Online transient isotachophoresis concentration by the pseudo-terminating electrolyte buffer for the separation of DNA-aptamer and its thrombin complex in poly(methyl methacrylate) microchip

Online automatic transient isotachophoresis concentration of DNA-aptamer and its thrombin complex by using one kind of pseudo-terminating electrolyte buffer in a cross-channel poly(methyl methacrylate) microchip is reported. Sample injection, transient concentration and separation were done continuously and controlled by a sequential voltage switching program, time-consuming steps and complicated chip design were not required. Peak resolution between DNA-aptamer and its thrombin complex was influenced by this novel pseudo-terminating electrolyte buffer, which was prepared by the addition of chemical component with slow mobility into the same buffer as leading electrolyte buffer. 1100-fold signal enhancement of thrombin complex was achieved by this transient isotachophoresis on a standard cross-form microchip. The concentration effect or standing time of transient isotachophoresis was proved to be influenced by the concentration of leading electrolyte ion and the concentration of pseudo-terminating electrolyte buffer ion (glycine). The transient concentration was followed by on-chip nondenaturing gel electrophoresis in methylcellulose solution for the size-based separation. The detection limit, taken as the lowest thrombin concentration at threefold S/N, was determined to be 0.5 amol in mass by this method.     

Scalar and vector meson propagation in asymmetric nuclear matter

The propagation of the scalar (σ and δ) and vector (ω and ρ) mesons in an iso-asymmetric nuclear matter is studied in detail, using the Walecka model. We calculate the invariant masses and spectral functions of the mesons, including the effect of meson mixing. At finite density, the mixing effect is quite important in the propagation of the scalar and (longitudinal) vector mesons. In the σ channel, we find a three-peak structure in the spectral function, caused by the mixing effect.     

Estimation methodology for amplitude of second-order harmonic in nonlinear surface acoustic wave measured by optical diffraction method

An estimation methodology for amplitude from the fundamental to fourth-order harmonic composed of nonlinear surface acoustic waves on a LiNbO₃ substrate with a 128° Y-X propagation axis was demonstrated. First, equations for estimation of amplitudes from diffracted light intensity were shown and then numerical simulations of main factors were carried out. Normalized diffraction light intensities due to components of nonlinear surface acoustic waves were measured and their amplitudes were obtained from measured values. Finally, the amplitude of the second harmonic propagating on a gold thin film of about 50 nm thickness was estimated. It was found that the amplitude of the second harmonic increased continuously from 0.8 to 2.0 Å with propagation distance in the thin film.     

The Effects of pH and Ionic Strength on the Aggregation of Bacteriochlorophyll c in Aqueous Organic Media: The Possibility of Two Kinds of Aggregates

The aggregation behavior of two homologs of bacteriochlorophyll c (BChl c) in various media was investigated for the effects of pH and salt, and the corresponding structures were analyzed by Fourier transform (FT)-IR spectroscopy. R-[P, E] BChl c_F (3¹-R-form of BChl c with a propyl group at the C-8 position and an ethyl group at the C-12 position) and R-[E, E] BChl c_F (3¹-R-form of BChl c with two ethyl groups at positions C-8 and C-12) were isolated from the green sulfur bacterium Chloro-bium limicola. Aggregates of each homolog showed a pH-dependent shift of the absorption maximum; at low pH, the peak moved to the red. This tendency was also revealed by circular dichroic spectra. A similar red shift of the peak was also induced by a high concentration of salt (NaCl) or buffer for both homologs. The FT-IR spectrum indicates that at low pH, both homologs formed a rather amorphous aggregate. On the other hand, a regular structure of R-[P, E] BChl c_F was indicated in an acetone-water mixture. This structure was stabilized by a triangular interaction among three pigment molecules through the Mg-OH (3>) O = C (13¹) linkage. This structure was not found for R-[E, E] BChl c_F. These results indicate that the replacement of the side chain at the C-8 position on the macrocycle induces a change in aggregation behavior. A possible heterogeneity of the in vivo rod structure of chlorosomes in green sulfur bacteria is discussed based on the above results.     

Discrimination of ethylene/vinyl acetate copolymers with different composition and prediction of the content of vinyl acetate in the copolymers and their melting points by near-infrared spectroscopy and chemometrics

Near-infrared (NIR) diffuse reflectance spectra have been measured by use of a rotating drawer for pellets of 12 kinds of ethylene/vinyl acetate (EVA) copolymers with vinyl acetate (VA, the comonomer) varying in the 7–44 wt % range. They are unambiguously discriminated from one another by a score plot of the principal component analysis (PCA) Factor 1 and 2, based upon the NIR spectra pretreated by multiplicative scatter correction (MSC). Principal component (PC) weight loadings for Factor 1 show that the discrimination relies largely upon bands due to the overtone and combination modes arising from the VA unit. We have found one “outlier” in the score plot and elucidated its spectral characteristics based upon PC weight loadings for Factor 2. Partial least-squares (PLS) regression has been applied to propose calibration models which predict the VA content in EVA. The models have been prepared for three kinds of pretreatment, the first derivative, the second derivative, and MSC; and four kinds of wavelength regions. The NIR spectra in the 1100–2200 nm region after the MSC treatment has given the best correlation coefficient and standard error of prediction (SEP) of 0.998 and 0.70%, respectively. The calibration models, prepared by NIR diffuse reflectance spectroscopy for the pellet samples, are compared with previously reported models by NIR transmission spectroscopy for the flowing molten samples, and with those by Raman spectroscopy for the pellet samples. PLS regression has also allowed us to predict melting points of the copolymers with the correlation coefficient and SEP of 0.997 and 0.78°C, respectively. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1529–1537, 1998     

