UScholar Works
 
Filters: Publication Type: "abstract" Collection: "ir_uspace"
1 - 25 of 37
Number of results to display per page
CreatorTitleDescriptionSubjectDate
1 Sarofim, Adel F.; Pugmire, Ronald J.13C NMR analysis of soot produced from model compounds and a coalSoot samples, including the associated organics, produced from an Illinois No. 6 coal (five samples) and two model compounds, biphenyl (three samples) and pyrene (two samples), have been studied by 13C NMR methods. The coal soot data served as a guide to selection of the temperature range that would...13C NMR; Biphenyl; Aromatic cluster size2001
2 Smith, Grant D.; Borodin, Oleg; Bedrov, Dmitro13C NMR spin-lattice relaxation and conformational dynamics in a 1,4-polybutadiene meltWe have performed molecular dynamics (MD) simulations of a melt of 1,4-polybutadiene (PBD, 1622 Da) over the temperature range 400?273 K. 13C NMR spin?lattice relaxation times (T1) and nuclear Overhauser enhancement (NOE) values have been measured from 357 to 272 K for 12 different resonances. The T...Polybutadiene melt; 13C NMR; Spin-lattice relaxation; Conformational dynamics; Molecular dynamics simulation2001
3 Voth, Gregory AlanAb initio calculations of reactive pathways for ?-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (?-HMX)Using the BLYP and B3LYP level of density functional theory, four possible decomposition reaction pathways of HMX in the gas phase were investigated: N?NO2 bond dissociation, HONO elimination, C?N bond scission of the ring, and the concerted ring fission. The energetics of each of these four mechan...Ab initio calculations; Reactive pathways; HMX2000
4 Truong, ThanhBranching ratio and pressure dependent rate constants of multichannel unimolecular decomposition of gas-phase ?-HMX: an ab initio dynamics studyThe dynamics of the initial thermal decomposition step of gas-phase ?-HMX is investigated using the master equation method. Both the NO2 fission and HONO elimination channels were considered. The structures, energies, and Hessian information along the minimum energy paths (MEP) of these two channels...Thermal decomposition; HMX2001
5 Orendt, Anita; Pugmire, Ronald J.Carbon-13 chemical shift tensors in polycyclic aromiatic compounds. 9. BiphenyleneThe principal values of the 13C chemical-shift tensors of natural abundance biphenylene were measured at room temperature with the FIREMAT experiment. Of 18 crystallographically distinct positions (three sets of six congruent carbons each), the three primary bands have been resolved into seven singl...Carbon-13; Chemical-shift tensors; Biphenylene; Polycyclic aromiatic compounds; FIREMAT2000
6 Bedrov, Dmitro; Borodin, Oleg; Smith, Grant D.Comment on "On the accuracy of force fields for predicting the physical properties of dimethylnitramine"Zheng and Thompson have recently reported a comparison of three atomistic force fields for prediction of physical properties of dimethylnitramine (DMNA) from molecular dynamics (MD) simulations.1 Specifically, they compared the rigid molecule force field by Sorescu, Rice, and Thompson (SRT);2 the ge...2007
7 Wight, Charles AlbertCompetitive vaporization and decomposition of liquid RDXThe thermal decomposition of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) has been studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Activation energies as a function of the extent of conversion, ?, have been determined by model-free isoconversional analysis o...Liquid RDX; Competitive vaporization; Thermal decomposition; Differential scanning calorimetry2000
8 Veranth, John M.Computational modeling of CO/CO2 ratio inside single char particles during pulverized coal combustionA recently developed model was used to study the CO/CO2 ratio inside a burning pulverized coal particle, to better understand the effect of bulk gas composition on the equilibrium partial pressure of reduced metal species at the surface of ash inclusions. The motivation was to improve the ability to...Pulverized coal combustion; Computational modeling; Char2003
