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While microplastic analysis in aquatic systems is rather well standardized, the determination of microplastics in terrestrial samples has been less explored. Here, we review methods for microplastic analysis, with focus on sampling location and design, soil quantity, sampling depth and equipment, and sample handling and preservation. We found that the random sampling design can be used to collect a representative sample. Stainless steel shovels or soil augers were the most common tools for collecting topsoil, from 0 to 30 cm. Deep soil samples, of more than 100 cm depth, can only be obtained using a core drill. The number of soil samples collected in the field depends on the available budget and instruments for microplastic analysis. For example, if a micro-Fourier transform infrared microscope is used for analysis, soil samples as small as 15.0 g per point can be collected. Once the soils are collected, they can be stored in non-plastic containers, e.g., aluminum bags, to reduce contamination. [ABSTRACT FROM AUTHOR]

Accessory minerals in granitic rocks are unlikely significant radionuclide contributions to groundwater due to their remarkable durability. However, accessory minerals incorporating U and Th may suffer structural damages due to the radioactivity and become highly susceptible to alteration. This study investigates geochemistry coupled with textural analysis of the U–Th bearing accessory minerals using a field emission scanning electron microscope and an electron probe micro-analyzer. Altered zircons with numerous open structures related to the radioactive decay show higher contents of U and Th and low analytical totals. Some thorites show high contents of U and non-formula elements due to the hydrothermal alteration in the metamicted thorite. The cerianite including U occurs as micro-veinlet in fracture with trace of Fe and Mn oxides, which indicates secondary phase formation from the decomposed accessory minerals in an oxidizing environment. Some accessory minerals with the high content of U and Th have been found in Mesozoic granite terrain in South Korea, where high concentration levels of radionuclide in groundwater were also reported. The leaching of U may be more likely when the accessory minerals are highly metamicted or altered as found in our samples. The altered zircon and thorite of the study area could be major carriers of radioelement in Mesozoic granitic aquifers where the occurrence of soluble U-minerals has not been reported. [Display omitted] • High radionuclides concentration in groundwater poses a threat to human health. • Accessary minerals can enrich groundwater with radionuclides in granite aquifers. • Altered zircons contain high U and Th levels with open structures. • Thorites show elevated U levels and non-formula elements due to alteration. • Metamicted and/or altered accessory minerals increase uranium leaching potential. [ABSTRACT FROM AUTHOR]

[Display omitted] • Groundwater Deficit (GWD) highlights delayed response to precipitation decline. • GWD characterizes and quantifies groundwater drought, including spatial extent. • GWD identifies thirteen drought events over a two-decade span in South Korea. Although South Korea is frequently subjected to monsoons, the shortage of summer monsoons and relatively dry spring and winter seasons cause droughts in the Korean Peninsula. Since the late 1960s, severe droughts in South Korea have encouraged extensive groundwater development for agricultural and economic growth. Therefore, identifying and estimating the impact of droughts on the country's groundwater resources is crucial for establishing policies and regulations on groundwater exploitation and recharge. Current drought management of the country relies on a meteorological drought index. However, these estimates lack a comprehensive understanding of absolute drought severity and propagation. This study aims to develop a quantitative method for calculating the frequency and severity of groundwater droughts based on the Groundwater Deficit (GWD) derived from NASA's Gravity Recovery and Climate Experiment (GRACE) mission data. The estimated annual GWD in mass over the country ranges from -0.07 km3 to 0.04 km3, with a trend in the mass of -1.60×10−3 km3/year from 2002 to 2021. Thirteen groundwater drought events were identified based on GWD. Among those, the highest drought severities recorded in 2015 and 2019 were -34.27 km3 months and -55.38 km3 months, respectively. Monthly deficits define the quantity of water required to restore normal groundwater storage conditions. Hence, the minimum and average days to recover from groundwater droughts were estimated based on the strength of the storage-based approaches. The GWD approach aligns with meteorological drought databases with a time lag. It illustrates the transition from meteorological drought to groundwater drought, along with their onset, cessation, propagation, instantaneous severity, and peak magnitude. [ABSTRACT FROM AUTHOR]

