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Die Anforderungen der modernen Infrastruktur machen schnell ausführbare Abdichtungs- und Brückenbelagssysteme für den Bundesfernstraßenbereich erforderlich. Dazu gibt es innovative Systemansätze, in denen unter Ausnutzung neuer asphalttechnologischer Erkenntnisse und Weiterentwicklungen innovative Belagsaufbauten in Ergänzung zum bestehenden technischen Regelwerk erarbeitet werden. Diese neuartigen Asphaltmaterialien mit verbesserten Asphalt-Gebrauchseigenschaften (Standfestigkeit; Tieftemperaturverhalten) werden durch Kombination mit neuartigen Flüssigkunststoffen zur Aufnahme von schnelle wiederholten Bewegungen (Rissüberbrückungseigenschaften) nochmals verbessert. Durch das optimierte Gebrauchsverhalten und die systembedingten technologischen Verbesserungen ist es bei Einhaltung besonderer materialtechnischer Anforderungen möglich, leistungsfähige Brückenabdichtungs- und Belagssysteme in deutlich schnellerer Bauzeit instandzusetzen bzw. im Neubau auszuführen. Die vorliegende Veröffentlichung verallgemeinert u. a. wissenschaftlich-technische Erkenntnisse der BAM und Erfahrungen im Umgang mit den spezialisierten Baustoffen in eine für die Straßenbaubehörden des Bundes und der Länder praktisch umsetzbare Weise.
Glass has different outstanding material-specific properties which offer theoretically the application of thin-walled hollow fibers in the field of high pressure gas storage. Especially the storage of hydrogen as renewable and environmental friendly energy carrier is possible. Glass is an amorphous material which is characterized by a theoretical tensile strength much higher than this of other materials. However, in practice the tensile strength is decreased significantly by defects on the glass surface or in the material and its network structure. As part of this thesis the burst pressures of hollow glass fibers were determined. The burst pressure correlates very well with the tensile strength of hollow glass fibers. By using the Weibull statistic the results of different test series were evaluated in respect to failure probabilities and compared to each other. Thereby the influence of various parameters on the pressure resistance was investigated. Beside the influence of the chemical composition of the material the aging by environmental and their effect on the pressure resistance was investigated. Additionally hollow glass fibers were loaded dynamically and statically with different gases. Afterwards the burst pressure was determined and the effect of used gas on the pressure resistance could be determined as well as the impact of method and duration of loading. A further influence of the dimension of hollow glass fibers on their resistance against inner pressure load is the ratio between wall thickness and inner diameter which was investigated as well as the combination of different glasses and the utilization of their disparate coefficient of thermal expansion which lead to prestressing of the hollow glass fiber. Finally, the impact of the variation of several production parameters on the pressure resistance was determined experimentally as like as the influence of surface coatings. These shall protect the glass surface from subsequently procured defects and, hence, increase the pressure resistance. As essential part of current thesis the defect analysis of test samples of various series was done whereby the differentiation between material and production dependent defects was important. Not only a light microscope but a scanning electron microscope was used for the investigation, as well. Beside volume defects like bubbles or inclusions surface defects in the form of scratches or spalling can be detected and observed. A calculation of the failure-causing defect size from measured burst pressure is possible. Dependent on the dimension and determined burst pressure value of each single fiber defect sizes of less than one micron were calculated. Particularly the geometry of the test samples inappropriate for many examination methods and the fact that the calculated defect size occurs only under loaded conditions at actual burst pressure the local detection of corresponding defect rendered impossible. In the end, the present thesis shows the pressure resistance of hollow glass fibers and their potential to store safely gases under high pressure.
Die quantitative Bestimmung der Haftfestigkeit von Beschichtungen ist von entscheidender Bedeutung sowohl für die Entwicklung als auch für die Qualitätssicherung. In einer Vergleichsstudie zur Haftfestigkeit von optischen und ophthalmischen Schichten wurde mit Hilfe der Zentrifugentechnologie der Einfluss verschiedener Parameter (Substratdicke, Oberflächenvorbehand-lung, Haftvermittler) auf die Haftfestigkeit optischer Schichten auf silikatischen und ophthalmischer Schichten auf polymeren Substraten untersucht.
Zur Bestimmung der Haftfestigkeit in der physikalisch korrekten Dimension Kraft pro Fläche im Stirnabzug stehen die Ein-Proben-Prüfung mit der Zugprüfmaschine und die Mehr-Proben-Prüfung mittels Zentri- fugentechnologie zur Verfügung. Die Zentrifugentechnologie wurde ausgewählt, da die Prüfung von bis zu acht Proben unter nahezu identischen Versuchsbedingungen und somit eine statistisch gesicherte Bestimmung der Haftfestigkeit möglich sind.
Es konnte nachgewiesen werden, dass die Substratdicke einen erheblichen Einfluss auf die gemessene Haftfestigkeit hat. Dies entspricht den Erwartungen, da es sich bei der Haftfestigkeit um eine System- eigenschaft des Schicht-Substrat-Systems handelt. Bei den Delaminationsbrüchen (DF) konnte zwischen Delamination des metallischen Reflektors (DF-R) und Delamination des Dielektrikums (DF-D) unter- schieden werden. Im Fall hinreichender Haftfestigkeit der Beschichtung traten auch Adhäsionsbrüche am Interface zum und Kohäsionsbrüche im Klebstoff auf. Nachfolgende Untersuchungen werden sich mit alternativen Klebstoffen und weiterentwickelten Fügestrategien befassen.
