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  1. AU="Laufs, Sebastian"
  2. AU="McCanny, Suzette"
  3. AU="McHardy, John Alexander"
  4. AU="Erdal, Ranya"
  5. AU="Li, Long-Xia"
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  1. Article ; Online: Reply to the 'Comment on "Investigations on HONO formation from photolysis of adsorbed HNO

    Laufs, Sebastian / Kleffmann, Jörg

    Physical chemistry chemical physics : PCCP

    2018  Volume 20, Issue 48, Page(s) 30540–30541

    Abstract: In their comment to our recent paper about low HONO and NO2 formation by photolysis of adsorbed HNO3 Sullivan et al. confirmed their former results of HNO3 adsorption on silica under dry conditions using a quartz crystal microbalance. The authors ... ...

    Abstract In their comment to our recent paper about low HONO and NO2 formation by photolysis of adsorbed HNO3 Sullivan et al. confirmed their former results of HNO3 adsorption on silica under dry conditions using a quartz crystal microbalance. The authors concluded that the differences between their results and our conclusions are caused by the different experimental conditions, i.e. adsorption under very dry conditions compared to our experiments at 50% r.h. While we agree that adsorption of the highly water soluble HNO3 will strongly depend on humidity, there is still the conflict in the photolysis frequency of adsorbed HNO3 under atmospheric conditions to which the authors referred in their previous publications (see their atmospheric implication sections) and to which also our paper refers. If their results on both the adsorption cross sections of HNO3 (two to three orders of magnitude larger compared to the gas phase) and the quantum yield for NO2 formation (close to unity) are applicable under conditions prevailing in the atmosphere, then the photolytic lifetime of HNO3 on surfaces would be only ∼5 min for atmospheric solar flux (0° SZA), which is highly unlikely.
    Language English
    Publishing date 2018-11-30
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/c8cp06039h
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Investigations on HONO formation from photolysis of adsorbed HNO3 on quartz glass surfaces.

    Laufs, Sebastian / Kleffmann, Jörg

    Physical chemistry chemical physics : PCCP

    2016  Volume 18, Issue 14, Page(s) 9616–9625

    Abstract: During the last few decades, nitrous acid (HONO) has attracted significant attention as a major source of the OH radical, the detergent of the atmosphere. However, the different daytime sources identified in the laboratory are still the subject of ... ...

    Abstract During the last few decades, nitrous acid (HONO) has attracted significant attention as a major source of the OH radical, the detergent of the atmosphere. However, the different daytime sources identified in the laboratory are still the subject of controversial discussion. In the present study, one of these postulated HONO sources, the heterogeneous photolysis of nitric acid (HNO3), was studied on quartz glass surfaces in a photo flow-reactor under atmospherically relevant conditions. In contrast to other investigations, a very low HNO3 photolysis frequency for HONO formation of J(HNO3→ HONO) = 2.4 × 10(-7) s(-1) (0° SZA, 50% r.h.) was determined. If these results can be translated to atmospheric surfaces, HNO3 photolysis cannot explain the significant HONO levels in the daytime atmosphere. In addition, it is demonstrated that even the small measured yields of HONO did not result from the direct photolysis of HNO3 but rather from the consecutive heterogeneous conversion of the primary photolysis product NO2 on the humid surfaces. The secondary NO2 conversion was not photo-enhanced on pure quartz glass surfaces in good agreement with former studies. A photolysis frequency for the primary reaction product NO2 of J(HNO3→ NO2) = 1.1 × 10(-6) s(-1) has been calculated (0° SZA, 50% r.h.), which indicates that renoxification by photolysis of adsorbed HNO3 on non-reactive surfaces is also a minor process in the atmosphere.
    Language English
    Publishing date 2016-04-14
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/c6cp00436a
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Medication cost of persons with dementia in primary care in Germany.

