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Li Hu,Mengdi Li,Weijiu Huang,Xusheng Yang,Fei Guo,Haipeng Dong 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.5
Microstructure characteristics and mechanical behavior of AA2099 Al–Li alloy with no pre-existing Li-containing precipitates(AA2099-1 sample), pre-existing δ′ precipitates (AA2099-2 sample), pre-existing T1phase (AA2099-3 sample) andpre-existing T2phase (AA2099-4 sample) are systematically investigated via isothermal uniaxial compression at 250 °C inthe present study. Experimental results demonstrate that at the onset of plastic deformation, dynamic precipitation of smallsizedT1phase occurs rapidly within AA2099-1 sample, while it will be hindered within AA2099-2 sample. The increasingplastic strain benefits to dynamic precipitation of small-sized T1phase in AA2099-2 sample. Consequently, AA2099-1 andAA2099-2 samples possess similar and intermediate mechanical behaviors. In terms of AA2099-3 sample, the existence oflarge-sized T1phase results in the maximum yielding stress. However, some regions within these large-sized T1precipitatesare suspected to be sheared by cross-slip, leading to the destruction of crystallographic structure and the formation of Almatrix intervals. This aspect is responsible for the gradual degradation in true stress-strain curve after peak stress. As forAA2099-4 sample, dynamic precipitation rarely happens during plastic deformation and the interaction between dislocationand the pre-existing T2phase belongs to Orowan looping, resulting in the minimal mechanical response. Besides,AA2099-1 sample possesses the average minimum deviation angle (MDA) of ~ 16.5° between the loading direction and the<110> crystal direction, whereas AA2099-4 sample owns the average MDA of ~ 7.5°. The difference in MDA is mainlyattributed to δ′ phase and T1phase, which will separately accelerate and postpone the rotation of orientation towards the<110> crystal direction.
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Cao, Shiyu,Song, Shangbin,Xiang, Xing,Hu, Qing,Zhang, Chi,Xia, Ziwen,Xu, Yinghui,Zha, Wenping,Li, Junyang,Gonzale, Paulina Mercedes,Han, Young-Hwan,Chen, Fei The Korean Ceramic Society 2019 한국세라믹학회지 Vol.56 No.2
Recently, all-solid-state batteries (ASSBs) have attracted increasing interest owing to their higher energy density and safety. As the core material of ASSBs, the characteristics of the solid electrolyte largely determine the performance of the battery. Thus far, a variety of inorganic solid electrolytes have been studied, including the NASICON-type, LISICON-type, perovskite-type, garnet-type, glassy solid electrolyte, and so on. The garnet Li<sub>7</sub>La<sub>3</sub>Zr<sub>2</sub>O<sub>12</sub> (LLZO) solid electrolyte is one of the most promising candidates because of its excellent comprehensively electrochemical performance. Both, experiments and theoretical calculations, show that cubic LLZO has high room-temperature ionic conductivity and good chemical stability while contacting with the lithium anode and most of the cathode materials. In this paper, the crystal structure, Li-ion transport mechanism, preparation method, and element doping of LLZO are introduced in detail based on the research progress in recent years. Then, the development prospects and challenges of LLZO as applied to ASSBs are discussed.
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Ye Zhang,Li Wang,Wei Sun,Yue-hua Hu,Honghu Tang 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.81 No.-
Recent years have seen rapid improvement of technology and large-scale applications of lithium-ionbatteries, which leads to an increasing market demand for lithium. Since the land lithium resources arediminishing drastically, the sources of lithium extraction have shifted to the large amount of waterresources containing salt-lake brines and seawater. Among the varieties of aqueous recovery approaches,membrane technology seems to have huge development potential and good application prospect. This isbecause the membrane technologies exhibit excellent Li/Mg separation selectivity, with low energyconsumption and green process owing to no addition of chemicals. The present work reviews the latestadvances in various membrane technologies, including nanofiltration membrane, electrodialysis,membrane capacitive deionization approaches, solid electrolyte electrolysis-based technology, etc. Therecent developments in positively charged nanofiltration membrane are discussed in terms of thepreparation methods, membrane properties, and Li/Mg separation coefficient. In addition, the effects ofseveral factors on electrodialysis for lithium extraction and relevant mechanisms in both simple andactual saline systems are discussed, including applied voltage, VC/VD, and coexisting ions. Theapplications of electrodialysis with novel selective membrane involving nanofiltration membrane as wellas solid electrolyte membrane and perspectives for further investigation are proposed.