Hydrogen storage is indeed fundamental to utilizing H 2 effectively, and porous carbon materials have emerged as highly promising supports for this purpose. γ-Graphyne (γGy) possesses abundant chemical bonds, considerable porosity, and exceptional chemical stability, positioning it as a promising candidate for hydrogen storage and transport applications. In this study, we conducted density functional theory calculations to investigate the potential of Li- and Na-loaded γGy as hydrogen storage materials. Our findings reveal that the hydrogen storage capacity (HSC) of Na-loaded γGy falls significantly short of expectations, whereas Li-loaded γGy demonstrates a notably higher HSC. Subsequently, our calculations indicate that B-doping of γGy does not promote favorable HSC, whereas N-doping exhibits a beneficial effect. Furthermore, we observed that tensile strain favors the hydrogen storage properties of 4Li@γGy and 4Li@N-γGy, while compressive strain enhances the hydrogen storage characteristics of 4Li@B-γGy. Notably, we discovered the capacity to adjust the valence band center of Li (ɛ VB), consequently influencing the hydrogen storage performance of γGy. Our investigation suggests that increased overlap between ɛ VB in Li-loaded graphyne and the effective alignment of H 2 and the supporting structure augments the binding force between Li and H 2 , thereby amplifying the HSC. [Display omitted] • Li-loaded γ-Graphyne stores H 2 via Valence-like interaction. • B- and N-doping can enhance storage capacity of Li-loaded γ-Graphyne. • Valence band center of Li tuned by strain achieve efficient adsorption-desorption. [ABSTRACT FROM AUTHOR]

Graphdiyne (GDY) is a 2D carbon allotrope that has become increasingly prevalent among the family of carbon materials. GDY has advantages of high specific surface area and unique sp‐ and sp2‐hybridized carbon atom networks, is endowed with naturally adjustable bandgap, uniformly nanoporous structure, rapid carrier mobility activated by inhomogeneous π orbitals, and accessible on/off rations. These advantages, coupled with the direct binding ability of metal atoms resulting from sp‐hybridization, enable GDY to be applied across various research fields, especially as a substrate to support and further improve the performances of metals and metal compounds. Though many studies have considered the applications of GDY‐supported metals and metal compounds, a comprehensive introduction of synthesis and applications is deficient. Nonetheless, a discussion considering these diverse studies is essential to attract the attention of researchers and promote the development of new perspectives. In this review, a basic understanding of GDY and a thorough introduction to the synthesis and applications of GDY‐supported metals and metal compounds are presented. The review considers nanoparticles, nanoclusters, and dual and single atoms, and concurrently catalogues these in specific application domains. Moreover, future challenges and the development potentials of GDY‐supported materials are discussed to provide different perspectives and ideas. [ABSTRACT FROM AUTHOR]

B 4 C 12 achieves a rapid and stable CO 2 adsorption with a novel η3(O, C, O)-CO 2 configuration, and a small limiting potential for CO2RR producing HCOOH associating with suppressed HER. [Display omitted] The electrochemical reduction of CO 2 (CO2RR) to formic acid (HCOOH) is a promising approach to harness renewable energy for the production of value-added chemicals and contribute to carbon cycling. The search for cost-effective and efficient metal-free electrocatalysts is critical for realizing industrial applications. However, limited literature is available on this topic, primarily because the significant challenge of efficiently activating inert CO 2 remains unresolved. In this study, we have designed and applied a novel boron carbide (B 4 C 12) monolayered cage as an electrocatalyst for CO2RR to produce HCOOH. B 4 C 12 exhibits exceptional electronic, dynamic, and thermodynamic stability. Through comprehensive density functional theory computations, we have observed that B 4 C 12 rapidly and stably adsorbs CO 2 in a unique η3(O, C, O)-CO 2 configuration, resulting in excellent CO2RR activity with a low limiting potential (–0.38 V) and suppressed hydrogen evolution reaction. Our mechanistic investigations reveal that B 4 C 12 donates electrons to facilitate the bending of CO 2 , anchoring it onto the curved surface effectively. Additionally, the C atom in the η3(O, C, O)-CO 2 configuration attracts H+ + e− pairs through its active p electron, leading to the observed low limiting potential. This study not only successfully designs a novel class of metal-free electrocatalysts but also provides a promising strategy for advancing CO2RR research in the future. [ABSTRACT FROM AUTHOR]

Aptamers are increasingly recognized as potent alternatives to antibodies for diagnostic and therapeutic applications. The application of deep learning, particularly attention-based models, for aptamer (DNA/RNA) sequences is an innovative field. The ongoing advancements in aptamer sequencing technologies coupled with machine learning algorithms have resulted in novel developments. Further research is required to investigate the full potential of deep learning models and address the challenges associated with the generation of sequences, like the large search space of possible sequences. In this study, we propose a workflow that integrates an attention mechanism within a framework of a generative variational autoencoder, to generate novel sequences by expanding latent memory. They show 100 % novelty compared with the dataset, and approximately 88 % of them show negative values for the minimum free energy, which may indicate the likelihood of an RNA sequence folding into a functional structure. Because the field of aptamer discovery is affected by data scarcity, advanced strategies that facilitate the generation of diverse and superior sequences are necessitated. The utilization of our workflow can result in novel aptamers. Thus, investigations such as the present study can address the abovementioned challenge. Our research is anticipated to facilitate further discoveries and advancements in aptamer fields. • We leverage attention-based variational autoencoders for the generation of novel aptamer sequences. • The application of deep learning, particularly attention-based models, for aptamers is an innovative and emerging field. • The field of aptamer (DNA/RNA) discovery is affected by data scarcity, so strategies for generation of diverse sequences are necessitated. [ABSTRACT FROM AUTHOR]

