Abstract: Drought is a persistent, sluggish natural disaster in developing countries that has generated a financial burden and an unstable climate. Farmers should adopt early warning systems (EWS) in their strategies for monitoring drought to reduce its serious consequences. However, farmers in developing countries are reluctant to use EWS as their management strategies. Hence, the aim of this study was to investigate the decision of farmers to use climate knowledge through the model of farming activity in Kermanshah Township, Iran. A surveyor questionnaire was used to gather data from 370 wheat farmers using random sampling methods inmulti-stage clusters. Results revealed that the decision to use climate information is affected by personal factors, attitude towards climate information, objectives of using climate information, and external/physical farming factors. The result of this study has implications for drought management practitioners. To be specific, the results can aid policymakers to design early alert programs to minimize the risk of drought and thus move from conventional to climate smart agriculture. (C) 2020 Elsevier B.V. All rights reserved.

Abstract: Doped Cr2O3 has been shown to be a p-type transparent conducting oxide (TCO). Its conductivity, however, is low. As for most p-type TCOs, the main problem is the high effective hole mass due to flat valence bands. We use first-principles methods to investigate whether one can increase the valence band dispersion (i.e. reduce the hole mass) by anion alloying with sulfur, while keeping the band gap large enough for transparency. The alloying concentrations considered are given by Cr(4)SxO(6-x), with x = 1-5. To be able to describe the electronic properties of these materials accurately, we first study Cr2O3, examining critically the accuracy of different density functionals and methods, including PBE, PBE+U, HSE06, as well as perturbative approaches within the GW approximation. Our results demonstrate that Cr4S2O4 has an optical band gap of 3.08 eV and an effective hole mass of 1.8 m(e). This suggests Cr4S2O4 as a new p-type TCO host candidate.

Abstract: Dit onderzoek presenteert een overzicht van de mogelijkheden van LA-ICP-MS als een techniek voor kwantitatieve analyse, bepalen van isotoopverhoudingen en elementaire beeldvorming. Hiervoor wordt de techniek zelf voorgesteld en worden de belangrijkste parameters die een invloed hebben op de kwaliteit van een LA-ICP-MS meting beschreven. Voor kwantitieve analyse worden de huidige calibratiestrategieën voor LA-ICP-MS toegelicht, zowel op het vlak van selectie en bereiding van standaarden als op het vlak van dataverwerking. Daarnaast werd een nieuwe calibratiestrategie voorgesteld, gebaseerd op een lineaire combinatie van standaarden. Een case study met de traditionele calibratiestrategie uit de literatuur werd uitgevoerd en vergeleken met data van SEM-EDX om een referentiekader te schetsen voor de performantie van de techniek. In een tweede case study werd onze nieuwe calibratiestrategie toegepast en werd er uitsluitend gebruik gemaakt van LA-ICP-MS, wat uitstekende resultaten opleverde. Met het oog op het bepalen van isotoopverhoudingen, werd er onderzocht wat de limieten zijn van het gebruik van een lage resolutie quadrupool massaspectrometer voor deze bepaling. Dit stelde ons in staat om de te verwachten accuraatheid en precisie in te schatten. De performantie bleek goed genoeg te zijn om weapon-grade plutonium te onderscheiden van global fall-out, zoals het werd aangetoond in de case study omtrent dit onderwerp. Uiteindelijk hebben we ook LA-ICP-MS geëvalueerd als een techniek voor elementaire beeldvorming, waarbij we tevens de meest courante multivariate data analyse hebben beschreven. Om de techniek te plaatsen tegenover andere elementaire technieken, werd een historisch verffragment geanalyseerd dat in het verleden reeds geanalyseerd was met SEM-EDX and μ-XRD. Op die manier konden we de resultaten accuraat vergelijken met de andere technieken.

Abstract: Dislocations are always observed during crystal growth, and it is usually desirable to reduce the dislocation density in high-quality crystals. Here, the annihilation process of the 30 degrees Shockley partial dislocation pairs in CdTe is studied by first-principles calculations. We found that the dislocations can glide relatively easily due to the weak local bonding. Our systematic study of the slipping mechanism of the dislocations suggests that the energy barrier for the annihilation process is low. Band structure calculations reveal that the band bending caused by the charge transfer between the two dislocation cores depends on the core-core distance. A simple linear model is proposed to describe the mechanism of formation of the dislocation pair. More importantly, we demonstrate that hole injection can affect the core structure, increase the mobility, and eventually trigger a spontaneous mutual annihilation, which could be employed as a possible facile way to reduce the dislocation density.

