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Ultrasonic imaging of tendon ducts enables the precise localisation of grouting faults in many cases. Additionally to well known criteria for detecting grouting faults in tendon ducts recently new possibilities were developed. Two main effects influence the complex behaviour of wave propagation and reflection: a) different arrangement and number of strands or internal rebars; b) superposition of reflecting signals and different wave modes propagating into the interface region around the tendon duct. In order to understand the experimental results, EFIT modelling is performed (EFIT: Elastodynamic Finite Integration Technique).
The key objective of this work is to create a comprehensive comparison between experimental analysis methods for detecting crosslinking reaction in EVA encapsulant material during PV module fabrication process. Several analytical methods, spanning from classical gel content extraction measurements over different thermo-analytic and mechanical approaches to spectroscopic analysis as Thermally Stimulated Current (TSC), have been investigated as to their ability to reveal the crosslinking state of ethylene vinyl acetate (EVA). The basic results show that TSC complements perfectly other thermal analysis methods like as Differential Scanning Calorimetry (DSC), Dynamic Mechanical Thermal Analysis (DMTA) to determine fundamental properties of EVA such as molecular mobility characteristics and also to monitor the crosslinking reaction. Exothermic peak as revealed by DSC analysis can be used to estimate the crosslinking rate of EVA during PV module encapsulation process as fast quality control test. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
L'objectif principal de ce travail est de permettre une meilleure compréhension entre les différentes techniques analyses expérimentales pour détecter la réaction de réticulation au niveau de lencapsulant Ethylène-Vinyle Acétate (EVA), durant le process de fabrication d'un module PV. Plusieurs méthodes d'analyse, allant du test classique d'extraction du taux de gel aux différentes techniques d'analyses thermomécaniques ainsi que les techniques d'analyse de spectroscopie comme le courant stimulé thermiquement (TSC), ont été étudiés pour permettre de révéler le phénomène de la réaction de réticulation de l'encapsulant l'EVA. Les résultats de base montrent que la TSC complète parfaitement d'autres méthodes d'analyses thermiques comme la calorimétrie différentielle à balayage (DSC), l'analyse mécanique dynamique (DMTA) pour déterminer les propriétés fondamentales de l'EVA. Ces techniques permettent de déterminer les caractéristiques relatives à la mobilité moléculaire et aussi pour mieux mettre en évidence la réaction de réticulation. Le pic exothermique comme révélé par l'analyse par DSC, peut être utilisé pour estimer le taux de réticulation de l'EVA au cours du process d'encapsulation du module PV comme un test rapide de contrôle de qualité.
Silicon photonic micro-ring resonators (MRR) developed on the silicon-on-insulator (SOI) platform, owing to their high sensitivity and small footprint, show great potential for many chemical and biological sensing applications such as label-free detection in environmental monitoring, biomedical engineering, and food analysis. In this tutorial,we provide the theoretical background and give design guidelines for SOI-based MRR as well as examples of surface functionalization procedures for label-free detection of molecules. After introducing the advantages and perspectives of MRR, fundamentals of MRR are described in detail, followed by an introduction to the fabrication methods, which are based on a complementary metal-oxide semiconductor (CMOS) technology. Optimization of MRR for chemical and biological sensing is provided, with special emphasis on the optimization of waveguide geometry. At this point, the difference between chemical bulk sensing and label-free surface sensing is explained, and definitions like waveguide sensitivity, ring sensitivity, overall sensitivity as well as the limit of detection (LoD) of MRR are introduced. Further, we show and explain chemical bulk sensing of sodium chloride (NaCl) in water and provide a recipe for label-free surface sensing.
Silicon photonic micro-ring resonators (MRR) developed on the silicon-on-insulator (SOI) platform, owing to their high sensitivity and small footprint, show great potential for many chemical and biological sensing applications such as label-free detection in environmental monitoring, biomedical engineering, and food analysis. In this tutorial, we provide the theoretical background and give design guidelines for SOI-based MRR as well as examples of surface functionalization procedures for label-free detection of molecules.
After introducing the advantages and perspectives of MRR, fundamentals of MRR are described in detail, followed by an introduction to the fabrication methods, which are based on a complementary metal-oxide semiconductor (CMOS) technology. Optimization of MRR for chemical and biological sensing is provided, with special emphasis on the optimization of waveguide geometry. At this point, the difference between chemical bulk sensing and label-free surface sensing is explained, and definitions like waveguide sensitivity, ring sensitivity, overall sensitivity as well as the limit of detection (LoD) of MRR are introduced. Further, we show and explain chemical bulk sensing of sodium chloride (NaCl) in water and provide a recipe for label-free surface sensing.
The publicly available document encapsulates the first version of the Catalogue of Services of the future EC4Safenano Centre (CoS 2019).
The CoS 2019 is structured in 12 Service Categories and 27 Service Topics, for each of the 12 categories considered. This architecture configures a 12 x 27 matrix that allows ordering the potential EC4Safenano offer in 324 types of services/groups of services.
Each type of service/group of services is described, in a simple and friendly way, by means of a specific service sheet: the EC4Safenano - Service Data Sheet (EC4-SDS). These EC4-SDSs allow structuring and summarizing the information of each service, providing the customer with a concise view of characteristics of the service and also the contact details with the service provider.
The CoS 2019 deploys a map of services consisting of a set of 100 EC4-SDSs, covering 7 of the 12 Service Categories and 17 of the 27 Service Topics.
The harmonization of services is visualized as a future necessary step in EC4Safenano, in order to strengthen the offer and provide added value to customers with a growing offer of harmonized services in future versions of the CoS.
The information contained in this document is structured in 3 main sections, as follows:
• Catalogue structure. This section describes in short the main characteristics of the CoS 2019.
• Catalogue content. This section represents the core part of the document and encapsulates the set of 100 SDSs displaying the offer proposed by the CoS 2019.
• Online Catalogue. This section describes the resources implemented by EC4Safenano to facilitate the on-line consultation of the CoS 2019 by customers and other interested parties.
