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Journal articles on the topic 'Relaxation'
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1
Bury, Peter, Peter Hockicko, and Miroslav Jamnický. "Transport and Relaxation Study of Ionic Phosphate Glasses." Advanced Materials Research 39-40 (April 2008): 111–16. http://dx.doi.org/10.4028/www.scientific.net/amr.39-40.111.
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Dynamic processes in glassy materials with ionic conductivity are extremely important since the ion transport significantly affects their practical performance. Conductivity measurement and dielectric relaxation spectroscopy are powerful techniques that reflect the essential features of the transport and relaxational dynamics of the mobile ions that encounter different kinds of site and ionic hopping motion connected with charge mobility. Acoustic spectroscopy is another technique for the study of relaxations in glasses. In this contribution the acoustic and electrical relaxation processes are compared on identical ionic phosphate glasses of the systems CuI-CuBr-Cu2O-P2O5 and CuI-CuBr-Cu2O-P2O5-MoO3 containing Cu+ ions. The acoustic attenuation spectra indicate various relaxation processes and at least two conductivity regimes of transport mechanisms were observed. Both the acoustic and electrical measured data were analyzed using suitable model representations.
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Suzuki, Yasuhito, Takahito Kano, Tsuyoshi Tomii, Nagisa Tsuji, and Akikazu Matsumoto. "Relaxation and Amorphous Structure of Polymers Containing Rigid Fumarate Segments." Polymers 14, no. 22 (November 12, 2022): 4876. http://dx.doi.org/10.3390/polym14224876.
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The physical properties of polymers are significantly affected by relaxation processes. Recently, we reported that poly(diethyl fumarate) (PDEF) shows two thermal anomalies on DSC measurement, despite the fact that it is a homopolymer. We attribute these two relaxations α relaxation and β relaxation, respectively. In this study, we investigate the two relaxations of fumarate-containing polymers by DSC, solid-state NMR, and X-ray scattering. The two relaxations are present even in a copolymer of diethyl fumarate and ethyl acrylate with fumarate segments of 30%. We used poly(methyl methacrylate) (PMMA) as a model polymer for comparison, since there are detailed investigations of its dynamics and physical properties. Solid-state NMR indicates that the very local relaxation of poly(fumarate)s is not significantly different from that of PMMA. The tensile test showed that PDEF is still brittle at above β relaxation temperature and below α relaxation temperature. It was revealed that a structural anisotropy appeared when PDEF was extended at around α relaxation temperature. We discuss the effect of the glassy packing of the rigid polymer chain including the DEF segments on the strong β relaxation behavior. Our data provide insight into the microscopic mechanism of β relaxation of vinyl polymers.
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Toda, Noboru. "Hemolysate Inhibits Cerebral Artery Relaxation." Journal of Cerebral Blood Flow & Metabolism 8, no. 1 (February 1988): 46–53. http://dx.doi.org/10.1038/jcbfm.1988.7.
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In helical strips of dog middle cerebral arteries partially contracted with prostaglandin (PG) F2α, relaxations induced by angiotensin-II, possibly mediated by PGI2, and those induced by PGH2 were reversed to a contraction or markedly reduced by treatment with hemolysate, which, however, attenuated the PGI2-induced relaxation only slightly. The relaxant response of human middle cerebral arterial strips to PGH2 was also suppressed by hemolysate. Dog and monkey middle cerebral arteries responded to transmural electrical stimulation and nicotine with transient relaxations, which were quite susceptible to tetrodotoxin and hexamethonium, respectively; the relaxations were abolished almost completely by hemolysate and methylene blue. On the other hand, the relaxant response of dog cerebral arteries to a low concentration of K+ was not influenced by hemolysate or by methylene blue, but was reversed to a contraction by treatment with ouabain. Relaxations induced by substance-P and nitroglycerin were markedly inhibited by hemolysate; removal of endothelium abolished the relaxation by substance-P, but did not influence the nitroglycerin-induced relaxation. Hemolysate may interfere with the biosynthesis of PGI2 in the vascular wall, thereby reversing the relaxation induced by angiotensin-II and PGH2 to a contraction. Relaxations induced by electrical and chemical stimulation of vasodilator nerves innervating cerebral arteries appear to be elicited by a mechanism dependent on cellular cyclic guanosine monophosphate (GMP), like that underlying the substance-P-induced and nitroglycerin-induced relaxation. These actions of hemolysate may be involved in the genesis of cerebral vasospasm after subarachnoid hemorrhage.
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Haruyama, Osami, and Sadao Yamada. "Density and Enthalpy Relaxation Behavior in a Bulk Pd40Ni40P20 Metallic Glass." Materials Science Forum 561-565 (October 2007): 1283–86. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.1283.
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The kinetics of structural relaxation in a Pd40Ni40P20 bulk metallic glass was investigated by the volume relaxation due to density experiments and the enthalpy relaxation due to specific heat experiments. A two-step relaxation process was found in the volume relaxation, while the enthalpy relaxation seemed to be one-step relaxation process with a spectrum of relaxation times. First-step volume relaxation only in as-quenched glass was the process with a spread of relaxation times at lower relaxing temperature, while a Debye-type relaxation behavior was observed at higher temperature near Tg and in pre-annealed glass. The comparison of the kinetics of volume and enthalpy relaxations at the same temperature showed a disagreement with the prediction of free volume theory.
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Holloway, R. H., R. Penagini, and A. C. Ireland. "Criteria for objective definition of transient lower esophageal sphincter relaxation." American Journal of Physiology-Gastrointestinal and Liver Physiology 268, no. 1 (January 1, 1995): G128—G133. http://dx.doi.org/10.1152/ajpgi.1995.268.1.g128.
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We developed and evaluated objective manometric criteria that define transient lower esophageal sphincter (LES) relaxation. In 23 normal subjects and 9 patients with gastroesophageal reflux disease, systematic analysis of swallow-induced LES relaxation showed that dry swallows preceded LES relaxation by a median of 1.4 s. The relaxation rate was always > 1 mmHg/s, the relaxation nadir always occurred within 7 s, and the duration of relaxation was < 9 s. During concurrent esophageal manometry and pH monitoring, 104 reflux episodes associated with a LES pressure fall that was not related to swallowing were identified and the pressure falls classified as transient LES relaxations or not by visual recognition. LES pressure was always < or = 2 mmHg at time of reflux, and relaxation was significantly longer than for swallow-induced LES relaxation. Of 88 pressure falls classified visually as transient LES relaxations, 90% reached nadir pressure within 7 s at a rate of > 1 mmHg/s. Sixteen pressure falls were classified as a gradual downward drift in LES pressure, which in 15 cases was < 1 mmHg/s. Based on the analysis, transient LES relaxation can be defined by 1) absence of swallowing for 4 s before to 2 s after the onset of LES relaxation, 2) relaxation rate of > or = 1 mmHg/s, 3) time from onset to complete relaxation of < or = 10 s, and 4) nadir pressure of < or = 2 mmHg.(ABSTRACT TRUNCATED AT 250 WORDS)
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Guo, Jin Quan, Wu Zhou Meng, Fei Li, and Li Xin Wang. "Creep Prediction From Stress Relaxation Coupled With Equivalent Relaxation Rate." Applied Mechanics and Materials 644-650 (September 2014): 1382–85. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.1382.
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Several stress relaxation and creep tests of high temperature material are performed. According to the characteristics of stress relaxations and the superposition equation of diffusion and Maxwell equations of two stages, equivalent relaxation time and equivalent relaxation rate are proposed. Considering equivalent relaxation rate as the creep rate under constant stress, the relaxation-creep conversion model is built up and presented. Then the steady-state creep curve and creep rate are calculated. The results show that the numerical results are in good agreement with the experimental data. It indicates that equivalent relaxation rate can be employed for the analysis of steady-state creep rate. The conversion model and method can be used to design the creep strength and predict the life of the component at high temperature.
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Kumar-Krishnan, Siva, Evgen Prokhorov, and Gabriel Luna-Barcenas. "Molecular relaxation in Chitosan films in GHz frequency range." MRS Proceedings 1613 (2014): 83–88. http://dx.doi.org/10.1557/opl.2014.162.
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ABSTRACTThe molecular relaxations behavior of chitosan (CS) films in the wide frequency range of 0.1-3x109 Hz (by using three different impedance analyzers) have been investigated in the temperature range of -100C to 120°C using Dielectric Spectroscopy (DS). Additionally to the low frequency molecular relaxations such as α and β relaxations, for the first time, high frequency (1-3 GHz) relaxation process has been observed in the chitosan films. This relaxation exhibits Arrhenius-type dependence in the temperature range of -100 C to 54°C with negative activation energy -2.7 kJ/mol. At temperatures above 54°C, the activation energy changes from -2.7 kJ/mol to +4.4 kJ/mol. Upon cooling, the activation energy becomes negative again with a value of -1.2 kJ/mol. The bound water between chitosan molecules strongly modifies molecular motion and the relaxation spectrum, giving rise to a new relaxation at the frequency at ca. 1 GHz. In situ FTIR analysis has shown that this relaxation related to the changes in vibration of the –OH, NH and –CO functional groups.
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Hashimoto, M., L. A. Close, Y. Ishida, and R. J. Paul. "Dependence of endothelium-mediated relaxation on oxygen and metabolism in porcine coronary arteries." American Journal of Physiology-Heart and Circulatory Physiology 265, no. 1 (July 1, 1993): H299—H306. http://dx.doi.org/10.1152/ajpheart.1993.265.1.h299.
