Photochemical primary process of photo-Fries rearrangement reaction of 1-naphthyl acetate as studied by MFE probe

Photo-Fries rearrangement reactions of 1-naphthyl acetate (NA) in n-hexane and in cyclohexane were studied by the magnetic field effect probe (MFE probe) under magnetic fields (B) of 0 to 7 T. Transient absorptions of the 1-naphthoxyl radical, T-T absorption of NA, and a short-lifetime intermediate (τ = 24 ns) were observed by a nanosecond laser flash photolysis technique. In n-hexane, the yield of escaped 1-naphthoxyl radicals dropped dramatically upon application of a 3 mT field, but then the yield increased with increasing B for 3 mT < B≤ 7 T. These observed MFEs can be explained by the hyperfine coupling and the Δg mechanisms through the singlet radical pair. The fact that MFEs were observed for the present photo-Fries rearrangement reaction indicates the presence of a singlet radical pair intermediate with a lifetime as long as several tens of nanoseconds.     

Stereoselective synthesis of the beta-anomer of 4'-thionucleosides based on electrophilic glycosidation to 4-thiofuranoid glycals

Three types of 4-thiofuranoid glycal with different 3,5-O-silyl protecting groups were prepared and their electrophilic glycosidation was investigated. The 3,5-bis-O-(tert-butyldimethylsilyl)-4-thiofuranoid glycal (5) was obtained through mesylation of 2-deoxy-4-thio-D-erythro-pentofuranose (4) and subsequent base-promoted elimination, while thermal elimination of sulfoxide derivatives was suitable for the preparation of 3,5-O-(tetraisopropyldisiloxane-1,3-diyl) (9) and 3,5-O-(di-tert-butylsilylene) (11) 4-thioglycals. The glycosidation reactions of these 4-thioglycals were carried out, in the presence of either PhSeCl or NIS, by using silylated derivatives of uracil, thymine, cytosine, and N(6)-benzoyladenine. Among the three 4-thioglycals, 11 was found to be an excellent glycosyl donor, forming the desired beta-anomer exclusively irrespective of the nucleobase employed.     

A facile structural rearrangement to unprecedented mu 2-eta 6:eta 6-bis(cyclopentadienylidene)ethene diruthenium complexes in the oxidation of 1,2-bis(ruthenocenyl)ethynes

The two-electron oxidation of 1,2-bis(ruthenocenyl)ethynes and bis(1',2',3',4',5'-pentamethylruthenocenyl)ethynes, prepared from alkyne metathesis of the corresponding propynes, gave the unprecedented mu 2-eta 6:eta 6-bis(cyclopentadienylidene)ethene diruthenium complexes.     

Water/supercritical CO2 microemulsions with mixed surfactant systems

Phase behavior was investigated for water/supercritical CO 2 (W/scCO2) microemulsions stabilized with sodium bis(1H,1H,2H,2H-heptadecafluorodecyl)-2-sulfosuccinate (8FS(EO) 2) mixed with various guest surfactants. Only for the mixtures with fluorocarbon-hydrocarbon hybrid anionic surfactants (FC6-HC n), the maximum water-to-surfactant molar ratio (W0(c)) was larger than that estimated from linear interpolation of the W0(c) values for pure 8FS(EO) 2 and pure guest surfactant. Fourier transform infrared (FT-IR) measurement for the microemulsion revealed that the mixing of 8FS(EO) 2 with FC6-HC n can prevent a phase transition from the microemulsion to the liquid crystal even in the presence of excess water. It was also found from the measurement of water/scCO 2 interfacial tension that the area occupied per surfactant molecule was markedly increased by the mixing with FC6-HC n. The loose molecular packing, probably due to a microsegregation of 8FS(EO) 2 and FC6-HC n, is consistent with the enhanced stability of the microemulsion upon surfactant mixing.     

Analysis of variance for high-dimensional time series

Analysis of variance (ANOVA) is tailored for independent observations. Recently, there has been considerable demand for ANOVA of high-dimensional and dependent observations in many fields. For example, it is important to analyze differences among industry averages of financial data. However, ANOVA for these types of observations has been inadequately developed. In this paper, we thus present a study of ANOVA for high-dimensional and dependent observations. Specifically, we present the asymptotics of classical test statistics proposed for independent observations and provide a sufficient condition for them to be asymptotically normal. Numerical examples for simulated and radioactive data are presented as applications of these results.     

