Search results for "Relative stability"
showing 7 items of 7 documents
Computational Study of Nanosized Drug Delivery from Cyclodextrins, Crown Ethers and Hyaluronan in Pharmaceutical Formulations
2015
Abstract The problem in this work is the computational characterization of cyclodextrins, crown ethers and hyaluronan (HA) as hosts of inclusion complexes for nanosized drug delivery vehicles in pharmaceutical formulations. The difficulty is addressed through a computational study of some thermodynamic, geometric and topological properties of the hosts. The calculated properties of oligosaccharides of D-glucopyranoses allow these to act as co-solvents of polyanions in water. In crown ethers, the central channel is computed. Mucoadhesive polymer HA in formulations releases drugs in mucosas. Geometric, topological and fractal analyses are carried out with code TOPO. Reference calculations are…
The Pd3(dppm)3(CO)n clusters (n = 1-,2-); rare cases of anionic palladium species.
2010
Two novel anionic palladium clusters, Pd(3)(dppm)(3)(CO)(n-) (Pd(3)(n); n = 1-,2-) were electrochemically generated from the dicationic cluster Pd(3)(2+) in 0.2 M THF/Bu(4)NPF(6)via two first consecutive reversible 1-electron reductions (Pd(3)(2+) + 1 e(-) ⇌ Pd(3)(+), -0.210, and Pd(3)(+) + 1 e(-) ⇌ Pd(3)(0), -0.470 V vs. SCE) followed by two others at -2.350 (Pd(3)(0) + 1 e(-) ⇌ Pd(3)(1-), reversible) and at -2.690 V vs. SCE (Pd(3)(1-) + 1 e(-) ⇌ Pd(3)(2-), irreversible). The chemical stability and instability, respectively, of the Pd(3)(dppm)(3)(CO)(n-) clusters (Pd(3)(n); n = 1-,2-) at the time scale of the electrochemical experiments were addressed by DFT computations. Indeed, geometry …
Orthodontic treatment stability predictors: A retrospective longitudinal study
2016
ABSTRACTObjective: To examine medium- to long-term orthodontic treatment stability and its possible association with certain variables.Materials and Methods: In a retrospective longitudinal study of 70 postretention patients, the Peer Assessment Rating (PAR) index was measured at the start (T1) and end (T2) of treatment and between 4 and 10 years afterwards (T3). The stability was considered absolute when the T2 and T3 values were identical and relative when the difference was within the ±5 range.Results: Among the 70 patients, 65.8% were female and 34.2% were male. Their mean age was 14.5 years. The mean treatment length was 2.4 years. The mean retention phase was 3.3 years. The mean pre- …
Phase competition in (La1 − c,Src)CoO3solid solutions:ab initiothermodynamic study
2013
Statistical thermodynamics and density functional theory (DFT) formalisms are combined to analyze the phase competition of energetically preferable phases in (La1 − c,Src)CoO3 solid solutions upon LaCoO3 doping with Sr. La/Sr sublattice in ABO3 perovskite structure is considered as immersed in the field of CoO3 units and the superstructures that are stable with respect to the formation of antiphase domains are analyzed. The concentration-dependent energy parameters determining the relative stability of the cubic superstructures (phases) are extracted. This allows us calculations of concentration- and temperature dependences of the long-range order (LRO) parameters for different phases. The …
Tendencies in paleontological practice when defining species, and consequences on biodiversity studies
2005
The exploration of evolutionary patterns over geological time has recently received new impetus from the development of morphological disparity as a new biodiversity metric alongside taxonomic diversity. Clade dynamics can be analyzed by comparing and contrasting these two metrics. Like any metrics based on sampling, quantification, and naming, taxonomic diversity and morphological disparity are not free from bias. The long use of taxonomic diversity has prompted many studies of bias and its effects, whereas bias affecting morphological disparity has only been summarily explored. This is particularly so for the effect of the growth of knowledge over paleontographical time (i.e., historical …
Thermodynamic properties of neutral and charged oxygen vacancies in BaZrO3 based on first principles phonon calculations.
2015
The structural, electronic and thermodynamic properties of neutral and positively doubly charged oxygen vacancies in BaZrO3 are addressed by first principles phonon calculations. The calculations are performed using two complementary first principles approaches and functionals; the linear combination of atomic orbitals (LCAO) within the hybrid Hartree–Fock and density functional theory formalism (HF-DFT), and the projector augmented plane wave approach (PAW) within DFT. Phonons are shown to contribute significantly to the formation energy of the charged oxygen vacancy at high temperatures (∼1 eV at 1000 K), due to both its large distortion of the local structure, and its large negative form…
Clinical severity and molecular characteristics of circulating and emerging rotaviruses in young children attending hospital emergency departments in…
2016
International audience; Group A rotavirus (RVA) is the leading cause of acute gastroenteritis in young children worldwide. A prospective surveillance network has been set up to investigate the virological and clinical features of RVA infections and to detect the emergence of potentially epidemic strains in France. From 2009 to 2014, RVA-positive stool samples were collected from 4800 children <5 years old attending the paediatric emergency units of 16 large hospitals. Rotaviruses were then genotyped by RT-PCR with regard to their outer capsid proteins VP4 and VP7. Genotyping of 4708 RVA showed that G1P[8] strains (62.2%) were predominant. The incidence of G9P[8] (11.5%), G3P[8] (10.4%) and …