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71.
Victor A. Rozentsvet Valery G. Kozlov Nelly A. Korovina Ivan A. Novakov Sergei V. Kostjuk 《Macromolecular chemistry and physics.》2014,215(12):1239-1249
A novel method for the investigation of the chain‐end structure of poly(1,3‐pentadiene)s synthesized using the CF3COOD/TiCl4 initiating system is developed. It is shown for the first time that the content of trans‐1,2‐structures in the first monomer unit is considerably higher than the content of trans‐1,4‐structures, whereas the content of trans‐1,4‐units is substantially higher than trans‐1,2‐units for the polymer chain as a whole. Another important observation is that chain transfer to monomer is significant even at the earlier stages of the 1,3‐pentadiene polymerization (after 1 s of reaction). The very low functionality at the ω‐end (Fn (Cl) < 0.15) confirms the intensive chain transfer to monomer. This method is also applied for the estimation of the concentration of active species and the rate constant for propagation (k p) for the cationic polymerization of 1,3‐pentadiene using the CF3COOD/TiCl4 initiating system: rate constants for propagation, k p, of 1.5 × 103 and 3.3 × 103 L mol?1 min?1 are determined for 1,3‐pentadiene polymerization at 20 and –78 °C, respectively.
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Kozlov AS Andor-Ardó D Hudspeth AJ 《Proceedings of the National Academy of Sciences of the United States of America》2012,109(8):2896-2901
The ear detects sounds so faint that they produce only atomic-scale displacements in the mechanoelectrical transducer, yet thermal noise causes fluctuations larger by an order of magnitude. Explaining how hearing can operate when the magnitude of the noise greatly exceeds that of the signal requires an understanding both of the transducer's micromechanics and of the associated noise. Using microrheology, we characterize the statistics of this noise; exploiting the fluctuation-dissipation theorem, we determine the associated micromechanics. The statistics reveal unusual Brownian motion in which the mean square displacement increases as a fractional power of time, indicating that the mechanisms governing energy dissipation are related to those of energy storage. This anomalous scaling contradicts the canonical model of mechanoelectrical transduction, but the results can be explained if the micromechanics incorporates viscoelasticity, a salient characteristic of biopolymers. We amend the canonical model and demonstrate several consequences of viscoelasticity for sensory coding. 相似文献
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Armen?Yuri?Gasparyan Giuseppe?CoccoEmail author Stefano?Pandolfi 《Rheumatology international》2012,32(2):461-464
Cardiovascular disease is the leading cause of premature mortality in patients with rheumatoid arthritis (RA). Pathophysiology
of rheumatoid cardiovascular phenomenon is not fully understood, but systemic inflammation is thought to play a crucial role
in the endothelial damage and accelerated course of atherosclerotic disease. Rheumatoid inflammation can also cause coronary
pathology and heart failure. We present a case of transient cardiomyopathy in RA in the absence of occlusive coronary pathology,
which mimics acute coronary syndrome. 相似文献
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