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Die Optimierung der Museumsbeleuchtung basiert auf der gleichzeitigen Berucksichtigung energetischer, beleuchtungstechnischer, farbmetrischer und konservatorischer Aspekte, die sich auf den ersten Blick unter Umstanden widersprechen. Am Beispiel des Berliner “Bode-Museums“ konnte gezeigt werden, dass der Ersatz der bisher verwendeten HGL- durch LED-Leuchten eine Reduzierung des Energieumsatzes um bis zu 70 % ermoglicht. Im gedimmten Betrieb kann sich dieser Wert aufgrund der besser geeigneten Dimmkennlinie der LEDs noch weiter erhohen. Gleichzeitig ist mit einer verringerten Objektschadigung durch UV- und kurzwellige sichtbare Strahlung und deutlich verringerter thermischer Belastung der Objekte durch IR-Strahlung zu rechnen. Auserdem ermoglicht die Kombination verschiedener LEDs in einer Leuchte eine variable Lichtfarbe mit sehr guter Farbwiedergabe. Bei der Auswahl der LED-Losungen ist eine Abwagung der konservatorischen Anforderungen unerlasslich, als einfachstes Bewertungskriterium kann dabei die ahnlichste Farbtemperatur herangezogen werden. Werden alle diese Gesichtspunkte berucksichtigt, ermoglicht die LED-Technik erstmals die Kombination einer energieeffizienten verbesserten Beleuchtung bei gleichzeitig verbessertem Objektschutz. Optimized lighting for the Bode-Museum in Berlin. The optimization of museum lighting is based on energetic, luminous, colorimetric and conservation aspects, which seems to contradict each other in part. As an example the energy expenditure of the illumination of the “Bode-Museum” could be reduced by up to 70 % when replacing conventional HGL- by LED-luminaires. In dimmed mode, this value may increase even further due to a more appropriate dimming characteristic of LED. This is accompanied by a reduced damage by UV radiation and short wavelength part of the visible radiation and at the same time without thermal loading of objects by IR radiation. In addition, the combination of different LED in one luminaire creates a variable luminous colour with very good colour rendering properties. The consideration of the conservation requirements is essential when choosing the correct LED-lighting, for a simple evaluation criterion the correlated colour temperature can be used. If all these aspects are taken into account, the LED technology enables the combination of enhanced energy-efficient lighting with improved preservation requirements.

Fur eine zuverlassige Tageslichtplanung im Innenraum ist die genaue Kenntnis insbesondere uber die bi-direktionalen Kennzahlen (raumliche Verteilung des Leuchtdichtekoeffizienten q in Abhangigkeit des Lichteinfalls) der Tageslichtsysteme unverzichtbar. Es wird eine Methode mit Beispielen (RETROLux-Tageslichtsysteme) vorgestellt, bei der die gemessenen Verteilungen des Leuchtdichtekoeffizienten konvertiert werden, so dass die Ergebnisse in konventionellen Lichtplanungstools wie DIALux oder Relux importiert werden konnen, um lichttechnische Berechnungen mit photorealistischen Darstellungen durchzufuhren. Integration of luminous characteristics into lighting design tools using the example of an innovative sun protection system. For reliable daylighting design in interior, precise knowledge is essential in particular on the bi-directional characteristics (spatial distribution of luminance coefficient q as a function of the light incidence) of the daylighting systems. A new method is presented with examples (RETROLux-daylighting systems), in which the measured distributions of luminance coefficients are converted, so that the results can be imported into conventional lighting design tools such as DIALux and Relux to perform calculations with photo-realistic representations.

