Reconfigurable T-junction DNA Origami

DNA self-assembly allows the construction of nanometre-scale structures and devices. Structures with thousands of unique components are routinely assembled in good yield. Experimental progress has been rapid, based largely on empirical design rules. Herein, we demonstrate a DNA origami technique designed as a model system with which to explore the mechanism of assembly. The origami fold is controlled through single-stranded loops embedded in a double-stranded DNA template and is programmed by a set of double-stranded linkers that specify pairwise interactions between loop sequences. Assembly is via T-junctions formed by hybridization of single-stranded overhangs on the linkers with the loops. The sequence of loops on the template and the set of interaction rules embodied in the linkers can be reconfigured with ease. We show that a set of just two interaction rules can be used to assemble simple T-junction origami motifs and that assembly can be performed at room temperature.     

Detection of enantiomers in dissymmetric biaryls with chiral shift reagents

Methoxycarbonyl groups in racemic biphenyls show separation of the methyl proton magnetic resonance signals in the presence of large amounts of chiral shift reagents.     

Chemistry of benzo[b] furan IV.. Chemical behaviour of furo[3,4-b] -benzofuran and synthesis of 4-Arylbenzofuro[2,3-d] pyridazines

Furo[3,2-b]benzofuran was demonstrated to be an intermediate for the synthesis of dibenzofuran and 1,4-epoxy-1,4-dihydrodibenzofuran ring systems. Starting from the readily available aryl 3-bromomethyl-2-benzo[b]furyl ketones, a method was developed for the synthesis of 4-arylbenzofuro[2,3-d]pyridazines.     

Kinetic spectrophotometric determination of trace amounts of palladium by whole kinetic curve and a fixed time method using resazurine sulfide reaction

The univariate and multivariate calibration methods were applied for the determination of trace amounts of palladium based on the catalytic effect on the reaction between resazurine and sulfide. The decrease in absorbance of resazurine at 602 nm over a fixed time is proportional to the concentration of palladium over the range of 10.0-160.0 ng mL(-1). The calibration matrix for partial least squares (PLS) regression was designed with 14 samples. Orthogonal signal correction (OSC) is a preprocessing technique used for removing the information unrelated to the target variables based on constrained principal component analysis. OSC is a suitable preprocessing method for PLS calibration without loss of prediction ability using spectrophotometric method. The root mean square error of prediction (RMSEP) for palladium determination with fixed-time, PLS and OSC-PLS were 3.71, 2.84 and 0.68, respectively. This procedure allows the determination of palladium in synthetic and real samples with good reliability of the determination.     

An integrated CMOS high voltage supply for lab-on-a-chip systems

Electrophoresis is a mainstay of lab-on-a-chip (LOC) implementations of molecular biology procedures and is the basis of many medical diagnostics. High voltage (HV) power supplies are necessary in electrophoresis instruments and are a significant part of the overall system cost. This cost of instrumentation is a significant impediment to making LOC technologies more widely available. We believe one approach to overcoming this problem is to use microelectronic technology (complementary metal-oxide semiconductor, CMOS) to generate and control the HV. We present a CMOS-based chip (3 mm x 2.9 mm) that generates high voltages (hundreds of volts), switches HV outputs, and is powered by a 5 V input supply (total power of 28 mW) while being controlled using a standard computer serial interface. Microchip electrophoresis with laser induced fluorescence (LIF) detection is implemented using this HV CMOS chip. With the other advancements made in the LOC community (e.g. micro-fluidic and optical devices), these CMOS chips may ultimately enable 'true' LOC solutions where essentially all the microfluidics, photonics and electronics are on a single chip.     

Tandem Behaviour of a Telecommunication System with Repeated Calls: A Markovian Case with Buffers

The performance of a telecommunication system consisting of a set of transmitters with finite capacity buffers is modelled with a Markovian queueing network, and its tandem behaviour is approximated, in steady state. In this system, a fraction of the units which, at the instants of their arrival at each transmitter, find it busy may retry to be processed by merging with the incoming arrival units at the same transmitter after a fixed delay time. The performance of this system is approximated by a recursive algorithm, in steady state. Furthermore, the approximation outcomes are compared against those from a simulation study. In summary, our numerical results indicate that approximating the non-renewal superposition arrival, the non-renewal overflow and the non-renewal departure processes at each node of the network can be approximated with compatible Poisson processes.     

A characterization of the finite simple group L<Subscript>16</Subscript>(2) by its prime graph

In this paper as the main result we prove that the projective special linear group L ₁₆(2) is uniquely determined by its prime graph. In fact we give a positive answer to an open problem arose in Zavarnitsin (Algebra Logic 43(4), 220–231, 2006) and we obtain a first example of a finite group with connected prime graph which is uniquely determined by its prime graph. This research was in part supported by a grant from IPM (No. 86200023).     

Transetherification of Allylic and Benzylic Ethers in the Presence of Ferric Ion

Alcoholysis of allylic, secondary and tertiary benzylic ethers is proceeded efficiently in the presence of catalytic amounts of ferric ion as anhydrous FeCl₃ and Fe(ClO₄)₃.     

Release Profiles of Tricalcium Phosphate Nanoparticles from Poly(L‐lactic acid) Electrospun Scaffolds with Single Component,Core–Sheath,or Porous Fiber Morphologies: Effects on hASC Viability and Osteogenic Differentiation

Functional PLA scaffolds are created with single component, core–sheath, or porous fiber morphology and doped with TCP nanoparticles to study the release profiles for use in bone tissue engineering applications. Pharmacokinetic analyses are performed for the three different nanofibrous structures after doping with TCP. Results indicate that single component and porous fiber scaffolds exhibit an initial‐burst release profile whereas core–sheath fibers show a steady release. All scaffolds are then seeded with human adipose‐derived stem cells (hASC), which remain viable and continue proliferation on all nanofibrous morphologies for up to 21 d. Osteogenic differentiation of hASC and cell‐mediated calcium accretion are largest on porous fibers.