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191.
The aim of this paper is to present an algorithm for finding a saddle point to the constrained minimax problem. The initial problem is transformed into an equivalent equality constrained problem, and then the interior point approach is used. To satisfy the original inequality constraints a logarithmic barrier function is used and special care is given to step size parameter to keep the variables within permitted boundaries. Numerical results illustrating the method are given. 相似文献
192.
Maria Farsari George Filippidis Kyriaki Sambani Savas Georgiou Electra Gizeli Costas Fotakis 《Applied Surface Science》2007,253(19):8115-8118
A new method is demonstrated, where three-dimensional protein structures are made by employing multi-photon polymerization and photobiotin photolysis. The technique enables the construction of arbitrary two- and three-dimensional shapes with submicron resolution. The integrity of the immobilized biotin is confirmed by derivatization with fluorescently labeled streptavidin. Fluorescence microscopy is used in order to visualize the distribution of fluorescent streptavidin on the 3D structure. 相似文献
193.
M. Lassithiotaki A. Athanassiou D. Anglos S. Georgiou C. Fotakis 《Applied Physics A: Materials Science & Processing》1999,69(3):363-367
0 ∝t1/2. The best results are expected for a circular top-hat beam shape.
Received: 15 January 1999 / Accepted: 18 January 1999 相似文献
194.
195.
Natassa Pippa Konstantinos Gardikis Stergios Pispas Costas Demetzos 《Journal of Thermal Analysis and Calorimetry》2014,116(1):99-105
The aim of this work is to study the morphological characteristics via fractal analysis and the alterations of the thermotropic behavior of dipalmitoylphosphatidylcholine (DPPC) liposomes, caused by the incorporation of cholesterol, poly(amidoamine) (PAMAM) dendrimer, and MPOx (poly(2-methyl-2-oxazoline)-grad-poly(2-phenyl-2-oxazoline)) gradient block copolymer (9:1 molar ratio). A gamut of light scattering techniques and differential scanning calorimetry were used in order to extract information on the morphological (in different dispersion media) and thermodynamic characteristics of liposomal drug nanocarriers, respectively. The vesicles’ structure of liposomes has a different thermodynamic content, which corresponds to a different thermotropic behavior, in comparison to pure lipid bilayers. The observed metastable phase only for DPPC liposomes has been considered as a “physical impurity”, which leads to “physical incompatibility” and consequently promotes the aggregation of DPPC liposomes in aqueous media. The incorporation of biomaterials such as PAMAM G4 and MPOx, caused alterations in the thermotropic behavior of DPPC liposomes affecting only the main transition specific enthalpy ΔH. All the other calorimetric parameters remained unaltered. These findings supported the hypothesis that the exceptional stability and transition cooperativity of the chimeric liposomal membrane might be due to the reduction of the vesicle size with the smaller membrane curvature that is indicated by the fractal dimensionality of the system. In conclusion, the results from the thermal analysis of the liposomal systems were in line with the picture of their structural characteristics, as indicated by the interplay between physicochemical and thermodynamical parameters, which determines their fractal morphology. 相似文献
196.
Junhang Dong Valmor F. de Almeida Costas Tsouris 《Journal of Dispersion Science and Technology》2013,34(1-3):155-166
In this work, coalescence of a single organic or aqueous drop with its homophase at a horizontal liquid interface was investigated under applied electric fields. The coalescence time was found to decrease for aqueous drops as the applied voltage was increased, regardless of the polarity of the voltage. For organic drops, the coalescence time increased with increasing applied voltage of positive polarity and decreased with increasing applied voltage of negative polarity. Under an electric field, the coalescence time of aqueous drops decreases due to polarization of both the drop and the flat interface. The dependency of organic drop-interface coalescence on the polarity of the electric field may be a result of the negatively charged organic surface in the aqueous phase. Due to the formation of a double layer, organic drops are subjected to an electrostatic force under an electric field, which, depending on the field polarity, can be attractive or repulsive. Pair-drop coalescence of aqueous drops in the organic phase was also studied. Aqueous drop-drop coalescence is facilitated by polarization and drop deformation under applied electric fields. Without applied electric fields, drop deformation increases the drainage time of the liquid film between two approaching drops. Therefore, a decrease in the interfacial tension, which causes drop deformation, accelerates drop-drop coalescence under an electric field and inhibits drop coalescence in the absence of an electric field. 相似文献
197.