Short-range order has been investigated in Zr69.5Cu12Ni11Al7.5 and Zr41.5Ti41.5Ni17 metallic glasses using X-ray absorption spectroscopy and ab initio molecular dynamics simulations. While both of these alloys are good glass formers, there is a difference in their glass-forming abilities (Zr41.5Ti41.5Ni17 > Zr69.5Cu12Ni11Al7.5). This difference is explained by inciting the relative importance of strong chemical order, icosahedral content, cluster symmetry and configuration diversity.
Investigation of interphases between thermoplastic and thermosetting polymers - an AFM approach
(2002)
This paper focuses on the preparation and characterization of crystalline thin films of rare-earth-doped sesquioxides (Y2O3, Lu2O3) grown by pulsed laser deposition on single-crystal (0001) sapphire substrates. X-ray diffraction measurements show that the films with thicknesses between 1 nm and 500 nm were highly textured along the 111 direction. Using Rutherford backscattering analysis, the correct stoichiometric composition of the films was established. The emission and excitation spectra of europium-doped films with a thickness 100 nm look similar to those of the corresponding crystalline bulk material, whereas films with a thickness 20 nm show a completely different emission behavior.
To date, in the textile manufacturing process of warp knitting, trouble-shooting and process optimization mainly rely on empirical knowledge and experiments. This factor limits the achievable increase in productivity and quality. On the other hand, using simulations, different phenomena that affect the quality of the knitted fabric and the knitting process can be clarified in the run-up of the experiments. Consequently, an increase in quality and flexibility can be reached with reduced experimental effort. This paper presents a process simulation of the warp thread dynamics in the thread feeding system of a warp knitting machine. For this purpose, a continuum model of the warp thread that includes the spatial dynamics of the thread and the axial transport movement has been developed.
Advantage of a combined ultrasonic and eddy current examination for railway inspection trains
(2007)
Some years ago, two railway inspection trains (RIT) already equipped with ultrasound, had additional advanced eddy current techniques installed. Recently, a new RIT was equipped with a system that was designed, from the beginning, to employ a combination of these two techniques for non-destructive rail inspection. The eddy current technique has been developed to enable identification and evaluation of rolling contact fatigue (RCF) defects. The ultrasound technique is aimed at measurements in the rail bulk volume, which are not feasible using the eddy current technique. Experience gained from application has shown that clear improvement on rail inspection can be achieved. For example, following Deutsche Bahn DB (German Rail) AG guideline, defects which are classified as group 2 using ultrasound testing can be further labelled as 'distinguished positions' if, for example, head checking can be identified in the same position using the eddy current technique. In other words, the new technique is capable of identifying two fundamentally different types of defects occurring at the same location. Such defects can then be classified as Group 1, equivalent according to the DB AG guideline. Furthermore, problem cases in the past, such as the decision whether a weld or rail joint is present for a fishing table, can be reliably determined using additional information from the eddy current technique. In this paper, examples will be provided to demonstrate application.
Aluminas resulting from sols prepared via a modified Yoldas procedure were studied with differential thermal analysis (DTA), differential thermal gravimetrie (DTG), 27Al nuclear magnetic resonance (27Al MAS NMR) and X-ray diffraction (XRD) concerning their thermal properties, aluminum speciation and phase content.
Hydrolysis of aluminum-sec-butoxide in aluminum nitrate solutions allowed to prepare stable sols with varying NO3-/Al molar ratios, solids contents and pH values. Resulting sols contained different aluminum species including also Al13 polycations. Sol preparation conditions also determined aluminum speciation in solid products obtained after thermal treatments of gels obtained from these sols. Al13 polycations and AlO5 species were found to play an important role for thermally induced transformation from amorphous products via eta-Al2O3 to alpha-Al2O3. Intermediately formed eta-Al2O3 promotes the phase transformation to alpha-Al2O3.
The Scythica Vindobonensia, the new fragments on Gothic incursions into Roman provinces in the Balkans in the middle of the third century AD that were revealed some years ago in a Greek palimpsest at the Austrian National Library in Vienna (ÖNB), are commonly considered as one of the most important additions of the last decades to the corpus of texts from classical Antiquity. Tere is a high degree of confdence among scholars in supposing that the fragments come from the lost work Scythica written in Greek by the third-century historian P. Herennius Dexippus (Δέξιππος) of Athens. The new fragments have hence also been called Dexippus Vindobonensis. In his Scythica, Dexippus recorded wars of the Romans with the Goths (and other tribes) whom he called Scythians.
The work had been hitherto known only from excerpts and quotes by later authors. Eight pages of a Byzantine manuscript copy of the ancient text have survived hidden underneath the visible surface of the last four parchment folios of the Vienna manuscript Historicus graecus 73, f. 192r -195v4. The copy is written in a Greek calligraphic minuscule which has been estimated by palaeographers to be of the middle or the second half of the eleventh century. In the thirteenth century, the text (on each of the eight pages arranged in one column, with 30 lines per page) was washed of the parchment and the valuable material made from animal skin was re-used for Christian texts. The new writing largely covered the faded remnants of the original text. It thus became hidden from the human eye for more than seven hundred years. Its discovery by Jana Grusková, a classical philologist specialized in the transmission of Greek texts, resulted from a systematic review of all Greek palimpsests kept at the Austrian National Library in Vienna at the beginning of the twenty-first century and a detailed examination of the four folios in 2007-20097.
