233 research outputs found
SIZE EFFECTS ON MAGNETIC PROPERTY AND CRYSTAL STRUCTURE OF MN3O4 NANOPARTICLES IN MESOPOROUS SILICA
Mn3O4 nanoparticles with particle sizes of 7.8, 11.4, and 18.3 nm were synthesized in the pores of mesoporous silica, and their crystal structure and magnetic properties were investigated. The powder X-ray diffractions at room temperature indicated that the crystal structural symmetry was the same as that for bulk crystal, and the lattice constants deviated from those for bulk crystal, which depended on the particle size. In addition, compared with the bulk crystal, the Jahn-Teller distortion for the nanoparticles was suppressed and decreased with decreasing the particle size. The coercive field for 7.8 nm was rather smaller than those for 11.4 and 18.3 nm. The nanoparticles with 11.4 and 18.3 nm exhibited pronounced three kinds of magnetic transition temperatures, whereas the susceptibility for 7.8 nm indicated the existence of two transition temperatures. These experimental results suggested that the Mn3O4 nanoparticles have a strong correlation between crystallographic structure and magnetic property, and the characteristic magnetic size effects are attributed to the reduction of Jahn-Teller distortion.The 21st International Conference on Magnetism (ICM2018), July 15-20, 2018, San Francisco, US
Effect of pressure on single-chain magnets with repeating units of the MnIII-NiII-MnIII trimer
The single-chain magnet (SCM) system [Mn2(saltmen)2Ni(pao)2(L)2](A)2 (L: intrachain attaching ligand of NiII ion; A-1: interchain counteranion) is a ferromagnetic one-dimensional network system with repeating units of the MnIII-NiII-MnIII trimer which itself behaves as a single-molecule magnet with an S=3 spin ground state and negative uniaxial single-ion anisotropy (D) parallel to the bridging direction. The slow relaxation of the magnetic moment in this SCM system originates in an energy barrier for spin reversal (ΔE), which is closely related to the ferromagnetic interaction between the trimers (Jtrimer) as well as to the D of the trimer. We have investigated the effects of pressure on three compounds representative of the above SCM family through ac susceptibility measurements under hydrostatic pressures up to P=13.5 kbar and crystal structural analysis experiments up to P=20.0 kbar, and have observed a pronounced enlargement of ΔE when J was artificially increased. The application of hydrostatic pressure brought about the systematic enhancement of EΔ (a maximum increase of 10% within the pressure region of the experiments). The pressure dependence of EΔ varied according to the kind of attaching ligand L involved and the intrachain structure, and we have experimentally found that isotropic lattice shrinkage is desirable if a continuous increase of ΔE in this system is aimed at
Mixbiotic society measures: Assessment of community well-going as living system
Social isolation is caused by the impoverishment of community (atomism) and
fragmentation is caused by the enlargement of in-group (mobism), both of which
can be viewed as social problems related to communication. To solve these
problems, the philosophical world has proposed the concept of "mixbiotic
society," in which individuals with freedom and diverse values mix and mingle
to recognize their respective "fundamental incapability" each other and
sublimate into solidarity. Based on this concept, this study proposes new
mixbiotic society measures to evaluate dynamic communication patterns with
reference to classification in cellular automata and particle reaction
diffusion that simulate living phenomena. Specifically, the hypothesis of
measures corresponding to the four classes was formulated, and the hypothesis
was validated by simulating the generation and disappearance of communication.
As a result, considering communication patterns as multidimensional vectors, it
found that the mean of Euclidean distance for "mobism," the variance of the
relative change in distance for "atomism," the composite measure that
multiplies the mean and variance of cosine similarity for "mixism," which
corresponds to the well-going of mixbiotic society, and the almost zero
measures for "nihilism," are suitable. Then, evaluating seven real-society
datasets using these measures, we showed that the mixism measure is useful for
assessing the livingness of communication, and that it is possible to typify
communities based on plural measures. The measures established in this study
are superior to conventional analysis in that they can evaluate dynamic
patterns, they are simple to calculate, and their meanings are easy to
interpret. As a future development, the mixbiotic society measures will be used
in the fields of digital democracy and platform cooperativism toward a
desirable society.Comment: 52 pages, 10 figure
knn-seq: Efficient, Extensible kNN-MT Framework
k-nearest-neighbor machine translation (kNN-MT) boosts the translation
quality of a pre-trained neural machine translation (NMT) model by utilizing
translation examples during decoding. Translation examples are stored in a
vector database, called a datastore, which contains one entry for each target
token from the parallel data it is made from. Due to its size, it is
computationally expensive both to construct and to retrieve examples from the
datastore. In this paper, we present an efficient and extensible kNN-MT
framework, knn-seq, for researchers and developers that is carefully designed
to run efficiently, even with a billion-scale large datastore. knn-seq is
developed as a plug-in on fairseq and easy to switch models and kNN indexes.
Experimental results show that our implemented kNN-MT achieves a comparable
gain to the original kNN-MT, and the billion-scale datastore construction took
2.21 hours in the WMT'19 German-to-English translation task. We publish our
knn-seq as an MIT-licensed open-source project and the code is available on
https://github.com/naist-nlp/knn-seq . The demo video is available on
https://youtu.be/zTDzEOq80m0
Tartaric acid in red wine as one of the key factors to induce superconductivity in FeTe0.8S0.2
The red wine dependence of superconductivity in FeTe0.8S0.2 was investigated.
Samples with a higher shielding volume fraction had a tendency to show a higher
concentration of tartaric acid in red wine. We found the tartaric acid is one
of the key factors to induce superconductivity in FeTe0.8S0.2.Comment: 9 pages, 4 figure
Pressure-Induced Ferromagnetic to Nonmagnetic Transition and the Enhancement of Ferromagnetic Interaction in the Thiazyl-Based Organic Ferromagnet γ-BBDTA·GaCl4
A thiazyl-based ferromagnet, the γ-phase of BBDTA (i.e., benzo[1,2- d :4,5- d \u27]bis[1,3,2]dithiazole)·GaCl 4 , has a high ferromagnetic ordering temperature of 7.0 K in organic radical ferromagnets. In this system, pressurization generated more compact molecular packing, resulting in that the ferromagnetic state at P = 16.2 kbar is stabilized over a temperature range of more than twice of the initial range. However, the saturation magnetic moment was reduced with increasing pressure, decreasing to about 12% of the initial value even at the low pressure level of P = 1.0 kbar. This suggests that the ferromagnetic molecular packing of the monoclinic γ-phase is easily transformed into that of the diamagnetic phase. Powder X-ray diffraction experiments revealed that the diamagnetic non-monoclinic (α- or β-) phase became stable instead of the monoclinic γ-phase across the pressure of 2.5–5.8 kbar. The increase in the temperature of onset of ferromagnetic state occurs in the surviving ferromagnetic domain surrounded by the diamagnetic domains
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