1,413 research outputs found
Coexistence of two elastic surface modes enhanced by viscous losses
No full textSpatial profiles of electrically excited surface waves on agarose gels were measured as a function of frequency and concentration of the agarose. Two surface waves were observed in the low-frequency region. One is a Rayleigh wave, which shows the elastic behavior up to a certain frequency and then gradually disappears with the increase in frequency. The other wave is also elastic; however, it has higher value of phase velocity than the Rayleigh wave and approaches the dispersion of the capillary wave in the high-frequency region. The surface response function analysis shows that the semi-infinite viscoelastic media support the propagation of the two elastic surface waves, but not the propagation of the elastic and pure capillary waves as was claimed previously. Moreover, the theoretical analysis reveals that the viscous losses effectively enhance the coexistence of the two elastic surface modes
Thickness dependence of surface modes on a gel
No full textA surface wave mode on a gel has been studied as a function of thickness by using electrically excited surface wave spectroscopy (EESWS), which measures the response of excited surface waves by applying an electric field at the surface. In the frequency region where the elastic and surface tension forces dominate, multiple harmonics of a surface mode are predicted theoretically for a finite-thickness case due to a coupling with the normal direction wave to the surface. This paper shows the rst experimental measurement of the multiple harmonics of a surface mode. We have compared the experimental data with the theoretical calculation
Shimmer
No full text1 volume, slipcase, 48 pages . Author, editor, translator and imprint from colophon. Short story by Jule Claudia Mahn accompanied by the author\u27s photographs. Set in Pollen Regular, Pigment print on Awagami Inbe, Thin white Washi paper ... in an edition of 13 copies in German and XVI copies in English ... 14th book in the series \u27Verwandte Objekte,\u27 Leipzig 2018 --Colophon. Exposed thread binding in Hollytex non-woven fabric. Housed in a paper-covered case. Enclosed in same fabric slipcase. All housed in two-piece grey board binder, held closed with two orange rubber bands (31 x 18 cm).https://digitalcommons.risd.edu/specialcollections_artistsbooks/1223/thumbnail.jp
Tau-isoform dependent enhancement of taxol mobility through microtubules
No full textTau, a family of microtubule-associated proteins (MAPS), stabilizes microtubules (MTs) and regulates their dynamics. Tau isoforms regulate MT dynamic instability differently: 3-repeat tau is less effective than 4-repeat tau at Suppressing the disassembly of MTs. Here, we report another tau-isoforn-dependent phenomenon, revealed by fluorescence recovery after photobleaching measurements on a BODIPY-conjugated taxol bound to MTs. Saturating levels of recombinant full-length 3-repeat and 4-repeat tau both cause taxol mobility to be remarkably sensitive to taxol concentration. However, 3-repeat tau induces 2.5-fold faster recovery (similar to 450 s) at low taxol concentrations (similar to 100 nM) than 4-repeat tau (similar to 1000 s), indicating that 3-repeat tau decreases the probability of taxol rebinding to its site in the MT lumen. Finding no tau-induced change in the MT-binding affinity Of taxol, We Conclude that 3-repeat tau either competes for the taxol binding site with an affinity of similar to 1 mu M or alters the MT structure so as to facilitate the passage of taxol through Pores in the MT wall. (c) 2008 Elsevier Inc. All rights reserved
Surface modes on polymer solutions by surface light-scattering techniques
No full textBy using the surface heterodyne spectroscopy, we study the surface modes on polymer solutions of polyisobutylene/decane at different concentrations. For each concentration, we measure the power spectra at various wave numbers (110.0-600.0 cm-1). We find that the relation between the frequency shift omega-k of the power spectrum and wave number k changes continuously from omega-k is-proportional-to k when concentration of the polymer solution is changed from 0.5 g/dl to 8.0 g/dl. For the low-concentration polymer solutions, the surface modes are capillary modes (omega-k is-proportional-to k3/2). For the high-concentration polymer solutions, the surface modes are elastic modes (omega-k is-proportional-to k). This result is compared with the theory [J. L. Harden, H. Pleiner, and P. A. Pincus, J. Chem. Phys. 94, 5208 (1991)]
H2S as potential modulator of Ca2+-induced T-cell activation
