Removal of aqueous ammonium with magnesium phosphates obtained from the ammonium-elimination of magnesium ammonium phosphate

In order to recycle magnesium ammonium phosphate (MgNH4PO4.6H2O: MAP) obtained from MAP process, which is one of the attractive processes for removal of aqueous ammonium and phosphate from wastewater, ammonium elimination from MAP to magnesium phosphates and ammonium incorporation into the magnesium phosphates have been investigated in the present study. It is confirmed that magnesium hydrogen phosphate (MgHPO4) is favorably obtained from the ammonium elimination from MAP at temperatures greater than 353 K, although magnesium phosphate (Mg3(PO4)2) and magnesium pyrophosphate (Mg2P2O7) have been suggested as possible candidates. Based on the dissolution-precipitation mechanism for the removal of aqueous ammonium with magnesium phosphates, three magnesium phosphates were employed for the removal of aqueous ammonium. The order of the removal rate of the aqueous ammonium was MgHPO4>Mg3(PO4)2>Mg2P2O7, as expected from the solubility of those magnesium phosphates. The removability of the solid obtained from ammonium elimination of MAP is also confirmed. The present results show that MAP can be employed as an advanced material for the removal/recovery of ammonium, although it is generally accepted that an excess of MAP obtained from the wastewater treatment can be only used as a slow-acting fertilizer.     

AgInZn7S9 solid solution photocatalyst for H2 evolution from aqueous solutions under visible light irradiation

AgInZn7S9 with a 2.3 eV band gap, which was a solid solution of AgInS2 and ZnS semiconductors, showed photocatalytic activity for H2 evolution from an aqueous solution containing sacrificial reagents SO3(2-) and S2- under visible light irradiation (lambda > 420 nm) even without a Pt cocatalyst, and loading of the Pt cocatalyst improved the photocatalytic activity.     

A facile combinatorial approach to construct a ratiometric fluorescent sensor: application for the real-time sensing of cellular pH changes

Realtime monitoring of the cellular environment, such as the intracellular pH, in a defined cellular space provides a comprehensive understanding of the dynamics processes in a living cell. Considering the limitation of spatial resolution in conventional microscopy measurements, multiple types of fluorophores assembled within that space would behave as a single fluorescent probe molecule. Such a character of microscopic measurements enables a much more flexible combinatorial design strategy in developing fluorescent probes for given targets. Nanomaterials with sizes smaller than the microscopy spatial resolution provide a scaffold to assemble several types of fluorophores with a variety of optical characteristics, therefore providing a convenient strategy for designing fluorescent pH sensors. In this study, fluorescein (CF) and tetramethylrhodamine (CR) were assembled on a DNA nanostructure with controlling the number of each type of fluorophore. By taking advantage of the different responses of CF and CR emissions to the pH environment, an appropriate assembly of both CF and CR on DNA origami enabled a controlled intensity of fluorescence emission and ratiometric pH monitoring within the space defined by DNA origami. The CF and CR-assembled DNA origami was successfully applied for monitoring the intracellular pH changes.

A combinatorial assembly of two types of intensity-based fluorophores on a DNA nanostructure provided a ratiometric pH probe with high emission intensity for monitoring intracellular pH changes.     

Transfer of actinide ion at the interface between aqueous and nitrobenzene solutions studied by controlled-potential electrolysis at the interface

A novel electrochemical method based on controlled-potential electrolysis has been developed for the elucidation of the ion transfer at the interface between two immiscible electrolyte solutions (ITIES). A relationship between the applied interfacial potential (E_app) and the amount of the ion transferred (A_tr) was investigated after an electrolytic equilibrium was attained by controlled-potential electrolysis. The A_tr was determined chemically or radiometrically instead of by current measurement. It was found that (i) controlled-potential electrolysis was applicable to the study of the transfer of such hydrophilic ions as transition metal ions which gave no appreciable current within the potential window in voltammetry or polarography at ITIES, (ii) controlled-potential electrolysis in combination with a sensitive analytical method enabled a study of the transfer reaction of an ion of very dilute concentration, and (iii) even when the transfer reaction of an ion was irreversible or quasi-reversible, a standard ion transfer potential could be determined by controlled-potential electrolysis without using a kinetic parameter. The controlled-potential electrolysis method developed was applied to the transfer reactions of actinide ions such as UO₂ ²⁺ and Am³⁺ from aqueous solution to nitrobenzene solution in the absence or presence of an ionophore facilitating the transfer. The Gibbs energy for the transfer of actinide ion and a stability constant of the complex between an actinide ion and the ionophore in nitrobenzene solution were determined from log D versus E_app plots (D the ratio of the concentration of the ion in nitrobenzene solution to that in aqueous solution). The feasibility of controlled-potential electrolysis as a method for electrolytic separation of actinide ions is discussed.     

