TY - JOUR A1 - Usmani, Shirin M. A1 - Plarre, Rüdiger A1 - Hübert, Thomas A1 - Kemnitz, E. T1 - Termite resistance of pine wood treated with nano metal fluorides JF - European Journal of Wood and Wood Products N2 - Fluorides are well-known as wood preservatives. One of the limitations of fluoride-based wood preservatives is their high leachability. Alternative to current fluoride salts such as NaF used in wood protection are low water-soluble fluorides. However, impregnation of low water-soluble fluorides into wood poses a challenge. To address this challenge, low water-soluble fluorides like calcium fluoride (CaF2) and magnesium fluoride (MgF2) were synthesized as nanoparticles via the fluorolytic sol−gel synthesis and then impregnated into wood specimens. In this study, the toxicity of nano metal fluorides was assessed by termite mortality, mass loss and visual analysis of treated specimens after eight weeks of exposure to termites, Coptotermes formosanus. Nano metal fluorides with sol concentrations of 0.5 M and higher were found to be effective against termites resulting in 100% termite mortality and significantly inhibited termite feeding. Among the formulations tested, the least damage was found for specimens treated with combinations of CaF2 and MgF2 with an average mass loss less than 1% and visual rating of “1”. These results demonstrate the efficacy of low water-soluble nano metal fluorides to protect Wood from termite attack. KW - Wood Protection KW - Nano Particles KW - Termites PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508377 DO - https://doi.org/10.1007/s00107-020-01522-z VL - 78 SP - 493 EP - 499 PB - Springer AN - OPUS4-50837 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Usmani, S. A1 - Voss, L. A1 - Stephan, Ina A1 - Hübert, Thomas A1 - Kemnitz, E. T1 - Improved Durability of Wood Treated with Nano Metal Fluorides against Brown-Rot and White-Rot Fungi JF - Applied Sciences N2 - Low-water soluble metal fluorides such as magnesium fluoride (MgF2) and calcium Fluoride (CaF2) were evaluated for decay protection of wood. Initially, the biocidal efficacy of nano metal fluorides (NMFs) against wood destroying fungi was assessed with an in-vitro agar test. The results from the test showed that agar medium containing MgF2 and CaF2 was more efficient in preventing fungal decay than stand-alone MgF2 or CaF2. These metal fluorides, in their nanoscopic form synthesized using fluorolytic sol-gel synthesis, were introduced into the sapwood of Scots pine and beech wood and then subjected to accelerated ageing by leaching (EN 84). MAS 19F NMR and X-ray micro CT images showed that metal fluorides were present in treated wood, unleached and leached. Decay resistance of Scots pine and beech wood treated with NMFs was tested against Wood destroying fungi Rhodonia placenta and Trametes versicolor in accordance with EN 113. Results revealed that mass losses were reduced to below 3% in wood treated with the combination of MgF2 and CaF2. It is concluded that NMFs provide full protection to wood even after it has been leached and can be used as wood preservatives in outdoor environments. KW - Nanoparticles KW - Fluoride KW - Wood protection KW - Fluorolytic sol-gel synthesis KW - Brown-rot fungi KW - White-rot fungi KW - Basidiomycetes PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543877 DO - https://doi.org/10.3390/app12031727 VL - 12 IS - 3 SP - 1 EP - 11 PB - MDPI AN - OPUS4-54387 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Brita A1 - Bücker, Michael A1 - Reinsch, Stefan A1 - Hübert, Thomas T1 - Chemical aspects of wood modification by sol-gel-derived silica JF - Wood science and technology N2 - It has been shown that tetraethoxysilane-derived precursors are suitable solutions for impregnating pine sapwood to improve its dimensional stability. Tailored sol–gel syntheses result in precursors with nano-scaled silica species which are able to penetrate into the cell walls of wood. The physical fixation of those species inside the cell walls was verified by ESEM/EDX investigations. There is evidence that the silica species are chemically bonded to wood components. Nonreacted alkoxy groups can exist in the wood composites after impregnation. The amount of these organic residues depends on the composition of the precursors, especially their condensation degree and reactivity. Treatments for finishing the composites after the impregnation step to get clean products and stable properties are discussed in this context. An explanation of the complex relationship between solids content in the impregnation solutions and percentage weight gain and bulking of the composites is given. It can be demonstrated that high WPG values (>20 %) are pre-conditions for an effective protection of the resulting composites but they only guarantee efficient improvements if connected with the incorporation of the inorganic component inside the cell walls. Therefore, the sol–gel syntheses have to be carried out in such a manner that very small (<2 nm) as well as reactive species are sufficiently available. This demands syntheses using sub-stoichiometric water contents (H2O/TEOS <4, better <2). KW - Silica-wood composites KW - Sol-gel derived precursors KW - Curing KW - Fixation of silica KW - Dimensional stability PY - 2013 DO - https://doi.org/10.1007/s00226-012-0486-7 SN - 0043-7719 SN - 1432-5225 VL - 47 IS - 1 SP - 83 EP - 104 PB - Springer CY - Berlin AN - OPUS4-26258 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tiebe, Carlo A1 - Miessner, H. A1 - Koch, B. A1 - Hübert, Thomas T1 - Detection of microbial volatile organic compounds (MVOCs) by ion-mobility spectrometry JF - Analytical and bioanalytical chemistry N2 - Traces of microbial volatile organic compounds (MVOCs) in air can indicate the presence of growth of moulds in the indoor environment. Ion-mobility spectrometry is a very promising method for detection of these MVOCs, because of its high sensitivity. For development of an in-situ method for detection of MVOCs, a portable ion-mobility spectrometer (IMS) was used and test gases of 14 MVOCs and their respective mixtures were investigated. IMS spectra were recorded as a function of concentration of MVOCs in air. Drift time and mobility of reactant ions formed in positive polarity mode were determined and correlated with the mass-to-charge ratio (m/z) of the MVOCs investigated. The estimated detection limit has a specific value for each MVOC and is in the range 3 to 96 µg m-3 (1 to 52 ppbV). Indoor trials show that IMS can indicate hidden mould growth. KW - Trace gas analysis KW - MVOCs KW - Ion-mobility spectrometry KW - Mould detection PY - 2009 DO - https://doi.org/10.1007/s00216-009-3147-4 SN - 1618-2642 SN - 1618-2650 VL - 395 IS - 7 SP - 2313 EP - 2323 PB - Springer CY - Berlin AN - OPUS4-20082 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tiebe, Carlo A1 - Hübert, Thomas A1 - Lorek, A. A1 - Wernecke, R. T1 - New planar trace humidity sensor T2 - IMCS 2012 - 14th International meeting on chemical sensors N2 - A new planar sensor element for continuous coulometric trace humidity measurements in industrial gases has been developed. In order to ensure precise measurements a calibration facility including a precision dew point hygrometer as a reference device was developed. The sensor can measure the humidity in the frost point temperature range of -20 °C to -80 °C and has an expanded uncertainty of 2 K, a fast reaction time and a settling time of the entire system from 15 to 30 min. T2 - IMCS 2012 - 14th International meeting on chemical sensors CY - Nuremberg, Germany DA - 2012-05-20 KW - Trace humidity KW - Coulometric principle KW - HUMITRACE sensor KW - Humidity measurement PY - 2012 SN - 978-3-9813484-2-2 DO - https://doi.org/10.5162/IMCS2012/3.4.2 SP - 294 EP - 297 PB - AMA Service GmbH CY - Wunstorf AN - OPUS4-27570 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tiebe, Carlo A1 - Detjens, Marc A1 - Banach, Ulrich A1 - Hübert, Thomas T1 - Measurement uncertainty of coulometric trace humidity sensors JF - tm - Technisches Messen N2 - Especially trace amounts of water vapour in gases can be reliably determined by coulometric trace humidity sensors. The principle of these sensors is based on water vapour absorption in a hygroscopic layer and its subsequent electrolytic decomposition. The calibration of sensors was performed in the humidity range, expressed as frost point temperature, from −30°C to −80°C . This range is equivalent to volume fractions smaller than 376 µL·L−1. Generated humidity was measured with coulometric sensors and a chilled dew point hygrometer that was used as reference. An empirical non-linear function was found between sensor signal and measured reference humidity. This function consists of two parameters with a measurement uncertainty. Both calibration parameters were checked by means of one-way analysis of variance. It showed that gas specific function can be used for humidity measurement in nitrogen, hydrogen, dinitrogen monoxide, compressed and synthetic air. It is possible to determine trace humidity in all tested gases with an expanded