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Corner rounding in EUV photoresist: tuning through molecular weight, PAG size, and development time

Description: In this paper, the corner rounding bias of a commercially available extreme ultraviolet photoresist is monitored as molecular weight, photoacid generator (PAG) size, and development time are varied. These experiments show that PAG size influences corner biasing while molecular weight and development time do not. Large PAGs are shown to exhibit less corner biasing, and in some cases, lower corner rounding, than small PAGs. In addition, heavier resist polymers are shown to exhibit less corner rounding than lighter ones.
Date: December 31, 2009
Creator: Anderson, Christopher; Daggett, Joe & Naulleau, Patrick
Partner: UNT Libraries Government Documents Department

Physics group progress report, May 1--31, 1948

Description: Various studies conducted at Mound Laboratory concerning physical properties of postum (Polonium 210) are described. Some studies are entitled Purity of Postum (Vacuum Balance Method); Vapor Pressure of Postum; X-ray Studies; Vapor Pressure by Effusion; Molecular Weigh of Postum; and Weighing Procedures for Macroassay.
Date: December 31, 1948
Creator: Knauss, H.P.
Partner: UNT Libraries Government Documents Department

Static and Flow Properties of Dilute Polymer Solutions

Description: Small weight percentages of certain high-molecular weight polymers added to liquids in turbulent flow through conduits can result in dramatic friction reduction. Although many current and potential uses of the drag reduction phenomenon exist, there is a fundamental problem: drag reduction efficacy decreases rapidly with flow time due to the mechanical degradation in flow of the added polymer. In this thesis study, dilute aqueous solutions of polyacrylamide were tested under turbulent flow conditions in an attempt to determine where mechanical degradation in flow occurs.
Date: August 1991
Creator: Whang, Kyu-ho
Partner: UNT Libraries

Degradation kinetics of polymers in solution: Time-dependence of molecular weight distributions. [Quarterly report, January--March 1996]

Description: Polymer degradation occurs when polymer chains are broken under the influence of thermal, mechanical, or chemical energy. Chain-end depolymerization and random- and midpoint-chain scission are mechanisms that have been observed in liquid-phase polymer degradation. Here we develop mathematical models, unified by continuous-mixture kinetics, to show how these different mechanisms affect polymer degradation in solution. Rate expressions for the fragmentation of molecular-weight distributions (MWDs) govern the evolution of the MWDs. The governing integro-differential equations can be solved analytically for realistic conditions. Moment analysis for first-order continuous kinetics shows the temporal behavior of MWDs. Chain-end depolymerization yields monomer product and polymer molecular-weight moments that vary linearly with time. In contrast, random- and midpoint-chain scission models display exponential time behavior. The mathematical results reasonably portray experimental observations for polymer degradation. This approach, based on the time evolution of continuous distributions of chain length or molecular weight, provides a framework for interpreting several types of polymer degradation processes.
Date: February 27, 1996
Creator: McCoy, B.J. & Madras, G.
Partner: UNT Libraries Government Documents Department

Detection of Biological Materials Using Ion Mobility Spectroscopy

Description: Traditionally, Ion Mobility Spectroscopy has been used to examine ions of relatively low molecular weight and high ion mobility. In recent years, however, biomolecules such as bradykinin, cytochrome c, bovine pancreatic trypsin inhibitor (BPTI), apomyoglobin, and lysozyme, have been successfully analyzed, but studies of whole bio-organisms have not been performed. In this study an attempt was made to detect and measure the mobility of two bacteriophages, {lambda}-phage and MS2 using electrospray methods to inject the viruses into the ion mobility spectrometer. Using data from Yeh, et al., which makes a comparison between the diameter of non-biologic particles and the specific particle mobility, the particle mobility for the MS2 virus was estimated to be 10{sup {minus}2} cm{sup 2}/volt-sec. From this mobility the drift time of these particles in our spectrometer was calculated to be approximately 65 msec. The particle mobility for the {lambda}-phage virus was estimated to be 10{sup {minus}3} cm{sup 2}/volt-sec. which would result in a drift time of 0.7 sec. Spectra showing the presence of a viral peak at the expected drift time were not observed. However, changes in the reactant ion peak that could be directly attributed to the presence of the viruses were observed. Virus clustering, excessive collisions, and the electrospray injection method limited the performance of this IMS. However, we believe that an instrument specifically designed to analyze such bioagents and utilizing other injection and ionization methods will succeed in directly detecting viruses and bacteria.
Date: March 1, 1999
Creator: Rodacy, P.J.; Sterling, J.P. & Butler, M.A.
Partner: UNT Libraries Government Documents Department

