A large-area free-standing graphene oxide multilayer membrane with high stability for nanofiltration applications

Chen, Long,Li, Yanhui,Chen, Lina,Li, Na,Dong, Chenglong,Chen, Qiong,Liu, Beibei,Ai, Qing,Si, Pengchao,Feng, Jinkui,Zhang, Lin,Suhr, Jonghwan,Lou, Jun,Ci, Lijie Elsevier 2018 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.345 No.-

<P><B>Abstract</B></P> <P>A flexible and free-standing graphene oxide and nylon 6 (GO@nylon 6) multilayer nanofiltration membrane was prepared by a layer-by-layer assembly process. The combination of electrospinning and electrospraying technique was employed, which can facilely prepare large-area membrane with size of 20 × 30 cm. The mechanical stability of multilayer membrane has enhanced significantly due to the tightly locked structure achieved by nylon 6 nanofibers network. The novel GO@nylon 6–13 multilayer nanofiltration membrane demonstrated a pure water flux up to 11.15 L m<SUP>−2</SUP> h<SUP>−1</SUP> bar<SUP>−1</SUP>, while keeping high organic dye rejection rate (>95% for methylene blue, and >99% for methyl orange). The rejections rate of the Na<SUB>2</SUB>SO<SUB>4</SUB>, NaCl, CuSO<SUB>4</SUB>, and Pb(NO<SUB>3</SUB>)<SUB>2</SUB> were 56.5%, 27.6%, 36.7%, and 18.9%, respectively. Furthermore, GO@nylon 6–13 multilayer nanofiltration membrane also demonstrated a high flux of some common organic solvents (8.4, 5.3, and 0.8 L m<SUP>−2</SUP> h<SUP>−1</SUP> bar<SUP>−1</SUP> for methanol, ethanol, and NMP, respectively), showing excellent chemical stability for separation process in those solvents.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Large-area GO@nylon 6 multilayer nanofiltration membrane was prepared. </LI> <LI> The multilayer structure enhances the mechanical stability. </LI> <LI> The multilayer membrane demonstrates a high water flux. </LI> <LI> The multilayer membrane shows high rejection rate for organic dyes. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Photograph and cross-section SEM image of GO@nylon 6 multilayer nanofiltration membrane, the inset shows the water contact angle.</P> <P>[DISPLAY OMISSION]</P>

Experimental study on the Influence of Heating Surface Inclination Angle on Heat Transfer and CHF performance for Pool Boiling

Chenglong Wang,Panxiao Li,Dalin Zhang,Wenxi Tian,Suizheng Qiu,G.H. Su,Jian Deng 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1

Pool boiling heat transfer is widely applied in nuclear engineering fields. The influence of heating surface orientation on the pool boiling heat transfer has received extensive attention. In this study, the heating surface with different roughness was adopted to conduct pool boiling experiments at different inclination angles. Based on the boiling curves and bubble images, the effects of inclination angle on the pool boiling heat transfer and critical heat flux were analyzed. When the inclination angle was bigger than 90°, the bubble size increased with the increase of inclination angle. Both the bubble departure frequency and critical heat flux decreased as the inclination angle increased. The existing theoretical models about pool boiling heat transfer and critical heat flux were compared. From the perspective of bubble agitation model and Hot/Dry spot model, the experimental phenomena could be explained reasonably. The enlargement of bubble not only could enhance the agitation of nearby liquid but also would cause the bubble to stay longer on the heating surface. Consequently, the effect of inclination angle on the pool boiling heat transfer was not conspicuous. With the increase of inclination angle, the rewetting of heating surface became much more difficult. It has negative effect on the critical heat flux. This work provides experimental data basis for heat transfer and CHF performance of pool boiling.

