γ-Fe₂O₃ nanoparticles aligned in porous carbon nanofibers towards long life-span lithium ion batteries

Chen, Yujie,Zhao, Xiaohui,Liu, Ying,Razzaq, Amir Abdul,Haridas, Anupriya K.,Cho, Kwon-Koo,Peng, Yang,Deng, Zhao,Ahn, Jou-Hyeon Elsevier 2018 ELECTROCHIMICA ACTA Vol.289 No.-

<P><B>Abstract</B></P> <P>A freestanding γ-Fe<SUB>2</SUB>O<SUB>3</SUB>/carbon nanofiber composite as the anode of lithium ion batteries has been prepared with γ-Fe<SUB>2</SUB>O<SUB>3</SUB> nanoparticles aligned in the tubular channels of the nanofibrous carbon matrix. Innovatively, a large amount of voids are generated for confining a very high active mass content by facilely verifying the ratio of carbon source and the sacrificing pore-forming agent, poly(methyl methacrylate). The best electrochemical performance at an active mass ratio of 70% is obtained with a high discharge capacity of 1088 mAh g<SUP>−1</SUP> retained after 300 cycles at 0.2 C. Good rate capability and long life-span performance are further achieved at 0.5 and 2 C for 600 and 1000 cycles, respectively. <I>In situ</I> X-ray patterns further reveal better exploitation of the active materials for this γ-Fe<SUB>2</SUB>O<SUB>3</SUB>/carbon nanofiber composite electrode. The enhanced electrochemical performance of lithium ion batteries can be ascribed to the well-dispersed γ-Fe<SUB>2</SUB>O<SUB>3</SUB> nanoparticles within the porous carbon matrix, as well as the cross-linked fiber morphology. Consequently, this study provides a superior electrode architecture for constructing flexible anodes of high-performance lithium ion batteries.</P> <P><B>Graphical abstract</B></P> <P>The freestanding γ-Fe<SUB>2</SUB>O<SUB>3</SUB>/carbon nanofiber composite with hierarchical porous structure promotes the development of long life-span lithium ion batteries.</P> <P>[DISPLAY OMISSION]</P>

Determination of ginsenosides in Asian and American ginsengs by liquid chromatography-quadrupole/time-of-flight MS: assessing variations based on morphological characteristics

Chen, Yujie,Zhao, Zhongzhen,Chen, Hubiao,Brand, Eric,Yi, Tao,Qin, Minjian,Liang, Zhitao The Korean Society of Ginseng 2017 Journal of Ginseng Research Vol.41 No.1

Background: Asian ginseng and American ginseng are functional foods that share a close genetic relationship and are well-known worldwide. This article aims to investigate the correlation between morphological characteristics and the inherent quality of Asian and American ginsengs. Methods: In this study, an ultra-HPLC-quadrupole/time-of-flight MS (UHPLC-Q/TOF-MS) method was established for the quantitative analysis of 45 ginseng samples. The method developed for determination was precise and accurate. Results: The results showed that Asian ginseng samples with the same growing time (with the same or similar number of stem scars) that had a thinner main root, a longer rhizome and more branch roots contained greater amounts of ginsenosides. For American ginseng, two tendencies were observed in the relationship between the diameter of the main root and contents of ginsenosides. One tendency was that samples with thinner main roots tended to contain higher levels of ginsenosides, which was observed in the samples sold under the commercial name pao-shen. Another tendency was that samples with thicker main roots contained higher contents of ginsenosides, which was observed in the samples sold under the commercial name pao-mian, as well as in samples of American ginseng cultivated in Jilin, China. Conclusion: An approach using ultra-HPLC-quadrupole/time-of-flight MS was successfully established to link morphology and active components for evaluating the quality of Asian and American ginsengs. Clear correlation between visible morphological features and quality of Asian and American ginsengs was found. People can see the difference; this means consumers and vendors can evaluate ginseng by themselves.

