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Microstructures and bio-corrosion resistances of as-extruded Mg-Ca alloys with ultra-fine grain size

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Rare Metals 2023年第2期42卷 680-687页

作者： Zi-ren xie Cheng Zhang Hu-Cheng Pan Yu-Xin Wang Yu-Ping ren Gao-Wu Qin Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) Northeastern UniversityShenyang110819China

Electrochemical and immersion tests were conducted to characterize the bio-corrosion resistance of asextruded Mg-Ca binary alloys with submicron grain *** microstructures were further characterized by optical microscopy(OM),scanning electronic microscopy and transmission electron microscope(TEM).The grain size was estimated from OM and TEM *** samples and at least 20 images were used to evaluate the average grain ***-textures of the as-extruded samples were measured via X-ray *** Mg-2Cu alloy extruded at 300℃(2Ca-300)exhibits the lowest current density of 1.683 mA·cm^(-2)and corrosion rate of 22.14 g·m^(-2)·day^(-1)in simulated body fluid,which is comparable with that of pure *** Ca addition can reduce grain size of as-extruded Mg alloy and decrease the corrosion *** formed Mg2Ca phases would accelerate the local galvanic corrosion and protect theα-Mg matrix simultaneously due to the lower electrode *** lower defect density,finer grain size and weaker basal texture intensity contribute to the excellent bi-corrosion resistance of the 2Ca-300 alloy.

关键词： Magnesium alloys Corrosion Defects Grain size

Jointly optimized congestion control, forwarding strategy,and link scheduling in a named-data multihop wireless network

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Frontiers of Information Technology & Electronic Engineering 2017年第10期18卷 1573-1590页

作者： Cheng-cheng LI ren-chao xie Tao HUANG Yun-jie LIU State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing Advanced Innovation Center for Future Internet Technology Beijing University of Technology

As a promising future network architecture, named data networking(NDN) has been widely considered as a very appropriate network protocol for the multihop wireless network(MWN). In named-data MWNs, congestion control is a critical issue. Independent optimization for congestion control may cause severe performance degradation if it can not cooperate well with protocols in other layers. Cross-layer congestion control is a potential method to enhance performance. There have been many cross-layer congestion control mechanisms for MWN with Internet Protocol(IP). However, these cross-layer mechanisms for MWNs with IP are not applicable to named-data MWNs because the communication characteristics of NDN are different from those of IP. In this paper, we study the joint congestion control, forwarding strategy, and link scheduling problem for named-data MWNs. The problem is modeled as a network utility maximization(NUM) problem. Based on the approximate subgradient algorithm, we propose an algorithm called ‘jointly optimized congestion control, forwarding strategy, and link scheduling(JOCFS)'to solve the NUM problem distributively and iteratively. To the best of our knowledge, our proposal is the first cross-layer congestion control mechanism for named-data MWNs. By comparison with the existing congestion control mechanism, JOCFS can achieve a better performance in terms of network throughput, fairness, and the pending interest table(PIT) size.

关键词： Information-centric networking Congestion control Cross-layer design Multihop wireless network

Defect and interface engineering in core@shell structure hollow carbon@MoS_(2)nanocomposites for boosted microwave absorption performance

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Nano Research 2022年第9期15卷 7778-7787页

作者： Junxiong Xiao Xiaosi Qi Xiu Gong Qiong Peng Yanli Chen ren xie Wei Zhong College of Physics Guizhou Province Key Laboratory for Photoelectrics Technology and ApplicationGuizhou UniversityGuiyang 550025China National Laboratory of Solid State Microstructures and Jiangsu Provincial Laboratory for NanoTechnology Nanjing UniversityNanjing 210093China

Defect and interface engineering are efficient approaches to adjust the physical and chemical properties of *** order to effectively utilize these strategies for the improvement of microwave absorption properties(MAPs),in this study,we reported the synthesis of hollow carbon shells and hollow carbon@MoS_(2)nanocomposites by the template-etching and templateetching-hydrothermal methods,*** obtained results indicated that the degree of defect for hollow carbon shells and hollow carbon@MoS_(2)could be modulated by the thickness of hollow carbon shell,which effectively fulfilled the optimization of electromagnetic parameters and improvement of ***,the microstructure investigations revealed that the precursor of hollow carbon shells was encapsulated by the sheet-like MoS_(2)in high *** the introduction of MoS_(2)nanosheets acting as the shell effectively improved the interfacial effects and boosted the polarization loss capabilities,which resulted in the improvement of comprehensive *** elaborately designed hollow carbon@MoS_(2)samples displayed very outstanding MAPs including strong absorption capabilities,broad absorption bandwidth,and thin matching ***,this work provided a viable strategy to improve the MAPs of microwave absorbers by taking full advantage of their defect and interface engineering.