uncertainty less than 2.1 K (coverage factor k=2 ) regarding frost point temperature. KW - Trace humidity KW - Coulometric sensor KW - Measurement uncertainty KW - ANOVA PY - 2018 DO - https://doi.org/10.1515/teme-2018-0031 SN - 0171-8096 VL - 85 IS - 12 SP - 746 EP - 753 PB - De Gruyter CY - Oldenbourg AN - OPUS4-45959 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tahri, K. A1 - Tiebe, Carlo A1 - El Bari, N. A1 - Hübert, Thomas A1 - Bouchikhi, B. T1 - Geographical provenience differentiation and adulteration detection of cumin by means of electronic sensing Systems and SPME-GC-MS in combination with different chemometric approaches JF - Analytical Methods N2 - The detection of the aroma and flavour volatile compounds of spices is key in product quality control. Accordingly, it is necessary to develop new electronic sensing systems for food adulteration control and authenticity assessment for protecting customer's health. In this work, the capability of the E-nose and VE-tongue in combination with SPME-GC-MS to correctly discriminate between several cumin samples of different geographical origins and to detect their adulteration, by using unsupervised and supervised chemometric tools, was evaluated. Regarding the aroma profile, eleven volatile compounds were characterized by SPME-GC-MS; all of them were found in cumin powder while only eight are found in cumin seeds. The main volatile compounds detected were b-pinene, m-cymene, g-terpinene, cuminaldehyde and cuminic alcohol, in different proportions depending on the cumin sample form (seed or powder). In summary, the results obtained are sufficiently encouraging as a starting point for the development of new electronic sensing systems with more improvement in the reliability of the sensor's performance as well as chemometric tools in order to deal with a complex dataset. KW - Voltammetric electronic tongue KW - Electronic nose KW - SPME-GC-MS KW - Chemometric tool KW - Cumin discrimination KW - Geographical origins KW - Adulteration detection PY - 2016 DO - https://doi.org/10.1039/c6ay01906d SN - 1759-9660 VL - 8 IS - 42 SP - 7638 EP - 7649 PB - RCS AN - OPUS4-38558 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tahri, K. A1 - Tiebe, Carlo A1 - El Bari, N. A1 - Hübert, Thomas A1 - Bouchikhi, B. T1 - Geographical classification and adulteration detection of cumin by using electronic sensing coupled to multivariate analysis JF - Procedia Technology - Special Issue Biosensors 2016 N2 - The objective of this work is to report the improvement obtained in the discrimination of complex aroma and taste with subtle differences in odor and flavor, by the use of fast suitable procedures for the cases of measurements in the field demanding decision-making in real time. The proposed electronic sensing systems, formed by an E-nose and VE-tongue, were used to discriminate cumin cultivars from different geographical origins, as well as to quantify the cumin adulteration percentages by using unsupervised and supervised chemometric tools. Thus, the results obtained are sufficiently encouraging as a starting point for the development of new electronic sensing systems with more improvement such the reliability of the sensors’ performance as well as the chemometric tools in order to deal with a complex dataset. KW - VE-tongue KW - E-nose KW - Chemometric tools KW - Cumin discrimination KW - Geographical origins KW - Adulteration detection PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-409735 DO - https://doi.org/10.1016/j.protcy.2017.04.102 SN - 2212-0173 VL - 27 SP - 240 EP - 241 PB - Elsevier B.V. AN - OPUS4-40973 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tahri, K. A1 - Tiebe, Carlo A1 - Bougrini, M. A1 - Saidi, T. A1 - El Alami-El Hassani, N. A1 - El Bari, N. A1 - Hübert, Thomas A1 - Bouchikhi, B. T1 - Determination of safranal concentration in saffron samples by means of VE-tongue, SPME-GC-MS, UV-vis spectrophotometry and multivariate analysis T2 - Proceedings of IEEE Sensors 2015 N2 - 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. T2 - IEEE Sensor 2015 CY - Busan, South Korea DA - 01.11.2015 KW - Chemometrics KW - Voltammetric electronic tongue KW - SPME-GC-MS KW - UV-vis Spectrometry KW - Saffron KW - Geographic differentiation PY - 2015 SN - 978-1-4799-8202-8 VL - CFP15SEN-USB SP - 68 EP - 71 PB - IEEE CY - Piscataway AN - OPUS4-36545 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tahri, K. A1 - Tiebe, Carlo A1 - Bougrini, M. A1 - Saidi, T. A1 - El Alami El Hassani, N. A1 - El Bari, N. A1 - Hübert, Thomas A1 - Bouchikhi, B. T1 - Characterization and discrimination of saffron by multisensory systems, SPME-GC-MS and UV-Vis spectrophotometry JF - Analytical methods N2 - Different electronic sensor systems coupled with multivariate data analysis were applied to characterize and classify seven saffron samples and to verify their declared geographical origin. The proposed electronic sensing consists of a low-cost electronic nose (E-nose) based on metal oxide semiconductor sensors and a voltammetric electronic tongue (VE-tongue) based on voltammetric sensors. The ability of multivariable analysis methods such as Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA) and Support Vector Machines (SVMs) to classify the saffron samples according to their geographical origin have been investigated. Both PCA and HCA have shown an overlapping of E-nose responses. Moreover, the SVM analysis of the E-nose database reached a 66.07% success rate in the recognition of the saffron sample odour. On the other hand, good discrimination has been reached using PCA and HCA in the VE-tongue characterization case, besides a 100% accuracy in the saffron flavour recognition was attained. To validate the proposed electronic sensing systems, analytical chemical methods such as SPME-GC-MS and UV-Vis spectrophotometry were used. These analytical methods could be helpful tools to identify the composition of volatile compounds of the analysed saffron samples. Moreover, UV-Vis spectrophotometry was also used to determine the non-volatile profile of the samples from different geographic origins. It is demonstrated that the electronic sensing systems' findings are in a satisfactory correlation with the analytical methods. In the light of these results, we might say that the electronic systems offer a fast, simple and efficient tool to recognize the declared geographical origin of the saffron samples. KW - Electronic nose KW - Voltammetric electronic tongue KW - SPME-GC-MS KW - UV-vis spectrophotometry KW - Saffron KW - Geographic differentiation KW - Multivariable analysis PY - 2015 DO - https://doi.org/10.1039/C5AY01986A SN - 1759-9660 SN - 1759-9679 VL - 7 IS - 24 SP - 10328 EP - 10338 PB - RSC Publ. CY - Cambridge AN - OPUS4-35174 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shimamura, Aki A1 - Hübert, Thomas A1 - Thust, H. T1 - Characterization of sol-gel derived glass composite thin films JF - Surface and interface analysis N2 - A comprehensive analysis of composition and structure is essential for the development of new materials with tailored properties. We will demonstrate the application of SEM, XPS and XRD for the development of thin films containing nano-scaled electrical conductive particles for application in hybrid resistors. The films were prepared using the sol-gel process and precursor solutions were synthesized from an acid hydrolysis of a mixture of TEOS, water and ethanol. Alcoholic solutions of ruthenium chloride were then allocated to obtain up to 30 vol% filler in the films. The films were precipitated by dip-coating on silicon, silica or glass sheets and heat treated at up to 600°C in air or nitrogen atmospheres. A nano-structured morphology could be identified consisting of homogeneously dispersed crystalline RuO2 particles of 10 to 180 nm in size, in an amorphous SiO2 matrix. Film morphology can be varied using the synthesis process. The resistivity of the films was measured by an I-V measurement system. It changes drastically from 109·cm to 10-2·cm according to the amount of dispersed conductive particles. The results show that composition-structure-property relations can be described by use of sophisticated analytical methods. T2 - 10th European Conference on Applications of Surface and Interface Analysis (ECASIA '03) CY - Berlin, Germany DA - 2003-10-05 KW - Sol-gel KW - Thin film KW - Nano-structure KW - Electrical resistivity KW - RuO2 PY - 2004 DO - https://doi.org/10.1002/sia.1877 SN - 0142-2421 SN - 1096-9918 VL - 36 IS - 8 SP - 1207 EP - 1209 PB - Wiley CY - Chichester AN - OPUS4-4753 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shabir Mahr, Muhammad A1 - Hübert, Thomas A1 - Stephan, Ina A1 - Militz, H. T1 - Decay protection of wood against brown-rot fungi by titanium alkoxide impregnations JF - International biodeterioration & biodegradation N2 - Decay resistance of pine sapwood treated with titanium alkoxide solutions was tested against the brown-rot fungi Coniophora puteana and Poria placenta for exposure times of 10 and 16 wk. In practice, wood-specimens were vacuum-impregnated by alcoholic solutions of titanium