[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...

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Dye-Sensitized Solar Cells

BiFeO3 is perhaps the only material that is both magnetic and a strong ferroelectric at room temperature. As a result, it has had an impact on the field of multiferroics that is comparable to that of yttrium barium copper oxide (YBCO) on superconductors, with hundreds of publications devoted to it in the past few years. In this Review, we try to summarize both the basic physics and unresolved aspects of BiFeO3 (which are still being discovered with several new phase transitions reported in the past few months) and device applications, which center on spintronics and memory devices that can be addressed both electrically and magnetically.

Physics and Applications of Bismuth Ferrite

Multiferroic magnetoelectric materials, which simultaneously exhibit ferroelectricity and ferromagnetism, have recently stimulated a sharply increasing number of research activities for their scientific interest and significant technological promise in the novel multifunctional devices. Natural multiferroic single-phase compounds are rare, and their magnetoelectric responses are either relatively weak or occurs at temperatures too low for practical applications. In contrast, multiferroic composites, which incorporate both ferroelectric and ferri-/ferromagnetic phases, typically yield giant magnetoelectric coupling response above room temperature, which makes them ready for technological applications. This review of mostly recent activities begins with a brief summary of the historical perspective of the multiferroic magnetoelectric composites since its appearance in 1972. In such composites the magnetoelectric effect is generated as a product property of a magnetostrictive and a piezoelectric substance. A...

Multiferroic magnetoelectric composites: Historical perspective, status, and future directions

R J Baxter 1982 London: Academic xii + 486 pp price £43.60 Over the past few years there has been a growing belief that all the twodimensional lattice statistical models will eventually be solved and that it will be Professor Baxter who solves them. Baxter has inherited the mantle of Onsager who started the process by solving exactly the two-dimensional Ising model in 1944.

Exactly Solved Models in Statistical Mechanics

The polarization fatigue behavior of ferroelectric Pb1-xBax(Zr0.52Ti0.48)O-3 (PBZT) thin films deposited on Pt-coated silicon wafers by sol-gel method is investigated. The fatigue endurance is significantly enhanced upon Ba doping and almost fatigue-free performance up to 1010 switching cycles for PBZT (x=0.1) thin films are observed at room temperature. It is revealed that Ba doping up to x=0.1 results in a 70% decrease of oxygen vacancies in the films. The improved fatigue endurance is attributed to the enhanced oxygen ion stability and suppressed oxygen vacancies.

Fatigue suppression of ferroelectric Pb1_xBax (Zr0.52Ti0.48)O3 thin films prepared by sol-gel method

The Kitaev model on the honeycomb lattice has been receiving substantial attention due to the discovery of quantum spin liquid state associated with this model. Consequently, its classical partners such as the Kitaev-Heisenberg (KH) model and associated phase transitions become concerned. Specifically, an intermediate Kosterlitz-Thouless (KT) phase engaged in the transition from the high-temperature (T) disordered state to the low-T sixfold degenerate state is predicted in the isotropic KH model [Phys. Rev. Lett. 109, 187201 (2012)10.1103/PhysRevLett.109.187201], but so far no sufficient experimental proof has been reported. In this work, we consider an essential extension of this KH model on the honeycomb lattice by including the Kitaev exchange anisotropy that is non-negligible in realistic materials. The associated phase transitions are thus investigated using the Monte Carlo simulations. It is found that such an anisotropy will result in a degradation of the sixfold degeneracy of the ground state in the isotropic KH model down to the fourfold or twofold degenerate ground state, and the finite-T phase transitions will also be modified remarkably. Interestingly, the intermediate KT phase can be suppressed by this Kitaev exchange anisotropy. This work thus provides a more realistic description of the physics ingredient with the KH model and presents a possible explanation on absence of the intermediate phase in real materials where the Kitaev exchange anisotropy can be more or less available.

Phase transitions in the classical exchange-anisotropic Kitaev-Heisenberg model.

Al‐Sn‐Y3元系の室温等温切断状態図

We investigate the effect of Cr-doping in polycrystalline TbMn1−xCrxO3 (x ≤ 6%) ceramics on the magnetism, ferroelectricity, and dielectricity The Cr substitution gradually suppresses the ferroelectricity induced by the Mn spiral spin ordering, and results in a stronger modulation of polarization by magnetic field with increasing x However, the transition temperature TTb corresponding to onset of Tb magnetic ordering has barely shifted with Cr doping In other words, although the Cr-doping obviously disrupts the Mn spiral spin ordering, the exchange field JMn-Tb acting on the Tb moments from the Mn-spin structure is hardly impacted Our work demonstrates that the eg electron of Mn3+ plays an important role in forming the Mn spiral spin order, but the f-d exchange interaction between the Mn 3d spins and the Tb 4f moments in multiferroic TbMnO3 almost involves only the t2g electrons

Role of t2g electrons in Mn-Tb coupling of multiferroic TbMnO3

OBJECTIVE To investigate the potential effects of miR-200c on proliferation and apoptosis of papillary thyroid cancer (PTC) cells. MATERIALS AND METHODS Micro ribonucleic acid-200c (miR-200c) inhibitor was transfected to down-regulate miR-200c expression. Cell counting kit-8 (CCK-8), colony formation experiment, and flow cytometry were used to detect the effects of miR-200c knockdown on proliferation and apoptosis of Butylated Hydroxytoluene 101 (BHT101) cells. The dual-luciferase reporter gene assay was conducted to detect whether miR-200c directly binds to the target gene. After knocking down miR-200c, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting analysis were performed to detect changes of target genes regarding messenger RNA (mRNA) and protein. Western blotting analysis was also adopted to detect gene expression of Wnt/β-catenin signaling pathway-related proteins. RESULTS Compared with those in control group, the proliferation and clone formation ability of BHT101 cells in miR-200c knockdown group were significantly inhibited (p<0.05), while the apoptosis rate increased markedly (p<0.05). Dachshund Family Transcription Factor 1 (DACH1) was the direct target gene of miR-200c. After miR-200c knockdown, the expression levels of Wnt/β-catenin signaling pathway members (including c-Myc, β catenin and cyclin D1) all decreased. CONCLUSIONS MiR-200c is a tumor suppressor miRNA, which promotes proliferation of PTC cells and activates Wnt/β-catenin signaling pathway by directly regulating the corresponding target protein, DACH1.

J.-M. Liu

Papers

Fatigue suppression of ferroelectric Pb1_xBax (Zr0.52Ti0.48)O3 thin films prepared by sol-gel method

Phase transitions in the classical exchange-anisotropic Kitaev-Heisenberg model.

Al‐Sn‐Y3元系の室温等温切断状態図

Role of t2g electrons in Mn-Tb coupling of multiferroic TbMnO3

MiR-200c promotes proliferation of papillary thyroid cancer cells via Wnt/β-catenin signaling pathway.