23 research outputs found
VIBRATIONAL SPECTROSCOPY OF PHOTOREACTIVE MOLECULES IN ATMOSPHERIC CHEMISTRY
No full textAuthor Institution: Department of chemistry and Biochemistry, University of Colorado, Boulder, CO 80309Vibrational overtone spectra of oxidized atmospheric chromophores are presented and analyzed to energies where chemistry through vibrational overtone pumping is possible. Experimental near infrared and visible spectra complemented by dynamical theory are presented to elucidate the light initiated reaction dynamics of pyruvic and of glyoxilic acid photo-decarboxylation. The role of water is investigated by making use of vibrational spectra of hydrates of the title compounds. Consequences of water and sunlight mediated chemistry to formation of secondary organic aerosol in the atmosphere will be discussed.\\ \\ \noindent K. L. Plath, J. L. Axson, G. C. Nelson, K. Takahashi, R. T. Skodje and V. Vaida {em React. Kineti. Catal. Lett.} \textbf{96}, 209 (2009)\\ V. Vaida {\em J. Phys. Chem. A} \textbf{113}, 5 (2009)\\ K. Takahashi, K. L. Plath, R. T. Skodje and V. Vaida {\em J. Phys. Chem A} \textbf{112} 7321 (2008
Examining Interdisciplinary Sustainability Institutes at Major Research Universities: Innovations in Cross-Campus and Cross-Disciplinary Models.
No full textThis is a study of the distinctive characteristics, activities, challenges and opportunities of a specific type of sustainability institute, one that spans the many disciplines of the University and, to do so, reports to upper administration (Provost or Vice President.) Among research universities within the Association of American Universities (AAU), 19 are identified and 18 agreed to participate in this study. Directors were sent a 71-question survey in January 2017 that covered issues of Governance, Research, Education, Engagement, Campus Operations and Best Practiceshttps://deepblue.lib.umich.edu/bitstream/2027.42/136638/1/1366_Hoffman.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136638/4/1366_Hoffman_June2017.pdfDescription of 1366_Hoffman_June2017.pdf : June 2017 revisio
Detection of Active Microbial Enzymes in Nascent Sea Spray Aerosol: Implications for Atmospheric Chemistry and Climate
No full textThe oceans cover nearly three-quarters
of the Earth’s surface
and produce vast quantities of sea spray aerosols (SSA). Studies have
shown that due to ocean biology SSA particles are comprised of much
more than just sea salt and often include proteins, lipids, sugars,
viruses, and bacteria. In this study, we show for the first time that
a diverse array of microbial enzymes (protease, lipases, and alkaline
phosphatase) are transferred from the ocean into the atmosphere and
often become even more active with measured activities in SSA particles
that are 1–2 orders of magnitude higher than those in bulk
seawater. We hypothesize that these enzymatic reactions are enhanced
in the interfacial environment of droplets and aerosols that can dynamically
modify surface chemical species and properties. Simulations reveal
that enzyme-containing SSA particles can rapidly coagulate with other
preexisting aerosols, thus transferring the impact of enzyme reactions
to a broad range of marine aerosols. These biotic reaction pathways
are expected to profoundly change the composition of marine aerosols,
particularly at the interface, and thus will impact cloud properties
in marine environments. Future studies are needed to determine how
photochemistry, changing ocean conditions in a warming climate, and
other external factors will influence the activities of these enzymes
and their impact on the composition of the marine atmosphere
Relationship Between Epoxy Resin Properties and Weepage of Glass-Reinforced Filament-Wound Pipes
No full textInternational audienceThis study aims to understand the relationship between mechanical properties of a resin and weepage (loss of water tightness) of glass-reinforced filament-wound pipes. A three-stage study has been carried out, from epoxy resin chemistry to mechanical behaviour of composite pipes under pressure. Four resin formulations were selected by accounting for their different mechanical characteristics in tension. The study of unidirectional composite plaques showed that fracture in tension transversally to the fibre direction essentially comes from the failure of the fibre/matrix interface. The failure strain of these plaques is higher when the strain of the resin at failure of the fibre/matrix interface is higher. Biaxial pressure tests on ± 55°-filament-wound pipes revealed that weepage is due to the transversal failure of unidirectional layers of the pipe wall. Moreover, a very simple weepage criterion was proposed: weepage appears for a pressure directly proportional to the failure strain of unidirectional composite plaques in tension transversally to the fibre direction. The proportionality constant depends on the pipe geometry
Lake spray aerosol generation: a method for producing representative particles from freshwater wave breaking
No full textWave-breaking action in bodies of freshwater produces atmospheric aerosols
via a similar mechanism to sea spray aerosol (SSA) from seawater. The term
lake spray aerosol (LSA) is proposed to describe particles formed by this
mechanism, which have been observed over the Laurentian Great Lakes. Though
LSA has been identified from size distribution measurements during a single
measurement campaign, no measurements of LSA composition or relationship to
bubble-bursting dynamics have been conducted. An LSA generator utilizing a
plunging jet, similar to many SSA generators, was constructed for the
generation of aerosol from freshwater samples and model salt solutions. To
evaluate this new generator, bubble and aerosol number size distributions
were measured for salt solutions representative of freshwater (CaCO3)
and seawater (NaCl) at concentrations ranging from that of freshwater to
seawater (0.05–35 g kg−1), synthetic seawater (inorganic), synthetic
freshwater (inorganic), and a freshwater sample from Lake Michigan.
