Freshwater Recovery and Removal of Cesium and Strontium from Radioactive Wastewater by Methane Hydrate Formation.

As human society has advanced, nuclear energy has provided energy security while also offering low carbon emissions and reduced dependence on fossil fuels, whereas nuclear power plants have produced large amounts of radioactive wastewater, which threatens human health and the sustainability of water resources. Here, we demonstrate a hydrate-based desalination (HBD) technology that uses methane as a hydrate former for freshwater recovery and for the removal of radioactive chemicals from wastewater, specifically from Cs- and Sr-containing wastewater. The complete exclusion of radioactive ions from solid methane hydrates was confirmed by a close examination using phase equilibria, spectroscopic investigations, thermal analyses, and theoretical calculations, enabling simultaneous freshwater recovery and the removal of radioactive chemicals from wastewater by the methane hydrate formation process described in this study. More importantly, the proposed HBD technology is applicable to radioactive wastewater containing Cs+ and Sr2+ across a broad concentration range of low percentages to hundreds of parts per million (ppm) and even subppm levels, with high removal efficiency of radioactive chemicals. This study highlights the potential of environmentally sustainable technologies to address the challenges posed by radioactive wastewater generated by nuclear technology, providing new insights for future research and development efforts.

Zero-field polarity-reversible Josephson supercurrent diodes enabled by a proximity-magnetized Pt barrier.

Simultaneous breaking of inversion and time-reversal symmetries in a conductor yields a non-reciprocal electronic transport1-3, known as the diode or rectification effect, that is, low (ideally zero) conductance in one direction and high (ideally infinite) conductance in the other. So far, most of the diode effects observed in non-centrosymmetric polar/superconducting conductors4-7 and Josephson junctions8-10 require external magnetic fields to break the time-reversal symmetry. Here we report zero-field polarity-switchable Josephson supercurrent diodes, in which a proximity-magnetized Pt layer by ferrimagnetic insulating Y3Fe5O12 serves as the Rashba(-type) Josephson barrier. The zero-field diode efficiency of our proximity-engineered device reaches up to ±35% at 2 K, with a clear square-root dependence on temperature. Measuring in-plane field-strength/angle dependences and comparing with Cu-inserted control junctions, we demonstrate that exchange spin-splitting11-13 and Rashba(-type) spin-orbit coupling13-15 at the Pt/Y3Fe5O12 interface are key for the zero-field giant rectification efficiency. Our achievement advances the development of field-free absolute Josephson diodes.

Adaptive R&D contract for urgently needed drugs: Lessons from COVID-19 vaccine development.

This paper analyzes an incentive contract for new vaccine research and development (R&D) under pandemic situations such as COVID-19, considering the R&D contract's adaptability to the pandemic. We study how the public sector (government) designs the adaptive R&D contract and offers it to pharmaceutical enterprises. An agency-theoretic model is employed to explore the contract whose terms are an upfront grant as a fixed fee and a sales tax credit as an incentive tool, examining how the values of related parameters affect contract term determinations. We found that the adaptability factor derived from urgent policies such as emergency use authorization (EUA) as well as tax credits, can be utilized as practical incentive tools that lead vaccine developers to increase their effort levels for R&D success. We also found that public-private state-emergency contracts may not follow the conventional wisdom. Counterintuitively, dependency on tax credits (incentive part) decrease as the client's degree of risk averseness increases in the emergency contract.

Evidence of higher-order topology in multilayer WTe2 from Josephson coupling through anisotropic hinge states.

Td-WTe2 (non-centrosymmetric and orthorhombic), a type-II Weyl semimetal, is expected to have higher-order topological phases with topologically protected, helical one-dimensional hinge states when its Weyl points are annihilated. However, the detection of these hinge states is difficult due to the semimetallic behaviour of the bulk. In this study, we have spatially resolved the hinge states by analysing the magnetic field interference of the supercurrent in Nb-WTe2-Nb proximity Josephson junctions. The Josephson current along the a axis of the WTe2 crystal, but not along the b axis, showed a sharp enhancement at the edges of the junction, and the amount of enhanced Josephson current was comparable to the upper limits of a single one-dimensional helical channel. Our experimental observations suggest a higher-order topological phase in WTe2 and its corresponding anisotropic topological hinge states, in agreement with theoretical calculations. Our work paves the way for the study of hinge states in topological transition-metal dichalcogenides and analogous phases.

