Effect of salinity on biological concentrations of 137Cs in phytoplankton inhabited in brackish Lake Obuchi, Japan, bordered by nuclear fuel facilities

Lake Obuchi is on the Shimokita Peninsula, Aomori Prefecture, Japan, near several nuclear fuel-related facilities. The lake contains from oligohaline to polyhaline regions, and the salinity fluctuates greatly both spatially and temporally. This study examined the possible effect of salinity on biological concentrations of ¹³⁷Cs in phytoplankton on the basis of a culture experiment using stable Cs and phytoplankton species isolated from the lake. In both Cyclotellaand Skeletonema, the biological concentrations of Cs varied with salinity conditions, and a positive linear relation was found between maximum proliferation and biological concentrations of Cs. This revised version was published online in July 2006 with corrections to the Cover Date.     

Partition of carotenoid-to-bacteriochlorophyll singlet-energy transfer through two channels in the LH2 complex from Rhodobacter sphaeroides G1C

The excited-state dynamics of both carotenoid (Car) and bacteriochlorophyll (BChl) in the LH2 complex from Rhodobacter sphaeroides G1C were simultaneously probed by subpicosecond time-resolved absorption spectroscopy in the visible and near-infrared regions. By the use of a four excited-state model, where the 1B_u⁺ and 1B_u⁻ states were treated inclusively as the ‘1B_u' state, the time constant and the efficiency partition of Car-to-BChl singlet-energy transfer were determined to be 67–114 fs and 60–74% for the ‘1B_u' channel, and 1.39–1.42 ps and 24–38% for the 2A_g⁻ channel, when a time constant of 170–190 fs was assumed for the 1B_u-to-2A_g⁻ internal conversion.     

Electrochemistry and electrochromic properties of phenanthroline-iron(II/III) complex films

New films of the iron complexes with bis((2-hydroxyphenyl)methylaminosulfonyl)bathophenanthroline(HPBP) and bis((2-aminophenyl)methylaminosulfonyl)bathophenanthroline(APBP) ligands are prepared on the electrode surfaces by electrochemical polymerization. The resulting film-coated electrode shows a well-defined reversible voltammogram corresponding to the redox reaction of the Fe(II/III) complexes and an electrochromic change from red(absorption maximum: 540 nm) to colorless. The response rate of the color change to a potential step was found to be correlated to the apparent diffusion coefficient(Dapp) for the homogeneous charge-transport process within the film. The Dapp values estimated are (3-4) × 10⁻⁹cm²s⁻¹ for the [Fe(APBP)₃] film and(1-2) × 10⁻⁸cm²s⁻² for the [Fe(HPBP)₃] film, respectively, by potential-step chronoamperometric and chronocoulometric methods. The result of electrochemical quartz crystal microbalance(EQCM) measurements⁴) and dependence of the formal potential of the metal complex of the Fe(II/III) redox couple with activity of the supporting electrolyte anion in NaClO₄ aqueous solution showed that anion, cation, and solvent move simultaneously across the polymer film/solution interface during the redox reaction. A piezoelectric admittance measurement⁴⁾ of the poly[Fe(APBP)₃] coated quartz crystal electrode showed that the viscosity of the film is affected by the oxidation state of iron.     

INDUCTION OF A TRANSIENT ENHANCEMENT OF LOW LEVEL CHEMILUMINESCENCE IN INTACT LEAVES BY ANAEROBIC TREATMENT

Intrinsic low level chemiluminescence of dark adapted intact leaves exhibits a transient enhancement of light emission when ambient air is replaced with an anaerobic atmosphere. Re establishing aerobic conditions gives rise to a complex kinetic behavior of the light emission in the post-anoxic phase. Metabolic changes within the leaf are suggested to be responsible for this phenom enon, where intactness of the leaf is found to be of crucial importance. Leaf homogenate showed nearly oxygen independent chemiluminescence. In contrast, low level chemiluminescence of UV-light damaged leaves and of chloroplast preparations was inhibited by oxygen depletion. Spectral analyses of the ultraweak light emission from the intact leaf indicates that in both aerobic and anaerobic cases, the source of the ultraweak light is the same. The similarity to the spectrum of delayed fluorescence also obtained from the leaf suggests that chlorophyll is the light emitting species.     

Dual modification of a triple-stranded β-helix nanotube with Ru and Re metal complexes to promote photocatalytic reduction of CO2

We have constructed a robust β-helical nanotube from the component proteins of bacteriophage T4 and modified this nanotube with Ru(II)(bpy)(3) and Re(I)(bpy)(CO)(3)Cl complexes. The photocatalytic system arranged on the tube catalyzes the reduction of CO(2) with higher reactivity than that of the mixture of the monomeric forms.     

