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51.
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S. Sarmento P. Simeão Carvalho M. R. Chaves F. Pinto H. T. Nguyen 《Liquid crystals》2013,40(12):1839-1845
The SmC* phase of (R)-4-(1-methylheptyloxycarbonyl)phenyl 4'-(4-decyloxy-3-fluorobenzoyloxy)-benzoate, 10FHBBBM7*, shows an anomalous thermal hysteresis that is reflected in the values of the measured dielectric constant. When the cooling-heating cycle is repeated, a memory effect occurs. In this work, we present a detailed study and a tentative interpretation of this unusual effect. 相似文献
53.
Pharmacokinetics (PK) is a branch of pharmacology dedicated to the study of the time course of drug concentrations, from absorption to excretion from the body. PK dynamic models are often based on homogeneous, multi-compartment assumptions, which allow to identify the PK parameters and further predict the time evolution of drug concentration for a given subject. One key characteristic of these time series is their high variability among patients, which may hamper their correct stratification. In the present work, we address this variability by estimating the PK parameters and simultaneously clustering the corresponding subjects using the time series. We propose an expectation maximization algorithm that clusters subjects based on their PK drug responses, in an unsupervised way, collapsing clusters that are closer than a given threshold. Experimental results show that the proposed algorithm converges fast and leads to meaningful results in synthetic and real scenarios. 相似文献
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Maria Andrea Mendes Formiga Melo Marco Aurélio Rodrigues de Melo Andrea Suame Gouvea Costa Pontes Ana Flávia Félix Farias Manoel Barbosa Dantas Clediana Dantas Calixto Antonio Gouveia de Souza José Rodrigues de Carvalho Filho 《Journal of Thermal Analysis and Calorimetry》2014,117(2):845-849
Vegetable oils with variable proportions of oleic, linoleic, and linolenic acids are more susceptible to oxidative processes. In this subject, this study evaluates the physical chemical properties and oxidative stability of non-conventional oils such as andiroba, babassu, sesame, oiticica, jatropha, and grape through accelerated oxidation techniques (pressurized differential scanning calorimetry, Rancimat and PetroOxy). It was verified that babassu and andiroba oil do not showed detectable induction period presenting high oxidative stability; moreover, it was observed that the enthalpic events occurred in 1.19, >10, 0.53, 0.49, 0.49, and 0.60 h for the andiroba oil, babassu oil, sesame seeds, jatropha, oiticica oils, and grapes, respectively, stimulating the conclusion of greater stability for the babassu oil. 相似文献
56.
Carla Marisa Brito Carvalho Marta Akemi FujitaTimothy John Brocksom Kleber Thiago de Oliveira 《Tetrahedron》2013
New β-fused uracil-porphyrin conjugates were synthesized by the tetramerization of uracil-pyrroles under acidic conditions. Two different synthetic approaches were systematically studied in order to evaluate their efficiency, as well as the possibility to obtain a single regioisomer. Metallation effects were studied for aggregation in solution, and preliminary photophysical experiments were also performed in order to evaluate the potential of these new compounds. 相似文献
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Elionai Cassiana de Lima Gomes Izabella Ercole de Carvalho Silvia Ligório Fialho Jamile Barbosa Maria Irene Yoshida Armando da Silva Cunha Júnior 《Journal of Thermal Analysis and Calorimetry》2018,131(3):2123-2128
Most of the pharmaceutical products are formulated as solid dosage form, which may present drug–excipient interactions that lead to changes in the chemical nature of the drug, such as solubility and bioavailability and may compromise its safety and effectiveness. Differential scanning calorimetry (DSC) is a widely used method for the rapid evaluation of the drug-excipient compatibility and the stability of the mixture formed; however, there is no consensus on the preparation methods of the drug–excipient mixtures. The aim of this study was to investigate the influence of the mixing method on the drug–excipient compatibility studies by means of DSC analysis, using tenofovir disoproxil fumarate as a drug model. Statistical analysis revealed significant differences in the heat of fusion of the drug in the mixtures prepared by several mixing methods. Vortex Mixer with a Pop-Off Cup used for 3 min proved to be very satisfactory for these studies. A polymorphic transition was observed in the mixture prepared with the mortar and pestle. Therefore, this method should be avoided since it may induce errors in the interpretation of DSC results. In this way, the mixing method used to prepare a mixture for studies of interactions between the API and the excipients in a pharmaceutical formulation has a great influence on the results and it must be chosen carefully. 相似文献
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P. L. Almeida G. Lavareda C. Nunes De Carvalho A. Amaral M. H. Godinho M. T. Cidade 《Liquid crystals》2013,40(3):475-477
In this work we perform a study of 250 ≈ μm thick flexible electro-optical PDLC type cells made from a biocompatible cellulose derivative film and several conductive substrates. The deposition of an ITO layer by reactive thermal evaporation on a polymeric substrate was referred to in the literature very recently and this type of coated substrate was used in the present work. In order to consider the influence of the substrates on the electro-optical behaviour of the cells, five cells were made using different substrates (three flexible polymers and two glass for comparison). Three of the substrates were coated under the same conditions, and the other two were commercially available substrates. 相似文献