Materials with the pyrochlore/fluorite structure have diverse technological applications, from magnetism to nuclear waste disposal. Here we report the observation of structural instability present in ...the pyrochlores A
Zr
O
O' (A = Pr, La) and Yb
Ti
O
O', that exists despite ideal stoichiometry, ideal cation-ordering, the absence of lone pair effects, and a lack of magnetic order. Though these materials appear to have good long-range order, local structure probes find displacements, of the order of 0.01 nm, within the pyrochlore framework. The pattern of displacements of the A
O' sublattice mimics the entropically-driven fluxional motions characteristic of and well-known in the silica mineral β-cristobalite. The universality of such displacements within the pyrochlore structure adds to the known structural diversity and explains the extreme sensitivity to composition found in quantum spin ices and the lack of ferroelectric behavior in pyrochlores.
We report single-crystal V51 NMR studies on volborthite Cu3V2O7(OH)2·2H2O, which is regarded as a quasi-two-dimensional frustrated magnet with competing ferromagnetic and antiferromagnetic ...interactions. In the 1/3 magnetization plateau above 28 T, the nuclear spin-lattice relaxation rate 1/T1 indicates an excitation gap with a large effective g factor in the range of 4.6–5.9, pointing to magnon bound states. Below 26 T where the gap has closed, the NMR spectra indicate small internal fields with a Gaussian-like distribution, whereas 1/T1 shows a power-law-like temperature dependence in the paramagnetic state, which resembles a slowing down of spin fluctuations associated with magnetic order. We discuss the possibility of an exotic spin state caused by the condensation of magnon bound states below the magnetization plateau.
Giant negative thermal expansion is achieved in antiperovskite manganese nitrides when the sharp volume change associated with magnetic ordering is broadened by substitution. In this Letter, we ...address the unique role of the ''magic" element, Ge, for such broadening in Mn3Cu1-xGexN. We present evidence for a local lattice distortion well described by the low-temperature tetragonal (T4) structure of Mn3GeN for a range of x, where the overall structure remains cubic. This structural instability shows a strong correlation with the broadness of the growth of the ordered magnetic moment and, hence, is considered to trigger the broadening of the volume change.
Summary Objective Hypertrophy-like changes are often observed in chondrocytes during the development of osteoarthritis (OA). These changes play a crucial part in the OA-associated cartilage ...degradation and osteophyte formation. However, the pathogenesis leading to such changes is still unknown. In this study, we investigated the mechanism by which these hypertrophy-like changes are induced from the viewpoint of impaired glycolytic metabolism. Methods The effect of sodium fluoride (NaF) on glycolytic metabolism of cultured chondrocytes was confirmed by measurement of intracellular adenosine triphosphate (ATP) production. Translocation of phosphorylated Smad1/5/8 to the nucleus was evaluated by subcellular fractionation and Western blotting. Chondrocyte hypertrophy-like changes were investigated by real-time RT-PCR and Western blot analysis of differentiation markers. Results ATP production was dose-dependently decreased by NaF in the human chondrocytic cell line HCS-2/8. In addition, both chondrocyte proliferation and differentiation were inhibited, whereas cell death was promoted by treatment with NaF. Interestingly, combinational treatment with NaF and lactate enhanced translocation of phospho-Smad1/5/8 to the nucleus, as well as gene expression of ALP , VEGF , COL10a1 , and matrix metalloproteinase13 ( MMP13 ), which were the markers of late mature and hypertrophic chondrocytes. Furthermore, the production of type X collagen and activation of MMP9 were also promoted under the same conditions. Conclusions These findings suggest that decreased ATP production by NaF promotes hypertrophy-like changes via activation of phospho-Smad1/5/8 in the presence of lactate. Novel metabolic aspects of OA pathogenesis are indicated herein.
Summary Objective CCN family protein 2/connective tissue growth factor (CCN2/CTGF) promotes cartilage regeneration in experimental osteoarthritis (OA) models. However, CCN2 production is very low in ...articular cartilage. The aim of this study was to investigate whether or not CCN2 was promoted by cultured chondrocytes treated with low-intensity pulsed ultrasound (LIPUS) and to clarify its mechanism. Methods Human chondrocytic cell line HCS-2/8, rat primary epiphyseal and articular cartilage cells, and Ccn2 -deficient chondrocytes that impaired chondrocyte differentiation, were treated with LIPUS for 20 min at 3.0 MHz frequency and 60 mW/cm2 power. Expressions of chondrocyte differentiation marker mRNAs were examined by real-time PCR analysis from HCS-2/8 cells and Ccn2 -deficient chondrocytes at 30 min and 1 h after LIPUS treatment, respectively. CCN2 production was examined by Western blotting after 5 h of LIPUS treatment. Moreover, Ca2+ influx was measured by using a Fluo-4 probe. Results The gene expression of chondrocyte differentiation markers and CCN2 production were increased in cultured chondrocytes treated with LIPUS. In addition, Ca2+ influx and phosphorylation of p38 MAPK and ERK1/2 were increased by LIPUS treatment, and the stability of TRPV4 and BK ca channel mRNAs was decreased by siRNA against CCN2. Consistent with those findings, the LIPUS-induced the gene expressions of type II collagen and Aggrecan observed in wild-type cells were not observed in the Ccn2 -deficient chondrocytes. Conclusion These data indicate that chondrocyte differentiation represented by CCN2 production was mediated via MAPK pathways activated by LIPUS-stimulated Ca2+ influx, which in turn was supported by the induced CCN2 molecules in articular chondrocytes.