Neural Network-based Event-triggered Adaptive Asymptotic Tracking Control for Switched Nonlinear Systems

Chenglong Zhu,Baomin Li,Jianwei Xia,Na Zhang,Rui Liu 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.6

In this paper, an adaptive event-triggered asymptotic tracking control problem is addressed for switched nonlinear systems with unknown control directions. In existing control schemes, the proposed controller is not directly aimed at the original system, which affects the control performance. Different from the existing control schemes, based on the original system, an event-triggered control law is constructed in this paper. The proposed event-triggered controller guarantees that the tracking error ς1 asymptotically converges to the origin. Finally, the effectiveness of the proposed controller design scheme is proved by simulation examples.

Finite-time Secondary Frequency Modulation of Microgrid Based on Event Triggering Mechanism

Chenglong Zhou,Ze Li,Guozeng Cui,Yifan Chen,Wangjun Hao 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.4

This paper designs a ratio consistency algorithm based on event triggering mechanism aiming at the frequency recovery deviation caused by traditional droop control in microgrid. It achieves secondary frequency modulation in microgrid by adjusting the active power setting value. The max-min consistency algorithm is proposed to realize asymptotic consistency of distributed power supply in a finite time. Communication delay is added to ensure the accuracy of frequency update and verifies the robustness of the algorithm against itself. Meanwhile, the validity of event triggering conditions is verified. Finally, the simulation examples are carried out to prove the correctness and superiority of the proposed finite-time control strategy.

Full-space Cloud of Random Points with a Scrambling Metasurface

Li, Zile,Dai, Qi,Mehmood, Muhammad Q.,Hu, Guangwei,yanchuk, Boris Luk’,Tao, Jin,Hao, Chenglong,Kim, Inki,Jeong, Heonyeong,Zheng, Guoxing,Yu, Shaohua,Alù,, Andrea,Rho, Junsuk,Qiu, Cheng-Wei Nature Publishing Group UK 2018 Light, science & applications Vol.7 No.1

<▼1><P>With the rapid progress in computer science, including artificial intelligence, big data and cloud computing, full-space spot generation can be pivotal to many practical applications, such as facial recognition, motion detection, augmented reality, etc. These opportunities may be achieved by using diffractive optical elements (DOEs) or light detection and ranging (LIDAR). However, DOEs suffer from intrinsic limitations, such as demanding depth-controlled fabrication techniques, large thicknesses (more than the wavelength), Lambertian operation only in half space, etc. LIDAR nevertheless relies on complex and bulky scanning systems, which hinders the miniaturization of the spot generator. Here, inspired by a Lambertian scatterer, we report a Hermitian-conjugate metasurface scrambling the incident light to a cloud of random points in full space with compressed information density, functioning in both transmission and reflection spaces. Over 4044 random spots are experimentally observed in the entire space, covering angles at nearly 90°. Our scrambling metasurface is made of amorphous silicon with a uniform subwavelength height, a nearly continuous phase coverage, a lightweight, flexible design, and low-heat dissipation. Thus, it may be mass produced by and integrated into existing semiconductor foundry designs. Our work opens important directions for emerging 3D recognition sensors, such as motion sensing, facial recognition, and other applications.</P></▼1><▼2><P><B>Metasurfaces: scrambling light for 3D detection and recognition</B></P><P>Firing light at a manufactured 'metasurface'—one carrying patterns at a smaller scale than the wavelength of the light—fills large volumes of space with defined points of light, potentially improving 3-D recognition and sensor applications. Cheng-Wei Qui and colleagues at the National University of Singapore, with co-workers across Asia and in the USA, created their unique metasurface from amorphous silicon. Light is scattered from and transmitted through the material to generate a cloud of data points in the surrounding space in which the structure and motion of objects under study can be analyzed. The initial development work with this “scrambling metasurface” suggests it could improve pattern recognition, including face recognition, motion detection and augmented reality applications. The researchers describe how their innovation overcomes significant limitations of existing methods in these fields.</P></▼2>

Visualizing the distributions and spatiotemporal changes of metabolites in Panax notoginseng by MALDI mass spectrometry imaging