alkoxide with concentrations in the range of 5–16 mass % (solid content in solution) and subsequently cured under different humidity conditions. Results reveal that treated wood degraded up to 5% in comparison to untreated one that deteriorated 38% and 50%, respectively against both wood-decay fungi. Even full protection (mass loss below 3%) was achieved against brown rot with titanium alkoxide solution containing solid content of around 5 mass% with a weight percentage gain (WPG) of 9 mass%. With increased concentration, fungal resistance decreased slightly which was associated with more cracks and imperfections formed in the deposited layers of titanium dioxide in the adjacent wood matrix. Thermal analysis verified that a considerable amount of precursor remained in the wood structure as un-hydrolyzed organic residues. These organics, being bioactive, had the tendency to induce similar fungicidal effects as those of conventional fungicides. The amount of organic residues is correlated with the decay resistance of the tested samples. In a prolonged decay test, mass losses of 16-wk incubated samples do not show behavior different from that of the wood samples incubated for 10 wk. This result implies that the decay protection is permanent and confirms further the fungicidal activity of titanium-alkoxide-treated wood. KW - Precursor solutions KW - Sol-gel process KW - Equivalent solid content KW - Brown rot KW - Coniophora puteana KW - Poria placenta KW - Fungal colonization KW - Biocidal effect PY - 2013 DO - https://doi.org/10.1016/j.ibiod.2012.04.026 SN - 0964-8305 VL - 77 SP - 56 EP - 62 PB - Elsevier Ltd. CY - Barking AN - OPUS4-27622 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shabir Mahr, Muhammad A1 - Hübert, Thomas A1 - Stephan, Ina A1 - Bücker, Michael A1 - Militz, H. T1 - Reducing copper leaching from treated wood by sol-gel derived TiO2 and SiO2 depositions JF - Holzforschung N2 - The antileaching efficacy of sol-gel-derived TiO2- and SiO2-based precursors has been evaluated through laboratory leaching trials with pine sapwood in two different ways. In a one-step process, wood was vacuum impregnated by the precursor solutions containing CuCl2. The copper (Cu) emission rates of the sol-gel-based impregnated woods were up to 70% lower than that of wood treated with pure CuCl2 solution at the same level of concentration. More improvement (80%) could be achieved in a two-step process, in which sol-gel precursors were introduced into an already CuCl2-treated wood. The refinement was attributed to several effects. In the one-step approach, Cu was embedded in the TiO2/SiO2 gels formed in the wood texture. During a two-step impregnation, gel layers that were formed in the wooden interior acted as an effective diffusion barrier. The sol-gel impregnations made wood more hydrophobic; therefore, the low amount of water that penetrated the cell wall was less efficient to leach out Cu. KW - Copper leachability KW - SiO2-based gel KW - Sol-gel treatment of wood KW - TiO2-based gel KW - Wood impregnation KW - Wood protection PY - 2013 DO - https://doi.org/10.1515/hf-2012-0105 SN - 0018-3830 SN - 1437-434X VL - 67 IS - 4 SP - 429 EP - 435 PB - De Gruyter CY - Berlin AN - OPUS4-28892 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shabir Mahr, Muhammad A1 - Hübert, Thomas A1 - Schartel, Bernhard A1 - Bahr, Horst A1 - Sabel, Martin A1 - Militz, H. T1 - Fire retardancy effects in single and double layered sol-gel derived TiO2 and SiO2-wood composites JF - Journal of sol gel science and technology N2 - Sol–gel derived TiO2 and SiO2-wood inorganic composites are prepared by direct vacuum infiltration of silicon and titanium alkoxide based precursors in pine sapwood in one or two cycles followed by a controlled thermal curing process. The resulting flame retardancy effect is investigated under two different fire scenarios using cone calorimetry and oxygen index (LOI). Heat release rates (HRR) especially the values for the second peak, are reduced moderately for all single layered composites. This effect is more pronounced for double layered composites where HRR was reduced up to 40 % showing flame retardancy potential in developing fires. Beside this, smoke release was lowered up to 72 % indicating that these systems had less fire hazards compared to untreated wood, whereas no meaningful improvement is realized in terms of fire load (total heat evolved) and initial HRR increase. However impressively, the LOI of the composites were increased up to 41 vol% in comparison to 23 vol% for untreated wood displaying a remarkable flame retardancy against reaction to a small flame. An approximate linear interdependence among the fire properties and the material loading as well as fire residue was observed. A residual protection layer mechanism is proposed improving the residue properties for the investigated composites. KW - Wood KW - Sol-gel KW - Composite materials KW - Cone calorimeter KW - Fire retardance KW - Flammability PY - 2012 DO - https://doi.org/10.1007/s10971-012-2877-5 SN - 0928-0707 SN - 1573-4846 VL - 64 IS - 2 SP - 452 EP - 464 PB - Kluwer Academic Publ. CY - Dordrecht AN - OPUS4-27618 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shabir Mahr, Muhammad A1 - Hübert, Thomas A1 - Sabel, Martin A1 - Schartel, Bernhard A1 - Bahr, Horst A1 - Militz, H. T1 - Fire retardancy of sol-gel derived titania wood-inorganic composites JF - Journal of materials science N2 - Sol–gel technology was applied in tailoring novel wood-made-inorganic composites with improved thermal and fire properties. In practice, composites materials were prepared by impregnating pine sapwood wood with nano-scaled precursor solutions derived from titanium(IV) isopropoxide followed by a thermal curing process. Thermal and fire properties were evaluated by thermal analysis and cone calorimetry, whereas flammability was specified by oxygen index (LOI) and UL 94 test. Peak heat release rates were moderately reduced indicating fire retardance potential in terms of flame spread attributed to the appropriate protection layer action of the titania-based depositions. LOI (oxygen index) values of these composites were increased up to 38 vol.% in comparison to 23 vol.% for untreated wood. The flame retardancy performance depends on the fire scenario and is strongly influenced by wood loading and crackfree deposition of the titania layers inside the composite. PY - 2012 DO - https://doi.org/10.1007/s10853-012-6628-3 SN - 0022-2461 SN - 1573-4803 VL - 47 IS - 19 SP - 6849 EP - 6861 PB - Springer Science + Business Media B.V. CY - Norwell, Mass. AN - OPUS4-26235 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reinecke, E.-A. A1 - Hübert, Thomas A1 - Tkatschenko, I. A1 - Kessler, A. A1 - Kuznetsov, M. A1 - Wilkins, M. A1 - Hedley, D. A1 - Azkarate, I. A1 - Proust, C. A1 - Acosta-Iborra, B. A1 - Gavrikov, B. A1 - De Bruijn, P.C.J. A1 - Marangon, A. A1 - Teodorczyk, A. A1 - Grafwallner, A. T1 - Integration of experimental facilities: a joint effort for establishing a common knowledge base in experimental work on hydrogen safety JF - International journal of hydrogen energy N2 - In the area of hydrogen safety, research facilities are essential for the experimental investigation of relevant phenomena, for testing devices and safety concepts, as well as for the generation of validation data for the various numerical codes and models. Within the framework of the European HySafe Network of Excellence (NoE), the 'Integration of Experimental Facilities (IEF)' activity has provided basic support for joint experimental work. Even beyond the funding period of the HySafe NoE in the 6th Framework Program, IEF represents a long-lasting effort for the sustainable integration of experimental research capacities and expertise of the partners from different research fields. In order to achieve a high standard in the quality of experimental data provided by the partners, emphasis was put on the know-how transfer between the partners. On the one hand, documentation on the experimental capacities was prepared and analyzed. On the other hand, a wiki-based communication platform was established, supported by biannual workshops covering topics ranging from measurement technologies to safety issues. Based on the partners' contributions, a working document was created on best practice including the joint experimental knowledge of all partners with regard to experimental set-ups and instrumentation. The paper gives an overview of the IEF partners and the network activities over the last five years. KW - Hydrogen safety KW - Experiments PY - 2011 DO - https://doi.org/10.1016/j.ijhydene.2010.04.162 SN - 0360-3199 VL - 36 IS - 3 SP - 2700 EP - 2710 PB - Elsevier CY - Oxford AN - OPUS4-23257 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Polyakova, Irina A1 - Hübert, Thomas T1 - Thermal stability of TiN thin films investigated by DTG/DTA JF - Surface and coatings technology N2 - The paper demonstrates the scope of the differential thermal analysis coupled with the thermal gravimetry as an express method for estimation of thin film protecting ability and