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SHIELDING ANALYSIS FOR X-RAY SOURCES GENERATED IN TARGET CHAMBER OF THE NATIONAL IGNITION FACILITY (open access)

SHIELDING ANALYSIS FOR X-RAY SOURCES GENERATED IN TARGET CHAMBER OF THE NATIONAL IGNITION FACILITY

Prompt doses from x-rays generated as result of laser beam interaction with target material are calculated at different locations inside the National Ignition Facility (NIF). The maximum dose outside a Target Chamber diagnostic port is {approx} 1 rem for a shot utilizing the 192 laser beams and 1.8 MJ of laser energy. The dose during a single bundle shot (8 laser beams) drops to {approx} 40 mrem. Doses calculated outside the Target Bay doors and inside the Switchyards (except for the 17 ft.-6 in. level) range from a fraction of mrem to about 11 mrem for 192 beams, and scales down proportionally with smaller number of beams. At the 17ft.-6 in. level, two diagnostic ports are directly facing two of the Target Bay doors and the maximum doses outside the doors are 51 and 15.5 mrem, respectively. Shielding each of the two Target Bay doors with 1/4 in. Pb reduces the dose by factor of fifty. One or two bundle shots (8 to 16 laser beams) present a small hazard to personnel in the Switchyards.
Date: March 27, 2008
Creator: Khater, H Y; Brereton, S J & Singh, M S
System: The UNT Digital Library
A Radiocarbon Chronology of Hunter-Gatherer Occupation from Bodega Bay, California, USA (open access)

A Radiocarbon Chronology of Hunter-Gatherer Occupation from Bodega Bay, California, USA

The evolution of hunter-gatherer maritime adaptations in western North America has been a prominent topic of discussion among archaeologists in recent years (e.g. Arnold 1992; Erlandson and Colten 1991; Erlandson and Glassow 1997; Lightfoot 1993). Although vast coastal regions of the northeastern Pacific (for example, southern California) have been investigated in detail, our understanding of hunter-gatherer developments along the coast of northern California is limited. Previous research indicates that humans have exploited marine mammals, fish and shellfish along the northern California shoreline since the early Holocene (Schwaderer 1992). By the end of the late Holocene, some groups remained year-round on the coast subsisting primarily on marine resources (e.g. Gould 1975; Hildebrandt and Levulett 2002). However, a paucity of well-dated cultural deposits has hindered our understanding of these developments, particularly during the early and middle Holocene. The lack of a long and reliable chronological sequence has restricted our interpretations of behavioral change, including the adaptive strategies (such as foraging, mobility and settlement) used by human foragers to colonize and inhabit the coastal areas of this region. These shortcomings have also hindered comparative interpretations with other coastal and inland regions in western North America. Here we present a Holocene radiocarbon chronology of …
Date: April 27, 2005
Creator: Kennedy, M. A.; Russell, A. D. & Guilderson, T. P.
System: The UNT Digital Library
Technology of the LSST Focal Plane (open access)

Technology of the LSST Focal Plane

None
Date: February 27, 2008
Creator: O'Connor, P.; Radeka, V.; Takacs, P.; Geary, J.; Gilmore, K.; Oliver, J. et al.
System: The UNT Digital Library
The Cost of Superconducting Magnets as a Function of Stored Energy and Design Magnetic Induction Times the Field Volume (open access)

The Cost of Superconducting Magnets as a Function of Stored Energy and Design Magnetic Induction Times the Field Volume

By various theorems one can relate the capital cost of superconducting magnets to the magnetic energy stored within that magnet. This is particularly true for magnet where the cost is dominated by the structure needed to carry the magnetic forces. One can also relate the cost of the magnet to the product of the magnetic induction and the field volume. The relationship used to estimate the cost the magnet is a function of the type of magnet it is. This paper updates the cost functions given in two papers that were published in the early 1990 s. The costs (escalated to 2007 dollars) of large numbers of LTS magnets are plotted against stored energy and magnetic field time field volume. Escalated costs for magnets built since the early 1990 s are added to the plots.
Date: August 27, 2007
Creator: Green, Mike; Green, M. A. & Strauss, B. P.
System: The UNT Digital Library
CRISPR - a Widespread System That Provides Acquired Resistance Against Phages in Bacteria and Archaea (open access)

