Uptake and excretion of total inorganic arsenic by the freshwater alga Chlorella vulgaris

Arsenic-tolerant freshwater alga Chlorella vulgaris which had been collected from an arsenicpolluted environment were tested for uptake and excretion of inorganic arsenic. Approximately half the quantity of arsenic taken up by C. vulgaris was estimated to be adhered to the extraneous coat (10 wt %) of the cell. The remainder was bioaccumulated by the cell. Both adhered and accumulated arsenic concentrations increased with an increase in arsenic(V) concentration of the aqueous phase. Arsenic(V) accumulation was affected by the growth phse: arsenic was most actively accumulated when the cell was exposed to arsenic during the early exponential phase and then accumulation decreased with an increase in culture time exposed to arsenic. The alga grew well in the modified Detmer (MD) medium containing 1 mg As(III) dm^?3 and the growth curve was approximated by a ‘logistic equation’. Arsenic(III) was accumulated up to the second day of the culture time and arsenic(III) accumulation decreased with an increase in the culture time after that. Arsenic accumulation was also largely affected by various nutrients, especially by managanese, iron and phosphorus compounds. A modified MD medium with the three nutrients was proposed for the purpose of effective removal of arsenic from the aqueous phase. Using radioactive arsenate (Na₂H⁷⁴AsO₄), the arsenic accumulated was found to be readily excreted under conditions which were unfavourable for the multiplication of C. vulgaris.     

Results from Super-Kamiokande and K2K

Results from Super-Kamiokande-I’s entire 1496 live days of solar neutrino data are presented, including the absolute flux, energy spectrum, zenith angle (day/night) and seasonal variation. The possibility of MSW and vacuum oscillations is discussed in light of these results. Results from the first 1289 days of Super-K-I’s atmospheric neutrino analysis are also presented, including the evidence for ν_μ →ν _τ oscillations, against ν_μ → ν_sterile oscillations, and the current limits on proton decay. Finally, results based on 56 × 10¹⁹ protons on target are given for the K2K long-baseline neutrino oscillation experiment.     

Synthesis of poly(vinylene-arsine)s: alternating radical copolymerization of arsenic atomic biradical equivalent and phenylacetylene

Novel organoarsenic polymers, poly(vinylene-arsine)s, were synthesized by a free-radical alternating copolymerization of phenylacetylene with cyclooligoarsines as an atomic biradical equivalent. The polymerization between pentamethylpentacycloarsine (1a) or hexaphenylhexacycloarsine (1b) with phenylacetylene (2) in the presence of a catalytic amount of AIBN (in benzene; refluxing; for 12 h) gave the corresponding poly(vinylene-arsine)s. The obtained polymers were soluble in common organic solvents such as THF, chloroform, and benzene. From gel permeation chromatographic analysis (chloroform, PSt standards), the number-average molecular weights of the polymers from 1a and 1b were found to be 11500 and 3900, respectively. The structures of the polymers were supported by 1H and 13C NMR spectroscopies. The corresponding polymer was also obtained by irradiation of a benzene solution of 1a and 2 with xenon lamp at room temperature. After the polymer from 1a was stirred vigorously with 30% H2O2, the 1H NMR spectrum of the polymer showed the methyl proton that was assigned to As(III)-Me, suggesting the insensitivity of the trivalent state arsenic in the main chain to the oxidation. The structures and the molecular weights of the polymers were insensitive to the feed ratio of the monomers. This result indicates that the addition of the arsenic radical to phenylacetylene was a rate-determining step in the copolymerization.     

Decomposition of Co2TiO4 spinel below 1000 K

Co₂TiO₄ spinel was found to decompose to the mixture of CoTiO₃ ilmenite and Co₃O₄ spinel below 1000 K. The decomposition rate was the larger for the sample ground for the longer period. It showed a maximum around 870–920 K which seemed to appear from the balance between the rate increase by diffusion and the decrease of nucleation probability with temperature. The thermodynamical consideration supported the experimental results.     

Preparation of '2,('3)-O-Acyl-pCpA derivatives as substrates for T4 RNA ligase-mediated “chemical aminoacylation”

The synthesis of '2('3)-O-(amino)acyl-pCpA derivatives is described and the products are characterized chemically and as substrates for T4 RNA ligase in the presence of E. coli tRNA ^phe-C_OH. The modified (N-acetylammo)acyl-tRNA's so derived are characterized by their chromatographic and biochemical properties, and by their ability to act as P-site tRNA donors in the peptidyltransferase reaction.     

