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Papers by Hainer Wackerbarth
international conference on nanotechnology, 2005
Tillæg til Dansk …, 2002
2Novozymes det første i mere end en tredjedel af alle kendte proteiners funktion [3, 4]. Der er a... more 2Novozymes det første i mere end en tredjedel af alle kendte proteiners funktion [3, 4]. Der er altid involveret metalioner, når naturen udøver en sofistikeret funktion, f. eks. i fotosyntese, respiration, enzymfunktion og alle faser af DNA's biologiske virksomhed. Den tværfaglige ...
Global climate change demands better use of energy and stricter limitations on the emission of gr... more Global climate change demands better use of energy and stricter limitations on the emission of greenhouse gases. Additionally, due to technological advances, automation in process analytics demand better in-situ sensor technologies. For this Raman spectroscopy is suitable, but the technique itself needs to be enhanced to be viable. Here, we present a first analysis for the suitability of fibre-enhanced Raman spectroscopy (FERS). We studied environmental gases by means of Raman spectroscopy with hollow core photonic crystal fibres (HC-PCF).
Designing efficient and robust nonprecious metal-based electrocatalysts for overall water electro... more Designing efficient and robust nonprecious metal-based electrocatalysts for overall water electrolysis, which is mainly limited by the oxygen evolution reaction (OER), for hydrogen production remains a major challenge for the hydrogen economy. In this work, a bimetallic NiFeP catalyst is coated on nickel phosphide rods grown on nickel foam (NiFeP@NiP@NF). This self-supported and interfacially connected electrode structure is favorable for mass transfer and reducing electrical resistance during electrocatalysis. The preparation of NiFeP@NiP@NF is optimized in terms of (i) the coprecipitation time of the NiFe Prussian blue analogue layer that serves as phosphides precursor and (ii) the phosphidation temperature. The optimized sample exhibits excellent OER performance delivering current densities of 10 and 100 mA cm-2 at low overpotentials of 227 and 252 mV in 1.0 M KOH, respectively, and maintaining 10 mA cm-2 for more than 120 h without obvious degradation. Moreover, it can also be operated as a hydrogen evolution electrocatalyst, requiring an overpotential of 105 mV at 10 mA cm-2 in the same medium. Thus, the as-prepared material was tentatively utilized as a bifunctional electrocatalyst in a symmetric electrolyzer, requiring a voltage bias of 1.57 V to afford 10 mA cm-2 in 1.0 M KOH, while exhibiting outstanding stability.
SAE International Journal of Engines, 2018
Applied Optics, 2010
In this study we present a device based on surface-enhanced Raman scattering (SERS) for the detec... more In this study we present a device based on surface-enhanced Raman scattering (SERS) for the detection of airborne explosives. The explosives are resublimated on a cooled nanostructured gold substrate. The explosives trinitrotoluene (TNT) and triacetone triperoxide (TATP) are used. The SERS spectrum of the explosives is analyzed. Thus, TNT is deposited from an acetonitrile solution on the gold substrate. In the case of TATP, first the bulk TATP Raman spectrum was recorded and compared with the SERS spectrum, generated by deposition out of the gas phase. The frequencies of the SERS spectrum are hardly shifted compared to the spectrum of bulk TATP. The influence of the nanostructured gold substrate temperature on the signals of TATP was studied. A decrease in temperature up to 200 K increased the intensities of the TATP bands in the SERS spectrum; below 200 K, the TATP fingerprint disappeared.
Applied Optics, 2010
A challenge in the detection of explosives is the differentiation between explosives and contamin... more A challenge in the detection of explosives is the differentiation between explosives and contaminants. Synthetic musk-containing perfumes can cause false alarms, as these perfumes are nitroaromatic compounds, which can be mistaken for trinitro toluene (TNT) by some detectors. We present a detection principle based on surface-enhanced Raman scattering (SERS). A stream of the airborne compounds is focused and resublimated on a cooled nanostructured gold surface. We recorded high-resolution SERS spectra of TNT, musk xylene, and musk ketone. The nitroaromatic compounds can be identified unambiguously by their SERS spectra. Even the dominant bands containing nitro-group scissoring and symmetric stretching modes are significantly shifted by the difference in molecular structure.
