V₂O₅ xerogel electrodes with much enhanced lithium-ion intercalation properties with N₂ annealing

Liu, Dawei,Liu, Yanyi,Garcia, Betzaida Batalla,Zhang, Qifeng,Pan, Anqiang,Jeong, Yoon-Ha,Cao, Guozhong The Royal Society of Chemistry 2009 Journal of materials chemistry Vol.19 No.46

<p>V<SUB>2</SUB>O<SUB>5</SUB> xerogel films were fabricated by casting V<SUB>2</SUB>O<SUB>5</SUB> sols onto FTO glass substrates and annealing at 300 °C for 3 hours in nitrogen and air. The films annealed in nitrogen and air possessed different grain size and crystallinity. Optical absorption measurements and electrochemical impedance analyses revealed a reduced optical bandgap and enhanced electrical conductivity of N<SUB>2</SUB> annealed V<SUB>2</SUB>O<SUB>5</SUB> film. Lithium ion intercalation measurements showed that at a charge/discharge current density of 600 mAg<SUP>−1</SUP>, the N<SUB>2</SUB> annealed sample possessed noticeably better lithium ion storage capability. In contrast to the air annealed sample, which started with a discharge capacity of 152 mAhg<SUP>−1</SUP> but after 50 cycles the capacity had decreased to a low value of only 44 mAhg<SUP>−1</SUP>, the N<SUB>2</SUB> annealed sample started with a low value of 68 mAhg<SUP>−1</SUP> but the capacity increased sharply to a high value of 158 mAhg<SUP>−1</SUP> at the 24<SUP>th</SUP> cycle, followed by little capacity degradation in later cycles and after 50 cycles, the discharge capacity was still as high as 148 mAhg<SUP>−1</SUP>. Much improved lithium ion intercalation capacity and cyclic stability could be attributed to surface defects V<SUP>4+</SUP> and/or V<SUP>3+</SUP> and associated oxygen vacancies introduced by N<SUB>2</SUB> annealing as well as much less crystallized vanadium oxide.</p> <P>Graphic Abstract</P><P>V<SUB>2</SUB>O<SUB>5</SUB> films annealed in N<SUB>2</SUB> exhibited a much improved lithium ion intercalation capability as compared to counterparts annealed in air, highly favoring potential application as lithium ion battery electrodes. <img src='http://pubs.rsc.org/ej/JM/2009/b914436f/b914436f-ga.gif'> </P>

A Bidirectional Dual Buck-Boost Voltage Balancer with Direct Coupling Based on a Burst-Mode Control Scheme for Low-Voltage Bipolar-Type DC Microgrids

Liu, Chuang,Zhu, Dawei,Zhang, Jia,Liu, Haiyang,Cai, Guowei The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6

DC microgrids are considered as prospective systems because of their easy connection of distributed energy resources (DERs) and electric vehicles (EVs), reduction of conversion loss between dc output sources and loads, lack of reactive power issues, etc. These features make them very suitable for future industrial and commercial buildings' power systems. In addition, the bipolar-type dc system structure is more popular, because it provides two voltage levels for different power converters and loads. To keep voltage balanced in such a dc system, a bidirectional dual buck-boost voltage balancer with direct coupling is introduced based on P-cell and N-cell concepts. This results in greatly enhanced system reliability thanks to no shoot-through problems and lower switching losses with the help of power MOSFETs. In order to increase system efficiency and reliability, a novel burst-mode control strategy is proposed for the dual buck-boost voltage balancer. The basic operating principle, the current relations, and a small-signal model of the voltage balancer are analyzed under the burst-mode control scheme in detail. Finally, simulation experiments are performed and a laboratory unit with a 5kW unbalanced ability is constructed to verify the viability of the bidirectional dual buck-boost voltage balancer under the proposed burst-mode control scheme in low-voltage bipolar-type dc microgrids.