关键词： core@shell structure hollow carbon shells hollow carbon@MoS_(2) defect and interface engineering improved microwave absorption properties

Tunable and improved microwave absorption of flower-like core@shell MFe_(2)O_(4)@MoS_(2)(M=Mn,Ni and Zn)nanocomposites by defect and interface engineering

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Journal of Materials Science & Technology 2023年第8期139卷 137-146页

Previous results revealed that the defect and/or interface had a great impact on the electromagnetic pa-rameters of *** order to understand the main physical mechanisms and effectively utilize these strategies,in this study,M Fe_(2)O_(4)and flower-like core@shell M Fe_(2)O_(4)@MoS_(2)(M=Mn,Ni,and Zn)sam-ples with different categories were elaborately designed and selectively produced in large scale through a simple two-step hydrothermal *** conducted the systematical investigation on their microstruc-tures,electromagnetic parameters and microwave absorption performances(MAPs).The obtained results revealed that the large radius of M^(2+)cation could effectively boost the concentration of oxygen vacancy in the M Fe_(2)O_(4)and M Fe_(2)O_(4)@MoS_(2)samples,which resulted in the improvement of dielectric loss capabil-ities and ***,the introduction of MoS_(2)nanosheets greatly improved the interfacial effect and enhanced the polarization loss capabilities,which also boosted the *** taking full advantage of the defect and interface,the designed M Fe_(2)O_(4)@MoS_(2)samples displayed tunable and excellent com-prehensive MAPs including strong absorption capability,wide absorption bandwidth and thin matching ***,the clear understanding of defect and interface engineering made these strategies well elaborately designed and applicable to improving MAPs.

关键词： Core@shell structure M Fe_(2)O_(4)@MoS_(2)(M=Mn,Ni and Zn) Defect and interface engineering Improved microwave absorption properties

Microstructure optimization of core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)flower-like multicomponent nanocomposites towards high-efficiency microwave absorption

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Journal of Materials Science & Technology 2022年第33期128卷 59-70页

作者： Jingjing Zhang Xiaosi Qi Xiu Gong Qiong Peng Yanli Chen ren xie Wei Zhong College of Physics Guizhou Province Key Laboratory for Photoelectrics Technology and ApplicationGuizhou UniversityGuiyang 550025China National Laboratory of Solid State Microstructures and Jiangsu Provincial Laboratory for NanoTechnology Nanjing UniversityNanjing 210093China

In this work,we put forward a scheme to exquisitely design and selectively synthesize the core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)flower-like multicomponent nanocomposites(MCNCs)through a simple two-step hydrothermal reaction on the surfaces of MFe_(2)O_4 nanospheres with the certain amounts of Mo and Se *** increasing the amounts of Mo and Se sources,the obtained core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)MCNCs with the enhanced content of MoSe_(2)and improved flower-like geometry morphology could be produced on a large *** obtained results revealed that the as-prepared samples displayed improved comprehensive microwave absorption properties(CMAPs)with the increased amounts of Mo and Se *** as-prepared CoSe_(2)/FeSe_(2)@MoSe_(2)and NiSe_(2)/FeSe_(2)@MoSe_(2)MCNCs with the well-defined flower-like morphology could simultaneously present the outstanding CMAPs in terms of strong absorption capability,wide absorption bandwidth,and thin matching thicknesses,which mainly originated from the conduction loss and flower-like geometry ***,the findings not only develop the very desirable candidates for high-performance microwave absorption materials but also pave a new way for optimizing the CMAPs through tailoring morphology engineering.

关键词： Core@shell structure MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co.Ni) multicomponent nanocomposites Flower-like geometry morphology Broad frequency bandwidth Microwave absorption

Magnetic-dielectric synergy and interfacial engineering to design yolk-shell structured CoNi@void@C and CoNi@void@C@MoS_(2) nanocomposites with tunable and strong wideband microwave absorption

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Nano Research 2022年第7期15卷 6761-6771页

作者： Chen Li Xiaosi Qi Xiu Gong Qiong Peng Yanli Chen ren xie Wei Zhong College of Physics Guizhou Province Key Laboratory for Photoelectrics Technology and ApplicationGuizhou UniversityGuiyang 550025China National Laboratory of Solid State Microstructures and Jiangsu Provincial Laboratory for NanoTechnology Nanjing UniversityNanjing 210093China