Analytical and Bioanalytical Chemistry, 2011
Free-flow electrophoresis techniques have been applied for separations in various areas of chemis... more Free-flow electrophoresis techniques have been applied for separations in various areas of chemistry and biochemistry. Here we focus on the generation of a free-flow electrophoresis chip and direct monitoring of the separation of different molecules in the separation bed of the miniaturized chip. We demonstrate a fast and efficient way to generate a low-cost micro-free-flow electrophoresis (μFFE) chip with a filling capacity of 9.5 μL based on a multi-lamination technique. Separating webs realized by two transfer-adhesive tapes avoid the problem of gas bubbles entering the separation area. The chip is characterized by isoelectric focusing markers (IEF markers). The functionality of the chip is demonstrated by free-flow isoelectric focusing (FFIEF) of the proteins BSA (bovine serum albumin) and avidin and a single-stranded DNA (ssDNA) fragment in the pH range 3 to 10. The separation voltage ranges between 167 Vcm −1 and 422 V cm −1 , depending on the application.
Diagnostics
Incorrect medication administration causes millions of undesirable complications worldwide every ... more Incorrect medication administration causes millions of undesirable complications worldwide every year. The problem is severe and there are many control systems in the market, yet the exact molecular composition of the solution is not monitored. Here, we propose an alarm sensor based on UV-Vis spectroscopy and refractometry. Both methods are non-invasive and non-destructive as they utilize visible light for the analysis. Moreover, they can be used for on-site or point-of-care diagnosis. UV-Vis-spectrometer detect the absorption of light caused by an electronic transition in an atom or molecule. In contrast a refractometer measures the extent of light refraction as part of a refractive index of transparent substances. Both methods can be used for quantification of dissolved analytes in transparent substances. We show that a sensor combining both methods is capable to discern most standard medications that are used in intensive care medicine. Furthermore, an integration of the alarm se...
Die Erfindung betrifft die Identifizierung von in einer Gasphase vorliegenden schwer fluchtigen S... more Die Erfindung betrifft die Identifizierung von in einer Gasphase vorliegenden schwer fluchtigen Substanzen, insbesondere von Gefahrstoffen. Eine Messzelle (2) und eine an die Messzelle (2) angeschlossene Gaszufuhrungseinrichtung (14) werden erwarmt, und eine in der Messzelle (2) angeordnete plasmonische Oberflache (1) wird derart temperiert, dass die plasmonische Oberflache (1) eine geringere Temperatur als die Messzelle (2) und die Gaszufuhrungseinrichtung (14) aufweist. Die Gasphase wird durch die Gaszufuhrungseinrichtung (14) derart in die Messzelle (2) gefuhrt, dass die Gasphase an die temperierte plasmonische Oberflache (1) gelangt. Aus der Gasphase ander plasmonischen Oberflache(1) adsorbierte Substanzen werden mit einem optischen Verfahren analysiert. Als optisches Verfahren kann die oberflachenverstarkte Raman-Spektroskopie oder die oberflachenverstarkte Infrarot-Spektroskopie eingesetzt werden. Durch die Kombination beider Verfahren kann die Selektivitat erhoht werden. Zusa...
Journal of Sensors and Sensor Systems
The global climate change calls for more environmentally friendly use of energy and has led to st... more The global climate change calls for more environmentally friendly use of energy and has led to stricter limits and regulations for the emissions of various greenhouse gases. Consequently, there is nowadays an increasing need for the detection of exhaust and natural gases. This need leads to an ever-growing market for gas sensors, which, at the moment, is dominated by chemical sensors. Yet, the increasing demands to also measure under harsh environmental conditions pave the way for non-invasive measurements and thus optical detection techniques. Here, we present the development of two optical detection systems using non-dispersive infrared absorption spectroscopy (NDIR). One system is intended for civilian use, capable of detecting both CO as well as CO 2 in the range of 4-5 µm. Furthermore, restrictions regarding size and economic viability are put on this sensor so it can compete with existing sensors. For CO 2 , an estimated resolution of 444 ppm is achieved, which is competitive with established sensors on the market. For CO an estimated resolution of 1401 ppm was achieved, rendering it necessary to improve this sensor to be competitive with other available sensors. The second system is used in an exhaust system and is capable of detecting CO 2 at 3.2 µm facing cross-sensitivity with H 2 O. A data analysis method is described to separate the CO 2 and H 2 O signals, revealing a time resolution of 33 µs.
