UV resistance of encapsulated low molecular weight aromatic compounds in fluoroalkyl end‐capped trimethoxyvinylsilane oligomer/silica nanocomposites

Sol–gel reactions of fluoroalkyl end‐capped trimethoxyvinylsilane oligomer in the presence of low molecular weight aromatic compounds (ArH) such as 1,1′‐bi(2‐naphthol) (BINOL) and 2‐hydroxy‐4‐methoxy benzophenone (HMB) were found to proceed smoothly under alkaline conditions at room temperature to give the corresponding fluorinated oligomeric silica nanocomposites‐encapsulated aromatic compounds (BINOL and HMB) [R_F‐(VM‐SiO₂)_n‐R_F/ArH nanocomposites]. UV light irradiation (λ_max: 254 nm) toward R_F‐(VM‐SiO₂)_n‐R_F/ArH nanocomposites showed that photodegradation of encapsulated ArH was not observed at all in the fluorinated nanocomposites cores, although the parent ArH can exhibit an effective photodegradation behavior under similar conditions. Especially, encapsulated ArH can exhibit no weight loss corresponding to the contents of the aromatic compounds in the fluorinated nanocomposites even after calcination at 800°C. Therefore, fluoroalkyl end‐capped trimethoxyvinylsilane oligomer has high potential for not only the thermal resistance but also the UV resistance fluorinated polymeric materials. Copyright © 2014 John Wiley & Sons, Ltd.     

Fabrication of L10 FePtAg nanoparticles and a study of the effect of Ag during the annealing process

L1₀ ferromagnetic phase FePt nanoparticles containing Ag atoms (FePtAg) were synthesized by means of a liquid phase process, followed by annealing. The addition of Ag to FePt nanoparticles permits annealing to be conducted at a lower temperature (350 °C). This is further accompanied by a subsequent transformation in the crystal phase from the FCC superparamagnetic phase to the FCT (L1₀) ferromagnetic phase. The effects of annealing temperature and the Ag atoms inside the nanoparticles on the magnetic properties of the FePt nanoparticles have been studied. Using electron spectroscopy for the chemical analysis (ESCA), Ag atoms in the L1₀ phase FePtAg nanoparticles were found to be localized on the surface region of the annealed nanoparticles. The Ag atoms function to inhibit the oxidation of FePt, causing the particles to become more stable and to have ferromagnetic properties.     

One-pot preparation and activation of glycosyl trichloroacetimidates: operationally simple glycosylation induced by combined use of solid-supported, reactivity-opposing reagents

By the combined use of solid-supported reactivity-opposing reagents, that is, basic PTBD and acidic Nafion^®-SAC resins, sequential reactions consisting of glycosyl trichloroacetimidate formation and glycosylation can be effected in a one-pot operation starting from 1-O-unprotected sugars. The solid-supported reagents can be introduced into the reaction vessel either sequentially or, more conveniently, in a `one-shot' manner in comparable yields.     

Neutron diffraction and IR spectroscopy on mechanically alloyed La-substituted PbWO4

Defect structures of the lanthanum-substituted PbWO₄ prepared by mechanical alloying (MA) were investigated by means of powder neutron diffraction and FT-IR, to compare with that of the oxide ion conductive sintered samples. Neutron diffraction revealed that Pb_1−xLa_xWO_4+x/2 prepared by MA possessed the lead site deficiency in the lattice. In addition, it was also found that occupation factors of the lead site were still smaller than the nominal value even for the mechanically alloyed Pb_1−xLa_2x/3WO₄. The vacancy formation at the lead site of the mechanically alloyed Pb_1−xLa_xWO_4+x/2 was also corroborated from the splitting of the absorption band around 800 cm⁻¹ ascribed to the W–O stretching vibration of WO₄ tetrahedron. At the end of this paper, the formation process of the lead site vacancy was discussed in the sintered Pb_1−xLa_xWO_4+x/2 during milling.     

Propagating mode in the photonic gap of 1D resonant Bragg reflector

Concerning “1D resonant photonic crystals”, i.e., 1D periodic arrays of resonant layers with a spacing satisfying the Bragg condition for resonant light, recent topics are summarized together with additional new findings. The central points are about (1) the recent theoretical finding of a new branch in the middle of photonic gap, (2) an approach-dependent controversy about its existence, (3) its consequence as sharp dips in reflectance spectrum and the corresponding internal field patters, indicating its propagating mode character, (4) the comparison between macroscopic and microscopic treatment of resonance effect, and (5) corrected transfer matrix method and its analytical equivalence with nonlocal response theory.     

