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Giant magnetocaloric effect in Tb_5Ge_(2-x)Si_(2-x)Mn_(2x) compounds

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Chinese Physics B 2010年第5期19卷 542-548页

作者： E.yzak B.Emre y.Elerman A.ycel Department of Engineering Physics Faculty of EngineeringAnkara University06100 BesevlerAnkaraTurkey Faculty of Science and Letters Physics DepartmentMugla UniversityKtekli 48000 MuglaTurkey

The crystal structure, magnetic and magnetocaloric characteristics of the pseduo ternary compounds of TbsGe2-xSi2-xMn2x （0 ≤ 2x ≤ 0.1） were investigated by x-ray powder diffraction and magnetization measurements. The x-ray powder diffraction results show that all compounds preserve the monoclinic phase as the majority phase and all the synthesized compounds were observed to be ferromagnetic from magnetization measurements. Magnetic phase transitions were interpreted in terms of Landau theory. Maximum isothermal magnetic entropy change value （20.84 J-kg-1 -K-1） was found for Tb5Ge1.95Si1.95Mn0.1 at around 123 K in the magnetic field change of 5T.

关键词： magnetic properties magnetocaloric effect isothermal magnetic entropy change

AN HREM STUDy OF A LATERAL MICROCRACK BENEATHINDENTATION OF [001] SILICON

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Acta Metallurgica Sinica(English Letters) 1998年第5期11卷 342-346页

作者： y.Q.Wu X.y.yang y.B.Xu Inst of Metal Research The Chinese Acad of Sciences Shenyang China

A cross-sectional sample of indentation in [001] silicon was made and a lateral microcrack beneath the indentation was observed by high resolution electron microscope (HREM). The HREM images around the microcrack tip show an alternate distribution of the amorphous and lattice structure. The crack does not propagate by the successive debonding between certain atomic planes, meaning that before a crack completely opens, there may be a stage of amorphization, resulting from severe distortion of lattice.

关键词： amorphization lateal crack indentation HREM silicon

Equivariant PT-symmetric real Chern insulators

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Frontiers of physics 2020年第1期15卷 63-69,F0004页

作者： y.X.zhao National laboratory of solid state microstructures and department of physics nanjing universitynanjing 210093china Collaborative innovation center of advanced microstructures nanjing universitynanjing 210093china

It was understood that Chern insulators cannot be realized in the presence of PT *** this paper,we reveal a new class of PT-symmetric Chern insulators,which has internal degrees of freedom forming real representations of a symmetry group with a complex endomorphism *** a generalization to the conventional 2n-dimensional Chern insulators with integer n≥1,these PT-symmetric Chern insulators have the n-th complex Chern number as their topological invariant,and have a Z classification given by the equivariant orthogonal K ***,in a fairly different sense,there exist ubiquitously Chern insulators with *** generalizing the Thouless charge pump argument,we find that,for a PT-symmetric Chern insulator with Chern number *** are equally many v flavors of coexisting left-and right-handed chiral *** modes with opposite chirality are complex conjugates to each other as complex representations of the internal symmetry group,but are not *** the physical dimensionality d=2,the PT-symmetric Chern insulators may be realized in artificial systems including photonic crystals and periodic mechanical systems.

关键词： topological insulator Chern insulator

Ecological toxicity of reactive X-3B red dye and cadmium acting on wheat (Triticum aestivum)

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Journal of Environmental Sciences 2002年第1期14卷 136-140页

作者： Chen.y ZhouQX OpenLaboratoryofTerrestrialEcologicalProcess InstituteofAppliedEcologyChineseAcademyofSciencesShenyang110016China.E－mail：zhouq@*** OpenLaboratoryofTerrestrialEcologicalProcess Instituteof

Ecological toxicity of reactive X\|3B red dye and cadmium in both their single form and their combined form on wheat was studied using the experimental method of seed and root exposure. The single factor exposure indicated that the inhibitory rate of wheat root elongation was significantly increased with the increase in the concentration of the dye in the cultural solution, although seed germination of wheat was not sensitive to the dye. The toxicity of cadmium was greatly higher than that of the dye, but low concentration cadmium (ye and cadmium on wheat were complicated. There was no significant correlation between the inhibitory rate of seed germination and the concentrations of the dye and cadmium. Low concentration cadmium could strengthen the toxicity of the dye acting on root elongation. On the contrary, high concentration cadmium could weaken the toxicity of the dye acting on root elongation.

关键词： ecological toxicity reactive X 3B red dye cadmium combined pollution wheat

Effect of Strain Rate on Hydrogen Embrittlement Behaviour of Amorphous NiCrFeSiB Alloy

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Journal of Materials Science & Technology 1996年第2期12卷 105-108页

作者： Zuo, y Latanision, RM MIT CAMBRIDGEMA 02139

The effect of strain rate on hydrogen embrittlement behaviour of amorphous Ni-6.6Cr-2.6Fe-7.8Si-14.5B (at pct) alloy in 0.1 mol/L H2SO4 solution was studied by the methods of slow strain rate test and electrochemical charging. The results show that fracture stress of the alloy decreases with the decrease of strain rate within a certain range. As a tentative explanation, the effect of strain rate on hydrogen embrittlement fracture stress was attributed to the interaction between hydrogen and the excess volume in amorphous alloys.

