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51.
We present an all-electron method for time-dependent density functional theory which employs hierarchical nonuniform finite-element bases and the time-propagation approach. The method is capable of treating linear and nonlinear response of valence and core electrons to an external field. We also introduce (i) a preconditioner for the propagation equation, (ii) a stable way to implement absorbing boundary conditions, and (iii) a new kind of absorbing boundary condition inspired by perfectly matched layers. 相似文献
52.
Dongfei Liu Ermei Mäkilä Hongbo Zhang Barbara Herranz Martti Kaasalainen Päivi Kinnari Jarno Salonen Jouni Hirvonen Hélder A. Santos 《Advanced functional materials》2013,23(15):1893-1902
A major bottleneck in nanometer‐scale drug delivery systems is the fabrication of nanocarriers with excellent stability under physiological conditions that can both efficiently encapsulate therapeutic agents and controllably release their payloads. Herein, the formation of a novel nanocomposite based on the encapsulation of thermally hydrocarbonized porous silicon (THCPSi) nanoparticles with solid lipid nanoparticles (SLNs) on a 1:1 ratio is described. The THCPSi‐SL nanocomposites (THCPSi‐SLNCs) are formed using a solid‐in‐oil‐in‐water emulsion solvent evaporation method. TEM and FTIR analyses prove that THCPSi nanoparticles are successfully encapsulated in the SLN matrix. The formation of the THCPSi‐SLNCs alters the surface smoothness and hydrophobicity of the THCPSi nanoparticles, and also remarkably enhances their stability in human plasma. After encapsulation, the cytocompatibility of the THCPSi nanoparticles with intestinal, liver, and macrophage cancer cells is also greatly improved. A prolonged release of the model drug, furosemide, from THCPSi‐SLNC is achieved, indicating that the SLN matrix successfully seals the pores of the THCPSi nanoparticles. Flow cytometry and confocal fluorescence microscopy studies demonstrates the significantly reduced cellular association of THCPSi‐SLNCs with the cells comparing to bare THCPSi nanoparticles. Overall, the THCPSi‐SLNCs exhibits superior suspensibility and better stability against aggregation in aqueous buffer solutions, increases the particle surface smoothness and cytocompatibility, reduces the cellular association, increases the in vitro stability in human plasma, and prolonges the drug release. These results suggest that the nanocomposite is a promising nanovector system for drug delivery applications. 相似文献
53.
Harry Alles Jaan Aarik Aleks Aidla Aurelien Fay Jekaterina Kozlova Ahti Niilisk Martti Pärs Mihkel Rähn Maciej Wiesner Pertti Hakonen Väino Sammelselg 《Central European Journal of Physics》2011,9(2):319-324
Atomic layer deposition of HfO2 on unmodified graphene from HfCl4 and H2O was investigated. Surface RMS roughness down to 0.5 nm was obtained for amorphous, 30 nm thick hafnia film grown at 180°C. HfO2 was also deposited in a two-step temperature process where the initial growth of about 1 nm at 170°C was continued up to 10–30 nm at 300°C. This process yielded uniform, monoclinic HfO2 films with RMS roughness of 1.7 nm for 10–12 nm thick films and 2.5 nm for 30 nm thick films. Raman spectroscopy studies revealed that the deposition process caused compressive biaxial strain in graphene, whereas no extra defects were generated. An 11 nm thick HfO2 film deposited onto bilayer graphene reduced the electron mobility by less than 10% at the Dirac point and by 30–40% far away from it. 相似文献
54.
Pier Paolo Giardino Kristjan Kannike Martti Raidal Alessandro Strumia 《Physics letters. [Part B]》2012
The recently discovered resonance at 125 GeV has properties remarkably close to those of the Standard Model Higgs boson. We perform model-independent fits of all presently available data. The non-standard best-fits found in our previous analyses remain favored with respect to the SM fit, mainly but not only because the γγ rate remains above the SM prediction. 相似文献
55.
