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Hypervalent dimethyloxonium radical, (CH3)2O&z.sbnd;H⋅ (1), is formed by collisional electron transfer to protonated dimethyl ether in the gas phase and dissociates rapidly by cleavage of the O&z.sbnd;H and O&z.sbnd;C bonds. Ab initio and density functional theory calculations show that these dissociations originate from different electronic states of 1. The loss of H proceeds from the repulsive ground electronic (X) state of 1 and is 131 kJ mol−1 exothermic to form vibrationally excited (CH3)2O. The loss of methyl proceeds from the first excited electronic (A) state of 1 by crossing to the repulsive part of the X state potential energy surface, yielding vibrationally excited methanol. A substantial fraction of deuterated radicals, (CH3)2O&z.sbnd;D⋅ (1-OD), are metastable on the microsecond time scale. The metastable species result from the population of the B and higher excited states of 1 that are calculated to be bound along both O&z.sbnd;H and O&z.sbnd;C coordinates. The isotope effects on the metastability of 1 are explained by less efficient vibronic coupling between the bound B and dissociative A states in the deuterated radical. [Copyright &y& Elsevier]

The first resonance Raman spectra of nitrosyl chloride (ClNO) in solution obtained with excitation resonant with the A-band are reported. For ClNO dissolved in cyclohexane, intensity is observed for transitions corresponding to all three normal coordinates: the bend, NCl stretch and NO stretch. This observation demonstrates that excited-state structural evolution occurs along these coordinates following photoexcitation resonant with the A-band. Resonance Raman depolarization ratios measured at excitation wavelengths spanning the A-band are reported. The depolarization ratios are found to be less that 1/3 consistent with at least two electronic transitions contributing to the A-band absorption intensity. [Copyright &y& Elsevier]

New experimental and analysis methods for investigating the role local environment has on photoluminescence intermittency (PI) exhibited by single luminophores are presented. Quasi-single molecule (SM) microscopy provides spatial resolution of dielectric environments within poly(vinylidene fluoride) (PVDF) films, and reveals annealing's effect on the structural phase of PVDF. New analysis methods establish that the PI exhibited by nile red (NR) SMs in PVDF are consistent with photoinduced electron transfer between NR and PVDF, where transfer rates depend on local dielectric environment. These methods should prove useful for SM studies of guest–host materials where elucidating PI contribution from the host is required. [ABSTRACT FROM AUTHOR]

Abstract: Copepods represent the major part of the dry weight of the mesozooplankton in pelagic ecosystems and therefore have a central role in the secondary production of the North Atlantic Ocean. The calanoid copepod species Calanus finmarchicus is the main large copepod in subarctic waters of the North Atlantic, dominating the dry weight of the mesozooplankton in regions such as the northern North Sea and the Norwegian Sea. The objective of this work was to investigate the relationships between both the fundamental and realised niches of C. finmarchicus in order to better understand the future influence of global climate change on the abundance, the spatial distribution and the phenology of this key-structural species. Based on standardised Principal Component Analyses (PCAs), a macroecological approach was applied to determine factors affecting the spatial distribution of C. finmarchicus and to characterise its realised niche. Second, an ecophysiological model was used to calculate the Potential Egg Production Rate (PEPR) of C. finmarchicus and the centre of its fundamental niche. Relationships between the two niches were then investigated by correlation analysis. We found a close relationship between the fundamental and realised niches of C. finmarchicus at spatial, monthly and decadal scales. While the species is at the centre of its niche in the subarctic gyre, our joint macroecological and macrophysiological analyses show that it is at the edge of its niche in the North Sea, making the species in this region more vulnerable to temperature changes. [Copyright &y& Elsevier]

Abciximab decreases adverse cardiac ischemic events, and in some subgroups, decreases the need for revascularization after percutaneous coronary intervention (PCI). However, abciximab may cause bleeding complications and thrombocytopenia after PCI. We hypothesized that the efficacy and safety of PCI would be maintained, if not improved, when performed using abciximab accompanied by only minimal doses (≤1,000 U) of unfractionated heparin. In this prospectively designed observational study, we assessed 500 consecutive patients who underwent PCI, consisting of either stent deployment or high-speed rotational atherectomy, and who received abciximab accompanied by only a minimal dose of unfractionated heparin, as directed by a novel dosing strategy: (1) if the patient was previously receiving an infusion of heparin, then it was terminated upon arrival to the cardiac catheterization laboratory, and no further heparin was administered; or (2) if the patient was not receiving an infusion of heparin, then a single bolus infusion of 1,000 U was administered after establishment of vascular access. The median activated clotting time for the patients during PCI was 168 seconds (25% quartiles, 153 to 185). The technical success rate was 99.8%. There were no major adverse clinical events during the 24 hours after PCI. The incidence of non–Q-wave myocardial infarction was 1.6%. The incidences of major and minor bleeding complications were 0.2% and 3.6%, respectively, and the incidence of thrombocytopenia was 2.2%. During the 30 days after PCI, there was 1 major adverse clinical event (0.2%). During the 1 year after PCI, among the remaining patients, there were 92 adverse events (18.4%). We conclude that, in the context of historical data, the efficacy and safety of PCI using either stent deployment or high-speed rotational atherectomy is maintained, if not improved, when performed using abciximab accompanied by only minimal doses of unfractionated heparin. [Copyright &y& Elsevier]