YanFeng Yue XiaoGuang Sun Richard T. Mayes Jungseung Kim Pasquale F. Fulvio ZhenAn Qiao Suree Brown Costas Tsouris Yatsandra Oyola Sheng Dai 《中国科学:化学(英文版)》2013,56(11):1510-1515
Polymer-coated mesoporous carbon nanocomposites were prepared from the immobilization of acrylonitrile and acrylic acid copolymers with divinylbenzene as a crosslinker onto a mesoporous carbon framework. High surface areas were maintained after polymerization with accessible porosity. This functional nanocomposite was tested as an adsorbent for uranium from high salinity solutions. Uranium adsorption results have shown that the adsorption capacities are strongly influenced by the density of the amidoxime groups and the specific surface area. 相似文献
198.
Zoel Codolà João M. S. Cardoso Dr. Beatriz Royo Dr. Miquel Costas Dr. Julio Lloret‐Fillol 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(22):7203-7213
Exceptional water oxidation (WO) turnover frequencies (TOF=17 000 h?1), and turnover numbers (TONs) close to 400 000, the largest ever reported for a metal‐catalyzed WO reaction, have been found by using [Cp*IrIII(NHC)Cl2] (in which NHC=3‐methyl‐1‐(1‐phenylethyl)‐imidazoline‐2‐ylidene) as the pre‐catalyst and NaIO4 as oxidant in water at 40 °C. The apparent TOF for [Cp*IrIII(NHC)X2] ( 1 X , in which X stands for I ( 1 I ), Cl ( 1 Cl ), or triflate anion ( 1 OTf )) and [(Cp*‐NHCMe)IrIIII2] ( 2 ) complexes, is kept constant during almost all of the O2 evolution reaction when using NaIO4 as oxidant. The TOF was found to be dependent on the ligand and on the anion (TOF ranging from ≈600 to ≈1100 h?1 at 25 °C). Degradation of the complexes by oxidation of the organic ligands upon reaction with NaIO4 has been investigated. 1H NMR, ESI‐MS, and dynamic light‐scattering measurements (DLS) of the reaction medium indicated that the complex undergoes rapid degradation, even at low equivalents of oxidant, but this process takes place without formation of nanoparticles. Remarkably, three‐month‐old solution samples of oxidized pre‐catalysts remain equally as active as freshly prepared solutions. A UV/Vis feature band at λmax=405 nm is observed in catalytic reaction solutions only when O2 evolves, which may be attributed to a resting state iridium speciation, most probably Ir–oxo species with an oxidation state higher than IV. 相似文献
199.
Self-Assembling Peptides and Carbon Nanomaterials Join Forces for Innovative Biomedical Applications
Self-assembling peptides and carbon nanomaterials have attracted great interest for their respective potential to bring innovation in the biomedical field. Combination of these two types of building blocks is not trivial in light of their very different physico-chemical properties, yet great progress has been made over the years at the interface between these two research areas. This concise review will analyze the latest developments at the forefront of research that combines self-assembling peptides with carbon nanostructures for biological use. Applications span from tissue regeneration, to biosensing and imaging, and bioelectronics. 相似文献
200.
Jeon H Schmidt R Barton JE Hwang DJ Gamble LJ Castner DG Grigoropoulos CP Healy KE 《Journal of the American Chemical Society》2011,133(16):6138-6141
We applied 2-photon laser ablation to write subdiffraction nanoscale chemical patterns into ultrathin polymer films under ambient conditions. Poly(ethylene glycol) methacrylate brush layers were prepared on quartz substrates via surface-initiated atom-transfer radical polymerization and ablated to expose the underlying substrate using the nonlinear 2-photon absorbance of a frequency-doubled Ti:sapphire femtosecond laser. Single-shot ablation thresholds of polymer films were ~1.5 times smaller than that of a quartz substrate, which allowed patterning of nanoscale features without damage to the underlying substrate. At a 1/e(2) laser spot diameter of 0.86 μm, the features of exposed substrate approached ~80 nm, well below the diffraction limit for 400 nm light. Ablated features were chemically distinct and amenable to chemical modification. 相似文献