Experimental study of a pretensioned connection for modular buildings

Yujie Yu,Zhihua Chen,Aoyi Chen 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.31 No.3

Modular steel buildings consist of prefabricated room-sized structural units that are manufactured offsite and installed onsite. The inter-module connections must fulfill the assembly construction requirements and soundly transfer the external loads. This work proposes an innovative assembled connection suitable for modular buildings with concrete-filled steel tube columns. The connection uses pretensioned strands and plugin bars to vertically connect the adjacent modular columns. The moment-transferring performance of this inter-module connection was studied through monotonic and cyclic loading tests. The results showed that because of the assembly construction, the connected sections were separated under lateral bending, and the prestressed inter-module connection performed as a weak semirigid connection. The moment strength at the early loading stage originated primarily from the contact bonding mechanism with the infilled concrete, and the postyield strength depended mainly on the tensioned strands. The connection displayed a self-centering-like behavior that the induced deformation was reversed during unloading. The energy dissipation originated primarily from frictional slipping of the plugin bars and steel strands. The moment transferring ability was closely related to the section dimension and the arrangements of the plugin bars and steel strands. A simplified strength calculation and evaluation method was also proposed, and the effectiveness was validated with the test data.

NLRP3-dependent lipid droplet formation contributes to posthemorrhagic hydrocephalus by increasing the permeability of the blood–cerebrospinal fluid barrier in the choroid plexus

Zhang Zhaoqi,Guo Peiwen,Liang Liang,Jila Shiju,Ru Xufang,Zhang Qiang,Chen Jingyu,Chen Zhi,Feng Hua,Chen Yujie 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-

Hydrocephalus is a severe complication that can result from intracerebral hemorrhage, especially if this hemorrhage extends into the ventricles. Our previous study indicated that the NLRP3 inflammasome mediates cerebrospinal fluid hypersecretion in the choroid plexus epithelium. However, the pathogenesis of posthemorrhagic hydrocephalus remains unclear, and therapeutic strategies for prevention and treatment are lacking. In this study, an Nlrp3−/− rat model of intracerebral hemorrhage with ventricular extension and primary choroid plexus epithelial cell culture were used to investigate the potential effects of NLRP3-dependent lipid droplet formation and its role in the pathogenesis of posthemorrhagic hydrocephalus. The data indicated that NLRP3-mediated dysfunction of the blood–cerebrospinal fluid barrier (B-CSFB) accelerated neurological deficits and hydrocephalus, at least in part, through the formation of lipid droplets in the choroid plexus; these lipid droplets interacted with mitochondria and increased the release of mitochondrial reactive oxygen species that destroyed tight junctions in the choroid plexus after intracerebral hemorrhage with ventricular extension. This study broadens the current understanding of the relationship among NLRP3, lipid droplets and the B-CSFB and provides a new therapeutic target for the treatment of posthemorrhagic hydrocephalus. Strategies to protect the B-CSFB may be effective therapeutic approaches for posthemorrhagic hydrocephalus.

Gyral net: A new representation of cortical folding organization

Chen, Hanbo,Li, Yujie,Ge, Fangfei,Li, Gang,Shen, Dinggang,Liu, Tianming Elsevier 2017 Medical image analysis Vol.42 No.-

<P><B>Abstract</B></P> <P>One distinct feature of the cerebral cortex is its convex (gyri) and concave (sulci) folding patterns. Due to the remarkable complexity and variability of gyral/sulcal shapes, it has been challenging to quantitatively model their organization patterns. Inspired by the observation that the lines of gyral crests can form a connected graph on each brain hemisphere, we propose a new representation of cortical gyri/sulci organization pattern – gyral net, which models cortical architecture from a graph perspective, starting with nodes and edges obtained from the reconstructed cortical surfaces. A novel computational framework is developed to efficiently and automatically construct gyral nets from surface meshes, and four measurements are devised to quantify the folding patterns. Using an MRI dataset for autism study as a test bed, we identified reduced local connectivity cost and increased curviness of gyral net bilaterally on the parietal lobe, occipital lobe, and temporal lobe in autistic patients. Additionally, we found that the cortical thickness and the gyral straightness of gyral joints are higher than the rest of gyral crest regions. The proposed representation offers a new tool for a comprehensive and reliable characterization of the cortical folding organization. This novel computational framework will enable large-scale analyses of cortical folding patterns in the future.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new representation of cortical gyri/sulci organization pattern. </LI> <LI> A novel framework to efficiently and automatically construct gyral net from mesh surface. </LI> <LI> A new tool for a comprehensive and reliable characterization of the cortical folding organization. </LI> <LI> Enable large-scale cortical folding pattern analyses in the future. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Illustration of the concept of gyral net and gyral joint. (a) Reconstructed cortical surface color-coded by gyral altitude. (b) Extracted gyral net. (c) Zoom in view of the circled area in (b). In this paper, we propose a new representation of cortical gyri/sulci organization pattern – gyral net, which models cortical architecture from a graph perspective, starting with nodes and edges obtained from the surface reconstructions.</P> <P>[DISPLAY OMISSION]</P>

