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Photodetachment of O-
No full textPhotodetachment of O- (2p5)2P° has been investigated with a new R-matrix (close-coupling) code [1] that uses a B-spline basis for the continuum functions. The completeness of the B-spline basis ensures that no Buttle correction is needed for the R-matrix elements. Another distinguishing feature of the present work is the use of non-orthogonal orbital sets in the construction of the target and the scattering wavefunctions. This allows us to employ a highly correlated target description without possibly introducing inconsistencies between the continuum and the bound parts of the trial wavefunction.
Our close-coupling expansion includes the lowest 25 bound and autoionizing states of neutral oxygen. Emphasis was placed on the accuracy of the target wavefunctions by describing each state (including the initial O- state) with a different set of orbitals, determined separately from state-specific multi-configuration Hartree-Fock calculations. Note that using non-orthogonal orbital sets directly accounts for relaxation effects during 2s or 2p excitation.
Our absolute values of the photodetachment cross sections exceed the experimental values [2] by 40%. The latter measurements were carried out 45 years ago, but the data are still being used today to normalize current photodetachment measurements. Our previous calculations of B- and C- photodetachment [3] also show excellent agreement with experiment for the energy dependence, but the theoretical absolute values exceed the experimental data by 35%. Note, however, that both the measured B- and C- photodetachment cross sections were normalized to the O- data from [2]. Such very similar discrepancies between the absolute values from three independent calculations with a single experiment suggest a possible systematic error in [2].
[1] O. Zatsarinny, Comp. Phys. Commun. 174 (2006) 273.
[2] S.J. Smith, Proc. 4th ICIPG, Uppsala (1959) IC219
[3] O. Zatsarinny and T.W. Gorczyca, Abstracts of XXIII ICPEAC, Stockholm (2003); We026, Th006.This work was supported by the National Science Foundation, under grants PHY-0244470 and PHY-0311161
Carbon-carbon bond formation via epititanation and aromatization of acetylenes
No full textThe dibutyltitanium(IV) diisopropoxide, Bu2Ti(OPri)2, reacts with acetylenes, RCºCR (1), where R = Ph, Pr, to undergo in high yield epimetalation with Ti(OPri)2 by transfer. Our on-going research has demonstrated the transformation of such three-membered titanacycles (2) into 1,2,4,5-tetrasubstituted benzene derivatives (4) in good yields upon reaction of (2) with monomeric acetylenes, R¢CºCH (3), R¢=Ph, Me3Si at room temperature over 2h. A 1:2 molar mixture of PhCºCPh and PhCºCH provided 90% of pure 1,2,4,5-tetraphenylbenzene.
The formation of such aromatic products is made possible via the insertion of the monomeric terminal acetylenes to one of the carbon – titanium bonds of (2) and the subsequent Diels-Alder type addition of the second equivalent of the terminal acetylene to the resulting five-membered titanacycles leading to the elimination of Ti(OPri)2
The Development of a Match to Sample Memory Task and Test of Impulsivity to Investigate Rat Models of Schizophrenia
Get PDFAnimal models of schizophrenia have been developed using chronic exposure to the dissociative anesthetics phencycladine (PCP) and ketamine to induce psychosis in rats. Preliminary research in our laboratory has shown marginal effects of low doses of PCP on the rat P300 event related potential (ERP) similar to those found in human male schizophrenics. As part of a broader program of research investigating the P300 ERP in a rat model of schizophrenia, we have been developing a battery of behavioral paradigms to test for memory deficits and impulsiveness that can be used to differentiate schizophrenic-like behavior from normal behavior in rats. The present research is directed toward developing a Y-maze match to sample (MTS) and a two lever MTS paradigm to screen for memory deficits. In these tests the rat receives a water reinforcer only if it chooses to run to the alley that was lighted or press the lever that was lighted during the sample phase. Memory is tested by inserting a delay interval during which the light cue disappears and the response is prevented. We are also developing a test of impulsivity in which the rat must inhibit a nose poke response until the third brief presentation of a light to obtain a water reinforcer. Early nose pokes result in a time out. Olin Hall construction delayed the initiation of this experiment. Accordingly preliminary results will be presented
The Solubilization mechanism of benzyl esters in sodium dodecyl sulfate (SDS) micelles
