Rapid DNA hybridization analysis using a PDMS microfluidic sensor and a molecular beacon.

A rapid DNA analysis has been developed based on a fluorescence intensity change of a molecular beacon in a PDMS microfluidic channel. Recently, we reported a new analytical method of DNA hybridization involving a PDMS microfluidic sensor using fluorescence energy transfer (FRET). However, there are some limitations in its application to real DNA samples because the target DNA must be labelled with a suitable fluorescent dye. To resolve this problem, we have developed a new DNA microfluidic sensor using a molecular beacon. By monitoring the change in the restored fluorescence intensity along the channel length, it is possible to rapidly detect any hybridization of the molecular beacon to the target DNA. In this case, the target DNA does not need to be labelled. Our experimental results demonstrate that this microfluidic sensor using a molecular beacon is a promising diagnostic tool for rapid DNA hybridization analysis.     

Desorption behavior of a surfactant in a linear low‐density polyethylene blend at elevated temperatures

The desorption behavior of a surfactant in a linear low‐density polyethylene (LLDPE) blend at elevated temperatures of 50, 70, and 80 °C was studied with Fourier transform infrared spectroscopy. The composition of the LLDPE blend was 70:30 LLDPE/low‐density polyethylene. Three different specimens (II, III, and IV) were prepared with various compositions of a small molecular penetrant, sorbitan palmitate (SPAN‐40), and a migration controller, poly(ethylene acrylic acid) (EAA), in the LLDPE blend. The calculated diffusion coefficient (D) of SPAN‐40 in specimens II, III, and IV, between 50 and 80 °C, varied from 1.74 × 10^?11 to 6.79 × 10^?11 cm²/s, from 1.10 × 10^?11 to 5.75 × 10^?11 cm²/s, and from 0.58 × 10^?11 to 4.75 × 10^?11 cm²/s, respectively. In addition, the calculated activation energies (E_D) of specimens II, III, and IV, from the plotting of ln D versus 1/T between 50 and 80 °C, were 42.9, 52.7, and 65.6 kJ/mol, respectively. These values were different from those obtained between 25 and 50 °C and were believed to have been influenced by the interference of Tinuvin (a UV stabilizer) at elevated temperatures higher than 50 °C. Although the desorption rate of SPAN‐40 increased with the temperature and decreased with the EAA content, the observed spectral behavior did not depend on the temperature and time. For all specimens stored over 50 °C, the peak at 1739 cm^?1 decreased in a few days and subsequently increased with a peak shift toward 1730 cm^?1. This arose from the carbonyl stretching vibration of Tinuvin, possibly because of oxidation or degradation at elevated temperatures. In addition, the incorporation of EAA into the LLDPE blend suppressed the desorption rate of SPAN‐40 and retarded the appearance of the 1730 cm^?1 peak. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1114–1126, 2004     

Beam Combination using Stimulated Brillouin Scattering for the Ultimate High Power-Energy Laser System Operating at High Repetition Rate over 10 Hz for Laser Fusion Driver

After the laser was invented in 1960, a phase conjugation mirror has been respected to be the most fantastic one for the laser resonator composition because it can compensate any distortions of the laser beams occurred by the many inhomogenuities of the laser media and optical components. Among the many phase conjugation configurations, the stimulated Brillouin scattering phase conjugation mirror is the most simple one and many researchers have tried to utilize it to develop high power/energy laser systems. For realizing a high energy/power laser system the thermal problem is the most difficult to solve, and some researchers suggested a beam combination technique to reduce the thermal load of the big laser media to many small sized ones. To accomplish the beam combination using stimulated Brillouin scattering phase conjugation mirrors (SBS-PCMs), it is necessary to lock/control the phases of the SBS-PCMs. And some researchers have developed several ways for it, but they can lock the phases of a limited number of beams overlapped at the foci less than 5, or lock the phases by back-seeding technique but it loses the phase conjugation characteristics. For realization of the laser fusion driver, it is necessary to combine more than 10 or 100 beams. And the authors have developed recently a new phase controlling/locking technique which is isolated and independent totally from other beams and it can be applied to an unlimited number of beams in principle.     

Potential energy surfaces for HenNe+ ions: ab initio and diatomics-in-molecule results

The potential energy surface of He2Ne+ has been reinvestigated using a combination of ab initio and diatomics-in-molecule (DIM) calculations. In contrast to the reports of two recent studies the ion is found to have an asymmetric linear He-Ne-He structure, with no barrier to formation from the separated atoms on the ground-state surface. The He-Ne+ bond lengths at the potential minimum are 1.51 and 1.81 A, and the total bonding energy is 0.717 eV. Comparing the He2Ne+ energy to that of HeNe+, the bonding energy for the second helium atom is 0.06 eV, about 10% of that of the first He atom. The saddle point between the two equivalent minima is a symmetric structure, 0.0074 eV above the potential minimum. A symmetric geometry becomes the overall potential minimum if the 2s hole on the Ne is excluded from the reference states of a multireference configuration interaction calculation. A DIM potential was created for the HenNe+ family of ions. The DIM potential is consistent with the asymmetric He2Ne+ ion serving as a core; it predicts a slightly more asymmetric geometry than the ab initio results. Additional helium atoms form five-membered rings around the bonds of the core ion to fill the first shell and then add to the ends of the cluster. The asymmetric core ion and the highly compact structure help to account for the lack of apparent shell structure in the mass spectrometry of HenNe+ clusters. Finally, we recommend that the value De=0.63+/-0.04 eV be adopted for the ground state of HeNe+.     

