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Stress is a normal part of life for fungi, which can survive in environments considered inhospitable or hostile for other organisms. Due to the ability of fungi to respond to, survive in, and transform the environment, even under severe stresses, many researchers are exploring the mechanisms that enable fungi to adapt to stress. The International Symposium on Fungal Stress (ISFUS) brings together leading scientists from around the world who research fungal stress. This article discusses presentations given at the third ISFUS, held in Sao Jose dos Campos, Sao Paulo, Brazil in 2019, thereby summarizing the state-of-the-art knowledge on fungal stress, a field that includes microbiology, agriculture, ecology, biotechnology, medicine, and astrobiology.
The present work shows results on elemental distribution analyses in Cu(In,Ga)Se2 thin films for solar cells performed by use of wavelength-dispersive and energy-dispersive X-ray spectrometry (EDX) in a scanning electron microscope, EDX in a transmission electron microscope, X-ray photoelectron, angle-dependent soft X-ray emission, secondary ion-mass (SIMS), time-of-flight SIMS, sputtered neutral mass, glow-discharge optical emission and glow-discharge mass, Auger electron, and Rutherford backscattering spectrometry, by use of scanning Auger electron microscopy, Raman depth profiling, and Raman mapping, as well as by use of elastic recoil detection analysis, grazing-incidence X-ray and electron backscatter diffraction, and grazing-incidence X-ray fluorescence analysis. The Cu(In,Ga)Se2 thin films used for the present comparison were produced during the same identical deposition run and exhibit thicknesses of about 2 µm. The analysis techniques were compared with respect to their spatial and depth resolutions, measuring speeds, availabilities, and detection limits.
A Proof of Concept: Are Detection Dogs a Useful Tool to Verify Potential Biomarkers for Lung Cancer?
(2018)
Early and reliable diagnostic test is essential for effective therapy of lung cancer. Volatile organic compounds that are characteristic for cancer could serve as valuable biomarkers in cancer diagnosis. Both trace analytical and detection dog approaches give some evidence for the existence of such biomarkers. In this proof of concept, study dogs and trace analysis were implemented in combination to gain more information concerning cancer biomarkers. Two dogs were trained to distinguish between absorbed breath samples of lung cancer patients and healthy persons and succeeded with correct identification of patients with 9/9 and 8/9 and correct negative indications from of 8/10 and 4/10 samples from healthy individuals. A recent observational study found that breath samples from lung cancer patients showed an increase in 1-butanol, 2-butanone, 2-pentanone, and hexanal. Synthetic air samples were therefore fortified with these compounds and adsorbed to a fleece. Tested against breath samples from healthy probands, on presentation to the dogs these synthetic samples provoked an indication in three out of four samples. We were able to demonstrate that a combination of the natural nose of a dog and a trace analytic technique can be a valuable concept in the search for cancer biomarkers.
In vitro cultured lung cancer cells are not suitable for animal-based breath biomarker detection
(2015)
In vitro cultured lung cancer cell lines were investigated regarding the possible identification of volatile organic compounds as potential biomarkers. Gas samples from the headspace of pure culture medium and from the cultures of human lung adenocarcinoma cell lines A549 and Lu7466 were exposed to polypropylene fleece in order to absorb odour components. Sniffer dogs were trained with loaded fleeces of both cell lines, and honey bees were trained with fleeces exposed to A549. Afterwards, their ability to distinguish between cell-free culture medium odour and lung cancer cell odour was tested. Neither bees nor dogs were able to discriminate between odours from the cancer cell cultures and the pure culture medium. Solid phase micro extraction followed by gas chromatography with mass selective detection produced profiles of volatiles from the headspace offered to the animals. The profiles from the cell lines were largely similar; distinct differences were based on the decrease of volatile culture medium components due to the cells' metabolic activity. In summary, cultured lung cancer cell lines do not produce any biomarkers recognizable by animals or gas chromatographic analysis.
Wie viele Forschergruppen, haben auch wir uns das langfristige Ziel gesetzt, einen Beitrag bei der Beantwortung der Frage zu leisten, was Hunde riechen, wenn sie Krebs erschnüffeln.