The influence of temperature and counterbody material on the tribological properties of a-C:H
coatings deposited on Cronidur 30 steel has been investigated in a lubricated ball on disk
contact situation with alpha-alumina and silicon nitride as counterbodies. The results show, that the wear volumes of the systems increase exponentially with increasing temperature, for alpha-alumina more than for silicon nitride. Two different wear mechanisms seem to have a
major influence: First, the abrasive action due to materials hardness and second, the tribo-oxidation when silicon nitride is counter material.
Many industrial processes are run at non-atmospheric conditions (elevated temperatures and pressures, other oxidizers than air). To judge whether and if yes to what extent explosive gas(vapor)/air mixtures will occur or may be generated during malfunction it is necessary to know the safety characteristic data at the respective conditions. Safety characteristic data like Explosion limits, are depending on pressure, temperature and the oxidizer. Most of the determination methods are standardized for ambient conditions.
In order to obtain determination methods for non-atmospheric conditions, particularly for higher initial pressures, reliable ignition criteria were investigated. Ignition tests at the explosion Limits were carried out for mixtures of methane, propane, n-butane, n-hexane, hydrogen, ammonia and acetone in air at initial pressures up to 20 bar. The tests have been evaluated according to different ignition criteria: visual flame propagation, temperature and pressure rising. It could be shown that flame propagation and occasionally self-sustained combustion for several seconds occurred together with remarkable temperature rise, although the pressure rise was below 3%. The results showed that the combination of a pressure rise criterion of 2% and a temperature rise criterion of 100 K seems to be a suitable ignition criterion for the determination of explosion limits and limiting oxidizer concentration at higher initial pressures and elevated temperatures. The tests were carried out within the framework of a R&D project founded by the German Ministry of Economics and Technology.
It is important to protect critical buildings (shopping centres, government buildings and embassies), infrastructure and utilities, train and underground stations from being damaged, destroyed or disrupted by deliberate acts of terrorism, criminal activity and malicious behaviour. Normal regulations and building guidelines do not generally take into account these threats. The introduction of appropriate regulations or guidelines, where deemed necessary, should enhance the resilience of buildings and infrastructures against explosion incidents. In order to protect the built infrastructure, testing methods are required which can answer the question whether certain building elements can withstand certain loading conditions created by an explosive event. The applicable state-of-the-art techniques may include either experimental or numerical methods, or a combination of both. Therefore, the thematic group (TG) on the resistance of structures to explosion effects was formed in order to bring the required expertise together, to make it commonly available and to find and define harmonised methods and solutions which can be provided to the decision-makers responsible for critical infrastructure protection. The TG described in a fist report JPC87202 the physical phenomena which have to be understood in order to ensure a proper testing of the elements and a correct interpretation of the results. In a second step, the differences between the existing standards for testing blast-resistant glazing and windows have been derived, and a basis for fundamental recommendations for the future development of the suite of European standards has been addressed JRC94930. Based on the prior findings, this report now formulates the proper enhancements of the existing standards in terms of actual recommendations for the improvement of the test standards.
The determination of the blast protection level of laminated glass windows and facades is of crucial importance, and it is normally done by using experimental investigations. In recent years numerical methods have become much more powerful also with respect to this kind of application. This report attempts to give a first idea of a possible standardisation concerning such numerical simulations. Attention is drawn to the representation of the blast loading and of the behaviour of the material of the mentioned products, to the geometrical meshing, as well as to the modelling of the connections of the glass components to the main structure. The need to validate the numerical models against reliable experimental data, some of which are indicated, is underlined.
The economic use of chemical admixtures depends on supply chains. Therefore, in most regions ins sub-Saharan Africa (SSA), the use of admixtures is not common practice. This amplifies the unfavorable framework for concrete construction such as fragmentary supply chains, high local cement prices, and unfavorable construction site facilities in this region significantly. The use of superplasticizer (SP) and stabilizing agents (STA) can enhance the concrete technology in SSA, since they can disassociate the concrete quality from external boundary influences. After providing a general overview of the peculiarities of the SSA boundary framework, economic concepts are provided, how existing material solutions can be significantly improved by the use of SPs and STAs based on locally available materials such as lignosulphonates and cassava starch. Finally a three step optimization process is described that helps developing flowable concrete based on materials that can be accessed in most locations in SSA.
Polysaccharides modify the rheological properties of cement based systems. Depending upon their chemistry, molecular architecture, and adsorption tendency, they have different modes of action. Some polysaccharides like diutan gum have strong effect on the fluid phase; others like starch strongly interact with particles. This paper presents effects of diutan gum and starches in presence of polycarboxylates. Rheometric investigations with varied particle volume fractions and increasing coarse aggregate diameters were conducted. The results show that starches have stronger influence on the rheology at high particle volume fractions than diutan gum. At lower particle volume fractions this trend is inverted. Experiments with aggregates sizes up to 16 mm (0.63 in.) indicate that stabilizing agent influences on the effects of aggregates on yield stress were small; however up to 1.0 mm (0.04 in.), a significant effect on the plastic viscosity could be observed, which levelled off at larger diameters.