The Combination of Platelet Rich Plasma Gel, Human Umbilical Mesenchymal Stem Cells and Nanohydroxyapatite/polyamide 66 Promotes Angiogenesis and Bone Regeneration in Large Bone Defect

Liu Wei,Huang Yong,Liu Daqian,Zeng Teng,Wang Jingzhe,Li Ang,Wang Dawei,Wang Xiaoyu 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.6

BACKGROUND: In the present study, a novel tissue engineering bone graft including platelet rich plasma gel (PRP gel), human umbilical mesenchymal stem cells (HUMSCs) and nanohydroxyapatite/polyamide 66 (nHA-PA66) was constructed. We explored whether the composite scaffolds could enhance the angiogenesis and bone repair capacity in rat femoral large bone defect (LBD). This study aimed to provide evidence for the clinical application of the composite scaffold in LBD treatment. METHODS: PRP was prepared, the platelets and growth factors were measured. HUMSCs were isolated and identified. the osteogenic capacity of PRP in vitro was measured. Then HUMSCs-PRP-gel/nHA-PA66 composite scaffolds were synthesized and observed. The proliferation and osteogenesis differentiation of HUMSCs on the composite scaffold was measured. The angiogenic capacity of PRP in vitro was measured by capillary-like tube formation assay. Finally, the angiogenesis and bone repair capacity of the composite scaffolds was measured in rat LBD. RESULTS: PRP contained high level of platelets and growth factors after activation, and promoted osteogenic and angiogenic differentiation in vitro. The HUMSCs-PRP-gel/nHA-PA66 composite scaffold was porosity and promoted the proliferation and osteogenesis differentiation of HUMSCs. At 12th weeks, more micro-vessels and new bone were formed around the composite scaffolds compared with other groups, the defect was almost repaired. CONCLUSION: Our study for the first time identified that the combination of PRP gel, HUMSCs and nHA-PA66 scaffold could significantly promote angiogenesis and bone regeneration in rat LBD, which may have implications for its further application in clinical LBD treatment.

Hypoglycemic effect of Gynostemma pentaphyllum saponins by enhancing the Nrf2 signaling pathway in STZ-inducing diabetic rats

Dawei Gao,Min Zhao,Ximing Qi,Yanping Liu,Nan Li,Zhiwei Liu,Yanhong Bian 대한약학회 2016 Archives of Pharmacal Research Vol.39 No.2

Gynostemma pentaphyllum (GP) is a natural plant resources for diabetes therapy, however, there is little research on the mechanisms of GP. The present study was undertaken to characterize if G. pentaphyllum saponins (GPs) is the principal active compound of GP responsible for anti-diabetes, and to examine the relativity between blood glucose modulate and antioxidation. The GPs-treated streptozotocin diabetic rats had a more effective hypoglycemic status than those of diabetic control rats, which also ameliorate dyslipidemia. GPs has increased SOD and GSH-px activities, and the spleen and thymus indexes in diabetic rats. The insulin levels in the GPs-treated groups were significantly higher than diabetic control group. Our finding provides a new insight into the application of GPs for the treatment of oxidative stress related diseases.

Effect of crumb rubber on compressive behaviour of CRCFST stub columns

Dawei Liu,Jiongfeng Liang,Guangwu Zhang,Jianbao Wang 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.25 No.3

This paper investigates the effect of crumb rubber (CR) on compressive behaviour of crumb rubber concrete filled steel tube (CRCFST) stub columns. Therefore, experiments on 16 stub columns subjected to axial loading are carried out. The results show that the failure modes of CRCFST stub columns with different CR replacement ratios and CR size are similar, manifested the buckling of the outer steel tube. The axial bearing capacity and stiffness both decrease with an increase in CR replacement ratio, and with decreasing CR size.

Mutually different tooth surface contact characteristics of a noncircular face gear with intersecting axes

Dawei Liu,Heng Li,Zhenzhen Lv,Yuetong Cao 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.4

The noncircular face gear (NFG) with intersecting axes is composed of a spur gear and a NFG, which can realize the reduced and variable-speed integrated transmission between any intersecting axes. To study the contact characteristics of NFG with intersecting axes, the mutually different tooth surface mathematical model of the NFG with intersecting axes was established, and a tooth surface analysis method based on rotational projection was innovatively proposed. By using this method, the distribution characteristics of contact traces on different tooth profiles can be accurately compared through establishing the comparison reference of the middle plane on gear teeth. At the same time, the effects of installation errors and eccentricity on the contact characteristics of tooth surface were analyzed in detail. Results demonstrate that the change in the same kind of installation error has the same effect on the offset direction of the contact traces on each gear tooth. Under the same installation error, changing the eccentricity of the NFG will cause different changes in the offset of the contact traces on each gear tooth. Finally, a gear transmission device of NFG with intersecting axes was designed and manufactured. The correctness of the contact model and the analysis results were proven by the gear pair rolling experiment, which provides a theoretical basis for the design and installation of NFG with intersecting axes.

