UScholar Works
 
Filters: School Or College: "College of Science" Collection: "ir_uspace"
1 - 25 of 175
Number of results to display per page
CreatorTitleDescriptionSubjectDate
1 Sperry, John S.Anatomy of the palm Rhapis excelsa, IX. Xylem structure of the leaf insertionSTEMS OF PERENNIAL PLANTS, particularly trees, represent a considerable investment in biomass. Trees can survive even under the most adverse conditions, but only if the hydraulic integrity of the stem is preserved. A very important and vulnerable part of the stem is the xylem. As water is pulled int...Palm stems; Palm stem anatomy; Palm leaves; Leaf insertion; Vessel network; Vessel-length distribution; Primary vascular stem tissue; Hydraulic architechture; Water column1983
2 Poulter, Charles DaleTetartohedral twinning in IDI-2 from Thermus thermophilus: crystallization under anaerobic conditionsType-2 isopentenyl diphosphate isomerase (IDI-2) is a key flavoprotein involved in the biosynthesis of isoprenoids. Since fully reduced flavin mononucleotide (FMNH2) is needed for activity, it was decided to crystallize the enzyme under anaerobic conditions in order to understand how this reduced co...2014-01-01
3 Vardeny, Zeev Valentine; Ehrenfreund, Eitan A.Illumination-induced metastable polaron-supporting state in poly(p-phenylene vinylene) filmsWe found an illumination-induced metastable polaron-supporting state in films of a soluble derivative of poly-p-phenylene vinylene (MEH-PPV). Pristine, nonilluminated MEH-PPV polymer films do not show longlived photogenerated polarons. Prolonged UV illumination, however, is found to induce a revers...Metastable polaron-supporting state; Poly(p-phenylene vinylene); PPV; MEH-PPV; Excitons2007-07
4 Symko, Orest GeorgeMicrowave absorption in the superconducting and normal phases of Y-Ba-Cu-OMicrowave absorption in a dc magnetic field up to 12 kG, attributed to nonequilibrium contributions to the ac susceptibility, appears at Tc as the sample is cooled. ESR measurements of YBa-Cu-O show that Cu2+ exists only in the fraction of the sample which is not superconducting in a distorted octa...Microwave absorption; Superconducting phase; YBCO; High Tc1987-08
5 Sperry, John S.Evolution of water transport and xylem structureLand plants need water to replace the evaporation that occurs while atmospheric CO2 is diffusing into photosynthetic tissue. The water-for-carbon exchange rate is poor, and evolutionary history indicates a progression of innovations for cheap water transport--beginning in order with capillary sucti...Cavitation; Vessels; Plants2003
6 Mishchenko, EugeneCoulomb drag by small momentum transfer between quantum wiresWe demonstrate that in a wide range of temperatures Coulomb drag between two weakly coupled quantum wires is dominated by processes with a small interwire momentum transfer. Such processes, not accounted for in the conventional Luttinger liquid theory, cause drag only because the electron dispersion...Coulomb drag; Quantum wires; Luttinger liquid2003-09
7 Mattis, Daniel C.Existence of two phase transitions in Hubbard modelWe solve the Hubbard model, for one electron per atom in a simple cubic structure, using one-particle Green's functions. We determine the accuracy of this calculation to be good by comparison with an exact solution by Lieb and Wu of a one-dimensional limiting case.Critical temperature1969-12
8 Poulter, Charles DaleCatalytic mechanism of Escherichia coli isopentenyl diphosphate isomerase involves Cys-67, Glu-116, and Tyr-104 as suggested by crystal structures of complexes with transition state analogues and irreversible inhibitorsIsopentenyl diphosphate (IPP):dimethylallyl diphosphate (DMAPP) isomerase is a key enzyme in the biosynthesis of isoprenoids. The reaction involves protonation and deprotonation of the isoprenoid unit and proceeds through a carbocationic transition state. Analysis of the crystal structures (2 A) of ...Catalytic Domain; Crystallography; Organophosphorus Compounds2003-04-04
