Search results for "Statics"
showing 10 items of 141 documents
The route to protein aggregate superstructures: Particulates and amyloid-like spherulites.
2015
AbstractDepending on external conditions, native proteins may change their structure and undergo different association routes leading to a large scale polymorphism of the aggregates. This feature has been widely observed but is not fully understood yet. This review focuses on morphologies, physico-chemical properties and mechanisms of formation of amyloid structures and protein superstructures. In particular, the main focus will be on protein particulates and amyloid-like spherulites, briefly summarizing possible experimental methods of analysis. Moreover, we will highlight the role of protein conformational changes and dominant forces in driving association together with their connection w…
Hemostatic agents in endodontic surgery of maxillary molars : a randomized controlled pilot study of polytetrafluoroethylene (PTFE) strips as an adju…
2019
Background Hemostasis is of critical importance in endodontic surgery. Studies on bleeding control in maxillary molars are scarce. The present study compares the efficacy of two hemostatic techniques in controlling bleeding in endodontic surgery. Material and Methods A randomized two-arm pilot study involving 30 patients with peri-radicular lesions in maxillary molars (first and second molars) was carried out including the following hemostatic agents: polytetrafluoroethylene (PTFE) strips as an adjunct to epinephrine impregnated gauze (test group; n = 15) and aluminum chloride (Expasyl™) (control; n = 15). Bleeding control was independently assessed by the surgeon and by two blinded observe…
Interaction of Nanometric Clay Platelets
2008
International audience; The free energy of interaction between two nanometric clay platelets immersed in an electrolyte solution has been calculated using Monte Carlo simulations as well as direct integration of the configurational integral. Each platelet has been modeled as a collection of charged spheres carrying a unit chargethe face of a platelet contains negative charges, and the edge, positive charges. The calculations predict that a configuration of “overlapping coins” is the global free energy minimum at intermediate salt concentrations (10−100 mM). A second weaker minimum, corresponding to the well-known “house of cards” configuration, also appears in this salt interval. At low sal…
Analysis of Multipactor Effect in a Partially Dielectric-Loaded Rectangular Waveguide
2019
This paper 1 presents a study of the multipactor 2 effect in a partially dielectric-loaded rectangular waveguide. 3 To obtain the simulations presented in this paper, a detailed 4 analysis of the dynamics of the electron inside this waveguide 5 has been performed, taking into account the radio frequency 6 electromagnetic fields propagating in the waveguide and the dc 7 electric field that appears because of the charging of the dielectric 8 layer. This electrostatic field is obtained by computing the electric 9 potential produced by an arbitrary charge distribution on the 10 dielectric layer in a dielectric-loaded waveguide. The electron 11 trajectory is then found by numerically solving the…
Multipactor Effect in a Parallel-Plate Waveguide Partially Filled With Magnetized Ferrite
2014
The aim of this paper is the analysis of the multipactor effect in a parallel-plate waveguide when a ferrite slab, transversally magnetized by a static magnetic field parallel to the waveguide walls, is present. Employing an in-house developed code, numerical simulations are performed to predict the multipactor radio frequency voltage threshold in such a ferrite-loaded waveguide. Variations of the ferrite magnetization field strength and the ferrite slab height are analyzed. Effective electron trajectories are also shown for a better understanding of the breakdown phenomenon, finding different multipactor regimes.
Nanocomposites by Electrostatic Interactions: 1. Impact of Sublayer Quality on the Organization of Functionalized Nanoparticles on Charged Self-Asse…
2000
Bis-benzamidines were studied as linkers for the formation of gold nanoparticle assemblies on planar gold surfaces modified with ω-mercaptohexadecanoic acid. In situ ellipsometry, external reflecti...
Potential and energy of oblate spheroidal charge distributions
1989
Abstract The Poisson equation for a large class of charge distributions contained within oblate spheroids in solved and their energies are obtained. In many cases, the potential and the energy can be found by comparison with the solutions of the Poisson equation for prolate spheroidal charge distributions obtained in preceding works. The limits of validity of this comparison procedure are established. For the simplest cases the electrostatic energy is computed and, after suitable normalization, displayed graphically.
Trapping of hydrogen and helium at dislocations in tungsten: anab initiostudy
2017
Retention of plasma gas components such as hydrogen (H) isotopes and helium (He) is one of the limiting factors in selection of plasma facing materials for future thermonuclear fusion devices. Tungsten (W) is one of the promising candidates for such materials and was chosen for the divertor armor for International Thermonuclear Experimental Reactor (ITER) and the first wall material for the design of the demonstrational fusion power plant - DEMO. For the analytical estimation of accumulation of H/He components in tungsten, it is important to understand the relevant physical mechanisms of their trapping in the material and thoroughly parameterize them numerically. Experiments involving high …
Laser spectroscopy with an electrostatic ConeTrap
2017
A compact electrostatic trap has been designed and installed as part of the recent upgrades to the IGISOL IV facility. The ConeTrap provides an in vacuo optical pumping site for low energy (800 eV) ionic ensembles available for interaction periods of 10-100 ms. At present, 6.7(3) % of injected mass A=98 ions can be trapped, stored for 5 ms, extracted and transported to a laser-ion interaction region. This fraction represents those ions for which no perturbation to total energy or energy spread is observed. Proposed enhancements to the trap are designed to improve the trapping efficiency by up to a factor of 5. Differential pumping and reduction in background pressure below the present 10−6 …
The Right Answer for the Right Electrostatics: Force Field Methods Are Able to Describe Relative Energies of DNA Guanine Quadruplexes
2014
Different force fields and approximate density functional theory were applied in order to study the rotamer space of the telomeric G-quadruplex DNA. While some force fields show an erratic behavior when it comes to the reproduction of the higher-order DNA conformer space, OPLS and MMFF implementations are able to reproduce the experimentally known energy order. The stabilizing effect of the AA (anti−anti) versus SA (syn−anti) conformer is analyzed applying mechanical bond strength descriptors (compliance constants). The fact that we observe the correct energy order using appropriate force fields is in contrast with results previously reported, which suggested the general inappropriateness o…