101 - 125 of 338
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CreatorTitleDescriptionSubjectDate
101 Miller, Joel Steven; Epstein, Arthur J.Complex ac susceptibility studies of the disordered molecular based magnets V(TCNE)x: role of spinless solventThe effect of different spinless solvents on the magnetism of V(TCNE)x . y(solvent) (TCNE= tetracyanoethylene) is studied by temperature (T) dependent ac susceptibility above 2.3 K. Though V(TCNE)x.y(CH2Cl2) has a critical temperature Tc -400 K, for V(TCNEx.y(C4H8O), Tc -205 K and the coercive field...Magnetization; Spin; Temperature1993
102 Morse, Michael DavidPhotodissociation measurements of bond dissociation energies: Ti?+, V?+, Co?+, and Co?+The bond dissociation energies of Ti2+, V+2 , Co+2, and Co: have been measured from the sudden onset of predissociation in the photodissociation spectra of these molecules, yielding values of D?(Ti+2)=2.435+0.002 eV, D?(V+2)=3.140?0.002 eV, D?(Co+2)=2.7651?0.001 eV, and D?(Co+3)=2.086?0.002 eV. Thes...1993
103 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
104 Miller, Joel StevenPressure dependence of magnetic ordering temperature for decamethylferrocenium tetracyanoethenideIt has been demonstrated that the linear-chain charge-transfer salt, decamethylferrocenium tetracyanoethanide (DMeFc) (TCNE), is a ferromagnet with a transition temperature of -4.8 K. This low-temperature 3D ordering has been attributed to a strong intrachain and a weak interchain interaction. To...Ferromagnetic; Transition; Antiferromagnetic1993
105 Morse, Michael DavidSpectroscopic analysis of jet-cooled AICuDiatomic AlCu has been interrogated using resonant two-photon ionization spectroscopy in a supersonic expansion of helium. The ground state is shown to be X l?+, deriving from the 3&3dgd configuration, in agreement with theoretical predictions. The closed-shell nature of this molecule results in a l...1993
106 Poulter, Charles DaleYeast squalene synthase. A mechanism for addition of substrates and activation by NADPHSqualene synthase catalyzes the condensation of two molecules of farnesyl diphosphate (FPP) to give presqualene diphosphate (PSPP) and the subsequent reductive rearrangement of PSPP to squalene. Previous studies of the mechanism of addition of FPP to the enzyme have led to conflicting interpretation...Enzyme Activation; Sesquiterpenes; Kinetics1993-04-15
107 Poulter, Charles DalePurification and characterization of farnesyl diphosphate/geranylgeranyl diphosphate synthaseFarnesyl diphosphate (FPP)/geranylgeranyl diphosphate (GGPP) synthase, a bifunctional enzyme that synthesizes C15 and C2o isoprenoid diphosphates from isopentenyl diphosphate and dimethylallyl diphosphate, was purified to homogeneity from the archae-bacterium Methanobacterium thermoautotrophicum. Th...Bifunctional enzyme; Methanobacterium thermautotrophicum; Synthases1993-05-25
108 Poulter, Charles Dale(S)-Geranylgeranylglyceryl phosphate synthase. Purification and characterization of the first pathway-specific enzyme in archaebacterial membrane lipid biosynthesisThe first pathway-specific step in the biosynthesis of the core membrane diether lipids in archaebacteria is the alkylation of the primary hydroxyl group in (S)-glyceryl phosphate by geranylgeranyl diphosphate. The reaction is catalyzed by (S)-3-O-geranylgeranylglyceryl phosphate ((S)-GGGP) synthase...Polyacrylamide gel; Molecular weight1993-10-15
109 Miller, Joel Steven; Epstein, Arthur J.Molecular magnets V(tetracyanoethylene)x.y(solvent): applications to magnetic shieldingThe specific advantages and limitations of a new class of polymer based magnets [exemplified by V(TCNE)x. y (solvent) (TCNE= tetracyanoethylene)] for static and low frequency magnetic shielding and inductive applications are evaluated using results of dc superconducting quantum interference device ...Frequency; Permeability; Transition1994