Dabei sollen die Hunde nicht nur anzeigen, ob eine Atemluftprobe positiv oder negativ ist, sondern sie sollen auch aktiv eingebunden werden in den systematischen Suchprozess nach detektierbaren Biomarkern. So ist geplant, dass mittels eines präparativen Fraktionssammlers definierte Schnitte des Gaschromatogramms einzeln oder in möglichen Kombinationen auf das Adsorbervlies gebracht werden, um im Hundetraining eingesetzt zu werden. In analoger Weise könnte auch mit spezifischen Kandidatensubstanzen verfahren werden.
Pyrolysis and fire behaviour of a phosphorus polyester (PET-P-DOPO) have been investigated. The glycol ether of the hydroquinone derivative of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was used as a reactive halogen-free flame retardant in PET-P-DOPO. PET-P-DOPO is proposed as an alternative to poly(butylene terephthalate) (PBT) with established halogen-free additives. It exhibits a high LOI (39.3%) and achieves V-0 classification in the UL 94 test. Three different mechanisms (flame inhibition, charring and a protection effect by the intumescent char) contribute to the flame retardancy in PET-P-DOPO and were quantified with respect to different fire risks. The fire load was reduced by 66% of the PBT characteristic. The reduction is the superposition of the relative reduction due to flame inhibition (factor 0.625) and charring (factor 0.545). The peak of heat release rate (pHRR) was reduced by 83% due to flame inhibition, charring and the protection properties of the char (factor 0.486). The strength of all three mechanisms is in the same order of magnitude. The intumescent multicellular structure enables the char to act as an efficient protection layer. PBT flame-retarded with aluminium diethylphosphinate was used as a benchmark to assess the performance of PET-P-DOPO absolutely, as well as versus the phosphorus content. PET-P-DOPO exhibits superior fire retardancy, in particular due to the additional prolongation of the time to ignition and increase in char yield. PET-P-DOPO is a promising alternative material for creating halogen-free flame-retarded polyesters.
Pyrolysis, fire behaviour and mechanical properties of a blend of poly(butylene terephthalate) (PBT) with a phosphorus polyester (PET-P-DOPO) are investigated and compared with PBT/aluminium diethylphosphinate (AlPi-Et) composites. The PBT/PET-P-DOPO is immiscible and exhibits gas-phase and condensed-phase activity, whereas AlPi-Et in PBT results mainly in flame inhibition. Only higher loadings of AlPi-Et yield significant condensed-phase activity. Using the same phosphorus content, PBT/PET-P-DOPO and PBT/AlPi-Et exhibit similar reductions in fire load (22%) and flame spread (17% assessed by fire growth rate, FIGRA), compared with PBT. In contrast to AlPi-Et, the addition of PET-P-DOPO does not decrease the tensile strength of PBT. Thus, PET-P-DOPO is an interesting alternative to low-molecular-weight flame retardants.
Odor Perception by Dogs: Evaluating Two Training Approaches for Odor Learning of Sniffer Dogs
(2017)
In this study, a standardized experimental set-up with various combinations of herbs as odor sources was designed. Two training approaches for sniffer dogs were compared; first, Training with a pure reference odor, and second, training with a variety of odor mixtures with the target odor as a common denominator. The ability of the dogs to identify the target odor in a new context was tested. Six different herbs (basil, St. John’s wort, dandelion, marjoram, parsley, ribwort) were chosen to produce reference materials in various mixtures with (positive) and without (negative)chamomile as the target odor source. The dogs were trained to show 1 of 2 different behaviors, 1 for the positive, and 1 for the negative sample as a yes/no task. Tests were double blind with one sample presented at a time. In both training approaches, dogs were able to detect chamomile as the target odor in any presented mixture with an average sensitivity of 72% and a specificity of 84%. Dogs trained with odor mixture containing the target odor had more correct indications in the transfer task.
Since the beginnings of the European American Workshops (EAW) in 1997, the aim was to gather the experts in NDE reliability and discuss burning topics with the aim of identifying crucial problems and suggesting ways to move forward. This was usually achieved during the so-called break-out sessions, in which predetermined topics were discussed. During the 5th EAW, held in Berlin in 2013, this approach was replaced by an Open Space Technology (OST) approach. The benefit of this approach is seen in the freedom of topic choices, i. e., the topics are not predetermined but rather arise at that moment in that space and by the participants choice. The following topics arose: new reliability methods (Bayesian, MAPOD,
), structural health monitoring, definition of requirements of NDE by customer versus provider, what value of POD is good enough?, human factors, manual versus automated inspection, and basic concepts of reliability of NDE. The participants were encouraged to walk from one session to another and openly express their opinions. These were in the end summarized by a chosen group of moderators and presented in this paper.
