Ingenieurwissenschaften und zugeordnete Tätigkeiten
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The implementation of fluorescent methods is of outstanding importance in the field of optical chemical sensor Technology and biosciences. Their bioanalytical applications are manifold including fluorescence microscopy, fluorescence in situ hybridization, DNA sequencing, fluorescence-activated cell sorting, immunoassays, analysis of DNA and Protein microarrays, and quantitative PCR, just to name a few examples. Particularly, fluorescence microscopy is a valuable method in the versatile field of biomedical imaging methods which nowadays utilizes different fluorescence Parameters like emission wavelength/Color and lifetime for the discrimination between different targets. Sectional Images are available with confocal microscopes. Tissue, cells or single cellular compartments can be stained and visualized with fluorescent dyes and biomolecules can be selectively labeled with fluorescent dyes to Monitor biomolecular interactions inside cells or at Membrane bound receptors.
On the other hand , fluorophores can act as indicator (or "molecular probe") to visualize intrinsically colorless and non-fluorescent ionic and neutral analytes such as pH, Oxygen (pO2), metal ions, anions, hydrogen peroxide or bioactive small organic molecules such as Sugars or nucleotides. Thereby, their photoluminescent properties (fluorescence or phoporescence intensity, exitation and/or Emission wavelength, emission lifetime or anisotropy) respond to the presence of these species in their immediate Environment. In general, the use of luminescent probes has the advantage that they can be delivered directly into the sample, and detected in a contactless remote mode. By now, these probes are often encapsulated in different types of nanoparticles (NPs) made from (biodegradable) organic polymers, biopolymers or inorganic materials like silica or bound to their surface.
Damage of PE-HD induced by liquid media - Full Notch Creep Testing (FNCT) and Imaging analysis
(2017)
Due to the increasing demand for utilization and improvement of energy efficient materials, especially concerning requirements in lightweight construction and design, polyolefin materials are used extensively and in an increasingly broad range of applications.
Although loaded with stresses under yield stress, preformed voids, inhomogeneities or notches can possibly lead to damage and unexpected failure induced by liquid media in polyolefin materials. For PE-HD, slow crack growth (SCG) as well as environmental stress cracking (ESC) are relevant damage mechanisms. SCG appears without influence of a surrounding medium or in “inert” media whereas ESC occurs in “active” media, which have decisive influence on damage mechanism and time to failure.
To characterize the inherent resistance of the material against those damage mechanisms, the Full-Notch Creep Test (FNCT) is widely used. Therefore, the FNCT is of paramount importance particularly for the assessment of pipe and blow molding types of PE-HD – especially for automotive but also for most other high-performance applications.
In this study, the FNCT – usually applied as a standardized testing method (ISO 16770) using a few universal model liquid media – is extended by investigations of selected relevant PE-HD materials with a variety of properties also in real media. Mainly topical fuels, customary in the market such as diesel and biodiesel are examined. Especially the influence of temperature, and the ESC behavior of PE-HD in media that are sorbed to a significant extent, are addressed.
The investigations were performed using a novel FNCT-device with 12 individual sub-stations, each equipped with individual electronic stress and temperature control and continuous online monitoring of the specimen elongation.
Additional to acquired results concerning time to failure and elongation behavior, imaging techniques, such as light microscopy (LM), laser scanning microscopy (LSM) and X-ray computed tomography (CT scan) were utilized to obtain data concerning crack propagation and media migration. Correlations of elongation behavior and data derived from imaging analysis such as fracture plane roughness were obtained.
In this review we present new concepts and recent progress in the application of semiconductur quantum dots (QD) as labels in two important areas of biology, bioimaging and biosensing. We analyze the biologically relevant properties of QDs focusing on the following topics: QD surface treatment and stability labeling of cellular structures and receptors with QDs, incorporation of QDs in living cells, cytotoxicity of QDs and influence of the biolocical environment on the biological and optical properties of QDs. Initially, we consider utilization of QDs as agants in high-resolution bioimaging techniques that can provide information at the molecular levels. The deverse range of modern live-cell QD-based imaging techniques with resolution far beyond the diffraction limit of light is examined. In each technique, we discuss the pros and cons of QD use and deliberate how QDs can be further engineered to facilitate their application in the respective imaging techniques and to produce significant improvements in resolution. Then we review QD-based point-of-care bioassays, bioprobes, and biosensors designed in different formats ranging from analytic biochemistry assays and ELISA, to novel point-of-care smartphone integrated QD-based biotests. Here, a wide range of QD-based fluorescence bioassays with optical transduction, electrochemiluminescence and photoelectrochemical assays are discussedc. Finally, this review provides an analysis of the prospects of application of QDs in selected important Areas of biology.
One of today’s major problems in many technical plants as well as fuel tanks is Microbial induced corrosion (MIC), leading to considerable damage and huge financial losses. Successful prevention of MIC requires the localization of first signs of corrosion as well as the identification of factors influencing the corrosion process. Hence, there is a growing need for sensitive and preferably inexpensive tools that enable the early detection of MIC. Of utmost importance are methods, which provide spatially and time-resolved information and allow the determination of corrosion rates at sites of interest for possible prevention of MIC.