Electronic properties of alkali-metal loaded zeolites -- a "supercrystal" Mott insulator

First-principles band calculations are performed for the first time for an open-structured zeolite (LTA) with guest atoms (potassium) introduced in their cages. A surprisingly simple band structure emerges, which indicates that this system may be regarded as a "supercrystal", where each cluster of guest atoms with diameter $\sim$10\AA acts as a "superatom" with well-defined $s$- and $p$-like orbitals, which in turn form the bands around the Fermi energy. The calculated Coulomb and exchange energies for these states turn out to be in the strongly-correlated regime. With the dynamical mean-field theory we show the system should be on the Mott-insulator side, and, on a magnetic phase diagram for degenerate-orbital systems, around the ferromagnetic regime, in accord with experimental results. We envisage this class of systems can provide a new avenue for materials design.Comment: 4 pages, 4 figure

High-resolution reconstruction of late Pleistocene climate based on TOC content in a 54m sediment core drilled from Takano Formation, central Japan

The Takano Formation of late Pleistocene lacustrine sediment is distributed at the southern Nagano City. The TKN-2004 core, 53.88 m long, was taken at the central part or the basin, and is composed mostly or homogenous clayey silt. Age of the sediment was estimated from the relationship between radiometric ages and calibrated depths of DKP,Aso-4,K-Tz,Ata and Aso-2tephras, postulating that the sedimentation rate is constant.Paleoclimate from 169ka to 37ka was reconstructed on the basis of TOC content variation. The long-term TOC fluctuations are concordant with the SPECMAP curve. This result is supported by pollen composition. The short-term variations are similar to stadial-interstadial cycles in the Greenland ice cores, and most of warm peaks can be correlated with IS 9 to 25.長野市南部に分布する更新世後期の湖成層である高野層において,全層ボーリングを行い53.88mの連続したコア試料を得た.コア試料は,黒灰色ではぼ均質な粘土質シルト～シルトの層相を示し,多数のテフラ層を挟んでいる.これらのうち5つの広域指標テフラ(DKP,Aso-4,K-Tz, Ata,Aso-2)の放射年代値と補正深度を用いて年代モデルを作成した.高野層のTOC含有率の経年変動は,本コア試料中の花粉組成変化と同調しており,およそ169ka～37kaにおける数万年周期の長期の気候変動を示している.この変動はMIS 6-3前半における海洋酸素同位体比変動と同調しており,各ステージに対比される長期の温暖期･寒冷期が認識できた.また,数百～数千年周期の短期の寒暖変動も存在しており,これらは亜氷期-亜間氷期サイクルに相当すると考えられる.また,それらの温暖期の多くはIS9～25に対比される可能性がある.ArticleJournal of the Sedimentological Society of Japan. 64:37-41 (2007)journal articl

Magnetodielectric detection of magnetic quadrupole order in Ba(TiO)Cu4_4(PO4_4)4_4 with Cu4_4O12_{12} square cupolas

In vortex-like spin arrangements, multiple spins can combine into emergent multipole moments. Such multipole moments have broken space-inversion and time-reversal symmetries, and can therefore exhibit linear magnetoelectric (ME) activity. Three types of such multipole moments are known: toroidal, monopole, and quadrupole moments. So far, however, the ME-activity of these multipole moments has only been established experimentally for the toroidal moment. Here, we propose a magnetic square cupola cluster, in which four corner-sharing square-coordinated metal-ligand fragments form a noncoplanar buckled structure, as a promising structural unit that carries an ME-active multipole moment. We substantiate this idea by observing clear magnetodielectric signals associated with an antiferroic ME-active magnetic quadrupole order in the real material Ba(TiO)Cu$_4$(PO$_4$)$_4$. The present result serves as a useful guide for exploring and designing new ME-active materials based on vortex-like spin arrangements.Comment: 4 figure

Effects of substituents in polyvinylcarbazole structures on their optical properties

Absorption, photoluminescence, and photoluminescence excitation spectra of solutions and thin films of N-vinylcarbazole polymers and copolymers with various substituents directly on the carbazole moiety and on the polymer chain were studied comprehensively. Polymers that were used previously to develop polymer composites with polymethine dyes having photosensitivity over a broad spectral range including the visible and near-IR regions were selected for the studies

2 Novel deletions of the sterol 27-hydroxylase gene in a Chinese Family with Cerebrotendinous Xanthomatosis

<p>Abstract</p> <p>Background</p> <p>Cerebrotendinous xanthomatosis (CTX) is a rare lipid-storage disease. We investigated the clinic manifestation, histopathology and sterol 27-hydroxylase gene (CYP27A1) in a Chinese family with Cerebrotendinous Xanthomatosis (CTX).</p> <p>Case Presentation</p> <p>A 36-year-old female with typical CTX clinical manifestation had Spindle-shaped lipid crystal clefts in xanthomas and "onion-like demyelination" in sural nerve. The patient was compound heterozygote carrying two deletions in exon 1 (c.73delG) and exon 2 (c.369_375delGTACCCA). The family memebers were carriers.</p> <p>Conclusions</p> <p>A Chinese family with Cerebrotendinous Xanthomatosis had typical clinical manifestation. CYP27A1 mutations were found in the proband and all other family members.</p

Signatures of the excitonic memory effects in four-wave mixing processes in cavity polaritons

We report the signatures of the exciton correlation effects with finite memory time in frequency domain degenerate four-wave mixing (DFWM) in semiconductor microcavity. By utilizing the polarization selection rules, we discriminate instantaneous, mean field interactions between excitons with the same spins, long-living correlation due to the formation of biexciton state by excitons with opposite spins, and short-memory correlation effects in the continuum of unbound two-exciton states. The DFWM spectra give us the relative contributions of these effects and the upper limit for the time of the exciton-exciton correlation in the unbound two-exciton continuum. The obtained results reveal the basis of the cavity polariton scattering model for the DFWM processes in high-Q GaAs microcavity.Comment: 11 pages, 1 figur

Electron-phonon renormalization of the absorption edge of the cuprous halides

Compared to most tetrahedral semiconductors, the temperature dependence of the absorption edges of the cuprous halides (CuCl, CuBr, CuI) is very small. CuCl and CuBr show a small increase of the gap $E_0$ with increasing temperature, with a change in the slope of $E_0$ vs. $T$ at around 150 K: above this temperature, the variation of $E_0$ with $T$ becomes even smaller. This unusual behavior has been clarified for CuCl by measurements of the low temperature gap vs. the isotopic masses of both constituents, yielding an anomalous negative shift with increasing copper mass. Here we report the isotope effects of Cu and Br on the gap of CuBr, and that of Cu on the gap of CuI. The measured isotope effects allow us to understand the corresponding temperature dependences, which we also report, to our knowledge for the first time, in the case of CuI. These results enable us to develop a more quantitative understanding of the phenomena mentioned for the three halides, and to interpret other anomalies reported for the temperature dependence of the absorption gap in copper and silver chalcogenides; similarities to the behavior observed for the copper chalcopyrites are also pointed out.Comment: 14 pages, 5 figures, submitted to Phys. Rev.