| 1. |
- Schiebel, Ralf, et al.
(författare)
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Advances in planktonic foraminifer research : New perspectives for paleoceanography
- 2018
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Ingår i: Revue de Micropaleontologie. - : Elsevier BV. - 0035-1598 .- 1873-4413. ; 61:3-4, s. 113-138
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Forskningsöversikt (refereegranskat)abstract
- Planktonic foraminifer tests are major archives of environmental change and provide a multitude of proxies in paleoceanography and paleoclimatology. The application of such proxies is contingent upon a collaborative effort to better understand how the living organisms record the properties of their environment and how the resulting signals are recorded in marine sediments. In this contribution, we provide a review of the rapidly developing sub-fields of research, where new advances have been made possibleby technological developments, and by cross-disciplinary work of the scientific community. Following brief historical overviews of the sub-fields, we discuss the latest advances in planktonic foraminifer research and highlight the resulting new perspectives in ocean and climate research. Natural classification based on consistent species concepts forms the basis for analysis of any foraminifer-derived proxy. New approaches in taxonomy and phylogeny of Cenozoic planktonic foraminifers (Section 2) are presented, highlighting new perspectives on sensitivity and response of planktonic foraminifers to the changing climate and environment (Section 4). Calibration of foraminifer-specific data and environmental parameters is improving along with the technical development of probes and the access to samples from the natural environment (Section 3), enhancing our understanding of the ever-changing climate and ocean system. Comprehension of sedimentation and flux dynamics facilitates maximum gain of information from fossil assemblages (Section 5). Subtle changes in the physical (e.g., temperature), chemical (e.g., pH), and biological (e.g., food) conditions of ambient seawater affect the abundance of species and composition of assemblages as well as the chemical composition of the foraminifer shell and provide increasingly-detailed proxy data on paleoenvironments (Section 6).
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| 2. |
- Bordiga, Manuela, et al.
(författare)
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Absolute nannofossil abundance estimates : quantifying the pros and cons of different techniques
- 2015
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Ingår i: Revue de Micropaléontologie. - : Elsevier BV. - 0035-1598. ; 58:3, s. 155-165
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Tidskriftsartikel (refereegranskat)abstract
- A quick and inexpensive method to determine absolute nannofossil abundance in deep sea sediments – the “drop” technique (modified dilution method) – was compared to two other available methods – the filtration and random settling techniques. All techniques rely on the same basic principle, under which a volume of known concentration (bulk sediment weight/mL) is distributed evenly over a known total area (glass slide or filter) to then count particles within a set of (randomly) selected fields of view. The three preparation techniques were also calibrated by spiking the samples with microbeads to approach the “real values” as closely as possible. Significant offsets in abundance estimates between methods mainly reflect bias due to the uneven distribution and/or loss of particles. We show that the drop technique is most consistent and accurate in estimating “real values” and offers similar or better reproducibility than the other techniques. The drop method also allows detection of the same trends with or without calibration with microbeads. The filtration method holds the risk to drastically underestimate absolute abundances, while the settling technique is demanding in terms of time and may suffer from advection processes. The composition of nannofossil assemblages can be reliably determined by any of the three different techniques.
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| 3. |
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| 4. |
- Bergman, Susanna L., et al.
(författare)
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In-situ studies of oxidation/reduction of copper in Cu-CHA SCR catalysts: Comparison of fresh and SO2-poisoned catalysts
- 2020
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Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 269
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Tidskriftsartikel (refereegranskat)abstract
- SO2-poisoning results in deactivation of Cu-CHA SCR under standard SCR conditions; however regeneration at 700 °C completely restores the SCR performance. To understand the nature of these effects, Cu-species in the fresh and poisoned catalysts were characterized by in-situ temperature-dependent time-resolved Cu K-edge X-ray absorption spectroscopy using the multivariate curve resolution alternating least squares (MCR-ALS) approach and continuous Cauchy wavelet transforms. The extracted chemically-meaningful reference spectra of Cu-species were analyzed by DFT-assisted XANES calculations. Cu-bisulfates were found as the most energetically favorable poisoned Cu-species. The response of Cu-species to a reducing environment differs in the fresh and SO2-poisoned catalysts. Differences in reducibility are related to the formation of quasi-linear Cu-complexes in the SO2-poisoned catalyst formed during heating in H2/He. Heating in H2/He leads to partial desulfurization of the poisoned catalyst. Cooling in H2/He after heating results in more facile formation of Cu-metal clusters in fresh catalyst than in SO2-poisoned.
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| 5. |
- Hakonen, Aron, 1970, et al.