Synthesis of fluoride garnets {Na3}[M3+2](Li3)F12 (M = Al,Cr, and Fe) from aqueous solution and their properties

The garnet-type fluorides, Na₃M₂Li₃F₁₂ (M = Al, Cr, and Fe) were synthesized as the coprecipitates of ～1 to 10 μm powders from HF solutions. The garnet structures were always obtained under acidic conditions. The incorporation of water molecules into the structure of the Cr and Fe garnets was observed. After heat treatment at 300°C, very small unknown peaks were observed in the X-ray powder pattern in addition to the garnet phase which had a slightly smaller value of the lattice constant than that of hydrous garnets. From the measurement of magnetic properties and Mössbauer effects, the Fe and Cr garnets were found to be paramagnetic with both ions in the trivalent state. Presentation of infrared spectra of the garnets is also included.     

Synthesis of Optically Active P‐Chiral and Optically Inactive Oligophosphines

A series of optically active P‐chiral oligophosphines (S,R,R,S)‐ 2 , (S,R,S,S,R,S)‐ 3 , (S,R,S,R,R,S,R,S)‐ 4 , and (S,R,S,R,S,R,R,S,R,S,R,S)‐ 5 with four, six, eight, and 12 chiral phosphorus atoms, respectively, were successfully synthesized by a step‐by‐step oxidative‐coupling reaction from (S,S)‐ 1 . The corresponding optically inactive oligophosphines 1′ – 5′ were also prepared. Their properties were characterized by DSC, XRD, and optical‐rotation analyses. While optically active bisphosphine (S,S)‐ 1 and tetraphosphine (S,R,R,S)‐ 2 behaved as small molecules, octaphosphine (S,R,S,R,R,S,R,S)‐ 4 and dodecaphosphine (S,R,S,R,S,R,R,S,R,S,R,S)‐ 5 exhibited the features of a polymer. Furthermore, DSC and XRD analyses showed that hexaphosphine (S,R,S,S,R,S)‐ 3 is an intermediate between a small molecule and a polymer. Comparison of optically active oligophosphines 1 – 5 with the corresponding optically inactive oligophosphines 1′ – 5′ revealed that the optically active phosphines have higher crystallinity than the optically inactive counterparts. It is considered that the properties of oligophosphines depend on the enantiomeric purity as well as the oligomer chain length.     

Synthesis of Star-Shaped Polymers via Coordination of Bipyridyl-Terminated Polyoxyethylene with Metal Ions

Abstract

This paper describes the synthesis of various star-shaped polymers by means of complexation of bipyridyl-terminated polyoxyethylene with Ru(II) ion. Three kinds of bipyridyl-terminated polyoxyethylenes of different molecular weights were prepared from the corresponding polyoxyethylene monomethyl ethers with narrow molecular weight distributions. Bipyridyl was found to be introduced quantitatively at the end of the polymers based on the results of UV spectra. The formation of a star-shaped polymer was carried out by the reaction of RuCl₃ with three equivalents of bipyridyl-terminated polyoxyethylene. The UV spectrum of the star-shaped polymer obtained supported the formation of a typical Ru(II) tris(bipyridyl) complex. From the results of GPC, the star-shaped polymer obtained had a higher molecular weight than the pre-polymer and showed a narrow molecular weight distribution. In the case of a Ni(II) or a Co(II) complex, however, the star-shaped polymer was found to be dissociated into three linear prepolymers under the conditions of GPC measurement.     

Syntheses and properties of dumbbell‐shaped POSS derivatives linked by luminescent π‐conjugated units

Dumbbell‐shaped isobutyl‐substituted 1,2‐bis(4‐vinylphenyl)acetylene‐linked POSS (DA1), 9,10‐bis(4‐vinylphenyl)ethynyl)anthracene‐linked POSS (DA2), and 5,5″‐bis((4‐vinyl)phenyl)ethynyl)‐2,2′:5′2″‐terthiophene‐linked POSS (DA3), and corresponding model compounds were synthesized by cross metathesis and Sonogashira reaction, and their film formability, and thermal and optical properties were examined. The dumbbell structures of the obtained compounds were confirmed by ¹H‐, ¹³C‐, and ²⁹Si‐NMR and MALDI‐TOF‐MS analysis. The dumbbell‐shaped POSS compounds gave optically transparent films. All the model compounds, however, formed opaque films. All the films were emissive under UV irradiation. The dumbbell structures minimize longer wavelength shifts and improve emission efficiency of the luminescent π‐conjugated linker units in their solid states compared with the model compounds. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012.     

Lembehsterols A and B,novel sulfated sterols inhibiting thymidine phosphorylase,from the marine sponge Petrosia strongylata

Lembehsterols A (1) and B (2), two novel sulfated sterols, were isolated from the marine sponge Petrosia strongylata. Both sterols showed inhibitory activity against thymidine phosphorylase, which is an enzyme related to angiogenesis in solid tumors. The structures of these sulfated sterols were established on the basis of chemical and physicochemical evidence.