Multiplexed single-molecule flow-stretching bead assay for DNA enzymology

Single-molecule techniques have been used successfully to visualize real-time enzymatic activities, revealing transient complex properties and heterogeneity of various biological events. Especially, conventional force spectroscopy including optical tweezers and magnetic tweezers has been widely used to monitor change in DNA length by enzymes with high spatiotemporal resolutions of similar to nanometers and similar to milliseconds. However, DNA metabolism results from coordination of a number of components during the processes, requiring efficient monitoring of a complex of proteins catalyzing DNA substrates. In this min-review, we will introduce a simple and multiplexed single-molecule assay to detect DNA substrates catalyzed by enzymes with high-throughput data collection. We conclude with a perspective of possible directions that enhance capability of the assay to reveal complex biological events with higher resolution.11Ysciescopuskc

Dynamics of the molecular orientation field coupled to ions in two-dimensional ferroelectric liquid crystals

Molecular orientation fluctuations in ferroelectric smectic liquid crystals produce space charges, due to the divergence of the spontaneous polarization. These space charges interact with mobile ions, so that one must consider the coupled dynamics of the orientation and ionic degrees of freedom. Previous theory and light scattering experiments on thin free-standing films of ferroelectric liquid crystals have not included this coupling, possibly invalidating their quantitative conclusions. We consider the most important case of very slow ionic dynamics, compared to rapid orientational fluctuations, and focus on the use of a short electric field pulse to quench orientational fluctuations. We find that the resulting change in scattered light intensity must include a term due to the quasistatic ionic configuration, which has previously been ignored. In addition to developing the general theory, we present a simple model to demonstrate the role of this added term

Optimisation of treatment of cancer based on principles of pharmacokinetics

The main hypothesis of this research project was that optimisation of treatment based on pharmacokinetic principles is on its own a powerful approach in improvement of treatment outcomes. This work therefore focused on optimisation of treatment of cancer based on principles of pharmacokinetics using two main approaches 1) lipophilic prodrug approach to specifically target the intestinal lymphatic system following oral administration and 2) identification of orally bioavailable candidate anticancer agents and biopharmaceutical development to increase the bioavailability for sufficient systemic exposure to the drug. The first approach was the prodrug derivatisation to take advantage of the physiological process of intestinal lymphatic transport in order to deliver anticancer agents to the mesenteric lymph nodes. Similar prodrug approaches have been researched by other groups but the main focus previously was on increasing the overall bioavailability where they mostly used long-chain or triglyceride mimetic prodrug moieties. However, in this project, through a series of stability and chylomicron association studies, it was revealed that activated ester prodrugs are the most suitable forms for yielding high concentrations of active drugs in the mesenteric lymph nodes. It was remarkable that using this novel approach significantly higher concentrations of the active drugs were achievable in the intestinal lymphatics without affecting the systemic exposure. The second approach taken in this PhD project was achieving sufficient systemic exposure of anticancer agents by identification of orally bioavailable candidate and improvement of oral bioavailability by biopharmaceutical development. The candidates with promising pharmacokinetic properties were rank-ordered by application of a rational drug discovery and development approach of integrated in vitro-in silico assessments. Following in vivo confirmation studies, oral bioavailability was further enhanced for a compound that exhibited a double-peak phenomenon. The results of the two approaches indicate that pharmacokinetic optimisation can be useful in development of anticancer agents to improve the treatment outcomes of cancer

Behavior of Connections Between SHS Columns & W-section Beams

Connections between SHS (Square Hollow Section) columns and W-section beams are generally fabricated by welding with or without endplates in the factory. These welded connections possess some finite degree of rotational stiffness which falls between fully rigid and ideally pinned joints. The influence of partially restrained connections on structural response not only changes the moment distribution but also increases frame drift. In this paper, a series of connection tests joining SHS column and W-section beam were executed and the test results compared with theoretical values. A method to utilize nonlinear moment-rotation relations of beam-to-column connections in steel framed structures is proposed. For the problem of contact in endplate-type connections, a simple and efficient method is also introduced

PAGaN I: Multi-Frequency Polarimetry of AGN Jets with KVN

Active Galactic Nuclei (AGN) with bright radio jets offer the opportunity to study the structure of and physical conditions in relativistic outflows. For such studies, multi-frequency polarimetric very long baseline interferometric (VLBI) observations are important as they directly probe particle densities, magnetic field geometries, and several other parameters. We present results from first-epoch data obtained by the Korean VLBI Network (KVN) within the frame of the Plasma Physics of Active Galactic Nuclei (PAGaN) project. We observed seven radio-bright nearby AGN at frequencies of 22, 43, 86, and 129 GHz in dual polarization mode. Our observations constrain apparent brightness temperatures of jet components and radio cores in our sample to $>10^{8.01}$ K and $>10^{9.86}$ K, respectively. Degrees of linear polarization $m_{L}$ are relatively low overall: less than 10%. This indicates suppression of polarization by strong turbulence in the jets. We found an exceptionally high degree of polarization in a jet component of BL Lac at 43 GHz, with $m_{L} \sim$ 40%. Assuming a transverse shock front propagating downstream along the jet, the shock front being almost parallel to the line of sight can explain the high degree of polarization.Comment: 14 pages, 17 figures, 4 tables. To appear in JKAS (received 2015 July 27; accepted 2015 October 25). Note the PAGaN II companion paper by J. Oh et a