Rationally designed hybrids of NiCo₂O₄ and polymeric carbon nitride as faradaic electrodes with enhanced electrochemical performance

Wang, Zhonghao,Hu, Xun,Wang, Lina,Jin, Bingjun,Zou, Guojun,Huang, Zhiwei,Liu, Qing,Hu, Guangzhi,Zhang, Kan,Park, Jong Hyeok Elsevier 2019 ELECTROCHIMICA ACTA Vol.299 No.-

<P><B>Abstract</B></P> <P>Herein, electrochemically sluggish polymeric carbon nitride (PCN) is successfully introduced into NiCo<SUB>2</SUB>O<SUB>4</SUB> to form hybrids of NiCo<SUB>2</SUB>O<SUB>4</SUB> and PCN, in which PCN nanosheets are regarded as a substrate to promote the nucleation and subsequent in-situ growth of NiCo<SUB>2</SUB>O<SUB>4</SUB> nanosheets. The surface of as-prepared hybrids are rich in Ni and Co ions in low and high valence state, respectively. In addition, the hybrids exhibit more hydrophilic compared with that of pristine NiCo<SUB>2</SUB>O<SUB>4</SUB> due to its higher amounts of hydroxyl group. It has been found that the nitrogen species originated from PCN nanosheets tend to bond with the metal ions and electrolyte used, resulting in tuning the electronic structural states and coupling effects with NiCo<SUB>2</SUB>O<SUB>4</SUB> nanosheets. Owing to these structural characteristics, the electrochemical performance as faradaic electrode materials and long-term stability of optimized hybrid is much superior to the bare NiCo<SUB>2</SUB>O<SUB>4</SUB> nanosheets.</P> <P><B>Highlights</B></P> <P> <UL> <LI> NiCo<SUB>2</SUB>O<SUB>4</SUB>-PCN samples were prepared via a facile and scalable strategy. </LI> <LI> The NiCo<SUB>2</SUB>O<SUB>4</SUB>-PCN-40 exhibited much higher supercapacitor performance than that of pure NiCo<SUB>2</SUB>O<SUB>4</SUB>. </LI> <LI> The PCN nanosheets can promote the nucleation and subsequent in-situ growth of NiCo<SUB>2</SUB>O<SUB>4</SUB> nanosheets in oriented way. </LI> <LI> The presence of PCN can tune the electronic structural states and coupling effects with NiCo<SUB>2</SUB>O<SUB>4</SUB> nanosheets. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>The vertically growth of NiCo<SUB>2</SUB>O<SUB>4</SUB> on PCN nanosheets substrate with 3D open frameworks synthesized here is beneficial for facilitating electrolyte ions transport and electron trapping, thus boosting the supercapacitor performance of NiCo<SUB>2</SUB>O<SUB>4</SUB>.</P> <P>[DISPLAY OMISSION]</P>

Effect of asymmetrical tip clearances on energy performance and cavitation characteristics of NACA0009 hydrofoil in tidal energy

Like Wang,Xingqi Luo,Jinling Lu,Jianjun Feng,Guojun Zhu,Wei Wang,Kai Wang 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9

Tidal energy is an important renewable energy that uses the potential energy created by the rising and falling of ocean tides to generate electricity. The tip leakage vortex (TLV) and cavitation caused by the tip leakage flow have adverse effects on the energy conversion efficiency and stable operation of the tubular turbine. The selection of the tip clearance shape is critical. Therefore, the effects of four different combinations of asymmetrical tip clearance shapes on the energy and cavitation characteristics of hydrofoils are studied in this paper. The results show that the TLV remains unchanged when tipwall and endwall are sinusoidal and cosine curve shaped, respectively. When tip clearance is the combination of a flat tipwall and a sinusoidal endwall, the lift-drag ratio decreases by 10.72 %. The high shear stress region of tipwall near leading edge decreases. The flow resistance of the leakage flow decreases, and the leakage flow becomes more serious. The cavitation volume is 2.5 times that under the original flat tip clearance. When tip clearance is the combination of a flat tipwall and a cosine endwall, and the lift-drag ratio increases by 9.67 %. The shear stress increases, the leakage flow decreases. The swirling strength around the center of the vortex core is weakened. The cavitation volume is 3.81, with a decrease of nearly 30 %. A proper asymmetrical tip clearance can effectively improve the energy performance and cavitation characteristics of hydrofoils. This study provides theoretical support for the design and optimization of hydraulic machine with tip clearance.

