Chemistry Commons^™

Observation Of Fano Asymmetry In Raman Spectra Of Srtio3 And Cax Sr1-Xtio3 Perovskite Nanocubes, Sarbajit Banerjee, Dae In Kim, Richard D. Robinson, Irving P. Herman, Yuanbing Mao, Stanislaus S. Wong

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Bulk SrTi O3 is cubic and not expected to exhibit any first-order Raman scattering. However, nanocubes of SrTi O3 with an edge length of 80±10 nm show strong first-order Raman scattering originating from the breaking of symmetry caused by frozen surface dipoles (local tetragonality) and the presence of nanoscopic polar domains (arising from incorporated impurities). Rapid polarization fluctuations within these nanoscopic ferroelectric regions interfere with a polar phonon, resulting in a Fano-like asymmetric line shape in these SrTi O3 nanocubes, as well as in Ca0.3 Sr0.7 Ti O3 nanocubes.

4,4′-(1,1,1,3,3,3-Hexafluoro­Propane-2,2-Diyl)Bis­(Benzoyl Chloride), Cecilia Rodriguez De Barbarin, Sylvain Bernes, Javier Macossay-Torres, Patrick E. Cassidy

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

In the structure of the title mol­ecule, C17H8Cl2F6O2, the dihedral angle between the least-squares planes of the benzene rings is 66.31 (15)°. The CF3 groups adopt an eclipsed conformation.

High-Resolution Studies Of Tropolone In The S 0 And S 1 Electronic States: Isotope Driven Dynamics In The Zero-Point Energy Levels, John C. Keske, Wei Lin, Wallace C. Pringle, Stewart E. Novick, Thomas A. Blake, David F. Plusquellic

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Rotationally resolved microwave (MW) and ultraviolet (UV) spectra of jet-cooled tropolone have been obtained in S0 and S1 electronic states using Fourier-transform microwave and UV-laser/molecular-beam spectrometers. In the ground electronic state, the MW spectra of all heavy-atom isotopomers including one O18 and four C13 isotopomers were observed in natural abundance. The OD isotopomer was obtained from isotopically enriched samples. The two lowest tunneling states of each isotopomer except O18 have been assigned. The observed inversion splitting for the OD isotopomer is 1523.227(5) MHz. For the asymmetric C13 structures, the magnitudes of tunneling-rotation interactions are found to diminish with decreasing distance …

Discovery And Characterization Of The Cryptic Psi Subunit Of The Pseudomonad Dna Replicase, Thale C. Jarvis, Amber A. Beaudry, James M. Bullard, Urs Ochsner, H. Garry Dallmann, Charles S. Mchenry

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

We previously reconstituted a minimal DNA replicase from Pseudomonas aeruginosa consisting of α and ϵ (polymerase and editing nuclease), β (processivity factor), and the essential τ, δ, and δ′ components of the clamp loader complex (Jarvis, T., Beaudry, A., Bullard, J., Janjic, N., and McHenry, C. (2005) J. Biol. Chem. 280, 7890-7900). In Escherichia coli DNA polymerase III holoenzyme, χ and Ψ are tightly associated clamp loader accessory subunits. The addition of E. coli χΨ to the minimal P. aeruginosa replicase stimulated its activity, suggesting the existence of χ and Ψ counterparts in P. aeruginosa. The P. aeruginosa χ …

A Bacillus Thuringiensis Isolation Method Utilizing A Novel Stain, Low Selection And High Throughput Produced Atypical Results, Joanne Rampersad-Ammons, David R. Ammons

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Background

Bacillus thuringiensis is a bacterium known for producing protein crystals with insecticidal properties. These toxins are widely sought after for controlling agricultural pests due to both their specificity and their applicability in transgenic plants. There is great interest in isolating strains with improved or novel toxin characteristics, however isolating B. thuringiensis from the environment is time consuming and yields relatively few isolates of interest. New approaches to B. thuringiensis isolation have been, and continue to be sought. In this report, candidate B. thuringiensis isolates were recovered from environmental samples using a combination of a novel stain, high throughput and …

A Nested-Pcr With An Internal Amplification Control For The Detection And Differentiation Of Bartonella Henselae And B. Clarridgeiae: An Examination Of Cats In Trinidad, Joanne Rampersad, John D. Watkins, Michael S. Samlal, Raymond Deonanan, Shalini Ramsubeik, David Ammons

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Background

Bartonella species are bacterial blood parasites of animals capable of causing disease in both animals and man. Cat-Scratch Disease (CSD) in humans is caused mainly by Bartonella henselae and is acquired from the cat, which serves as a reservoir for the bacteria. A second species, B. clarridgeiae is also implicated in the disease. Diagnosis of Bartonellosis by culture requires a week or more of incubation on enriched media containing blood, and recovery is often complicated by faster growing contaminating bacteria and fungi. PCR has been explored as an alternative to culture for both the detection and species identification of …

Reconstitution Of A Minimal Dna Replicase From Pseudomonas Aeruginosa And Stimulation By Non-Cognate Auxiliary Factors, Thale C. Jarvis, Amber A. Beaudry, James M. Bullard, Nebojsa Janjic, Charles S. Mchenry

