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Description: The synthesis of nonracemic yields of hexa-, hepta-, octa-, and nonhelicene with circular light was observed, and the structural and wavelength dependence of the induced optical yields was examined. The results obtained, together with a detailed consideration of the mechanism of helicene synthesis from the parent diarylolefins, indicate that the induced optical activity is due to selective reaction of enantiomeric conformations of the parent cis diarylolefins by circular light.
Date: May 1, 1971
Creator: Bernstein, William J.; Calvin, Melvin & Buchardt, Ole.
Partner: UNT Libraries Government Documents Department


Description: The capacity of photosynthetic organisms to exhibit photo-induced electron paramagnetic resonance (EPR) signals has been known for over ten years. Subcellular units of photosynthetic materials, the quantasomes and the chromatophores, are capable of Hill Reaction activity, and also of exhibiting the light-induced EPR signals. This, coupled with the rapid rise and decay kinetics of these signals, suggests but does not prove that the unpaired electrons are involved in the initial electron transfer processes in the primary quantum conversion act. The identification of the species giving rise to these signals and their connection with processes of primary quantum conversion remains elusive even though such varied approaches as mutant strains, special growth conditions, extreme physical conditions, special metabolic inhibitors, etc. have been applied to this problem. In this communication the authors wish to report another method being used in an attempt to identify the species responsible for the unpaired electrons. Hoffman prepared a water soluble, stable free radical, di-tertiary-butylnitroxide (hereafter called DTBN), which is a 'vigorous free radical scavenger'. It shows a sharp, well resolved, symmetrical, three-line paramagnetic resonance spectrum that is relatively insensitive to the molecular environment. The chemistry of di-tertiary butylnitroxide has not been studied extensively. However, four distinct types of interaction can be envisioned for this molecule. It could undergo a one-electron reduction to form a hydroxylamine which can be reduced subsequently to the amine; an oxidative degradation to 2-methyl-2-nitrosopropane and isobutylene; or a coupling with another radical forming either an oxygen substituted hydroxylamine or a tri-substituted amine oxide.
Date: September 9, 1966
Creator: Corker, Gerald A.; Klein, Melvin P. & Calvin, Melvin.
Partner: UNT Libraries Government Documents Department

Experimental and theoretical investigation of the product channels of the O + CH{sub 3} reaction

Description: The product channels of the O({sup 3}P)+CH{sub 3} reaction was investigated. In the experimental part, the branching fraction for formaldehyde production (O+CH{sub 3}{r_arrow}H{sub 2}CO+H) was measured at room temperature in a tubular flow reactor coupled to a photoionization mass spectrometer. The reactants (CH{sub 3} and O) were generated homogeneously in the reactor by simultaneous {ital in}{ital situ} 193-nm photolysis of acetone and SO{sub 2}. Formaldehyde yield relative to the methyl radicals consumed (branching fraction) was determined to be 1.0{+-}0.15. In the theoretical part, calculations of the energetics of possible decomposition pathways of the energy-rich methoxy radical initially formed in the O+CH{sub 3} reaction indicate that the dominant channel for decomposition is C-H bond cleavage leading to atomic hydrogen and formaldehyde. A possible, minor, secondary channel is hydrogen migration, followed by O-H bond cleavage, leading to the same final products. No energetically competitive pathways leading to H{sub 2}, HCO, HOC, or CO could be found.
Date: May 1, 1994
Creator: Slagle, I.R.; Kalinovski, I.J.; Gutman, D. & Harding, L.B.
Partner: UNT Libraries Government Documents Department

Infrared absorption measurements of the kinetics of Cl atom reactions with C{sub 3}H{sub n} (n=4,6) unsaturated hydrocarbons between 300-850 K

Description: The reaction of chlorine (Cl) atoms with the unsaturated C{sub 3}H{sub n} where n=4,6, hydrocarbons propylene, allene, and methyl acetylene have been uninvestigated as a function of temperature and pressure.
Date: August 1, 1997
Creator: Farrell, J.T.; Pilgrim, J.S. & Taatjes, C.A.
Partner: UNT Libraries Government Documents Department

A study of the spray injection Reynolds number effects on gasoline yields of an FCC riser reactor