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Hypoxia has major effects on endothelium-dependent relaxation. To further understand the underlying mechanism(s), we investigated the O2 dependence of the endothelium-dependent relaxations elicited by ionophore A-23187 or agonists substance P (SP) or thrombin (TB) in porcine coronary arteries. A-23187 elicits an endothelium-dependent relaxation of KCl- or U-46619-induced contractures that can be described in terms of a rapid and slow phase. The duration of the relaxation was dose dependent. SP (10 nM) and TB (0.1 U/ml) also elicited endothelium-dependent relaxations that were rapid but transient. Hypoxic conditions (95% N2-5% CO2 instead of 95% O2-5% CO2; PO2 < 1%) abolished the A-23187 rapid phase and the SP and TB transient relaxation but not the A-23187 slow phase. Threshold PO2 for the rapid phase was approximately 35 mmHg. Pretreatment with cyanide (5 mM), to inhibit respiration, or 2-deoxy-D-glucose, to inhibit glycolysis, had little effect. Similarly, propranolol (10 microM) or indomethacin (10 microM) had no effect on the relaxation to A-23187, TB, or SP. In contrast, both NO synthesis inhibitors and ouabain blunted all endothelium-dependent relaxations studied. Our results suggest that the rapid relaxations to A-23187, SP, and TB are sensitive to O2 but not mitochondrial respiration. The slow sustained relaxation induced by A-23187, however, is characterized by a sensitivity to O2 that is distinct from that of the rapid phase, yet is dependent on an intact endothelium and is affected by NO synthesis inhibitors. Thus the endothelium-dependent relaxation to A-23187 is probably mediated by NO, but its sensitivity to O2 suggests that two distinct mechanisms may be involved.
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Nagao, T., and P. M. Vanhoutte. "Hyperpolarization contributes to endothelium-dependent relaxations to acetylcholine in femoral veins of rats." American Journal of Physiology-Heart and Circulatory Physiology 261, no. 4 (October 1, 1991): H1034—H1037. http://dx.doi.org/10.1152/ajpheart.1991.261.4.h1034.
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The contribution of membrane hyperpolarization to endothelium-dependent relaxations induced by acetylcholine was investigated in the femoral vein of the rat using a microelectrode technique and isometric tension recordings. Acetylcholine caused endothelium-dependent relaxations and hyperpolarization in tissues contracted with norepinephrine. The relaxation was sustained during a prolonged exposure to acetylcholine (less than or equal to 10 min). In contrast, the hyperpolarization declined with time. In the presence of nitro-L-arginine, a blocker of nitric oxide synthesis, the relaxation became smaller and transient, whereas the hyperpolarization was not affected. There was a temporal relationship between the relaxation and the hyperpolarization in the presence of nitro-L-arginine, when the two parameters were recorded simultaneously. In tissues contracted with 60 mM K+, in which hyperpolarization could not be observed, acetylcholine caused relaxations and these relaxations were abolished by nitro-L-arginine. The results suggest a contribution of both nitric oxide and membrane hyperpolarization to the endothelium-dependent relaxation induced by acetylcholine in the femoral vein of the rat.
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Yu, Peng, Cheng Fang, and Brian Williams. "Resolving Uncontrollable Conditional Temporal Problems Using Continuous Relaxations." Proceedings of the International Conference on Automated Planning and Scheduling 24 (May 11, 2014): 341–48. http://dx.doi.org/10.1609/icaps.v24i1.13623.
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Uncertainty is commonly encountered in temporal scheduling and planning problems, and can often lead to over-constrained situations. Previous relaxation algorithms for over-constrained temporal problems only work with requirement constraints, whose outcomes can be controlled by the agents. When applied to uncontrollable durations, these algorithms may only satisfy a subset of the random outcomes and hence their relaxations may fail during execution. In this paper, we present a new relaxation algorithm, Conflict-Directed Relaxation with Uncertainty (CDRU), which generates relaxations that restore the controllability of conditional temporal problems with uncontrollable durations. CDRU extends the Best-first Conflict-Directed Relaxation (BCDR) algorithm to uncontrollable temporal problems. It generalizes the conflict-learning process to extract conflicts from strong and dynamic controllability checking algorithms, and resolves the conflicts by both relaxing constraints and tightening uncontrollable durations. Empirical test results on a range of trip scheduling problems show that CDRU is efficient in resolving large scale uncontrollable problems: computing strongly controllable relaxations takes the same order of magnitude in time compared to consistent relaxations that do not account for uncontrollable durations. While computing dynamically controllable relaxations takes two orders of magnitude more time, it provides significant improvements in solution quality when compared to strongly controllable relaxations.
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Ristaniemi, Aapo, Dristi Regmi, Diponkor Mondal, Jari Torniainen, Petri Tanska, Lauri Stenroth, Mikko A. J. Finnilä, Juha Töyräs, and Rami K. Korhonen. "Structure, composition and fibril-reinforced poroviscoelastic properties of bovine knee ligaments and patellar tendon." Journal of The Royal Society Interface 18, no. 174 (January 2021): 20200737. http://dx.doi.org/10.1098/rsif.2020.0737.
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Tissue-level stress-relaxation of ligaments and tendons in the toe region is characterized by fast and long-term relaxations and an increase in relaxation magnitude with strain. Characterizing the compositional and structural origins of these phenomena helps in the understanding of mechanisms of ligament and tendon function and adaptation in health and disease. A three-step tensile stress-relaxation test was conducted on dumbbell-shaped pieces of bovine knee ligaments and patellar tendon (PT) ( n = 10 knees). Their mechanical behaviour was characterized by a fibril-reinforced poroviscoelastic material model, able to describe characteristic times and magnitudes of fast and long-term relaxations. The crimp angle and length of tissues were measured with polarized light microscopy, while biochemical contents were determined by colorimetric biochemical methods. The long-term relaxation time was longer in the anterior cruciate ligament (ACL) and PT compared with collateral ligaments ( p < 0.05). High hydroxyproline content predicted greater magnitude and shorter time of both fast and long-term relaxation. High uronic acid content predicted longer time of long-term relaxation, whereas high crimp angle predicted higher magnitude of long-term relaxation. ACL and PT are better long-term stabilizers than collateral ligaments. The long-term relaxation behaviour is affected or implied by proteoglycans and crimp angle, possibly relating to slow structural reorganization of the tissue.
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Suzuki, Shigeru, and Alfred Seeger. "Effect of Purity on Dislocation-Induced Relaxations in Molybdenum Single Crystals." Defect and Diffusion Forum 363 (May 2015): 106–11. http://dx.doi.org/10.4028/www.scientific.net/ddf.363.106.
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Dislocation-induced relaxations in different molybdenum single crystals were investigated by means of low-frequency internal friction measurements in the temperature range of 20–600 K. The results indicated that the appearance of the dislocation-induced relaxations strongly depends on the purity of the molybdenum, although the intrinsic dislocation relaxations appeared at about 100 K and 450 K in the high-purity molybdenum. The molybdenum containing a small amount of carbon did not exhibit the intrinsic dislocation relaxations but rather revealed a modulus increase due to the dislocation pinning caused by the dissolved carbon. When the molybdenum containing a small amount of carbon was annealed up to 700 K, a new relaxation peak appeared at about 450 K. The activation process for this relaxation indicated that it could be attributed to the relaxation due to a carbon-dislocation interaction. In addition, it was shown that the dislocation-induced relaxations in medium-purity molybdenum were small, which was attributed to the residual substitutional impurities in the molybdenum.
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Zhao, Binshan, Liping Wen, Li Xu, Xiujian Zhao, and Baoshun Liu. "The Effect of Cu(II) Nanoparticle Decoration on the Electron Relaxations and Gaseous Photocatalytic Oxidations of Nanocrystalline TiO2." Catalysts 13, no. 3 (March 9, 2023): 550. http://dx.doi.org/10.3390/catal13030550.
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A photocatalytic effect arises from the electron relaxation of semiconductors. Directing the electron relaxation toward photocatalytic reactions is the focus of photocatalytic studies. Co-catalyst decoration is a main way to modulate the electron relaxation, and the Cu(II) nanoparticles have been widely studied as an important co-catalyst. However, the detailed mechanism is still not well known. The current study is devoted to investigating the effect of the Cu(II) nanoparticle decoration on the electron relaxations for TiO2 through in situ photochromism and photoconductances, based on which the relation to the photocatalytic properties was discussed. The result shows that the Cu(II)/Cu(0) redox couple assists the double electron transfer from TiO2 to O2, while the Cu(I)/Cu(0) redox couple assists the single electron transfer to O2. Although the Cu(II) decoration changes the mechanism and increases the rate of the electron relaxations, the electron relaxation does not occur via the Cu redox couple assistance. It was found that the electron relaxation kinetics depends on the reduced Cu species, which can be greatly increased when the Cu(II) was reduced to Cu(0). It is also revealed that the electron relaxation corresponds to the electron transfer from TiO2 to O2, but it does not occur through the Cu redox couple assistance. The result also shows that the increase in the electron relaxation is mainly directed toward the recombination rather than photocatalytic reactions. The present research gains some insights on the role of the co-catalysts in the electron relaxations and its relation to photocatalysis; this should be meaningful for designing novel photocatalytic materials.
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Kroigaard, Christel, Thomas Dalsgaard, and Ulf Simonsen. "Mechanisms underlying epithelium-dependent relaxation in rat bronchioles: analogy to EDHF-type relaxation in rat pulmonary arteries." American Journal of Physiology-Lung Cellular and Molecular Physiology 298, no. 4 (April 2010): L531—L542. http://dx.doi.org/10.1152/ajplung.00220.2009.
