Switching of Slow Magnetic Relaxation Dynamics in Mononuclear Dysprosium(III) Compounds with Charge Density

The symmetry around a Dy ion is recognized to be a crucial parameter dictating magnetization relaxation dynamics. We prepared two similar square-antiprismatic complexes, [Dy(LOMe)2(H2O)2](PF6) (1) and Dy(LOMe)2(NO3) (2), where LOMe = [CpCo{P(O)(O(CH3))2}3], including either two neutral water molecules (1) or an anionic nitrate ligand (2). We demonstrated that in this case relaxation dynamics is dramatically affected by the introduction of a charged ligand, stabilizing the easy axis of magnetization along the nitrate direction. We also showed that the application of either a direct-current field or chemical dilution effectively stops quantum tunneling in the ground state of 2, thereby increasing the relaxation time by over 3 orders of magnitude at 3.5 K.FP7-ERC-247384ERC-2014-CoG/ 647301MAT2014-56143-RCTQ2014-52758-PMDM-2015-0538The symmetry around a Dy ion is recognized to be a crucial parameter dictating magnetization relaxation dynamics. We prepared two similar square-antiprismatic complexes, [Dy(LOMe)2(H2O)2](PF6) (1) and Dy(LOMe)2(NO3) (2), where LOMe = [CpCo{P(O)(O(CH3))2}3], including either two neutral water molecules (1) or an anionic nitrate ligand (2). We demonstrated that in this case relaxation dynamics is dramatically affected by the introduction of a charged ligand, stabilizing the easy axis of magnetization along the nitrate direction. We also showed that the application of either a direct-current field or chemical dilution effectively stops quantum tunneling in the ground state of 2, thereby increasing the relaxation time by over 3 orders of magnitude at 3.5 K

The complete mitochondrial genome of the sand dollar Astriclypeus mannii (Verrill, 1867) (Echinoidea: Astriclypeidae) in the subtidal sand flat in Jeju Island off the south coast of Korea

We sequenced the complete mitochondrial genome of sand dollar Astriclypeus mannii (Verrill 1867) (Echinoidea: Astriclypeidae) occurring in the subtidal sand flat in Jeju Island off the south coast of Korea. The mitochondrial genome was 15,744 bp in length and contained 13 protein-coding genes (PCGs), 22 transfer RNAs, two ribosomal RNAs, and 140 nucleotides representing the putative control region. We reconstructed the concatenated phylogenetic tree based on 13 PCGs of 18 echinoderms, including A. mannii. From the maximum likelihood clustering, A. mannii was grouped in the order Echinolampadacea. The complete mitochondrial sequence of A. mannii for the first time in this study provide valuable insight in understanding the evolution and phylogenetic analysis of echinoids (sea urchins)

Developing harmonic structure in CoCrFeMnNi high entropy alloy to enhance mechanical properties via powder metallurgy approach

The FCC structured CoCrFeMnNi high entropy alloy (HEA) has attracted great attention due to its excellent ductility and strain hardening ability, but the lowest yield strength is insufficient for structural applications. To achieve high strength and ductility, we developed a new strategy called harmonic structure (HS) consisting of soft coarse and hard fine grains via controlled mechanical milling time. The SEM and EBSD microscopic characterizations reveal that the formation of HS from surface to the interior of powder is due to a difference in the degree of plastic deformation. The hardness of HS HEAs increased with increasing distance from center to surface regions due to a reduction in grain size. Compared with the homogeneous HEA, the yield strength of HS HEAs increased from 370 MPa to 730 MPa and 760 MPa due to grain boundary strengthening, dislocation strengthening, and twin boundary strengthening effects. While HS HEAs exhibited enhanced strain hardening ability due to gradient structure with their mechanical incompatibility provide back stress strengthening. Furthermore, the compressive deformation behavior of homogeneous and HS HEAs was analyzed by microstructural evolution.(c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).11Nsciescopu

Reversible Structural Flexibility and Sensing Properties of a Zn(II) Metal–Organic Framework: Phase Transformation between Interpenetrating 3D Net and 2D Sheet

A three-dimensional Zn­(II) framework, [Zn₄O­(L)₃(DMF)₂]·0.5DMF·H₂O (<b>1</b>; H₂L = 3,3′-dimethoxybiphenyl-4,4′-dicarboxylic acid) was prepared under a solvothermal reaction in DMF. The structure reveals that the 3-fold interpenetration is stabilized in the framework with a distinct secondary building unit of the formula [Zn₄O­(R-CO₂)₆(DMF)₂], slightly different from that of MOF-5. Phase transformations in <b>1</b> occur reversibly via two pathways of solvent exchange/resolvation and activation/resolvation, which is indicative of the presence of extensive structural flexibility. Nitrobenzene among tested solvents is selectively detected by <b>1</b>, and the sensing event was operating repeatedly. The three-dimensional framework of <b>1</b> with 3-fold interpenetration is uniquely converted to the two-dimensional Cu phase with no interpenetration, reflecting a drastic dimensionality variation

