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Abstract Reversible ferroelectric domain wall movements beyond the 10 nm range associated with Rayleigh behavior are usually restricted to specific defect-engineered systems. Here, we demonstrate that such long-range movements naturally occur in the improper ferroelectric ErMnO3 during electric-field-cycling. We study the electric-field-driven motion of domain walls, showing that they readily return to their initial position after having traveled distances exceeding 250 nm. By applying switching spectroscopy band-excitation piezoresponse force microscopy, we track the domain wall movement with nanometric spatial precision and analyze the local switching behavior. Phase field simulations show that the reversible long-range motion is intrinsic to the hexagonal manganites, linking it to their improper ferroelectricity and topologically protected structural vortex lines, which serve as anchor point for the ferroelectric domain walls. Our results give new insight into the local dynamics of domain walls in improper ferroelectrics and demonstrate the possibility to reversibly displace domain walls over much larger distances than commonly expected for ferroelectric systems in their pristine state, ensuring predictable device behavior for applications such as tunable capacitors or sensors.

Future air traffic using (green) hydrogen (H2) promises zero carbon emissions, but the effects of contrails from this new technology have hardly been investigated. We study contrail formation behind aircraft with H2 combustion by means of the particle-based Lagrangian Cloud Module (LCM) box model. Assuming the absence of soot and ultrafine volatile particle formation, contrail ice crystals form solely on atmospheric background particles mixed into the plume. While a recent study extended the original LCM with regard to the contrail formation on soot particles, we further advance the LCM to cover the contrail formation on ambient particles. For each simulation, we perform an ensemble of box model runs using the dilution along 1000 different plume trajectories. The formation threshold temperature of H2 contrails is around 10 K higher than for conventional contrails (which form behind aircraft with kerosene combustion). Then, contrail formation becomes primarily limited by the homogeneous freezing temperature of the water droplets such that contrails can form at temperatures down to around 234 K. The number of ice crystals formed varies strongly with ambient temperature even far away from the contrail formation threshold. The contrail ice crystal number clearly increases with ambient aerosol number concentration and decreases significantly for ambient particles with mean dry radii ⪅ 10 nm due to the Kelvin effect. Besides simulations with one aerosol particle ensemble, we analyze contrail formation scenarios with two co-existing aerosol particle ensembles with different mean dry sizes or hygroscopicity parameters. We compare them to scenarios with a single ensemble that is the average of the two aerosol ensembles. We find that the total ice crystal number can differ significantly between the two cases, in particular if nucleation-mode particles are involved. Due to the absence of soot particle emissions, the ice crystal number in H2 contrails is typically reduced by more than 80 %–90 % compared to conventional contrails. The contrail optical thickness is significantly reduced, and H2 contrails either become visible later than kerosene contrails or are not visible at all for low ambient particle number concentrations. On the other hand, H2 contrails can form at lower flight altitudes where conventional contrails would not form.

Recent laboratory studies have shown that biopolymers have the potential to act as dust suppressants on barren mine soils. However, there is a lack of field trials investigating the effectiveness of biopolymer treatments under real field conditions on a large scale. This study performed field trials to examine the potential of three biopolymers—corn starch (CS), xanthan gum (XG), and fava bean protein concentrate (FBPC)—as dust suppressants. The field trials started in August 2022 with spraying of low doses of the selected biopolymers on trial areas of an overburden dump at the Inden open-cast lignite mine, Germany. The field trials were conducted over 45 days. They included repeated measurements of dust emissions from soil plots exposed to different airflows generated by an electric blower, visual inspections, and penetrometer tests. The results showed that all biopolymer treatments effectively suppressed dust emissions in the short term up to 8 days after application. Total suspended particle emissions measured on the biopolymer-treated trial plots were significantly reduced and ranged from 0.05 to 0.27 mg/m3 compared to the untreated control (4.5 to 39.2 mg/m3). The visual inspections and penetrometer tests supported these results. After day 8, rainfall-induced leaching of the biopolymers resulted in the rapid degradation of the treatments’ effectiveness. The results suggest that the treatments would have lasted longer under dry conditions. Thus, the field trials provide practical evidence that biopolymers can effectively mitigate dust emissions on exposed, undisturbed mine soils in the short term, making them a bio-based alternative to traditional dust suppressants, such as chloride salts or petroleum-based products.