Mesenchymal stromal cells (MSC) and factors secreted by them are essential components of the hematopoietic stem cell (HSC) niche within the bone marrow microenvironment. It has been shown that the extracellular matrix (ECM) can influence HSC-supportive potential of MSC and is a prerequisite for the proper signaling of morphogens. Therefore, we aimed at the identification of ECM components and candidate morphogens capable of enhancing the expression of HSC-supportive proteins in human MSC, namely, angiopoietin-1 (Ang-1) and stromal cell-derived factor 1 (SDF-1). For this purpose, highly sensitive secreted dual reporter constructs for Ang-1 and SDF-1 were established. These newly designed dual reporter systems enable continuous monitoring of the Ang-1 and SDF-1 promoter activity in an immortalized human MSC line cultured on ECM/morphogen microarrays. Reporter arrays showed that Ang-1 and SDF-1 expression can be induced by different ECM/morphogen combinations. In addition, continuous monitoring of promoter activity allows delineating time-dependent effects of the ECM and morphogens. Thus, we identified that collagen I and vitronectin in combination with Wnt3a favored SDF-1 expression over time, while only transiently inducing the expression of Ang-1. Taken together, the newly developed reporter systems allow for the monitoring of Ang-1 and SDF-1 promoter activity induced by morphogens and the ECM in a combinatorial and high-throughput manner. This technology might therefore be helpful to optimize culture conditions, which favor the activity of MSC as feeder cells for various types of stem and progenitor cells.

Functional impairment of the human corneal endothelium can lead to corneal blindness. In order to meet the high demand for transplants with an appropriate human corneal endothelial cell density as a prerequisite for corneal function, several tissue engineering techniques have been developed to generate transplantable endothelial cell sheets. These approaches range from the use of natural membranes, biological polymers and biosynthetic material compositions, to completely synthetic materials as matrices for corneal endothelial cell sheet generation. This review gives an overview about currently used materials for the generation of transplantable corneal endothelial cell sheets with a special focus on thermo-responsive polymer coatings.

Der Energiebedarf von Gebauden ist in den letzten Jahren durch die Vorgabe von EU-Richtlinien und durch nationale Normen begrenzt worden und erfordert eine entsprechende Bewertung der Gebaude zum Nachweis der jeweiligen Energiebedarfszahlen. Dies ist auch auf offentliche Gebaude wie Museen umzusetzen. Die Themenschwerpunkte Heizung, Kuhlung, Behaglichkeit, Lebenszyklusanalyse, konservatorische Klimaanforderungen, Luftung, Stromungssimulation, Bausubstanzerhaltung und Raumakustik werden in einem Verbundprojekt des BMWi behandelt. Zusatzlich ist erganzend die Umsetzung der energetisch optimierten Beleuchtung und Erkennbarkeit in abgesicherte Planungsvorschlage zu erarbeiten. Dies gilt sowohl fur den Einsatz neuer Lampen- und Vorschalttechnik als auch fur den kombinierten Einsatz der Tageslichttechnik und elektronischer Kontrollsysteme. Energy-efficient lighting in museums, taking conservation into account. Energy demand in buildings has been restricted in recent years by EU Directives and national standards. Buildings now need to be assessed as proof that they meet the relevant energy demand requirements. These assessments must also be performed on public buildings, including museums. As part of a collaborative project, the BMWi (Federal Ministry of Economics and Technology) is currently addressing the issues of heating, cooling, comfort, life-cycle analysis, conservation-related requirements for air-conditioning, ventilation, flow simulation, structural preservation and acoustics. The project will also involve the development of definitive design guidance for implementing lighting and visibility with maximum energy efficiency. This will cover both new lamp and ballast technology and the combined use of daylight technology with electronic control systems.

