Reversible Guest Exchange Mechanisms in Supramolecular Host-Guest Assemblies (open access)

Reversible Guest Exchange Mechanisms in Supramolecular Host-Guest Assemblies

Synthetic chemists have provided a wide array of supramolecular assemblies able to encapsulate guest molecules. The scope of this tutorial review focuses on supramolecular host molecules capable of reversibly encapsulating polyatomic guests. Much work has been done to determine the mechanism of guest encapsulation and guest release. This review covers common methods of monitoring and characterizing guest exchange such as NMR, UV-VIS, mass spectroscopy, electrochemistry, and calorimetry and also presents representative examples of guest exchange mechanisms. The guest exchange mechanisms of hemicarcerands, cucurbiturils, hydrogen-bonded assemblies, and metal-ligand assemblies are discussed. Special attention is given to systems which exhibit constrictive binding, a motif common in supramolecular guest exchange systems.
Date: September 1, 2006
Creator: Pluth, Michael D. & Raymond, Kenneth N.
System: The UNT Digital Library
Optomechanical considerations for the VISAR diagnostic at the National Ignition Facility (NIF) (open access)

Optomechanical considerations for the VISAR diagnostic at the National Ignition Facility (NIF)

The National Ignition Facility (NIF) requires optical diagnostics for measuring shock velocities in shock physics experiments. The velocity interferometer for any reflector measures shock velocities at a location remote to the NIF target chamber. Our team designed two systems, one for a polar port orientation, and the other to accommodate two equatorial ports. The polar-oriented design requires a 48-m optical relay to move the light from inside the target chamber to a separately housed measurement and laser illumination station. The currently operational equatorial design requires a much shorter relay of 21 m. Both designs posed significant optomechanical challenges due to the long optical path length, large quantity of optical elements, and stringent NIF requirements. System design had to tightly control the use of lubricants and materials, especially those inside the vacuum chamber; tolerate earthquakes and radiation; and consider numerous other tolerance, alignment, and steering adjustment issues. To ensure compliance with NIF performance requirements, we conducted a finite element analysis.
Date: September 1, 2006
Creator: Kaufman, Morris I.; Celeste, John R.; Frogget, Brent C.; Lee, Tony L.; GacGowan, Brian J.; Malone, Robert M. et al.
System: The UNT Digital Library
Microprocessor-controlled, wide-range streak camera (open access)

Microprocessor-controlled, wide-range streak camera

Bechtel Nevada/NSTec recently announced deployment of their fifth generation streak camera. This camera incorporates many advanced features beyond those currently available for streak cameras. The arc-resistant driver includes a trigger lockout mechanism, actively monitors input trigger levels, and incorporates a high-voltage fault interrupter for user safety and tube protection. The camera is completely modular and may deflect over a variable full-sweep time of 15 nanoseconds to 500 microseconds. The camera design is compatible with both large- and small-format commercial tubes from several vendors. The embedded microprocessor offers Ethernet connectivity, and XML [extensible markup language]-based configuration management with non-volatile parameter storage using flash-based storage media. The camera’s user interface is platform-independent (Microsoft Windows, Unix, Linux, Macintosh OSX) and is accessible using an AJAX [asynchronous Javascript and XML]-equipped modem browser, such as Internet Explorer 6, Firefox, or Safari. User interface operation requires no installation of client software or browser plug-in technology. Automation software can also access the camera configuration and control using HTTP [hypertext transfer protocol]. The software architecture supports multiple-simultaneous clients, multiple cameras, and multiple module access with a standard browser. The entire user interface can be customized.
Date: September 1, 2006
Creator: Amy E. Lewis, Craig Hollabaugh
System: The UNT Digital Library
Limits of NbTi and Nb3Sn, and Development of W&R Bi-2212 HighField Accelerator Magnets (open access)

Limits of NbTi and Nb3Sn, and Development of W&R Bi-2212 HighField Accelerator Magnets

