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11.
12.
F. Sima P. Davidson E. Pauthe O. Gallet K. Anselme I. N. Mihailescu 《Applied Physics A: Materials Science & Processing》2011,105(3):611-617
We report on matrix-assisted pulsed laser evaporation (MAPLE) transfer of intact and functional protein molecules from a cryogenic
aliquot obtained by freezing a protein-saline buffer solution. Vitronectin (Vn), an extracellular matrix protein with distinctive
active domains for cell attachment and signalization, was expelled from frozen targets by KrF* excimer laser irradiation,
and then immobilized on substrates. Particulates surrounded by a dense matrix were observed by optical, profilometry and AFM
studies. The composition preservation of MAPLE-deposited protein films versus drop-cast films was demonstrated by FTIR and
immunostaining studies. The stability and integrity of Vn after transfer was shown by their interaction with human osteoprogenitor
cells in which actin filaments stretched across the entire cell area and clear focal points with surface were formed. The
absence of detectable degradation of protein structure after MAPLE immobilization could provide benefits to surface functionalization
for biomedical applications. 相似文献
13.
A. Stanculescu M. Socol G. Socol I. N. Mihailescu M. Girtan F. Stanculescu 《Applied Physics A: Materials Science & Processing》2011,104(3):921-928
In this study, we present the deposition of ZnPc, Alq3, and PTCDA thin films using Matrix Assisted Pulsed Laser Evaporation
(MAPLE) technique. We also report the realisation of multilayer structures, made by the successive application of MAPLE. The
films have been characterized by spectroscopic (UV–VIS and Photoluminescence) and microscopic (SEM and AFM) methods, and the
effect of different deposition conditions such as fluence, number of pulses, and target concentration on the properties has
been analysed. This paper also presents some investigations on the electrical conduction in sandwich type structures ITO or
Si/organic layer/Au or Cu and ITO/double organic layer/Cu, emphasising the dominant effect of the height of the energetic
barriers at the inorganic/organic and organic/organic interfaces. 相似文献
14.
A new design of the U-type resonator is described. In this way, a laser beam with symmetrical intensity profile (regarding to a symmetry plane) can be extracted from an active medium that exhibits gain asymmetry along one of the transverse directions. The whole area of the active medium cross-section can be used, and consequently the laser efficiency will be increased. This resonator structure was applied for efficiency power extraction (as a low order TEM modes laser beam) from a DC excited transverse flow CO2 laser with cylindrical geometry. Although the cross-section area of the discharge was entirely used (including the cathode fall region), a symmetrical intensity profile of the laser beam (regarding to the two orthogonal symmetry planes) was obtained in the near field as well as in the far field; the gain asymmetry along the flow direction was compensated by the gas circulation fluidodynamical circuit with two counterflowing discharge channels. A double-U optical resonator was introduced in order to provide a laser beam with axial symmetry.For the practical construction of these two types of optical resonators we have developed two new types of 90° deflection elements: the first one, which does not reverse the image (and which has the properties of the pentaprism), and the second one, which rotates the image with 90° angle. Both elements exhibit good focusability if they are equipped with two concave mirrors. 相似文献
15.
16.
C. Ristoscu E. Gyorgy I.N. Mihailescu A. Klini V. Zorba C. Fotakis 《Applied Physics A: Materials Science & Processing》2004,79(4-6):927-929
AlN thin films with a thickness in the nanometer range were prepared by pulsed laser deposition technique. We investigated the effect of laser wavelength, pulse duration, and ambient gas pressure on the composition and morphology of the deposited films. In all experiments we used AlN targets. We worked with three laser sources generating pulses of 34 ns@248 nm (source A), 450 fs@248 nm (source B), and 50 fs@800 nm (source C). XRD, SEM, and profilometric measurements were performed on the obtained AlN thin films. We have demonstrated that duration of the laser pulse is an important parameter for the quality and performances of AlN structures obtained by pulsed laser deposition. PACS 81.05.Ea; 81.15.Fg; 61.10.Nz 相似文献
17.
R. Alexandrescu J. Morjan C. Grigoriu I. N. Mihailescu Z. Bastl J. Tlaskal R. Mayer J. Pola 《Applied Physics A: Materials Science & Processing》1988,46(4):275-279
Infrared multiphoton decomposition of monosilane in the presence of methyl methacrylate results in the formation of gaseous methane, acetylene, butenes and carbon monoxide along with a solid polymer whose chemical mechanism of formation is discussed in line of the poly(dimethylsiloxane) structure inferred from ESCA and IR spectral analysis. 相似文献
18.