The functionality of magnetoelectric multiferroics depends on the formation, size, and coupling of their magnetic and electric domains. Knowing the parameters guiding these criteria is a key effort in the emerging field of magnetoelectric domain engineering. Here we show, using a combination of piezoresponse-force microscopy, nonlinear optics, and x-ray scattering, that the correlation length setting the size of the ferroelectric domains in the multiferroic hexagonal manganites can be engineered from the micron range down to a few unit cells under the substitution of Mn^{3+} ions with Al^{3+} ions. The magnetoelectric coupling mechanism between the antiferromagnetic Mn^{3+} order and the distortive-ferroelectric order remains intact even at substantial replacement of Mn^{3+} by Al^{3+}. Hence, chemical substitution proves to be an effective tool for domain-size engineering in one of the most studied classes of multiferroics.

Reversible ferroelectric domain wall movements beyond the 10 nm range associated with Rayleigh behavior are usually restricted to specific defect-engineered systems. Here, we demonstrate that such long-range movements naturally occur in the improper ferroelectric ErMnO3 during electric-field-cycling. We study the electric-field-driven motion of domain walls, showing that they readily return to their initial position after having traveled distances exceeding 250 nm. By applying switching spectroscopy band-excitation piezoresponse force microscopy, we track the domain wall movement with nanometric spatial precision and analyze the local switching behavior. Phase field simulations show that the reversible long-range motion is intrinsic to the hexagonal manganites, linking it to their improper ferroelectricity and topologically protected structural vortex lines, which serve as anchor point for the ferroelectric domain walls. Our results give new insight into the local dynamics of domain walls in improper ferroelectrics and demonstrate the possibility to reversibly displace domain walls over much larger distances than commonly expected for ferroelectric systems in their pristine state, ensuring predictable device behavior for applications such as tunable capacitors or sensors. The authors find the electric-field-driven motion of domain walls in the improper ferroelectric ErMnO3, showing that they readily return to their initial position after having travelled distances exceeding 250 nm. [ABSTRACT FROM AUTHOR]

At present, the majority of water testing is carried out in the laboratory, and portable field methods for the quantification of elements in natural waters remain to be established. In contrast, portable instruments like portable X-ray fluorescence (pXRF) analysis and portable laser-induced breakdown spectroscopy (pLIBS) have become routine analytical methods for the quantification of elements in solids. This study aims to show that pLIBS can also be used for chemical compositional measurements of natural waters. Bottled mineral waters were selected as sample materials. A surface-enhanced liquid-to-solid conversion technique was used to improve the detection limits and circumvent the physical limitations in liquid analysis. The results show that low to medium mineralised waters can be analysed quantitatively for their ions using the documented method. For more highly concentrated samples, typically above an electrical conductivity (EC) of 1000 µS/cm, further adjustment is required in the form of self-absorption correction. However, water with a conductivity up to this limit can be analysed for the main cations (Li+, Na+, Mg2+, K+, Ca2+, and Sr2+) as well as the main anions (SO42− and Cl−) using the documented method. This study demonstrates that there is significant potential for developing field-based pLIBS as a tool for quantitative water analysis.

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In h-RMnO3, the linear magnetoelectric effect is symmetry forbidden. Here, the authors show a pronounced magnetoelectric coupling driven by superexchange interaction giving rise to types of topological defects like magnetoelectric domain walls and vortex-like singularities.

We investigate the effect of chemical doping on the electric and magnetic domain pattern in multiferroic hexagonal ErMnO3. Hole- and electron doping are achieved through the growth of Er1-xCaxMnO3 and Er1-xZrxMnO3 single crystals, which allows for a controlled introduction of divalent and tetravalent ions, respectively. Using conductance measurements, piezoresponse force microscopy and nonlinear optics we study doping-related variations in the electronic transport and image the corrsponding ferroelectric and antiferromagnetic domains. We find that moderate doping levels allow for adjusting the electronic conduction properties of ErMnO3 without destroying its characteristic domain patterns. Our findings demonstrate the feasibility of chemical doping for nonperturbative property-engineering of intrinsic domain states in this important class of multiferroics.

