Simple method for the simultaneous determination of noradrenaline, dopamine and serotonin by stepwise elution from a short column of weak cation-exchange resin

A simple method for the simultaneous determination of noradrenaline, dopamine and serotonin using a short column of Amberlite CG-50 is described. Noradrenaline and dopamine were eluted from the column with phosphate buffers containing 1.5 and 4.0% boric acid, respectively, and then serotonin was eluted with 1.0 N HCl. Catecholamines were determined by a modification of the ethylenediamine condensation method using potassium ferricyanide as oxidant and isobutanol for extraction of the fluorophores. Serotonin was measured by the acidic o-phthalaldehyde method. The method was applied to the simultaneous determination of noradrenaline, dopamine and serotonin in discrete regions of rat brain.     

UV exposure of elementary school children in five Japanese cities

A 1 week UV‐exposure measurement and outdoor‐activity pattern survey was conducted for elementary school children for four seasons at five sites in Japan, i.e. Sapporo (43°05′N, altitude 40 m), Tsukuba (36°05′N, 20 m), Tokyo (35°40′N, 45 m), Miyazaki (31°60′N, 40 m) and Naha (26°10′N, 5 m), and UV exposure was measured directly and estimated using outdoor‐activity records. The study site with largest UV exposure was Miyazaki, a southern rural area. Comparing the results for boys and girls, UV exposure was larger in boys. UV exposure was large in spring and summer and small in winter. The total amount of UV exposure in spring and summer contributed 57.7–73.4% of total exposure for the year. As a whole, 8.1% and 1.8% of the schoolchildren were exposed to more than 1 minimum erythemal dose (MED) and 2 MED of solar UV in a day, respectively. The estimated yearly UV exposure ranged from 49 207 J/m² in Miyazaki to 31 520 J/m² in Tsukuba. The actual UV exposure correlated to potential UV exposure, estimated using outdoor‐activity records and ambient UV irradiance, but the ratio differed by season and site. The yearly average of percent UV exposure to ambient UV on a horizontal plane ranged from 9.9% in Tokyo to 4.0% in Naha. In the questionnaire survey on outdoor‐activity pattern, a short question “How long did you spend time outdoors between 0900 and 1500 h?” gives the best estimates of UV exposure.     

Analytical application of second-harmonic a.c. polarography

Phase-selective second-harmonic a.c. polarography can be used to distinguish two different species having similar reduction potentials. Because each species has a different phase angle depending on the electrode kinetics, a certain phase angle can be chosen to detect only one component in the mixture. In 1 M potassium chloride solution, indium-(III) at the 4 × 10^-6 M level can be determined in the presence of 50-fold amounts of cadmium(II), and zinc(II) at the 2 × 10^-5 M level in the presence of 100-fold amounts of nickel(II).     

A new ruthenium complex with an electron-donating aminoindenyl ligand for fast metal-mediated living radical polymerizations

A new ruthenium complex with an electron-donating aminoindenyl ligand induces a fast living radical polymerization of methyl methacrylate (MMA) in the presence of a chloride initiator to give polymers with controlled and variable molecular weights (Mn = 103-105) and very narrow molecular weight distributions (Mw/Mn < 1.1). The structure and high activity of the catalyst were analyzed by X-ray crystallography and cyclic voltammetry in comparison to those of a similar complex with an indenyl ligand.     

Absorption spectroscopic and ESR studies on one-electron reduction products of copper(II) and oxovanadium(IV) tetraphenylporphyrins produced by γ-radiolysis in 2-methyltetrahydrofuran solutions at 77 K

Optical absorption spectra of one-electron reduced species of copper(II) and oxovanadium(IV) tetraphenylporphyrins. Cu(II)TPP and V(IV)OTPP, in 2-methyltetrahydrofuran at 77 K reveal that not the central metal but the porphyrin ligand is reduced by an excess electron. The triplet ESR spectrum resulting from the spin-spin interaction between two odd electrons located on the porphyrin ligand and the central metal is observed for the one-electron reduced species of V(IV)OTPP while not for that of Cu(II)TPP.     