Author Correction: Evidence of higher-order topology in multilayer WTe2 from Josephson coupling through anisotropic hinge states.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Recovery of N2O: Energy-Efficient and Structure-Driven Clathrate-Based Greenhouse Gas Separation.

N2O has 300 times more global warming potential than CO2 and is also one of the main stratospheric ozone-depleting substances emitted by human activities such as agriculture, industry, and the combustion of fossil fuels and solid waste. We present here an energy-efficient clathrate-based greenhouse gas-separation (CBGS) technology that can operate at room temperature for selectively recovering N2O from gas mixtures. Clathrate formation between α-form/ß-form hydroquinone (α-HQ/ß-HQ) and gas mixtures reveals guest-specific and structure-driven selectivity, revealing the preferential capture of N2O in ß-HQ and the molecular sieving characteristics of α-HQ. With a maximum gas storage capacity and cage occupancy of 54.1 cm3 g-1 and 0.86, respectively, HQ clathrate compounds including N2O are stable at room temperature and atmospheric pressure and thus can be easily synthesized, treated, and recycled via commercial CBGS processes. High selectivity for N2O recovery was observed during ß-HQ clathrate formation from N2O/N2 gas mixtures with N2O concentrations exceeding 20%, whereas α-HQ traps only N2 molecules from gas mixtures. Full characterization using X-ray diffraction, scanning electron microscopy, Raman spectroscopy, solid-state nuclear magnetic resonance, and compositional analysis and the formation kinetics of HQ clathrates was conducted to verify the peculiar selectivity behavior and to design the conceptual CBGS process. These results provide a new playground on which to tailor host-guest materials and develop commercial processes for the recovery and/or sequestration of greenhouse gases.

A Case Report of Tracheostomy for a Patient with COVID-19: How to Minimize Medical Staff and Patient Risks.

Coronavirus disease was first reported in December 2019, and the World Health Organization declared it as a pandemic on March 11, 2020. The virus is known to attack various vital organs, including the respiratory system. Patients sometimes require positive pressure ventilation and tracheostomy. Because tracheostomy is a droplet-spreading procedure, medical staff should protect themselves against the risk of transmission of this contagious viral disease. In our case, we performed tracheostomy for a 70-year-old man with coronavirus disease 2019 (COVID-19) who had required more oxygen with gradual weakness of respiratory muscle to maintain his arterial oxygen saturation. We focused on the risks of the medical staffs and patients, and minimized them at the same time using temporary balloon over-inflation, pre-operative adjustment of endotracheal tube position, and attachment of a transparent film dressing to the surgical field without stopping the ventilator while following routine safety measures. Fourteen days after the tracheostomy, all participating medical staff members were healthy and asymptomatic. The patient was discharged 105 days after the COVID-19 diagnosis.

MRI-based EMVI positivity predicts systemic recurrence in rectal cancer patients with a good tumor response to chemoradiotherapy followed by surgery.

BACKGROUND: This study aimed to determine the prognostic value of baseline magnetic resonance imaging-based extramural vascular invasion status (EMVI) among rectal cancer patients with a good tumor response to standard chemoradiotherapy followed by surgery. METHODS: A total of 359 patients with ypT0-2/N0 disease from The Yonsei Multicenter Colorectal Cancer Electronic Database were retrospectively included between January 2000 and December 2014. Magnetic resonance images and medical records were reviewed to investigate risk factors for tumor recurrence. RESULTS: When we compared patients without and with EMVI, significant differences were observed in the 5-year disease-free survival rate (DFS) (80.8% vs 57.8%, P = 0.005) and in the 5-year systemic recurrence-free survival rate (SRFS) (86.9% vs 64.3%, P = 0.007). In the multivariate analysis, both mrEMVI and APR independently predicted overall DFS (APR; HR 2.088, 95% CI: 1.082-4.031, P = 0.028, mrEMVI; HR: 2.729, 95% CI: 1.230-6.058, P = 0.014). mrEMVI was only independent prognostic factor for systemic recurrence with statistical significance (HR: 3.321, 95% CI: 1.185-9.309, P = 0.022). CONCLUSION: Even in rectal cancer patients with a good response to chemoradiotherapy followed by curative surgery, extramural vascular invasion and APR may predict poor disease-free survival outcomes. Intensified treatment strategy should be considered.