No full textMicelles are aggregates of surfactant molecules used to increase the solubility and bioavailability of poorly soluble pharmaceutical compounds. Past studies have suggested that a micelle is an oil droplet surrounded by a layer of water. To further investigate the microenvironment of a micelle, the thickness of water penetration was not clearly understood. To study the mechanism of micellar solubilization, we have purchased and synthesized several benzyl esters derivatives. Alkyl chain length of the acid segment was increased from one as in benzyl acetate to ten carbons as in benzyl decanoate. Partition coefficients of each benzyl ester were determined from kinetic data using pseudo phase mathematical model. Degradation studies were conducted using borate buffer at pH 9 and constant temperature (40ºC). Surfactants (SDS) were dissolved in the buffer solution at varying concentrations to extend the concentration range below and above the critical micelle concentration. Reaction products were analyzed using high performance liquid chromatography HPLC and detected using UV detector at 254 nm. Hydrolysis reaction rate constants followed pseudo first order mechanism. Rate constants decreased as the surfactant concentrations have increased. Also, water solubility decreased as the alkyl chain length was increased which consequently caused the water-micelle partition coefficients to increase. To further understand the interaction between benzyl esters and micelles we introduced a linear interaction model where we proposed that each benzyl ester will fit into the micelle with linear orientation where the alkyl chain is pointed towards the core interacting with the hydrophobic region while the benzene ring is located in the hydrophilic region of the micelle
HPG function in men and women stratified by drug use and HIV status
Get PDFMost studies of hypothalamic-pituitary-gonadal (HPG) function and depression in illicit drug users focus only on men or do not consider the impact of HIV infection along with drug use. This study investigated relationships between illicit drug use and HIV status with depressive symptoms and HPG function in both men and women. Illicit drug use and HIV status were differentially associated with HPG function and depressive symptoms in men and women. Specifically, free testosterone concentrations were lower in men who use drugs and in women who are HIV positive. Estradiol concentrations were marginally lower in women, but not in men, who are HIV positive. Women and drug users reported the most depressive symptoms; however, impaired HPG function was associated with increased depressive symptoms in men only. Neither HPG function nor depression was impacted in an additive or synergistic manner by both drug use and HIV in either sex. These data indicate that illicit drug use is associated with altered HPG function in men and HIV infection is associated with altered HPG function in women. Furthermore, altered HPG function was associated with depressive symptoms in men, but not in women. Sex specific natural histories of illicit drug use and HIV infection, as they relate to endocrine and mental health, suggest a potential role for sex specific treatments to ameliorate these problems. The present data support recommendations of The National Academy of Science to consider gender differences in medical research
Assessing gene expression by real-time polymerase chain reaction
No full textEnd-point Polymerase Chain Reaction (PCR) is a highly sensitive technique that can be used to assess gene expression in limited tissue/cell samples. However, accurately quantifying gene expression with this method is tedious and inconsistent if not performed properly. Real-time PCR refers to using fluorescent probes that bind double-stranded DNA to monitor DNA product formation during PCR. The number of cycles required for the amplicon fluorescence to reach a threshold level is inversely correlated with the initial amount of target sequence present. The present study compared end-point and real-time PCR techniques to determine whether hypoxia alters growth factor mRNA expression in cardiomyocytes. We chose to assess placenta growth factor (PIGF) expression, an important angiogenic factor with normally low level expression outside of the placenta. End-point RT-PCR showed that cardiomyocytes express PIGF and its receptor, VEGFR1, mRNA under normal culture conditions. Cells were cultured under normoxic (N; 21%O2) or hypoxic (H; <2%O2) conditions for 1, 3, 6, 12 or 24 hours and total RNA was isolated, reverse transcribed and resultant cDNA was used to assess changes in PIGF mRNA expression by end-point PCR (figure). After optimization, the induction of PIGF mRNA expression at 12/24 hours of hypoxia were confirmed using real-time PCR: 12 hour = 3.88 ± 0.62 fold increase (n=6; p<0.05); 24 hour = 3.64 ± 0.41 fold increase (n = 6; p< 0.05). The results demonstrate very good concordance between real-time and end-point PCR.