NbTi accelerator dipoles are limited to magneticfields (H)of about 10 T, due to an intrinsic upper critical field (Hc2) limitationof 14 T. To surpass this restriction, prototype Nb3Sn magnets are beingdeveloped which have reached 16 T. We show that Nb3Sn dipole technologyis practically limited to 17 to 18 T due to insufficient high fieldpinning, and intrinsically to 20 to 22 T due to Hc2 limitations.Therefore, to obtain magnetic fields approaching 20 T and higher, amaterial is required with a higher Hc2 and sufficient high field pinningcapacity. A realistic candidate for this purpose is Bi-2212, which isavailable in roundwires and sufficient lengths for the fabrication ofcoils based on Rutherford-type cables. We initiated a program to developthe required technology to construct accelerator magnets from'windand-react' (W&R) Bi-2212 coils. We outline the complicationsthat arise through the use of Bi-2212, describe the development paths toaddress these issues, and conclude with the design of W&R Bi-2212sub-scale magnets.
Date: September 1, 2006
Creator: Godeke, A.; Cheng, D.; Dietderich, D. R.; Ferracin, P.; Prestemon, S. O.; Sabbi, G. et al.
System: The UNT Digital Library
Design of a Thermal Imaging Diagnostic Using 90-Degree, Off-Axis, Parabolic Mirrors (open access)

Design of a Thermal Imaging Diagnostic Using 90-Degree, Off-Axis, Parabolic Mirrors

Thermal imaging is an important, though challenging, diagnostic for shockwave experiments. Shock-compressed materials undergo transient temperature changes that cannot be recorded with standard (greater than ms response time) infrared detectors. A further complication arises when optical elements near the experiment are destroyed. We have designed a thermal-imaging system for studying shock temperatures produced inside a gas gun at Sandia National Laboratories. Inexpensive, diamond-turned, parabolic mirrors relay an image of the shocked target to the exterior of the gas gun chamber through a sapphire vacuum port. The 3000–5000-nm portion of this image is directed to an infrared camera which acquires a snapshot of the target with a minimum exposure time of 150 ns. A special mask is inserted at the last intermediate image plane, to provide dynamic thermal background recording during the event. Other wavelength bands of this image are split into high-speed detectors operating at 900–1700 nm, and at 1700–3000 nm for timeresolved pyrometry measurements. This system incorporates 90-degree, off-axis parabolic mirrors, which can collect low f/# light over a broad spectral range, for high-speed imaging. Matched mirror pairs must be used so that aberrations cancel. To eliminate image plane tilt, proper tip-to-tip orientation of the parabolic mirrors is required. …
Date: September 1, 2006
Creator: Malone, Robert M.; Becker, Steven A.; Dolan, Daniel H.; Hacking, Richard G.; Hickman, Randy J.; Kaufman, Morris I. et al.
System: The UNT Digital Library
Loss of Bacterial Diversity During Antibiotic Treatment ofIntubated Patients Colonized with Pseudomonas aeruginosa (open access)

Loss of Bacterial Diversity During Antibiotic Treatment ofIntubated Patients Colonized with Pseudomonas aeruginosa

None
Date: September 1, 2006
Creator: Flanagan, J. L.; Weng, L.; Brodie, E. L.; Lynch, S. V.; Garcia, O.; Brown, R. et al.
System: The UNT Digital Library
Identity of Passive Film Formed on Aluminum in Li-ion BatteryElectrolytes with LiPF6 (open access)

Identity of Passive Film Formed on Aluminum in Li-ion BatteryElectrolytes with LiPF6

The passive film that forms on aluminum in 1:1 ethylene carbonate + ethylmethyl carbonate with 1.2M LiPF{sub 6} and 1:1 ethylene carbonate + dimethyl carbonate with 1.0M LiPF{sub 6} was investigated by a combination of electrochemical quartz crystal microbalance measurements (EQCM), electrochemical impedance spectroscopy (EIS), and x-ray photoelectron spectroscopy. During anodic polarization of aluminum a film of AlF{sub 3} forms on top of the air-formed oxide, creating a duplex, or two-layered film. The thickness of the AlF{sub 3} increases with the applied potential. Independent measurements of film thickness by EQCM and EIS indicate that at a potential of 5.5V vs. Li/Li{sup +}, the thickness of the AlF{sub 3} is approximately 1 nm.
Date: September 1, 2006
Creator: Zhang, Xueyuan & Devine, T.M.
System: The UNT Digital Library
Supersymmetry searches at the Tevatron (open access)