Selective Encaging of N2O in N2O-N2 Binary Gas Hydrates via Hydrate-Based Gas Separation.

The crystal structure and guest inclusion behaviors of nitrous oxide-nitrogen (N2O-N2) binary gas hydrates formed from N2O/N2 gas mixtures are determined through spectroscopic analysis. Powder X-ray diffraction results indicate that the crystal structure of all the N2O-N2 binary gas hydrates is identified as the structure I (sI) hydrate. Raman spectra for the N2O-N2 binary gas hydrate formed from N2O/N2 (80/20, 60/40, 40/60 mol %) gas mixtures reveal that N2O molecules occupy both large and small cages of the sI hydrate. In contrast, there is a single Raman band of N2O molecules for the N2O-N2 binary gas hydrate formed from the N2O/N2 (20/80 mol %) gas mixture, indicating that N2O molecules are trapped in only large cages of the sI hydrate. From temperature-dependent Raman spectra and the Predictive Soave-Redlich-Kwong (PSRK) model calculation, we confirm the self-preservation of N2O-N2 binary gas hydrates in the temperature range of 210-270 K. Both the experimental measurements and the PSRK model calculations demonstrate the preferential occupation of N2O molecules rather than N2 molecules in the hydrate cages, leading to a possible process for separating N2O from gas mixtures via hydrate formation. The phase equilibrium conditions, pseudo-pressure-composition (P-x) diagram, and gas storage capacity of N2O-N2 binary gas hydrates are discussed in detail.

Effect of the finite pixel boundary on the angular emission characteristics of top-emitting organic light-emitting diodes.

We numerically investigate the effect of the pixel boundary on the angular emission characteristics of top-emitting organic light-emitting diodes (OLEDs) using the finite element method. A three-dimensional OLED structure has the square pixel boundary, which is surrounded by the pixel definition layer. The angular emission characteristics based on the Poynting vectors are calculated in various positions of a Hertz dipole emitter within the pixel boundary. When the dipole emitter is located near the center of the square pixel, the angular emission characteristics have a symmetric forward-directed pattern, which is similar to the angular emission pattern calculated by the thin-film-based optical model. When the position of the dipole emitter is close to the pixel boundary, the angular emission pattern becomes asymmetric because the optical reflections from the pixel boundary in the horizontal direction affect the emission pattern of the dipole emitter. The total angular emission characteristics of the top-emitting OLED are obtained by summing the individual angular emission pattern of the whole dipole emitters, which are assumed to be uniformly distributed in the two-dimensional emission plane. The asymmetrical angular emission characteristics of the dipole emitters near the pixel boundary contribute to narrowing the total angular emission pattern.

Spatial evolution of depolarization in homogeneous turbid media within the differential Mueller matrix formalism.

We show, through visible-range Mueller polarimetry, as well as numerical simulations, that the depolarization in a homogeneous turbid medium consisting of submicron spherical particles follows a parabolic law with the path-length traveled by light through the medium. This result is in full agreement with the phenomenological theory of the fluctuating medium within the framework of the differential Mueller matrix formalism. We further found that the standard deviations of the fluctuating elementary polarization properties of the medium depend linearly on the concentration of particles. These findings are believed to be useful for the phenomenological interpretation of polarimetric experiments, with special emphasis on biomedical applications.

Equilibrium, Kinetics, and Spectroscopic Studies of SF6 Hydrate in NaCl Electrolyte Solution.

Many studies have focused on desalination via hydrate formation; however, for their potential application, knowledge pertaining to thermodynamic stability, formation kinetics, and guest occupation behavior in clathrate hydrates needs to be determined. Herein, the phase equilibria of SF6 hydrates in the presence of NaCl solutions (0, 2, 4, and 10 wt %) were monitored in the temperature range of 277-286 K and under pressures of up to 1.4 MPa. The formation kinetics of SF6 hydrates in the presence of NaCl solutions (0, 2, and 4 wt %) was also investigated. Gas consumption curves of SF6 hydrates showed that a pure SF6 hydrate system allowed fast hydrate growth as well as high conversion yield, whereas SF6 hydrate in the presence of NaCl solutions showed retarded hydrate growth rate as well as low conversion yield. In addition, structural identification of SF6 hydrates with and without NaCl solutions was performed using spectroscopic tools such as Raman spectroscopy and X-ray diffraction. The Raman spectrometer was also used to evaluate the temperature-dependent release behavior of guest molecules in SF6 and SF6 + 4 wt % NaCl hydrates. The results indicate that whereas SF6 hydrate starts to decompose at around 240 K, the escape of SF6 molecules in SF6 + 4 wt % NaCl hydrate is initiated rapidly at around 205 K. The results of this study can provide a better understanding of guest-host interaction in electrolyte-containing systems.

