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Complete Relaxation (complete + relaxation)
Selected AbstractsIs aperistalsis with complete lower esophageal sphincter relaxation an early stage of classic achalasia?JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 4 2007Jeong Hwan Kim Abstract Background:, Aperistalsis with complete lower esophageal sphinter (LES) relaxation, characterized by the complete relaxation of the LES and aperistalsis of the esophageal body on manometry, has been considered by some authors to be an early manifestation of classic achalasia, which is defined as incomplete relaxation of the LES and aperistalsis of the esophageal body. The aim of the present study was to compare the clinical features of patients with aperistalsis with complete LES relaxation, with those of patients with classic achalasia. Methods:, Eighteen patients with aperistalsis with complete LES relaxation and 53 patients with classic achalasia were analyzed with regard to clinical history, the maximal diameter of the esophageal body on barium esophagogram, LES resting pressure and the duration of LES relaxation on manometric recordings, and the selected treatment and its efficacy. Results:, The aperistalsis with complete LES relaxation group had distinctly different features compared to those of the classic achalasia group including older age, more frequent association with non-cardiac chest pain, less frequent association with dysphagia and weight loss, lower LES resting pressures, and longer duration of LES relaxation. However, the two groups were similar in terms of maximal diameter of the esophageal body, and efficacy associated with pneumatic dilation. Conclusions:, Aperistalsis with complete LES relaxation on manometry is not necessarily an early manifestation of classic achalasia. However, this condition does not preclude a diagnosis of achalasia or a good response to achalasia therapy. [source] Vibrational spectroscopy investigation using density functional theory on 7-chloro-3-methyl-2H-1,2,4- benzothiadiazine 1,1-dioxideJOURNAL OF RAMAN SPECTROSCOPY, Issue 6 2009S. Seshadri Abstract The solid phase Fourier transform infrared (FTIR) and Fourier transform (FT) Raman spectral analysis of 7-chloro-3-methyl-2H-1,2,4-benzothiadiazine 1,1-dioxide (diazoxide), an antihypertensive agent was carried out along with density functional computations. The optimized geometry, wavenumber and intensity of the vibrational bands of diazoxide were obtained by DFT-B3LYP level of theory with complete relaxation in the potential energy surface using 6-31G(d,p) basis set. A complete vibrational assignment aided by the theoretical harmonic frequency analysis has been proposed. The harmonic vibrational wavenumbers calculated have been compared with experimental FTIR and FT Raman spectra. The observed and the calculated wavenumbers are found to be in good agreement. The experimental spectra coincide satisfactorily with those of calculated spectra. Copyright © 2009 John Wiley & Sons, Ltd. [source] Verhalten laserschockverfestigter und festgewalzter Randschichten der Ti-Legierung Ti-6Al-4V bei schwingender Beanspruchung unter erhöhten TemperaturenMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 6 2003I. Altenberger Laser Shock Peening; Deep Rolling; Residual Stresses; Ti-6-4 Abstract Es ist seit langem bekannt, dass mechanische Oberflächenbehandlungen wie etwa Festwalzen, Kugelstrahlen oder Laserschockoberflächenbehandlungen, um nur einige zu nennen, das Ermüdungsverhalten hochbeanspruchter metallischer Bauteile entscheidend verbessern können. Insbesondere Festwalzen und Laserschockoberflächenbehandlungen haben sich als besonders wirksam herausgestellt, da sie tiefe Druckeigenspannungs- und Verfestigungsprofile sowie eine vergleichsweise glatte Oberflächentopographie erzeugen. Tatsächlich wird z.,B. das Festwalzen bereits serienmässig zur Erhöhung der Schwingfestigkeit von Stählen, wie etwa beim Festwalzen von Kurbelwellen, eingesetzt. Obwohl die meisten Arbeiten zum Festwalzen sich mit Stählen beschäftigen, wurde dieses Verfahren in jüngerer Zeit auch auf eine Reihe von Titanwerkstoffen erfolgreich angewendet. Die vorliegenden Untersuchungen beschäftigen sich mit dem Einfluss von Festwalzbehandlungen auf das Niedrig- und Hochlastwechselermüdungsverhalten der wichtigsten kommerziellen Titanlegierung Ti-6Al-4V, wobei besonderes Augenmerk auf die thermische und mechanische Stabilität randnaher Eigenspannungszustände und Mikrostrukturen