Catalytic combustion of chlorobenzene over V2O5/TiO2 catalysts prepared by the precipitation-deposition method

Catalytic combustion of chlorobenzene over supported vanadium oxides has been investigated. TiO₂ was prepared by the sol-gel method from titanium isopropoxide. The supported vanadium oxide catalysts have been prepared by precipitation-deposition and impregnation method and characterized by XRD, FT-Raman and TPR. In the VO_x/TiO₂catalysts prepared using the impregnation method, when vanadium loading reaches 3 wt.%, the activity shows a maximum. However, in the VO_x/TiO₂catalysts prepared by precipitation-deposition, when vanadium loading reaches 7 wt.%, the activity shows a maximum. This result suggests that the precipitation-deposition can yield a higher metal loading on the support and a high dispersion compared to the impregnation method. This revised version was published online in August 2006 with corrections to the Cover Date.     

Direct observation of an intermediate state for a surface photochemical reaction initiated by hot electron transfer

The photoinduced charge transfer that had been suggested to result in the dissociation of phenol on Ag(111) was investigated by two-photon photoemission spectroscopy. An unoccupied intermediate state was positively identified, which was found to be located 3.22 eV above the Fermi level. From the photoelectron energy dispersion, the effective mass of the intermediate state was determined to be (15 +/- 10)m(e) for a 1 ML coverage of phenol. This implies that the excited electron is localized mainly on the adsorbed phenol, forming a molecular resonance state. Polarization dependence of the photoelectron intensity suggested that the initial photoexcitation of the substrate produces hot electrons that scatter into the molecular resonance state, leading ultimately to the dissociation of the adsorbate. These results are the first two-photon photoemission study to characterize the transient anionic state involved in photodissociation of a molecule adsorbed on a metal surface.     

Copolymerization of ethylene and 1-butene with highly active Ticl4/THF/Mgcl2, Ticl4/THF/Mgcl2/SiO2, and TiCl3.1/3AlCl3 catalysts

Highly active catalysts for copolymerization have been prepared by the precipitation of MgCl₂/ToCl₄ complex with or without high surface area silica. Copolymerization of ethylene and 1-butene has been tested by using the prepared catalysts at various concentrations of 1-butene. The catalytic activities are 20–80 kg/g Ti h. The rate of copolymerization is strongly affected by the addition of 1-butene. The decay rate of copolymerization is first order with respect to time. Analyses of copolymers with solvent extraction, DSC, IR, XRD, and NMR were performed. Ethylene reactivity ratio (k₁₁) for TiCl₄/MgCl₂/THF catalyst is calculated to be about 26 by NMR spectrum. © 1994 John Wiley & Sons, Inc.     

Formation of nanostructured polymer filaments in nanochannels

We describe the use of hard etching methods to create nanodimensional channels and their use as templates for the formation of polymer filament arrays with precise dimensional and orientational control in a single integrated step. The procedure is general as illustrated by the radical, coordination, and photochemical polymerizations that were performed in these nanochannels. The nanochannel templates (20 nm high, 20-200 nm wide, and 100 mum long) were fabricated by the combined use of electron-beam lithography and a sacrificial metal line etching technique. Radical polymerization of acrylates, metal-catalyzed polymerization of norbornene, and photochemical polymerization of 1,4-diiodothiophene were carried out in these nanochannels. The polymers grown follow the dimensions and orientation of the channels, and the polymer filaments can be released without breaking. The approach opens up the possibility of just-in-place manufacturing and processing of patterns and devices from nanostructured polymers using well-established polymer chemistry.     

Pattern generation of biological ligands on a biodegradable poly(glycolic acid) film

The micropatterns of biological ligands (biotin and RGD peptides) were generated on a flat surface of biodegradable polymer, poly(glycolic acid) (PGA). The immobilization of biological ligands onto the surface of biodegradable polymers (especially aliphatic polyesters) is usually hampered by the absence of functionalizable groups on the polymer backbone. We demonstrate herein that PGA polymer films were modified by surface hydrolysis to introduce carboxylic acid groups on the film surfaces, which were subsequently used for patterning amine-terminated ligands by microcontact printing. Fluorescence microscopy was used to verify the pattern of biotin on the surface of the PGA films after complexation with fluorescein-conjugated streptavidin. In addition, the cellular micropatterns were obtained from micropatterns of RGD peptides on the surface-hydrolyzed PGA films.