Description: A computational analysis of the combined effects of feed oil injection parameters in a commercial-scale fluidized catalytic cracking riser reactor was performed using a three-phase, multiple species kinetic cracking computer code. The analysis showed that the injection operating parameters (droplet diameter and injection velocity) had strong impacts on the gasoline yields of the FCC unit. A spray injection Reynolds number combining the two parameters was defined. A correlation between the spray injection Reynolds number and the gasoline product yields for various feed injection conditions was developed. A range of spray injection Reynolds number for the maximum gasoline yield was identified.
Date: April 3, 2000
Creator: Bowman, B. J.; Zhou, C. Q.; Chang, S. L. & Lottes, S. A.
Partner: UNT Libraries Government Documents Department

Pyrolysis mechanisms of lignin model compounds

Description: The flash vacuum pyrolysis of lignin model compounds was studied under conditions optimized for the production of liquid products to provide mechanistic insight into the reaction pathways that lead to product formation. The major reaction products can be explained by cleavage of the C-O either linkage by a free radial or concerted 1,2-elimination.
Date: June 1, 1997
Creator: Britt, P.F.; Buchanan, A.C. III & Cooney, M.J.
Partner: UNT Libraries Government Documents Department

Scale-up of mild gasification to a process development unit. Progress report, November 21, 1994--February 20, 1995

Description: The overall objective of this project is to develop the IGT Mild-Gasification (MILDGAS) process for near-term commercialization. The specific objectives of the program are to: design, construct, and operate a 24-tons/day adiabatic process development unit (PDU) to obtain process performance data suitable for further design scaleup; obtain large batches of coal-derived co-products for industrial evaluation; prepare a detailed design of a demonstration unit; develop technical and economic plans for commercialization of the MILDGAS process. The project team that is performing the initial phases of the PDU development are: Kerr-McGee Coal Corporation (K-M Coal), the Institute of Gas Technology (IGT), Bechtel Corporation (Bechtel), and Southern Illinois University at Carbondale (SIUC). The MILDGAS process is a continuous closed system for producing liquid and solid (char) co-products at mild operating conditions up to 50 psig and 1300{degrees}F. It is capable of processing a wide range of both eastern caking and western noncaking coals. The 1 ton/hr PDU facility that is to be constructed is comprised of a 2.5-ft ID adiabatic gasifier for the production of gases, coal liquids, and char; a three-stage condensation train to condense and store the liquid products; and coal feeding and char handling equipment. The facility will also incorporate support equipment for environmentally acceptable disposal of process waste. This quarter, Roberts and Schaefer (R&S) of Salt Lake City, Utah was awarded the contract to perform the detailed design for the gasification, liquids recovery and overall plant design coordination. They began work in December of 1994 and a meeting was held between R&S, Bechtel, and IGT to discuss control methods, detailed equipment design, the heavy liquids filter, and possible modifications to the first and second stage cyclones.
Date: March 1, 1995
Creator: Doane, E.P.; Carty, R.H. & Foster, H.
Partner: UNT Libraries Government Documents Department

Reaction mechanisms in aromatic hydrocarbon formation involving the C{sub 5}H{sub 5} cyclopentadienyl moiety

Description: The quantum chemical BAC-MP4 and BAC-MP2 methods have been used to investigate the reaction mechanisms leading to polycyclic aromatic hydrocarbon (PAH) ring formation. In particular the authors have determined the elementary reaction steps in the conversion of two cyclopentadienyl radicals to naphthalene. This reaction mechanism is shown to be an extension of the mechanism occurring in the H atom-assisted conversion of fulvene to benzene. The net reaction involves the formation of dihydrofulvalene, which eliminates a hydrogen atom and then rearranges to form naphthalene through a series of ring closures and openings. The importance of forming the {single_bond}CR({center_dot}){single_bond}CHR{single_bond}CR{prime}{double_bond}CR{double_prime}-moiety, which can undergo rearrangement to form three-carbon-atom ring structures, is illustrated with the C{sub 4}H{sub 7} system. The ability of hydrogen atoms to migrate around the cyclopentadienyl moiety is illustrated both for methyl-cyclopentadiene, C{sub 5}H{sub 5}CH{sub 3}, and dihydrofulvalene, C{sub 5}H{sub 5}C{sub 5}H{sub 5}, as well as for their radical species, C{sub 6}H{sub 7} and C{sub 5}H{sub 5}C{sub 5}H{sub 4}. The mobility of hydrogen in the cyclopentadienyl moiety plays an important role both in providing resonance-stabilized radical products and in creating the {single_bond}CR({center_dot}){single_bond}CHR{single_bond}CR{prime}{double_bond}CR{double_prime}-moiety for ring formation. The results illustrate the radical pathway for converting five-membered rings to aromatic six-membered rings. Furthermore, the results indicate the important catalytic role of H atoms in the aromatic ring formation process.
Date: February 1, 1996
Creator: Melius, C.F.; Colvin, M.E.; Marinov, N.M.; Pitz, W.J. & Senkan, S.M.
Partner: UNT Libraries Government Documents Department

