Efficient photoanode with a MoS2/TiO2/Au nanoparticle heterostructure for ultraviolet-visible photoelectrocatalysis.

Green energy technology is generally becoming one of hot issues that need to be solved due to the adverse effects on the environment of fossil fuels. One of the strategies being studied and developed by theorists and experimentalists is the use of photoelectrochemical (PEC) cells, which are emerging as a candidate to produce hydrogen from water splitting. However, creating photoelectrodes that meet the requirements for PEC water splitting has emerged as the primary obstacle in bringing this technology to commercial fruition. Here, we construct a heterostructure, which consists of MoS2/TiO2/Au nanoparticles (NPs) to overcome the drawbacks of the photoanode. Owing to the dependence on charge transfer, the bandgap of MoS2/TiO2and the utilization the Au NPs as a stimulant for charges separation of TiO2by localized surface plasmon resonances effect as well as the increase of hot electron injection to cathode, leading to photocatalytic activities are improved. The results have recorded a significant increase in the photocurrent density from 2.3µAcm-2of TiO2to approximately 16.3µAcm-2of MoS2/TiO2/Au NPs. This work unveils a promising route to enhance the visible light adsorption and charge transfer in photo-electrode of the PEC cells by combining two-dimensional materials with metal NPs.

Morphology Control of Au-Ni Hybrid Nanoparticles: Exploring Heterostructures and Optical Tuning.

Hybrid nanoparticles (NPs) have attracted considerable attention because of their ability to provide diverse properties by integrating the inherent properties of multiple components; however, synthetic strategies to control their morphology remain unexplored. In this study, a new method was used to control the morphology and optical properties of Au-Ni heterostructure (ANH) NPs. Unique morphological changes were observed by varying the Au/Ni precursor ratio from 2:1 to 1:4, exhibiting a shape transformation from dumbbell-like to quasi-spherical owing to the Ni NP size expansion, whereas the Au NP maintained their size. Moreover, increasing the Ni ratio induced plasmonic band broadening and wavelength redshift, resulting in color changes from red to navy and black. In terms of the structure, the atomic orientation of the crystallite showed that even a large lattice mismatch can result in heterojunctions at the NPs. In addition, the reaction aliquots uncovered heterogeneous nucleation and growth of ANH NPs in the colloidal system, demonstrating Ni reduction on the preformed Au NP owing to the reduction in potential gap. This study provides new insights into controlling the morphology of hybrid NPs using colloidal synthesis and the design of optimized materials for various applications.

Multi-Functional PEDOT:PSS as the Efficient Perovskite Solar Cells.

Poly(3,4-ethylenedioxythiophene) (PEDOT), particularly in its complex form with poly(styrene sulfonate) (PEDOT:PSS), stands out as a prominent example of an organic conductor. Renowned for its exceptional conductivity, substantial light transmissibility, water processability, and remarkable flexibility, PEDOT:PSS has earned its reputation as a leading conductive polymer. This study explores the unique effects of two additives, Bisphenol A diglycidyl ether (DGEBA) and Dimethyl sulfoxide (DMSO), on the PSS component of PEDOT:PSS films are shown. Both additives induce grain size growth, while DGEBA makes the PEDOT:PSS layer hydrophobic, which acts as a passivation to protect the perovskite layer, which is vulnerable to moisture. The other additive, DMSO, separates the PSS groups, resulting in increased conductivity through the free movement of holes. With these multi-modified p-type PEDOT:PSS, the ITO/M-PEDOT:PSS/Perovskite/PCBM/Ag structured reverse structure solar cell has improved the power conversion efficiency (PCE) from 15.28% to 17.80% compared to the control cell with conventional PEDOT:PSS. It also maintains 90% for 500 h at 60 °C and 300 h at 1 sun illuminating conditions.

Transcriptome Profiling of a Soybean Mutant with Salt Tolerance Induced by Gamma-ray Irradiation.

