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In this paper we report the first measurements of carrier mobilities in an inorganic nanocrystal: conducting polymer composite. The composite material in question (lead sulphide nanocrystals in the conducting polymer poly (2-methoxy-5-(2'-ethyl-hexyloxy)-pphenylene vinylene (MEH-PPV)) was made using a new single-pot, surfactant-free synthesis. Mobilties were measured using time of flight (ToF) and steady-state techniques. We have found that the inclusion of PbS nanocrystals in MEH-PPV both balances and markedly increases the hole and electron mobilities -the hole mobility is increased by a factor of ~10 5 and the electron mobility increased by ~10 7 under an applied bias of 5kVcm -1 . These results explain why dramatic improvements in electrical conductivity and photovoltaic performance are seen in devices fabricated from these composites.

An experimental investigation of high-enthalpy flow over a toroidal ballute (balloon/parachute) was conducted in an expansion tube facility. The ballute, proposed for use in a number of future aerocapture missions, involves the deployment of a large toroidal-shaped inflatable parachute behind a space vehicle to generate drag on passing through a planetary atmosphere, thus, placing the spacecraft in orbit. A configuration consisting of a spherical spacecraft, followed by a toroid, was tested in a superorbital facility. Measurements at moderate-enthalpy conditions (15-20 MJ/kg) in nitrogen and carbon dioxide showed peak heat transfer rates of around 20 MW/m 2 on the toroid. At higher enthalpies (>50 MJ/kg) in nitrogen, carbon dioxide, and a hydrogen-neon mixture, heat transfer rates above 100 MW/m 2 were observed. Imaging using near-resonant holographic interferometry showed that the flows were steady except when the opening of the toroid was blocked. Nomenclaturespacecraft center-to-center offset from toroid, mm h = specific enthalpy, J · kg −1 K = stagnation point streamwise velocity gradient, s −1 L = characteristic length scale, m M = Mach number m = order of truncation error in computational fluid dynamics (CFD) code N = number of cells in the simulation Pr = Prandtl number p = pressure, Pȧ Q = total heat flux, Ẇ q = heat flux, Wm −2 Re = Reynolds number based on freestream properties and U eq Re e = Reynolds number based on postshock properties and U eq r = toroid cylinder radius, 3 mm St = Stanton number based on freestream conditions St e = Stanton number based on postshock density using U eq as the velocity T = temperature, K U = velocity, m · s −1 U eq = equivalent flight speed √ (2 × stagnation enthalpy), m · s −1 γ = specific heat ratio x = length of a cell within the grid of the CFD code µ = viscosity (Pa · s) ρ = density, kg · m −3 Subscripts and Superscripts e = ballute stagnation conditions eq = equivalent flight conditions w = wall conditions 0 = isentropic total conditions 1 = initial (fill) value 2 = postprimary shock value ∞ = freestream in test section

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