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1.
Electronic structure spin-polarized calculations were performed for 79-atoms embedded clusters representing the ordered intermetallic compound FeNi, the fcc Fe-rich disordered alloy Fe85Ni15 in an antiferromagnetic (AFM) configuration, and the ferromagnetic (FM) disordered alloy Fe50Ni50. The spin-polarized discrete variational method (DVM) in Density Functional theory was employed. Spin magnetic moments, as well as the 57Fe Mössbauer hyperfine parameters isomer shift and magnetic hyperfine fields, were obtained from the calculations. For FM Fe50Ni50, the effect of pressure on the hyperfine field and on the isomer shift was investigated, for three different local atomic configurations surrounding the 57Fe probe atom. In the case of the isomer shift, the calculated values were compared to reported experimental data. 相似文献
2.
Ancély F. dos Santos Daria Raquel Q. de Almeida Letícia F. Terra Rosangela A.M. Wailemann Vinícius M. Gomes Gabriel S. Arini Felipe G. Ravagnani Maurício S. Baptista Leticia Labriola 《Photochemistry and photobiology》2020,96(3):658-667
Photodynamic therapy (PDT) appears as a promising alternative in the treatment of breast cancer since it can be highly effective in curing cancer while preserving normal tissue. However, predicting outcomes in PDT still constitutes a great challenge. One of the parameters that are usually empirically determined is the rate of photon flux delivered to the tissue (light fluence rate). In the present study, we intended to understand why monolayers of human cells derived from mammary adenocarcinomas (MDA-MB-231 and MCF-7) respond quite differently to fluence rates (cells were irradiated either for 6 or for 16 min) at a fixed light dose (4.5 J cm−2) delivered with an array of LEDs in a typical methylene blue PDT protocol. While death rates of MDA-MB-231 cells were insensitive to the fluence rate, MCF-7 cells showed a quite impressive (three times) decrease in cell death levels in the shorter irradiation protocol. Independent on cell type cell death was invariably correlated with the depletion of reduced glutathione intracellular levels and consequently with widespread redox misbalance. Our data show the potential to optimize fluence rates to provide exhaustion of the cell antioxidant responses in order to circumvent therapy resistance of breast tumors. 相似文献
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4.
F. S. Terra 《Applied Physics A: Materials Science & Processing》1996,62(2):169-173
Thin copper-indium-disulphide films were prepared by thermal evaporation technique. X-ray diffraction analysis of the compound used for evaporation showed a tetragonal polycrystalline structure. Differential Thermal Analysis (DTA) of this compound showed two exothermic peaks at 585 and 632 °C. Thin films with thicknesses of 0.14 and 0.27 nm have a deposition rate 10 nm/min, while those with thicknesses of 0.54 and 0.56 nm have a deposition rate 48 nm/min. The obtained films have polycrystalline structure as shown from the electron diffraction study. A growth process was detected in the films by transmission electron microscopy as the film thickness increases. The surface topography was revealed by scanning electron microscopy. The variations of Hall mobility and carrier concentration with magnetic induction were studied. The resistivity-temperature relationship was investigated, from which the activation energies before and after annealing were found to be 0.2, 0.3 and 0.055 eV, respectively. 相似文献
5.
Ellis DE Terra J Warschkow O Jiang M González GB Okasinski JS Bedzyk MJ Rossi AM Eon JG 《Physical chemistry chemical physics : PCCP》2006,8(8):967-976
Characterization of lead substitution for calcium in hydroxyapatite (CaHA) is carried out, using experimental techniques and Density Functional theoretical (DFT) analyses. Theoretical modeling is used to obtain information of the Pb chemical environment for occupancy at either Ca(I) or Ca(II) sites of CaHA. Effects of the larger ionic radius of Pb(+2) compared to Ca(+2) are apparent in embedded cluster calculations of local chemical bonding properties. DFT periodic planewave pseudopotential studies are used to provide first-principles predictions of local structural relaxation and site preference for Pb(x)Ca(10-x)HA over the composition range x< or = 6. General characteristics of the polycrystalline material are verified by X-ray diffraction and FTIR analysis, showing the presence of a single phase of CaHA structure. A short range structure around lead is proposed in order to interpret the Pb L-edge EXAFS spectrum of the solid solution Ca(6.6)Pb(3.4)HA. In this concentration we observe that lead mainly occupies Ca(II) sites; the EXAFS fit slightly favors Pb clustering, while theory indicates the importance of Pb-Pb avoidance on site (II). 相似文献
6.