Aptamers are increasingly recognized as potent alternatives to antibodies for diagnostic and therapeutic applications. The application of deep learning, particularly attention-based models, for aptamer (DNA/RNA) sequences is an innovative field. The ongoing advancements in aptamer sequencing technologies coupled with machine learning algorithms have resulted in novel developments. Further research is required to investigate the full potential of deep learning models and address the challenges associated with the generation of sequences, like the large search space of possible sequences. In this study, we propose a workflow that integrates an attention mechanism within a framework of a generative variational autoencoder, to generate novel sequences by expanding latent memory. They show 100 % novelty compared with the dataset, and approximately 88 % of them show negative values for the minimum free energy, which may indicate the likelihood of an RNA sequence folding into a functional structure. Because the field of aptamer discovery is affected by data scarcity, advanced strategies that facilitate the generation of diverse and superior sequences are necessitated. The utilization of our workflow can result in novel aptamers. Thus, investigations such as the present study can address the abovementioned challenge. Our research is anticipated to facilitate further discoveries and advancements in aptamer fields. • We leverage attention-based variational autoencoders for the generation of novel aptamer sequences. • The application of deep learning, particularly attention-based models, for aptamers is an innovative and emerging field. • The field of aptamer (DNA/RNA) discovery is affected by data scarcity, so strategies for generation of diverse sequences are necessitated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Optimal flow process can maximize the denitrification capacity of riparian zones downstream of reservoirs. • Denitrification is reaction- instead of transport-limited when the hydrograph wave amplitude/duration ratio is high. • Riparian nitrogen removal has a strongly positive correlation to return/infiltration time ratio of solutes. Flood waves generated by reservoir discharge play a crucial role in the potential for riparian denitrification downstream. The efficiency of nitrogen (N) removal from river water by riparian zones is typically enhanced with greater wave amplitude (A) and duration (T). However, a knowledge gap exists with respect to the impact of flood waves on N removal when considering a fixed-value integral over time of flood waves (IOFW). This study explored N transport and transformation in the riparian zone downstream of the dammed Inbuk River, Korea under various wave conditions with a fixed IOFW. The results revealed a logarithmic enhancement in solute infiltration into the riverbank with an increasing wave amplitude/duration ratio (A / T ratio). The solute residence time within the riparian zone displays an initial increase followed by a decrease with the increment in the A/T ratio. We identified a threshold for the wave A/T ratio that maximizes riverine N removal by the riparian zone, a phenomenon observed across various dammed rivers. Our findings indicated that riparian denitrification is reaction time-limited when the wave A/T ratio exceeds the threshold; contrarily, it becomes transport capacity-limited. Additionally, we observed a significant relationship between the net nitrate removal and the return/infiltration time ratio of water (r2 = 0.93, p < 0.05). The research results contribute to a better understanding of the impact of water level fluctuations on the N cycle in riparian zones, and provide valuable insights for developing sustainable reservoir operation strategies. [ABSTRACT FROM AUTHOR]

• Graphyne nanotubes with sp-B doping showed excellent catalytic activity for nitrogen reduction reaction. • Δ G *NNH has a good volcano relationship with the limiting potential. • Curvature effect induces the synergistic effect of p-orbital and positive charge enhancement on sp-B dopants to enhance N 2 fixation. Developing novel, metal-free materials as efficient catalysts for the electrochemical nitrogen reduction reaction (NRR) to replace the Haber-Bosch process remains a significant challenge. Herein, γ-graphyne nanotubes (γGyNTs) doped with single sp2-B or sp-B were developed as electrocatalysts. The NRR activity of the doped γGyNTs was studied by intensive density functional theory (DFT) calculations. The results reveal that the curvature effect significantly enhances the catalytic activity of sp-B-doped γGyNTs, in contrast with that achieved via sp2-B doping. The limiting potential of sp-B-doped (2, 0)-γGyNT is predicted to be −0.071 V, which is significantly superior to that of previously reported metal-free catalysts (MFCs). Moreover, the competing hydrogen evolution reaction (HER) is suppressed by sp-B-doped (2, 0)-γGyNT. Analysis of the catalytic mechanism revealed that the enhanced NRR activity of the sp-B doped γGyNTs mainly originates from the synergistic effects of the enhanced exposure of the p-orbital and positive charge on the sp-B dopants induced by the curvature effect, which can alter the interactions with intermediates. The present findings are insightful and suggest a new strategy for designing graphyne-related materials as high-performance non-metallic NRR catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]