| 1. |
- Vaughan, A., et al.
(författare)
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Regolith of the Crater Floor Units, Jezero Crater, Mars : Textures, Composition, and Implications for Provenance
- 2023
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Ingår i: Journal of Geophysical Research - Planets. - : John Wiley and Sons Inc. - 2169-9097 .- 2169-9100. ; 128:3
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Tidskriftsartikel (refereegranskat)abstract
- A multi-instrument study of the regolith of Jezero crater floor units by the Perseverance rover has identified three types of regolith: fine-grained, coarse-grained, and mixed-type. Mastcam-Z, Wide Angle Topographic Sensor for Operations and eNgineering, and SuperCam Remote Micro Imager were used to characterize the regolith texture, particle size, and roundedness where possible. Mastcam-Z multispectral and SuperCam laser-induced breakdown spectroscopy data were used to constrain the composition of the regolith types. Fine-grained regolith is found surrounding bedrock and boulders, comprising bedforms, and accumulating on top of rocks in erosional depressions. Spectral and chemical data show it is compositionally consistent with pyroxene and a ferric-oxide phase. Coarse-grained regolith consists of 1–2 mm well-sorted gray grains that are found concentrated around the base of boulders and bedrock, and armoring bedforms. Its chemistry and spectra indicate it is olivine-bearing, and its spatial distribution and roundedness indicate it has been transported, likely by saltation-induced creep. Coarse grains share similarities with the olivine grains observed in the Séítah formation bedrock, making that unit a possible source for these grains. Mixed-type regolith contains fine- and coarse-grained regolith components and larger rock fragments. The rock fragments are texturally and spectrally similar to bedrock within the Máaz and Séítah formations, indicating origins by erosion from those units, although they could also be a lag deposit from erosion of an overlying unit. The fine- and coarse-grained types are compared to their counterparts at other landing sites to inform global, regional, and local inputs to regolith formation within Jezero crater. The regolith characterization presented here informs the regolith sampling efforts underway by Perseverance. © 2023. The Authors.
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| 2. |
- Wang, J., et al.
(författare)
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Final report of the CCQM-K145 : Toxic and essential elements in bovine liver
- 2020
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Ingår i: Metrologia. - : IOP Publishing Ltd. - 0026-1394 .- 1681-7575. ; 57:1 A
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Tidskriftsartikel (refereegranskat)abstract
- Liver plays a major role in metabolism and acts as a source of energy for the body by storing glycogen. With the growing interest and investigation in the biological effects in recent years, it is important and necessary to develop accurate and comparable analytical methods for elements in bio-samples. It has, however, been 10 years since the tissue sample (bovine liver) of CCQM-K49 key comparison. The purpose of CCQM-K145 is to ensure the comparable and traceable measurement results for essential and toxic elements such as P, S, Zn, Mn, Ni, Mo, Sr, Cr, Co, Pb, As and Hg in bovine liver among NMIs and other designated measurement bodies worldwide. The comparison was agreed by IAWG as 6th IAWG Benchmarking Exercise with Zn and Ni as exemplary elements at the meeting in Korea in the early October 2016. The results of CCQM-K145 are expected to cover the measurement capability and support CMCs claiming for inorganic elements in the similar biological tissue materials and food samples. 30 NMIs and DIs registered in CCQM-K145. With respect to the methodology, a variety of techniques such as IDMS, ICP-OES, ICP-MS(non-ID), AAS and NAA were adopted by the participants. For Zn, Ni, Sr, Pb and Hg measurements, most participants chose ID-ICP-MS method, which showed the better performance in terms of consistency and reliability of the measurement results. In aspect of the traceability for the measurement results in CCQM-K145, most participants used their own (in house) CRMs or other NMI's CRMs to guarantee trace to SI unit. Most participants used similar matrix CRMs for quality control or method validation. Base on different statistic way to calculate the reference mass fraction values and associated uncertainties for each measurand, removal of the suspected extreme values, and discussion at the IAWG meetings, the median values are proposed as the KCRV for Zn, Ni, Mn, Mo, Cr, Pb and Hg; the arithmetic mean values are proposed as the KCRV for P, S, Sr, Co and As. In general, the performances of the majority of CCQM-K145 participants are very good, illustrating their measurement capabilities for Zn, Ni, P, S, Mn, Mo, Sr, Cr, As, Co, Pb and Hg in a complex biological tissue matrix. Bovine liver contains many kinds of nutrients and microelements, it can be regarded as a typical representative material of biological tissue and food. In CCQM-K145, the analytes involved alkali metals and transition elements, metalloids/semi-metals and non metals with a range of mass fraction from mg/g to μg/kg. CCQM-K145 also tested the ability of NMIs/DIs to determine elements that were easy to be lost and polluted, and interfered significantly. The chemical pretreatment methods of samples used in the comparison is suitable for general food and biological matrix samples. A variety of measurement methods used in the comparison represent the main instrumental technology for elemental analysis. Therefore, for supporting CMC claim, CCQM-K145 is readily applicable to measurement of more elements in a wide range of biological materials (including liquids and solids) and meat products. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
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| 3. |
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| 4. |
- Krick, B. A., et al.