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Xia Wentao,Cheng Miao,Hu Jing,Liu Qianqian,Wei Tao,Wang Ruirui,Li Wanfei,Liu Bo 한국탄소학회 2024 Carbon Letters Vol.34 No.1
N-doping content and configurations have a significant effect on the electrochemical performance of carbon anodes. Herein, we proposed a simple method to synthesize highly N self-doped chitosan-derived carbon with controllable N-doping types by introducing 2ZnCO3·3Zn(OH)2 into the precursor. The as-synthesized NC-CS/2ZnCO3·3Zn(OH)2 electrode exhibited more than twice the reversible capacity (518 mAh g−1 after 100 cycles at 200 mA g−1) compared to the NC-CS electrode, superior rate performance and outstanding cycling stability. The remarkable improvement should be mainly attributed to the increase of N-doping content (particularly the pyrrolic-N content), which provided more active sites and favored Li+ diffusion kinetics. This study develops a cost-effective and facile synthesis route to fabricate high-performance N self-doped carbon with tunable doping sites for rechargeable battery applications.
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Hui Xiao,Jing Hu,Shuailin Jin,Rui Hai Li 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.9
A novel zwitterionic monomer 3-[(2-acrylamido)dimethylammonio]propanesulfonate (DMADAS) was designed and synthesized in this study. Then it was polymerized with acrylamide (AM) by free radical polymerization in 0.5 mol/L NaCl solution with ammonium persulfate ((NH4)2S2O8) and sodium sulfate (NaHSO3) as initiator. The structure and composition of DMADAS and acrylamide-3-[(2-acrylamido)- dimethylammonio]propanesulfonate copolymer (P-AM-DMADAS) were characterized by FT-IR spectroscopy, 1H NMR and elemental analyses. Isoelectric point (IEP) of P-AM-DMADAS was tested by nanoparticle size and potential analyzer. Solution properties of copolymer were studied by reduced viscosity. Antipolyelectrolyte behavior was observed and was found to be enhanced with increasing DMADAS content in copolymer. The results showed that the viscosity of P-AM-DMADAS is 5.472 dl/g in pure water. Electrolyte was added, which weakened the mutual attraction between sulfonic acid group and quaternary ammonium group. The conformation became loose, which led to the increase of reduced viscosity. The ability of monovalent and divalent cation influencing the viscosity of zwitterionic copolymer obeyed the following sequence: Li+ < Na+ < K+, Mg2+ < Ca2+ < Ba2+, and that of anion is in the order: Cl− < Br− < I−, CO3 2− > SO3 2− ≈ SO4 2−.
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Siqi Xu,Xiaoyan Wu,Zhihua Tao,Hongsheng Li1,Chenliang Fan,Songjin Chen,Jianwei Guo,Yao Ning,Xuqi Hu 한국유전학회 2020 Genes & Genomics Vol.42 No.3
Background Androgen-independent prostate cancer (AIPC) is an extremely malignant tumor developed from the androgen dependent (ADPC). However, the mechanism of transition process from ADPC to AIPC remains unknown. Objective Here we aimed to identify the androgen receptor (AR) target gene and its roles in AIPC. Methods Target genes of AR were identified by ChIP-seq in AIPC cells. AR target gene PCDH7 was detected by real time PCR and western blot. Methylation of PCDH7 was measured by bisulfite sequencing and bisulfite amplicon sequencing. Cell growth, invasion and apoptosis were measured by CCK-8, transwell and flow cytometry, respectively. Results AR was significantly enriched in the upstream of PCDH7 gene. The expression of PCDH7 was significantly decreased, while the methylation of PCDH7 was increased in the AIPC cells compared to the ADPC cells. DNA methyltransferase inhibitor significantly suppressed the methylation and increased the mRNA and protein level of PCDH7. Moreover, overexpression of DNMT1 remarkably reduced the mRNA and protein level of PCDH7. DNA methyltransferase inhibitor decreased the cell growth and invasion while promote the cell apoptosis in the AIPC cells. AR significantly target PCDH7, whose hypermethylation may repress cell growth and invasion, and promote apoptosis in AIPC. Conclusions This study might provide a novel potential target for the treatment of AIPC.
