Ultrathin Two-Dimensional Atomic Crystals as Stable Interfacial Layer for Improvement of Lithium Metal Anode

Yan, Kai,Lee, Hyun-Wook,Gao, Teng,Zheng, Guangyuan,Yao, Hongbin,Wang, Haotian,Lu, Zhenda,Zhou, Yu,Liang, Zheng,Liu, Zhongfan,Chu, Steven,Cui, Yi American Chemical Society 2014 NANO LETTERS Vol.14 No.10

<P>Stable cycling of lithium metal anode is challenging due to the dendritic lithium formation and high chemical reactivity of lithium with electrolyte and nearly all the materials. Here, we demonstrate a promising novel electrode design by growing two-dimensional (2D) atomic crystal layers including hexagonal boron nitride (h-BN) and graphene directly on Cu metal current collectors. Lithium ions were able to penetrate through the point and line defects of the 2D layers during the electrochemical deposition, leading to sandwiched lithium metal between ultrathin 2D layers and Cu. The 2D layers afford an excellent interfacial protection of Li metal due to their remarkable chemical stability as well as mechanical strength and flexibility, resulting from the strong intralayer bonds and ultrathin thickness. Smooth Li metal deposition without dendritic and mossy Li formation was realized. We showed stable cycling over 50 cycles with Coulombic efficiency ∼97% in organic carbonate electrolyte with current density and areal capacity up to the practical value of 2.0 mA/cm<SUP>2</SUP>and 5.0 mAh/cm<SUP>2</SUP>, respectively, which is a significant improvement over the unprotected electrodes in the same electrolyte.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2014/nalefd.2014.14.issue-10/nl503125u/production/images/medium/nl-2014-03125u_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl503125u'>ACS Electronic Supporting Info</A></P>

Study on Properties of Expansive Soil Improved by Steel Slag Powder and Cement under Freeze-Thaw Cycles

Yankai Wu,Xiaolong Qiao,Xinbao Yu,Jiali Yu,Yongfeng Deng 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.2

Expansive soil is considered to be an unfavorable soil due to its swelling-shrinking behavior. In order to improve the properties of expansive soil, the addition of steel slag powder (SSP) has been used to improve expansive soil that has been mixed with the cement. In this study, a series of cylindrical improved expansive soil specimens were prepared, which were improved either by the addition of cement, cement SSP, or cement SSP sodium hydroxide (NaOH). All of the specimens were prepared with an optimum water content and then subjected to a maximum of 12 closed-system freeze-thaw (F-T) cycles. The specimens were subjected to different curing times and temperatures (-5oC,-10oC and -15oC) during the tests. After each freeze-thaw (F-T) cycle, the volume of each specimen was measured and an unconfined compression strength (UCS) test was performed. The results have shown that as the temperature of the F-T cycle decreased, the volume expansion rate increased with the increase of the length of the F-T cycle. As the curing time increased, the effect of the F-T cycles on the volume change rate of the specimens reduced and the UCS increased. The first F-T cycle had the greatest influence on the volume of the specimen as well as the UCS of the improved expansive soil. After the improved expansive soils had undergone more than eight F-T cycles, the volume change rate of the specimen tended to stabilize. The maximum F-T volume change rate of the improved soil was 1.93%.When the curing age was 60d and 90d, the strength of the specimen with cement SSP sodium hydroxide was 377.3 kPa and 294.7 kPa higher than the specimen with cement only (ES specimen), and its strength degradation rate was 18.737% and 9.97% lower than the ES specimen. The results have shown that the addition of SSP and cement improved the expansive soil; moreover, NaOH inhibited the degradation of the soil during an F-T cycle.

