A High-Flux, Flexible Membrane with Parylene-encapsulated Carbon Nanotubes (open access)

A High-Flux, Flexible Membrane with Parylene-encapsulated Carbon Nanotubes

We present fabrication and characterization of a membrane based on carbon nanotubes (CNTs) and parylene. Carbon nanotubes have shown orders of magnitude enhancement in gas and water permeability compared to estimates generated by conventional theories [1, 2]. Large area membranes that exhibit flux enhancement characteristics of carbon nanotubes may provide an economical solution to a variety of technologies including water desalination [3] and gas sequestration [4]. We report a novel method of making carbon nanotube-based, robust membranes with large areas. A vertically aligned dense carbon nanotube array is infiltrated with parylene. Parylene polymer creates a pinhole free transparent film by exhibiting high surface conformity and excellent crevice penetration. Using this moisture-, chemical- and solvent-resistant polymer creates carbon nanotube membranes that promise to exhibit high stability and biocompatibility. CNT membranes are formed by releasing a free-standing film that consists of parylene-infiltrated CNTs, followed by CNT uncapping on both sides of the composite material. Thus fabricated membranes show flexibility and ductility due to the parylene matrix material, as well as high permeability attributed to embedded carbon nanotubes. These membranes have a potential for applications that may require high flux, flexibility and durability.
Date: March 14, 2008
Creator: Park, H. G.; In, J.; Kim, S.; Fornasiero, F.; Holt, J. K.; Grigoropoulos, C. P. et al.
System: The UNT Digital Library
Low-Temperature Martensitic and Pressure-Induced Delta to Alpha-Prime Phase Transformations in a Pu-Ga Alloy (open access)

Low-Temperature Martensitic and Pressure-Induced Delta to Alpha-Prime Phase Transformations in a Pu-Ga Alloy

None
Date: March 14, 2008
Creator: Schwartz, A J; Wall, M A; Farber, D L; Moore, K T & Blobaum, K M
System: The UNT Digital Library
Molecular analysis of the gut microbiota of identical twins with Crohn's disease (open access)

Molecular analysis of the gut microbiota of identical twins with Crohn's disease

Increasing evidence suggests that a combination of host genetics and the composition of the gut microbiota are important for development of Crohn's disease (CD). Our aim was to study identical twins with CD to determine microbial factors independently of host genetics. Fecal samples were studied from 10 monozygotic twin pairs with CD (discordant n=6, concordant n=4) and 8 healthy twin pairs. DNA was extracted, 16S rRNA genes were PCR amplified and T-RFLP fingerprints generated using general bacterial and Bacteroides group specific primers. The microbial communities were also profiled based on their % G+C contents. Bacteroides 16S rRNA genes were cloned and sequenced from a subset of the samples. The bacterial diversity in each sample and similarity indices between samples were estimated based on the T-RFLP data using a combination of statistical approaches. Healthy individuals had a significantly higher bacterial diversity compared to individuals with CD. The fecal microbial communities were more similar between healthy twins than between twins with CD, especially when these were discordant for the disease. The microbial community profiles of individuals with ileal CD were significantly different from healthy individuals and those with colonic CD. Also, CD individuals had a lower relative abundance of B. uniformis and …
Date: March 14, 2008
Creator: Jansson, Janet; Dicksved, Johan; Halfvarson, Jonas; Rosenquist, Magnus; Jarnerot, Gunnar; Tysk, Curt et al.
System: The UNT Digital Library
Optical Switching in VO2 films by below-gap excitation (open access)

Optical Switching in VO2 films by below-gap excitation

We study the photo-induced insulator-metal transition in VO2, correlating threshold and dynamic evolution with excitation wavelength. In high-quality single crystal samples, we find that switching can only be induced with photon energies above the 670-meV gap. This contrasts with the case of polycrystalline films, where formation of the metallic state can also be triggered with photon energies as low as 180 meV, well below the bandgap. Perfection of this process may be conducive to novel schemes for optical switches, limiters and detectors, operating at room temperature in the mid-IR.
Date: March 14, 2008
Creator: Dipartimento di Fisica, Universita?di Brescia, Italy
System: The UNT Digital Library
Searching for Gluinos at the Tevatron (open access)

