Preparation of low flow-resistant methacrylate-based monolithic stationary phases of different hydrophobicity and the application to rapid reversed-phase liquid chromatographic separation of alkylbenzenes at high flow rate and elevated temperature

Low flow-resistant alkyl methacrylate-based monolithic stationary phases of different hydrophobicity were constructed for reversed-phase capillary liquid chromatography by thermally initiated radical polymerization of respective methacrylate ester monomer with different alkyl chain (C2, C4, C6, C12, C18) and ethylene glycol dimethacrylate (EDMA) in a 250 microm i.d. fused silica capillary. The hydrophobicity was basically controlled by changing the length and/or the density of the alkyl-chain, while the composition and the ratio of porogenic solvent were adjusted to obtain highly permeable rigid monoliths with adequate column efficiency. Among the prepared monolithic stationary phases, C18-methacrylate monoliths polymerized from a binary porogenic solvent of isoamyl alcohol and 1,4-buthandiol exhibited the most promising performance in terms of hydraulic resistance and column efficiency. The pressure drops of 20-cm long monolithic columns were below approximately 0.4 MPa at a normal linear velocity of 1mm/s (a flow rate of 3 microL/min), and the numbers of theoretical plates for alkylbenzenes mostly exceeded 3000 plates/20 cm. The produced monolithic columns had good mechanical strength for high pressure and temperature, and could be properly operated even at a temperature of 80 degrees C and at a pressure of at least 33 MPa. At 80 degrees C, the theoretical plate numbers reached 6000 plates/20 cm because of the enhanced mass transfer. Due to the novel hydraulic resistance and mechanical strength, the separation time could be reduced 120-fold simply by raising the flow rate and column temperature.     

Free oscillator realization of Laguerre polynomials

Theoretical and Mathematical Physics - We revisit the radial oscillator from the standpoint of a free oscillator realization. By using a free oscillator, namely, the creation/annihilation operators...     

Eigensystem and full character formula of theW 1+∞ algebra withc = 1

By using the free field realizations, we analyze the representation theory of theW ₁₊ algebra withc = 1. The eigenvectors for the Cartan subalgebra ofW ₁₊ are parametrized by Young diagrams, and explicitly written down byW ₁₊ generators. Moreover, their eigenvalues and full character formula are also obtained.     

A sub-second, time-resolved, linear dichroism measurement system for visible attenuated total reflection spectroscopy with a slab optical waveguide

A sub-second, time-resolved, linear dichroism (LD) measurement system was constructed, fitted with a slab optical waveguide (SOWG), and utilized to observe the adsorption process of methylene blue (MB) onto silica surfaces. In the system, a semiconductor laser (670 nm) was used as the light source and the out-coupled beam from the SOWG was split by a polarizing beam splitter into two polarized beams (TE and TM modes) to allow sequential linear dichroic ratio data to be obtained; the acquisition rate was 11 data sets per second. For an MB solution that contained no sodium dodecylbenzenesulfonate (DBS), in contact with a bare silica surface, a clear decrease occurred in the average orientation angle of adsorbed MB in the initial stages of the adsorption process. This result may correspond to a change in the chemical form of MB from monomer to dimer.     

Development and optimization of a lab-on-a-chip device for the measurement of trace nitrogen dioxide gas in the atmosphere

We propose the use of lab-on-a-chip technology for measuring gaseous chemical pollutants, and describe the development of a microchip for the detection of nitrogen dioxide (NO2) in air. A microchip fabricated from quartz glass has been developed for handling the following three functions, gas absorption, chemical reaction and fluorescence detection. Channels constructed in the microchip were covered with porous glass plates, allowing nitrogen dioxide to penetrate into the triethanolamine (TEA) flowing within the microchannel beneath. The nitrogen dioxide was then mixed with TEA and reacted with a suitable fluorescence reagent in the chemical reaction chamber in the microchip. The reacted solution was then allowed to flow into the fluorescence detection area to be excited by an ultraviolet light-emitting diode (UV-LED), and the fluorescence was detected using a photomultiplier tube (PMT). The reaction time, reagent concentration, pH, flow rate and other measurement conditions were optimised for analysis of nitrogen dioxide in air. Preliminary studies with standardized test solutions revealed quantitative measurements of nitrite ion (NO2-), which corresponded to atmospheric nitrogen dioxide in the range of 10-80 ppbv.     

