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Organisationseinheit der BAM
This specification describes how corrosion monitoring is used to check the condition of reinforced and prestressed concrete members. In this specification, the term "corrosion monitoring" covers all methods in which it is possible to continuously track corrosion-relevant variables in the area of stationary, built-in sensors. This specification does not cover other possible methods, such as potential field measurements, involving the use of mobile, portable sensors that are placed temporarily on the membersurface to take measurements.
The development of earth-abundant catalysts for selective electrochemical CO2 conversion is a central challenge. Cu-Sn bimetallic catalysts can yield selective CO2 reduction toward either CO or formate. This study presents oxide-derived Cu-Sn catalysts tunable for either product and seeks to understand the synergetic effects between Cu and Sn causing these selectivity trends. The materials undergo significant transformations under CO2 reduction conditions, and their dynamic bulk and surface structures are revealed by correlating observations from multiple methods—X-ray absorption spectroscopy for in situ study, and quasi in situ X-ray photoelectron spectroscopy for surface sensitivity. For both types of catalysts, Cu transforms to metallic Cu0 under reaction conditions. However, the Sn speciation and content differ significantly between the catalyst types: the CO-selective catalysts exhibit a surface Sn content of 13 at. % predominantly present as oxidized Sn, while the formate-selective catalysts display an Sn content of ≈70 at. % consisting of both metallic Sn0 and Sn oxide species. Density functional theory simulations suggest that Snδ+ sites weaken CO adsorption, thereby enhancing CO selectivity, while Sn0 sites hinder H adsorption and promote formate production. This study reveals the complex dependence of catalyst structure, composition, and speciation with electrochemical bias in bimetallic Cu catalysts.
Stable isotope dilution assay for the accurate determination of mycotoxins in maize by UHPLC-MS/MS
(2012)
A fast, easy-to-handle and cost-effective analytical
method for 11 mycotoxins currently regulated in maize and
other cereal-based food products in Europe was developed
and validated for maize. The method is based on two extraction
steps using different acidified acetonitrilewater mixtures.
Separation is achieved using ultrahigh-performance
liquid chromatography (UHPLC) by a linear watermethanol
gradient. After electrospray ionisation, tandem mass spectrometric
detection is performed in dynamic multiple reaction
monitoring mode. Since accurate mass spectrometric quantification
is hampered by matrix effects, uniformly [13C]-
labelled mycotoxins for each of the 11 compounds were added
to the sample extracts prior to UHPLC-MS/MS analysis.
Method performance parameters were obtained by spiking
blank maize samples with mycotoxins before as well as after
extraction on six levels in triplicates. The twofold extraction
led to total recoveries of the extraction steps between 97%and
111% for all target analytes, including fumonisins. The [13C]-
labelled internal standards efficiently compensated all matrix
effects in electrospray ionisation, leading to apparent recoveries
between 88% and 105% with reasonable additional costs.
The relative standard deviations of the whole method were
between 4% and 11% for all analytes. The trueness of the
method was verified by the measurement of several maize test
materials with well-characterized concentrations. In conclusion,
the developed method is capable of determining all
regulated mycotoxins in maize and presuming similar
matrix effects and extraction recovery also in other cerealbased
foods.
Corrosion monitoring of reinforced concrete structures:The DGZfP specification B12 Collaboration
(2023)
Corrosion monitoring of reinforced or prestressed concrete structures has becomeincreasingly important in recent years. Areas of application include componentsthat are no longer accessible after completion or where potential fieldmeasurements cannot be carried out due to existing coatings. Corrosion monitoringcan also be used to monitor the progress of corrosion in corroding systems, e.g. toprove the success of repair measures according to repair principle 8 in accordancewith EN 1504‐9 or repair method 8.3 in accordance with the DIBt repair guideline.It also could be used to prove the functionality of cathodic corrosion protectionsystems in accordance with ISO 12696. Despite the increasing importance ofcorrosion monitoring, no guidelines orrecommendations existed until 2018. Thisgap was closed by the English version of specification B12,“Corrosion Monitoringof Reinforced and Prestressed Concrete Structures,”of the German Society for Non‐Destructive Testing, which was published in 2021. This article introducesspecification B12 by explaining the basicmeasurement principles and illustratingthe potential of corrosion monitoring in new and existing buildings.