In order to effectively utilize the magnetic-dielectric synergy and interfacial engineering,in this paper,yolk–shell structured magnetic multicomponent nanocomposites(MCNCs)including CoNi@void@C and CoNi@void@C@MoS_(2) were produced in large scale by in-situ pyrolysis of cubic CoNi Prussian blue analogs(PBAs)followed by the hydrothermal process,*** of their unique structures,excellent synergistic effect between dielectric and magnetic loss,the as-prepared CoNi@void@C and CoNi@void@C@MoS_(2) MCNCs displayed very outstanding electromagnetic wave absorption performances(EMWAPs)including strong absorption capabilities,broad absorption bandwidth and thin matching ***,the as-prepared CoNi@void@C and CoNi@void@C@MoS_(2) MCNCs well maintained the cubic configuration of CoNi PBAs even after the thermal treatment and hydrothermal *** unique structure and formed carbon layers effectively prevented the corrosion of internal CoNi alloy during the formation of MoS_(2),and CoNi@void@C@MoS_(2) MCNCs with different MoS_(2) contents could be synthesized by controlling the hydrothermal *** obtained results revealed that the EM parameters,dielectric and magnetic loss capabilities of CoNi@void@C@MoS_(2) MCNCs could be tuned by controlling hydrothermal temperature and filler loading,which made their outstanding EMWAPs could be achieved in different frequency *** account of simple process,low density and high chemical stability,our findings provided a new and effective pathway to develop the strong wideband microwave absorbers.

关键词： yolk-shell structure CoNi@void@C CoNi@void@C@MoS_(2) interface polarization strong wideband microwave absorbers

Reduction of Aromatic Aldehydes and Ketones with Acyloxy Substituent at the Ortho-position by NaBH_4 in the Presence of Waters

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Chemical Research in Chinese Universities 1999年第2期15卷 90-95页

作者： WAN Xinhua ZHOU Hongbing xie ren ZHANG Dong FENG Xinde ZHOU QiFeng Department of Polymer Science&Engineering Peking UniversityBeijing100871

An unusual reduction of some aromatic aldehydes and ketones by sodium borohydride was *** a THF/H2O or DMSO/H2O solvent system the aromatic aldehydes and ketones with acyloxy substituent on the orthoposition to the carbonyl group can be reduced to the corresponding alkyl *** unusual reduction is applicable also to the corresponding alcohols of all the above aldehydes and ketones.A putative mechanism was *** addition to the above aldehydes,ketones and benzyl alcohols,certain 4acyloxybenzyl esters(probably also the 2substituted analogues)such as 4benzoyloxybenzyl benzoate was also found to be reduced to methylphenol by this unusual reduction.

关键词： Reduction Sodium borohydride Benzaldehyde Aromatic ketone

In-network caching for energy efficiency in content-centric networking

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The Journal of China Universities of Posts and Telecommunications 2014年第4期21卷 25-31页

作者： WANG Guo-qing HUANG Tao LIU Jiang xie ren-chao LIU Yun-jie State Key Laboratory of Networking and Switching Technology School of Telecommunication EngineeringBeijing University of Posts and Telecommunications

Recently, Internet energy efficiency is paid more and more attention. New Internet architectures with more energy efficiency were proposed to promote the scalability in energy consumption. The eontent-eentrie networking （CCN） proposed a content-centric paradigm which was proven to have higher energy efficiency. Based on the energy optimization model of CCN with in-network caching, the authors derive expressions to tradeoff the caching energy and the transport energy, and then design a new energy efficiency cache scheme based on virtual round trip time （EV） in CCN. Simulation results show that the EV scheme is better than the least recently used （LRU） and popularity based cache policies on the network average energy consumption, and its average hop is also much better than LRU policy.

关键词： CCN EV cache scheme energy efficiency

Difference and similarity between type A interrupted aortic arch and aortic coarctation in adults:Two case reports

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World Journal of Clinical Cases 2022年第11期10卷 3472-3477页

作者： Si-xie ren Qian Zhang Pan-Pan Li Xiao-Dong Wang Department of Radiology Chengdu Second People’s HospitalChengdu 610000Sichuan ProvinceChina Department of Radiology First Hospital of Shanxi Medical UniversityTaiyuan 030000Shanxi ProvinceChina Department of Radiology Sichuan Cancer HospitalChengdu 610000Sichuan ProvinceChina

BACKGROUND Aortic coarctation(CoA)is usually confused with interrupted aortic arch(IAA),especially adult type A interrupted aortic arch,due to their similar anatomical *** the main difference between them is whether arterial lumen exhibits continuity or not,the clinical manifestations are similar and connection exists between *** type A IAA is considered as an extreme form of CoA,which is complete discontinuity of aortic function and lumen caused by degenerative arterial *** paper reports two cases(interrupted aortic arch and severe aortic coarctation)to analyze the difference and similarity between *** SUMMARY The two cases of patients presented with hypertension for many *** tomography angiography showed that the aortic arch and descending aorta were discontinuous or significantly narrowed with extensive collateral *** IAA patient refused surgical treatment and blood pressure could be controlled with *** the CoA patient underwent stent implantation because of uncontrollable hypertension,the blood flow recovered smoothly and the blood pressures at both ends of the stenosis returned to normal after *** Adult type A IAA and CoA have difference and similarity,and type A IAA is associated with CoA to a certain *** treatment method should be chosen based on the patient's clinical symptoms rather than the severity of the lesion.

关键词： Interrupted aortic arch Aortic coarctation Computed tomography Angiogram Case report