AN IMPROVED METHOD FOR TRANSFERRING GRAPHENE GROWN BY CHEMICAL VAPOR DEPOSITION

YUJIE REN,CHAOFU ZHU,WEIWEI CAI,HUIFENG LI,YUFENG HAO,YAPING WU,SHANSHAN CHEN,QINGZHI WU,RICHARD D. PINER,RODNEY S. RUOFF 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.1

In this paper, we report an improved transfer of graphene by directly picking up the graphene with target substrates and the comparison of such transferred graphene samples with other graphene samples transferred by the commonly used "PMMA-based transfer" method. Raman spectroscopy studies show that this "direct transfer method" does not degrade the graphene structure and field effect transistor measurements show that it does not introduce any extra doping in graphene; in contrast, PMMA-based transfer samples have strong n-type doping. We also find that graphene samples achieved by this direct transfer method show higher mobility than graphene obtained from the PMMA-based transfer method.

Block Sparse Signals Recovery Algorithm for Distributed Compressed Sensing Reconstruction

Chen, Xingyi,Zhang, Yujie,Qi, Rui Korea Information Processing Society 2019 Journal of information processing systems Vol.15 No.2

Distributed compressed sensing (DCS) states that we can recover the sparse signals from very few linear measurements. Various studies about DCS have been carried out recently. In many practical applications, there is no prior information except for standard sparsity on signals. The typical example is the sparse signals have block-sparse structures whose non-zero coefficients occurring in clusters, while the cluster pattern is usually unavailable as the prior information. To discuss this issue, a new algorithm, called backtracking-based adaptive orthogonal matching pursuit for block distributed compressed sensing (DCSBBAOMP), is proposed. In contrast to existing block methods which consider the single-channel signal reconstruction, the DCSBBAOMP resorts to the multi-channel signals reconstruction. Moreover, this algorithm is an iterative approach, which consists of forward selection and backward removal stages in each iteration. An advantage of this method is that perfect reconstruction performance can be achieved without prior information on the block-sparsity structure. Numerical experiments are provided to illustrate the desirable performance of the proposed method.

Potential impact of flowback water from hydraulic fracturing on agricultural soil quality: Metal/metalloid bioaccessibility, Microtox bioassay, and enzyme activities

Chen, Season S.,Sun, Yuqing,Tsang, Daniel C.W.,Graham, Nigel J.D.,Ok, Yong Sik,Feng, Yujie,Li, Xiang-Dong Elsevier 2017 The Science of the total environment Vol.579 No.-

<P><B>Abstract</B></P> <P>Hydraulic fracturing has advanced the development of shale gas extraction, while inadvertent spills of flowback water may pose a risk to the surrounding environment due to its high salt content, metals/metalloids (As, Se, Fe and Sr), and organic additives. This study investigated the potential impact of flowback water on four representative soils from shale gas regions in Northeast China using synthetic flowback solutions. The compositions of the solutions were representative of flowback water arising at different stages after fracturing well establishment. The effects of solution composition of flowback water on soil ecosystem were assessed in terms of metal mobility and bioaccessibility, as well as biological endpoints using Microtox bioassay (<I>Vibrio fischeri</I>) and enzyme activity tests. After one-month artificial aging of the soils with various flowback solutions, the mobility and bioaccessibility of As(V) and Se(VI) decreased as the ionic strength of the flowback solutions increased. The results inferred a stronger binding affinity of As(V) and Se(VI) with the soils. Nevertheless, the soil toxicity to <I>Vibrio fischeri</I> only presented a moderate increase after aging, while dehydrogenase and phosphomonoesterase activities were significantly suppressed with increasing ionic strength of flowback solutions. On the contrary, polyacrylamide in the flowback solutions led to higher dehydrogenase activity. These results indicated that soil enzyme activities were sensitive to the composition of flowback solutions. A preliminary human health risk assessment related to As(V) suggested a low level of cancer risk through exposure via ingestion, while holistic assessment of environmental implications is required.</P> <P><B>Highlights</B></P> <P> <UL> <LI> High ionic strength of flowback water reduced mobility of metalloids. </LI> <LI> Relatively high bioaccessibility of metalloids in spite of low mobility </LI> <LI> Soil toxicity moderately increased after 1-month aging with flowback water. </LI> <LI> Soil dehydrogenase activity was affected by PAM in flowback water. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Insights into the subsurface transport of As(V) and Se(VI) in produced water from hydraulic fracturing using soil samples from Qingshankou Formation, Songliao Basin, China