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This study investigated the mechanisms underlying epithelium-derived hyperpolarizing factor (EpDHF)-type relaxation in rat bronchioles. Immunohistochemistry was performed, and rat bronchioles and pulmonary arteries were mounted in microvascular myographs for functional studies. An opener of small (SKCa) and intermediate (IKCa)-conductance calcium-activated potassium channels, NS309 (6,7-dichloro-1H-indole-2,3-dione 3-oxime) was used to induce EpDHF-type relaxation. IKCa and SKCa3 positive immunoreactions were observed mainly in the epithelium and endothelium of bronchioles and arteries, respectively. In 5-hydroxytryptamine (1 μM)-contracted bronchioles (828 ± 20 μm, n = 84) and U46619 (0.03 μM)-contracted arteries (720 ± 24 μm, n = 68), NS309 (0.001–10 μM) induced concentration-dependent relaxations that were reduced by epithelium/endothelium removal and by blocking IKCa channels with charybdotoxin and in bronchioles also by blocking SKCa channels with apamin. Inhibition of cyclooxygenase, nitric oxide synthase, and cytochrome 2C isoenzymes, or blockade of large (BKCa)-conductance calcium-activated potassium channels with iberiotoxin, failed to reduce NS309 relaxation. In contrast to the pulmonary arteries, relaxations to a β2-adrenoceptor agonist, salbutamol, were reduced in bronchioles by removing the epithelium or blocking IKCa and/or SKCa channels. Extracellular K+ (2–20 mM) induced relaxation in both bronchioles and arteries. An inhibitor of Na+-K+-ATPase, ouabain, abolished relaxations to NS309, salbutamol, and K+. These results suggest that IKCa and SKCa3 channels are located in the epithelium of bronchioles and endothelium of pulmonary arteries. Analog to the endothelium-derived hyperpolarizing factor (EDHF)-type relaxation in pulmonary arteries, these channels may be involved in EpDHF-type relaxation of bronchioles caused by epithelial K+ efflux followed by activation of Na+-K+-ATPase in the underlying smooth muscle layer.
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Kohjitani, Atsushi, Takuya Miyawaki, Makoto Funahashi, Hitoshi Higuchi, Ryuji Matsuo, and Masahiko Shimada. "Ketamine and Midazolam Differentially Inhibit Nonadrenergic Noncholinergic Lower Esophageal Sphincter Relaxation in Rabbits." Anesthesiology 98, no. 2 (February 1, 2003): 449–58. http://dx.doi.org/10.1097/00000542-200302000-00026.
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Background The authors previously reported that ketamine and midazolam inhibited nitric oxide-mediated nonadrenergic noncholinergic (NANC) lower esophageal sphincter (LES) relaxation nitric oxide-3',5'-cyclic guanosine monophosphate pathway modulation. The mechanisms inhibiting the NANC relaxation by ketamine and midazolam were investigated. Methods The isometric tension of circular distal esophageal muscle strips from Japanese White rabbits was examined. NANC relaxation was induced by KCl (30 mm) in the presence of atropine (3 x 10(-6) m) and guanethidine (3 x 10(-6) m). Nitric oxide synthase activity in the absence and presence of ketamine and midazolam was analyzed using the biochemical conversion of L-[3H]arginine to L-[3H]citrulline. Results The ketamine-induced inhibition of the NANC relaxation was partly reversed by superoxide dismutase (200, 400 U/ml) but not by catalase (100 U/ml). Ketamine concentration-dependently inhibited the relaxation induced by N-ethylethanamine:1,1-diethyl-2-hydroxy-2-nitrosohydrazine (diethylamine NONOate) and S-nitrosoglutathione. The NANC relaxation itself was not affected by superoxide dismutase. The midazolam-induced inhibition of the NANC relaxation was reversed neither by superoxide dismutase nor by catalase, and midazolam did not affect the relaxations induced by nitric oxide donors. The nitric oxide synthase activity was concentration-dependently suppressed by midazolam, but there was no marked effect of ketamine. Pyrogallol, a superoxide generator, inhibited the NANC and the diethylamine NONOate-induced relaxations. The pyrogallol-induced inhibition of the NANC relaxation was reversed by superoxide dismutase. Conclusion These findings suggest that ketamine inhibits NANC LES relaxation by the extracellular production of superoxide anion, and that midazolam inhibits it by the inhibition of nitric oxide synthase activity.
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Laureckienė, Ginta, and Rimvydas Milašius. "Behaviour of Long-Lasting Stress Relaxation of Various Types of Yarns." Autex Research Journal 17, no. 4 (December 20, 2017): 379–85. http://dx.doi.org/10.1515/aut-2017-0017.
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Abstract The main goal of this researcher is estimating of the possibility of long-lasting (even until 200,000 s) stress relaxation by empirical investigation, which was performed for a few thousands of seconds. The empirical investigations of longlasting stress relaxation of different types of yarns (multifilament polyester, cotton and woollen) at different levels of elongation, i.e. at 3%, 5%, 7% and 10%, were carried out. The method of long-lasting relaxation behaviour prediction by the break-point of relaxation rate as well as the linear dependence of second part of relaxation were used. It was found that the behaviour of relaxation can be described using time logarithmic scale by two straight lines, and the value of stress relaxation in long time period could be estimated by the second line. The break-point of relaxation rate of all kinds of yarns occurs in the area of 100-200 s after relaxations started. The obtained results showed that the place of relaxation break-point depends on the level of elongation but does not depend on the type of yarns.
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Tripodo, Antonio, Francesco Puosi, Marco Malvaldi, Simone Capaccioli, and Dino Leporini. "Coincident Correlation between Vibrational Dynamics and Primary Relaxation of Polymers with Strong or Weak Johari-Goldstein Relaxation." Polymers 12, no. 4 (March 31, 2020): 761. http://dx.doi.org/10.3390/polym12040761.
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The correlation between the vibrational dynamics, as sensed by the Debye-Waller factor, and the primary relaxation in the presence of secondary Johari-Goldstein (JG) relaxation, has been investigated through molecular dynamics simulations. Two melts of polymer chains with different bond length, resulting in rather different strength of the JG relaxation are studied. We focus on the bond-orientation correlation function, exhibiting higher JG sensitivity with respect to alternatives provided by torsional autocorrelation function and intermediate scattering function. We find that, even if changing the bond length alters both the strength and the relaxation time of the JG relaxation, it leaves unaffected the correlation between the vibrational dynamics and the primary relaxation. The finding is in harmony with previous studies reporting that numerical models not showing secondary relaxations exhibit striking agreement with experimental data of polymers also where the presence of JG relaxation is known.
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Kalia, Sapna, J. K. Sharma, and Vandana Sharma. "Study of Dielectric Relaxation Behavior of Liquid Crystal Copolyester Vectra-A by Thermally Stimulated Discharge Current Technique." ISRN Polymer Science 2013 (March 27, 2013): 1–6. http://dx.doi.org/10.1155/2013/590682.
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The dielectric relaxation behavior of thermotropic liquid crystal copolyester of 73% of p-hydroxy-benzoic acid (HBA) and 27% of 2-hydroxy-6-naphthoic acid (HNA) (Vectra-A) at poling temperature 80°C has been studied using thermally stimulated depolarization current (TSDC) technique in the temperature range from 15°C to 250°C. The TSD currents were obtained for different polarizing fields ranging from 3.8 kV/cm to 19.2 kV/cm. TSD current spectra in the temperature range from 15°C to 250°C show three current maxima around 25°C, 110°C, and 220°C. The maxima around 25°C and 110°C correspond to characteristic dipolar relaxations β and α, respectively. The peak around 220°C is due to space charge effects named as δ-relaxation. The various relaxation parameters like activation energy (U), relaxation strength , preexponential factor , the quantity of charge released (Q) and concentration of trap for β- and α-relaxations at polarizing temperature 80°C for different polarizing fields were evaluated using Bucci-Fieschi fit. The linear variation between activation energy and natural logarithm of preexponential factor indicates the presence of compensation effect for dipolar relaxations of Vectra-A under present poling conditions.
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Hatano, Y., K. Mizumoto, T. Yoshiyama, M. Yamamoto, and H. Iranami. "Endothelium-dependent and -independent vasodilation of isolated rat aorta induced by caffeine." American Journal of Physiology-Heart and Circulatory Physiology 269, no. 5 (November 1, 1995): H1679—H1684. http://dx.doi.org/10.1152/ajpheart.1995.269.5.h1679.
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Caffeine (10(-4)-10(-3) M) induced concentration-dependent relaxations of phenylephrine-precontracted rat aortic rings with endothelium. Endothelial denudation significantly, but only partially, attenuated caffeine-induced relaxation. Pretreatment with NG-nitro-L-arginine, oxyhemoglobin, and methylene blue attenuated the relaxations to an extent similar to endothelial denudation. Guanosine 3',5'-cyclic monophosphate (cGMP) and adenosine 3',5'-cyclic monophosphate (cAMP) contents of aortic strips with endothelium increased significantly after exposure to caffeine (10(-3) M). Endothelial denudation attenuated caffeine-induced cGMP increase. Pretreatment with ryanodine (2 x 10(-5) M), which has been shown to combine with receptors on endoplasmic reticulum (ER) of endothelium, attenuated caffeine-induced relaxation and cGMP content increase of rings with endothelium. Pretreatment with caffeine potentiated sodium nitroprusside-induced relaxations and cGMP increase of rings without endothelium. These results demonstrated that caffeine-induced relaxation comprises two components. In the endothelium-dependent mechanism, caffeine promotes nitric oxide synthesis in endothelium by release of Ca2+ from ER through a ryanodine-sensitive Ca2+ channel, and the suppression of cGMP degradation also contributes to the relaxation. In the endothelium-independent mechanism, caffeine acts as a 3',5'-cyclic-nucleotide phosphodiesterase inhibitor.
