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Search Results: 1 - 10 of 144441 matches for " Nadejda B. Matsko "
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Self-Sensing and –Actuating Probes for Tapping Mode AFM Measurements of Soft Polymers at a Wide Range of Temperatures  [PDF]
Nadejda B. Matsko, Julian Wagner, Anton Efimov, Ines Haynl, Stefan Mitsche, Wolfgang Czapek, Boris Matsko, Werner Grogger, Ferdinand Hofer
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.22012
Abstract: Self-sensing and –actuating probes optimized for conventional tapping mode atomic force microscopy (AFM) are described. 32-kHz quartz tuning forks with a chemically etched and focus ion beam (FIB) sharpened (curvature radii are 5-10 nm) tungsten tip are stable at air and liquid nitrogen atmosphere and at a wide range of temperatures. If driven at constant frequency, the scan speed of such sensors can be up to 3 Hz. AFM was performed on polymer samples in order to study the stability and applicability of these sensor for investigation of soft materials with high dynamical tendencies.
Analytical Electron Microscopy for Characterization of Fluid or Semi-Solid Multiphase Systems Containing Nanoparticulate Material
Victoria Klang,Claudia Valenta,Nadejda B. Matsko
Pharmaceutics , 2013, DOI: 10.3390/pharmaceutics5010115
Abstract: The analysis of nanomaterials in pharmaceutical or cosmetic preparations is an important aspect both in formulation development and quality control of marketed products. Despite the increased popularity of nanoparticulate compounds especially in dermal preparations such as emulsions, methods and protocols of analysis for the characterization of such systems are scarce. This work combines an original sample preparation procedure along with different methods of analytical electron microscopy for the comprehensive analysis of fluid or semi-solid dermal preparations containing nanoparticulate material. Energy-filtered transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron energy loss spectroscopy and high resolution imaging were performed on model emulsions and a marketed product to reveal different structural aspects of both the emulsion bulk phase and incorporated nanosized material. An innovative analytical approach for the determination of the physical stability of the emulsion under investigation is presented. Advantages and limitations of the employed analytical imaging techniques are highlighted.
Noise conversion in Kerr comb RF photonic oscillators
Andrey B. Matsko,Lute Maleki
Physics , 2014, DOI: 10.1364/JOSAB.32.000232
Abstract: Transfer of amplitude and phase noise from a continuous wave optical pump to the repetition rate of a Kerr frequency comb is studied theoretically, with focus on generation of spectrally pure radio frequency (RF) signals via demodulation of the frequency comb on a fast photodiode. It is shown that both the high order chromatic dispersion of the resonator spectrum and frequency-dependent quality factor of the resonator modes facilitate the optical-to-RF noise conversion that limits spectral purity of the RF signal.
Feshbach Resonances in Kerr Frequency Combs
Andrey B. Matsko,Lute Maleki
Physics , 2014, DOI: 10.1103/PhysRevA.91.013831
Abstract: We show that both the power and repetition rate of a frequency comb generated in a nonlinear ring resonator, pumped with continuous wave (cw) coherent light, are modulated. The modulation is brought about by the interaction of the cw background with optical pulses excited in the resonator, and occurs in resonators with nonzero high-order chromatic dispersion and wavelength-dependent quality factor. The modulation frequency corresponds to the detuning of the pump frequency from the eigenfrequency of the pumped mode in the resonator.
Semi-solid Sucrose Stearate-Based Emulsions as Dermal Drug Delivery Systems
Victoria Klang,Julia C. Schwarz,Nadejda Matsko,Elham Rezvani,Nivine El-Hagin,Michael Wirth,Claudia Valenta
Pharmaceutics , 2011, DOI: 10.3390/pharmaceutics3020275
Abstract: Mild non-ionic sucrose ester surfactants can be employed to produce lipid-based drug delivery systems for dermal application. Moreover, sucrose esters of intermediate lipophilicity such as sucrose stearate S-970 possess a peculiar rheological behavior which can be employed to create highly viscous semi-solid formulations without any further additives. Interestingly, it was possible to develop both viscous macroemulsions and fluid nanoemulsions with the same chemical composition merely by slight alteration of the production process. Optical light microscopy and cryo transmission electron microscopy (TEM) revealed that the sucrose ester led to the formation of an astonishing hydrophilic network at a concentration of only 5% w/w in the macroemulsion system. A small number of more finely structured aggregates composed of surplus surfactant were likewise detected in the nanoemulsions. These discoveries offer interesting possibilities to adapt the low viscosity of fluid O/W nanoemulsions for a more convenient application. Moreover, a simple and rapid production method for skin-friendly creamy O/W emulsions with excellent visual long-term stability is presented. It could be shown by franz-cell diffusion studies and in vitro tape stripping that the microviscosity within the semi-solid formulations was apparently not influenced by their increased macroviscosity: the release of three model drugs was not impaired by the complex network-like internal structure of the macroemulsions. These results indicate that the developed semi-solid emulsions with advantageous application properties are highly suitable for the unhindered delivery of lipophilic drugs despite their comparatively large particle size and high viscosity.