The molecular dynamics of addition-type poly(tricyclononenes) with Si-substituted bulky side groups has been investigated by a combination of neutron time-of-flight and neutron backscattering spectroscopy methods on a time scale from 0.1 ps to ca. 3 ns. The investigated poly(tricyclononenes) PTCNSi1 and PTCNSi2g both bear a high microporosity which makes them promising candidates for active separation layers for gas separation membranes. At least for larger gas molecules it is assumed that the pathways for diffusion require an enlargement of pre-existing micropores in terms of an activated zone. A low temperature relaxation process was found for both polymers by the performed neutron scattering experiments. This process was assigned to the methyl group rotation. It was analysed in terms of a jump diffusion in a three-fold potential. The analysis of the dependence of the elastic incoherent structure factor on the scattering vector yields the number of methyl groups which might be immobilized. For PTCNSi1 (3 methyl groups in the monomeric unit) it was found that all methyl groups take part in the methyl group rotation whereas for PTCNSi2g (6 methyl groups in monomeric unit) a considerable number of methyl groups are blocked in their rotation. This immobilization of methyl groups is due to the sterically demanding arrangement of the methyl groups in PTCNSi2g. This conclusion is further supported by the result that the activation energy for the methyl group rotation is three times higher for PTCNSi2g than that of PTCNSi1.
A Large Aperture UltraSonic (LAUS) system has been designed and built for testing thick concrete structures. The scalable system consists of twelve ultrasonic units, each hosting 32 individual shear wave transducers with mechanical dry point contact (DPC) to the concrete surface. The twelve units are attached to the concrete surface using a vacuum case which holds them in place during operation. Each LAUS unit can be placed individually depending on the surface condition and optimal ultrasonic condition, e.g. rebar position. Air pressure is supplied to each unit through an air hose. The following extended abstract is a short version of an article to be published in the special edition of ASCE JIS that will describe the outline of the system, the principle of functioning, the data processing and adapted reconstruction calculation based on SAFT as well as the system performance during first applications.
Inhalt ist die zerstörungsfreie Detailuntersuchung von Holzbauteilen mit einem dreidimensional abbildenden Ultraschall-Echoverfahren. Das neu entwickelte 3D-Verfahren berücksichtigt den anisotropen Aufbau des Holzes. Die Bildschnitte und Projektionen werden aus flächigen Ultraschallaufnahmen berechnet. Die Messungen erfolgen an Probekörpern sowie an Bauteilen aus der Praxis. In dem Forschungsvorhaben wird die für Holz neue 3D-Rekonstruktionsrechnung verwendet und mit dem Ziel weiterentwickelt, unter Berücksichtigung der anisotropen Struktur des Holzes eine dreidimensional aufgelöste Abbildung von Reflektoren im Inneren der Holzbauteile zu ermöglichen. Damit werden die bisher für Holzbauteile zur Verfügung stehenden Verfahren entscheidend ergänzt, weil nun eine hochgenaue dreidimensionale Abbildung erreichbar ist (Auflösung: 20 mm und besser).
Die ZfP versucht mit Hilfe von Messdaten, die sie aus z. B. einer Impuls-Echo-Messung gewinnt, Rückschlüsse auf die innere Struktur eines Objektes zu ziehen. Bei Betonbauteilen sollen im Besonderen Verpressfehler, die dann zur Korrosion und damit zur einer Beeinträchtigung der Standsicherheit und Dauerhaftigkeit des Konstruktion (z. B. einer Spannbetonbrücke) führen können, schnell und mit einer hohen Sicherheit aus den Messdaten lokalisiert werden. Das konventionellen SAFT oder FT-SAFT-Verfahren liefern in Verbindung mit einer Phasenauswertung einen schnellen und sicheren Hinweis darauf, dass ein Lufteinschluss/Defekt vorliegt. Darüber hinaus können jedoch Rückausbreitungs-Verfahren, wenn ein gutes Geschwindigkeitsprofil vorliegt, eine wesentlich bessere Lokalisierung des Defekts bieten als SAFT-Verfahren, jedoch mit dem Nachteil, dass sie sehr zeit- und rechenintensiv sind, vor allem im Dreidimensionalen. Als Mittelweg kann hierzu die "One-Way"-Methode dienen. Diese Methode verwendet Pseudo-Differential-Operatoren und ist sehr robust auch bei relativ groben Geschwindigkeitsprofilen. Sie wird an Beispielen aus der Bauwerkdiagnose mit den konventionellen Verfahren verglichen.
Besonders beim Bauen im Bestand und der Bauwerkserhaltung werden zur Bestimmung des Tragvermögens von historischen, oft unter Denkmalschutz stehenden, natursteinernen Bauteilen Materialkennwerte benötigt. Die üblichen Verfahren mittels Probeentnahme am Objekt und Bestimmung der Kennwerte im Labor bedeuten bei Denkmälern einen massiven Eingriff und sollten vermieden werden. Vermehrt wird daher der Einsatz von zerstörungsfreien Untersuchungsmethoden erforscht und angewendet. Eine dieser Methoden stellt die Ultraschallprüfung dar.
The cure behaviour of a specific ethylene vinyl acetate material as used for encapsulation of photovoltaic modules was analysed by rheometer, differential scanning calorimetry and Fourier transform infrared spectroscopy to test for a suitable replacement for the laborious determination of gel content. The results show that all applied methods are capable of describing the effects of the cross-linking process. Some provide results very similar to those yielded by analysis of the insoluble content, but the question remains as to whether indirect methods should be preferred over the direct measurement of physical properties, e.g. as performed by the curemeter. A material stored for one year was also tested to demonstrate the effect of extended storage on cure behaviour and how this is detected by different methods. This complements the other methods, which were clearly able to detect the different cure behaviour of the aged EVA, whereas determination of the gel content could not.
A Large Aperture UltraSonic system (LAUS) has been designed and built for testing thick concrete structures. The scalable system consists of twelve ultrasonic units, each hosting 32 individual shear wave transducers with mechanical dry point contact (DPC) to the concrete surface. The twelve units are attached to the concrete surface using a vacuum case which holds them in place during operation. Each LAUS unit can be placed individually on the surface to achieve optimal ultrasonic condition, e.g. to avoid rebars. For the generation of vacuum, air pressure is supplied to each unit through an air hose. The twelve units define an aperture which is necessary for fast reconstruction of the subsurface structure. The well-known SAFT (Synthetic Aperture Focusing Technique) algorithm has been adopted to this situation, where the individual LAUS units form a linear aperture with not necessarily equidistant spacing between the units. The exact geometrical position of the units, which are individually marked with retroreflective labels, is determined using photographs and image processing. All transducers are synchronized and work either as transmitter or receiver. A full scan consists of 12 * 11 recordings, where each unit acts as transmitter once and all others as receivers. An electronic sub-unit on the back of the ultrasonic device holds the battery and handles data acquisition, synchronization and data communication. A computer is used as base unit which communicates with each LAUS unit for control and data acquisition, the synchronization is performed by a radio modem that uses a special algorithm similar to a digital PLL (phase locked loop). No wire connections are necessary between the units and the base system.