Research on the Flame Simulation Method Based on the Particle System

Xumin Liu,Zilong Duan,Dawei Qian,Xiaojun Wang 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.12

In reality, flame is a common fluid scene. In this paper, we simulated flame by using improved particle system and detail the properties and changes of particles in the model. We realized a realistic color change and dynamic flickering flame characteristics. We used texture mapping method to render the flame and used the hierarchical programming structure to provide a simple and practical interactive flame simulation. We also designed and implemented demonstration system of flame simulation. Experiments show that using the flame image generated in this paper can not only satisfy the visual effect but also meet the real-time requirements.

A Bidirectional Dual Buck-Boost Voltage Balancer with Direct Coupling Based on a Burst-Mode Control Scheme for Low-Voltage Bipolar-Type DC Microgrids

Chuang Liu,Dawei Zhu,Jia Zhang,Haiyang Liu,Guowei Cai 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6

DC microgrids are considered as prospective systems because of their easy connection of distributed energy resources (DERs) and electric vehicles (EVs), reduction of conversion loss between dc output sources and loads, lack of reactive power issues, etc. These features make them very suitable for future industrial and commercial buildings’ power systems. In addition, the bipolar-type dc system structure is more popular, because it provides two voltage levels for different power converters and loads. To keep voltage balanced in such a dc system, a bidirectional dual buck-boost voltage balancer with direct coupling is introduced based on P-cell and N-cell concepts. This results in greatly enhanced system reliability thanks to no shoot-through problems and lower switching losses with the help of power MOSFETs. In order to increase system efficiency and reliability, a novel burst-mode control strategy is proposed for the dual buck-boost voltage balancer. The basic operating principle, the current relations, and a small-signal model of the voltage balancer are analyzed under the burst-mode control scheme in detail. Finally, simulation experiments are performed and a laboratory unit with a 5kW unbalanced ability is constructed to verify the viability of the bidirectional dual buck-boost voltage balancer under the proposed burst-mode control scheme in low-voltage bipolar-type dc microgrids.

Fault Diagnosis of Subsea Blowout Preventer Based on Artificial Neural Networks

Zengkai Liu,Yonghong Liu,Baoping Cai,Dawei Zhang,Junlei Li 보안공학연구지원센터 2014 International Journal of Security and Its Applicat Vol.8 No.2

Excessive copper in feed not merely undermines animal health but affects food safety

Zicheng Ma,Yan Li,Zifeng Han,Zhaohu Liu,Hongyu Wang,Fanliang Meng,Sidang Liu,Dawei Chen,Mengda Liu 대한수의학회 2021 Journal of Veterinary Science Vol.22 No.3

Background: Blackened intestines in slaughtered pigs have been commonly observed in China in recent years. However, no cause has been reported. Objectives: We attempted to determine whether the blackening of the pig intestine was related to an excess of copper (Cu) in their feed. Methods: In this study, we observed and collected porcine intestines in small- and large-scale pig slaughterhouses in Shandong province from May to October 2018. Twelve types of metal ions were detected in the black intestinal samples. Results: The Cu level in the intestine samples was mostly higher than the Chinese national limit for food. Further study showed that Cu supplementation in most commercial porcine feed also exceeded the national standard. An animal model (mouse) that could mimic the intestinal blackening in pigs was established. Compared to control mice, Cu accumulated in the liver and intestines of mice fed an excessive Cu level, confirming the excessive Cu in the feed may be considered the major cause of blackened porcine intestines. Microscopic examination revealed that black intestines had many particles containing Cu in the lamina propria of the intestinal mucosa, and the intestinal mucosal epithelial cells showed degeneration and necrosis. Conclusions: In conclusion, overuse of Cu in animal feed can lead to animal poisoning and Cu accumulation in animal products. Such overuse not only harms the health of livestock but can also affect public health.