9 Morse, Michael DavidResonant two-photon ionization spectroscopy of jet-cooled Pt?The gas phase optical spectrum of jet-cooled Pt? has been investigated over the range of 11 300 to 26 300 cm -1 using resonant two-photon ionization spectroscopy in combination with time-of-flight mass spectrometry. Numerous vibronic bands are observed. Analysis of the data gives the location of som...1988
10 Morse, Michael DavidLaser vaporization generation of the SiB and SiAi radicals for matrix isolation electron spin resonance studies: comparison with theoretical calculations and assignment of their electronic ground states as X ??The first experimental spectroscopic study of the SiB and SiAl diatomic radicals is reported. Electron spin resonance results indicate that both molecules have X 4? ground electronic states, in agreement with earlier theoretical calculations. The SIB and SiAl radicals were generated in neon matrices...1993
11 Miller, Joel StevenCharge transfer complexes of 2,4,6-tricyano-s-triazine with tetrathiafulvalene (TTF) and N,N,N' ,N'-tetramethyl-p-phenylenediamine (TMPD)Reaction of 2,4,6-tricyano-s-triazine (TCT) with tetrathiafulvalene (TTF) and N,N,N',N'-tetramethylp-phenylenediamine (TMPD) leads to 1 : 1 charge transfer complexes. The crystal structures of the TTF[TCT], as well as the decomposition product due to hydrolysis of the [TMPD][TCT], i.e. HTMPD]+[2,4-d...Electron; Solution; Hydrolysis2002
12 Morse, Michael DavidResonant two-photon ionization spectroscopy of NiCA spectroscopic investigation of jet-cooled diatomic NiC has revealed a complex pattern of vibronic levels in the wave number range from 21 700 to 27 000 cm-1. Of the more than 50 vibronic bands observed, 31 have been rotationally resolved and analyzed. All are ?'=0+??"=0+ transitions, consistent wi...2002
13 Golden, Kenneth M.; Zhu, Jing YiNetwork model for fluid transport through sea iceThe flow of liquid through porous sea ice is a fundamental process affecting problems in polar biology, oceanography and geophysics. The geometry and connectedness of the pore microstructure of sea ice determine its fluid permeability, which depends strongly on temperature. Here we analyze a simple ...Fluid transport; Pipe network; Brine2006
14 Minteer, Shelley D.Controlled placement of enzymes on carbon nanotubes using comb-branched DNAImmobilization is not only useful for preserving enzyme activity, but also to adhere an enzyme to a surface, such as an electrode, so that the enzyme does not leach into solution during testing. Current immobilization approaches do not readily allow for adjustments to the distance between the enzyme...2014-01-01
15 Lupton, John MarkUltrafast intramolecular energy transfer in single conjugated polymer chains probed by polarized single chromophore spectroscopySingle molecule spectroscopy of rigid-rod ladder-type conjugated polymers reveals individual chromophore units on a polymer chain, exhibiting fluorescence linewidths of less than 1 nm. Whereas the fluorescence from a single chromophore is fully linearly polarized at low temperatures, a number of exc...Single molecule spectroscopy; Intramolecular energy transfer; Chromophore spectroscopy; Chromophores; Rigid-rod; Ladder-type2004
16 Williams, Clayton C.Single electron tunneling to insulator surfaces detected by electrostatic forceThe detection of single-electron tunneling events between a metallic scanning probe tip and an insulating surface is demonstrated by an electrostatic force method. When a voltage-biased oscillating atomic force microscopy tip is placed within tunneling range of the surface of an insulator, single...Single electron; Tunneling events; Scanning tunneling microscope2002
17 Sperry, John S.Analysis of circular bordered pit function I. Angiosperm vessels with homogenous pit membranesA model predicted pit and vessel conductivity, the air-seed pressure for cavitation, and the implosion pressure causing vessel collapse. Predictions were based on measurements from 27 angiosperm species with circular bordered pits and air-seed pressures of 0.2-11.3 MPa. Vessel implosion pressure exc...Functional wood anatomy; hydraulic architecture; plant biomechanics2004