Chen, Season S.,Sun, Yuqing,Tsang, Daniel C.W.,Graham, Nigel J.D.,Ok, Yong Sik,Feng, Yujie,Li, Xiang-Dong Elsevier 2017 Environmental pollution Vol.223 No.-

<P><B>Abstract</B></P> <P>Produced water is a type of wastewater generated from hydraulic fracturing, which may pose a risk to the environment and humans due to its high ionic strength and the presence of elevated concentrations of metals/metalloids that exceed maximum contamination levels. The mobilization of As(V) and Se(VI) in produced water and selected soils from Qingshankou Formation in the Songliao Basin in China were investigated using column experiments and synthetic produced water whose quality was representative of waters arising at different times after well creation. Temporal effects of produced water on metal/metalloid transport and sorption/desorption were investigated by using HYDRUS-1D transport modelling. Rapid breakthrough and long tailings of As(V) and Se(VI) transport were observed in Day 1 and Day 14 solutions, but were reduced in Day 90 solution probably due to the elevated ionic strength. The influence of produced water on the hydrogeological conditions (i.e., change between equilibrium and non-equilibrium transport) was evidenced by the change of tracer breakthrough curves before and after the leaching of produced water. This possibly resulted from the sorption of polyacrylamide (PAM (-CH<SUB>2</SUB>CHCONH<SUB>2</SUB>-)<SUB>n</SUB>) onto soil surfaces, through its use as a friction reducer in fracturing solutions. The sorption was found to be reversible in this study. Minimal amounts of sorbed As(V) were desorbed whereas the majority of sorbed Se(VI) was readily leached out, to an extent which varied with the composition of the produced water. These results showed that the mobilization of As(V) and Se(VI) in soil largely depended on the solution pH and ionic strength. Understanding the differences in metal/metalloid transport in produced water is important for proper risk management.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Earlier breakthrough of metals with increasing ionic strength of flowback solutions. </LI> <LI> Two-region physical non-equilibrium model provided a good fit of metal transport. </LI> <LI> Less non-equilibrium transport in Day 14 and Day 90 than Day 1 flowback solutions. </LI> <LI> Tracer tests indicated reversible change of transport channels due to leaching. </LI> <LI> Sorption/desorption of As(V) and Se(VI) was both pH- and ionic strength-dependent. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Block Sparse Signals Recovery Algorithm for Distributed Compressed Sensing Reconstruction

Xingyi Chen,Yujie Zhang,Rui Qi 한국정보처리학회 2019 Journal of information processing systems Vol.15 No.2

Distributed compressed sensing (DCS) states that we can recover the sparse signals from very few linearmeasurements. Various studies about DCS have been carried out recently. In many practical applications, thereis no prior information except for standard sparsity on signals. The typical example is the sparse signals haveblock-sparse structures whose non-zero coefficients occurring in clusters, while the cluster pattern is usuallyunavailable as the prior information. To discuss this issue, a new algorithm, called backtracking-based adaptiveorthogonal matching pursuit for block distributed compressed sensing (DCSBBAOMP), is proposed. Incontrast to existing block methods which consider the single-channel signal reconstruction, the DCSBBAOMPresorts to the multi-channel signals reconstruction. Moreover, this algorithm is an iterative approach, whichconsists of forward selection and backward removal stages in each iteration. An advantage of this method isthat perfect reconstruction performance can be achieved without prior information on the block-sparsitystructure. Numerical experiments are provided to illustrate the desirable performance of the proposed method.