Atomic force microscopy (AFM) studies of cementitious materials are limited, mainly due to the lack of appropriate sample preparation techniques. In porous autoclaved aerated concrete (AAC), calcium ...silicate hydrate (C–S–H) is produced in its crystalline form, tobermorite. The crystals are lath-like with a length of several micrometers. In this work, we demonstrate the application of nanomanipulators to separate an individual tobermorite crystal from the bulk AAC for subsequent AFM investigations. The nanomanipulators are operated directly in an environmental scanning electron microscope (ESEM). We studied the interaction between moisture and the tobermorite surface under controlled relative humidity (RH). The results of topography and adhesion force measurements with AFM suggest that the surface of tobermorite is hydrophobic, which contrasts the macroscopic material properties (e.g. moisture transport in capillary pores).
Marine litter and non-degradable plastic pollution is of global concern. Regular monitoring programs are being established to assess and understand the scale of this pollution. In Europe, the goal of ...the European Marine Strategy Framework Directive (MSFD) is to assess trends in Good Environmental Status and support large-scale actions at the regional level. Marine litter monitoring requires tailored sampling strategies, protocols and indicators, that align with specific objectives and are tailored for local or regional needs. In addition, the uneven spatial and temporal distributions of marine litter present a challenge when designing a statistically powerful monitoring program. In this paper, we critically review the existing marine litter monitoring programs in Europe. We discuss the main constraints, including environmental, logistical, scientific, and ethical factors. Additionally, we outline the critical gaps and shortcomings in monitoring MSFD beaches/shorelines, floating litter, seafloor litter, microplastics, and harm. Several priorities must be established to shape the future of monitoring within the MSFD. Recent developments in analytical approaches, including optimizing protocols and sampling strategies, gaining a better understanding of the spatiotemporal heterogeneity of litter and its implications for survey design and replication, and the inclusion of newly validated methodologies that have achieved sufficient technical readiness, must be considered. Although there are well-established methods for assessing beaches, floating and seafloor litter, it will be necessary to implement monitoring schemes for microplastics in sediments and invertebrates as robust analytical methods become available for targeting smaller particle size classes. Furthermore, the inclusion of indicators for entanglement and injury to marine organisms will have to be considered in the near future. Moreover, the following actions will enhance the effectiveness of monitoring efforts: (1) creating an inventory of accumulation areas and sources of specific types of litter (e.g., fishing gear), (2) monitoring riverine inputs of litter, (3) monitoring atmospheric inputs including microplastics, (4) accidental inputs during extreme weather events, and (5) studying how species at risk may be transported by litter. We provide recommendations to support long-term, effective, and well-coordinated marine litter monitoring within the MSFD to achieve a comprehensive and accurate understanding of marine litter in EU waters. This will allow the development of measures to mitigate the impacts of marine pollution and eventually to evaluate the success of the respective measures.
•Monitoring of marine litter performed in Europe within MSFD has been reviewed.•- Marine litter monitoring gaps and critical points were identified.•Recommendations for improving future monitoring of marine litter within MSFD.
Laser-induced breakdown detection (LIBD) is a promising method to detect trace amounts of nanoparticles (NP, <100 nm) in aqueous suspensions. Based on available systems, we developed a mobile LIBD, ...designed for on-site and on-line measurements. We used the energy ratio of every laser pulse before and after passing the laser beam through the aqueous sample as a new method to detect laser-induced plasma events. The particle size and the particle number density are derived from recorded energy curves. Our LIBD is operated with a Nd:YAG laser at 100 Hz significantly reducing the measurement times compared to other LIBD systems operated at 20 Hz and increasing the capabilities for monitoring purposes. Long-term experiments on water samples revealed losses of NP up to 75% in 15 mL and 35% in 5 L sample containers after 3 months. The size of the particles remained constant (5 L) or slightly decreased (15 mL) indicating significant adsorption of NP to the walls of the sampling containers. Furthermore, we monitored the NP content of water after different purification steps at a drinking water plant (Maennedorf, Lake Zurich, Switzerland). Activated carbon filtration resulted in an increase of the particle size from ∼20 nm to ∼75 nm possibly caused by the release of organic fragments derived from the biology within the activated carbon tank. After the final ultrafiltration step the particle size was around 10 nm in agreement with the nominal cutoff of 100 kDa of the membrane. The results underline the strength of a fast-screening LIBD to detect relative changes in NP size and concentration.
A fast screening laser induced breakdown detection (LIBD) system operated at 100 Hz allows monitoring the nanoparticle content in the drinking water on-site and on-line.
Background and Purpose
To determine the prognostic value for ischemic stroke or transitory ischemic attack (TIA) of plaque surface echogenicity alone or combined to degree of stenosis in a Swiss ...multicenter cohort
Methods
Patients with ≥60% asymptomatic or ≥50% symptomatic carotid stenosis were included. Grey‐scale based colour mapping was obtained of the whole plaque and of its surface defined as the regions between the lumen and respectively 0‐0.5, 0–1, 0–1.5, and 0–2 mm of the outer border of the plaque. Red, yellow and green colour represented low, intermediate or high echogenicity. Proportion of red color on surface (PRCS) reflecting low echogenictiy was considered alone or combined to degree of stenosis (Risk index, RI).
Results
We included 205 asymptomatic and 54 symptomatic patients. During follow‐up (median/mean 24/27.7 months) 27 patients experienced stroke or TIA. In the asymptomatic group, RI ≥0.25 and PRCS ≥79% predicted stroke or TIA with a hazard ratio (HR) of respectively 8.7 p = 0.0001 and 10.2 p < 0.0001. In the symptomatic group RI ≥0.25 and PRCS ≥81% predicted stroke or TIA occurrence with a HR of respectively 6.1 p = 0.006 and 8.9 p = 0.001. The best surface parameter was located at 0‐0.5mm. Among variables including age, sex, degree of stenosis, stenosis progression, RI, PRCS, grey median scale values and clinical baseline status, only PRCS independently prognosticated stroke (p = 0.005).
Conclusion
In this pilot study including patients with at least moderate degree of carotid stenosis, PRCS (0‐0.5mm) alone or combined to degree of stenosis strongly predicted occurrence of subsequent cerebrovascular events.
The ability of metallothionein (MT) to modulate DNA binding by a two-finger peptide of Tramtrack (TTK), a CCHH zinc transcription
factor, was investigated using metal-bound and metal-deficient forms ...of rabbit MT-2 and the TTK peptide. Thionein inhibited
DNA binding by zinc-bound TTK, and Zn-MT restored DNA-binding by zinc-deficient apo-TTK. âFreeâ zinc at low concentrations
was as effective as Zn-MT in restoring DNA binding by apopeptide but was inhibitory at concentrations equal to zinc bound
to 2 mol eq and higher of Zn-MT. Substitution of cadmium for zinc reduced the affinity of the peptide for its DNA binding
site. This effect was reversed by incubation with Zn-MT. The circular dichroic spectra of the TTK peptide indicated that zinc
removal resulted in loss of α-helical structures, which are sites of DNA contact points. Reconstitution with cadmium resulted
in stoichiometric substitution of 2 mol of Cd/mol of peptide but not recovery of α-helical structures. Incubation of Cd-TTK
with Zn-MT restored the secondary structure expected for zinc-bound TTK. The ability of Zn-MT and thionein to restore or inhibit
DNA-binding by TTK was associated with effects on the metallation status of the peptide and related alterations in its secondary
structure.
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