In the past few years, the share of earthen building materials used in constructions in Central Europe has increased. That is due to growing acknowledgement of its qualities regarding balancing of humidity, absorption of odours and acoustical insulation.
To regulate these (mostly indoor) uses, the German Institute for Standardization (DIN) has published norms for adobe, earth mortar for masonry and earth plaster. In addition to these traditional building materials, earthen panels have been developed. As an ecological alternative to gypsum plaster boards, they combine climatic advantages of traditional materials with economic advantages of industrial processing, i.e. prefabrication and drywall techniques. Earthen panels are a composite layered material, comparable to Textile Reinforced Concrete (TRC). Most products contain an inner layer of reed tubes which improve the tensile strength and reduce the weight. Often, one or both surfaces are reinforced with a fibrous net to prevent cracks in the plastering that is usually applied on top. Additives range from straw to expanded clay. Special panels contain waxes that improve their heat storage capacity or water pipes to allow the usage as flat heating and cooling systems.
Als schweizweit einziger Hersteller produzierte die Gesellschaft der Ludwig von Roll'schen Eisenwerke seit den 1870er Jahren granulierte Hochofenschlacke. Im Blashochofen von Choindez im Schweizer Jura wird bis Mitte der 1920er Jahre Bohnerz aus dem Delsberger Becken, das kontemporär publizierten Analysen zufolge als Spuren- bzw. Schwermetalle Titan, Chrom, Blei und Vanadium enthält, zu grauem Roheisen verhüttet. In zementgebundenen Mörtelmischungen des 19. und frühen 20. Jahrhunderts aus verschiedenen Regionen der Schweiz finden sich neben reliktischen Hüttensandsplittern vereinzelt bis zu fünfhundert Mikrometer große scharze Kugeln mit grünlichem Schimmer, wohl nicht gemahlener Schlackensand. Deren mittels Ramanmikroskopie (Phasenbestand) und energiedispersiver Röntgenspektroskopie am Rasterelektronenmikroskop (Elementanalytik) ermittelte Mineralogie ergibt in Form von Plattnerit PbO2, Rutil TiO2 und vermitlich Chromit Fe(II)Cr2O4 bzw. Nichromit (Ni,Co,Fe(II))(Cr,Fe(III),Al)2)4 Übereinstimmungen mit den nur die Elementzusammensetzung berücksichtigenden historischen Resultaten. Ebenfalls im Zusammenhang mit dem das Bohnerz begleitenden Boluston samt Huppererde zu sehen sind die Minerale Coelestin SrSO4 und Zirkon ZrSiO4, des Weiteren der Siliciumcarbidpolymorph Moissanit SiC als Reaktionsprodukt von Quarzsand und Brennstoff. Die Kohärenz zwischen um die Jahrhundertwende durchgeführten Analysen von Rohmaterial als auch Ofenbruch aus dem in Choindez betriebenen Hochofen und den in diesem Beitrag diskutierten Resultaten moderner analytischer Methoden spricht für den Gebrauch von granulierter Schlacke aus dem Hause Ludwig von Roll als Mörtelzuschlag. Die Hüttensandkörner, eigentlich latent hydraulisch, sind aufgrund der fehlenden Aufbereitung zu grob für eine effektive Hydratation und deshalb trotz reaktiver Glasphase und Klinkermineralien (Belit Ca2SiO4 und Monocalciumaluminat CaAl2O4) intakt in der Bindemittelmatrix erhalten.
Diclofenac (DCF) wird als nicht-steroidales-antientzündliches Arzneimittel gegen Fieber, Entzündungen, rheumatische Erkrankungen und Schmerzen eingesetzt. 70 % werden nach Einnahme wieder ausgeschieden. Aufgrund unvollständiger Elimination in den Kläranlagen lassen sich Rückstände im Trinkwasser und im Oberflächengewässer nachweisen. Diclofenac wird in der Umweltanalytik v.a. mittels GC-MS oder LC-MS nachgewiesen. Bioanalytische Methoden machen sich die spezifische Antigen-Antikörper-Wechselwirkung zunutze, so z.B. Immunoassays. Die hierfür erforderlichen Antikörper werden durch Immunisierung mit einem Konjugat aus dem Analyten und einem Trägerprotein gewonnen. Die Kopplung kann direkt über die Carboxylfunktion von Diclofenac erfolgen. Um Abschirmungseffekte zu vermeiden, kann zwischen Protein und Analyt ein Spacer sinnvoll sein.
The design of sample flow cells, commonly used in online analytics and especially for medium resolution NMR spectroscopy (MR-NMR) in low magnetic fields, was experimentally and theoretically investigated by 1H-NMR and numerical simulations. The flow pattern was characterised to gain information about the residence time distribution and mixing effects. Both 1H-NMR imaging and spectroscopy were used to determine the characteristics of flow cells and their significance for on-line measurements such as reaction monitoring or hyphenated separation spectroscopy. The volume flow rates investigated were in the range from 0.1 to 10 ml/min, typically applied in the above mentioned applications. When compared to those commonly used in high-field NMR, the special characteristics of flow cells for MR-NMR were revealed by various NMR experiments and compared with CFD simulations. The influence of the design of the inlet and outlet on the flow pattern was investigated as well as the effect of the length of the cell. For practical use, a numerical estimation of the inflow length was given. In addition, it was shown how experiments on the polarisation build-up revealed insight into the flow characteristics in MR-NMR.
