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排序方式: 共有219条查询结果,搜索用时 15 毫秒
31.
Fernanda V. Corrêa Sibele R.R. Comim Aline M. de Cesaro Aline A. Rigo Marcio A. Mazutti Haiko Hense J. Vladimir Oliveira 《The Journal of chemical thermodynamics》2011,43(1):34-38
The compound oryzanol available in the rice bran (oriza sativa) is well known for its antioxidant activity. Phase equilibrium data involving oryzanol in compressed fluids, hardly found in the literature, are important to provide the basis for the extraction and fractionation processes. In this sense, the aim of this work is to report phase equilibrium measurements for the system (γ-oryzanol + chloroform) in compressed propane. Phase equilibrium experiments were performed using the static synthetic method (cloud points transition data) in a high-pressure variable-volume view cell in the temperature range of 303 K to 353 K, pressures up to 17 MPa, for oryzanol overall mass fractions of 2 wt%, 5 wt% and 10 wt% in (propane + chloroform) mixtures. A complex phase behaviour comprising vapour–liquid, liquid–liquid, vapour–liquid–liquid, solid–liquid, solid–liquid–liquid, solid–liquid–liquid–vapour transitions were visually observed for the system studied. 相似文献
32.
Barbara Bellich Massimiliano Borgogna Michela Cok Attilio Cesàro 《Journal of Thermal Analysis and Calorimetry》2011,103(1):81-88
Hydrogels are characterized by properties which make them ideal candidates for applications in several fields, such as drug
delivery, biomedicine, and functional foods. Molecular diffusion out of a hydrogel matrix depends on their hydrodynamic radii
and the mesh sizes within the matrix of the gel. A quantitative experimental and mathematical understanding of interactions,
kinetics, and transport phenomena within complex hydrogel systems assists network design by identifying the key parameters
and mechanisms that govern the rate and extent of solute release. In this article a calorimetric differential scanning calorimetry
(DSC) study reports on the approach to parallel water effusion from a hydrogel matrix to the release of a model protein. The
measurement of the water evaporation is taken as the simplest routine determination of a phenomenon that is basically due
to a diffusive process through the porous structure of the gel and thermodynamically governed by the difference in the water
chemical potential inside and outside of the bead. The analysis of the experimental calorimetric curves is made with the purpose
of extracting several numerical parameters characteristic of each curve. The rationale is to develop a simple methodology
to understand the release properties of the porous structure of the complex gel matrix by means of DSC. 相似文献
33.
Gobat Giorgio Guillot Louis Frangi Attilio Cochelin Bruno Touzé Cyril 《Meccanica》2021,56(8):1937-1969
Meccanica - Quasi-periodic solutions can arise in assemblies of nonlinear oscillators as a consequence of Neimark-Sacker bifurcations. In this work, the appearance of Neimark-Sacker bifurcations is... 相似文献
34.
Attilio Anzano Bruna de Falco Mohammad Ammar Annarita Ricciardelli Laura Grauso Mohammed Sabbah Rosanna Capparelli Virginia Lanzotti 《Molecules (Basel, Switzerland)》2022,27(24)
Moringa oleifera is a traditional food crop widespread in Asiatic, African, and South American continents. The plant, able to grow in harsh conditions, shows a high nutritional value and medicinal potential evidencing cardioprotective, anti-inflammatory, antioxidant, and antimicrobial properties. The purpose of this study was the phytochemical analysis of M. oleifera and the identification of the antimicrobial compounds by combining a chemical approach with in vitro tests. The metabolite profile of M. oleifera polar and apolar extracts of leaves and seeds were investigated by using Nuclear Magnetic Resonance spectroscopy and Gas Chromatography-Mass Spectrometry. The antimicrobial activity of all of the obtained extract was evaluated against four bacterial pathogens (Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Salmonella enterica). The chemical analysis provided a wide set of metabolites that were identified and quantified. Moreover, apolar extracts from seeds showed a significant concentration-dependent antimicrobial activity against S. aureus and S. epidermidis, (4 mg/mL reduced the viability up to 50%) that was associated to the content of specific fatty acids. Our results remarked the advantages of an integrated approach for the identification of plant metabolites and its use in association with biological tests to recognize the compounds responsible for bioactivity without compounds purification. 相似文献
35.