The LAUS system is designed to investigate concrete structures with thicknesses in excess of 2 m, depending on the acoustic condition of the object under investigation. Highly reinforced concrete may have less penetration depth. The LAUS provides quasi real time imaging, once the transducers are put in place and the data has been acquired. First measurements on a foundation slab confirm, that the system can register ultrasonic echoes from the back wall at 4 m distance.
Effect of well dispersed amorphous silicon dioxide in flame retarded styrene butadiene rubber
(2013)
Spherically shaped amorphous silicon dioxide with broad size particle distribution was used in combination with aluminium trihydroxide (ATH) in styrene butadiene rubber composites. The pyrolysis, flammability, fire properties, flame spread and gas diffusion were investigated. The kind and amount of ATH, but in particular the fine silicon dioxide chosen as an additive, influenced the thermal decomposition and fire behaviour of styrene butadiene rubber composites. Gravimetric gas sorption measurements showed that the gas diffusion was systematically lower with silicon dioxide. The initial pyrolysis gas release was hindered, increasing the temperature at which decomposition begins as well as the ignition time in fire tests. During combustion, ATH and silicon dioxide accumulate on the surface of the specimen, forming a residual protective layer. A reduced peak heat release rate and fire spread were observed. The addition of a special kind of silicon dioxide is proposed to play a key role in optimising fire retardancy.
The determination of magnetic distortion fields caused by inclusions hidden in a
conductive matrix using homogeneous current flow needs to be addressed in multiple tasks of
electromagnetic non-destructive testing and materials science. This includes a series of testing
problems such as the detection of tantalum inclusions hidden in niobium plates, metal inclusion in
a nonmetallic base material or porosity in aluminum laser welds. Unfortunately, straightforward
tools for an estimation of the defect response fields above the sample using pertinent detection
concepts are still missing. In this study the Finite Element Method (FEM) was used for modeling
spherically shaped defects and an analytical expression developed for the strength of the response
field including the conductivity of the defect and matrix, the sensor-to-inclusion separation and the
defect size. Finally, the results also can be useful for Eddy Current Testing problems, by taking the
skin effect into consideration.
The primary screening of hybridoma cells is a time-critical and laborious step during the development of monoclonal antibodies. Often, critical errors occur in this phase, which supports the notion that the generation of monoclonal antibodies with hybridoma technology is difficult to control and hence, a risky venture. We think that it is crucial to improve the screening process to eliminate most of the critical deficits of the conventional approach. With this new microarray-based procedure, several advances could be achieved: Selectivity for excellent binders, high-throughput, reproducible signals, avoidance of misleading avidity (multivalency) effects, and performance of simultaneous competition experiments. The latter can also be used to select clones of desired cross-reactivity properties. In this paper, a model system with two excellent clones against carbamazepine, two weak clones, and blank supernatant containing fetal bovine serum was designed to examine the effectiveness of the new system. The excellent clones could be detected largely independent of the immunoglobulin G (IgG) concentration, which is usually unknown during the clone screening since the determination and subsequent adjustment of the antibody concentration are not feasible in most cases. Furthermore, in this approach, the enrichment, isolation, and purification of IgG for characterization is not necessary. Raw cell culture supernatant can be used directly, even when fetal calf serum (FCS) or other complex media is used. In addition, an improved method for the oriented antibody-immobilization on epoxy-silanized slides is presented. Based on the results of this model system with simulated hybridoma supernatants, we conclude that this approach should be preferable to most other protocols leading to many false positives, causing expensive and lengthy elimination steps to weed out the poor clones.
The illegal use of explosives by terrorists and other criminals is an increasing issue in public spaces, such as airports, railway stations, highways, sports venues, theaters, and other large buildings. Security in these environments can be achieved by different means, including the installation of scanners and other analytical devices to detect ultra-small traces of explosives in a very short time-frame to be able to take action as early as possible to prevent the detonation of such devices. Unfortunately, an ideal explosive detection system still does not exist, which means that a compromise is needed in practice. Most detection devices lack the extreme analytical sensitivity, which is nevertheless necessary due to the low vapor pressure of nearly all explosives. In addition, the rate of false positives needs to be virtually zero, which is also very difficult to achieve. Here we present an immunosensor system based on kinetic competition, which is known to be very fast and may even overcome affinity limitation, which impairs the performance of many traditional competitive assays. This immunosensor consists of a monolithic glass column with a vast excess of immobilized hapten, which traps the fluorescently labeled antibody as long as no explosive is present. In the case of the explosive 2,4,6-trinitrotoluene (TNT), some binding sites of the antibody will be blocked, which leads to an immediate breakthrough of the labeled protein, detectable by highly sensitive laser-induced fluorescence with the help of a Peltier-cooled complementary metal-oxide-semiconductor (CMOS) camera. Liquid handling is performed with high-precision syringe pumps and chip-based mixing-devices and flow-cells. The system achieved limits of detection of 1 pM (1 ppt) of the fluorescent label and around 100 pM (20 ppt) of TNT. The total assay time is less than 8 min. A cross-reactivity test with 5000 pM solutions showed no signal by pentaerythritol tetranitrate (PETN), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). This immunosensor belongs to the most sensitive and fastest detectors for TNT with no significant cross-reactivity by non-related compounds. The consumption of the labeled antibody is surprisingly low: 1 mg of the reagent would be sufficient for more than one year of continuous biosensor operation.
