Multi-scale modelling techniques are commonly used to characterize heterogeneous rock samples. However, open challenges limit the efficiency of these models. A significant issue is the tradeoff between resolution and field of view (FoV) during imaging. Capturing an image of a heterogeneous rock sample that includes pores of different scales with a large FoV is impossible. Various novel approaches have attempted to solve this problem, but they have inherent limitations such as unrealistic results and high computational costs. In this study, we propose a novel method to generate 3D multiscale images of two heterogeneous rock samples: Berea sandstone and Edward Brown carbonate. We scanned both samples at low and high (HR) resolutions using X-ray microtomography. Our approach involves distinct reconstruction of resolved and unresolved porosity in rock images at lower resolutions. We divide the unresolved porosity into smaller sections, called unresolved templates, using the watershed algorithm to reduce memory allocation. The cross-correlation based simulation approach then finds a suitable replacement template from the HR images, which contain a significant number of micro-pores, using a modified overlap region selection procedure in 3D. We compare the geometrical and petrophysical properties of the reconstructed multi-scale images with those of the HR rock images. The results show good agreement with the HR image properties computed from the direct numerical simulation approach. Additionally, our thus validated method is two to four times faster in constructing multi-scale images.

Single particle inductively coupled plasma mass spectrometry (spICP-MS) is a well-established technique to characterize the size, particle number concentration (PNC), and elemental composition of engineered nanoparticles (NPs) and colloids in aqueous suspensions. However, a method capable of directly analyzing water-sensitive or highly reactive NPs in alcoholic suspension has not been reported yet. Here, we present a novel spICP-MS method for characterizing the main cement hydration product, i.e., calcium-silicate-hydrate (C-S-H) NPs, in ethanolic suspensions, responsible for cement strength. The method viability was tested on a wide range of NP compositions and sizes (i.e., from Au, SiO2, and Fe3O4 NP certified reference materials (CRMs) to synthetic C-S-H phases with known Ca/Si ratios and industrial cement hardening accelerators, X-Seed 100/500). Method validation includes comparisons to nanoparticle tracking analysis (NTA) and transmission/scanning electron microscopy (TEM/SEM). Results show that size distributions from spICP-MS were in good agreement with TEM and NTA for CRMs ≥ 51 nm and the synthetic C-S-H phases. The X-Seed samples showed significant differences in NP sizes depending on the elemental composition, i.e. CaO and SiO2 NPs were bigger than Al2O3 NPs. PNC via spICP-MS was successfully validated with an accuracy of 1 order of magnitude for CRMs and C-S-H phases. The spICP-MS Ca/Si ratios matched known ratios from synthetic C-S-H phases (0.6, 0.8, and 1.0). Overall, our method is applicable for the direct and element-specific quantification of fast nucleation and/or mineral formation processes characterizing NPs (ca. 50–1000 nm) in alcoholic suspensions.

Pseudomonas alloputida KT2440 is a ubiquitous, soil-dwelling bacterium that metabolizes recalcitrant and volatile carbon sources. The latter are utilized by two redundant, Ca- and lanthanide (Ln)-dependent, pyrroloquinoline quinone-dependent alcohol dehydrogenases (PQQ ADH), PedE and PedH, whose expression is regulated by Ln availability. P. alloputida KT2440 is the best-studied, non-methylotroph in the context of Ln-utilization. We report the most comprehensive differential gene expression analysis, to date, for any Ln-utilizing microbe. Combined with microfluidic cultivation and single-cell elemental analysis, we studied the impact of light and heavy Ln when growing P. alloputida KT2440 with 2-phenylethanol as the carbon and energy source. Light Ln (La, Ce, Nd) and a mixture of light and heavy Ln (La, Ce, Nd, Dy, Ho, Er, Yb) had a positive effect on growth, while supplementation with heavy Ln (Dy, Ho, Er, Yb) exerted fitness costs. These were likely a consequence of mismetallation and oxidative stress. Gene expression analysis showed that the Ln sensing and signaling machinery, the two-component system PedS2R2 and PedH, responds differently to (non-)utilizable Ln. We broadened the understanding of the Ln switch in P. alloputida KT2440 and could show that it operates as a dimmer switch, modulating the pool of PQQ ADH dependent on Ln availability. Determined quantities of cell-associated Ln suggest a role for Ln beyond alcohol oxidation. The usability of Ln governs the response of P. alloputida KT2440 to different Ln elements. Importance The Ln switch, the inverse regulation of Ca- and Ln-dependent PQQ ADH dependent on Ln availability in organisms featuring both, is central to our understanding of Ln utilization. Although the preference of bacteria for light Ln is well known, the effect of different Ln, light and heavy, on growth and gene expression has rarely been studied. We provide evidence for a dimmer switch-like regulation of Ca- and Ln-dependent PQQ ADH in P. alloputida KT2440, and could show that the response to (non-)utilizable Ln differs depending on the element. Ln commonly co-occur in nature. Our findings underline that Ln-utilizing microbes must be able to discriminate between Ln to use them effectively. Considering the prevalence of Ln-dependent proteins in many microbial taxa, more work addressing Ln sensing and signaling is needed. Ln availability likely necessitates different adaptations regarding Ln utilization.

This book provides a comprehensive overview of Chinese activities to establish a new underground laboratory for repository research.

Streptomyces are important soil bacteria used for bioremediation of metal-contaminated soils, however, it is still unknown how metal-selective Streptomyces are and which mechanisms are involved during their capture. In this work, we exposed S. coelicolor spores to environmentally relevant concentrations (0.1, 1, 10, 100 μM) of Ce, U and Cd in solid medium for one week to investigate the uptake behaviour of hyphae in the newly formed spores. Additionally, metal adsorption onto the spores was explored by incubating inactive, ungerminated spores for one day in aqueous metal solution. The spore-washing treatment was key to distinguishing between strongly spore-associated (e.g. incorporation; Tris-EDTA buffer) and weakly spore-associated metals (Tris buffer alone minus Tris-EDTA). Single cell (sc) ICP-MS was used to quantify metal-associated content in individual spores. Our results revealed element-specific adsorption onto inactive spores showing that out of the total metal exposure, both strongly (Ce: 58%; U: 54%; Cd: 28%) and weakly (Ce: 12%; U: 1%; Cd: 18%) adsorbed metals occur. However, scICP-MS showed that from metal-amended solid medium, only Ce and U were strongly spore-associated (averages 0.040 and 0.062 fg spore−1 for 10 μM exposures, respectively) while Cd was below the limit of detection (<0.006 fg spore−1). We propose that hyphae only metabolically interact with Ce in a controlled manner but uncontrolled with U, as 66–73% Ce and only 2–4% U were inherited from adsorbed content. We conclude that Streptomyces spore-metal interaction starts with a relevant adsorption step of Ce, U and Cd as presented for aqueous conditions. If spores start to germinate, hyphae are capable of effectively encapsulating Ce and U, but not Cd. This study brings light into the still unknown field of metal interactions with Streptomyces and applied understanding for more efficient and metal-specific use of Streptomyces in bioremediation of metal-polluted soils.