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Li, Hong-Sheng,Chen, Jin-Hu,Zhang, Wei,Shang, Dong-Ping,Li, Bao-Sheng,Sun, Tao,Lin, Xiu-Tong,Yin, Yong Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.3
Objective: To evaluate the effect of intravenous contrast on dose calculation in radiation treatment planning for oesophageal cancer. Methods: A total of 22 intravein-contrasted patients with oesophageal cancer were included. The Hounsfield unit (HU) value of the enhanced blood stream in thoracic great vessels and heart was overridden with 45 HU to simulate the non-contrast CT image, and 145 HU, 245 HU, 345 HU, and 445 HU to model the different contrast-enhanced scenarios. 1000 HU and -1000 HU were used to evaluate two non-physiologic extreme scenarios. Variation in dose distribution of the different scenarios was calculated to quantify the effect of contrast enhancement. Results: In the contrast-enhanced scenarios, the mean variation in dose for planning target volume (PTV) was less than 1.0%, and those for the total lung and spinal cord were less than 0.5%. When the HU value of the blood stream exceeded 245 the average variation exceeded 1.0% for the heart V40. In the non-physiologic extreme scenarios, the dose variation of PTV was less than 1.0%, while the dose calculations of the organs at risk were greater than 2.0%. Conclusions: The use of contrast agent does not significantly influence dose calculation of PTV, lung and spinal cord. However, it does have influence on dose accuracy for heart.
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Scalable graphene composite membranes for enhanced ion selectivity
Li, Siying,Lee, Jung-Hun,Hu, Qicheng,Oh, Tae-Sik,Yoo, Ji-Beom Elsevier 2018 Journal of membrane science Vol.564 No.-
<P><B>Abstract</B></P> <P>Unintended defects are a significant problem for mass production of graphene membranes. Herein, we report a method to fabricate scalable CVD graphene polymer membranes through the formation of a polysulfone (PSf) supporting layer, which is capable of duplicating the Cu morphology. Unintended defects were limited by minimizing defects associated with graphene wrinkles and eliminating polymer residues used in the transfer process. Consequently, the KCl leakage by diffusion of raw graphene membranes fabricated with this method was only ~ 0.5% that of the supporting membrane; there was also no water flux under a pressure of 20 bar. Excellent ion selectivity was achieved by controlling the duration of H<SUB>2</SUB> plasma treatment. The selectivity of KCl over NaCl was 2.61, the selectivity of KCl over MgCl<SUB>2</SUB> was 15.62, and the selectivity of NaCl over MgCl<SUB>2</SUB> was 5.98.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Polysulfone formed in Ethanol coagulation bath performed better permeability comparing to that formed in water coagulation bath. </LI> <LI> Cu foil morphology was duplicated by liquid phase PSf solution to minimize additional graphene wrinkles and unintended defects. </LI> <LI> ~ 0.5% KCl leakage by diffusion of raw graphene membranes that of the supporting membrane. </LI> <LI> Artificial graphene defects were enlarged and controlled with hydrogen plasma. </LI> <LI> The membrane exhibited an excellent selectivity among KCl, NaCl, MgCl<SUB>2</SUB> salts. </LI> </UL> </P>
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Ahmad, Ishfaq,Li, Feng,Kim, Changmin,Seo, Jeong-Min,Kim, Guntae,Mahmood, Javeed,Jeong, Hu Young,Baek, Jong-Beom Elsevier 2019 Nano energy Vol.56 No.-
<P><B>Abstract</B></P> <P>Fused aromatic (FA) porous organic networks (PON) have unique properties including structural diversity, low density, thermal and chemical stability, and are gaining extensive attention in the scientific community. Here, we report a new FA-PON formed by polycondensation between triphenylene hexamine (TPH) and hexaketocyclohexanone (HKH) octahydrate. The structure and properties of the FA-PON were characterized by various techniques, which showed the chemical formula of the repeating unit to be C<SUB>24</SUB>N<SUB>6</SUB> (C<SUB>4</SUB>N<SUB>1</SUB>), with good thermal and chemical stability. The hole-to-hole distance of the FA-PON was 0.994 nm and each hole contained 6 nitrogen atoms, allowing the efficient fixation and encapsulation of iron (Fe) nanoparticles, and formation of a durable indirect-contact catalyst for the oxygen reduction reaction (ORR). The Fe nanoparticles on the FA-PON (Fe@FA-PON) catalyst displayed high electrocatalytic activity with durability in both acidic and alkaline media. Moreover, the catalyst exhibited unusual ORR activity with a half wave potential of 0.884 V, which is a 38 mV positive shift compared to commercial platinum on activated carbon (Pt/C) catalyst in alkaline medium.