Experimental study and numerical simulation of hot crack formation for novel laser weldability test.
(2015)
Laser beam welding is a widely established manufacturing process in several industries. The solidification cracking seriously effecting the safety of welded joints could arise during the beam welding of stainless steels caused by high solidification rates. In this study the controlled tensile weldability test (CTW) was used to investigate the solidification cracking susceptibility the fully austenitic stainless steels CrMnNi (1.4376), CrNi (1.4301), CrNiMo (1.4404) and CrNiSi (1.4828) during laser beam welding. The test facility allows welding of specimens with simultaneous application of tensile load along or cross to the welding direction while the speed of tensile force application is either constant or increases linearly. The tensile force increment and/or the displacement are set by means of a CNC controller. Trials were conducted by varying the ultimate tensile strain and cross-head speed while keeping the welding parameters constant. By observing the crack-no crack behaviour and estimating the generated crack length for each trail using a new optimized experimental procedure the influence of the two important conditions (the strain and the strain rate) for the formation of solidification cracks can be investigated, the critical values of strain and strain rate that are responsible for solidification cracking formation have been determined. In the present study a three-dimensional FEM using the contact element technique was developed to simulate the solidification cracking during laser full penetration welding under external load conditions for the steel 1.4376 in order to get a better understanding of the mechanisms of hot crack initiation and the theoretical results were compared to the experimental ones. By comparing the resulting solidification crack with simulated crack, it is possible to determine the critical condition of solidification crack formation in the region where the strains and the strain rates cannot be measured due to the high temperature. The results show a good agreement between numerical calculation and experiment. It is proposed that the solidification cracking susceptibility may be predicted by FEM analysis by using the correct mechanical and thermo-physical constants of the materials.
An experimental investigation has been carried out to characterize and discriminate seven saffron samples and to verify their declared geographical origin using a voltammetric electronic tongue (VE-tongue). The ability of multivariable analysis methods such as Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA) to classify the saffron samples according to their geographical origin have been investigated. A good discrimination has reached using PCA and HCA in the VE-tongue characterization case. Furthermore, cross validation and Partial Least Square (PLS) techniques were applied in order to build suitable management and prediction models for the determination of safranal concentration in saffron samples based on SPME-GC-MS and UV-Vis Spectrophotometry. The obtained results reveals that some relationships were established between the VE-tongue signal, SPMEGC-MS and UV-Vis spectrophotometry methods to predict safranal concentration levels in saffron samples by using the PLS model. In the light of these results, we can say that the proposed electronic system offer a fast, simple and efficient tool to recognize the declared geographical origin of the saffron samples.
The new standard ‘ISO 17636-2:2013: Non-destructive testing of welds — Radiographic testing — Part 2: X- and gamma-ray techniques with digital detectors’, defines the practice for radiographic inspection of welded pipes for manufacturing and in-service inspection. It is applied in Europe for inspections of pipe welds in nuclear power plants as well as in chemical plants and allows a faster inspection with digital detector arrays (DDA) than with film. Nevertheless, it does not allow the evaluation of the depth and shape of volumetric and planar indications. In 2001 a planar tomography scanner, TomoCAR, was introduced for mechanized radiographic testing (RT) inspection and non-destructive measurement of cross sections. The project TomoWELD is based on a new concept of the scan geometry, an enhanced GPU based reconstruction, and the application of a new generation of photon counting DDAs based on CdTe crystal CMOS hybrids. The new detector permits the selection of energy thresholds to obtain an optimum energy range and reduction of the influence of scattered radiation. The concept and first measurements are presented. Flaw depth and shape of volumetric and planar irregularities can be determined.
Properties and application areas of photon counting and energy resolving digital detector arrays
(2015)
Since a few years the direct detection of X-ray photons into electrical signals is allowed by usage of highly absorbing photo conducting materials (e.g. CdTe) as detection layer of an underlying CMOS semiconductor X-ray detector. NDT energies up to 400 keV are today also possible. The image sharpness and absorption efficiency is improved by the replacement of the unsharp scintillation layer (as used at indirect detectors) with a photo conducting layer of much higher thickness and a high voltage across it. If the read-out speed is high enough (ca. 50 – 100 ns dead time) single X-ray photons can be counted and their energy measured. Read-out noise and dark image correction can be avoided. By definition of energy thresholds selected energy ranges of the X-ray spectrum can be detected or also suppressed. This allows material discrimination by dual-energy technique or the reduction of image contributions from scattered radiation, which results in an enhanced contrast sensitivity. To use these advantages in an effective way, a special calibration procedure has to be developed, which considers also time dependent processes in the detection layer. This contribution presents some of these new properties of direct converting DDAs in comparison to the conventional indirect converting detectors for fiber composites and thick walled steel pipes (up to 35 mm wall thickness). Possible new application areas of NDT will be discussed for material discrimination especially within fiber reinforced composites (e.g. CFRC und GFRC).