(författare)
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Ultralow wear fluoropolymer composites : Nanoscale functionality from microscale fillers
- 2016
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Ingår i: Tribology International. - : Elsevier Ltd. - 0301-679X .- 1879-2464. ; 95, s. 245-255
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Tidskriftsartikel (refereegranskat)abstract
- Polytetrafluoroethylene (PTFE) filled with certain alumina additives has wear rates over four orders of magnitude lower than unfilled PTFE. The mechanisms for this wear reduction have remained a mystery. In this work, we use a combination of techniques to show that porous, nanostructured alumina microfillers (not nanofillers) are critical for this wear reduction. The microscale alumina particles break during sliding into nanoscale fragments. X-ray microtomography, transmission electron microscopy and infrared spectroscopy reveal nanoscale alumina fragments accumulated in the tribofilms. Tribochemically generated carboxylate endgroups bond to metal species in the transfer film and to alumina fragments in the surface of the polymer composite. These mechanically reinforced tribofilms create robust sliding surfaces and lead to a dramatic reduction in wear. © 2015 The Authors.
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| 6. |
- Regmi, P., et al.
(författare)
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The future of WRRF modelling - Outlook and challenges
- 2019
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 79:1, s. 3-14
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Tidskriftsartikel (refereegranskat)abstract
- The wastewater industry is currently facing dramatic changes, shifting away from energy-intensive wastewater treatment towards low-energy, sustainable technologies capable of achieving energy positive operation and resource recovery. The latter will shift the focus of the wastewater industry to how one could manage and extract resources from the wastewater, as opposed to the conventional paradigm of treatment. Debatable questions arise: Can the more complex models be calibrated, or will additional unknowns be introduced? After almost 30 years using well-known International Water Association (IWA) models, should the community move to other components, processes, or model structures like 'black box' models, computational fluid dynamics techniques, etc.? Can new data sources - e.g. on-line sensor data, chemical and molecular analyses, new analytical techniques, off-gas analysis - keep up with the increasing process complexity? Are different methods for data management, data reconciliation, and fault detection mature enough for coping with such a large amount of information? Are the available calibration techniques able to cope with such complex models? This paper describes the thoughts and opinions collected during the closing session of the 6th IWA/WEF Water Resource Recovery Modelling Seminar 2018. It presents a concerted and collective effort by individuals from many different sectors of the wastewater industry to offer past and present insights, as well as an outlook into the future of wastewater modelling.
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| 7. |
- Ringsberg, JW, et al.
