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681.
Joo Miguel Silveira Stephane Longelin Antnio Duarte Mata Maria Luísa Carvalho 《Journal of Raman spectroscopy : JRS》2012,43(8):1089-1093
Oxygen is a polymerization inhibitor of 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloxypropoxy) phenyl]propane (Bis‐GMA) and triethylene glycol dimethacrylate, a basic constituent of most dental adhesive materials. Some hypothesis that oxygen remains in tooth mineralized tissues following some dental treatments and thus reducing adhesive forces and compromising the restorative treatments, have been advanced, but no experimental demonstration has been conducted. We used for the first time a confocal micro Raman technique to successfully identify the presence of oxygen generated by tooth bleaching products in tooth enamel surface, hence, helping to provide confirmation for this theory. This new data result from a multidisciplinary research approach between physics and dentistry is pioneering and could in the future support dental treatment protocol changes, increasing productivity and patient's benefits. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
682.
An essential step towards improving sound insulation is a reliable means of quantifying the performance. However, for various reasons sound insulation measurements at low frequencies are associated with relatively high uncertainty and wide variance values. The objective of this research is to develop a method of sound insulation measurement which complements the standard ISO 140 measurement methods by providing improved accuracy at low frequencies. In this paper part of the problem is considered, namely the measurement of power radiated into the receiver room. The ‘peak envelope method’ is based on mode theory and the measurement employs a pair of microphones in the receiver room and a calibrated volume velocity source. No reverberation time measurements are required. The theory is outlined and computer simulations and trial measurements are carried out in order to validate the theory. Good agreement in numerical and experimental validation is demonstrated. We conclude that the peak envelope method is suitable for the measurement of radiated sound power at modal frequencies where ISO 140 methods are poorly adapted. In order to obtain transmission loss, a measure of incident power in the source room will also be required, which will be the subject of future works. 相似文献
683.
Pedro Silvino Pereira Carlos Vinicius Barros Oliveira Ana Josicleide Maia Maria Celeste Vega-Gomez Miriam Roln Cathia Coronel Antnia Eliene Duarte Henrique Douglas Melo Coutinho Abolghasem Siyadatpanah Roghayeh Norouzi Seyed Jafar Adnani Sadati Polrat Wilairatana Teresinha Gonalves Silva 《Molecules (Basel, Switzerland)》2022,27(9)
Cymbopogon winterianus, known as “citronella grass”, is an important aromatic and medicinal tropical herbaceous plant. The essential oil of C. winterianus (EOCw) is popularly used to play an important role in improving human health due to its potential as a bioactive component. The present study aimed to identify the components of the essential oil of C. winterianus and verify its leishmanicidal and trypanocidal potential, as well as the cytotoxicity in mammalian cells, in vitro. The EOCw had geraniol (42.13%), citronellal (17.31%), and citronellol (16.91%) as major constituents. The essential oil only exhibited significant cytotoxicity in mammalian fibroblasts at concentrations greater than 250 μg/mL, while regarding antipromastigote and antiepimastigote activities, they presented values considered clinically relevant, since both had LC50 < 62.5 μg/mL. It can be concluded that this is a pioneer study on the potential of the essential oil of C. winterianus and its use against the parasites T. cruzi and L. brasiliensis, and its importance is also based on this fact. Additionally, according to the results, C. winterianus was effective in presenting values of clinical relevance and low toxicity and, therefore, an indicator of popular use. 相似文献
684.
Adriano de Souza Carolino Matheus Moraes Biondo tefan lu Henrique Duarte da Fonseca Filho Pedro Henrique Campelo Jaqueline de Araújo Bezerra Cicero Mota Hidembergue Ordozgoith da Frota Vanderlei Salvador Bagnato Natalia Mayumi Inada Edgar Aparecido Sanches 《Molecules (Basel, Switzerland)》2022,27(15)
The development of conjugated polymer-based nanocomposites by adding metallic particles into the polymerization medium allows the proposition of novel materials presenting improved electrical and optical properties. Polyaniline Emeraldine-salt form (ES–PANI) has been extensively studied due to its controllable electrical conductivity and oxidation states. On the other hand, tungsten oxide (WO3) and its di-hydrated phases, such as WO3·2H2O, have been reported as important materials in photocatalysis and sensors. Herein, the WO3·2H2O phase was directly obtained during the in-situ polymerization of aniline hydrochloride from metallic tungsten (W), allowing the formation of hybrid nanocomposites based on its full oxidation into WO3·2H2O. The developed ES–PANI–WO3·2H2O nanocomposites were successfully characterized using experimental techniques combined with Density Functional Theory (DFT). The formation of WO3·2H2O was clearly verified after two hours of synthesis (PW2 nanocomposite), allowing the confirmation of purely physical interaction between matrix and reinforcement. As a result, increased electrical conductivity was verified in the PW2 nanocomposite: the DFT calculations revealed a charge transfer from the p-orbitals of the polymeric phase to the d-orbitals of the oxide phase, resulting in higher conductivity when compared to the pure ES–PANI. 相似文献
685.
686.
Duarte B. Clemente Dr. Jaime A. S. Coelho 《European journal of organic chemistry》2023,26(17):e202300193
Total synthesis of natural products is an important discipline of organic chemistry that has enabled the development of new synthetic methods and strategies for the preparation and study of the structure and reactivity of complex naturally occurring products. In this review we summarize the synthetic strategies developed in Portugal by several research groups for the synthesis of bioactive natural products including alkaloids, cyclitols, fatty alcohols, phenylpropanoic acids, γ-butyrolactones, xanthones and nucleosides. 相似文献
687.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献