Meta-Analysis of the Efficacy and Safety of Mirabegron Add-On Therapy to Solifenacin for Overactive Bladder

Yankai Xu,Ruihua Liu,Chu Liu,Yuanshan Cui,Zhenli Gao 대한배뇨장애요실금학회 2017 International Neurourology Journal Vol.21 No.3

Purpose: We performed a meta-analysis to evaluate the efficacy and safety of mirabegron add-on therapy to solifenacin for patients with overactive bladder (OAB). Methods: We conducted a systematic literature review to identify all randomized, double-blind, controlled trials (RCTs) of this combination (mirabegron and solifenacin) for OAB. Embase, MEDLINE, and the Cochrane Central Register of Controlled Trials were searched. A manual search was also performed to investigate relevant references from the retrieved studies. Results: Four publications describing 5 RCTs that compared combination therapy with solifenacin, including a total of 3,309 patients, were analyzed. The mean number of micturitions per 24 hours (mean difference [MD], -0.45; 95% confidence interval [CI], -0.65 to -0.26; P<0.00001), number of episodes of incontinence per 24 hours (MD, -0.71; 95% CI, -0.14 to -0.02; P=0.04), volume voided per micturition, and number of urgency episodes per 24 hours demonstrated that combination therapy was more effective than solifenacin therapy alone. Safety assessments, including common treatment-emergent adverse events (odds ratio, 1.09; 95% CI, 0.95–1.27; P=0.23) and discontinuations due to adverse events (P=0.30), demonstrated that the combination therapy was well tolerated. Conclusions: This meta-analysis suggests that mirabegron therapy as an add-on to solifenacin provides a satisfactory therapeutic effect for OAB symptoms with a low occurrence of side effects.

Modeling and Deep Reinforcement Learning Based Control Parameter Tuning for Voltage Source Converter in a Renewable Energy Generation System

Xing Yankai,Zhang Guangdou,Wang Baolu,Li Jian,Bamisile Olusola,Cai Dongsheng,Huang Qi 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.2

The fast response and low inertia characteristics of converter-based generation (CBG) lead to a new stability issue that limits renewable energy development. This is due to the fact that, using traditional control theory as basic, there is no unifed and efective way to linearize the electronic device and set the parameters in the existing analysis method. In order to optimize the parameters tuning process of the converter control, a benchmark model is adopted in this paper, and the linearization model is updated by selecting suitable variables and detailed with considering the infuence of resistance of the converter. Based on this model, the stability margin related to the parameters of the system is analyzed. Furthermore, to consider more dynamics and make the converter controller focus on the topologies and scenarios, the dynamic response of a disturbance in the grid is selected as the iteration state to design a controller using Deep Reinforcement Learning (DRL). That is, the cascaded voltage and current control along with droop control are tuned by Deep Deterministic Policy Gradient (DDPG) algorithm in the linearized model. The validation tests are carried out on the nonlinear model in Simulink test and real-time platform. They indicate that the proposed linearization and tuning method provides more accuracy and stability for the power system in various grid conditions.

Frame Vibration Suppression Method for Sensorless PMSM Drive Applications

Supharat Suthep,Yankai Wang,Muneaki Ishida,Naoki Yamamura,Kazuhiro Yubai,Satoshi Komada 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6

This study proposes a novel frame anti-vibration controller for position sensorless PMSM drive application. This controller is called specific component reduction controller (SCRC). SCRC can function without an accelerometer and can achieve speed variable control. This study mainly comprises the following phases. First, the position sensorless control method will be provided. Second, the frame vibration model and load torque ripple will be shown. Third, SCRC will be discussed and its stability will be analyzed. Finally, experimental results show that SCRC can achieve speed variable anti-vibration control and compensate target frequency torque ripple.

Frame Vibration Suppression Method for Sensorless PMSM Drive Applications

Suthep, Supharat,Wang, Yankai,Ishida, Muneaki,Yamamura, Naoki,Yubai, Kazuhiro,Komada, Satoshi The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6

This study proposes a novel frame anti-vibration controller for position sensorless PMSM drive application. This controller is called specific component reduction controller (SCRC). SCRC can function without an accelerometer and can achieve speed variable control. This study mainly comprises the following phases. First, the position sensorless control method will be provided. Second, the frame vibration model and load torque ripple will be shown. Third, SCRC will be discussed and its stability will be analyzed. Finally, experimental results show that SCRC can achieve speed variable anti-vibration control and compensate target frequency torque ripple.