(författare)
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Reduction in ultimate strength capacity of corroded ships involved in collision accidents
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- There are many studies in the literature which present advanced numerical simulations of the assessment of the crashworthiness of marine structures. Most of these studies have not considered the effect of corrosion as an impairment of the struck structure’s resistance to the collision load and the consequence on the ship’s ultimate strength. The objective of the current investigation is to study the effects of sudden damage (ship-ship collision), and progressive deterioration due to corrosion, on the ultimate strength of a ship which has been collided by another vessel. Explicit finite element analyses of collision scenarios are presented where several factors are varied systematically in a parametric study, e.g. the vessels involved in the collision, and consideration of corroded ship structure elements and their material characteristics in the model. The striking ship is represented by a coastal tanker while the struck ship is either a RoPax ship, or, a coastal oil tanker vessel. The crashworthiness of the struck vessels is quantified in terms of the shape and size of the damage opening in the side-shell structure, and the division of energy absorption between the striking and struck ships for the different collision simulations. The ultimate strength of the struck vessel, for each collision simulation, is calculated using the Smith method and the shape and size of the damage openings from the finite element analyses. In conclusion, the study contributes to understanding of how corroded, collision-damaged ship structures suffer significantly from a reduction in crashworthiness and ultimate strength, how this should be considered and modelled using the finite element method and analysed further using the Smith method
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| 8. |
- Sundberg, Peter, et al.
(författare)
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Novel thermo-chemical strengthening of glass for solar energy applications and its impact on the physical properties
- 2017
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Konferensbidrag (refereegranskat)abstract
- The LIMES project (Light Innovative Materials for Enhanced Solar Efficiency), a Solar-ERA.NET project, have been a fruitful collaboration project to optimize many different properties in state-of-the-art solar glasses for photovoltaic (PV) modules. Here, we present results related to the effectiveness of reactive gas strengthening and its improvement of the physical properties of thin glasses. Novel thermo-chemical strengthening has been created using reactive chemicals that react with the glass surface during the thermal strengthening process. The glass surface gets a markedly increase of Al2O3, which in previous studies has been shown to have a beneficial effect on the mechanical properties. Successful thermo-chemical strengthening of 4 and 2 mm glasses to a similar strengthening level have repeatedly been performed, polariscope images in Figure 1. The strengthening level has been quantified using SCALP (Scattered Light Polariscope) and were found to be in the range of 85-110 MPa of compressive stresses in the surface which are comparable to values for conventional thermally strengthened glass.The strength of the glasses was quantified using the ring-on-ring method and the surface mechanical properties were evaluated by means of nano/microindentation. UV-Vis spectroscopy measurements have also been performed.Results for the ring-on-ring tests show that the 2 mm thin glass were positively affected by the while 4 mm did not show any significant change as compared to thermally strengthened. The thermo-chemically strengthened glasses have a significantly higher crack resistance than both the reference float glass and the traditionally thermally strengthened glass. The hardness results show that for low loads, ≥1 mN, the hardness follow the order thermo-chemically strengthened glass > thermally strengthened glass > annealed float glass. The scratch resistance for thermo-chemically strengthened glass is increased as compared to ordinary float glass. In addition, the transmission is not markedly reduced.
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| 9. |
- Tyrode, Eric, et al.
(författare)
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A study of the adsorption of ammonium perfluorononanoate at the air-liquid interface by vibrational sum-frequency spectroscopy
- 2007
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 111:1, s. 316-329
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Tidskriftsartikel (refereegranskat)abstract
- Vibrational sum frequency spectroscopy (VSFS) has been used to study the adsorption of ammonium perfluorononanoate (APFN) at the air-liquid interface, specifically targeting the C-F and carboxylate stretches. In the spectral region extending from 1050 to 1850 cm(-1), three major peaks situated at 1369, 1408, and similar to 1665 cm(-1) were detected under the polarization combinations ssp, ppp, and sps. The first of these peaks was assigned to CF3 stretching vibrations after a detailed comparison with other surfactant molecules with different degrees of fluorination, while the last two resonant features were assigned to symmetric and antisymmetric carboxylate stretching vibrations. From the combined analysis of the VSFS, ellipsometry, and previous FTIR measurements, a consistent physical model for the adsorption of APFN to the liquid surface is proposed. At low surface coverages the APFN molecules lie essentially flat on the surface. At concentrations from 1 mM to the critical micellar concentration (molecular areas < 70 angstrom(2)) the mean orientation of both the surfactant head group and terminal CF3 group remained constant. The formation of surface micelles at higher concentrations is consistent with the experimental data.
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