Searching for Gluinos at the Tevatron

This letter describes how to perform model-independent searches for new pair-produced color octet particles that each subsequently decay into two jets plus missing energy at the Tevatron. Current searches are not sensitive to all regions of parameter space because they employ CMSSM-motivated cuts. Optimizing the H{sub T} and E{sub T} cuts expands the sensitivity of searches for all kinematically allowed decays.
Date: March 14, 2008
Creator: Alwall, Johan; Le, My-Phuong; Lisanti, Mariangela; Wacker, Jay G. & /SLAC /Stanford U., Phys. Dept.
System: The UNT Digital Library
2nd Annual DOE-ERSP PI Meeting: Abstracts (open access)

2nd Annual DOE-ERSP PI Meeting: Abstracts

Welcome to the annual 2007 Environmental Remediation Sciences Program (ERSP) Principal Investigators (PIs) meeting. The purpose of this meeting is to bring together all of the lead PIs and key Co-PIs in the program to share and review the results of funded research from the past year. This meeting allows program managers from the Environmental Remediation Sciences Division (ERSD) within the Office of Biological and Environmental Research (OBER) to gauge the progress and significance of the funded research, and it is also an important venue to showcase ERSP research to interested parties within DOE and other invited federal agency representatives. Additionally, these meetings should serve as an opportunity for funded PIs to view their research in the context of the entire ERSP portfolio. Past ERSP meetings have been very important venues for detailed discussion of research results among PIs, development of new research ideas, fostering new collaborations and discussion with ERSD program managers on future research efforts and/or initiatives within the program. In short, these meetings are an important resource for both program managers and PIs. There will be only one ERSP PI meeting for 2007. In years past, ERSD has sponsored two PI meetings, one in the spring and …
Date: March 14, 2007
Creator: Hazen, Terry C.
System: The UNT Digital Library
B0 to K0K0bar and Other Hadronic b to d Decays (open access)

B0 to K0K0bar and Other Hadronic b to d Decays

The b {yields} d penguin-dominated modes B {yields} K{bar K} have been observed at the B factories. in addition, the BABAR collaboration has reported the first time-dependent CP-violation measurement in B{sup 0} {yields} K{sup 0}{bar K}{sup 0}.
Date: March 14, 2007
Creator: Biesiada, J.
System: The UNT Digital Library
Energy Doubling of 42 GeV Electrons in a Meter-scale Plasma Wakefield Accelerator (open access)

Energy Doubling of 42 GeV Electrons in a Meter-scale Plasma Wakefield Accelerator

The energy frontier of particle physics is several trillion electron volts, but colliders capable of reaching this regime (such as the Large Hadron Collider and the International Linear Collider) are costly and time-consuming to build; it is therefore important to explore new methods of accelerating particles to high energies. Plasma-based accelerators are particularly attractive because they are capable of producing accelerating fields that are orders of magnitude larger than those used in conventional colliders. In these accelerators, a drive beam (either laser or particle) produces a plasma wave (wakefield) that accelerates charged particles. The ultimate utility of plasma accelerators will depend on sustaining ultrahigh accelerating fields over a substantial length to achieve a significant energy gain. Here we show that an energy gain of more than 42 GeV is achieved in a plasma wakefield accelerator of 85 cm length, driven by a 42 GeV electron beam at the Stanford Linear Accelerator Center (SLAC). The results are in excellent agreement with the predictions of three-dimensional particle-in-cell simulations. Most of the beam electrons lose energy to the plasma wave, but some electrons in the back of the same beam pulse are accelerated with a field of {approx} 52GV m{sup -1}. This effectively …
Date: March 14, 2007
Creator: Blumenfeld, Ian; Clayton, Christopher E.; Decker, Franz-Josef; Hogan, Mark J.; Huang, Chengkun; Ischebeck, Rasmus et al.
System: The UNT Digital Library
First NNLL Prediction of B(\barB \rightarrow X_s \gamma) (open access)

First NNLL Prediction of B(\barB \rightarrow X_s \gamma)

The authors discuss the first NNLL prediction of the B {yields} X{sub s}{gamma} branching ratio, including important additional subtleties due to non-perturbative corrections and logarithmically-enhanced cut effects.
Date: March 14, 2007
Creator: Hurth, Tobias & /SLAC, /CERN
System: The UNT Digital Library
Flashing Slurry Releases (open access)