CRISPR - a Widespread System That Provides Acquired Resistance Against Phages in Bacteria and Archaea

Arrays of clustered, regularly spaced short palindromic repeats (CRISPR) are widespread in the genomes of many bacteria and almost all archaea. These arrays are composed of direct repeats sized 24-47 bp separated by similarly sized non-repetitive sequences (spacers). It was recently experimentally shown that CRISPR arrays, along with a group of associated proteins, confer resistance to phage. Following exposure to phage, bacteria integrate new spacer sequences that are derived from the phage genome. Acquisition of these spacers enables the bacterial cell to shutdown the phage attack, presumably by an RNA-interference-like mechanism. This progress discusses the structure and function of CRISPRs and the implications of his new antiviral mechanisms in bacteria.
Date: November 27, 2007
Creator: Kunin, Victor; Sorek, Rotem; Kunin, Victor & Hugenholtz, Philip
System: The UNT Digital Library
On Point Designs for High Gain Fast Ignition (open access)

On Point Designs for High Gain Fast Ignition

Fast ignition research has reached the stage where point designs are becoming crucial to the identification of key issues and the development of projects to demonstrate high gain fast ignition. The status of point designs for cone coupled electron fast ignition and some of the issues they highlight are discussed.
Date: September 27, 2007
Creator: Key, M.; Akli, K.; Beg, F.; Betti, R.; Clark, D. S.; Chen, S. N. et al.
System: The UNT Digital Library
A Cone Jet-Finding Algorithm for Heavy-Ion Collisions at LHCEnergies (open access)

A Cone Jet-Finding Algorithm for Heavy-Ion Collisions at LHCEnergies

Standard jet finding techniques used in elementary particle collisions have not been successful in the high track density of heavy-ion collisions. This paper describes a modified cone-type jet finding algorithm developed for the complex environment of heavy-ion collisions. The primary modification to the algorithm is the evaluation and subtraction of the large background energy, arising from uncorrelated soft hadrons, in each collision. A detailed analysis of the background energy and its event-by-event fluctuations has been performed on simulated data, and a method developed to estimate the background energy inside the jet cone from the measured energy outside the cone on an event-by-event basis. The algorithm has been tested using Monte-Carlo simulations of Pb+Pb collisions at {radical}s = 5.5 TeV for the ALICE detector at the LHC. The algorithm can reconstruct jets with a transverse energy of 50 GeV and above with an energy resolution of {approx} 30%.
Date: July 27, 2006
Creator: Blyth, S.-L.; Horner, M.J.; Awes, T.C.; Cormier, T.; Gray, H.M.; Klay, J.L. et al.
System: The UNT Digital Library
Monochromatic electron photoemission from diamondoid monolayers (open access)

Monochromatic electron photoemission from diamondoid monolayers

We found monochromatic electron photoemission from large-area self-assembled monolayers of a functionalized diamondoid, [121]tetramantane-6-thiol. Photoelectron spectra of the diamondoid monolayers exhibited a peak at the low-kinetic energy threshold; up to 68percent of all emitted electrons were emitted within this single energy peak. The intensity of the emission peak is indicative of diamondoids being negative electron affinity materials. With an energy distribution width of less than 0.5 electron volts, this source of monochromatic electrons may find application in technologies such as electron microscopy, electron beam lithography, and field-emission flatpanel displays.
Date: February 27, 2007
Creator: Yang, Wanli; Yang, Wanli L.; Fabbri, J. D.; Willey, T. M.; Lee, J. R. I.; Dahl, J. E. et al.
System: The UNT Digital Library
A HIGH CURRENT, HIGH VOLTAGE SOLID-STATE PULSE GENERATOR FOR THE NIF PLASMA ELECTRODE POCKELS CELL (open access)

