UScholar Works
 
Filters: Date: "2000" School Or College: "College of Science" Collection: "ir_uspace"
1 - 25 of 57
Number of results to display per page
CreatorTitleDescriptionSubjectDate
1 Ailion, David Charles109Ag NMR investigation of atomic motions in the incommensurate and paraelectric phases of proustite (Ag3AsS3)109Ag NMR line shape, T1 , Hahn spin echo, and Carr-Purcell-Meiboom-Gill ~CPMG! spin-echo measurements were performed in proustite (Ag3AsS3) between 420 and 47 K in order to understand the role of atomic motions in phase transitions in a system containing an incommensurate phase. These measurements ...NMR; Atomic motion; Proustitie; Phase transitions; Line shape2000
2 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
3 Mattis, Daniel C.Accuracy of bosonization for localized interactionsBosonization is commonly used to calculate the ground-state energy and the dynamics of simple model nonmagnetic impurities in metals. We analyze the accuracy of this procedure in the calculation of the ground-state energy of a simple, solvable, model.Fermions; Electrons; Magnetic2000
4 Lupton, John MarkBragg scattering from periodically microstructured light emitting diodesWe present a simple method of generating a periodic wavelength scale structure in the optically active layer of a light emitting diode. This is achieved by solution deposition of a light emitting polymer on top of a corrugated substrate. The periodic structure allows waveguide modes normally trapped...Bragg scattering; Periodic wavelength scale structure2000
5 Poulter, Charles DaleCaaX proteases, Afc1p and Rce1p, have overlapping but distinct substrate specificitiesMany proteins that contain a carboxyl-terminal CaaX sequence motif, including Ras and yeast a-factor, undergo a series of sequential posttranslational processing steps. Following the initial prenylation of the cysteine, the three C-terminal amino acids are proteolytically removed, and the newly fo...Proteins; Enzymes; Hydrophobic2000
6 Hultine, KevinCarbon and nitrogen allocation to male and female reproduction in Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca, Pinaceae)We measured carbon (respiration, photosynthesis, and production) and nitrogen allocation to male and female cones of Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca) to quantify gender-specific: (1) resource allocation to reproduction, and (2) contribution to carbon costs of reproducti...Gender; photosynthesis; resource allocation2000
7 Ehleringer, James R.Carbon isotope discrimination and water relations of oak hybrid populations in southwestern UtahThe evergreen oak Quercus turbinella and the deciduous Q. gambelii form natural hybrids in southwestern Utah and northern Arizona. Hybrid individuals also are found in northern Utah in a region where only Q. gambelii currently exists, indicating that Q. turbinella has recently retreated southward. ...Quercus turbinella; Oak hybrids; Leaf structure; Leaf nitrogen; Carbon isotope discrimination; Water potential; Oak ecology2000
8 Ehleringer, James R.Carbon isotope ratios in belowground carbon cycle processesAnalyses of carbon isotope ratios (δ13C) in soil organic matter (SOM) and soil respired CO2 provide insights into dynamics of the carbon cycle. δ13C analyses do not provide direct measures of soil CO2 efflux rates but are useful as a constraint in carbon cycle models. In many cases, δ13C analyses...Below ground processes; Ecosystems; Carbon cycle; Carbon isotope ratio; Ecosystem processes; Global change; Soil organic carbon; Soil organic matter2000
9 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
10 Beckerle, Mary C.Characterization of the interaction between zyxin and members of the Ena/Vasodilator-stimulated Phosphoprotein family of proteinsZyxin contains a proline-rich N-terminal domain that is similar to the C-terminal domain in the ActA protein of the bacteria, Listeria monocytogenes. We screened the entire amino acid sequence of human zyxin for Menainteracting peptides and found that, as with ActA, proline-rich sequences were the s...Zyxin; Actin; Listeria monocytogenes; Proline-rich repeats; Cell spreading2000
11 Miller, Joel StevenCluster glass state and photoinduced effects on the freezing dynamics in KxCo[Fe(CN)6]y.ZH2O (x-0.16,y-0.72, z-4.4)The magnetic properties and photoinduced magnetization of a Prussian blue analog, KxCo[Fe(Cn)6]y•ZH2O (x-0.16, y-0.72, z-4.4) were systematically studied. The frequency dependence of the linear ac susceptibility, the irreversibility in the field-cooled/ zero-field-cooled magnetization (MFC /MZFC)...Hexacyanide; Illumination; Temperatures2000
12 Armentrout, Peter B.Collision-induced dissociation dynamics of the [OCS • C2H2]+ complex. A combined experimental and theoretical studyCollision-induced dissociation (CID) of the [OCS • C2H2]+ complex ion with both Xe and Ar over an energy range of 0 to 10 eV in the center of mass frame is studied using a guided ion beam tandem mass spectrometer. The cross sections of the ionic products observed (C,H2S+, OCS+, C2HJ, and S+) are ...Collision-induced dissociation; Competitive shift; Ethylene Sulfide cation; Kinetic shift; Thioketene cation; Potential energy surface2000