The primary screening of hybridoma cells is a time-critical and laborious step during the development of monoclonal antibodies. Often critical errors occur in this phase, which supports the notion that the generation of monoclonal antibodies with hybridoma technology is difficult to control and hence a risky venture. We think that it is crucial to improve the screening process to eliminate most of the immanent deficits of the conventional approach. With this new microarray-based procedure, several advances could be achieved: Selectivity for excellent binders, high throughput, reproducible signals, avoidance of misleading avidity (multivalency) effects, and simultaneous performance of competition experiments. The latter can directly be used to select clones of desired cross-reactivity properties. In this paper, a model system with two excellent clones against carbamazepine, two weak clones and blank supernatant has been designed to examine the effectiveness of the new system. The excellent clones could be detected largely independent of the IgG concentration, which is unknown during the clone screening since the determination and subsequent adjustment of the antibody concentration is not possible in most cases. Furthermore, in this approach, the enrichment, isolation, and purification of IgG for characterization is not necessary. Raw cell culture supernatant can be used directly, even when fetal calf serum (FCS) or other complex media had been used. In addition, an improved method for the oriented antibody-immobilization on epoxy-silanized slides is presented. Based on the results of this model system, we conclude that this approach should be preferable to most other protocols leading to many of false positives, causing expensive and lengthy confirmation steps to weed out the poor clones.
CMOS-Compatible Silicon Photonic Sensor for Refractive Index Sensing Using Local Back-Side Release
(2020)
Silicon photonic sensors are promising candidates for lab-on-a-chip solutions with versatile applications and scalable production prospects using complementary metal-oxide semiconductor (CMOS) fabrication methods. However, the widespread use has been hindered because the sensing area adjoins optical and electrical components making packaging and sensor handling challenging. In this work, a local back-side release of the photonic sensor is employed, enabling a separation of the sensing area from the rest of the chip. This approach allows preserving the compatibility of photonic integrated circuits in the front-end of line and metal interconnects in the back-end of line. The sensor is based on a micro-ring resonator and is fabricated on wafer-level using a CMOS technology. We revealed a ring resonator sensitivity for homogeneous sensing of 106 nm/RIU.
In this work, a cost-effective optofluidic system is proposed and preliminary experimental results are presented. A microfluidic channel monolithically integrated into a photonic integrated circuit technology is used in conjunction with a cyclic olefin copolymer (COC) substrate to provide fluidic in- and output ports. We report on initial experimental results as well as on the simple and cost-effective fabrication of this optofluidic system by means of micro-milling.
The trafficking of illegal drugs by criminal networks at borders, harbors, or airports is an increasing issue for public health as these routes ensure the main supply of illegal drugs. The prevention of drug smuggling, including the installation of scanners and other analytical devices to detect small traces of drugs within a reasonable time frame, remains a challenge. The presented immunosensor is based on a monolithic affinity column with a large excess of immobilized hapten, which traps fluorescently labeled antibodies as long as the analyte cocaine is absent. In the presence of the drug, some binding sites of the antibody will be blocked, which leads to an immediate breakthrough of the labeled protein, detectable by highly sensitive laser-induced fluorescence with the help of a Peltier-cooled complementary metal-oxide-semiconductor (CMOS) camera. Liquid handling is performed with high-precision syringe pumps and microfluidic chip-based mixing devices and flow cells. The biosensor achieved limits of detection of 7 ppt (23 pM) of cocaine with a response time of 90 s and a total assay time below 3 min. With surface wipe sampling, the biosensor was able to detect 300 pg of cocaine. This immunosensor belongs to the most sensitive and fastest detectors for cocaine and offers near-continuous analyte measurement.
The trafficking of illegal drugs by criminal networks at borders, harbors, or airports is an increasing issue in public health as these routes ensure the main supply of illegal drugs. The prevention of drug smuggling, including the installation of scanners and other analytical devices to detect ultra-small traces of drugs within a reasonable time frame, remains a challenge. The presented immunosensor is based on a monolithic affinity column with a large excess of immobilized hapten, which traps fluorescently labeled antibodies as long as the analyte cocaine is absent. In the presence of the drug, some binding sites of the antibody will be blocked, which leads to an immediate breakthrough of the labeled protein, detectable by highly sensitive laser-induced fluorescence with the help of a Peltier-cooled complementary metal-oxide-semiconductor (CMOS) camera. Liquid handling is performed with high-precision syringe pumps and microfluidic chip-based mixing devices and flow cells. The biosensor achieved limits of detection of 23 pM (7 ppt) of cocaine with a response time of 90 seconds and a total assay time below 3 minutes. With surface wipe sampling, the biosensor was able to detect 300 pg of cocaine. This immunosensor belongs to the most sensitive and fastest detectors for cocaine and offers near-continuous analyte measurement.
BioPIC - Integration of Biosensors based on Photonic Integrated Circuits by Local-Backside Etching
(2020)
Silicon photonic sensors are promising candidates for lab-on-a-chip solutions with versatile applications and scalable production prospects using complementary metal-oxide semiconductor (CMOS) fabrication methods. However, the widespread use has been hindered because the sensing area adjoins optical and electrical components making packaging and sensor handling challenging. In this work, a local back-side release of the photonic sensor is employed, enabling a separation of the sensing area from the rest of the chip. This approach allows preserving the compatibility of photonic integrated circuits in the front-end of line and metal interconnects in the back-end of line.
Scanning force microscopy (SFM) has been used to assess the local mechanical properties of fibre-reinforced polymers. Using a sinusoidal displacement modulation (DM) and lock-in technique the method allows to characterize local viscoelastic properties with a high lateral resolution. The simultaneous measurement of the local electrical conductivity is proposed which facilitates the interpretation of the mechanical data. The investigation of cross-sections perpendicular to the axis of carbon fibres embedded in PPS delivers some information about the change in local stiffness within the interfacial region. As a first approach, assuming a single-exponential decrease in local stiffness along a radial line from fibre to polymer we find characteristic decay lengths which are distributed in a range between 20 and 80nm. Further, a modified DM-mode is proposed which is expected to provide a contrast enhancement of the signal which is related to local stiffness. This can be achieved by installing an additional feedback loop which keeps constant the amplitude of dynamic indentation (CDI-mode).