Characterization of asphaltenes from processed resids

Description: The current and future trend for petroleum processing is towards conversion of heavier and heavier fractions into useful products such as gasoline and diesel. Asphaltenes, the heptane insoluble fraction of heavy oils, are a solubility class and not a specific boiling range. They tend to be the hardest fraction to process in the refinery because of their high molecular mass, aromaticity and heteroatom and metal (S, N, Ni, V) content. Molecular characterization of asphaltenes is important since a more thorough understanding of the chemical nature of the constituents should lead to more efficient processing schemes. A major hurdle in the accurate representation of the molecular structure of asphaltenes has been the determination of the molecular weight. The main problem is the formation of molecular aggregates depending upon factors such as polarity of the solvent, temperature, concentration and others. Over the past 15 years or so, the apparent molecular weight of asphaltenes has dropped significantly lower as the cause and effect of aggregation on molecular weight was determined. Molecular weights as high as 500,000 have been reported for some asphaltenes in the past with weights as low as 600 appearing in the literature recently depending on the analytical method used. In this study, high resolution sector field mass spectrometry was used to determine the comparative speciation of the composition of the asphaltenes from resid subjected to processing conditions.
Date: April 1, 1997
Creator: Hunt, J.E.; Winans, R.E. & Miller, J.T.
Partner: UNT Libraries Government Documents Department

Factor analysis of GPC-FTIR data in PBX9501 binder degradation studies

Description: The GPC/FTIR data consist of sets of 120 FTIR spectra corresponding to 120 GPC fractions. The GPC fractions can be further categorized by their polystyrene equivalent molecular weight and retention time, The FTIR data to be compared is in three sets of 120 spectra corresponding to the control, thermally aged, and radiolytically aged binder material. Figure 1 shows the extracted spectra (or factors) and corresponding concentration profiles (or scores) for the control data set. The four extracted spectra correspond to spectra for the background/baseline, Estane, Irganox, and NP. The extracted spectra match the spectra of pure components with the exception of Irganox. The Irganox spectrum has some spectral features corresponding to Irganox, but others are due to the poor signal-to-noise in the spectra of these GPC fractions. The low concentration for Irganox results in a widely varying concentration profile and the poor extracted spectrum. The factors and scores for the thermally aged data set demonstrate the same components that are evident in the control data set. The concentration profile shows an asymmetric distribution for Estane with a tail on the low molecular weight side. Less NP is associated with Estane in this region compared to the control data. The major NP concentration is near fraction 80, but is considerably less in magnitude (relative to Estane) when compared to the control. For the radiolytically aged sample set a five-factor solution provides a better fit for the data. The primary difference is the presence of additional bands near 1050,1320, and 1560 cm{sup {minus}1} for factor 5. Factor 5 shows concentration primarily in the same region as Estane.
Date: November 1, 2000
Creator: Schoonover, J. & Bridgewater, J.
Partner: UNT Libraries Government Documents Department

Structure of charged polymer chains in confined geometry.

Description: The intra- and interchain structure of sodium poly(styrenesulphonate) when free and when confined in contrast matched porous Vycor has been investigated by SANS. When confined, a peak is observed whose intensity increases with molecular weight and the 1/q scattering region is extended compared to the bulk. We infer that the chains are sufficiently extended, under the influence of confinement, to highlight the large scale disordered structure of Vycor. The asymptotic behavior of the observed interchain structure factor is = 1/q{sup 2} and = 1/q for free and confined chains respectively.
Date: December 15, 2000
Creator: Gilbert, E. P.; Auvray, L. & Lal, J.
Partner: UNT Libraries Government Documents Department