Design and synthesis of carboxylate inhibitors for matrix metalloproteinases

A series of carboxylate compounds were prepared from N(alpha)-substituted 2,3-diaminopropionic acid and were tested for efficacy as matrix metalloproteinase (MMP) inhibitors. During modeling of the initial compound 10a, we utilized three-dimensional structure modeling software (InsightII/Discover Ver. 2.98). Some of the prepared carboxylate derivatives, such as carbamate compounds (12c,d, 22) and sulfonamide compounds (14b,c), proved to be effective MMP-1 inhibitors (with IC50 values of a 10(-6) M order), depending on the substituent at the N(alpha)-position of 2,3-diaminopropionic acid. Some of them were also evaluated for inhibition of stromelysin-1 (MMP-3), and the sulfonamide compound 14c exceeded the lead compound 5b in its MMP-3 inhibitory potency. For the carbamate compounds, we investigated the minimum molecular size at which the MMP-1 inhibitory potency was maintained, and found that this was P3-P1' compound 10b.     

Highly sensitive and direct detection of DNA fragments using a laser-induced capillary vibration effect.

A pulsed laser-induced stationary wave capillary vibration detection method was applied to the sensitive detection of capillary gel electrophoresis, and the direct detection of non-labeled nucleic acids, such as DNA sequencing products, was demonstrated. An excimer laser operating at 248 nm was used as a CVL excitation source, and polynucleotides were sensitively detected without derivatization. From an investigation on the endurance of several matrixes to pulsed laser irradiation, a polyacrylamide without a cross-linker (0%C) was found to have adequate endurance, and it exhibited no serious damage during an analysis. A cytosine-terminated sequence reaction product was detected with a sensitivity close to that of laser-induced fluorometry (LIF). These results suggest the feasibility of the highly sensitive detection of ultramicro amounts of biological materials without a pre- or post-column derivatization, which has usually been required in sensitive detection procedures, such as LIF. Furthermore, the feasibility of a novel DNA sequencing method is also suggested.     

Infinitely many shape invariant potentials and new orthogonal polynomials

Three sets of exactly solvable one-dimensional quantum mechanical potentials are presented. These are shape invariant potentials obtained by deforming the radial oscillator and the trigonometric/hyperbolic Pöschl–Teller potentials in terms of their degree ℓ polynomial eigenfunctions. We present the entire eigenfunctions for these Hamiltonians (ℓ=1,2,…) in terms of new orthogonal polynomials. Two recently reported shape invariant potentials of Quesne and Gómez-Ullate et al.'s are the first members of these infinitely many potentials.     

Design and synthesis of sulfur based inhibitors of matrix metalloproteinase-1

Fibroblast collagenase (MMP-1), a member of the matrix metalloproteinases family, is believed to be a pathogenesis of arthritis, by cleaving triple-helical type II collagen in cartilage. From the similarity of the active site zinc binding mode with hydroxamate, we designed and synthesized alpha-mercaptocarbonyl possessing compounds (3-5), which incorporated various peptide sequences as enzyme recognition sites. The P4-P1 peptide incorporating compound (3) exhibited as potent inhibition as the hydroxamate (1) and the carboxylate (2) type inhibitors, with an IC50 of 10(-6) M order against MMP-1. But the inhibitor (3) related compounds (6-8) displayed decreased or no inhibitory potencies. These results suggest that the existence of both the carbonyl and thiol groups might be critical for the inhibition, and the distance between the two functional groups is important for inhibitory potency. For Pn' peptide incorporating compounds (4a-k), except for 4h and 4k, all compounds showed IC50 values under sub-nanomolar. Among them, for potent inhibition, Leu was better than Phe and Val as the P1' amino acid, and the P2' position amino acid was necessary, and preferentially Phe. Insertion of the Pn peptide into 4d or 4k, giving compounds 5a-c, did not increase the activities of 4d and 4k. Substitution of the mercapto group with other functional groups lost the activity of compound 4a. The stereochemical preference at the thiol-attached position was also determined by preparation of both isomers of 4a. It was found that the S configuration compound (36b) is approximately 100 times more potent than the corresponding R-isomer (36a).