110 Poulter, Charles DaleIsoprenyl diphosphate synthases: protein sequence comparisons, a phylogenetic tree, and predictions of secondary structureIsoprenyl diphosphate synthases are ubiquitous enzymes that catalyze the basic chain-elongation reaction in the isoprene biosynthetic pathway. Pairwise sequence comparisons were made for 6 farnesyl diphosphate synthases, 6 geranylgeranyl diphosphate synthases, and a hexaprenyl diphosphate synthase...Catalytic site; Evolution; Farnesyl diphosphate; Geranylgeranyl diphosphate; Prenyltransferase; Substrate binding:1994
111 Morse, Michael DavidInteraction of an aluminum atom with an alkaline earth atom: spectroscopic and ab initio investigations of AICaA spectroscopic analysis of diatomic AlCa generated by laser vaporization of a 2:1 AI:Ca metal alloy followed by supersonic expansion has been completed using resonant two-photon ionization spectroscopy. Four excited electronic states have been identified and investigated in the energy region from 1...1994
112 Morse, Michael DavidNi? revisited: reassignment of the ground electronic stateResonant two-photon ionization spectroscopy was used to study jet-cooled Ni2 produced by pulsed laser ablation of a nickel target in the throat of a supersonic nozzle using argon as the carrier gas. Spectral regions previously investigated using helium as the carrier gas were reinvestigated, and the...1994
113 Morse, Michael DavidSpectroscopic analysis of the open 3 d subshell transition metal aluminides: AIV, AICr, and AICoThree open 3d subshell transition metal aluminides, AlV, AICr, and AlCo, have been investigated by resonant two-photon ionization spectroscopy to elucidate the chemical bonding in these diatomic molecules. The open nature of the 3d subshell results in a vast number of excited electronic states in th...1994
114 Morse, Michael DavidInteraction of an aluminum atom with a closed subshell metal atom: spectroscopic analysis of AIZnResonant two-photon ionization spectroscopy has been employed to investigate diatomic AlZn produced by laser vaporization of a 1:2 Al:Zn alloy target disk in a supersonic expansion of helium. Several discrete transitions are reported in the energy range from 18 400 to 19 100 cm-?. Most of these are...1994
115 Miller, Joel Steven; Epstein, Arthur J.Ferromagnetic behavior and magnetic excitations in a molecular-based alternating-spin chain: decamethylchromocenium tetracyanoethenideWe report the study of magnetic properties of a molecular-based alternating-spin chain: metallocenium electron-transfer salt decamethylchromocenium tetracyanoethanide, [CrCp(*2)] [TCNE]. We give a modified spin-wave theory for the Heisenberg alternating-spin chains. The low-field susceptibility and...TCNE; Magnetization1994
116 Morse, Michael DavidSpectroscopy of mixed early-late transition metal diatomics: ScNi, YPd, and ZrCoResonant two-photon ionization spectroscopy has been employed to investigate the spectra of the jet-cooled transition metal diatomics ScNi, YPd, and ZrCo, which are isovalent species which possess ~or are thought to possess! an X 2?+ ground state. Several electronic band systems have been observed f...1994
117 Miller, Joel Steven; Epstein, Arthur J.Forthcoming attractionsMagnets made from molecules and ions having spins in p orbitals have only been discovered in the past decade. Their solubility in organic solvents and room temperature manufacture means that they should find a variety of applications.Electron; Temperature; Magnets1994
