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Enhancing ammonia production rates from electrochemical nitrogen reduction by engineering three-phase boundary with phosphorus-activated Cu catalysts

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Journal of Energy Chemistry 2023年第9期84卷 394-401页

作者： Jeehye Kim cho Hee Lee Yong Hyun Moon min Hee Lee Eun Hyup Kim Sun Hee choi Youn Jeong Jang Jae sung Lee School of Energy and Chemical Engineering Ulsan National Institute of Science and Technology(UNIST)Ulsan 44919Republic of Korea Department of Chemical Engineering Hanyang UniversitySeoul 04763Republic of Korea Pohang Accelerator Laboratory(PAL) Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea

Electrochemical N_(2) reduction reaction(eNRR) over Cu-based catalysts suffers from an intrinsically low activity of Cu for activation of stable N_(2) molecules and the limited supply of N_(2) to the catalyst due to its low solubility in aqueous ***,we propose phosphorus-activated Cu electrocatalysts to generate electron-deficient Cu sites on the catalyst surface to promote the adsorption of N_(2) *** eNRR system is further modified using a gas diffusion electrode(GDE) coated with polytetrafluoroethylene(PTFE) to form an effective three-phase boundary of liquid water-gas N_(2)-solid catalyst to facilitate easy access of N_(2) to the catalytic *** a result,the new catalyst in the flow-type cell records a Faradaic efficiency of 13.15% and an NH_(3) production rate of 7.69 μg h^(-1) cm^(-2) at-0.2 V_(RHE),which represent 3.56 and 59.2 times increases from those obtained with a pristine Cu electrode in a typical electrolytic *** work represents a successful demonstration of dual modification strategies;catalyst modification and N_(2) supplying system engineering,and the results would provide a useful platform for further developments of electrocatalysts and reaction systems.

关键词： Electrochemical nitrogen reduction reaction Ammonia production Phosphorous modified copper electrodes Gas diffusion electrodes Three-phase boundary PTFE coating

Gastric dysplasia may be an independent risk factor of an advanced colorectal neoplasm

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World Journal of Gastroenterology 2009年第45期15卷 5722-5726页

作者： Rack Cheon Bae Seong Woo Jeon Han Jin cho min Kyu Jung Young Oh Kweon sung Kook Kim Department of Internal Medicine Kyungpook National University Hospital

AIM: To evaluate the relationship between gastric dysplasia and Helicobacter pylori (H pylori) and the occurrence of colorectal adenoma, and to defi ne the necessity for colonoscopy in patients with gastric dysplasia or H pylori ***: From May 2005 to February 2008, 133 patients with established gastric dysplasia by gastroduo-denoscopy (EGD) were additionally investigated by colonoscopy. The authors compared results with those of 213 subjects who underwent both EGD and colonoscopy during the same period at the author’s Health Promotion Center as a control group. H pylori infection was evaluated in both the gastric dysplasia and control ***: The mean age of all 346 study subjects was 54.1 ± 10.5 years, and there were 258 (73%) men and 87 (27%) women. No signif icant difference was found between the H pylori positive and negative subjects in terms of the prevalence of colorectal adenoma and advanced colorectal adenoma (P = 0.261). Patients with gastric dysplasia showed no elevated risk of colorectal adenoma (OR = 0.910, 95% CI: 0.587-1.411, P = 0.738), but had a signif icantly higher risk of having advanced colorectal adenoma (OR = 3.382, 95% CI: 1.700-6.342, P = 0.000).CONCLUSION: The study emphasizes the need for colon surveillance in patients with gastric dysplasia, regardless of H pylori infection.

