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On Carrier Facilitated Transport Through Membranes

Description: Facilitated transport is a process, whereby the diffusion of a solute across a membrane is chemically enhanced. In this report an analysis is given of a facilitated transport system involving a volatile species A which reacts with a nonvolatile carrier species B to form the nonvolatile product AB.
Date: June 1980
Creator: Kaper, H. G.; Leaf, G. K. & Matkowsky, Bernard J.
Partner: UNT Libraries Government Documents Department

Scale dependence of the effective matrix diffusion coefficient:some analytical results

Description: Matrix diffusion is an important process affecting solutetransport in fractured rock, and the matrix diffusion coefficient is akey parameter for describing this process. Previous studies haveindicated that the effective matrix-diffusion coefficient values,obtained from a number of field tracer tests, are enhanced in comparisonwith local values and may increase with test scale. In thiscommunication, we develop analytical expressions for the effective matrixdiffusion coefficient for two simple fracture-matrix systems, anddemonstrate that heterogeneities in the rock matrix at different scalescontribute to the scale dependence of the effective matrix diffusioncoefficient.
Date: May 30, 2005
Creator: Liu, H.H.; Zhang, Y.Q. & Molz, F.J.
Partner: UNT Libraries Government Documents Department

Transport-Depletion Desalination Pilot Plant

Description: From Summary: "The transport-depletion data obtained by the Southern Research Institute and by the Bureau of Reclamation at Denver, Colorado and at Webster, South Dakota, was reviewed. This data review made it possible to develop a design methodology for the pilot plant, and to identify the additional data required to adequately predict the performance of a transport-depletion stack."
Date: April 1971
Creator: Redman, Ralph
Partner: UNT Libraries Government Documents Department

Trajectory versus probability density entropy

Description: In this article, the authors show that the widely accepted conviction that a connection can be established between the probability density entropy and the Kolmogorov-Sinai (KS) entropy is questionable.
Date: 2001
Creator: Bologna, Mauro; Grigolini, Paolo; Karagiorgis, Markos & Rosa, Angelo
Partner: UNT College of Arts and Sciences

Synthesis Strategies and a Study of Properties of Narrow and Wide Band Gap Nanowires

Description: Various techniques to synthesize nanowires and nanotubes as a function of growth temperature and time were investigated. These include growth of nanowires by a chemical vapor deposition (CVD) system using vapor-liquid-solid (VLS) growth mechanism and electro-chemical synthesis of nanowires and nanotubes. Narrow band gap InSb Eg = 0.17 eV at room temp) nanowires were successively synthesized. Using a phase diagram, the transition of the nanowire from metallic- semiconducting- semi-metallic phase was investigated. A thermodynamic model is developed to show that the occurrence of native defects in InSb nanowires influenced by the nanowire growth kinetics and thermodynamics of defect formation. Wide band gap ZnO (Eg = 3.34 eV) and In2O3 (3.7 eV) were also synthesized. ZnO nanowires and nanotubes were successfully doped with a transition metal Fe, making it a Dilute Magnetic Semiconductor of great technological relevance. Structural and electronic characterizations of nanowires were studied for different semiconducting, metallic and semi-metallic nanowires. Electron transport measurements were used to estimate intrinsic material parameters like carrier concentration and mobility. An efficient gas sensing device using a single In2O3 nanowire was studied and which showed sensitivity to reducing gas like NH3 and oxidizing gas like O2 gas at room temperature. The efficiency of the gas sensing device was found to be sensitive to the nature of contacts as well as the presence of surface states on the nanowire.
Date: May 2014
Creator: Sapkota, Gopal
Partner: UNT Libraries

An analysis of the airspeeds and normal accelerations of Boeing S-307 airplanes in commercial transport operation

Description: From Introduction: "The present paper has been prepared to give the results of the analysis of the V-G records obtained from three Boeing S-307 airplanes operating in Caribbean region and the northern part of South America during the period from 1940 to 1944."
Date: September 1946
Creator: Peiser, A M & Walker, W G
Partner: UNT Libraries Government Documents Department

An analysis of the airspeeds and normal accelerations of Douglas DC-3 airplanes in commercial transport operation

Description: From Introduction: "The present report is the second prepared to give the results of an analysis of V-G data from commercial transport airplanes. The present report is concerned with an analysis of data obtained with Douglas DC-3 airplanes flying over three transcontinental routes in the United States."
Date: September 1946
Creator: Peiser, A M
Partner: UNT Libraries Government Documents Department

An analysis of acceleration, airspeed, and gust-velocity data from one type of four-engine transport airplane operated over two domestic routes

Description: From Introduction: "As part of a continuing study of the gust and load histories for transport airplanes (see, for example, refs. 1 and 2), samples of VGH records have been obtained from two four-engine commercial transport airplanes. The data samples represent 839 and 1,080 flight hours of operation on two transcontinental routes and cover operations up to an altitude of 25,000 feet."
Date: October 1, 1955
Creator: Coleman, Thomas L & Copp, Martin R
Partner: UNT Libraries Government Documents Department

