A study of the alumina-silica gel adsorbent for the removal of silicic acid from geothermal water: increase in adsorption capacity of the adsorbent due to formation of amorphous aluminosilicate by adsorption of silicic acid

Two kinds of adsorbents (Si adsorbent and Al adsorbent) for the removal of silicic acid from geothermal water to retard the formation of silica scales were prepared using silicic acid contained in geothermal water. The Si adsorbent was prepared by evaporating geothermal water, and the Al adsorbent was prepared by evaporating geothermal water after the addition of aluminum chloride. The specific surface area of the Si adsorbent was small and it's adsorption capacity of silicic acid was low. Although the specific surface area of the Al adsorbent was also small, it was significantly increased by the adsorption of silicic acid and it's adsorption capacity was high. Based on the change in the local structure of aluminum ion by the adsorption of silicic acid, the Al adsorbent was considered to be silica particles covered with crystalline aluminum hydroxide. Moreover, it was concluded that the increase in the specific surface area of the Al adsorbent and the decrease in the zeta potential were due to the formation of an amorphous aluminosilicate with a large surface area and a negative charge (one 4-coordinated Al) by the reaction between aluminum ions and silicic acids.     

One-dimensional ion transport in self-organized columnar ionic liquids

New fan-shaped ionic liquids forming columnar liquid crystalline phases have been prepared to obtain one-dimensional ion-transporting materials. The ionic liquids consist of two incompatible parts: an imidazolium-based ionic part as an ion-conducting part and tris(alkyloxy)phenyl parts as insulating parts. Two compounds having octyl and dodecyl chains have been synthesized. Self-assembly of these materials leads to the formation of thermotropic hexagonal columnar liquid crystalline states at room temperature. Anisotropic one-dimensional ionic conductivities have been successfully measured by the cells having comb-shaped gold electrodes. The self-organized columns have been aligned macroscopically in two directions by shearing perpendicular and parallel to the electrodes. The ionic conductivities parallel to the column axis are higher than those perpendicular to the axis. The incorporation of lithium salts in these columnar materials leads to the enhancement of the ionic conductivities and their anisotropy. These materials would be useful for anisotropic transportation of ions at the nanometer level.     

Quantitative study of diffuse increased 99mTc-methylene diphosphonate accumulation of both kidneys

Patients with diffuse increased accumulation in both kidneys on 99mTc-MDP bone scintigram were evaluated quantitatively. Among 1,100 cases, 7 (0.63%) showed this finding. The accumulation density ratios of kidneys/lumbal vertebra in A/D exchanged images of these patients were compared with control group, so that these ratios of patient group were higher than control group statistically. In conclusion, the accumulation density ratio was made the index of diffuse increase accumulation in both kidneys on 99mTc-MDP bone scintigram.     

WAVELENGTH-DEPENDENT PROPERTIES OF PHOTOTAXIS IN LARVAE OF Bombyx mori

Phototactic responses of newly hatched silkworm larvae to monochromatic lights and their mixtures were measured to determine wavelength-dependent properties. Each fluence rate-response curve for a monochromatic light was composed of a log-linearly increasing part, a plateau and a decreasing part. Curves were classified into two groups according to the slopes of the linear parts: responses to UV-blue light (364-482 nm) and responses to green-red light (513-681 nm). Different plateau values were found for both groups. The action spectrum had its maximum at 557 nm and showed another large value at about 364 nm, and its minimum was at 447 nm. When green-orange lights (540-577 nm) were added to 557 nm, the silkworms were attracted more by the mixed lights than by the 557 nm component light only. Mixed lights of UV (364 nm) and blue (447 nm) attracted the silkworms more than either component. The magnitude of the response decreased remarkably when green light was mixed with U V or blue light. We conclude that the silkworm possesses colour vision and responds differently to green-red lights (≥ 513 nm) from UV-blue lights (≲ 482 nm).     

On the electronic character of localized singlet 2,2-dimethoxycyclopentane-1,3-diyl diradicals: substituent effects on the lifetime

Photodenitrogenation of the diazenes 4 affords exclusively the housanes 5 through intramolecular cyclization of the spectrally detected and characterized singlet diradicals 3. The lifetime of singlet diradical 3, determined by transient absorption measurements, depends on the Y and Z substituents at the para position of the phenyl ring and has the following order: Y, Z = OMe, OMe > OMe, CN > CN, CN > OMe, H > Cl, Cl approximately CN, H approximately Me, Me > H, H. This unprecedented substituent effect reveals stabilization of the singlet 2,2-dimethoxycyclopentane-1,3-diyl diradicals 3 through radical, zwitterionic, pi-bonding, and hyperconjugative structures.     