A brain somatic RHEB doublet mutation causes focal cortical dysplasia type II

Shanshan Zhao,Zhenghui Li,Muxian Zhang,Lingliang Zhang,Honghua Zheng,Jinhuan Ning,Yanyan Wang,Feng-Peng Wang,Xiaobin Zhang,Hexia Gan,Yuanqing Wang,Xian Zhang,Hong Luo,Guojun Bu,Huaxi Xu,Yi Yao,Yun-wu 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-

Focal cortical dysplasia type II (FCDII) is a cerebral cortex malformation characterized by local cortical structure disorganization, neuronal dysmorphology, and refractory epilepsy. Brain somatic mutations in several genes involved in the PI3K/AKT/mTOR pathway are associated with FCDII, but they are only found in a proportion of patients with FCDII. The genetic causes underlying the development FCDII in other patients remain unclear. Here, we carried out whole exome sequencing and targeted sequencing in paired brain–blood DNA from patients with FCDII and identified a brain somatic doublet mutation c.(A104T, C105A) in the Ras homolog, mTORC1 binding (RHEB) gene, which led to the RHEB p.Y35L mutation in one patient with FCDII. This RHEB mutation carrier had a dramatic increase of ribosomal protein S6 phosphorylation, indicating mTOR activation in the region of the brain lesion. The RHEB p.Y35L mutant protein had increased GTPλS-binding activity compared with wild-type RHEB. Overexpression of the RHEB p. Y35L variant in cultured cells also resulted in elevated S6 phosphorylation compared to wild-type RHEB. Importantly, in utero electroporation of the RHEB p.Y35L variant in mice induced S6 phosphorylation, cytomegalic neurons, dysregulated neuron migration, abnormal electroencephalogram, and seizures, all of which are found in patients with FCDII. Rapamycin treatment rescued abnormal electroencephalograms and alleviated seizures in these mice. These results demonstrate that brain somatic mutations in RHEB are also responsible for the pathogenesis of FCDII, indicating that aberrant activation of mTOR signaling is a primary driver and potential drug target for FCDII.

Neural Network and Data Fusion in the Application Research of Natural Gas Pipeline Leakage Detection

Bingkun Gao,Guojun Shi,Qing Wang 보안공학연구지원센터(IJSIP) 2013 International Journal of Signal Processing, Image Vol.6 No.6

Mitigation Effect of Waste Glass Powders on Alkali–Silica Reaction (ASR) Expansion in Cementitious Composite

Guojun Ke,Wengui Li,Ruyi Li,Yuelin Li,George Wang 한국콘크리트학회 2018 International Journal of Concrete Structures and M Vol.12 No.7

The effects of different contents and particle sizes of waste glass powder on alkali–silica reaction (ASR) expansion of cementitious composite bar were investigated in this study. Waste glass powder with particle size less than 300 ㎛ exhibits an excellent mitigation effect on ASR expansion. With larger content and smaller particle size, the mitigation effect of waste glass powder on ASR expansion gradually increases. The mitigation effect of waste glass powder with particle size ranging from 38 to 53 ㎛ and 20% by weight of cement seems relatively better than that of fly ash. When the waste glass powder content reaches 30%, the mitigation effect is still effective and almost the same as that of fly ash. However, the waste glass powder with particle size larger than 300 ㎛ presents negative mitigation effect on ASR expansion when the replacement rate is larger than 30%. On the other hand, the waste glass powder and calcium hydroxide (CH) further react, and produce more calcium–silicate–hydrate gels, which apparently reduce the amount of CH. Moreover, the increasing content of waste glass powder results in a lower pH value in the pore solution of cementitious composite.

Feeding behavior of the notorious invasive Mealybug, Phenacoccus solenopsis to exotic weeds using EPG

Wang Qianjin,Qi Guojun,He Yurong,Lyu Lihua 한국응용곤충학회 2023 Journal of Asia-Pacific Entomology Vol.26 No.2

The cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is notorious for causing severe economic losses to a wide range of crop species. It is noteworthy that this mealybug performed different host preference and fitness within their host range. In order to determine the preference of P. solenopsis between economic plants and weeds, the feeding behavior of cotton mealybug on three widespread exotic weeds belong to Asteraceae family (Bidens pilosa L., Wedelia trilobata and Ambrosia artemisiifolia.) were determined and compared with cotton Gossypium hirsutum L. using electrical penetration graph (EPG). Compared with G. hirsutum, cotton mealybug took the shortest time for trying/detecting on leaf surface and spend the longest duration times for ingestion from phloem bundle tissues feeding on A. artemisiifolia. Results showed that A. artemisiifolia was the most adaptable host for cotton mealybug, B. pilosa and W. trilobata were less suitable ones, implying these plants vulnerable to damage by this mealybug. This consequence gave more evidence for the feeding harm of P. solenopsis and might provide a scientific basis for explain if exotic weeds play an important role in the regional dispersal, and exist as transfer host for pest divert to farmland during uncultivated season.