C. Berbecaru H.V. Alexandru A. Popescu G. Socol F. Sima Ion Mihailescu 《Applied Surface Science》2009,255(10):5476-5479
Pulsed laser deposition (PLD) method was used to obtain bioglass (BG) thin film coatings on titanium substrates. An UV excimer laser KrF* (λ = 248 nm, τ = 25 ns) was used for the multi-pulse irradiation of the BG targets with 57 or 61 wt.% SiO2 content (and Na2O-K2O-CaO-MgO-P2O5 oxides). The depositions were performed in oxygen atmosphere at 13 Pa and for substrates temperature of 400 °C. The PLD films displayed typical BG of 2-5 μm particulates nucleated on the film surface or embedded in. The PLD films stoichiometry was found to be the same as the targets. XRD spectra have shown, the glass coatings obtained, had an amorphous structure. One set of samples, deposited in the same conditions, were dipped in simulated body fluids (SBFs) and subsequently extracted one by one after several time intervals 1, 3, 7, 14 and 21 days. After washing in deionized water and drying, the surface morphology of the samples and theirs composition were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), IR spectroscopy (FTIR) and energy dispersive X-ray analysis (EDX). After 3-7 days the Si content substantially decreases in the coatings and PO43− maxima start to increase in FTIR spectra. The XRD spectra also confirm this evolution. After 14-21 days the XRD peaks show a crystallized fraction of the carbonated hydroxyapatite (HAP). The SEM micrographs show also significant changes of the films surface morphology. The coalescence of the BG droplets can be seen. The dissolution and growth processes could be assigned to the ionic exchange between BG and SBFs. 相似文献
19.
Carmen Moldovan Carmen Mihailescu Dana Stan Lavinia Ruta Rodica Iosub Raluca Gavrila Munizer Purica Schiopu Vasilica 《Applied Surface Science》2009,255(22):8953-8959
This article presents the characterization of two substrates, silicon and polymer coated with gold, that are functionalized by mixed self-assembled monolayers (SAMs) in order to efficiently immobilize the anti-Escherichia coli O157:H7 polyclonal purified antibody.A biosurface functionalized by SAMs (self-assembled monolayers) technique has been developed. Immobilization of goat anti-E. coli O157:H7 antibody was performed by covalently bonding of thiolate mixed self-assembled monolayers (SAMs) realized on two substrates: polymer coated with gold and silicon coated with gold. The F(ab′)2 fragments of the antibodies have been used for eliminating nonspecific bindings between the Fc portions of antibodies and the Fc receptor on cells. The properties of the monolayers and the biofilm formatted with attached antibody molecules were analyzed at each step using infrared spectroscopy (FTIR-ATR), atomic force microscopy (AFM), scanning electron microscopy (SEM) and cyclic voltammetry (CV). In our study the gold-coated silicon substrates approach yielded the best results.These experimental results revealed the necessity to investigate each stage of the immobilization process taking into account in the same time the factors that influence the chemistry of the surface and the further interactions as well and also provide a solid basis for further studies aiming at elaborating sensitive and specific immunosensor or a microarray for the detection of E. coli O157:H7. 相似文献
20.
Maria Mernea Octavian Calborean Oana Grigore Traian Dascalu Dan Florin Mihailescu 《Optical and Quantum Electronics》2014,46(4):505-514
Terahertz (THz) spectroscopy is a promising technique for the study of protein structure and internal flexibility. Here, we used THz spectroscopy and molecular modeling for bovine serum albumin (BSA) structure investigation. BSA molecule was built using homology modeling methods and 30 different more relaxed models were obtained by molecular dynamics simulations of the hydrated protein. As the experimental and simulated THz spectra are linear, we compared them by comparing the slopes of the lines that fit them. Six BSA structures had slope values in the range given by the slope of the experimental spectrum $\pm $ 0.2 and a total of sixteen BSA structures had slope values in the 0.6 interval near the experimental slope value. BSA average structures were calculated over the six and the sixteen identified BSA molecules. Based on the similarity with the crystal structure of BSA, we validated the average structure calculated over the sixteen BSA conformations. The comparison with the crystal structure showed that the structure validated using THz spectroscopy is a coarse model of BSA, as its root-mean-square deviation relative to the crystal structure is 1.9 Å. The regions from our model that present the highest deviation from the crystal structure are exterior loops. The results presented here show that using THz spectroscopy and molecular modeling is a promising approach to determine the structure of proteins. 相似文献