Chenglong Sun,Shuangshuang Ma,Lili Li,Daijie Wang,Wei Liu,Feng Liu,Lanping Guo,Xiao Wang 고려인삼학회 2021 Journal of Ginseng Research Vol.45 No.6

Background: Panax notoginseng is a highly valued medicinal herb used widely in China and many Asiancountries. Its root and rhizome have long been used for the treatment of cardiovascular and hematologicaldiseases. Imaging the spatial distributions and dynamics of metabolites in heterogeneous planttissues is significant for characterizing the metabolic networks of Panax notoginseng, and this will alsoprovide a highly informative approach to understand the complex molecular changes in the processing ofPanax notoginseng. Methods: Here, a high-sensitive MALDI-MS imaging method was developed and adopted to visualize thespatial distributions and spatiotemporal changes of metabolites in different botanical parts of Panaxnotoginseng. Results: A wide spectrum of metabolites including notoginsenosides, ginsenosides, amino acids, dencichine,gluconic acid, and low-molecular-weight organic acids were imaged in Panax notoginseng rhizomeand root tissues for the first time. Moreover, the spatiotemporal alterations of metabolites during thesteaming of Panax notoginseng root were also characterized in this study. And, a series of metabolitessuch as dencichine, arginine and glutamine that changed with the steaming of Panax notoginseng weresuccessfully screened out and imaged. Conclusion: These spatially-resolved metabolite data not only enhance our understanding of the Panaxnotoginseng metabolic networks, but also provide dire

Changes in distribution and morphology of Tamarix ramosissima nebkhas in an oasis-desert ecotone

Chaofan Li,Fan Yang,Xinqian Zheng,Zhangyong Han,Honglin Pan,Chenglong Zhou,Chunrong Ji 한국지질과학협의회 2021 Geosciences Journal Vol.25 No.5

In the oasis-desert ecotone, nebkhas are of great importance for blocking the intrusion of shifting sand and maintaining the ecological security of oases. The morphological characteristics of nebkhas have been widely researched. However, their spatial distribution and morphological variation with the environment remain unclear. In this paper, we systematically analyzed the spatial distribution pattern, morphological changes, and potential indicative significance of Tamarix ramosissima nebkhas (that is, nebkhas formed around T. ramosissima) in a typical oasis-desert ecotone in Northwest China. Our results showed that the intensity of aeolian activities increased from the inside to the outside of the ecotone, and only T. ramosissima shrubs with high tolerance to aeolian activities could survive. Moreover, from the inside to the outside of the ecotone, the density of the T. ramosissima nebkhas decreased, their size increased, and spatial distribution shifted from aggregation to random. The T. ramosissima shrub can trap aeolian transport and protect nebkhas, leading to sand accumulation in the space between, and leeward edges of, the shrubs. Wind erosion mainly occurs to the windward side and along the sides of the nebkhas. Further, the protective effect of the shrub gradually increased with its growth in a year, resulting in the gradually changed of nebkha surface from wind erosion to sand accumulation, and the nebkha volume showed a fluctuating state of first decreasing and then increasing. This indicates that wind erosion and sand accumulation on the nebkha surface were closely related to the growth cycle of the shrub. In addition, nebkhas exhibited a spatial pattern of growth, inside of the ecotone, to degradation, outside of the ecotone. These results indicate that we should focus on the outside of the ecotone to ensure the ecological stability of oases.

Clusterin negatively modulates mechanical stress-mediated ligamentum flavum hypertrophy through TGF-β1 signaling

