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Assessing the hyphenation of ion chromatography with optical emission spectrometry for trace analysis of oxyhalide bromine and chlorine species
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The increased application of oxidative water treatment is associated with the presence of halogenated disinfection by-products (DBPs) in aqueous systems. Due to their hazard potential, permanent measurements of selected analytes are required to monitor their compliance with regulatory limits and guidelines. However, the simultaneous acquisition of alarming inorganic oxyhalide species by conventional ion chromatography (IC) is often impeded by co-elution of interfering analyte or matrix components, especially when DBPs of multiple halogens are present in solution. This necessitates a complementary, orthogonal detection setup that allows for an element-specific analysis
Sustainability in motion: Investigation of automated gravimetric sample preparation in industrial liquid chromatography
Get PDFFor analysis with liquid chromatography (LC), samples and calibration standards generally require a dilution by a factor of 103 to 106. To guarantee a high accuracy, sample preparation usually employs high-volume pipettes and volumetric flasks for dilution series. Consequently, sample preparation is a prominent driving factor for consumption of solvents in the LC laboratory. Miniaturisation in sample preparation can thus be a means of reducing the required amount of solvent within the laboratory, saving valuable resources. In the context of dilution series, this can be achieved by the use of low-volume dispensing tools, which usually have a higher relative instrument error, resulting in a less accurate overall method. Another approach is the transition to a gravimetric sample preparation, in which the dilution steps are not measured in volume but weight, only depending on the much lower error of the analytical balance. By implementing weighing robots, one can fully automate the sample preparation workflow. This study deals with the comparison of various dilution methods. Gravimetric, robot-aided dilution allows for the reduction of the solvent down to the amount of sample needed for analyses. Including the initial dissolution of the sample, using gravimetric dilution can reliably and repeatedly reduce the required solvent amount by over 90 %, while still generating the same analytical results. Overall, this application leads to significant economic, ecological, social, and technological benefits for the LC laboratory
Investigation of Al/SrO2/MgSt and Si/CaO2/MgSt Delay Pellets and Parameters Influencing the Burning Rate As Well As Thermal Aging Effects on Their Burning Properties
Get PDFToxic and environmentally harmful components of pyrotechnic compositions require to be substituted with alternative substances. Therefore, the subject of this work was the burning rate investigation of the Al/SrO2 and Si/CaO2 pyrotechnic delay compositions. The delay elements were prepared by pressing the compositions into pellets and transferring them into delay tubes. However, the Al/SrO2 pellets were also placed into the delay tube and post-pressed to determine if any differences in the burning rate were measurable. The dependency of the burning rate in relation to the pellet diameter, binder content, delay tube material, and artificial aging of the compositions was investigated. Further, the impact of the aging as well as of the binder content on the ignition temperature of the compositions was determined. The used silicon powders were characterized by means of Raman spectroscopy, particle size analysis, and BET surface area analysis. Raman spectroscopy was also used to investigate differences between the freshly prepared and artificially aged pyrotechnic compositions. The investigation of friction and impact sensitivity of the compositions, with and without use of the binder, resulted in the classification of both compositions as insensitive. In addition, the mechanical pellet stability in dependency of the binder content was determined, which increased with the binder content
3-Hydroxy-3-methylglutaryl-coenzyme A lyase deficiency: case report of a child with rare HMGCL gene variants
No full textKonzeptentwicklung eines kostengünstigen Ultraschall-Laufzeit-Sensors zur Verwendung in Anemometern
Get PDFDas Verständnis urbaner Windfelder ist zentral für eine klimaangepasste Stadtplanung, da Windströmungen die Verteilung von Hitze und Schadstoffen wesentlich beeinflussen. Um nachhaltig Maßnahmen in der Stadtplanung durchsetzen zu können, braucht es verlässliche Winddaten. Diese liefern unter anderem 3D-Ultraschall-Anemometer, deren hohe Kosten jedoch den flächendeckenden Einsatz erschweren. Ziel dieser Arbeit ist daher die Machbarkeitsuntersuchung einer kostengünstigen Ultraschallsensorik.