New Method to Generate Reversible Hydrophobic and Hydrophilic Surfaces
V. Mittal and N.B. Matsko
The Open Surface Science Journal , 2009, DOI: 10.2174/1876531900901010007]
Abstract: 7-12 Designer particles synthesized by surfactant-free emulsion polymerization were adsorbed successfully on the sapphire discs. The particles carried a thin layer of an atom transfer radical polymerization (ATRP) initiator on the surface and were subsequently successfully used to graft PNIPAAM brushes from the surface. The surface coverage of the discs by these particles could be improved by heat treatment of the discs which fused the particles with each other but keeping the initial ATRP layer on them. The reversible wetting characteristics of the surfaces as a function of temperature could be established by studying the behavior of water droplets placed on the PNIPAAM modified discs. The heat treated discs improved the reversible behavior further, though no superhydrophobic and superhydrophilic behavior could be achieved. The reversible temperature responsively makes these surfaces tremendously important for the commercial separation and filtration processes.
Induced Absorption Resonance on the Open Fg = 1 -> Fe = 2 Transition of the D1 Line of the 87Rb Atom
A. S. Zibrov,A. B. Matsko
Physics , 2005,
Abstract: Induced absorption resonance on the open Fg=1 -> Fe = 2 transition of the D1 line of the 87Rb atom has been observed. The effect of atomic motion on the formation of the resonance has been revealed. The numerical calculations are in good agreement with experiment.
Enabling Arbitrary Wavelength Optical Frequency Combs on Chip
Mohammad Soltani,Andrey B. Matsko,Lute Maleki
Physics , 2015,
Abstract: A necessary condition for generation of bright soliton Kerr frequency combs in microresonators is to achieve anomalous group velocity dispersion (GVD) for the resonator modes. This condition is hard to implement in visible as well as ultraviolet since the majority of optical materials are characterized with large normal GVD in these wavelength regions. We overcome this challenge by borrowing ideas from strongly dispersive coupled systems in solid state physics and optics. We show that photonic compound ring resonators can possess large anomalous GVD at any desirable wavelength, even if each individual resonator is characterized with normal GVD. Based on this concept we design a mode locked frequency comb with thin-film silicon nitride compound ring resonators in the vicinity of Rubidium D1 line (794.6nm) and propose to use this optical comb as a flywheel for chip-scale optical clocks.
Be careful with the Exp-function method
Nikolay A. Kudryashov,Nadejda B. Loguinova
Physics , 2010, DOI: 10.1016/j.cnsns.2008.07.021
Abstract: An application of the Exp-function method to search for exact solutions of nonlinear differential equations is analyzed. Typical mistakes of application of the Exp-function method are demonstrated. We show it is often required to simplify the exact solutions obtained. Possibilities of the Exp-function method and other approaches in mathematical physics are discussed. The application of the singular manifold method for finding exact solutions of the Fitzhugh - Nagumo equation is illustrated. The modified simple equation method is introduced. This approach is used to look for exact solutions of the generalized Korteweg - de Vries equation.
Electrodynamic phenomena induced by a dark fluid: Analogs of pyromagnetic, piezoelectric, and striction effects
Alexander B. Balakin,Nadejda N. Dolbilova
Physics , 2014, DOI: 10.1103/PhysRevD.89.104012
Abstract: We establish a new model of coupling between a cosmic dark fluid and electrodynamic systems, based on an analogy with effects of electric and magnetic striction, piezo-electricity and piezo-magnetism, pyro-electricity and pyro-magnetism, which appear in classical electrodynamics of continuous media. Extended master equations for electromagnetic and gravitational fields are derived using Lagrange formalism. A cosmological application of the model is considered, and it is shown that a striction-type interaction between the dark energy (the main constituent of the dark fluid) and electrodynamic system provides the universe history to include the so-called unlighted epochs, during which electromagnetic waves can not propagate and thus can not scan the universe interior.
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