Supersymmetry searches at the Tevatron

CDF and D0 detectors have already collected 1.3 fb{sup -1} of data delivered by the Tevatron collider at 1.96 TeV center-of-mass energy. We present here the various analyses that are currently testing the possibility of a supersymmetric extension of the Standard Model. No evidence for such processes have been found in luminosities that range from 300 to 800 pb{sup -1} and different limits on the different supersymmetric models are set. Constraints coming from indirect searches are also presented.
Date: September 1, 2006
Creator: Portell, Xavier
System: The UNT Digital Library
Developing Multiple Diverse Potential Designs for Heat Transfer Utilizing Graph Based Evolutionary Algorithms (open access)

Developing Multiple Diverse Potential Designs for Heat Transfer Utilizing Graph Based Evolutionary Algorithms

This paper examines the use of graph based evolutionary algorithms (GBEAs) to find multiple acceptable solutions for heat transfer in engineering systems during the optimization process. GBEAs are a type of evolutionary algorithm (EA) in which a topology, or geography, is imposed on an evolving population of solutions. The rates at which solutions can spread within the population are controlled by the choice of topology. As in nature geography can be used to develop and sustain diversity within the solution population. Altering the choice of graph can create a more or less diverse population of potential solutions. The choice of graph can also affect the convergence rate for the EA and the number of mating events required for convergence. The engineering system examined in this paper is a biomass fueled cookstove used in developing nations for household cooking. In this cookstove wood is combusted in a small combustion chamber and the resulting hot gases are utilized to heat the stove’s cooking surface. The spatial temperature profile of the cooking surface is determined by a series of baffles that direct the flow of hot gases. The optimization goal is to find baffle configurations that provide an even temperature distribution on the …
Date: September 1, 2006
Creator: Jr., David J. Muth
System: The UNT Digital Library
W and Z production at the Tevatron (open access)

W and Z production at the Tevatron

In this paper, recent experimental results on W and Z boson production at the Tevatron are described. These results not only provide tests of the standard model, but are also sensitive to proton parton distribution functions.
Date: September 1, 2006
Creator: Sanders, Michiel P.
System: The UNT Digital Library
Measurement of the top quark mass in the lepton+jets final state with the matrix element method (open access)

Measurement of the top quark mass in the lepton+jets final state with the matrix element method

We present a measurement of the top quark mass with the Matrix Element method in the lepton+jets final state. As the energy scale for calorimeter jets represents the dominant source of systematic uncertainty, the Matrix Element likelihood is extended by an additional parameter, which is defined as a global multiplicative factor applied to the standard energy scale. The top quark mass is obtained from a fit that yields the combined statistical and systematic jet energy scale uncertainty.
Date: September 1, 2006
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
System: The UNT Digital Library
Roll measurement of Tevatron dipoles and quadrupoles (open access)

Roll measurement of Tevatron dipoles and quadrupoles

In 2003 a simple digital level system was developed to allow for rapid roll measurements of all dipoles and quadrupoles in the Tevatron. The system uses a Mitutoyo digital level and a PC running MS WINDOWS XP and LAB VIEW to acquire data on the upstream and downstream roll of each magnet. The system is sufficiently simple that all 1,000 magnets in the Tevatron can be measured in less than 3 days. The data can be quickly processed allowing for correction of rolled magnets by the Fermilab alignment group. Data will be presented showing the state of the Tevatron in 2003 and the changes in rolls as measured in each shutdown since then.
Date: September 1, 2006
Creator: Volk, J.T.; Elementi, L.; Gollwitzer, K.; Jostlein, H.; Nobrega, F.; Shiltsev, V. et al.
System: The UNT Digital Library
The Standard model: Alchemy and astrology (open access)

The Standard model: Alchemy and astrology

A brief unconventional review of Standard Model physics, containing no plots.
Date: September 1, 2006
Creator: Lykken, Joseph D.
System: The UNT Digital Library
A Review of Software-Induced Failure Experience. (open access)

A Review of Software-Induced Failure Experience.

