Resistance properties of a macroporous silica-based N,N,N′,N′-tetraoctyl-3-oxapentane-1,5-diamide-impregnated polymeric adsorption material against nitric acid, temperature and γ-irradiation

The resistance of a novel silica-based N,N,N′,N′-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) polymeric adsorption material (TODGA/SiO₂-P) against nitric acid, temperature and γ-irradiation had been investigated. The adsorption property of the treated TODGA/SiO₂-P was evaluated by a 3 M HNO₃ solution containing 0.01 M Nd(III). It was found that both 3 and 0.01 M HNO₃ concentrations did not decrease the stability of TODGA/SiO₂-P at 25°C. The quantity of TODGA leaked from TODGA/SiO₂-P was equivalent to its solubility in the corresponding HNO₃ aqueous solution. The effect of 3 M HNO₃ on the leakage of TODGA at 80°C was significantly higher than that in 0.01 M HNO₃ as well as in all cases at 25°C. The amount of Nd(III) adsorbed towards the treated TODGA/SiO₂-P was determined in the range of 0.143–0.148 mmol/g for the HNO₃ concentration effect and 0.142–0.0506 mmol/g for the temperature effect. γ-Irradiation showed a more noticeable destruction effect on TODGA/SiO₂-P. The content of TODGA leaked increased with an increase in the γ-irradiation dose (ID) from 1.06 to 3.72 MGy in terms of the linear equation [TODGA]=794.5ID+84.0. The amount of Nd(III) adsorbed onto the irradiated TODGA/SiO₂-P decreased rapidly from 0.134 to 0.0438 mmol/g, which was lower than 0.153 mmol/g, the adsorption of fresh TODGA/SiO₂-P for Nd(III), according to the equation Q_Nd(III)=−0.0301ID+0.160, showing that a large quantity of TODGA leaked from TODGA/SiO₂-P. The adsorbed amount of Nd(III) decreased obviously in this order: the HNO₃ concentration effect, temperature effect and γ-irradiation.     

Extraction Equilibria between Benzene and Water of Uni- and Bivalent Metal Picrates with Lariat 16-Crown-5: Effect of the Side Arms on the Extraction Ability and Selectivity

The overall extraction constants (K_ex) of uni- andbivalent metal picrates with 15-(2,5-dioxahexyl)-15-methyl-16-crown-5(L16C5) were determined between benzene and water at 25°C. TheK_ex values were analyzed into the constituent equilibriumconstants, i.e., the extraction constant of picric acid, the distributionconstant of the crown ether, the stability constant of the metalion–crown ether complex in water, and the ion-pair extraction constantof the complex cation with the picrate anion. The K_ex valuedecreases in the orders Ag⁺ > Na⁺ >Tl⁺ > K⁺ > Li⁺ andPb²⁺ > Ba²⁺ > Sr²⁺ for theuni- and bivalent metals, respectively, which are the same as those observedfor 16C5. The extraction selectivity was found to be governed by theselectivity of the ion-pair extraction of the L16C5–metal picratecomplex rather than by that of the complex formation in water. Theextraction ability of L16C5 is smaller for all the metals than that of 16C5,which is mostly attributed to the higher lipophilicity of L16C5. Differencesin the extraction selectivity between L16C5 and 16C5 were observed for thebivalent metals but little for the univalent metals. The side-arm effect onthe extraction selectivity was interpreted on the basis of the negativecorrelation between the effect on the complex stability constant in waterand that on the ion-pair extraction constant.     

Polymer‐Assisted Solution‐Phase Synthesis and Neurite‐Outgrowth‐Promoting Activity of 15‐Deoxy‐Δ12,14‐PGJ2 Derivatives

An efficient solution‐phase synthesis of rac‐15‐deoxy‐Δ^12,14‐PGJ₂ (15dPGJ₂) derivatives that contain variable α and ω chains based on a polymer‐assisted strategy and their neurite‐outgrowth‐promoting activity are described. The strategy for the synthesis of PGJ₂ derivatives involves the use of a vinyl iodide bearing cyclopentenone as a key intermediate, which undergoes Suzuki–Miyaura coupling and subsequent Lewis acid catalyzed aldol condensation for incorporation of the ω and α chains, respectively. For easy access to the PGJ₂ derivatives, a polymer‐supported catalyst and scavengers were adapted for use in these four diverse steps, in which workup and purification can be performed by simple filtration of the solid‐supported reagents. By using this methodology, we succeeded in the synthesis of 16 PGJ₂ derivatives with four alkyl boranes and four aldehydes. The neurite‐outgrowth‐promoting activity of the 16 synthetic compounds in PC12 cells revealed that the side‐chains play a major role in modulating their biological activity. The carboxylic acid on the α chain improved the biological activity, although it was not absolutely required. Furthermore, a PGJ₂ derivative with a phenyl moiety on the ω chain was found to exhibit an activity comparable to that of natural 15dPGJ₂.     