Abstract: Dislocation mediated plastic deformation decisively influences the friction coefficient and the microstructural changes at many metal sliding interfaces during tribological loading. This work explores the initiation of a tribologically induced microstructure in the vicinity of a copper twin boundary. Two distinct horizontal dislocation traces lines (DTL) are observed in their interaction with the twin boundary beneath the sliding interface. DTL formation seems unaffected by the presence of the twin boundary but the twin boundary acts as an indicator of the occurring deformation mechanisms. Three concurrent elementary processes can be identified: simple shear of the subsurface area in sliding direction, localized shear at the primary DTL and crystal rotation in the layers above and between the DTLs around axes parallel to the transverse direction. Crystal orientation analysis demonstrates a strong compatibility of these proposed processes. Quantitatively separating these different deformation mechanisms is crucial for future predictive modeling of tribological contacts.

Abstract: Discrepancies exist between the theoretically predicted and experimentally measured performance of band-to-band tunneling devices, such as Esaki diodes and tunnel field-effect transistors (TFETs). We resolve this discrepancy for highly-doped, direct-bandgap Esaki diodes by successfully calibrating a semi-classical model for high-doping-induced ballistic band-tails tunneling currents at multiple temperatures with two In0.53Ga0.47As Esaki diodes using their SIMS doping profiles, C-V characteristics and their forward-bias current density in the negative differential resistance (NDR) regime. The current swing in the NDR regime is shown not to be linked to the band-tails Urbach energy. We further demonstrate theoretically that the calibrated band-tails contribution is also the dominant band-tails contribution to the subthreshold swing of the corresponding TFETs. Lastly, we verify that the presented procedure is applicable to all direct-bandgap semiconductors by successfully applying it to InAs Esaki diodes in literature.

Abstract: Direct splitting of earth-abundant seawater provides an eco-friendly route for the production of clean H2, but is hampered by selectivity and stability issues. Direct seawater electrolysis is the most established technology, attaining high current densities in the order of 1–2 A cm−2. Alternatively, light-driven processes such as photocatalytic and photoelectrochemical seawater splitting are particularly promising as well, as they rely on renewable solar power. Solar-to-Hydrogen efficiencies have increased over the past decade from negligible values to about 2%. Especially the absence of large local pH changes (in the order of several tenths of a pH unit compared to up to 9 pH units for electrolysis) is a strong asset for pure photocatalysis. This may lead to less adverse side-reactions such as Cl2 and ClO− formation, (acid or base induced) corrosion and scaling. Besides, additional requirements for electrolytic cells, e.g. membranes and electricity input, are not needed in pure photocatalysis systems. In this review, the state-of-the-art technologies in light-driven seawater splitting are compared to electrochemical approaches with a focus on sustainability and stability. Promising advances are identified at the level of the catalyst as well as the process, and insight is provided in solutions crossing different fields.

Abstract: Direct oxidation of methane to methanol (DOMTM) is attractive for the increasing industrial demand of feedstock. In this review, the latest advances in heterogeneous catalysis and plasma catalysis for DOMTM are summarized, with the aim to pinpoint the differences between both, and to provide some insights into their reaction mechanisms, as well as the implications for future development of highly selective catalysts for DOMTM.

Abstract: Direct mercury (Hg) speciation was assessed for soil samples with a Hg concentration ranging from 7 up to 240 mg kg1. Hg chemical forms were identified and quantified by sequential extractions and bulkand micro-analytical techniques exploiting synchrotron generated X-rays. In particular, microspectroscopic techniques such as m-XRF, m-XRD and m-XANES were necessary to solve bulk Hg speciation, in both soil fractions <2 mm and <2 mm. The main Hg-species found in the soil samples were metacinnabar (b-HgS), cinnabar (a-HgS), corderoite (Hg3S2Cl2), and an amorphous phase containing Hg bound to chlorine and sulfur. The amount of metacinnabar and amorphous phases increased in the fraction <2 mm. No interaction among Hg-species and soil components was observed. All the observed Hgspecies originated from the slow weathering of an inert Hg-containing waste material (K106, U.S. EPA) dumped in the area several years ago, which is changing into a relatively more dangerous source of pollution.

Abstract: Direct experimental measurement of thermal expansion coefficient without substrate effects is a challenging task for two-dimensional (2D) materials, and its accurate estimation with large-scale ab initio molecular dynamics is computationally very expensive. Machine learning-based interatomic potentials trained with ab initio data have been successfully used in molecular dynamics simulations to decrease the computational cost without compromising the accuracy. In this study, we investigated using Gaussian approximation potentials to reproduce the density functional theory-level accuracy for graphene within both lattice dynamical and molecular dynamical methods, and to extend their applicability to larger length and time scales. Two such potentials are considered, GAP17 and GAP20. GAP17, which was trained with pristine graphene structures, is found to give closer results to density functional theory calculations at different scales. Further vibrational and structural analyses verify that the same conclusions can be deduced with density functional theory level in terms of the reasoning of the thermal expansion behavior, and the negative thermal expansion behavior is associated with long-range out-of-plane phonon vibrations. Thus, it is argued that the enabled larger system sizes by machine learning potentials may even enhance the accuracy compared to small-size-limited ab initio molecular dynamics.

