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Electrochemical Umpolung Enabled Radical-Radical Cross-Coupling Between Electron-Deficient Methylarenes and Aldehydes

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CCS Chemistry 2023年第9期5卷 1973-1981页

作者： Fei Lian kun Xu Chengchu zeng Faculty of Environment and Life Beijing University of TechnologyBeijing 100124

The electrochemical utilization of electron-deficient methylarenes for radical-radical cross-couplings remains very *** by an umpolung strategy,the unprecedented electrochemical cross-coupling of electron-deficient methylarenes with aldehydes was *** paired electrolysis simultaneously generated electron-deficient benzylic radicals and ketyl radicals at both electrodes,which then underwent radical recombination,governed by polarity matching and persistent-radical effect(PRE)to afford functionalized alcohols that are not easily accessible by other *** protocol features catalystand external redox agent-free conditions and a formal 100%atom *** studies support the radical-radical cross-coupling pathway.

关键词： paired electrolysis ketyl radical umpolung radical-radical cross-coupling methylarene aldehyde

Two families of Niho sequences having four-valued cross correlation with m-sequences Dedicated to Professor Yingbo Zhang on the Occasion of His 70th Birthday

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Science China Mathematics 2017年第12期60卷 2377-2390页

作者： fan JinMei XU YunGe XIA YongBo zeng XiangYong Faculty of Mathematics and Statistics Hubei Key Laboratory of Applied MathematicsHubei University College of Science Guilin University of Technology Department of Mathematics and Statistics South-Central University for Nationalities

For two odd integers m and s with 1≤s < m and gcd(m, s) = 1, let h satisfy h(2~s-1) ≡1(mod 2~m+ 1) and d =(h + 1)(2~m-1) + 1. The cross correlation function between a binary m-sequence of period 22~m-1 and its d-decimation sequence is proved to take four values, and the correlation distribution is completely determined. Let n be an even integer and k be an integer with 1≤k≤n/2. For an odd prime p and a p-ary m-sequence {s(t)} of period p^n-1, define u(t) =∑(p^k-1)/2 i=0 s(d_it), where d_i = ip^(n/2) + p^k-i and i = 0, 1,...,(p^k-1)/2. It is proved that the cross correlation function between {u(t)} and {s(t)} is three-valued or four-valued depending on whether k is equal to n/2 or not, and the distribution is also determined.

关键词： m-sequence decimation sequence correlation distribution Niho exponent exponential sum

Effects of the shape and size of rectangular inclusions on the fatigue cracking behavior of ultra-high strength steels

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International Journal of Minerals,Metallurgy and Materials 2013年第4期20卷 360-364页

作者： Yan-ping zeng Hong-mei fan Xi-shan Xie School of Materials Science and Engineering University of Science and Technology Beijing

The fatigue cracking behavior of ultra-high strength steels containing rectangular inclusions of small sizes were investigated based on in situ observations by scanning electron microscopy （SEM）. The size and shape of rectangular inclusions affect markedly the initiation site and propagation path of a fatigue crack. Especially, the initiation site of a fatigue crack depends strongly on the angle between the long-axis of a rectangle inclusion and the loading direction, and the length/width ratio of this rectangle inclusion because the residual stress distribution fields vary with these conditions. The results coincide very well with those of finite element analysis.

关键词： high strength steel inclusions fatigue of materials crack initiation crack propagation

Construction of dual heterogeneous interface between zigzag-like Mo–MXene nanofibers and small CoNi@NC nanoparticles for electromagnetic wave absorption

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Journal of Advanced Ceramics 2023年第8期12卷 1562-1576页

作者： Xiaojun zeng Xiao Jiang Ya Ning Feiyue Hu Bingbing fan School of Materials Science and Engineering Jingdezhen Ceramic UniversityJingdezhen 333403China School of Materials Science&Engineering Zhengzhou UniversityZhengzhou 450001China Jiangsu Key Laboratory of Advanced Metallic Materials School of Materials Science and EngineeringSoutheast UniversityNanjing 211189China

Two-dimensional(2D)transition metal carbides(MXene)possess attractive conductivity and abundant surface functional groups,providing immense potential in the field of electromagnetic wave(EMW)***,high conductivity and spontaneous aggregation of MXene suffer from limited EMW *** by dielectric–magnetic synergy effect,the strategy of decorating MXene with magnetic elements is expected to solve this *** this work,zigzag-like Mo_(2)TiC_(2)–MXene nanofibers(Mo-based MXene(Mo–MXene)NFs)with cross-linked networks are fabricated by hydrofluoric acid(HF)etching and potassium hydroxide(KOH)shearing ***,Co-metal–organic framework(MOF)and derived CoNi layered double hydroxide(LDH)ultrathin nanosheets are grown inside Mo–MXene NFs,and the N-doped carbon matrix anchored by CoNi alloy nanoparticles formed by pyrolysis is firmly embedded in the Mo–MXene NFs *** from synergistic effect of highly dispersed small CoNi alloy nanoparticles,a three-dimensional(3D)conductive network assembled by zigzag-like Mo–MXene NFs,numerous N-doped hollow carbon vesicles,and abundant dual heterogeneous interface,the designed Mo–MXene/CoNi–NC heterostructure provides robust EMW absorption ability with a reflection loss(RL)value of−68.45 dB at the thickness(d)of 4.38 *** robust EMW absorption performance can be attributed to excellent dielectric loss,magnetic loss,impedance matching(Z),and multiple scattering and reflection triggered by the unique 3D network *** work puts up great potential in developing advanced MXene-based EMW absorption devices.

关键词： zigzag-like Mo-MXene nanofiber(NF)network dual heterogeneous interface CoNi alloy electromagnetic wave(EMW)absorption

Community structures and population dynamics of “Candidatus Accumulibacter” in activated sludges of wastewater treatment plants using ppk1 as phylogenetic marker

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Journal of Environmental Sciences 2018年第5期30卷 237-248页

作者： Wei zeng Limin Zhang Pengchao fan Jingjing Guo Yongzhen Peng National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology Department of Environmental EngineeringBeijing University of Technology

Candidatus Accumulibacter has been identified as dominant polyphosphate-accumulating organisms（PAOs） in enhanced biological phosphorus（P） removal（EBPR） from *** study revealed the relevance of community structure, abundance and seasonal population dynamics of Candidatus Accumulibacter to process operation of wastewater treatment plants（WWTPs） in China using ppk1 gene as phylogenetic marker. All sludge samples had properties of denitrifying P removal using nitrate as an electron *** abundance in the anaerobic-anoxic-oxic（A^2O） process was the highest（26%of total bacteria）, and higher in winter than in summer with a better EBPR ***-II was the dominant Accumulibacter in all processes, and type-I accounted for a small proportion of total Accumulibacter. The abundance of Clade-IIC as the most dominant clade reached 2.59 × 10~9 cells/g MLSS and accounted for 87.3% of total Accumulibacter. Clade IIC mainly contributed to denitrifying P removal. Clades IIA, IIC and IID were found in all processes, while clade-IIF was only found in oxidation ditch process through phylogenetic analysis. High proportion of clade IID to total Accumulibacter led to poor performance of aerobic P-uptake in inverted A^2O process. Therefore, Accumulibacter clades in WWTPs were diverse, and EBPR performance was closely related to the clade-level community structures and abundances of Accumulibacter.

关键词： Candidatus Accumulibacter Polyphosphate kinase 1 gene (ppk1) Activated sludge Enhanced biological phosphorusremoval (EBPR) Wastewater treatmentplants (W Ps)

Catalase-imprinted Fe3O4/Fe@fibrous SiO2/polydopamine nanoparticles： An integrated nanoplatform of magnetic targeting, magnetic resonance imaging, and dual-mode cancer therapy

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Nano Research 2017年第7期10卷 2351-2363页

作者： Jinxing Chen Shan Lei kun zeng Mozhen Wang Anila Asif Xuewu Ge CAS Key Laboratory of Soft Matter Chemistry Department of Polymer Science and Engineering University of Science and Technology of China Hefei 230016 China Interdisciplinary Research Centre in Biomedical Materials (IRCSM) COMSATS Institute of Information Technology Lahore 54000 Pakistan

Recent advances in the research on the molecular mechanism of cell death and methods for preparation of nanomaterials make the integration of various therapeutic approaches, targeting, and imaging modes into a single nanoscale complex a new trend for the development of future nanotherapeutics. Hence, a novel ellipsoidal composite nanoplatform composed of a magnetic Fe3O4/Fe nanorod core （-120 nm） enwrapped by a catalase （CAT）-imprinted fibrous SiO2/ polydopamine （F-SiO2/PDA） shell with thickness 70 nm was prepared in this work. In vitro experiments showed that the Fe3O4/Fe@F-SiO2/PDA nanoparticles can selectively inhibit the bioactivity of CAT in tumor cells by the molecular imprinting technique. As a result, the H2O2 level in tumor cells was elevated dramatically. At the same time, the Fe304FFe core released Fe ions to catalyze the conversion of H2O2 to ＊OH in tumor cells. Eventually, the concentration of ＊OH in tumor cells rapidly rose to a lethal level thus triggering apoptosis. Combined with the remarkable near-infrared light （NIR） photothermal effect of the CAT- imprinted PDA layer, the Fe3O4/Fe@F-SiO2/PDA nanoparticles can effectively kill MCF-7, HeLa, and 293T tumor cells but are not toxic to nontumor cells. Furthermore, these nanoparticles show good capacity for magnetic targeting and suitability for magnetic resonance imaging （MRI）. Therefore, the integrated multifunctional nanoplatform opens up new possibilities for high-efficiency visual targeted nonchemo therapy for cancer.

关键词： molecular imprintednanoparticles reactive oxygen species NIR photothermal therapy magnetic targeting magnetic resonanceimaging (MRI)

Mechanics of advanced fiber reinforced lattice composites

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Acta Mechanica Sinica 2010年第6期26卷 825-835页

作者： Hua-Lin fan Tao zeng Dai-Ning fang Wei Yang College of Mechanics and Materials Hohai University Nanjing 210098China Key Laboratory for Advanced Building Materials of Sichuan Province Southwest University of Science and Technology Mianyang 621010China College of Civil Engineering and Architecture Harbin University of Science and TechnologyHarbin 150080China College of Engineering Peking University Beijing 100871China University Office Zhejiang University Hangzhou 310058China

Fiber reinforced lattice composites are lightweight attractive due to their high specific strength and specific *** the past 10 years,researchers developed three-dimensional（3D） lattice trusses and two-dimensional （2D） lattice grids by various methods including interlacing, weaving,interlocking,filament winding and molding hot- *** lattice composites have been applied in the fields of radar cross-section reduction,explosive absorption and heat-resistance. In this paper,topologies of the lattice composites, their manufacturing routes,as well as their mechanical and multifunctional applications,were surveyed.

关键词： Lattice composites Mechanical behaviors Fabrication Multifunction

Simultaneous enhancements of strength and toughness by multiscale lamellar structure in Ti_(2)AlNb based intermetallic

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Journal of Materials Science & Technology 2024年第7期174卷 249-261页

作者： fan Zhang Weidong zeng Penghui Zhang Haoyuan Ma Jianwei Xu State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Defense Technologies Innovation Center of precision forging and ring rolling School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China

Multi-scale lamellar structure significantly improves toughness of Ti_(2)AlNb based alloys,which are inher-ently brittle intermetallics,without compromising their *** structure was achieved through-B2-transus-forging(TBTF)combined with O+B2 two-phase region heat *** types of multi-scale lamellar structures were obtained by controlling the cooling rate after *** variations were mainly attributed to differences in the distribution,content,and size of the thick lamellar O phase and the size and crystallographic orientation of B2 *** analyzing the microstructural characteristics and crystallographic orientation near the crack propagation path,it was found that the crack propaga-tion resistance of thick lamellae,sub grain and grain boundaries(GBs)O phase increased sequentially,accompanied by more tortuous crack propagation ***,B2 grains with high misorientation significantly deflected the crack propagation by cleavage ridges between adjoining cleavage ***-tionally,the development of numerous secondary cleavage ridges,resulting from the transition through varying secondary cleavage planes in distinct sub B2 grains,further hindered the quick propagation of *** was clarified that the cleavage planes were dominantly belonging to{110}.These findings pro-vided valuable guidance for the design of damage tolerance strategies for Ti_(2)AlNb-based intermetallics.

关键词： Multiscale lamellae structure Fracture toughness Crack propagation Ti_(2)AlNb-based intermetallic Through-B2-transus-forging

Low nutrient levels as drinking water conditions can reduce the fitness cost of efflux pump-mediated ciprofloxacin resistance in Pseudomonas aeruginosa

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Journal of Environmental Sciences 2019年第9期31卷 123-132页

作者： Wenfang Lin kun Wan Jie zeng Jingjing Li Xi Li Xin Yu Key Lab of Urban Environment and Health Institute of Urban Environment Chinese Academy of Sciences Xiamen 361021 China University of Chinese Academy of Sciences Beijing 100049 China

The long-term persistence of antibiotic resistance in the environment, especially in drinking water, is a public health concern. Expression of an efflux pump, an important mechanism of resistance to antibiotics, usually confers a fitness cost in bacteria. In this study, we aimed to determine why antibiotic resistance conferred by overexpression of an efflux pump persisted in low-nutrient environments(TOC < 10 mg/L) such as drinking and source water in which antibiotic selective pressure might be very low or even *** experiments between wild-type Pseudomonas aeruginosa and ciprofloxacinresistant mutants revealed that the fitness cost of ciprofloxacin resistance significantly decreased(p < 0.05) under low-nutrient(0.5 mg/L total organic carbon(TOC)) relative to high-nutrient(500 mg/L TOC) conditions. Mechanisms underlying this fitness cost were analyzed. The mexD gene expression in resistant bacteria(cip3 strain) was significantly lower(p < 0.05) in low-nutrient conditions, with 10 mg/L TOC((8.01 ± 0.82)-fold), than in high-nutrient conditions, with 500 mg/L TOC((48.89 ± 4.16)-fold). Moreover, rpoS gene expression in resistant bacteria((1.36 ± 0.13)-fold) was significantly lower(p < 0.05) than that in the wild-type strain((2.78 ± 0.29)-fold) under low-nutrient conditions(10 mg/L TOC),suggesting a growth advantage. Furthermore, the difference in metabolic activity between the two competing strains was significantly smaller(p < 0.05) in low-nutrient conditions(5 and 0.5 mg/L TOC). These results suggest that nutrient levels are a key factor in determining the persistence of antibiotic resistance conferred by efflux pumps in the natural environment with trace amounts or no antibiotics.

关键词： Efflux pumps Antibiotic resistance Fitness cost Low nutrient nfxB mutation Ciprofloxacin resistance