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The sorption properties of TiO nanoparticles (NPs) on sand were investigated in the presence of Suwannee River humic acid (SRHA) as a surrogate for natural organic matter. SRHA drastically reduced the sorption preference regardless of the initial pH and ionic strength of the solution. Despite the higher SRHA loading onto sand versus the TiO NPs, the consequent zeta ( ζ)-potential drop was more significant in the TiO NPs, indicating that the decreased sorption should be primarily ascribed to the fraction of SRHA sorbed onto the TiO NP surfaces. The hindering effect of SRHA on the sorption increased with SRHA concentration, but stabilized at the concentration equivalent to full surface coverage of the TiO NPs and sand in the reaction system. Interaction force measurements indicated that SRHA inhibits the approach of the TiO NPs to the sand surface, as expected by the Derjaguin-Landau-Verwey-Overbeek calculation. However, the adhesion force of TiO NPs to sand was not critically affected by the presence of SRHA. TiO NP sorption to natural sand was limited as to the acid-treated sand in the presence of SRHA, implying that the organics dissolved from natural sand might facilitate the transport of TiO NPs in aquifers by inhibiting TiO NP sorption to aquifer materials. [ABSTRACT FROM AUTHOR]

The ultimate goal of our study is to establish thin-layer chromatography (TLC) as a quick and simple method for identifying the type of refined petroleum products present in the environmental media. As a preliminary step, TLC chromatograms of different petroleum products, including gasoline, kerosene, and diesel, were characterized and compared. Methanol was determined as the optimum carrier solution in TLC analysis. The spherical-shaped TLC chromatogram of gasoline showed the longest migration distance, and thus the highest retardation factor ( R ) of 0.91. This was followed by that of kerosene (0.63) with an elliptical-shaped, and diesel (0.24) with an elongated trapezoid-shaped chromatogram. R of kerosene and diesel increased with the dilution factor, while gasoline showed a constant value. Additionally, it was observed that the TLC chromatograms of oils produced the same peak pattern with the corresponding petroleum products in gas chromatography (GC). A mixed sample of kerosene and diesel presented a triangular shaped chromatogram, underlining the need to consider the shape of chromatogram in addition to the R value, as an indicator of the petroleum type. The findings indicate that TLC has a huge potential to be used as a quick and reliable method for identifying the type of refined petroleum products in the environmental media. [ABSTRACT FROM AUTHOR]

• Variable-density flow controls the coupling between pressure and concentration data. • The coupling effect is formally quantified by the analysis of mutual information. • We analyze the value-of-information of joint pressure-concentration inversion. • The advantage of joint inversion decreases as the coupling effect increases. • The amount of shared information decreases as permeability heterogeneity increases. Predicting variable-density flow and transport in aquifers is critical for the management of many coastal saline aquifers. Accurate characterization of hydrogeological parameters is critical for prediction, and the characterization is often conducted by assimilating data into models. However, few studies have investigated the underlying physics controlling the value-of-information (VOI) of data for aquifer characterization. In this study, we show how a greater understanding of the underlying physics controlling pressure and concentration data coupling can lead to improved characterization. In variable-density flow, the key physics that controls the VOI of pressure and concentration data is the non-linear coupling between flow and transport via fluid density which causes the pressure field to experience transient changes according to the evolution of salinity distribution. We first demonstrate the coupling between pressure and concentration data using information theory, and then systematically investigate how the variable-density flow impacts the VOI of these data in relation to permeability estimation. Using an ensemble Kalman filter, we estimate the permeability field of saline aquifer systems in two scenarios of data usage: pressure data only, and pressure and concentration data jointly. This study demonstrates that, regardless of the data usage scenario, the maximum VOI of data is obtained when free convection and forced convection are balanced. We further show that the advantage of joint inversion of pressure and concentration data decreases as the coupling effect between flow and transport increases. Finally, we study how the level of permeability field heterogeneity affects the coupling, which in turn controls VOI of pressure and concentration data. [ABSTRACT FROM AUTHOR]