Salt stress is a significant abiotic stress that reduces crop yield and quality globally. In this study, we utilized RNA sequencing (RNA-Seq) to identify differentially expressed genes (DEGs) in response to salt stress induced by gamma-ray irradiation in a salt-tolerant soybean mutant. The total RNA library samples were obtained from the salt-sensitive soybean cultivar Kwangan and the salt-tolerant mutant KA-1285. Samples were taken at three time points (0, 24, and 72 h) from two tissues (leaves and roots) under 200 mM NaCl. A total of 967,719,358 clean reads were generated using the Illumina NovaSeq 6000 platform, and 94.48% of these reads were mapped to 56,044 gene models of the soybean reference genome (Glycine_max_Wm82.a2.v1). The DEGs with expression values were compared at each time point within each tissue between the two soybeans. As a result, 296 DEGs were identified in the leaves, while 170 DEGs were identified in the roots. In the case of the leaves, eight DEGs were related to the phenylpropanoid biosynthesis pathway; however, in the roots, Glyma.03G171700 within GmSalt3, a major QTL associated with salt tolerance in soybean plants, was differentially expressed. Overall, these differences may explain the mechanisms through which mutants exhibit enhanced tolerance to salt stress, and they may provide a basic understanding of salt tolerance in soybean plants.

Modeling Henry's law and phase separations of water-NaCl-organic mixtures with solvation and ion-pairing.

Empirical measurements of solution vapor pressure of ternary acetonitrile (MeCN) H2O-NaCl-MeCN mixtures were recorded, with NaCl concentrations ranging from zero to the saturation limit, and MeCN concentrations ranging from zero to an absolute mole fraction of 0.64. After accounting for speciation, the variability of the Henry's law coefficient at vapor-liquid equilibrium (VLE) of MeCN ternary mixtures decreased from 107% to 5.1%. Solute speciation was modeled using a mass action solution model that incorporates solute solvation and ion-pairing phenomena. Two empirically determined equilibrium constants corresponding to solute dissociation and ion pairing were utilized for each solute. When speciation effects were considered, the solid-liquid equilibrium of H2O-NaCl-MeCN mixtures appear to be governed by a simple saturation equilibrium constant that is consistent with the binary H2O-NaCl saturation coefficient. Further, our results indicate that the precipitation of NaCl in the MeCN ternary mixtures was not governed by changes in the dielectric constant. Our model indicates that the compositions of the salt-induced liquid-liquid equilibrium (LLE) boundary of the H2O-NaCl-MeCN mixture correspond to the binary plateau activity of MeCN, a range of concentrations over which the activity remains largely invariant in the binary water-MeCN system. Broader comparisons with other ternary miscible organic solvent (MOS) mixtures suggest that salt-induced liquid-liquid equilibrium exists if: (1) the solution displays a positive deviation from the ideal limits governed by Raoult's law; and (2) the minimum of the mixing free energy profile for the binary water-MOS system is organic-rich. This work is one of the first applications of speciation-based solution models to a ternary system, and the first that includes an organic solute.

X-band MMICs for a Low-Cost Radar Transmit/Receive Module in 250 nm GaN HEMT Technology.

This paper describes Monolithic Microwave Integrated Circuits (MMICs) for an X-band radar transceiver front-end implemented in 0.25 µm GaN High Electron Mobility Transistor (HEMT) technology. Two versions of single pole double throw (SPDT) T/R switches are introduced to realize a fully GaN-based transmit/receive module (TRM), each of which achieves an insertion loss of 1.21 dB and 0.66 dB at 9 GHz, IP1dB higher than 46.3 dBm and 44.7 dBm, respectively. Therefore, it can substitute a lossy circulator and limiter used for a conventional GaAs receiver. A driving amplifier (DA), a high-power amplifier (HPA), and a robust low-noise amplifier (LNA) are also designed and verified for a low-cost X-band transmit-receive module (TRM). For the transmitting path, the implemented DA achieves a saturated output power (Psat) of 38.0 dBm and output 1-dB compression (OP1dB) of 25.84 dBm. The HPA reaches a Psat of 43.0 dBm and power-added efficiency (PAE) of 35.6%. For the receiving path, the fabricated LNA measures a small-signal gain of 34.9 dB and a noise figure of 2.56 dB, and it can endure higher than 38 dBm input power in the measurement. The presented GaN MMICs can be useful in implementing a cost-effective TRM for Active Electronically Scanned Array (AESA) radar systems at X-band.