Shale oil value enhancement research. Quarterly report, June 1 - August 31, 1996

Description: The overall objective is to develop a new technology for manufacturing valuable marketable products from shale oil. The quarter`s efforts were concentrated on (a) THDA and reaction of alkylpyridines at elevated conditions, (b) compound type analysis of kerogen oil and its derived products, (b) thermal hydrodealkylation of the > 290{degrees}C polar fraction, (c) secondary reactions of pyridinic type compounds to form marketable products, and (d) preparation of presentation to the Dawnbreaker Commercial Assistance Program. Excellent progress is being made in all cases. Our market analysis and industrial feedback indicate that the low molecular weight pyridines are the main market driving force. We are concentrating our effort toward increasing the yield of ``light`` pyridines before the end of Phase II(a). Our current laboratory set-up can only produce analytical quantity of samples, which is not sufficient for marketing purpose. However, the completion of a secondary flow THDA unit for a pilot-scale production depends on the availability of the Phase-II(b) and Phase-III funding.
Date: December 31, 1996
Creator: Bunter, J.W.; Russell, C.P.; Tsai, J.C.H.; Cogswell, D.E.; Mihamou, H. & Wright, A.D.
Partner: UNT Libraries Government Documents Department

In-situ monitoring of etch by-products during reactive ion beam etching of GaAs in chlorine/argon

Description: Mass spectrometry of the plasma effluent during Reactive Ion Beam Etching (RIBE) of GaAs using an Inductively Coupled Plasma (ICP) source and a Cl{sub 2}/Ar gas chemistry shows that AsCl{sub 3}, AsCl{sub 2} and AsCl are all detected as etch products for As, while GaCl{sub 2} is the main signal detected for the Ga products. The variation in selective ion currents for the various etch products has been examined as a function of chuck temperature (30--100 C), percentage Cl{sub 2} in the gas flow, beam current (60--180 mA) and beam voltage (200--800 V). The results are consistent with AsCl{sub 3} and GaCl{sub 3} being the main etch product species under their conditions, with fragmentation being responsible for the observed mass spectra.
Date: December 1, 1997
Creator: Lee, J.W.; Pearton, S.J.; Abernathy, C.R.; Vawter, G.A.; Shul, R.J.; Bridges, M.M. et al.
Partner: UNT Libraries Government Documents Department

Radiation turbulence interactions in pulverized coal flames. Technical progress report, third year, second quarter, December 15, 1995--March 15, 1996

Description: In this paper, the authors discuss an experimental and theoretical methodology to characterize soot volume fraction fluctuations in turbulent diffusion flames via chaotic maps. The approach is based on the hypothesis that the fluctuations of properties in turbulent flames is deterministic in nature, rather than statistical. To this extent, the authors measured the time series of soot scattering coefficient in an ethylene diffusion flame from light scattering experiments. Following this, corresponding power spectra and delay maps were calculated. It was shown that if the data were averaged, the characteristics of the fluctuations were almost completely washed out. The psds from experiments were successfully modeled using a series of logistic maps.
Date: September 1, 1996
Creator: Menguec, M.P.; McDonough, J.M.; Manickavasagam, S.; Mukerji, S.; Swabb, S. & Ghosal, S.
Partner: UNT Libraries Government Documents Department