239Pu, 240Pu, 241Pu, 241Am, 137Cs,and 210Pb in seafloor sediments in the western North Pacific Ocean and the Sea of Japan: distributions,sources and budgets

Journal of Radioanalytical and Nuclear Chemistry - Vertical distributions of 239Pu, 240Pu, 241Pu, 241Am, 137Cs, and 210Pb concentrations, and 240Pu/239Pu ratios were determined in seafloor...     

Generation of anti-trypanosomal agents through concise synthesis and structural diversification of sesquiterpene analogues

To access high-quality small-molecule libraries to screen lead candidates for neglected diseases exemplified by human African trypanosomiasis, we sought to develop a synthetic process that would produce collections of cyclic scaffolds relevant to an assortment of natural products exhibiting desirable biological activities. By extracting the common structural features among several sesquiterpenes, including artemisinin, anthecularin, and transtaganolides, we designed six types of scaffolds with systematic structural variations consisting of three types of stereochemical relationships on the sp(3) ring-junctions and two distinct arrays of tricyclic frameworks. A modular and stereodivergent assembly of dienynes exploiting a versatile manifold produced a series of cyclization precursors. Divergent cyclizations of the dienynes employing tandem ring-closing metathesis reactions overrode variant reactivities of the cyclization precursors, leading to the six canonical sets of the tricyclic scaffolds incorporating a diene group. Screenings of trypanosomal activities of the canonical sets, as well as regio- and stereoisomers of the tricyclic dienes, allowed generation of several anti-trypanosomal agents defining the three-dimensional shape of the pharmacophore. The candidate tricyclic dienes were selected by primary screenings and further subjected to installation of a peroxide bridge, which generated artemisinin analogues that exhibited potent in vitro anti-trypanosomal activities comparable or even superior to those of artemisinin and the approved drugs, suramin and eflornithine.     

Electrodes modified with the phase transition polymer and heme peptide: biocatalysis and biosensing with tunable activity and dynamic range

An electrode was modified with a phase transition polymer, poly(N-isopropylacrylamide), and the polymer was further modified with a peroxidase model compound, heme peptide (HP). As the polymer layer shrank at temperatures above 30-40 degrees C, the catalytic activity of the HP molecules for H(2)O(2) reduction improved, and simultaneously, the number of HP molecules that can communicate electrochemically with the electrode increased. As a result, the catalytic current for H(2)O(2) reduction in the shrunken state was 4 times larger than that in the swollen state. This reversible change was exploited for tuning the sensitivity and dynamic range of the HP electrode in H(2)O(2) biosensing. The dynamic range in inhibition-based biosensing of imidazole derivatives was also tunable.     

The (γ, p0) reactions in the giant dipole resonance region of 51V and 52Cr nuclei

The differential cross sections at 90° for the ⁵¹V(e, p₀)⁵⁰Ti and ⁵²Cr(e, p₀ + p₁)⁵¹V reactions have been measured over the giant dipole resonance region. These cross sections were used to obtain the differential cross sections of the ⁵¹V(γ, p₀)⁵⁰Ti and ⁵²Cr(γ, p₀ + p₁)⁵¹V reactions. The results show two peaks that appear at the same energies as the main peaks of the (γ, n) and (γ, p) cross section for both nuclei. The angular distributions of protons from the (e, p) reaction have also been measured at several points of the incident electron energy. The coefficients A₂ obtained by fitting with a series of Legendre polynomials, W(θ) = 1 + A₁P₁(cos θ)+A₂P₂(cos θ), varies with excitation energy. These results are discussed in terms of the direct-semidirect process considering isospin effects in the giant dipole resonance.     

Self-consistent solutions for single,intense beam polariton with linear polarization

New modes of propagation for a single, intense beam of light have been theoretically studied in the frequency region of giant two photon absorption (GTA) to excitonic molecule (EM) states. Self-consistent solutions for left and right circularly polarized (LCP and RCP respectively) components have been obtained for the polariton dispersion equations which include the ω- and k-dependent self-energy term for exciton due to the GTA process to EM. There are two types of solutions: [I] k(LCP) = k(RCP), [II] k(LCP) ≠ k(RCP). The induced branch for the former has a half of EM mass. There are experimental observations which support the existence of such new propagation modes.