A HIGH CURRENT, HIGH VOLTAGE SOLID-STATE PULSE GENERATOR FOR THE NIF PLASMA ELECTRODE POCKELS CELL

A high current, high voltage, all solid-state pulse modulator has been developed for use in the Plasma Electrode Pockels Cell (PEPC) subsystem in the National Ignition Facility. The MOSFET-switched pulse generator, designed to be a more capable plug-in replacement for the thyratron-switched units currently deployed in NIF, offers unprecedented capabilities including burst-mode operation, pulse width agility and a steady-state pulse repetition frequency exceeding 1 Hz. Capable of delivering requisite fast risetime, 17 kV flattop pulses into a 6 {Omega} load, the pulser employs a modular architecture characteristic of the inductive adder technology, pioneered at LLNL for use in acceleration applications, which keeps primary voltages low (and well within the capabilities of existing FET technology), reduces fabrication costs and is amenable to rapid assembly and quick field repairs.
Date: July 27, 2007
Creator: Arnold, P. A.; Barbosa, F.; Cook, E. G.; Hickman, B. C.; Akana, G. L. & Brooksby, C. A.
System: The UNT Digital Library
Preparation and Reactions of Base-FreeBis(1,2,4-tri-tert-butylcyclopentadienyl)uranium Methylimide, Cp'2U=NMe,and Related Compounds (open access)

Preparation and Reactions of Base-FreeBis(1,2,4-tri-tert-butylcyclopentadienyl)uranium Methylimide, Cp'2U=NMe,and Related Compounds

The uranium metallocenes, [eta5-1,3-(Me3E)2C5H3]2UMe2 (E =C, Si), react with NH3 to give the dimers{[eta5-1,3-(Me3E)2C5H3]2U}2(mu-NH)2 (E = C (1), Si (2)) but withp-toluidine to give the monomeric diamides,[eta5-1,3-(Me3E)2C5H3]2U(NH-p-tolyl)2 (E = C (3), Si (4)). The diamides[eta5-1,3-(Me3E)2C5H3]2U(NH-p-tolyl)2 (E = C (3), Si (4)) do noteliminate p- toluidine but sublime intact at 140oC in vacuum. The uraniummetallocene, [eta5-1,2,4-(Me3C)3C5H2]2UMe2, reacts with RNH2 to yield[eta5-1,2,4-(Me3C)3C5H2]2U(NHR)2 (R = Me (8), PhCH2 (9), p-tolyl (10)),which are isolated as crystalline solids. In benzene solution thesediamides are in equilibrium with [eta5-1,2,4-(Me3C)3C5H2]2U=NR, which maybe isolated pure when R is Me (11) or p-tolyl (12), and the primaryamine. The monomeric imide, [eta5-1,2,4-(Me3C)3C5H2]2U=NMe (11), reactswith R'=CR' to yield the cycloaddition products[eta5-1,2,4-(Me3C)3C5H2]2U[N(Me)C(R')=C(R')](R' = Me (15), Ph (16)),which react with excess MeNH2 to regenerate the diamide[eta5-1,2,4-(Me3C)3C5H2]2U(NHMe)2 (8) and MeN=C(R')CH(R'). Themethylimide, [eta5-1,2,4-(Me3C)3C5H2]2U=NMe (11), does not react withMe3SiX reagents; a model is proposed that rationalizes this reactivitypattern.
Date: May 27, 2005
Creator: Zi, Guofu; Blosch, Laura L.; Jia, Li & Andersen, Richard A.
System: The UNT Digital Library
Proceedings of RIKEN BNL Research Center Workshop: Understanding QGP through Spectral Functions and Euclidean Correlators (Volume 89) (open access)