Die wissenschaftlich-technischen Arbeitsziele dieses vom Bundesministerium fur Wirtschaft (BMWi) geforderten Projektes wurden in funf Teilen erarbeitet. Die einzelnen Themen resultieren aus aktuellen Fragestellungen; sie haben dennoch einen allgemein anwendbaren Charakter. Das Konsortium hat die folgenden Teilprojekte bearbeitet: (1) Aufbau einer Messtechnik zur Bestimmung energetischer und lichttechnischer Kennzahlen von Tageslichtbauteilen mit einem round robin test, an dem drei Institute beteiligt waren. (2) Realisierung eines detaillierten Bewertungs- und Nachweisverfahrens fur die Tageslichtversorgung von Innenraumen in unterschiedlichen Klimazonen. (3) Fur die Beleuchtungskontrolle privater Lebensraume wurde ein “Powerline Carrier Communication“-System evaluiert und die Vorteile gegenuber einem Funkubertragungssystem herausgearbeitet. (4) In einem Pflegeheim wurden quantitative Untersuchungen zum Wohlbefinden, zur Erfullung von Sehaufgaben und zur Eignung zur Melatoninsuppression bei verschiedenen Szenarien der Allgemeinbeleuchtung mit zwei unterschiedlichen Farbtemperaturen der eingesetzten Lampen (“warmweises Licht“ mit TCP = 3000 K und “kaltweises Tageslicht“ mit TCP = 6500 K) und vertikalen Beleuchtungsstarken an den Augen der Probanden zwischen 100 lx und 700 lx durchgefuhrt. (5) Fur zwei Schulgebaude in Berlin wurde der Endenergiebedarf der Bestandsanlage, des Referenzgebaudes sowie der Neuplanung ermittelt. Dabei wurde in beiden Beispielen deutlich, dass die Bestandsanlage im Bereich der Beleuchtung den zulassigen Wert nach EnEV 2009 mitunter weit uberschreitet. Eine gute Neuplanung hingegen kann den maximal zulassigen Wert deutlich unterschreiten. Diese Untersuchungen wurden von einem einjahrigen Monitoring des Energieumsatzes begleitet. Eine Querschnittsanalyse uber 48 Schulen mit insgesamt 86 Gebauden zeigt unter anderem einen erheblichen Sanierungsbedarf bei Schulgebauden, die vor 1990 errichtet wurden. Energy optimised lighting in buildings with simultaneous improvement of quality of life by daylight utilisation and innovative lamps and ballast techniques. The scientific and technical goals of this project were developed in five parts. The individual topics arising from current issues, they still have a generally applicable nature. The consortium has worked on the following subprojects: (1) Development of a measurement technique to determine energy and photometric key figures of daylight components with a round robin test with three institutes. (2) Implementation of a detailed evaluation and documentation process for daylighting of interior spaces in different climate zones. (3) For lighting control in private living areas a “Power Line Carrier Communication” system has been evaluated and the advantages of a wireless transmission system were identified. (4) In a home for elderly quantitative studies on the well-being, for the fulfillment of visual tasks and the capability of melatonin suppression at different scenarios of general lighting with two different color temperatures of lamps (“warm white” with TCP = 3000 K and “cold white daylight” with TCP = 6500 K) and vertical illuminance at the eyes of the subjects between 100 lx and 700 lx were performed. (5) For two school buildings in Berlin, the final energy consumption of the existing lighting system, the reference building and a re-planning were determined. It became clear in both examples that the existing lighting system exceeds the permitted value (EnEV 2009) by far. A good redesign, however, can be significantly less than the maximum allowed value. These studies were accompanied by a one-year monitoring of energy consumption. A cross-sectional analysis of 48 schools with a total of 86 buildings shows a substantial need for renovation of school buildings that were built before 1990.

In biomedizinischen Anwendungen mussen die polymeren Materialien haufig mit einer biokompatiblen Oberflache ausgerustet werden. Wir stellen verschiedene Methoden vor, biokompatible und auch bioaktive Hydrogele auf Polymeroberflachen zu immobilisieren. Dabei werden einerseits Makroinitiator-Reaktivschichten eingesetzt, die es erlauben, z. b. Polyacrylsaurehydrogele auf Polykondensaten durch „grafting-from” aufwachsen zu lassen. Auf der anderen Seite konnen vorgefertigte hydrophile Polymere uber Plasma und Elektronenstrahlimmobilisierung kovalent an verschiedenen Oberflachen gebunden werden. Die Stabilitat, Quellfahigkeit und Biokompatibilitat der Hydrogelschichten konnte verifiziert werden. Uber das Einbringen von ph bzw. thermoresponsiven Gruppen kann das Quellverhalten der Schichten auch extern gesteuert werden. Biocompatible and bioactive polymer surface for most biomedical applications of polymers biocompatible surface properties are highly needed. here we present various methods to immobilize biocompatible and also bioactive hydrogels on polymer surfaces. In one approach, macroinitiator-based reactive layers are attached to polycondensates which are able to allow the grafting-from of various hydrogels. on the other hand, it is possible to immobilize hydrophilic polymers on various substrates by plasma and e-beam treatment. Stability, swelling and biocompatibility of the polymer films could be verified. by incorporating ph and thermo-responsive groups, it is possible additionally to control the swelling behaviour by external triggers.