Abstract: Direct conversion of CH4 and CO2 to liquid fuels and chemicals under mild conditions is appealing for biogas conversion and utilization but challenging due to the inert nature of both gases. Herein, we report a promising plasma process for the catalyst-free single-step conversion of CH4 and CO2 into higher value oxygenates (i.e., methanol, acetic acid, ethanol, and acetone) at ambient pressure and room temperature using a water-cooled dielectric barrier discharge (DBD) reactor, with methanol being the main liquid product. The distribution of liquid products could be tailored by tuning the discharge power, reaction temperature and residence time. Lower discharge powers (10–15 W) and reaction temperatures (5–20 ◦ C) were favourable for the production of liquid products, achieving the highest methanol selectivity of 43% at 5 ◦ C and 15 W. A higher discharge power and reaction temperature, on the other hand, produced more gaseous products, particularly H2 (up to 26% selec­tivity) and CO (up to 33% selectivity). In addition, varying these process parameters (discharge power, reaction temperature and residence time) resulted in a simultaneous change in key discharge properties, such as mean electron energy (Ee), electron density (ne) and specific energy input (SEI), all of which are essential determiners of plasma chemical reactions. According to the results of artificial neural network (ANN) models, the relative importance of these process parameters and key discharge indicators on reaction performance follows the order: discharge power > reaction temperature > residence time, and SEI > ne > Ee, respectively. This work provides new insights into the contributions and tuning mechanism of multiple parameters for optimizing the reaction performance (e.g., liquid production) in the plasma gas conversion process.

Abstract: Dirac plasmons in graphene are very sensitive to the dielectric properties of the environment. We show that this can be used to probe the structure and composition of van der Waals heterostructures (vdWh) put underneath a single graphene layer. In order to do so, we assess vdWh composed of hexagonal boron nitride and different types of transition metal dichalcogenides (TMDs). By performing realistic simulations that account for the contribution of each layer of the vdWh separately and including the importance of the substrate phonons, we show that one can achieve single-layer resolution by investigating the nonlocal nature of the Dirac plasmon-polaritons. The composition of the vdWh stack can be inferred from the plasmon-phonon coupling once it is composed by more than two TMD layers. Furthermore, we show that the bulk character of TMD stacks for plasmonic screening properties in the terahertz regime is reached only beyond 100 layers.

Abstract: Digital disconnection has emerged as a concept describing the actions people take to limit their digital connectivity to enhance their well-being. To date, evidence on its effectiveness is mixed, leading to calls for greater consideration of why, how, when, and for whom digital disconnection works. This article responds to these calls, presenting a framework that differentiates four key harms that contribute to experiences of digital ill-being (time displacement, interference, role blurring, and exposure effects). Using these four harms as a starting point, the framework explains: (1) why people are motivated to digitally disconnect; (2) how specific disconnection strategies (i.e., placing limits on time, access, channels, and contents, interactions and features) may help them; and for whom (3) and under which conditions (when) these strategies can be effective.

Abstract: Diffusive properties of a monodisperse system of interacting particles confined to a quasi-one-dimensional channel are studied using molecular dynamics simulations. We calculate numerically the mean-squared displacement (MSD) and investigate the influence of the width of the channel (or the strength of the confinement potential) on diffusion in finite-size channels of different shapes (i.e., straight and circular). The transition from single-file diffusion to the two-dimensional diffusion regime is investigated. This transition [ regarding the calculation of the scaling exponent (alpha) of the MSD <Delta x(2)(t)> proportional to t(alpha)] as a function of the width of the channel is shown to change depending on the channel's confinement profile. In particular, the transition can be either smooth (i.e., for a parabolic confinement potential) or rather sharp (i.e., for a hard-wall potential), as distinct from infinite channels where this transition is abrupt. This result can be explained by qualitatively different distributions of the particle density for the different confinement potentials.

Abstract: Difficulties in the production of lignin from rice straw because of high silica content in the recovered lignin reduce its recovery yield and applications as bio-fuel and aromatic chemicals. Therefore, the objective of this study is to develop a novel method to reduce the silica content in lignin from rice straw more effectively and selectively. The method is established by monitoring the precipitation behavior as well as the chemical structure of precipitate by single-stage acidification at different pH values of black liquor collected from the alkaline treatment of rice straw. The result illustrates the significant influence of pH on the physical and chemical properties of the precipitate and the supernatant. The simple two-step acidification of the black liquor at pilot-scale by sulfuric acid 20w/v% is applied to recover lignin at pH 9 and pH 3 and gives a percentage of silica removal as high as 94.38%. Following the developed process, the high-quality lignin could be produced from abundant rice straw at the industrial-scale.