Description: This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project addresses fundamental questions concerning the behavior of polymers at interfaces: (1) What processes control the formation of an adsorbed layer on a clean surface? (2) What processes control the displacement of preadsorbed polymers? (3) Can one accurately predict the structure of polymer layers? To answer these questions, using neutron reflectivity, we have studied adsorbed layers of the polymer poly(methyl methacrylate) (PMMA) onto a quartz substrate. The polymer density profiles were derived from the neutron reflectivity data. We have shown that dry films exhibit behavior predicted by mean-field theory in that the equilibrated layer thickness scales with the molecular weight of the polymer. Also, we find that the profiles of the polymers in solution qualitatively agree with those predicted by reflected random walk (RRW) theories, yet the profiles are not in quantitative agreement.
Date: November 1, 1999
Creator: SMITH, G.S.; MAJEWSKI, J. & AL, ET
Partner: UNT Libraries Government Documents Department

A Mechanistic Investigation of Gelation. The Sol-Gel Polymerization of Bridged Silsesquioxane Monomers

Description: The study of a homologous series of silsesquioxane monomers has uncovered striking discontinuities in gelation behavior. An investigation of the chemistry during the early stages of the polymerization has provided a molecular basis for these observations. Monomers containing from one to four carbon atoms exhibit a pronounced tendency to undergo inter or intramolecular cyclization. The cyclic intermediates have been characterized by {sup 29}Si NMR, chemical ionization mass spectrometry and isolation from the reaction solution. These carbosiloxanes are local thermodynamic sinks that produce kinetic bottlenecks in the production of high molecular weight silsesquioxanes. The formation of cyclics results in slowing down or in some cases completely shutting down gelation. An additional finding is that the cyclic structures are incorporated intact into the final xerogel. Since cyclization alters the structure of the building block that eventually makes up the xerogel network, it is expected that this will contribute importantly to the bulk properties of the xerogel as well.
Date: July 14, 2000
Partner: UNT Libraries Government Documents Department

Opto-acoustic cell permeation

Description: Optically generated acoustic waves have been used to temporarily permeate biological cells. This technique may be useful for enhancing transfection of DNA into cells or enhancing the absorption of locally delivered drugs. A diode-pumped frequency-doubled Nd:YAG laser operating at kHz repetition rates was used to produce a series of acoustic pulses. An acoustic wave was formed via thermoelastic expansion by depositing laser radiation into an absorbing dye. Generated pressures were measured with a PVDF hydrophone. The acoustic waves were transmitted to cultured and plated cells. The cell media contained a selection of normally- impermeable fluorescent-labeled dextran dyes. Following treatment with the opto-acoustic technique, cellular incorporation of dyes, up to 40,000 Molecular Weight, was noted. Control cells that did not receive opto-acoustic treatment had unremarkable dye incorporation. Uptake of dye was quantified via fluorescent microscopic analysis. Trypan Blue membrane exclusion assays and fluorescent labeling assays confirmed the vitality of cells following treatment. This method of enhanced drug delivery has the potential to dramatically reduce required drug dosages and associated side effects and enable revolutionary therapies.
Date: March 9, 2000
Creator: Visuri, S R & Heredia, N
Partner: UNT Libraries Government Documents Department

Hydrolytic Degradation of Estane 5703

Description: Relative to the unaged Estane{reg_sign} 5703, heating decreases the modulus and ultimate stress for both the dry and humid samples. The sample aged in dry air, quickly recovered to its original mechanical properties. The reversibility of the mechanical properties is a result of the reorganization of the hard segments into domains. For the Estane 5703 samples aged in humid air, the mechanical properties only partially recovered with time. Molecular weight data confirm that differences in the extent of the recovery for the samples aged under humid environments are likely due to the hydrolytic scission of the polyester soft segments. Since the tensile moduli are similar for the samples aged in both the dry and humid environments, it is believed that the phase behavior of the hard domains dictate the mechanical properties at low extensions. However, at higher elongations, the mechanical properties are dominated by the soft segments. Both the influences of morphological changes and chemical changes induced by heating must be considered in multiphase polymers when accelerated aging is utilized to predict long term polymer properties. After accelerated aging experiments, the morphology must be allowed to recover to equilibrium conditions in order to assess the extent of degradation and aging. Also, the effect of different humidities on the rate of hydrolytic degradation are presented.
Date: April 27, 1999
Creator: Wrobleski, D.A.; Smith, M.E. & Orler, E.B.
Partner: UNT Libraries Government Documents Department