Flashing Slurry Releases

The Hanford K Basin Closure Project involves the retrieval, transfer and processing of radioactive contaminated slurries containing partially corroded spent nuclear fuel from the K Basin spent fuel pools. The spent fuel is primarily metallic fuel from the operation of the Hanford reactors. The Sludge Treatment Project is being designed to treat and package this material in preparation for ultimate disposal. The processing of the contaminated slurries includes further corrosion of the remaining uncorroded uranium metal in a large heated vessel to form a more stable metal oxide for packaging and storage.
Date: March 14, 2007
Creator: Schmitt, Bruce E. & Young, Jonathan
System: The UNT Digital Library
Measurement of the Time-dependent CP Asymmetry inB to D(*)_CP h0 Decays (open access)

Measurement of the Time-dependent CP Asymmetry inB to D(*)_CP h0 Decays

The authors report a measurement of the time-dependent CP-asymmetry parameters S and C in color-suppressed B{sup 0} {yields} D{sup (*)0}h{sup 0} decays, where h{sup 0} is a {pi}{sup 0}, {eta}, or {omega} meson, and the D{sup 0} decays to one of the CP eigenstates K{sup +}K{sup -}, K{sub S}{sup 0}{pi}{sup 0}, or K{sub S}{sup 0}{omega}. The data sample consists of 383 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy B-factory at SLAC. The results are S = -0.56 {+-} 0.23 {+-} 0.05 and C = -0.23 {+-} 0.16 {+-} 0.04, where the first error is statistical and the second is systematic.
Date: March 14, 2007
Creator: Aubert, B.
System: The UNT Digital Library
Observation of CP Violation in B0 to K+pi- and B0 to pi+pi- (open access)

Observation of CP Violation in B0 to K+pi- and B0 to pi+pi-

The authors report observations of CP violation in the decays B{sup 0} {yields} K{sup +}{pi}{sup -} and B{sup 0} {yields} {pi}{sup +}{pi}{sup -} in a sample of 383 million {Upsilon}(4S) {yields} B{bar B} events. They find 4372 {+-} 82 B{sup 0} {yields} K{sup +}{pi}{sup -} decays and measure the direct Cp-violating charge asymmetry {Alpha}{sub K{pi}} = -0.107 {+-} 0.018(stat){sub -0.004}{sup +0.007}(syst), which excludes the CP-conserving hypothesis with a significance of 5.5 standard deviations. In the same sample they find 1139 {+-} 49 B{sup 0} {yields} {pi}{sup +}{pi}{sup -} decays and measure the CP-violating asymmetries S{sub {pi}{pi}} = -0.60 {+-} 0.11(stat) {+-} 0.03(syst) and C{sub {pi}{pi}} = -0.21 {+-} 0.09(stat) {+-} 0.02(syst). CP conservation in B{sup 0} {yields} {pi}{sup +}{pi}{sup -} (S{sub {pi}{pi}} = C{sub {pi}{pi}} = 0) is excluded at a confidence level 1-C.L. = 8 x 10{sup -8}, corresponding to 5.4 standard deviations.
Date: March 14, 2007
Creator: Aubert, B.
System: The UNT Digital Library
OPTIMIZATION OF WATER TO FUEL RATIOS IN CLADDED CYLINDER ARRAYS (open access)

OPTIMIZATION OF WATER TO FUEL RATIOS IN CLADDED CYLINDER ARRAYS

Often in criticality safety problems, the analyst is concerned about two conditions: Loss of Mass Control and Loss of Moderation Control. Determining and modeling the maximum amount of fuel that can fit in a given container is usually trivial. Determining and modeling the maximum amount of water (or other potential moderator) is usually more difficult. Optimization of the pitch has been shown to provide an increase in system reactivity. Both MOX and LEU systems have been shown to be sensitive to moderator intrusion in varying pitched configurations. The analysis will have to determine the effect of optimizing the pitch for each array.
Date: March 14, 2007
Creator: Huffer, J
System: The UNT Digital Library
Regulatory Background of VSS with respect to the USQ Process (open access)

Regulatory Background of VSS with respect to the USQ Process

None
Date: March 14, 2007
Creator: Brown, E & Mitchell, M
System: The UNT Digital Library
Spectroscopic Characterization and Simulation of Chemical Sputtering Using the DiMES Porous Plug Injector in DIII-D (open access)

