Search results for "Dissociation"
showing 10 items of 531 documents
Experimental and methodological factors affecting test-retest reliability of amygdala BOLD responses.
2018
Previous studies reported poor to fair test-retest reliability of amygdala BOLD responses to emotional stimuli. However, these findings are very heterogeneous across and within studies. The present study sought to systematically examine experimental and methodological factors that contribute to this heterogeneity. Forty-six young subjects were scanned twice with a mean test-retest interval of 7 weeks. We compared amygdala reliability across three tasks: A face-matching task, passive viewing of emotional faces, and passive viewing of emotional scenes. We also explored whether extraction of physiological noise can affect the stability of amygdala responses. We assessed test-retest reliability…
Effect of protonation and deprotonation on the gas phase reactivity of fluorinated 1,2,4-triazines
2008
Positive and negative electrospray mass spectrometry (MS), in-time and in-space MS n experiments, high-resolution and accurate mass measurements obtained with an Orbitrap, together with density functional theory calculations have been used to study the gas-phase ion chemistry of a series of fluorinated 1,2,4-triazines. As a result of low-energy collision-induced dissociations, occurring in an ion trap and in a triple quadrupole, their protonated and deprotonated molecules show interesting features depending on the nature and structure of the precursor ions. The occurrence of elimination/hydration reactions produced by positive ions in the ion trap is noteworthy. Decompositions of deprotonat…
Control of kinetics by cooperative interactions.
2011
Cooperative effects in ligand binding and dissociation kinetics are much less investigated than steady state kinetics or equilibrium binding. Nevertheless, cooperativity in ligand binding leads necessarily to characteristic properties with respect to kinetic properties of the system. In case of positive cooperativity as found in oxygen binding proteins, a typical property is an autocatalytic ligand dissociation behavior leading to a time dependent, apparent ligand dissociation rate. To follow systematically the influence of the various potentially involved parameters on this characteristic property, simulations based on the simple MWC model were performed which should be relevant for all ty…
Low energy electrons and ultra-soft X-rays irradiation of plasmid DNA. Technical innovations
2016
Abstract In this paper we present in a first part the latest results of our group which are in relation with the study of DNA damages inflicted by low energy electrons (0-20 eV) in ultra-high vacuum as well as in air under atmospheric conditions. A short description of the drop-casting technique we developed to produce thin and nanometre-scaled DNA layers onto graphite sheets is given. We provide the absolute cross-section for loss of supercoiled topology of plasmid DNA complexed with 1,3-diaminopropane (Dap) in the vacuum under 10 eV electron impact and suggest a specific pathway for the dissociation of the transient negative ion formed by resonant capture of such a low energy electron (LE…
Characterization of gramicidin A in an inverted micellar environment. A combined high-performance liquid chromatographic and spectroscopic study
1992
We have investigated the conformational adaptability of gramicidin A incorporated into reverse micelles of sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/isooctane/water, a so far unexplored "host" membrane-mimetic model system for this peptide. A high-performance liquid chromatographic strategy previously developed for the study of gramicidin in phospholipid vesicles and normal micelles [Bañó et al. (1989) FEBS Lett. 250, 67; Bañó et al. (1991) Biochemistry 30, 886] has been successfully extended to this system. The method has permitted the separation of peptide conformational species, namely, double-stranded dimers and monomers, and an accurate quantitation of their proportion in the invert…
Dissociative adsorption of water on Au/MgO/Ag(001) from first principles calculations
2015
Abstract The molecular and dissociative adsorption of water on a Ag-supported 1 ML, 2 ML and 3 ML-a six atomic layer-thick MgO films with a single Au adatom is investigated using density functional theory calculations. The obtained results are compared to a bulk MgO(001) surface with an Au atom. On thin films the negatively charged Au strengthens the binding of the polar water molecule due to the attractive Au–H interaction. The adsorption energy trends of OH and H with respect to the film thickness depend on an adsorption site. In the case OH or H binds atop Au on MgO/Ag(001), the adsorption becomes more exothermic with the increasing film thickness, while the reverse trend is seen when th…
Ab initio study of the F centers in CaF2: Calculations of the optical absorption, diffusion and binding energies
1998
Abstract The ground electronic state of the F center in CaF 2 crystal, its optical absorption energy, the activation energy of thermal diffusion and M center dissociation to pair of F centers are calculated using the Hartree-Fock embedded molecular cluster method. Different pseudopotentials, basis sets, boundary conditions and two computer codes, EMBED96 and Gaussian94, are employed and their results compared.
The Interdependence of Respiratory Gas Values and pH as a Function of Base Excess in Human Blood at 37°C
1973
The accurate estimation of the transport function of human blood for respiratory gases as well as the respiratory gas exchange in human body requires detailed knowledge of the respiratory gas partial pressures and the acid-base status in the blood. Because there is an interdependence between the different respiratory gas parameters described as Bohr and Haldane effect (3,4), it is possible to obtain a general picture of the whole transport system, if these interrelations are known.
Bipolar membranes under forward and reverse bias conditions. Theory vs. experiment
1994
Abstract Bipolar membranes are layered structures composed of one cation-and one anion-exchange membrane joined together in series. The current—voltage curves of two recently developed bipolar membranes have been analysed theoretically and experimentally under both forward and reverse bias conditions. The experimental trends observed are high conductivity under forward bias conditions and high impedance first, and then electric field enhanced (EFE) water dissociation for high enough applied voltages, under reverse bias conditions. The forward bias measurements can contribute to a better knowledge of some of the transport parameters entering also in the reverse biased membrane. Comparison of…
Raman spectroscopy and crystal-field split rotational states of photoproducts CO and H2 after dissociation of formaldehyde in solid argon.
2012
Raman signal is monitored after 248 nm photodissociation of formaldehyde in solid Ar at temperatures of 9-30 K. Rotational transitions J = 2 ← 0 for para-H(2) fragments and J = 3 ← 1 for ortho-H(2) are observed as sharp peaks at 347.2 cm(-1) and 578.3 cm(-1), respectively, which both are accompanied by a broader shoulder band that shows a split structure. The rovibrational spectrum of CO fragments has transitions at 2136.5 cm(-1), 2138.3 cm(-1), 2139.9 cm(-1), and 2149 cm(-1). To explain the observations, we performed adiabatic rotational potential calculations to simulate the Raman spectrum. The simulations indicate that the splitting of rotational transitions is a site effect, where H(2) …