oxidation kinetics. Oxidation of an iron foil protected by the PVD titanium nitride thin film coating was investigated as well as non-isothermal oxidation of PVD thin films of TiN (two types of the preparation procedure), (Ti,Nb)N and (Ti,Al)N isolated from a substrate by dissolving them in an acid. Additions of aluminium and niobium are expected to improve chemical, thermal and biomedical properties of thin films for their technical application. It was established that the addition of niobium decreases, whereas the addition of aluminium not only increases the thermal stability of TiN coatings, but also changes the oxidation mechanism. It was demonstrated that the TiN film oxidation is a many-staged process depending on the heating rate. An opportunity of a quite formal treatment for getting Kissinger's estimation of kinetics parameters of different oxidation stages is also demonstrated. PY - 2001 DO - https://doi.org/10.1016/S0257-8972(01)01042-8 SN - 0257-8972 VL - 141 IS - 1 SP - 55 EP - 61 PB - Elsevier Science CY - Lausanne AN - OPUS4-2050 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nie, Yaru A1 - Hübert, Thomas T1 - Effect of carbon nanofiber (CNF) silanization on the properties of CNF/epoxy nanocomposites JF - Polymer International N2 - Carbon nanofibers (CNFs) were functionalized by a multistage process including oxidation, reduction and silanization. The chemical modifications were examined by Fourier transform infrared spectroscopy, X-ray photoelectron spectrometry, Raman spectroscopy and thermogravimetric analysis. The silanized CNFs were then added into an epoxy resin (EPON 828) to study the effect of the surface modification of CNFs on the properties of nanocomposites. For comparison, nanocomposites containing original unmodified CNFs were also investigated. Scanning electron microscopy indicates better dispersion of modified fibers in the epoxy polymer matrix; the mechanical and thermal properties of composites are also improved; the electrical conductivity of the composites is reduced. KW - Carbon nanofibers KW - Epoxy composites KW - Silanization KW - Electrical conductivity KW - Thermal conductivity KW - Mechanical properties PY - 2011 DO - https://doi.org/10.1002/pi.3124 SN - 0959-8103 SN - 1097-0126 SN - 0007-1641 VL - 60 IS - 11 SP - 1574 EP - 1580 PB - Wiley InterScience CY - Chichester, West Sussex AN - OPUS4-25865 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nie, Yaru A1 - Hübert, Thomas T1 - Surface modification of carbon nanofibers by glycidoxysilane for altering the conductive and mechanical properties of epoxy composites JF - Composites / A N2 - Carbon nanofibers (CNFs) were functionalized with 3-glycidoxypropyltrimethoxysilane and dispersed into epoxy resin. The chemical modification of CNFs was confirmed by FTIR, SEM, EDX and TGA measurements. After silanization, FTIR showed the existance of epoxy ring; EDX detected Si element; while TGA indicated 1.1 wt.% Si on CNFs. Mechanical properties were analyzed by DMA. Silanized CNFs/epoxy composites demonstrated improved dispersion of CNFs in the matrix, and an enhancement of storage modulus for about 20% compared to the neat matrix, which indicated that the modification of CNFs improved the adhesion between fillers and matrices. DC electrical conductivity of CNFs was reduced about 7-fold compared to the original CNFs due to the silane coating. Accordingly, the composites containing silanized CNFs also had lower electrical conductivity than those containing original CNFs. In spite of decreased electrical conductivity, thermal conductivity of silanized CNFs/epoxy composites was increased due to the surface modification of CNFs. KW - A. Polymer-matrix composites (PMCs) KW - B. Mechanical properties KW - B. Electrical properties KW - B. Thermal properties PY - 2012 DO - https://doi.org/10.1016/j.compositesa.2012.03.025 SN - 1359-835X VL - 43 IS - 8 SP - 1357 EP - 1364 PB - Elsevier CY - Oxford AN - OPUS4-26073 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mosel, Günter A1 - Willfahrt, Manfred A1 - Banach, Ulrich A1 - Hübert, Thomas T1 - An extended X-ray absorption fine structure investigation on the local environment of niobium ions in Nb2O5-doped SrTiO3 glass ceramics JF - Journal of materials science PY - 1997 SN - 0022-2461 SN - 1573-4803 VL - 32 SP - 1591 EP - 1597 PB - Springer Science + Business Media B.V. CY - Norwell, Mass. AN - OPUS4-2045 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mosel, Günter A1 - Hübert, Thomas A1 - Nofz, Marianne A1 - Brenneis, Rudolf A1 - Köcher, Peter A1 - Kley, Gerd T1 - Zn-K EXAFS investigations on ZnS/ZnO containing vitrified ashes from municipal incinerator facilities JF - Journal of materials science N2 - Zn-K transmission EXAFS measurements were performed on vitrified ashes from municipal waste incinerator facilities, which contain low amounts of Zn (up to 3 wt%) and sulphur (up to 0.5 wt%) in a ZnS phase. From the Fourier transform it can be concluded that the zinc ions are fourfold co-ordinated by oxygen or sulphur ions. The amount of zinc ions of sulphur environment, e.g. the concentration of ZnS, was determined by Fourier filtering and subsequent parameter fitting. A quantitative analysis of low ZnS concentrations up to 1 wt% has been performed for samples with a molar ratio Zn/S < 5. PY - 2001 DO - https://doi.org/10.1023/A:1011802202743 SN - 0022-2461 SN - 1573-4803 VL - 36 SP - 5017 EP - 5025 PB - Springer Science + Business Media B.V. CY - Norwell, Mass. AN - OPUS4-18579 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Massiot, D. A1 - Müller, D. A1 - Hübert, Thomas A1 - Schneider, M. A1 - Kentgens, A. A1 - Coté, B. A1 - Coutures, J. A1 - Gessner, W. T1 - Double rotation and magic-angle spinning nuclear magnetic resonance study of 27Al: reexamination of the aluminium borate 9Al2O3 · 2B2O3 JF - Solid state nuclear magnetic resonance N2 - 27Al nuclear magnetic resonance spectra of polycrystalline aluminium borate 9Al2O3 · 2B2O3 have been measured in double rotation at 11.7 and 7.0 T and high-speed magic-angle spinning at 7.0, 9.4, 11.7, 14.1 and 17.6 T. Spinning sidebands from the satellite transitions were observed at 7.0 and 14.1 T. Each of the four structural aluminium sites [Al(IV), Al(V)(1), Al(V)(2) and Al(VI)] are observed, characterised and assigned in the spectra. The obtained parameter set gives a fully consistent interpretation in agreement with the crystal structure of the compound. KW - Aluminium KW - Kernresonanz, magnetisch KW - Winkel, magisch KW - Doppelrotation PY - 1995 DO - https://doi.org/10.1016/0926-2040(95)00021-H SN - 0926-2040 SN - 1527-3326 VL - 5 IS - 2 SP - 175 EP - 180 PB - Academ. Press CY - Orlando, Fla. AN - OPUS4-639 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lippitz, Andreas A1 - Hübert, Thomas T1 - XPS investigations of chromium nitride thin films JF - Surface and coatings technology N2 - Cr–N film coatings were prepared by magnetron sputter deposition at different nitrogen partial pressures. The film characterisation by XRD and DTG gives average bulk compositions of Cr2N and CrN for the coatings. Highly sensitive XPS investigations were performed and the chemical and phase compositions of a film surface range of about 10 nm thickness was estimated quantitatively from the deconvoluted peak intensities. It is demonstrated that the composition of the surface of chromium nitride thin films differs from the core and is more complex in constitution. Not only chromium nitrides (Cr2N and CrN) but also chromium oxynitrides and chromium oxides (CrOx and CrOxHy) were detected. Metallic chromium was also found in films prepared at higher nitrogen flow. The concentration of the estimated phases shows dependence on film preparation and additional heat treatment. KW - XPS KW - ESCA KW - Physical vapour deposition (PVD) KW - CrN thin films PY - 2005 DO - https://doi.org/10.1016/j.surfcoat.2005.02.091 SN - 0257-8972 VL - 200 IS - 1-4 SP - 250 EP - 253 PB - Elsevier Science CY - Lausanne AN - OPUS4-10865 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lang, M. A1 - Banach, Ulrich A1 - Nörthemann, K. A1 - Gerlitzke, A.