Worn surface and subsurface layer structure formation behavior on wear mechanism of CoCrFeMnNi high entropy alloy in different sliding conditions

In this study, equiatomic CoCrFeMnNi high entropy alloy (HEA) was fabricated by induction melting and sub-sequent thermomechanical treatments were carried out to achieve single FCC phase with equiaxed grains. The friction and wear behavior of HEA was investigated using ball-on-disc configuration in dry and ambient con-ditions under different sliding time, normal load and velocity. The detailed microscopic characterizations were invested to examine the worn surface and subsurface deformation mechanisms to identify the kinds of wear involved during dry sliding process. Results revealed the hardness of deformed layer showed 63% higher than matrix owing to grain refinement induced by sliding friction. The friction coefficient stabilized at longer sliding time due to oxidized wear debris acting as as lubricant behavior during sliding. While wear rate significantly decreased with increasing sliding time due to oxidation of wear debris on worn surface and formation of deformed layer with grain refinement resists the plastic deformation by strengthening the subsurface layers. On the other hand, wear rate stabilized for 6 and 8 N due to worn surface oxidation and subsurface hardening. Moreover, wear rate stabilized at higher sliding velocity owing to balance between subsurface hardening and delamination behavior.11Nsciescopu

Reversible Structural Flexibility and Sensing Properties of a Zn(II) Metal–Organic Framework: Phase Transformation between Interpenetrating 3D Net and 2D Sheet

A three-dimensional Zn­(II) framework, [Zn₄O­(L)₃(DMF)₂]·0.5DMF·H₂O (<b>1</b>; H₂L = 3,3′-dimethoxybiphenyl-4,4′-dicarboxylic acid) was prepared under a solvothermal reaction in DMF. The structure reveals that the 3-fold interpenetration is stabilized in the framework with a distinct secondary building unit of the formula [Zn₄O­(R-CO₂)₆(DMF)₂], slightly different from that of MOF-5. Phase transformations in <b>1</b> occur reversibly via two pathways of solvent exchange/resolvation and activation/resolvation, which is indicative of the presence of extensive structural flexibility. Nitrobenzene among tested solvents is selectively detected by <b>1</b>, and the sensing event was operating repeatedly. The three-dimensional framework of <b>1</b> with 3-fold interpenetration is uniquely converted to the two-dimensional Cu phase with no interpenetration, reflecting a drastic dimensionality variation

Phase Transformation, Exceptional Quenching Efficiency, and Discriminative Recognition of Nitroaromatic Analytes in Hydrophobic, Nonporous Zn(II) Coordination Frameworks

Five-fold interpenetrated Zn­(II) frameworks (<b>1</b> and <b>2</b>) have been prepared, and an irreversible phase transformation from <b>1</b> to <b>2</b> is found to occur through a dissolution–recrystallization process. Compound <b>1</b> exhibits the highest quenching efficiency (>96%) for nitrobenzene at 7 ppm among luminescent coordination polymers. Selective discrimination of nitroaromatic molecules including <i>o</i>-nitrophenol (<i>o</i>-NP), <i>p</i>-nitrophenol (<i>p</i>-NP), 2,4-dinitrophenol (DNP), and 2,4,6-trinitrophenol (TNP) is realized in <b>1</b> and <b>2</b> as a result of the fact that the framework–analyte interaction affords characteristic emission signals. This observation is the first case of a nonporous coordination framework for such discriminative detection. Notably, significant hydrophobicity is evident in the framework <b>1</b> because of its surface roughness, which accounts for the enhanced quenching ability

Correlation between fracture toughness and stretch-flangeability of advanced high strength steels

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Synthesis, Structures, and Magnetic Properties of End-to-End Azide-Bridged Manganese(III) Chains: Elucidation of Direct Magnetostructural Correlation

The two one-dimensional chain compounds [Mn­(<b>L1</b>)­(N₃)]·H₂O (<b>1</b>·H₂O; H₂<b>L1</b> = 2,2′-((1<i>E</i>,1′<i>E</i>)-ethane-1,2-diylbis­(azan-1-yl-1-ylidene))­bis­(phenylmethan-1-yl-1-ylidene)­diphenol) and [Mn­(<b>L2</b>)­(N₃)] (<b>2</b>; H₂<b>L2</b> = 2,2′-((1<i>E</i>,1′<i>E</i>)-2,2-dimethylpropane-1,3-diyl)­bis­(azan-1-yl-1-ylidene)-bis­(phenylmethan-1-yl-1-ylidene)­diphenol) bridged by single end-to-end azides were prepared via a self-assembly process. Each Mn­(III) ion exhibits a characteristic Jahn–Teller elongation along the chain direction. For both compounds, antiferromagnetic interactions between Mn­(III) spins within a chain are transmitted through the azide ligands, together with the apparent occurrence of spin canting at low temperatures. Remarkably, the coupling constants (<i>J</i>) for <b>1</b> and <b>2</b> exceed those reported for end-to-end azide-linked Mn­(III) systems. A systematic magnetostructural relationship based on the torsion angle is established in terms of the torsion angle Mn–N_ax···N_ax–Mn (ax = axial) for the first time