To assess the suitability of asymmetric cyanine dyes for in vivo fluoro-optical molecular imaging, a comprehensive study on the influence of the number of negatively charged sulfonate groups governing the hydrophilicity of the DY-67x family of asymmetric cyanines was performed. Special attention was devoted to the plasma protein binding capacity and related pharmacokinetic properties. Four members of the DY-67x cyanine family composed of the same main chromophore, but substituted with a sequentially increasing number of sulfonate groups (n = 1−4; DY-675, DY-676, DY-677, DY-678, respectively), were incubated with plasma proteins dissolved in phosphate-buffered saline. Protein binding was assessed by absorption spectroscopy, gel electrophoresis, ultrafiltration, and dialysis. Distribution of dye in organs was studied by intraveneous injection of 62 nmol dye/kg body weight into mice (n = 12; up to 180 minutes postinjection) using whole-body near-infrared fluorescence imaging. Spectroscopic studies, gel electrophoresis, and dialysis demonstrated reduced protein binding with increasing number of sulfonate groups. The bovine serum albumin binding constant of the most hydrophobic dye, DY-675, is 18 times higher than that of the most hydrophilic fluorophore, DY-678. In vivo biodistribution analysis underlined a considerable influence of dye hydrophilicity on biodistribution and excretion pathways, with the more hydrophobic dyes, DY-675 and DY-676, accumulating in the liver, followed by strong fluorescence signals in bile and gut owing to accumulation in feces and comparatively hydrophilic DY-678-COOH accumulating in the bladder. Our results demonstrate the possibility of selectively controlling dye-protein interactions and, thus, biodistribution and excretion pathways via proper choice of the fluorophore's substitution pattern. This underlines the importance of structure-property relationships for fluorescent labels. Moreover, our data could provide the basis for the rationalization of future contrast agent developments.
We investigate the dynamics of semiconductor lasers subject to time-delayed optical Feedback from the perspective of dynamical self-injection locking. Based on the Lang-Kobayashi model, we perform an analysis of the well-known Low Frequency Fluctuations (LFFs) in the frequency-intensity plane. Moreover, we investigate a recently found dynamical regime of fragmented LFFs by means of a locking-range analysis, spectral comparison and precursor pulse identification. We show that LFF dynamics can be explained by dynamical optical injection locking due to the delayed optical feedback. Moreover, the fragmented LFFs occur due to a re-injection locking induced by a particular optical pulse structure in the chaotic feedback dynamics. This is corrobo-rated by experiments with a semiconductor laser experiencing delayed feedback from an optical fiber loop. The dynamical nature of the feedback injection results in an eventual loss, but also possible regaining, of the locking, explaining the recently observed phenomenon of fragmented LFFs.
Flame retarded poly(butylene terephthalate) (PBT) is required for electronic applications and is mostly achieved by low molar mass additives so far. Three phosphorus-containing polyesters are suggested as halogen-free and polymeric flame retardants for PBT. Flame retardancy was achieved according to cone calorimeter experiments showing that the peak heat release rate and total heat evolved were reduced because of flame inhibition and condensed-phase activity. The presented polymers containing derivatives of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide form immiscible blend systems with PBT. Shear-rheology shows an increase in storage moduli at low frequencies. This is proposed as quantitative measure for the degree of phase interaction. The phase structure of the blends depends on the chemical structure of the phosphorus polyester and was quite different, depending also on the viscosity ratio between matrix and second phase. A lower viscosity ratio leads to two types of phases with spherical and additionally continuous droplets. Addition of the flame retardants showed no influence on the dielectric properties but on the mechanical behavior. The polymeric flame retardants significantly diminish the impact strength because of several reasons: (1) high brittleness of the phosphorus polyesters themselves, (2) thermodynamic immiscibility, and (3) weak phase adhesion. By adding a copolymer consisting of the two base polymers to the blend, an improvement of impact strength was obtained. The copolymer particularly acts as compatibilizer between the phases and therefore leads to a smaller phase size and to a stronger phase adhesion due to the formation of fibrils.