In the terminal step of the respiratory chain of aerobic organisms, the membrane-bound enzyme cyt... more In the terminal step of the respiratory chain of aerobic organisms, the membrane-bound enzyme cytochrome c oxidase (CcO) reduces dioxygen to water [1]. The required electrons are delivered stepwise by the soluble electron carrier cytochrome c (Cyt) [2]. Prior to these interprotein electron transfer reactions, Cyt binds to CcO via electrostatic interactions between the positively charged lysine-rich region on the surface of Cyt and a negatively charged binding domain of CcO [3]. Although the crystal structures of the individual redox proteins have been determined (e. g., [4, 5]), the structure of the Cyt-CcO protein complex is not known. On the other hand, a variety of spectroscopic results indicate that conformational changes are induced in the active sites of both partner proteins upon complex formation [6 – 8]. In our previous resonance Raman (RR) studies [7, 8], we could demonstrate that upon formation of the fully oxidized Cyt-CcO complex, a conformational equilibrium of the bound Cyt is established which involves two conformers, B1 and B2. These species are also formed upon binding to negatively charged model systems (electrodes, phospholipid vesicles, polyanions) which mimic the interaction domain of CcO [9, 10]. In contrast to Bl, which can be regarded as essentially identical to the unbound Cyt, the spectrum of state B2 reveals significant structural changes in the heme pocket of this conformer which most likely include the exchange of the Met-80 axial ligand presumably by a hydroxide [11] and are accompanied by a drastic lowering of the reduction potential [9]. These findings have been suggested to be of functional relevance for interprotein electron transfer to CcO [7, 8].
Scientific Reports
Benzotriazole (BTAH) has been used for decades as corrosion inhibitor and antifreeze. Since it is... more Benzotriazole (BTAH) has been used for decades as corrosion inhibitor and antifreeze. Since it is fairly soluble in water but very stable and can only be partly removed from wastewater treatment plants, it represents a threat to the environment and thus also to human health. Therefore, it is of uttermost importance to have a detection method capable of monitoring the concentration of BTAH at trace level on-site. Here, we demonstrate that a sensor based on surface-enhanced Raman spectroscopy is capable of detecting trace-level concentrations of BTAH. We carefully studied the concentration dependency and the time dependent coverage. Moreover, we could not only perform the measurements with clean solution but also with real samples from a wastewater treatment plant, ensuring that our method proposed works in a complex environment.
international conference on nanotechnology, 2005
Tillæg til Dansk …, 2002
2Novozymes det første i mere end en tredjedel af alle kendte proteiners funktion [3, 4]. Der er a... more 2Novozymes det første i mere end en tredjedel af alle kendte proteiners funktion [3, 4]. Der er altid involveret metalioner, når naturen udøver en sofistikeret funktion, f. eks. i fotosyntese, respiration, enzymfunktion og alle faser af DNA's biologiske virksomhed. Den tværfaglige ...
Global climate change demands better use of energy and stricter limitations on the emission of gr... more Global climate change demands better use of energy and stricter limitations on the emission of greenhouse gases. Additionally, due to technological advances, automation in process analytics demand better in-situ sensor technologies. For this Raman spectroscopy is suitable, but the technique itself needs to be enhanced to be viable. Here, we present a first analysis for the suitability of fibre-enhanced Raman spectroscopy (FERS). We studied environmental gases by means of Raman spectroscopy with hollow core photonic crystal fibres (HC-PCF).
Designing efficient and robust nonprecious metal-based electrocatalysts for overall water electro... more Designing efficient and robust nonprecious metal-based electrocatalysts for overall water electrolysis, which is mainly limited by the oxygen evolution reaction (OER), for hydrogen production remains a major challenge for the hydrogen economy. In this work, a bimetallic NiFeP catalyst is coated on nickel phosphide rods grown on nickel foam (NiFeP@NiP@NF). This self-supported and interfacially connected electrode structure is favorable for mass transfer and reducing electrical resistance during electrocatalysis. The preparation of NiFeP@NiP@NF is optimized in terms of (i) the coprecipitation time of the NiFe Prussian blue analogue layer that serves as phosphides precursor and (ii) the phosphidation temperature. The optimized sample exhibits excellent OER performance delivering current densities of 10 and 100 mA cm-2 at low overpotentials of 227 and 252 mV in 1.0 M KOH, respectively, and maintaining 10 mA cm-2 for more than 120 h without obvious degradation. Moreover, it can also be operated as a hydrogen evolution electrocatalyst, requiring an overpotential of 105 mV at 10 mA cm-2 in the same medium. Thus, the as-prepared material was tentatively utilized as a bifunctional electrocatalyst in a symmetric electrolyzer, requiring a voltage bias of 1.57 V to afford 10 mA cm-2 in 1.0 M KOH, while exhibiting outstanding stability.