An analysis of accelerations, airspeeds, and gust velocities from three commercial operations of one type of medium-altitude transport airplane

Description: From Introduction: "Past analyses of data from the NACA V-G and the NACA VGH recorders (see, for example, refs. 1 and 2) have yielded information on the magnitude and frequency of occurrence of gust and maneuver accelerations, and the associated airspeeds and altitudes for several types of airplanes flown by different operators on various routes."
Date: March 1, 1955
Creator: Coleman, Thomas L; Copp, Martin R; Engel, Jerome N & Walker, Walter G
Partner: UNT Libraries Government Documents Department

Recent advances in neutral particle transport methods and codes

Description: An overview of ORNL`s three-dimensional neutral particle transport code, TORT, is presented. Special features of the code that make it invaluable for large applications are summarized for the prospective user. Advanced capabilities currently under development and installation in the production release of TORT are discussed; they include: multitasking on Cray platforms running the UNICOS operating system; Adjacent cell Preconditioning acceleration scheme; and graphics codes for displaying computed quantities such as the flux. Further developments for TORT and its companion codes to enhance its present capabilities, as well as expand its range of applications are disucssed. Speculation on the next generation of neutron particle transport codes at ORNL, especially regarding unstructured grids and high order spatial approximations, are also mentioned.
Date: June 1, 1996
Creator: Azmy, Y.Y.
Partner: UNT Libraries Government Documents Department

Persistence and transport potential of chemicals in a multimedia environment

Description: Persistence in the environment and potential for long-range transport are related since time in the environment is required for transport. A persistent chemical will travel longer distances than a reactive chemical that shares similar chemical properties. Scheringer (1997) has demonstrated the correlation between persistence and transport distance for different organic chemicals. However, this correlation is not sufficiently robust to predict one property from the other. Specific chemicals that are persistent mayor may not exhibit long-range transport potential. Persistence and long-range transport also present different societal concerns. Persistence concerns relate to the undesired possibility that chemicals produced and used now may somehow negatively affect future generations. Long-range transport concerns relate to the undesired presence of chemicals in areas where these compounds have not been used. Environmental policy decisions can be based on either or both considerations depending on the aim of the regulatory program. In this chapter, definitions and methods for quantifying persistence and transport potential of organic chemicals are proposed which will assist in the development of sound regulatory frameworks.
Date: February 1, 2000
Creator: van de Meent, D.; McKone, T.E.; Parkerton, T.; Matthies, M.; Scheringer, M.; Wania, F. et al.
Partner: UNT Libraries Government Documents Department

Impacts of Humic Injection Experiments on the South Oyster Field Research Site

Description: A closure plan for the South Oyster Focus Area (SOFA) is being implemented to assess the impacts of a series of experimental injections of microorganisms, tracers and chemical amendments on the chemical and physical properties of the aquifer. The proposed research addresses environmental monitoring of humic substances injected into the aquifer, as described in the Site Closure Plan for the South Oyster Field Research Site. The goal of the research is to demonstrate that the dissolved organic matter (DOM) in the groundwater at and downgradient from the injection site has returned to a pre-injection �baseline� conditions with respect to either the concentration or chemical composition of the DOM. For clarity, the humic solution injected during the experiment will be referred to as �humic injectate.� The term �DOM� will refer to the organic material recovered in the groundwater, which includes the autochthonous groundwater DOM as well as any of the humic injectate remaining in the groundwater. Specific objectives include: � Estimate the amount of humic material remaining in the aquifer at the completion of the push-pull experiment and the potential for environmental impacts due to release of humics retained on the sediments. � Monitor the DOM concentrations in groundwater over time at the injection well and at sampling locations within the potential downgradient plume of the injected tracers. � Evaluate the chemical composition of the DOM to determine whether the injection experiment had an impact of the chemical properties of the aquifer. The product of this research will be a contribution to the Site Closure Report documenting the impact of the humic experiments on the aquifer. Return of the aquifer to a �baseline� conditions will be achieved if the DOM concentrations in the groundwater are determined over the course of the research to have decreased to the pre-injection level, or if ...
Date: April 27, 2004
Creator: McCarthy, John F.
Partner: UNT Libraries Government Documents Department

Transgenic approaches to altering carbon and nitrogen partitioning in whole plants: assessing the potential to improve crop yields and nutritional quality

Description: This article summarizes the key transport steps involved in organic carbon and nitrogen compound partitioning, and discusses various transgenic approaches for directly manipulating key carbon and nitrogen transporters involved.
Date: April 22, 2015
Creator: Yadav, Umesh P.; Ayre, Brian G. & Bush, Daniel R.
Partner: UNT College of Arts and Sciences

TART 2000: A Coupled Neutron-Photon, 3-D, Combinatorial Geometry, Time Dependent, Monte Carlo Transport Code