(författare)
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Explosive and chemical threat detection by surface-enhanced Raman scattering: A review
- 2015
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Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 893, s. 1-13
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Forskningsöversikt (refereegranskat)abstract
- Acts of terror and warfare threats are challenging tasks for defense agencies around the world and of growing importance to security conscious policy makers and the general public. Explosives and chemical warfare agents are two of the major concerns in this context, as illustrated by the recent Boston Marathon bombing and nerve gas attacks on civilians in the Middle East. To prevent such tragic disasters, security personnel must be able to find, identify and deactivate the threats at multiple locations and levels. This involves major technical and practical challenges, such as detection of ultra-low quantities of hazardous compounds at remote locations for anti-terror purposes and monitoring of environmental sanitation of dumped or left behind toxic substances and explosives. Surface-enhanced Raman scattering (SERS) is one of todays most interesting and rapidly developing methods for label-free ultrasensitive vibrational "fingerprinting" of a variety of molecular compounds. Performance highlights include atto-molar detection of TNT and DNT explosives, a sensitivity that few, if any, other technique can compete with. Moreover, instrumentation needed for SERS analysis are becoming progressively better, smaller and cheaper, and can today be acquired for a retail price close to 10,000 US$. This contribution aims to give a comprehensive overview of SERS as a technique for detection of explosives and chemical threats. We discuss the prospects of SERS becoming a major tool for convenient in-situ threat identification and we summarize existing SERS detection methods and substrates with particular focus on ultra-sensitive real-time detection. General concepts, detection capabilities and perspectives are discussed in order to guide potential users of the technique for homeland security and anti-warfare purposes. (C) 2015 Elsevier B.V. All rights reserved.
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| 6. |
- Persson, Daniel, 1972, et al.
(författare)
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Penetratin-induced Aggregation and Subsequent Dissociation of Negatively Charged Phospholipid Vesicles
- 2001
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Ingår i: FEBS Letters. - 1873-3468 .- 0014-5793. ; 505:2, s. 307-312
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Tidskriftsartikel (refereegranskat)abstract
- The interaction of the cellular delivery vector penetratin with a model system consisting of negatively charged phospholipid vesicles has been studied. Above a certain peptide to lipid molar ratio, the cationic oligopeptide induces vesicle aggregation. Interestingly, the aggregation is followed by spontaneous disaggregation, which may be related to membrane translocation of the peptide. Circular dichroism (CD) measurements indicate a conformational transition, from alpha -helix to antiparallel beta -pleated sheet, which is simultaneous with the aggregation process. The potential influence of spectroscopic artifacts on CD data due to the drastically increased turbidity during aggregation is discussed.
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| 7. |
- Arion, Tiberiu, et al.
(författare)
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New insight into the Auger decay process in O-2: The coincidence perspective
- 2012
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 185:8-9, s. 234-243
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Tidskriftsartikel (refereegranskat)abstract
- Photoelectron-Auger electron coincidence spectroscopy is a powerful tool for the investigation of Auger decay processes with different core-ionized intermediate states. In this paper we describe an investigation into the Auger decay of the O-2 molecule, with the purpose of bringing new insight into the dynamics of the core hole decay mechanism. Using a novel experimental approach to measuring such coincidence spectra we report the highest resolution Auger spectrum of O-2 recorded hitherto. In our approach, we have combined the advantages of these coincidence spectra with the high resolution and excellent signal-to-noise ratios of non-coincident Auger spectra and a state-of-the-art fit analysis. In this way we have derived information about the potential energy curves of the final states W-3 Delta(u), B-3 Pi(g), and B' (3)Sigma(-)(u) and concluded that the corresponding Auger transitions are formed to a large part by strongly overlapping vibrational progressions. The present findings are compared to earlier results reported in the literature confirming some theoretical predictions. (C) 2012 Elsevier B.V. All rights reserved.
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| 8. |
- Karlsson, Martin, et al.
(författare)
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Income inequality and health: Importance of a cross-country perspective
- 2010
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Ingår i: Social Science and Medicine. - : Elsevier BV. - 1873-5347 .- 0277-9536. ; 70, s. 875-885
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Tidskriftsartikel (refereegranskat)abstract
- This paper uses a unique dataset containing information collected in 2006 on individuals aged 40–79 in 21 countries throughout the world to examine whether individual income, relative income in a reference group, and income inequality are related to health status across middle/low and high-income countries. The dependent variable is self-assessed health (SAH), and as a robustness check, activities of daily living (ADL) are considered. The focus is particularly on assumptions regarding an individual’s reference group and on how the estimated relationships depend on the level of economic development. Correcting for national differences in health reporting behavior, individual absolute income is found to be positively related to individual health. Furthermore, in the high-income sample, there is strong evidence that average income within a peer-age group is negatively related to health, thus supporting the relative income hypothesis. In middle/low-income countries, it is instead average regional income that is negatively associated with health. Finally, there is evidence of a negative relationship between income inequality and individual health in high-income countries. Overall, the results suggest that there might be important differences in these relationships between high-income and middle/low-income countries.