Encapsulation of doxorubicin into liposomes by a freeze-thawing method using buffer solution

When doxorubicin was encapsulated into liposomes by freeze-thawing, the percentage of encapsulated doxorubicin (EN%) was found to vary according to the type of buffer solution used. The reason for this was investigated in the present report. Drug-free liposomes prepared by hydration were mixed with doxorubicin dissolved in a certain type of buffer solution that shows a pH decrease on freezing, and this mixture was subjected to freeze-thawing. Doxorubicin was encapsulated by the liposomes due to the difference in pH between freezing and thawing. EN% depended on the pH of the buffer solution before freezing and increased significantly at over pH 7. About 60% of doxorubicin was encapsulated into liposomes after the Ist freeze-thawing cycle, and EN% was increased gradually with the number of freeze-thawing cycles. The addition of sugar to the experimental system was seen to affect doxorubicin encapsulation and the particle size of liposomes.     

Crystal Structure and Property of Perovskite-Type Oxides Containing Ion Vacancy

Studies on the role of oxygen vacancy in structural change of nonstoichiometric perovskites and a property of oxygen-deficient perovskite-related K₂NiF₄ compounds are reviewed.The structural changes on which the authors focused are cation ordering and lattice distortion. The relationship between the distortion and oxygen vacancy was investigated by comparing the structures of Sr₂(Sr_1-xM_x)TaO_6-d (M = Ca²⁺ and Nd³⁺) solid solutions. It was found that distortion of a perovskite-type lattice decreased with an increasing amount of oxygen vacancies. In order to investigate the relationship between the cation ordering on octahedral sites and oxygen vacancy, structures of stoichiometric Sr_2-xLa_xCo_1-yTa_1+yO₆ and oxygen-deficient Sr_2-xLa_xMg_1-yTa_1+yO_6-d solid solutions were compared. The authors' work reveals that the cation ordering affects the amount of oxygen vacancies in addition to cation charge and size.     

NLO‐active maleimide copolymers with ­high glass transition temperatures

We synthesized some novel rigid NLO‐active maleimide copolymers bearing DR‐1 moieties ( PMPD , PHSD and PHND ). All copolymers exhibited high T_g's (190～197 °C), good solubilities for common solvents and excellent film‐forming properties. Dependence of film thickness on the d₃₃ value for the poled copolymer films induced by corona poling was investigated and it was demonstrated that in less than thickness of 0.3 µm decrease of the thickness gives rise to remarkable increase in the d₃₃ value. The poled copolymer films exhibited large d₃₃ values (270 × 10^?9 esu (film thickness 0.13 µm) for PMPD , 290 × 10^?9 esu (0.12 µm) for PHSD and 350 × 10^?9 esu (0.08 µm) for PHND ) as well as large r₃₃ values (51.0 pmV^?1 for PMPD and 60.4 pmV^?1 for PHND ) which are significantly large compared to the value of LiNbO₃ (31 pmV^?1) as a typical EO material. The d₃₃ values of the poled copolymers were kept constant even after standing 1000h at 80 °C, although a small decrease was observed at an initial stage. Further, the d₃₃ values did not change up to ca. 123 °C upon heating at the rate of 10 °C/min in all cases. Copyright © 2002 John Wiley & Sons, Ltd.     

Manipulating the Through‐Space Spin–Spin Interaction of Organic Radicals in the Confined Cavity of a Self‐Assembled Cage

We show a new approach to manipulating the through‐space spin–spin interaction by utilizing the confined cavity of a self‐assembled M₆L₄ coordination cage. The coordination cage readily encapsulates stable organic radicals in solution, which brings the spin centers of the radicals closer to each other. In sharp contrast to the fact that the radical in solution in the absence of the cage is in a doublet state, in the presence of the cage through‐space spin–spin interaction is induced through cage‐encapsulation effects in solution as well as in the solid state, resulting in the triplet state of the complex. These results were confirmed by ESR spectroscopy and X‐ray crystallography. The quantity of triplet species generated by encapsulation in the cage increases with increasing affinity of the radicals to the cage. We estimated the affinity between several types of guests and the cage in solution by cyclic voltammetry. We also demonstrate that the through‐space interaction of organic radicals within the self‐assembled coordination cage can be controlled by external stimuli such as heat or pH.     

Assembly of Carbohydrates on a Nickel(II) Center by Utilizing N-Glycosidic Bond Formation with Tris(2-aminoethyl)amine (tren). Syntheses and Characterization of [Ni{N-(aldosyl)-tren}(H(2)O)](2+), [Ni{N,N'-bis(aldosyl)-tren}](2+) and [Ni{N,N',N"-tris(aldosyl)-tren}](2+)

Reactions of [Ni(tren)(H(2)O)(2)]X(2) (tren = tris(2-aminoethyl)amine; X = Cl (1a), Br (1b); X(2) = SO(4) (1c)) with mannose-type aldoses, having a 2,3-cis configuration (D-mannose and L-rhamnose), afforded {bis(N-aldosyl-2-aminoethyl)(2-aminoethyl)amine}nickel(II) complexes, [Ni(N,N'-(aldosyl)(2)-tren)]X(2) (aldosyl = D-mannosyl, X = Cl (2a), Br (2b), X(2) = SO(4) (2c); aldosyl = L-rhamnosyl, X(2) = SO(4) (3c)). The structure of 1c was confirmed by X-ray crystallography to be a mononuclear [Ni(II)N(4)O(2)] complex with the tren acting as a tetradentate ligand (1c.2H(2)O: orthorhombic, Pbca, a = 15.988(2) ?, b = 18.826(4) ?, c = 10.359(4) ?, V = 3118 ?(3), Z = 8, R = 0.047, and R(w) = 0.042). Complexes 2a,c and 3c were characterized by X-ray analyses to have a mononuclear octahedral Ni(II) structure ligated by a hexadentate N-glycoside ligand, bis(N-aldosyl-2-aminoethyl)(2-aminoethyl)amine (2a.CH(3)OH: orthorhombic, P2(1)2(1)2(1), a = 16.005(3) ?, b = 20.095(4) ?, c = 8.361(1) ?, V = 2689 ?(3), Z = 4, R = 0.040, and R(w) = 0.027. 2c.3CH(3)OH: orthorhombic, P2(1)2(1)2(1), a = 14.93(2) ?, b = 21.823(8) ?, c = 9.746(2) ?, V = 3176 ?(3), Z = 4, R = 0.075, and R(w) = 0.080. 3c.3CH(3)OH: orthorhombic, P2(1)2(1)2(1), a = 14.560(4) ?, b = 21.694(5) ?, c = 9.786(2) ?, V = 3091 ?(3), Z = 4, R = 0.072, and R(w) = 0.079). The sugar part of the complex involves novel intramolecular sugar-sugar hydrogen bondings around the metal center. The similar reaction with D-glucose, D-glucosamine, and D-galactosamine, having a 2,3-trans configuration, resulted in the formation of a mono(sugar) complex, [Ni(N-(aldosyl)-tren)(H(2)O)(2)]Cl(2) (aldosyl = D-glucosyl (4b), 2-amino-2-deoxy-D-glucosyl (5a), and 2-amino-2-deoxy-D-galactosyl (5b)), instead of a bis(sugar) complex. The hydrogen bondings between the sugar moieties as observed in 2 and 3 should be responsible for the assembly of two sugar molecules on the metal center. Reactions of tris(N-aldosyl-2-aminoethyl)amine with nickel(II) salts gave the tris(sugar) complexes, [Ni(N,N',N"-(aldosyl)(3)-tren)]X(2) (aldosyl = D-mannosyl, X = Cl (6a), Br (6b); L-rhamnosyl, X = Cl (7a), Br (7b); D-glucosyl, X = Cl (9); maltosyl, X = Br (10); and melibiosyl, X = Br (11)), which were assumed to have a shuttle-type C(3) symmetrical structure with Delta helical configuration for D-type aldoses on the basis of circular dichroism and (13)C NMR spectra. When tris(N-rhamnosyl)-tren was reacted with NiSO(4).6H(2)O at low temperature, a labile neutral complex, [Ni(N,N',N"-(L-rhamnosyl)(3)-tren)(SO(4))] (8), was successfully isolated and characterized by X-ray crystallography, in which three sugar moieties are anchored only at the N atom of the C-1 position (8.3CH(3)OH.H(2)O: orthorhombic, P2(1)2(1)2(1), a = 16.035(4) ?, b = 16.670(7) ?, c = 15.38(1) ?, V = 4111 ?(3), Z = 4, R = 0.084, and R(w) = 0.068). Complex 8 could be regarded as an intermediate species toward the C(3) symmetrical tris(sugar) complexes 7, and in fact, it was readily transformed to 7b by an action of BaBr(2).