Measurement of mobile-phase volume in reversed-phase liquid chromatography and evaluation of the composition of liquid layer formed by solvation of packing materials

The mobile-phase volumes (Vm) in reversed-phase liquid chromatography (RPLC) with alkyl-bonded silica, defined as the difference between the total volume of eluent in the column (V0) and the volume of the eluent solvent layer formed by solvation of the bonded phase (VL), are determined by the method derived from the eluent electrolyte effect on the retention of ionic analytes. The validity of the Vm values obtained is evaluated by comparing them with the retention volumes of various organic compounds and inorganic ions, which have been suggested as unretained markers, and those obtained from a linear dependence of the logarithmic retention factor on the carbon numbers of homologous series. From the results obtained, it has been concluded that the solvated liquid phase on a column packing material should be assigned to a part of the stationary phase and the method developed for determination of the Vm value based on the ion partition model gives the most reasonable value as the mobile-phase volume in RPLC. The volume and the solvent composition of the solvated liquid phase on C1, C8, and C18 bonded silica are estimated, and the effects of organic modifiers and the physicochemical structures of the packing materials on these values are discussed.     

Convenient preparative method for lactones from 3-hydroxy propanoic acids using iodine under solvent-free conditions

Intramolecular cyclization of 3-hydroxy acids was investigated using iodine as a catalyst under solvent-free conditions. The reaction proceeded to completion in the heterogeneous system. Lactones were obtained by intramolecular cyclization of 3-hydroxy acids. Propella lactone (11-oxatricyclo[4.4.3.0(1,6)]tridecan-12-one) was conveniently synthesized from 3-hydroxy acid ((6-hydroxyspiro[4.5]dec-6-yl)acetic acid) in 88% yield with carbon skeleton rearrangement. Spiro lactones and bicyclic lactones were also obtained from the corresponding 3-hydroxy acids in yields of over 75%. The most suitable reaction conditions were a temperature of 80 degrees C, a molar ratio of 3-hydroxy acid:iodine = 1:0.1, and a time period of 6 h. In addition, terpenic lactones were efficiently synthesized from the corresponding 3-hydroxy acids, derived from (+)-camphor, (-)-fencone, and (-)-pulegone, with skeleton rearrangement. The yield of the solvent-free reaction was as high as that of the corresponding reaction in solution.     

Engineering of alpha1-antitrypsin variants selective for subtilisin-like proprotein convertases PACE4 and PC6: importance of the P2' residue in stable complex formation of the serpin with proprotein convertase

Furin and PACE4, members of the subtilisin-like proprotein convertase (SPC) family, have been implicated in the metastatic progression of certain tumors in addition to the activation of viral coat proteins and bacterial toxins, indicating that these enzymes are potential targets for therapeutic agents. Alpha1-Antitrypsin Portland is an engineered alpha1-antitrypsin designed as a furin-specific inhibitor and has been used as a tool in the functional analysis of furin. In this work, we engineered rat alpha1-antitrypsin to create a PACE4-specific inhibitor. Substituting Arg-Arg-Arg-Arg for Ala-Val-Pro-Met(352) at P4-P1 and Ala for Leu(354) at P2' created a potent PACE4- and PC6-specific inhibitor. This variant (RRRRSA) formed an SDS- and heat-stable serpin/proteinase complex with PACE4 or PC6 and inhibited both enzyme activities. The RRRRSA variant was efficiently cleaved by furin without formation of the stable complex. This is the first report of a highly selective protein-based inhibitor of PACE4 and PC6. This inhibitor will be useful in delineating the roles of PACE4 and PC6 localized in the extracellular matrix.     

Perspectives on molecular computing

In 1996, we began a research project on molecular computers under the new program “Research for the Future” funded by the Japan Society for the Promotion of Science. In this paper, we first summarize the research that has been completed in the field of DNA computing and the research problems that must be overcome. We also report some achievements of our research project in the first two years. We then propose a new direction in research towardsautonomous molecular computers, and describe the author’s work on the implementation of state machines using DNA molecules. We finally discuss the future perspectives on molecular computing based on our experiences. Masami Hagiya, Ph.D.: He received M.Sc. from University of Tokyo in 1982, and D.Sc. from Kyoto University in 1988. After the years in Research Institute for Mathematical Sciences, Kyoto University, he returned to University of Tokyo in 1992. He has been working on programming languages, verification and synthesis of programs, and automated deduction. In addition, he is interested in bio-computing since he was involved in the human genome project of Japan. He is currently organizing a project on molecular computing under the “Research for the Future” program of JSPS.     

Pollution control of actual flue gas using pulsed power at a thermal power plant

There are several important environmental problems in the world. One of them is acid rain caused by combustion flue gases from thermal power plants, factories, and automobiles. Different kinds of gas discharges, such as surface discharge, dc and ac corona discharge, silent discharge, and electron beam controlled discharge, have been studied for the removal of NO_x and SO₂ from flue gases. The recent development of repetitive pulsed power generators gives the pulsed steamer corona discharges a chance of success in the removal of NO_x and SO₂. In this paper, the experimental results of NO_x and SO₂ removal by a repetitive pulse power generator are described. The actual flue gas at a thermal power plant was used. It is shown that about 90% of the NO was removed at a flow rate of 0.8 liters/min and a repetition rate of 7 pps. © 2001 Scripta Technica, Electr Eng Jpn, 134(4): 28–35, 2001     

Cationic polymerization of β-pinene with the AlCl3/SbCl3 binary catalyst: Comparison with α-pinene polymerization

The polymerization of β-pinene with the AlCl₃/SbCl₃ binary catalyst was investigated in toluene at −40°C and was compared with that of α-pinene. The polymerization of β-pinene with AlCl₃ alone was very rapid and retarded on addition of SbCl₃, in sharp contrast to that of α-pinene where added SbCl₃ remarkably accelerated it to give relatively high molecular weight oligomers. Attempted copolymerization of the two isomers with the binary catalyst, in turn, induced their parallel homopolymerizations, indicating that the copolymerization was difficult due to the large difference in reactivity. The homopolymerizations with AlCl₃/SbCl₃ were not seriously affected by a sterically hindered base, 2,6-di-tert-butyl-4-methylpyridine (DTBMP); the initiating species, therefore, would be different in nature from a proton. © 1996 John Wiley & Sons, Inc.     

L1 synthesis of a static output controller for positive systems by LMI iteration

An approach to find a static output feedback gain that makes the feedback system positive and minimizes the L₁ gain is proposed. The problem of finding a static output feedback gain has 3 aspects: stabilizing the system, making the system positive, and then minimizing the L₁ gain. Each subproblem is described by bilinear matrix inequality with respect to the feedback gain and the Lyapunov matrix or vector. Linear matrix inequality (LMI) that is sufficient to satisfy bilinear matrix inequality is derived using a convex‐concave decomposition, and the feedback gain sequence is calculated by an iterative solution of LMI. The sequence of the upper bounds on the design parameter is guaranteed to be monotonically nonincreasing for each algorithm. Similarly, 2 other LMIs are derived for each subproblem using another convex‐concave decomposition and PK iteration. The effectiveness of these algorithms is illustrated via several numerical examples.