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Najibi, S., C. L. Cowan, J. J. Palacino, and R. A. Cohen. "Enhanced role of potassium channels in relaxations to acetylcholine in hypercholesterolemic rabbit carotid artery." American Journal of Physiology-Heart and Circulatory Physiology 266, no. 5 (May 1, 1994): H2061—H2067. http://dx.doi.org/10.1152/ajpheart.1994.266.5.h2061.
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The effect of hypercholesterolemia for 10 wk on endothelium-dependent relaxations to acetylcholine was studied in isolated rings of rabbit carotid artery and abdominal aorta contracted with phenylephrine or elevated potassium. In these arteries obtained from hypercholesterolemic rabbits, endothelium-dependent relaxations to acetylcholine were not significantly different from those of normal rabbits. In normal and hypercholesterolemic arteries, partial relaxation persisted in the presence of NG-nitro-L-arginine methyl ester (L-NAME), which blocked acetylcholine-induced increases in arterial guanosine 3',5'-cyclic monophosphate (cGMP). Combined treatment with L-NAME and the calcium-dependent potassium-channel inhibitor, charybdotoxin, blocked relaxations in both groups, suggesting that L-NAME-resistant relaxations are mediated by an endothelium-derived hyperpolarizing factor. Charybdotoxin alone or depolarizing potassium had no significant effect on normal carotid artery or normal and hypercholesterolemic abdominal aorta but significantly inhibited relaxations of the carotid artery from cholesterol-fed rabbits. The enhanced role of calcium-dependent potassium channels and the hyperpolarizing factor in relaxation of the hypercholesterolemic carotid artery suggested by these results was likely related to the fact that acetylcholine failed to stimulate cGMP only in that artery. These data suggest that endothelium-dependent relaxation in these rabbit arteries is mediated by nitric oxide-cGMP-dependent and -independent mechanisms. In hypercholesterolemia, the contribution of nitric oxide-cGMP in the carotid artery is reduced, but a hyperpolarizing factor and calcium-dependent potassium channels maintain normal acetylcholine-induced relaxation.
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Diederich, D., J. Skopec, A. Diederich, and F. X. Dai. "Endothelial dysfunction in mesenteric resistance arteries of diabetic rats: role of free radicals." American Journal of Physiology-Heart and Circulatory Physiology 266, no. 3 (March 1, 1994): H1153—H1161. http://dx.doi.org/10.1152/ajpheart.1994.266.3.h1153.
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Diabetes was induced in rats by an injection of streptozotocin (55 mg/kg). Endothelium-dependent relaxations in mesenteric resistance arteries (luminal diameter 210 +/- 20 microns) of control and diabetic rats were compared in myographs. Acetylcholine induced endothelium-dependent relaxations that were mediated by nitric oxide (EDNO). EDNO-mediated relaxations were impaired in diabetic arteries; concentrations of acetylcholine required to produce 50% relaxation (ED50) of activated arteries were 5 nM in control and 13.5 nM in arteries from diabetic rats studied after 6 wk (P < 0.05). The impairment in relaxation worsened with duration of the diabetes; ED50 for acetylcholine increased to 63 and 100 nM in diabetic arteries studied after 16 and 24 wk of diabetes, respectively. NG-nitro-L-arginine produced 5.5- and 16-fold decreases in sensitivity of control and diabetic arteries to acetylcholine. NG-nitro-L-arginine produced at least as much inhibition of acetylcholine relaxations in diabetic arteries, indicating that the impaired relaxation noted in diabetic arteries does not result from decreased production of EDNO. EDNO-mediated relaxations in diabetic arteries were impaired by increased production of endothelium-derived free radicals. Superoxide dismutase, a scavenger of superoxide anion, and dimethylthiourea, a scavenger of hydroxyl radicals, normalized EDNO-mediated relaxations in diabetic arteries. The ED50 values for acetylcholine were 13.5, 5.5, and 4 nM for untreated and SOD- and DMTU-treated diabetic arteries, respectively (P < 0.05 for treated vs. untreated arteries). Superoxide anion and hydroxyl radicals appear to block EDNO-mediated relaxation by inactivating EDNO.(ABSTRACT TRUNCATED AT 250 WORDS)
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MEVISSEN, MARTIN, and MASAKAZU KOJIMA. "SDP RELAXATIONS FOR QUADRATIC OPTIMIZATION PROBLEMS DERIVED FROM POLYNOMIAL OPTIMIZATION PROBLEMS." Asia-Pacific Journal of Operational Research 27, no. 01 (February 2010): 15–38. http://dx.doi.org/10.1142/s0217595910002533.
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Based on the convergent sequence of SDP relaxations for a multivariate polynomial optimization problem (POP) by Lasserre (2006), Waki et al. (2006) constructed a sequence of sparse SDP relaxations to solve sparse POPs efficiently. Nevertheless, the size of the sparse SDP relaxation is the major obstacle in order to solve POPs of higher degree. This paper proposes an approach to transform general POPs to quadratic optimization problems (QOPs), which allows to reduce the size of the SDP relaxation substantially. We introduce different heuristics resulting in equivalent QOPs and show how sparsity of a POP is maintained under the transformation procedure. As the most important issue, we discuss how to increase the quality of the SDP relaxation for a QOP. Moreover, we increase the accuracy of the solution of the SDP relaxation by applying additional local optimization techniques. Finally, we demonstrate the high potential of this approach through numerical results for large scale POPs of higher degree.
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Yang, L. Q., B. Huang, J. Yi, N. Z. Zhang, C. Geng, Y. Yang, X. X. Shui, and G. Wang. "Influence of magnetic interaction on configurational-entropy-suppressed β-relaxations in FeNi-based metallic glasses." AIP Advances 12, no. 6 (June 1, 2022): 065304. http://dx.doi.org/10.1063/5.0088052.
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In this article, we studied the effect of magnetic interaction on β-relaxations of FexNi72−xSi4.8B19.2Nb4 (x = 0, 10, 30, 50, 72) metallic glasses (MGs). It is found that, with the substitution of Fe by Ni, the β-relaxation changes from a shoulder to an excess wing, suggesting an entropic effect on the suppression of β-relaxation. A peak caused by ferromagnetic transformation appears in the loss modulus curve of Fe30Ni42Si4.8B19.2Nb4 MG with suppressed β-relaxation, which is sensitive to stress and strain. In addition, the β-relaxation can be further varied by annealing under a transverse or longitudinal magnetic field. The results suggest that the entropy-suppressed β-relaxation in MGs can be affected by magnetic interaction that could help to improve their mechanical properties.
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Shahin, W., J. A. Murray, E. Clark, and J. L. Conklin. "Role of cGMP as a mediator of nerve-induced motor functions of the opossum esophagus." American Journal of Physiology-Gastrointestinal and Liver Physiology 279, no. 3 (September 1, 2000): G567—G574. http://dx.doi.org/10.1152/ajpgi.2000.279.3.g567.
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Stimulation of esophageal nerves produces biphasic relaxation of the lower esophageal sphincter (LES) and an off response of circular esophageal muscle. Previously, we proposed that cGMP mediates nerve-induced hyperpolarization of circular LES muscle but not LES relaxation. These experiments explore whether cGMP mediates LES relaxation or the off response. Strips of muscle from the opossum esophagus and LES were connected to force-displacement transducers, placed in tissue baths containing oxygenated Krebs solution at 37°C, and stimulated by an electrical field. 1H-[1,2,4]oxadiazolo-[4,3- a]quinoxalin-1-one (ODQ), a selective inhibitor of guanylyl cyclase, antagonized the off response, shortened its latency, and blocked the first phase of LES relaxation. ODQ also antagonized LES relaxation by exogenous nitric oxide (NO) but not relaxations by vasoactive intestinal polypeptide (VIP). Part of the nerve-induced LES relaxation and the off response appear to be mediated by the second messenger cGMP. These studies indicate that VIP-induced LES relaxation is not mediated by cGMP and therefore do not support the hypothesis that VIP produces LES relaxation by causing the generation of NO.
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Oliveira, L. C., H. A. Gomide, and R. S. L. Rade. "Primary creep behaviour of polyester resins from multiple relaxation curves." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 217, no. 12 (December 1, 2003): 1301–13. http://dx.doi.org/10.1243/095440603322769947.
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Typical primary creep behaviour of a viscoelastoplastic material is shown when varying the temperature and the time rate of strain (of a previous tension). The creep behaviour is obtained from the tension test with multiple relaxations, where a numerical procedure is used in order to obtain creep curves from a series of relaxation curves. This test methodology allows interrelated tension, relaxation and creep behaviours to be obtained from one single test. The materials tested are proportional to the weight mixtures of rigid/flexible polyester resins with hardeners, generally used as model materials in photomechanics. With the increase in temperature, there is a decrease in the time needed to reach a given creep strain. The time rate of the strain, used in the tensions prior to the relaxations, has a considerable influence on the beginning of the relaxations. Since the creep curve is obtained from these relaxations, the rate of strain is shown to have an influence on creep behaviour, depending on the portion of the relaxation curve from where values are taken for calculation of creep.
