Optically detected X-ray absorption spectroscopy measurements as a means to monitor corrosion layers on copper

XANES and EXAFS information is conventionally measured in transmission through the energy-dependent absorption of X-rays or by observing X-ray fluorescence, but secondary fluorescence processes, such as the emission of electrons and optical photons (e.g., 200-1000 nm), can also be used as a carrier of the XAS signatures, providing complementary information such as improved surface specificity. Where the near-visible photons have a shorter range in a material, the data will be more surface specific. Moreover, optical radiation may escape more readily than X-rays through liquid in an environmental cell. Here, we describe a first test of optically detected X-ray absorption spectroscopy (ODXAS) for monitoring electrochemical treatments on copper-based alloys, for example, heritage metals. Artificially made corrosion products deposited on a copper substrate were analyzed in air and in a 1% (w/v) sodium sesquicarbonate solution to simulate typical conservation methods for copper-based objects recovered from marine environments. The measurements were made on stations 7.1 and 9.2 MF (SRS Daresbury, UK) using the mobile luminescence end station (MoLES), supplemented by XAS measurements taken on DUBBLE (BM26 A) at the ESRF. The ODXAS spectra usually contain fine structure similar to that of XAS spectra measured in X-ray fluorescence. Importantly, for the compounds examined, the ODXAS is significantly more surface specific, and > 98% characteristic of thin surface layers of 0.5-1.5-mu m thickness in cases where X-ray measurements are dominated by the substrate. However, EXAFS and XANES from broadband optical measurements are superimposed on a high background due to other optical emission modes. This produces statistical fluctuations up to double what would be expected from normal counting statistics because the data retain the absolute statistical fluctuation in the original raw count, while losing up to 70% of their magnitude when background is removed. The problem may be solved in future through optical filtering to isolate the information-containing band, combined with the use of higher input X-ray fluxes available on third-generation light sources

How does iron interact with sporopollenin exine capsules? An X-ray absorption study including microfocus XANES and XRF imaging

Sporopollenin exine capsules (SECs) derived from plant spores and pollen grains have been proposed as adsorption, remediation and drug delivery agents. Despite many studies there is scant structural data available. This X-ray absorption investigation represents the first direct structural data on the interaction of metals with SECs and allows elucidation of their structure–property relationships. Fe K-edge XANES and EXAFS data have shown that the iron local environment in SECs (derived from Lycopodium clavatum) reacted with aqueous ferric chloride solutions is similar to that of ferrihydrite (FeOOH) and by implication ferritin. Fe Kα XRF micro-focus experiments show that there is a poor correlation between the iron distribution and the underlying SEC structure indicating that the SEC is coated in the FeOOH material. In contrast, the Fe Kα XRF micro-focus experiments on SECs reacted with aqueous ferrous chloride solutions show that there is a very high correlation between the iron distribution and the SEC structure, indicating a much more specific form of interaction of the iron with the SEC surface functional groups. Fe K-edge XANES and EXAFS data show that the FeII can be easily oxidised to give a structure similar to, but not identical to that in the FeIII case, and that even if anaerobic conditions are used there is still partial oxidation to FeIII

Measurement of feeder performance during coal discharge from an underroof seam using machine vision

The technology for extracting and discharging coal from an underroof seam uses the so-called gravitational extraction method in which coal is extracted and discharged from under the roof by gravity. Here, coal can be discharged onto the main conveyor (face conveyor, located in the supported area), central conveyor (rear conveyor in Western literature), and tail conveyor (discharge conveyor, located in the unsupported area). The most common facilities used currently are longwall sets of equipment providing discharge onto tail conveyors. The purpose of this study is to measure the performance of a motorised plate feeder supplying coal from the outlet port of a roof support to a conveyor during the extraction of thick seams with discharge onto the face conveyor. To achieve the goal, it is proposed to measure the coal volume using machine vision. Methods for calculating a unit volume in a measuring section using a three-dimensional model were investigated. Laboratory studies were carried out to estimate the relative errors of the methods. The research allowed properly defining: a method for collecting data to calculate the unit volume of coal; a method for calculating the unit volume in the measuring section; a method for calculating the feeder performance using machine vision, and approaches for physically simplifying the video scene examined by machine vision. A relative error of less than 10 % with the existing measurement accuracy for constructing a coal layer surface height map indicates the sufficiency of the proposed calculation method for engineering use. The developed mathematical apparatus for calculating the unit volume of coal at the measuring section and measuring the feeder performance allows creating algorithmic software using the elementary mathematical functions of addition, subtraction, multiplication, and division. This aspect is important because it lower sights for the software development environment, and therefore expands the range of hardware suitable for calculating the feeder performance

Value chain stress resilience and behavioral strategies of companies in Russian coal industry

Under the current conditions, the Russian coal industry is under unprecedented external pressure: it is both the imposed sanctions and the need to meet strict environmental requirements that inevitably lead to the closure of part of the enterprises, the collapse of value chains (VCs) in the coal and related industries. As a result, a complex restructuring of the industry is required. To carry it out successfully, a reliable criterion is needed to assess the prospects for the long-term development of both individual companies and VCs as a whole. From the authors’ point of view, the degree of stress resilience of VCs is the criterion needed. The article deals with the evaluation of the long-term development prospects of the coal industry based on the established stress resilience of VCs and the related strategies of coal companies’ behavior. The authors proposed an algorithm for assessing the stress resilience of VCs in the coal industry: a description of the aspects and typology of VCs in the Russian coal industry; an assessment of their current stress resilience; a description of the survival strategy of the companies included in the VCs; an assessment of the prospects for sustaining VCs under sanctions. Subsequently, this article presents theresults of the stress resilience assessment of 169 coal companies operating in 110 different VCs between 2010 and 2021. The authors created a typology of VCs in the coal industry, which makes it possible to identify three basic types of VCs in the domestic coal industry: two integrated – the captive market and the hierarchical market – and one non-integrated market. Analysis of companies operating from 2010 to 2021 showed that 90 out of 169 businesses (53%) operated as integrated companies (hierarchical and captive VCs), the remaining 79 were classified as market ones. For each type we measured overall stress resilience (βrescom), indicating the VC degree of recovery from shocks; robustness (βres), the VC ability to withstand (swallow) shocks; adaptability (βrec), the VC flexibility CDS and the ability to recover quickly after a shock. The analysis conducted by the authors showed that the stress resilience of key segments of the coal industry is low and tends to decrease and will only decrease in the long run. The research also found that systemically important companies are in the most difficult situation. They belong to the hierarchical VCs, especially the energyand coal companies, which are mainly focused on foreign markets. Their cooperative survival strategy does not even maintain the current level of stress resilience. Market and relational VCs are in a more favorable position. As a result, the authors conclude that part of the coal companies will inevitably close and for the other part a profound restructuring will be necessary, while the current survival strategies of the companies will not allow to solve this problem by themselves and an active participation of the state will be necessary

Energy Resolution Performance of the CMS Electromagnetic Calorimeter

The energy resolution performance of the CMS lead tungstate crystal electromagnetic calorimeter is presented. Measurements were made with an electron beam using a fully equipped supermodule of the calorimeter barrel. Results are given both for electrons incident on the centre of crystals and for electrons distributed uniformly over the calorimeter surface. The electron energy is reconstructed in matrices of 3 times 3 or 5 times 5 crystals centred on the crystal containing the maximum energy. Corrections for variations in the shower containment are applied in the case of uniform incidence. The resolution measured is consistent with the design goals