Abstract: Cold atmospheric plasma (CAP) is a promising new agent for (selective) cancer treatment, but the underlying cause of the anti-cancer effect of CAP is not well understood yet. Among different theories and observations, one theory in particular has been postulated in great detail and consists of a very complex network of reactions that are claimed to account for the anti-cancer effect of CAP. Here, the key concept is a reactivation of two specific apoptotic cell signaling pathways through catalase inactivation caused by CAP. Thus, it is postulated that the anti-cancer effect of CAP is due to its ability to inactivate catalase, either directly or indirectly. A theoretical investigation of the proposed theory, especially the role of catalase inactivation, can contribute to the understanding of the underlying cause of the anti-cancer effect of CAP. In the present study, we develop a mathematical model to analyze the proposed catalase-dependent anti-cancer effect of CAP. Our results show that a catalase-dependent reactivation of the two apoptotic pathways of interest is unlikely to contribute to the observed anti-cancer effect of CAP. Thus, we believe that other theories of the underlying cause should be considered and evaluated to gain knowledge about the principles of CAP-induced cancer cell death.

Abstract: An efficient and selective procedure was developed for the direct C2-H arylation of indoles using a Pd-loaded metal-organic framework (MOF) as a heterogeneous catalyst and the nontoxic biomass-derived solvent gamma-valerolactone (GVL) as a reaction medium. The developed method allows for excellent yields and C-2 selectivity to be achieved and tolerates various substituents on the indole scaffold. The established conditions ensure the stability of the catalyst as well as recoverability, reusability, and low metal leaching into the solution.

Abstract: When monolayer (ML) MoS2 is placed on a substrate, the proximity-induced interactions such as the Rashba spin-orbit coupling (RSOC) and exchange interaction (EI) can be introduced. Thus, the electronic system can behave like a spintronic device. In this study, we present a theoretical study on how the presence of the RSCO and EI can lead to the band splitting, the lifting of the valley degeneracy and to the spin polarization in n- and p-type ML MoS2. We find that the maxima of the in-plane spin orientation in the conduction and valence bands in ML MoS2 depend on the Rashba parameter and the effective Zeeman field factor. At a fixed Rashba parameter, the minima of the split conduction band and the maxima of the split valence band along with the spin polarization in ML MoS2 can be tuned effectively by varying the effective Zeeman field factor. On the basis that the EI can be induced by placing the ML MoS2 on a ferromagnetic substrate or by magnetic doping in ML MoS2, we predict that the interesting spintronic effects can be observed in n- and p-type ML MoS2. This work can be helpful to gain an in-depth understanding of the basic physical properties of ML MoS2 for application in advanced electronic and optoelectronic devices.

Abstract: This Special Issue, entitled “Plasma Medicine Technologies”, covers the latest remarkable developments in the field of plasma bioscience and medicine. Plasma medicine is an interdisciplinary field that combines the principles of plasma physics, material science, bioscience, and medicine, towards the development of therapeutic strategies. A study on plasma medicine has yielded the development of new treatment opportunities in medical and dental sciences. An important aspect of this issue is the presentation of research underlying new therapeutic methods that are useful in medicine, dentistry, sterilization, and, in the current scenario, that challenge perspectives in biomedical sciences. This issue is focused on basic research on the characterization of the bioplasma sources applicable to living cells, especially to the human body, and fundamental research on the mutual interactions between bioplasma and organic–inorganic liquids, and bio or nanomaterials.

Abstract: N2 fixation into NH3 is one of the main processes in the chemical industry. Plasma catalysis is among the environmentally friendly alternatives to the industrial energy-intensive Haber-Bosch process. However, many questions remain open, such as the applicability of the conventional catalytic knowledge to plasma. In this work, we studied the performance of Al2O3-supported Fe, Ru, Co and Cu catalysts in plasma-catalytic NH3 synthesis in a DBD reactor. We investigated the effects of different active metals, and different ratios of the feed gas components, on the concentration and production rate of NH3, and the energy consumption of the plasma system. The results show that the trend of the metal activity (common for thermal catalysis) does not appear in the case of plasma catalysis: here, all metals exhibited similar performance. These findings are in good agreement with our recently published microkinetic model. This highlights the virtual independence of NH3 production on the metal catalyst material, thus validating the model and indicating the potential contribution of radical adsorption and Eley-Rideal reactions to the plasma-catalytic mechanism of NH3 synthesis.