Thin films of poly(vinyl methyl ether) (PVME) were immobilized on polystyrene surfaces by low energy elec- tron beam cross-linking. Structure retention as well as the thermo-responsive swelling behavior in aqueous media were studied by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and spectroscopic ellipsometry respectively. The physical properties of the thermo-responsive coatings can be controlled in a wide range by adjusting the irradiation parameters. To allow for a variety of biomolecular functionalization strategies, the concept was extended by adding reactive sites to the system. For that purpose a mixture of PVME and the copolymer of PVME and maleic acid was applied, that possesses a similar stimuli-responsive behavior.

Recently, it was possible to show that human corneal endothelial cells (HCEC) can be cultured on thermo-responsive polymer substrates, and can be harvested as entire cell sheets without losing viability. We sought to study HCEC sheet cultivation on such cell culture carriers under serum-free conditions as the next consequential step in developing methods for generation of corneal endothelial cell transplants.An immortalized heterogenous HCEC population and two immortalized, clonally grown HCEC lines (HCEC-B4G12 and HCEC-H9C1) were cultured on thermo-responsive substrates under serum-supplemented and serum-free culture conditions. Cell sheets were characterized by phase contrast microscopy and by immunofluorescent staining for ZO-1, Na(+),K(+)-ATPase, and vinculin.All tested HCEC populations were able to adhere, spread and proliferate on thermo-responsive substrates under serum-supplemented conditions. Under serum-free conditions, pre-coating of the polymer substrates with ECM proteins was necessary to facilitate attachment and spreading of the cells, except in the case of HCEC-B4G12 cells. The heterogenous HCEC population formed closed monolayers, properly localized ZO-1 to lateral cell borders, and had moderate vinculin levels under serum-free, and higher vinculin levels under serum-supplemented culture conditions. HCEC-B4G12 cells formed closed monolayers, showed proper localization of ZO-1 and Na(+),K(+)-ATPase to lateral cell borders, and had high vinculin levels irrespective of culture conditions. In contrast, HCEC-H9C1 cells had lowest vinculin levels under serum-supplemented, and higher vinculin levels under serum-free culture conditions. ZO-1 was detected throughout the cytoplasm under both culture conditions. These loosely adherent cells were only able to form a closed monolayer under serum-supplemented conditions.Serum-free production of HCEC sheets is possible. The extremely adherent clonal HCEC line B4G12 produced higher vinculin levels than the other two tested HCEC populations, and showed strong adherence to the thermo-responsive, polymeric culture substratum irrespective of culture conditions. This cell line closely resembles terminally differentiated HCEC in vivo, and was found to be particularly suitable for further studies on HCEC cell sheet engineering.

A series of graft copolymers consisting of poly(N-isopropylacrylamide) as a thermoresponsive component in the polymer backbone and poly(ethyleneglycol) side chains were immobilized as thin films on various substrates via low-pressure plasma treatment. The surface-immobilized hydrogels exhibit a transition from partially collapsed to completely swollen, which is in the range of 32 – 35 °C and corresponds to the lower critical solution temperature of the soluble polymers. Cell culture and detachment experiments were performed with mouse fibroblasts and human corneal endothelial cells under standard conditions. The hydrogel-coated supports were found to permit adhesion, spreading and proliferation of the cells and allowed for fast and effective temperature-dependent detachment of intact cell sheets of both cell types. Thus, these coatings offer an efficient method for growth and gentle harvesting of functional cellular assemblies for use in tissue engineering strategies.

