Determination of environmental actinide nuclides and210Pb(210Po) by low-energy photon spectrometry with alpha-spectrometry

Low-energy photon spectrometry with -spectrometry was used to determine the environmental concentrations of low-level actinides and other nuclides, especially²¹⁰Pb and²¹⁰Po. The isotopic ratio of²⁴⁰Pu/²³⁹Pu was successfully determined by measuring L_x-ray/-ray counting ratio. A reliable method has been developed for the determination of extremely low-level²³⁷Np global fallout in environmental samples. The non-destructive determination by Ge-LEPS for natural²¹⁰Pb in various samples (tobacco leaves, commercially available tobacco, etc.) was also carried out with the determination of²¹⁰Po by -spectrometry using²⁰⁹Po as a yield tracer.     

Catalytic, highly enantio- and diastereoselective pinacol coupling reaction with a new tethered bis(8-quinolinolato) ligand

A new class of chiral ligand, tethered bis(8-quinolinol) (TBOxH), is developed. Its chromium complex, TBOxCrCl (3 mol %), effectively catalyzes the pinacol coupling reaction of aromatic aldehydes at room temperature with high yield (up to 94%), high diastereoselectivity (up to dl:meso = 98:2), and high enantioselectivity (up to 98%). The scope of the present method turns out not to be limited to aromatic aldehyde derivatives, as cyclohexanecarboxaldehyde undergoes pinacolization as well (44% yield, dl:meso = 93:7, 84% ee). The method provides an efficient access to enantioenriched 1,2-diols.     

DESIGN AND PERFORMANCE OF THE OKAZAKI LARGE SPECTROGRAPH FOR PHOTOBIOLOGICAL RESEARCH

A computer-operated spectrograph was recently built at Okazaki, Japan. Different specimens can be placed on a horseshoe-shaped focal curve (10 m long) covering a wavelength range of 250 to 1000 nm so they can be irradiated simultaneously. The linear dispersion is about 0.8 nm/cm. The photon fluence rate on the focal curve is 5 x 10¹⁵. photons x cm^-2 x s^-1 at 300nm and 1 x 10¹⁶ photons x cm^-2 x s^-1 at 600 and at 900 nm. The spectral half width is 5.5 nm or less on the focal curve. The stray light content is about 10^-5 of the main peak at the peak wavelength ± 100 nm. Specimens are set in microcomputer-controlled threshold boxes so that wavelengths, photon fluence rates, photon fluences and timing of irradiations are controlled automatically according to a pre-programmed schedule. An optical fiber system is also provided for remote irradiations.     

Ideal nonideality in adsorption of 2-aminoethanethiol and 2-mercaptoethane sulfonic acid to form electrostatically stabilized binary self-assembled monolayers on Au(111)

In formation of binary self-assembled monolayers (SAMs) composed of 2-aminoethanethiol (AET) and 2-mercaptoethane sulfonic acid (MES) by adsorption from an ethanol solution on Au(111), the adsorption shows nearly ideal nonideality in that the surface ratio of MES to AET in the SAM is unity and does not depend on the mixing ratio of MES to AET in the bathing ethanol solution used for preparing SAMs, chi(soln)MES, over the wide range of chi(soln)MES between 0.01 and 0.95. X-ray photoelectron spectroscopy confirms that at least 80% of AET molecules adsorbed are protonated in this range of chi(soln)MES, indicating that the electrostatic interaction between positively charged AET and negatively charged MES is responsible to the observed nonideality. Correspondingly, there appears only one cathodic peak in a linear-sweep voltammogram of the reductive desorption of the SAM, having a narrow full width at half-maximum of about 20 mV. This suggests the presence of strong lateral attractive interaction between the adsorbed thiolates.     

Determination of Low-Level Ethylenediaminetetraacetic Acid in Water Samples by Ion Chromatography with Ultraviolet Detection

A convenient and sensitive ion chromatographic (IC) method for the analysis of ethylenediaminetetraacetic acid (EDTA) in water samples was proposed. Using a fast reversible reaction of free EDTA and metal–EDTA complexes into Fe(III)–EDTA complex in the presence of Fe(III) ions, sample solutions were applied to an ion-exchange column using a mobile phase (pH 2.3), which was composed of 100 μM Fe(III) chloride and 5 mM methanesulfonic acid. The addition of Fe(III) solution (100 μL) containing 10 mM Fe(III) chloride and 0.5 M methanesulfonic acid to the sample solution (10 mL) permitted the injection of a large volume (400 μL) of sample, which allowed for greater sensitivity. The proposed IC method gave a highly linear (r ² > 0.999) calibration curve ranging 0.005–1.0 μM EDTA and had a limit of detection of 1.5 nM. High repeatability (RSD < 2.1%) and recoveries (88–108%) were also obtained. With this method, total EDTA level in raw and drinking waters were analyzed successfully.     