18 Morse, Michael DavidFirst spectroscopic investigation of the 4 d transition metal monocarbide MoCThe first optical spectroscopic investigation of MoC has revealed a complicated vibronic spectrum consisting of about 35 bands between 17 700 and 24 000 cm-1. Analysis has shown the ground state to be the ?=0+ spin?orbit component of a 3?- state that derives from a 10?211?25rr42d 2 configuration. Th...1998
19 Sperry, John S.Analysis of circular bordered pit function II. Gymnosperm tracheids with torus-margo pit membranesA model of xylem conduit function was applied to gymnosperm tracheids with torus-margo pit membranes for comparison with angiosperm vessels. Tracheids from 17 gymnosperm tree species with circular bordered pits and air-seed pressures from 0.8 to 11.8 MPa were analyzed. Tracheids were more reinforced...Functional wood anatomy; hydraulic architecture; plant biomechanics2004
20 Sperry, John S.Size and function in conifer tracheids and angiosperm vesselsThe wide size range of conifer tracheids and angiosperm vessels has important consequences for function. In both conduit types, bigger is better for conducting efficiency. The gain in efficiency with size is maximized by the control of conduit shape, which balances end-wall and lumen resistances.Ecological wood anatomy; vascular structure and function; water transport2006
21 Morse, Michael DavidSpectroscopy and electronic structure of jet-cooled NiPd and PdPtResonant two-photon ionization spectroscopy of jet-cooled NiPd and PdPt has revealed a dense vibronic spectrum for NiPd and a much more sparse spectrum for PdPt. Four vibrational progressions have been identified for NiPd, and three have been located for PdPt. High resolution investigations of NiPd...1990
22 Gesteland, Raymond F.; Atkins, John F.; Wills, Norma M.rRNA-mRNA base pairing stimulates a programmed -1 ribosomal frameshiftBase pairing between the 3' end of 16S rRNA and mRNA is shown to be important for the programmed -1 frameshifting utilized in decoding the Escherichia coli dnaX gene. This pairing is the same as the Shine-Dalgarno pairing used by prokaryotic ribosomes in selection of translation initiators, but for ...Frameshifting; Escherichia coli; Binding Sites; Base Composition1994
23 Gesteland, Raymond F.; Atkins, John F.; Ingram, Jennifer A.; Kelly, Paul J.; Grentzmann, GuidoDual-luciferase reporter system for studying recoding signalsA new reporter system has been developed for measuring translation coupling efficiency of recoding mechanisms such as frameshifting or readthrough. A recoding test sequence is cloned in between the renilla and firefly luciferase reporter genes and the two luciferase activities are subsequently measu...Amino Acid Sequence; Genes, Reporter; HIV; Antizyme; Translation1998
24 Vardeny, Zeev Valentine; Raikh, Mikhail E.Emission spectrum of a dipole in a semi-infinite periodic dielectric structure: effect of the boundaryThe emission spectrum of a dipole embedded in a semi-infinite photonic crystal is calculated. For simplicity we study the case in which the dielectric function is sinusoidally modulated only along the direction perpendicular to the boundary surface plane. In addition to oscillations of the emission...Emission spectrum; Dipole; Periodic dielectric structure2000-07
25 Lupton, John MarkProbing the electrode-polymer interface in conjugated polymer devices with surface-enhanced Raman scatteringA crucial consideration in organic devices is the role of the interface between a metal electrode and the active polymer material. Here, we use the conjugated polymer poly[2-methoxy-5-(2-ethylhexyl-oxy)-1,4-phenylene-vinylene] (MEH-PPV) with model gold and silver electrodes to perform surface-enhanc...2012-01-01
1 - 25 of 175