Dynamic Manipulation of Chiral Domain Wall Spacing for Advanced Spintronic Memory and Logic Devices.

Nanoscopic magnetic domain walls (DWs), via their absence or presence, enable highly interesting binary data bits. The current-controlled, high-speed, synchronous motion of sequences of chiral DWs in magnetic nanoconduits induced by current pulses makes possible high-performance spintronic memory and logic devices. The closer the spacing between neighboring DWs in an individual conduit or nanowire, the higher the data density of the device, but at the same time, the more difficult it is to read the bits. Here, we show how the DW spacing can be dynamically varied to facilitate reading for otherwise closely packed bits. In the first method, the current density is increased in portions of the conduit that, thereby, locally speeds up the DWs, decompressing them and making them easier to read. In the second method, a localized bias current is used to compress and decompress the DW spacing. Both of these methods are demonstrated experimentally and validated by micromagnetic simulations. DW compression and decompression rates as high as 88% are shown. These methods can increase the density with which DWs can be packed in future DW-based spintronic devices by more than an order of magnitude.

All-Oxide Metasurfaces Formed by Synchronized Local Ionic Gating.

Ionic gating of oxide thin films has emerged as a novel way of manipulating the properties of thin films. Most studies are carried out on single devices with a three-terminal configuration, but, by exploring the electrokinetics during the ionic gating, such a configuration with initially insulating films leads to a highly non-uniform gating response of individual devices within large arrays of the devices. It is shown that such an issue can be circumvented by the formation of a uniform charge potential by the use of a thin conducting underlayer. This synchronized local ionic gating allows for the simultaneous manipulation of the electrical, magnetic, and/or optical properties of large arrays of devices. Designer metasurfaces formed in this way from SrCoO2.5 thin films display an anomalous optical reflection of light that relies on the uniform and coherent response of all the devices. Beyond oxides, almost any material whose properties can be controlled by the addition or removal of ions via gating can form novel metasurfaces using this technique. These findings provide insights into the electrokinetics of ionic gating and a wide range of applications using synchronized local ionic gating.

Thermodynamic stability, spectroscopic identification, and gas storage capacity of CO2-CH4-N2 mixture gas hydrates: implications for landfill gas hydrates.

Landfill gas (LFG), which is primarily composed of CH(4), CO(2), and N(2), is produced from the anaerobic digestion of organic materials. To investigate the feasibility of the storage and transportation of LFG via the formation of hydrate, we observed the phase equilibrium behavior of CO(2)-CH(4)-N(2) mixture hydrates. When the specific molar ratio of CO(2)/CH(4) was 40/55, the equilibrium dissociation pressures were gradually shifted to higher pressures and lower temperatures as the mole fraction of N(2) increased. X-ray diffraction revealed that the CO(2)-CH(4)-N(2) mixture hydrate prepared from the CO(2)/CH(4)/N(2) (40/55/5) gas mixture formed a structure I clathrate hydrate. A combination of Raman and solid-state (13)C NMR measurements provided detailed information regarding the cage occupancy of gas molecules trapped in the hydrate frameworks. The gas storage capacity of LFG hydrates was estimated from the experimental results for the hydrate formations under two-phase equilibrium conditions. We also confirmed that trace amounts of nonmethane organic compounds do not affect the cage occupancy of gas molecules or the thermodynamic stability of LFG hydrates.

Structural transformation and guest dynamics of methanol-loaded hydroquinone clathrate observed by temperature-dependent Raman spectroscopy.

