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Emission Data (emission + data)
Selected AbstractsTheoretical study on the spectroscopic properties and electronic structures of heteroleptic phosphorescent Ir(III) complexesINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 6 2009Min Zhang Abstract The geometries, spectroscopic and electronic structures properties of a series of heteroleptic phosphorescent Ir(III) complexes including N981, N982, N983, N984 have been characterized by density functional theory calculations. The excited-state properties of the Ir(III) complexes have been characterized by CIS method. The ground- and excited-state geometries were optimized at the B3LYP/LANL2DZ and CIS/LANL2DZ levels, respectively. By using the time-dependent density functional theory method, the absorption and phosphorescence spectra were calculated based on the optimized ground- and excited-state geometries, respectively. The results show that the absorption and emission data agree well with the corresponding experimental results. The calculated results also revealed that the nature of the substituent at the 4-position of the pyridyl moiety can influence the distributions of HOMO and LUMO and their energies. In addition, the charge transport quality has been estimated approximately by the calculated reorganization energy (,). Our result also indicates that the positions of the substitute groups not only change the transition characters but also affect the charge transfer rate and balance, and complex N982 is a very good charge transfer material for green OLEDs. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Freeze,thaw-induced embolism in Pinus contorta: centrifuge experiments validate the ,thaw-expansion hypothesis' but conflict with ultrasonic emission dataNEW PHYTOLOGIST, Issue 4 2010Stefan Mayr Summary ,The ,thaw-expansion hypothesis' postulates that xylem embolism is caused by the formation of gas bubbles on freezing and their expansion on thawing. We evaluated the hypothesis using centrifuge experiments and ultrasonic emission monitoring in Pinus contorta. ,Stem samples were exposed to freeze,thaw cycles at varying xylem pressure (P) in a centrifuge before the percentage loss of hydraulic conductivity (PLC) was measured. Ultrasonic acoustic emissions were registered on samples exposed to freeze,thaw cycles in a temperature chamber. ,Freeze,thaw exposure of samples spun at ,3 MPa induced a PLC of 32% (one frost cycle) and 50% (two cycles). An increase in P to ,0.5 MPa during freezing had no PLC effect, whereas increased P during thaw lowered PLC to 7%. Ultrasonic acoustic emissions were observed during freezing and thawing at ,3 MPa, but not in air-dried or water-saturated samples. A decrease in minimum temperature caused additional ultrasonic acoustic emissions, but had no effect on PLC. ,The centrifuge experiments indicate that the ,thaw-expansion hypothesis' correctly describes the embolization process. Possible explanations for the increase in PLC on repeated frost cycles and for the ultrasonic acoustic emissions observed during freezing and with decreasing ice temperature are discussed. [source] Characteristics of environmental reporters on the OM Stockholm exchangeBUSINESS STRATEGY AND THE ENVIRONMENT, Issue 5 2002Pontus Cerin External validation of company environmental performance is normally based on corporate environmental reports, due to the lack of other information. Critics of these reports, however, claim that these are no more than public relations exercises, consisting mainly of wordy descriptions and glossy pictures. It is therefore important to turn the spotlight on the real character of the companies behind the reports. Fewer than 10% of the companies listed on the OM Stockholm Exchange, however, provide documented environmental reports on the Internet (DERI) annually. The highest DERI percentages are found among those industry sectors that began reporting some ten years ago. Data from the Dow Jones Country Index Sweden shows that DERI producers have an average market capitalization some six times greater than non-producers. Moreover, the DERI producers emitted twice as much CO2 per turnover as the non-DERI producers. The fact that less than half of the companies on the OM Stockholm Exchange presented CO2 emission data somewhat weakens the conclusions on emissions. The fact that 60% of the DERI producers could not provide complete CO2 emission data for their companies does say something concrete about the usefulness of current DERIs as a tool for externally determining company environmental performance characteristics. Copyright © 2002 John Wiley & Sons, Ltd and ERP Environment. [source] Role