In-pile tritium release behavior and the post-irradiation experiments of Li4SiO4 fabricated by melting process

Zhao Linjie,Yang Mao,Xiao Chengjian,Gong Yu,Ran Guangming,Chen Xiaojun,Li Jiamao,Yue Lei,Chen Chao,Hou Jingwei,Wang Heyi,Long Xinggui,Peng Shuming 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.1

Understanding the tritium release and retention behavior of candidate tritium breeder materials is crucial for breeder blanket design. Recently, a melt spraying process was developed to prepare Li4SiO4 pebbles, which were subsequently subjected to the in-pile tritium production and extraction platform in China Mianyang Research Reactor (CMRR) to investigate their in-situ tritium release behavior and irradiation performance. The results demonstrate that HT is the main tritium release form, and adding hydrogen to the purge gas reduces tritium retention while increasing the HT percent in the purge gas. Post-irradiation experiments reveal that the irradiated pebbles darken in color and their grains swell, but the mechanical properties remain largely unchanged. It is concluded that the tritium residence time of Li4SiO4 made by melt spraying method at 467 ◦C is approximately 23.34 h. High-density Li4SiO4 pebbles exhibit tritium release at relatively low temperatures (<600 ◦C) that is mainly controlled by bulk diffusion. The diffusion coefficient at 525 ◦C and 550 ◦C is 1.19 × 10 11 cm2/s and 5.34 × 10 11 cm2/s, respectively, with corresponding tritium residence times of 21.3 hours and 4.7 hours.

Controllable Synthesis of Co-Doped Spinel LiMn2O4 Nanotubes as Cathodes for Li-Ion Batteries

Li-Xin Zhang,Yuan-Zhong Wang,Hong-Fang Jiu,Ya-Lei Wang,Yi-Xin Sun,Zhenzhong Li 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.2

Spinel Co-LiMn2O4 nanotubes have been synthesized via solid state reaction using α-MnO2 nanotubes as selftemplates. The as-prepared powders were investigated by XRD, TEM, and galvanostatic discharge/charge analysis. The optimal doping amount was confirmed by galvanostatic charge/discharge measurements. The results indicate that about 67% of initial capacity (115 mAh/g) of LiMn2O4 nanotubes can be retained after 50 cycles. For Co-LiMn2O4 nanotubes, the initial reversible capacity is 126.6 mAh/g and 100 mAh/g can be maintained after 50 cycles. The capacitance retention rate of Co-LiMn2O4 nanotubes is as high as 79%. These results indicate that the doping Co can effectively improve circle stability and electrochemical performance of LiMn2O4 nanotubes.

Fabrication and Interface Structural Behavior of Mg/Al Thickness-Oriented Bonding Sheet via Direct Extrusion

Lei Gao,Feng Li,Ye Wang,Xing Mao Xiao,Peng Da Huo 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

Solid-state bonding of heterogeneous materials is one of the effective ways to achieve light weight. An extrusion formingprocess for Mg/Al thickness-oriented bonding sheet was carried out. Due to triaxial compressive stress in the extrusion container,the AZ31 and AA6061 billets were deformed and the bonding and forming of Mg/Al thickness-oriented sheet can berealized by this method. The observation results of the bonding position by using XRD, SEM and EDS showed that: at theforming temperature with 360–420 °C, it had a good bonding interface, and the width of the transition layer increased withthe increase of the forming temperature. The presence of brittle intermetallic compounds in the transition layer indicated thatmetallurgical bonding had occurred at the interface. Considering all factors comprehensively, when the forming temperaturewas 390 °C, the bonding quality was appropriate. Its tensile-shear strength was 42 MPa, the width of the interface transitionlayer was about 10 μm, and the microhardness was about 164.3 HV. This method provided scientific guidance and technicalreserves for green forming of Mg/Al sheets.

Cloning and Characterization of a Na+/H+ Antiporter Gene of the Moderately Halophilic Bacterium Halobacillus aidingensis AD-6T

Ya Jie Zou,Li Fu Yang,Lei Wang,Su Sheng Yang 한국미생물학회 2008 The journal of microbiology Vol.46 No.4

A gene encoding a Na+/H+ antiporter was obtained from the genome of Halobacillus aidingensis AD-6T, which was sequenced and designated as nhaH. The deduced amino acid sequence of the gene was 91% identical to the NhaH of H. dabanensis, and shared 54% identity with the NhaG of Bacillus subtilis. The cloned gene enable the Escherichia coli KNabc cell, which lack all of the major Na+/H+ antiporters, to grow in medium containing 0.2 M NaCl or 10 mM LiCl. The nhaH gene was predicted to encode a 43.5 kDa protein (403 amino acid residues) with 11 putative transmembrane regions. Everted membrane vesicles prepared from E. coli KNabc cells carrying NhaH exhibited Na+/H+ as well as Li+/H+ antiporter activity, which was pH-dependent with the highest activity at pH 8.0, and no K+ /H+ antiporter activity was detected. The deletion of hydrophilic C-terminal amino acid residues showed that the short C-terminal tail was vital for Na+/H+ antiporter activity.