    Michalowsky, Bernhard / Eichler, Tilly / Thyrian, Jochen René / Hertel, Johannes / Wucherer, Diana / Laufs, Sebastian / Fleßa, Steffen / Hoffmann, Wolfgang

    Journal of Alzheimer's disease : JAD

    2014  Volume 42, Issue 3, Page(s) 949–958

    Abstract: Background: Results of cost-of-illness studies in dementia have shown a considerable divergence in costs of medication for persons with dementia. However, detailed economic analyses of medication costs for community-dwelling persons with dementia are ... ...

    Abstract Background: Results of cost-of-illness studies in dementia have shown a considerable divergence in costs of medication for persons with dementia. However, detailed economic analyses of medication costs for community-dwelling persons with dementia are currently still missing, especially on the basis of primary data.
    Objective: To determine medication cost, cost per drug, and number of drugs taken of community-dwelling persons with dementia and analyze their associated factors; to estimate the current price reduction of anti-dementia drugs due to implementation of low-priced generics.
    Method: The present analysis included 205 patients screened positive for dementia. Medication data were assessed within a medication review. To estimate the cost effect of implementing generics, the most favorable equivalent generic was assigned to each anti-dementia drug. Factors associated with medication cost, cost per drug, and number of drugs taken were evaluated using multiple regression models.
    Results: Medication cost and cost per drug were higher and the number of taken drugs lower in advanced stages of cognitive impairment. Prescription of anti-dementia generics could decrease overall medication cost by 28%. Medication cost was associated with number of diagnoses, deficits in activities of daily living, and age. Dementia severity was related to cost per drug and number of drugs taken.
    Conclusion: Medication cost increases with the number of diagnoses and growing deficits in activities of daily living and decreases with age. Severely cognitively impaired persons are treated with a small number of high-priced drugs, which could suggest inadequate medication of multimorbid persons.
    MeSH term(s) Activities of Daily Living ; Aged ; Antipsychotic Agents/economics ; Antipsychotic Agents/therapeutic use ; Cross-Sectional Studies ; Dementia/drug therapy ; Dementia/economics ; Dementia/psychology ; Female ; Follow-Up Studies ; Germany ; Health Care Costs ; Humans ; Male ; Mental Status Schedule ; Neuropsychological Tests ; Primary Health Care
    Chemical Substances Antipsychotic Agents
    Language English
    Publishing date 2014
    Publishing country Netherlands
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1440127-7
    ISSN 1875-8908 ; 1387-2877
    ISSN (online) 1875-8908
    ISSN 1387-2877
    DOI 10.3233/JAD-140804
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

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    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 2021: Bestellungen von Artikeln über das Online-Bestellformular
    ab Jg. 2022: Lesesaal (EG)

    Order via subito

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  4. Book ; Online: Diurnal fluxes of HONO above a crop rotation

    Laufs, Sebastian / Cazaunau, Mathieu / Stella, Patrick / Kurtenbach, Ralf / Cellier, Pierre / Mellouki, Abdelwahid / Loubet, Benjamin / Kleffmann, Jörg

    eISSN: 1680-7324

    2016  

    Abstract: Nitrous acid (HONO) fluxes were measured above an agricultural field site near Paris during different seasons, above bare soil and different crops using the aerodynamic gradient (AG) method. Two LOPAPs (LOng Path Absorption Photometer) were used to ... ...

    Abstract Nitrous acid (HONO) fluxes were measured above an agricultural field site near Paris during different seasons, above bare soil and different crops using the aerodynamic gradient (AG) method. Two LOPAPs (LOng Path Absorption Photometer) were used to determine the HONO gradients between two heights. During daytime mainly positive HONO fluxes were observed which showed strong correlation with the product of the NO 2 concentration and the long wavelength UV light intensity, expressed by the photolysis frequency J(NO 2 ). These results indicate HONO formation by photosensitized heterogeneous conversion of NO 2 on soil surfaces as observed in recent laboratory studies. An additional influence of the soil temperature on the HONO flux can be explained by the temperature dependent HONO adsorption on the soil surface. A parameterization of the HONO flux at this location with NO 2 concentration, J(NO 2 ), soil temperature and humidity fits reasonably well all flux observations at this location.
    Subject code 630
    Language English
    Publishing date 2016-12-09
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article: Assessing chemistry schemes and constraints in air quality models used to predict ozone in London against the detailed Master Chemical Mechanism.

