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排序方式: 共有393条查询结果,搜索用时 31 毫秒
381.
Funari CS Gullo FP Napolitano A Carneiro RL Mendes-Giannini MJ Fusco-Almeida AM Piacente S Pizza C Silva DH 《Food chemistry》2012,135(3):2086-2094
The Lippia genus is used in ethnobotany as food, beverages, seasoning and antiseptic remedies, among others. The chemical compositions of fifteen extracts of six Lippia species were investigated comparatively by HPLC-PDA. To avoid data replication of previous works on this genus, Lippia lupulina Cham. root ethanol extract was selected for isolation procedures based on Principal Component Analyses (PCA) of such data. Seven compounds previously unreported in this genus were isolated from this extract (a triterpene, two furanonaphtoquinones, a furanochromone, an isoflavone, a stilbene and an iridoid). The activities of extracts, fractions and pure compounds towards Candida albicans, Candida krusei, Candida parapsilosis and Cryptococcus neoformans were investigated. Two fractions from the extract of Lippia salviaefolia leaves showed marked inhibition of fungal growth, in addition to verbascoside and asebogenin, which showed MICs lower than 15.6μg/ml and may be promising leads for the development of new antifungal agents, especially against C. neoformans. 相似文献
382.
The risk of chronic diseases has been shown to be inversely related to tomato intake and the lycopene levels in serum and tissue. Cis-isomers represent approximately 50%-80% of serum lycopene, while dietary lycopene maintains the isomeric ratio present in the plant sources with about 95% of all-trans-lycopene. Supercritical CO(2) extraction (S-CO(2)) has been extensively developed to extract lycopene from tomato and tomato processing wastes, for food or pharmaceutical industries, also by using additional plant sources as co-matrices. We compared two S-CO(2)-extracted oleoresins (from tomato and tomato/hazelnut matrices), which showed an oil-solid bi-phasic appearance, a higher cis-lycopene content, and enhanced antioxidant ability compared with the traditional solvent extracts. Heat-treating, in the range of 60-100 °C, led to changes in the lycopene isomeric composition and to enhanced antioxidant activity in both types of oleoresins. The greater stability has been related to peculiar lycopene isomer composition and to the lipid environment. The results indicate these oleoresins are a good source of potentially healthful lycopene. 相似文献
383.
The use of mild conditions to perform the entrapment of biomolecules in polymeric matrices is a crucial step in a broad range of applications as biosensors, biocarrier‐mediated facilitated transport membranes, and drug‐controlled release devices. In this study, we investigated the crosslinking of poly(vinyl alcohol) (PVA) by glutaraldehyde in the absence of an acid catalyst and organic solvents to improve the water resistance of the hydrophilic biocompatible polymer. Glutaraldehyde was chosen as the crosslinking agent because it favors the intermolecular reaction with PVA and is able to bind nonspecifically to proteins. The effects of the temperature and glutaraldehyde content on the thermal and structural properties of the PVA films were examined. Membranes prepared at 40°C showed a maximum crosslinking density for low glutaraldehyde content namely, 0.04 wt % in the spreading solution. Higher amounts of the crosslinker led to the branching of PVA. The increase in membrane thermal properties and reduction in crystallinity were ascribed to the crosslinking treatment, which was confirmed by Fourier transform infrared analysis. The oxygen permeability of the films was reduced up to 2.7 times, which indicated that the crosslinking of the polymer was successfully accomplished. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
384.