118 Miller, Joel Steven; Epstein, Arthur J.Magnetic behavior of octaethylporphyrinatomanganese(III) tetracyanoethenide, [MnOEP][TCNE], and hexacyanobutadienide, [MnOEP][C4(CN)6]: the importance of a uniform chain for stabilizing strong effective ferromagnetic coupling[MnOEP][A] {A=[TCNE]'- and [C4(CN)6]'-} have been isolated as extended 1D coordination polymers with trans-U2"[A] bridging ligands with strong {A=[C4(CN)6].-} and weak {A=TCNE].-} ferromagnetic coupling as evidenced from the fit of the magnetic susceptibility to the Curie-Weiss law (0=5.1 and 67.1 K...Crystals; Inversion; Coupling1995
119 Miller, Joel StevenIsolation and structural determination of {(1,1,2,2-tetracyano-1,2-ethanediyl)bis[imino(cyanomethylene)]}bis-(cyanamide) ion(2--), [C12N12]2--, a new cyanocarbonThe oxidative degradation of [N(PPh3)2]3[Mnilll(CN)6] leads to the isolation of the unprecedented [C12N12]2- dianion, which is characterized by single-crystal X-ray diffraction and spectroscopic techniques.Cyanogen; Bond; Absorptions1995
120 Morse, Michael DavidUltraviolet photoelectron spectroscopy of molybdenum and molybdenum monoxide anionsThe 351 nm photoelectron spectra of Mo-and MoO- have been measured. The electron affinity of atomic molybdenum is 0.748(2) eV and that of molybdenum monoxide is 1.290(6) eV. The term energies of several MoO electronic states not previously observed are obtained and compared with ab initio prediction...1995
121 Morse, Michael DavidSpectrsocopy of Jet-cooled YCuOptical spectra of jet-cooled diatomic YCu have been recorded using resonant two-photon ionization spectroscopy in a supersonic expansion of helium. The ground state is shown experimentally to be of 1?+ symmetry, with a measured bond length of re"=2.6197(6) ? and a vibrational frequency of 193.21(24...1995
122 Poulter, Charles DaleIsolation of Schizosaccharomyces pombe isopentenyl diphosphate isomerase cDNA clones by complementation and synthesis of the enzyme in Escherichia coliIsopentenyl diphosphate (IPP) isomerase catalyzes an essential activation step in the isoprene biosynthetic pathway. The Saccharomyces cerevisiae gene for IPP isomerase, IDI1, was recently isolated and characterized (Anderson, M. S., Muehlbacher, M., Street, I. P., Proffitt, J., and Poulter, C. D. (...Carbon-Carbon; Biosynthesis; Genetics1995-05-12
123 Poulter, Charles Dale; Jiang, YunfengBTS1 encodes a geranylgeranyl diphosphate synthase in Saccharomyces cerevisiaeProtein prenylation utilizes different types of isoprenoids groups, namely farnesyl and geranylgeranyl, to modify proteins. These lipophilic moieties attach to carboxyl-terminal cysteine residues to promote the association of soluble proteins to membranes. Most prenylated proteins are geranylgeranyl...Amino Acid Sequence; Cloning, Molecular; Gene Expression1995-09-15
124 Miller, Joel Steven; Epstein, Arthur J.Magnetization and dynamics of reentrant ferrimagnetic spin-glass [MnTPP]::+[TCNE].-.2PhMeWe present direct current (dc) magnetization M(T,H) and alternating current (ac) susceptibility Xac(T,H,f) data for the quasi-one-dimensional molecule-based ferrimagnet [MnTPP]::+[TCNE].-.•2PhMe (TPP=meso-tetraphenylporphyrinato, TCNE=tetracyanoethylene). Static scaling of the real part X' of ...Ferrimagnetic order; Magnetism1996
125 Miller, Joel StevenDecamethylnickelocenium hydrogen-7,7,8,8-tetracyanoperfluoro-p-quinodimethandiide: isolation of the protonated weak base [HTCNQF4]-Unprecedently stable hydrogen-7,7,8,8- tetracyanoperfluoro-p-quinodimethandiide, [HTCNQF4]-, is isolated and crystallographically characterized.Structure; Electron; Transfer1996
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