Reducing a DNA molecule's translocation speed in a solid-state nanopore is a key step toward rapid single molecule identification. Here we demonstrate that DNA translocation speeds can be reduced by an order of magnitude over previous results. By controlling the electrolyte temperature, salt concentration, viscosity, and the electrical bias voltage across the nanopore, we obtain a 3 base/micros translocation speed for 3 kbp double-stranded DNA in a 4-8 nm diameter silicon nitride pore. Our results also indicate that the ionic conductivity inside such a nanopore is smaller than it is in bulk.

Time-resolved x-ray spectra from solid targets irradiated by the VULCAN Petawatt laser focused to 1020Wcm−2 show that material at solid density is heated to temperatures above 500 eV to a depth of about 15 μm and for a duration of more than 30 ps. Modeling with the implicit hybrid plasma code LSP shows that the heating is sensitive to the laser prepulse through resistive inhibition of the laser accelerated electrons in the blow off layer.

Experiments have been conducted using laser-driven cylindrical hohlraums whose walls are machined from Ta2O5 foams of 100 mg/cc and 4 g/cc densities. Measurements of the radiation temperature demonstrate that the lower density walls produce higher radiation temperatures than the high density walls. This is the first experimental demonstration of the prediction that this would occur [M. D. Rosen and J. H. Hammer, Phys. Rev. E 72, 056403 (2005)10.1103/PhysRevE.72.056403]. For high density walls, the radiation front propagates subsonically, and part of the absorbed energy is wasted by the flow kinetic energy. For the lower wall density, the front velocity is supersonic and can devote almost all of the absorbed energy to heating the wall.

The Rayleigh-Taylor instability is an important limitation in inertial confinement fusion capsule designs. Significant work both theoretically and experimentally has been done to demonstrate the stabilizing effects of material flow through the unstable region. The experimental verification has been done predominantly in planar geometry. Convergent geometry introduces effects not present in planar geometry such as shell thickening and accelerationless growth of modal amplitudes ͑e.g., Bell-Plesset growth͒. Amplitude thresholds for the nonlinear regime are reduced, since the wavelength of a mode m decreases with convergence ϳR/m, where R is the radius. Convergent effects have been investigated using an imploding cylinder driven by x-ray ablation on the NOVA laser ͓J. L. Emmet, W. F. Krupke, and J. B. Trenholme, Sov. J. Quantum Electron. 13, 1 ͑1983͔͒. By doping sections of the cylinder with opaque materials, in conjunction with x-ray backlighting, the growth and feedthrough of the perturbations from the ablation front to the inner surface of the cylinder for various initial modes and amplitudes from early time through stagnation was measured. Mode coupling of illumination asymmetries with material perturbations is observed, as well as phase reversal of the perturbations from near the ablation front to the inner surface of the cylinder. Perturbation growth is observed due to convergence and compressibility alone, without the effects of acceleration, and scales as ϳ1/R, where is the mass density. Imaging is performed with an x-ray pinhole camera coupled to a gated microchannel plate detector.

In this work we report on how salt concentration and cation species affect DNA translocation in voltage-biased silicon nitride nanopores. The translocation of double-stranded DNA (dsDNA) in linear, circular, and supercoiled forms was measured in salt solutions containing KCl, NaCl, and MgCl2. As the KCl concentrations were decreased from 1M to 0.1M, the time taken by a DNA molecule to pass through a nanopore was shorter and the frequency of the translocation in a folded configuration was reduced, suggesting an increase in DNA electrophoretic mobility and DNA persistence length. When the salt concentration was kept at 1M, but replacing K+ with Na+, longer DNA translocation times (td) were observed. The addition of low concentrations of MgCl2 with 1.6M KCl resulted in longer td and an increased frequency of supercoiled DNA molecules in a branched form. These observations were consistent with the greater counterion charge screening ability of Na+ and Mg2+ as compared to K+. In addition, we demonstrated that dsDNA molecules indeed translocated through a ~10 nm nanopore by PCR amplification and gel electrophoresis. We also compared the dependence of DNA mobility and conformation on KCl concentration and cation species measured at single molecule level by silicon nitride nanopores with existing bulk-based experimental results and theoretical predictions.