Description: TART2000 is a coupled neutron-photon, 3 Dimensional, combinatorial geometry, time dependent Monte Carlo radiation transport code. This code can run on any modern computer. It is a complete system to assist you with input Preparation, running Monte Carlo calculations, and analysis of output results. TART2000 is also incredibly FAST; if you have used similar codes, you will be amazed at how fast this code is compared to other similar codes. Use of the entire system can save you a great deal of time and energy. TART2000 is distributed on CD. This CD contains on-line documentation for all codes included in the system, the codes configured to run on a variety of computers, and many example problems that you can use to familiarize yourself with the system. TART2000 completely supersedes all older versions of TART, and it is strongly recommended that users only use the most recent version of TART2000 and its data files.
Date: November 22, 2000
Creator: Cullen, D.E
Partner: UNT Libraries Government Documents Department

Radiation Diffusion: An Overview of Physical and Numerical Concepts

Description: An overview of the physical and mathematical foundations of radiation transport is given. Emphasis is placed on how the diffusion approximation and its transport corrections arise. An overview of the numerical handling of radiation diffusion coupled to matter is also given. Discussions center on partial temperature and grey methods with comments concerning fully implicit methods. In addition finite difference, finite element and Pert representations of the div-grad operator is also discussed
Date: January 14, 2005
Creator: Graziani, F R
Partner: UNT Libraries Government Documents Department

Interfacial Charge Transport in Organic Electronic Materials: the Key to a New Electronics Technology

Description: This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The primary aim of this project is to obtain a basic scientific understanding of electrical transport processes at interfaces that contain an organic electronic material. Because of their processing advantages and the tunability of their electronic properties, organic electronic materials are revolutionizing major technological areas such as information display. We completed an investigation of the fundamental electronic excitation energies in the prototype conjugated polymer MEH-PPV. We completed a combined theoretical/experimental study of the energy relation between charged excitations in a conjugated polymer and the metal at a polymer/metal interface. We developed a theoretical model that explains injection currents at polymer/metal interfaces. We have made electrical measurements on devices fabricated using the conjugated polymer MEH-PPV a nd a series of metals.
Date: June 4, 1999
Creator: Smith, D.L.; Campbell, I.H.; Davids, P.S.; Heller, C.M.; Laurich, B.K.; Crone, B.K. et al.
Partner: UNT Libraries Government Documents Department

Subsurface Pathway Flow and Transport Modeling for the Idaho National Engineering and Environmental Laboratory's Subsurface Disposal Area

Description: Migration of contaminants through the complex subsurface at the Idaho National Engineering and Environmental Laboratory's Subsurface Disposal Area was simulated for an ongoing Comprehensive Environmental Response, Compensation, and Liability (CERCLA) assessment. A previously existing model for simulating flow and transport through the vadose zone for this site was updated to incorporate information obtained from recent characterization activities. Given the complexity of the subsurface at this site, the simulation results were acknowledged to be uncertain. Rather than attempt parametric approaches to quantify uncertainty, it was recognized that conceptual uncertainty involving the controlling processes was likely dominant. So, the effort focused on modeling different scenarios to evaluate the impact of the conceptual uncertainty.
Date: August 1, 2002
Creator: Magnuson, Swen O
Partner: UNT Libraries Government Documents Department

Using the Schwinger variational functional for the solution of inverse transport problems

Description: A new iterative inverse method for gama-ray transport problems is presented. The method, based on a novel application of the Schwinger variational functional, is developed as a perturbation problem in which the current model (in the iterative process) is considered the initial, unperturbed system, and the actual model is considered the perturbed system. The new method requires the solution of a set of uncoupled one-group forward and adjoint transport equations in each iteration. Four inverse problems are considered: determination of (1) interface locations in a multilayer sourcehhield system; (2) the isotopic composition of an unknown source (including inert elements); (3) interface locations and the source composition simultaneously; and (4) the composition of an unknown layer in the shield. Only the first two problems were actually solved in numerical one-dimensional (spherical) test cases. The method worked well for the unknown interface location problem and extremely well for the unknown source composition problem. Convergence of the method was heavily dependent on the initial guess.
Date: January 1, 2002
Creator: Favorite, J. A. (Jeffrey A.)
Partner: UNT Libraries Government Documents Department

Implict Monte Carlo Radiation Transport Simulations of Four Test Problems

Description: Radiation transport codes, like almost all codes, are difficult to develop and debug. It is helpful to have small, easy to run test problems with known answers to use in development and debugging. It is also prudent to re-run test problems periodically during development to ensure that previous code capabilities have not been lost. We describe four radiation transport test problems with analytic or approximate analytic answers. These test problems are suitable for use in debugging and testing radiation transport codes. We also give results of simulations of these test problems performed with an Implicit Monte Carlo photonics code.
Date: August 1, 2007
Creator: Gentile, N
Partner: UNT Libraries Government Documents Department