No full textH2S ist als endogen gebildeter Transmitter an zahlreichen physiologischen Prozessen wie Blutdruckregulation, Entzündung und Neuromodulation beteiligt. Da viele der bekannten Effekte von H2S über Beeinflussung von Ca2+-Signalkaskaden zustande kommen und Änderungen der intrazellulären Ca2+-Konzentration ([Ca2+]i) bei der Aktivierung von T-Zellen eine entscheidende Rolle spielen, wurde im Rahmen dieser Diplomarbeit der Effekt von NaHS als H2S-Donor auf T-Zellen genauer untersucht. Als weitere Testsubstanz diente der K+-Kanal-Blocker Glibenclamid, der im Blutgefäß die Wirkung von H2S antagonisiert. Als Versuchsmodell wurde die etablierte T-Zellline JURKAT, sowie als Vergleich kultivierte Endothelzellen der Schweineaorta (ECAP) verwendet. Die Effekte auf Ca2+-Einstrom und Ca2+-Freisetzung sowie die Verlaufsdynamik dieser beiden Parameter wurden mit Hilfe des Ca2+-sensitiven Fluoreszenzfarbstoffes Fura-2 untersucht. Die Ergebnisse zeigten, dass NaHS sowohl in JURKAT- als auch ECAP-Zellen einen Anstieg der [Ca2+]i induziert, wobei sowohl eine intrazelluläre Freisetzung als auch ein gesteigerter Einstrom beobachtet wurde. Ähnlich wie in Gefäßmuskelzellen antagonisierte Glibenclamid die Effekte von NaHS, blockierte aber auch die Wirkung anderer Ca2+-mobilisierender Substanzen wie ATP, Thrombin und Thapsigarin in konzentrationsabhängiger Weise. Da der Sulfonylharnstoff selbst eine (nahezu) vollständige Depletierung intrazellulärer Ca2+-Speicher verursachte, scheint der Hemmeffekt vorrangig auf die massive Reduktion des Ca2+-Einstromes zurückzuführen zu sein. Eine Beteiligung von plasmamembranständigen K+-Kanälen an den beobachteten Effekten konnte ausgeschlossen werden. Zusammenfassend lässt sich sagen, dass NaHS in JRUKAT-Zellen zu einer Freisetzung von Ca2+ aus intrazellulären Speichern führt und so einen speicherregulierten Ca2+-Einstrom bewirkt der durch Glibenclamid über einen noch ungeklärten Mechanismus gehemmt wird.H2S is an endogenous transmitter that is involved in a variety of physiological processes, such as blood pressure regulation, inflammation and neuromodulation. Since H2S is known to modulate Ca2+ signaling, and changes in intracellular Ca2+ ([Ca2+]i) play a crucial role in the activation of T cells, this diploma thesis was aimed at investigating the role of H2S in T cell activation. Thereby, special emphasis was given to the interplay between H2S and glibenclamide, a selective K+ channel blocker that is known to antagonize the effects of H2S in the vasculature. In the course of the thesis, experiments were performed with the T cell line JURKAT and, for comparison, cultured porcine aortic endothelial cells (ECAP). NaHS was used as H2S donor, and changes in [Ca2+]i were monitored by fluorescence measurements using the Ca2+ indicator Fura-2. The results revealed that H2S promotes both release of the Ca2+ from intracellular stores and influx of Ca2+ from the extracellular space, resulting in a longlasting increase in [Ca2+]i in JURKAT as well as ECAP cells. In accordance with its effects in vascular smooth muscle cells, glibenclamide antagonized the Ca2+ rise induced by NaHS but interestingly also blocked the effect of other Ca2+ mobilizing agonists such as ATP, thrombin or thapsigargin in a concentration dependent manner. Since glibenclamide itself induced a depletion of intracellular Ca2+ stores that was not accompanied by Ca2+ influx, the sulfonylurea apparently interferes with store-operated Ca2+ entry. A participation of K+ channels could be excluded. Summarized the data show that in JURKAT cells NaHS promotes Ca2+ release and store-operated Ca2+ entry. The latter is inhibited by glibenclamide through an as yet unknown mechanism.eingereicht von Mahn StephanZusammenfassungen in Deutsch und EnglischAbweichender Titel laut Übersetzung des Verfassers/der VerfasserinDiplomarbeit Karl-Franzens-Universität Graz 2018 778
H2S as potential modulator of Ca2+-induced T-cell activation
No full textH2S ist als endogen gebildeter Transmitter an zahlreichen physiologischen Prozessen wie Blutdruckregulation, Entzündung und Neuromodulation beteiligt. Da viele der bekannten Effekte von H2S über Beeinflussung von Ca2+-Signalkaskaden zustande kommen und Änderungen der intrazellulären Ca2+-Konzentration ([Ca2+]i) bei der Aktivierung von T-Zellen eine entscheidende Rolle spielen, wurde im Rahmen dieser Diplomarbeit der Effekt von NaHS als H2S-Donor auf T-Zellen genauer untersucht. Als weitere Testsubstanz diente der K+-Kanal-Blocker Glibenclamid, der im Blutgefäß die Wirkung von H2S antagonisiert. Als Versuchsmodell wurde die etablierte T-Zellline JURKAT, sowie als Vergleich kultivierte Endothelzellen der Schweineaorta (ECAP) verwendet. Die Effekte auf Ca2+-Einstrom und Ca2+-Freisetzung sowie die Verlaufsdynamik dieser beiden Parameter wurden mit Hilfe des Ca2+-sensitiven Fluoreszenzfarbstoffes Fura-2 untersucht. Die Ergebnisse zeigten, dass NaHS sowohl in JURKAT- als auch ECAP-Zellen einen Anstieg der [Ca2+]i induziert, wobei sowohl eine intrazelluläre Freisetzung als auch ein gesteigerter Einstrom beobachtet wurde. Ähnlich wie in Gefäßmuskelzellen antagonisierte Glibenclamid die Effekte von NaHS, blockierte aber auch