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Full-Text Articles in Chemistry
Influence Of Crystal Fields On The Quasimetallic Reflection Spectra Of Crystals: Optical Spectra Of Polymorphs Of A Squarylium Dye, M. Tristani-Kendra, Craig J. Eckhardt
Influence Of Crystal Fields On The Quasimetallic Reflection Spectra Of Crystals: Optical Spectra Of Polymorphs Of A Squarylium Dye, M. Tristani-Kendra, Craig J. Eckhardt
Craig J. Eckhardt Publications
The reflection and Kramers–Kronig absorption spectra have been obtained from the monoclinic and triclinic polymorphs of a squarylium dye, 2,4-bis(4-diethylamino-2-hydroxy phenyl) cyclobutadienediylium-1,3-diolate. The extremely different optical responses were found to arise from two molecular singlet transitions of essentially long axis polarization. Successful application of a four oscillator molecular exciton–polariton theory required the use of point charge densities rather than point dipoles in an extension of the theory which employed both interactions between the two singlets as well as a frequency dependent lattice damping. An intermolecular charge transfer transition is also assigned. The Journal of Chemical Physics is copyrighted by The …
Modulated Piezoreflectivity And The Photoelasticity Of Molecular Crystals, T. Luty, Craig J. Eckhardt
Modulated Piezoreflectivity And The Photoelasticity Of Molecular Crystals, T. Luty, Craig J. Eckhardt
Craig J. Eckhardt Publications
Analysis of the optical response of a molecular crystal undergoing an external, periodic modulation is presented in terms of classical dipole theory. The case of modulated strain is treated in particular and identification of such strain with acoustic phonons with q=0 permits use of lattice dynamical theory to elucidate the acoustic phonon–exciton interaction. It is shown that extrema in the piezomodulated reflectivity (PMR) locate transverse and longitudinal exciton–polariton frequencies under specific experimental conditions. Model calculations demonstrate the great difference in the PMR for strong and weakly coupled systems. Relation of the PMR intensity to the elasto-optic coefficients and the storage …
Some Plant Leaves Have Orientation-Dependent Epr And Nmr Spectra, Douglas C. Mccain, Ted C. Selig, University Of Illinois At Urbana-Champaign, John L. Markey
Some Plant Leaves Have Orientation-Dependent Epr And Nmr Spectra, Douglas C. Mccain, Ted C. Selig, University Of Illinois At Urbana-Champaign, John L. Markey
Chemistry Department: Faculty Publications
Proton nuclear magnetic resonance (1H NMR) spectra of leaves from 50 plant species were obtained at a spectrometer frequency of 470 MHz. Water present in leaf samples gives rise to characteristic spectral patterns. Most species show only one broad 1H NMR peak; however, the leaves of some plants display complex, orientation-dependent spectra in which a common three-line pattern is discerned. The pattern varies with the angle between the leaf surface and the external magnetic field. Proton relaxation measurements show the presence of at least two water compartments in the leaves. The compartments are responsible for different components …
Protein Synthesis In Rabbit Reticulocytes: A Study Of The Mechanism Of Action Of The Protein Factor Rf That Reverses Protein Synthesis Inhibition In Heme-Deficient Reticulocyte Lysates, M. Grace, M. Bagchi, F. Ahmad, T. Yeager, C. Olson, I. Chakravarty, N. Nasrin, A. Banerjee, N. K. Gupta
Protein Synthesis In Rabbit Reticulocytes: A Study Of The Mechanism Of Action Of The Protein Factor Rf That Reverses Protein Synthesis Inhibition In Heme-Deficient Reticulocyte Lysates, M. Grace, M. Bagchi, F. Ahmad, T. Yeager, C. Olson, I. Chakravarty, N. Nasrin, A. Banerjee, N. K. Gupta
Chemistry Department: Faculty Publications
A eukaryotic initiation factor 2 (eIF-2)-ancillary protein factor Co-eIF-2 promotes displacement of GDP from eIF-2GDP and facilitates ternary complex (Met-tRNAf• eIF-2-GTP) formation in the presence of Mg2+. Heme-regulated protein synthesis inhibitor, HRI, phosphorylates the α-subunit of eIF-2 and thus inhibits ternary complex formation as Co-eIF•2 does not displace GDP from eIF-2α(P)•GDP. RF, a high molecular weight cell supernatant factor, reverses protein synthesis inhibition in heme-deficient reticulocyte lysates and also reverses HRI inhibition of ternary complex formation. RF contains Co-eIF•2 activity. In addition, an active RF preparation contains excess α-subunit of eIF-2 in the free and unphosphorylated …