Potential of two-dimensional near-infrared correlation spectroscopy in studies of pre-melting behavior of nylon 12

This review paper discusses the potential of generalized two-dimensional (2D) near-infrared (NIR) correlation spectroscopy in studies of pre-melting behavior and hydrogen bonds of nylon 12. A 2D NIR study on dissociation and hydrogen bonds of N-methylacetamide (NMA) is also reviewed here as a model compound study of nylon 12. Fourier transform (FT)-NIR spectra in the region of 9000–5000 cm⁻¹ of nylon 12 were measured over a temperature range of 30–150°C where gradual weakening of inter- or intramolecular associative interactions and decrease of local order leading to the eventual fusion of nylon 12 crystals are observed. The 2D correlation analysis provided the following conclusions for the pre-melting behavior of nylon 12. (i) There are at least eight bands in the 6800–6100 cm⁻¹ region assignable to free- and hydrogen-bonded NH groups of nylon 12 in various environments. The asynchronous 2D correlation spectrum in the above region indicates that the amide groups with free carbonyl oxygen appear first and then the unassociated free amide and amide groups with free NH follow as the temperature is increased. (ii) The asynchronous spectrum in the 6000–5500 cm⁻¹ region, where the first overtones of the CH₂ stretching modes are expected to appear, indicates that substantial amount of disordered or dissociated components start appearing before the disappearance of more ordered components. It seems that they appear as the pre-melting precursors (or even possibly as the indirect cause) to the precipitous decrease of the ordered components associated with melting of nylon 12 occurring at a much higher temperature.     

Developments of GNSS buoy for a synthetic geohazard monitoring system

A global navigation satellite system (GNSS) buoy system for early tsunami warnings has been developed for more than 20 years. The first GNSS buoy system using a real-time kinematic algorithm (RTK) was implemented in the Nationwide Ocean Wave information network for Ports and HArbourS (NOWPHAS) wave monitoring system in Japan in 2008. The records of NOWPHAS were used to update the tsunami alert by the Japan Meteorological Agency (JMA), owing to the tsunami generated by the 2011 Tohoku-oki earthquake (Mw9.0). However, considering that the distance limit is less than 20 km for the RTK algorithm, a new system was designed by introducing a new positioning algorithm and satellite data transmission to place the buoy much farther from the coast. A new technique for the continuous monitoring of ocean-bottom crustal movements was also implemented in the new system. The new buoy system can be used for weather forecasting and ionospheric monitoring as well.     

In situ Raman and optical microscopy of the relaxation behavior of amorphous ices under pressure

The transformation of low‐density amorphous (LDA) ice produced from high‐density amorphous (HDA) ice was studied up to 400 MPa as a function of temperature by in situ Raman spectroscopy and optical microscopy. Changes in these amorphous states of H₂O were directly tracked without using emulsions to just above the crystallization temperature T_x. The spectra show significant changes occurring above ∼125 K. The results are compared with data reported for the relaxation behavior of HDA, to form what we call relaxed HDA, or rHDA. We find a close connection with expanded HDA (eHDA), which is reported to exist as another metastable form in this P–T region. The observation of this temperature‐induced LDA transition under pressure complements the previously observed pressure‐induced reversible transition between LDA and HDA at 120–140 K. Copyright © 2009 John Wiley & Sons, Ltd.     

A Significant Two-Dimensional Structural Transformation in a Coordination Polymer that Changes Its Electronic and Protonic Behavior

A 2D-to-2D (2D: two-dimensional) structural transformation accompanying significant bond rearrangement and coordination environment change is demonstrated in a coordination polymer (CP) comprised of copper(II) ions and terephthalate (BDC²⁻) ligands for the first time. When immersed in water, a free-standing membrane of 2D Cu(BDC)(DMF) ( Cu-1 ; DMF: N,N-dimethylformamide) transforms into 2D Cu(BDC)(H₂O)₂ ( Cu-2 ) while maintaining its highly oriented layered structure. In the 2D sheet, paddlewheel-type Cu^II dimers coordinated with four bidentate BDC ligands in a square-planar array in Cu-1 were released to form uniform aqua-bridged Cu^II chains, which are cross-linked with each other by unidentate BDC ligands, in Cu-2 . The present facile approach to implement the 2D-to-2D transformation accompanied by bond rearrangement, which is characteristic of CPs, leads to a marked increase in in-plane magnetic susceptibility and proton conductivity. In situ experiments in support of theoretical calculations unveiled the energy diagram that governs the unique structural transformation.