Synthesis of polyphosphonates containing pendant chloromethyl groups by the polyaddition of bis(oxetane)s with phosphonic dichlorides

The polyaddition of 4,4′‐bis[(3‐ethyl‐3‐oxetanyl)methoxy]biphenyl (4,4′‐BEOBP) and phenylphosphonic dichloride (PPDC) with quaternary onium salts as catalysts proceeded under mild reaction conditions to afford a polymer containing phosphorous atoms in its main chain. A polyphosphonate with a high number‐average molecular weight (10,300) was obtained by the reaction of 4,4′‐BEOBP and PPDC in the presence of tetraphenylphosphonium chloride (TPPC) in o‐dichlorobenzene at 130 °C for 24 h. The structure of the resulting polymer was confirmed with IR, ¹H NMR, and ³¹P NMR spectroscopy. Furthermore, it was proved that the polyaddition of certain bis(oxetane)s with phosphonic dichlorides proceeded smoothly to give corresponding polyphosphonates with TPPC as the catalyst. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3835–3846, 2002     

Rational Design of a Novel Intercalation System. Layer-Gap Control of Crystalline Coordination Polymers, {[Cu(CA)(H(2)O)(m)()](G)}(n)() (m = 2, G = 2,5-Dimethylpyrazine and Phenazine; m = 1, G = 1,2,3,4,6,7,8,9-Octahydrophenazine)

New copper(II) intercalation compounds, {[Cu(CA)(H(2)O)(2)](G)}(n)() (H(2)CA = chloranilic acid; G = 2,5-dimethylpyrazine (dmpyz) (1a and 1b) and phenazine (phz) (2)) have been synthesized and characterized. 1acrystallizes in the triclinic space group P&onemacr;, with a = 8.028(2) ?, b = 10.269(1) ?, c = 4.780(2) ?, alpha = 93.85(3) degrees, beta = 101.01(2) degrees, gamma = 90.04(3) degrees, and Z = 1. 1b crystallizes in the triclinic space group P&onemacr;, with a = 8.010(1) ?, b = 10.117(1) ?, c = 5.162(1) ?, alpha = 94.40(1) degrees, beta = 97.49(1) degrees, gamma = 112.64(1) degrees, and Z = 1. 2crystallizes in the triclinic space group P&onemacr;, with a = 8.071(1) ?, b = 11.266(1) ?, c = 4.991(1) ?, alpha = 97.80(1) degrees, beta = 99.58(1) degrees, gamma = 83.02(1) degrees, and Z = 1. For all the compounds, the crystal structures consist of one dimensional [Cu(CA)(H(2)O)(2)](m)() chains and uncoordinated guest molecules (G). Each copper atom for 1a, 1b, and 2 displays a six-coordinate geometry with the two bis-chelating CA(2)(-) anions and water molecules, providing an infinite, nearly coplanar linear chains running along the a-direction. Theses chains are linked by hydrogen bonds between the coordinated water and the oxygen atoms of CA(2)(-) on the adjacent chain, forming extended layers, which spread out along the ac-plane. The guest molecules are intercalated in between the {[Cu(CA)(H(2)O)(2)](k)()}(l)() layers, just like pillars, which are supported with N.H(2)O hydrogen bonding. The guest molecules are stacked each other with an interplanar distance of ca. 3.2 ? along the c-axis perpendicular to the [Cu(CA)(H(2)O)(2)](m)() chain. The EHMO band calculations of intercalated dmpyz and phz columns show an appreciable band dispersion of phz pi (b(2g) and b(3g)) and dmpyz pi (b(g)), indicative of the importance of planar pi structure for the formation of the intercalated structure. The distances of O-H---N (guest molecules) fall within the range 2.74-2.80 ?, insensitive to the guest, whereas the interlayer distances increase in the order 9.25 ? (1b), 10.24 ? (1a), and 11.03 ? (2). The degree in lengthening the distance correlates well with the size of a molecule, indicative of the stability of the 2-D sheet structure and the flexibility of the sheet packing. The magnetic susceptibilities were measured from 2 to 300 K and analyzed by a one-dimensional Heisenberg-exchange model to yield J = -1.83 cm(-)(1), g = 2.18 (1a), J = -0.39 cm(-)(1), g = 2.14 (1b), and J = -1.84 cm(-)(1), g = 2.18 (2). The absolute value of J is smaller than that value for [Cu(CA)](n)(), which has a planar ribbon structure suggesting that the magnetic orbital d(x)()()2(-)(y)()()2 is not parallel to the chloranilate plane. For comparison with phz another type of copper(II) coordination compound, {[Cu(CA)(H(2)O)](ohphz)}(n)() (ohphz = 1,2,3,4,6,7,8,9-octahydrophenazine (7)) has also been obtained. 7 crystallizes in the orthorhombic space group Cmcm with a = 7.601(2) ?, b = 13.884(2) ?, c = 17.676(4) ?, and Z = 4. Nonplanar ohphz molecules are in between [Cu(CA)(H(2)O)(2)](m)() chains with the N.H(2)O hydrogen bonding in a fashion parallel to the chain direction. The copper atom shows a five-coordinate square-pyramidal configuration with two CA and one water molecule, thus affording no hydrogen bonding links between chains, dissimilar to 1a, 1b, and 2. The magnetic susceptibilities yield J = -10.93 cm(-)(1) and g = 2.00, comparable to that of the four-coordinate [Cu(CA)](n)(). On this basis both hydrogen bonding and stack capability of a guest molecule is responsible for building the unique intercalated structure such as is seen in 1a, 1b, and 2.     