gerichtet wurde. Zusätzlich werden erste Ergebnisse zum Eigenspannungszustand und zur Schwingfestigkeit lasergeschockter Ti-6Al-4V-Proben präsentiert und mit Resultaten festgewalzter Zustände verglichen. Ausserdem wird untersucht, ob die Oberflächenbehandlungen auch bei erhöhten Temperaturen (bis 450,°C) ihre Wirksamkeit zur Verbesserung der Schwingfestigkeit behalten. Basierend auf Wechselverformungs- und Lebensdaueruntersuchungen, in Kombination mit Röntgendiffraktometrie und In-situ -Transmissionselektronenmikroskopie, lässt sich feststellen, dass Laserschockoberflächenbehandlungen und insbesondere Festwalzen die Rissbildung und Ausbreitung in hochtemperaturschwingbeanspruchtem Ti-6Al-4V trotz eines fast völligen Druckeigenspannungsabbaus wirkungsvoll hemmt. Daraus lässt sich ableiten, dass zusätzlich zu Eigenspannungen vor allem randnahe Mikrostrukturen, welche im Falle von mechanisch randschichtverfestigtem Ti-6Al-4V durch sehr hohe Versetzungsdichten und Nanokristallite gekennzeichnet ist, einen wesentlichen Einfluss bei der Lebensdauererhöhung durch Randschichtverfestigung haben. Residual stress stability and near-surface microstructures in high temperature fatigued mechanically surface treated Ti-6Al-4V It is well known that mechanical surface treatments, such as deep rolling, shot peening and laser shock peening, can significantly improve the fatigue behavior of highly-stressed metallic components. Deep rolling is particularly attractive since it is possible to generate, near the surface, deep compressive residual stresses and work hardened layers while retaining a relatively smooth surface finish. In the present investigation, the effect of deep rolling on the low-cycle and high-cycle fatigue behavior of a Ti-6Al-4V alloy is examined, with particular emphasis on the thermal and mechanical stability of the residual stress states and the near-surface microstructures. Preliminary results on laser shock peened Ti-6Al-4V are also presented for comparison. Particular emphasis is devoted to the question of whether such surface treatments are effective for improving the fatigue properties at elevated temperatures up to ,450,°C, i.e., at an homologous temperature of ,0.4 T/Tm (where Tm is the melting temperature). Based on cyclic deformation and stress/life (S/N) fatigue behavior, together with the X-ray diffraction and in situ transmission electron microscopy observations of the microstructure, it was found that deep rolling can be quite effective in retarding the initiation and initial propagation of fatigue cracks in Ti-6Al-4V at such higher temperatures, despite the almost complete relaxation of the near-surface residual stresses. In the absence of such stresses, it is shown that the near-surface microstructures, which in Ti-6Al-4V consist of a layer of work hardened nanoscale grains, play a critical role in the enhancement of fatigue life by mechanical surface treatment. [source] Modulation of oesophago-UOS contractile reflex: effect of proximal and distal esophageal distention and swallowingNEUROGASTROENTEROLOGY & MOTILITY, Issue 3 2003M. Aslam Abstract Upper oesophageal sphincter (UOS) tone is influenced by intraoesophageal pressure events. Our aim was to test the hypothesis that UOS tone is responsive to simultaneous inhibitory and stimulatory signals originating from the oesophagus and compare effect of proximal and distal oesophageal air distention on oesophageal balloon-stimulated UOS contraction. We studied 16 healthy volunteers, ages 19,80 years in two stages. We induced UOS contraction by distending various size balloons intraoesophageally and studied response of contracted UOS to oesophageal air distentions and swallowing. Intraoesophageal injections of 60-ml room air resulted in UOS pressure augmentation (31%), relaxation (64%) and no effect in the remaining 5% of instances. The majority of air injections into the oesophageal segment proximal to the distended balloon were followed by relaxation of the contracted UOS, whereas, the majority of oesophageal air distentions distal to the balloon resulted in augmentation of UOS contraction (P < 0.01). Swallowing resulted in complete relaxation of the UOS. In conclusion, UOS contractile response to oesophageal balloon distention is overridden by further augmentation or relaxation as a result of oesophageal air distention and swallowing. Contractile and inhibitory responses of the contracted UOS to generalized oesophageal distention is region-specific. [source] | ||||||||||