27 research outputs found

    Thermal (in)stability of type I collagen fibrils

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    We measured Young's modulus at temperatures ranging from 20 to 100 ^{\circ}Cforacollagenfibriltakenfromratstendon.Thehydrationchangeunderheatingandthedampingdecrementweremeasuredaswell.AtphysiologicaltemperaturesC for a collagen fibril taken from rat's tendon. The hydration change under heating and the damping decrement were measured as well. At physiological temperatures 25-45^{\circ}CYoungsmodulusdecreases,whichcanbeinterpretedasinstabilityofcollagen.FortemperaturesbetweenC Young's modulus decreases, which can be interpreted as instability of collagen. For temperatures between 45-80^{\circ}CYoungsmodulusfirststabilizesandthenincreaseswithdecreasingthetemperature.ThehydratedwatercontentandthedampingdecrementhavestrongmaximaintheintervalC Young's modulus first stabilizes and then increases with decreasing the temperature. The hydrated water content and the damping decrement have strong maxima in the interval 70-80^{\circ}Cindicatingoncomplexintermolecularstructuralchangesinthefibril.AlltheseeffectsdisappearafterheatdenaturatingthesampleatC indicating on complex inter-molecular structural changes in the fibril. All these effects disappear after heat-denaturating the sample at 120^\circ$C. Our main result is a five-stage mechanism by which the instability of a single collagen at physiological temperatures is compensated by the interaction between collagen molecules within the fibril.Comment: 4 pages, 4 figure

    Observation of Resonant Diffusive Radiation in Random Multilayered Systems

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    Diffusive Radiation is a new type of radiation predicted to occur in randomly inhomogeneous media due to the multiple scattering of pseudophotons. This theoretical effect is now observed experimentally. The radiation is generated by the passage of electrons of energy 200KeV-2.2MeV through a random stack of films in the visible light region. The radiation intensity increases resonantly provided the Cherenkov condition is satisfied for the average dielectric constant of the medium. The observed angular dependence and electron resonance energy are in agreement with the theoretical predictions. These observations open a road to application of diffusive radiation in particle detection, astrophysics, soft X-ray generation and etc.. `Comment: 4pages, 4figure

    Multiple scattering of classical waves: microscopy, mesoscopy, and diffusion

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    Does creatine kinase-MB (CK-MB) isoenzyme elevation following percutaneous coronary intervention with drug-eluting stents impact late clinical outcome?

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    BACKGROUND: The incidence of postprocedural creatine kinase (CK)-MB elevation to >3x the upper limit of normal after percutaneous coronary intervention (PCI) has been reported at rates of up to 18% in the bare metal stent era and is correlated with higher adverse cardiovascular outcomes. This study examined the incidence and prognostic significance of CK-MB elevations after drug-eluting stent (DES) implantation. METHODS: The records of 2,537 patients who underwent DES implantation and completed > or =6 months' follow-up were evaluated. Patients with acute myocardial infarction and those who presented in cardiogenic shock and had elevated cardiac enzymes at baseline were excluded from the analysis. Of these, 179 patients (7.1%) had > or =3x postprocedural CK-MB and 2,358 patients had or =3x elevation had a higher number of diseased vessels (2.15 +/- 0.86 vs. 1.81 +/- 0.87; P or =3x elevation following PCI with DES continues to be a marker for the complexity of coronary disease and lack of clinical success; and correlates with higher rates of subacute thrombosis as well as late adverse events at 6-months and 1-year postprocedure.6 page(s
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