-K. A1 - Milstrey, M. A1 - Kaufer, R. A1 - Woratz, M. A1 - Hübert, Thomas A1 - Moritz, W. T1 - Long-term stability of a MEIS low energy hydrogen sensor JF - Sensors and actuators B: Chemical N2 - A hydrogen sensor based on a silicon Metal/Solid Electrolyte/Insulator/Semiconductor (MEIS) structure with thin layers of the super-ionic conductor LaF3 and Pd gate metal was investigated in a hybrid structure on a resistance heater mounted on a ceramic substrate. The sensor was operated at room temperature, however, a short heating impulse once a day ensures a fast and reproducible dynamic behavior. The sensor was characterized in the concentration range typical for alarm levels up to 40% of the lower flammability limit and shows a logarithmic dependency of the sensor signal from the hydrogen concentration and a mean sensitivity of about 140 mV/decade. The response time (t90) is about 8 s. In a long term test for a period of three month, the sensor was exposed to hydrogen every two weeks. The sensor signal was shown to be stable in dynamic behavior, sensitivity and signal difference. KW - Hydrogen detection KW - Long-term measurement KW - MEIS-structure KW - Low energy sensor PY - 2013 DO - https://doi.org/10.1016/j.snb.2012.12.081 SN - 0925-4005 SN - 1873-3077 VL - 187 SP - 395 EP - 400 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-29223 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Willfahrt, Manfred A1 - Witke, Klaus A1 - Reich, Peter T1 - Low Frequency Raman Investigations of Lead Borate and Lead Alumino Borate Glasses JF - Journal of molecular structure PY - 1995 SN - 0022-2860 SN - 1872-8014 SN - 0377-046X VL - 349 SP - 373 EP - 376 PB - Elsevier CY - Amsterdam AN - OPUS4-3776 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Unger, Brita A1 - Bücker, Michael T1 - Sol-gel derived TiO2 wood composites JF - Journal of sol gel science and technology N2 - The sol–gel process was applied to enhance properties of pine sapwood. For this purpose wood prisms were soaked in nanoscaled precursor solutions prepared from titanium(IV) n-butoxide and titanium(IV) iso-propoxide, respectively, using vacuum impregnation technique. The wet composites were cured by special program with final heat treatment at 103 °C. Weight percent gains (WPG) of the wood specimen in the range of 19-25% were obtained due to these procedures. SEM investigations show that precursor solutions penetrate into the whole wood body and the titania formed after heat treatment in the composites is deposited in the pores (lumen) and partly in the cell walls of the wooden matrix. The moisture sorption was investigated in long term tests for a period of some months by storage at 20-23 °C in humid air (relative humidity of 99%) and ambient atmosphere (relative humidity 40-60%), respectively. For untreated reference samples the moisture sorption results in increasing of mass and volume according to saturation values of 24 and 13%, respectively, after about 15 days. The incorporation of titania reduces the saturation values of the moisture sorption by up to 12% in mass and by up to 5% in volume at a relative humidity of 99%. Thus, an enhancement of the dimensional stability of about 60% is obtained at best. The results demonstrate that modification of wood with sol-gel derived precursors can enhance its dimensional stability, which prevents the formation of cracks. Because of that reduced moisture sorption biological attacks should be delimited. Additionally, thermal analyses show a retarded combustion of the wood matrix due to titania infiltration. KW - Titania KW - Sol-gel KW - Nanocomposites KW - Wood protection KW - Water sorption PY - 2010 DO - https://doi.org/10.1007/s10971-009-2107-y SN - 0928-0707 SN - 1573-4846 VL - 53 IS - 2 SP - 384 EP - 389 PB - Kluwer Academic Publ. CY - Dordrecht AN - OPUS4-20892 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Tiebe, Carlo A1 - Stephan, Ina T1 - Detection of fungal infestations of wood by ion mobility spectrometry JF - International biodeterioration & biodegradation N2 - During their growth on wood many fungi produce characteristic volatile organic compounds as secondary metabolites. These microbial volatile organic compounds (MVOCs) can be used as indicators of fungal growth even when such growth is concealed. In order to investigate the formation of these volatile metabolites on building materials, specimens of pine sapwood on agar media colonized by the dry-rot fungus Serpula lacrymans and a mixture of six moulds were examined. MVOCs from this fungal growth were studied over a period of up to half a year by ion mobility spectrometry (IMS) headspace analysis using a sensitive, portable IMS mini-device. The IMS headspace spectra from the growing fungal specimens obtained during this time span are differed from non-incubated wood specimens and indicate the presence of a mixture of MVOCs. The composition and amount of volatile metabolites of the fungi changed during cultivation. This was confirmed by a principal component analysis (PCA). Identification of different MVOCs in the headspace according to drift time and the mobility of ionized gaseous species in reference to GC-MS investigations were proposed. It was concluded that IMS can be used as a rapid and sensitive on-site method to indicate actively growing fungi concealed within wood. KW - Dry rot KW - Serpula lacrymans KW - Moulds KW - Concealed infestation KW - Ion mobility spectrometry KW - Fungal detection PY - 2011 DO - https://doi.org/10.1016/j.ibiod.2011.03.008 SN - 0964-8305 VL - 65 IS - 5 SP - 675 EP - 681 PB - Elsevier CY - Barking AN - OPUS4-23994 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Tiebe, Carlo A1 - Detjens, Marc A1 - Majewski, J. T1 - On-site calibration system for trace humidity sensors JF - Measurement N2 - A portable device for calibration of trace humidity sensors and an adopted calibration procedure have been developed. The calibration device is based on humidity generation by permeating water through polymeric membrane tubes. Water vapour transmission rates for various polymers were experimentally determined in order to select the most suitable polymeric material. The developed trace humidity generator consists of a gas-flow polymeric hose immersed in a water reservoir thermostated by a sensorcontrolled heater. Mole fractions of water vapour between 1 µmol/ molˉ¹ and 350 µmol/molˉ¹ (equivalent to frost-point temperatures from -76 °C to -31 °C) were generated by varying either the operating temperature or gas flow. The operating temperature can be varied from 20 °C to 60 °C and kept stable within 0.1 K. Uncertainty analysis indicated that the trace humidity generator produces gas flows of constant humidity amounts with a relative expanded uncertainty less than 3.4% (k = 2) of the generated value. KW - Polymeric tubes KW - Measurements KW - Trace Humidity KW - Sensor calibration KW - Water vapour permeation PY - 2016 DO - https://doi.org/10.1016/j.measurement.2016.05.013 SN - 0263-2241 VL - 91 IS - 9 SP - 251 EP - 257 PB - Elsevier Ltd. AN - OPUS4-36762 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Svoboda, S. A1 - Oertel, B. T1 - Wear resistant alumina coatings produced by a sol-gel process JF - Surface and coatings technology N2 - Aluminium oxide films were prepared by a dip-coating procedure from solutions of hydrolysed aluminium-tri-sec-butoxide in methoxyethanol on austenitic steel as well as hard metal tools. The heat treatment was performed in an argon atmosphere or vacuum at temperatures up to 1100 °C. Characterisation of the coatings by SEM, showed nearly crack free coatings with a dense morphology which completely cover the substrate. The chemical composition of the coatings was investigated by ESCA, GD-OES and XRD measurements. This analysis detected a multi-layered arrangement of spinel phases, ?- and ?-alumina in the coatings. The scratch test showed sufficient adhesion of the coatings comparable to CVD layers. Pin-on-disc and oscillating sliding tests were carried out on sol–gel coated samples and also on uncovered reference samples. The determined wear rates and friction coefficients showed significant improvement in wear resistance of sol–gel coatings containing a corundum phase. The strong adhesion to the substrates is due to a layered assembly formation and gradient composition of the coating caused by an interdiffusion of metal cations and oxygen in the metal/oxide interface during heat treatment. KW - Oxide film formation KW - Film analysis KW - Wear resistance PY - 2006 DO - https://doi.org/10.1016/j.surfcoat.2005.11.014 SN - 0257-8972 VL - 201 IS - 1-2 SP - 487 EP - 491 PB - Elsevier Science CY - Lausanne AN - OPUS4-18583 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Shimamura, Aki A1 - Klyszcz, Andreas T1 - Electrical Properties of Carbon Black and Ruthenium Dioxide Embedded Silica Films JF - Journal of sol gel science and technology N2 - The electrical properties of sol–gel-derived films can be tailored by embedding conductive particles of ruthenium dioxide or carbon black in an insulating amorphous SiO2 silica matrix. The preparation process included an acid hydrolysis of tetraethoxysilane and methyltrimethoxysilane. Then alcohol solutions of ruthenium chloride or carbon black were added. Films of filler concentration up to 60 vol.% were prepared by dip coating and then dried and heat-treated at various temperatures up to 600_°C. The D.C. resistance of the films can be varied within the range of 109 to 10–2 OHgr sdot cm. A non-linear dependence on filler composition in the films was observed for both systems, which is explained by a modified percolation theory. A percolation threshold of 5.5 vol.% for SiO2-RuO2 or 50 vol.