Synthesis and antitumor activity of benzimidazolyl-1,3,5-triazine and benzimidazolylpyrimidine derivatives

Triamino-substituted 1,3,5-triazine and pyrimidine derivatives were synthesized and tested for antitumor activities using some human cancer cell lines and murine leukemia cell lines. All the compounds having benzimidazolyl and morpholino groups as substituents on the 1,3,5-triazine ring showed antitumor activity. Pyrimidine derivatives having the same groups as substituents also showed antitumor activity. Among them, the compounds having 1-benzimidazolyl, morpholino and cis-2,3-dimethylmorpholino groups as substituents on the 1,3,5-triazine ring or pyrimidine ring exhibited the most potent antitumor activity, and these compounds exhibited no or very weak aromatase inhibitory activity. In contrast, the compounds having imidazolyl group instead of benzimidazolyl group as a substituent on the 1,3,5-triazine ring showed a potent aromatase inhibitory activity.     

(Nitronyl Nitroxide)‐Substituted Trioxytriphenylamine Radical Cation Tetrachlorogallate Salt: A 2p‐Electron‐Based Weak Ferromagnet Composed of a Triplet Diradical Cation

The synthesis and the solid state magnetic properties of (nitronyl nitroxide)‐substituted trioxytriphenylamine radical cation tetrachlorogallate, NNTOT+·GaCl4? , are reported. In the temperature region between 300 and 3 K, the magnetic behavior is characterized by the strong intramolecular ferromagnetic interaction (J/k_B=+400 K) between the radical ( NN ) and the radical cation ( TOT ⁺) and the weak intermolecular antiferromagnetic interaction (J/k_B=?1.9 K) between NNTOT⁺ ions. Below 3 K, a 3D‐type long‐range magnetic ordering into a weak ferromagnet was observed (T_N=2.65 K). The magnetic entropy (S_mag=8.97 J K^?1 mol^?1) obtained by the heat capacity measurement is in good agreement with the theoretical value of R ln3=9.13 J K^?1 mol^?1 based on the S=1 state.     

Pre-evaluation of metal ions as a catalyst on chemiluminometric sequential injection analysis with luminol-H2O2 system

Catalytic effect of metal ions on luminol chemiluminescence (CL) was investigated by sequential injection analysis (SIA). The SIA system was set up with two solenoid micropumps, an eight-port selection valve, and a photosensor module with a fountain-type chemiluminescence cell. The SIA system was controlled and the CL signals were collected by a LabVIEW program. Aqueous solutions of luminol, H₂O₂, and a sample solution containing metal ion were sequentially aspirated to the holding coil, and the zones were immediately propelled to the detection cell. After optimizing the parameters using 1 × 10⁻⁵ M Fe³⁺ solution, catalytic effect of some metal species was compared. Among 16 metal species examined, relatively strong CL responses were obtained with Fe³⁺, Fe²⁺, VO²⁺, VO₃⁻, MnO₄⁻, Co²⁺, and Cu²⁺. The limits of detection by the present SIA system were comparable to FIA systems. Permanganate ion showed the highest CL sensitivity among the metal species examined; the calibration graph for MnO₄⁻ was linear at the concentration level of 10⁻⁸ M and the limit of detection for MnO₄⁻ was 4.0 × 10⁻¹⁰ M (S/N = 3).     

The Reductive Leaching of Chalcopyrite by Chromium(II) Chloride for the Rapid and Complete Extraction of Copper

A hydrometallurgical process is developed to lower the costs of copper production and thereby sustain the use of copper throughout the global transition to renewable energy technologies. The unique feature of the hydrometallurgical process is the reductive treatment of chalcopyrite, which is in contrast to the oxidative treatment more commonly pursued in the literature. Chalcopyrite reduction by chromium(II) ion is described for the first time and superior kinetics are shown. At high concentrate loadings of 39, 78, and 117 g L⁻¹, chalcopyrite reacted completely within minutes at room temperature and pressure. The XRD, SEM-EDS, and XPS measurements indicate that chalcopyrite reacts to form copper(I) chloride (CuCl). After the reductive treatment, the mineral products are leached by iron(III) sulfate to demonstrate the complete extraction of copper. The chromium(II) ion may be regenerated by an electrolysis unit inspired by an iron chromium flow battery in a practical industrial process.     

ULTRAWEAK LIGHT EMISSION FROM RAT LIVER NUCLEI

Abstract–An extremely weak native light emission from rat liver nuclei was detected and studied using a highly sensitive single photon counting system. This emission is oxygen dependent and we attribute it to (per) oxidative processes. The effects of deuterium oxide and l,4-diazabicyclo-[2.2.2] octane on the light emission suggests the possible involvement of singlet oxygen. The kinetic features of the underlying reactions including biphasic response to both oxygen and temperature changes, could be clearly discerned. Further study of this light emission can serve as a useful adjunct to biochemical investigations of oxidative processes which play an important role in mutation, carcinogenesis and aging.