Controllable Synthesis of Silver Nanoparticles Using Piezoelectric-Actuated High-Frequency Vibration Self-Circulating Microfluidic Reactor

Guojun Liu,Fang He,Yan Li,Xinbo Li,Hong Zhao,Conghui Wang,Conghong Zhan,Chunxiu Tang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.8

Based on the liquid-phase reduction mechanism, a controllable synthesis method, which uses piezoelectric-actuated high-frequency vibration self-circulating microfluidic reactor, to prepare silver nanoparticles is proposed. Firstly, the synthesis mechanism of silver nanoparticles and the working principle of the microfluidic reactor were analyzed. Then, in order to study and explore the influence of self-circulating and high frequency vibration on the synthesis of silver nanoparticles, a series of related synthesis experiments were carried out. The synthesized silver nanoparticles were characterized by UV-Visible spectroscopy and transmission electron microscopy. The effects of micropump driving voltage and high-frequency vibration on the synthesis of silver nanoparticles were analyzed. The experiment results show that when the silver nanoparticles were synthesized using piezoelectric-actuated high-frequency vibration self-circulating microfluidic reactor, the higher the driving voltage of the circulating reflux micropump, the faster the vortex rotation speed in the mixing pool and the more uniform the reagent reaction. Besides, high-frequency vibration can suppress the aggregation of silver nanoparticles, and balance the growth environment of particles, which is beneficial to the formation of silver nanoparticles with good monodispersity, high sphericity and small size deviation.

Mechanical and Microscopic Properties of Copper-contaminated Soil Solidified with Calcium Carbide Residue, Metakaolin, and Desulfurization Gypsum under Freeze-thaw Cycles

Qiang Wang,Dandan Ge,Guojun Cai,Man Li,Liuyan Wu,Huangrui Xu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.2

The solidification/stabilization effect of heavy metal contaminated soils in frozen soil regions may be weakened. A novel binder comprising calcium carbide residue, metakaolin, and desulfurization gypsum was used to solidify and stabilize copper-contaminated soil subjected to freeze-thaw (F-T) cycles. The unconfined compressive strength (UCS), F-T cycles, scanning electron microscope (SEM), X-ray diffraction (XRD), and pH tests were conducted to investigate the characteristics of UCS, deformation, pH value, and microscopic mechanism of contaminated soils. The results demonstrated that the UCS of contaminated soils decreased with the increasing F-T cycles and Cu2+ concentration; the strength loss rate increased first and then decreased as the F-T cycles increased. The failure strain rose first and then reduced with the increase of F-T cycles, and increased with the rise of Cu2+ concentration. There was a considerable correlation between UCS, failure strain, and deformation modulus E50. The pH value decreased with the increasing F-T cycles and Cu2+ concentration. The microscopic characteristics indicated that the formation of hydrated calcium silicate and ettringite was the fundamental reason for the enhanced UCS. Besides, heavy metals could be solidified and stabilized by chemical precipitation, physical encapsulation, and ion exchange. The effect of F-T cycles could significantly damage the internal structure of contaminated soils, and the frost heaving force could loosen the soil skeleton structure, leading to the deterioration of the mechanical properties.

Air Recirculation and Its Effect on Microfiber Spinning in Blunt-Die Melt Blowing

Sheng Xie,Guojun Jiang,Xianyan Wu,Yaping Wang,Haisu Fang,Baoqing Shentu 한국섬유공학회 2021 Fibers and polymers Vol.22 No.3

In the present work, approaches of the Computational Fluid Dynamics (CFD) simulation, the Particle ImageVelocimetry (PIV) measurement, and the spinning experiment were applied to investigate the phenomenon of air recirculation inblunt-die melt-blown airflow. Firstly, the characteristics of air recirculation were explored by CFD simulation. The simulationresults predicted that the air recirculation generated a lateral air velocity along the nose-piece direction. Then, the aircirculation was experimental verified by using PIV technique. The PIV results confirmed the predicted conclusions of CFDsimulation. Finally, the effect of air recirculation on the microfiber spinning during the melt-blown process was experimentallyinvestigated by a spinning experiment using a blunt die with nose-piece width of 2.56 mm. The spinning results indicated thatthe air circulation had a tendency of splitting the normal polymeric stream, which played negative effect on the continuity ofmicrofiber spinning. This work is expected to provide some clues to melt-blown die design and the quality control ofnonwoven products.

Market analysis of VC insurance

Kang Yi,Wang Guojun 인하대학교 정석물류통상연구원 2009 인하대학교 정석물류통상연구원 학술대회 Vol.2009 No.10

VC insurance is still developing slowly even with rapid developments of VC and insurance industries. In this paper the current situation of VC insurance is introduced from points of market demand and supply, and a conclusion is made that VC insurance is in great imbalances with greater demands and less supplies especially for technology and credit risks. Peasons for the demand-supply imbalances in VC insurance are mainly high failure rate of VC and difficulties in innovations management in. Finally, the following propopals are made that both VC and insurance industries should improve the assessment in innovation and strengthern the risk management to promote the VC insurance.