Spectroscopic Characterization and Simulation of Chemical Sputtering Using the DiMES Porous Plug Injector in DIII-D

None
Date: March 14, 2007
Creator: McLean, A. G.; Davis, J. W.; Stangeby, P. C.; Brooks, N. H.; Whyte, D. G.; Allen, S. L. et al.
System: The UNT Digital Library
Spontaneous Superlattice Formation in Nanorods through PartialCation Exchange (open access)

Spontaneous Superlattice Formation in Nanorods through PartialCation Exchange

Lattice mismatch strains are widely known to controlnanoscale pattern formation in heteroepitaxy, but such effects have notbeen exploited in colloidal nanocrystal growth. We demonstrate acolloidal route to synthesizing CdS-Ag2S nanorod superlattices throughpartial cation exchange. Strain induces the spontaneous formation ofperiodic structures. Ab initio calculations of the interfacial energy andmodeling of strain energies show that these forces drive theself-organization. The nanorod superlattices exhibit high stabilityagainst ripening and phase mixing. These materials are tunablenear-infrared emitters with potential applications as nanometer-scaleoptoelectronic devices.
Date: March 14, 2007
Creator: Robinson, Richard D.; Sadtler, Bryce; Demchenko, Denis O.; Erdonmez, Can K.; Wang, Lin-Wang & Alivisatos, A. Paul
System: The UNT Digital Library
Symplectic Symmetry and the Ab Initio No-Core Shell Model (open access)

Symplectic Symmetry and the Ab Initio No-Core Shell Model

The symplectic symmetry of eigenstates for the 0{sub gs}{sup +} in {sup 16}O and the 0{sub gs}{sup +} and lowest 2{sup +} and 4{sup +} configurations of {sup 12}C that are well-converged within the framework of the no-core shell model with the JISP16 realistic interaction is examined. These states are found to project at the 85-90% level onto very few symplectic representations including the most deformed configuration, which confirms the importance of a symplectic no-core shell model and reaffirms the relevance of the Elliott SU(3) model upon which the symplectic scheme is built.
Date: March 14, 2007
Creator: Draayer, Jerry P.; Dytrych, Tomas; Sviratcheva, Kristina D.; Bahri, Chairul & Vary, James P.
System: The UNT Digital Library
2005 Chemical Reactions at Surfaces (open access)

2005 Chemical Reactions at Surfaces

The Gordon Research Conference (GRC) on 2005 Chemical Reactions at Surfaces was held at Ventura Beach Marriott, Ventura California from February 13, 2005 through February 18, 2005. The Conference was well-attended with 124 participants (attendees list attached). The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students. In designing the formal speakers program, emphasis was placed on current unpublished research and discussion of the future target areas in this field. There was a conscious effort to stimulate lively discussion about the key issues in the field today. Time for formal presentations was limited in the interest of group discussions. In order that more scientists could communicate their most recent results, poster presentation time was scheduled. Attached is a copy of the formal schedule and speaker program and the poster program. In addition to these formal interactions, 'free time' was scheduled to allow informal discussions. Such discussions are fostering new collaborations and joint efforts in the field.
Date: March 14, 2006
Creator: Friend, Cynthia M.
System: The UNT Digital Library
Beam Test Proposal of An ODR Beam Size Monitor at the SLAC FFTB (open access)

Beam Test Proposal of An ODR Beam Size Monitor at the SLAC FFTB

ODR (Optical Diffraction Radiation) transverse beam size measurement at the SLAC FFTB at 28.5 GeV is a challenge and it requires special target and optics system, which is much difficult than the conventional ODR beam size measurement. We propose to use a curved disphased conductive slit target to recover the sensitivity in the measurement of the single bunch transverse beam size by using ODR photons from a conductive slit. In order to cancel the effect of the beam divergence, the conductive slit target surface must be curved. Also, we can obtain the focused interference pattern of the ODR photons at the detector at the shorter distance from the target than the {gamma}{sup 2}{lambda}, by using lens optics system.
Date: March 14, 2006
Creator: Fukui, Y.; Cline, D.; Zhou, F.; /UCLA; Aryshev, A.; Karataev, P. et al.
System: The UNT Digital Library
High-Precision Resonant Cavity Beam Position, Emittance And Third-Moment Monitors (open access)