High-performance solid-state flexible supercapacitor based on reduced graphene oxide/hierarchical core-shell Ag nanowire@NiAl layered double hydroxide film electrode

Li, Lei,Hui, Kwan San,Hui, Kwun Nam,Zhang, Tengfei,Fu, Jianjian,Cho, Young-Rae Elsevier 2018 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.348 No.-

<P><B>Abstract</B></P> <P>All-solid-state flexible supercapacitor (AFSC) is a promising energy storage device due to its high flexibility, security, and environmental friendliness. However, high electrical resistance and low specific capacitance of electrodes limit its application for potential portable electronic devices. In this study, we design a novel hybrid film electrode composed of reduced graphene oxide (rGO)/silver nanowire (Ag NW)@nickel aluminum layered double hydroxide (NiAl LDH; herein, GAL) possessing high electrochemical performance by using hydrothermal and vacuum filtration techniques. The Ag NW@NiAl LDH (AL) composites with hierarchical core-shell structure are utilized to increase electroactive surface area and improve electrical conductivity, while the rGO nanosheets serve as a prominent carbon material with outstanding electrical conductivity and mechanical flexibility. The freestanding GAL electrode shows high specific capacitance of 1148 F g<SUP>−1</SUP> at 1 A g<SUP>−1</SUP> compared with rGO/NiAl LDH (GL) of 765.2 F g<SUP>−1</SUP> at 1 A g<SUP>−1</SUP>. Furthermore, the bind-free symmetric AFSC device is successfully prepared using GAL hybrid film as electrodes and PVA-KOH as solid-state gel electrolyte. The GAL//GAL AFSC device delivers a superior specific capacitance of 127.2 F g<SUP>−1</SUP> at 1 A g<SUP>−1</SUP>, a high energy density of 35.75 mWh cm<SUP>−3</SUP> at a power density of 1.01 W cm<SUP>−3</SUP>, and great cycling ability of 83.2% over 10,000 cycles at 5 A g<SUP>−1</SUP>. This study introduces a novel design of flexible electrode structure for advanced energy storage applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A well-designed rGO/Ag NW@NiAl-LDH (GAL) hybrid film was prepared. </LI> <LI> The Ag NWs improved the conductivity of the hybrid film. </LI> <LI> The GAL electrode shows high specific capacitance of 1148 F g<SUP>−1</SUP>. </LI> <LI> The flexible device displays high energy density of 35.75 mWh cm<SUP>−3</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Catalytic effects of calcium and potassium on a curved char surface in fuel reburning: A first-principles study on the adsorption of nitric oxide on single-wall carbon nanotubes with metal decoration

Liu, Lei,Jin, Jing,Hou, Fengxiao,Li, Shengjuan,Lee, Chang-Ha Pergamon Press 2017 Energy Vol.125 No.-

<P><B>Abstract</B></P> <P>To investigate the role of a curved char surface in the nitric oxide (NO)-char reaction, single-wall carbon nanotubes (SWCNTs) were proposed as a model for simulating the curved char surface in first-principles calculations. The effect of calcium and potassium decoration on the adsorption of NO was compared for SWCNTs and graphene, the latter of which represented a flat char surface. The contribution of a curved surface to the NO-char reaction was insignificant in the absence of metals, as the binding energy of NO on pure SWCNTs was only 13% of that on pure graphene. In contrast, when calcium or potassium was present, NO adsorption on the curved surface became significant as the binding energies of NO on calcium- or potassium-decorated SWCNTs increased to 72% and 18% of those on the corresponding decorated graphene surfaces, respectively. The catalytic effect of calcium and potassium was attributed to electron transfer and backdonation between the 4s- and 3d-orbitals of the metal atoms and the NO molecule. Thus, the studies into NO adsorption on flat and curved char surfaces render it possible to determine the degree of catalytic effect of these two metals on the char surface during fuel reburning.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SWCNTs were proposed to simulate the curved char surface in the fuel reburning. </LI> <LI> The catalytic effects of Ca and K were studied by Ca- or K-decorated SWCNTs. </LI> <LI> Without Ca or K, the binding energy of NO on curved char surface was trivial. </LI> <LI> When Ca or K was present, NO adsorption on the curved surface became significant. </LI> <LI> Electrons of Ca and K in 4s- and 3d-orbitals transferred to the NO molecule. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Robust, self-cleaning, amphiphobic coating with flower-like nanostructure on micro-patterned polymer substrate