PET-P-DOPO is a phosphorus-containing polyester prepared from the glycol ether of the hydroquinone derivative of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and dimethyl terephthalate. PET-P-DOPO and a blend of PBT with PET-PDOPO were investigated with respect to pyrolysis and fire behavior. PET-P-DOPO achieves a V-0 rating in the UL 94 test and exhibits a high LOI of 39.3%. The outstanding flame-retardant properties of PET-P-DOPO are the result of three different mechanisms (flame inhibition, charring and a protection effect of the intumescent char) that are active in PET-P-DOPO. The fire load and the peak of heat release rate (pHRR) are reduced to 34% and 17%, respectively. The char exhibits an intumescent multicellular structure enabling it to act as an efficient protection layer. As PET-P-DOPO is immiscible with PBT, the blend shows a lower breaking elongation than pure PBT. Compared to pure PET-P-DOPO, the flame retardancy of the blend is decreased according to the fraction of PET-P-DOPO used. Nevertheless, the flame-retardancy of PET-P-DOPO in the blend was good enough to compete with PBT flame-retarded by AlPi-Et (aluminum diethylphosphinate) that was used as a Benchmark.
Background: Gas sensors are very important in several fields like gas monitoring, safety and environmental applications. In this approach, a new gas sensing concept is investigated which combines the powerful adsorption probability of metal oxide conductive sensors (MOS) with an optical ellipsometric readout. This concept Shows promising results to solve the problems of cross sensitivity of the MOS concept.
Results: Undoped tin oxide (SnOx) and iron doped tin oxide (Fe:SnOx) thin add-on films were prepared by magnetron sputtering on the top of the actual surface plasmon resonance (SPR) sensing gold layer. The films were tested for their sensitivity to several gas species in the surface plasmon resonance enhanced (SPREE) gas measurement. It was found that the undoped tin oxide (SnOx) shows higher sensitivities to propane (C3H8) then to carbon monoxide (CO). By using Fe:SnOx, this relation is inverted. This behavior was explained by a change of the amount of binding sites for CO in the layer due to this iron doping. For hydrogen (H2) no such relation was found but the sensing ability was identical for both layer materials. This observation was related to a different sensing mechanism for H2 which is driven by the Diffusion into the layer instead of adsorption on the surface.
Conclusion: The gas sensing selectivity can be enhanced by tuning the properties of the thin film overcoating. A relation of the binding sites in the doped and undoped SnOx films and the gas sensing abilities for CO and C3H8 was found. This could open the path for optimized gas sensing devices with different coated SPREE sensors.
Der vorliegende Bericht beschreibt Konzepte für eine intelligente Brücke auf der Grundlage einer zuverlässigkeitsbasierten Zustandsbewertung unter Berücksichtigung von Bauwerksinformationen, welche aus Prüfungen, Inspektionen und Überwachung gewonnen werden. Das Brückensystem wird durch ein Modell beschrieben, welches den zentralen Teil des Konzeptes darstellt. Das Modell wird in Schädigungsmodelle und ein Tragwerkssystem-Modell unterteilt. Dieses Modell wird a-priori durch die Eingangsdaten (welche etwa die Geometrie, die Materialien und die Verwendung der Brücke beschreiben) charakterisiert. Aus diesen ergeben sich dann auch die Ausgangsmodelle. Um die signifikanten Streuungen und Unsicherheiten adäquat abzubilden sind diese Modelle probabilistisch. Das Modell liefert eine sich kontinuierlich ändernde probabilistische Zustandsbewertung. Die Zustandsbewertung gibt eine Aussage über den Zustand und die Zuverlässigkeit des Brückensystems und seiner Bauteile und dient als Grundlage für die Planung und die Optimierung von Maßnahmen. Die Verwendung von Resultaten aus Inspektionen, Prüfungen und Überwachungen erfolgt durch eine Aktualisierung der Modellparameter. Die Aktualisierung beruht auf der Methode der Bayes'schen Aktualisierung und wird auf der Grundlage der entwickelten Klassifizierung der Bauwerksinformationen mit entsprechenden Methoden durchgeführt. Dieses Verfahren erlaubt es, alle Informationen in konsistenter Weise in ein einziges Modell einfließen zu lassen. Dabei wird die Genauigkeit und Aussagekraft der gewonnenen Daten und Beobachtungen explizit berücksichtigt. Durch die Aktualisierung der Modellparameter unter Berücksichtigung von Systemeffekten wird die Zustandsbewertung der Bauteile und des Brückensystems aktualisiert. Das ermöglicht die Planung und die Optimierung von Maßnahmen unter Berücksichtigung der Bauwerksinformationen. Auf diese Weise wird die intelligente Brücke mit Inspektionen und Überwachungen zu einem adaptiven System, welches sich Veränderungen anpassen kann.