Fluorescence enhancement of oxide fluoride glass co-doped with TbF3 and SmF3

The fluorescence property of xTbF₃-BaF₂-AlF₃-GeO₂+ySmF₃ (x=0.01-40 mol%, y=0-5 wt%) glasses were investigated. The enhancement of Sm³⁺ fluorescence was recognized in the presence of Tb³⁺. Increasing Tb³⁺ content, the emission color changed from green to orange. When the intensity of fluorescence at 540 nm originated from Tb³⁺ is compared with that at 600 nm originated from Sm³⁺, the information about the concentration quenching of Tb³⁺ and Sm³⁺ was obtained. From these results, rare earth ions were dispersed identically in the glasses. After heating to 673 K or cooling to 77 K, the emission color of 20TbF₃-20BaF₂-10AlF₃-50GeO₂/mol%+0.05 wt% SmF₃ glass was reversibly changed from orange to green. In addition, while the emission from 10TbF₃-20BaF₂-10AlF₃-60GeO₂+0.01 wt% SmF₃ glass was green, its crystallized sample, prepared by annealing at 1073 K, exhibited an orange emission due to Sm³⁺ at room temperature.     

Improved complementary polymer pair system: switching for enzyme activity by PEGylated polymers

The development of technology for on/off switching of enzyme activity is expected to expand the applications of enzyme in a wide range of research fields. We have previously developed a complementary polymer pair system (CPPS) that enables the activity of several enzymes to be controlled by a pair of oppositely charged polymers. However, it failed to control the activity of large and unstable α-amylase because the aggregation of the complex between anionic α-amylase and cationic poly(allylamine) (PAA) induced irreversible denaturation of the enzyme. To address this issue, we herein designed and synthesized a cationic copolymer with a poly(ethylene glycol) backbone, poly(N,N-diethylaminoethyl methacrylate)-block-poly(ethylene glycol) (PEAMA-b-PEG). In contrast to PAA, α-amylase and β-galactosidase were inactivated by PEAMA-b-PEG with the formation of soluble complexes. The enzyme/PEAMA-b-PEG complexes were then successfully recovered from the complex by the addition of anionic poly(acrylic acid) (PAAc). Thus, dispersion of the complex by PEG segment in PEAMA-b-PEG clearly plays a crucial role for regulating the activities of these enzymes, suggesting that PEGylated charged polymer is a new candidate for CPPS for large and unstable enzymes.     

Design of Ratiometric Fluorescent Probes Based on Arene–Metal‐Ion Interactions and Their Application to CdII and Hydrogen Sulfide Imaging in Living Cells

Non‐coordinative interactions between a metal ion and the aromatic ring of a fluorophore can act as a versatile sensing mechanism for the detection of metal ions with a large emission change of fluorophores. We report the design of fluorescent probes based on arene–metal‐ion interactions and their biological applications. This study found that various probes having different fluorophores and metal binding units displayed significant emission redshift upon complexation with metal ions, such as Ag^I, Cd^II, Hg^II, and Pb^II. X‐ray crystallography of the complexes confirmed that the metal ions were held in close proximity to the fluorophore to form an arene–metal‐ion interaction. Electronic structure calculations based on TDDFT offered a theoretical basis for the sensing mechanism, thus showing that metal ions electrostatically modulate the energy levels of the molecular orbitals of the fluorophore. A fluorescent probe was successfully applied to the ratiometric detection of the uptake of Cd^II ions and hydrogen sulfide (H₂S) in living cells. These results highlight the utility of interactions between arene groups and metal ions in biological analyses.     

Simultaneous determination of210Bi and210Po on pine needles by solvent extraction and liquid scintillation counting

A determination procedure has been developed for²¹⁰Bi and²¹⁰Po in environmental samples and was applied for pine needles. Bismuth-210 and²¹⁰Po separated from the parent nuclide²¹⁰Pb as BiOCl precipitate were extracted simultaneously by TOPO/toluene containing PPO and POPOP. The separation of²¹⁰Bi and²¹⁰Po from²¹⁰Pb was almost satisfactory. The activity of²¹⁰Bi+²¹⁰Po in the TOPO/toluene was measured periodically by liquid scintillation counting for about 20 days after separation. The time course of the decreasing pattern of the activity was determined by the initial activity ratio²¹⁰Po/²¹⁰Bi. The decreasing pattern of the activity was compared with theoretical patterns, and best estimates for²¹⁰Po and²¹⁰Bi were obtained by non-linear least-squares fitting. The activities of²¹⁰Bi and²¹⁰Po were determined for one-year and two-year old pine needles fro the same pine tree, and weathering half-time and deposition rate of these nuclides was discussed.     