Intercalation of gaseous thiols and sulfides into Ag+ ion-exchanged aluminum dihydrogen triphosphate

Ag(+) ion-exchanged layered aluminum dihydrogen triphosphate (AlP) with the interlayer distance of 0.85 nm was synthesized by the ion-exchange of proton in triphosphate with Ag(+) ion. The amount of exchanged Ag(+) ion depended on the concentration of AgNO(3) aqueous solution. Ag(+) ion-exchanged AlP adsorbed gaseous thiols and sulfides into the interlayer region. The adsorption amounts of thiols were more than those of sulfides, thiols with one mercapto group > thiol with two mercapto groups > sulfides, and depended on the amount of exchanged Ag(+) ion in the interlayer region. The thiols with one mercapto group were intercalated to expand the interlayer distance of Ag(+) ion-exchanged AlP, whereas there was no expansion in the adsorption of sulfide. In the case of thiol with two mercapto groups, there was observed contraction of the interlayer distance through the bridging with Ag(+) ions of the upper and lower sides of the interlayer region.     

Asymmetric Michael reactions of α-substituted acetates with cyclic enones catalyzed by multifunctional chiral Ru amido complexes

Well-defined 16-electron chiral Ru amido complexes, Ru[(R,R)-diamine](η⁶-arene), efficiently catalyze asymmetric Michael additions of Michael donors to cyclic enones to give adducts in high yields and with excellent ee’s. β-Ketoesters or nitroacetate as Michael donors react with 2-cyclopentenone in toluene or t-butyl alcohol containing the Ru amido catalyst (S/C=50) to afford the Michael adduct in 99% yield and with up to 92% ee. The outcome of the reaction was delicately influenced by the structures of the diamine and arene ligands as well as reaction conditions.     

Pyrimidine derivatives. IX . Synthesis of bromosubstituted 5-nitro-2,4(1H,3H)-pyrimidinedione derivatives

The following 5-nitro-2,4(1H,3H)-pyrimidinediones possessing bromo substituted side chains at the 1- and 6-positions were prepared by bromination of 3,6-dimethyl-1-(ω-hydroxyalkyl)-5-nitro-2,4(1H,3H)-pyrimidinediones 4a and 4b and its nitrates 2a and 2b . The three of mono-bromo derivatives are: 1-(ω-acetoxyalkyl and ω-hydroxyalkyl)-6-bromomethyl-3-methyl. 6a, 6b, 7a and 7b and 1-(ω-bromoalkyl)-3,6-dimethyl-2,4(1H,3H)- pyrimidinediones 8a and 8b . The one type dibromo derivatives are: 1-(ω-bromoalkyl)-6-bromomethyl-3-methyl-2,4(1H,3H)-pyrimidinediones 5a and 5b .     

Cm3+-F- interaction in a mixed system of methanol and water

The stability constants (b₁) of the monofluoro complex of Cm(III) have been determined in mixed solvents of methanol and water using the solvent extraction technique. The values of lnb₁ increase as the molar fraction of methanol (X_s) in the mixed solvent increases. The variation in the stability constants mainly depends on the solvation of F^- and slightly depends on both (1) the solvation of cations in connection with the complexation of CmF²⁺ and (2) the electrostatic attraction of Cm³⁺-F^-. The variation in lnb₁ for Cm(III) due to the effect of both (1) and (2) is similar to that for Sm(III). By variation of lnb₁ the coordination number in the primary hydration sphere (CN) of Cm(III) decreased from a value between CN = 9 and CN = 8 to CN = 8, at about X_s = 0.02. The X_s value of the inflection point of the CN for Cm is slightly lower than X_s = 0.06 for Sm(III) and X_s = 0.03 for Eu(III), previously obtained.     

Large third-order optical nonlinearity of self-assembled porphyrin oligomers.

Third-order nonlinear optical properties of two series of self-assembled porphyrin wires, one being terminated by zinc porphyrin and the other by free base porphyrin, were measured by femtosecond time-resolved optical Kerr effect. The hyperpolarizability values of the latter series were extremely large ranging from 10-30 to 10-29 esu, 10 times larger than the former. The behavior is accounted for by the contribution of terminal free base porphyrin to enhance the molecular polarization by acceptor nature toward central metalloporphyrin array.