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

DNA polymerase III holoenzyme is responsible for chromosomal replication in bacteria. The components and functions of Escherichia coli DNA polymerase III holoenzyme have been studied extensively. Here, we report the reconstitution of replicase activity by essential components of DNA polymerase holoenzyme from the pathogen Pseudomonas aeruginosa. We have expressed and purified the processivity factor (β), single-stranded DNA-binding protein, a complex containing the polymerase (α) and exonuclease (ϵ) subunits, and the essential components of the DnaX complex (τ₃δδ′). Efficient primer elongation requires the presence of αϵ, β, and τ₃δδ′. Pseudomonas aeruginosa αϵ can substitute completely for …

Alignment, Mechanical And Thermo-Physical Characterization Of Nanofiber-Reinforced Polyethylene, Veronica M. Diaz-Serrato

Theses and Dissertations - UTB/UTPA

Alignment of vapor grown carbon nano-reinforced polyethylene composites was performed using conventional extrusion processing methods. The alignment of the nanofibers within polyethylene, PE; the matrix, produced a material with anisotropic behavior. Mechanical and thermo-physical properties of the nanocomposite were studied. Enhancements in mechanical properties were investigated for pure PE, misaligned, and aligned specimens for stress versus strain, maximum load, and Young's modulus as high as 185, 273, and 80%, respectively. In fact, toughness was considerably high for the 10 rpm specimen when compared to other samples of different windup speeds. Thermo-physical studies were performed using differential scanning calorimetry (DSC) and …

Dna Polymerase Iii Holoenzyme From Thermus Thermophilus Identification Expression Purification Of Components And Use To Reconstitute A Processive Replicase, James M. Bullard, Jennifer C. Williams, Wendy K. Acker, Carsten Jacobi, Nebojsa Janjic, Charles S. Mchenry

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

DNA replication in bacteria is performed by a specialized multicomponent replicase, the DNA polymerase III holoenzyme, that consist of three essential components: a polymerase, the β sliding clamp processivity factor, and the DnaX complex clamp-loader. We report here the assembly of the minimal functional holoenzyme from Thermus thermophilus (Tth), an extreme thermophile. The minimal holoenzyme consists of α (pol III catalytic subunit), β (sliding clamp processivity factor), and the essential DnaX (τ/γ), δ and δ′ components of the DnaX complex. We show with purified recombinant proteins that these five components are required for rapid and processive DNA synthesis …

A Three-Domain Structure For The Delta Subunit Of The Dna Polymerase Iii Holoenzyme Delta Domain Iii Binds Delta' And Assembles Into The Dnax Complex, James M. Bullard, Arthur E. Pritchard, Min Sun Song, Bradley P. Glover, Anna Wieczorek, Joe Chen, Nebojsa Janjic, Charles S. Mchenry

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Using ψ-BLAST, we have developed a method for identifying the poorly conserved δ subunit of the DNA polymerase III holoenzyme from all sequenced bacteria. This approach, starting withEscherichia coli δ, leads not only to the identification of δ but also to the DnaX and δ′ subunits of the DnaX complex and other AAA⁺-class ATPases. This suggests that, although not an ATPase, δ is related structurally to the other subunits of the DnaX complex that loads the β sliding clamp processivity factor onto DNA. To test this prediction, we aligned δ sequences with those of δ′ and, using …

Interaction Of Mitochondrial Elongation Factor Tu With Aminoacyl-Trna And Elongation Factor Ts, Ying Chun Cai, James M. Bullard, Nancy L. Thompson, Linda L. Spremulli

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Elongation factor (EF) Tu promotes the binding of aminoacyl-tRNA (aa-tRNA) to the acceptor site of the ribosome. This process requires the formation of a ternary complex (EF-Tu·GTP·aa-tRNA). EF-Tu is released from the ribosome as an EF-Tu·GDP complex. Exchange of GDP for GTP is carried out through the formation of a complex with EF-Ts (EF-Tu·Ts). Mammalian mitochondrial EF-Tu (EF-Tu_mt) differs from the corresponding prokaryotic factors in having a much lower affinity for guanine nucleotides. To further understand the EF-Tu_mt subcycle, the dissociation constants for the release of aa-tRNA from the ternary complex (K _tRNA) and for …

Role Of Reactive Oxygen Species In Mercapto-Methylimidazole-Induced Gastric Acid Secretion And Stress-Induced Gastric Ulceration, Uday Bandyopadhyay, Dipak Das, Debasish Bandyopadhyay, Mrinalini Bhattacharjee, Ranajit K. Banerjee

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

The objective of the present study is to delineate the role of reactive oxygen species in drug-induced gastric hyperacidity and stress-induced gastric ulceration. We reported earlier that mercaptomethylimidazole (MMI), an antithyroid drug, induces gastric acid (HCl) secretion partially through H2receptor activation of the parietal cell by histamine release and partially through an intracellular mechanism. While studying the latter, MMI-induced acid secretion was found to correlate well with the inactivation of the peroxidase, an important H2O2metabolizing enzyme of the mucosa. MMI activates the isolated parietal cell for acid secretion, which is sensitive to omeprazole. Peroxidase and catalase activity of the isolated …