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51.
Alves GA Amato S Anjos JC Appel JA Astorga J Bernard T Bracker SB Cremaldi LM Darling CL Dixon RL Errede D Gay C Green DR Jedicke R Karchin PE Kwan S Lueking LJ de Mello Neto JR Metheny J Milburn RH de Miranda JM da Motta Filho H Napier A Passmore D Rafatian A dos Reis AC Ross WR Santoro AF Sheaff M Souza MH Spalding WJ Stoughton C Streetman ME Summers DJ Takach SF Wallace A Wu Z 《Physical review letters》1994,72(6):812-815
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Enrique Saiz 《Journal of Polymer Science.Polymer Physics》1987,25(8):1565-1579
A theoretical analysis of the conformational energies of poly(dichlorophosphazene) (PDCP) is presented. The results indicate that the bond pair P? N? P possesses a considerable conformational freedom, whereas the bond pair N? P? N is relatively rigid. This difference explains the low glass transition temperatures Tg and large end-to-end distances measured for polyphosphazenes. A statistical model containing four rotational isomers (ie., trans, gauche, cis, and negative gauche) is developed and used to calculate unperturbed dimensions and dipole moments of PDCP. The results, obtained at 25°C with n = 400 skeletal bonds (200 repeating units), were Cn = 〈r2〉0/nl2 = 13.5; CT = 103d(ln〈r2〉0)/dT = ?3.0 K?1; Dn = 〈μ2〉/nμ = 0.35; DT = 103d(ln〈μ2〉)/dT = ?3.4 K?1. All the calculated magnitudes are extremely sensitive to the energy Eσ that controls the statistical weights of the conformations tg, tc, tg?, gt, ct, and g?t relative to tt for the bond pair P? N? P. A qualitative explanation for this sensitivity is discussed. 相似文献
56.
Garrido L López-Gonzalez M Saiz E Riande E 《The journal of physical chemistry. B》2008,112(14):4253-4260
Gas transport of carbon dioxide in poly[bisphenol A carbonate-co-4,4'-(3,3,5-trimethylcyclohexylidene)diphenol carbonate] films over a wide range of pressure is described. The interpretation of the experimental results in terms of the dual mode model allowed the evaluation of the parameters of the model that govern the gas permeation process. The value of the diffusion coefficient obtained for carbon dioxide at zero concentration was 2.4 x 10(-8) cm(2) s(-1), at 303 K. This parameter was also measured by using pulsed field gradient NMR finding that its value reaches a nearly constant value of (2.7 +/- 0.9) x 10(-8) cm(2) s(-1), at 298 K, for diffusion times greater than 20 ms. Both the diffusion and solubility coefficients were also computed by using simulation methods based on the transition states theory and the Widom method, respectively. The value obtained for the diffusion coefficient was 1.8 x 10(-8) cm(2) s(-1), at 303 K, which compares very favorably with the experimental measurements. The drop of the simulated solubility coefficient with increasing pressure is sharper than that of the experimental one, at low pressures, and similar, at high pressures. 相似文献
57.
Christian Haarkötter Diana C. Vinueza-Espinosa Xiomara Gálvez María Saiz María Isabel Medina-Lozano José Antonio Lorente Juan Carlos Álvarez 《Electrophoresis》2023,44(19-20):1559-1568
Skeletal remains are the only biological material that remains after long periods; however, environmental conditions such as temperature, humidity, and pH affect DNA preservation, turning skeletal remains into a challenging sample for DNA laboratories. Sample selection is a key factor, and femur and tooth have been traditionally recommended as the best substrate of genetic material. Recently, petrous bone (cochlear area) has been suggested as a better option due to its DNA yield. This research aims to evaluate the efficiency of petrous bone compared to other cranium samples (tooth) and postcranial long bones (femur and tibia). A total amount of 88 samples were selected from 38 different individuals. The samples were extracted by using an organic extraction protocol, DNA quantification by Quantifiler Trio kit and amplified with GlobalFiler kit. Results show that petrous bone outperforms other bone remains in quantification data, yielding 15–30 times more DNA than the others. DNA profile data presented likeness between petrous bone and tooth regarding detected alleles; however, the amount of DNA extracted in petrous bones allowed us to obtain more informative DNA profiles with superior quality. In conclusion, petrous bone or teeth sampling is recommended if DNA typing is going to be performed with environmentally degraded skeletal remains. 相似文献
58.
E M Ortiz P J Valle J M Saiz F González F Moreno 《Waves in Random and Complex Media》2013,23(3):319-329
Abstract The scattered field in the far-field region for two small metallic particles on a conducting substrate is analysed as a function of both their separation and the angle of incidence. Special attention is paid to multiple scattering, which appears when the particles are very close, as well as to its related effects such as its influence on the enhanced backscattering phenomenon and depolarization of the incident beam in the plane of incidence. 相似文献
59.
Javier Saiz‐Poseu Dr. Jordi Faraudo Antoni Figueras Dr. Ramon Alibes Dr. Felix Busqué Dr. Daniel Ruiz‐Molina 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(10):3056-3063
The large tendency of catechol rings to adsorb on surfaces has been studied by STM experiments with molecular resolution combined with molecular‐dynamics simulations. The strong adhesion is due to interactions with the surface and solvent effects. Moreover, the thermodynamic control over the differential adsorption of 1 and the nonanoic solvent molecules has been used to induce a new temperature‐induced switchable interconversion. Two different phases that differ in their crystal packing and the presence of solvent molecules coexist upon an increase or decrease in the temperature. These results open new insight into the behavior of catechol molecules on surfaces and 2D molecular suprastructures. 相似文献
60.
Pedro M. Martin‐Sanchez Santiago Sanchez‐Cortes Eduardo Lopez‐Tobar Valme Jurado Fabiola Bastian Claude Alabouvette Cesareo Saiz‐Jimenez 《Journal of Raman spectroscopy : JRS》2012,43(3):464-467
We used surface‐enhanced Raman spectroscopy to investigate the chemical composition of the black stains threatening the rock‐art paintings of Lascaux Cave, Montignac, France. The stains are mainly composed of melanin from the fungus Ochroconis sp. and the faecal pellets of the collembolan Folsomia candida. Surface‐enhanced Raman spectroscopy is a useful technique for revealing the structure of unknown macromolecules in cultural heritage research. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献