Evaluation of soil pesticide leaching to groundwater using undisturbed lysimeter: development of the pesticide groundwater leaching scoring system (PLS).

Groundwater pesticide safety management is essential for providing consistently safe water for humans, but such management is limited globally. In this study, we developed an accurate and convenient exposure assessment method for the safety management of pesticides in groundwater by conducting a lysimeter experiment to evaluate the leaching of 11 pesticides into groundwater. During the experimental period, flutoalanil and oxadiazon had the highest cumulative leaching amounts, 603.7 and 83.5 ng, respectively. Comparative analysis of existing groundwater exposure prediction indices, including the GUS, LEACH, modified LEACH, Hornsby index, and GLI showed no correlations with the measured data (p > 0.05). To enhance the accuracy of the assessment method, we used lysimeter data and principal component analysis to determine the main factors affecting groundwater leaching, and developed the "pesticide groundwater leaching scoring system" (PLS). The soil and water half-life, which had the greatest positive impact on groundwater leaching, was set as a 10-point indicator, whereas log P was set as a 1-point indicator. In contrast, solubility in water was determined as a 5-point indicator, and organic carbon partition coefficient and vapor pressure were determined as 2.5-point indicators owing to their negative relationship. The correlation coefficient was 0.670, indicating a significant correlation with the lysimeter data (p < 0.05). Using our scoring system, we ranked 376 pesticides. As an exposure assessment method developed using actual data, the PLS is expected to be applicable to groundwater safety management.

360-degree mixed reality volumetric display using an asymmetric diffusive holographic optical element.

Volumetric display technique has a great advantage of displaying realistic three-dimensional contents with a 360-degree viewing angle. However, most volumetric displays cannot provide mixed reality because their screens inside the displays obstruct the external scene. We design a 360-degree mixed-reality volumetric display using an asymmetric diffusive holographic optical element (ADHOE). The ADHOE has wavelength selectivity, and it diffuses the light with the only specific wavelength for the virtual object, so it is possible to optically combine the virtual object and the real scene. Also, the ADHOE has different vertical and horizontal diffusing angles, and it is suitable for a horizontal-parallax-only application. In our system, the parallax images are generated by the DMD, and they are projected sequentially on the ADHOE. The ADHOE is shaped as a slanted curved surface with respect to the optical axis, and some annoying color dispersion is observed due to the mismatch between the diffraction peak points of two different wavelengths. In order to solve this problem, the carrier frequency is applied to green elemental images and the proper Fourier filter cuts off the unwanted diffraction peak points. The Fourier transform with 2f optics is built to record the ADHOE where the angular spectral bandwidth is determined by adjusting the width of the incident object light. A 360-degree see-through display with ADHOE is implemented and the feasibility of mixed reality is verified successfully.

Fatigue-free visual perception of high-density super-multiview augmented reality images.

It is well known that wearing virtual reality (VR) and augmented reality (AR) devices for long periods can cause visual fatigue and motion sickness due to vergence-accommodation conflict (VAC). VAC is considered the main obstacle to the development of advanced three-dimensional VR and AR technology. In this paper, we present a novel AR high-density super-multiview (HDSMV) display technique capable of eliminating VAC in wide range. The designed binocular time-sequential AR HDSMV projection, which delivers 11 views to each eye pupil, is experimentally demonstrated, confirming that VAC is eliminated over a wide-range of viewer's focus distance. It is believed that the proposed time-sequential AR HDSMV method will pave the way for the development of VAC-free AR technology.

Holographic printing for generating large-angle freeform holographic optical elements.

We propose a holographic printing technique for generating highly efficient large-deflection-angle freeform holographic optical elements (HOEs). For industrial device applications, the optical efficiency and deflection angle of HOEs are critical. To fabricate a high-frequency volume grating in a hogel, we design an optomechanical hogel recording system with a high angle deflection capability, which contrasts with the conventional printing scheme, the wavefront holographic printing technique featuring a paraxial deflection angle. With the proposed system, a large-deflection-angle HOE is experimentally demonstrated, and short-throw holographic caustic projection patterns are realized.

Wide-viewing full-color depthmap computer-generated holograms.