Laser welding is a widely established manufacturing process in many industry sectors. Solidification cracking represents one of the most inadequately solved problems in welding and has major economic implications. The avoidance of hot crack is for most fusion welding processes a key challenge for an important range of metallic construction materials and affects not only the manufacturers of welding equipment and material manufacturers, but also a large number of customers using welding technologies, as well as welding standardization and research. In this study a new investigation programme has been developed to qualify the hot cracking susceptibility of a variety of austenitic stainless steels. The results show the possibility of using this technique to determinate the critical values that occur with initiation of solidification cracking during laser beam welding
Solidification cracking phenomena taking place under Controlled Tensile Weldability (CTW) test conditions have already been investigated both experimentally and numerically via FEA in order to get a better understanding of the mechanisms of hot crack formation during laser beam welding of austenitic steel grades. This paper develops a three dimensional finite element model employing the contact elements technique to simulate the formation and propagation of solidification cracks during laser full penetration welding of fully austenitic stainless steel 1.4376. During the experimental procedure the resulting strain and displacement directed to the laser beam in the Close vicinity of the weld pool was measured at the surface of the workpiece using a Digital Image Correlation (DIC) technique with an external diode laser as an illuminating source. Local strain fields, global loads and crack lengths predicted by the model are in good Agreement with those observed in experiments.
Laser welding is a widely established manufacturing process in many industry sectors. Solidification cracking represents one of the most inadequately solved problems in welding and has major economic implications. The avoidance of hot crack forms for most fusion welding processes poses a key challenge for an important range of metallic construction materials and affects not only the manufacturers of welding equipment and material manufacturers, but also a large number of customers using welding technologies, as well as welding technical standardization and research. Solidification cracking susceptibility was examined with the help of the Controlled Tensile Weldability Test (CTW) developed by Federal Institute for Materials Research and Testing (BAM), Berlin. The test is based on the fact that hot crack formation depends on a critical strain that emerges within a critical temperature range, the so called brittle temperature range (BTR). Using this test and defined investigation programme a centreline solidification crack was generated. By controlling the applied strain during the laser beam welding process, it was possible to determine the critical strain and strain rate that led to solidification cracking formation. The hot cracking susceptibility of the tested stainless steels was qualified and quantified. The results demonstrate that the crack length increases with increasing applied strain. Furthermore, the strain rate has a significant influence on the formation of the solidification crack.
Effect of cooling rate on microstructure and properties of microalloyed HSLA steel weld metals
(2015)
Two high strength Nb/Ti microalloyed S690QL steels were welded with identical filler material, varying welding parameters to obtain three cooling rates: slow, medium and fast cooling. As cooling rate increased, the predominantly acicular ferrite in Nb weld metal (WM) is substituted by bainite, with a consequence of obvious hardness increase, but in Ti WM, no great variation of acicular ferrite at all cooling rates contributed to little increment of hardness. The transition between bainite and acicular ferrite has been analysed from the point view of inclusions characteristics, chemical composition and cooling rate. Excellent Charpy toughness at 233 K was obtained with acicular ferrite as predominantly microstructure. Even with bainite weld of high hardness, the toughness was nearly enough to fulfill the minimal requirements. WM for Ti steel showed to be markedly less sensitive to the variations of cooling rate than that for Nb steel.
For the design of laminates the knowledge of the failure behaviour of plies under multiaxial stresses is a necessary precondition. The strength of plies under multiaxial stresses commonly is determined by standard off-axis tests using fixed clamps. By varying the off axis angle the ratio of shear to normal stresses can be prescribed. However, by preventing the rotation a complex stress field develops which strongly varies with the off axis angle as well. While these effects are not crucial when determining the elastic material parameters since the stress state in the center of the specimen is not far from the ideal uniaxial stress state they have a great influence on the failure behaviour.
Room temperature mechanical behavior of extruded Mg–Y–Zn alloys with varying fractions of LPSO phase was studied in tension and compression along the extrusion direction. The microstructure is characterized by elongated LPSO fibers along the extrusion direction within the magnesium matrix. Moreover, the magnesium matrix presents a bimodal grain structure with dynamically-recrystallized grains and deformed, elongated grains with the basal plane parallel to the extrusion direction. The beginning of plasticity depends on the volume fraction of deformed and DRX grains. Alloys with low volume fraction of LPSO phase(o10vol%),with a high volume fraction of deformed grains, show the typical behavior of extruded magnesium alloys where yield stress in tension is higher than in compression. This effect is, however, reversed as the volume fraction of the LPSO phase increases since DRX grains are majority.
Die Verleihung des Deutschen Zukunftspreises an ein Team zum Thema "Ultrakurzpulslaser für die industrielle Massenfertigung - Produzieren mit Lichtblitzen" im Jahr 2013 belegt die industrielle Relevanz des Ultrakurzpulslasereinsatzes in der Materialbearbeitung. Zunehmend werden weitere Anwendungen z.B. in der Mess- und Medizintechnik erschlossen. Femtosekunden-Laserpulse weisen prinzipbedingt ein breites Spektrum auf und besitzen bereits bei moderaten Pulsenergien extreme Pulsspitzenleistungen, womit über „konventionelle“ Laserquellen hinausgehende Herausforderungen an den Laserschutz entstehen. Die in entsprechenden Laserschutzbrillen verwendeten Laserschutzfilter müssen eine große spektrale Absorptionsbandbreite aufweisen und dürfen nicht aufschalten, d.h. keine induzierte Transmission zeigen. Im Vortrag soll dargestellt werden, dass Laserschutzfilter auf Glasbasis, die über ein breites Absorptionsspektrum verfügen, einen ausreichenden Schutz gegenüber fs-Laserstrahlung bieten, wohingegen Laserschutzfilter auf Polymerbasis eine induzierte spektrale Transmission bei steigender Energiedichte aufweisen können, was zu einem drastischen Verlust der Schutzfunktion führt.
