Physical Sciences and Mathematics Commons^™

Reply To ‘‘Comment On ‘Brillouin-Scattering Study Of The Elastic Constants Of Phenothiazine Through The Phase Transition’ ’’, J. Sartwell, Craig J. Eckhardt

Craig J. Eckhardt Publications

Disagreement in the ordering of relative magnitudes of the elastic constants of phenothiazine with those of Ecolivet et al. is resolved. Dubious methodologies and assumptions employed by Ecolivet et al. in their measurements, approximations, and arguments [C. Ecolivet et al., Phys. Rev. B 44, 4185 (1991)] are noted. Samples employed by these investigators in both their ultrasonic and Brillouin measurements are shown to exhibit properties consistent with impure samples and inconsistent with those of Sartwell and Eckhardt.

Anisotropic Anharmonicity Of Lattice And Molecular Vibrations Of 1,2,4,5 Tetrabromobenzene Determined By Piezomodulated Raman Spectroscopy, K.M. White, Craig J. Eckhardt

Craig J. Eckhardt Publications

Strain-induced coupling constants for the anharmonicity of Raman-active lattice and certain molecular modes of vibration in 1,2,4,5-tetrabromobenzene (TBB) crystals have been determined using piezomodulated Raman spectroscopy. These constants, which are directly related to the first anharmonic term in the potential energy expansion for lattice dynamical calculations, are a quantitative measurement of the modal anharmonicities in the TBB molecular crystal. Application of uniaxial stress in the experiments permits the anisotropy of the anharmonicity to be determined as well as its magnitude. The TBB lattice modes are significantly coupled by the induced strains and the effects of coupling were observed to be …

Electrocrystallization Of Strongly Adherent Brushite Coatings On Prosthetic Alloys (Continuation), Jody G. Redepenning

Chemistry Department: Faculty Publications

An electrolytic method for providing bone-emulating, phosphate coatings on prosthetic appliances. Such coatings serve to enhance bone furation after implantation of the appliances. The method of the invention is an electrolysis process wherein the appliance to be coated is immersed in a phosphate-containing electrolyte to serve as the cathode of the electrolysis process. When current is appIied to the electrolysis cell, the electrolyte solution, which includes calcium ions and dihydrogen phosphate ions, is caused to rapidly increase in (localized) pH proximate the cathode element. The localized pH increase creates a supersaturated local condition causing less soluble calcium phosphate salts to …

Studies Directed Toward Enantioselective Catalysis, Brian E. Jones

Open Access Master's Theses (through 2010)

Many organic molecules of modest size and complexity have chirality.That is, these molecules can exist in more than one stereoisomeric form.There is a strong desire to synthesize chiral compounds that exist in the form of a single stereoisomer.The method of synthesizing chiral compounds that was studied in our research employed a less than stoichiometric amount of chiral catalyst to both catalyze and control the stereochemical outcome of the reactions attempted.

A new chiral ligand was developed to be used as part of the chiral catalyst.This new ligand was used in the enantioselective Diels-Alder cycloaddition reaction and the enantioselective allylation reaction …

Primase Structure And Function, Mark A. Griep

Chemistry Department: Faculty Publications

Primase is the ssDNA-dependent RNA polymerase that synthesizes RNA primers during DNA replication. In common with all DNA and RNA polymerases, primase has structural and functional features involved in polymer elongation. As RNA polymerase, it has structural and functional features for initiating chain synthesis. As a primase, it has structural and functional features for initiating chain synthesis on ssDNA. Using amino acid sequence analysis the structure of Escherichia coli primase responsible for binding zinc, at least three magnesium, and DnaB helicase has been identified. One of the magnesium binding motifs resembles the “active magnesium” motif found in all DNA and …

A Nanosecond Ord Study Of Hemoglobin, Lawrence J. Parkhurst

Lawrence Parkhurst Publications

This year marks the one hundredth anniversary of the first observation of CO photodissociation from HbCO, with the correct interpretation and publication following in the next year (Haldane and Smith, 1896). Little of kinetic importance could be learned from this photosensitivity, however, until the development of sensitive photodetectors and short duration high intensity light sources. These allowed Gibson, in pioneering discoveries in the mid to late 1950's (Gibson, 1956, 1959), to discover “Hb*,” a rapidly reacting form of hemoglobin, which we now associate with deoxy Hb in the tertiary relaxed “r” 9 state with the protein in the quaternary R …

Preparation Of Doped Polycarbynes, Reuben D. Rieke

Chemistry Department: Faculty Publications

Polycarbynes, such as doped polycarbynes, prepared from a soluble source of electrons and an organic monomer or co-monomer containing at least one carbyne group and, optionally, containing a doping agent, in an ethereal, poly ethereal, or hydrocarbon solvent are presented. A wide variety of arylcarbyne and/or alkylcarbyne monomers and co-monomers can be combined with a source of electrons soluble in an ethereal, polyethereal, or hydrocarbon solvent to form novel polycarbyne polymers. These polycarbyne polymers can be used to form synthetic diamond materials, fibers, and other materials that can withstand extreme con ditions.

Enantiomerically Enriched Α-Methyl Amino Acids. Use Of An Acyclic, Chiral Alanine-Derived Dianion With A High Diastereofacial Bias., David B. Berkowitz, Marianne K. Smith

David Berkowitz Publications

Hindered esters derived from N-benzoylalanine and the following chiral alcohols have been synthesized: (1) (−)-isopinocampheol; (2) (−)-trans-2-phenylcyclohexanol and (3) (−)-8-phenylmenthol. Sequential treatment of these esters with LDA (1.2 equiv.) and n-butyllithium (2.4 equiv.) at −78°C in THF generates the corresponding chiral dianions. Alkylation of each of these with benzyl bromide reveals that only the (−)-8-phenylmenthyl auxiliary confers a high diastereofacial bias upon its derivative dianion. In fact, that dianion (6) consistently displays diastereomeric ratios in the range of 89:11 to 94:6 for alkylations with a spectrum of nine alkyl halides. If one recrystallization step is …

Free Α-Oxiranyl Amino Acids, David B. Berkowitz, Michelle L. Pedersen

David Berkowitz Publications

Analogues of natural amino acids, in which the α-proton is replaced by an unsubstituted epoxide ring, are potential mechanism-based inhibitors for pyridoxal phosphate dependent enzymes.¹ Yet, free α-oxiranyl amino acids have remained elusive until now. The synthesis of an α-(phenyl-substituted)oxiranyl amino ester has been reported. However, the accessibility and stability of the corresponding free, zwitterionic α-oxiranyl amino acid remained an open question.⁹

Preparations Of Polycarbynes, Reuben D. Rieke

Chemistry Department: Faculty Publications

Polycarbynes prepared from a soluble source of electrons and an organic monomer or co-monomer containing at least one carbyne group in an ethereal, polyethereal, or hydrocarbon solvent are presented. A wide variety of arylcarbyne and/or alkylcarbyne monomers and co-monomers can be combined with a source of electrons soluble in an ethereal, polyethereal, or hydro-carbon solvent to form novel polycarbyne polymers. These polycarbyne polymers can be used to form synthetic diamond materials, fibers, and other materials that can withstand extreme conditions.