[Display omitted] • The homogeneous coating layer is formed using electrostatic force of the polymer. • Li 3 VO 4 -coated LiNi 0.5 Mn 1.5 O 4 are synthesized simultaneously by a single calcination step. • Nanoscale Li 3 VO 4 coating improves the LiNi 0.5 Mn 1.5 O 4 performance. • Li 3 VO 4 coating layer increases Li-ion access and conductivity. • Li 3 VO 4 layer effectively suppresses side reactions at elevated temperatures. One of the most promising high voltage cathode materials for application in lithium ion batteries (LIBs), the 5 V spinel LiNi 0.5 Mn 1.5 O 4 , faces electrode/electrolyte decomposition at high voltage, rendering commercial application difficult. To overcome these obstacles, this study proposes a method for adsorbing vanadium anion complexes on the surface of Ni 0.25 Mn 0.75 (OH) 2 using cationic polymers and calcination them with LiOH to form LiNi 0.5 Mn 1.5 O 4 with a uniform nano-Li 3 VO 4 coating layer. The uniform nano-Li 3 VO 4 coating layer prepared by the above method promotes transfer of lithium ions and protects active material from electrolyte corrosion, thereby obtaining a particularly stable electrochemical performance under severe operating conditions such as high temperatures. Electrochemical tests show that the Li 3 VO 4 -coated LiNi 0.5 Mn 1.5 O 4 demonstrates a high discharge capacity and at the cycling test after storage test at 60 °C, the Li 3 VO 4 -coated LiNi 0.5 Mn 1.5 O 4 shows higher capacity retention than pristine LiNi 0.5 Mn 1.5 O 4 ; this can be attributed to the coating that acts as a protective layer. [ABSTRACT FROM AUTHOR]

The anomalous (i.e., non-Fickian) transport characteristics (e.g., early arrival/long tailing and other non-Gaussian plume properties) make it challenging to apply classical transport theories to the transport and retention of microplastics in soil due to their heterogeneity. This overview attempts 1) to delineate the previous studies on the transport of colloids and MPs, which used the recently developed analytical devices (e.g., microfluidics and micro-CT) and process-based (e.g., lattice Boltzmann method (LBM) and pore network modeling (PNM)) or data-driven models (e.g., machine learning (ML) techniques) and 2) to provide future directions for bridging the pore- and continuum-scale properties. Although the LBM and PNM offer significant advantages in depicting particle transport at the pore scale, their employment at larger scales is hindered by computational demands. Nonetheless, applying these methods to generate datasets for ML techniques is anticipated to provide a robust tool for an accurate and rapid continuum-scale microplastics transport model. [Display omitted] • We outlined recent particle transport studies for various scales and model types. • Recent advancements enabled microscopic observations and simulations. • Machine learning enhanced the prediction performance for particle transport models. • A multiscale, hybrid model could overcome the limitations of the individual model. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pilot-scale simulated ASR system injecting river water was stably operated. • Seasonal variations in organics and soil microbiome were evaluated for one year. • Organic compounds in soil and effluent water were maintained for long-term periods. • Soil microbial communities were shifted with process operation and sample location. • Diverse soil microbes degraded the organics during the ASR storage period. Soil microbiome is responsible for crucial biochemical reactions by interacting with organic compounds in the injection wells in aquifer storage and recovery (ASR) processes. This study investigated seasonal variations in organic compounds and microbial communities in a simulated ASR system. For this purpose, eleven pilot-scale soil columns were operated in ASR mode over 13 months. River water was intermittently fed into the simulated ASR system after sedimentation pretreatment. As a result, the sand ratios in soil texture were slightly increased from 93.2-93.4 % to 96.6–98.1 % while the total organic carbon content in the soil was accumulated and maintained at < 0.2 % during the ASR operation. During the sedimentation process, 9–31 % of dissolved organic carbon (DOC) was removed in the water, while during the storage in the soil column, the DOC in water was fluctuated. However, the DOC concentration (less than 4 mg/L) in the effluent was stably maintained until the end of operational periods. High-throughput sequencing results showed that the predominant phylum was Proteobacteria. Interestingly, at the species level, the microbial community structure clearly shifted with elapsed time and column location; various organic degrading soil microbiome having different physiological characteristics (e.g., oxygen, substrate, and temperature) became predominant. Outcomes of this study suggest that soil microbiome can facilitate the establishment of stable ASR processes for river water treatment by contributing to bioattenuation. [ABSTRACT FROM AUTHOR]

Evaluating and predicting the natural attenuation capacity (AC) of a vadose zone is essential for determining groundwater vulnerability to contamination from upper sources. However, it remains unclear how the physicochemical properties of vadose zone soils affect AC owing to their complexity and spatial heterogeneity. In this study, we developed a regression model for estimating the AC of a vadose zone against diesel using datasets from different soils with a wide range of physicochemical properties. Among the 17 properties, six (i.e., organic matter (OM), total phosphorous (TP), coefficient of uniformity, particle size (D 30), van Genuchten's n, saturation degree (SD)) were selected as primary regressors. The results indicate that biogeochemical factors, including OM and TP, have decisive effects on the AC. Finally, the regression model was expanded to a GIS-based spatial model and applied to Namyangju, Korea using the index-overlay method. The produced AC map showed a nonmonotonic decrease along the depth, and the areas closer to the water bodies generally represented low AC values, most likely due to the lower OM, TP, and higher SD. This study provides an empirical basis for future research initiatives for spatial and temporal AC dynamics, which complements conventional intrinsic groundwater vulnerability models such as DRASTIC. [Display omitted] • Diesel attenuation capacity (AC) was predicted from multiple linear regression. • Biogeochemical factors have decisive effects on the AC. • AC prediction was expanded to the spatial model using the overlay-index method. • Produced AC map showed a non-monotonic decrease along the depth. • Areas closer to the water bodies generally represented low AC values. [ABSTRACT FROM AUTHOR]