13 Truong, ThanhCombined reaction class approach with integrated molecular orbital + molecular orbital (IMOMO) methodology: a practical tool for kinetic modelingWe present a new practical computational methodology for predicting thermal rate constants of reactions involving large molecules or a large number of elementary reactions in the same class. This methodology combines the integrated molecular orbital1molecular orbital (IMOMO) approach with our rece...IMOMO; Kinetic modeling; Thermal rate constants2000
14 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
15 Boehme, ChristophDiffusion of hydrogen and deuterium in stack systems of SixNyHz/SixNyDz and crystalline SiH/D-, N-H/D- and Si-H/D-bond density changes were investigated in stacks consisting of a Cz-Si substrate, a thin layer of SiC>2, amorphous deuterated silicon nitride as well as amorphous hydrogenated silicon nitride in order to see if the post deposition anneal of a-SixNyHz layers on crystalline sil...Hydrogenated silicon nitride; Anneal process2000
16 Truong, ThanhDirect ab initio dynamics studies of N + H2<-->NH + H reactionKinetics of the N+H2<-->NH+H reaction have been studied using a direct ab initio dynamics method. Potential energy surface for low electronic states have been explored at the QCISD/ cc-pVDZ level of theory. We found the ground-state reaction is N(4S)+H2-->NH(3Σ-)+H. Thermal rate constants for this ...Ab initio dynamics; Potential energy surfaces; Minimum energy path; Ground-state reaction; Rate constants2000
17 Olivera, Baldomero M.Distinction among neuronal subtypes of voltage-activated sodium channels by μ-conotoxin PIIIAThe functional properties of most sodium channels are too similar to permit identification of specific sodium channel types underlying macroscopic current. Such discrimination would be particularly advantageous in the nervous system in which different sodium channel family isoforms are coexpressed i...Conotoxins; m-conotoxin2000
18 Miller, Joel StevenEffect of thermal annealing on the ferrimagnetic behavior and ordering of the [MnTXPP]+[TCNE].-.solv (X=F, Cl, Br, I; solv = PhMe, CH2Cl2) family of magnets+5,10,15,20-Tetrakis(4-fluorophenyl)porphyrinatomanganese(III) tetracyanoethenide, [MnTFPP][TCNE], 1F, 5,10,15,20-tetrakis(4-bromophenyl)porphyrinatomanganese(III) tetracyanoethenide, [MnTBrPP][TCNE], 1Br, and 5,10,15,20-tetrakis(4-iodophenyl)porphyrinatomanganese(III) tetracyanoethenide, [MnTIPP][T...Magnetic; Coupling2000
19 Williams, Clayton C.Electron tunneling detected by electrostatic forceA method is introduced for measuring the tunneling of electrons between a specially fabricated scanning probe microscope tip and a surface. The technique is based upon electrostatic force detection of charge as it is transferred to and from a small (10217 F) electrically isolated metallic dot on the...Electrons; Tunneling events; Electrostatic force microscopy2000
20 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
21 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
22 Kieda, David B.Evidence for changing of cosmic ray composition between 10(17) and 10(18) eV from multicomponent measurementsThe average mass composition of cosmic rays with primary energies between 1017 and 1018 eV has been studied using a hybrid detector consisting of the High Resolution Fly's Eye (HiRes) prototype and the MIA muon array. Measurements have been made of the change in the depth of shower maximum and the ...Cosmic rays; Particle energy; Muon array2000
23 Miller, Joel StevenFerrimagnetic ordering of a methylthio-substituted planar porphyrin based electron transfer salt, octakis(2,3,7,8,12,13,17,18-methylthio)porphyrinatomanganese(III) tetracyanoethanideThe direct redox reaction between tetracyanoethylene (TCNE) and a planar porphyrinatomanganese(II), octakis(2,3,7,8,12,13,17,18-methylthio)porphyrinatomanganese(II), MnIIOMTP, produced a polymeric electron transfer salt (ETS), that has been structurally and magnetically characterized. The ETS belon...Magnetic; Temperature; Coupling2000
24 Ehleringer, James R.Fuentes de aqua utilizadas por las plantas desérticas y su importancia en planes de manejo y restauración ecológicaEl agua es el factor más importante que afecta a la productividad primaria y la estructura de la vegetación en ecosistemas áridos. Dado que las especies de plantas pueden diferir en sus capacidades de utilizar distintas fuentes de agua, el conocimiento de estos aspectos es fundamental para los ...Fuentes de agua; Isótopos estables; 8-H; 5 l sO; Zonas áridas; Plantas desérticas; Relaciones hídricas; Restauración ecológica; Desierto de Atacama; Atacama Desert; Stable isotopes; Water sources; Arid regions; Ecological restoration; Water relations; Water supplies2000
25 Adler, Frederick R.Genetic and phylogenetic consequences of island biogeographyIsland biogeography theory predicts that the number of species on an island should increase with island size and decrease with island distance to the mainland. These predictions are generally well supported in comparative and experimental studies. These ecological, equilibrium predictions arise as a...Extinction; Genetic divergence; Island isolation; Migration; Speciation2000
1 - 25 of 57