% for SiO2-C films, whereby the resistance drastically decreases, was determined. Moreover the temperature dependency of resistance and the current-voltage characteristics of the films can also be explained by this geometric model. KW - Sol-gel KW - Thin films KW - Carbon black KW - Ruthenium dioxide KW - Percolation phenomena PY - 2004 DO - https://doi.org/10.1007/s10971-004-5777-5 SN - 0928-0707 SN - 1573-4846 VL - 32 SP - 131 EP - 135 PB - Kluwer Academic Publ. CY - Dordrecht AN - OPUS4-6909 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Shimamura, Aki A1 - Klyszcz, Andreas T1 - Carbon-silica sol-gel derived nanomaterials JF - Materials science : international journal N2 - The preparation of sol-gel derived silica-based nanomaterials containing electrical conductive carbon fillers in an extensive composition range is described and their electrical properties are presented. Nanomaterials of carbon filler concentrations up to 60% (v/v) were obtained by dip coating or screen-printing from precursors of hydrolysed alkoxysilanes. Nanostructured morphology could be identified to consist of homogeneously dispersed carbon black particles or carbon fibres of 30 to 500 nm in size in a modified silica matrix. The electrical resistivity of the films changes drastically from 1010 to 10?1 O?cm, according to the amount of dispersed conductive particles. A threshold between 5 and 50% (v/v), at which the resistance abruptly decreases, was determined. A geometrical model related to percolation theory explains this non-linear dependence on the filler composition in the materials. Moreover the temperature dependence of resistance and the current-voltage characteristics of the nanomaterials can also be illustrated using this geometric model. KW - Sol-gel KW - Nanomaterials KW - Carbon black KW - Electrical resitivity KW - Percolation PY - 2005 UR - http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.123.3004&rep=rep1&type=pdf SN - 0137-1339 VL - 23 IS - 1 SP - 61 EP - 68 PB - Technical Univ. Press CY - Wroclaw AN - OPUS4-7362 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Schwarz, J. A1 - Oertel, B. T1 - Sol-gel alumina coatings on stainless steel for wear protection JF - Journal of sol gel science and technology N2 - The aluminium oxide films on austenitic steel are prepared from sols of re-dispersed boehmite nano powders in water. After dip-coating of the sol, a heat treatment including drying, calcination and annealing in vacuum at temperatures up to 1100°C is performed to obtain crack-free coatings of a thickness up to 6 µm. XRD measurements detect α- and γ-alumina, a TiOx-phase at the metal/coating interface and a gradient of phase formation in the coating. The strong adhesion on the substrates is due to the layered assembly and gradient composition of the coating caused by an inter-diffusion of metal cations and oxygen in the metal/oxide interface during heat treatment. Residual stress measurements by X-rays result in compressive stresses of 2–4 GPa in the alumina coatings. The pin-on-disc test shows a remarkable improvement of wear resistance obtained by sol-gel coatings. The α-alumina content and the compressive stress of the coatings correlate with wear resistance of the coatings. KW - Alumina KW - Sol-gel KW - Coating KW - Wear protection KW - Residual stress PY - 2006 DO - https://doi.org/10.1007/s10971-006-6470-7 SN - 0928-0707 SN - 1573-4846 VL - 38 IS - 2 SP - 179 EP - 184 PB - Kluwer Academic Publ. CY - Dordrecht AN - OPUS4-12435 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Schuffenhauer, W. A1 - Wernecke, R. T1 - Selbstüberwachendes und -regenerierendes System zur Online-Spurenfeuchtemessung in chemischen Prozessgasen JF - Chemie - Ingenieur - Technik PY - 2000 DO - https://doi.org/10.1002/1522-2640(200011)72:11<1376::AID-CITE1376>3.0.CO;2-C SN - 0009-286X SN - 1522-2640 VL - 72 IS - 11 SP - 1380 EP - 1382 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-2048 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Schuffenhauer, W. A1 - Wernecke, R. T1 - Self-Monitoring and Self-Regenerating System for On-line Measuring of Moisture Traces in Chemical Process Gases JF - Chemical engineering & technology PY - 2002 DO - https://doi.org/10.1002/1521-4125(200205)25:5<492::AID-CEAT492>3.0.CO;2-L SN - 0930-7516 SN - 1521-4125 VL - 25 IS - 5 SP - 492 EP - 494 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-3777 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Mosel, Günter A1 - Witke, Klaus T1 - Structural Elements in Borovanadate Glasses JF - Glass physics and chemistry N2 - The structure of glasses in the Li2O–B2O3–V2O5and ZnO–B2O3–V2O5systems of a high modifier content ([Li2O, ZnO]/[B2O3] ratio > 1) and 10 to 50 mol % V2O5are investigated by V-KEXAFS and Raman spectroscopy. In the glasses investigated, VO4tetrahedra are the predominant coordination polyhedra for the vanadium ions. The symmetry of the tetrahedra is more or less distorted in comparison with crystalline substances. The VO4tetrahedra can be either directly connected to each other or incorporated into the borate groupings of the BO3and BO4units. An increase in the vanadium content in the glasses reduces the interconnection of structural units and, therefore, the glass transition and crystallization temperatures. T2 - International Conference "Thermodynamics and Chemical Structure of melts and Glasses" CY - St. Petersburg, Russia DA - 1999-09-07 PY - 2001 DO - https://doi.org/10.1023/A:1011376225695 SN - 1087-6596 SN - 1608-313X VL - 27 IS - 2 SP - 114 EP - 120 PB - Pleiades Publ. CY - New York, NY AN - OPUS4-2049 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Lang, Cindy T1 - Artificial fruit: postharvest online monitoring of agricultural food by measuring humidity and temperature JF - International Journal of Thermophysics N2 - An online monitoring of environmental and inherent product parameters is required during transportation and storage of fruit and vegetables to avoid quality degradation and spoilage. The control of transpiration losses is suggested as an indicator for fruit freshness by humidity measurements. For that purpose, an electronic sensor is surrounded by a wet porous fiber material which is in contact with the outer atmosphere. Transpiration reduces the water content of the porous material and thus also the internal water activity. The sensor system, known as 'artificial fruit,' measures the relative humidity and temperature inside the wet material. Humidity and temperature data are collected and transmitted on demand by a miniaturized radio communication unit. The decrease in the measured relative humidity has been calibrated against the mass loss of tomatoes under different external influencing parameters such as temperature, humidity, and air flow. Current battery life allows the sensor system, embedded in a fruit crate, to transmit data on transpiration losses via radio transmission for up to two weeks. KW - Agricultural food KW - Relative humidity KW - Transpiration losses KW - Water activity PY - 2012 DO - https://doi.org/10.1007/s10765-011-1101-0 SN - 0195-928X SN - 1572-9567 VL - 33 IS - 8-9 SP - 1606 EP - 1615 PB - Springer CY - Dordrecht AN - OPUS4-27343 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Hattermann, Hilke A1 - Griepentrog, Michael T1 - Sol-gel-derived nanocomposite coatings filled with inorganic fullerene-like WS2 JF - Journal of sol gel science and technology N2 - Silica coatings filled with nanoscaled inorganic fullerene-like tungsten disulphide (IF-WS2) have been prepared through a sol–gel process on stainless steel substrates, and the structure and mechanical properties have been investigated. The precursor was prepared from a mixture of colloidal silica, 3-glycidoxypropyltrimethoxysilane (GLYMO), water and ethanol, adjusted to pH 4 with HNO3. In this solution WS2 is dispersed and in some cases immediately before coating ethylenediamine (ED) is added. The stainless steel substrates are dip-coated, dried in air and heat-treated in the temperature range of either 150–360 °C in air or up to 900 °C in vacuum. The solidification process is followed by differential thermal analysis (DTA). The resulting brown coloured coatings have a thickness of 1.5–4 µm. Scanning electron microscopy investigations (SEM) show that the WS2 nanoparticles are embedded as small aggregates in a hybrid silica matrix. X-ray diffraction (XRD) measurements prove that most of the tungsten disulphide embedded in the matrix can be protected against oxidation even after curing the samples at temperatures up to 900 °C. Hardness and modulus of the hybrid silica films were measured through an instrumented indentation test. Increasing the temperature of the heat treatment yields an increase of hardness from 0.3 to 1 GPa and of modulus from 3 to 17 GPa. The amount of up to 10 wt.