Novel standards in the measurement of rat insulin granules combining electron microscopy, high-content image analysis and in silico modelling

Knowledge of number, size and content of insulin secretory granules is pivotal for understanding the physiology of pancreatic beta cells. Here we re-evaluated key structural features of rat beta cells, including insulin granule size, number and distribution as well as cell size

High resolution infrared spectroscopy of carbon dioxide clusters up to (CO 2) 13

Thirteen specific infrared bands in the 2350 cm -1 region are assigned to carbon dioxide clusters, (CO 2) N, with N = 6, 7, 9, 10, 11, 12 and 13. The spectra are observed in direct absorption using a tuneable infrared laser to probe a pulsed supersonic jet expansion of a dilute mixture of CO 2 in He carrier gas. Assignments are aided by cluster structure calculations made using two reliable CO 2 intermolecular potential functions. For (CO 2) 6, two highly symmetric isomers are observed, one with S 6 symmetry (probably the more stable form), and the other with S 4 symmetry. (CO 2) 13 is also symmetric (S 6), but the remaining clusters are asymmetric tops with no symmetry elements. The observed rotational constants tend to be slightly ( 482%) smaller than those from the predicted structures. The bands have increasing vibrational blueshifts with increasing cluster size, similar to those predicted by the resonant dipole-dipole interaction model but significantly larger in magnitude. \ua9 2011 American Institute of Physics.Peer reviewed: YesNRC publication: Ye

Fundamental and torsional combination bands of two isomers of the OCS-CO2 complex in the CO2 \u3bd3 region

Spectra of two isomers of the weakly bound complex OCS-CO2 are observed in the region of the CO2 \u3bd3 fundamental vibration ( 3c2349 cm-1), using an infrared tunable diode laser to probe a pulsed supersonic slit-jet expansion. Two bands are measured and analyzed for each isomer, the fundamental asymmetric stretch of the CO 2 component and a combination band involving this fundamental plus the intermolecular out-of-plane torsional mode. For one isomer, the corresponding torsional combination band is also detected in the OCS \u3bd1 stretching region ( 3c2060 cm-1). The resulting torsional frequencies are found to be 18.8 and 15.9 cm-1 for isomers a and b of OCS-CO2, respectively. This may be the first time that such a combination band is observed for a higher-energy isomer of a weakly bound complex. \ua9 2013 American Chemical Society.Peer reviewed: YesNRC publication: Ye

NEW INFRARED SPECTRA OF THE NITROUS OXIDE TRIMER

Author Institution: Department of Physics and Astronomy, University of Calgary; Calgary, AB T2N 1N4, CANADA; Steacie Institute for Molecular Sciences, National Research; Council of Canada, Ottawa, ON K1A 0R6, CANADAInfrared spectra of N$_{2}$O trimers are studied using a tunable diode laser to probe a pulsed supersonic slit-jet expansion. A previous observation by R.E. Miller and L. Pedersen [J. Chem. Phys. \textbf{108}, 436 (1998)] in the N$_{2}$O \nub{1}+\nub{3} combination band region (~3480 cm$^{-1}$) showed the trimer structure to be noncyclic, with three inequivalent N$_{2}$O monomer units which could be thought of as an N$_{2}$O dimer (slipped antiparallel configuration) plus a third monomer unit lying above the dimer plane. The present observations cover the N$_{2}$O fundamental band regions \nub{3} (~1280 cm$^{-1}$) and \nub{1} (~2230 cm$^{-1}$). In the \nub{3} region, two trimer bands are assigned with vibrational shifts and other characteristics similar to those in the \nub{1}+\nub{3} region, but in the \nub{1} region all three possible trimer bands are observed. Relationships among the various bands such as rotational intensity patterns, vibrational shifts, and the properties of the related N$_{2}$O dimer, generally support the conclusions of Miller and Pedersen. Three trimer bands are also observed for the fully$\ ^{15}$N-substituted species in the \nub{1} region, and these results should aid in detection of the as-yet-unobserved pure rotational microwave spectrum of the trimer. Finally, three combination bands involving the intermolecular van der Waals modes at 2253.7, 2255.5, and 2269.4 cm$^{-1}$ have been measured. The analyses of these bands and the identification of the nature of the intermolecular modes involved are currently underway

INFRARED SPECTRA OF (CO2_{2})2_{2}-OCS COMPLEX: INFRARED OBSERVATION OF TWO DISTINCT BARREL-SHAPED ISOMERS

Author Institution: Department of Physics and Astronomy, University of Calgary, Calgary, AB T2N; 1N4, Canada; Steacie Institute for Molecular Sciences, National Research Council of; Canada, Ottawa, ON K1A 0R6, CanadaSpectra of (CO$_{2}$)$_{2}$-OCS complex in the region of the OCS $\nu _{1}$ fundamental ( $\sim$2062 cm$^{-1}$) are observed using a tunable diode laser to probe a pulsed supersonic slit jet expansion. A previous microwave study of the complex by Peebles and Kuczkowskia gave a distorted triangular cylinder. The geometerical disposition of the three dimer faces of this trimer are quite similar to the slipped CO$_{2}$ dimer, the lowest energy form of OCS-CO$_{2}$ (isomer a), also observed and analyzed in the microwave region, and the higher energy form of OCS-CO$_{2}$ (isomer b), first observed by our group in the infrared region. Here we report the observation and analysis of two infrared bands, corresponding to two distinct isomers of the (CO$_{2}$)$_{2}$-OCS complex. A band around 2058.8 cm$^{-1}$ was assigned to isomer I, which is the same as that studied previously by microwave spectroscopy. A second band around 2051.7 cm$^{-1}$ was assigned to a higher energy isomer of the complex, isomer II, has not been observed previously, but expected on the basis of \textit{ab initio} calculations. Approximate structural parameters for this new isomer were obtained by means of isotopic substitution. In contrast to isomer I, the geometerical disposition of the faces containing OCS and CO$_{2}$ in isomer II are similar to isomer b of the OCS-CO$_{2}$ complex