Micro Galvanic Cell To Generate PtO and Extend the Triple-Phase Boundary during Self-Assembly of Pt/C and Nafion for Catalyst Layers of PEMFC

Long, Zhi,Gao, Liqin,Li, Yankai,Kang, Baotao,Lee, Jin Yong,Ge, Junjie,Liu, Changpeng,Ma, Shuhua,Jin, Zhao,Ai, Hongqi American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.44

<P>The self-assembly powder (SAP) with varying Nafion content was synthesized and characterized by XRD, XPS, HRTEM, and mapping. It is observed that the oxygen from oxygen functional groups transfers to the surface of Pt and generate PtO during the process of self-assembly with the mechanism of micro galvanic cell, where Pt, carbon black, and Nafion act as the anode, cathode and electrolyte, respectively. The appearance of PtO on the surface of Pt leads to a turnover of Nafion structure, and therefore more hydrophilic sulfonic groups directly contact with Pt, and thus the triple-phase boundary (TPB) has been expanded.</P>

Effects of Microbiota on the Treatment of Obesity with the Natural Product Celastrol in Rats

Weiyue Hu,Lingling Wang,Guizhen Du,Quanquan Guan,Tianyu Dong,Ling Song,Yankai Xia,Xinru Wang 대한당뇨병학회 2020 Diabetes and Metabolism Journal Vol.44 No.5

Background: Obesity has become one of the most serious issues threatening the health of humankind, and we conducted this study to examine whether and how celastrol protects against obesity. Methods: We fed male Sprague-Dawley rats a high-fat diet and administered celastrol to obese rats for 3 weeks. By recording body weight (BW) and other measures, we identified the effective dose of celastrol for obesity treatment. Feces were collected to perform 16S rRNA sequencing, and hypothalami were extracted for transcriptome sequencing. We then treated leptin knockout rats with celastrol and explored the changes in energy metabolism. Male Institute of Cancer Research (ICR) mice were used to test the acute toxicity of celastrol. Results: We observed that celastrol reduced BW and promoted energy expenditure at a dose of 500 μg/kg BW but that food intake was not changed after administration. The diversity of the gut microbiota was improved, with an increased ratio of Bacteroidetes to Firmicutes, and the gut microbiota played an important role in the anti-obesity effects of celastrol. Hypothalamic transcriptome analysis showed a significant enrichment of the leptin signaling pathway, and we found that celastrol significantly enhanced energy expenditure, which was mediated by the leptin signaling pathway. Acute lethal toxicity of celastrol was not observed at doses ranging from 0 to 62.5 mg/kg BW. Conclusion: Our study revealed that celastrol decreased the BW of obese rats by enhancing energy expenditure but not by suppressing food intake and that this effect was mediated by the improvement of the gut microbiota and the activation of the hypothalamic leptin signaling pathway.

Experimental Study of Rubber-Concrete-Filled CST Composite Column Under Axial Compression

Baodong Liu,Linlin Zhang,Mingyang Feng,Haibo Sun,Yankai Chai 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.1

Rubber concrete has been proposed to address the environmental challenges caused by waste tires and the shortage of natural aggregates worldwide; however, its strength and elastic modulus reduction hinder its wide application in structure members. This study proposes filling corrugated steel tubes with rubber concrete (RuCFCST) and using the non-uniform confinement provided by corrugated steel tubes (CSTs) to compensate for the loss in strength and elastic modulus of rubber concrete. We conducted monotonic axial compression tests on 12 tubular specimens to evaluate the effects of the steel tube type, loading mode, diameter-to-thickness ratio, and rubber concrete strength on the axial shortening behavior and strength. The test results confirmed the effectiveness of CST confinement in strengthening the axial behavior of rubber concrete and CST had a higher confinement efficiency than plain straight steel tubes. The strength and ductility indices of the specimens increased by 10% and 30%, respectively; however, the strength of the concrete core decreased by 38.4% owing to the incorporation of rubber particles. These results suggest that such columns can be used in infrastructure, such as in seismic bridge piers, mine roadway supports, and underground structural columns, where load-bearing capacity and ductility are required. The current specifications lack consistency in predicting the axial strength of RuCFCST columns and the results of our proposed modified formulas were in good agreement with the experimental data, and the formulas predicted the axial strength of piers well.