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81.
Viorel Vjitu Vjitu 《Indagationes Mathematicae》2007,18(3):471-477
We give a separation theorem for (q, n - q)-coronas improving a recent result due to Laurent-Thiébaut and Leiterer. 相似文献
82.
In this Letter we develop a general procedure leading from a Mourre-type estimation for a given self-adjoint operator H to a Hardy-type weighted inequality. We use this method in order to prove exponential decay for eigenvectors of a large class of perturbations of operators of convolution with bounded analytic functions. 相似文献
83.
We consider the classical Gurtin–MacCamy system describing the growth and spread of an age structured population and show
that the steady states are actually stabilizable by a controller v = v(a, t) acting on an age interval [a
1, a
2]. 相似文献
84.
A system of third order differential equations, whose coefficients do not depend explicitly on time, can be viewed as a third
order vector field, which is called a semispray, and lives on the second order tangent bundle. We prove that a regular second
order Lagrangian induces such a semispray, which is uniquely determined by two associated Poincaré-Cartan one-forms. To study
the geometry of this semispray, we construct a horizontal distribution, which is a Lagrangian subbundle for an associated
Poincaré-Cartan two-form. Using this semispray and the associated nonlinear connection we define dynamical covariant derivatives
of first and second order. With respect to this, the second order dynamical derivative of the Lagrangian metric tensor vanishes. 相似文献
85.
86.
87.
Silaghi-Dumitrescu R 《Inorganic chemistry》2004,43(12):3715-3718
Nitrite reduction by cytochrome cd(1) nitrite reductase (cd(1)NIR) is currently accepted to involve coordination of the nitrite nitrogen atom to the ferrous d(1) heme. Here, density functional theory results are reported on the previously unexplored O-binding of nitrite to ferrous and ferric cd(1)NIR. Although the N-isomer (nitro) is energetically favored over the O-nitrite (nitrito), even one single strong hydrogen bond may provide the energy required to put the two isomers on level terms. When hydrogen bonding existent at the cd(1)NIR active site is accounted for in the computational model, the O-nitrite isomer is found to spontaneously protonate and thus yield a ferric-hydroxo species, liberating nitric oxide. An O-nitrite ferrous cd(1)NIR complex appears to be an energetically feasible intermediate for nitrite reduction. O-Coordination would offer an advantage since the end product of nitrite reduction would be a ferric-hydroxo/water complex, rather than the more kinetically inert iron-nitrosyl complex implied by the N-nitrite mechanism. 相似文献
88.
Mihai Andrei Raluca Paula Vacaru Anca Coricovac Radu Ilinca Andreea Cristiana Didilescu Ioana Demetrescu 《Molecules (Basel, Switzerland)》2021,26(9)
Dental pulp vitality is a desideratum for preserving the health and functionality of the tooth. In certain clinical situations that lead to pulp exposure, bioactive agents are used in direct pulp-capping procedures to stimulate the dentin-pulp complex and activate reparative dentinogenesis. Hydraulic calcium-silicate cements, derived from Portland cement, can induce the formation of a new dentin bridge at the interface between the biomaterial and the dental pulp. Odontoblasts are molecularly activated, and, if necessary, undifferentiated stem cells in the dental pulp can differentiate into odontoblasts. An extensive review of literature was conducted on MedLine/PubMed database to evaluate the histological outcomes of direct pulp capping with hydraulic calcium-silicate cements performed on animal models. Overall, irrespective of their physico-chemical properties and the molecular mechanisms involved in pulp healing, the effects of cements on tertiary dentin formation and pulp vitality preservation were positive. Histological examinations showed different degrees of dental pulp inflammatory response and complete/incomplete dentin bridge formation during the pulp healing process at different follow-up periods. Calcium silicate materials have the ability to induce reparative dentinogenesis when applied over exposed pulps, with different behaviors, as related to the animal model used, pulpal inflammatory responses, and quality of dentin bridges. 相似文献
89.
Mantz YA Gerard H Iftimie R Martyna GJ 《Journal of the American Chemical Society》2004,126(13):4080-4081
The cis-trans isomerization of N-methylacetamide, a molecular model of the polypeptide chain, is examined via umbrella sampling Car-Parrinello MD and classical MD, in both gas and solution phases at 300 K. A new analysis of the C(O)-N bond interconversion and a full examination of the solvent shell structure are presented. 相似文献