Thermal decomposition studies of halogenated organic compounds

Description: Thermal decomposition results for CCl{sub 4}, CHCl{sub 3}, CH{sub 2}Cl{sub 2}, CH{sub 3}Cl, C{sub 3}H{sub 3}Cl, CFCl{sub 3}, CF{sub 2}Cl{sub 2}, CF{sub 3}Cl, CF{sub 2}HCl, CF{sub 3}I, CH{sub 3}I, C{sub 2}H{sub 5}I, C{sub 6}H{sub 5}I, and CCl{sub 2}O are presented. The results were obtained by shock tube techniques coupled with optical spectroscopic detection of transient species formed from dissociation. The method is illustrated with the CH{sub 3}I (+ Kr) {yields} CH{sub 3} + I (+ Kr) reaction where decomposition was monitored using I-atomic resonance absorption spectrometry (ARAS). Modern unimolecular rate theoretical analysis has been carried out on the present cases, and the conclusions from these calculations are discussed. Lastly, the possible destruction of halo-organics by incineration is considered and some implications are discussed.
Date: June 1, 1997
Creator: Michael, J.V. & Kumaran, S.S.
Partner: UNT Libraries Government Documents Department

He synthesis. Quarterly report, October--December, 1971

Description: Existing supplies of bis-trinitroanisole and picryl hydrazine were used to make 2 kg of bis-hexanitrohydrazobenzene. Development of the HNAB recrystallization process was temporarily stopped due to the need to produce a supply of the intermediate products (picryl chloride and HNHB). Purchase orders for DINOL and DNPIA required for synthesis of AFNOL were awarded.
Date: December 31, 1972
Creator: Hayes, D.V. & Honea, F.I.
Partner: UNT Libraries Government Documents Department

Radiation chemical effects of X-rays on liquids

Description: This review describes some of the chemical changes induced by photoelectrons which are released in liquids when X-rays are absorbed. Both experimental studies and theory are discussed. In part 1, the basic processes occurring upon absorption of X-rays are described. Parts 2 and 3 deal with hydrocarbon liquids; in part 2 the ion yields, including effects at K-edges, and in part 3, the yields of excited states. Part 4 discusses chemical effects of X-rays in aqueous solutions. The authors end with a summary of future needs and directions.
Date: November 1, 1998
Creator: Holroyd, R.A. & Preses, J.M.
Partner: UNT Libraries Government Documents Department

Exploring old and new benzene formation pathways in low-pressure premixed flames of aliphatic fuels

Description: A modeling study of benzene and phenyl radical formation is performed for three low-pressure premixed laminar flat flames having an unsaturated C{sub 2} or C{sub 3} hydrocarbon fuel (acetylene, ethylene, and propene). Predictions using three published detailed elementary-step chemical kinetics mechanisms are tested against MBMS species profile data for all three flames. The differences between the three mechanisms predictive capabilities are explored, with an emphasis on benzene formation pathways. A new chemical kinetics mechanism is created combining features of all three published mechanisms. Included in the mechanism are several novel benzene formation reactions involving combinations of radicals such as C{sub 2}H+C{sub 4}H{sub 5}, and C{sub 5}H{sub 3}+CH{sub 3}. Reactions forming fulvene (a benzene isomer) are included, such as C{sub 3}H{sub 3}+C{sub 3}H{sub 5},as well as fulvene-to-benzene reactions. Predictions using the new mechanism show virtually all of the benzene and phenyl radical to be formed by reactions of either C{sub 3}H{sub 3}+C{sub 3}H{sub 3} or C{sub 3}H{sub 3}+C{sub 3}H{sub 5}, with the relative importance being strongly dependent upon the fuel. C{sub 5}H{sub 3}+CH{sub 3} plays a minor role in fulvene formation in the acetylene flame. The C{sub 2}H{sub x}+C{sub 4}H{sub 4} reactions do not contribute noticeably to benzene or phenyl radical formation in these flames, sometimes being a major decomposition channel for either fulvene or phenyl radical. The formation pathways for C{sub 3}H{sub 3} and C{sub 3}H{sub 5}are delineated for the three flames; while the key reactions differ from flame to flame, CH{sub 2}+C{sub 2}H{sub 2} {Longleftrightarrow} C{sub 3}H{sub 3}+H is important for all three flames.
Date: December 13, 2000
Creator: Pope, Christopher J. & Miller, James A.
Partner: UNT Libraries Government Documents Department