The development of innovative medium resolution NMR spectrometers (MR-NMR) is remarkable due to their possible applications in quality control, education, or process monitoring.
The use of compact permanent magnets allows to employ NMR devices in an industrial environment without high maintenance requirements and without the need for cryogenic liquids.
A benchtop 43 MHz MR-NMR spectrometer was used for reaction monitoring. Quasi-simultaneous proton and fluorine NMR spectra were acquired. Automatic data pretreatment and evaluation methods were applied and compared to quantitative 500 MHz HR-NMR spectroscopy
Due to recent advances in technical developments of NMR instruments such as acquisition electronics and probe design, detection limits of components in liquid mixtures were improved into the lower ppm range (approx. 5–10 ppm amount of substance). This showed that modern NMR equipment is also suitable for the observation of hydrocarbon samples in the expanded fluid phase or gas phase. Since Quantitative NMR spectroscopy (qNMR) is a direct ratio method of analysis without the need of calibration it was used to determine impurities in appropriate liquid and liquefied hydrocarbon isomers up to C6, which are used for preparation of primary gas standards, e.g., natural gas or exhaust gas standards. At the same time it is possible to yield structural information with a minimum of sample preparation. Thus, cross contaminations between different isomers of the observed hydrocarbons and their (NMR-active) impurities can be identified and quantified.
In general, most quantitative organic chemical measurements rely on the availability of highly purified compounds to act as calibration standards. The traceability and providence of these standards is an essential component of any measurement uncertainty budget and provides the final link of the result to the units of measurement, ideally the SI. The more recent increase in the use of qNMR for the direct assessment of chemical purity however can potentially improve the traceability and reduce the uncertainty of the measured chemical purity at a reduced cost and with less material. For example the method has beneficially been used by National Measurement institutes for recent CCQM comparisons including the CCQM–K55 series of purity studies.
Traditional ‘indirect’ methods of purity analysis require that all impurities are identified and quantified, leading to a minimum of 4 individual analytical methods (organic impurities, water, solvents, inorganic residue). These multiple technique approaches measure an array of different chemical impurities normally present in purified organic chemical compounds. As many analytical methodologies have compound-specific response factors, the accuracy and traceability of the purity assessment is dependent on the availability of reference materials of the impurities being available.
qNMR provides the most universally applicable form of direct purity determination without need for reference materials of impurities or the calculation of response factors but only exhibiting suitable NMR properties. The development of CRMs addressing qNMR specific measurement issues will give analysts compounds ideally suited for the analytical method and also provide full characterisation of qNMR related parameters to enable more realistic uncertainty budgets. These materials will give users the tools to exploit qNMR more easily and enable them to speed up analytical method development and reduce the time and financial burden of multiple analytical testing.
Troubleshooting Samples Analytics:
Impurities in products: unexpected & unwanted occurrence, unknown identity, analytical method unclear, often various analytical methods, necessary, short response time important (< 1 d), benefits: allocation of its source within hours safes cost
• Investigations planned, coordinated and documented by TSA team
• Variety of analytical methods available
Resolving overlapping peaks of multiple components. Relative primary analytical method - Fundamental relationship of qNMR.
SAF€RA ERANET – Coordination of European Research on Industrial Safety towards Smart and Sustainable Growth, in 2014 launched a joint call on “Innovating in safety and safe innovations”. The HAZPRED project “Predictive methods for determining the decomposition properties of hazardous substances: from development to experimental verification” was selected in this initiative. Main goal is the development and use of predictive methods to determine hazardous physico-chemical properties of various energetic materials (e.g. organic peroxides and self-reactive substances), e. g. thermal stability (self-accelerating decomposition temperature - SADT), explosive power (Trauzl test), heating under confinement (Koenen test), mechanical sensitiveness (impact or friction), etc. The project is based on a co-operation with INERIS (France), VSB-TUO (Czech Republic), BAM and chemical industry.
The application of intumescent coatings for fire protection of steel constructions is
increasing. Thanks to the relative thin thickness of the coatings, the typical visual
appearance of the structures can remain essentially unchanged. In Germany, the
applicability of the systems is regulated by the national as well as European technical
assessments. According to the approvals, the application on steel members in tension is
only allowed with limitations. Especially, the application on solid steel rods in tension is
currently excluded from the approval. The paper explains the actual state of the art of the
application of reactive fire protection systems applied to steel structures. Physical and
technical background information are provided. Furthermore, the latest scientific results
of an on-going research project funded by the German National Institute of Building
Technology (DIBt) and conducted by the Federal Institute for Materials Research and
Testing (BAM) will be described.
Air-coupled ultrasound has been applied increasingly as a non-destructive testing method for lightweight construction in recent years. It is particularly appropriate for composite materials being used in automotive and aviation industry. Air-coupled ultrasound transducers mostly consist of piezoelectric materials and matching layers. However, their fabrication is challenging and their signal-to-noise ratio often not sufficient for many testing requirements. To enhance the efficiency, air-coupled ultrasound transducers made of cellular polypropylene have been developed. Because of its small density and sound velocity, this piezoelectric ferroelectret matches the small acoustic impedance of air much better than matching layers applied in conventional transducers. In our contribution, we present two different methods of spherical focusing of ferroelectret transducers for the further enhancement of their performance in NDT applications. Measurements on carbon-fiber-reinforced polymer (CFRP) samples and on metal adhesive joints performed with commercially available focused air-coupled ultrasound transducers are compared to measurements executed with self-developed focused ferroelectret transducers.