New glycomonomers 3-(1,2:5,6-di-O-isopropylidene--D-glucofuranosyl)-6-methacrylamido hexanoate (MAIpGlcC5) and 3-(1,2:5,6-di-O-isopropylidene--D-glucofuranosyl)-6-methacrylamido undecanoate (MAIpGlcC10) with hydrophobic spacer units were synthesized and their homopolymers, as well as random copolymers with N-isopropylacrylamide (NiPAAm) were prepared in varying compositions. The acidolysis of the isopropylidene protection groups of the polymers gave well-defined sugar-containing water-soluble homopolymers (PMAGlcCn, n = 5, 10) and copolymers. By using the reversible addition-fragmentation chain transfer (RAFT) process, it was possible to afford these copolymers with a polydispersity index (PDI) of 1.1-1.5. Furthermore, NiPAAm homopolymers with an active chain transfer unit at the chain end could be prepared by RAFT, which were used as macro-chain transfer agents (macro-CTAs) to prepare a variety of sugar containing responsive block copolymers from new glycomonomers by the monomer addition concept. The cloud points of the aqueous solutions of the copolymers were strongly affected by the comonomer content, spacer chain length of the glycomonomer, and the chain architecture of the copolymers. Especially by the block copolymer concept, glycopolymers with lower critical solution temperatures (LCSTs) in the physiologically interesting range could be realized.

The technique of gently harvesting cells and cell sheets using stimuli-responsive cell culture carriers was applied to human umbilical vein cord endothelial cells (HUVEC). To meet the particular requirements of this demanding cell type, a copolymer consisting of N-isopropylacrylamide and diethyleneglycol methacrylate (poly(NiPAAm-co-DEGMA)) was combined with a fine-tuned protein pre-coating. Using this approach the detachment of HUVEC sheets was studied. Furthermore, the behavior of the extracellular matrix upon cell detachment was followed by protein staining. The results demonstrate the feasibility of harvesting HUVEC sheets from stimuli-responsive polymer layers and provide valuable options for the advanced engineering of vascular structures.

Gentle harvesting of corneal endothelial cell sheets grown in culture is of interest for the development of cornea replacement strategies. Thin films of a fast responding copolymer of N-isopropylacrylamide (NiPAAm) and diethyleneglycol methacrylate (DEGMA) with a phase transition temperature of 32°C were prepared and evaluated for that purpose. The polymer layers were immobilized onto fluorocarbon substrates using low pressure argon plasma treatment. Cell culture and detachment experiments were performed with L929 mouse fibroblasts and human corneal endothelial cells (HCEC) at standard conditions. The hydrogel-coated supports were found to permit adhesion, spreading, and proliferation of both cell types. Harvesting of cell sheets was achieved upon lowering the temperature to about 30°C. The formation of a closed monolayer as a crucial prerequisite for maintaining ionic pump function in HCEC was proven by ZO-1 immunostainung. Labeling of fibronectin indicated that the vast majority of the extracellular matrix is detached from the hydrogel coatings together with the cell layer. Inspired by this result, the reuse of the hydrogel-coated culture carriers was investigated confirming the suitability of the substrates for repeated cell harvesting. Altogether, the introduced thermoresponsive coating was found advantageous for the efficient generation of HCEC sheets and will be further utilized in transplantation strategies. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 80A:, 2007

The kinetics of the copolymerization of N-isopropylacrylamide (NiPAAm) and diethylene glycol monomethylether monomethacrylate was followed by online 1H NMR spectroscopy. Two copolymerization reactions were sufficient to evaluate the kinetic data with the Extended-Kelen–Tudos method as well as the nonlinear least square method. The copolymerization parameter was determined as rNiPAAm = 0.70 and rDEGMA = 2.0. The higher reactivity of the methacrylate compared to the NiPAAm is in good agreement with other kinetic data of similar systems. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 142–148, 2005

Corneal endothelial diseases lead to severe vision impairment, motivating the transplantation of donor corneae or corneal endothelial lamellae, which is, however, impeded by endothelial cell loss during processing. Therefore, one prioritized aim in corneal tissue engineering is the generation of transplantable human corneal endothelial cell (HCEC) layers. Thermo-responsive cell culture carriers are widely used for non-enzymatic harvest of cell sheets. The current study presents a novel thermo-responsive carrier based on simultaneous electron beam immobilization and cross-linking of poly(vinyl methyl ether) (PVME) on polymeric surfaces, which allows one to adjust layer thickness, stiffness, switching amplitude and functionalization with bioactive molecules to meet cell type specific requirements. The efficacy of this approach for HCEC, which require elaborate cell culture conditions and are strongly adherent to the substratum, is demonstrated. The developed method may pave the way to tissue engineering of corneal endothelium and significantly improve therapeutic options.

