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.     

A discontinuous Galerkin method for the Cahn-Hilliard equation

The Cahn-Hilliard equation is modeled to describe the dynamics of phase separation in glass and polymer systems. A priori error estimates for the Cahn-Hilliard equation have been studied by the authors. In order to control accuracy of approximate solutions, a posteriori error estimation of the Cahn-Hilliard equation is obtained by discontinuous Galerkin method.     

Ultraviolet cavity ringdown spectra and the S1(n,pi) ring-inversion potential energy function for 2-cyclohexen-1-one-d0 and Its 2,6,6-d3 isotopomer

The cavity ringdown spectra of 2-cyclohexen-1-one (2CHO) and its 2,6,6-d3 isotopomer (2CHO-d3) have been recorded in the spectral region near their S1(n,pi)<--S0 band origins which are at 26,081.3 and 26,075.3 cm-1, respectively. The data allow several of the quantum states of nu39, the ring inversion, to be determined for both the ground and excited electronic states. These were utilized to calculate the one-dimensional potential energy functions which best fit the data. The barriers to inversion for the S0 and S1(n,pi) states were found to be 1,900 +/- 300 and 3,550 +/- 500 cm-1, respectively. Density functional theory calculations predict values of 2,090 and 2,265 cm-1, respectively.     

Flash vacuum pyrolysis of 1-propynoylpyrazoles: a new precursor of tricarbon monoxide

Pyrolysis of 3,5-dimethyl-1-propynoylpyrazole (1) at 640°C/0.1 torr gives 2-methyl-1$\text{H}$-pyrazolo[2,3-a]pyridin-5-one (3) with inversion of the propynoyl chain. 1-Ethynylpyrazole and tricarbon monoxide have been identified in pyrolysates formed at 700–1000°C/0.01–0.1 torr from the parent 1-propynoylpyrazole (4).     

The dual-site alternating cyclocopolymerization of 1,3-butadiene with ethylene

The copolymerization of ethylene with 1,3-butadiene was studied with the series of ansa-metallocenes Me2Si(Cp)(9-Flu)ZrCl2 (1), Me2Si(1-Ind)(9-Flu)ZrCl2 (2), and Me2Si(9-Flu)2ZrCl2 (3) with methylaluminoxane (MAO) as cocatalyst. The catalyst 2/MAO yields a cyclocopolymer composed of two ethylene monomer units for every one butadiene in a novel periodic architecture of 1,2-enchained cyclopentane units separated by three methylenes. The high butadiene content in the copolymer and the high selectivity for alternating cyclocopolymerization to form methylene-1,2-cyclopentane units implicate a dual-site mechanism where butadiene and ethylene are enchained at different coordination sites.     

Macrodasine A, a novel macroline derivative incorporating fused spirocyclic tetrahydrofuran rings containing a spiroacetal moiety

A novel indole alkaloid, viz., macrodasine A, incorporating fused spirocyclic tetrahydrofuran rings onto a macroline-like moiety, was obtained from a Malayan Alstonia species. The structure, which is also notable for the presence of an unprecedented spiroacetal moiety in an indole alkaloid, was established by spectroscopic analysis.     

A theoretical investigation into the conformational changes of dibenzo-p-dioxin, thianthrene, and selenanthrene

Theoretical ab initio calculations using the HF and B3LYP methods have been carried out to investigate the conformational differences of three cyclic rings, dibenzo-p-dioxin (DPD), thianthrene (THT), and selenanthrene (SET). The physical origin for the conformational preference of each molecule has been studied using the natural bond orbital (NBO) analysis. The NBO results indicate that DPD exists in a planar form due to strong electron delocalization caused by the specific orbital interaction, around the X atom. On the other hand, THT and SET exist as puckered forms with high inversion barriers due to less effective electron delocalization. The NBO analysis also shows that the conformational stabilization in DPD is caused by a more effective overlap of the orbitals, compared with the overlap of the orbitals in THT.     

Kopsifolines A–F: a New Structural Class of Monoterpenoid Indole Alkaloids from Kopsia

Six new indole alkaloids, named kopsifolines A–F ( 1 – 6 ), with an unprecedented hexacyclic carbon skeleton, constituting a new structural group of monoterpenoid indole alkaloids, were obtained from the leaf extract of a Malayan Kopsia species, and their structures were established by spectroscopic analysis.     

Unusual spirocyclic macroline alkaloids, nitrogenous derivatives, and a cytotoxic bisindole from Alstonia

The bark extract of the Malayan A. macrophylla provided several novel indoles with unprecedented carbon skeletons, an unusual nitrogenous compound, a cytotoxic bisindole, several new macroline alkaloids, in addition to other known alkaloids. The structures of the new compounds were established by spectroscopic analysis.     

Morphological investigation of polylactide/microfibrillated cellulose composites

Optical microscopy and transmission electron microscopy have been used to investigate the morphology of polylactide (PLA)/microfibrillated cellulose (MFC) composites prepared by: compression molding of wet-comingled MFC and PLA latex or powder, twin-screw extrusion of the wet-comingled compounds, and solvent mixing of PLA with MFC or acetylated MFC. Compression molding of wet-comingled MFC and PLA latex or powder compounds resulted in a cellular MFC network, whereas solvent-cast films showed a more uniform dispersion of MFC fibers. Somewhat lower aggregate diameters observed in the acetylated MFC were assumed to be due to decreased MFC hydrophilicity and improved chemical affinity with the PLA matrix. The MFC networks in the commingled compounds were severely disrupted after twin-screw extrusion. This confirmed the limited deformability of the networks inferred from the extensive syneresis during the initial compression molding step, and accounted for substantial losses in stiffness reinforcement by the MFC after extrusion.