关键词： Gastric adenoma or dysplasia Helicobacter pylori Colorectal neoplasm

Neuroprotective effects of tamsulosin on intracerebral hemorrhage

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Neural Regeneration Research 2011年第32期6卷 2505-2510页

作者： Hong-Jin Suh sung-min So Young-Gil Na Il-Gyu Ko sung-Eun Kim Yun-Hee sung Mal-Soon Shin Chang-Ju Kim Young-Sam cho Khae-Hawn Kim Department of Urology Incheon St. Mary's Hospital the Catholic University of Korea School of Medicine Department of Urology Chungnam National University School of Medicine Department of Physiology Kyung Hee University School of Medicine Department of Urology Kangbuk Samsung Hospital Sungkyunkwan University School of Medicine Department of Urology Gachon University Gil Hospital Gachon University of Medicine and Science

The alpha1 adrenoreceptor antagonist tamsulosin is primarily used to treat benign prostatic hypertrophy. In this study, we intragastrically administered rats with 0.01,0.1 and 1 mg/kg tamsulosin to investigate the effects of tamsulosin on memory function, and hippocampal cell apoptosis and proliferation following intracerebral hemorrhage. Step-down avoidance task results showed that tamsulosin treatment markedly alleviated intracerebral hemorrhage- induced short-term memory impairment. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling results showed that tamsulosin treatment markedly suppressed intracerebral hemorrhage-induced caspase-3 expression in the hippocampal CA1 region and cell proliferation in the hippocampal dentate gyrus. Tamsulosin treatment at a dose of 0.01 mg/kg exhibited the most potent inhibitory effects on cell apoptosis and proliferation. These findings suggest that tamsulosin treatment facilitates the recovery of rat memory function by inhibiting hippocampal cell apoptosis and proliferation followincl intracerebral hemorrhaQe.

关键词： tamsulosin, intracerebral hemorrhage short-term memory apoptosis cellproliferation hippocampus neural regeneration

Development of Preliminary Design Program for Combustor of Regenerative Cooled Liquid Rocket Engine

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Journal of Thermal Science 2011年第5期20卷 467-473页

作者： Won Kook cho Woo Seok Seol min Son min Kyo Seo Jaye Koo Korea Aerospace Research Institute DaejoenRepublic of Korea Graduate Student Korea Aerospace UniversityGoyangRepublic of Korea School of Aerospace and Mechanical Engineering Korea Aerospace UniversityGoyangRepublic of Korea

An integrated program was established to design a combustor for a liquid rocket engine and to analyze regenerative cooling results on a preliminary design *** of burnt gas from a kerosene-LOx mixture in the combustor and rocket performance were calculated from CEA which is the code for the calculation of chemical *** heat transfer of regenerative cooling was analyzed by using SUPERTRAPP code for coolant properties and by one-dimensional correlations of the heat transfer coefficient from the combustor liner to the *** of the combustors of F-1 and RS-27A engines were designed from similar input data and the present results were compared to actual data for ***,the combustors of 30 tonf class,75 tonf class and 150 tonf class were designed from the required thrust,combustion chamber,exit pressure and mixture ratio of *** wall temperature,heat flux and pressure drop were calculated for heat transfer analysis of regenerative cooling using the profiles.

关键词： Liquid rocket engine Preliminary design of Combustor Regenerative cooling

Therapeutic benefit of repetitive transcranial magnetic stimulation for severe mirror movements A case report

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Neural Regeneration Research 2013年第6期8卷 569-574页

作者： Han Sun Kim sung Ho Jang Zee-Ihn Lee Mi Young Lee Yun Woo cho Migyoung Kweon Su min Son Department of Physical Medicine and Rehabilitation College of MedicineYeungnam University Department of Pediatrics College of MedicineYeungnam University Department of Physical Medicine and Rehabilitation Daegu Fatima Hospital Department of Physical therapy College of Health and TherapyDaegu Haany University