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| 9. |
- Rahimi-Aghdam, T., et al.
(författare)
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Nitrogen and phosphorous doped graphene quantum dots : Excellent flame retardants and smoke suppressants for polyacrylonitrile nanocomposites
- 2020
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Ingår i: Journal of Hazardous Materials. - : Elsevier. - 0304-3894 .- 1873-3336. ; 381
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen (N-GQD) as well as nitrogen and phosphorous co-doped (NP-GQD) graphene quantum dots were demonstrated as novel, low cost, green and highly effective flame retardants and smoke suppressants for polyacrylonitrile (PAN) nanocomposites. The N-GQD and NP-GQD samples were synthesized by hydrothermal method with citric acid as the main reactant. For the first time, the flame retardant and smoke suppressant properties of the NP-GQD were studied. The GQDs were introduced into PAN by solvent blending route. Subsequently, thermal stability, flame retardancy, fire behavior, fire hazard and structure of the residual char were investigated by thermogravimetric analysis (TGA), UL-94 vertical burning test, cone calorimetry, FE-SEM, and Raman spectroscopy. Results showed that both PAN/N-GQD and PAN/NP-GQD nanocomposites had higher flame retardancy and smoke suppressant behavior in addition to lower fire hazard properties than neat PAN. Furthermore, the residual chars for the nanocomposite samples were increased in comparison to the neat PAN. The improvements were even more significant in case of the PAN/NP-GQD due to the synergistic effect of nitrogen and phosphorous. The improvements were mainly ascribed to the ability of the N-GQD and NP-GQD to provide stronger and larger protective char barrier layers, which was even more pronounced in case of the NP-GQD.
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| 10. |
- Rahimi-Aghdam, T., et al.
(författare)
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Polyacrylonitrile/N,P co-doped graphene quantum dots-layered double hydroxide nanocomposite : Flame retardant property, thermal stability and fire hazard
- 2019
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Ingår i: European Polymer Journal. - : Elsevier. - 0014-3057 .- 1873-1945. ; 120
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Tidskriftsartikel (refereegranskat)abstract
- ZnAl layered double hydroxide (ZnAl LDH) was synthesized via a facile hydrothermal method and then hybridized with the nitrogen and phosphorous co-doped graphene quantum dots at mild conditions. The structure and morphology of the prepared ZnAl LDH-NPGQD were characterized in detail by multiple techniques and then introduced into the polyacrylonitrile (PAN) matrix by solvent blending method. Subsequently, thermal stability, flame retardancy, fire behavior and fire hazard of the nanocomposite as well as structure of the residual char were investigated by thermogravimetric analysis (TGA), UL-94 vertical burning test, cone calorimetry and FE-SEM, respectively. The PAN/ZnAl LDH-NPGQD nanocomposite exhibited significantly higher flame retardancy and smoke suppressant capability in addition to lower fire hazard properties in comparison to the neat PAN. Moreover, incorporation of the ZnAl LDH-NPGQD into the PAN matrix increased the residual char from 0% for neat PAN to 14% for PAN/ZnAl LDH-NPGQD. These improvements were deduced to the ability of the ZnAl LDH-NPGQD to contribute in formation of stronger and larger protective char barrier layers.
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| 11. |
- Elyasi, S, et al.
(författare)
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The effect of temperature and styrene concentration on biogas production and degradation characteristics during anaerobic removal of styrene from wastewater
- 2021
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 342
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Tidskriftsartikel (refereegranskat)abstract
- In the current study, styrene was removed anaerobically from wastewaters at temperatures of 35 degrees C, 25 degrees C, and 15 degrees C and concentration range of 20-150 ppm in the presence of ethanol as a co-substrate and co-solvent. Maximum styrene removal of 93% was achieved at 35 degrees C. The volatilization of styrene was negligible at about 2% at all experimented temperatures. The average special methane yield (SMY) at 35 degrees C was 4.14- and 225-times higher than that of at T = 25 degrees C and T = 15 degrees C, respectively, but no methane was produced in the absence of ethanol. The proteins content of the soluble microbial product (SMP) and extracellular polymeric substance (EPS) was much higher than the carbohydrate content. At styrene concentration > 80 ppm, SMY, SMP, and EPS dropped sharply. The results confirmed the well performance of anaerobic microorganisms in removing styrene from wastewater and biogas production at mesophilic condition.
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