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31.
Städler B Falconnet D Pfeiffer I Höök F Vörös J 《Langmuir : the ACS journal of surfaces and colloids》2004,20(26):11348-11354
We present a novel concept for the creation of lipid vesicle microarrays based on a patterning approach termed Molecular Assembly Patterning by Lift-off (MAPL). A homogeneous MAPL-based single-stranded DNA microarray was converted into a vesicle array by the use of vesicles tagged with complementary DNAs, permitting sequence-specific coupling of vesicles to predefined surface regions through complementary DNA hybridization. In the multistep process utilized to fulfill this achievement, active spots consisting of PLL-g-PEGbiotin with a resistant PLL-g-PEG background, as provided by the MAPL process, was converted into a DNA array by addition of complexes of biotin-terminated DNA and NeutrAvidin. This was then followed by addition of POPC vesicles tagged with complementary cholesterol-terminated DNA, thus providing specific coupling of vesicles to the surface through complementary DNA hybridization. Quartz crystal microbalance with dissipation (QCM-D) and optical waveguide lightmode spectroscopy monitoring were used to optimize the multistep surface modification process. It was found that the amount of adsorbed biotinDNA-NeutrAvidin complexes decreases with increasing molar ratio of biotinDNA to NeutrAvidin and decreasing ionic strength of the buffer solution. Modeling of the QCM-D data showed that the shape of the immobilized vesicles depends on the amount of available anchoring groups between the vesicles and the surface. Fluorescent microscopy images confirmed the possibility to create well-defined patterns of DNA-tagged, fluorescently labeled vesicles in the micrometer range. 相似文献
32.
Dalla Serra M Coraiola M Viero G Comai M Potrich C Ferreras M Baba-Moussa L Colin DA Menestrina G Bhakdi S Prévost G 《Journal of chemical information and modeling》2005,45(6):1539-1545
Staphylococcal gamma-hemolysins are bicomponent toxins forming a protein family with leucocidins and alpha-toxin. Two active toxins (AB and CB) can be formed combining one of the class-S components, HlgA or HlgC, with the class-F component HlgB. These two gamma-hemolysins form pores with marked similarities to alpha-toxin in terms of conductance, nonlinearity of the current-voltage curve, and channel stability in the open state. AB and CB pores, however, are cation-selective, whereas alpha-toxin is anion-selective. gamma-Hemolysins' pores are hetero-oligomers formed by three or four copies of each component (indicated as 3A3B and 3C3B or 4A4B and 4C4B). Point mutants located on a beta-strand of the class-S component that forms part of the protomer-protomer contact region can prevent oligomer assembly. Interestingly, these mutants inhibit growth of pores formed not only by their natural components but also by nonstandard components. This lead to the hypothesis that mixed ABC pores could also be formed. By studying the conductance of pores, assembled in the presence of all three components (in different ratios), it was observed that the magnitudes expected for mixed pores were, indeed, present. We conclude that the gamma-hemolysin/leucocidin bicomponent toxin family may form a larger than expected number of active toxins by cross-combining various S and F components. 相似文献
33.
A study on the synthesis of La1−xAgxMnO3+δ (x = 0, 0.2) using a microwave process (MWhyd) has been carried out by comparing the heating time and reaction temperature with the same factor under conventional thermal process (CHhyd). Experiments have been conducted using the hydrothermal method at medium pressure (T = 200 °C, P = 20 atm) followed by a thermal treatment of the precursor at 700 °C (10 h).Structural and physico-chemical properties of the catalysts were investigated using X-ray diffraction (XRD), BET sorption, temperature-programmed reduction or desorption, mass spectrometry (TPR-MS and TPD-MS), and X-ray photoelectron spectroscopy (XPS). While CHhyd and MWhyd powder catalysts exhibited the same XRD patterns indexed as pure perovskite structure, their surface physico-chemical properties were found to be strongly influenced by the preparation method. The effect of the nature of oxygen species, their amount and mobility, evidenced by temperature programmed experiments, on the catalytic properties in methane combustion in the presence and in the absence of hydrogen sulphide has been studied. MWhyd-La0.8Ag0.2MnO3+δ catalysts were found to exhibit a much better performance in methane combustion together with higher resistance to sulphur poisoning than CHhyd catalysts. 相似文献
34.