SAE International Journal of Engines, 2018
Applied Optics, 2010
In this study we present a device based on surface-enhanced Raman scattering (SERS) for the detec... more In this study we present a device based on surface-enhanced Raman scattering (SERS) for the detection of airborne explosives. The explosives are resublimated on a cooled nanostructured gold substrate. The explosives trinitrotoluene (TNT) and triacetone triperoxide (TATP) are used. The SERS spectrum of the explosives is analyzed. Thus, TNT is deposited from an acetonitrile solution on the gold substrate. In the case of TATP, first the bulk TATP Raman spectrum was recorded and compared with the SERS spectrum, generated by deposition out of the gas phase. The frequencies of the SERS spectrum are hardly shifted compared to the spectrum of bulk TATP. The influence of the nanostructured gold substrate temperature on the signals of TATP was studied. A decrease in temperature up to 200 K increased the intensities of the TATP bands in the SERS spectrum; below 200 K, the TATP fingerprint disappeared.
Applied Optics, 2010
A challenge in the detection of explosives is the differentiation between explosives and contamin... more A challenge in the detection of explosives is the differentiation between explosives and contaminants. Synthetic musk-containing perfumes can cause false alarms, as these perfumes are nitroaromatic compounds, which can be mistaken for trinitro toluene (TNT) by some detectors. We present a detection principle based on surface-enhanced Raman scattering (SERS). A stream of the airborne compounds is focused and resublimated on a cooled nanostructured gold surface. We recorded high-resolution SERS spectra of TNT, musk xylene, and musk ketone. The nitroaromatic compounds can be identified unambiguously by their SERS spectra. Even the dominant bands containing nitro-group scissoring and symmetric stretching modes are significantly shifted by the difference in molecular structure.
Analytical and Bioanalytical Chemistry, 2011
Free-flow electrophoresis techniques have been applied for separations in various areas of chemis... more Free-flow electrophoresis techniques have been applied for separations in various areas of chemistry and biochemistry. Here we focus on the generation of a free-flow electrophoresis chip and direct monitoring of the separation of different molecules in the separation bed of the miniaturized chip. We demonstrate a fast and efficient way to generate a low-cost micro-free-flow electrophoresis (μFFE) chip with a filling capacity of 9.5 μL based on a multi-lamination technique. Separating webs realized by two transfer-adhesive tapes avoid the problem of gas bubbles entering the separation area. The chip is characterized by isoelectric focusing markers (IEF markers). The functionality of the chip is demonstrated by free-flow isoelectric focusing (FFIEF) of the proteins BSA (bovine serum albumin) and avidin and a single-stranded DNA (ssDNA) fragment in the pH range 3 to 10. The separation voltage ranges between 167 Vcm −1 and 422 V cm −1 , depending on the application.
Diagnostics
Incorrect medication administration causes millions of undesirable complications worldwide every ... more Incorrect medication administration causes millions of undesirable complications worldwide every year. The problem is severe and there are many control systems in the market, yet the exact molecular composition of the solution is not monitored. Here, we propose an alarm sensor based on UV-Vis spectroscopy and refractometry. Both methods are non-invasive and non-destructive as they utilize visible light for the analysis. Moreover, they can be used for on-site or point-of-care diagnosis. UV-Vis-spectrometer detect the absorption of light caused by an electronic transition in an atom or molecule. In contrast a refractometer measures the extent of light refraction as part of a refractive index of transparent substances. Both methods can be used for quantification of dissolved analytes in transparent substances. We show that a sensor combining both methods is capable to discern most standard medications that are used in intensive care medicine. Furthermore, an integration of the alarm se...