Large volume preconcentration and purification for determining the240Pu/<Superscript>239</Superscript>Pu isotopic ratio and <Superscript>238</Superscript>Pu/<Superscript>239+240</Superscript>Pu alpha-activity ratio in seawater

Summary The present paper describes a new analytical method for determining the ²⁴⁰Pu/²³⁹Pu isotopic ratio and ²³⁸Pu/^239+240Pu α -activity ratio in seawater, both of which are important parameters for determining Pu sources in the ocean. Plutonium isotopes were preconcentrated from a large volume of seawater (4700-10800 liter) by solid phase extraction using MnO₂-impregnated fibers and eluted into 3M HCl. After the elution, the Pu species of all oxidation states were converted to Pu(IV) using NaNO₂, purified by solvent extraction using thenoyltrifluoroacetone (TTA)-benzene, and concentrated in 5 ml of 0.2M HNO₂. The ²⁴⁰Pu/²³⁹Pu and ²³⁸Pu/^239+240Pu ratios in the 5-ml final solution were determined by inductively coupled plasma-mass spectrometry (ICP-MS) and α-spectrometry, respectively. A pg level of Pu, which was a sufficiently large amount for the determination, was obtained by the solid phase extraction. Through the redox conversion and solvent extraction, the Pu species, such as Pu(III), Pu(IV) and Pu(VI), were collected at a high recovery of 96±2% (n=3) despite the presence of large amounts of Mn, and interfering ²³⁸U (3.3 μg^. l^-1in seawater) was effectively removed with a decontamination factor of 1.7·10⁷. The accuracy of the method for the ²⁴⁰Pu/²³⁹Pu ratio was verified using reference materials of seawater and a terrestrial soil sample. The present technique was applied to the determination of the ²⁴⁰Pu/²³⁹Pu and ²³⁸Pu/^239+240Pu ratios in coastal and oceanic water.     

PULSE RADIOLYSIS STUDIES IN MODEL LIPID SYSTEMS: FORMATION AND BEHAVIOR OF PEROXY RADICALS IN FATTY ACIDS

Abstract— Radiolytic formation and peroxidation of fatty acid radicals have been investigated by pulse radiolysis techniques in oleate, linoleate, linolenate and arachidonate systems. A strong absorption band at 280 nm associated with conjugated radicals, R_conj, formed in polyunsaturated fatty acid moieties has been used as a probe for kinetic processes occurring at doubly allylic sites in the hydrocarbon chain. Formation of R_conj by O^- has been found to be more efficient than the less selective OH radical. Peroxidation of R_conj is shown to be somewhat slower, ( k _R+ O₂˜ 3 × 10⁸ M ^-1 s^-1), than O₂ reactions with radicals in oleate ( k _R+ O₂= 1 × 10⁹ M ^-1 s^-1). Peroxy radicals generated in these reactions disappear slowly by essentially second order processes (2 k RO₁˜ 10⁷ M ^-1 s^-1). The superoxide radical, O^-₂, shows little if any reactivity towards 0.01 M linolenate or arachidonate over periods of 20 s.     

Difference in spin crossover pathways among saddle-shaped six-coordinated iron(III) porphyrin complexes

The electronic states of a series of saddle-shaped porphyrin complexes [Fe(OMTPP)L(2)](+) and [Fe(TBTXP)L(2)](+) have been examined in solution by (1)H NMR, (13)C NMR, and EPR spectroscopy and by magnetic measurements. While [Fe(OMTPP)(DMAP)(2)](+) and [Fe(TBTXP)(DMAP)(2)](+) maintain the low-spin (S = (1)/(2)) state, [Fe(OMTPP)(THF)(2)](+) and [Fe(TBTXP)(THF)(2)](+) exhibit an essentially pure intermediate-spin (S = (3)/(2)) state over a wide range of temperatures. In contrast, the Py and 4-CNPy complexes of OMTPP and TBTXP exhibit a spin transition from S = (3)/(2) to S = (1)/(2) as the temperature was decreased from 300 to 200 K. Thus, the magnetic behavior of these complexes is similar to that of [Fe(OETPP)Py(2)](+) reported in our previous paper (Ikeue, T.; Ohgo, Y.; Yamaguchi, T.; Takahashi, M.; Takeda, M.; Nakamura, M. Angew. Chem., Int. Ed. 2001, 40, 2617-2620) in the context that all these complexes exhibit a novel spin crossover phenomenon in solution. Close examination of the NMR and EPR data of [Fe(OMTPP)L(2)](+) and [Fe(TBTXP)L(2)](+) (L = Py, 4-CNPy) revealed, however, that these complexes adopt the less common (d(xz), d(yz))(4)(d(xy))(1) electron configuration at low temperature in contrast to [Fe(OETPP)Py(2)](+) which shows the common (d(xy))(2)(d(xz), d(yz))(3) electron configuration. These observations have been attributed to the flexible nature of the OMTPP and TBTXP cores as compared with that of OETPP; the relatively flexible OMTPP and TBTXP cores can ruffle the porphyrin ring and adopt the (d(xz), d(yz))(4)(d(xy))(1) electron configuration at low temperature. Therefore, this study reveals that the rigidity of porphyrin cores is an important factor in determining the spin crossover pathways.     