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Eguchi, Daihiko, and Zvonimir S. Katusic. "Inhibitory effect of valves on endothelium-dependent relaxations to calcium ionophore in canine saphenous vein." American Journal of Physiology-Heart and Circulatory Physiology 280, no. 2 (February 1, 2001): H892—H898. http://dx.doi.org/10.1152/ajpheart.2001.280.2.h892.
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The present study was designed to evaluate endothelium-dependent relaxation to the calcium ionophore A-23187 in isolated canine saphenous veins. Isometric force recordings and cGMP measurements using isolated veins with and without valves were performed. During contractions to U-46619 (3 × 10−7 M), endothelium-dependent relaxations to A-23187 (10−9–10−6 M) were significantly reduced in rings with valves compared with rings without valves. Endothelial removal abolished A-23187-induced relaxation. Relaxations to forskolin (FK; 10−8–10−5 M) and diethylaminodiazen-1-ium-1,2-dionate; DEA-NONOate, 10−9–10−5 M) were identical in rings with and without valves. In rings without valves, a nitric oxide synthase inhibitor, N G-nitro-l-arginine methyl ester (l-NAME; 3 × 10−4 M), and a cyclooxygenase inhibitor, indomethacin (10−5 M), partially reduced A-23187-induced relaxation. However, in rings with valves,l-NAME had no effect, whereas indomethacin abolished the relaxation to A-23187. A selective soluble guanylate cyclase inhibitor, 1 H-[1,2,4]-oxadiazolo [4,3-a]quinoxalin-1-one (ODQ; 3×10−6 M), had no effect on the relaxation to A-23187 in either group. In contrast, ODQ abolished the A-23187-induced increase in cGMP levels, suggesting that relaxation to nitric oxide released by A-23187 is independent of increases in cGMP. These results demonstrate that endothelium-dependent relaxation to A-23187 is reduced in regions of veins with valves compared with relaxation in the nonvalvular venous wall. Lower production of nitric oxide in endothelial cells of valvular segments appears to be a mechanism responsible for reduced reactivity to A-23187.
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Peng, Si-Xu, Yudong Cheng, Julian Pries, Shuai Wei, Hai-Bin Yu, and Matthias Wuttig. "Uncovering β-relaxations in amorphous phase-change materials." Science Advances 6, no. 2 (January 2020): eaay6726. http://dx.doi.org/10.1126/sciadv.aay6726.
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Relaxation processes are decisive for many physical properties of amorphous materials. For amorphous phase-change materials (PCMs) used in nonvolatile memories, relaxation processes are, however, difficult to characterize because of the lack of bulk samples. Here, instead of bulk samples, we use powder mechanical spectroscopy for powder samples to detect the prominent excess wings—a characteristic feature of β-relaxations—in a series of amorphous PCMs at temperatures below glass transitions. By contrast, β-relaxations are vanishingly small in amorphous chalcogenides of similar composition, which lack the characteristic features of PCMs. This conclusion is corroborated upon crossing the border from PCMs to non-PCMs, where β-relaxations drop substantially. Such a distinction implies that amorphous PCMs belong to a special kind of covalent glasses whose locally fast atomic motions are preserved even below the glass transitions. These findings suggest a correlation between β-relaxation and crystallization kinetics of PCMs, which have technological implications for phase-change memory functionalities.
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Ivanov, Ivan T., and Boyana K. Paarvanova. "Role of Plasma Membrane at Dielectric Relaxations and Intermembrane Interaction in Human Erythrocytes." Membranes 13, no. 7 (July 11, 2023): 658. http://dx.doi.org/10.3390/membranes13070658.
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Dielectric relaxations at 1.4 MHz (βsp) and 9 MHz (γ1sp) on the erythrocyte spectrin network were studied by dielectric spectroscopy using dense suspensions of erythrocytes and erythrocyte ghost membranes, subjected to extraction with up to 0.2% volume Triton-X-100. The step-wise extraction of up to 60% of membrane lipids preserved γ1sp and gradually removed βsp-relaxation. On increasing the concentration up to 100 mM of NaCl at either side of erythrocyte plasma membranes, the βsp-relaxation was linearly enhanced, while the strength of γ1sp-relaxation remained unchanged. In media with NaCl between 100 and 150 mM βsp-relaxation became slightly inhibited, while γ1sp-relaxation almost disappeared, possibly due to the decreased electrostatic repulsion allowing erythrocytes to come into closer contact. When these media contained, at concentrations 10–30 mg/mL dextran (MW 7 kDa), polyethylene glycol or polyvinylpyrrolidone (40 kDa), or albumin or homologous plasma with equivalent concentration of albumin, the γ1sp-relaxation was about tenfold enhanced, while βsp-relaxation was strengthened or preserved. The results suggest the Maxwell–Vagner accumulation of ions on the lipid bilayer as an energy source for βsp-relaxation. While βsp-relaxation appears sensitive to erythrocyte membrane deformability, γ1sp-relaxation could be a sensitive marker for the inter-membrane interactions between erythrocytes.
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Williams, S. P., G. W. Dorn, and R. M. Rapoport. "Prostaglandin I2 mediates contraction and relaxation of vascular smooth muscle." American Journal of Physiology-Heart and Circulatory Physiology 267, no. 2 (August 1, 1994): H796—H803. http://dx.doi.org/10.1152/ajpheart.1994.267.2.h796.
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Prostaglandin (PG) I2 elicits a biphasic concentration-response curve in rat aorta: lower concentrations elicit relaxation, whereas at higher concentrations, the relaxation is reversed. The purpose of this study was to investigate 1) the nature of the receptors that mediate these effects and 2) whether the relaxant efficacy of PGI2 is decreased at higher PGI2 concentrations by PGI2-induced contraction. PGI2 (1 microM), the stable PGI2 analogue carbacyclin (1 microM), and PGE1 (3 microM) induced maximal relaxations of 55, 40, and 63%, respectively, of norepinephrine-contracted aorta, whereas higher concentrations of PGI2, carbacyclin, and PGE1 reversed the relaxation. The thromboxane (Tx) A2-PGH2 receptor antagonist, SQ-29548, abolished the reversal of the PGI2-, carbacyclin-, and PGE1-induced relaxation, and maximal relaxations to PGI2, carbacyclin, and PGE1 increased to 73, 85, and 89% of the norepinephrine contraction, respectively, with 50% effective concentrations of 0.16, 0.43, and 0.83 microM, respectively. PGE2 and PGD2 did not induce relaxation in the presence or absence of SQ-29548. PGI2 and carbacyclin displaced the TxA2-PGH2 receptor ligand 1S-[1 alpha,2 beta(5Z),3 alpha(1E,3S),4 alpha]-7-(3-[3-hydroxy-4-(p- [125I]iodophenoxy)-1-butenyl]7-oxabicyclo[2.2.1]hept-2-yl]-5- heptenoic acid from cultured rat aorta smooth muscle cells with concentrations of competing ligand that displaced 50% of the specifically bound radioligand from its binding site of 6.0 and 2.3 microM, respectively. These results suggest that 1) PGI2 induces relaxation through a PGI2-PGE1 receptor, and 2) higher concentrations of PGI2 act at the TxA2-PGH2 receptor to decrease PGI2-induced relaxation.
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SHARMA, R. R. K., and A. MURALIDHAR. "A NEW FORMULATION AND RELAXATION OF THE SIMPLE PLANT LOCATION PROBLEM." Asia-Pacific Journal of Operational Research 26, no. 01 (February 2009): 1–11. http://dx.doi.org/10.1142/s0217595909002122.
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In this paper a new formulation of the simple plant location problem (SPLP) is given that uses the style of Sharma and Sharma (European Journal of Operational Research, 122(3), 37–48). When the integer restrictions are relaxed, it results in a new relaxation of SPLP that is different from the already well known "strong" and "weak" relaxation of SPLP. It is shown that the bound given by the new relaxation is worse than the bound given by "strong relaxation" of SPLP. However, a numerical example illustrates that the bound given by the new relaxation can at times be better than the bound given by "weak relaxation" (already known) of SPLP. In this paper a new proof [which is different from the one given by Bilde and Krarup (Annals of Discrete Mathematics, 1, 79–97)] is given to establish relative strengths of various relaxations of SPLP.
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Das, Chinmay, and Daniel J. Read. "A tube model for predicting the stress and dielectric relaxations of polydisperse linear polymers." Journal of Rheology 67, no. 3 (May 2023): 693–721. http://dx.doi.org/10.1122/8.0000605.
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We present an algorithm to predict the linear relaxation spectra for linear polymers of fully general and arbitrary polydispersity. As is common in the tube theory descriptions of linear polymers, we assume that the stress relaxation is affected by both the constraint release and tube escape modes, but unlike most existing descriptions we consider how these two modes of relaxation affect each other. We argue that the proper description for relaxation in an arbitrary blend of linear polymers requires consideration of multiple embedded tubes affecting the different relaxation pathways; we propose a novel but minimal description involving five embedded tubes. Building on prior work for binary blends, we derive the scaling level descriptions of the relaxation pathways. We use a large number of existing experimental results on the stress and dielectric relaxations to validate our model, ensuring we explore a very broad range of parameter space.
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Yetik-Anacak, Gunay, Tian Xia, Christiana Dimitropoulou, Richard C. Venema, and John D. Catravas. "Effects of hsp90 binding inhibitors on sGC-mediated vascular relaxation." American Journal of Physiology-Heart and Circulatory Physiology 291, no. 1 (July 2006): H260—H268. http://dx.doi.org/10.1152/ajpheart.01027.2005.