    Malkin, Tamsin L / Heard, Dwayne E / Hood, Christina / Stocker, Jenny / Carruthers, David / MacKenzie, Ian A / Doherty, Ruth M / Vieno, Massimo / Lee, James / Kleffmann, Jörg / Laufs, Sebastian / Whalley, Lisa K

    Faraday discussions

    2016  Volume 189, Page(s) 589–616

    Abstract: Air pollution is the environmental factor with the greatest impact on human health in Europe. Understanding the key processes driving air quality across the relevant spatial scales, especially during pollution exceedances and episodes, is essential to ... ...

    Abstract Air pollution is the environmental factor with the greatest impact on human health in Europe. Understanding the key processes driving air quality across the relevant spatial scales, especially during pollution exceedances and episodes, is essential to provide effective predictions for both policymakers and the public. It is particularly important for policy regulators to understand the drivers of local air quality that can be regulated by national policies versus the contribution from regional pollution transported from mainland Europe or elsewhere. One of the main objectives of the Coupled Urban and Regional processes: Effects on AIR quality (CUREAIR) project is to determine local and regional contributions to ozone events. A detailed zero-dimensional (0-D) box model run with the Master Chemical Mechanism (MCMv3.2) is used as the benchmark model against which the less explicit chemistry mechanisms of the Generic Reaction Set (GRS) and the Common Representative Intermediates (CRIv2-R5) schemes are evaluated. GRS and CRI are used by the Atmospheric Dispersion Modelling System (ADMS-Urban) and the regional chemistry transport model EMEP4UK, respectively. The MCM model uses a near-explicit chemical scheme for the oxidation of volatile organic compounds (VOCs) and is constrained to observations of VOCs, NOx, CO, HONO (nitrous acid), photolysis frequencies and meteorological parameters measured during the ClearfLo (Clean Air for London) campaign. The sensitivity of the less explicit chemistry schemes to different model inputs has been investigated: Constraining GRS to the total VOC observed during ClearfLo as opposed to VOC derived from ADMS-Urban dispersion calculations, including emissions and background concentrations, led to a significant increase (674% during winter) in modelled ozone. The inclusion of HONO chemistry in this mechanism, particularly during wintertime when other radical sources are limited, led to substantial increases in the ozone levels predicted (223%). When the GRS and CRIv2-R5 schemes are run with the equivalent model constraints to the MCM, they are able to reproduce the level of ozone predicted by the near-explicit MCM to within 40% and 20% respectively for the majority of the time. An exception to this trend was observed during pollution episodes experienced in the summer, when anticyclonic conditions favoured increased temperatures and elevated O3. The in situ O3 predicted by the MCM was heavily influenced by biogenic VOCs during these conditions and the low GRS [O3] : MCM [O3] ratio (and low CRIv2-R5 [O3] : MCM [O3] ratio) demonstrates that these less explicit schemes under-represent the full O3 creation potential of these VOCs. To fully assess the influence of the in situ O3 generated from local emissions versus O3 generated upwind of London and advected in, the time since emission (and, hence, how far the real atmosphere is from steady state) must be determined. From estimates of the mean transport time determined from the NOx : NOy ratio observed at North Kensington during the summer and comparison of the O3 predicted by the MCM model after this time, ∼60% of the median observed [O3] could be generated from local emissions. During the warmer conditions experienced during the easterly flows, however, the observed [O3] may be even more heavily influenced by London's emissions.
    Language English
    Publishing date 2016--18
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1359-6640
    ISSN 1359-6640
    DOI 10.1039/c5fd00218d
    Database MEDical Literature Analysis and Retrieval System OnLINE

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