Basic peptides as functional components of non-viral gene transfer vehicles

Improving the performance of non-viral gene-delivery vehicles that consist of synthetic compounds and nucleic acids is a key to successful gene therapy. Supplementing synthetic vehicles with various biological functions by using natural or artificial peptides is a promising approach with which to achieve this goal. One of the obstacles hindering this effort is that some of the potentially useful peptides, especially those with many basic amino acid residues, interfere with the formation of the complex owing to strong electrostatic interactions with the nucleic acid. In this review, we describe our recent work in examining the potential of these peptides in gene delivery, using a recombinant lambda phage particle as the model for the gene-delivery complex. Lambda phage encapsulates large duplex DNA in a rigid polyplex-like shell with a diameter of 55 nm, and can display various peptides on this capsid, independently of particle formation. By examining the expression of marker genes encapsulated in the phage capsid, we have demonstrated that the protein transduction domain of HIV Tat protein and the nuclear localization signal derived from SV40 T antigen can remarkably facilitate the delivery of these marker genes across the two major barriers, the cell membrane and the nuclear membrane, respectively. Our results indicate that these basic peptides can constitute effective components of synthetic gene-transfer complexes, as long as sufficient copies are displayed on the outer surface of the complex.     

Reversible electro-optical switching of a memory type PDLC using two-frequency-addressing liquid crystals

Abstract

A memory type PDLC has been prepared by sandwiching a mixture of two-frequency-addressing liquid crystals and acrylate monomers with a hydoroxy group between two glass substrates with ITO electrodes followed by UV irradiation. This PDLC can be electrically switched between a transparent state and a light scattering state, which are maintained over several months without electric fields.     

Non‐contact evaluation of the electrical conductivity of thin metallic films by eddy current microscopy

An eddy current microscopy technique to evaluate the electrical conductivity of thin metallic films in a non‐contact manner is reported. A narrow track formed in an approximately 100 nm thick Au film was prepared, and a Co–Cr coated magnetic tip was driven to oscillate above the track both with and without current passing through the track. Despite the absence of current, the electromagnetic interaction between the tip and the stray magnetic field from the track gave rise to a phase delay in the probe. This was due to an eddy current being induced within part of the track. Moreover, measurements of the phase change in the probe oscillation for different metallic films with thicknesses of about 100 nm found this to be proportional to the electrical conductivity of the film. Finally, the electrical conductivity of an Al film was evaluated using the eddy current microscopy technique. Copyright © 2012 John Wiley & Sons, Ltd.     

Hybrid EuIII Coordination Luminophore Standing on Two Legs on Silica Nanoparticles for Enhanced Luminescence

In this study, we have demonstrated a two-legged, upright molecular design method for monochromatic and bright red luminescent Ln^III-silica nanomaterials. A novel Eu^III-silica hybrid nanoparticle was developed by using a doubly binding TPPO−Si(OEt)₃ (TPPO: triphenyl phosphine oxide) linker. The TPPO−Si(OEt)₃ was confirmed by ¹H, ³¹P, ²⁹Si NMR spectroscopy and single-crystal X-ray analysis. Luminescent Eu(hfa)₃ and Eu(tfc)₃ moieties (hfa: hexafluoroacetylacetonate, tfc: 3-(trifluoromethylhydroxymethylene)camphorate) were fixed onto TPPO−Si(OEt)₃-modified silica nanoparticles, producing Eu(hfa)₃(TPPO−Si)₂-SiO₂ and Eu(tfc)₃(TPPO−Si)₂-SiO₂, respectively. Eu(hfa)₃(TPPO−Si)₂−SiO₂ exhibited the higher intrinsic luminescence quantum yield (93 %) and longer emission lifetime (0.98 ms), which is much larger than those of previously reported Eu^III-based hybrid materials. Eu(tfc)₃(TPPO−Si)₂−SiO₂ showed an extra-large intrinsic emission quantum yield (54 %), although the emission quantum yield for the precursor Eu(tfc)₃(TPPO−Si(OEt)₃)₂ was found to be 39 %. These results confirmed that the TPPO−Si(OEt)₃ linker is a promising candidate for development of Eu^III-based luminescent materials.