Preparation of uniform spherical aluminum hydrous oxide particles from acetylacetonato-aluminum solutions

Uniform spherical particles of amorphous aluminum hydrous oxide (0.45 m in diameter with a relative standard deviation of 0.09) were produced under a limited set of conditions in an aluminum sulfate/acetylacetone system at 100°C aged for 24 h. Grain-like crystalline -AlOOH particles (2.6 m in length with a relative standard deviation of 0.10) were also prepared in the absence of sulfate ions at 100°C for 42 h. Their morphology and size were sensitive to the total aluminum concentration, even though the initial pH was kept the same. The temperature dependence of the absorption spectra of acetylacetonato-aluminum complexes indicated their exothermic formation. These complexes release free aluminum ions at elevated temperatures, which subsequently hydrolyzed. The resulting polymerized hydroxo-aluminum species complexes with the sulfate ion act as precursors to particle formation.     

Contortisiliosides A–G: Isolation of Seven New Triterpene Bisdesmosides from Enterolobium contortisiliquum and Their Cytotoxic Activity

Seven new bisdesmosidic triterpene saponins, with up to eight monosaccharides, which were given the trivial names contortisiliosides A–G ( 1 – 7 ), were isolated from Enterolobium contortisiliquum. The structures of the new saponins were determined on the basis of extensive spectroscopic and chromatographic analyses of both intact and acid‐hydrolyzed compounds. The isolated saponins were evaluated for their cytotoxic activities against BAC1.2F5 mouse macrophages, EL‐4 mouse lymphoma cells, and L‐929 mouse fibroblasts. Whereas contortisiliosides A ( 1 ) and C ( 3 ) were moderately cytotoxic to both BAC1.2F5 macrophages and EL‐4 cells, and contortisiliosides D–G ( 4 – 7 ) did not show any apparent cytotoxic activities against the three cell lines, contortisilioside B ( 2 ) exhibited selective cytotoxic activity against BAC1.2F5 mouse macrophages, with an IC₅₀ value of 3.4 μM . The macrophage death caused by 2 was shown to be neither necrotic nor apoptosis‐inducing based on the unique morphological change of the killed cells, whose cytosols were transformed into large vacuoles, and according to the TUNEL assay.     

Substoichiometric and non-destructive determination of trace impurities in high-purity optical glasses by neutron activation analysis

A method of radioactivation analysis has been developed for the determination of 17 elements as impurities in high-purity optical glasses. The substoichiometric extraction of platinum with dithizone was studied and a simple procedure was proposed for the determination of platinum. Copper and manganese were also determined substoichiometrically by the extractions with dithizone and with thenoyltrifluoracetone, respectively. The non-destructive γ-ray spectrometry using a Ge(Li) detector has been applied for the determination of the other 14 elements (Ag, Co, Cr, Eu, Fe, Ir, Sc, Zn, Cs, Hf, Rb, Sb, Ta and Tb). Impurity elements at the ppb level were analysed by the proposed method and it is shown that the method is reliable for the determination of trace impurities in high-purity optical glasses.     

Catalytic reactions of oxetanes with protonic reagents and aprotic reagents leading to novel polymers

This paper reports new addition reactions of oxetanes with certain protonic reagents such as carboxylic acid, phenol, and thiol, and with certain aprotic reagents such as acyl chloride, thioester, phosphonyl dichloride, silyl chloride, and chloroformate using quaternary onium salts as catalysts. The kinetic study of the addition reactions of oxetanes was also investigated. These new addition reactions were applicable to the synthesis of new polymers. These polyaddition systems could also construct both polymer main chains and reactive side chains. The alternating copolymerization of oxetanes with carboxylic anhydride was performed. Furthermore, it was found that anionic ring‐opening polymerization of oxetanes containing hydroxy groups proceeded to afford the hyperbranched polymer (HBP) with an oxetanyl group and many hydroxy groups at the ends of the polymer chains. Alkali developable photofunctional HBPs were synthesized by the polyaddition of bis(oxetane)s or tris(oxetane)s, and their patterning properties were examined, too. The photo‐induced cationic polymerization of the polymers with pendant oxetanyl groups and the thermal curing reactions of polyfunctional oxetanes (oxetane resins) were also examined to give the crosslinking materials quantitatively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 709–726, 2007