Full textAbstract:
Vascular soluble guanylate cyclase (sGC) exists in multimeric complexes with endothelial nitric oxide (NO) synthase (eNOS) and heat shock protein 90 (hsp90). Whereas disruption of hsp90-eNOS complexes clearly attenuates eNOS-dependent vascular relaxation, the contribution of sGC-hsp90 complexes to eNOS- or NO donor-dependent relaxations remains unclear. Isolated rat thoracic aortic rings were preincubated with structurally diverse hsp90 binding inhibitors, radicicol (RA) or geldanamycin (GA), or vehicle for 0.5, 1, or 15 h. Preconstricted vessels were exposed to ACh, 8-bromo-cGMP (8-BrcGMP), forskolin, or one of three NO donors: nitroglycerin (NTG), sodium nitroprusside, or spermine NONOate (SNN). Both RA and GA inhibited endothelium-dependent relaxations dose dependently. Indomethacin or the antioxidant tiron did not affect the inhibition of ACh-induced relaxations by GA. Long-term (15 h) exposure to RA inhibited all NO donor-induced relaxations; however, GA inhibited SNN-induced relaxation only. The effects of GA and RA appeared to be selective because 15-h treatment with either agent did not affect forskolin-induced relaxations and only slightly decreased 8-BrcGMP-induced relaxations. Similarly to their effects on NO-donor-induced relaxation, 15-h exposure to RA, but not to GA, decreased hsp90-bound sGC protein expression and NTG-stimulated cGMP formation in aortic rings, whereas RA more than GA reduced SNN-stimulated cGMP formation. We conclude that RA, much more so than GA, selectively inhibits sGC-dependent relaxations of aortic rings by reducing sGC expression, disrupting sGC-hsp90 complex formation and decreasing cGMP formation. These studies suggest that hsp90 regulates both eNOS- and sGC-dependent relaxations.
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Dingwell, Donald B., and Sharon L. Webb. "Relaxation in silicate melts." European Journal of Mineralogy 2, no. 4 (August 31, 1990): 427–51. http://dx.doi.org/10.1127/ejm/2/4/0427.
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ChongNak Son. "Relaxation Techniques, Relaxation Theories, and Relaxation States." Korean Journal of Health Psychology 17, no. 4 (December 2012): 793–822. http://dx.doi.org/10.17315/kjhp.2012.17.4.003.
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Ohhashi, T., and N. Takahashi. "Acetylcholine-induced release of endothelium-derived relaxing factor from lymphatic endothelial cells." American Journal of Physiology-Heart and Circulatory Physiology 260, no. 4 (April 1, 1991): H1172—H1178. http://dx.doi.org/10.1152/ajpheart.1991.260.4.h1172.
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Ring segments of dog thoracic ducts precontracted with a high concentration of norepinephrine (NE) relaxed in a concentration-dependent manner in response to acetylcholine (ACh) or sodium nitroprusside (SNP). Pretreatment with atropine inhibited the ACh-induced relaxation in a competitive manner. The Schild plot showed a slope of 1.1 +/- 0.2 and a pA2 value of 10.4 +/- 0.4 (n = 6 ring segments). Removal of endothelium caused a complete inhibition of the ACh-induced relaxations in precontracted dog thoracic ducts. ACh, which failed to relax precontraction of the ring segment when mounted separately, induced relaxation in the same preparation when it was mounted as a "sandwich" with the longitudinal strip. The ACh-induced relaxations in the lymphatic preparations with endothelium were suppressed or abolished by pretreatment with oxyhemoglobin (10(-6) and 10(-5) M), methylene blue (10(-6) and 10(-5) M), and NG-monomethyl-L-arginine (3 x 10(-5) M), but the relaxations were unaffected by aspirin (10(-5) M). Pretreatment with methylene blue (10(-5) M) also caused a significant reduction of the SNP-induced relaxations in the precontracted thoracic ducts. It may be concluded that ACh-induced relaxation in dog thoracic ducts precontracted with NE is mediated by high-affinity muscarinic receptors in the lymphatic endothelial cells. Also, stimulation of the endothelial muscarinic receptors liberates a transferable endothelium-derived relaxing factor, which results in the relaxation of the lymphatic smooth muscles via the accumulation of cellular guanosine 3',5'-cyclic monophosphate.
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Setiyono, Agus, Yeni Kartika Sari, and Yohanes Kusuma Pribadi. "The Effect of Benson Relaxation on Anxiety Levels In Major Surgical Preoperative Patients in the Dahlia Room Mardi Waluyo Blitar Hospital." Health Gate 1, no. 4 (October 29, 2023): 135–40. http://dx.doi.org/10.33846/hg1404.
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Surgery can cause excessive fear and anxiety and can lead to complications. To reduce anxiety, non-pharmacological techniques is Benson Relaxation Therapi which is carried out by deep breathing and accompanied by beliefs held by the patient to achieve a relaxed state. Population on this research is preoperative major surgery patients. Sampling technique with Purposive Sampling 22 respondent. This research method : Quasy Experimental with One Group Pre-Test Post-Test, using questionnaire sheets, Standard Operating Procedures of Benson’s Relaxations, and Wilcoxon Sign Rank Test analysis. The purpose of study to determine the effect of Benson’s Relaxations on anxiety levels in preoperative major surgery patients. The Results of the Study : Using the analysis with the results of p-value = 0.000 which means <0.005. Conclusion : There is an effect of Benson’s Relaxation on the anxiety levels of pre operative major surgery patients. With the result of this reseach be used as a reference for Mardi Waluyo Blitar District Hospital in publishing of SPO Benson’s Relaxation it can be used to treat anxiety non-pharmacologically. Beside that, of nurses are expected to be able and willing to implement of Benson’s Relaxation which is proven effective in treating anxiety patients in all patients who experience anxiety in general.Keywords : Surgery, Benson Relaxation Technique, Anxiety
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Kähönen, Mika, Kirsi Karjala, Nina Hutri-Kähönen, Xiumin Wu, Pia Jaatinen, Päivi Riihioja, Antti Hervonen, and Ilkka Pörsti. "Influence of chronic ethanol consumption on arterial tone in young and aged rats." American Journal of Physiology-Heart and Circulatory Physiology 276, no. 2 (February 1, 1999): H464—H471. http://dx.doi.org/10.1152/ajpheart.1999.276.2.h464.
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The aim of this work was to evaluate the effects of long-term ethanol consumption on arterial responses in vitro in young and aged rats. Therefore, Wistar rats (ages 3 and 29 mo, respectively) were allocated to six groups: control-young, sucrose-young, ethanol-young, control-aged, sucrose-aged, and ethanol-aged. The ethanol-fed groups were given 25% ethanol by intragastric gavage three times a day 4 days a week. Responses of mesenteric arterial rings were examined in standard organ chambers after 5 treatment weeks. In norepinephrine-precontracted arterial rings, endothelium-dependent relaxations to acetylcholine, as well as endothelium-independent relaxations to isoproterenol, were attenuated in aged rats when compared with young controls. Relaxation responses to isoproterenol, but not to acetylcholine and nitroprusside, were clearly improved by ethanol treatment in both young and aged rats. The cyclooxygenase inhibitor diclofenac, which reduces the synthesis of dilating and constricting prostanoids, enhanced the relaxation to acetylcholine in all three aged rat groups but was without significant effect in the young rats. In the presence of the nitric oxide synthase inhibitor N G-nitro-l-arginine methyl ester the relaxation to acetylcholine in control and sucrose-fed aged rats was markedly reduced compared with control rats, whereas in the young controls and in both young and aged ethanol-exposed groups, distinct relaxations to higher concentrations of acetylcholine were still present. The endothelium-independent relaxations to cromakalim, a hyperpolarizing vasodilator acting via ATP-sensitive potassium channels, were also markedly augmented by ethanol feeding in both young and aged rats. In conclusion, ethanol consumption in both young and aged rats was associated with markedly improved arterial relaxations to isoproterenol and cromakalim, as well as clearly augmented relaxation to acetylcholine during inhibition of cyclooxygenase and nitric oxide synthase. These findings suggest that especially the potassium channel-related component of arterial relaxation was augmented by long-term ethanol exposure.
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Masuda, Hitoshi, Toshihiko Tsujii, Tetsuo Okuno, Kazunori Kihara, Moritaka Goto, and Hiroshi Azuma. "Accumulated endogenous NOS inhibitors, decreased NOS activity, and impaired cavernosal relaxation with ischemia." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 282, no. 6 (June 1, 2002): R1730—R1738. http://dx.doi.org/10.1152/ajpregu.00277.2001.
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We examined whether endogenous inhibitors of nitric oxide (NO) synthesis are involved in the impaired cavernosal relaxation with ischemia in rabbits. Two weeks after cavernosal ischemia caused by partial vessel occlusion, endothelium-dependent and electrical field stimulation (EFS)-induced neurogenic NO-mediated relaxations, but not sodium nitroprusside (SNP)-induced relaxation, were significantly impaired in the isolated corpus cavernosum. The Ca2+-dependent NO synthase (NOS) activity and the basal and stimulated cGMP productions with carbachol or EFS were significantly decreased after ischemia. Supplementation of excessl-arginine partially recovered both of the impaired relaxations. The contents of N G-monomethyl-l-arginine (l-NMMA) and asymmetric N G, N G-dimethyl-l-arginine (ADMA) but not l-arginine and symmetric N G, N′G-dimethyl-l-arginine (SDMA) were increased in the cavernosal tissues after ischemia. Authentic l-NMMA and ADMA but not SDMA concentration dependently inhibited both relaxations without affecting the relaxation produced by SNP in the control. Excess l-arginine abolished the inhibition with l-NMMA and ADMA. These results suggest that the impaired NO-mediated cavernosal relaxations after ischemia are closely related to the decreased NOS activity and the increased accumulation of l-NMMA and ADMA.