Abstract: We introduce single-shot x-ray tomography that aims to estimate the target image from a single cone-beam projection measurement. This linear inverse problem is extremely under-determined since the measurements are far fewer than the number of unknowns. Moreover, it is more challenging than conventional tomography, where a sufficiently large number of projection angles forms the measurements, allowing for a simple inversion process. However, single-shot tomography becomes less severe if the target image is only composed of known shapes. This paper restricts analysis to target image function that can be decomposed into known compactly supported non-negative-valued functions termed shapes. Hence, the shape prior transforms a linear ill-posed image estimation problem to a non-linear problem of estimating the roto-translations of the shapes. We circumvent the non-linearity by using a dictionary of possible roto-translations of the shapes. We propose a convex program CoShaRP, to recover the dictionary coefficients successfully. CoShaRP relies on simplex-type constraints and can be solved quickly using a primal-dual algorithm. The numerical experiments show that CoShaRP recovers shape stably from moderately noisy measurements.

Abstract: In Ethiopia, urban expansion happens at high rates and results in land expropriations often at the cost of agriculture and forests. The process of urban expansion does not include assessment of ecosystem services (ES). This has been causing unintended environmental problems. This study aims to uncover ES of three most important land use types (cropland, agroforestry, and grassland) that are threatened by land expropriation for urban expansion in Bahir Dar City. The study applied a participatory approach using community perception and expert judgments (N = 108). Respondents were asked to locate their perceptions on the use of 35 different ES, and then to evaluate the potential of the land use. Respondents were shown to have the ability to differentiate between ES and land use in terms of their potential to deliver ES. The results show that agroforestry is expected to have a high relevant potential to deliver 31% of all ES, but cropland 20% and grassland 14%. Food, fodder, timber, firewood, fresh water, energy, compost, climate regulation, erosion prevention, and water purification and treatment were identified as the ten most important services. It is not only the provisioning services that are being supplied by the land use types which are expropriated for urbanization, but also regulating, supporting and cultural services. To ensure sustainable urban land development, we suggest the consideration of the use of ES and the potential of the land use to supply ES when making land use decisions, including land expropriation for urban expansion.

Abstract: Plasmonic catalysis in the colloidal phase requires robust surface ligands that prevent particles from aggregation in adverse chemical environments and allow carrier flow from reagents to nanoparticles. This work describes the use of a water-soluble conjugated polymer comprising a thiophene moiety as a surface ligand for gold nanoparticles to create a hybrid system that, under the action of visible light, drives the conversion of the biorelevant NAD+ to its highly energetic reduced form NADH. A combination of advanced microscopy techniques and numerical simulations revealed that the robust metal-polymer heterojunction, rich in sulfonate functional groups, directs the interaction of electron-donor molecules with the plasmonic photocatalyst. The tight binding of polymer to the gold surface precludes the need for conventional transition-metal surface cocatalysts, which were previously shown to be essential for photocatalytic NAD(+) reduction but are known to hinder the optical properties of plasmonic nanocrystals. Moreover, computational studies indicated that the coating polymer fosters a closer interaction between the sacrificial electron-donor triethanolamine and the nanoparticles, thus enhancing the reactivity.

Abstract: We explorethepotentialofmicrowave(MW)-plasma-based in situ
utilizationoftheMartianatmospherewithafocusonthenovelpos-
sibilityoffixingN2 forfertilizerproduction. Conversioninasimulant
plasma (i.e.,
96% CO2,
2% N2, and
2% Ar),performedunderen-
ergyconditionssimilartothoseoftheMarsOxygen In Situ Resource
UtilizationExperiment(MOXIE),currentlyonboardNASA’sPerse-
verancerover,demonstratesthatO/O2 formedthroughCO2 dissociation
facilitatesthefixationoftheN2 fractionviaoxidationtoNOx.
PromisingproductionratesforO2, CO,andNOx of 47.0,76.1,and
1.25g/h,respectively,arerecordedwithcorrespondingenergy
costs of0.021,0.013,and0.79kWh/g,respectively.Notably,O2
productionratesare
30 timeshigherthanthosedemonstrated
by MOXIE,whiletheNOx production raterepresentsan
7% fixa-
tionoftheN2 fraction presentintheMartian atmosphere.MW-
plasma-basedconversionthereforeshowsgreatpotentialasan in
situ resourceutilization(ISRU)technologyonMarsinthatitsimulta-
neouslyfixesN2 and producesO2.