High-Precision Resonant Cavity Beam Position, Emittance And Third-Moment Monitors

Linear colliders and FEL facilities need fast, nondestructive beam position and profile monitors to facilitate machine tune-up, and for use with feedback control. FAR-TECH, Inc., in collaboration with SLAC, is developing a resonant cavity diagnostic to simultaneously measure the dipole, quadrupole and sextupole moments of the beam distribution. Measurements of dipole and quadrupole moments at multiple locations yield information about beam orbit and emittance. The sextupole moment can reveal information about beam asymmetry which is useful in diagnosing beam tail deflections caused by short-range dipole wakefields. In addition to the resonance enhancement of a single-cell cavity, use of a multi-cell standing-wave structure further enhances signal strength and improves the resolution of the device. An estimated resolution is better than 1 {micro}m in rms beam size and better than 1 nm in beam position.
Date: March 14, 2006
Creator: Barov, N.; Kim, J. S.; Weidemann, A. W.; Miller, R. H. & Nantista, C. D.
System: The UNT Digital Library
Lattice disorder and size-induced Kondo behavior in CeAl2 andCePt2+x (open access)

Lattice disorder and size-induced Kondo behavior in CeAl2 andCePt2+x

When the particle size of CeAl{sub 2} and CePt{sub 2+x} samples is reduced to the nanometer scale, antiferromagnetism is suppressed and Kondo behavior dominates. We find that the Kondo temperature T{sub K} can either decrease (CeAl{sub 2}) or increase (CePt{sub 2+x}) in the nanoparticles relative to the bulk. Extended x-ray absorption fine-structure data show that the Ce-Al and Ce-Pt environments are significantly distorted in the nanoparticles. While such distortions should strongly affect magnetic and electronic properties, we find they cannot explain the observed changes in T{sub K}. Changes in the conduction density of states or other parameters must, therefore, play a significant role.
Date: March 14, 2006
Creator: Han, S. W.; Booth, C. H.; Bauer, E. D.; Huang, P. H.; Chen, Y. Y. & Lawrence, J. M.
System: The UNT Digital Library
Measurements of B meson decays to (omega)K* and (omega)(rho) (open access)

Measurements of B meson decays to (omega)K* and (omega)(rho)

The authors describe searches for B meson decays to the charmless vector-vector final states {omega}K* and {omega}{rho} in 89 million B{bar B} pairs produced in e{sup +}e{sup -} annihilation at {radical}s = 10.58 GeV.
Date: March 14, 2006
Creator: Aubert, B.; Cheng, C. H.; Lange, D. J.; Simani, M. C.; Wright, D. M.; Abrams, G. S. et al.
System: The UNT Digital Library
The Short Circumference Damping Ring Design for the ILC (open access)

The Short Circumference Damping Ring Design for the ILC

The ILC damping ring tentative design is driven by the operational scenario of the main linac, the beam-dynamics demand of producing a stable and high-quality beam, the injection/extraction scheme and the kicker performance. In this paper, a short circumference damping ring design based on TME cells is described. The ring accommodates injection kickers which provide a flat top of 280 nsec and a 60 nsec rise and fall time and very fast strip-line kickers for beam extraction with a 2 nsec rise and fall time for 3-MHz operation.
Date: March 14, 2006
Creator: Korostelev, M.; Zimmermann, F.; Kubo, K.; Kuriki, M.; Kuroda, S.; Naito, T. et al.
System: The UNT Digital Library
Solid-State Modulators for RF And Fast Kickers (open access)

Solid-State Modulators for RF And Fast Kickers

As the switching capabilities of solid-state devices increase, these devices are being incorporated into modulator designs for high voltage accelerator applications. Solid-state modulators based on inductive adder circuit topology have demonstrated great versatility with regard to pulse width and pulse repetition rate while maintaining fast pulse rise and fall times. Additionally, these modulators are capable of being scaled to higher output voltage and power levels. An explanation of the basic circuit operation will be presented as well as test data of several different hardware systems.
Date: March 14, 2006
Creator: Cook, E. G.; Akana, G. L.; Gower, E. J.; Hawkins, S. A.; Hickman, B. C.; Brooksby, C. A. et al.
System: The UNT Digital Library