Proceedings of RIKEN BNL Research Center Workshop: Understanding QGP through Spectral Functions and Euclidean Correlators (Volume 89)

In the past two decades, one of the most important goals of the nuclear physics community has been the production and characterization of the new state of matter--Quark-Gluon Plasma (QGP). Understanding how properties of hadrons change in medium, particularly, the bound state of a very heavy quark and its antiquark, known as quarkonium, as well as determining the transport coefficients is crucial for identifying the properties of QGP and for the understanding of the experimental data from RHIC. On April 23rd, more than sixty physicists from twenty-seven institutions gathered for this three-day topical workshop held at BNL to discuss how to understand the properties of the new state of matter obtained in ultra-relativistic heavy ion collisions (particularly at RHIC-BNL) through spectral functions. In-medium properties of the different particle species and the transport properties of the medium are encoded in spectral functions. The former could yield important signatures of deconfinement and chiral symmetry restoration at high temperatures and densities, while the later are crucial for the understanding of the dynamics of ultra-relativistic heavy ion collisions. Participants at the workshop are experts in various areas of spectral function studies. The workshop encouraged direct exchange of scientific information among experts, as well as …
Date: June 27, 2008
Creator: Mocsy, A. & Petreczky, P.
System: The UNT Digital Library
Understanding Modern Magnets through Conformal Mapping (open access)

Understanding Modern Magnets through Conformal Mapping

When I had to choose, within some narrow range, the topic of this paper, I received great help from a colleague in Berkeley and from Prof. Little when it was suggested that I should pick among the possible subjects of my talk the subject that Prof. Bloch would have enjoyed most. Since Prof. Bloch would prefer a scalpel over a sword every time, I hope and think that most people will approve my choice. When one intends to talk about a subject that is as old as conformal mapping and one does not want to lose the audience in a very short time, it is advisable to start by explaining both the motivation for the talk as well as the goals one has in mind when giving the talk. This particular talk has been motivated by the increasing frequency with which one hears, from people that ought to know better, statements like: 'Conformal mapping is really a thing of the past because of all the marvelous computer programs that we now have'. Even though, or more likely because, I have been intimately involved in the development of some large and widely used computer codes, I am deeply disturbed by such …
Date: October 27, 1989
Creator: Halbach, K.
System: The UNT Digital Library
Surface structure of CdSe Nanorods revealed by combined X-rayabsorption fine structure measurements and ab-initio calculations (open access)

Surface structure of CdSe Nanorods revealed by combined X-rayabsorption fine structure measurements and ab-initio calculations

We report orientation-specific, surface-sensitive structural characterization of colloidal CdSe nanorods with extended X-ray absorption fine structure spectroscopy and ab-initio density functional theory calculations. Our measurements of crystallographically-aligned CdSe nanorods show that they have reconstructed Cd-rich surfaces. They exhibit orientation-dependent changes in interatomic distances which are qualitatively reproduced by our calculations. These calculations reveal that the measured interatomic distance anisotropy originates from the nanorod surface.
Date: January 27, 2006
Creator: Aruguete, Deborah A.; Marcus, Matthew A.; Li, Liang-shi; Williamson, Andrew; Fakra, Sirine; Gygi, Francois et al.
System: The UNT Digital Library
Quantifying the importance of orbital over spin correlations in delta-Pu within density-functional theory (open access)

Quantifying the importance of orbital over spin correlations in delta-Pu within density-functional theory