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Decressain, R., and L. Carpentier. "Influence of the preparation method (thermal quench, ball-milling, dehydration and freeze-drying) on the dynamical properties of glassy trehalose." Physica Scripta 99, no. 7 (June 17, 2024): 075965. http://dx.doi.org/10.1088/1402-4896/ad5115.
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Abstract Dielectric relaxation measurements have been performed on the glassy states of trehalose reached using different routes of amorphisation: thermal quench of the liquid state, milling of the anhydrous crystalline form, freeze-drying and dehydration of the dihydrate crystalline form. This study has revealed that all the glassy states are characterized by two relaxation processes respectively attributed to the slow Johari-Goldstein mode and to fast secondary intramolecular relaxations. These sub-Tg secondary relaxations are however strikingly different in the four glassy states revealing different energy landscape topologies.
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Yi, Xiu-Yu, Kathryn M. Gauthier, Lijie Cui, Kasem Nithipatikom, John R. Falck, and William B. Campbell. "Metabolism of adrenic acid to vasodilatory 1α,1β-dihomo-epoxyeicosatrienoic acids by bovine coronary arteries." American Journal of Physiology-Heart and Circulatory Physiology 292, no. 5 (May 2007): H2265—H2274. http://dx.doi.org/10.1152/ajpheart.00947.2006.
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Adrenic acid (docosatetraenoic acid), an abundant fatty acid in the vasculature, is produced by a two-carbon chain elongation of arachidonic acid. Despite its abundance and similarity to arachidonic acid, little is known about its role in the regulation of vascular tone. Gas chromatography/mass spectrometric analysis of bovine coronary artery and endothelial cell lysates revealed arachidonic acid concentrations of 2.06 ± 0.01 and 6.18 ± 0.60 μg/mg protein and adrenic acid concentrations of 0.29 ± 0.01 and 1.56 ± 0.16 μg/mg protein, respectively. In bovine coronary arterial rings preconstricted with the thromboxane mimetic U-46619, adrenic acid (10−9–10−5 M) induced concentration-related relaxations (maximal relaxation = 83 ± 4%) that were similar to arachidonic acid relaxations. Adrenic acid relaxations were blocked by endothelium removal and the K+ channel inhibitor, iberiotoxin (100 nM), and inhibited by the cyclooxygenase inhibitor, indomethacin (10 μM, maximal relaxation = 53 ± 4%), and the cytochrome P-450 inhibitor, miconazole (10 μM, maximal relaxation = 52 ± 5%). Reverse-phase HPLC and liquid chromatography/mass spectrometry isolated and identified numerous adrenic acid metabolites from coronary arteries including dihomo (DH)-epoxyeicosatrienoic acids (EETs) and DH-prostaglandins. DH-EET [16,17-, 13,14-, 10,11-, and 7,8- (10−9–10−5 M)] induced similar concentration-related relaxations (maximal relaxations averaged 83 ± 3%). Adrenic acid (10−6 M) and DH-16,17-EET (10−6 M) hyperpolarized coronary arterial smooth muscle. DH-16,17-EET (10−8–10−6 M) activated iberiotoxin-sensitive, whole cell K+ currents of isolated smooth muscle cells. Thus, in bovine coronary arteries, adrenic acid causes endothelium-dependent relaxations that are mediated by cyclooxygenase and cytochrome P-450 metabolites. The adrenic acid metabolite, DH-16,17-EET, activates smooth muscle K+ channels to cause hyperpolarization and relaxation. Our results suggest a role of adrenic acid metabolites, specifically, DH-EETs as endothelium-derived hyperpolarizing factors in the coronary circulation.
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Suh, Daewoong, and Reinhold H. Dauskardt. "Mechanical Relaxation Time Scales in a Zr–Ti–Ni–Cu–Be Bulk Metallic Glass." Journal of Materials Research 17, no. 6 (June 2002): 1254–57. http://dx.doi.org/10.1557/jmr.2002.0188.
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The relaxation time scales in a commercial-grade Zr41.25Ti13.75Ni10Cu12.5Be22.5 (at.%) bulk metallic glass were examined using transient and dynamic mechanical experiments. The viscoelastic and sub-Tg relaxations were well described by the Kohlrausch–Williams–Watts relaxation function. A large activation energy (4.0 eV) and small nonexponentiality parameter (approximately 0.5) were observed for viscoelastic relaxation above Tg consistent with the cooperative nature of atomic movements leading ultimately to viscous flow. Conversely, a small activation energy (0.1 eV) and large nonexponentiality parameter (approximately 0.9) were observed for the sub-Tg relaxation suggesting localized atomic adjustments which may involve different structural units or mechanisms. The glass transition was manifested as a decoupling of the sub-Tg and viscoelastic relaxation. The resulting transition temperature determined at a selected time scale was in agreement with the value obtained from calorimetric studies.
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Ishiguchi, Tadashi, Toku Takahashi, Hidekazu Itoh, and Chung Owyang. "Nitrergic and purinergic regulation of the rat pylorus." American Journal of Physiology-Gastrointestinal and Liver Physiology 279, no. 4 (October 1, 2000): G740—G747. http://dx.doi.org/10.1152/ajpgi.2000.279.4.g740.
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The role of nitric oxide (NO) and ATP in the regulation of nonadrenergic, noncholinergic (NANC) inhibitory transmission in the pylorus remains unclear. In the presence of atropine and guanethidine, electric field stimulation induced NANC relaxations in a frequency-dependent manner (1–20 Hz) in the rat pylorus. NANC relaxations were significantly inhibited by N G-nitro-l-arginine methyl ester (l-NAME; 10−4 M). P2Xpurinoceptor antagonist pyridoxal phosphate-6-azophenyl-2′,4′-disulfonic acid (PPADS; 3 × 10−5 M) and P2Y purinoceptor antagonist reactive blue 2 (2 × 10−5 M) had no effect on NANC relaxations. However, the combined administration of l-NAME and PPADS, but not reactive blue 2, evoked greater inhibitory effects on NANC relaxation than that evoked by l-NAME alone. α-Chymotrypsin and vasoactive intestinal polypeptide antagonist did not affect NANC relaxations. ATP (10−5–10−3 M) and P2Xpurinoceptor agonist α,β-methyleneadenosine 5′-triphosphate (10−7−10−5 M), but not P2Ypurinoceptor agonist 2-methylthioadenosine 5′-triphosphate (10−7−10−5 M), induced muscle relaxations in a dose-dependent manner, and relaxations were significantly reduced by PPADS and unaffected by TTX. These studies suggest that NO and ATP act in concert to mediate NANC relaxation of the rat pylorus. ATP-induced relaxation appears to be mediated by P2X purinoceptors located on smooth muscle cells.
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Cheng, Zhongjian, Xiaohua Jiang, Warren D. Kruger, Domenico Praticò, Sapna Gupta, Karthik Mallilankaraman, Muniswamy Madesh, et al. "Hyperhomocysteinemia impairs endothelium-derived hyperpolarizing factor–mediated vasorelaxation in transgenic cystathionine beta synthase–deficient mice." Blood 118, no. 7 (August 18, 2011): 1998–2006. http://dx.doi.org/10.1182/blood-2011-01-333310.
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Abstract Hyperhomocysteinemia (HHcy) is associated with endothelial dysfunction (ED), but the mechanism is largely unknown. In this study, we investigated the role and mechanism of HHcy-induced ED in microvasculature in our newly established mouse model of severe HHcy (plasma total homocysteine, 169.5μM). We found that severe HHcy impaired nitric oxide (NO)– and endothelium-derived hyperpolarizing factor (EDHF)–mediated, endothelium-dependent relaxations of small mesenteric arteries (SMAs). Endothelium-independent and prostacyclin-mediated endothelium-dependent relaxations were not changed. A nonselective Ca2+-activated potassium channel (KCa) inhibitor completely blocked EDHF-mediated relaxation. Selective blockers for small-conductance KCa (SK) or intermediate-conductance KCa (IK) failed to inhibit EDHF-mediated relaxation in HHcy mice. HHcy increased the levels of SK3 and IK1 protein, superoxide (O2−), and 3-nitrotyrosine in the endothelium of SMAs. Preincubation with antioxidants and peroxynitrite (ONOO−) inhibitors improved endothelium-dependent and EDHF-mediated relaxations and decreased O2− production in SMAs from HHcy mice. Further, EDHF-mediated relaxation was inhibited by ONOO− and prevented by catalase in the control mice. Finally, L-homocysteine stimulated O2− production, which was reversed by antioxidants, and increased SK/IK protein levels and tyrosine nitration in cultured human cardiac microvascular endothelial cells. Our results suggest that HHcy impairs EDHF relaxation in SMAs by inhibiting SK/IK activities via oxidation- and tyrosine nitration–related mechanisms.
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HAMILTON, C. A., G. BERG, K. MCARTHUR, J. L. REID, and A. F. DOMINICZAK. "Does potassium channel opening contribute to endothelium-dependent relaxation in human internal thoracic artery?" Clinical Science 96, no. 6 (May 11, 1999): 631–38. http://dx.doi.org/10.1042/cs0960631.