9 Smith, Grant D.Conformational properties of poly(vinylidene fluoride). A quantum chemistry study of model compoundsThe molecular geometries and conformational energies of model molecules of poly(vinylidene fluoride) (PVDF) have been determined from high-level quantum chemistry calculations and have been used in parametrization of a six-state rotational isomeric state (RIS) model for PVDF. The model molecules inv...Poly(vinylidene fluoride); PVDF; Conformational properties1999
10 Truong, ThanhDirect ab initio dynamics studies of the hydrogen abstraction reactions of hydrogen atom with fluoromethanesA direct ab initio dynamics study on the gas-phase reactions of atomic hydrogen with different fluoromethanes has been carried out. The thermal rate constants were calculated using canonical variational transition state (CVT) theory augmented by multidimensional semiclassical zero and small curvatur...Hydrogen abstraction reactions; Gas-phase reactions; Fluoromethanes; Thermal rate constants; Moller?Plesset perturbation theory; Hybrid density functional theory1999
11 Voth, Gregory AlanElectronic structure calculation of the structures and energies of the three pure polymorphic forms of crystalline HMXThe molecular structures and energetic stabilities of the three pure polymorphic forms of crystalline HMX were calculated using a first-principles electronic-structure method. The computations were performed using the local density approximation in conjunction with localized "fireball" orbitals and ...HMX; Crystalline HMX; Molecular geometry2000
12 Wight, Charles AlbertEstimating realistic confidence intervals for the activation energy determined from thermoanalytical measurementsA statistical procedure is proposed for estimating realistic confidence intervals for the activation energy determined by using an advanced isoconversional method. Nine sets of five thermogravimetric measurements have been produced for the process of gassification of ammonium nitrate at five differe...Thermoanalysis; Activation energy; Isoconversional method2000
13 Truong, ThanhHigh level ab initio and density functional theory evaluation of combustion reaction energetics: NO2 and HONO elimination from dimethylnitramineDimethylnitramine (DMNA) is used as a model system for investigating accurate and efficient electronic structure methods for nitramines. Critical points on the potential energy surfaces of DMNA, CH3NCH3, CH3NCH2, NO2, HONO, and the transition state to HONO elimination were located through geometry o...Dimethylnitramine; DMNA; Nitramines; Combustion reaction energetics1999
14 Truong, ThanhImportance of polarization in simulations of condensed phased energetic materialsAn embedded cluster model is used to estimate the molecular dipole moment of crystalline dimethylnitramine (DMNA). The electrostatic potential due to the crystal is included in the calculation via the SCREEP (surface charge representation of the electrostatic embedding potential) approach. The resul...Dimethylnitramine; DMNA; Embedded cluster model1999
15 Pugmire, Ronald J.Investigation of the structural conformation of biphenyl by solid state 13C NMR and quantum chemical NMR shift calculationsThe principal values of the 13C chemical-shift tensor (CST) for biphenyl have been determined with the FIREMAT experiment. The internal dihedral angle between the benzene rings in biphenyl is estimated to fall between 10 and 20° on the basis of quantum mechanical calculations of the CST principal v...Carbon-13; Chemical-shift tensor; biphenyl; FIREMAT2001
16 Eddings, Eric G.; Sarofim, Adel F.Journey from n-heptane to liquid transportation fuels. 1. The role of the allylic radicals and its related species in aromatic precursor chemistryThe Utah normal heptane mechanism compiled from submechanisms in the literature was extended into a detailed normal decane combustion mechanism, which is a subset of the Utah surrogate mechanisms. Few species have greater impact on the concentrations of other species than the allyl radical CH2CHCH2....Utah Surrogate Mechanisms; Heptane mechanism; Decane combustion mechanism; Allyl radical; Aromatic precursors2008
17 Sorensen, Justin Bruce; Williams, Donald Glade; Chaufty, Lisa MarieJust digitize it! : The J. Willard Marriott Library's endeavor to bring geological scholarship to the world (Abstract)The need to organize, preserve, and share the geoscience materials available at the University of Utah motivated the J. Willard Marriott Library's Geospatial Information Committee to begin a project of digitizing the University of Utah's geological theses and their associated maps. This presentation...Thesis and dissertation georeferencing project; digitization; Utah; Abstract2011-10-12