An efficient synthesis algorithm for wide-viewing full-color depthmap computer-generated holograms is proposed. We develop a precise computational algorithm integrating wave-optic geometry-mapping, color-matching, and noise-filtering to multiplex multiview elementary computer-generated holograms (CGHs) into a single high-definition CGH without three-dimensional perspective distortion or color dispersion. Computational parallelism is exploited to achieve significant computational efficiency improvement in the production throughput of full-color wide-viewing angle CGHs. The proposed algorithm is verified through the full-color binary hologram reconstruction experiments utilizing an off-axis R·G·B simultaneous illumination method, which suggests the feasibility of the full-color sub-wavelength binary spatial light modulator technology.

Monitoring and risk assessment of tepraloxydim in banana (Musa paradisiaca) and sweet orange (Citrus sinensis).

This study was conducted to analyze the residue levels of tepraloxydim in banana and sweet orange. Successive liquid-liquid extraction and cartridge clean-up method for tepraloxydim determination in banana and sweet orange were developed and validated by HPLC. The developed method was validated, and the recovery and LOQ of tepraloxydim were 79.3-99.5% and 0.02 mg kg-1, respectively. Among the 48 banana and 34 sweet orange samples, tepraloxydim was detected in two (0.03 mg kg-1) and four samples (0.03-0.05 mg kg-1), respectively. A risk assessment of tepraloxydim in banana and sweet orange was conducted by calculating the percent ratio of estimated daily intake (EDI) and acceptable daily intake (ADI). The ADI of tepraloxydim was 0.05 mg kg-1 day-1, and the EDIs of it from banana and sweet orange were 6.3 × 10-6 and 5.1-8.5 × 10-6, respectively. The percent of EDI to ADI of tepraloxydim was 0.013 and 0.010-0.017%, respectively. These results showed that the tepraloxydim levels in this study might not be harmful to human beings.

Inverse conversion algorithm for an all-optical depth coloring camera.

Three-dimensional (3D) metrology has received a lot of attention from academic and industrial communities due to its broad applications, such as 3D contents, 3D printing, and autonomous driving. The all-optical depth coloring (AODC) camera has some benefits in computation load since it extracts depth information of an object fully optically. The AODC camera represents the depth of the object as a variation of wavelength, and spectroscopy is generally required to measure the wavelength. However, in the AODC camera, the color vector in RGB color space is convertible inversely into the wavelength after projection on the normalized rgb plane because the detected spectrum through the gating part has a narrow bandwidth as a result of the width of the slit in the projection part. In this paper, we propose an inverse conversion algorithm from RGB color to depth without spectroscopy. Experimental results are presented to confirm its feasibility. Also, some practical limitations are discussed, resulting from the nonlinearity of the response of the image sensor and the widths of the slits in the projection part and the gating part.

All-optical depth coloring based on directional gating.

In non-contacting depth extraction there are several issues, such as the accuracy and the measurement speed. In the issue of the measurement speed, the computation cost for image processing is significant. We present an all-optical depth extraction method by coloring objects according to their depth. Our system is operated fully optically and both encoding and decoding processes are optically performed. Therefore, all-optical depth coloring has a distinct advantage to extract the depth information in real time without any computation cost. We invent a directional gating method to extract the points from the object which are positioned at the same distance. Based on this method, the objects look painted by different colors according to the distance when the objects are observed through our system. In this paper, we demonstrate the all-optical depth coloring system and verify the feasibility of our method.

Electrochemically Synthesized Sb/Sb2O3 Composites as High-Capacity Anode Materials Utilizing a Reversible Conversion Reaction for Na-Ion Batteries.

Sb/Sb2O3 composites are synthesized by a one-step electrodeposition process from an aqueous electrolytic bath containing a potassium antimony tartrate complex. The synthesis process involves the electrodeposition of Sb simultaneously with the chemical deposition of Sb2O3, which allows for the direct deposition of morula-like Sb/Sb2O3 particles on the current collector without using a binder. Structural characterization confirms that the Sb/Sb2O3 composites are composed of approximately 90 mol % metallic Sb and 10 mol % crystalline Sb2O3. The composite exhibits a high reversible capacity (670 mAh g(-1)) that is higher than the theoretical capacity of Sb (660 mAh g(-1)). The high reversible capacity results from the conversion reaction between Na2O and Sb2O3 that occurs additionally to the alloying/dealloying reaction of Sb with Na. Moreover, the Sb/Sb2O3 composite shows excellent cycle performance with 91.8% capacity retention over 100 cycles, and a superior rate capability of 212 mAh g(-1) at a high current density of 3300 mA g(-1). The outstanding cycle performance is attributed to an amorphous Na2O phase generated by the conversion reaction, which inhibits agglomeration of Sb particles and acts as an effective buffer against volume change of Sb during cycling.