Abstract
Reinforced concrete structures in a salt-damaged environment are deteriorated by salt damage due to the influence of salt. As a repair measure, repair materials with salt adsorption ...performance and rebar rust prevention performance are used for inorganic materials. However, products with these added to organic materials are used for various purposes, which are used for various applications as repair materials. Unfortunately, there are few examples of its use becoming possible expected that measures against salt damage will be taken in various applications which have developed a “salt-adsorbing epoxy resin repair material” in which a salt-adsorbing agent is added to epoxy resin, which is an organic material. In addition, this research presented the salt adsorption effect and the corrosion inhibition effect on steel bars applied to each repair application.
Aerosols in the troposphere influence photolysis frequencies and hence the concentrations of chemical species. We used a three-dimensional regional chemical transport model (NAQPMS) coupled with an ...accurate radiative transfer model to examine the impacts of aerosols on summertime photochemistry in Central Eastern China (CEC)
via changing photolysis frequencies. In addition to looking at changes in concentrations as previous studies have done, we examined the changes in ozone (O
3) budgets and the uncertainties related to our estimations. The 1st–12th June 2006 was selected as the simulation period when high aerosol optical depth at 550
nm (AOD550) and O
3 were found. A comparison of measurements showed that the model was capable of reproducing the spatial and temporal variations in photolysis frequencies, ultraviolet (UV) radiation, AOD550, cloud optical depth, O
3 and other chemical constitutes in CEC. Aerosols have important impacts on atmospheric oxidation capacity in CEC. On a regional scale, aerosols decreased the average O
3→O (
1D) photolysis frequency by 53%, 37% and 21% in the lower, middle and upper troposphere in CEC. The uncertainties of these estimations were 37%, 25% and 14%, respectively. Mean OH concentrations decreased by 51%, 40% and 24% in layers below 1
km, 1–3
km and 3–10
km, with uncertainties of 39%, 28% and 9%, respectively. The changes in HO
2 concentrations were smaller but significant. In contrast, NO
x showed a significant increase at 0–1
km and 1–3
km in CEC, with magnitudes of 6% and 8%. The largest relative enhancement occurred in downwind regions below 1
km. Summertime boundary layer O
3 (below 1
km and 1–3
km) was reduced by 5% with a maximum of 9% in highly polluted regions. The reduced ozone production (P (O
3)) was responsible for this reduction below 3
km.
► A 3D chemical transport model was coupled with an accurate radiative transfer model. ► The siginificant impacts of aerosols on summertime photochemistry in Central China. ► Summertime boundary layer ozone reduced by 5% in polluted regions.
We have synthesized high-quality single crystals of volborthite, a seemingly distorted kagome antiferromagnet, and carried out high-field magnetization measurements up to 74 T and ^{51}V NMR ...measurements up to 30 T. An extremely wide 1/3 magnetization plateau appears above 28 T and continues over 74 T at 1.4 K, which has not been observed in previous studies using polycrystalline samples. NMR spectra reveal an incommensurate order (most likely a spin-density wave order) below 22 T and a simple spin structure in the plateau phase. Moreover, a novel intermediate phase is found between 23 and 26 T, where the magnetization varies linearly with magnetic field and the NMR spectra indicate an inhomogeneous distribution of the internal magnetic field. This sequence of phases in volborthite bears a striking similarity to those of frustrated spin chains with a ferromagnetic nearest-neighbor coupling J_{1} competing with an antiferromagnetic next-nearest-neighbor coupling J_{2}.
Number concentrations, size distributions, and mixing states of aerosols are essential parameters for accurate estimations of aerosol direct and indirect effects. In this study, we develop an aerosol ...module, designated the Aerosol Two-dimensional bin module for foRmation and Aging Simulation (ATRAS), that can explicitly represent these parameters by considering new particle formation (NPF), black carbon (BC) aging, and secondary organic aerosol (SOA) processes. A two-dimensional bin representation is used for particles with dry diameters from 40 nm to 10 μm to resolve both aerosol sizes (12 bins) and BC mixing states (10 bins) for a total of 120 bins. The particles with diameters between 1 and 40 nm are resolved using additional eight size bins to calculate NPF. The ATRAS module is implemented in the WRF-Chem model and applied to examine the sensitivity of simulated mass, number, size distributions, and optical and radiative parameters of aerosols to NPF, BC aging, and SOA processes over East Asia during the spring of 2009. The BC absorption enhancement by coating materials is about 50% over East Asia during the spring, and the contribution of SOA processes to the absorption enhancement is estimated to be 10–20% over northern East Asia and 20–35% over southern East Asia. A clear north–south contrast is also found between the impacts of NPF and SOA processes on cloud condensation nuclei (CCN) concentrations: NPF increases CCN concentrations at higher supersaturations (smaller particles) over northern East Asia, whereas SOA increases CCN concentrations at lower supersaturations (larger particles) over southern East Asia. The application of ATRAS in East Asia also shows that the impact of each process on each optical and radiative parameter depends strongly on the process and the parameter in question. The module can be used in the future as a benchmark model to evaluate the accuracy of simpler aerosol models and examine interactions between NPF, BC aging, and SOA processes under different meteorological conditions and emissions.
We report a (51)V-NMR study on a high-quality powder sample of volborthite Cu3V2O7(OH)2 . 2H2O, a spin-1/2 Heisenberg antiferromagnet on a distorted kagome lattice formed by isosceles triangles. In ...the magnetic fields below 4.5 T, a sharp peak in the nuclear spin-lattice relaxation rate 1/T(1) accompanied with line broadening revealed a magnetic transition near 1 K. The low temperature phase shows anomalies such as a Lorentzian line shape, a 1/T(1) proportional, variantT behavior indicating dense low-energy excitations, and a large spin-echo decay rate 1/T(2) pointing to unusually slow fluctuations. Another magnetic phase appears above 4.5 T with less anomalous spectral shape and dynamics.
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