Congenital mirror movements retard typical hand functions, but no definite therapeutic modality is available to treat such movements. We report an 8-year-old boy with severe mirror movements of both hands. His mirror movements were assessed using the Woods and Teuber grading scale and his fine motor skills were also evaluated by the Purdue Pegboard Test. A 2-week regimen of repetitive transcranial magnetic stimulation produced markedly diminished mirror movement symptoms and increased the fine motor skills of both hands. Two weeks after the completion of the regimen, mirror movement grades had improved from grade 4 to 1 in both hands and the Purdue Pegboard Test results of the right and left hands also improved from 12 to 14 or 13. These improvements were maintained for 1 month after the 2-week repetitive transcranial magnetic stimulation regimen. After 18 months, the mirror movement grade was maintained and the Purdue Pegboard test score had improved to 15 for the right hand while the left hand score was maintained at 13. This occurred without any additional repetitive transcranial magnetic stimulation or other treatment. These findings suggest that repetitive transcranial magnetic stimulation for this patient had a therapeutic and long-term effect on mirror movements.

关键词： neural regeneration neurorehabilitation clinical practice mirror movements Purdue Pegboard test hand transcranial magnetic stimulation hand function cortex suppression corticospinal tract grants-supported paper neuroregeneration

Ion shielding functional separator using halloysite containing a negative functional moiety for stability improvement of Li–S batteries

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Journal of Energy Chemistry 2021年第9期30卷 334-340页

作者： Yong min Kwon Jihoon Kim Kuk Young cho Sukeun Yoon Division of Advanced Materials Engineering&Institute for Rare Metals Kongju National UniversityChungnam 31080Republic of Korea Department of Materials Science and Chemical Engineering Hanyang UniversityGyeonggi 15588Republic of Korea

Lithium–sulfur batteries are one of the attractive next-generation energy storage systems owing to theienvironmental friendliness,low cost,and high specific energy ***,the low electrical conductivity of sulfur,shuttling of soluble intermediate polysulfides between electrodes,and low capacitretention have hampered their commercial *** address these issues,we use a halloysitemodulated(H-M)separator in a lithium–sulfur battery to mitigate the shuttling *** H-M separator acts as a mutual Coulombic repulsion in lithium-sulfur batteries,thereby selectively permitting Lions and efficiently suppressing the transfer of undesired lithium polysulfides to the Li anode sideMoreover,the use of halloysite switches the surface of the separator from hydrophobic to hydrophilicconsequently improving the electrolyte wettability and adhesion between the separator and cathodeWhen sulfur-multi-walled carbon nanotube(S-MWCNT)composites are used as cathode active materialsa lithium–sulfur battery with an H-M separator exhibits first discharge and charge capacities of 1587 an1527 m Ah g-1,***,there is a consistent capacity retention up to 100 cyclesAccordingly,our approach demonstrates an economical and easily accessible strategy for commercialization of lithium–sulfur batteries.

关键词： Li–S batteries Halloysite Ion shielding Negative functional moiety Lithium polysulfides

The geometrical properties of parity and time reversal operators in two dimensional spaces

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Applied Mathematics(A Journal of Chinese Universities) 2019年第2期34卷 173-183页

作者： HUANG min-yi YANG Yu WU Jun-de cho min-Hyung School of Mathematical Science Zhejiang UniversityHangzhou 310027People’s Republic of China Department of Mathematics National University of SingaporeSingapore 119076Republic of Singapore Department of Applied Mathematics Kumoh National Institute of TechnologyKyungbuk39177Korea

The parity operator P and time reversal operator T are two important operators in the quantum theory, in particular, in the PT -symmetric quantum theory. By using the concrete forms of P and T , we discuss their geometrical properties in two dimensional spaces. It is showed that if T is given, then all P links with the quadric surfaces;if P is given, then all T links with the quadric curves. Moreover, we give out the generalized unbroken PT -symmetric condition of an operator. The unbroken PT -symmetry of a Hermitian operator is also showed in this way.