% WS2 in the coatings has no remarkable influence on hardness and modulus of the samples. KW - Nanocomposites KW - Tungsten disulphide KW - Sol-gel KW - Mechanical properties PY - 2009 DO - https://doi.org/10.1007/s10971-009-1896-3 SN - 0928-0707 SN - 1573-4846 VL - 51 IS - 3 SP - 295 EP - 300 PB - Kluwer Academic Publ. CY - Dordrecht AN - OPUS4-19713 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hübert, Thomas A1 - Boon-Brett, L. A1 - Palmisano, V. A1 - Frigo, G. A1 - Hellstrand, A. A1 - Kiesewetter, O. A1 - May, M. ED - Carcassi, M.N. T1 - Trends in gas sensor development for hydrogen safety T2 - ICHS2013 - 5th International conference on hydrogen safety (Proceedings) N2 - Gas sensors are applied for facilitating the safe use of hydrogen in, for example, fuel cell and hydrogen fuelled vehicles. New sensor developments, aimed at meeting the increasingly stringent performance requirements in emerging applications are presented based on in-house technical developments and a literature study. The strategy of combining different detection principles, i.e. sensors based on electrochemical cells, semiconductors or field effects in combination with thermal conductivity sensor or catalytic combustion elements, in one new measuring system is reported. This extends the dynamic measuring range of the sensor while improving sensor reliability to achieve higher safety integrity through diverse redundancy. The application of new nanoscaled materials, nano wires, carbon tubes and graphene as well as the improvements in electronic components of fieldeffect, resistive-type and optical systems are evaluated in view of key operating parameters such as sensor response time, low energy consumption and low working temperature. T2 - ICHS2013 - 5th International conference on hydrogen safety CY - Brussels, Belgium DA - 09.09.2013 KW - Hydrogen KW - Safety KW - Sensors PY - 2013 SN - 978-2-9601366-0-9 SP - Paper 123, 1 EP - 14 AN - OPUS4-31079 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Boon-Brett, L. A1 - Palmisano, V. A1 - Bader, Mark Andreas T1 - Developments in gas sensor technology for hydrogen safety JF - International journal of hydrogen energy N2 - Gas sensors are applied for facilitating the safe use of hydrogen in, for example, fuel cell and hydrogen fuelled vehicles. New sensor developments, aimed at meeting the increasingly stringent performance requirements in emerging applications, are reviewed. The strategy of combining different detection principles, i.e. sensors based on electrochemical cells, semiconductors or field effects in combination with thermal conductivity sensing or catalytic combustion elements, in one new measuring system is reported. This extends the dynamic measuring range of the sensor while improving sensor reliability to achieve higher safety integrity through diverse redundancy. The application of new nanoscaled materials, nanowires, carbon tubes and graphene as well as the improvements in electronic components and optical elements are evaluated in view of key operating parameters such as measuring range, sensor response time and low working temperature. KW - Hydrogen sensor KW - Hydrogen safety PY - 2014 DO - https://doi.org/10.1016/j.ijhydene.2014.05.042 SN - 0360-3199 VL - 39 IS - 35 SP - 20474 EP - 20483 PB - Elsevier CY - Oxford AN - OPUS4-32379 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Boon-Brett, L. A1 - Black, G. A1 - Banach, Ulrich T1 - Hydrogen sensors - A review JF - Sensors and actuators B: Chemical N2 - Hydrogen sensors are of increasing importance in connection with the development and expanded use of hydrogen gas as an energy carrier and as a chemical reactant. There are an immense number of sensors reported in the literature for hydrogen detection and in this work these sensors are classified into eight different operating principles. Characteristic performance parameters of these sensor types, such as measuring range, sensitivity, selectivity and response time are reviewed and the latest technology developments are reported. Testing and validation of sensor performance are described in relation to standardisation and use in potentially explosive atmospheres so as to identify the requirements on hydrogen sensors for practical applications. KW - Hydrogen sensors KW - Hydrogen detection KW - Detection technologies KW - Technology developments PY - 2011 DO - https://doi.org/10.1016/j.snb.2011.04.070 SN - 0925-4005 SN - 1873-3077 VL - 157 IS - 2 SP - 329 EP - 352 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-24037 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Bauroth, F. A1 - Oertel, B. A1 - Svoboda, S. T1 - Aluminiumoxid-Sol/Gel-Schutzschichten auf Metallen JF - Ceramic Forum International : cfi PY - 1995 SN - 0173-9913 SN - 0196-6219 VL - 10 IS - 4 SP - 60 EP - 66 PB - Göller CY - Baden-Baden AN - OPUS4-5680 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hübert, Thomas A1 - Banach, Ulrich ED - Carcassi, M.N. T1 - Response time of hydrogen sensors T2 - ICHS2013 - 5th International conference on hydrogen safety (Proceedings) N2 - The efficiency of gas sensor application for facilitating the safe use of hydrogen depends to a considerable extent on the response time of the sensor to change in hydrogen concentration. The response and recovery times have been measured for five different hydrogen sensors, three commercially available and two promising prototypes which operate at room temperature. Experiments according to ISO 26142 show that most of the sensors surpass much for a concentration change from clean to hydrogen containing air the demands of the Standard for the response times t(90) and values of 2 to lös were estimated. For an opposite shift to clean air, the recovery times t(10) are from 7 to 70 s. Results of transient behaviour can be fitted with an exponential approach. It can be demonstrated that results on transient behaviour depend not only from investigation method, and the experimental conditions, like gas changing rate and concentration jump, as well as from operating Parameters of sensors. In comparison to commercial MOS and MIS-FET hydrogen sensors new sensor prototypes operating at room temperature possesses in particular longer recovery times. T2 - ICHS2013 - 5th International conference on hydrogen safety CY - Brussels, Belgium DA - 09.09.2013 KW - Hydrogen sensors KW - Time response PY - 2013 SN - 978-2-9601366-0-9 SP - Paper 124, 1 EP - 8 AN - OPUS4-31082 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas T1 - Humidity-Sensing Materials JF - MRS bulletin KW - Humidity-Sensing PY - 1999 DO - https://doi.org/10.1557/S0883769400052519 SN - 0883-7694 SN - 1938-1425 VL - 24 IS - 6 SP - 49 EP - 54 PB - Materials Research Society CY - Pittsburgh, Pa. AN - OPUS4-810 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gerlitzke, A.-K. A1 - Nörthemann, K. A1 - Lang, M. A1 - Milstrey, M. A1 - Kaufer, R. A1 - Woratz, M. A1 - Banach, Ulrich A1 - Hübert, Thomas A1 - Moritz, W. T1 - Long-term stability of the low energy hydrogen sensor T2 - IMCS 2012 - 14th International meeting on chemical sensors N2 - A silicon MIS-structure prepared with thin layers of the super-ionic conductor LaF3 and Pd is used to detect hydrogen. The sensor is able to detect hydrogen in a concentration range from below one ppm to the lower flammable limit in air which is 4 vol.-%. The chip operates at room temperature which results in an extremely low energy consumption compared to other hydrogen sensors. Only once per day a short heating pulse is necessary to reactivate the sensor chip. In cooperation with the BAM, a long-term experiment was carried out. The duration of the measurement was about three months, with a hydrogen exposure every two weeks. The sensor signal remained stable over the measured period. T2 - IMCS 2012 - 14th International meeting on chemical sensors CY - Nuremberg, Germany DA - 20.05.2012 KW - Hydrogen detection KW - Long-term measurement KW - MIS-structure KW - Low energy sensor PY - 2012 SN - 978-3-9813484-2-2 DO - https://doi.org/10.5162/IMCS2012/P2.5.1 SP - 1571 EP - 1574 PB - AMA Service GmbH CY - Wunstorf AN - OPUS4-26177 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Erwamati, F. U. A1 - Pratapa, S. A1 - Suasmoro, S. A1 - Hübert, Thomas A1 - Banach, Ulrich T1 - Preparation and structural study of Mg1−xZnxTiO3 ceramics and their dielectric properties from 1 Hz to 7.7 GHz JF - Journal of Materials Science: Materials in Electronics N2 - A series of Mg₁₋ₓZnₓTiO₃, x = 0–0.5 (MZT0–MZT0.5) ceramics was synthesised and characterised. The dielectric properties of the samples in the frequency range of 1 Hz – 7.7 GHz were explored using three different methods: a contacting electrode method, a parallel-plate method and a perturbed resonator method. The electrical properties in the space charge and dipolar polarisation frequency ranges are discussed in relation to the phase composition and microstructure data. Differences in the zinc Substitution divided the dielectrics into two groups, namely MZT0-MZT0.2 and MZT0.3–MZT0.5, each with different amount of a main Mg₁₋ₓZnₓTiO₃ solid solution phase and a secondary solid solution phase. Zinc substitution promoted the density of the ceramics, improved the purity of the main phase and increased the permittivity for frequencies up to 10⁸ Hz, but reduced the permittivity in the microwave range. In the MZT0.3–MZT0.5 samples, for frequencies less than 1 MHz the quality (Q x ƒ) factors were lower and log σ ₐ.c, the AC conductivity, was higher than for the MZT0–MZT0.2 samples. Above 10 MHz, the (Q x ƒ) factors and log σ ₐ.c of the two groups were similar. KW - Mg1-xZnxTiO3 KW - Space charge polarisation KW - Dipole polarisation KW - Microwave frequency KW - Dielectric properties PY - 2016 DO - https://doi.org/10.1007/s10854-016-4610-6 SN - 0957-4522 VL - 27 IS - 7 SP - 6637 EP - 6645 PB - Springer CY - Dordrecht, Netherlands AN - OPUS4-36466 