Cardiac troponin I (cTnI) is a crucial biomarker for diagnosing cardiac vascular diseases, including acute myocardial infarction (AMI). This study presents a proof-of-concept chemiluminescence-based immunosensor for rapid and accurate measurement of cTnI, with the potential for online monitoring. The immunosensor incorporates a flow cell design and a sensitive complementary metal-oxide-semiconductor (CMOS) camera for optical readout. A microfluidic setup was established to enable selective and quasi-online determination of cTnI within ten minutes. The sensor was tested with recombinant cTnI in phosphate buffer, demonstrating measurements in the concentration range of 2–25 µg/L, with a limit of detection (LoD) of 0.6 µg/L (23 pmol/L) achieved using the optimized system. The immunosensor exhibited high selectivity, as no cross-reactivity was observed with other recombinant proteins such as cTnT and cTnC at a concentration of 16 µg/L. Measurements with diluted blood plasma and serum yielded an LoD of 60 µg/L (2.4 nmol/L) and 70 µg/L (2.9 nmol/L), respectively. This biosensor offers a promising approach for the rapid and sensitive detection of cTnI, contributing to the diagnosis and management of acute myocardial infarction and other cardiac vascular diseases.
The limited availability of accurate experimental data in wide ranges of pressure, temperature, and composition is the main constraining factor for the proper development and assessment of thermodynamic models and equations of state. In the particular case of carbon capture and storage (CCS) processes, there is a clear need for data sets related to the (carbon dioxide + oxygen) mixtures that this work aims to address. This work provides new experimental (p, rho, T) data for three binary (CO2 + O2) mixtures with mole fractions of oxygen x(O2) = (0.05, 0.10, and 0.20) mol/mol, in the temperature range T = (250 to 375) K and pressure range p = (0.5 to 13) MPa. The measurements were performed with a high-precision single-sinker densimeter with magnetic suspension coupling. The density data were obtained with estimated expanded relative uncertainties of 0.02 % for the highest densities and up to 0.3 % for the lowest ones.The results were compared to the corresponding results calculated by the current reference equations of state for this kind of mixtures, namely the EOS-CG (combustion gases) and the GERG-2008 equation of state, respectively. The EOS-CG yields better estimations in density than the GERG-2008 equation of state. The results from the EOS-GC model show no systematic temperature dependence. For the GERG-2008 model, however, this criterion is significantly less fulfilled.
Methane dry reforming (DRM) was investigated over highly active Ni catalysts with low metal content (2.5wt%) supported on Mg-Al mixed oxide. The aim was to minimize carbon Deposition and metal sites agglomeration on the working catalyst which are known to cause catalyst deactivation.
The solids were characterized using N2 adsorption, X-ray diffraction, temperature-programmed reduction, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The results showed that MgO-Al2O3 solid solution phases are obtained when calcining Mg-Al hydrotalcite precursor in the temperature range of 550–800 °C. Such phases contribute to the high activity of catalysts with low Ni content even at low temperature (500 °C). Modifying the catalyst preparation with citric acid significantly slows the coking rate and reduces the size of large octahedrally coordinated NiO-like domains, which may easily agglomerate on the surface during DRM. The most effective Ni catalyst shows a stable DRM course over 60 h at high weight hourly space velocity with very low coke deposition. This is a promising result for considering such catalyst systems for further development of an industrial DRM technology.
A novel stationary phase for affinity separations is presented. This material is based on sintered borosilicate glass readily available as semi-finished filter plates with defined porosity and surface area. The material shows fast binding kinetics and excellent long-term stability under real application conditions due to lacking macropores and high mechanical rigidity. The glass surface can be easily modified with standard organosilane chemistry to immobilize selective binders or other molecules used for biointeraction. In this paper, the manufacturing of the columns and their respective column holders by 3D printing is shown in detail. The model system protein A/IgG was chosen as an example to examine the properties of such monolithic columns under realistic application conditions. Several specifications, such as (dynamic) IgG capacity, pressure stability, long-term performance, productivity, non-specific binding, and peak shape, are presented. It could be shown that due to the very high separation speed, 250 mg antibody per hour and column can be collected, which surpasses the productivity of most standard columns of the same size. The total IgG capacity of the shown columns is around 4 mg (5.5 mg/mL), which is sufficient for most tasks in research laboratories. The cycle time of an IgG separation can be less than 1 min. Due to the glass material’s excellent pressure resistance, these columns are compatible with standard HPLC systems. This is usually not the case with standard affinity columns, limited to manual use or application in low-pressure systems. The use of a standard HPLC system also improves the ability for automation, which enables the purification of hundreds of cell supernatants in one day. The sharp peak shape of the elution leads to an enrichment effect, which might increase the concentration of IgG by a factor of 3. The final concentration of IgG can be around 7.5 mg/mL without the need for an additional nano-filtration step. The purity of the IgG was > 95% in one step and nearly 99% with a second polishing run.
EXAFS analysis of pure elements, binary and ternary equiatomic refractory alloys within the Nb-Zr-Ti-Hf- Ta system is performed at the Nb and Zr K-edges to analyze the evolution of the chemical local environ- ment and the lattice distortion. A good mixing of the elements is found at the atomic scale. For some compounds, a distribution of distances between the central atom and its neighbors suggests a distortion of the structure. Finally, analysis of the Debye-Waller parameters shows some correlation with the lat- tice distortion parameter δ², and allows to quantify experimentally the static disorder in medium entropy alloys.
