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  • 1
    Publication Date: 2015-04-12
    Description: Aim Epiphytes are a conspicuous feature of numerous forests, yet they are poorly understood compared with terrestrial plants. Theoretical frameworks have helped bridge this gap; however, important questions relating to epiphyte community development have yet to be answered. For example, at what point in tree ontogeny do epiphytes first establish? Do epiphyte communities develop uniformly, or is there variation among host trees? Methods In this study, we build upon Darwin's geological theory of island ontogeny to explore changes in epiphyte species richness throughout the life span of their respective host trees. Based on the general features of island ontogeny, we predict that there are three stages of epiphyte community development: (i) an initial stage where host trees are devoid of epiphytes because they lack sufficient architectural and physiological characteristics suitable for epiphyte establishment, (ii) a second stage where trees acquire epiphytes as adults and continue to do so into maturity, and (iii) a final stage where epiphyte communities progress through a period of species decline following host tree mortality. To test our model predictions, we censused epiphyte communities on 371 host trees from six New Zealand tree species. We first assessed the relationship between epiphyte species richness and host tree diameter. We then tested whether relationships between epiphyte species richness and host tree diameter varied between host species. Results and conclusion Results were consistent with model predictions. Our investigation found variation in the ontogenetic stage at which host trees become favourable for epiphyte establishment. Moreover, the rate at which epiphyte species richness increased with host tree diameter varied among host species. Our findings indicate that an island ontogeny framework is useful for guiding investigations on epiphyte community development. We built upon Darwin's geological theory of island ontogeny, to explore the development of epiphyte communities throughout the life span of their respective hosts. We observed variation in the ontogenetic stage that host trees become favorable for epiphytes to establish on. Additionally, epiphyte community development varied between tree species.
    Print ISSN: 1100-9233
    Electronic ISSN: 1654-1103
    Topics: Biology
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  • 2
    Publication Date: 2015-04-12
    Description: Purpose Microwave (MW) heating has been identified as a potential cost-effective technique to remediate hydrocarbon-polluted soils; however, the soil texture and properties could have a great impact on its full-scale treatment. In addition, very limited energy and economical data on MW treatment are available, and this lack makes its real application very limited. In this work, a first experimental phase was performed simulating a MW of several hydrocarbon-polluted soils. Obtained data were elaborated for a techno-economic analysis. Materials and methods Four soil textures, corresponding to medium, fine silica sand (at different soil moistures), silt as silica flour and clay as kaolin, were artificially contaminated with diesel fuel and irradiated by MWs using a bench scale apparatus. Soil samples were treated applying four specific power values at different times. At the end, soil temperature was measured, whereas residual contaminant concentrations were measured and fitted considering and exponential decay kinetic model. Temperature data, as well as kinetic parameters obtained, were used for the techno-economic analysis. The changing of the internal electric field was calculated for all the soils and operating conditions, then considering initial contamination values ranging from 750 to 5000 mg kg −1 , the minimal remediation time, specific energy and costs for the remediation were assessed. Results and discussion At low powers, MW effectiveness is limited by low soil moistures or fine soil textures due to a limitation of the electric field penetration, whereas when high powers are used soil properties have a limited effect. Remediation time, as a function of the initial contamination level, follows a linear trend, except for dry soils, for which an exponential trend was observed. For powers higher than 30 kW Kg −1 , remediation times lower than about 100 min are needed, for all the moisturized soils, in order to treat a contamination of 5000 mg kg −1 . The variation of soil moisture or soil texture results in the range 20–160 € ton −1 , and doubled costs are required for the treatment of clayey soils respect to sandy soils. Conclusions The analysis performed suggests that soil layers lower than 70 cm should be considered for ex situ remediation. MW has been shown as a quick technique also for high hydrocarbon concentrations; however, for energy saving, the application of some powers should be avoid. Unmoisturized or fine texture soil treatment results in higher costs; however, a maximum cost of 160 € ton −1 generally makes MW heating a quick and cost-effective ex situ technique.