Morpho-physiological and genetic characteristics of a salt-tolerant mutant line in soybean (Glycine max L.).

KEY MESSAGE: One major quantitative trait loci and candidate gene for salt tolerance were identified on chromosome 3 from a new soybean mutant derived from gamma-ray irradiation, which will provide a new genetic resource for improving soybean salt tolerance. Soil salinity is a worldwide problem that reduces crop yields, but the development of salt-tolerant crops can help overcome this challenge. This study was conducted with the purpose of evaluating the morpho-physiological and genetic characteristics of a new salt-tolerant mutant KA-1285 developed using gamma-ray irradiation in soybean (Glycine max L.). The morphological and physiological responses of KA-1285 were compared with salt-sensitive and salt-tolerant genotypes after treatment with 150 mM NaCl for two weeks. In addition, a major salt tolerance quantitative trait locus (QTL) was identified on chromosome 3 in this study using the Daepung X KA-1285 169 F2:3 population, and a specific deletion was identified in Glyma03g171600 (Wm82.a2.v1) near the QTL region based on re-sequencing analysis. A kompetitive allele-specific PCR (KASP) marker was developed based on the deletion of Glyma03g171600 which distinguished the wild-type and mutant alleles. Through the analysis of gene expression patterns, it was confirmed that Glyma03g171700 (Wm82.a2.v1) is a major gene that controls salt tolerance functions in Glyma03g32900 (Wm82.a1.v1). These results suggest that the gamma-ray-induced mutant KA-1285 has the potential to be employed for the development of a salt-tolerant cultivar and provide useful information for genetic research related to salt tolerance in soybeans.

Versatile microbial communities rapidly assimilate ammonium hydroxide-treated plastic waste.

Waste plastic presently accumulates in landfills or the environment. While natural microbial metabolisms can degrade plastic polymers, biodegradation of plastic is very slow. This study demonstrates that chemical deconstruction of polyethylene terephthalate (PET) with ammonium hydroxide can replace the rate limiting step (depolymerization) and by producing plastic-derived terephthalic acid and terephthalic acid monoamide. The deconstructed PET (DCPET) is neutralized with phosphoric acid prior to bioprocessing, resulting in a product containing biologically accessible nitrogen and phosphorus from the process reactants. Three microbial consortia obtained from compost and sediment degraded DCPET in ultrapure water and scavenged river water without addition of nutrients. No statistically significant difference was observed in growth rate compared to communities grown on DCPET in minimal culture medium. The consortia were dominated by Rhodococcus spp., Hydrogenophaga spp., and many lower abundance genera. All taxa were related to species known to degrade aromatic compounds. Microbial consortia are known to confer flexibility in processing diverse substrates. To highlight this, we also demonstrate that two microbial consortia can grow on similarly deconstructed polyesters, polyamides, and polyurethanes in water instead of medium. Our findings suggest that microbial communities may enable flexible bioprocessing of mixed plastic wastes when coupled with chemical deconstruction.

Design and synthesis of metal-free ethene-based covalent organic framework photocatalysts for efficient, selective, and long-term stable CO2 conversion into methane.

The efficient and selective photocatalytic CO2 conversion into higher-valued hydrocarbon products (e.g., methane and ethane) over covalent organic frameworks (COFs) remains a challenge, with all previously reported attempts producing carbon monoxide as the dominant product. Herein, we report a new ethene-based COF, through polycondensation of electron-rich (E)-1,2­diphenylethene and 1,3,6,8­tetraphenylpyrene units. The synthesized ethene-based COF functioned as an efficient metal-free photocatalyst for the conversion of CO2 into methane under visible light irradiation, with a selectivity of 100 %, a production rate of 14.7 µmol g-1h-1, and an apparent quantum yield of c.a. 0.99 % at 489.5 nm, which are the most promising values reported for CO2 conversion by a metal-free COF photocatalyst, without any support from a co-catalyst. The carbon origin of CH4 product is confirmed by isotope tracer 13CO2 experiment. Moreover, the photocatalytic system consistently produces methane for > 14 h with recyclability.