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fixation of Fe precursors in porous 2D FA-PON structure leads to a durable Fe-based indirect-contact Fe/Fe<SUB>3</SUB>C@C<SUB>4</SUB>N catalyst. </LI> <LI> The Fe/Fe<SUB>3</SUB>C@C<SUB>4</SUB>N catalyst displays a pH-universal electrocatalytic activity for ORR. </LI> <LI> The biggest advantage of Fe/Fe<SUB>3</SUB>C@C<SUB>4</SUB>N catalyst over commercial Pt/C is superior durability. </LI> <LI> The unusual durability of Fe/Fe<SUB>3</SUB>C@C<SUB>4</SUB>N catalyst is due to encapsulating Fe cores inside defect-free graphitic shells. </LI> <LI> Encapsulating graphitic shells allow stably protecting unstable Fe cores and efficiently tunneling electrons. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>An efficient fixation of Fe precursors in porous two-dimensional structure leads to a durable Fe-based indirect-contact Fe/Fe<SUB>3</SUB>C@C<SUB>4</SUB>N catalyst. The catalyst displays a electrocatalytic activity for ORR both in acid and alkaline media. Encapsulating graphitic shells allow stably protecting unstable Fe/Fe<SUB>3</SUB>C cores and efficiently tunneling electrons through the layers.</P> <P>[DISPLAY OMISSION]</P>
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Fe@C<sub>2</sub>N: A highly-efficient indirect-contact oxygen reduction catalyst
Mahmood, Javeed,Li, Feng,Kim, Changmin,Choi, Hyun-Jung,Gwon, Ohhun,Jung, Sun-Min,Seo, Jeong-Min,Cho, Sung-June,Ju, Young-Wan,Jeong, Hu Young,Kim, Guntae,Baek, Jong-Beom Elsevier 2018 Nano energy Vol.44 No.-
<P><B>Abstract</B></P> <P>Converting unstable earth-abundant group VIIIB transition metals into stable catalysts with high oxygen reduction reaction (ORR) performances remains a critical challenge for electrochemical technologies. Iron (Fe)-nitrogen (N)-carbon (C)-based electrocatalysts have recently demonstrated ORR performances comparable to platinum (Pt)-based catalysts. However, as their poor stability remains a critical issue, which needs to be resolved to satisfy commercial requirements. Here, we describe a methodology for preparing a high-performance and stable Fe-based ORR catalyst. The catalyst was obtained by the <I>in-situ</I> sandwiching of a Fe<SUP>3+</SUP> precursor in a nitrogenated holey two-dimensional network (denoted as C<SUB>2</SUB>N). Reduction of the sandwiched Fe<SUP>3+</SUP> results in the formation of Fe oxide (Fe<SUB>x</SUB>O<SUB>y</SUB>) nanoparticles, which are simultaneously transformed into highly crystalline Fe<SUP>0</SUP> nanoparticle cores, while the C<SUB>2</SUB>N is catalysed into well-defined, encapsulating, nitrogenated graphitic shells (Fe@C<SUB>2</SUB>N nanoparticles) during heat-treatment. The resultant Fe<SUP>0</SUP>@C<SUB>2</SUB>N nanoparticles are uniformly distributed on the C<SUB>2</SUB>N substrate, becoming the Fe@C<SUB>2</SUB>N catalyst, which displayed ORR activities superior to commercial Pt/C in both acidic and alkaline media. Furthermore, the Fe@C<SUB>2</SUB>N catalyst remained rust-free during harsh electrochemical testing even after 650h, suggesting that its unusual durability originates from indirect-contact electrocatalysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Iron (Fe) nanoparticle cores encapsulated in electrochemically transparent and stable shells (Fe@C<SUB>2</SUB>N) are prepared. </LI> <LI> The Fe@C<SUB>2</SUB>N catalyst displays superb oxygen reduction (ORR) performance in both alkaline and acidic media. </LI> <LI> The advantages of Fe@C<SUB>2</SUB>N catalyst over commercial Pt/C are low-cost and comparable ORR activity and superior durability. </LI> <LI> The unusual ORR performance is the result of the electrochemically stable and transparent encapsulating shells. </LI> <LI> Encapsulating shells allow not only an efficient electron tunneling but also protecting unstable active Fe cores. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Oxygen reduction catalyst from iron encapsulated in C<SUB>2</SUB>N framework (Fe@C<SUB>2</SUB>N) exhibits outstanding catalytic activities in both alkaline and acidic media. The Fe@C<SUB>2</SUB>N catalyst holds great potential for commercialization.</P> <P>[DISPLAY OMISSION]</P>
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