Thermal, sonochemical, and mechanical behaviors of single crystal [60]fullerene nanotubes

Although related to conventional carbon nanotubes in both shape and construction, fullerene nanowhiskers and fullerene nanotubes have received far less attention. A modified liquid-liquid interfacial precipitation technique is described to produce relatively uniform batches of [60]fullerene nanotubes in high yield. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) reveal that the tubes possess approximately 100-nm inside diameters and 300-nm outside diameters. The [60]fullerene nanotubes degrade slowly at 180 degrees C, eventually collapsing into micron scale [60]fullerene discs and rods, as revealed by optical microscopy and AFM. Ultrasonic cavitation chops [60]fullerene nanotubes into smaller segments within seconds. Longer ultrasonic bathing leads to considerable structural damage in which the sidewalls rupture. Mechanical stress tests using an AFM microscope tip effectively dent and break [60]fullerene nanowhiskers, revealing a hollow interior.     

An Exploration of Embodied Visual Exploration

International Journal of Computer Vision - Embodied computer vision considers perception for robots in novel, unstructured environments. Of particular importance is the embodied visual exploration...     

DISTILLATION COLUMN DESIGN BY METHOD OF McCABE AND THIELE: DISTMAN COMPUTER GRAPHICS PROGRAM

A computer graphics program developed for the IBM PC calculates equilibrium and operating lines and steps off the number of stages on screen using the McCabe-Thiele method. The results are obtained by graphics, not by numerical methods, so that the accuracy depends upon the screen resolution or pixel density. The equilibrium line is drawn from bubble-point temperature calculations using constants from the Wilson and Antoine equations. The operating lines and staircase are constructed by computer graphics according to the prescribed operating parameters. Design variables, which include the reflux ratio, quality of feed, Murphree efficiency, product purities and pressure, may be changed interactively.     

Three-dimensional reconstruction of a plant dictyosome from series of ultrathin sections using computer image processing

A single dictyosome from an actively secreting ovary gland cell of Aptenia cordifolia has been reconstructed in 3-D from a series of twenty-nine electron micrographs by computer image processing. The reconstruction is presented under different viewing angles in the form of shaded perspective displays. From these displays the entire dictyosome, surrounded by numerous vesicles, appears to be more a spherical than a flat body. The plate-like region of the dictyósome is demonstrated when only a portion of the electron micrographs is used for the image processing, leading to ‘cut-off’ displays. Since some upper planes were removed, such ‘cut-off’ displays revealed both tubular connections between cisternae of the dictyosome and the neighbouring endoplasmic reticulum as well as tubular continuities between adjacent Golgi cisternae within the same stack. Possible consequences of both types of interconnections on transport and processing of proteins and glycoproteins are discussed.     

On the effect of spatial resolution on atmospheric mercury modeling

Mathematical modeling of the atmospheric fate and transport of mercury (Hg) was conducted using three nested domains covering global, continental and regional scales with horizontal resolutions of approximately 1000, 100 and 20 km, respectively. Comparisons of modeling results with wet deposition fluxes show a coefficient of determination (r(2)) of 0.45 for the continental simulation and 0.14 for the continental/regional simulation. The poor correlation obtained in the regional simulation results to a large extent from the fact that the model predicts an increasing gradient in Hg wet deposition from Minnesota to Pennsylvania, which is not observed in the monitoring network. The use of a finer spatial resolution (20 km) improves model performance in Minnesota and Wisconsin (upwind of major Hg emission sources) but degrades model performance in Pennsylvania (downwind of major Hg emission sources). We suggest the hypothesis that some key Hg chemical transformations are likely missing in current models of atmospheric Hg.     

Analyzing CRA Lending During the Tsunami in Subprime Lending and Foreclosure in the Philadelphia MSA

Until the onset of the financial meltdown, independent mortgage companies (IMCs) had begun to originate an increasing share of subprime loans, a high proportion of which went into foreclosure. In this study, we compare and contrast the characteristics of neighborhoods that have high proportions of loans made by Community Reinvestment Act (CRA)-regulated institutions with those that have high proportions made by IMCs. We find that IMC-dominated neighborhoods are characterized by high proportions of Blacks/African-Americans, low average family incomes and low nominal average family income increases, an old housing stock with inexpensive homes, a low homeownership rate, high vacancy rates, and a high proportion of high-cost loans. Based on t-tests and regression analyses, we find that areas dominated by IMCs are different from neighborhoods dominated by CRA Lenders and that the proportion of people of color helps explain foreclosure rates.     

The effect of solidification direction with respect to gravity on ice-templated TiO2 microstructures

Unidirectional ice-templating produces materials with aligned, elongated pores via: (i) directional solidification of particle suspensions wherein suspended particles are rejected and incorporated between aligned dendrites, (ii) sublimation of the solidified fluid, and (iii) sintering of the particles into elongated walls which are templated by the ice dendrites. Most ice-templating studies utilize upward solidification techniques, where solid ice is located at the bottom of the solidification mold (closest to the cold source), the liquid suspension is above the ice, and the solidification front advances upward, against gravity. Liquid water reaches its maximum density at 4 °C; thus, liquid nearest the solid/liquid interface, at 0ºC, is less dense than warmer liquid above (up to 4 °C, above which, a density inversion occurs, and liquid density decreases with increasing temperature). The lower density liquid nearest the solidification front is thus expected to rise due to buoyancy, promoting convective fluid motion in the liquid during solidification. Here, we investigate the effect of solidification direction with respect to the direction of gravity on ice-templated microstructures to study the role of buoyancy-driven fluid motion during solidification. We hypothesize that, for upward solidification, the convective fluid motion that results from the liquid density gradient occurs near the solidification front. For downward solidification, we expect that this fluid motion occurs farther away from the solidification front. Aqueous suspensions of TiO₂ nanoparticles (10–30 nm in size, 10, 15, and 21 vol.%) are solidified upward (against gravity, with ice on bottom and water on top), downward (water on bottom, ice on top), and horizontally (perpendicular to gravity). Microstructural investigation of sintered samples shows evidence of buoyancy-driven, convective fluid flow during solidification for samples solidified upwards (against gravity), including (i) tilting of the wall (and pore) orientation with respect to the induced temperature gradient, (ii) ice lens defects (cracks oriented perpendicular to the freezing direction), and (iii) radial macrosegregation. These features are not observed for downward nor horizontal solidification configurations, consistent with the hypothesis that convective fluid motion does not interact directly with the solidification front for downward solidification.     

Reaction kinetics and optimization of the copper-catalyzed oxidation of ApoA-1M

This paper summarizes the development of an optimized Cu(II)-catalyzed oxidation process for the dimer formation of ApoA-1M, the protein component of an HDL mimic with potential efficacy in atherosclerotic plaque reduction. This oxidation represents a major processing step in the large-scale manufacture of ApoA-1M dimer. The development approach utilizes reaction kinetic modeling, design of experiment, and neural network analysis to establish a quantitative basis for specification of process operating ranges. This work is thus an example of quality by design (QbD) principles where a systematic mechanistic understanding combined with multivariate analysis is integral to process development. Operating within the defined optimum window of operation resulted in both enhanced performance and robustness for the oxidation step in the piloting and manufacturing campaigns.