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211.
The antioxidant activity, total phenolic content, and total flavonoid content of 10 edible mushrooms species, including cultivated (Pleurotus ostreatus, Agaricus bisporus white and brown) and wild (P. ostreatus, Macrolepiota procera, Cantharellus cibarius, Russula vesca, Russula alutacea, Boletus edulis and Agaricus campestris), were determined. The extraction was performed using water and 50% water–ethanol and the caps and stipe were investigated separately. Water was the most appropriate solvent for phenolic compounds regardless of the sample. In contrast, the presence of ethanol in the solvent increased the extraction of flavonoids for cultivated P. ostreatus (caps and stipe), and wild R. alutacea, R. vesca, A. campestris, P. ostreatus (only caps) and C. cibarius, M. procera (only stipe). Significant differences between the antioxidant activities of the samples were registered in relationship with the different solvents. The antioxidant activity of water extract of dried A. bisporus brown (cultivated) showed the strongest 1,1-diphenyl-2-picrylhydrazyl radicals-scavenging assay (88.64%), while the B. edulis hydroalcoholic extract contained 74.93%. A detailed investigation into the functional group of phenolics and other organic compounds responsible with the antioxidant activity has been performed using Fourier transform infrared spectroscopy. The infrared spectra showed that the solvent-type directly influences the extraction process and, hence, the antioxidant activity. The present study contributes to information concerning mushrooms as sources of biologically active compounds. To investigate the correlations between phytochemical characteristics (i.e., phenolics, flavonoids and antioxidant activity) closely related to nature of solvents, the statistical analysis was performed.  相似文献   
212.
The thermal behavior of CoxFe3?xO4/SiO2 nanocomposites obtained by direct synthesis starting from nonahydrate ferric nitrate and hexahydrate cobalt nitrate in different ratios with and without the addition of 1,4-butanediol was studied. For the synthesis of CoxFe3?xO4 (x = 0.5–2.5) dispersed in the silica matrix a wide Co/Fe molar ratio was used. The decomposition processes, formation of crystalline phases, gases evolvement and mass changes during gels annealing at different temperatures were assessed by thermal analysis. The absence of succinate precursor and a low mass loss were observed in the case of the gel obtained in the absence of 1,4-butanediol. In case of gels obtained using a stoichiometric ratio of Co/Fe, no clear delimitation between Co and Fe succinates was observed, while for samples with a Fe or Co excess, the formation of the two succinates was observed. The evolution of the crystalline phase after annealing (673, 973 and 1273 K) investigated by X-ray diffraction analysis and Fourier transformed infrared spectrometry revealed that in samples with Fe excess, stoichiometric Fe/Co ratio or low Co excess, the cobalt ferrite (CoFe2O4) was obtained as a single phase, while in samples with higher cobalt excess, olivine (Co2SiO4) as a main phase, cobalt oxide and CoFe2O4 as secondary phases were obtained after annealing at 1273 K. The SEM images confirmed the nanoparticles embedding in the silica matrix, while the TEM and X-ray diffraction data showed that the obtained nanoparticles’ size was below 10 nm in most samples.  相似文献   
213.
The 15 valence-electron iron(I) complex [CpArFe(IiPr2Me2)] ( 1 , CpAr=C5(C6H4-4-Et)5; IiPr2Me2=1,3-diisopropyl-4,5-dimethylimidazolin-2-ylidene) was synthesized in high yield from the FeII precursor [CpArFe(μ-Br)]2. 57Fe Mössbauer and EPR spectroscopic data, magnetic measurements, and ab initio ligand-field calculations indicate an S= 3/2 ground state with a large negative zero-field splitting. As a consequence, 1 features magnetic anisotropy with an effective spin-reversal barrier of Ueff=64 cm−1. Moreover, 1 catalyzes the dehydrogenation of N,N-dimethylamine–borane, affording tetramethyl-1,3-diaza-2,4-diboretane under mild conditions.  相似文献   
214.
Huang  Zan  Chen  Hsinchun  Yip  Alan  Ng  Gavin  Guo  Fei  Chen  Zhi-Kai  Roco  Mihail C. 《Journal of nanoparticle research》2003,5(3-4):333-363
Nanoscale science and engineering (NSE) and related areas have seen rapid growth in recent years. The speed and scope of development in the field have made it essential for researchers to be informed on the progress across different laboratories, companies, industries and countries. In this project, we experimented with several analysis and visualization techniques on NSE-related United States patent documents to support various knowledge tasks. This paper presents results on the basic analysis of nanotechnology patents between 1976 and 2002, content map analysis and citation network analysis. The data have been obtained on individual countries, institutions and technology fields. The top 10 countries with the largest number of nanotechnology patents are the United States, Japan, France, the United Kingdom, Taiwan, Korea, the Netherlands, Switzerland, Italy and Australia. The fastest growth in the last 5 years has been in chemical and pharmaceutical fields, followed by semiconductor devices. The results demonstrate potential of information-based discovery and visualization technologies to capture knowledge regarding nanotechnology performance, transfer of knowledge and trends of development through analyzing the patent documents.  相似文献   
215.
