Catalytic synthesis and enhanced Curie temperature of ε-Fe₃N@C nanostructure synthesized in a tetraethylenepentamine solution

Li, Yong,Pan, Desheng,Li, Da,Feng, Yang,Choi, C.J.,Liu, Wei,Zhang, Zhidong Elsevier 2018 Journal of magnetism and magnetic materials Vol.465 No.-

<P><B>Abstract</B></P> <P>ε-Fe<SUB>3</SUB>N@C nanocrystals without oxidation are one-pot synthesized by using the iron(II) acetylacetonate and tetraethylenepentamine (TEPA) as Fe and N precursors under a low temperature (533 K) in the presence of a small quantity of Pt atoms as the co-catalyst. The ε-Fe<SUB>3</SUB>N@C nanoparticles with a core-shell structure are nearly spherical and have a wide particle size distribution of 100–500 nm in diameter. Fe nanoparticles obtained by reduction of Fe<SUP>2+</SUP> with TEPA are an effective catalyzer for decomposing TEPA to produce N and C atoms at a temperature much lower than the boiling point of TEPA. The diffusion of N atoms into Fe nanoparticles for the formation of ε-Fe<SUB>3</SUB>N@C is proposed, based on the results obtained by kinetically controlling the synthetic temperature and surfactants. The ε-Fe<SUB>3</SUB>N@C nanoparticles have an excellent saturation magnetization of 135.5 emu/g at room temperature. A significantly enhanced Curie temperature (T<SUB>C</SUB>) of 614 K is reached in the present ε-Fe<SUB>3</SUB>N@C nanoparticles, which is much higher than the T<SUB>C</SUB> values in the previously reported ε-Fe<SUB>3</SUB>N<SUB>x</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Tetraethylenepentamine is proposed as a new N source to synthesize Fe nitride. </LI> <LI> Core-shelled ε-Fe<SUB>3</SUB>N@C nanoparticles are one-pot synthesized at 260 °C. </LI> <LI> Curie temperature of ε-Fe<SUB>3</SUB>N is significantly enhanced to 614 K. </LI> <LI> ε-Fe<SUB>3</SUB>N@C shows a high saturation magnetization of 135.5 emu/g at 300 K. </LI> </UL> </P>

Prospect and status of iron-based rare-earth-free permanent magnetic materials

Li, Da,Li, Yong,Pan, Desheng,Zhang, Zhidong,Choi, Chul-Jin Elsevier 2019 Journal of magnetism and magnetic materials Vol.469 No.-

<P><B>Abstract</B></P> <P>With the advent of high performance permanent magnets based on the rare-earth (RE) elements such as Sm-Co, Nd-Fe-B alloys in 1980s, the application areas have been extended from the electronics to hybrid electric vehicles and wind turbines etc. However, the advantages of these RE based magnets may be overshadowed by the supply constraints, high prices and environmental issues. Much attention has been paid on non-RE element based permanent magnetic materials as next generation of permanent magnetic materials, due to low cost, large coercivity and high Curie temperatures (working temperatures). A variety of methods are available to manufacture RE-free permanent magnetic materials in bulk, nanostructure, nanocomposite and thin films. The proper scale-up methods to produce magnetic nanostructures with high energy efficiency have still been a significant challenge, which are very important to the development of novel RE-free permanent magnetic materials to meet tomorrow’s energy needs. In this review paper, we emphasize to introduce the prospect and status of developments of iron-based RE-free hard-magnetic nanomaterials involving magnetic thin films, nanocomposites and nanostructures.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Several fundamental physics effects of magnetic theory are introduced for high permanent magnetic properties. </LI> <LI> The research progress of Fe-based rare-earth-free hard-magnetic materials is reviewed. </LI> <LI> The magnetic properties and preparation method of Fe-based hard-magnetic nanomaterials are summarized. </LI> </UL> </P>

Experimental Studies on Active Noise Control Using Smart Structures

Desheng Li,Li Cheng,Clement Gosselin 한국소음진동공학회 2003 한국소음진동공학회 국제학술대회논문집 Vol.2003 No.8

ATTRACTORS OF LOCAL SEMIFLOWS ON TOPOLOGICAL SPACES

Li, Desheng,Wang, Jintao,Xiong, Youbing Korean Mathematical Society 2017 대한수학회지 Vol.54 No.3

In this paper we introduce a notion of an attractor for local semiflows on topological spaces, which in some cases seems to be more suitable than the existing ones in the literature. Based on this notion we develop a basic attractor theory on topological spaces under appropriate separation axioms. First, we discuss fundamental properties of attractors such as maximality and stability and establish some existence results. Then, we give a converse Lyapunov theorem. Finally, the Morse decomposition of attractors is also addressed.