Liu Chunlei,Li Peng,Ao Xiang,Lian Zhengnan,Liu Jie,Li Chenglong,Huang Minjun,Wang Liang,Zhang Zhongmin 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Ligamentum flavum hypertrophy (LFH) is a major cause of lumbar spinal canal stenosis (LSCS). The pathomechanisms for LFH have not been fully elucidated. Isobaric tags for relative and absolute quantitation (iTRAQ) technology, proteomics assessments of human ligamentum flavum (LF), and successive assays were performed to explore the effect of clusterin (CLU) upregulation on LFH pathogenesis. LFH samples exhibited higher cell positive rates of the CLU, TGF-β1, α-SMA, ALK5 and p-SMAD3 proteins than non-LFH samples. Mechanical stress and TGF-β1 initiated CLU expression in LF cells. Notably, CLU inhibited the expression of mechanical stress-stimulated and TGF-β1-stimulated COL1A2 and α-SMA. Mechanistic studies showed that CLU inhibited mechanical stress-stimulated and TGF-β1-induced SMAD3 activities through suppression of the phosphorylation of SMAD3 and by inhibiting its nuclear translocation by competitively binding to ALK5. PRKD3 stabilized CLU protein by inhibiting lysosomal distribution and degradation of CLU. CLU attenuated mechanical stress-induced LFH in vivo. In summary, the findings showed that CLU attenuates mechanical stress-induced LFH by modulating the TGF-β1 pathways in vitro and in vivo. These findings imply that CLU is induced by mechanical stress and TGF-β1 and inhibits LF fibrotic responses via negative feedback regulation of the TGF-β1 pathway. These findings indicate that CLU is a potential treatment target for LFH.

Expediting the Formation of Cellulose Nanopaper by Heterocoagulation of Oppositely Charged Cellulose Nanofibers

Meng Kang,Chenglong Li,Dehai Yu,Guodong Li,Zhaoping Song,Huili Wang,Wenxia Liu 한국섬유공학회 2022 Fibers and polymers Vol.23 No.7

Cellulose nanopaper has attracted tremendous attention as an alternative to fossil-based flexible substrates. However, the fabrication of nanopaper from cellulose nanofibers (CNFs) is a time-consuming process. Herein, positivelycharged CNFs (PCNFs) were employed to heterocoagulate negatively charged CNFs (NCNFs) at various PCNF-to-NCNFratios in order to decrease the formation time of nanopaper. At a PCNF-to-NCNF ratio of 1:1, the formation time was reducedfrom 98 min to 20 min. Although heterocoagulation increases the roughness of cellulose nanopaper, nanopapers made from amixture of NCNFs and PCNFs still possess a nanosized network structure and therefore show similar transparency tonanopapers made of pure NCNFs. Compared to the nanopaper made from pure NCNFs, the nanopaper made from themixture of NCNFs and PCNFs showed reduced tensile strength but improved resistance to deformation. This study providesa practical method for the production of cellulose nanopaper.

The “living” Feature of the ATRP Macroinitiators in Different Catalytic Systems

Yazhen Wang,Li Liu,Shaobo Dong,Xilai Zhou,Chenglong Wang,Zhen Shi 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.2

Atom transfer radical polymerization (ATRP) has achieved widespread use in living polymerization. However, until now there hasbeen little report that macroinitiators initiate polymerization in different catalytic systems. The preparation of bromine-terminatedpolymethyl methacrylate (PMMA-Br) and chlorine-terminated PMMA (PMMA-Cl) were carried out via reverse atom transferradical polymerization (RATRP). The PMMA with halogen termination and narrow polydispersity (Mn = 12,000–15,000 g/mol,Mw/Mn = 1.1–1.2) were used as macroinitiators. The block copolymer of polymethyl methacrylate and polyacrylonitrile (PMMAb-PAN) was prepared in different catalytic systems through normal ATRP. The analyses of the 1H NMR showed that the PMMAprepared by RATRP were end-functionalized by halogen atoms, demonstrated the activities of the PMMA macroinitiators. Themolecular weight and polydispersity index (PDI) of the polymers were analyzed using gel permeation chromatography (GPC). The results indicated that the block polymers that the molecular weight of the block copolymer after chain extension has increasedsignificantly and the molecular weight distribution is narrow (Mn = 17,000–25,000 g/mol, Mw/Mn = 1.1–1.3). The kinetics ofthese polymerization processes were studied as a function of monomers to the macroinitiator molar ratio. It was found that thepolymerizations in different catalytic systems coincidence first-order kinetics with respect to monomers.