Anti-allergic effect of the flavonoid myricitrin from Myrica rubra leaf extracts in vitro and in vivo

Flavonoids are ingested by the general population as anti-oxidant and anti-inflammatory agents. In this study, we investigated the effects of myricitrin, a flavonoid rich in Myrica rubra leaf, upon anti-inflammatory action. Myrica rubra leaf extracts inhibited pro-inflammatory TNFα production in a macrophage cell line, Raw264.7 cells. We observed that the serum IgE levels in the leaf extract-treated DO11.10, a mouse allergy model, were down-regulated. HPLC was performed to demonstrate that M. rubra leaf extracts contain a large amount of myricitrin. We observed an inhibitory effect of HPLC-purified myricitrin on TNFα production in Raw264.7 cells. Thus, myricitrin may be of potential interest in the management of inflammatory conditions.     

Contraction of supramolecular double-threaded dimer formed by alpha-cyclodextrin with a long alkyl chain

A double-threaded dimer bearing a long substituent part and a large stopper group has been prepared and showed a conformational change with increased solvent polarity. [structure: see text]     

Chemical and Genetic Study of Ligularia cyathiceps in Yunnan Province of China

Root chemicals and evolutionarily neutral DNA regions in L. cyathiceps samples collected in the Zhongdian (Shangrila) County of Yunnan, P. R. China, were examined. Twenty compounds were isolated, including three new ones, 1β,10β‐epoxy‐6β‐(propionyloxy)furanoeremophilan‐9‐one ( 6 ), 1β,10β‐epoxy‐8α‐ethoxyeremophila‐6,11‐diene ( 14 ), and 11αH‐6β‐isobutyryloxy‐1β,10β,7β,8β‐diepoxyeremophilan‐12,8α‐olide ( 15 ). The chemical diversity was found to be limited, with cacalol ( 1 ) and 6‐(acyloxy)furanoeremophilan‐9‐ones ( 4 and/or 5 ) being major components in all the samples. The nuclear ribosomal RNA gene was also found to harbor little variation, although two distinct sequence types were found for the plastid atpB‐rbcL intergenic region.     

Uranium determination by133Xe in meteorites; comparative study with fission track and/or239Np methods and thermal release character of133Xe

Uranium concentrations in three types of inclusions of the Allende (C III), a bulk sample of the Plainview (H5), and a bulk and 5 to 15 density separates of the Huckitta pallasite were determined and discussed by comparing the results from homogenized fission track and/or²³⁹Np analyses with the¹³³Xe results. Stepwise heating experiment revealed that the¹³³Xe release from the Plainview is bimordal and incomplete by a simple heating at 1600 °C, and that the¹³³Xe releases in the Huckitta bulk and metallic samples are multitudinous but can be extracted rather completely at 1600–1700 °C. In the Huckitta, uranium-rich phase (∼100 ppb) was in the lightest density fraction of d=2.9–3.3, but the bulk uranium was found to be mostly from the heavy metal-rich fraction of d>4.2.     

Nature of water transport and electro-osmosis in nafion: insights from first-principles molecular dynamics simulations under an electric field

The effects of water content on water transport and electro-osmosis in a representative polymer electrolyte membrane, Nafion, are investigated in detail by means of first-principles molecular dynamics (MD) simulations in the presence of a homogeneous electric field. We have directly evaluated electro-osmotic drag coefficients (the number of water molecules cotransported with proton conduction) from the trajectories of the first-principles MD simulations and also explicitly evaluated factors that contribute to the electro-osmotic drag coefficients. In agreement with previously reported experiments, our calculations show virtually constant values ( approximately 1) of the electro-osmotic drag coefficients for both low and high water content states. Detailed comparisons of each factor contributing to the drag coefficient reveal that an increase in water content increases the occurrence of the Grotthuss-like effective proton transport process, whose contribution results in a decrease in the electro-osmotic drag coefficient. At the same time, an environment that is favorable for the Grotthuss-like effective proton transport process is also favorable for the transport of water arising from water transport occurring beyond the hydration shell around the protons, whose contribution results in an increase in the electro-osmotic drag coefficient. Conversely, an environment that is not favorable for proton conduction is also not favorable for water transport. As a result, the electro-osmotic drag coefficient shows virtually identical values with respect to change in the water content.