Li M Bonnet D Bill E Neese F Weyhermüller T Blum N Sellmann D Wieghardt K 《Inorganic chemistry》2002,41(13):3444-3456
Two new pentadentate, pendent arm macrocyclic ligands of the type 1-alkyl-4,7-bis(4-tert-butyl-2-mercaptobenzyl)-1,4,7-triazacyclononane where alkyl represents an isopropyl, (L(Pr))(2-), or an ethyl group, (L(Et))(2-), have been synthesized. It is shown that they bind strongly to ferric ions generating six-coordinate species of the type [Fe(L(alk))X]. The ground state of these complexes is governed by the nature of the sixth ligand, X: [Fe(III)(L(Et))Cl] (2) possesses an S = 5/2 ground state as do [Fe(III)(L(Et))(OCH(3))] (3) and [Fe(III)(L(Pr))(OCH(3))] (4). In contrast, the cyano complexes [Fe(III)(L(Et))(CN)] (5) and [Fe(III)(L(Pr))(CN)] (6) are low spin ferric species (S = 1/2). The octahedral [FeNO](7) nitrosyl complex [Fe(L(Pr))(NO)] (7) displays spin equilibrium behavior S = 1/2<==>S = (3)/(2) in the solid state. Complexes [Zn(L(Pr))] (1), 4.CH(3)OH, 5.0.5toluene.CH(2)Cl(2), and 7.2.5CH(2)Cl(2) have been structurally characterized by low-temperature (100 K) X-ray crystallography. All iron complexes have been carefully studied by zero- and applied-field M?ssbauer spectroscopy. In addition, Sellmann's complexes [Fe(pyS(4))(NO)](0/1+) and [Fe(pyS(4))X] (X = PR(3), CO, SR(2)) have been studied by EPR and M?ssbauer spectroscopies and DFT calculations (pyS(4) = 2,6-bis(2-mercaptophenylthiomethyl)pyridine(2-)). It is concluded that the electronic structure of 7 with an S = 1/2 ground state is low spin ferrous (S(Fe) = 0) with a coordinated neutral NO radical (Fe(II)-NO) whereas the S = 3/2 state corresponds to a high spin ferric (S(Fe) = 5/2) antiferromagnetically coupled to an NO(-) anion (S = 1). The S = 1/2<==>S = 3/2 equilibrium is then that of valence tautomers rather than that of a simple high spin<==>low spin crossover. 相似文献
35.
36.
We report six-dimensional quantum dynamics calculations of the dissociative scattering of molecular hydrogen from the copper111 surface. Two potential energy surfaces are investigated and the results are compared with experiment. Our study completes the preliminary work of Somers et al. [Chem. Phys. Lett. 360, 390 (2002)] and focuses on the role of initial vibrational excitation and on isotopic effects. None of the two investigated potential energy surfaces is found satisfactory: the use of neither potential yields reaction and vibrational excitation probabilities and vibrational efficacies that are in close agreement with experiment. In addition to showing the shortcomings of existing potential energy surfaces we point out an inconsistency in the experimental fits for D2. 相似文献
37.
A general approach to information correction and fusion for belief functions is proposed, where not only may the information items be irrelevant, but sources may lie as well. We introduce a new correction scheme, which takes into account uncertain metaknowledge on the source’s relevance and truthfulness and that generalizes Shafer’s discounting operation. We then show how to reinterpret all connectives of Boolean logic in terms of source behavior assumptions with respect to relevance and truthfulness. We are led to generalize the unnormalized Dempster’s rule to all Boolean connectives, while taking into account the uncertainties pertaining to assumptions concerning the behavior of sources. Eventually, we further extend this approach to an even more general setting, where source behavior assumptions do not have to be restricted to relevance and truthfulness. We also establish the commutativity property between correction and fusion processes, when the behaviors of the sources are independent. 相似文献
38.
Maillard Christophe Maloubier Didier Boulay Olivier Savigny Victor Quemet Alexandre 《Journal of Radioanalytical and Nuclear Chemistry》2021,330(3):579-587
Journal of Radioanalytical and Nuclear Chemistry - Due to unexpected Pu behavior using the U/TEVA resin and the most-recognized reagents, some key separation stages need to be studied for the... 相似文献
39.
Didier Lesesvre Paul Pegon Filippo Santambrogio 《Set-Valued and Variational Analysis》2013,21(3):541-556
The main result of this paper is the existence of an optimal transport map T between two given measures μ and ν, for a cost which considers the maximal oscillation of T at scale δ, given by ω δ (T) :?=??sup|x???y|?<?δ |T(x)???T(y)|. The minimization of this criterion finds applications in the field of privacy-respectful data transmission. The existence proof unfortunately only works in dimension one and is based on some monotonicity considerations. 相似文献
40.