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118 results on '"Klar, T."'

5. The Effect of Mobile Indoor Air Cleaners on the Risk of Infection with SARS-CoV-2 in Surgical Examination and Treatment Rooms with Limited Ventilation Options

Author

M Oberst, Klar T, A Heinrich, and Trauma Clinic for Orthopedics

Subjects
medicine.medical_specialty, Indoor air, business.industry, law, Risk of infection, Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), Ventilation (architecture), Emergency medicine, Medicine, Ocean Engineering, business, complex mixtures, law.invention
Abstract

Objective: Due to the airborne transmission of the Coronavirus Disease (Covid-19) via aerosols, we investigated the effect of a mobile air filter system in a surgical examination room. Methods: A mobile indoor air cleaner (AP 90, DEMA-airtech, Germany) was run during regular surgical consulting hour in our outpatient’s clinic. Aerosol concentration was measured by Fidas Frog fine dust monitoring system (Palas, Germany) by constantly recording PM1.0, PM2.5, PM4, PM10 and the total particle load PMtot. Results: The use of the air filter system led to a significant reduction of aerosols in the room despite the fact that there were various numbers of persons in the room constantly. Conclusion: The use of a high efficiency air filtration device, especially in examination rooms with poor ventilation, e.g., lack of windows or local exhaust is recommendable.

Published
2021
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12. Optical properties of InN grown on Si(111) substrate

Author

Sakalauskas, E., Schley, P., Räthel, J., Klar, T. A., Müller, R., Pezoldt, J., Tonisch, K., Grandal, J., Sanchez-Garcia, M.A., Calleja, E., Vilalta-Clemente, Arantxa, Ruterana, Pierre, Goldhahn, R., Institut für Festkörperelektronick, Max-Planck-Institut, Departamento de Ingeniería Electrónica and ISOM (ETSI Telecomunicacion), Universidad Politécnica de Madrid (UPM)-Ciudad Universitaria, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Brassy, Chantal, Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), and Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
optical properties, PAMBE, band gap, interband transitions, InN films, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [PHYS.COND.CM-MS] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
Abstract

International audience; A comprehensive characterization of the optical properties of wurtzite InN films grown by molecular beam epitaxy on Si(111) substrates is presented. Two types of films are investigated in this work: InN on AlN/Si(111) and InN on GaN/AlN/Si(111). Their properties are compared to a layer deposited on GaN/ sapphire substrate. The dielectric function (DF) is obtained from spectroscopic ellipsometry (SE). The infrared studies yield the plasma frequency and thus the electron density, while the interband absorption is probed between 0.56 and 9.8 eV. For InN grown on Si(111) substrate, the absorption onset is slightly shifted to higher energies with respect to the InN film grown on GaN/sapphire which can be attributed to higher electron concentrations. Despite this, strongly pronounced optical transitions due to critical points of the band structure are found in the high-energy part of the DF. It emphasizes the already promising quality of the InN films on silicon. Band-gap renormalization (BGR), band filling, and strain are taken into account in order to estimate the intrinsic band gap of wurtzite InN. For the InN layers on silicon, we get a band gap between 0.66 and 0.685 eV.

Published
2010

13. Bone-forming cells with pronounced spread into the third dimension in polymer scaffolds fabricated by two-photon polymerization.

Author

Heitz, J., Plamadeala, C., Wiesbauer, M., Freudenthaler, P., Wollhofen, R., Jacak, J., Klar, T. A., Magnus, B., Köstner, D., Weth, A., Baumgartner, W., and Marksteiner, R.

Abstract

The main aim of this work was to stimulate bone-forming cells to produce three-dimensional networks of mineralized proteins such as those occurring in bones. This was achieved by a novel approach using a specific type of mesenchymal progenitor cells (i.e., primary fibroblast cells from human hair roots) seeded on to polymer scaffolds. We wrote polymer microstructures with one or more levels of quadratic pores on to a flexible substrate by means of two-photon polymerization using a Ti-sapphire femtosecond laser focused into a liquid acrylate-based resin containing a photoinitiator. Progenitor cells, differentiated into an osteogenic lineage by the use of medium supplemented with biochemical stimuli, can be seeded on to the hydrophilic three-dimensional scaffolds. Due to confinement to the microstructures and/or mechanical interaction with the scaffold, the cells are stimulated to produce high amounts of calcium-binding proteins, such as collagen type I, and show an increased activation of the actin cytoskeleton. The best results were obtained for quadratic pore sizes of 35 µm: the pore volumes become almost filled with both cells in close contact with the walls of the structure and with extracellular matrix material produced by the cells. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 891-899, 2017. [ABSTRACT FROM AUTHOR]

Published
2017
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18. Optical properties of InN grown on Si(111) substrate

Author

Sakalauskas, E., primary, Schley, P., additional, Räthel, J., additional, Klar, T. A., additional, Müller, R., additional, Pezoldt, J., additional, Tonisch, K., additional, Grandal, J., additional, Sánchez-García, M. A., additional, Calleja, E., additional, Vilalta-Clemente, A., additional, Ruterana, P., additional, and Goldhahn, R., additional

Published
2010
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39. Gold Nanoshells Improve Single Nanoparticle Molecular Sensors

Author

Raschke, G., primary, Brogl, S., additional, Susha, A. S., additional, Rogach, A. L., additional, Klar, T. A., additional, Feldmann, J., additional, Fieres, B., additional, Petkov, N., additional, Bein, T., additional, Nichtl, A., additional, and Kürzinger, K., additional

Published
2004
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49. Photodoping with CdSe nanocrystals as a tool to probe trap-state distributions in C60 crystals.

Author

Biebersdorf, A., Dietmüller, R., Ohlinger, A., Klar, T. A., Feldmann, J., Talapin, D. V., and Weller, H.

Subjects
NANOCRYSTALS, SEMICONDUCTORS, SEMICONDUCTOR doping, CRYSTALS, PHYSICS
Abstract

Optical injection of electrons from CdSe nanocrystals into amorphous semiconductors can be used to optically control the electron density in trap-rich conduction bands. For the specific example of polycrystalline C60, we show that important parameters of the density of trap states below the mobility edge can be retrieved. [ABSTRACT FROM AUTHOR]

Published
2008
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50. Negative-Index Metamaterials: Going Optical.

Author

Klar, T. A., Kildishev, A. V., Drachev, V. P., and Shalaev, V. M.

Abstract

The race toward engineering metamaterials comprising of negative refractive indexes in the optical range started with the realization of negative-index materials for gigahertz frequencies six years ago. Sheer miniaturization of the gigahertz resonant structures is one approach. Alternative designs make use of localized plasmon resonant metal nanoparticles or nanoholes in metal films. Following this approach, a negative refractive index has been realized in the optical range very recently. We review these recent results and summarize how to unambiguously retrieve the effective refractive index of thin layers from data accessible to measurements. Numerical simulations show that a composite material comprising of silver strips and a gain-providing material can have a negative refractive index of -1.3 and 100% transmission, simultaneously. [ABSTRACT FROM PUBLISHER]

Published
2006
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