关键词： Amorphous alloys

Effect of Aging Treatment on Microstructural and Mechanical Characteristics of PEO Coatings on Mg-Al Alloy

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Journal of Materials Science & Technology 2008年第1期24卷 37-40页

作者： y.L.Kim Department of Materials Engineering Korea Aerospace University Gyeonggi-do412-791Korea

Cast Mg-6 wt pct Al alloy solution-treated at 683 K for 16 h and aged at 498 K was coated by plasma electrolytic oxidation （PEO） *** Mg-6 wt pct Al alloy aged for 16 h exhibited the highest microhardness and wear *** PEO coating,however,the microhardness and wear resistance of coatings on Mg- 6 wt pct Al alloy showed a tendency to decrease with increasing aging time,which was in aggrement with the change of thickness with aging *** addition,the coatings on solution-treated Mg-6 wt pct Al alloy had better microhardness and wear resistance than those on aged Mg-6 wt pct Al ***,it can be understood that the aging treatment has a deleterious influence on the mechanical properties of coatings on Mg-6 wt pct Al alloy.

关键词： Cast Mg-6 wt pct Al Aging treatment Plasma electrolytic oxidation Thickness Microhardness Wear resistance

New Naturally Occurring Product Extract as Corrosion Inhibitor for 316 Stainless Steel in 5% HCl

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Journal of Materials Science & Technology 2004年第4期20卷 463-466页

作者： T.y.Soror Chemistry Department Faculty of Science Cairo University Cairo Egypt

Medipolymorphol, a new sterol isolated from the whole plant of Medicago polymorpha Roxb was used as corrosion inhibitor for 316 stainless steel in 5% HCI at room temperature. Electrochemical techniques have been found to be reliable in evaluating corrosion characteristics of the system. Several techniques have been used including Tafel, linear polarization, potentiodynamic polarization, and open circuit potential (OCP) studies. The additives simultaneously deaccelerated the anodic process, intensified the cathodic process and provided a stable passive state, giving good inhibition efficiencies to stainless steel electrodes. In addition, adsorption isotherm have been fitted for the inhibitor under investigation.

关键词： Medipolymorpho] Plant extract Stainless steel HCl Corrosion inhibitor

Motion of the moonlet in the binary system 243 Ida

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Acta Mechanica Sinica 2018年第1期34卷 214-224页

作者： L.Lan y.Ni y.Jiang J.Li School of Aerospace Engineering Tsinghua University State Key Laboratory of Astronautic Dynamic Xi'an Satellite Control Center

The motion of the moonlet Dactyl in the binary system 243 Ida is investigated in this paper. First, periodic orbits in the vicinity of the primary are calculated, including the orbits around the equilibrium points and large-scale orbits. The Floquet multipliers’ topological cases of periodic orbits are calculated to study the orbits’ stabilities. During the continuation of the retrograde near-circular orbits near the equatorial plane, two period-doubling bifurcations and one Neimark–Sacker bifurcation occur one by one, leading to two stable regions and two unstable regions. Bifurcations occur at the boundaries of these regions. Periodic orbits in the stable regions are all stable, but in the unstable regions are all unstable. Moreover, many quasi-periodic orbits exist near the equatorial plane. Long-term integration indicates that a particle in a quasi-periodic orbit runs in a space like a tire. Quasi-periodic orbits in different regions have different styles of motion indicated by the Poincare sections. There is the possibility that moonlet Dactyl is in a quasi-periodic orbit near the stable region I, which is enlightening for the stability of the binary system.

关键词： Binary system Bifurcation Periodic orbits Quasi-periodic orbits

First principles calculations on the thermoelectric properties of bulk Au2S with ultra-low lattice thermal conductivity

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Chinese Physics B 2020年第8期29卷 108-114页

作者： y y Wu X L Zhu H y yang Z G Wang y H Li B T Wang School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Spallation Neutron Source Science Center Dongguan 523808China School of Materials Science and Engineering Hunan University of Science and TechnologyXiangtan 411201China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

Sulfide nanocrystals and their composites have shown great potential in the thermoelectric(TE)field due to their extremely low thermal *** a solid and hollow metastable Au2S nanocrystalline has been successfully ***,we study the TE properties of this bulk Au2S by first-principles calculations and semiclassical Boltzmann transport theory,which provides the basis for its further experimental *** results indicate that the highly twofold degeneracy of the bands appears at theΓpoint in the Brillouin zone,resulting in a high Seebeck ***,Au2S exhibits an ultra-low lattice thermal conductivity(~0.88 W·m^-1·K^-1 at 700 K).At 700 K,the thermoelectric figure of merit of the optimal p-type doping is close to 1.76,which is higher than 0.8 of ZrSb at 700 K and 1.4 of PtTe at 750 *** work clearly demonstrates the advantages of Au2S as a TE material and would greatly inspire further experimental studies and verifications.

关键词： first principles calculation thermodynamic transport properties