Digital PCR enables the absolute quantitation of nucleic acids in a sample. The lack of scalable and practical technologies for digital PCR implementation has hampered the widespread adoption of this inherently powerful technique. Here we describe a high-throughput droplet digital PCR (ddPCR) system that enables processing of ∼2 million PCR reactions using conventional TaqMan assays with a 96-well plate workflow. Three applications demonstrate that the massive partitioning afforded by our ddPCR system provides orders of magnitude more precision and sensitivity than real-time PCR. First, we show the accurate measurement of germline copy number variation. Second, for rare alleles, we show sensitive detection of mutant DNA in a 100 000-fold excess of wildtype background. Third, we demonstrate absolute quantitation of circulating fetal and maternal DNA from cell-free plasma. We anticipate this ddPCR system will allow researchers to explore complex genetic landscapes, discover and validate new disease associations, and define a new era of molecular diagnostics.

Experiments to examine the effects of biomass/coal cofiring on fine particle formation were performed in the Sandia Multi-Fuel Combustor using fuels of pure coal, three combinations of switchgrass and coal, and pure switchgrass. For this work, fine particles with aerodynamic diameter between 10 nm and 1 μm were examined. A constant solid-fuel thermal input of 8 kW was maintained. The combustion products were cooled from 1200 to 420°C during passage through the 4.2 m long reactor to simulate the temperatures experienced in the convection pass of a boiler. Fine particle number densities, mass concentrations, and total integrated number and mass concentrations at the reactor exit were determined using a scanning mobility particle sizer. The fine particle number concentrations for cofiring were much higher than those achieved with dedicated coal combustion. However, the total integrated mass concentration of particles remained essentially constant for all levels of cofiring from 0% coal to 100% coal. The constant mass concentration is significant because pending environmental regulations are likely to be based on particle mass rather than particle size.

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In this paper is presented an analytic, theoretical and numerical study of the Viscous Rotary Engine Power System (VREPS). In addition, a proposed process flow for the fabrication of the VREPS using DRIE of silicon is described. The design premise of the VREPS is to derive mechanical power from the surface viscous shearing forces developed by a pressure driven flow present between a rotating disk or annulus and a stationary housing. The resulting motion of the rotating disk or annulus is converted into electrical power by using an external permanent magnet, embedded nickel-iron magnetic circuits, and an external switched magnetic pole electric generator similar to the design proposed by M. Senesky for the UC Berkeley micro-Wankel Engine [1]. This paper will examine the power output, isentropic efficiency, and operating characteristics of the disk and annular viscous turbines using the lubrication approximation and the Creeping Flow Equations (Stokes Flow). The viscous turbine is optimized for maximum isentropic efficiency using MATLAB numerical optimization routines. Finally, a unique triple-wafer micro-fabrication process for VREPS is presented. The proposed design consists of a 250 μm thick, 3.4 mm OD / 2.4 mm ID annular rotor with embedded magnetic poles and four 10 μm driving channels on each side of the rotor. Electrical power is generated with a switched magnetic pole generator, external permanent magnet, and integrated magnetic circuits. Calculations with water predict an output power of 825 mW at an isentropic efficiency of 25% using a pressure drop of 5 MPa cross the device.

Experiments to examine the effects of biomass/coal cofiring on fine particle formation were performed in the Sandia Multi-Fuel Combustor using fuels of pure coal, 3 combinations of switchgrass and coal, and pure switchgrass. A constant thermal input was maintained. The combustion products were cooled during passage through the 4.2 m long reactor to simulate the temperatures experienced in the convection pass of a boiler. Fine particle number densities, mass concentrations, and total number concentrations for particles between 10 nm and 1 μm at the reactor exit were determined using a Scanning Mobility Particle Sizer. The results indicate that the fine particle loading for cofiring is higher than that achieved with dedicated coal combustion but lower than that achieved with dedicated switchgrass combustion.