Spin and orbital and electron correlations are known to be important when treating the high-temperature {delta} phase of plutonium within the framework of density-functional theory (DFT). One of the more successful attempts to model {delta}-Pu within this approach has included condensed-matter generalizations of Hund's three rules for atoms, i.e., spin polarization, orbital polarization, and spin-orbit coupling. Here they perform a quantitative analysis of these interactions relative rank for the bonding and electronic structure in {delta}-Pu within the DFT model. The result is somewhat surprising in that spin-orbit coupling and orbital polarization are far more important than spin polarization for a realistic description of {delta}-Pu. They show that these orbital correlations on their own, without any formation of magnetic spin moments, can account for the low atomic density of the {delta} phase with a reasonable equation-of-state. In addition, this unambiguously non-magnetic (NM) treatment produces a one-electron spectra with resonances close to the Fermi level consistent with experimental valence band photoemission spectra.
Date: July 27, 2007
Creator: Soderlind, P & Wolfer, W
System: The UNT Digital Library
Extracellular Proteins Limit the Dispersal of BiogenicNanoparticles (open access)

Extracellular Proteins Limit the Dispersal of BiogenicNanoparticles

High spatial-resolution secondaryion microprobespectrometry, synchrotron radiation Fourier-transform infraredspectroscopy and polyacrylamide gel analysis demonstrate the intimateassociation of proteins with spheroidal aggregates of biogenic zincsulfide nanocrystals, an example of extracellular biomineralization.Experiments involving synthetic ZnS nanoparticles and representativeamino acids indicate a driving role for cysteine in rapid nanoparticleaggregation. These findings suggest that microbially-derivedextracellular proteins can limit dispersal of nanoparticulatemetal-bearing phases, such as the mineral products of bioremediation,that may otherwise be transported away from their source by subsurfacefluid flow.
Date: April 27, 2007
Creator: Moreau, John W.; Weber, Peter K.; Martin, Michael C.; Gilbert,Benjamin; Hutcheon, Ian D. & Banfield, Jillian F.
System: The UNT Digital Library
Gauge Mediation Simplified (open access)

Gauge Mediation Simplified

None
Date: January 27, 2007
Creator: Murayama, Hitoshi & Nomura, Yasunori
System: The UNT Digital Library
Coordination of Retail Demand Response with Midwest ISO Markets (open access)

Coordination of Retail Demand Response with Midwest ISO Markets

The Organization of Midwest ISO States (OMS) launched the Midwest Demand Resource Initiative (MWDRI) in 2007 to identify barriers to deploying demand response (DR) resources in the Midwest Independent System Operator (MISO) region and develop policies to overcome them. The MWDRI stakeholders decided that a useful initial activity would be to develop more detailed information on existing retail DR programs and dynamic pricing tariffs, program rules, and utility operating practices. This additional detail could then be used to assess any"seams issues" affecting coordination and integration of retail DR resources with MISO's wholesale markets. Working with state regulatory agencies, we conducted a detailed survey of existing DR programs, dynamic pricing tariffs, and their features in MISO states. Utilities were asked to provide information on advance notice requirements to customers, operational triggers used to call events (e.g. system emergencies, market conditions, local emergencies), use of these DR resources to meet planning reserves requirements, DR resource availability (e.g., seasonal, annual), participant incentive structures, and monitoring and verification (M&V) protocols. This report describes the results of this comprehensive survey and discusses policy implications for integrating legacy retail DR programs and dynamic pricing tariffs into organized wholesale markets. Survey responses from 37 MISO members and …
Date: May 27, 2008
Creator: Bharvirkar, Ranjit; Bharvirkar, Ranjit; Goldman, Charles; Heffner, Grayson & Sedano, Richard
System: The UNT Digital Library
MECHANISMS OF PHASE FORMATION IN THE VITRIFICATION OF HIGH-FERROUS SAVANNAH RIVER SITE SB2 HLW SLUDGE SURROGATE - 9300 (open access)

