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V Correcher J Garcia-Guinea FJ Valle-Fuentes 《Journal of Thermal Analysis and Calorimetry》2006,83(2):439-444
In
this paper, novel results on the blue thermally stimulated luminescence (TSL)
emission of ulexite (NaCaB5O6(OH)6·5H2O)
have been studied. The four maxima appearing at 60, 110, 200 and 240°C
on the TSL glow curves of this borate could be respectively associated to:
(i) the first dehydration (NaCaB5O6(OH)6·5H2O→NaCaB5O6(OH)6·3H2O),
(ii) the creation-annihilation of the three-hydrated
phase, (iii) the Na-coordinated chains
dehydroxylation and the starting point of the alkali self-diffusion through
the lattice and (iv) the amorphisation
of the lattice. These results are fairly well correlated with the differential
thermal analyses (DTA), in situ thermal observations under environmental scanning
electron microscope (TESEM) and thermal X-ray diffraction (TXRD) techniques. 相似文献
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Krishna Bisetty Francesc J. Corcho Josep Canto Hendrik G. Kruger Juan J. Perez 《Journal of Molecular Structure》2006,770(1-3):221-228
In this paper, we report on the conformational profile of the pentacyclo-undecane (PCU) cage tripeptide carried out by molecular dynamics (MD) simulation using water as an explicit solvent. The MD solution phase studies carried on the model peptide analogues (A)=Ac–Ala–Ala–Ala–NHMe; (B)=Ac–Cage–Cage–Cage–NHMe; (C)=Ac–Ala–Cage–Ala–NHMe and (D)=Ac–Ala–Pro–Ala–NHMe, are used as a complimentary technique to the corresponding gas phase simulated annealing (SA) study previously carried out in our laboratory. No significant structural changes were observed over the MD trajectories. However, the results reported here provide further evidence that the (PCU) cage amino acid exhibits C7eq, C7aq, R and L conformations, and the theoretical results suggest that the PCU cage amino acid is a strong β-turn inducer. These results support the prediction that when the PCU cage residues are in the (i) and (i+2) positions, the β-turn can be extended in either direction to form anti-parallel β-pleated sheets, thereby forming the basis of the mechanism for the folding back of the chain in a cross-β-turn structure. 相似文献
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The present study describes an extensive conformational search of substance P using two different computational methods. On the one hand, the peptide was studied using the iterative simulated annealing, and on the other, molecular dynamics simulations at 300 and 400 K. With the former method, the peptide was studied in vacuo with a dielectric constant of 80, whereas using the latter study the peptide was studied in a box of TIP3P water molecules. Analysis of the results obtained using both methodologies was carried out using an in-house methodology using a cluster analysis method based on information theory. Comparison of the two sampling methodologies and the different environment used in the calculations is also analyzed. Finally, the conformational motifs that are characteristic of substance P in a hydrophilic environment are presented and compared with the experimental results available in the literature. 相似文献
7.
J. A. Corcho Alvarado Y. Nedjadi F. Bochud 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):375-379
Liquid scintillation counting (LSC) is one of the most widely used methods for determining the activity of 241Pu. One of the main challenges of this counting method is the efficiency calibration of the system for the low beta energies
of 241Pu (E
max = 20.8 keV). In this paper we compare the two most frequently used methods, the CIEMAT/NIST efficiency tracing (CNET) method
and the experimental quench correction curve method. Both methods proved to be reliable, and agree within their uncertainties,
for the expected quenching conditions of the sources. 相似文献
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We obtain local well-posedness for the one-dimensional Schrödinger–Debye interactions in nonlinear optics in the spaces \(L^2\times L^p,\; 1\le p < \infty \). When \(p=1\) we show that the local solutions extend globally. In the focusing regime, we consider a family of solutions \(\{(u_{\tau }, v_{\tau })\}_{\tau >0}\) in \( H^1\times H^1\) associated to an initial data family \(\{(u_{\tau _0},v_{\tau _0})\}_{\tau >0}\) uniformly bounded in \(H^1\times L^2\), where \(\tau \) is a small response time parameter. We prove that \(\left( u_{\tau }, v_{\tau }\right) \) converges to \(\left( u, -|u|^2\right) \) in the space \(L^{\infty }_{[0, T]}L^2_x\times L^1_{[0, T]}L^2_x\) whenever \(u_{\tau _0}\) converges to \(u_0\) in \(H^1\) as long as \(\tau \) tends to 0, where u is the solution of the one-dimensional cubic nonlinear Schrödinger equation with the initial data \(u_0\). The convergence of \(v_{\tau }\) for \(-|u|^2\) in the space \(L^{\infty }_{[0, T]}L^2_x\) is shown under compatibility conditions of the initial data. For non-compatible data, we prove convergence except for a corrector term which looks like an initial layer phenomenon. 相似文献
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