---------------------------------------------------------------------------------------------------------------------------------------------------------------------------This report describes concepts for an intelligent bridge on the basis of a reliability-based condition assessment utilizing inspection and monitoring data. The central part of the concept is a model describing the bridge system. The overall bridge model is comprised of deterioration models and a mechanical system model of the structure. The model is a-priori characterized by the input data (such as the geometry, the materials, and the utilization of the bridge). Significant uncertainties in the deterioration modeling as well as the load conditions motivate a probabilistic modeling. The model enables a continuously updated probabilistic condition assessment. It provides information about the condition and the reliability of the bridge system and its components and serves as a basis for the planning and the optimization of maintenance actions. Inspection, measurement, and monitoring information are included by updating the model parameters. Bayesian updating is utilized for the updating of the model parameters and is performed on the basis of the developed classification of structural information and the corresponding procedures. These methodologies allow to consistently incorporate all available information into the model and the prediction. Thereby, the precision and the validity of the data and observations are explicitly accounted for. The condition assessment of the bridge system and its components is updated by updating the model parameters, and maintenance actions can be planned and optimized taking into account all available information in a rational and consistent manner. In this way, the intelligent bridge with inspections, measurements, and monitoring information becomes an adaptive system, which has the ability to adjust to changes.
A software prototype is developed for assessing and updating the reliability of single-cell prestressed concrete box girders subjected to chloride-induced reinforcement corrosion. The underlying system model consists of two integrated sub-models: a condition model for predicting the deterioration state of the box girder and a structural model for evaluating the overall system reliability. The condition model is based on a dynamic Bayesian network (DBN) model which considers the spatial variation of the corrosion process. Inspection data are included in the calculation of the system reliability through Bayesian updating on the basis of the DBN model. To demonstrate the effect of partial inspections, the software prototype is applied to a case study of a typical highway bridge with six spans. The case study illustrates that it is possible to infer the condition of uninspected parts of the structure due to the spatial correlation of the corrosion process.
Inspection and maintenance of concrete bridges is a major cost factor in transportation infrastructure, and there is significant potential for using information gained during inspection to update predictive models of the performance and reliability of such structures. In this context, this paper presents an approach for assessing and updating the reliability of prestressed concrete bridges subjected to chloride-induced reinforcement corrosion. The system deterioration state is determined based on a Dynamic Bayesian Network (DBN) model that considers the spatial variability of the corrosion process. The overall system reliability is computed by means of a probabilistic structural model coupled with the deterioration model. Inspection data are included in the system reliability calculation through Bayesian updating on the basis of the DBN model. As proof of concept, a software prototype is developed to implement the method presented here. The software prototype is applied to a typical highway bridge and the influence of inspection information on the system deterioration state and the structural reliability is quantified taking into account the spatial correlation of the corrosion process. This work is a step towards developing a software tool that can be used by engineering practitioners to perform reliability assessments of ageing concrete bridges and update their reliability with inspection and monitoring data.
