Discovering structure–property correlations: General discussion

This article is a discussion of the paper "Web-BO: Towards increased accessibility of Bayesian optimisation (BO) for chemistry" by Austin M. Mroz, Piotr N. Toka, Ehecatl Antonio del Río Chanona and Kim E. Jelfs (Faraday discussions, 2025, 256, 221-234)

Influence of hydroxypropylation of starch on rheological properties of cement paste modified by superplasticizers

Starch is often used as a viscosity modifying agent (VMA) in self-compacting concrete (SCC) and highly flowable concrete. In this paper, starches possessing different degrees of hydroxypropyl substitution (DS) were used to study the shear rheological properties and hydration kinetics of cement paste in the presence of and without polycarboxylate superplasticizer (PCE). The starch with the highest DS increases the yield stress and the plastic viscosity stronger than others. Regardless of the dosage and DS of starch the structural build-up is not affected specifically by the starch during the induction period. During the acceleration period starches reduce the structural build-up, but with the highest DS this effect was less prominent than for the other modifications. In the presence of PCE the addition of starch notably increases the yield stress, whereas the influence on the plastic viscosity is limited. Yet, the combined application of PCE and starch allows to control rheological properties and maintain the structural build-up rate

Accuracy assessment of a micro-Raman spectroscopy method for small microplastic particles in infant milk formula

The presence of microplastics (MPs) in the food chain is increasingly documented, raising concerns over potential risks to human health. Despite growing efforts, standardized methods for MPs detection in food matrices remain limited. This study presents an interlaboratory comparison (ILC) aimed at assessing the accuracy and comparability of an analytical approach for the identification and quantification of small MPs (5–100 μm) in infant milk powder using μ-Raman spectroscopy and a representative polyethylene terephthalate (PET) reference material (RM). The RM, formulated as water-soluble tablets, was designed to replicate the morphology, size distribution, and polymer composition of environmentally relevant MPs, and was previously assessed for homogeneity and stability for mass fraction and particle numbers. The approach was assessed using two PET RM batches with different MPs particle numbers (high load batch: 1759 ± 141 MPs; low load batch: 160 ± 22 MPs), subjected to an enzymatic–chemical digestion, followed by μ-Raman analysis performed independently in two laboratories with different instruments and operators. Results are reported as absolute particle counts per analyzed sample and demonstrated excellent recovery across all size classes, including the smallest particles (down to 5 μm), with recovery rates ranging from 82 % to 88 %, in good agreement with the RM reference values. The analytical approach proved to be robust, reproducible, and suitable for low-level MPs quantification in complex food matrices, supporting ongoing efforts toward method harmonization and standardization for reliable MPs monitoring in the food sector

Development, Validation and Application of an Accelerated Weathering Protocol for Assessing Bisphenol A Release from Polycarbonate Materials into the environment

Bisphenol A (BPA) is under continuous regulatory scrutiny and listed as substance of very high concern (SVHC). Particular concern is related to its frequent detection in surface waters, despite being readily biodegradable. Several studies have been conducted to investigate sources and pathways of BPA in the environment, concluding that its main use as monomer in polycarbonate (PC) contributes only marginally to environmental BPA releases over its life cycle. To better understand the actual releases of BPA from PC under environmental conditions, a newly developed methodology (Federal Institute for Materials Research and Testing, BAM) was applied, which comprises a novel accelerated weathering protocol for polycarbonate (PC) materials, combined with an advanced analytical setup allowing for improved detection of BPA at trace level concentrations. The weathering protocol achieves a 13.6-fold acceleration compared to Central European outdoor conditions and simulates environmental stressors (global radiation, rain, temperature variations) in a laboratory weathering chamber, with simultaneous BPA release measurements using an organic isotope dilution calibration LC-MS/MS approach. Validation was performed in parallel outdoor exposure tests, by using haze and yellowness index measurements as reference parameters. PC sample types representative of major polycarbonate applications were examined: Samples with different levels of UV-protection as used in transparent sheets used outdoor in construction or housings in Electro- and Electronic applications as well as samples with a protective coating as used in automotive applications (headlamps, glazing and construction). Results demonstrated consistently low total BPA releases of around 0.3 mg m⁻² for samples with exposed PC surfaces, while releases from coated samples were significantly reduced by around two orders of magnitude. In all cases examined, the BPA release ceased to zero after a period of four to six weeks, equivalent to approximately 1 to 1.5 years of outdoor exposure. This suggests that potential BPA releases diminish to virtually zero after that timespan. While the newly developed test method is not suitable for routine laboratory implementation, it provides crucial quantitative data on BPA release from PC materials during accelerated environmental weathering

Quantitative Analysis of Gadolinium Deposits in Liver Tissue of Patients After Single or Multiple Gadolinium-based Contrast Agent Application

Gadolinium-based contrast agents (GBCAs) are widely used in magnetic resonance imaging. Concerns exist regarding gadolinium deposition and its potential histopathologic tissue alterations, especially after repeated administrations of linear, less stable GBCAs. This study aimed to quantify gadolinium mass fractions in liver specimens of subjects exposed to GBCAs in correlation with histopathologic features. In this study, mass fractions of gadolinium in human liver specimens from 25 subjects who underwent liver tumor resection surgery and had received GBCA (1 to 9 times over 4 years), were quantitatively analyzed using inductively coupled plasma–mass spectrometry (ICP-MS). Histomorphology was assessed based on the nonalcoholic fatty liver disease activity score (NAS). Our results suggest that after intravenous administration of GBCA, a small fraction of gadolinium is retained in the liver over a time period of at least several weeks. A relationship was observed between Gadolinium retention and the number of GBCA administrations, but not with the cumulative dose and the degree of fatty liver disease