A novel stationary phase for affinity separations is presented. This material is based on sintered borosilicate glass readily available as semi-finished filter plates with defined porosity and surface area. The material shows fast binding kinetics and excellent long-term stability under real application conditions due to lacking macropores and high mechanical rigidity. The glass surface can be easily modified with standard organosilane chemistry to immobilize selective binders or other molecules used for biointeraction. In this paper, the manufacturing of the columns and their respective column holders by 3D printing is shown in detail. The model system protein A/IgG was chosen as an example to examine the properties of such monolithic columns under realistic application conditions. Several specifications, such as (dynamic) IgG capacity, pressure stability, long-term performance, productivity, non-specific binding, and peak shape, are presented. It could be shown that due to the very high separation speed, 250 mg antibody per hour and column can be collected, which surpasses the productivity of most standard columns of the same size. The total IgG capacity of the shown columns is around 4 mg (5.5 mg/mL), which is sufficient for most tasks in research laboratories. The cycle time of an IgG separation can be less than 1 minute. Due to the glass material's excellent pressure resistance, these columns are compatible with standard HPLC systems. This is usually not the case with standard affinity columns, limited to manual use or application in low-pressure systems. The use of a standard HPLC system also improves the ability for automation, which enables the purification of hundreds of cell supernatants in one day. The sharp peak shape of the elution leads to an enrichment effect, which might increase the concentration of IgG by a factor of 3. The final concentration of IgG can be around 7.5 mg/mL without the need for an additional nanofiltration step. The purity of the IgG was > 95% in one step and nearly 99% with a second polishing run.
We present a new high resolution X-ray imager based on a pnCCD detector and a polycapillary optics. The properties of the pnCCD like high quantum efficiency, high energy resolution and radiation hardness are maintained, while color corrected polycapillary lenses are used to direct the fluorescence photons from every spot on a sample to a corresponding pixel on the detector. The camera is sensitive to photons from 3 to 40 keV with still 30% quantum efficiency at 20 keV. The pnCCD is operated in split frame mode allowing a high frame rate of 400 Hz with an energy resolution of 152 eV for Mn Kα (5.9 keV) at 450 kcps. In single-photon counting mode (SPC), the time, energy and position of every fluorescence photon is recorded for every frame. A dedicated software enables the visualization of the elements distribution in real time without the need of post-processing the data. A description of the key components including detector, X-ray optics and camera is given. First experiments show the capability of the camera to perform fast full-field X-Ray Fluorescence (FF-XRF) for element analysis. The imaging performance with a magnifying optics (3×) has also been successfully tested.
Pilot studies have been carried out at the BAMline at BESSY II in collaboration with the Bundesanstalt
für Materialforschung und -prüfung (BAM) on metal- and metalloid-containing compounds in biological
samples after electrophoretic protein separation. After sodium dodecylsulfate polyacrylamide gel
electrophoresis (SDS-PAGE) and transfer onto a blotting membrane the distribution of selenium among
the proteins of testis homogenate of a rat and a wallaby was determined. The comparison with the
autoradiogram of 75Se-labeled proteins separated in the same way showed that of nine seleniumcontaining
proteins found in rat testis homogenate by autoradiography four could be detected by
synchrotron radiation X-ray fluorescence analysis (SRXRF).
Absorption effects in total reflection X-ray fluorescence (TXRF) analysis are important to consider, especially if external calibration is to be applied. With a color X-ray camera (CXC), that enables spatially and energy resolved XRF analysis, the absorption of the primary beam was directly visualized for mL-droplets and an array of pL-droplets printed on a Si-wafer with drop-on-demand technology. As expected, deposits that are hit by the primary beam first shade subsequent droplets, leading to a diminished XRF signal. This shading effect was quantified with enhanced precision making use of sub-pixel analysis that improves the spatial resolution of the camera. The measured absorption was compared to simulated results using three different model calculations. It was found they match very well (average deviation < 10%). Thus errors in quantification due to absorption effects can be accounted for in a more accurate manner.
Metakaolin-based alkali activated mortars (AAM) - with and without CuSO4·5H2O and ZnO addition (mass ratio Mn+/solid binder 0.08% to 1.7%) - were casted and exposed within an extensive long-term field campaign over the period of 20 months to a sewer basin, strongly affected by biogenic acid corrosion. (Un-)exposed AAM were tested regarding their physicochemical and microstructural properties, bioreceptivity and overall durability. Metal addition led to a retarding effect during alkali-activation reaction, as well as to an increase in open porosity of up to 3.0% and corresponding lower compressive strength of up to 10.9%. Reduced microbial colonization and diversity were observed on AAM with Cu, while Zn addition led to increased biodiversity. We propose that the observed higher durability of Cu-doped AAM is due to antibacterial effects and associated reduction of biogenic acid production, superseding overall negative effects of metal-dosage on physical material properties. Observed lower durability of Zn-doped AAM was related to combined negative physicochemical and microbial effects.
The development of earth-abundant catalysts for selective electrochemical CO2 conversion is a central challenge. Cu-Sn bimetallic catalysts can yield selective CO2 reduction toward either CO or formate. This study presents oxide-derived Cu-Sn catalysts tunable for either product and seeks to understand the synergetic effects between Cu and Sn causing these selectivity trends. The materials undergo significant transformations under CO2 reduction conditions, and their dynamic bulk and surface structures are revealed by correlating observations from multiple methods—X-ray absorption spectroscopy for in situ study, and quasi in situ X-ray photoelectron spectroscopy for surface sensitivity. For both types of catalysts, Cu transforms to metallic Cu0 under reaction conditions. However, the Sn speciation and content differ significantly between the catalyst types: the CO-selective catalysts exhibit a surface Sn content of 13 at. % predominantly present as oxidized Sn, while the formate-selective catalysts display an Sn content of ≈70 at. % consisting of both metallic Sn0 and Sn oxide species. Density functional theory simulations suggest that Snδ+ sites weaken CO adsorption, thereby enhancing CO selectivity, while Sn0 sites hinder H adsorption and promote formate production. This study reveals the complex dependence of catalyst structure, composition, and speciation with electrochemical bias in bimetallic Cu catalysts.