Raman and infrared spectra of isopropyl nitrate and isobutyl nitrate are reported. These spectra are used in combination with computational studies employing density functional theory at the B3-LYP/6-31G* level to assign the vibrational transitions to their corresponding normal coordinates. Similar to other alkyl nitrates, the frequency of the NO2 symmetric stretch remains relatively unchanged while the asymmetric stretch shifts to lower frequency with increasing α-carbon substitution. The mode assignments involving the photochemically relevant &z.sbnd;ONO2 chromophore agree well with those from previous infrared work. Raman depolarization ratios are also presented, and provide evidence that the condensed phase, ground-state molecular structure of isobutyl nitrate is of Cs symmetry. In contrast, the minimum energy structure of isopropyl nitrate is predicted to contain a pronounced twist around the C&z.sbnd;O bond relative to the Cs-symmetry structure that lies 2.6 kcal/mol higher in energy. Infrared intensities of isopropyl nitrate are consistent with the twisted geometry, demonstrating that this conformer is favored in solution. [Copyright &y& Elsevier]

Selected Baltic Sea watershed River Runoff (BSRR) events during 1970–2000 were used as predictor in Generalised Linear Mixed Models (GLIMMIX) for evidence of simultaneous changes/chain of events (including possible time lags) in some chemical, physical and biological variables in the Baltic and North Sea ecosystems. Our aim was to explore for climatic-based explanation for ecological regime shifts that were documented semi-simultaneously in both ecosystems. Certain similarities were identified in the North Sea and the Baltic Sea salinity, oxygen concentration, temperature and phyto- and zooplankton parameters. These findings suggest that BSRR events which originate in the Baltic Sea catchment area modify and contribute to large scale ecosystem changes not only in the Baltic Sea, but also in the adjacent parts of the North Sea. However, the Baltic Sea inter-annual and inter-decadal variabilities of physical and biological parameters are driven by direct atmospheric forcing, typically with a relatively short lag. In contrast, such changes in the North Sea are influenced by both local and direct atmospheric forcing, typically with a longer lag than in the Baltic, and a more regional, indirect forcing from changes in the North Atlantic. We suggest that this interactive system partially is behind large scale ecosystem regime shifts found in both Seas. During our study period two such shifts have been identified independently from us in a study earlier in the Southern and Central Baltic in 1980s and 1990s and a later one in 2001/2002 in the North Sea. As a post hoc test we compared the 0+ year class strength of the North Sea herring with BSRR intensity, and found evidence for higher herring production in high BSRR periods, which further corroborates the idea of a remote effect from the large watershed area of the Baltic. Regime shifts as well as their semi-synchronous appearance in two neighbouring sea areas could be identified. GLIMMIX models provide opportunities for determining and understanding the mechanisms behind marine ecosystem long-term and large-scale changes. Many studies have shown the importance of climatic factors (identified by the air pressure index, North Atlantic Oscillation) to the physical and biological changes over the North Atlantic. Our study enlarges the areal and temporal scope of these observations, and provides further support and explanation for climate as the pacemaker for marine ecological changes. [ABSTRACT FROM AUTHOR]

Abstract: In order to explore the effects of incorporation of an amino-phenyl-thienyl (APT) donor moiety into state-of-the art donor-bridge-acceptor organic NLO chromophores, two new materials were synthesized and characterized. Density functional theory (DFT) quantum-mechanical modeling indicates that this structural modification, producing enhanced ground-state electron density asymmetry and increased conjugation length, should lead to appreciable enhancement in first molecular hyperpolarizability (β). Previous empirical data suggests that such an approach to enhancements in nonlinearity may overcome the tradeoffs in nonlinearity with optical absorption and thermal stability, often encountered in organic NLO chromophore design. Material properties were evaluated in terms of poling-induced electro-optic coefficients normalized against applied poling field (r 33/E p), DFT calculated β and gas-phase dipole moment, experimentally determined β HRS, absorption maxima, and thermal stability. These data were then compared against those from benchmark materials. Experimental data were determined to reflect enhancements in nonlinearity with little detriment to thermal stability and optical absorption, making them excellent candidates for use in electro-optic polymer applications. The most active material (C3) demonstrated highly reproducible values of r 33 =130pm/V. [Copyright &y& Elsevier]

Abciximab decreases adverse cardiac ischemic events, and in some subgroups, decreases the need for revascularization after percutaneous coronary intervention (PCI). However, abciximab may cause bleeding complications and thrombocytopenia after PCI. We hypothesized that the efficacy and safety of PCI would be maintained, if not improved, when performed using abciximab accompanied by only minimal doses (< or =1,000 U) of unfractionated heparin. In this prospectively designed observational study, we assessed 500 consecutive patients who underwent PCI, consisting of either stent deployment or high-speed rotational atherectomy, and who received abciximab accompanied by only a minimal dose of unfractionated heparin, as directed by a novel dosing strategy: (1) if the patient was previously receiving an infusion of heparin, then it was terminated upon arrival to the cardiac catheterization laboratory, and no further heparin was administered; or (2) if the patient was not receiving an infusion of heparin, then a single bolus infusion of 1,000 U was administered after establishment of vascular access. The median activated clotting time for the patients during PCI was 168 seconds (25% quartiles, 153 to 185). The technical success rate was 99.8%. There were no major adverse clinical events during the 24 hours after PCI. The incidence of non-Q-wave myocardial infarction was 1.6%. The incidences of major and minor bleeding complications were 0.2% and 3.6%, respectively, and the incidence of thrombocytopenia was 2.2%. During the 30 days after PCI, there was 1 major adverse clinical event (0.2%). During the 1 year after PCI, among the remaining patients, there were 92 adverse events (18.4%). We conclude that, in the context of historical data, the efficacy and safety of PCI using either stent deployment or high-speed rotational atherectomy is maintained, if not improved, when performed using abciximab accompanied by only minimal doses of unfractionated heparin. [ABSTRACT FROM AUTHOR]