die Wirkung anderer Ca2+-mobilisierender Substanzen wie ATP, Thrombin und Thapsigarin in konzentrationsabhängiger Weise. Da der Sulfonylharnstoff selbst eine (nahezu) vollständige Depletierung intrazellulärer Ca2+-Speicher verursachte, scheint der Hemmeffekt vorrangig auf die massive Reduktion des Ca2+-Einstromes zurückzuführen zu sein. Eine Beteiligung von plasmamembranständigen K+-Kanälen an den beobachteten Effekten konnte ausgeschlossen werden. Zusammenfassend lässt sich sagen, dass NaHS in JRUKAT-Zellen zu einer Freisetzung von Ca2+ aus intrazellulären Speichern führt und so einen speicherregulierten Ca2+-Einstrom bewirkt der durch Glibenclamid über einen noch ungeklärten Mechanismus gehemmt wird.H2S is an endogenous transmitter that is involved in a variety of physiological processes, such as blood pressure regulation, inflammation and neuromodulation. Since H2S is known to modulate Ca2+ signaling, and changes in intracellular Ca2+ ([Ca2+]i) play a crucial role in the activation of T cells, this diploma thesis was aimed at investigating the role of H2S in T cell activation. Thereby, special emphasis was given to the interplay between H2S and glibenclamide, a selective K+ channel blocker that is known to antagonize the effects of H2S in the vasculature. In the course of the thesis, experiments were performed with the T cell line JURKAT and, for comparison, cultured porcine aortic endothelial cells (ECAP). NaHS was used as H2S donor, and changes in [Ca2+]i were monitored by fluorescence measurements using the Ca2+ indicator Fura-2. The results revealed that H2S promotes both release of the Ca2+ from intracellular stores and influx of Ca2+ from the extracellular space, resulting in a longlasting increase in [Ca2+]i in JURKAT as well as ECAP cells. In accordance with its effects in vascular smooth muscle cells, glibenclamide antagonized the Ca2+ rise induced by NaHS but interestingly also blocked the effect of other Ca2+ mobilizing agonists such as ATP, thrombin or thapsigargin in a concentration dependent manner. Since glibenclamide itself induced a depletion of intracellular Ca2+ stores that was not accompanied by Ca2+ influx, the sulfonylurea apparently interferes with store-operated Ca2+ entry. A participation of K+ channels could be excluded. Summarized the data show that in JURKAT cells NaHS promotes Ca2+ release and store-operated Ca2+ entry. The latter is inhibited by glibenclamide through an as yet unknown mechanism.eingereicht von Mahn StephanZusammenfassungen in Deutsch und EnglischAbweichender Titel laut Übersetzung des Verfassers/der VerfasserinDiplomarbeit Karl-Franzens-Universität Graz 2018 778
Feasibility Study for Biological Membranes by Using a New Neutron Reflectometer at the HANARO
No full textA new neutron reflectometer was installed at the HANARO research reactor in 2006 and polymer thin films and a series of biological membrane studies were measured with the neutron reflectometer to check its viability for studying different thin films. The experimental results showed that the essential structural information of these biological systems could be acquired from the measurements and the results were in good agreement with those previously reported. Hence, HANARO neutron reflectometer was confirmed as a useful tool for performing measurements at air-solid and solid-liquid interfaces, especially for biological applications
Oxygen adsorbates on the Si(111)4x1-In metallic atomic wire: Scanning tunneling microscopy and density-functional theory calculations
No full textThe Si(111)4x1-In surface is composed of metallic atomic wires, which undergo a transition into a charge density wave phase at a transition temperature (T-c) of 125 K. This T-c was reported recently to substantially increase upon the oxygen adsorption, for which the underlying mechanism is not understood. We investigate the structures of oxygen adsorbates on the Si(111)4x1-In surface by scanning tunneling microscopy (STM) and density-functional theory calculations. We identify three distinct atomic-scale structures induced by the oxygen adsorption with high-resolution STM topography. The calculations find two energetically favorable adsorption sites on and between In zigzag chains, respectively. In conjunction with an additional adsorption configuration, where O is buried underneath the In chain, three stable structures are thus identified that reproduce very well the characteristic bias-dependent STM images. Experimentally, a switching between two specific adsorption structures is observed and is consistent with the structure models proposed. The structural distortions and the charge transfer of In atomic wires around the adsorbates are also characterized. This work provides a solid basis for the microscopic understanding of the intriguing oxygen impurity effect on the phase transition.open1166sciescopu
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