TY - JOUR A1 - Safinia, L. A1 - Dantan, Nathalie A1 - Höhse, Marek A1 - Mantalaris, A. A1 - Bismarck, A. T1 - Towards a methodology for the effective surface modification of porous polymer scaffolds N2 - A novel low-pressure radio-frequency plasma treatment protocol was developed to achieve the effective through-thickness surface modification of large porous poly (d,l-lactide) (PDLLA) polymer scaffolds using air or water: ammonia plasma treatments. Polymer films were modified as controls. Scanning electron micrographs and maximum bubble point measurements demonstrated that the PDLLA foams have the high porosity, void fraction and interconnected pores required for use as tissue engineering scaffolds. The polymer surface of the virgin polymer does contain acidic functional groups but is hydrophobic. Following exposure to air or water: ammonia plasma, an increased number of polar functional groups and improved wetting behaviour, i.e. hydrophilicity, of wet surfaces was detected. The number of polar surface functional groups increased (hence the decrease in water contact angles) with increasing exposure time to plasma. The change in surface composition and wettablility of wet polymer constructs was characterised by zeta potential and contact angle measurements. The hydrophobic recovery of the treated PDLLA polymer surfaces was also studied. Storage of the treated polymer constructs in ambient air caused an appreciable hydrophobic recovery, whereas in water only partial hydrophobic recovery occurred. However, in both cases the initial surface characteristics decay as function of time. KW - Scaffold KW - Polyactic acid KW - Plasma KW - Surface modification KW - Contact angle KW - Wettability hydrophilicity PY - 2005 DO - https://doi.org/10.1016/j.biomaterials.2005.05.078 SN - 0142-9612 VL - 26 IS - 36 SP - 7537 EP - 7547 PB - Elsevier CY - Oxford AN - OPUS4-11487 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dantan, Nathalie A1 - Höhse, Marek A1 - Karasyov, A.A. A1 - Wolfbeis, Otto S. T1 - Entwicklung eines optischen pH-Sensors zur Früherkennung korrosionsgefährdender Zustände in Stahlbeton KW - Korrosion KW - Stahlbeton KW - Monitoring KW - pH-Wert KW - Faseroptik KW - Sensorik KW - Corrosion KW - Steel-reinforced concrete KW - pH value KW - Fiber optic sensor PY - 2007 SN - 0340-837X SN - 0178-2312 SN - 0171-8096 VL - 74 IS - 4 SP - 211 EP - 216 PB - Oldenbourg CY - München AN - OPUS4-14971 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Höhse, Marek A1 - Gornushkin, Igor B. A1 - Merk, Sven A1 - Panne, Ulrich T1 - Assessment of suitability of diode pumped solid state lasers for laser induced breakdown and Raman spectroscopy N2 - The potential of a diode pumped solid state (DPSS) laser for laser induced breakdown spectroscopy (LIBS) and Raman spectroscopy was investigated. The DPSS laser operating at repetition rates of 1 Hz–200 kHz, pulse energy of ~1 mJ, and pulse duration of ~20 ns was added to a conventional LIBS system equipped with the flashlamp-pumped Nd:YAG laser (10 Hz, 400 mJ, 6 ns) to directly compare the two laser systems. Despite the lower mass ablated per laser pulse (~several nanograms) and a weaker plasma, the total mass ablated per measurement interval (~1 s) and total emission signal were significantly higher than those obtained with the flashlamp pumped Nd:YAG laser. This resulted in the improved signal-to-noise ratio and better limits of detection (LOD). The best LODs were obtained for Cu, Cr and Ni in ultrapure standard iron samples, 0.7 ppm, 1 ppm and 5 ppm, correspondingly. The plasma from the DPSS laser was characterized in terms of its radiative properties, temperature, and shockwave propagation speed. The suitability of this laser for LIBS-Raman was demonstrated by mapping the elemental and molecular composition of a mineral sample. The results strongly imply that DPSS lasers are the promising source for LIBS, Raman, or combined LIBS-Raman spectroscopy. PY - 2011 DO - https://doi.org/10.1039/c0ja00038h SN - 0267-9477 SN - 1364-5544 VL - 26 IS - 2 SP - 414 EP - 424 PB - Royal Society of Chemistry CY - London AN - OPUS4-22943 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Höhse, Marek A1 - Mory, D. A1 - Florek, S. A1 - Weritz, Friederike A1 - Gornushkin, Igor B. A1 - Panne, Ulrich T1 - A combined laser-induced breakdown and Raman spectroscopy Echelle system for elemental and molecular microanalysis N2 - Raman and laser-induced breakdown spectroscopy is integrated into a single system for molecular and elemental microanalyses. Both analyses are performed on the same ~ 0.002 mm² sample spot allowing the assessment of sample heterogeneity on a micrometric scale through mapping and scanning. The core of the spectrometer system is a novel high resolution dual arm Echelle spectrograph utilized for both techniques. In contrast to scanning Raman spectroscopy systems, the Echelle-Raman spectrograph provides a high resolution spectrum in a broad spectral range of 200-6000 cm- 1 without moving the dispersive element. The system displays comparable or better sensitivity and spectral resolution in comparison to a state-of-the-art scanning Raman microscope and allows short analysis times for both Raman and laser induced breakdown spectroscopy. The laser-induced breakdown spectroscopy performance of the system is characterized by ppm detection limits, high spectral resolving power (15,000), and broad spectral range (290-945 nm). The capability of the system is demonstrated with the mapping of heterogeneous mineral samples and layer by layer analysis of pigments revealing the advantages of combining the techniques in a single unified set-up. KW - LIBS KW - Raman KW - Echelle KW - Laser-induced breakdown spectroscopy KW - Hyphenated technique PY - 2009 DO - https://doi.org/10.1016/j.sab.2009.09.004 SN - 0584-8547 SN - 0038-6987 VL - 64 IS - 11-12 SP - 1219 EP - 1227 PB - Elsevier CY - Amsterdam AN - OPUS4-20493 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -