Measurements of kineic parameters of inorganic pyrophosphatase by flow-injection procedures

Two flow-injection systems were designed for characterizing the enzymatic hydrolysis of pyrophosphate by inorganic pyrophosphatase (EC 3.6.1.1). By using a molybdenum(VI) reagent the selective determination of a product, orthophosphate, in the presence of pyrophosphate was made. An anion exchange column was employed for the simultaneous determination of both the substrate and the product with a molybdenum(V)/molybdenum(VI) reagent. The effects of magnesium concentration and reaction temperature on the enzyme activity were determined. The Michaelis constant and maximum velocity at 25°C and pH 7.2 were evaluated. K_m was ca. 3 μM.     

Flow pattern and pressure fluctuation in air-solid two-phase flow in a pipe at low air velocities

An experiment was made on an air-solid two-phase flow in a horizontal pipe. The main concern was the relation between flow patterns and pressure fluctuation at low air velocities. First, the flow patterns were classified into five different types depending on the air and particle flow rates. Next, it was shown how the properties of pressure fluctuation change as the air velocity decreases. Further, fluctuation signals were analyzed in detail and differences due to the flow patterns and particle size were discussed.     

Studies on suspension and emulsion. XXXV. Effect of epoxy groups at the surface layer of ethyl acrylate–glycidyl methacrylate copolymer emulsion particles on its crosslinking reactivity

The effect of epoxy groups at the surface layer of ethyl acrylate–glycidyl methacrylate copolymer (1) emulsion particles on its crosslinking reactivity has been investigated. For this purpose two series of I emulsions were prepared. In the Y series, of which emulsion particles have epoxy groups at the surface layer, the epoxy content in the polymerization recipe was varied. For preparing the X series, of which emulsion particles have few epoxy groups at the surface layer, the high epoxy content of a given emulsion was reduced by various degrees of cleavage reaction with HCl–CaCl₂. In emulsion blend films with amine-group-containing copolymer (II) emulsion, where the crosslinking reaction was expected to proceed only at the interfacial layer of I and II emulsion particles, the Y series, compared to the X series at the equal overall epoxy content in particles, showed less swelling and higher gel fraction in dioxane, less swelling in water, and higher tensile strength and modulus. On the other hand, this difference was not observed in the next two crosslinked films in which crosslinking was expected to be homogeneous. First, blends of I and II, which were isolated from the corresponding emulsions discussed above, were cast from dioxane solutions. Second, I emulsions were cast with BF₃ ether complex which was expected to penetrate into the particles. It is concluded that the response of I emulsion cleaving the epoxy groups at the surface layer of particles to subsequent interfacial crosslinking is obviously reduced. However, even such an emulsion can be crosslinked to an extent similar to that of an uncleaved emulsion with similar overall epoxy content, if the crosslinking reaction is conducted so as to give an homogeneous effect.     

Preparation and characterization of cyclic polystyrene with short poly(2‐tert‐butylbutadiene) sequences

A polystyrene‐block‐oligo(2‐tert‐butylbutadiene)‐block‐polystyrene triblock copolymer was prepared and cyclized by end‐to‐end ring closure. Ring‐shaped polystyrene‐block‐oligo(2‐tert‐butylbutadiene) was isolated from the coupling product via gel permeation chromatography (GPC) fractionation. The ring polymer was ozonized for decomposition of the oligo(2‐tert‐butylbutadiene) sequences selectively referring to the linear molecule. From GPC analysis of the decomposed products by ozonolysis, it was quantitatively confirmed that the fractionated product was 86% ring molecules. Single chain dimensions of the ring and linear molecules in a good solvent, benzene, and in a θ solvent, cyclohexane, were measured with small‐angle neutron scattering. The ratios of the radii of gyration, R_g(ring)/R_g(linear), were 0.780 in benzene and 0.789 in cyclohexane. These were compared with theoretically predicted values. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1582–1589, 2002     

Synthesis of bicyclo[6.2.2] bridgehead dienes

Bicyclo[6.2.2]dodecadienes ($\text{2}$), ($\text{3a}$), and ($\text{3b}$) having two bridgehead double bonds were synthesized by the pyrolysis of the acetate ($\text{1}$).     

A design of nanosized PEGylated-latex mixed polymer solution for microchip electrophoresis

We report here advanced microchip electrophoresis using a nanoparticle doped polymer solution that enables greater separation of DNA. The proposed system is simple and effective without any new apparatus or complicated procedures. Various amounts and sizes (80 nm, 110 nm, and 193 nm) of polymer nanoparticle solutions (PEGylated-latex) were mixed with a conventional polymer solution for microchip electrophoresis. When a 0.49 wt% hydroxyl propyl methyl cellulose (HPMC) buffer solution was mixed with a 2.25 wt% 80 nm-PEGylated-latex a higher separation efficiency and a higher mobility of a wider molecular range of dsDNA (10 bp to 2 kbp) was achieved under low viscosity conditions (<5.5 cP) than in conventional 0.7% HPMC. The separation performance was dependent on the particle size and concentration. Furthermore, the effectiveness of the larger PEGylated-latex (193 nm) was not as high as the smaller one (80 to 110 nm). The observed separation improvement by polymer solution with latex-nanoparticles seems to derive from the balance between wider polymer mesh size and the structural obstacles of particles in the buffer.     

Nano-Biodevice for Genomic Medicine and Systems Biology

Since human genome sequencing has been almost completed, human genome project will quickly move on to the post genome sequencing era, including single nucleotide polymorphism (SNP) analysis, functional genomics, mutation analysis, transeriptome analysis, proteome analy-