Microscopic measurements of deformation of liquid surfaces induced by localized direct current electric field.

This study presents a new microscopic method for the measurements of the deformation of liquid surfaces induced by a localized direct current (dc) electric field in a noncontact manner. Since the dielectric constant of aqueous and organic liquids is larger than that of air, the liquids tend to occupy a space with a stronger electric field. The horizontal level of transparent surfaces was measured with a constructed microscopic system that possessed a resolution of about 2 microm. When a rod electrode (2.0 mm in radius) was brought near to a liquid surface vertically within 150 - 200 microm and a dc voltage (50 - 75 V) was applied, the surface just under the electrode rose by 4 - 19 microm. The deformation of the liquid surfaces was quantitatively analyzed by using a dielectric force, surface tension, and hydrostatic pressure.     

Direct determination of bromine in plastics by electrothermal vaporization/inductively coupled plasma mass spectrometry using a tungsten boat furnace vaporizer and an exchangeable sample cuvette system

A tungsten boat furnace vaporization inductively coupled plasma mass spectrometry (TBF/ICP‐MS) method has been applied to the direct determination of bromine in plastic samples. In the pretreatment, the plastic sample is spread over a small sample cuvette made of tungsten by treating it with a strongly basic organic solution, e.g., octanol or diisobutyl ketone in the presence of potassium hydroxide. The cuvette is placed on a tungsten boat furnace, with which the electrothermal vaporizer is equipped. At the vaporization step, a widely spread thin layer of the sample facilitates its efficient evaporation and introduction into an ICP mass spectrometer. The most remarkable feature is that all the bromine species in plastic samples are decomposed to form a thermally stable inorganic salt during the pretreatment procedure. Therefore, the bromine content in plastic samples can be measured by a calibration curve method constructed with an aqueous standard solution of potassium bromate(V). The detection limit (3σ) was estimated to be 0.77 pg of bromine, which corresponds to a concentration of 0.31 ng g^?1 of bromine in plastic samples when a sample amount taken of 2.5 mg is studied. The relative standard deviation was calculated to be 2.2%. Analytical results of some plastic samples, which contained both inorganic bromide salts and also organic bromine species, are given. Copyright © 2010 John Wiley & Sons, Ltd.     

On the morphological similarities between networklike structures in viscoelastic polymer systems and the large-scale structure of the universe

Networklike structures are observed in various materials and nature. The networklike structures in viscoelastic phase separation of polymer mixtures have been explained by a model with a couple of hydrodynamic equations. On the other hand, the large-scale structure of the universe has been explained by a multi-dimensional extension of the Burgers equation. The networklike structures of the two very different systems have some morphological similarities. To see origins of the similarities and differences, the Burgers equation is derived from the model of the polymer mixtures using several approximations. The meaning of the approximations is discussed in connection with the morphology.     

Synthesis and structure activity relationship studies of benzothieno[3,2-b]furan derivatives as a novel class of IKKbeta inhibitors

As a novel class of IKKbeta inhibitors, a series of tricyclic furan derivatives was designed and synthesized based on the structure of known thiophene IKKbeta inhibitors. Among the various fused furan derivatives synthesized, a benzothieno[3,2-b]furan derivative 13a displayed potent inhibitory activity towards IKKbeta in enzymatic and cellular assays. The potent inhibitory activity originates from an intramolecular non-bonded S...O interaction which was confirmed by the X-ray structure of JNK3 with 16k. The introduction of further substituents on the core structure led to the discovery of the 6-alkoxy derivatives, which possessed a comparable IKKbeta inhibitory activity to 13a and an improved metabolic stability. Among these, appropriately lipophilic compounds 16a, h, i, and 13g (log D>2) were found to possess good oral bioavailability.     

Luminol Chemiluminescence with Heteropoly Acids and its Application to the Determination of Arsenate,Germanate, Phosphate and Silicate by Ion Chromatography

A flow-injection chemiluminescence (CL) method has been proposed for sensitive determination of arsenate, germanate, phosphate and silicate, after separation by ion chromatography (IC). The post-column detection system involved formation of heteropoly acid in a H₂SO₄ medium before the CL reaction with luminol in an NaOH medium. For separation, heteropoly acid formation and the CL detection reaction, pH requirements were not compatible. When present as a heteropoly acid complex with molybdenum(VI), ger- manium(IV) and silicon(IV) caused CL emission from oxidation of luminol, and such a CL oxidation of luminol was observed analogously for arsenic(V) and phosphorus(V) but with the addition of metavanadate ion to the acid solution of molybdate. Good sensitivity for the three analytes arsenic(V), ger- manium(IV) and phosphorus(V) could be given by a single set of reagent conditions, chosen carefully. Another set was suitable for determining phosphorus(V) and silicon(IV). The minimum detectable concentrations of arsenic(V), germanium(IV), phosphorus(V) and silicon(IV) were 10, 50, 1 and 10 μg l⁻¹, respectively. Linear calibrations for arsenic(V), germanium(IV), phosphorus(V) and silicon(IV) were established over the respective concentration ranges of 10–1000, 50–25000, 1–1000 and 50–1 μg l⁻¹. The proposed IC–CL method was successfully applied to analyses of a seaweed reference material, rice wine and water samples.     

Loop effects in the Ising spin glass on the Bethe-like lattices

Equations for the spin glass order in the Ising spin glass model on the Bethe-like lattices with and without small loops are studied. For each lattice, equations are obtained by using and not using the replica method. Within the replica symmetric approximation, equations obtained by the two ways are shown to be identical. To see the effects of the small loops and the replica symmetry breaking, a spin glass order parameter is investigated as a function of the connectivity of the lattices close to the transition temperature. Replica symmetry breaking is enhanced by the existence of small loops.     

Sensitive determination of bromine and iodine in aqueous and biological samples by electrothermal vaporization inductively coupled plasma mass spectrometry using tetramethylammonium hydroxide as a chemical modifier

A procedure for the simultaneous determination of bromine and iodine by inductively coupled plasma (ICP) mass spectrometry was investigated. In order to prevent the decrease in the ionization efficiencies of bromine and iodine atoms caused by the introduction of water mist, electrothermal vaporization was used for sample introduction into the ICP mass spectrometer. To prevent loss of analytes during the drying process, a small amount of tetramethylammonium hydroxide solution was placed as a chemical modifier into the tungsten boat furnace. After evaporation of the solvent, the analytes instantly vaporized and were then introduced into the ICP ion source to detect the (79)Br(+), (81)Br(+), and (127)I(+) ions. By using this system, detection limits of 0.77 pg and 0.086 pg were achieved for bromine and iodine, respectively. These values correspond to 8.1 pg mL(-1) and 0.91 pg mL(-1) of the aqueous bromide and iodide ion concentrations, respectively, for a sampling volume of 95 microL. The relative standard deviations for eight replicate measurements were 2.2% and 2.8% for 20 pg of bromine and 2 pg of iodine, respectively. Approximately 25 batches were vaporizable per hour. The method was successfully applied to the analysis of various certified reference materials and practical situations as biological and aqueous samples. There is further potential for the simultaneous determination of fluorine and chlorine.     

Cation Effect on Formation of Preyssler‐type 30‐Tungsto‐5‐phosphate: Enhanced Yield of Na‐encapsulated Derivative and Direct Synthesis of Ca‐ and Bi‐Encapsulated Derivatives

The effect of cations in a reaction mixture for the preparation of the Preyssler‐Jeannin‐Pope type 30‐tungsto‐5‐phosphate [P₅W₃₀O₁₁₀Na]^14– is investigated. Reaction of phosphate and tungstate with a P/W ratio of ca. 3.9 in an acidic aqueous solution without cations selectively leads to the Dawson‐type 18‐tungsto‐2‐phosphate, [P₂W₁₈O₆₂]^6–. Amongst all the alkali cations, only Na⁺ allows formation of the Preyssler‐type polyanion [P₅W₃₀O₁₁₀Na]^14–, with an encapsulated Na⁺ ion, and the product yield can be improved by increasing Na⁺ amount. The presence of Li⁺ ions instead results in the Dawson‐type polyanion [P₂W₁₈O₆₂]^6–, whereas K⁺, Rb⁺, and Cs⁺ selectively result in the Keggin‐type polyanion [PW₁₂O₄₀]^3–. An improved synthetic procedure for the Na⁺‐encapsulated Preyssler‐ion leading to a higher isolated yield is presented. Furthermore, addition of Ca²⁺ and Bi³⁺ compounds allows formation of the Ca²⁺‐ and Bi³⁺‐encapsulated Preyssler‐type polyanions, [P₅W₃₀O₁₁₀Ca]^13– and [P₅W₃₀O₁₁₀Bi]^12–, respectively. Furthermore, single‐crystal XRD structure of the Bi³⁺‐encapsulated Preyssler‐type polyanions, [P₅W₃₀O₁₁₀Bi]^12–, is presented for the first time.     

Separate vaporisation of boric acid and inorganic boron from tungsten sample cuvette-tungsten boat furnace followed by the detection of boron species by inductively coupled plasma mass spectrometry and atomic emission spectrometry (ICP-MS and ICP-AES)

Utilising extremely different vaporisation properties of boron compounds, the determination procedures of volatile boric acid and total boron using tungsten boat furnace (TBF) ICP-MS and TBF-ICP-AES have been investigated. For the determination of volatile boric acid by TBF-ICP-MS, tetramethylammonium hydroxide (TMAH, Me₄NOH) was used as a chemical modifier to retain it during drying and ashing stages. As for the total boron, not only non-volatile inorganic boron such as boron nitride (BN), boron carbide (B₄C), etc. but also boric acid (B(OH)₃) was decomposed by a furnace-fusion digestion with NaOH to produce sodium salt of boron, a suitable species for the electrothermal vaporisation (ETV) procedure. The proposed method was applied to the analysis of various standard reference materials. The analytical results for various biological and steel samples are described.     

In situ measurements of emission transition dipole moment of individual ordered microdomain of diprotonated tetraphenylporphine aggregate formed at dodecane/aqueous H<Subscript>2</Subscript>SO<Subscript>4</Subscript> interface

Rhombic-ordered microdomains of diprotonated 5,10,15,20-tetraphenylporphine aggregate, whose sizes were 10–200 μm, were formed at dodecane/aqueous H₂SO₄ interfaces. The light excitation of their two absorption bands (410 and 473 nm for H- and J-bands, respectively) led to one fluorescence band at longer wavelength (723 nm). The direction of the emission transition dipole moment (μ _e) of individual rhombic microdomains, determined with an in situ optical microscope and a linear polarizer, was almost parallel to the major axis, which was also almost parallel to the direction of the absorption transition dipole moment of their J-bands. Their absorption and emission transition scheme was proposed.