…
Distansescharella seguenzai Cipolla, 1921 (Bryozoa, Cheilostomata),nouvelles données morphologiques et écologiques tirées de spécimens fossiles (Mioc…
1989
The cribrimorph Distansescharella seguenzai Cipolla,,1921, described from the Pliocene of Sicily has been rediscovered in fossil deposits (Messinian of Western Algeria, and Lower Pliocene of Calabria, Southern Italy) and in Recent Mediterranean material (Straits of Gibraltar, Alboran Sea, Gulf of Tripoli). Its morphology is demonstrated by SEM study of living specimens. In spite of some differences with the type-species of Distansescharella D'Orbigny revealed by examination of its neotype, the generic status of D. seguenzai is confirmed. An ecological analysis of the Recent and fossil assemblages including D. seguenzai is made by considering the zoarial growth forms and the potential habita…
COVARIANCE AND CORRELATION ESTIMATORS IN BIPARTITE SYSTEMS
2017
We present a weighted estimator of the covariance and correlation in bipartite complex systems with a double layer of heterogeneity. The advantage provided by the weighted estimators lies in the fact that the unweighted sample covariance and correlation can be shown to possess a bias. Indeed, such a bias affects real bipartite systems, and, for example, we report its effects on two empirical systems, one social and the other biological. On the contrary, our newly proposed weighted estimators remove the bias and are better suited to describe such systems.
Evaluation of Ligno Boost™ softwood kraft lignin epoxidation as an approach for its application in cured epoxy resins
2018
Abstract In this study, modification of LignoBoost™ softwood kraft lignin with epichlorhydrin in water-organic solvents media was realized. Lignin-based epoxy resins were obtained by two ways: acetone extraction of glycidylated lignin or glycidylation of the acetone soluble lignin fraction. The effect of glycidylation regimes on the yields of acetone soluble fractions, their functional composition and physical-chemical characteristics was investigated using wet chemistry methods, FTIR spectroscopy, size exclusion chromatography (SEC) and differential scanning calorimetry (DSC). The positive effect of the biphasic phase transfer catalytic system – KOH/quaternary ammonium salt – on glycidylat…
Experimental demonstration of phase bistability in a broad-area optical oscillator with injected signal
2015
We demonstrate experimentally that a broad-area laserlike optical oscillator (a nondegenerate photorefractive oscillator) with structured injected signal displays two-phase patterns. The technique [de Valc\'arcel and Staliunas, Phys. Rev. Lett. 105, 054101 (2010)] consists in spatially modulating the injection, so that its phase alternates periodically between two opposite values, i.e., differing by $\ensuremath{\pi}$.
The [Fe(etz)6](BF4)2 Spin-Crossover System - Part Two: Hysteresis in the LIESST Regime
1996
In the [Fe(etz)6](BF4)2 spincrossover system the iron(II) complexes occupy two nonequivalent lattice sites, sites A and B. Complexes on site A show a thermal high-spin (HS) low-spin (LS) transition at 105 K, whereas complexes on site B remain in the HS state down to 10 K. Complexes on both sites exhibit light-induced spin state conversions (LIESST) at 20 K: LS HS on site A with = 514.5 nm, and HS LS on site B with = 820 nm. The relaxation processes subsequent to the HS LS conversion on site B reveal a light-induced HSLS bistability for the complexes on site B at 70 K. The bistability as well as the absence of a thermal spin transition on site B are attributed to a thermal hysteresis for the…
The Cryptocercus punctulatus species complex (Dictyoptera: Cryptocercidae) in the eastern United States: comparison of cuticular hydrocarbons, chromo…
2008
1055-7903; The goal of the current study was to determine if cuticular hydrocarbons could be used to empirically delimit taxa within the Cryptocercus punctulatus species complex in the eastern United States. Cockroaches were collected from rotting logs in 22 locations across four states. Hydrocarbon phenotypes and two mitochondrial (16S and COII) genes and one nuclear (ITS2) gene were independently analyzed to determine their relationship with chromosome number. Five distinct hydrocarbon phenotypes were found, but these were only partly congruent with chromosome number and thus with purported species descriptions. Molecular and cuticular hydrocarbon data each indicate that Cryptocercus with…
Essential norm estimates for composition operators on BMOA
2013
Abstract We provide two function-theoretic estimates for the essential norm of a composition operator C φ acting on the space BMOA; one in terms of the n-th power φ n of the symbol φ and one which involves the Nevanlinna counting function. We also show that if the symbol φ is univalent, then the essential norm of C φ is comparable to its essential norm on the Bloch space.