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131.
Iulia Puescu Izolda Kntor Gyrgy Babos Zoltn May Andrea Fodor-Kardos Zsombor Miskolczy Lszl Biczk Francisc Pter Mihai Medeleanu Tivadar Feczk 《International journal of molecular sciences》2022,23(15)
Anthocyanidins, the aglycons of anthocyanins, are known, beyond their function in plants, also as compounds with a wide range of biological and pharmacological activities, including cytostatic effect against various cancer cells. The nature and position of the substituents in the flavylium cation is essential for such biological properties, as well as the equilibrium between the multistate of the different chemical species that are generated by the flavylium cation, including quinoidal base, hemiketal, and cis- and trans-chalcones. In this work, eight new flavylium derivatives were synthesized, characterized for confirmation of the structure by FT-IR and 2D-NMR, and investigated in vitro as possible cytostatic compounds against HCT116 and HepG2 cancer cells. The most active two compounds were explored for their halochromic properties that can influence the biological activity and subjected to molecular encapsulation in β-cyclodextrin derivatives in order to increase their solubility in water and bioavailability. The anticancer effect was influenced by the position (6-, 7-, or 8-) of the methoxy group in the β-ring of the methoxy-4′-hydroxy-3′-methoxyflavylium cation, while the study of the halochromic properties revealed the important role played by the chalcone species of the pH-dependent multistate in both the uncomplexed and inclusion complex forms of these anthocyanidins. 相似文献
132.
The multilevel modulation techniques of 64-quadrature amplitude modulation (QAM) and 64-differential amplitude and phase-shift keying (DAPSK) have been proposed in combination with the orthogonal frequency-division multiplexing (OFDM) scheme for digital terrestrial video broadcasting (DTVB). With this system a data rate of 34 Mb/s can be transmitted over an 8-MHz radio channel. A comparison of these modulation methods in the uncoded case has been presented by Engels and Rohling (see European Trans. Telecommun., vol.6, p.633-40, 1995). The channel coding scheme proposed for DTVB by Schafer (see Proc. Int. Broadcasting Convention, Amsterdam, The Netherlands, p.79-84, 1995) consists of an inner convolutional code concatenated with an outer Reed-Solomon (RS) code. In this paper the performance of the convolutional codes is analyzed for the two modulation techniques. This analysis includes soft decision Viterbi (1971) decoding of the convolutional code. For soft decision decoding of DAPSK modulated signals a new metric is developed 相似文献
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134.
R. Mayén-Mondragón J. M. Yánez-Limón K. M. Moya-Canul A. Herrera-Gomez M. Vazquez-Lepe F. Espinoza-Beltrán A. M. López Beltrán 《Journal of Materials Science: Materials in Electronics》2013,24(6):1981-1988
Lead zirconate titanate [PZT (53/47)] films (around 200 nm thick) were prepared by the sol–gel acetic-acid route, spin-coating onto Si/SiO2/Pt substrates. A simple thermal annealing program rendered complete crystallization to the perovskite phase and full removal of the organic material. The 53/47 film composition was attained in the bulk, however, X-ray photoelectron spectroscopy detected a different titanium/zirconium ratio at the film surface. Hysteresis loops were measured using a film-tester constructed at our laboratory. The single-annealed films showed a high resistive leakage. A second annealing cycle led to a better film densification and a marked reduction in surface roughness, significantly enhancing the ferroelectric response. Ferroelectric domains were mapped by piezoresponse force measurements. The relatively-simple experimental procedure applied allowed the fabrication of good quality ferroelectric films. 相似文献
135.
May May-hung Cheng 《Canadian Journal of Science, Mathematics, & Technology Education》2013,13(2):99-120
Abstract This article describes the outcome of a collaborative project between the Hong Kong Institute of Education and four secondary schools that aims to promote the development of scientific investigation skills. The project team designed scientific investigation tasks collaboratively with the teachers and provided school-based support when the tasks were implemented. A total of six teachers and 575 students were involved. Data were collected through questionnaires completed by the students and individual interviews with science teachers about their classroom practice after the completion of the project. The findings suggest that the students did not meet many difficulties and that there were positive influences on students’ interest in learning science. The teachers perceived that there were challenges related to raising students’ self-regulated learning abilities, structuring tasks that were at appropriate levels of difficulty, and promoting group cooperation among the students. Finally, the article argues that the strategies implemented in this study were effective, though it takes much time and effort to help students develop self-regulated learning abilities. The conclusion suggests that teachers consider these challenges collectively and proposes a two-staged model for planning scientific investigation tasks. 相似文献
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137.