For the dust control of barren mine soils, protein and polysaccharide biopolymers have recently shown potential as environmentally friendly alternatives to conventional dust suppressants (e.g., salt brines or petroleum-based products). However, laboratory studies that determine suitable application parameters are required for large-scale field trials. This study performed wind tunnel and pocket penetrometer tests to investigate the wind erosion and penetration resistance of treatments with different biopolymer types, concentrations (wt%), and application rates (L/m2) on two mine soils. The results demonstrate that all treatments significantly enhanced the wind erosion resistance of both tested soil types, with the biopolymer type, concentration, and application rate having a significant effect. Depending on the biopolymer type and application parameter, the wind-induced soil loss ranged from 0.86 to 423.9 g/m2 (Control = 2645.0 g/m2) for medium-grained sand and from 0.3 to 225 g/m2 (Control = 26,177.0 g/m2) for fine-grained silica sand, with the soil loss reducing as concentrations increase, until it reached a plateau concentration. For a similar performance, the tested proteins (wheat and fava bean protein) must be applied at higher concentrations than those of the polysaccharides (xanthan gum, corn starch, and carboxymethylcellulose). Spearman rank correlation revealed a moderate-to-strong negative correlation between soil loss (g/m2) and penetration resistance (N), rendering the pocket penetrometer a rapid, low-cost, and indirect method for evaluating potential dust suppressants. This research contributes to evaluating biopolymers as alternatives to traditional dust suppressants for controlling dust emissions on barren surfaces. Biopolymers are biodegradable and can be sourced regionally at a relatively low cost, reducing the environmental impact and expenses associated with dust suppression.

Polysaccharide biopolymers have been shown to be alternatives to established dust suppressants. This study investigates the potential of 14 polysaccharides and proteins from diverse botanical (corn, pea, wheat, cellulose, potato, and fava bean) and animal (pig, chicken, and cow) sources as dust suppressants on two mine soils (medium-grained sand and fine-grained silica sand). Results of laboratory tests demonstrate that the type of biopolymer and its concentration have a significant effect on penetration resistance, moisture retention, and crust thickness. Depending on biopolymer type, concentration, and soil type, moisture retention range from 1.0 to 19.5 wt% (control, Cmedium-gr. = 2.5 and Cfine-gr. = 6.9 wt%), penetration resistance from 1.7 to 37.9 N (Cmedium-gr. = 1.5 and Cfine-gr. = 1.7 N), and crust thickness from 0.3 to 18.1 mm (Cmedium-gr. and Cfine-gr. = 0 mm). Proteins form crusts with penetration resistances similar to polysaccharides but mainly require higher concentrations than polysaccharides. Based on the test results, xanthan gum, carboxymethyl cellulose, corn starch, fava bean protein concentrate, and plasma protein exhibit the highest potential to act as dust suppressants. This research contributes to evaluating biopolymers as environmentally friendly soil amendments that may be used to control fugitive dust emissions from large, barren surfaces.

Für die Gewährleistung von Sicherheit in Stadtquartieren ist es kaum zielführend, wenn kriminalpräventive Maßnahmen lediglich anlassbezogen und ohne eine belastbare empirische Wissensgrundlage der lokalen Problemlagen umgesetzt werden. Der Transfer wissenschaftlicher Erkenntnisse in die kommunale Handlungspraxis wird dabei oftmals durch einen Mangel an Vernetzung zwischen lokalen Sicherheitsakteur*innen, kommunaler Verwaltung und politischen Entscheidungsträger*innen zusätzlich erschwert. In dem Beitrag wird ein im Rahmen des vom BMBF geförderten Forschungsprojektes SiQua initiiertes Pilotprojekt vorgestellt, das eine Neustrukturierung der kommunalen Präventionsarbeit in Dresden zum Ziel hat. Die darin entwickelten Prozessabläufe einer empirisch geleiteten Maßnahmenplanung und einer Professionalisierung der organisationalen Zusammenarbeit werden auf ihre Wirksamkeit in der Praxis getestet und kritisch reflektiert. Als Anwendungsbeispiel dient das soziale Phänomen des Cornerns im Dresdner Kneipenviertel Neustadt.