In the quest for finding the ideal synchrotron-radiation-induced imaging method for the investigation of trace element distributions in human bone samples, experiments were performed using both a scanning confocal synchrotron radiation micro X-ray fluorescence (SR-mXRF) (FLUO beamline at ANKA) setup and a full-field color X-ray camera (BAMline at BESSY-II) setup. As zinc is a trace element of special interest in bone, the setups were optimized for its detection. The setups were compared with respect to count rate, required measurement time and spatial resolution. It was demonstrated that the ideal method depends on the element of interest. Although for Ca (a major constituent of the bone with a low energy of 3.69 keV for its K alpha XRF line) the color X-ray camera provided a higher resolution in the plane, for Zn (a trace element in bone) only the confocal SR-µXRF setup was able to sufficiently image the distribution.
Besides conventional scanning X-ray fluorescence imaging at synchrotron sources, full-field X-ray fluorescence (FF-XRF) imaging techniques that do not implicitly require spatial scanning of the sample have become available. FF-XRF has become achievable thanks to the development of a new type of energy dispersive CCD-based 2D detector, also referred to as a 'color X-ray camera (CXC)' or 'SLcam'. We report on different imaging schemes for biological samples using FF-XRF imaging: (a) 2D 'zoom' imaging with pinhole optics using the 'camera obscura' principle; (b) 2D 'fixed magnification' imaging using magnifying polycapillary optics; and (c) 3D-FF-XRF imaging using an X-ray sheet beam or computed tomography (CT). The different FF-XRF imaging modes are illustrated using the crustacean Daphnia magna, a model organism for investigating the effects of metals on organism/ecosystem health, and foraminifera, a class of amoeboid protist. Detailed analytical characterization of the set-up is performed through analyzing various reference materials in order to determine limits of detection (LODs) and sensitivities. Experiments were performed using the BAMline at the BESSY synchrotron (Berlin, Germany) and using the P06 Hard X-ray Microprobe at the PETRAIII synchrotron (Hamburg, Germany).
The incorporation of colloidal quantum dots (QDs) into solid matrices, especially ionic salts, holds several advantages for industrial applications. Here, we demonstrated via absolute measurements of photoluminescence quantum yields (PL-QY) that the photoluminescence of aqueous CdTe QDs can be considerably increased upon incorporation into a salt matrix with a simple crystallization procedure. Enhancement factors of up to 2.8 and a PL-QY of 50 to 80%, both in NaCl crystals and incorporated in silicone matrices, were reached. The fact that the achievable PL enhancement factors depend strongly on PL-QY of the parent QDs can be described by the change of the dielectric surrounding and the passivation of the QD surface, modifying radiative and nonradiative rate constants. Time-resolved PL measurements revealed noncorrelating PL lifetimes and PL-QY, suggesting that weakly emissive QDs of the ensemble are more affected by the enhancement mechanism, thereby influencing PL-QY and PL lifetime in a different manner.
In situ secondary ion mass spectrometry (SIMS) analyses of δ7Li, Li/Ca, and Mg/Ca were performed on five synthetic aragonite samples precipitated from seawater at 25°C at different rates. The compositions of δ7Li in bulk aragonites and experimental fluids were measured by multicollector inductively coupled plasmamass spectrometry (MC-ICP-MS). Both techniques yielded similar δ7Li in aragonite when SIMS analyses were corrected to calcium carbonate reference materials. Fractionation factors α7Li/6Li range from 0.9895 to 0.9923, which translates to a fractionation between aragonite and fluid from -10.5‰ to -7.7‰. The within-sample δ7Li range determined by SIMS is up to 27‰, exceeding the difference between bulk δ7Li analyses of different aragonite precipitates. Moreover, the centers of aragonite hemispherical bundles (spherulites) are enriched in Li/Ca and Mg/Ca relative to spherulite fibers by up to factors of 2 and 8, respectively. The Li/Ca and Mg/Ca ratios of spherulite fibers increase with aragonite precipitation rate. These results suggest that precipitation rate is a potentially important consideration when using Li isotopes and elemental ratios in natural carbonates as a proxy for seawater composition and temperature.
Recent results from a three-year multi-disciplinary project on Ancient Egyptian gold jewellery revealed that items of jewellery from the Middle Kingdom to the New Kingdom were manufactured using a variety of alluvial gold alloys. These alloys cover a wide range of colours and the majority contain Platinum Group Elements inclusions. However, in all the gold foils analysed, these inclusions were found to be absent. In this work a selection of gilded wood and leather items and gold foil fragments, all from the excavations by John Garstang at Abydos (primarily from Middle Kingdom graves), were examined using Scanning Electron Microscopy-Energy Disperse Spectroscopy (SEM-EDS), X-Ray Fluorescence (µXRF), Particle Induced X-Ray Emission (µPIXE) and Double Dispersive X-Ray Fluorescence (D²XRF). The work allowed us to characterise the composition of the base-alloys and also to reveal the presence of Pt at trace levels, confirming the use of alluvial gold deposits. Corrosion products were also investigated in the foils where surface tarnish was visually observed. Results showed that the differences in the colour of corrosion observed for the foils are related not only to the thickness of the corrosion layer but also to a multi-layer structure containing the various corrosion products.
Absorption effects and the impact of specimen shape on TXRF analysis has been discussed intensively. Model calculations indicated that ring shaped specimens should give better results in terms of higher counts per mass signals than filled rectangle or circle shaped specimens. One major reason for the difference in signal is shading effects. Full field micro-XRF with a color X-ray camera (CXC) was used to investigate shading, which occurs when working with small angles of excitation as in TXRF. The device allows monitoring the illuminated parts of the sample and the shaded parts at the same time. It is expected that sample material hit first by the primary beam shade material behind it. Using the CXC shading could be directly visualized for the high concentration specimens.
In order to compare the experimental results with calculation of the shading effect the generation of controlled specimens is crucial. This was achieved by 'drop on demand' technology. It allows generating uniform, microscopic deposits of elements. The experimentally measured shadings match well with those expected from calculation.