Simple calculations of Franck-Condon factors for electronic transition bands of polyacenes

Progressional intensities have been calculated for the L_a and L_b transitions of the polyacenes, on the basis of semi-empirical SCF CI calculations of geometry changes upon electronic excitation and from normal analyses. The results give the Franck-Condon intensity distributions over various totally symmetric modes in good agreement with the vibrational structures observed in high resolution spectra.     

Photoinduced ionic polymerization. VII. Cationic polymerization of cyclohexene oxide in solid state

Photopolymerization of cyclohexene oxide in the presence of electron acceptors was studied in a bulk system (in liquid as well as in solid states). The polymerization was proved to proceed by a cationic mechanism in both states by the effect of inhibitors. In a liquid phase the light intensity dependence of the rate of polymerization and the molecular weight distribution showed a contribution of a free ionic polymerization. Any discontinuous phenomenon in the rate as well as in the molecular weight was not discerned between liquid(above ?36°C) and plastic crystal (between ?36 and ?81°C) phases. A quantum yield of monomer consumption as high as 8 × 10³ was observed in the plastic crystal phase. Below ?81°C in the normal crystal phase the rate as well as the molecular weight was remarkably suppressed.     

Fibrinolytic effect of tissue plasminogen activator on cerebral embolism in stroke-prone spontaneously hypertensive rats.

To study the thrombolytic effect of tissue plasminogen activator (t-PA) on cerebral emboli, we characterized cerebral embolization in stroke-prone spontaneously hypertensive rats (SHRSPs) and Wistar Kyoto rats (WKYs). [125I]Fibrin clot particles (20-100 microns diameter) were injected twice at an interval of 90 min into the left internal carotid artery of WKYs and SHRSPs. After each injection, spontaneous embolus dissolution was monitored with a gamma-ray detector placed on the head of the embolic rats. Embolus dissolution was spontaneously generated in 15 min after the injection of fibrin clots. In WKYs, 21% and 42% of the clots were dissolved 30 and 90 min after the second embolization, respectively. On the other hand, the spontaneous embolus dissolution in SHRSPs was significantly lower than that of WKYs, indicating that the endogenous fibrinolytic ability of SHRSPs is less potent than that of normotensive rats. The intravenous administration of t-PA at doses of 75, 250 and 750 micrograms/kg caused a dose-dependent embolus dissolution in SHRSPs. Furthermore, systematically applied t-PA produced embolus dissolution without causing systemic plasminogen activation, fibrinogen breakdown or bleeding. In conclusion, the intravenous administration of t-PA produces selective embolus dissolution without systemic fibrino(geno)lysis in a cerebral embolic SHRSP.     

THE CONFORMATIONAL ANALYSIS AND PHOTOISOMERIZATION OF RETINOCHROME ANALOGS WITH POLYENALS

Abstract— 3, 7-Dimethyl-2, 4, 6, 8, 10-dodecapentaenal was synthesized for reconstitution of the retinochrome analog. Its opsin shift was 1000 cm ¹ smaller than that of native retinochrome, whose chromophore contains the same number of double bonds. The conformational change from 6-s-trans to 6-s-cis , as figured in a retinal molecule, plays an important role in the formation of the retinochrome analog, based on the estimation of opsin shifts for retinal analogs locked in the 6-s conformation. Thus the conformation of the 6–7 single bond in the native retinochrome was suggested to be 6 -cis . Analysis of the circular dichroic spectra of retinochrome analogs revealed that the 6-s conformation is independent of the appearance of the β-band. The stereoselectivity in the photoisomerization of the retinal analogs by a retinochrome template depends on the hydrophobic binding in the region of the β-ionone ring.     

Selective reduction of tertiary alkyl,benzyl, and allyl halides to hydrocarbons using lithium 9,9-di-n-butyl-9-borabicyclo[3.3.1]nonanate

The title 9-borabicyclo[3.3.1]nonane(9-BBN) ate complex (1) brings about selective removal of tertiary alkyl, benzyl and allyl halides to give the corresponding hydrocarbons in excellent yields without concomitant attack on secondary, primary and aryl derivatives. The reduction of cis- and trans - 4 - t - butyl - 1 - methylcyclohexyl chlorides (2) with 1 gives 4 - t - butyl - 1 - methylcyclohexanes (3) with partial inversion of configuration in cyclohexane, while that in benzene gives thermodynamically stable trans-3 predominantly. The reactions of 1,1 - dimethyl - 5 - hexenyl chloride (4) and 1,7,7 - trimethylbicyclo[2.2.1]hept - 2 - yl chloride (8) with 1 proceed with the rearrangements characteristic to a carbonium ion intermediate. The reduction of 1 - ethyl - 1 - methylpentyl chloride with 1 follows a second-order rate equation.