A gradient-enhanced JH2 model for dynamic simulations of concrete structures

Concrete structures subjected to impact and blast loads experience complex failure mechanisms that are challenging to simulate accurately. Local constitutive models formulated using plasticity with softening are commonly used for this purpose. The softening behavior is typically represented by a scalar damage field, which scales the yield surface to capture the degradation of material strength. However, these local models often exhibit meshdependent results with localization of damage into a few cells. To address this limitation, this study combines a modified version of the Johnson-Holmquist (JH2) model with a gradientenhancement approach. The introduction of an inertia term into the additional PDE for the determination of the nonlocal equivalent plastic strain transforms it into a hyperbolic equation, enabling an efficient solution with an explicit dynamics solver. A one-dimensional benchmark simulation demonstrates the differences between the local and gradient-enhanced models. The local model shows severe damage localization and diminishing plastic energy dissipation with finer meshes. In contrast, the gradient-enhanced model distributes damage over multiple elements, though the plastic strain still localizes within a single element. Introducing strain hardening with respect to the local equivalent plastic strain resolves this issue, ensuring convergence of plastic energy and non-localizing plastic strain. These findings are extended and validated with two-dimensional simulations, showcasing the model’s practical relevance. Additionally, the impact of the added inertia term is analyzed in the context of dynamic strength enhancement, a critical characteristic of concrete under high strain rates. The proposed gradient-enhancement approach demonstrates improved numerical stability and mesh-independence compared to local models, making it a suitable tool for simulating concrete behavior under extreme loading conditions

Human-in-the-Loop: Decision Making in AI-Supported Non-Destructive Testing

The increasing integration of automation and artificial intelligence (AI) in non-destructive testing (NDT) is not only changing the inspection processes themselves, but also the way decisions are made. While technical systems can reduce error-proneness and support data processing, the ultimate responsibility remains with the human. This paper examines the role of intuition in decision-making and analyses typical errors of judgment using prospect theory and insights from cognitive psychology. It also shows how well-informed decisions can be supported in AI-supported NDT processes - through training, explainable systems, user-centred design, suitable metrics, and a targeted distribution of tasks between people and technology. Rather than replacing human intuition, AI systems should be designed to complement it. To engage effectively with such systems, inspectors require not only technical expertise, but also competencies in risk assessment, probabilistic reasoning, and critical reflection on both their own judgments and the outputs provided by AI

Pore solution compositions and redox potentials of ground granulated blast furnace slag-containing cement pastes

The pore solutions of hardened ground granulated blast furnace slag (GGBFS)-containing cements differ from the pore solutions of other cements with effects on reinforcement corrosion, application of electrochemical methods and immobilisation of radioactive waste. In the present study, the pore solutions of seven different GGBFS-containing cements (alkali-activated slag, alkali-activated slag/fly ash blends, hybrid alkaline cement (HAC), CEM III/C and CEM III/B) were extracted and their elemental and sulfate concentration, pH, redox potential and conductivity were determined; a Portland cement (CEM I) pore solution was analysed analogously. The silicon and aluminium concentrations of the alkali-activated cements increased with fly ash fraction, reaching values up to 5 mM and 10 mM, respectively, and thus were considerably higher than those of the standard cements. The redox potentials of the pore solutions of the GGBFS-containing cements were in the range from −100 mV to –500 mV vs Ag/AgCl, that is considerably lower than that of the Portland cement (8–20 mV vs Ag/AgCl), with the value depending on the GGBFS fraction and whether the cements were alkali-activated or not. These results indicate that the effects of reduced sulfur species from GGBFS in cements are more pronounced in alkali-activated materials, including HAC, and increase with GGBFS fraction

Thermal Transport in Ag8TS6 (T= Si, Ge, Sn) Argyrodites: An Integrated Experimental, Quantum-Chemical, and Computational Modelling Study. DFT-part

This repository contains computational data supporting the manuscript titled *“Thermal Transport in Ag8TS6 (T= Si, Ge, Sn) Argyrodites: An Integrated Experimental, Quantum-Chemical, and Computational Modelling Study”* It includes raw data for vibrational properties, elastic properties and Bonding analysis

Reduction of residual stress by narrowing the repair groove: Optimising repair welding with modern welding processes for high strength offshore steels

The ongoing German energy transition will require offshore wind turbines with outputs of >10 MW in the future. Turbines with these high outputs must be located far from the coast, with up to 50 m large subsea jacket structures and tall towers. These structures are increasingly fabricated of high-strength steels with a yield strength up to 500 MPa and wall thicknesses of up to 120 mm. During production, weld defects identified through non-destructive testing (NDT) must be locally repaired by gouging and rewelding. Standards and guidelines lack sufficient concepts and information regarding such repair procedures. To address this gap, BAM launched the FOSTA project P1629 (IGF 01IF22746N) to explore stress-optimised repair concepts, specifically local gouging and welding, for high-strength thick plate joints made from offshore-grade steels with yield strengths between 355 MPa and 460 MPa, including matching weld metals. This research aims to develop a stress-optimised repair concept for thick plate joints, utilising controlled high-performance GMAW techniques and narrow gouging grooves. Both thermal and mechanical gouging methods are applied, enabling adjustments to the groove geometry. Modern welding processes offer deep root penetration and concentrated energy input, making them suitable for narrow seams. The intended reduction in residual stress results from the decreased weld metal volume, due to modified groove shapes and the lower heat input per layer achieved through controlled arc processes. Experimental investigations examine how process parameters, material properties, and design factors interact to influence the development of welding-induced stresses. The project concludes with practical recommendations for guidelines tailored to steel-processing SMEs