Arsenic (As) is a widespread environmental contaminant that poses a significant threat to ecosystems and human health. Although previous studies have qualitatively revealed the effects of individual soil properties on the transport and fate of As in the vadose zone, their integrated impacts remain obscure. Moreover, studies investigating the retardation factor therein, which is a key parameter for comprehending As transport in the vadose zone, are extremely limited. In this study, we investigated the interplay of soil properties with As transport and retention within the vadose zone, while focusing on the retardation factor of As. We employed steady-state unsaturated water-flow soil column experiments coupled with a mobile–immobile model and multiple linear regression analysis to elucidate the dependence of As retardation factors on the soil properties. In the mobile water zone, iron and organic matter contents emerged as the two most influential properties that impedes As mobility. Whereas, in the immobile water zone, the coefficient of uniformity and bulk density were the most influential factors that enhanced As retention. Finally, we derived an empirical equation for calculating the As retardation factors in each zone, offering a valuable tool for describing and predicting As behavior to protect the groundwater resources underneath. [Display omitted] • Dual-porosity characteristics resulted in anomalous transport of As in vadose zone. • Typical soil properties were used to estimate the As retardation in vadose zone. • Iron and organic matter contents were the major factors in the mobile water zone. • Uniformity coefficient and bulk density were the key factors in the immobile water. [ABSTRACT FROM AUTHOR]

• Gliomas grading is performed with MRI and is important for treatment and prognosis. • A robust network to handle missing MRI modalities is proposed. • Our network outperformed existing methods. Gliomas are graded using multimodal magnetic resonance imaging, which provides important information for treatment and prognosis. When modalities are missing, the grading is degraded. We propose a robust brain tumor grading model that can handle missing modalities. Our method was developed and tested on Brain Tumor Segmentation Challenge 2017 dataset (n = 285) via nested five-fold cross-validation. Our method adopts adversarial learning to generate the features of missing modalities relative to the features obtained from a full set of modalities in the latent space. An attention-based fusion block across modalities fuses the features of each available modality into a shared representation. Our method's results are compared to those of two other models where 15 missing-modality scenarios are explicitly considered and a joint training approach with random dropouts is used. Our method outperforms the two competing methods in classifying high-grade gliomas (HGGs) and low-grade gliomas (LGGs), achieving an area under the curve of 87.76% on average for all missing-modality scenarios. The activation maps derived with our method confirm that it focuses on the enhancing portion of the tumor in HGGs and on the edema and non-enhancing portions of the tumor in LGGs, which is consistent with prior expertise. An ablation study shows the added benefits of a fusion block and adversarial learning for handling missing modalities. Our method shows robust grading of gliomas in all cases of missing modalities. Our proposed network might have positive implications in glioma care by learning features robust to missing modalities. [ABSTRACT FROM AUTHOR]

In natural environments, the fate and migratory behavior of metalloid contaminants such as antimony (Sb) significantly depend on the interfacial reactivity of mineral surfaces. Although boehmite (γ-AlOOH) is widely observed in (sub)surface environments, its underlying interaction mechanism with Sb oxyanions at the molecular scale remains unclear. Considering Sb-contaminated environmental conditions in this study, we prepared boehmite under weakly acidic conditions for use in the systematic investigation of interfacial interactions with Sb(III) and Sb(V). The as-synthesized boehmite showed a nanorod morphology and comprised four crystal facets in the following order: 48.4% (010), 27.1% (101), 15.0% (001), and 9.5% (100). The combined results of spectroscopic analyses and theoretical calculations revealed that Sb(III) formed hydrogen bonding outer-sphere complexation on the (100), (010), and (001) facets and that Sb(V) preferred to form bidentate inner-sphere complexation via mononuclear edge-sharing configuration on the (100), (001), and (101) facets and binuclear corner-sharing configuration on the (010) facet. These findings indicate that the facet-mediated thermodynamic stability of the surface complexation determines the interaction affinity toward the Sb species. This work is the first to document the contribution of boehmite to (sub)surface media, improving the ability to forecast the fate and behavior of Sb oxyanions at mineral–water interfaces. [Display omitted] • Interfacial interaction between boehmite nanorods (BNRs) and Sb(III/V) was studied. • XAS and DFT analyses show a molecular-scale interaction mechanism. • Affinity of BNRs was determined by energy-based geometric structures of Sb(III/V). • The (100), (010), and (001) facets preferred to form hydrogen bonding for Sb(III). • Four facets were functional to form a bidentate inner-sphere complex for Sb(V). [ABSTRACT FROM AUTHOR]