Photocatalytic Carbon Dioxide Conversion by Structurally and Materially Modified Titanium Dioxide Nanostructures.

TiO2 has aroused considerable attentions as a promising photocatalytic material for decades due to its superior material properties in several fields such as energy and environment. However, the main dilemmas are its wide bandgap (3-3.2 eV), that restricts the light absorption in limited light wavelength region, and the comparatively high charge carrier recombination rate of TiO2, is a hurdle for efficient photocatalytic CO2 conversion. To tackle these problems, lots of researches have been implemented relating to structural and material modification to improve their material, optical, and electrical properties for more efficient photocatalytic CO2 conversion. Recent studies illustrate that crystal facet engineering could broaden the performance of the photocatalysts. As same as for nanostructures which have advantages such as improved light absorption, high surface area, directional charge transport, and efficient charge separation. Moreover, strategies such as doping, junction formation, and hydrogenation have resulted in a promoted photocatalytic performance. Such strategies can markedly change the electronic structure that lies behind the enhancement of the solar spectrum harnessing. In this review, we summarize the works that have been carried out for the enhancement of photocatalytic CO2 conversion by material and structural modification of TiO2 and TiO2-based photocatalytic system. Moreover, we discuss several strategies for synthesis and design of TiO2 photocatalysts for efficient CO2 conversion by nanostructure, structure design of photocatalysts, and material modification.

Solvent-driven fractional crystallization for atom-efficient separation of metal salts from permanent magnet leachates.

This work reports a dimethyl ether-driven fractional crystallization process for separating rare earth elements and transition metals. The process has been successfully applied in the treatment of rare earth element-bearing permanent magnet leachates as an atom-efficient, reagent-free separation method. Using ~5 bar pressure, the solvent was dissolved into the aqueous system to displace the contained metal salts as solid precipitates. Treatments at distinct temperatures ranging from 20-31 °C enable crystallization of either lanthanide-rich or transition metal-rich products, with single-stage solute recovery of up to 95.9% and a separation factor as high as 704. Separation factors increase with solution purity, suggesting feasibility for eco-friendly solution treatments in series and parallel to purify aqueous material streams. Staged treatments are demonstrated as capable of further improving the separation factor and purity of crystallized products. Upon completion of a crystallization, the solvent can be recovered with high efficiency at ambient pressure. This separation process involves low energy and reagent requirements and does not contribute to waste generation.

A 90 GHz Broadband Balanced 8-Way Power Amplifier for High Precision FMCW Radar Sensors in 65-nm CMOS.

We present a W-band 8-way wideband power amplifier (PA) for a high precision frequency modulated continuous wave (FMCW) radar in 65-nm CMOS technology. To achieve a broadband operation with an improved output power for a high range resolution and high distance coverage of FMCW radar sensors, a balanced architecture is employed with the Lange coupler which naturally combines the output powers from two 4-way push-pull PAs. By utilizing a transformer-based push-pull structure with a cross-coupled capacitive neutralization technique, the gate-drain capacitance of the 4-way PA is compensated for the stabilization with an improved power gain. Interstage matching was performed with transformers for a reduced loss from the matching network and minimal area occupation. The implemented balanced 8-way PA achieved a saturated output power (Psat) of 16.5 dBm, a 1-dB compressed output power (OP1dB) of 13.3 dBm, a power-added efficiency (PAE) of 9.9% at 90 GHz and 3-dB power bandwidth was 20.4 GHz (79.2-99.6 GHz).

Physiological causes of transplantation shock on rice growth inhibition and delayed heading.

Transplanting is an important rice cultivation method; however, transplanting shock commonly affects grain yield, and the mechanisms underlying the inhibition of growth, development, and delayed heading caused by transplanting shock have not yet been clearly elucidated. Here, we investigated the effects of seedling age, temperature, and root damage during transplanting on growth, development, and time to heading, both under artificially controlled and natural day length. Additionally, we investigated the impact of seedling root growth space and the potential mitigating effects of residual seed nutrients on young transplanted seedlings. The delay in heading in transplanted versus directly seeded plants was affected more by growth inhibition during the seedling period than by root damage during transplanting. However, root damage had an effect on the inhibition of leaf and tiller development, and the ratio of leaves to tillers increased because tiller development was inhibited more by transplanting shock compared with leaf development. Based on these findings, we propose factors reflecting the delay in growth due to transplanting shock that should be included for more accurate rice phenology modeling and suggest advantageous seeding conditions and transplanting methods for improved rice cultivation and yield in response to climate change.