    Print ISSN: 1439-0108
    Electronic ISSN: 1614-7480
    Topics: Geosciences
    Published by Springer
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  • 3
    Publication Date: 2015-04-12
    Description: Journal of the American Chemical Society DOI: 10.1021/jacs.5b01707
    Print ISSN: 0002-7863
    Electronic ISSN: 1520-5126
    Topics: Chemistry and Pharmacology
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  • 4
    Publication Date: 2015-04-12
    Description: Questions What were the features of the historical forest fire regime, fire intensity in particular, in Pinus sylvestris -dominated stands of Białowieża Forest? Did tree recruitment patterns relate to the fire history? Location Białowieża Forest, western Belarus and northeast Poland. Methods We used dendrochronological methods to reconstruct the fire regime in a 8.5-ha mixed coniferous ( Pinus sylvestris – Picea abies ) forest stand located in the Belarusian part of Białowieża Forest. We analysed fire frequency at stand and point scale, seasonal distribution of fires and fire intensity. We compared the results to a previous study done in a 13.0-ha site of similar habitat and stand structure, located in the Polish part of Białowieża Forest. Results We reconstructed fires back to 1655, the most recent fire dating to 1918. Mean fire interval at stand scale during 1645–2010 was 9 ± 7.8 yrs (±SD). Fire frequency gradually declined after 1811, with mean fire interval at stand scale increasing from 5 ± 2.5 yrs prior to 1811 to 18 ± 9.3 yrs thereafter. Most fires were likely of low intensity, as suggested by (1) small average tree diameter (5.1 ± 2.9 cm) at the first scar, (2) absence of strong negative growth reactions after fire, and (3) high fire frequency likely limiting fuel build-up. However, a fire in 1718 was intense and resulted in a wave of P. sylvestris regeneration. The reconstructed fire history in the Belarusian part of Białowieża Forest showed many similarities with that done in the Polish section of this forest. Similarities included dominance of low-intensity dormant and early-season fires, sporadic occurrence of high-intensity fires, high fire frequencies between the 1650s and the early 1800s, and cessation of fires since the early 20th century. Six out of 50 fire dates reconstructed in both sites were common and represented a level of synchrony that was significantly higher than expected under a random pattern of fire occurrence. Conclusions Low-intensity surface fires dominated the historical fire regime of Białowieża Forest. However, occasional high-intensity stand-replacing fires led to successional changes at the stand scale. We present dendrochronological evidence for a mixed-intensity fire regime in P. sylvestris -stands of Białowieża, a remnant of European natural old-growth lowland forests. We show that low-intensity surface fires were common but also occasionally interrupted by high-intensity stand-replacing fire events, that led to large successional changes by initiating cohort regeneration in the midst of long periods with only sporadic tree establishment.
    Print ISSN: 1100-9233
    Electronic ISSN: 1654-1103
    Topics: Biology
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  • 5
    Publication Date: 2015-04-12
    Description: Langmuir DOI: 10.1021/acs.langmuir.5b00161
    Print ISSN: 0743-7463
    Electronic ISSN: 1520-5827
    Topics: Chemistry and Pharmacology
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  • 6
    Publication Date: 2015-04-22
    Description: The Journal of Organic Chemistry DOI: 10.1021/acs.joc.5b00049
    Print ISSN: 0022-3263
    Electronic ISSN: 1520-6904
    Topics: Chemistry and Pharmacology
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  • 7
    Publication Date: 2015-04-22
    Description: The Journal of Physical Chemistry B DOI: 10.1021/acs.jpcb.5b00389
    Electronic ISSN: 1520-5207
    Topics: Chemistry and Pharmacology , Physics
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  • 8
    Publication Date: 2015-04-22
    Description: The Journal of Organic Chemistry DOI: 10.1021/jo502894r
    Print ISSN: 0022-3263
    Electronic ISSN: 1520-6904
    Topics: Chemistry and Pharmacology
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  • 9
    Publication Date: 2015-04-22
    Description: The Journal of Physical Chemistry B DOI: 10.1021/acs.jpcb.5b01051
    Electronic ISSN: 1520-5207
    Topics: Chemistry and Pharmacology , Physics
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  • 10
    Publication Date: 2015-04-22
    Description: The effect of aging time on physicochemical and catalytic properties of CuO-ZnO-Al 2 O 3 /HZSM-5 nanocatalyst for direct conversion of syngas to dimethyl ether (DME) has been investigated. Nanocatalysts were synthesized using co-precipitation method in which the aging time varied from 0 to 6 h. The physicochemical properties of the nanocatalysts were studied by X-ray diffraction, Brunauer, Emmett, and Teller, Field Emission Scanning Electron Microscopy (FESEM), energy dispersive X-ray, transmission electron microscopy, FTIR, and temperature-programmed reduction by hydrogen (TPR-H 2 ) techniques. Results showed that the crystallinity of CuO-ZnO-Al 2 O 3 has been increased significantly by increasing of aging time. FESEM analysis showed that, with extension of the aging time, the aggregation of CuO-ZnO-Al 2 O 3 over HZSM-5 has been increased. The size of the particles in the active phase was between 25.0 and 127.1 nm with an average size of 48.36 nm. TPR-H 2 profiles indicated that reducibility of nanocatalysts was enhanced with increasing of aging time. Catalytic performance was investigated at 200–300 °C, 10–40 bar, GHSV = 600 cm 3 g/h, and H 2 /CO = 2. It was found that the increase of aging time had a great influence on the activity of nanocatalysts. Moreover, the 6 h aged nanocatalyst displayed the highest catalytic activity. It was also observed that the optimum operating conditions for syngas to DME reaction were 275 °C and 40 bar.
    Electronic ISSN: 1941-7012
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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