Optimal design of active noise control systems in rooms using the Image-GA method

Desheng Li,Murray Hodgson,Ann Nakashima 한국소음진동공학회 2003 한국소음진동공학회 국제학술대회논문집 Vol.2003 No.8

ATTRACTORS OF LOCAL SEMIFLOWS ON TOPOLOGICAL SPACES

Desheng Li,Jintao Wang,Youbing Xiong 대한수학회 2017 대한수학회지 Vol.54 No.3

In this paper we introduce a notion of an attractor for local semiflows on topological spaces, which in some cases seems to be more suitable than the existing ones in the literature. Based on this notion we develop a basic attractor theory on topological spaces under appropriate separation axioms. First, we discuss fundamental properties of attractors such as maximality and stability and establish some existence results. Then, we give a converse Lyapunov theorem. Finally, the Morse decomposition of attractors is also addressed.

Partly Random Multiple Weighting Matrices Selection for Orthogonal Random Beamforming

Li Tan,Zhongcai Li,Chao Xu,Desheng Wang 한국통신학회 2016 Journal of communications and networks Vol.18 No.6

In the multi-user multiple-input multiple-output(MIMO) system, orthogonal random beamforming (ORBF)scheme is proposed to serve multiple users simultaneously in orderto achieve the multi-user diversity gain. The opportunistic spacedivisionmultiple access system (OSDMA-S) scheme performs multipleweighting matrices during the training phase and choosesthe best weighting matrix to be used to broadcast data during thetransmitting phase. The OSDMA-S scheme works better than theoriginal ORBF by decreasing the inter-user interference duringthe transmitting phase. To save more time in the training phase,a partly random multiple weighting matrices selection scheme isproposed in this paper. In our proposed scheme, the Base Stationdoes not need to use several unitary matrices to broadcast pilotsymbol. Actually, only one broadcasting operation is needed. Each subscriber generates several virtual equivalent channels witha set of pre-saved unitary matrices and the channel status informationgained from the broadcasting operation. The signal-tointerferenceand noise ratio (SINR) of each beam in each virtualequivalent channel is calculated and fed back to the base stationfor the weighting matrix selection and multi-user scheduling. Accordingto the theoretical analysis, the proposed scheme relativelyexpands the transmitting phase and reduces the interactive complexitybetween the Base Station and subscribers. The asymptoticanalysis and the simulation results show that the proposed schemeimproves the throughput performance of the multi-user MIMOsystem.

Partly Random Multiple Weighting Matrices Selection for Orthogonal Random Beamforming

Tan, Li,Li, Zhongcai,Xu, Chao,Wang, Desheng The Korea Institute of Information and Commucation 2016 Journal of communications and networks Vol.18 No.6

In the multi-user multiple-input multiple-output (MIMO) system, orthogonal random beamforming (ORBF) scheme is proposed to serve multiple users simultaneously in order to achieve the multi-user diversity gain. The opportunistic space-division multiple access system (OSDMA-S) scheme performs multiple weighting matrices during the training phase and chooses the best weighting matrix to be used to broadcast data during the transmitting phase. The OSDMA-S scheme works better than the original ORBF by decreasing the inter-user interference during the transmitting phase. To save more time in the training phase, a partly random multiple weighting matrices selection scheme is proposed in this paper. In our proposed scheme, the Base Station does not need to use several unitary matrices to broadcast pilot symbol. Actually, only one broadcasting operation is needed. Each subscriber generates several virtual equivalent channels with a set of pre-saved unitary matrices and the channel status information gained from the broadcasting operation. The signal-to-interference and noise ratio (SINR) of each beam in each virtual equivalent channel is calculated and fed back to the base station for the weighting matrix selection and multi-user scheduling. According to the theoretical analysis, the proposed scheme relatively expands the transmitting phase and reduces the interactive complexity between the Base Station and subscribers. The asymptotic analysis and the simulation results show that the proposed scheme improves the throughput performance of the multi-user MIMO system.