Explaining Neural Networks Using Attentive Knowledge Distillation.

Explaining the prediction of deep neural networks makes the networks more understandable and trusted, leading to their use in various mission critical tasks. Recent progress in the learning capability of networks has primarily been due to the enormous number of model parameters, so that it is usually hard to interpret their operations, as opposed to classical white-box models. For this purpose, generating saliency maps is a popular approach to identify the important input features used for the model prediction. Existing explanation methods typically only use the output of the last convolution layer of the model to generate a saliency map, lacking the information included in intermediate layers. Thus, the corresponding explanations are coarse and result in limited accuracy. Although the accuracy can be improved by iteratively developing a saliency map, this is too time-consuming and is thus impractical. To address these problems, we proposed a novel approach to explain the model prediction by developing an attentive surrogate network using the knowledge distillation. The surrogate network aims to generate a fine-grained saliency map corresponding to the model prediction using meaningful regional information presented over all network layers. Experiments demonstrated that the saliency maps are the result of spatially attentive features learned from the distillation. Thus, they are useful for fine-grained classification tasks. Moreover, the proposed method runs at the rate of 24.3 frames per second, which is much faster than the existing methods by orders of magnitude.

Mass action model of solution activity via speciation by solvation and ion pairing equilibria.

Solutes and their concentrations influence many natural and anthropogenic solution processes. Electrolyte and solution models are used to quantify and predict such behavior. Here we present a mechanistic solution model based on mass action equilibria. Solvation and ion pairing are used to model speciated solute and solvent concentrations such that they correlate to a solution's vapor pressure (solvent activity) according to Raoult's law from dilute conditions to saturation. This model introduces a hydration equilibrium constant (Kha) that is used with either an ion dissociation constant (Kid) or a hydration modifier (m) with an experimentally determined ion dissociation constant, as adjustable parameters to fit vapor-liquid equilibrium data. The modeled solvation equilibria are accompanied by molecular dynamics (MD) studies that support a decline in the observed degree of solvation with increased concentration. MD calculations indicate this finding is a combination of a solvent that solvates multiple solutes, and changes in a solute's solvation sphere, with the dominant factor changing with concentration. This speciation-based solution model is lateral to established electrostatics-based electrolyte theories. With its basis in mass action, the model can directly relate experimental data to the modeled solute and solvent speciated concentrations and structures.

Diffusivity and hydrophobic hydration of hydrocarbons in supercritical CO2 and aqueous brine.

CO2 injection (EOR and sequestration technique) creates the amalgamation of hydrocarbons, CO2, and aqueous brine in the subsurface. In this study, molecular dynamics (MD) simulations were used to investigate the diffusivity of hydrocarbon molecules in a realistic scenario of supercritical CO2 (SC-CO2) injection in the subsurface over a wide range of pressures (50 < P < 300 bar) and aqueous brine concentrations (0, 2, and 5% brine). To overcome existing challenges in traditional diffusivity calculation approaches, we took advantage of fundamental molecular-based methods, along with further verification of results by previously published experimental data. In this regard, computational methods and MD simulations were employed to compute diffusion coefficients of hydrocarbons (benzene and pentane). It was found that the presence of water and salt affects the thermodynamic properties of molecules where the intermolecular interactions caused the hydrophobic hydration of hydrocarbons coupled with ionic hydration due to hydrogen bond and ion-dipole interactions. Based on these results, it is demonstrated that the formation of water clusters in the SC-CO2 solvent is a major contributor to the diffusion of hydrophobic molecules. The outcome at different pressure conditions showed that hydrocarbons always would diffuse less in the presence of water. The slopes of linearly fitted MSD of benzene and pentane infinitely diluted in SC-CO2 is around 13 to 20 times larger than the slope with water molecules (4 wt%). When pressure increases (100-300 bar), the diffusion coefficients (D) of benzene and pentane decreases (around 1.2 × 10-9 to 0.4 × 10-9 and 2 × 10-9 to 1 × 10-9 m2 s-1, respectively). Furthermore, brine concentration generally plays a negative role in reducing the diffusivity of hydrocarbons due to the formation of water clusters as a result of hydrophobic and ionic hydration. Under the SC-CO2 rich (injection) system in the shale reservoir, the diffusion of hydrocarbon is correlated to the efficiency of hydrocarbon flow/recovery. Ultimately, this study will guide us to better understand the phenomena that would occur in nanopores of shale that undergo EOR or are becoming a target of CO2 sequestration.