of land cover changes for atmospheric CO2 increase and climate change during the last 150 yearsGLOBAL CHANGE BIOLOGY, Issue 8 2004Victor Brovkin Abstract We assess the role of changing natural (volcanic, aerosol, insolation) and anthropogenic (CO2 emissions, land cover) forcings on the global climate system over the last 150 years using an earth system model of intermediate complexity, CLIMBER-2. We apply several datasets of historical land-use reconstructions: the cropland dataset by Ramankutty & Foley (1999) (R&F), the HYDE land cover dataset of Klein Goldewijk (2001), and the land-use emissions data from Houghton & Hackler (2002). Comparison between the simulated and observed temporal evolution of atmospheric CO2 and ,13CO2 are used to evaluate these datasets. To check model uncertainty, CLIMBER-2 was coupled to the more complex Lund,Potsdam,Jena (LPJ) dynamic global vegetation model. In simulation with R&F dataset, biogeophysical mechanisms due to land cover changes tend to decrease global air temperature by 0.26°C, while biogeochemical mechanisms act to warm the climate by 0.18°C. The net effect on climate is negligible on a global scale, but pronounced over the land in the temperate and high northern latitudes where a cooling due to an increase in land surface albedo offsets the warming due to land-use CO2 emissions. Land cover changes led to estimated increases in atmospheric CO2 of between 22 and 43 ppmv. Over the entire period 1800,2000, simulated ,13CO2 with HYDE compares most favourably with ice core during 1850,1950 and Cape Grim data, indicating preference of earlier land clearance in HYDE over R&F. In relative terms, land cover forcing corresponds to 25,49% of the observed growth in atmospheric CO2. This contribution declined from 36,60% during 1850,1960 to 4,35% during 1960,2000. CLIMBER-2-LPJ simulates the land cover contribution to atmospheric CO2 growth to decrease from 68% during 1900,1960 to 12% in the 1980s. Overall, our simulations show a decline in the relative role of land cover changes for atmospheric CO2 increase during the last 150 years. [source] Evidence for surviving outer hair cell function in congenitally deaf ears,THE LARYNGOSCOPE, Issue 11 2003FRCS (London), FRCS (ORL-HNS), Peter A. Rea MA Abstract Objective/Hypothesis: The hypotheses of the study were that congenital hearing impairment in infants can result from the isolated loss of inner hair cells of the cochlea and that this is shown by the presence of abnormal positive summating potentials on round window electrocochleography. The objectives were to establish the proportion of infants with hearing loss affected, the nature of the cochlear lesion, and its etiology. And to highlight the important implications for otoacoustic emissions testing and universal neonatal screening. Study Design: A prospectively conducted consecutive cohort study with supplemental review of notes was performed. Methods: Four hundred sixty-four children underwent round window electrocochleography and auditory brainstem response testing under general anesthesia to assess suspected hearing loss. The presence of abnormal positive potentials was recorded. Otoacoustic emissions data were collected separately and retrospectively. Results: Three hundred forty-two children had significant bilateral congenital hearing loss. All results were from hearing-impaired children. Abnormal positive potentials were recorded in 73 of 342 children (21%). Eighty-three percent of children with otoacoustic emissions also had abnormal positive potentials, but only 14% of children without otoacoustic emissions had abnormal positive potentials (P < .001). In the neonatal intensive care unit setting, 43% of infants were found to have abnormal positive potentials, whereas only 10% had abnormal positive potentials if not in the neonatal intensive care unit setting (P < .001). Abnormal positive potentials were present in 63% of infants born before 30 weeks gestation and in 14% of infants born at term (P < .001). Abnormal positive potentials were identified in 57% of infants with documented hypoxia and 11% of children with no episodes (P < .001). Otoacoustic emissions were present in 48% of infants from the neonatal intensive care unit, despite their hearing loss. Conclusion: Both otoacoustic emissions and abnormal positive potentials may originate from outer hair cell activity following inner hair cell loss. This may occur in more than 40% of hearing-impaired children in the neonatal intensive care unit setting. Chronic hypoxia is the most likely cause. Otoacoustic emissions testing may not be a suitable screening tool for such infants. 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