关键词： PT -symmetry geometrical property unbroken condition

Conceptual Design for a Kerosene Fuel-rich Gas-generator of a Turbopump-fed Liquid Rocket Engine

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Journal of Thermal Science 2012年第5期21卷 428-434页

作者： min Son Jaye Koo Won Kook cho Eun Seok Lee Graduate Student Korea Aerospace UniversityGoyang Republic of Korea School of Aerospace and Mechanical Engineering Korea Aerospace UniversityGoyang Republic of Korea Korea Aerospace Research Institute Daejeon Republic of Korea

A design method for a kerosene fuel-rich gas-generator of a liquid rocket engine using turbopumps to supply propellant was performed at a conceptual level. The gas-generator creates hot gases, enabling the turbine to operate the turbopumps. A chemical non-equilibrium analysis and a droplet vaporization model were used for the estimation of the burnt gas properties and characteristic chamber length. A premixed counter-flow flame analysis was performed for the prediction of the burnt gas properties, namely the temperature, the specific heat ratio and heat capacity, and the chemical reaction time. To predict the vaporization time, the Spalding model, using a single droplet in convective condition, was used. The minimum residence time in the chamber and the characteristic length were calculated by adding the reaction time and the vaporization time. Using the characteristic length, the design methods for the fuel-rich gas-generator were established. Finally, a parametric study was achieved for the effects of the O/F ratio, mass flow rate, chamber pressure, initial droplet temperature, initial droplet diameter and initial droplet velocity.

关键词： Liquid rocket engine Conceptual design Fuel-rich gas-generator Sensitivity analysis

An investigation of the microstructural effects on the mechanical and electrochemical properties of a friction stir processed equiatomic CrMnFeCoNi high entropy alloy

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Journal of Materials Science & Technology 2021年第28期87卷 60-73页

作者： Sam Yaw Anaman Solomon Ansah Hoon-Hwe cho min-Gu Jo Jin-Yoo Suh minjung Kang Jong-Sook Lee sung-Tae Hong Heung Nam Han Department of Materials Science and Engineering Hanbat National University125 Dongseodae-roYuseong-GuDaejeonRepublic of Korea Center for Energy Materials Research Clean Energy InstituteKorea Institute of Science and TechnologySeoul02792Republic of Korea Department of Materials Science and Engineering&Research Institute of Advanced Materials Seoul National University1Gwanak-roGwanak-guSeoul08826Republic of Korea Advanced Functional Technology R&D Department Korea Institute of Industrial TechnologyIncheon21999Republic of Korea School of Materials Science and Engineering Chonnam National UniversityGwangju61186Republic of Korea School of Mechanical Engineering University of UlsanUlsan680-749Republic of Korea

The electrochemical properties of a friction stir processed(FSPed)equiatomic CrMnFeCoNi high-entropy alloy(HEA)was investigated in an aerated 0.5 M Na_(2)SO_(4) electrolyte solution at room *** microstructural analysis reveals a highly refined stir zone(SZ)with an average grain size that decreases from the top region of the SZ to the bottom region of the SZ(also known as shear-processed zone;SPZ).However,the region below the SPZ,(*** the plunge depth)experienced an increase in average grain size and dislocation densities compared to the other *** is no secondary phase observed in the FSPed region,however,the microstructural evolution in the FSPed region affects the electrochemical behavior of the ***_(2)O_(3) passive layer was observed to form on the FSPed HEA,leading to excellent corrosion properties from the polarization corrosion *** refinement in the SZ enhances the rapid formation of the passive layer,thus,leading to better corrosion properties in the front surface of the FSPed *** localized corrosion behavior of the FSPed HEA was predicted to be caused by the micro-galvanic nature of the HEA,which leads to an increase in polarization at the anodic sites(pits).A numerical model was established using the corrosion parameters from the experiment to simulate the localized corrosion behavior on the surface of the FSPed HEA in a neutral *** predicted initial pitting potential and corresponding current density agree well with the experimental *** model is also capable of tracking the dissolution of the pits over longer periods.

关键词： High entropy alloys Friction stir processing Grain refinement Passive film Pitting Simulation