Conversion of bagasse cellulose into ethanol

Description: The study conducted by Arkenol was designed to test the conversion of feedstocks such as sugar cane bagasse, sorghum, napier grass and rice straw into fermentable sugars, and then ferment these sugars using natural yeasts and genetically engineered Zymomonis mobilis bacteria (ZM). The study did convert various cellulosic feedstocks into fermentable sugars utilizing the patented Arkenol Concentrated Acid Hydrolysis Process and equipment at the Arkenol Technology Center in Orange, California. The sugars produced using this process were in the concentration range of 12--15%, much higher than the sugar concentrations the genetically engineered ZM bacteria had been developed for. As a result, while the ZM bacteria fermented the produced sugars without initial inhibition, the completion of high sugar concentration fermentations was slower and at lower yield than predicted by the National Renewable Energy Laboratory (NREL). Natural yeasts performed as expected by Arkenol, similar to the results obtained over the last four years of testing. Overall, at sugar concentrations in the 10--13% range, yeast produced 850090% theoretical ethanol yields and ZM bacteria produced 82--87% theoretical yields in 96 hour fermentations. Additional commercialization work revealed the ability to centrifugally separate and recycle the ZM bacteria after fermentation, slight additional benefits from mixed culture ZM bacteria fermentations, and successful utilization of defined media for ZM bacteria fermentation nutrients in lieu of natural media.
Date: November 19, 1997
Creator: Cuzens, J.E.
Partner: UNT Libraries Government Documents Department

Steady-state and transient catalytic oxidation and coupling of methane

Description: This project addresses the conversion of methane from natural gas into ethane, ethylene and higher hydrocarbons. Our research explores the mechanistic and practical implications of carrying out the methane oxidative coupling reaction in reactor designs other than conventional packed-beds with co-fed reactants. These alternate reactor designs are needed to prevent the full oxidation of methane, which limits C{sub 2}, yields in methane oxidative coupling reactions. The research strategy focuses on preventing contact between the 0{sub 2} reactant required for favorable overall thermodynamics and the C{sub 2+} products of methane coupling. The behavior of various reactor designs are simulated using detailed kinetic transport models. These simulations have suggested that the best way to prevent high C0{sub 2} yields is to separate the oxygen and hydrocarbon streams altogether. As a result, the project has focused on the experimental demonstration of proton transport membrane reactors for the selective conversion of methane into higher hydrocarbons.
Date: June 1, 1995
Creator: Iglesia, E.; Perry, D.L. & Heinemann, H.
Partner: UNT Libraries Government Documents Department

The development of an integrated multistaged fluid bed retorting process. Technical report, October 1, 1992--December 31, 1992

Description: The KENTORT II process includes integral fluidized bed zones for pyrolysis, gasification, and combustion of the oil shale. The purpose of this program is to design and test the KENTORT II process at the 50-lb/hr scale. Along with the major activity of assembling the components of the 50-lb/hr retort, work was also completed in other areas this quarter. Basic studies of the cracking and coking kinetics of model compounds in a fixed bed reactor were continued. Additionally, as part of the effort to investigate niche market applications for KENTORT II-derived products, a study of the synthesis of carbon fibers from the heavy fraction of KENTORT II shale oil was initiated.
Date: January 1, 1993
Creator: Taulbee, D.; Fei, Y. & Carter, S.
Partner: UNT Libraries Government Documents Department

Small angle X-ray scattering study of coal soot formation

Description: The objective of this study is to examine, by small angle X-ray scattering (SAXS), the formation of soot from individual coal particle combustion in a methane flat flame burner. The SAXS instrument at the Basic Energy Sciences Synchrotron Radiation Center (BESSRC) at the Advanced Photon Source (APS) can be used to observe both the formation of spherules and clusters since it can access length scales of 6--6000 {angstrom}. The high X-ray flux enables rapid acquisition of scattering data of various regions of the flame. SAXS data reveal particle size, shape, surface areas, and surface roughness.
Date: February 14, 2000
Creator: Winans, R. E.; Parker, J. T.; Seifert, S. & Fletcher, T. H.
Partner: UNT Libraries Government Documents Department