Yao, Wenhui,Li, Lei,Li, Oi Lun,Cho, Young-Wook,Jeong, Myung-Yung,Cho, Young-Rae Elsevier 2018 Chemical Engineering Journal Vol.352 No.-

<P><B>Abstract</B></P> <P>Many superhydrophobic surfaces lose their repellency to water owing to the contamination of organic liquids or mechanical damage. Though amphiphobic coatings can repel both water and organic liquids, the poor mechanical and chemical stabilities significantly restrict their practical applications. Herein, we demonstrated a hydrothermal method to synthesize micro-patterned substrates bearing NiAl layered double hydroxide with flower-like nanostructures, which resemble the surface morphology of a lotus leaf. The surface was further modified by a low-surface-energy material of perfluorooctanoic acid through a solution immersion method. The binder-free coating formed in-situ on the substrate showed a good adhesion quality of 5B (ASTM D-3359). The coating possessed high repellency to different liquid droplets, including water, diiodomethane, ethylene glycol, soybean oil, etc., with surface tensions ranging from 72.7 to 22.4 mN m<SUP>−1</SUP>. Due to the excellent self-cleaning property, the contaminant on the surface was easily cleaned as the water droplet rolled off. Moreover, the coating exhibited good mechanical and chemical robustness in some extreme conditions, such as gas blowing, sea sand abrasion, and chemical immersion tests. These good performances made the coating possible to be applied widely in various practical applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Flower-like nanostructure of NiAl-LDH was synthesized on micro-patterned polymer. </LI> <LI> The hierarchical structure showed good amphiphobicity after fluorination. </LI> <LI> The amphiphobic surface possessed excellent self-cleaning performance. </LI> <LI> The amphiphobic surface exhibited good mechanical and chemical robustness. </LI> <LI> The coating can be used in anti-contaminant, self-cleaning, and biomedical device. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Stretchy binary classification

Toh, Kar-Ann,Lin, Zhiping,Sun, Lei,Li, Zhengguo Elsevier 2018 Neural networks Vol.97 No.-

<P><B>Abstract</B></P> <P>In this article, we introduce an analytic formulation for compressive binary classification. The formulation seeks to solve the least <SUP> ℓ p </SUP> -norm of the parameter vector subject to a classification error constraint. An analytic and stretchable estimation is conjectured where the estimation can be viewed as an extension of the pseudoinverse with left and right constructions. Our variance analysis indicates that the estimation based on the left pseudoinverse is unbiased and the estimation based on the right pseudoinverse is biased. Sparseness can be obtained for the biased estimation under certain mild conditions. The proposed estimation is investigated numerically using both synthetic and real-world data.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Proposed a novel cost function for counting the samples that are misclassified. </LI> <LI> Conjectured an analytic solution to a constrained p -norm minimization problem. </LI> <LI> Linkage of the proposed formulation to two existing classifiers. </LI> <LI> Provided variance analysis for the proposed analytic solution. </LI> <LI> Extensive experiments with comparison to state-of-the-arts. </LI> </UL> </P>

NiCo₂O₄ nanostructure-decorated PAN/lignin based carbon nanofiber electrodes with excellent cyclability for flexible hybrid supercapacitors

Lei, Danyun,Li, Xiang-Dan,Seo, Min-Kang,Khil, Myung-Seob,Kim, Hak-Yong,Kim, Byoung-Suhk Elsevier 2017 Polymer Vol.132 No.-

