Synthesis and dopaminergic activity of trans-4-methyl-3-phenylpyrrolidines

tran-3-(3,4-Dihyroxyphenyl)-4-methyl-1-(n-propyl)pyrrolidine 13 trans-3-(3-Hydroxyphenyl)-4-methyl-1(n-propy)pyrrolidine 14 were synthesized and evaluated for dopaminergic activity. The stereochemical assignments of 13 and 14 were determined by nmr. Both 13 and 14 were either inactive or weakly active in most dopaminergic tests.     

D atom loss in the photodissociation of the DNCN radical: implications for prompt NO formation

The photodissociation of DNCN following excitation of the C 2A"<--X 2A" electronic transition was studied using fast beam photofragment translational spectroscopy. Analysis of the time-of-flight distributions reveals a photodissociation channel leading to D+NCN competitive with the previously observed CD+N2 product channel. The translational energy distributions describing the D+NCN channel are peaked at low energy, consistent with internal conversion to the ground state followed by statistical decay and the absence of an exit barrier. The results suggest a relatively facile pathway for the reaction CH+N2-->H+NCN that proceeds through the HNCN intermediate and support a recently proposed mechanism for prompt NO production in flames.     

A study of measured neutron elastic differential neutron cross sections for 23Na

Elastic neutron scattering angular distributions from ²³Na have been measured for incident neutron energies between 1.0 and 4.0 MeV at the University of Kentucky Accelerator Laboratory using neutron time-of-flight techniques for the scattered neutrons. This is an energy region in which existing data are very sparse. Measurements are compared with the predictions of the light particle-induced reaction code TALYS. The calculations reproduce forward angle scattering but have difficulty with relative minima in the differential cross section and large-angle scattering.     

Local dielectric spectroscopy of near-surface glassy polymer dynamics

A noncontact scanning probe microscopy method was used to probe local near-surface dielectric susceptibility and dielectric relaxation in polyvinyl acetate near the glass transition. Dielectric spectra were measured from 10(-4) to 10(2) Hz as a function of temperature. The measurements probed a 20 nm thick layer below the free surface of a bulk film. A significant change in the fragility index and moderate narrowing of the distribution of relaxation times were found in the near-surface layer. In contrast to results for ultrathin films confined on or between metallic electrodes, no reduction in the dielectric strength was found, inconsistent with the immobilization of slower modes.     

A structure-based approach to understanding somatostatin receptor-4 agonism (sst4)

It has been reported that somatostatin receptor subtypes 4 and 5 would be high-impact templates for homology modeling if their 3D structures became available. We have generated a homology model of the somatostatin receptor subtype 4 (sst4), using the newest active state β(2) adrenoreceptor crystal structure, and subsequently docked a variety of agonists into the model-built receptor to elucidate the binding modes of reported agonists. Using experimental restraints, we were able to explain observed activity profiles. We propose two binding modes that can consistently explain findings for high-affinity agonists and reason why certain structures display low affinities for the receptor.     

Two- and three-body photodissociation dynamics of diiodobromide (I2Br-) anion

The photodissociation of gas-phase I(2)Br(-) was investigated using fast beam photofragment translational spectroscopy. Anions were photodissociated from 300 to 270 nm (4.13-4.59 eV) and the recoiling photofragments were detected in coincidence by a time- and position-sensitive detector. Both two- and three-body channels were observed throughout the energy range probed. Analysis of the two-body dissociation showed evidence for four distinct channels: Br(-) + I(2), I(-) + IBr, Br+I(2) (-), and I + IBr(-). In three-body dissociation, Br((2)P(3∕2)) + I((2)P(3∕2)) + I(-) and Br(-) + I((2)P(3∕2)) + I((2)P(3∕2)) were produced primarily from a concerted decay mechanism. A sequential decay mechanism was also observed and attributed to Br(-)((1)S)+I(2)(B(3)Π(0u) (+)) followed by predissociation of I(2)(B).     

A study of valence band shake-up features of CO on Pt {100} using synchrotron radiation

A study of the shake-up features in the valence region of CO on Pt{100} is presented. The onset of these features is shown to be correlated with the excitation threshold for the Pt(4f) levels. A possible mechanism for the shake-up process is proposed in which the Pt(4f) hole results in excited states other than a single electron-hole state. Subsequently, the Pt(4f) hole decays via a direct recombination process resulting in the observed satellite features. The implications of such a shake-up process for photon-stimulated desorption (PSD) are also discussed.     

Synthesis of cis-4-methyl-3-phenylpyrrolidines as potential dopaminergic agonists

cis-3-(3,4-Dihydroxyprienyl)4-methyl-1-(n-propyl)pyrrolidine ( 23 ) was synthesized and evaluated for dopaminergic activity. The synthesis of 23 involved selective 4-acylation of the 3-phenylpyrrolidine-2,5-dione 15 and cis-addition of hydrogen to a 4-methyl-3-phenyl-3-pyrroline 4 . Pharmacological evaluation of 23 showed that introduction of a cis-4-methyl group into the 3-phenylpyrrolidine nucleus decreases dopaminergic activity.     

The effect of analyte concentration range on measurement errors obtained by NIR spectroscopy

Near infrared spectroscopy (NIRS) was employed to quantify five compounds, ammonium, glucose, glutamate, glutamine, and lactate, in conditions similar to those obtained in animal cell cultivations over varying ranges of analyte concentrations. These components represent the primary nutrients and wastes of animal cells for which such noninvasive monitoring schemes are required for development of accurate control schemes. Ideal cultivation conditions involve maintaining concentrations of these components as low as 1 mM each, however, it is not known if measurements of these compounds can be accurately accomplished at such a low level. We have found that NIRS measurements of these analytes over narrow and low (0-1 mM) concentration ranges yield measurement errors of roughly 11% of the concentration range. By contrast, wide concentration ranges (0-30 mM) yield measurement errors of roughly 1.6% of the concentration range. Decreasing the concentration range over which an analyte is quantified in four out of five cases decreases the optimal spectral range by 100 cm(-1) for measurement by partial least squares regression analysis. There appears a similarity in the ratio of (standard error of prediction (SEP)/concentration range) which may provide an estimation of the anticipated SEP to be obtained for measurement over a new concentration range. It was found that for the five analytes evaluated here, the ratio of SEP to concentration range divided by that obtained for a second concentration range is equal to a fairly constant value of 6.6. This relationship was found to be followed reasonably well by an extensive number of measurement results reported in the literature for similar conditions.