Das Funktionsprinzip eines Ultraschall-Anemometers beruht darauf, dass die Ausbreitungsgeschwindigkeit des Schalls in der Luft von der Bewegungsgeschwindigkeit und -richtung der Luft abhängt. Durch bidirektionale Messung kann die Windgeschwindigkeit kollinear zu der Achse zwischen zwei Schallwandlern unabhängig von Temperatur und Luftfeuchtigkeit bestimmt werden. Für die Umsetzung einer kostengünstigen 1D-Sensorik werden dafür in dieser Arbeit zwei Messansätze zur Messung der Windgeschwindigkeit evaluiert: Die direkte Laufzeitmessung des Schalls mittels eines TDCs (Time-to-Digital-Converter), sowie die Auswertung der Spannungsverläufe mittels eines ADCs (Analog-Digital-Converter). Die Umsetzung dieser beiden erfolgt in einem gemeinsamen Prototyp. Dabei werden sowohl die Hard- als auch die Software dessen entwickelt.
Für beide Messverfahren wird jeweils der optimale Abstand der Schallwandler ermittelt. Es werden beide Methoden, sowie ein kommerzielles Referenzmessgerät in einem Windkanal getestet, der durch Strömungsgleichrichter einen laminaren Luftstrom gewährleistet. Aus Budget- und Zeitgründen steht lediglich ein unkalibriertes Referenzmessgerät zur Verfügung. Es weist Schwankungen über einen längeren Zeitraum auf. Dadurch ist eine Aussage über die Genauigkeit des Prototyps kaum zu treffen. Dennoch sind die Ergebnisse beider Verfahren des Prototyps vielversprechend. Das Messen der Windgeschwindigkeit ist mit der entwickelten Ultraschallsensorik möglich. Diese Arbeit liefert die Grundlage für eine Weiterentwicklung des Systems. Eine 3D-Sensorik ist anzustreben
TransHyDE‐Sys: An Integrated Systemic Approach for Analyzing and Supporting the Transformation of Energy Systems and Hydrogen Infrastructure Development
Get PDFIn addition to the long-term goal of mitigating climate change, the current geopolitical upheavals heighten the urgency to transform Europe's energy system. This involves expanding renewable energies while managing intermittent electricity generation. Hydrogen is a promising solution to balance generation and demand, simultaneously decarbonizing complex applications. To model the energy system's transformation, the project TransHyDE-Sys, funded by the German Federal Ministry of Education and Research, takes an integrated approach beyond traditional energy system analysis, incorporating a diverse range of more detailed methods and tools. Herein, TransHyDE-Sys is situated within the recent policy discussion. It addresses the requirements for energy system modeling to gain insights into transforming the European hydrogen and energy infrastructure. It identifies knowledge gaps in the existing literature on hydrogen infrastructure-oriented energy system modeling and presents the research approach of TransHyDE-Sys. TransHyDE-Sys analyzes the development of hydrogen and energy infrastructures from “the system” and “the stakeholder” perspectives. The integrated modeling landscape captures temporal and spatial interactions among hydrogen, electricity, and natural gas infrastructure, providing comprehensive insights for systemic infrastructure planning. This allows a more accurate representation of the energy system's dynamics and aids in decision-making for achieving sustainable and efficient hydrogen network development integration
Adaptive Optimization of TLS Overhead for Wireless Communication in Critical Infrastructure
No full textInvestigation of explosives traces in pre-blast contamination scenarios using optimised wet swab sampling
No full textExplosives trace residues on surfaces are utilized for forensic investigations and to check suspicious objects using technical and non-technical detection procedures. Data about expected trace contaminations after the handling of explosives and how they relate to a potential chemical background help to determine requirements and limitations of detection procedures. Often swab sampling is used for the analysis of surface contaminations. A wet swab sampling procedure was optimized for PETN, TNT and ammonium nitrate. Good results were achieved using PU-foam swabs wetted with a mixture of acetonitrile/water (90/10). The swabs were subsequently solvent extracted and analysed using LC-triple-quad-MS and ion-chromatography. The swabs were applied for the determination of explosives residues in a mock-up car scenario simulating one person loading the car with explosives followed by a short car travel by the same person. As test substances an ANFO, TNT and plasticized PETN were used. Additional samples were taken from indoor installations regularly used for the training of explosive detection dogs as well as other objects and buildings close by. The surface contaminations found in the investigated scenario ranged from the ng to the µg scale. The results indicate that simple cleaning procedures might not sufficient to remove explosives contaminations in training settings for explosives detection dogs. A significant spreading of explosive traces beyond direct contact with the person handling the explosive or with the explosive itself was not observed