Dieser Bericht beschreibt ein Systemmodell für eine integrale Ermittlung und Prognose der Schadens- und Zustandsentwicklung der Elemente eines Brückensystems unter Berücksichtigung von Ergebnissen aus Inspektionen und Überwachung. Das Systemmodell wurde anhand eines ausgesuchten Spannbetonüberbaus in einzelliger Kastenbauweise entwickelt. Es besteht aus zwei integralen Teilmodellen: ein Modell zur Beschreibung des Systemschädigungszustandes und ein Modell zur Beschreibung der Standsicherheit. Für die Modellierung des stochastischen Systemschädigungszustandes eines Brückensystems werden dynamische Bayes'sche Netze (DBN) vorgeschlagen. Dieser Ansatz ermöglicht es, alle relevanten Schädigungsprozesse und deren stochastische Abhängigkeiten zu berücksichtigen. Ein wesentlicher Vorteil dieses Ansatzes ist es, dass DBN ideal dafür geeignet sind, Bayes'sche Aktualisierungen auf Grundlage von Informationen aus Inspektionen und Überwachungsmaßnahme auf eine effiziente und robuste Art und Weise durchzuführen. Der DBN-Ansatz ist deshalb für die Entwicklung von Software für das Erhaltungsmanagement von alternden Brückenbauwerken, die vom Benutzer keine vertieften Kenntnisse der Zuverlässigkeitstheorie verlangt, ideal geeignet. Für die Modellierung der Standsicherheit eines alternden Kastenträgers wird vereinfachend Biegeversagen des globalen Längssystems betrachtet. Zur Berechnung der maximalen Traglast eines Kastenträgers infolge des Systemschädigungszustandes wird ein plastisch-plastisches Verfahren eingesetzt, wobei die Beanspruchungen mittels der Fließgelenktheorie unter Ausnutzung der plastischen Beanspruchbarkeit der Querschnitte des Kastenträgers ermittelt werden. Ein Kastenträger versagt, wenn sich durch die Ausbildung einer ausreichend großen Anzahl von Fließgelenken eine kinematische Kette ausbildet. Dieser Modellierungsansatz berücksichtigt Redundanzen, die sich aus der plastischen Beanspruchbarkeit der Querschnitte und der statischen Unbestimmtheit eines Kastenträgers ergeben. Zum Nachweis der praktischen Einsetzbarkeit des entwickelten Systemmodells wurde ein Software-Prototyp entwickelt, der eine intuitiv benutzbare graphische Benutzeroberfläche (Front-End) mit einem Berechnungskern (Back-End) koppelt. Die aktuelle Version des Software-Prototyps implementiert ein Modell der chloridinduzierten Bewehrungskorrosion und ein Tragwerksmodell, welches das Verfahrens der stetigen Laststeigerung zur Bestimmung der maximalen Traglast des Kastenträgers auf der Grundlage eines Finite-Elemente-Modells umsetzt. Zur Durchführung von Bayes'schen Aktualisierungen des Systemschädigungszustandes auf der Grundlage des DBN-Modells implementiert der Prototyp den Likelihood-Weighting-Algorithmus. Die entwickelte Architektur des Prototyps ermöglicht eine Erweiterung der Software um weitere Schädigungsprozesse. Der entwickelte Software-Prototyp ermöglicht Benutzern ohne vertiefte Kenntnisse der Zuverlässigkeitstheorie eine Berechnung des Einflusses von Bauwerksinformationen auf den Systemschädigungszustand und die Tragsicherheit eines Kastenträgers. Auf dieser Grundlage können effiziente Inspektions- und Überwachungsmaßnahmen identifiziert und das Erhaltungsmanagement optimiert werden.
Der Frequenzbereich der Terahertzwellen liegt im elektromagnetischen Spektrum zwischen den Mikrowellen und dem infraroten Licht – also etwa im Bereich von 0,1 bis 10 Terahertz (THz). Der VDI-Statusreport „Terahertzsysteme und Anwendungen“ stellt die unterschiedlichen Konzepte für Terahertzsysteme vor und zeigt Anwendungsbeispiele, bei denen die Terahertztechnik erfolgreich eingesetzt wird. Umfangreiche Literaturangaben ermöglichen eine intensivere Beschäftigung mit allen Themen des VDI-Statusreports.