Following validation of the bubble and aerosol size distributions using
synthetic seawater, a range of salt concentrations were investigated. The
systematic studies of the model salts, synthetic freshwater, and Lake
Michigan sample indicate that LSA is characterized by a larger number size
distribution mode diameter of 300 nm (lognormal), compared to seawater at
110 nm. Decreasing salt concentrations from seawater to freshwater led to
greater bubble coalescence and formation of larger bubbles, which generated
larger particles and lower aerosol number concentrations. This resulted in a
bimodal number size distribution with a primary mode (180 ± 20 nm)
larger than that of SSA, as well as a secondary mode (46 ± 6 nm) smaller than
that of SSA. This new method for studying LSA under isolated conditions is
needed as models, at present, utilize SSA parameterizations for freshwater
systems, which do not accurately predict the different size distributions
observed for LSA or resulting climate properties. Given the abundance of
freshwater globally, this potentially important source of aerosol needs to
be thoroughly characterized, as the sizes produced are relevant to light
scattering, cloud condensation nuclei (CCN), and ice nuclei (IN)
concentrations over bodies of freshwater
Absolute ozone absorption cross section in the Huggins Chappuis minimum (350–470 nm) at 296 K
No full textAbstract. We report the ozone absolute absorption cross section between 350–470 nm, the minimum between the Huggins and Chappuis bands, where the ozone cross section is less than 10−22 cm2. Ozone spectra were acquired using an incoherent broadband cavity enhanced absorption spectrometer, with three channels centered at 365, 405, and 455 nm. The accuracy of the measured cross section is 2 %. Previous measurements vary by more than an order of magnitude in this spectral region. The measurements reported here provide much greater spectral coverage than the most recent measurements. We report a minimum absorption cross section of 3.4×10−24 cm2 at 381.8 nm, which is 22 % lower than the previously reported value. The effect of O3 concentration and water vapor partial pressure were investigated, however there were no observable changes in the absorption spectrum most likely due to the low optical density of the complex.
</jats:p
Absolute ozone absorption cross section in the Huggins Chappuis minimum (350–470 nm) at 296 K
No full textAbstract. We report the ozone absolute absorption cross section between 350–470 nm, the minimum between the Huggins and Chappuis bands, where the ozone cross section is less than 10−22 cm2. Ozone spectra were acquired using an incoherent broadband cavity enhanced absorption spectrometer, with three channels centered at 365, 405, and 455 nm. The accuracy of the measured cross section is 4–30%, with the greatest uncertainty near the minimum absorption at 375–390 nm. Previous measurements vary by more than an order of magnitude in this spectral region. The measurements reported here provide much greater spectral coverage than the most recent measurements. The effect of O3 concentration and water vapor partial pressure were investigated, however there were no observable changes in the absorption spectrum most likely due to the low optical density of the complex.
</jats:p
Consultative selling in financial services: An observational study of the mortgage mediation process.
No full textRecommended from our members
Factors controlling the transfer of biogenic organic species from seawater to sea spray aerosol
No full textOcean waves transfer sea spray aerosol (SSA) to the atmosphere, and these SSA particles can be enriched in organic matter relative to salts compared to seawater ratios. A fundamental understanding of the factors controlling the transfer of biogenic organic matter from the ocean to the atmosphere remains elusive. Field studies that focus on understanding the connection between organic species in seawater and SSA are complicated by the numerous processes and sources affecting the composition of aerosols in the marine environment. Here, an isolated ocean-atmosphere system enables direct measurements of the sea-air transfer of different classes of biogenic organic matter over the course of two phytoplankton blooms. By measuring excitation-emission matrices of bulk seawater, the sea surface microlayer, and SSA, we investigate time series of the transfer of fluorescent species including chlorophyll-a, protein-like substances, and humic-like substances. Herein, we show the emergence of different molecular classes in SSA at specific times over the course of a phytoplankton bloom, suggesting that SSA chemical composition changes over time in response to changing ocean biological conditions. We compare the temporal behaviors for the transfer of each component, and discuss the factors contributing to differences in transfer between phases
Delineamento de um sistema de informações gerenciais para cooperativas que atuam no segmento de planos de saúde baseado na metodologia Balanced Scorecard
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia de Produção.O presente trabalho propõe o delineamento de um sistema de informações gerenciais para a avaliação de desempenho de cooperativas que atuam na área de planos de saúde, baseando-se na metodologia BALANCED SCORECARD e utilizando como modelo hipotético indicadores para a Unidade de negócios Unimed na região de Santa Catarina. São descritos os principais conceitos relacionados com o assunto, mais especificamente, a abordagem do trabalho se dá demonstrando as necessidades relacionadas com sistemas de informação/inteligência competitiva, à metodologia Balanced Scorecard e à apresentação das principais características das cooperativas que atuam na área de planos de saúde. O assunto principal se refere à apresentação da definição de um modelo de sistema de informação que permite a avaliação de desempenho para as cooperativas de saúde, baseado nos indicadores criados, usando a metodologia Balanced Scorecard. Os indicadores criados para o desempenho proposto da atividade abrangem os de aprendizado e crescimento, os financeiros, os de clientes, os de processos e o de responsabilidade social, este último criado especificamente para atender à característica das cooperativas de saúde. O diferencial deste modelo consiste em ter como base a metodologia Balanced Scorecard, utilizando indicadores tradicionais, ou seja, financeiros e não financeiros que tratam dos processos, relacionamento dos clientes e inovação, fortalecendo, dessa forma, a comunicação da estratégia da empresa em todos os níveis da organização e facilitando uma análise de desempenho global assim como revisão das estratégias e plano de ação com o comprometimento de todos os colaboradores