Abstract: Using a particle-based model, we examine the collective dynamics of skyrmions interacting with a funnel potential under dc driving as the skyrmion density and relative strength of the Magnus and damping terms are varied. For driving in the easy direction, we find that increasing the skyrmion density reduces the average skyrmion velocity due to jamming of skyrmions near the funnel opening, while the Magnus force causes skyrmions to accumulate on one side of the funnel array. For driving in the hard direction, there is a critical skyrmion density below which the skyrmions become trapped. Above this critical value, a clogging effect appears with multiple depinning and repinning states where the skyrmions can rearrange into different clogged configurations, while at higher drives, the velocity-force curves become continuous. When skyrmions pile up near the funnel opening, the effective size of the opening is reduced and the passage of other skyrmions is blocked by the repulsive skyrmion-skyrmion interactions. We observe a strong diode effect in which the critical depinning force is higher and the velocity response is smaller for hard direction driving. As the ratio of Magnus force to dissipative term is varied, the skyrmion velocity varies in a non-linear and non-monotonic way due to the pile up of skyrmions on one side of the funnels. At high Magnus forces, the clogging effect for hard direction driving is diminished.

Abstract: As a part of the NASA Global Tropospheric Experiment (GTE), aerosols were sampled in the tropical rain forest of the Amazon Basin during the Amazon Boundary Layer Experiment (ABLE 2B) in April and May 1987, in the wet season, when no forest burning occurs. Fine (dp < 2.0 μm) and coarse (2.0 < dp < 15 μm) aerosol fractions were collected using stacked filter units, at three sites under the forest canopy and at three levels of a tower inside the jungle. Particle-induced X ray emission (PIXE) was used to measure concentrations of 22 elements (Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Zr, and Pb). Morphological and trace element measurements of individual particles were carried out by automated electron probe X ray microanalysis. Gravimetric analysis was performed to obtain the fine and coarse aerosol mass concentration. Absolute factor analysis was used to interpret the large data set of the trace element concentrations and to obtain elemental source profiles. Hierarchical cluster analysis was used to derive groups of individual particles. The concentrations of soil dust related elements (Al, Si, Ti, Fe, Mn) were 5 times larger in the wet season compared to the 1985 ABLE 2A dry season experiment. Biogenic aerosol related elements in the fine fraction showed lower concentrations in the wet season. Fine aerosol mass concentration averaged only 2.1±0.7 μg m−3, while the average coarse mass concentration was 6.1±1.8 μg m −3. Sulphur concentrations averaged 76±14 ng m −3 in the fine fraction and 37±9 ng m −3 in the coarse fraction. Biogenic aerosol-related elements were dominant under the forest canopy, while soil dust dominated at the top of the forest canopy. Only two factors explained about 90% of the data variability for the fine and coarse aerosol fractions. These were soil dust (represented mainly by Al, Si, Ti, Mn, and Fe) and biogenic aerosol (represented by K, P, Cl, S, Zn, and the aerosol mass concentration). Source profiles showed a homogeneous aerosol distribution with similar elemental compositions at the different sampling sites. Enrichment factor calculations revealed a soil dust elemental profile similar to the average bulk soil composition, and a biogenic component similar to the plant bulk elemental composition. Total aerosol mass source apportionment showed that biogenic particles account for 5595% of the airborne concentrations. The analysis of individual aerosol particles showed that the biogenic particles consist of leaf fragments, pollen grains, fungi, algae, and other types of particles. Several groups of particles with K, Cl, P, S, and Ca as minor elements could easily be identified as biogenic particles on the basis of their morphology. Considering the vast area of tropical rain forests and the concentrations measured in this work, it is possible that biogenic particles can play an important role in the global aerosol budget and in the global biogeochemical cycles of various elements.