The structural transformations and guest dynamics of methanol-loaded ß-form hydroquinone (HQ) clathrate were investigated using temperature-dependent Raman spectroscopy. Methanol-loaded ß-form HQ clathrate was obtained by recrystallization and characterized by elemental analysis, synchrotron X-ray diffraction, solid-state (13)C NMR spectroscopy, and Raman spectroscopy. Temperature-dependent Raman spectra of methanol-loaded ß-form HQ clathrate were measured in the temperature range 300-412 K at increments of 4 K. Although no significant changes were evident in the temperature range 300-376 K, abrupt changes in the relative intensity and shape of the Raman bands were observed between 380 and 412 K indicating the structural transition from methanol-loaded ß-form HQ clathrate to pure α-form HQ. Methanol molecules were gradually released from the ß-form HQ clathrate in the range 364-380 K. Upon returning to ambient conditions, the crystal structure of the HQ sample remained identical to that of pure α-form HQ. Therefore, the temperature-induced structural transition of methanol-loaded HQ clathrate is completely irreversible and α-form HQ is more stable at ambient conditions.

Trauma-induced capillary leak syndrome after penetrating chest injury: Manifestation of massive ascites and pulmonary secretions aggravated by transfusion.

Trauma with prolonged shock can cause systemic capillary leak syndrome regardless of the site of injury and a transfusion can aggravate it. The systemic capillary leak induces both an abdominal compartment syndrome and pulmonary edema, and a transfusion can aggra-vate these sequelae within hours. In our case, 21-year-old man with a penetrating injury in his left thorax experienced delay in rescue and definitive surgery. To manage life-threatening shock, massive blood transfusion and crystalloids had been infused. Cardiopulmonary cerebral resuscitations were performed 2 times during the surgery. Massive amount of pulmonary secretions emitted from his airways with severe hypoxia along with development of massive ascites causing abdominal compartment syndrome, while the surgery was underway. After temporary abdominal closure, he was moved to the intensive care unit and underwent venovenous extracorporeal membranous oxygenation. He recovered without any notable complications. It is important to prevent and correct the shock rapidly by appropriate rescue, controlling the source and infusing less amount of crystalloid and transfusion.

Local and global energy barriers for chiral domain walls in synthetic antiferromagnet-ferromagnet lateral junctions.

Of great promise are synthetic antiferromagnet-based racetrack devices in which chiral composite domain walls can be efficiently moved by current. However, overcoming the trade-off between energy efficiency and thermal stability remains a major challenge. Here we show that chiral domain walls in a synthetic antiferromagnet-ferromagnet lateral junction are highly stable against large magnetic fields, while the domain walls can be efficiently moved across the junction by current. Our approach takes advantage of field-induced global energy barriers in the unique energy landscape of the junction that are added to the local energy barrier. We demonstrate that thermal fluctuations are equivalent to the magnetic field effect, thereby, surprisingly, increasing the energy barrier and further stabilizing the domain wall in the junction at higher temperatures, which is in sharp contrast to ferromagnets or synthetic antiferromagnets. We find that the threshold current density can be further decreased by tilting the junction without affecting the high domain wall stability. Furthermore, we demonstrate that chiral domain walls can be robustly confined within a ferromagnet region sandwiched on both sides by synthetic antiferromagnets and yet can be readily injected into the synthetic antiferromagnet regions by current. Our findings break the aforementioned trade-off, thereby allowing for versatile domain-wall-based memory, and logic, and beyond.

Control of Oxygen Vacancy Ordering in Brownmillerite Thin Films via Ionic Liquid Gating.

Oxygen defects and their atomic arrangements play a significant role in the physical properties of many transition metal oxides. The exemplary perovskite SrCoO3-δ (P-SCO) is metallic and ferromagnetic. However, its daughter phase, the brownmillerite SrCoO2.5 (BM-SCO), is insulating and an antiferromagnet. Moreover, BM-SCO exhibits oxygen vacancy channels (OVCs) that in thin films can be oriented either horizontally (H-SCO) or vertically (V-SCO) to the film's surface. To date, the orientation of these OVCs has been manipulated by control of the thin film deposition parameters or by using a substrate-induced strain. Here, we present a method to electrically control the OVC ordering in thin layers via ionic liquid gating (ILG). We show that H-SCO (antiferromagnetic insulator, AFI) can be converted to P-SCO (ferromagnetic metal, FM) and subsequently to V-SCO (AFI) by the insertion and subtraction of oxygen throughout thick films via ILG. Moreover, these processes are independent of substrate-induced strain which favors formation of H-SCO in the as-deposited film. The electric-field control of the OVC channels is a path toward the creation of oxitronic devices.