A potentiometric oxygen electrode was successfully used to produce a microbial biosensors with an extended response range, based on immobilised yeast cells (Saccharomyces ellipsoideus). The response for ethanol takes ca. 7 min for the steady-state method and 2 min for kinetic measurements. A linear calibration achieved over more than two decades of ethanol concentration. Selective determination of ethanol in the presence of non-volatile compounds was achieved using a second PTFE membrane to cover the biocatalytic layer.  相似文献   
216.
Nickel–zinc ferrites have been synthesized via thermal decomposition of polynuclear coordination compounds containing as ligand the anion of malic acid, namely (NH4)[Fe2NixZn1–x(C4H4O5)(OH)3nH2O (x =0.25, 0.5 and 0.75, n=3 and 5). A comparison between the thermal behaviour of the studied polynuclear coordination compounds is inferred. Fe2NixZn1–xO4 (n=0.25, 0.5 and 0.75) ferrites with mean particle sizes of 65–85 Å and free from other phases are formed after a heating treatment of only one hour at 500°C.  相似文献   
217.
The binding of lead(II) cations to the terpyridine-type subunits of the helical ligand 1 leads to the self-assembly of different polynuclear metallosupramolecular architectures of nanometric size. Three different entities are generated and may be interconverted as a function of metal/ligand stoichiometry: a [4 x 4]Pb(16)(II) grid-type array 2, a [4 # 4]Pb(12)(II) double-cross species 4, and an intermediate complex 3. The structures of 2 and 4 have been confirmed by X-ray crystallography; that of 3 is based on NMR spectral data. The interconversion of the three species generates dynamic diversity and represents an expression of constitutional dynamic chemistry. In the course of ion binding, the helical molecules of ligand 1 unwrap to yield fully extended strands arranged in perpendicular fashion in the architectures 2-4 generated. This process amounts to molecular motions in two directions which confer to the present systems characteristics of two-dimensional nanomechanical devices, capable of performing 2D-contraction/extension motions. The triple features of self-organization, dynamic interconversion, and potential addressability displayed by the processes described trace a self-fabrication approach to nanoscience and nanotechnology.  相似文献   
218.
Convergence offers a new universe of discovery, innovation, and application opportunities through specific theories, principles, and methods to be implemented in research, education, production, and other societal activities. Using a holistic approach with shared goals, convergence seeks to transcend existing human limitations to achieve improved conditions for work, learning, aging, physical, and cognitive wellness. This paper outlines ten key theories that offer complementary perspectives on this complex dynamic. Principles and methods are proposed to facilitate and enhance science and technology convergence. Several convergence success stories in the first part of the 21st century—including nanotechnology and other emerging technologies—are discussed in parallel with case studies focused on the future. The formulation of relevant theories, principles, and methods aims at establishing the convergence science.  相似文献   
219.
One considers Hilbert space valued measures on the Borel sets of a compact metric space. A natural numerical valued integral of vector valued continuous functions with respect to vector valued measures is defined. Using this integral, different norms (we called them Monge–Kantorovich norm, modified Monge–Kantorovich norm and Hanin norm) on the space of measures are introduced, generalizing the theory of (weak) convergence for probability measures on metric spaces. These norms introduce new (equivalent) metrics on the initial compact metric space.  相似文献   
220.
Illegal deforestation is a worldwide problem which may be alleviated through technological means of deforestation monitoring, e.g. wireless sensor networks capable of identifying chain-saw noise, performing sound source localization (SSL), and alerting the authorities to the location of the illegal deforestation activity. In this paper we evaluate the feasibility of performing SSL on low-power, energy-constrained, microphone-array-equipped sensor nodes (SNs) with the Delay-and-Sum (DS) beam-forming algorithm. Our work is the first application of this technique for chain-saw noise. We evaluate array configurations of 4, 8, and 16 microphones, and a multitude of DS algorithm configurations, utilizing chain-saw recordings from the ESC dataset, which is available online. We implement the DS algorithm as a digital circuit in a Xilinx Spartan-6 FPGA and analyze its energy consumption. Our analysis indicates that accurate chain-saw localization can be achieved with much simpler microphone arrays and DS configurations compared to previous work. Furthermore, adding FPGA-based SSL capability to the SN increases the energy consumption by less than 10%, compared to a baseline SN capable only of chain-saw identification through spectral analysis executed in software on the SN microcontroller.  相似文献   
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