Adsorption based realistic molecular model of amorphous kerogen.

This paper reports the results of Grand Canonical Monte Carlo (GCMC)/molecular dynamics (MD) simulations of N2 and CO2 gas adsorption on three different organic geomacromolecule (kerogen) models. Molecular models of kerogen, although being continuously developed through various analytical and theoretical methods, still require further research due to the complexity and variability of the organic matter. In this joint theory and experiment study, three different kerogen models, with varying chemical compositions and structure from the Bakken, were constructed based on the acquired analytic data by Kelemen et al. in 2007: 13C nuclear magnetic resonance (13C-NMR), X-ray photoelectron spectroscopy (XPS), and X-ray absorption near-edge structure (XANES). N2 and CO2 gas adsorption isotherms obtained from GCMC/MD simulations are in very good agreement with the experimental isotherms of physical samples that had a similar geochemical composition and thermal maturity. The N2/CO2 uptake by the kerogen model at a range of pressure shows considerable similarity with our experimental data. The stronger interaction of CO2 molecules with the model leads to the penetration of CO2 molecules to the sub-surface levels in contrast to N2 molecules being concentrated on the surface of kerogen. These results suggest the important role of kerogen in the separation and transport of gas in organic-rich shale that are the target for sequestration of CO2 and/or enhanced oil recovery (EOR).

3D Nanoprinting of Perovskites.

As competing with the established silicon technology, organic-inorganic metal halide perovskites are continually gaining ground in optoelectronics due to their excellent material properties and low-cost production. The ability to have control over their shape, as well as composition and crystallinity, is indispensable for practical materialization. Many sophisticated nanofabrication methods have been devised to shape perovskites; however, they are still limited to in-plane, low-aspect-ratio, and simple forms. This is in stark contrast with the demands of modern optoelectronics with freeform circuitry and high integration density. Here, a nanoprecision 3D printing is developed for organic-inorganic metal halide perovskites. The method is based on guiding evaporation-induced perovskite crystallization in mid-air using a femtoliter ink meniscus formed on a nanopipette, resulting in freestanding 3D perovskite nanostructures with a preferred crystal orientation. Stretching the ink meniscus with a pulling process enables on-demand control of the nanostructure's diameter and hollowness, leading to an unprecedented tubular-solid transition. With varying the pulling direction, a layer-by-layer stacking of perovskite nanostructures is successfully demonstrated with programmed shapes and positions, a primary step for additive manufacturing. It is expected that the method has the potential to create freeform perovskite nanostructures for customized optoelectronics.

X-ray-Powered Micromotors.

Light-powered wireless manipulation of small objects in fluids has been of interest for biomedical and environmental applications. Although many techniques employing UV-vis-NIR light sources have been devised, new methods that hold greater penetrating power deep into medium are still in demand. Here, we develop a method to exploit X-rays to propel half-metal-coated Janus microparticles in aqueous solution. The Janus particles are simultaneously propelled and visualized in real-time by using a full-field transmission X-ray microscope. Our real-time observation discovers that the propulsive motion follows the bubble growth enhanced by water radiolysis near the particle surface under X-ray irradiation. We also show that the propulsion speed is remotely controlled by varying the radiation dose. We expect this work to open opportunities to employ light-powered micro/nanomotors in opaque environments, potentially by combining with medical imaging or nondestructive testing.