Jason Holt | University of California, Berkeley (original) (raw)

Papers by Jason Holt

Research paper thumbnail of Fast Mass Transport through Sub2nm Carbon Nanotubes

We report gas and water flow measurements through microfabricated membranes with sub-2nm aligned ... more We report gas and water flow measurements through microfabricated membranes with sub-2nm aligned carbon nanotubes as pores. The measured gas flow exceeds predictions of the Knudsen diffusion model by at least an order of magnitude. The measured water flow rate exceeds values calculated from continuum hydrodynamics models by two to three orders of magnitude and agrees with flow rates extrapolated from molecular dynamics simulations. The gas and water permeabilities of these nanotube-based membranes are orders of magnitude higher than those of commercial polycarbonate membranes, despite having an order of magnitude smaller pore sizes. These properties should enable more energy-efficient nanoscale filtration, as well as fundamental studies of mass transport in confined environments.

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Research paper thumbnail of Identification of endohedral water in single-walled carbon nanotubes by 1H NMR

Nano Letters, 2008

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Research paper thumbnail of The aging of tungsten filaments and its effect on wire surface kinetics in hot-wire chemical vapor deposition

Journal of Applied Physics, 2002

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Research paper thumbnail of Methods for probing water at the nanoscale

Microfluidics and Nanofluidics, 2008

... dynamics that has emerged from decades worth of studies. As Stillinger (1980) summarizes in h... more ... dynamics that has emerged from decades worth of studies. As Stillinger (1980) summarizes in his review on the state of knowledge of water 25 years ago (a picture that has in a general sense remained intact), water is envisioned as a random or disordered network of ...

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Research paper thumbnail of Method for characterization of adhesion properties of trace explosives in fingerprints and fingerprint simulations

Journal of Forensic …, 2000

The near inevitable transfer of explosive particulate matter through fingerprints makes it possib... more The near inevitable transfer of explosive particulate matter through fingerprints makes it possible to detect concealed explosives through surface sampling. Repeatable and well-characterized fingerprint simulation facilitates quantitative comparison between particulate sampling methods for subsequent detection of trace explosive residues. This study employs a simple, but reproducible sampling system to determine the accuracy of a fingerprint simulation. The sampling system uses a gas jet to entrain particles from a substrate and the resulting airborne particles are then aspirated onto a Teflon filter. A calibrated Barringer IonScan 400 ion mobility spectrometer was used to determine the mass of explosive material collected on the filter. The IonScan 400 was calibrated with known masses of 2,4,6-trinitrotoluene (TNT). The resulting calibration curve is in good agreement with that obtained by Garofolo et al. (1994) for an earlier model of the instrument. The collection efficiency of the sampling system was measured for three particle sizes (8.0. 10.0, and 13.0 microm) using spherical polystyrene particles laced with known quantities of TNT. Collection efficiency ranged from less than 1% for the larger particles to 5% for the smaller particles. Particle entrainment from the surface was monitored with dark field imaging of the remaining particles. The sampling system was then applied to two C4 test samples--a fingerprint transfer and a dry Teflon transfer. Over 100 ng of RDX was collected from the dry transfer sample, while less than 1 ng was collected from the fingerprint transfer. Possible explanations for this large difference are presented based on the system calibration.

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Research paper thumbnail of Recent advances in nanoelectrode architecture for photochemical hydrogen production

Energy & Environmental Science, 2010

... Finally, an example of the use of a designed nanostructure involves gold-tipped CdSe ... Rece... more ... Finally, an example of the use of a designed nanostructure involves gold-tipped CdSe ... Recentadvances in nanomaterials have facilitated a number of nanoscale designs for efficient solar ... In this review, we selected four important categories of nanoarchitectures that have the ...