Electrical and optical applications based on micro- and nanoparticles have specific demands on their interfacial properties. These properties are strongly related to atmospheric conditions to which the particles were exposed during their formation. In this study, metallic In microparticles are synthesized by solidification of In droplets on an amorphous Mo substrate at normal pressure and under vacuum conditions. The influence of ambient pressure on the interface and surface shape is investigated. While solidification at atmospheric pressure leads to collapsed particles with undisturbed contact to the substrate, low pressures result in smooth spherical particles but with cavities inside. Numerical simulations with COMSOL Multiphysics reveal different temperature profiles and heat flux in particles during solidification for both cases. This indicates different starting conditions of the solidification, which leads to the described phenomenon eventually. The investigation of the varying process conditions on the particle shape in combination with the calculated and measured temperature curves over time gives valuable insights into new approaches to synthesize micro- and nanoparticles with defined interfacial properties. Both ambient pressure and cooling rate provide well-controllable and reliable parameters for the realization of different interfacial shapes.
Diese Richtlinie definiert Kenngrößen und Messverfahren, um Terahertzsysteme für die Zeitbereichsspektroskopie (TDS)zu spezifizieren. So können Hersteller ihre Systeme übereinstimmend beschreiben und Anwender einfach Systeme vergleichen. Systeme für die Terahertz-Zeitbereichsspektroskopie sind aktive Systeme und nutzen verschiedene Techniken sowohl zur Erzeugung als auch zur zeitaufgelösten Messung von breitbandigen Terahertzimpulsen. Die dazugehörigen Terahertzspektren und -Phasen werden nach einer zeitlichen Abtastung über eine Fourier-Transformation berechnet. In dieser Richtlinie wird ein Überblick über die Funktionsweisen von Zeitbereichsspektrometern gegeben, die eingesetzten Messverfahren näher erläutert sowie die benötigten Begriffe und Kenngrößen definiert. Die Richtlinie konzentriert sich dabei auf Systeme, die auf sogenannten Abtastmessverfahren (Sampling-Messverfahren) basieren.
The surface structure, in particular the surface roughness, and the surface chemistry of titanium implants influence their anchoring in bone. The aim of this study was to analyse metal-bone contact (MBC) after modification of the implant surface, using different materials for blasting. The surface modification of titanium was produced by blasting it with particles made of Al2O3 or bioceramics. The biological effects were then investigated experimentally using 27 rabbits, analysed after 7, 28 and 84 days after the implantation of titanium cylinders treated accordingly. The MBC showed a tendency for more bone after bioceramics were used as a blasting material, compared to Al2O3.
Polystyrene nanoparticles (PS-NPs) were doped with an oxygen-sensitive near-infrared (NIR)-emissive palladium meso-tetraphenylporphyrin and an inert reference dye which are both excitable at 635 nm. The nanosensors were characterized with special emphasis on fundamental parameters such as absolute photoluminescence quantum yield and fluorescence lifetime. The PS-NPs were employed for ratiometric dual-wavelength and lifetime-based photoluminescent oxygen sensing. They were efficiently taken up by cultured murine alveolar macrophages, yielding a characteristic and reversible change in ratiometric response with decreasing oxygen concentration. This correlated with the cellular hypoxic status verified by analysis of hypoxia inducible factor-1α (HIF-1α) accumulation. In addition, the surface of PS-NPs was functionalized with polyethylene glycol (PEG) and the monoclonal antibody herceptin, and their binding to HER2/neu-overexpressing tumor cells was confirmed in vitro. First experiments with tumor-bearing mouse revealed a distinctive ratiometric response within the tumor upon hypoxic condition induced by animal sacrifice. These results demonstrate the potential of these referenced NIR nanosensors for in vitro and in vivo imaging that present a new generation of optical probes for oncology.
In the present study the incorporation of iron into an organic polymer, composed of formamidine subunits [R–N=C(H)–NH–R], has been examined. The catalytic ability of the recyclable material was investigated in the iron-catalyzed formation of C–C bonds. After optimization of the reaction conditions, excellent yields and chemoselectivities were feasible.
Nichtrostende Stähle gewinnen durch ihre Vielseitigkeit bei Bau, Sanierung und Einrichtung von Schwimmbädern seit einigen Jahren zunehmende Bedeutung. Neben der hohen Korrosionsbeständigkeit vermitteln die überlegenen hygienischen Eigenschaften sowie der geringe Inspektions- und Instandhaltungsaufwand ein beständiges Gefühl von Dauerhaftigkeit und Sicherheit. Voraussetzung dafür ist die richtige Wahl von Werkstoffsorte, Oberfläche, Bauweise und Reinigungstechnik.