Javier Plou Isabel García Mathias Charconnet Ianire Astobiza Clara García‐Astrain Cristiano Matricardi Agustín Mihi Arkaitz Carracedo Luis M. Liz‐Marzn 《Advanced functional materials》2020,30(17)
The composition and intercellular interactions of tumor cells in the tissues dictate the biochemical and metabolic properties of the tumor microenvironment. The metabolic rewiring has a profound impact on the properties of the microenvironment, to an extent that monitoring such perturbations could harbor diagnostic and therapeutic relevance. A growing interest in these phenomena has inspired the development of novel technologies with sufficient sensitivity and resolution to monitor metabolic alterations in the tumor microenvironment. In this context, surface‐enhanced Raman scattering (SERS) can be used for the label‐free detection and imaging of diverse molecules of interest among extracellular components. Herein, the application of nanostructured plasmonic substrates comprising Au nanoparticles, self‐assembled as ordered superlattices, to the precise SERS detection of selected tumor metabolites, is presented. The potential of this technology is first demonstrated through the analysis of kynurenine, a secreted immunomodulatory derivative of the tumor metabolism and the related molecules tryptophan and purine derivatives. SERS facilitates the unambiguous identification of trace metabolites and allows the multiplex detection of their characteristic fingerprints under different conditions. Finally, the effective plasmonic SERS substrate is combined with a hydrogel‐based three‐dimensional cancer model, which recreates the tumor microenvironment, for the real‐time imaging of metabolite alterations and cytotoxic effects on tumor cells. 相似文献
385.
L. Jalabert P. Temple-Boyer G. Sarrabayrouse F. Cristiano B. Colombeau F. Voillot C. Armand 《Microelectronics Reliability》2001,41(7)
This paper deals with the development of the disilane Si2H6 gaseous source for gate technology and more precisely, reports on the use of nitrogen doped silicon (NIDOS) deposited from disilane and ammonia for the realisation of polycrystalline gate. Boron diffusivity into the NIDOS films is studied thanks to SIMS experiments, and results are extended to the fabrication of P+-poly-Si/NIDOS/SiO2/Si capacitive structures. Electrical characterisations evidenced finally the influence of boron and nitrogen atoms on the electrical properties of PMOS devices. 相似文献
386.
Fabiola Liscio Silvia Milita Cristiano Albonetti Pasquale D'Angelo Antonietta Guagliardi Norberto Masciocchi Raffaele Guido Della Valle Elisabetta Venuti Aldo Brillante Fabio Biscarini 《Advanced functional materials》2012,22(5):943-953
A multiscale investigation of N,N′‐bis(n‐octyl)‐x:y, dicyanoperylene‐3,4:9,10‐bis(dicarboximide), PDI8‐CN2, shows the same molecular arrangement in the bulk and in thin films sublimated on SiO2/Si wafers. Non‐conventional powder diffraction methods and theoretical calculations concur to provide a coherent picture of the crystalline structure. X‐ray diffraction (XRD) and atomic force microscopy (AFM) analyses of films of different thickness deposited at different substrate temperatures indicate the existence of two temperature‐dependent deposition regimes: a low‐temperature (room temperature) regime and a high‐temperature (80–120 °C) one, each characterized by different growth mechanisms. These mechanisms eventually result in different morphological and structural features of the films, which appear to be highly correlated with the trend of the electrical parameters that are measured in PDI8‐CN2‐based field‐effect transistors. 相似文献
387.
Thakur Prasad Yadav Cristiano F. Woellner Shyam K. Sinha Tiva Sharifi Amey Apte Nilay Krishna Mukhopadhyay Onkar Nath Srivastava Robert Vajtai Douglas S. Galvao Chandra Sekhar Tiwary Pulickel M. Ajayan 《Advanced functional materials》2018,28(26)
The realization of quasicrystals has attracted a considerable attention due to their unusual structures and properties. The concept of quasicrystals in the atomically thin materials is even more appealing due to the in‐plane covalent bonds and weak interlayer interactions. Here, it is demonstrated that 2D quasicrystals can be created/isolated from bulk phases because of long‐range interlayer ordered aperiodic arrangements. An ultrasonication‐assisted exfoliation of polygrained icosahedral Al–Pd–Mn quasicrystals at room temperature shows the formation of a large area of mono‐ and few layers in threefold quasicrystalline plane. The formation of these layers from random grain orientation consistently indicates that the threefold plane is most stable in comparison to the twofold and fivefold planes in icosahedral clusters. The above experimental observations are further supported with help of theoretical simulations. The mono‐ and few‐layered aperiodic planes render plentiful active sites for the catalysis of hydrogen evolution reaction. The threefold 2D quasicrystalline plane exhibits a hydrogen evolution reaction overpotential of ≈100 mV (160 times less than bulk counterpart) and long‐term durability. These systems constitute the first demonstration of quasicrystalline monolayer ordering in a free‐standing thin layer without requiring the support of periodic or aperiodic substrate. 相似文献
388.