Testing and Lubrication for Single Race Bearings

Description: Three ES and H-compatible lubricants (Environment, Safety and Health) for single race bearing applications and one hybrid-material single race bearings were evaluated and compared against single race bearings with trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing lubricant extracted from Vydax{trademark}. Vydax is a product manufactured by DuPont consisting of various molecular weights of PTFE suspended in trichlorotrifluoroethane (Freon), which is an ozone-depleting solvent. Vydax has been used as a bearing lubricant in stronglink mechanisms since 1974. Hybrid bearings with silicon nitride balls and molded glass-nylon-Teflon retainers, bearings lubricated with titanium carbide (TiC) on the balls, bearings lubricated with sputtered MoS{sub 2} on races and retainers, and bearings lubricated with electrophoretically deposited MoS{sub 2} were evaluated. The bearings were maintained in a preloaded state in bearing cartridges during cycling and vibration tests. Bearings with electrophoretically deposited MoS{sub 2} performed as well as bearings lubricated with Vydax and were the best performing candidate. All candidates were suitable for low preload applications. Bearings with TiC coated balls and bearings lubricated with sputtered MoS{sub 2} on the races and retainers performed well at high preloads, though not as well as bearings lubricated with electrophoretic deposition of MoS{sub 2}. Bearings with silicon nitride balls were not suitable for high preload applications.
Date: March 4, 1998
Creator: Steinhoff, R.G.
Partner: UNT Libraries Government Documents Department


Description: A new molecular weight/polarity map based on the Scatchard-Hildebrand solubility equation has been developed for petroleum residua. A series of extractions are performed with solvents of increasing solubility parameter, and the fractions are analyzed by vapor pressure osmometry for number average molecular weight and by analytical-scale size exclusion chromatography for molecular weight spread. Work was performed for a heavy oil material subjected to three increasing severities of thermal treatment prior to and through the onset of coke formation. The results are diagnostic of the layers of solvations by resin-type molecules around a central asphaltene core. Two additional stability diagnostic methods were also used. These were the Heithaus titration ''P-index'' and Gaestel ''G'' index, which have been applied to paving asphalts for decades. The Heithaus titration involves the titration of three toluene solutions of a residuum at three concentrations with a poor solvent, such as isooctane, to the point of asphaltene flocculation. In the present work, the significance of the data are developed in terms of the Hildebrand solubility parameter. The Heithaus results are combined with data from the new molecular weight/polarity map. The solubility parameters for the toluene-soluble asphaltene components are measured, and the solubility parameters of the maltenes can be calculated. As thermal treatment progresses, the solubility parameters of asphaltene materials increase and the molecular weights decrease. A new coking index is proposed based on Heithaus titration data. Preliminary results suggest that an alternative, simpler coking index may be developed by measuring the weight percent of cyclohexane solubles in heptane asphaltenes. Coking onset appears to coincide with the depletion of these resin-type asphaltene solubilizing components of residua. The objective of the present study was to develop a mapping tool that will enhance understanding of the changes that occur in residua during upgrading and support the industry-sponsored work in which ...
Date: April 30, 1999
Creator: Schabron, John F.; Pauli, A. Troy & Joseph F. Rovani, Jr.
Partner: UNT Libraries Government Documents Department

Oxygen monitoring cells at Fermilab

Description: Questions have been raised about the accuracy of oxygen monitoring for personnel safety around systems containing gases with a molecular weight less than nitrogen. A study has been performed to test the accuracy of the oxygen monitoring devices used at Fermilab. Portable and fixed oxygen monitoring equipment is used throughout Fermilab for personnel safety in defined oxygen deficiency hazard (ODH) areas. The results are presented as well as corrective measures taken to ensure accuracy and maintain the proper level of personnel safety.
Date: July 28, 2004
Creator: Theilacker, Jay C.
Partner: UNT Libraries Government Documents Department


Description: Herein we report the aqueous polymerization of acrylamide using reversible addition fragmentation chain transfer (RAFT) polymerization to perform a comprehensive study on the polymerization of acrylamide. More specifically, the effect of polymerization conditions on the polymerization kinetics, molecular weight control, and blocking ability were examined. With this in mind, it was necessary to prepare ''A'' block (corona of the micelle) from a hydrophilic monomer. The responsive ''B'' block present in the core will be disclosed in the next two reports.
Date: October 20, 2004
Creator: McCormick, Charles & Lowe, Andrew
Partner: UNT Libraries Government Documents Department

Effect of secondary structure on the potential of mean force for poly-L-lysine in the alpha-Helix and beta-sheet conformations