Dynamics of oppositely charged carriers in a metal/coupled poly(p-phenylene vinylene) chains/metal structure

Dong-Mei Li,Yuan Li,Hai-Hong Li,Desheng Liu 한국물리학회 2011 Current Applied Physics Vol.11 No.2

By using the extended version of the Su-Schrieffer-Heeger (SSH) tight-binding model and a non-adiabatic dynamic evolution method, we present a study of the dynamic process of oppositely charged carriers in a metal/two coupled poly(p-phenylene vinylene) chains/metal structure. Electrons and holes can be injected into the polymer chains from metal electrodes by applying voltage biases. The behavior of the injected charged carriers depends closely on the electric field and the interchain coupling. The moderate intensity of electric field is in favor of forming stable wave packets, and the charge carriers localized in wave packets occur to transport, hopping, collide and recombine. With increasing the electric field, part of the carriers can be ejected into the metal electrodes.

Epigenetic silencing of UBXN8 contributes to leukemogenesis in t(8;21) acute myeloid leukemia

Yang Erna,Guan Wei,Gong Desheng,Li Jieying,Han Caixia,Zhang Juan,Wang Hong,Kang Synat,Gao Xuefeng,Li Yonghui,Yu Li 생화학분자생물학회 2021 Experimental and molecular medicine Vol.53 No.-

The formation of the RUNX1-RUNX1T1 fusion protein, resulting from the t(8;21) translocation, is considered to be one of the initiating events of t(8;21) acute myeloid leukemia (AML). However, the mechanisms of the oncogenic mechanism of RUNX1- RUNX1T1 remain unclear. In this study, we found that RUNX1-RUNX1T1 triggers the heterochromatic silencing of UBXN8 by recognizing the RUNX1-binding sites and recruiting chromatin-remodeling enzymes to the UBXN8 promoter region. Decitabine, a specific inhibitor of DNA methylation, upregulated the expression of UBXN8 in RUNX1-RUNX1T1+ AML cell lines. Overexpression of UBXN8 inhibited the proliferation and colony-forming ability of and promoted cell cycle arrest in t(8;21) AML cell lines. Enhancing UBXN8 levels can significantly inhibit tumor proliferation and promote the differentiation of RUNX1-RUNX1T1+ cells in vivo. In conclusion, our results indicated that epigenetic silencing of UBXN8 via methylation of its promoter region mediated by the RUNX1- RUNX1T1 fusion protein contributes to the leukemogenesis of t(8;21) AML and that UBXN8 targeting may be a potential therapeutic strategy for t(8;21) AML. The formation of the RUNX1-RUNX1T1 fusion protein, resulting from the t(8;21) translocation, is considered to be one of the initiating events of t(8;21) acute myeloid leukemia (AML). However, the mechanisms of the oncogenic mechanism of RUNX1-RUNX1T1 remain unclear. In this study, we found that RUNX1-RUNX1T1 triggers the heterochromatic silencing of UBXN8 by recognizing the RUNX1-binding sites and recruiting chromatin-remodeling enzymes to the UBXN8 promoter region. Decitabine, a specific inhibitor of DNA methylation, upregulated the expression of UBXN8 in RUNX1-RUNX1T1 + AML cell lines. Overexpression of UBXN8 inhibited the proliferation and colony-forming ability of and promoted cell cycle arrest in t(8;21) AML cell lines. Enhancing UBXN8 levels can significantly inhibit tumor proliferation and promote the differentiation of RUNX1-RUNX1T1 + cells in vivo. In conclusion, our results indicated that epigenetic silencing of UBXN8 via methylation of its promoter region mediated by the RUNX1-RUNX1T1 fusion protein contributes to the leukemogenesis of t(8;21) AML and that UBXN8 targeting may be a potential therapeutic strategy for t(8;21) AML.