MECHANISMS OF PHASE FORMATION IN THE VITRIFICATION OF HIGH-FERROUS SAVANNAH RIVER SITE SB2 HLW SLUDGE SURROGATE - 9300

Phase formation mechanisms associated with the vitrification of high-ferrous Savannah River Site (SRS) Sludge Batch 2 (SB2) high level waste surrogate were studied by infrared spectroscopy (IRS) and X-ray diffraction (XRD). Two mixtures at 50 wt% waste loading with commercially available Frit 320 (Li{sub 2}O - 8 wt %, B{sub 2}O{sub 3} - 8 wt %, Na{sub 2}O - 12 wt %, SiO{sub 2} - 72 wt %) and batch chemicals (LiOH {center_dot} H{sub 2}O, H{sub 3}BO{sub 3}, NaNO{sub 3}, SiO{sub 2}) to represent the frit formulation were prepared as slurries with a water content of {approx}50 wt%. The mixtures were air-dried at a temperature of 115 C and heat-treated at 500, 700, 900, 1000, 1100, 1200, and 1300 C for 1 hr at each temperature. Infrared spectra and XRD patterns of the products produced at each temperature were recorded. In both mixtures prepared using frit and batch chemicals to represent the frit, phase formation reactions were completed within the temperature range between 900 and 1000 C. However, residual quartz was still present in glass produced from the mixture with batch chemicals even at 1100 C. Although, the phase composition and structure of the glassy products obtained from both mixtures …
Date: August 27, 2008
Creator: Marra, J
System: The UNT Digital Library
Relativistic Many-body Moller-Plesset Perturbation Theory Calculations of the Energy Levels and Transition Probabilities in Na- to P-like Xe Ions (open access)

Relativistic Many-body Moller-Plesset Perturbation Theory Calculations of the Energy Levels and Transition Probabilities in Na- to P-like Xe Ions

Relativistic multireference many-body perturbation theory calculations have been performed on Xe{sup 43+}-Xe{sup 39+} ions, resulting in energy levels, electric dipole transition probabilities, and level lifetimes. The second-order many-body perturbation theory calculation of energy levels included mass shifts, frequency-dependent Breit correction and Lamb shifts. The calculated transition energies and E1 transition rates are used to present synthetic spectra in the extreme ultraviolet range for some of the Xe ions.
Date: March 27, 2007
Creator: Vilkas, M J; Ishikawa, Y & Trabert, E
System: The UNT Digital Library
Assembly and Test of a Support Structure for 3.5 m Long Nb3Sn Racetrack Coils. (open access)

Assembly and Test of a Support Structure for 3.5 m Long Nb3Sn Racetrack Coils.

The LHC Accelerator Research Program (LARP) is currently developing 4 m long Nb{sub 3}Sn quadrupole magnets for a possible upgrade of the LHC Interaction Regions (IR). In order to provide a reliable test bed for the fabrication and test of long Nb{sub 3}Sn coils, LARP has started the development of the long racetrack magnet LRS01. The magnet is composed of two 3.6 m long racetrack coils contained in a support structure based on an aluminum shell pre-tensioned with water-pressurized bladders and interference keys. For the phase-one test of the assembly procedure and loading operation, the structure was pre-stressed at room temperature and cooled down to 77 K with instrumented, solid aluminum 'dummy coils'. Mechanical behavior and stress homogeneity were monitored with strain gauges mounted on the shell and the dummy coils. The dummy coils were replaced with reacted and impregnated Nb{sub 3}Sn coils in a second assembly procedure, followed by cool-down to 4.5 K and powered magnet test. This paper reports on the assembly and loading procedures of the support structure as well as the comparison between strain gauge data and 3D model predictions.
Date: August 27, 2007
Creator: Ferracin, P.; Ambrosio, G.; Anerella, M.; Caspi, S.; Cheng, D. W.; Felice, H. et al.
System: The UNT Digital Library
Aligned vertical fractures, HTI reservoir symmetry, and Thomsenseismic anisotropy parameters (open access)

Aligned vertical fractures, HTI reservoir symmetry, and Thomsenseismic anisotropy parameters