The main advantages of real-time over end-point PCR are: 1) its ability to measure DNA concentrations over a wider range, 2) higher throughput, 3) more quantitative than end-point PCR, and 4) no post-PCR handling is necessary. In conclusion, real-time PCR can accommodate for a wider variance in initial gene expression between samples and allows for more in-depth and rapid quantification of gene expression
Circular polarization in PKS 1519-273
No full textThe intra-day variable BL Lac PKS 1519-273 exhibits variations at centimeter wavelengths in total intensity, linear polarization, and circular polarization. The variability is caused by scintillation due to the interstellar medium. PKS 1519-273 displays 4% circular polarization at 4.8 GHz and the variability has persisted as long as the source has been observed. We present observations of this source over several years, showing that the circularly polarized emission is highly variable on micro-arcsecond scales. We determine structural properties of the emission by examining the light curves and associated scintillation theory
Coca-Cola Classic
Get PDFBlue, Inc. is composed of the following students: Tracey Bien, Ryan Summerfelt, Sheryl Loren, Tiffany Mitchell, Holly Reynolds, Amanda Gunther, Adrianne Konrad, Larry Luckett, Bailey Posnick, Sara Withers, Susan Mainquist, Katie Leick, Jasmine Teo, Ben Truehart, James Bridgeford, Gina DiCesare, Emily Vraspir, Emily Sexton, Stacy Boerema, Justin Vaught, Sarah Elliott, Ellen Won, Mara Brettner, Lauren Smith, Joel Brewer, Zach Hayden, Pamela McNew, Jennifer Reff, Kathleen Anderson, Ajay Calvin, Jacquie Koepsel, Andrew Roger, Nick Grant, Jesse Sparks.This journalism class project (JMC145: Advertising Campaign Strategies) shows the presentation from Drake University competing in the National Student Advertising Competition. Students from college and university A.A.F. chapters competed in creating an advertising and marketing campaign for the contest sponsor, Coca-Cola Classic. The students were challenged to create an integrated marketing campaign emphasizing a unique product
Biobehavioral responses to conditioned fear and restraint stress in borderline hypertensive rats (BHR)
Get PDFThe purpose of this experiment was to determine the effects of an early environmental manipulation, handling (H), on cardiovascular (CV) reactivity, freezing behavior and corticosterone (CORT) responses to fear conditioning in the BHR, which is genetically susceptible to environmental stressors. H subjects were separated from the nest for 15 mins/day on post-natal days 1-14, while non-handled (NH) controls remained in the home cage. Adult BHR from each group were implanted with a femoral arterial catheter for mean arterial pressure (MAP) recording and blood sampling. Two days later, subjects were exposed to the fear conditioning procedure. Subjects were returned to the chamber the next day for 10 min during which time freezing behavior, CV responses and CORT measurements were taken. H subjects displayed significantly more freezing behavior compared to NH (92%±2.2 vs. 80.7%±5.7, p < .05). Although resting MAP did not differ between groups, H subjects had increased MAP reactivity when returned to the fear conditioning chamber (p < .01). Finally, H subjects had significantly lower CORT levels at the end of the 10 min test period (173±8 ng/ml vs. 217.7±22.2 ng/ml, p < .05). In a separate experiment, H subjects showed reduced CORT levels in response to acute restraint stress. These results indicate that neonatal H produces enhanced biobehavioral responses to fear conditioning in BHR and may suggest a useful model with which to study the interaction of genetics, emotionality, and heart disease.NIH grant HL07389
Analysis of mRNA changes as a function of learning and methamphetamine exposure
No full textMethamphetamine is a powerful, addictive drug that is of great concern in Iowa and the Midwest. Powerful methamphetamine abuse is correlated with depression and learning disabilities (e.g. attention deficit disorder). Although the mechanism of action of methamphetamine in the brain has been well characterized at the cellular and synaptic level, the effects of this drug at the genetic level are not well understood. To analyze the possible effects of methamphetamine on learning, we are using real-time PCR to investigate changes in gene expression (i.e., messenger RNA levels) in rat brains as a function of learning and exposure to methamphetamine. Specifically, we are analyzing relative mRNA levels from genes whose products have been implicated in learning and/or addiction: GABA receptors, dopamine receptors, and glutamate (NMDA) receptors. Comparison of these data sets is expected to reveal potential cellular and molecular mechanisms involved in producing drug-induced learning disabilities