<P><B>Abstract</B></P> <P>Nanostructured binary metal oxide-decorated carbon nanofibers (CNFs) were utilized as flexible electrodes for hybrid supercapacitor applications. Polyacrylonitrile (PAN)/lignin based carbon nanofibers (PAN/lignin CNFs) with different contents of lignin were prepared by electrospinning, stabilization and carbonization. Afterwards, the NiCo<SUB>2</SUB>O<SUB>4</SUB> oxides were deposited on the surface of CNFs by a facile hydrothermal method without any toxic reagents. SEM images confirmed that the NiCo<SUB>2</SUB>O<SUB>4</SUB> (nanosheet and nanoneedle) nanostructures were uniformly grown on the surface of every carbon fiber. The obtained flexible NiCo<SUB>2</SUB>O<SUB>4</SUB>-decorated PAN/lignin CNFs with 50% lignin (NiCo<SUB>2</SUB>O<SUB>4</SUB>@CNF55) electrode exhibited high specific capacitance of the ∼1757 F g<SUP>−1</SUP> at 2 mA cm<SUP>−2</SUP> and excellent cyclability with ∼138% capacitance retention after 5000 cycles at 7 mA cm<SUP>−2</SUP>, suggesting lower internal resistance and higher electrochemical reversibility. In addition, the NiCo<SUB>2</SUB>O<SUB>4</SUB>@CNFs//N-rGO solid state asymmetric supercapacitor devices were assembled in order to evaluate their practical applications. The NiCo<SUB>2</SUB>O<SUB>4</SUB>@CNF55//N-rGO asymmetric supercapacitor device exhibited a specific capacitance of 134.3 F g<SUP>−1</SUP> at a current densities of 1 A g<SUP>−1</SUP>, and possessed a maximum energy density of 47.75 Wh kg<SUP>−1</SUP> with a power density of 799.53 W kg<SUP>−1</SUP>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PAN/lignin-based carbon fibers were prepared by electrospinning, stabilization and carbonization. </LI> <LI> The NiCo<SUB>2</SUB>O<SUB>4</SUB> nanostructures were fabricated on PAN/lignin-based carbon nanofibers. </LI> <LI> The NiCo<SUB>2</SUB>O<SUB>4</SUB>-decorated fiber electrode exhibits highest specific capacitance of the ∼1757 Fg<SUP>-1</SUP>. </LI> <LI> The NiCo<SUB>2</SUB>O<SUB>4</SUB>-decorated fiber electrode shows excellent capacitance retention of ∼138% after 5000 cycles. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Removal of chlorinated organic solvents from hydraulic fracturing wastewater by bare and entrapped nanoscale zero-valent iron

Lei, Cheng,Sun, Yuqing,Khan, Eakalak,Chen, Season S.,Tsang, Daniel C.W.,Graham, Nigel J.D.,Ok, Yong Sik,Yang, Xin,Lin, Daohui,Feng, Yujie,Li, Xiang-Dong Elsevier 2018 CHEMOSPHERE - Vol.196 No.-

<P><B>Abstract</B></P> <P>With the increasing application of hydraulic fracturing, it is urgent to develop an effective and economically feasible method to treat the large volumes of fracturing wastewater. In this study, bare and entrapped nanoscale zero-valent iron (nZVI) were introduced for the removal of carbon tetrachloride (CT) and 1,1,2-trichloroethane (TCA) in model high-salinity fracturing wastewater. With increasing ionic strength (<I>I</I>) from Day-1 (<I>I</I> = 0.35 M) to Day-90 (<I>I</I> = 4.10 M) wastewaters, bare nZVI presented significantly lower removal efficiency of CT (from 53.5% to 38.7%) and 1,1,2-TCA (from 71.1% to 21.7%) and underwent more serious Fe dissolution from 1.31 ± 1.19% in Day-1 to 5.79 ± 0.32% in Day-90 wastewater. Particle aggregation induced by high ionic strength was primarily responsible for the lowered performance of nZVI due to less available reactive sites on nZVI surface. The immobilization of nZVI in alginate with/without polyvinyl alcohol provided resistance to particle aggregation and contributed to the superior performance of entrapped nZVI in Day-90 wastewater for 1,1,2-TCA removal (62.6–72.3%), which also mitigated Fe dissolution (4.00–4.69%). Both adsorption (by polymer matrix) and reduction (by immobilized nZVI) were involved in the 1,1,2-TCA removal by entrapped nZVI. However, after 1-month immersion in synthetic fracturing wastewater, a marked drop in the reactivity of entrapped nZVI for 1,1,2-TCA removal from Day-90 wastewater was observed with significant release of Na and total organic carbon. In summary, bare nZVI was sensitive to the nature of the fracturing wastewater, while the use of environmentally benign entrapped nZVI was more promising for wastewater treatment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Increasing ionic strength decreased nZVI reactivity and increased Fe dissolution. </LI> <LI> Entrapping nZVI in polymer matrix improved reactivity and limited Fe dissolution. </LI> <LI> Entrapped nZVI removed model chlorinated organic via both adsorption and reduction. </LI> <LI> Aging process was mitigated by polymer matrix but still inhibited nZVI reactivity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>