Search results for "etica."
showing 10 items of 13546 documents
Asymptotic potentials and rate constants in the adiabatic capture centrifugal sudden approximation for X + OH(X-2 Pi) -> OX + H(S-2) reactions where …
2012
International audience; New long-range multipolar coefficients for the X + OH(X-2 Pi) interactions, where X = O(P-3), S(P-3) and N(S-4), are given here. They have been evaluated on the basis or monomer properties of the atoms and OH such as the dipole and quadrupole moments, and the static and dynamic polarizabilities. Each matrix element of the 18 x 18 (8 x 8 for N + OH) quasi-degenerate asymptotic potentials has been built up by means of the perturbation theory up to second order including or not the fine-structure of O, S and OH. The adiabatic potentials, obtained after diagonalization of the full matrix, show many crossings and complex behaviors near the asymptotes. Using the entrance c…
Coupling between bulk- and surface chemistry in suspensions of charged colloids
2013
The ionic composition and pair correlations in fluid phases of realistically salt-free charged colloidal sphere suspensions are calculated in the primitive model. We obtain the number densities of all ionic species in suspension, including low-molecular weight microions, and colloidal macroions with acidic surface groups, from a self-consistent solution of a coupled physicochemical set of nonlinear algebraic equations and non-mean-field liquid integral equations. Here, we study suspensions of colloidal spheres with sulfonate or silanol surface groups, suspended in demineralized water that is saturated with carbon dioxide under standard atmosphere. The only input required for our theoretical…
Theoretical study of the NH tautomerism in free base porphyrin
1997
Abstract The NH tautomerism of free base porphyrin is investigated at the semiempirical spin-unrestricted AM1 (UAM1) and ab initio RHF/3-21G levels. The UAM1 method provides delocalized geometries for all stationary structures without imposing any symmetry constraint. RHF/3-21G geometry optimizations have to be performed under symmetry restrictions to ensure that realistic delocalized structures are obtained. Both the semiempirical and the ab initio calculations predict that the interconversion between trans tautomers proceeds in an asynchronous two-step process via intermediate cis tautomers. The cis tautomers are characterized as minima in the potential energy surface and are 8–10 kcal m…
Crystal structure of sinhalite MgAlBO4 under high pressure
2015
We report on high-pressure angle-dispersive X-ray diffraction data up to 27 GPa for natural MgAlBO4 sinhalite mineral and ab initio total energy calculations. The experimental bulk modulus of sinhalite is B-0 = 171(3) GPa with a first-pressure derivative of B-0' = 4.2(3). A comparison with other olivine-type compounds shows that the value for B0 is 27% larger than that of Mg2SiO4 forsterite and 29% smaller than that of Al2BeO4 chrysoberyl. These differences are interpreted, on the basis of our ab initio calculations, in terms of the relative incompressibility of Al-O bonds in AlO6 octahedra (with a calculated bulk modulus of 250(1) GPa) as compared to Mg-O bonds in MgO6 octahedra (with a ca…
Ab Initio Study on the Mechanism of the Reactions of the Nitrate Radical with Haloalkenes: 1,2-Dichloroethene, 1,1-Dichloroethene, Trichloroethene, …
2000
A general mechanism for the reactions of the NO3 radical with 1,2-dichloroethene, 1,1-dichloroethene, trichloroethene, and tetrachloroethene is proposed from ab initio DFT calculations. The calculated mechanism shows three main parallel reaction pathways. For the systems where the two carbon atoms are differently substituted, the study includes both the attacks with Markownikoff and contra-Markownikoff orientation. The first reaction pathway leads to the formation of an epoxide along with the NO2 radical, the second one to the formation of carbonyl compounds, and the third one leads, through the cleavage of the C−C bond, to the formation of carbonyl compounds with a lower number of carbon a…
Abel transforms with low regularity with applications to X-ray tomography on spherically symmetric manifolds
2017
We study ray transforms on spherically symmetric manifolds with a piecewise $C^{1,1}$ metric. Assuming the Herglotz condition, the X-ray transform is injective on the space of $L^2$ functions on such manifolds. We also prove injectivity results for broken ray transforms (with and without periodicity) on such manifolds with a $C^{1,1}$ metric. To make these problems tractable in low regularity, we introduce and study a class of generalized Abel transforms and study their properties. This low regularity setting is relevant for geophysical applications.
Automorphisms of hyperelliptic GAG-codes
2009
Abstract We determine the n –automorphism group of generalized algebraic-geometry codes associated with rational, elliptic and hyperelliptic function fields. Such group is, up to isomorphism, a subgroup of the automorphism group of the underlying function field.
Genetic Engineering Strategies for Abiotic Stress Tolerance in Plants
2015
Crop plants are affected by a variety of abiotic stresses such as salinity, drought, extreme temperatures, and oxidative stress and cause a significant yield loss (more than 50 %). In the near future, these abiotic stresses might increase because of global climate change. Abiotic stresses lead to dehydration or osmotic stress through reduced availability of water for vital cellular functions and maintenance of turgor pressure and also result in high production of reactive oxygen species (ROS). Plants are evolved with various mechanisms such as changes in cellular and metabolic processes to cope with the stress condition. Recent developments in molecular genetics have contributed greatly to …
Polyamines in Developing Stress-Resistant Crops
2012
F.Marco,R.Alcazar,T.Altabella,P.Carrasco,SarvajeetSinghGill,NarendraTuteja,andA.F. TiburcioPolyamines (PAs) are small protonated compounds with key roles in plant devel-opmentandphysiologicalprocesses.PAsmayalsofunctionasstressmessengersinplant responses to different stress signals. Recent studies using exogenous appli-cation of polyamines and more contemporary genetic manipulation of polyaminelevelsincropsandmodelspeciespointtotheirinvolvementinstressprotection.Thedifferentmechanismsbywhichpolyaminesexerttheirfunctionsarepresentlybeingunraveledandinvolvedifferentmodesofactionthataresummarizedinthischapter.Polyamines are integrated with other stress-related hormone pathways, such asabscisic…
Quando i corpi svelano lo spazio
2020
Living means transfiguring the place and loading it with meanings that transcend its pure objectivity, allowing our body to feel itself among "its things", close to itself. The path of "transfiguration" inherent in living interprets the complementarity between man and his environment and reveals the poetic capacity of architecture. Thus, it may be interesting to understand how the interaction between body and space can make us regain possession of the most problematic places, within a mental and transcendent dimension.