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Research paper thumbnail of Ion exclusion by sub-2-nm carbon nanotube pores

Proceedings of the …, 2008

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Research paper thumbnail of Nanofluidics in carbon nanotubes

Nano Today, 2007

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Research paper thumbnail of Fast mass transport through sub-2-nanometer carbon nanotubes

Science, 2006

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Research paper thumbnail of Fast Mass Transport through Sub2nm Carbon Nanotubes

We report gas and water flow measurements through microfabricated membranes with sub-2nm aligned ... more We report gas and water flow measurements through microfabricated membranes with sub-2nm aligned carbon nanotubes as pores. The measured gas flow exceeds predictions of the Knudsen diffusion model by at least an order of magnitude. The measured water flow rate exceeds values calculated from continuum hydrodynamics models by two to three orders of magnitude and agrees with flow rates extrapolated from molecular dynamics simulations. The gas and water permeabilities of these nanotube-based membranes are orders of magnitude higher than those of commercial polycarbonate membranes, despite having an order of magnitude smaller pore sizes. These properties should enable more energy-efficient nanoscale filtration, as well as fundamental studies of mass transport in confined environments.

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Research paper thumbnail of Identification of endohedral water in single-walled carbon nanotubes by 1H NMR

Nano Letters, 2008

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Research paper thumbnail of The aging of tungsten filaments and its effect on wire surface kinetics in hot-wire chemical vapor deposition

Journal of Applied Physics, 2002

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Research paper thumbnail of Methods for probing water at the nanoscale

Microfluidics and Nanofluidics, 2008

... dynamics that has emerged from decades worth of studies. As Stillinger (1980) summarizes in h... more ... dynamics that has emerged from decades worth of studies. As Stillinger (1980) summarizes in his review on the state of knowledge of water 25 years ago (a picture that has in a general sense remained intact), water is envisioned as a random or disordered network of ...

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Research paper thumbnail of Method for characterization of adhesion properties of trace explosives in fingerprints and fingerprint simulations

Journal of Forensic …, 2000

The near inevitable transfer of explosive particulate matter through fingerprints makes it possib... more The near inevitable transfer of explosive particulate matter through fingerprints makes it possible to detect concealed explosives through surface sampling. Repeatable and well-characterized fingerprint simulation facilitates quantitative comparison between particulate sampling methods for subsequent detection of trace explosive residues. This study employs a simple, but reproducible sampling system to determine the accuracy of a fingerprint simulation. The sampling system uses a gas jet to entrain particles from a substrate and the resulting airborne particles are then aspirated onto a Teflon filter. A calibrated Barringer IonScan 400 ion mobility spectrometer was used to determine the mass of explosive material collected on the filter. The IonScan 400 was calibrated with known masses of 2,4,6-trinitrotoluene (TNT). The resulting calibration curve is in good agreement with that obtained by Garofolo et al. (1994) for an earlier model of the instrument. The collection efficiency of the sampling system was measured for three particle sizes (8.0. 10.0, and 13.0 microm) using spherical polystyrene particles laced with known quantities of TNT. Collection efficiency ranged from less than 1% for the larger particles to 5% for the smaller particles. Particle entrainment from the surface was monitored with dark field imaging of the remaining particles. The sampling system was then applied to two C4 test samples--a fingerprint transfer and a dry Teflon transfer. Over 100 ng of RDX was collected from the dry transfer sample, while less than 1 ng was collected from the fingerprint transfer. Possible explanations for this large difference are presented based on the system calibration.

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Research paper thumbnail of Recent advances in nanoelectrode architecture for photochemical hydrogen production

Energy & Environmental Science, 2010

... Finally, an example of the use of a designed nanostructure involves gold-tipped CdSe ... Rece... more ... Finally, an example of the use of a designed nanostructure involves gold-tipped CdSe ... Recentadvances in nanomaterials have facilitated a number of nanoscale designs for efficient solar ... In this review, we selected four important categories of nanoarchitectures that have the ...

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Research paper thumbnail of Ion exclusion by sub-2-nm carbon nanotube pores

Proceedings of the …, 2008

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Research paper thumbnail of Nanofluidics in carbon nanotubes

Nano Today, 2007

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Research paper thumbnail of Fast mass transport through sub-2-nanometer carbon nanotubes

Science, 2006

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