The Sayers and Kachanov (1991) crack-influence parametersare shown to be directly related to Thomsen (1986) weak-anisotropyseismic parameters for fractured reservoirs when the crack density issmall enough. These results are then applied to seismic wave propagationin reservoirs having HTI symmetry due to aligned vertical fractures. Theapproach suggests a method of inverting for fracture density from wavespeed data.
Date: June 27, 2007
Creator: Berryman, James G.
System: The UNT Digital Library
Quantitative models of subduction zone fluids: How hydrous phases in the slab determine the composition of subduction zone lavas (open access)

Quantitative models of subduction zone fluids: How hydrous phases in the slab determine the composition of subduction zone lavas

None
Date: May 27, 2004
Creator: Feineman, M; Ryerson, F J & DePaolo, D
System: The UNT Digital Library
HYDROGEN EFFECTS ON THE BURST PROPERTIES OF TYPE 304L STAINLESS STEEL FLAWED VESSELS (open access)

HYDROGEN EFFECTS ON THE BURST PROPERTIES OF TYPE 304L STAINLESS STEEL FLAWED VESSELS

The effect of hydrogen on the burst properties Type 304L stainless steel vessels was investigated. The purpose of the study was to compare the burst properties of hydrogen-exposed stainless steel vessels burst with different media: water, helium gas, or deuterium gas. A second purpose of the tests was to provide data for the development of a predictive finite-element model. The burst tests were conducted on hydrogen-exposed and unexposed axially-flawed cylindrical vessels. The results indicate that samples burst pneumatically had lower volume ductility than those tested hydraulically. Deuterium gas tests had slightly lower ductility than helium gas tests. Burst pressures were not affected by burst media. Hydrogen-charged samples had lower volume ductility and slightly higher burst pressures than uncharged samples. Samples burst with deuterium gas fractured by quasi-cleavage near the inside wall. The results of the tests were used to improve a previously developed predictive finite-element model. The results show that predicting burst behavior requires as a material input the effect of hydrogen on the plastic strain to fracture from tensile tests. The burst test model shows that a reduction in the plastic strain to fracture of the material will result in lower volume ductility without a reduction in burst pressure …
Date: March 27, 2008
Creator: Morgan, M; Monica Hall, M; Ps Lam, P & Dean Thompson, D
System: The UNT Digital Library
Improved Bacterial and Viral Recoveries from 'Complex' Samples using Electrophoretically Assisted Acoustic Focusing (open access)

Improved Bacterial and Viral Recoveries from 'Complex' Samples using Electrophoretically Assisted Acoustic Focusing

Automated front-end sample preparation technologies can significantly enhance the sensitivity and reliability of biodetection assays [1]. We are developing advanced sample preparation technologies for biowarfare detection and medical point-of-care diagnostics using microfluidic systems with continuous sample processing capabilities. Here we report an electrophoretically assisted acoustic focusing technique to rapidly extract and enrich viral and bacterial loads from 'complex samples', applied in this case to human nasopharyngeal samples as well as simplified surrogates. The acoustic forces capture and remove large particles (> 2 {micro}m) such as host cells, debris, dust, and pollen from the sample. We simultaneously apply an electric field transverse to the flow direction to transport small ({le} 2 {micro}m), negatively-charged analytes into a separate purified recovery fluid using a modified H-filter configuration [Micronics US Patent 5,716,852]. Hunter and O'Brien combined transverse electrophoresis and acoustic focusing to measure the surface charge on large particles, [2] but to our knowledge, our work is the first demonstration combining these two techniques in a continuous flow device. Marina et al. demonstrated superimposed dielectrophoresis (DEP) and acoustic focusing for enhanced separations [3], but these devices have limited throughput due to the rapid decay of DEP forces. Both acoustic standing waves and electric fields …
Date: March 27, 2008
Creator: Ness, K.; Rose, K.; Jung, B.; Fisher, K. & Mariella, R. P., Jr.
System: The UNT Digital Library