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ermawati, F. U. A1 - Supardi, Z. A. I. A1 - Suasmoro, S. A1 - Hübert, Thomas T1 - Contribution of Relaxation Effect to the Permittivity of Mg1-xZnxTiO3 Ceramics JF - IOP Conference Series: Materials Science and Engineering N2 - This work reported the investigation on the effect of relaxation to the permittivity (epsilon' r ) characteristic of Mg1-x Zn x TiO3 ceramics for x = 0 – 0.5 (MZT0 – MZT0.5) measured from 1 Hz to 330 MHz. Within that frequency range, the relaxation effect that consists of the space charge (SC) and the dipolar (D) polarization mechanisms were identified. The contribution of the D relaxation in MZT0 – MZT0.2 systems extents overall from about 100 Hz to 330 MHz, while that in MZT0.3 – MZT0.5 systems is from 50 kHz to 330 MHz. The remaining frequencies, i.e. from 1 to 90 Hz for MZT0 – MZT0.2 and from 1 Hz to 50 kHz for MZT0.3 – MZT0.5, are attributed to the SC relaxation. The D polarization mechanism provides constant epsilon' r values which vary from (15.4 – 17.0) ± 0.3 throughout the samples. Contribution of the SC polarization mechanism to the characteristic is supported by the simultaneous presence of different content and level of resistivity of the secondary phase of (Mg1-αZnα)2TiO4 in MZT0 – MZT0.2 systems and of (Zn1-αMgα)2TiO4 in MZT0.3 – MZT0.5, along with the presence of the main Mg1-x Zn x TiO3 phase, as a result of the variation of zinc content in the systems. T2 - The 5th International Conference on Advanced Materials Sciences and Technology (ICAMST 2017) CY - Makassar, Indonesia DA - 19.09.2017 KW - Dielectric ceramic KW - dipolar polarization KW - Mg1-xZnxTiO3 KW - permittivity KW - space charge polarization PY - 2018 DO - https://doi.org/10.1088/1757-899X/367/1/012003 SN - 1757-8981 VL - 367 SP - 1 EP - 6 PB - IOP Publishing Ltd AN - OPUS4-45618 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Detjens, Marc A1 - Hübert, Thomas A1 - Tiebe, Carlo A1 - Banach, Ulrich T1 - Temperature influence on coulometric trace humidity measurement T2 - Proceedings of the IEEE Sensors 2017 N2 - Planar coulometric sensors were tested in humidified synthetic air at various gas temperatures. Generated frost point temperature in the gas ranged from -30 °C to -60 °C and were measured by coulometric sensors and in addition by a calibrated dew point hygrometer. The gas temperatures, which were measured by a calibrated Pt100 sensor, were set to -20 °C, 0 °C, 23 °C, 40 °C, 50 °C, and 60 °C during the experiments. Empiric nonlinear functions were calculated between the generated humidity and the sensor signals. In comparison to the measured signals at 23 °C, the sensor signals were lower at the other gas temperatures. The measurements at 60 °C showed indistinct results due to a great signal noise. The response behavior of the sensors was similar at 23 °C, 40 °C and 50 °C. In contrast to that, the sensors reacted slowly at a gas temperature of -20 °C and 0 °C. In summary, with coulometric sensors it was possible to measure continuously trace humidity with an expanded uncertainty below 2 K. T2 - IEEE Sensors 2017 CY - Glasgow, Scotland, UK DA - 30.10.2017 KW - Response behavior KW - Coulometric sensors KW - Trace humidity measurement KW - Temperature influence KW - Chemical reaction PY - 2017 SN - 978-1-5386-4056-2 SP - 1308 EP - 1310 PB - IEEE CY - Piscataway, NJ, USA AN - OPUS4-43241 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Detjens, Marc A1 - Hübert, Thomas A1 - Tiebe, Carlo A1 - Banach, Ulrich T1 - Coulometric trace humidity measurement in technical gases JF - Review of scientific instruments N2 - Trace humidity was measured by using miniaturized planar coulometric sensors in technical gases such as hydrogen, nitrogen, helium, nitrous oxide, and synthetic air. Frost point temperatures tf in the gases ranged from −60 °C to −30 °C, which is equivalent to a vapour mole fraction xv from 10 μmol mol−1 to 376 μmol mol−1. In addition, the generated humidity was determined by using a precision dew point hygrometer as reference. Nonlinear calibration functions were calculated that correlated electric current (sensor signal) and reference humidity. Parameters of functions were tested with one-way analysis of variances (ANOVA) to prove if all used sensors had a similar behavior in the same gas during experiments. Results of ANOVA confirmed that averaged functions can be applied for trace humidity measurement in nitrogen, helium, nitrous oxide, and synthetic air. The calculated functions were negligibly different for nitrogen, helium, and synthetic air. In humidified nitrous oxide, a minor change of parameters was observed due to lower electrical currents. In total contrast to that, the measured sensor signals were significantly higher in humidified hydrogen and each sensor required its own calibration function. The reason was a recombination effect that favoured multiple measurements of water molecules. Nevertheless, it was possible to measure continuously trace humidity in all tested gases by using coulometric sensors with an expanded uncertainty below 2 K (k = 2). KW - ANOVA KW - Trace humdity measurement KW - Coulometric sensors KW - Chemical sensors KW - Measurement uncertainty PY - 2018 DO - https://doi.org/10.1063/1.5008463 SN - 0034-6748 SN - 1089-7623 VL - 89 IS - 8 SP - 085004, 1 EP - 8 PB - American Institute of Physics (AIP) CY - Maryland (USA) AN - OPUS4-45956 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Boon-Brett, L. A1 - Bousek, J. A1 - Black, G. A1 - Moretto, P. A1 - Castello, P. A1 - Hübert, Thomas A1 - Banach, Ulrich T1 - Identifiying performance gaps in hydrogen safety sensor technology for automotive and stationary applications JF - International journal of hydrogen energy N2 - A market survey has been performed of commercially available hydrogen safety sensors, resulting in a total sample size of 53 sensors from 21 manufacturers. The technical specifications, as provided by the manufacturer, have been collated and are displayed herein as a function of sensor working principle. These specifications comprise measuring range, response and recovery times, ambient temperature, pressure and relative humidity, power consumption and lifetime. These are then compared against known performance targets for both automotive and stationary applications in order to establish in how far current technology satisfies current requirements of sensor end users. Gaps in the performance of hydrogen sensing technologies are thus identified and areas recommended for future research and development. KW - Hydrogen sensor KW - Hydrogen detection KW - Safety KW - Sensor performance testing KW - Performance specifications KW - Performance targets PY - 2010 DO - https://doi.org/10.1016/j.ijhydene.2009.10.064 SN - 0360-3199 VL - 35 IS - 1 SP - 373 EP - 384 PB - Elsevier CY - Oxford AN - OPUS4-22893 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Beck, Uwe A1 - Hübert, Thomas A1 - Kleinke, Helga T1 - Amorphous and nanocrystalline SrTiO3 thin films JF - Journal of non-crystalline solids KW - Schicht, dünn KW - Schicht, amorph KW - Schicht, nanokristallin KW - SrTiO3 PY - 1996 SN - 0022-3093 VL - 196 SP - 150 EP - 154 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-652 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Banach, Ulrich A1 - Tiebe, Carlo A1 - Hübert, Thomas T1 - Multigas sensors for the quality control of spice mixtures JF - Food control N2 - Spices have an important impact on daily aliment. Changes of their quality resulting in far reaching consequences in different foodstuffs and imply financial losing and even health hazard. In this study it is demonstrated that application of two different portable multi gas sensors (electronic nose and ion mobility spectrometer) supported by multivariate data analysis can contribute to ensure quality control of spice mixtures and to find out product adulteration. Headspace above spice mixtures for sausages and saveloy and product counterfeitings was investigated by a metal oxide based electronic nose (e-nose of KAMINA-type). Linear discriminant analysis (LDA) of sensor resistivity data was performed for differentiation. Simultaneously an ion mobility spectrometer (IMS) was coupled to the emission chamber for detection of gaseous components above spice mixtures. The measured spectra show differences between the two spice mixtures and were discussed using a principal component analysis (PCA). The two multigas sensors permit discrimination between the types of spice mixtures and can indicate product adulteration. Additionally, a headspace gas analysis by gas chromatography was performed to identify the main volatile components and to prove the chemical basis for the observed differences of the multi gas sensors. KW - Spice mixtures KW - Product adulteration KW - Electronic nose KW - Ion mobility spectrometer KW - Gas chromatography KW - Multivariate data analysis PY - 2012 DO - https://doi.org/10.1016/j.foodcont.2012.01.015 SN - 0956-7135 VL - 26 IS - 1 SP - 23 EP - 27 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-25402 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -