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Controlling reversible complexation-mediated polymerization(RCMP)via deep eutectic solvents:fast kinetics,narrow molecular weight distribution and mechanistic insights

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Science China Chemistry 2024年第8期67卷 2728-2736页

作者： xin Fu zhen lu Shen Li zheng-Hong luo Lin-xi Hou Department of Materials-Oriented Chemical Engineering College of Chemical EngineeringFuzhou UniversityFuzhou 350116China Department of Chemical Engineering School of Chemistry and Chemical EngineeringState Key Laboratory of Metal Matrix CompositesShanghai Jiao Tong UniversityShanghai 200030China Chemical Engineering Zhicheng College of Fuzhou UniversityFuzhou 350116China Qingyuan Innovation Laboratory Quanzhou 362801China

The exploitation of new green polymerization avenues for the effective synthesis of polymers by reversible-deactivation radical polymerization plays a critical role in pursuing the development of polymeric *** this work,serials of deep eutectic solvents(DES)with intermolecular-hydrogen-bonding interaction were constructed as catalysts and medium for actuating reversible complexation-mediated polymerization(RCMP)for the first time,yielding methacrylate polymers with high monomer conversion and narrow dispersion molecular weight in both water and oil *** mechanism and elementary reaction of RCMP were explored deeply,revealing that the complexation of initiator with DES to generate radicals was a ratecontrolling step and intermolecular-hydrogen-bond was primary factor to influence polymerization ***,the insights of density functional theory calculations revealed that negative electrostatic potential ensured nucleophilic *** investigation demonstrated the considerable potential of DES for RCMP,which is anticipated for other polymerization applications as a novel medium mode.

关键词： deep eutectic solvent reversible complexation-mediated polymerization intermolecular hydrogen bonding density functional theory elementary reaction steps

Nuclear charge radius predictions by kernel ridge regression with odd-even effects

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Nuclear Science and Techniques 2024年第2期35卷 94-102页

作者： lu Tang zhen-Hua Zhang Mathematics and Physics Department North China Electric Power UniversityBeijing 102206China Hebei Key Laboratory of Physics and Energy Technology North China Electric Power UniversityBaoding 071000China

The extended kernel ridge regression(EKRR)method with odd-even effects was adopted to improve the description of the nuclear charge radius using five commonly used nuclear *** are:(i)the isospin-dependent A^(1∕3) formula,(ii)relativistic continuum Hartree-Bogoliubov(RCHB)theory,(iii)Hartree-Fock-Bogoliubov(HFB)model HFB25,(iv)the Weizsacker-Skyrme(WS)model WS*,and(v)HFB25**** the last two models,the charge radii were calculated using a five-parameter formula with the nuclear shell corrections and deformations obtained from the WS and HFB25 models,*** each model,the resultant root-mean-square deviation for the 1014 nuclei with proton number Z≥8 can be significantly reduced to 0.009-0.013 fm after considering the modification with the EKRR *** best among them was the RCHB model,with a root-mean-square deviation of 0.0092 *** extrapolation abilities of the KRR and EKRR methods for the neutron-rich region were examined,and it was found that after considering the odd-even effects,the extrapolation power was improved compared with that of the original KRR *** strong odd-even staggering of nuclear charge radii of Ca and Cu isotopes and the abrupt kinks across the neutron N=126 and 82 shell closures were also calculated and could be reproduced quite well by calculations using the EKRR method.

关键词： Nuclear charge radius Machine learning Kernel ridge regression method

Experimental distillation of tripartite quantum steering with an optimal local filtering operation

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Photonics Research 2024年第3期12卷 552-562页

作者： QIAN-xi ZHANG xiAO-XU FANG HE lu School of Physics State Key Laboratory of Crystal MaterialsShandong UniversityJinan 250100China Shenzhen Research Institute of Shandong University Shenzhen 518057China

Multipartite Einstein-Podolsky-Rosen(EPR)steering admits multipartite entanglement in the presence of uncharacterized verifiers,enabling practical applications in semi-device-independent *** applications generally require stronger steerability,while the unavoidable noise weakens steerability and consequently degrades the performance of quantum information ***,we propose the local filtering operation that can maximally distill genuine tripartite EPR steering from N copies of three-qubit generalized Greenberger-Horne-Zeilinger states,in the context of two semi-device-independent *** optimal filtering operation is determined by the maximization of assemblage *** and numerical results indicate the advantage of the proposed filtering operation when N is finite and the steerability of initial assemblages is ***,a proof-of-principle demonstration of two-copy distillation is realized with the optical *** advantage of the optimal local filtering operation is confirmed by the distilled assemblage in terms of higher assemblage fidelity with perfectly genuine tripartite steerable assemblages,as well as the greater violation of the inequality to witness genuine tripartite steerable *** results benefit the distillation of multipartite EPR steering in practice,where the number of copies of initial assemblages is generally finite.

关键词： filtering distillation optimal

Formation and Destiny of White Dwarf and Be Star Binaries

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Research in Astronomy and Astrophysics 2023年第2期23卷 262-274页

作者： Chun-Hua Zhu Guo-Liang Lü xi-zhen lu Jie He School of Physical Science and Technology Xinjiang UniversityUrumqi 830046China xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China

The binary systems consisting of a Be star and a white dwarf(Be WDs) are very *** can originate from the binaries composed of a Be star and a subdwarf O or B star(Besd OBs),and they can merge into red giants via luminous red nova or can evolve into double WD potentially detected by the LISA *** the method of population synthesis,we investigate the formation and the destiny of Be WDs,and discuss the effects of the metallicity(Z) and the common envelope evolution *** find that Besd OBs are significant progenitors of Be *** 30%(Z = 0.0001)-50%(Z = 0.02) of Be WDs come from Besd *** 60%(Z = 0.0001)-70%(Z = 0.02) of Be WDs turn into red giants via a merger between a WD and a non-degenerated *** 30%(Z = 0.0001)-40%(Z = 0.02) of Be WDs evolve into double WDs which are potential gravitational waves of the LISA mission at a frequency band between about 3 × 10^(-3)and 3 × 10^(-2)*** common envelope evolution parameter introduces an uncertainty with a factor of about 1.3 on Be WD populations in our simulations.

关键词： (stars:)binaries(including multiple) close-stars evolution-stars rotation-(stars:)white dwarfs

Sedimentary Environment and Mineralization of the Black Shale Polymetallic Layer in the Early Cambrian,SW China:Constraints from in situ LA-ICP-MS Analysis of Pyrite

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Acta Geologica Sinica(English Edition) 2024年第2期98卷 416-429页

作者： YANG zhen FU Yong LI Chao CAI xi GUO Chuan College of Eco-Environmental Engineering Guizhou Minzu UniversityGuiyang 550025China College of Resources and Environmental Engineering Guizhou UniversityGuiyang 550025China Key Laboratory of Karst Georesources and the Environment Ministry of EducationGuizhou UniversityGuiyang 500025China National Research Center for Geoanalysis Chinese Academy of Geological SciencesBeijing 100037China

A polymetallic layer is usually developed at the bottom of the early Cambrian black shale in Guizhou *** mineral that makes up the polymetallic layer is related to the sedimentary *** analyze the differentiation mechanism between polymetallic deposits(Ni-Mo and V),the Zhijin Gezhongwu profile located in the outer shelf and the Sansui Haishan V deposit located in the lower slope are selected to study the in situ sulfur isotopes and trace elements of *** results show that δ^(34)S values of pyrite vary widely from−7.8‰to 28‰in the Gezhongwu profile,while the δ^(34)S values are relatively uniform(from 27.8‰to 38.4‰)in the Haishan *** isotopic S composition is consistent with the transition that occurs in the sedimentary phase from the shelf to the deep sea on the transgressive Yangtze platform;this indicates that the δ^(34)SO_(4)^(2−)values in seawater must be differently distributed in depositional *** sulfur in the Ni-Mo layer is produced after the mixing of seawater and hydrothermal fluid,while the V layer mainly originates from ***,the Ni-Mo and V deposits have been differentiated primarily on the basis of the combined effect of continental weathering and hydrothermal fluid.

关键词： sedimentary environment black shale polymetallic layer pyrite early Cambrian

Cobalt-catalyzed reductive alkynylation to construct C(sp)-C(sp^(3))and C(sp)-C(sp^(2))bonds

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Chinese Chemical Letters 2024年第7期35卷 253-258页

作者： Lei Wan Yizhou Tong xi lu Yao Fu Hefei National Research Center for Physical Sciences at the Microscale iChEMCAS Key Laboratory of Urban Pollutant ConversionAnhui Province Key Laboratory of Biomass Clean EnergyUniversity of Science and Technology of ChinaHefei 230026China Key Laboratory of Precision and Intelligent Chemistry School of Chemistry and Materials ScienceUniversity of Science and Technology of ChinaHefei 230026China

Transition-metal-catalyzed cross-electrophile coupling has emerged as a reliable method for constructing carbon–carbon ***,we report a general method,cobalt-catalyzed reductive alkynylation,to construct C(sp)-C(sp^(3))and C(sp)-C(sp^(2))*** presented reaction has a broad substrate scope,enabling the efficient cross-electrophile coupling between alkynyl bromides with alkyl halides and aryl or alkenyl(pseudo)*** presented reaction is conducted under mild conditions,tolerating many functional groups,thus suitable for the modification and synthesis of biologically active molecules.

关键词： Cobalt-catalysis Cross-electrophile coupling Carbon-carbon bond formation Reductive alkynylation Alkyne synthesis

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CToMP: a cycle-task-oriented memory protection scheme for unmanned systems

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Science China(Information Sciences) 2024年第6期67卷 399-417页

作者： Chengyan MA Ning xi Di lu Yebo FENG Jianfeng MA School of Cyber Engineering Xidian University School of Computer Science and Technology Xidian University Department of Computer and Information Science University of Oregon

Memory corruption attacks(MCAs) refer to malicious behaviors of system intruders that modify the contents of a memory location to disrupt the normal operation of computing systems, causing leakage of sensitive data or perturbations to ongoing processes. Unlike general-purpose systems, unmanned systems cannot deploy complete security protection schemes, due to their limitations in size, cost and *** in unmanned systems are particularly difficult to defend against. Furthermore, MCAs have diverse and unpredictable attack interfaces in unmanned systems, severely impacting digital and physical sectors. In this paper, we first generalize, model and taxonomize MCAs found in unmanned systems currently, laying the foundation for designing a portable and general defense approach. According to different attack mechanisms,we found that MCAs are mainly categorized into two types — return2libc and return2shellcode. To tackle return2libc attacks, we model the erratic operation of unmanned systems with cycles and then propose a cycle-task-oriented memory protection(CToMP) approach to protect control flows from tampering. To defend against return2shellcode attacks, we introduce a secure process stack with a randomized memory address by leveraging the memory pool to prevent Shellcode from being executed. Moreover, we discuss the mechanism by which CTo MP resists the return-oriented programming(ROP) attack, a novel variant of return2libc attacks. Finally, we implement CTo MP on CUAV V5+ with Ardupilot and Crazyflie. The evaluation and security analysis results demonstrate that the proposed approach CTo MP is resilient to various MCAs in unmanned systems with low footprints and system overhead.

关键词： unmanned system memory corruption attack memory protection system security randomized memory address

Liquid metal biomaterials: translational medicines,challenges and perspectives

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National Science Review 2024年第2期11卷 264-284页

作者： Hanchi Xu Jincheng lu Yikuang xi Xuelin Wang Jing Liu Department of Biomedical Engineering School of Medicine Tsinghua University Beijing Tsinghua Changgung Hospital School of Clinical Medicine Tsinghua University Shanghai World Foreign Language Academy Beijing Advanced Innovation Center for Biomedical Engineering School of Engineering MedicineBeihang University Beijing Key Lab of Cryo-Biomedical Engineering and Key Lab of Cryogenics Technical Institute of Physics and Chemistry Chinese Academy of Sciences

Until now, significant healthcare challenges and growing urgent clinical requirements remain incompletely addressed by presently available biomedical materials. This is due to their inadequate mechanical compatibility, suboptimal physical and chemical properties, susceptibility to immune rejection, and concerns about long-term biological safety. As an alternative, liquid metal(LM) opens up a promising class of biomaterials with unique advantages like biocompatibility, flexibility, excellent electrical conductivity,and ease of functionalization. However, despite the unique advantages and successful explorations of LM in biomedical fields, widespread clinical translations and applications of LM-based medical products remain limited. This article summarizes the current status and future prospects of LM biomaterials, interprets their applications in healthcare, medical imaging, bone repair, nerve interface, and tumor therapy, *** to translate LM materials into medicine and obstacles encountered in practices are *** that, we outline a blueprint for LM clinics, emphasizing their potential in making new-generation artificial organs. Last, the core challenges of LM biomaterials in clinical translation, including bio-safety,material stability, and ethical concerns are also discussed. Overall, the current progress, translational medicine bottlenecks, and perspectives of LM biomaterials signify their immense potential to drive future medical breakthroughs and thus open up novel avenues for upcoming clinical practices.

关键词： liquid metal biomaterials translational medicine clinical device healthcare therapeutics

Capacitor Voltage Imbalance Mechanism and Balancing Control of MMC When Riding Through PTG Fault

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 778-785页

作者： zhen He Maozeng lu Lijun Hang Pingliang Zeng Yanhua Liu Hangzhou Dianzi University Hangzhou 310018China Shandong University of Technology Zibo 255000China State Grid Hangzhou Power Supply Company State GridHangzhou 310000China

Modular multilevel converter (MMC) based fault ride through (FRT) control is a promising solution to deal with the pole-to-ground (PTG) fault in high voltage direct current (HVDC) system. However, when MMC switches to the FRT control, capacitor voltage imbalance between upper and lower arms will occur, resulting in the deterioration of FRT performance. This letter provides a comprehensive analysis for the imbalance issue from the perspective of fundamental frequency circulating current (FFCC). It is found the imbalance during FRT stage will not expand continuously, but converge to a certain value gradually. The specific imbalance degree is closely associated with the amplitude of FFCC. In order to solve the imbalance issue, an open-loop balancing control is proposed. By introducing a fundamental frequency feedforward item to the inherent circulating current control, the proposed method can not only balance the capacitor voltages, but also minimize the amplitude of FFCC, and consequently the power loss of MMC during FRT process can be reduced. Finally, simulation results of PSCAD/ EMTDC verify the validity of theoretical analysis.

关键词： Balancing control capacitor voltage imbalance FFCC FRT control HVDC system PTG fault