Lucio Randaccio Ennio Zangrando Attilio Cesro Dagmar Holthenrich Bernhard Lippert' 《Journal of Molecular Structure》1998,440(1-3):221-226
The characterization by X-ray analysis of the trans,trans,trans-[bis(1-methylcytosinate,N4)bis(ammine)bis(hydroxo)platinum(IV)] octahydrate complex (I) reveals an unexpected crystal packing. The neutral complex molecule is hosted by layers, totally built up by water molecules which do not exhibit a direct coordination to metal ions. These corrugated layers are made by puckered eight- and planar four-membered rings of water molecules, held together by hydrogen bonds with an ordered proton arrangement. 相似文献
36.
Masciocchi N Ardizzoia GA Brenna S LaMonica G Maspero A Galli S Sironi A 《Inorganic chemistry》2002,41(23):6080-6089
The synthesis of a number of 3d transition metal binary pyrazolates in microcrystalline form, thus suitable for a full XRPD characterization, has been pursued. The crystal and molecular structures of the Fe(pz)3, Co(pz)2, Co(pz)3, and Ni(pz)2 polymers, together with the few congeners reported in the recent literature, show that these species tend to afford highly crystalline materials where strictly collinear chains of metal atoms are present. Depending on the synthetic strategy used, Ni(pz)2 has been found to crystallize as two different alpha (orthorhombic) and beta (monoclinic) phases, possessing nearly identical intramolecular features. Data for each compound follow. Fe(pz)3: C9H9FeN6, hexagonal, P63/m, a = 9.1745(3) A, c = 7.2191(4) A, Z = 2. Co(pz)2: C6H6CoN4, orthorhombic, Ibam, a = 7.5239(5) A, b = 14.3461(9) A, c = 7.4331(5) A, Z = 4. Co(pz)3: C9H9CoN6, hexagonal, P63/m, a = 9.1966(3) A, c = 7.1051(3) A, Z = 2. Alpha-Ni(pz)2: C6H6N4Ni, orthorhombic, Cmcm, a = 16.6758(11) A, b = 6.4872(4) A, c = 6.9423(6) A, Z = 4. Beta-Ni(pz)2: C6H6N4Ni, monoclinic, P21/m, a = 9.967(2) A, b = 6.975(1) A, c = 6.016(1), A, beta = 98.50(1)degrees, Z = 2. The thermal stability and the detailed structural properties of these model compounds have been evaluated, in the light of the technologically relevant crystal phases (the well-known metal-diazolates showing reversible spin-crossover or spin-transition behavior) obtainable upon doping, magnetic dilution, and ring substitution (in the 4-position). 相似文献
37.
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39.
Francesco Minisci Attilio Citterio Elena Vismara Claudio Giordano 《Tetrahedron》1985,41(19):4157-4170
The synthetic interest of the direct substitution of protonated heteroaromatic bases by nucleophilic carbon-centered radicals is furtheron developed by the following new achievements: i) utilization of the redoc system in several solvents; ii) utilization of benzoyl peroxide in alcohols; iii) carbamoylation by HCONH2 and H2O2 in the presence of catalytic amounts of Fe(II). These systems allow to obtain either substitution till now tried without success or reactions of industrial interest. Polar effects play a dominant role in determining reactivity, selectivity and synthetic applications; in particular the role of the strongly nucleophilic intermediate radicals of pyridinyl type in the rearomatization step is emphasized. 相似文献
40.
Hypervalent iodine as good leaving group: oxidative rearrangement of 1-IODO-2-methoxy-2-arylalkanes.
Attilio Citterio Marco Gandolfi Claudio Giordano Graziano Castaldi 《Tetrahedron letters》1985,26(13):1665-1666
A new example of the good leaving group properties of hypervalent iodine is reported: oxidative rearrangement of 1-iodo-2-methoxy-2-arylalkanes 1 (R=alkyl) provides, via 1,2-aryl shift, alkyl benzyl ketones 3 in good yields. 相似文献