Analysis of Th, U, Pu, and Am in radioactive metal waste using extraction chromatography

In order to analyze actinide elements in radioactive metal waste, the dissolution and chemical separation conditions were optimized. The surfaces of a type 304 stainless steel plate and of pipe waste sampled from the prototype advanced thermal reactor (Fugen) were dissolved in mixed acid solution (HNO₃:HCl:H₂O = 1:1:4). The resulting solution was evaporated to dryness and dissolved with 2 mol/dm³ of HNO₃ to prepare sample solutions. In order to analyze trivalent actinide elements in the sample solution containing a large amount of Fe(III) (>0.1 g) using TRU resin, the effect of Fe(III) concentration on the recovery of Am(III) and reduction effect of Fe(III) to Fe(II) with ascorbic acid were studied. On the basis of results of this study, chemical separation scheme was constructed and Pu and Am in the sample solutions were separated. Thorium and U in the sample solutions were separated with UTEVA resin. High recoveries for all experimented elements were obtained from the analysis of spiked sample solutions, the effectiveness of the method was confirmed.     

Direct C-H arylation of (hetero)arenes with aryl iodides via rhodium catalysis

A new method for the catalytic C-H arylation of heteroarenes and arenes that manifests high activity paired with reasonably broad scope was developed. Under the catalytic influence of RhCl(CO){P[OCH(CF3)2]3}2 and Ag2CO3, the direct C-H arylation of heteroarenes/arenes with aryl/heteroaryl iodides took place to afford a range of biaryls in good to excellent yields with high regioselectivity. Thiophenes, furans, pyrroles, indoles, and alkoxybenzenes are applicable in this arylation protocol.     

Enrichment of surfactant from its aqueous solution using ultrasonic atomization

Dilute aqueous solutions of dodecyl-benzenesulfonic acid sodium salt (DBS-Na) and polyoxyethylenenonylphenyl ethers (PONPEs) were ultrasonically atomized. The surfactants were concentrated in collected mist droplets. The enrichment ratio increased with decreasing surfactant concentration. Depending on the surfactant’s molecular weight and affinity to water, different enrichment ratio was observed in the range of low feed concentrations. For anionic surfactant, DBS-Na, the enrichment ratio was significantly improved by KCl addition and a peak appeared on the plot of the ratio against KCl concentration. Addition of NaCl or CaCl₂ · 2H₂O to the surfactant solution also enhanced the enrichment ratio; however, the effect was relatively small. Such behaviors of the ratio were interpreted as enhanced interfacial adsorption of the surfactant and a lack of supply of surfactant monomers from liquid bulk because of slow breaking of surfactant micelles. Time required for collecting an amount of mist was also observed. Among the three salt systems, the time for KCl system was twice as long as others. This fact suggested that the formation of smaller droplets in KCl system.     

Classical phase space revealed by coherent light

We study the far-field characteristics of oval-resonator laser diodes made of an GaAs/Al(x)Ga(1-x)As quantum well. The resonator shapes are various oval geometries, thereby probing chaotic and mixed classical dynamics. The far-field pattern shows a pronounced fine structure that strongly depends on the cavity shape. Comparing the experimental data with ray-model simulations for a Fresnel billiard yields convincing agreement for all geometries and reveals the importance of the underlying classical phase space for the lasing characteristics.     

Copper-mediated C-H bond arylation of arenes with arylboronic acids

A new copper-mediated cross-coupling of arenes and arylboronic acids is described. Under the influence of Cu(OCOCF 3) 2, the C-H bond arylation of electron-rich arenes with arylboronic acids takes place to afford a range of biaryls in good yields. The reaction is selective for cross-coupling; no homocoupling product arising from arenes or arylboronic acids is detected. Multiple C-H bond arylation is possible with indoles and pyrroles furnishing interesting extended pi-systems.     

An effective method to use ionic liquids as reaction media for asymmetric reduction by Geotrichum candidum

An effective method was developed to use an enzyme in ionic liquids; the asymmetric reduction of ketones by Geotrichum candidum in ionic liquids proceeded smoothly with excellent enantioselectivity when the cell was immobilized on water-absorbing polymer containing water, while the reaction without the polymer did not proceed.     

Effects of the molecular properties of mixed solvents on the elution of alkyl benzoates in RPLC.

The retention behavior and mechanism of methyl, ethyl, propyl, isopropyl, buthyl and isobuthyl benzoates have been studied at different eluent compositions of aqueous mixtures with water-soluble organic solvents (methanol, ethanol, 1-propanol, 2-propanol, acetonitrile (AN), 1,4-dioxane and tetrahydrofuran (THF)) in RPLC. The retention of the solutes is discussed based on the solvent composition, solvent polarity (ETN value), preferential solvation, hydrogen bonding and solvent clusters of the eluents. The smaller ETN values and the larger preferential solvation of the mixed solvent eluted the solutes faster. The IR spectra of HDO suggested that the solvents, except for methanol and ethanol, break the hydrogen bonding between water molecules, resulting in fast elution of the solutes. Based upon the results, we chose an optimum solvent composition for the separation of benzoates and applied it to the determination of the benzoates in clove.     

On‐line Liquid‐liquid Extraction Coupled to a Reversed Micellar‐mediated Chemiluminescence Detection System: Application to the Determination of Amino/Nitroaromatic Compounds

A simple and fast flow method for the trace level determination of p‐toluidine, 2‐methyl‐5‐nitroaniline, and 2,4‐dinitroaniline in aqueous samples is reported. These amino/nitroaromatics are related to trinitrotoluene (TNT) and appear during the degradation process of the explosive. The chemical principles of ion‐pair formation and liquid‐liquid extraction are applied: In aqueous acidic medium, the protonated analyte [HA]⁺ makes an ion‐pair with the tetrachloroaurate(III) ion, followed by on‐line ion‐pair extraction into the dichloromethane carrier used. After membrane separation, the CH₂Cl₂ containing the ion‐pair, [HA]⁺[AuCl₄]⁻, is mixed with the reversed micellar luminescent reagent of luminol (in 0.3 M Na₂CO₃) prepared from cetyl‐trimethylammonium chloride in CH₂Cl₂‐cyclohexane and the [AuCl₄⁻‐luminol chemiluminescence (CL) output is recorded. The detection limits (S/N> 3) are: p‐toluidine, 1.0 × 10⁻⁴M; 2‐methyl‐5‐nitroaniline, 1.0 × 10⁻⁷ M; 2,4‐dinitroaniline, 1.0 × 10⁻⁷ M, while the calibration curves are linear between 1.0 × 10⁻⁴ — 1.0 × 10⁻² M for all the compounds. Although spectral studies indicated the formation and extraction of a very small amount of the ion‐pair species, the reversed micellar‐mediated CL detection system provides an alternative procedure for the determination of degradation products of the explosive TNT in environmental aqueous samples.     

Spontaneous Formation of Microgroove Arrays on the Surface of p‐Type Porous Silicon Induced by a Turing Instability in Electrochemical Dissolution

Self‐organization plays an imperative role in recent materials science. Highly tunable, periodic structures based on dynamic self‐organization at micrometer scales have proven difficult to design, but are desired for the further development of micropatterning. In the present study, we report a microgroove array that spontaneously forms on a p‐type silicon surface during its electrodissolution. Our detailed experimental results suggest that the instability can be classified as Turing instability. The characteristic scale of the Turing‐type pattern is small compared to self‐organized patterns caused by the Turing instabilities reported so far. The mechanism for the miniaturization of self‐organized patterns is strongly related to the semiconducting property of silicon electrodes as well as the dynamics of their surface chemistry.