排序方式: 共有17条查询结果,搜索用时 187 毫秒
1.
J. A. Gallastegui C. L. Folcia J. Etxebarria J. Ortega I. De Francisco M. B. Ros 《Liquid crystals》2002,29(10):1329-1333
Optical second harmonic generation (SHG) measurements have been carried out on the B2 phases of three liquid crystal materials composed of conventional banana-shaped molecules (P-10-O-PIMB, P-8-O-PIMB and P-8-PIMB). Quantitative values of the second order susceptibilities dij have been deduced from SHG measurements at oblique incidences on polydomain racemic samples under an electric field. The dij coefficients are in the range 1-10 pm V-1. 相似文献
2.
3.
J. Ortega Corresponding author J. A. Gallastegui C. L. Folcia J. Etxebarria N. Gimeno M. B. Ros 《Liquid crystals》2013,40(4):579-584
The second-order susceptibility tensor of three liquid crystals composed of banana-shaped molecules has been fully determined. The measurements were carried out in single domain samples, aligned by means of an electric field parallel to the cell surface. Special care was taken with the appropriate determination of the index mismatch between the fundamental and second harmonic waves. This was achieved by using samples of different thickness. This parameter is very important for obtaining reliable values of the second order susceptibility tensor components, and is seldom directly measured. The suitability of the experimental procedure was checked by comparing the results obtained for the reference compound P-8-O-PIMB with previously reported measurements for this material. The dij coefficients obtained in this work are in the range 1–4?pm?V?1 and are compared with other values obtained in previous reports. 相似文献
4.
Dr. Antonela Canneva Prof. Dr. Mauricio F. Erben Prof. Dr. Rosana M. Romano Dr. Yury V. Vishnevskiy Christian G. Reuter Prof. Dr. Norbert W. Mitzel Prof. Dr. Carlos O. Della Védova 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(29):10436-10442
The gas‐phase molecular structure of (CH3)3CSNO was investigated by using electron diffraction, allowing the first experimental geometrical parameters for an S‐nitrosothiol species to be elucidated. Depending on the orientation of the ?SNO group, two conformers (anti and syn) are identified in the vapor of (CH3)3CSNO at room temperature, the syn conformer being less abundant. The conformational landscape is further scrutinized by using vibrational spectroscopy techniques, including gas‐phase and matrix‐isolation IR spectroscopy, resulting in a contribution of ca. 80:20 for the anti:syn abundance ratio, in good agreement with the computed value at the MP2(full)/cc‐pVTZ level of approximation. The UV/Vis and resonance Raman spectra also show the occurrence of the conformational equilibrium in the liquid phase, with a moderate post‐resonance Raman signature associated with the 350 nm electronic absorption. 相似文献
5.
6.
7.
Marele AC Mas-Ballesté R Terracciano L Rodríguez-Fernández J Berlanga I Alexandre SS Otero R Gallego JM Zamora F Gómez-Rodríguez JM 《Chemical communications (Cambridge, England)》2012,48(54):6779-6781
The reaction between 1,3,5-tris(4-hydroxyphenyl)benzene and benzene-1,3,5-tricarbonyl trichloride leads to polyester condensation and formation of a novel COF on an Au(111) surface. The characterization performed in situ by means of variable temperature STM and XPS reveals the formation of an array of hexagonal cavities with ca. 2 nm size. 相似文献
8.
Omuralide and Vibralactone: Differences in the Proteasome‐ β‐Lactone‐γ‐Lactam Binding Scaffold Alter Target Preferences
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Nerea Gallastegui Marion Rusch Dr. Christian Hedberg Prof. Dr. Stephan A. Sieber Prof. Dr. Michael Groll 《Angewandte Chemie (International ed. in English)》2014,53(2):571-574
Despite their structural similarity, the natural products omuralide and vibralactone have different biological targets. While omuralide blocks the chymotryptic activity of the proteasome with an IC50 value of 47 nM, vibralactone does not have any effect at this protease up to a concentration of 1 mM . Activity‐based protein profiling in HeLa cells revealed that the major targets of vibralactone are APT1 and APT2. 相似文献
9.
10.
Synthesis of poly(HEMA‐co‐AAm) hydrogels by visible‐light photopolymerization of aqueous solutions containing aspirin or ibuprofen: analysis of the initiation mechanism and the drug release
下载免费PDF全文
![点击此处可从《先进技术聚合物》网站下载免费的PDF全文](/ch/ext_images/free.gif)
María Lorena Gómez Antonela Gallastegui Mariana B. Spesia Hernán A. Montejano Roberto J. Williams Carlos M. Previtali 《先进技术聚合物》2017,28(4):435-442
Recently, we reported the synthesis of hydrogels by visible‐light photopolymerization of 2‐hydroxyethylmethacrylate and acrylamide, employing safranine O as sensitizer, and a functionalized silsequioxane (SFMA) as co‐initiator/crosslinker. The influence of the ionic character of a drug on its release rate from the hydrogels was also reported. In the present study, we analyzed the photoinitiation mechanism, the synthesis of hydrogels in the presence of aspirin (ASA) or ibuprofen (Ibu), and their release from hydrogels synthesized with variable SFMA concentrations. Concerning the photoinitiation mechanism, we found that the main contribution was the electron transfer reaction between the excited triplet state of safranine and SFMA, followed by a fast proton transfer reaction from secondary amine groups. The generated nitrogen radicals initiated the copolymerization reaction. The photoreaction quantum yield was 0.031. Concerning the drug‐release study, we found that the release rate of both drugs increased by increasing pH from 7 to 10. This was ascribed to the increase in the partial ionization of the carboxylic acid groups, a fact that reduced the interactions with the secondary amine groups present in SFMA and increased the release rate. The effect was larger for ASA than for Ibu. Increasing the amount of SFMA increased both the crosslink density and the fraction of H‐bonds formed with the drugs. At pH 10, the increment in the crosslink density was dominant for the release of Ibu while the increase in fraction of H‐bonds determined the release rate of ASA. Cytotoxicity studies showed that these materials did not exhibit significant hemolytic activity. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献