Integrating dynamic spectrum access and device‐to‐device via cloud radio access networks and cognitive radio 下载免费PDF全文
Marcelo Antonio Marotta Leonardo Roveda Faganello Maicon Kist Lucas Bondan Juliano Araujo Wickboldt Lisandro Zambenedetti Granville Juergen Rochol Cristiano Bonato Both 《International Journal of Communication Systems》2018,31(11)
Dynamic Spectrum Access (DSA) can be integrated with Device‐to‐Device (D2D) communications to enable the exploitation of unused spectrum portions and to address the spectrum scarcity problem. Spectrum management mechanisms integrated into DSA and D2D allow low‐power communications between User Equipments without interfering with licensed primary users. However, these mechanisms tend to be energy and processing intensive, being unfeasible to implement in User Equipments with strict battery and processing limitations. On the other hand, Cloud Radio Access Networks already leverage the virtually unlimited computing capacity of clouds for baseband processing functions. Thus, in this article, we propose the Cognitive Radio Device‐to‐Device (CRD2D) approach aiming to offload spectrum management functionality to the cloud taking advantage of Cloud Radio Access Networks architecture to support the integration of DSA and D2D. 相似文献
389.
E.?Piatti A.?Sola D.?DagheroEmail author G.?A.?Ummarino F.?Laviano J.?R.?Nair C.?Gerbaldi R.?Cristiano A.?Casaburi R.?S.?Gonnelli 《Journal of Superconductivity and Novel Magnetism》2016,29(3):587-591
We perform electric double-layer gating experiments on thin films of niobium nitride. Thanks to a cross-linked polymer electrolyte system of improved efficiency, we induce surface charge densities as high as ≈ 2.8 × 1015cm?2 in the active channel of the devices. We report a reversible modulation of the superconducting transition temperature (either positive or negative depending on the sign of the gate voltage) whose magnitude and sign are incompatible with the confinement of the perturbed superconducting state to a thin surface layer, as would be expected within a na¨?ve screening model. 相似文献
390.
Augusto G.O. de Freitas Robson L. Dazzi Paulo I.R. Muraro Vanessa Schmidt Manfredo Hörner Cristiano Giacomelli 《Materials science & engineering. C, Materials for biological applications》2013,33(4):2221-2228
The development of organic solvent-free methods for the encapsulation of hydrophobic molecules is necessary for advances in micelle-mediated drug delivery. In this study we investigated the film/contact approach in which the use of organic solvents is limited to the preparation of a dry film before encapsulation. Unloaded micelles of five structurally related block copolymers were placed in contact with thin homogeneous films of two hydrophobic triazene anticancer compounds (1-(4-amidophenyl)-3-(4-acetylphenyl)triazene (1) and corresponding triazenido complex with triphenylphosphanegold(I) fragment (2)). The micelle surface becomes saturated with the drug, which eventually penetrates as a front into the core. Because the drug interacts with both the shell and the core microenvironments of micelle during the process, the maximum loading capacities were very sensitive to block copolymer micelle composition, ranging from 2.2 to 20.4% (wt./wt. of polymer). We conclude that micelles with poly[2-(diisopropylamino)ethyl methacrylate] (PDPA) cores are the best option for the encapsulation of triazene compounds because i) they are prepared in absence of organic phase; ii) the drug concentration in the particles is high enough for a therapeutic effect and iii) the responsiveness properties of PDPA is appropriate for practical applications in pH-triggered drug release systems. 相似文献