Synthesis of picryl chloride

Description: A total of six pilot-scale batches of picryl chloride were made. These included three 5-kg batches and three 10-kg batches. The three 5-kg batches were made to investigate the problems encountered with actual production and materials handling. The three 10-kg batches were made to study the process parameters and the yield problems originally encountered with the 5-kg batches. The yields on the 5-kg batches ranged from 40 to 60% of approximately 50% purity. The yields on the 10-kg batches were 80, 86 and 91% in chronological order. The purities were 95, 99+ and 99+% respectively.
Date: July 1, 1970
Creator: Hayes, D.V. & Honea, F.I.
Partner: UNT Libraries Government Documents Department

Soot scattering measurements in the visible and near-infrared spectrum

Description: Scattering to extinction cross-section ratios, {rho}{sub se} were measured using the NIST Large Agglomerate Optics Facility for soot produced from ethene and acetylene laminar diffusion flames. Measurements were performed using light sources at 543.5 nm, 632.8 nm and 856 nm. The average scattering to extinction cross-section ratios for these wavelengths are equal to 0.246, 0.196, and 0.196 for ethene and 0.316, 0.230, and 0.239 for acetylene. The 856 nm measurements represent the longest wavelength for which accurate scattering measurements have been performed for soot. The size distribution and fractal properties of the two soots were determined to assess the effects of limited acceptance angle range, finite size of the sensor, and departure from cosine response on the uncertainty in the measurement of {rho}{sub se} The expanded relative uncertainty (95% confidence level) was found to be {+-}6% at the two visible wavelengths and {+-}8% at 856 nm. Both the magnitude and wavelength dependence of {rho}{sub se} for the present experiments are significantly different from those reported by Krishnan et al. for overfire soot produced using a turbulent flame. The results are compared with the predictions of fractal optics.
Date: February 8, 2000
Partner: UNT Libraries Government Documents Department

Identification and temporal behavior of radical intermediates formed during the combustion and pyrolysis of gaseous fuels: Kinetic pathways to soot formation. Final performance report, July 1, 1994--June 30, 1997

Description: The authors have developed software in-house to automate the processing of peak heights recorded from the shock tube: time-of-flight mass spectrometer (TOF) experiments in a format suitable for the modeling programs and have performed numerous ab initio calculations to provide energy barrier values and thermodynamic data for several key reactions in various reaction mechanisms. Each of the studies described here has contributed to the understanding of the detailed kinetics of the reactions of acyclic fuels, the thermal decompositions of aromatic ring compounds, the shock tube techniques dedicated to combustion science problems, and the role of theoretical chemistry in providing essential thermodynamic and kinetics information necessary for constructing plausible reaction mechanisms. The knowledge derived from these investigations is applicable not only to the area of pre-particle soot formation chemistry, but also to various incineration and coal pyrolysis problems.
Date: September 1, 1998
Creator: Kern, R. D.
Partner: UNT Libraries Government Documents Department


Description: The use of H{sub 2} pulsing to maximize the yield of diesel-range (C{sub 10}-C{sub 20}) Fischer-Tropsch (FT) synthesis products was examined on two high-chain-growth-probability (a {ge} 0.9) Co-based FT catalysts. For both catalysts, H{sub 2} pulsing causes a significant increase in CO conversion, while only temporarily increasing the selectivity to undesirable CH{sub 4}. Increasing the frequency or the duration of H{sub 2} pulsing produces higher CO productivity and higher yield of the C{sub 10}-C{sub 20} range on the Co/Al{sub 2}O{sub 3} catalyst, in agreement with prior observations on a Co-Zr/SiO{sub 2} catalyst. An optimum set of pulse parameters is required for maximizing the selectivity towards the desirable C{sub 10}-C{sub 20} diesel product fraction. Application of a suitable H{sub 2} pulse in the presence of added steam in the feed is a simple method to overcome the loss in activity and the shift in paraffin vs. olefin selectivity (increase in the olefin/paraffin ratio) caused by the excess steam. A decrease in syngas concentration has a strong suppressing effect on the olefin/paraffin ratio of the light hydrocarbon products. Higher syngas concentration can increase the chain growth probability a and thus allow for better evaluation of the effect of pulsing on FT synthesis.
Date: November 1, 2001
Creator: Nikolopoulos, Apostolos A. & Gangwal, Santosh K.
Partner: UNT Libraries Government Documents Department