Abstract: The combination of several micro-XRF analysis modes is presented for the investigation of an illuminated parchment manuscript. With a commercial instrument, conventional micro-XRF spot analysis (0D) and mapping (2D) are performed, yielding detailed lateral elemental information. Depth resolution becomes accessible by mounting an additional polycapillary lens in front of an SDD detector. Quantitative confocal depth profiles (1D) are presented as well as the full separation of the front and the backside decorations with the help of fast 3D mappings of specific areas. Only through the use of these multidimensional modes can elemental information be assigned both to lateral and depth positions, making the analysis of such heterogeneous samples feasible.

Abstract: Nanocomposites In2O3/Ag obtained by ultraviolet (UV) photoreduction and impregnation methods were studied as materials for CO sensors operating in the temperature range 25-250 degrees C. Nanocrystalline In2O3 and In2O3/Ag nanocomposites were characterized by X-ray diffraction (XRD), single-point Brunauer-Emmet-Teller (BET) method, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) with energy dispersive X-ray (EDX) mapping. The active surface sites were investigated using Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR) spectroscopy and thermo-programmed reduction with hydrogen (TPR-H-2) method. Sensor measurements in the presence of 15 ppm CO demonstrated that UV treatment leads to a complete loss of In2O3 sensor sensitivity, while In2O3/Ag-UV nanocomposite synthesized by UV photoreduction demonstrates an increased sensor signal to CO at T < 200 degrees C. The observed high sensor response of the In2O3/Ag-UV nanocomposite at room temperature may be due to the realization of an additional mechanism of CO oxidation with participation of surface hydroxyl groups associated via hydrogen bonds.

Abstract: Developing an efficient material as a counter electrode (CE) with excellent catalytic activity, intrinsic stability, and low cost is essential for the commercial application of dye-sensitized solar cells (DSSCs). Transition metal phosphides have been demonstrated as outstanding multifunctional catalysts in a broad range of energy conversion technologies. Here, we exploited different phases of iron phosphide as CEs in DSSCs with an I–/I3–-based electrolyte. Solvothermal synthesis using a triphenylphosphine precursor as a phosphorus source allows to grow a Fe2P phase at 300 °C and a FeP phase at 350 °C. The obtained iron phosphide catalysts were coated on fluorine-doped tin oxide substrates and heat-treated at 450 °C under an inert gas atmosphere. The solar-to-current conversion efficiency of the solar cells assembled with the Fe2P material reached 3.96 ± 0.06%, which is comparable to the device assembled with a platinum (Pt) CE. DFT calculations support the experimental observations and explain the fundamental origin behind the improved performance of Fe2P compared to FeP. These results indicate that the Fe2P catalyst exhibits excellent performance along with desired stability to be deployed as an efficient Pt-free alternative in DSSCs.

Abstract: Mass, major ionic components (MICs) of PM2.5, and related gaseous pollutants (SO2, NOx, NH3, HNO2, and HNO3) were monitored over six locations of different anthropogenic influence (industrial, urban, suburban, and rural) in Belgium. SO42-, NO3-, NH4+, and Na+ were the primary ions of PM2.5 with averages diurnal concentrations ranging from 0.44.5, 0.37.6, 0.94.9, and 0.41.2 µg m-3, respectively. MICs formed 39% of PM2.5 on an average, but it could reach up to 8098%. The SO2, NO, NO2, HNO2, and HNO3 levels showed high seasonal and site-specific fluctuations. The NH3 levels were similar over all the sites (26 µg m-3), indicating its relation to the evenly distributed animal husbandry activities. The sulfur and nitrogen oxidation ratios for PM2.5 point towards a low-to-moderate formation of secondary sulfate and nitrate aerosols over five cities/towns, but their fairly intensive formation over the rural Wingene. Cluster analysis revealed the association of three groups of compounds in PM2.5: (i) NH4NO3, KNO3; (ii) Na2SO4; and (iii) MgCl2, CaCl2, MgF2, CaF2, corresponding to anthropogenic, sea-salt, and mixed (sea-salt + anthropogenic) aerosols, respectively. The neutralization and cation-to-anion ratios indicate that MICs of PM2.5 appeared mostly as (NH4)2SO4 and NH4NO3 salts. Sea-salt input was maximal during winter reaching up to 12% of PM2.5. The overall average Cl-loss for sea-salt particles of PM2.5 at the six sites varied between 69 and 96% with an average of 87%. Principal component analysis revealed vehicular emission, coal/wood burning and animal farming as the dominating sources for the ionic components of PM2.5.