Die Erfindung betrifft die Identifizierung von in einer Gasphase vorliegenden schwer fluchtigen S... more Die Erfindung betrifft die Identifizierung von in einer Gasphase vorliegenden schwer fluchtigen Substanzen, insbesondere von Gefahrstoffen. Eine Messzelle (2) und eine an die Messzelle (2) angeschlossene Gaszufuhrungseinrichtung (14) werden erwarmt, und eine in der Messzelle (2) angeordnete plasmonische Oberflache (1) wird derart temperiert, dass die plasmonische Oberflache (1) eine geringere Temperatur als die Messzelle (2) und die Gaszufuhrungseinrichtung (14) aufweist. Die Gasphase wird durch die Gaszufuhrungseinrichtung (14) derart in die Messzelle (2) gefuhrt, dass die Gasphase an die temperierte plasmonische Oberflache (1) gelangt. Aus der Gasphase ander plasmonischen Oberflache(1) adsorbierte Substanzen werden mit einem optischen Verfahren analysiert. Als optisches Verfahren kann die oberflachenverstarkte Raman-Spektroskopie oder die oberflachenverstarkte Infrarot-Spektroskopie eingesetzt werden. Durch die Kombination beider Verfahren kann die Selektivitat erhoht werden. Zusa...
Journal of Sensors and Sensor Systems
The global climate change calls for more environmentally friendly use of energy and has led to st... more The global climate change calls for more environmentally friendly use of energy and has led to stricter limits and regulations for the emissions of various greenhouse gases. Consequently, there is nowadays an increasing need for the detection of exhaust and natural gases. This need leads to an ever-growing market for gas sensors, which, at the moment, is dominated by chemical sensors. Yet, the increasing demands to also measure under harsh environmental conditions pave the way for non-invasive measurements and thus optical detection techniques. Here, we present the development of two optical detection systems using non-dispersive infrared absorption spectroscopy (NDIR). One system is intended for civilian use, capable of detecting both CO as well as CO 2 in the range of 4-5 µm. Furthermore, restrictions regarding size and economic viability are put on this sensor so it can compete with existing sensors. For CO 2 , an estimated resolution of 444 ppm is achieved, which is competitive with established sensors on the market. For CO an estimated resolution of 1401 ppm was achieved, rendering it necessary to improve this sensor to be competitive with other available sensors. The second system is used in an exhaust system and is capable of detecting CO 2 at 3.2 µm facing cross-sensitivity with H 2 O. A data analysis method is described to separate the CO 2 and H 2 O signals, revealing a time resolution of 33 µs.
In the terminal step of the respiratory chain of aerobic organisms, the membrane-bound enzyme cyt... more In the terminal step of the respiratory chain of aerobic organisms, the membrane-bound enzyme cytochrome c oxidase (CcO) reduces dioxygen to water [1]. The required electrons are delivered stepwise by the soluble electron carrier cytochrome c (Cyt) [2]. Prior to these interprotein electron transfer reactions, Cyt binds to CcO via electrostatic interactions between the positively charged lysine-rich region on the surface of Cyt and a negatively charged binding domain of CcO [3]. Although the crystal structures of the individual redox proteins have been determined (e. g., [4, 5]), the structure of the Cyt-CcO protein complex is not known. On the other hand, a variety of spectroscopic results indicate that conformational changes are induced in the active sites of both partner proteins upon complex formation [6 – 8]. In our previous resonance Raman (RR) studies [7, 8], we could demonstrate that upon formation of the fully oxidized Cyt-CcO complex, a conformational equilibrium of the bound Cyt is established which involves two conformers, B1 and B2. These species are also formed upon binding to negatively charged model systems (electrodes, phospholipid vesicles, polyanions) which mimic the interaction domain of CcO [9, 10]. In contrast to Bl, which can be regarded as essentially identical to the unbound Cyt, the spectrum of state B2 reveals significant structural changes in the heme pocket of this conformer which most likely include the exchange of the Met-80 axial ligand presumably by a hydroxide [11] and are accompanied by a drastic lowering of the reduction potential [9]. These findings have been suggested to be of functional relevance for interprotein electron transfer to CcO [7, 8].
Scientific Reports
Benzotriazole (BTAH) has been used for decades as corrosion inhibitor and antifreeze. Since it is... more Benzotriazole (BTAH) has been used for decades as corrosion inhibitor and antifreeze. Since it is fairly soluble in water but very stable and can only be partly removed from wastewater treatment plants, it represents a threat to the environment and thus also to human health. Therefore, it is of uttermost importance to have a detection method capable of monitoring the concentration of BTAH at trace level on-site. Here, we demonstrate that a sensor based on surface-enhanced Raman spectroscopy is capable of detecting trace-level concentrations of BTAH. We carefully studied the concentration dependency and the time dependent coverage. Moreover, we could not only perform the measurements with clean solution but also with real samples from a wastewater treatment plant, ensuring that our method proposed works in a complex environment.