Onset of Buoyancy-Driven Convection in a Liquid-Saturated Cylindrical Anisotropic Porous Layer Supported by a Gas Phase

A theoretical analysis of convective instability driven by buoyancy forces under the transient concentration fields is conducted in an initially quiescent, liquid-saturated, and anisotropic cylindrical porous layer supported by a gas phase. Darcy’s law and Boussinesq approximation are used to explain the characteristics of fluid motion, and linear stability theory is employed to predict the onset of buoyancy-driven motion. Under the quasi-steady-state approximation, the stability equations are derived in a similar boundary layer coordinate and solved by the numerical shooting method. The critical $Ra_D$ is determined as a function of the anisotropy ratio. Also, the onset time and corresponding wavelength are obtained for the various anisotropic ratios. The onset time becomes smaller with increasing $Ra_D$ and follows the asymptotic relation derived in the infinite horizontal porous layer. Anisotropy effect makes the system more stable by suppressing the vertical velocity.     

Cu(II)-catalyzed asymmetric hydrosilylation of diaryl- and aryl heteroaryl ketones: application in the enantioselective synthesis of orphenadrine and neobenodine

With certain amounts of sodium tert-butoxide and tert-butanol as additives, catalytic amounts of an inexpensive and easy-to-handle copper source Cu(OAc)(2)?H(2)O, a commercially available and air-stable non-racemic dipyridylphosphine ligand, as well as the stoichiometric desirable hydride donor polymethylhydrosiloxane (PMHS), formed a versatile in situ catalyst system for the enantioselective reduction of a broad spectrum of prochiral diaryl and aryl heteroarylketones in air, in high yields and with good to excellent enantioselectivities (up to 96?%). In particular, the practical viability of this process was evinced by its successful applications in the asymmetric synthesis of optically enriched potent antihistaminic drugs orphenadrine and neobenodine.     

Extended implementation of canonical transformation theory: parallelization and a new level-shifted condition

The canonical transformation (CT) theory has been developed as a multireference electronic structure method to compute high-level dynamic correlation on top of a large active space reference treated with the ab initio density matrix renormalization group method. This article describes a parallelized algorithm and implementation of the CT theory to handle large computational demands of the CT calculation, which has the same scaling as the coupled cluster singles and doubles theory. To stabilize the iterative solution of the CT method, a modification to the CT amplitude equation is introduced with the inclusion of a level shift parameter. The level-shifted condition has been found to effectively remove a type of intruder state that arises in the linear equations of CT and to address the discontinuity problems in the potential energy curves observed in the previous CT studies.     

The development of direct multicolour fluorescence cross-correlation spectroscopy: towards a new tool for tracking complex biomolecular events in real-time

Direct three-colour fluorescence cross-correlation spectroscopy can reveal interactions between three fluorescently labelled biomolecules, giving insight toward the complex events that constitute signal transduction pathways. Here we provide the optical and theoretical basis for this technology and demonstrate its ability to detect specific biological associations between nanoparticle-labelled DNA molecules.     

Magnetically-actuated blood filter unit attachable to pre-made biochips

We present a novel blood filter unit that is designed to separate blood plasma from whole blood by simple magnetic actuation. A non-diluted blood sample is dropped into the filter unit and magnetic attraction is applied to squeeze out only blood plasma while blood particles are filtered by membranes stacked in the filter unit. The new filter device yields good filtering performance with nearly perfect filtering efficiency (～99.999%), high plasma recovery (～30%), low blood consumption (<50 μl), and fast operation (～1 min). Because it is simple to operate and is attachable to any kind of pre-made biochip, it has commercial potential in various lab-on-a-chip applications for blood tests.     

Mitigation of signal suppression caused by the use of trifluoroacetic acid in liquid chromatography mobile phases during liquid chromatography/mass spectrometry analysis via post-column addition of ammonium hydroxide

A method has been developed to reduce the mass spectrometric ion signal suppression associated with the use of TFA as an additive in LC mobile phases. Through post-column infusion of diluted NH(4)OH solution to LC eluents, the ammonium ion introduced causes the neutral analyte-TFA ion pair to dissociate which consequently releases the protonated analyte as free ions into the gas phase (through regular electrospray ionization mechanisms). An ion signal improvement from 1.2 to 20 times for a variety of compounds had been achieved through the application of this method. The molar ratios of NH(4)OH:TFA which result in a reduction of signal suppression were determined to be between 0.5:1 and 50:1. In addition, it was shown that this NH(4)OH infusion method could reduce the level of doubly-charged species and the product ions formed via in-source collision. The use of diluted NH(4)OH solution is favorable since it is compatible with mass spectrometry analysis, and it is applicable in both positive and negative-ion generation mode.     

Simultaneous strain and temperature measurement based on a photonic crystal fiber modal-interference interacting with a long period fiber grating

An alternative all-fiber sensor for simultaneous strain and temperature measurement based on a photonic crystal fiber (PCF) spliced between single-mode fibers cascaded with a long period grating (LPG) is proposed. By collapsing the air holes at two splicing regions along the PCF, a simple but effective modal-interference (MI) is occurred between the core and cladding modes of the PCF. Due to the different responses on the changes of strain and temperature on the MI and the cascaded LPG, the strain and temperature can be measured simultaneously. Experimental results show that the sensing resolution of 9.1 με in strain measurement is experimentally achieved over a range of 2640 με, while the temperature sensing resolution is 0.27 °C within a range of 30-100 °C.     

Phenylethanoid glycosides isolated from Paraboea paniculata

Phytochemical studies of the leaves and rhizomes of Paraboea pa niculata (Gesneriaceae) are reported for the first time. Three phenylethanoid glycosides were isolated and characterized as 3,4-dihydroxyphenethyl-(3"-O-beta-D-apiofuranosyl)-beta-D-glucopyranoside, calceoralarioside E, and acteoside. These isolates exhibited weak cytotoxic activity against the K-562 cell line with a 50% of cell killing rate of 40.18 microM, 27.05 microM, and 27.24 microM, respectively. In the DPPH free radical scavenging assay, their IC50 values were determined as 75.89 microM, 25.00 microM, and 26.04 microM, respectively.