Search results for "RELAXATION"
showing 10 items of 1162 documents
Characterization of water mobility in dry and wetted roasted coffee using low-field proton nuclear magnetic resonance
2007
Abstract Roasted and ground coffee was studied by low-field 1 H nuclear magnetic resonance at various water contents and temperatures. The spin–spin relaxation times ( T 2 ) were measured with single pulse free induction decay (FID) and Carr–Purcell–Meiboom–Gill (CPMG) sequences. Four relaxing components were distinguished: the solid population was observed with FID sequence at T 2s ∼9 μs; the other three populations, measured with the CPMG sequence, corresponded to an apolar phase, the coffee oil, and two polar phases. The two polar populations, observed at T 2m ∼6 ms and ∼27 ms (for coffee with 50% water content at 90 °C) were attributed to water in cell wall polymers and in water filling…
Collisional relaxation measurements on Pb+ hyperfine levels
1993
The time constants for population relaxation of optically pumped Pb+ ions in a Paul ion trap have been determined in a He buffer gas atmosphere with additional components of other gases. For the 6P1/2 ground state of Pb+ and an ion temperatur of 104 K we find cross sections of 0.72(0.33)·10−17 cm2; 0.59(0.38)·10−15 cm2; and 2.56(0.74)·10−14 cm2 for He, N2 and O2, respectively. The error includes an estimated 20% uncertaincy in the pressure calibration of a residual gas analyser.
The photophysics of distorted nanographenes: Ultra-slow relaxation dynamics, memory effects, and delayed fluorescence
2023
The controlled deformation and engineering of the sp2 carbon network in atomically-precise nanographenes, and their substantially larger size as compared to typical optical dyes, opens new opportunities for the modulation of optical and electronic properties, but the peculiar photophysics of these systems is still poorly understood. Here, through a detailed comparative study of two well-defined distorted nanographenes, we show that they can exhibit interesting photophysical features, such as triplet-triplet annihilation delayed fluorescence, ultra-slow excited state dynamics, and excitation-wavelength memory effects on the nanosecond and sub-nanosecond relaxation cascades. Some of these beh…
Involvement of purinergic nerves in the NANC inhibitory junction potentials in pigeon oesophageal smooth muscle.
2004
1. Electrical field stimulation (EFS) (0.5 ms in train of 2-32 Hz for 300 ms) in smooth muscle of pigeon oesophagus, in the presence of atropine (1 microm) and guanethidine (1 microm), elicited an inhibitory response consisting of a transient hyperpolarization (inhibitory junction potential, IJP) associated with muscle relaxation. 2. Sodium nitroprusside (SNP, 100 microm) induced hyperpolarization correlated to mechanical relaxation. 3. The nitric oxide (NO) synthase inhibitor N(omega)-nitro-l-arginine (from 0.1 to 100 microm) caused a concentration-dependent reduction of electromechanical response to EFS indicating a role for NO in this response. 4. Apamin (1 microm) reduced both IJP and r…
Evidence that adenosine is not involved in the non-adrenergic non-cholinergic relaxation in the rat duodenum.
1990
In rat isolated duodenal segments, adenosine induced, in the presence of atropine and guanethidine, a dose-dependent, long-lasting (about 20 s), tetrodotoxin (TTX)-resistant relaxation both in endoluminal pressure and in isometric tension. Electrical field stimulation (EFS) induced, in the presence of atropine and guanethidine, a TTX-sensitive short-lasting (about 6 s) relaxation followed by a sustained rebound contraction. Theophylline, a P1 receptor antagonist, at the concentration of 100 microM caused a marked inhibition of the adenosine-induced relaxation, while the EFS-induced relaxation was not modified. Our results suggest that adenosine induces relaxation of the rat duodenal smooth …
Systematic trends in (0 0 1) surface ab initio calculations of ABO 3 perovskites
2018
This work was supported by the Latvian Council of Science Grant No. 374/2012 and the Latvian National Research Program IMIS2. Many stimulating discussions with D. Vanderbilt, K.M. Rabe, M. Rohlfing, E. Heifets, J. Maier, G. Borstel and E.A. Kotomin are greatly acknowledged.
Ab initio calculations of the atomic and electronic structure of BaZrO3 (111) surfaces
2013
Abstract The paper presents and discusses the results of calculations of surface relaxations and energetics for the polar (111) surface of BaZrO 3 using a hybrid B3LYP description of exchange and correlation. On the (111) surface, both Zr- and BaO 3 -terminations were analyzed. For both Zr and BaO 3 -terminated BaZrO 3 (111) surface upper layer atoms, with the sole exception of BaO 3 -terminated surface Ba atoms, relax inwards. The Zr-terminated BaZrO 3 (111) surface second layer Ba atoms exhibit the strongest relaxation between all Zr and BaO 3 -terminated BaZrO 3 (111) surface atoms. The calculated surface relaxation energy for Zr-terminated BaZrO 3 (111) surface is almost fifteen times l…
Reliable Underlay D2D Communications over Multiple Transmit Antenna Framework
2020
Robust beamforming is an efficient technique to guarantee the desired receiver performance in the presence of erroneous channel state information (CSI). However, the application of robust beamforming in underlay device-to-device (D2D) communication still requires further investigation. In this paper, we investigate resource allocation problem for underlay D2D communications by considering multiple antennas at the base station (BS) and at the transmitters of D2D pairs. The proposed design problem aims at maximizing the aggregate rate of all D2D pairs and cellular users (CUs) in downlink spectrum. In addition, our objective is augmented to achieve a fair allocation of resources across the D2D…
Relay selection in FDD amplify-and-forward cooperative networks
2017
In this paper, the problems of relay selection and distributed beamforming are investigated for bi-directional dual-hop amplify-and-forward frequency-division duplex cooperative wireless networks. When using individual per-relay maximum transmission power constraint, it has been proven that the relay selection and beamforming optimization problem becomes NP hard and requires exhaustive search to find the optimal solution. Therefore, we propose a computationally affordable sub-optimal multiple relay selection and beamforming optimization scheme based on the l1 norm squared relaxation. The proposed scheme performs the selection for the two transmission directions, simultaneously, while aiming…
Exponential Relaxation out of Nonequilibrium
1989
Simulation results are presented for a quench from a disordered state to a state below the coexistence curve. The model which we consider is the Ising model but with the dynamics governed by the Swendsen-Wang transition probabilities. We show that the resulting domain growth has an exponential instead of a power law behaviour and that the system is non-self-averaging while in nonequilibrium. The simulations were carried out on a parallel computer with up to 128 processors.