Titanium dioxide is one of the most studied metal oxides due to its interesting chemical, surface, electronic and (photo)catalytic properties. These properties provide this material of multisectorial applications, ranging from healthcare, photocatalysis, smart materials with self cleaning and self sterilizing properties and solar energy harvesting (photovoltaics and water photosplitting). However it is difficult to correlate the functional properties of TiO₂ nanomaterials to the properties at single nanoparticle level due to the high polydispersity in shape, size and surface properties of the currently available TiO₂ nanoparticles (NPs) Although intensive experimental and theoretical studies have been conducted on the reactivity of different surfaces of metal oxides such as TiO₂ [1,2] much less attention is paid on the dependence of functional properties, like photocatalytic activity, dye adsorption, open circuit potential and fill factor in dye sensitized solar cells, on crystal facets in different orientations [3]. One of the goal of SETNanoMetro is the development of design rules to tune crystal facets of TiO₂ NPs in order to optimize and control functional properties. By tuning the ratio of different facets, the functional properties would be correspondingly changed. In the present work we have developed a series of design rules in order to obtain sets of anatase TiO₂ NPs with low polydispersity and to tune their shape and their size though hydrothermal processing of Ti(IV)-Triethanolamine complex in presence of different shape controllers (OH-, triethanolamine, fluoride). Through a careful experimental design the influence of many process parameters (pH, temperature, shape controller type and concentration) on the synthesis outcome (size, shape and polydispersity), a predictive soft model was developed. The model is able to predict reasonably well the synthesis outcome allowing to tune the shape factor from 5 (prisms) to 1.5 (bipyramids) to 0.2 (platelets). This allows to control the main crystal facets exposed ranging from (100) to (001).
Experimental characterization of the thermodynamic behavior of multicomponent gas mixtures of accurately known composition is of great importance for testing the current reference equation of state for natural gases and related mixtures, GERG-2008. Natural gas composition may change considerably due to the diversity of origins, or the possibility to incorporate hydrogen, biogas or other non-conventional energy gases.
Thus, the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM) of the Bureau International des Poids et Mesures (BIPM) launched a key comparison on primary standard mixtures for natural gases of this particular characteristics. One mixture is a hydrogen-enriched natural gas mixture (13 components, x(H2) = 0.03) with low calorific value to facilitate support to power-to-gas applications, which often involve blending hydrogen with natural gas. The other mixture resembles a typical liquefied natural gas (“LNG”, 9 components) with high calorific value.
The GERG-2008 and AGA8-DC92 equations of state enable the calculation of thermal and caloric properties for natural gases and other related mixtures consisting of up to 21 pure components. Experimental characterization of the thermodynamic behavior of gas binary mixtures is of great importance because most of the binary systems were taken into account by using adjusted reducing functions for density and temperature. Only for those binary mixtures for which sufficient accurate experimental data were available, specific departure functions were developed. For the binary mixture methane-helium no departure function was developed so far.
This work studied the thermodynamic behavior of two gravimetrically prepared methane-helium binary mixtures through accurate (p, ρ, T) experimental data obtained by using a single-sinker densimeter with magnetic suspension coupling.
Surface-enhanced Raman scattering (SERS) exploits the enhancement of electromagnetic fields in close vicinity of plasmonic nanostructures, enabling characterization of analytes at the single-molecule level. The nanometer-scale spatial arrangement of plasmonic metal nanoparticles and analyte molecules has a significant effect on the observed signal enhancements and represents a great challenge in this technique.
In our work, DNA origami is used as platform for precise positioning of gold nanoparticles (AuNPs). Especially high sensitivities are expected for gold nanolenses (AuNLs), consisting of rows of three or more differently-sized AuNPs. We assembled different AuNL designs and determined respective SERS enhancement factors by collecting Raman spectra from single AuNLs. Finite difference time domain calculations estimate attainable electromagnetic field enhancements. Ultimately, we aim to develop a versatile platform for various SERS applications.
Chitosan (CS)/iron oxide (Fe3O4) composites were prepared using a chemical precipitation method. The CS/Fe3O4 composite was characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and zeta-potential measurements. The Composite was used to remove methyl orange (MO) dye from an aqueous solution. The factors affecting the adsorption capacity, such as adsorption time, absorbent dosage and solution pH were investigated. The results suggested that the composite was an effective adsorbent for the removal of MO dye from its aqueous solution. Kinetics studies showed that the adsorption process was consistent with a pseudo-second-order model. The adsorbent efficiency was unaltered, even after five cycles of reuse, and the adsorbent could be recollected easily using a magnet. In addition, the composite exhibited a superior antibacterial efficacy against Escherichia coli; 82 % within 24 h, as measured by the colony forming units.