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Opening of potassium channels can cause hyperpolarization and relaxation of vascular smooth muscle cells. The aim of this work was to investigate the contribution of potassium channel activation to vasorelaxation in internal thoracic artery taken from patients undergoing coronary artery bypass graft surgery. Relaxations to carbachol and sodium nitroprusside were studied in isolated rings of internal thoracic artery in the absence and presence of nitric oxide synthase inhibitors and potassium channel blockers. The nitric oxide synthase inhibitors Nω-nitro-⌊-arginine methyl ester and NG-monomethyl-⌊-arginine abolished relaxations to carbachol. Relaxations to both carbachol and sodium nitroprusside were attenuated in the presence of raised extracellular potassium and the potassium channel blockers charybdotoxin, iberiotoxin and tetraethylammonium. Neither apamin nor glibenclamide modified relaxation. ODQ (1H-[1,2,4]oxadiazolol-[4,3a] quinoxalin-1-one), an inhibitor of soluble guanylate cyclase, abolished relaxation to carbachol in rings from some but not all subjects. These results suggest that potassium channel opening may make a small contribution to endothelium-dependent vasorelaxation in internal thoracic artery. The potassium channels had characteristics consistent with those of large-conductance calcium-dependent potassium channels.
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Wang, Songwei, Xin Zhang, Rong Yao, Liguo Fan, and Huaiying Zhou. "High-Temperature Dielectric Relaxation Behaviors in Mn3O4 Polycrystals." Materials 12, no. 24 (December 4, 2019): 4026. http://dx.doi.org/10.3390/ma12244026.
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High temperature dielectric relaxation behaviors of single phase Mn3O4 polycrystalline ceramics prepared by spark plasma sintering technology have been studied. Two dielectric relaxations were observed in the temperature range of 200 K–330 K and in the frequency range of 20 Hz–10 MHz. The lower temperature relaxation is a type of thermally activated relaxation process, which mainly results from the hopping of oxygen vacancies based on the activation energy analysis. There is another abnormal dielectric phenomenon that is different from the conventional thermally activated behavior and is related to a positive temperature coefficient of resistance (PTCR) effect in the temperature region. In line with the impedance analyses, we distinguished the contributions of grains and grain boundaries. A comparison of the frequency-dependent spectra of the imaginary impedance with imaginary electric modulus suggests that both the long range conduction and the localized conduction are responsible for the dielectric relaxations in the Mn3O4 polycrystalline samples.
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Wang, Na, Xuebang Wu, and C. S. Liu. "Opposite Effects of SiO2 Nanoparticles on the Local α and Larger-Scale α’ Segmental Relaxation Dynamics of PMMA Nanocomposites." Polymers 11, no. 6 (June 3, 2019): 979. http://dx.doi.org/10.3390/polym11060979.
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The segmental relaxation dynamics of poly(methyl methacrylate)/silica (PMMA/SiO2) nanocomposites with different compositions ( ϕ SiO 2 ) near and above the glass transition temperature were investigated by mechanical spectroscopy. At ϕ SiO 2 ≤ 0.5%, the α peak temperature hardly changes with ϕ SiO 2 , but that of α’ relaxation composed of Rouse and sub-Rouse modes decreases by 15 °C due to the increase of free volume. At ϕ SiO 2 ≥ 0.7%, both α and α’ relaxations shift to high temperatures because of the steric hindrance introduced by nanoparticle agglomeration. On the other hand, with increasing ϕ SiO 2 , the peak height for α relaxation increases at ϕ SiO 2 ≤ 0.5% and then decreases at ϕ SiO 2 ≥ 0.7%, but that for α’ relaxation shows an opposite behavior. This is because at low ϕ SiO 2 , the short-chain segments related to α relaxation can easily bypass the particles, but the longer-chain segments related to α’ relaxation cannot. At high ϕ SiO 2 , the polymer chains were bound to the nanoparticles due to the physical adsorption effect, leading to the decrease of relaxation unit concentration involved in α relaxation. However, the dissociation of those bonds with heating and the concentration heterogeneity of polymer chains result in the increase of peak height for α’ relaxation.
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Sukcharoen, Kijvanish, Nitikorn Noraphaiphipaksa, Anat Hasap, and Chaosuan Kanchanomai. "Experimental and Numerical Evaluations of Localized Stress Relaxation for Vulcanized Rubber." Polymers 14, no. 5 (February 23, 2022): 873. http://dx.doi.org/10.3390/polym14050873.
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Vulcanized rubbers are commonly used to provide the energy absorption under compressive deformation from other engineering components. However, if a constant compressive deformation is maintained on rubber, the load response is not constant but decreases with time; i.e., the stress relaxation. A decrease in force response with time of rubber can be experimentally evaluated by the stress relaxation test. In the present work, the localized stress of vulcanized rubber during a compressive stress relaxation test (i.e., ASTM D6147) was evaluated. Hyperelastic behavior was assumed during rapid application of strain, while the viscoelastic behavior was assumed during stress relaxation. Hyperelastic and viscoelastic parameters were experimentally evaluated using a standard specimen. Finite element analysis (FEA) models were applied for the predictions of stress relaxations of rubbers with various geometries and applied strains. FEA results were in good agreement with results of the stress relaxation tests. Localized stresses in rubber during rapid application of compressive strain and stress relaxation were successfully evaluated. The findings can give the localized phenomena of vulcanized rubber during a stress relaxation test, which can be used as a guideline for the design, usage, and improvement of rubber and viscoelastic polymeric components.
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Oprea, S., V. E. Musteata, and V. O. Potolinca. "Molecular Dynamics of Linear and Crosslinked Polyester Urethanes Studied by Dielectric Spectroscopy." Journal of Elastomers & Plastics 43, no. 6 (September 26, 2011): 559–76. http://dx.doi.org/10.1177/0095244311413645.
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The molecular dynamics of crosslinked polyurethanes have been studied by dielectric spectroscopy and compared with the dynamics of linear polyurethanes. Two local relaxations, γ and β, and a primary relaxation, α, were observed for all the samples, appearing in relation with the increase in temperature. The conductivity was studied at temperatures higher than the glass transition temperature and it was found to decrease with the increasing content of crosslinker. The presence of crosslinks strongly influences their dielectric properties, especially in the elastic state. The linear polyurethane exhibits the lowest α-relaxation temperature. For the crosslinked samples, α-relaxation temperature increases with increase in the amount of crosslinkers; β- and γ-relaxations are less affected by chemical crosslinking and their activation energies are in the ranges 40–55 and 34–37 kJ/mol, respectively. For the linear polyurethane, there is an exception in the case of the γ-relaxation, which has a higher activation energy determined by its physical crosslinks. Conductivity analysis reveals a high mobility of charge carriers and low barriers for the transport of the charged particles. Also, the conductivity process is dependent on the segmental mobility of polymers.
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Villamor, Eduardo, Karin Ruijtenbeek, Victor Pulgar, Jo G. R. De Mey, and Carlos E. Blanco. "Vascular reactivity in intrapulmonary arteries of chicken embryos during transition to ex ovo life." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 282, no. 3 (March 1, 2002): R917—R927. http://dx.doi.org/10.1152/ajpregu.00369.2001.
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The present study aimed to characterize pulmonary vascular reactivity in the chicken embryo from the last stage of prenatal development and throughout the perinatal period. Isolated intrapulmonary arteries from non-internally pipped embryos at 19 days of incubation and from internally and externally pipped embryos at 21 days of incubation were studied. Arterial diameter and contractile responses to KCl, endothelin-1, and U-46619 increased with incubation but were unaffected by external pipping. In contrast, the contractions induced by norepinephrine, phenylephrine, and electric field stimulation decreased with development. No developmental changes were observed in endothelium-dependent [acetylcholine (ACh) and cyclopiazonic acid] or endothelium-independent [sodium nitroprusside (SNP)] relaxation. These relaxations were abolished by the soluble guanylate cyclase inhibitior 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one. Endothelium-dependent relaxation was unaffected by blockade of cyclooxygenase or heme oxygenase but was significantly reduced by nitric oxide (NO) synthase inhibitors. Reduction of O2 concentration from 95 to 5% produced a marked reduction in ACh and SNP-induced relaxations. Chicken embryo pulmonary arteries show a marked endothelium-dependent relaxation that is unaffected by transition to ex ovo life. Endothelium-derived NO seems to be the main mediator responsible for this relaxation.
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Zhou, Liqin, P. M. Vilarinho, P. Q. Mantas, and J. L. Baptista. "Dielectric Properties of Pb(Fe2/3W1/3)1−xMnxO3 Ceramics in the Temperature Range 200–600 K." Journal of Materials Research 15, no. 6 (June 2000): 1342–48. http://dx.doi.org/10.1557/jmr.2000.0195.
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The dielectric properties of Mn-doped Pb(Fe2/3W1/3)1−xMnxO3 (x = 0, 0.001, 0.003, and 0.005) in the temperature range 200–600 K were investigated. Two sets of dielectric peaks, located at 200–350 K and 350–600 K, were observed. The intensity of the dielectric permittivity and loss factor peaks for both relaxations decreased with the increase in the Mn content and no peak occurred when x = 0.005. Nonlinear current–voltage (I–V) behavior was observed in the samples containing less than 0.005Mn. The activation energy values for the relaxations at 200–350 K and at 350–600 K were around 0.42 and 0.56 eV, respectively. The direct current conduction activation energies were around 0.41 eV. Nitrogen annealing eliminated the relaxation peaks at 200–350 K while oxygen annealing enhanced them. Both annealings eliminated the dielectric peaks at 350–600 K. The nonlinear I–V characteristic tended to vanish either after the oxygen or the nitrogen annealing treatments. Relaxation mechanisms are proposed and discussed. It is suggested that the relaxation at 200–350 K is related to electron hole while the relaxation at 350–600 K is attributed to microstructure-dependent space-charge polarization.