Heterogeneous Fenton Degradation of Organic Pollutants in Water Enhanced by Combining Iron-type Layered Double Hydroxide and Sulfate

Water pollution derived from organic pollutants is one of the global environmental problems. The Fenton reaction using Fe²⁺ as a homogeneous catalyst has been known as one of clean methods for oxidative degradation of organic pollutants. Here, a layered double hydroxide (Fe²⁺Al³⁺-LDH) containing Fe²⁺ and Al³⁺ in the structure was used to develop a “heterogeneous” Fenton catalyst capable of mineralizing organic pollutants. We found that sulfate ion (SO₄²⁻) immobilized on the Fe²⁺Al³⁺-LDH significantly facilitated oxidative degradation (mineralization) of phenol as a model compound of water pollutants to carbon dioxide (CO₂) in a heterogeneous Fenton process. The phenol conversion and mineralization efficiency to CO₂ reached >99% and ca. 50%, respectively, even with a reaction time of only 60 min.     

Capillary electrophoresis using high ionic strength background electrolytes containing zwitterionic and non-ionic surfactants and its application to direct determination of bromide and nitrate in seawater

In capillary electrophoresis, it is commonly considered that even a moderately high ionic concentration in the background electrolyte (BGE) leads to high currents, resulting in Joule heating and serious peak distortion. As a new approach to overcome this problem, zwitterionic (Zwittergent-3-14) and/or non-ionic (Tween 20) surfactants have been added to BGEs containing high salt concentrations (e.g. 0.3 M NaCl) and have been shown to result in acceptable separation currents (<200 microA). In turn, these BGEs could be applied to the separation of samples containing high salt concentrations (such as undiluted seawater) without the occurrence of any significant peak broadening due to electrodispersion of the sample. For example, a BGE comprising 10 mM Zwittergent-3-14, 50 mM Tween 20, 0.3 M NaCl and 5 mM phosphate (ph 7) could be used for the determination of UV-absorbing anions in seawater, giving good peak shapes and detection limits of 0.8 microM and 0.6 microM for nitrate and bromide, respectively. The beneficial effects of the non-ionic surfactant on the separation were attributed largely to suppression of the electro-osmotic flow. On the other hand, the zwitterionic surfactant was found to be capable of the incorporation of some anions in accordance with the behaviour of these same surfactants in electrostatic ion chromatography. This incorporation resulted in a decreased conductivity of the BGE and also a change in the separation selectivity of the system.     

A collisional-radiative model including radiation trapping and transport phenomena for diagnostics of an inductively coupled argon plasma

The collisional-radiative model including radiation trapping and transport phenomena along with electron impact and radiative processes has been extended to the actual argon ICP, i.e. structural and inhomogeneous. The electron temperature (T_e), which is an essential plasma parameter for the collisional-radiative model, was measured from the background continuum without assuming the thermal equilibrium between the higher excited atomic levels and the ionic ground state. Observed T_e at the height of 15 mm above the load coil was 8400 K, which was rather lower compared with the literature values determined from the ratio of Ar emission line and continuum in a 40-MHz ICP, while the electron number density was approx. twice larger. The calculated population number densities showed close values to LTE, because the radiation trapping, not only for the resonance lines but also for non-resonance lines, compensated for the overpopulation of low lying levels which might be caused by spontaneous emission. The transport effect of species was negligible in the normal analytical region. In the coaxial zone around 5 mm above the load coil and in the tail flame of the plasma, however, the large inflow of electrons and ions by ambipolar diffusion or convection reduced the number density of argon neutral atoms, where the argon ICP can be denned as a recombining plasma.     

High-performance liquid chromatographic determination of free and total polyamines in human serum as fluorescamine derivatives

A highly sensitive and simple fluorimetric method for the determination of free and total polyamines, spermidine, spermine, putrescine and cadaverine, in human serum by high-performance liquid chromatography is described. The polyamines, obtained after clean-up of deproteinized serum by Cellex P column chromatography, are converted to their fluorescamine derivatives in the presence of nickel ion which inhibits the reaction of interfering amines with fluorescamine, and the derivatives are separated simultaneously by reversed-phase chromatography (LiChrosorb RP-18) with a linear gradient elution. The lower limits of detection are 10 and 15 pmole for spermine and the others in 0.5 ml of serum, respectively.     

Asymptotic theory of parameter estimation by a contrast function based on interpolation error

Interpolation is an important issue for a variety fields of statistics (e.g., missing data analysis). In time series analysis, the best interpolator for missing points problem has been investigated in several ways. In this paper, the asymptotics of a contrast function estimator defined by pseudo interpolation error for stationary process are investigated. We estimate parameters of the process by minimizing the pseudo interpolation error written in terms of a fitted parametric spectral density and the periodogram based on observed stretch. The estimator has the consistency and asymptotical normality. Although the criterion for the interpolation problem is known as the best in the sense of smallest mean square error for past and future extrapolation, it is shown that the estimator is asymptotically inefficient in general parameter estimation, which leads to an unexpected result.