n-Type indium antimonide-Au hybrid macro-structure was successfully fabricated on p-GaAs substrate by a simple and economic
flash evaporation technique. The elemental composition of the prepared InSb film was confirmed by energy dispersive X-ray
spectroscopy microanalysis (EDX). The surface topography and crystal structure of the InSb film was characterized by scanning
electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The magnetoresistance of the prepared hybrid macro-structure
was measured and discussed in terms of the model of current redistribution. 相似文献
7.
Production of Cellulolytic Enzymes by <Emphasis Type="Italic">Aspergillus phoenicis</Emphasis> in Grape Waste using Response Surface Methodology 总被引:1,自引:0,他引:1
Dedavid e Silva LA Lopes FC Silveira ST Brandelli A 《Applied biochemistry and biotechnology》2009,152(2):295-305
The production of cellulolytic enzymes by the fungus Aspergillus phoenicis was investigated. Grape waste from the winemaking industry was chosen as the growth substrate among several agro-industrial
byproducts. A 2 × 2 central composite design was performed, utilizing the amount of grape waste and peptone as independent
variables. The fungus was cultivated in submerged fermentation at 30 °C and 120 rpm for 120 h, and the activities of total
cellulases, endoglucanases, and β-glucosidases were measured. Total cellulases were positively influenced by the linear increase
of peptone concentration and decrease at axial concentrations of grape waste and peptone. Maximum activity of endoglucanase
was observed by a linear increase of both grape waste and peptone concentrations. Concentrations of grape waste between 5
and 15 g/L had a positive effect on the production of β-glucosidase; peptone had no significant effects. The optimum production
of the three cellulolytic activities was observed at values near the central point. A. phoenicis has the potential for the production of cellulases utilizing grape waste as the growth substrate. 相似文献
8.
Moura Edmilson M. Terra Vilma R. Siebald Helmuth G. L. de Lima Geraldo M. Paim Lilian A. Dias Fabrícia M. 《Transition Metal Chemistry》2003,28(4):437-442
A series of heterobimetallic complexes containing Ru–Sn bonds, of general formula [RuCp(L)2SnX2Y] [L = PPh3, 1/2 dppe = 1,2-bis(diphenylphosphino)ethane; X, Y = F, Cl and Br], was prepared and studied by elemental analysis, 119Sn-Mössbauer spectroscopy, i.r. and 1H-, 13C-, 19F-, 31P- and 119Sn-n.m.r. spectroscopy. 119Sn-Mössbauer studies allowed determination of the coordination number of the SnII center as well as the group electronegativity of the organometallic fragment [RuCp(L)2]+. These results, supported by multinuclear n.m.r. data suggested that the electronic charge distribution between the RuII and SnII centers are strongly dependant upon the nature of L and the electronegativity of X and Y. 相似文献
9.
I.A.A. Terra L.J. Borrero-González T.R. Figueredo J.M.P. Almeida A.C. Hernandes L.A.O. Nunes O.L. Malta 《Journal of luminescence》2012,132(7):1678-1682
The down-conversion process in Tb3+–Yb3+ co-doped Calibo glasses was studied. The emission, excitation and time-resolved measurements indicated the existence of an energy conversion through the excitation of Tb3+ ions to near-infrared emission by Yb3+ ions. The emission intensity dependence on excitation power confirms that the one-photon process is responsible for the Yb3+ emission. An enhanced Yb3+ emission was observed with Yb3+ doping and an optimal energy transfer efficiency of 32% was obtained before reaching near-infrared emission quenching. The mechanism of the non-resonant energy transfer from Tb3+ to Yb3+ is discussed in terms of the Tb3+–Yb3+ cross-relaxation and multiphonon decay processes. 相似文献
10.
We generalize the theory of Kobayashi and Oliva (On the Birkhoff Approach to Classical Mechanics. Resenhas do Instituto de Matemática e Estatística da Universidade de São Paulo, 2003) to infinite dimensional Banach manifolds with a view towards applications in partial differential equations. 相似文献