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Goldenberg L.M.,Wildau University of Applied Sciences | Goldenberg L.M.,Plasmachem GmbH | Lisinetskii V.A.,Wildau University of Applied Sciences | Schrader S.,Wildau University of Applied Sciences
Laser Physics | Year: 2014

Two simple procedures to manufacture continuously tunable miniature lasers in azobenzene-containing material were developed. Both types of lasers rely on the distributed feedback provided by polarization gratings. In a first approach tuning is achieved by changing the thickness of the active wave guiding layer by means of a wedge layer and in a second approach by gradually changing the spatial frequency of the refractive index grating obtained by modification of the Lloyd interferometer set-up used for holographic inscription of the gratings. A continuous tuning range of up to 35 nm has been demonstrated. © 2014 Astro Ltd. Source


Goldenberg L.M.,Plasmachem GmbH | Lisinetskii V.,Wildau University of Applied Sciences | Ryabchun A.,Fraunhofer Institute for Applied Polymer Research | Ryabchun A.,Moscow State University | And 2 more authors.
Journal of Materials Chemistry C | Year: 2014

The well-known commercially available azobenzene-containing polyelectrolyte poly{1-[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl, sodium salt} (PAZO-Na) has been easily modified by converting it into carboxylic acid and different salts. These new materials, similar to original PAZO-Na, were used as matrices to create DFB lasers based on polarization gratings. Such matrix modification allowed us to obtain laser generation with the laser dye 1,2,3,5,6,7-hexamethyl-8-cyanopyrromethene-difluoroborate complex (pyrromethene 650), to increase the laser device stability (up to a half-life time of 4 × 104pulses) and to considerably increase the laser efficiency (up to 9%). Therefore, these polymer composites can be considered as cheap and promising materials for photonics, optoelectronics, and sensor applications. © the Partner Organisations 2014. Source


Goldenberg L.M.,Wildau University of Applied Sciences | Goldenberg L.M.,Plasmachem GmbH | Lisinetskii V.,Wildau University of Applied Sciences | Schrader S.,Wildau University of Applied Sciences
Advanced Optical Materials | Year: 2014

Using amorphous side-chain azobenzene-containing polymers, stable and efficient miniature lasers based on polarization gratings as distributed feedback are fabricated. The lasers with Rhodamine 700 dye as the emitter exhibit a low lasing threshold of ca. 20 μJ cm-2, which is even further decreased to ca. 5-10 μJ cm-2 for the devices emitting in the 1st diffraction order. Additionally this new formulation exhibits a considerably higher efficiency of ca. 3%, and a higher half-life of more than 1 × 105 shots. A wide wavelength tuning range of 115 nm is obtained for the same formulation only by changing grating frequency. A variation of polymer matrix, laser dye, and grating spatial frequency allows an extended tuning range between 611 and 873 nm. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Zhang W.,Zhejiang University | Jiang P.,Zhejiang University | Chen W.,Zhejiang University | Zheng B.,Zhejiang University | And 5 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2016

The surface chemistry of nanoparticles (NPs) is one of the critical factors determining their cellular responses. In this study, the cytotoxicity and genotoxicity of copper oxide (CuO) NPs with a similar size but different surface chemistry to rat bone marrow mesenchymal stem cells (MSCs) were investigated. The morphology, size and surface charge of four types of CuO NPs, i.e., CuO-core, CuO-COOH, CuO-NH2 and CuO-PEG NPs, were characterized by TEM, dynamic light scattering (DLS) and zeta-potential measurement, respectively. All of the four CuO NPs had a negative surface charge around -10 mV and showed a similar tendency to form agglomerates with a size of ∼200 nm in cell culture environment. The cytotoxicity of CuO NPs to MSCs at various concentrations and incubation periods were firstly evaluated. The CuO NPs showed dose-dependent and time-dependent toxicity to MSCs, and their surface chemistry had influence on the toxicity to some extent too. The intracellular reactive oxygen species (ROS) level of MSCs was then quantified. Finally, the genotoxicity of the CuO NPs was studied by comet assay. The results suggest that the genotoxicity of CuO NPs was mainly dependent on NPs concentration, and was only slightly influenced by their surface chemistry. The osteogenic and adipogenic differentiation abilities of the MSCs exposed to different CuO NPs were studied by Alizarin Res S and Oil Red O staining. The preliminary results showed that the exposure to 10 μg/mL CuO NPs will not lead to significant impact on the differentiation potential of the MSCs. Copyright © 2016 American Scientific Publishers All rights reserved. Source


Severin N.,Humboldt University of Berlin | Dorn M.,Humboldt University of Berlin | Kalachev A.,Plasmachem GmbH | Rabe J.P.,Humboldt University of Berlin
Nano Letters | Year: 2011

The electronic properties of graphenes depend sensitively on their deformation, and therefore strain engineered graphene electronics is envisioned.(1-3)In order to deform graphenes locally, we have mechanically exfoliated single and few layer graphenes onto atomically flat mica surfaces covered with isolated double stranded plasmid DNA rings. Using scanning force microscopy in both contact and intermittent contact modes, we find that the graphenes replicate the topography of the underlying DNA with high precision. The availability of macromolecules of different topologies, e.g., programmable DNA patterns,(4)render this approach promising for new graphene based device designs.(1, 3)On the other hand, the encapsulation of single macromolecules offers new prospects for analytical scanning probe microscopy techniques. © 2011 American Chemical Society. Source

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