Matti Heikinheimo Antonio Racioppi Martti Raidal Christian Spethmann Kimmo Tuominen 《Nuclear Physics B》2013
We propose a model of Dark Supersymmetry, where a supersymmetric dark sector is coupled to the classically scale invariant non-supersymmetric Standard Model through the Higgs portal. The dark sector contains a mass scale that is protected against radiative corrections by supersymmetry, and the portal coupling mediates this scale to the Standard Model, resulting in a vacuum expectation value for the Higgs field and the usual electroweak symmetry breaking mechanism. The supersymmetric dark sector contains dark matter candidates, and we show that the observed dark matter abundance is generated for a natural choice of parameters, while avoiding the current experimental bounds on direct detection. Future experiments can probe this scenario if the dark sector mass scale is not too high. 相似文献
56.
57.
Ahti Niilisk Mart Moppel Martti Pärs Ilmo Sildos Taavi Jantson Tea Avarmaa Raivo Jaaniso Jaan Aarik 《Central European Journal of Physics》2006,4(1):105-116
The Raman spectroscopy method was used for structural characterization of TiO2 thin films prepared by atomic layer deposition (ALD) and pulsed laser deposition (PLD) on fused silica and single-crystal
silicon and sapphire substrates. Using ALD, anatase thin films were grown on silica and silicon substrates at temperatures
125–425 °C. At higher deposition temperatures, mixed anatase and rutile phases grew on these substrates. Post-growth annealing
resulted in anatase-to-rutile phase transitions at 750 °C in the case of pure anatase films. The films that contained chlorine
residues and were amorphous in their as-grown stage transformed into anatase phase at 400 °C and retained this phase even
after annealing at 900 °C. On single crystal sapphire substrates, phase-pure rutile films were obtained by ALD at 425 °C and
higher temperatures without additional annealing. Thin films that predominantly contained brookite phase were grown by PLD
on silica substrates using rutile as a starting material. 相似文献
58.
Martti Tienari 《BIT Numerical Mathematics》1972,12(3):409-433
A result quantity in a numerical algorithm is considered as a function of the input data, roundoff and truncation errors. In order to investigate this functional relationship using the methods of mathematical analysis a structural model of the numerical algorithm calledR-automaton is introduced. It is shown that the functional dependence defined by anR-automaton is a continuous rational function in a neighborhood of any data point except in a point set, the Lebesgue measure of which is zero. An effective general-purpose algorithm is presented to compute the derivative of any result quantity with respect to the individual roundoff and truncation errors. Some ways of generalizing theR-automation model without losing the results achieved are finally suggested. 相似文献
59.
A problem on filter cake washing assuming a geometrical model of the pore spaces, in which axial dispersion occurs in the flow channel and mass transfer through a resistance is taking place from the cross channels to the flow channel, is solved by deriving the differential equations and the auxiliary conditions corresponding to the geometrical model and solving the mathematical problem utilizing the Laplace transform and a method for its numerical inversion that utilizes positive values of the transform variable. The numerical results are checked by comparison with asymptotic expansions and by recalculating the results utilizing other values of the transform variable. The results are presented both numerically with four significant figures and graphically. 相似文献
60.
Siltanen M Cattaneo S Vuorimaa E Lemmetyinen H Katz TJ Phillips KE Kauranen M 《The Journal of chemical physics》2004,121(1):1-4
We present a new technique, based on regression analysis, to determine the second-order nonlinear optical susceptibility tensor of thin films. The technique does not require the absolute levels or phases of measured signals to be mutually calibrated. In addition it yields indicators that address the quality of theoretical models describing the sample. We use the technique to determine the susceptibility tensor of samples of a nonracemic chiral material which have very low symmetry (both chiral and anisotropic) and have many independent tensor components. The results show the importance of using detailed theoretical models that account for the linear optical properties of the sample. 相似文献