We present a review of software-induced failures in commercial nuclear power plants (NPPs) and in several non-nuclear industries. We discuss the approach used for connecting operational events related to these failures and the insights gained from this review. In particular, we elaborate on insights that can be used to model this kind of failure in a probabilistic risk assessment (PRA) model. We present the conclusions reached in these areas.
Date: September 1, 2006
Creator: Chu, T. L.; Martinez-Guridi, G.; Yue, M. & Lehner, J.
System: The UNT Digital Library
The CDF II eXtremely fast tracker upgrade (open access)

The CDF II eXtremely fast tracker upgrade

The CDF II Extremely Fast Tracker is the trigger track processor which reconstructs charged particle tracks in the transverse plane of the CDF II central outer tracking chamber. The system is now being upgraded to perform a three dimensional track reconstruction. A review of the upgrade is presented here.
Date: September 1, 2006
Creator: Abulencia, A.; Azzurri, P.; Cochran, E.; Dittmann, J.; Donati, S.; Efron, J. et al.
System: The UNT Digital Library
Higgs searches at Tevatron (open access)

Higgs searches at Tevatron

SM and MSSM Higgs Searches at the proton anti-proton collider Tevatron in Run II are presented. The performance of the collider and the two experiments D0 and CDF is shown. No deviation from SM background expectation and no MSSM Higgs signal has been observed.
Date: September 1, 2006
Creator: Sonnenschein, Lars
System: The UNT Digital Library
Development of 3D integrated circuits for HEP (open access)

Development of 3D integrated circuits for HEP

Three dimensional integrated circuits are well suited to improving circuit bandwidth and increasing effective circuit density. Recent advances in industry have made 3D integrated circuits an option for HEP. The 3D technology is discussed in this paper and several examples are shown. Design of a 3D demonstrator chip for the ILC is presented.
Date: September 1, 2006
Creator: Yarema, R.
System: The UNT Digital Library
B masses and lifetimes at the Tevatron (open access)

B masses and lifetimes at the Tevatron

The authors review recent results of B{sup ++} masses, mass and lifetime of B{sub c}{sup +} meson, and lifetimes of B{sub s}{sup 0} and {Lambda}{sub b}{sup 0} hadrons from Tevatron Run II.
Date: September 1, 2006
Creator: Uozumi, Satoru
System: The UNT Digital Library
Measurement of Angular Distributions of Drell-Yan Dimuons in p + d Interaction at 800-GeV/c (open access)

Measurement of Angular Distributions of Drell-Yan Dimuons in p + d Interaction at 800-GeV/c

None
Date: September 1, 2006
Creator: Zhu, L. Y.; Peng, J. C.; Reimer, P. E.; Awes, T. C.; Brooks, M. L.; Brown, C. N. et al.
System: The UNT Digital Library
FLUID FLOW, SOLUTE MIXING AND PRECIPITATION IN POROUS MEDIA (open access)

FLUID FLOW, SOLUTE MIXING AND PRECIPITATION IN POROUS MEDIA

Reactions that lead to the formation of mineral precipitates, colloids or growth of biofilms in porous media often depend on the molecular-level diffusive mixing. For example, for the formation of mineral phases, exceeding the saturation index for a mineral is a minimum requirement for precipitation to proceed. Solute mixing frequently occurs at the interface between two solutions each containing one or more soluble reactants, particularly in engineered systems where contaminant degradation or modification or fluid flow are objectives. Although many of the fundamental component processes involved in the deposition or solubilization of solid phases are reasonably well understood, including precipitation equilibrium and kinetics, fluid flow and solute transport, the deposition of chemical precipitates, biofilms and colloidal particles are all coupled to flow, and the science of such coupled processes is not well developed. How such precipitates (and conversely, dissolution of solids) are distributed in the subsurface along flow paths with chemical gradients is a complex and challenging problem. This is especially true in systems that undergo rapid change where equilibrium conditions cannot be assumed, particularly in subsurface systems where reactants are introduced rapidly, compared to most natural flow conditions, and where mixing fronts are generated. Although the concept of dispersion …
Date: September 1, 2006
Creator: Redden, George D; Fang, Y.; Scheibe, T.D.; Tartakovsky, A.M.; Fox, Don T; Fujita, Yoshiko et al.
System: The UNT Digital Library
An Enhanced GINGERSimulation Code with Harmonic Emission and HDF5IO Capabilities (open access)