Physico-chemical and topographical cues allow to control the behavior of adherent cells. Towards this goal, commercially available cell culture carriers can be finished with a laterally microstructured biomolecular functionalization. As shown in a previous study [Biomacromolecules 4 (2003) 1072], the anhydride moiety facilitates a simple and versatile way to protein binding. The present work addresses the technical issue of anhydride surface functionalization of polystyrene, the most common material for cell culture ware. Different approaches based on low pressure plasma, electron beam and ultraviolet light techniques (i.e. maleic anhydride plasma reactions; plasma, electron beam and UV immobilization of functional polymer thin films; grafting of functional polymers to plasma activated surfaces) are introduced and briefly illustrated with examples. Results are characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and ellipsometry. The different routes are compared in terms of technical feasibility and achievable surface properties.

Two established material systems for thermally stimulated detachment of adherent cells were combined in a cross-linked polymer blend to merge favorable properties. Through this approach poly(N-isopropylacrylamide) (PNiPAAm) with its superior switching characteristic was paired with a poly(vinyl methyl ether)-based composition that allows adjusting physico-chemical and biomolecular properties in a wide range. Beyond pure PNiPAAm, the proposed thermo-responsive coating provides thickness, stiffness and swelling behavior, as well as an apposite density of reactive sites for biomolecular functionalization, as effective tuning parameters to meet specific requirements of a particular cell type regarding initial adhesion and ease of detachment. To illustrate the strength of this approach, the novel cell culture carrier was applied to generate transplantable sheets of human corneal endothelial cells (HCEC). Sheets were grown, detached, and transferred onto planar targets. Cell morphology, viability and functionality were analyzed by immunocytochemistry and determination of transepithelial electrical resistance (TEER) before and after sheet detachment and transfer. HCEC layers showed regular morphology with appropriate TEER. Cells were positive for function-associated marker proteins ZO-1, Na+/K+-ATPase, and paxillin, and extracellular matrix proteins fibronectin, laminin and collagen type IV before and after transfer. Sheet detachment and transfer did not impair cell viability. Subsequently, a potential application in ophthalmology was demonstrated by transplantation onto de-endothelialized porcine corneas in vitro. The novel thermo-responsive cell culture carrier facilitates the generation and transfer of functional HCEC sheets. This paves the way to generate tissue engineered human corneal endothelium as an alternative transplant source for endothelial keratoplasty.

The physicochemical properties of thermo-responsive polymer films are dynamically altered upon changes in environmental conditions. We report on the design and detailed characterization of a novel thermo-responsive polymer film with a temperature transition tuned to fit applications related to the control of marine biofouling. A copolymer consisting of poly(N-isopropylacrylamide) (PNIPAAm) and N-(1-phenylethyl) acrylamide (PEAAm) was synthesized and immobilized as a thin film onto Teflon AF surfaces using a low pressure argon plasma treatment. The temperature dependent physicochemical properties of the thermo-responsive film were thoroughly characterized and the impact of sea water on the film properties was investigated. The immobilized thermo-responsive film exhibits a reversible swelling/deswelling with temperature. Atomic force microscopy showed no morphological changes with varying temperature. Streaming current measurements performed above and below the transition temperature of the thermo-responsive hydrogel indicated that the charging of the polymer/aqueous solution interface is mainly determined by the preferential water ion adsorption at the Teflon AF surface. Inverse contact angles measured using captive air bubbles and analysed by axisymmetric drop shape analysis (ADSA) supported the intrinsic properties of the thermo-responsive film, as surface hydrophilicity decreased with increasing temperature. The advancing water contact angle decreased with increasing temperature, which may be explained by the different molecular mobility at different temperatures, allowing or hampering the re-orientation of hydrophobic segments at the solid–liquid and solid–fluid interfaces. These new films will allow investigations on the interaction of microorganisms with environmentally sensitive surfaces.