Description: Because poly-L-lysine (PLL) can exist in the {alpha}-helix or {beta}-sheet conformation depending on solution preparation and solution conditions, PLL is a suitable candidate to probe the dependence of protein interactions on secondary structure. The osmotic second virial coefficient and weight-average molecular weight are reported from low-angle laser-light scattering measurements for PLL as a function of NaCl concentration, pH, and {alpha}-helix or {beta}-sheet content. Interactions between PLL molecules become more attractive as salt concentration increases due to screening of PLL charge by salt ions and at low salt concentration become more attractive as pH increases due to decreased net charge on PLL. The experimental results show that interactions are stronger for the {beta}-sheet conformation than for the {alpha}-helix conformation. A spherically-symmetric model for the potential of mean force is used to account for specific interactions not described by DLVO theory and to show how differences in secondary structure affect PLL interactions.
Date: October 30, 2001
Creator: Grigsby, J.J.; Blanch, H.W. & Prausnitz, J.M.
Partner: UNT Libraries Government Documents Department

Additional Reserve Recovery Using New Polymer Treatment on High Water Oil Ratio Wells in Alameda Field, Kingman County, Kansas

Description: The Chemical Flooding process, like a polymer treatment, as a tertiary (enhanced) oil recovery process can be a very good solution based on the condition of this field and its low cost compared to the drilling of new wells. It is an improved water flooding method in which high molecular-weight (macro-size molecules) and water-soluble polymers are added to the injection water to improve the mobility ratio by enhancing the viscosity of the water and by reducing permeability in invaded zones during the process. In other words, it can improve the sweep efficiency by reducing the water mobility. This polymer treatment can be performed on the same active oil producer well rather than on an injector well in the existence of strong water drive in the formation. Some parameters must be considered before any polymer job is performed such as: formation temperature, permeability, oil gravity and viscosity, location and formation thickness of the well, amount of remaining recoverable oil, fluid levels, well productivity, water oil ratio (WOR) and existence of water drive. This improved oil recovery technique has been used widely and has significant potential to extend reservoir life by increasing the oil production and decreasing the water cut. This new technology has the greatest potential in reservoirs that are moderately heterogeneous, contain moderately viscous oils, and have adverse water-oil mobility ratios. For example, many wells in Kansas's Arbuckle formation had similar treatments and we have seen very effective results. In addition, there were previous polymer treatments conducted by Texaco in Alameda Field on a number of wells throughout the Viola-Simpson formation in the early 70's. Most of the treatments proved to be very successful.
Date: October 1, 2005
Creator: Spillane, James
Partner: UNT Libraries Government Documents Department


Description: The dependence of an acoustically resonant optoacoustic signal on the molecular weight, and thermodynamic and transport properties of the buffer gas is reported. Our results show that careful selection of such gases can significantly increase the sensitivity and flexibility of optoacoustic spectroscopy. We also demonstrate that such thermodynamic quantities as {gamma} ({triple_bond} C{sub p}/C{sub v}) and sound velocity can now be measured readily and accurately. Other potential applications are suggested.
Date: November 1, 1977
Creator: Thomas III, L.J.; Kelly, M.J. & Amer, N.M.
Partner: UNT Libraries Government Documents Department

EOSN: A TOUGH2 module for noble gases

Description: We developed a new fluid property module for TOUGH2, called EOSN, to simulate transport of noble gases in the subsurface. Currently, users may select any of five different noble gases as well as CO2, two at a time. For the three gas components (air and two user-specified noble gases) in EOSN, the Henry's coefficients and the diffusivities in the gas phase are no longer assumed constants, but are temperature dependent. We used the Crovetto et al. (1982) model to estimate Henry's coefficients, and the Reid et al. (1987) correlations to calculate gas phase diffusivities. The new module requires users to provide names of the selected noble gases, which properties are provided internally. There are options for users to specify any (non-zero) molecular weights and half-lives for the gas components. We provide two examples to show applications of TOUGH2IEOSN. While temperature effects are relatively insignificant for one example problem where advection is dominant, they cause almost an order of magnitude difference for the other case where diffusion becomes a dominant process and temperature variations are relatively large. It appears that thermodynamic effects on gas diffusivities and Henry's coefficients can be important for low-permeability porous media and zones with large temperature variations.
Date: March 7, 2003
Creator: Shan, Chao & Pruess, Karsten
Partner: UNT Libraries Government Documents Department