18 Wight, Charles AlbertKinetic study of stabilizing effect of oxygen on thermal degradation of poly(methyl methacrylate)The thermal degradation of poly(methyl methacrylate) (PMMA) has been studied in both pure nitrogen and oxygen-containing atmospheres. The presence of oxygen increases the initial decomposition temperature by 70 °C. The stabilizing effect of oxygen may be explained by forming thermally stable radica...Poly(methyl methacrylate); PMMA; Thermal degradation; Isoconversional method1999
19 Sarofim, Adel F.; Truong, ThanhKinetics of hydrogen abstraction reactions from polycyclic aromatic hydrocarbons by H atomsAn application of the Reaction Class Transition State Theory/Linear Energy Relationship (RC-TST/LER) is presented for the evaluation of the thermal rate constants of hydrogen abstraction reactions by H atoms from Polycyclic Aromatic Hydrocarbons (PAH). Two classes of reactions have been considered, ...Reaction Class Transition State Theory; Linear Energy Relationship; Hydrogen abstraction reactions2004
20 Wight, Charles AlbertKinetics of thermal decomposition of cubic ammonium perchlorateThe methods of thermogravimetric analysis (TGA) and differential scanning calorimettry (DSC) have been used to study the thermal decomposition of ammonium perchlorate (AP). TGA curves obtained under both isothermal and nonisothermal conditions show a characteristic slowdown at the extents of convers...Thermal decomposition; Cubic ammonium perchlorate; Differential scanning calorimetry1999
21 Eddings, Eric G.; Sarofim, Adel F.Mechanism reduction and generation using analysis of major fuel consumption pathways for n-heptane in premixed and diffusion flamesReaction pathway analyses were conducted for three mechanisms (designated as the Pitsch, Utah, and Lawrence Livermore National Lab) for a normal heptane premixed flame (? = 1.9) and a normal heptane opposed diffusion flame, in order to identify the relative importance of the major fuel consumption p...Pitsch mechanism; Utah mechanism; Lawrence Livermore National Lab mechanism; Mechanism reduction; Heptane premixed flame2007
22 Smith, Grant D.Molecular dynamics of a 1,4-polybutadiene melt. Comparison of experiment and simulationWe have made detailed comparison of the local and chain dynamics of a melt of 1,4-polybutadiene (PBD) as determined from experiment and molecular dynamics simulation at 353 K. The PBD was found to have a random microstructure consisting of 40% cis, 50% trans, and 10% 1,2-vinyl units with a number-av...Polybutadiene melt; Molecular dynamics1999
23 Smith, Grant D.; Bedrov, DmitroNMR experiments and molecular dynamics simulations of the segmental dynamics of polystyreneWe have performed NMR spin?lattice relaxation experiments and molecular dynamics (MD) computer simulations on atactic polystyrene (a-PS). The segmental correlation times of three different molecular weight a-PS (Mn = 1600, 2100, 10 900 g/mol) were extracted from NMR by measuring the 2H spin?lattice ...2004
24 Eddings, Eric G.; Sarofim, Adel F.Olefin chemistry in a premixed n-heptane flameThree different n-heptane mechanisms were used to simulate a fuel-rich normal heptane premixed flame in order to identify major reaction pathways for olefin formation and consumption and areas of uncertainties of these reactions. Olefins are formed mainly via ?-scission and hydrogen abstraction, and...Heptane mechanism; N-heptane; Olefin formation; Olefin consumption; Alkyl radicals2007
25 Borodin, Oleg; Smith, Grant D.; Bedrov, DmitroPolarizable and nonpolarizable force fields for alkyl nitratesQuantum-chemistry-based many-body polarizable and two-body nonpolarizable atomic force fields were developed for alkyl nitrate liquids and pentaerythritol tetranitrate (PETN) crystal. Bonding, bending, and torsional parameters, partial charges, and atomic polarizabilities for the polarizable force f...Alkyl nitrate; Pentaerythritol tetranitrate; PETN; Polarizable atomic force fields; Nonpolarizable atomic force fields2007
1 - 25 of 37