正张宏明先生作为奥通汽车用品有限公司负责人,自07年就开始从事奥迪专项的项目工作。在上海追得"智慧·创新·分享"发布会行业交流论坛上,张宏明先生凭借自身4S服务商的经验,向与会的众多商协会领导、行业思想领袖、企业代表、渠道代表分享了自己从一线的管理中实践出来的行业认知——一个4S店服务商心中的5个"关键词"。 相似文献
138.
Tiffany D. Andras Troy S. Alexander Asiri Gahlena R. Mitchell Parry Facundo M. Fernandez Julia Kubanek May D. Wang Mark E. Hay 《Journal of chemical ecology》2012,38(10):1203-1214
Coral reefs are in global decline, with seaweeds increasing as corals decrease. Although seaweeds inhibit coral growth, recruitment, and survivorship, the mechanism of these interactions is poorly understood. Here, we used field experiments to show that contact with four common seaweeds induces bleaching on natural colonies of Porites rus. Controls in contact with inert, plastic mimics of seaweeds did not bleach, suggesting seaweed effects resulted from allelopathy rather than shading, abrasion, or physical contact. Bioassay-guided fractionation of the hydrophobic extract from the red alga Phacelocarpus neurymenioides revealed a previously characterized antibacterial metabolite, neurymenolide A, as the main allelopathic agent. For allelopathy of lipid-soluble metabolites to be effective, the compounds would need to be deployed on algal surfaces where they could transfer to corals on contact. We used desorption electrospray ionization mass spectrometry (DESI-MS) to visualize and quantify neurymenolide A on the surface of P. neurymenioides, and we found the molecule on all surfaces analyzed, with highest concentrations on basal portions of blades. 相似文献
139.
Andreas Kiermeier Mark Tamplin Damian May Geoff Holds Michelle Williams Alison Dann 《Food microbiology》2013
Packaging fresh lamb in a vacuum (VAC) versus a 100% CO2 modified atmosphere (MAP) may influence product shelf-life and the bacterial communities. While VAC is a common packing method and 100% CO2 MAP is used in some countries, there is little information about how these different techniques affect the growth of spoilage bacteria and sensory attributes of lamb. The aim of this study was to assess changes in microbiological and organoleptic properties, and determine differences in microbial communities by terminal restriction fragment length polymorphism (TRFLP) and 454 pyrosequencing, in bone-in (BI) and bone-out (BO) MAP- and VAC-packed lamb shoulders stored at −0.3 °C over 12 wk. VAC and MAP lamb shoulders were acceptable in sensory test scores over 12 wk of storage at −0.3 °C, despite total viable count (TVC) and lactic acid bacteria (LAB) levels increasing to 8 log10 CFU/cm2 for VAC lamb and 4–6 log10 CFU/cm2 for MAP lamb. Similar to the sensory results, there were no significant differences in microbial communities between BI and BO product. However, types of bacteria were different between VAC and MAP packaging. Specifically, while VAC shoulder became dominated by Carnobacterium spp. in the middle of the storage period, the MAP shoulder microbial population remained similar from the start until later storage times. 相似文献
140.
Modeling of a membrane reactor system for crude palm oil transesterification. Part II: Transport phenomena 下载免费PDF全文
Pin Pin Oh Mei Fong Chong Harrison Lik Nang Lau Yuen May Choo Junghui Chen 《American Institute of Chemical Engineers》2015,61(6):1981-1996
The mechanistic modeling of biodiesel production process in membrane reactor with the consideration of chemical reaction, phase equilibrium, and ultrafiltration is important for the membrane reactor design. In part II of this work, the chemical and phase equilibrium (CPE) model for crude palm oil transesterification reaction in the membrane reactor developed in part I is extended to an integration of CPE with modified Maxwell–Stefan model, which considers multicomponent mass transport phenomena of concentration polarization and intramembrane. A good fit of simulated permeate fluxes and apparent solute rejection to the experimental data shows that the model has a good prediction capability. Reversible fouling was found to be the major fouling and no pore plugging was observed. Simulation results verified that micelles were retained by the membrane at CPO:MEOH molar ratio of 1:24 and catalyst concentration of 0.5 wt %. However, phase inversion happened when catalyst concentration of 0.05 and 0.1 wt % were used. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1981–1996, 2015 相似文献