High-Performance Sb/Sb2 O3 Anode Materials Using a Polypyrrole Nanowire Network for Na-Ion Batteries.

Three-dimensional porous Sb/Sb2 O3 anode materials are successfully fabricated using a simple electrodeposition method with a polypyrrole nanowire network. The Sb/Sb2 O3 -PPy electrode exhibits excellent cycle performance and outstanding rate capabilities; the charge capacity is sustained at 512.01 mAh g(-1) over 100 cycles, and 56.7% of the charge capacity at a current density of 66 mA g(-1) is retained at 3300 mA g(-1) . The improved electrochemical performance of the Sb/Sb2 O3 -PPy electrode is attributed not only to the use of a highly porous polypyrrole nanowire network as a substrate but also to the buffer effects of the Sb2 O3 matrix on the volume expansion of Sb. Ex situ scanning electron microscopy observation confirms that the Sb/Sb2 O3 -PPy electrode sustains a strong bond between the nanodeposits and polypyrrole nanowires even after 100 cycles, which maintains good electrical contact of Sb/Sb2 O3 with the current collector without loss of the active materials.

Fabrication of graphene embedded LiFePO4 using a catalyst assisted self assembly method as a cathode material for high power lithium-ion batteries.

We have designed a unique microstructure of graphene embedded LiFePO4 by a catalyst assisted self assembly method as a cathode material for high power lithium-ion batteries. The stable amide bonds between LiFePO4 and graphene were formed by the catalyst assisted self assembly. High conductive graphene provides a fast electron transfer path, and many pores inside the structure facilitate the lithium-ion diffusion. The graphene embedded LiFePO4 fabricated by the novel method shows enhanced cycling performance and rate-capability compared with that of carbon coated LiFePO4 as a cathode material for high power lithium-ion batteries.

Tailoring crystal structure and morphology of LiFePO4/C cathode materials synthesized by heterogeneous growth on nanostructured LiFePO4 seed crystals.

Porous and coarse (5-10 µm) LiFePO4/C composites with excellent electrochemical performance were synthesized by a growth technology using nanostructured (100-200 nm) LiFePO4 as seed crystals for the 2nd crystallization process. The porous and coarse LiFePO4/C presented a high initial discharge capacity (∼155 mA h g⁻¹ at 0.1 C), superior rate-capability (∼100 mA h g⁻¹ at 5 C, ∼65 % of the discharge capacity at 0.1 C), and excellent cycling performance (∼131 mA h g⁻¹, ∼98 % of its initial discharge capacity after 100 cycles at 1 C). The improvement in the rate-capability of the LiFePO4/C was attributed to the high reaction area resulted from the pore tunnels formed inside LiFePO4 particles and short Li-ion diffusion length. The improved cycling performance of the LiFePO4/C resulted from the enhanced structural stability against Li-deficient LiFePO4 phase formation after cycling by the expansion of the 1D Li-ion diffusion channel in the LiFePO4 crystal structure.

Engineering properties of water/wastewater-treatment sludge modified by hydrated lime, fly ash and loess.

The purpose of this research was to present engineering properties of modified sludge from water/wastewater treatment by modifiers such as hydrated lime, loess, and fly ash. The proper mixing ratio was determined to hold the pH of the modified sludge above 12.0 for 2 h. Laboratory tests carried out in this research included particle analysis, compaction and CBR, SEM and X-ray diffraction, unconfined compression test, permeability test, and TCLP test. The main role of lime was to sterilize microorganisms in the sludge. The unconfined strength of the modified sludge by fly ash and loess satisfied the criteria for construction materials, which was above 100 kPa. The permeability of all the mixtures was around 1.0 x 10(-7) cm/s. Extraction tests for hazardous components in modified sludge revealed below the regulated criteria, especially for cadmium, copper, and lead. The present study suggested that the use of lime, fly ash, and loess be an another alternative to modify or stabilize water/wastewater treatment sludge as construction materials in civil engineering.