Microorganisms accumulate molar concentrations of compatible solutes like ectoine to prevent proteins from denaturation. Direct structural or spectroscopic information on the mechanism and about the hydration shell around ectoine are scarce. We combined surface plasmon resonance (SPR), confocal Raman spectroscopy, molecular dynamics simulations, and density functional theory (DFT) calculations to study the local hydration shell around ectoine and its influence on the binding of a gene-S-protein (G5P) to a single-stranded DNA (dT(25)). Due to the very high hygroscopicity of ectoine, it was possible to analyze the highly stable hydration shell by confocal Raman spectroscopy. Corresponding molecular dynamics simulation results revealed a significant change of the water dielectric constant in the presence of a high molar ectoine concentration as compared to pure water. The SPR data showed that the amount of protein bound to DNA decreases in the presence of ectoine, and hence, the protein-DNA dissociation constant increases in a concentration-dependent manner. Concomitantly, the Raman spectra in terms of the amide I region revealed large changes in the protein secondary structure. Our results indicate that ectoine strongly affects the molecular recognition between the protein and the oligonudeotide, which has important consequences for osmotic regulation mechanisms.
Zur Bestimmung von Arzneimittelrückständen in Oberflächengewässern wird häufig die LC-MS/MS als Methode der Wahl eingesetzt. Obwohl sich dieses Nachweisverfahren durch eine hohe Empfindlichkeit und Selektivität auszeichnet, gibt es vor allem bei geringen Substanzkonzentrationen häufig störende Einflüsse durch Matrixeffekte. Diese Matrixeffekte können unterschiedliche Ursachen haben.
Einige Matrixeffekte werden am Beispiel des Wirkstoffs Carbamazepin erläutert. Carbamazepin wird durch Kläranlagen nur partiell aus dem Abwasser entfernt und ist im Spurenbereich auch noch im Trinkwasser nachzuweisen. Wenn für die LC-MS/MS wasserbasierte Anteile in der mobilen Phase genutzt werden, befinden sich trotz Verwendung einer Labor-Reinstwasseranlage in der mobilen Phase noch kleinste Konzentrationen von Carbamazepin, welche einen Blindwert im unteren ppt-Bereich verursachen.
Weitere Matrixeffekte treten durch die unterschiedliche Qualität der Oberflächenwasserproben auf. Koelutionen von weiteren Inhaltstoffen zeitgleich mit dem Zielanalyten führen zu einer Diskriminierung des Meßsignals. Verbindungen, die den gleichen Massenübergang bei nahezu identischer Retentionszeit zeigen, erfordern eine reproduzierbare chromatographische Vortrennung oder die Wahl einer alternativen HPLC-Säule.
N4-acetyl-SMX is the most important cross-reacting compound for the SMX-ELISA with concentrations of 1064 - 2488 ng/L in influent wastewater and 40 - 160 ng/L in effluent wastewater.
The ELISAgrams for estrone show less interfering signals than for SMX.
ELISAgrams of SMX and estrone display in effluent wastewater more interfering signals than in influent wastewater.
Afin de garantir la qualité des eaux en Europe, la Commission Européenne a demandé aux États Membres, de leur fournir des résultats de mesure comparables et traçables pour l’analyse des polluants critiques. Devant ces enjeux considérables pour la protection de l’environnement, l’apport de la métrologie est nécessaire pour améliorer la fiabilité des analyses et permettre la comparabilité des résultats. C’est pourquoi, le projet de recherche européen Euramet/EMRP/ENV08 « Traçabilité des mesures pour la surveillance des polluants critiques de la DCE, Directive Cadre européenne sur l’Eau (2000/60/CE) », financé par l’EMRP, avait pour objectif de fournir des éléments pour la mise en place d’une base métrologique. Des méthodes de référence primaires permettant d’analyser des substances dangereuses prioritaires y sont développées pour répondre aux exigences de la DCE en termes de niveaux de performance (limites de quantification et incertitudes). Les hydrocarbures aromatiques polycycliques (HAP), substances dangereuses prioritaires « orphelines » de méthodes DCE compatibles, font partie des polluants ciblés par le projet. Le développement et la validation de la méthode d’analyse des HAP dans l’eau totale ont été réalisés. La méthode qui satisfait au mieux les exigences de la DCE en termes de concentrations et d’incertitudes accessibles est l’extraction en phase solide (SPE) sur un support disque suivie d’une analyse par dilution isotopique associée à la chromatographie en phase gazeuse couplée à la spectroscopie de masse (DI-CG/SM).
In 2011, the German Association of Engineers (VDI) started working on a set of guidelines towards increased resource efficiency. These guidelines represent a framework that defines resource efficiency and outlines considerations for the producing industry. A special guideline for SMEs is included as well as guidelines on methodologies for evaluating resource use indicators, such as the cumulative raw material demand of products and production systems. Resource efficiency, defined here as the ratio of specific quantifiable use to natural resource consumption, can be evaluated by defining a function which expresses the specific use and quantifies the resource requirements through a set of indicators (use of raw materials, energy, water, land and ecosystem services including sinks). The results from this also depend on the system boundary parameters and the allocation rules for by-products and waste treatment options. Optimising resource use is possible at all stages of a product’s or production system’s life cycle chain (raw material extraction, production and manufacturing, use and consumption, and the end-of-life stage). VDI guidelines are widely accepted across Germany’s industrial sector and therefore represent an important means of mainstreaming resource efficiency in this target area. As well as providing a methodological framework, the guidelines describe strategies and measures towards increasing resource efficiency, and they enable industrial producers and service providers to identify potential areas of improvement. The full article presents an overview of the methodology and contents of these guidelines and discusses their impact in achieving absolute reductions in the industrial use of natural resources.