Search results for "force"
showing 10 items of 3423 documents
Hexachlororhenate(IV) salts of organic radical cations
2005
Abstract The ionic salts ( p -rad) 2 [ReCl 6 ] ( 1 ) and ( m -rad) 2 [ReCl 6 ] ( 2 ) ( p / m -rad = 2-(4/3- N -methylpyridinium)-4,4,5,5-tetramethyl-4,5-dihydro-1 H -imidazol-1-oxyl-3- N -oxide) have been prepared and their crystal structures determined by single-crystal X-ray diffraction. The nitronyl nitroxide cations in compound 1 show a layered disposition, whereas the [ReCl 6 ] 2− units are placed between these layers. The nitronyl nitroxide cations in compound 2 adopt an hexagonal array but they do not result in layers. Bulk magnetic properties of 1 and 2 have been investigated in the temperature range 2–300 K. Both compounds show weak but significant intermolecular antiferromagnetic …
Restricting Magnetic Interaction Pathways in Polyoxometalate Salts of Cationic Nitronyl Nitroxide Free Radicals
2004
Abstract : Salts 1 and 2 that combine the [W 6 O 19 ] 2- Lindqvist anion with the cationic nitronyl nitroxide (NN) free radicals p -MepyNN + and n Bu 3 NCH 2 NN + , respectively, have been synthesized and their structural and magnetic properties have been studied. Keywords: Nitroxide radicals, polyoxometalates, magnetism. Introduction Ferromagnetism based on purely organic materials has raised a lot of interest during the last decade [1]. Most of the studies have been performed with nitronyl nitroxide (NN) radicals due to their persistence, stability and ease of functionalization [2]. Bulk ferromagnetism in these compounds arises from ferromagnetic interactions between open-shell molecules …
Some experimental issues of AFM tip blind estimation. The effect of noise and resolution
2006
The convolution of tip shape on sample topography can introduce significant inaccuracy in an AFM image, when the tip radius is comparable to the typical dimension of the sample features to be observed. The blind estimation method allows one to obtain information on the AFM tip through an unknown characterizer sample and thus to perform the deconvolution of the tip shape from an image. When applying the blind estimation method to determine the AFM tip shape, some apparently trivial issues relating to the experimental operating parameters must be taken into account. In this paper, the effects of the operating parameters, e.g., sampling intervals (resolution) and instrumental noise, have been …
Dynamics of non-local systems handled by fractional calculus
2007
Mechanical vibrations of non-local systems with long-range, cohesive, interactions between material particles have been studied in this paper by means of fractional calculus. Long-range cohesive forces between material particles have been included in equilibrium equations assuming interaction distance decay with order α . This approach yields as limiting case a partial fractional differential equation of order α involving space-time variables. It has been shown that the proposed model may be obtained by a discrete, mass-spring model that includes non-local interactions by non-adjacent particles and the mechanical vibrations of the particles have been obtained by an approximation fractional …
Tetrathiafulvalene-Polychlorotriphenylmethyl Dyads: Influence of Bridge and Open-Shell Characteristics on Linear and Nonlinear Optical Properties
2017
Three conjugated donor-π-acceptor radical systems (1 a–1 c) were prepared by bridging a tetrathiafulvalene (TTF) electron-donor unit to a polychlorotriphenylmethyl (PTM) electron-acceptor radical through vinylene units of different lengths. The dependence of the intramolecular charge transfer on the length of the conjugated bridge has been analyzed by different electrochemical and spectroscopic techniques. Linear optical properties and the second-order nonlinear optical (NLO) response of these derivatives have been computed by comparing systems 1 a–1 c with the non-radical analogues (2 a–2 c). Interestingly, an enhanced NLO response is predicted for dyads 1 a–1 c with PTM in the radical for…
Saying-Doing Correspondence
2002
The study of the correspondence concerns the functional relationships between an individual’s verbal and non-verbal behavior. The analysis of the functional relations between saying and doing is interesting from a theoretical perspective (e.g.: how and when do they relate together? Learning to tell the truth etc.) and from an applied point of view: many clinical procedures, as verbal forms of psychotherapy, are based on the idea that changing people’s verbalizations about their behavior will lead to corresponding changes in the way they behave. Since say-do correspondence training has been employed in a variety of behaviors and types of procedures to examine the conditions upon which the ar…
Wormlike Polystyrene Brushes in Thin Films
1997
Mono- and multilayer films were prepared on mica by solution casting of a high molecular weight polymacromonomer, i.e., a polymethacrylate of about 1000 repeating units each of which was substituted by a polystyrene chain with a molecular weight of about 5000 Da. The films were studied by tapping scanning force microscopy. The material showed a remarkable preference for forming well-defined monolayers of a thickness of 6.5 ± 0.2 nm consistent with the hard core diameter of the collapsed cylindrical brush molecules. When the films were probed with high normal force, the single molecules were observed to organize in a dense nematic-like packing as expected for inherently stiff molecules. In o…
How do normalization schemes affect net spillovers? A replication of the Diebold and Yilmaz (2012) study
2019
Abstract This paper replicates the Diebold and Yilmaz (2012) study on the connectedness of the commodity market and three other financial markets: the stock market, the bond market, and the FX market, based on the Generalized Forecast Error Variance Decomposition, GEFVD. We show that the net spillover indices (of directional connectedness), used to assess the net contribution of one market to overall risk in the system, are sensitive to the normalization scheme applied to the GEFVD. We show that, considering data generating processes characterized by different degrees of persistence and covariance, a scalar-based normalization of the Generalized Forecast Error Variance Decomposition is pref…
Effects of $CP$-violating internucleon interactions in paramagnetic molecules
2020
We demonstrate that electron electric dipole moment experiments with molecules in paramagnetic state are sensitive to $P,T$-violating nuclear forces and other $CP$-violating parameters in the hadronic sector. These experiments, in particular, measure the coupling constant $C_{SP}$ of the $CP$-odd contact semileptonic interaction. We establish relations between $C_{SP}$ and different $CP$-violating hadronic parameters including strength constants of the $CP$-odd nuclear potentials, $CP$-odd pion-nucleon interactions, quark-chromo EDM and QCD vacuum angle. These relations allow us to find limits on various $CP$-odd hadronic parameters.
Evidence for a spin-aligned neutron-proton paired phase from the level structure of (92)Pd
2011
4 páginas, 4 figuras.-- El Pdf es la versión pre-print.-- et al.