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.     

Arg-72 of pharaonis phoborhodopsin (sensory rhodopsin II) is important for the maintenance of the protein structure in the solubilized states

In bacteriorhodopsin (bR), Arg-82bR has been proven to be a very important residue for functional role of this light-driven proton pump. The arginine residue at this position is a super-conserved residue among archaeal rhodopsins. pharaonis phoborhodopsin (ppR; or called as "pharaonis sensory rhodopsin II") has its absorption maximum at 498 nm and acts as a sensor in the membrane of Natronobacterium pharaonis, mediating the negative phototaxis from the light of wavelength shorter than 520 nm. To investigate the role of the arginine residue (Arg-72ppR) of ppR corresponding to Arg-82bR, mutants whose Arg-72ppR was replaced by alanine (R72A), lysine (R72K), glutamine (R72Q) and serine (R72S) were prepared. These mutants were unstable in low concentrations of NaCl and lost their color gradually when the proteins were solubilized with 0.1% n-dodecyl-beta-D-maltoside. The order of instability was R72S > R72A > R72K > R72Q > the wild type. The rates of denaturation were reduced in a solution of high concentrations of monovalent anions.     

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.     

Stereospecific polymerization of isobutyl vinyl ether. III. Polymerization with VCl3 • LiCl

The polymerization of isobutyl vinyl ether by vanadium trichloride in n-heptane was studied. VCl₃ ? LiCl was prepared by the reduction of VCl₄ with stoichiometric amounts of BuLi. This type of catalyst induces stereospecific polymerization of isobutyl vinyl ether without the action of trialkyl aluminum to an isotactic polymer when a rise in temperature during the polymerization was depressed by cooling. It is suggested that the cause of the stereospecific polymerization might be due to the catalyst structure in which LiCl coexists with VCl₃, namely, VCl₃ ? LiCl or VCl₂ ? 2LiCl as a solid solution in the crystalline lattice, since VCl₃ prepared by thermal decomposition of VCl₄ and a commercial VCl₃ did not produce the crystalline polymer and soluble catalysts such as VCl₄ in heptane and VCl₃ ? LiCl in ether solution did not yield the stereospecific polymer. It was found that some additives, such as tetrahydrofuran or ethylene glycol diphenyl ether, to the catalyst increased the stereospecific polymerization activity of the catalysts. Influence of the polymerization conditions such as temperature, time, monomer and catalyst concentrations, and the kind of solvent on the formed polymer was also examined.     

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).     

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.     

Nmr spectroscopic studies on the tautomerism in tenuazonic acid analogs

Nmr spectra of structural analogs of tenuazonic acid such as 3-acetyltetramic acid, 3-acetyltetronic acid, 3-acetylthiotetronic acid and others were investigated for elucidation of the tautomeric structures. These compounds have completely enolized β,β′-triketone systems, and the position of the nmr signals for the enolic proton shows that the strength of their intramolecular hydrogen-bonding is weaker than those of acyclic β,β′-triketones and six-membered cyclic triketones. The assignment was made for nmr signals split by the difference of the diamagnetic anisotropic effect in each tautomers. The percentages of each of the tautomers were calculated from the intensities of the corresponding nmr signals. The results were confirmed by means of ¹³C-nmr spectroscopy.     

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.