An Enhanced GINGERSimulation Code with Harmonic Emission and HDF5IO Capabilities

GINGER [1] is an axisymmetric, polychromatic (r-z-t) FEL simulation code originally developed in the mid-1980's to model the performance of single-pass amplifiers. Over the past 15 years GINGER's capabilities have been extended to include more complicated configurations such as undulators with drift spaces, dispersive sections, and vacuum chamber wakefield effects; multi-pass oscillators; and multi-stage harmonic cascades. Its coding base has been tuned to permit running effectively on platforms ranging from desktop PC's to massively parallel processors such as the IBM-SP. Recently, we have made significant changes to GINGER by replacing the original predictor-corrector field solver with a new direct implicit algorithm, adding harmonic emission capability, and switching to the HDF5 IO library [2] for output diagnostics. In this paper, we discuss some details regarding these changes and also present simulation results for LCLS SASE emission at {lambda} = 0.15 nm and higher harmonics.
Date: September 1, 2006
Creator: Fawley, William M.
System: The UNT Digital Library
The Kaon B-parameter in mixed action chiral perturbation theory (open access)

The Kaon B-parameter in mixed action chiral perturbation theory

We calculate the kaon B-parameter, B{sub K}, in chiral perturbation theory for a partially quenched, mixed action theory with Ginsparg-Wilson valence quarks and staggered sea quarks. We find that the resulting expression is similar to that in the continuum, and in fact has only two additional unknown parameters. At one-loop order, taste-symmetry violations in the staggered sea sector only contribute to flavor-disconnected diagrams by generating an {Omicron}(a{sup 2}) shift to the masses of taste-singlet sea-sea mesons. Lattice discretization errors also give rise to an analytic term which shifts the tree-level value of B{sub K} by an amount of {Omicron}(a{sup 2}). This term, however, is not strictly due to taste-breaking, and is therefore also present in the expression for B{sub K} for pure G-W lattice fermions. We also present a numerical study of the mixed B{sub K} expression in order to demonstrate that both discretization errors and finite volume effects are small and under control on the MILC improved staggered lattices.
Date: September 1, 2006
Creator: Aubin, C.; Laiho, Jack & Van de Water, Ruth S.
System: The UNT Digital Library
Hydro static water level systems at Fermilab (open access)

Hydro static water level systems at Fermilab

Several Hydrostatic Water Leveling systems (HLS) are in use at Fermilab. Three systems are used to monitor quadrupoles in the Tevatron and two systems are used to monitor ground motion for potential sites for the International Linear Collider (ILC). All systems use capacitive sensors to determine the water level of water in a pool. These pools are connected with tubing so that relative vertical shifts between sensors can be determined. There are low beta quadrupoles at the B0 and D0 interaction regions of Tevatron accelerator. These quadrupoles use BINP designed and built sensors and have a resolution of 1 micron. All regular lattice superconducting quadrupoles (a total of 204) in the Tevatron use a Fermilab designed system and have a resolution of 6 microns. Data on quadrupole motion due to quenches, changes in temperature will be presented. In addition data for ground motion for ILC studies caused by natural and cultural factors will be presented.
Date: September 1, 2006
Creator: Volk, J.T.; Guerra, J.A.; Hansen, S.U.; Kiper, T.E.; Jostlein, H.; Shiltsev, V. et al.
System: The UNT Digital Library
VHTR Prismatic Super Lattice Model for Equilibrium Fuel Cycle Analysis (open access)

VHTR Prismatic Super Lattice Model for Equilibrium Fuel Cycle Analysis

The advanced Very High Temperature gas-cooled Reactor (VHTR), which is currently being developed, achieves simplification of safety through reliance on innovative features and passive systems. One of the VHTRs innovative features is the reliance on ceramic-coated fuel particles to retain the fission products under extreme accident conditions. The effect of the random fuel kernel distribution in the fuel prismatic block is addressed through the use of the Dancoff correction factor in the resonance treatment. However, if the fuel kernels are not perfect black absorbers, the Dancoff correction factor is a function of burnup and fuel kernel packing factor, which requires that the Dancoff correction factor be updated during Equilibrium Fuel Cycle (EqFC) analysis. An advanced Kernel-by-Kernel (K-b-K) hexagonal super lattice model can be used to address and update the burnup dependent Dancoff effect during the EqFC analysis. The developed Prismatic Super Homogeneous Lattice Model (PSHLM) is verified by comparing the calculated burnup characteristics of the double-heterogeneous Prismatic Super Kernel-by-Kernel Lattice Model (PSK-b-KLM). This paper summarizes and compares the PSHLM and PSK-b-KLM burnup analysis study and results. This paper also discusses the coupling of a Monte-Carlo code with fuel depletion and buildup code, which provides the fuel burnup analysis tool used …
Date: September 1, 2006
Creator: Chang, G. S.
System: The UNT Digital Library