| 1. |
- Fages, A., et al.
(författare)
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Tracking Five Millennia of Horse Management with Extensive Ancient Genome Time Series
- 2019
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Ingår i: Cell. - : Elsevier BV. - 0092-8674. ; 177:6
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Tidskriftsartikel (refereegranskat)abstract
- Horse domestication revolutionized warfare and accelerated travel, trade, and the geographic expansion of languages. Here, we present the largest DNA time series for a non-human organism to date, including genome-scale data from 149 ancient animals and 129 ancient genomes (>= 1-fold coverage), 87 of which are new. This extensive dataset allows us to assess the modem legacy of past equestrian civilisations. We find that two extinct horse lineages existed during early domestication, one at the far western (Iberia) and the other at the far eastern range (Siberia) of Eurasia. None of these contributed significantly to modern diversity. We show that the influence of Persian-related horse lineages increased following the Islamic conquests in Europe and Asia. Multiple alleles associated with elite-racing, including at the MSTN "speed gene," only rose in popularity within the last millennium. Finally, the development of modem breeding impacted genetic diversity more dramatically than the previous millennia of human management.
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| 2. |
- Feng, S., et al.
(författare)
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Modeling of micron-sized aluminum particle combustion in hot gas flow
- 2024
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Ingår i: Fuel. - 0016-2361. ; 369
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a model for micron-sized aluminum (Al) particle combustion in hot oxidizing environments, forming hollow spheres. The model comprises four sub-models describing the physical and chemical processes during Al combustion: melting of the solid core, ejection of liquid Al droplets from the breaking solid shell, vaporization of liquid droplets, and ignition and establishment of vapor flame surrounding the solid particles. The model is of critical importance when the ambient gas temperature is higher than the melting point of the Al core, Tc,m, but lower than the alumina (Al2O3) shell's melting point, Ts,m. In the model, the Al core is assumed to be surrounded by a thin, compact alumina shell that blocks the diffusion of oxidizer into the core and prevents surface reactions. The alumina shell's cracking and liquid Al's eruption are triggered by thermal expansion and pressure buildup in the liquid core. The splashed liquid Al droplets vaporize quickly and initiate gas-phase reactions, followed by the vaporization of the liquid Al core as the particle temperature Tp increases. Al vapor combustion heat is redistributed to simulate the gaseous flame near the particle. The model is implemented using the Lagrangian particle tracking method and is validated through simulations of micron-sized Al particle combustion in hot gas and comparison with experiments. The results can explain the formation of the sharp-edged holes on hollow aluminum oxide spheres and the ignition behavior observed in the experiments.
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| 3. |
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| 4. |
- Augusto Berrocal, Jose, et al.
(författare)
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Consequences of conformational flexibility in hydrogen-bond-driven self-assembly processes
- 2016
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Ingår i: Chemical Communications. - : ROYAL SOC CHEMISTRY. - 1359-7345 .- 1364-548X. ; 52:72, s. 10870-10873
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Tidskriftsartikel (refereegranskat)abstract
- We report the synthesis and self-assembly of chiral, conformationally flexible C-3-symmetrical trisamides. A strong Cotton effect is observed for the supramolecular polymers in linear alkanes but not in cyclic alkanes. MD simulations suggest 2:1 conformations of the amides within the aggregates in both types of solvents, but a chiral bias in only linear alkanes.
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| 5. |
- Berrocal, E., et al.
(författare)
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Image transfer through the complex scattering turbid media
- 2006
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Ingår i: Laser Physics Letters. - : IOP Publishing. - 1612-2011 .- 1612-202X. ; 3:9, s. 464-467
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Tidskriftsartikel (refereegranskat)abstract
- Seeing through a turbid medium such as fog, mist or clouds is a fascinating idea that would find applications in a large range of fields from research to industry. The main difficulty of this challenging task is related to the complexity of the multiple of optical radiation propagated through an emsemble of scattering particles and/or droplets randomly distributed in a medium. To deal with this challenging problem to deal with a new Monte Carlo based method computational technique able to simulate image transfer through the complex inhomogenous turbid media. The model is able to identify the contribution of the scattering orders in the detected images for a particular medium. With the presented approach the simulation of laser propagation and image transfer of an object hidden within a turbid scattering medium has been performed. The results of simulation demonstrate a good agreement with the experimental results. The validation of the technique has been one by using several modeling samples of water polystyrenes spheres solutions.
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| 6. |
- Berrocal, E., et al.
(författare)
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Imaging atomizing sprays with high visibility using two-photon fluorescence laser sheet imaging
- 2020
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Ingår i: ICLASS 2018 - 14th International Conference on Liquid Atomization and Spray Systems.
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Konferensbidrag (refereegranskat)abstract
- Two-photon excitation laser induced fluorescence (2p-LIF) is used here for imaging through an optically dense spray system. The main advantage of the approach is that a low level of unwanted fluorescence signal originating from multiple-light scattering is generated. This leads to high visibility and image contrast even through scattering media, thus providing faithful descriptions of the imaged fluid structures. While 2p-LIF imaging is a well-known point measurement approach in the field of life science microscopy [1], it has, to the best of the authors' knowledge, never been tested for observing atomizing sprays. We take advantage of this process here, at a macroscopic scale, by imaging a light sheet of ~1cm height. To generate enough 2p-LIF signal at such large scale and for single-shot detection, ultra-short laser pulses of high pulse energy are needed. This is obtained by using a laser system providing 25 fs pulses centered at 800 nm wavelength and having 2.5 mJ pulse energy. The technique is demonstrated by imaging a single spray plume from a 6 hole commercial Gasoline Direct Injection (GDI) system running at 200 bar injection pressure. The injected liquid is water mixed with Fluorescein dye. We show the important image contrast improvement of 2p-LIF light sheet imaging in comparison with the traditional shadowgraphy, laser sheet Mie scattering and back-fluorescence imaging. The proposed approach is very promising as a future imaging tool for detailed analysis of the dynamics of atomizing spray in the spray formation region.
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| 7. |
- Chen, Teresa E, 1988, et al.
(författare)
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Assessment of the mechanical behaviour of reinforcement bars with localised pitting corrosion by Digital Image Correlation
- 2020
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Ingår i: Engineering Structures. - : Elsevier BV. - 1873-7323 .- 0141-0296. ; 219
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Tidskriftsartikel (refereegranskat)abstract
- Corrosion of reinforcement in concrete impairs the mechanical behaviour of rebars by decreasing their strength and deformation capacity. In this study, uniaxial tensile tests were carried out on 61 rebars taken from 22 pre- and un- cracked reinforced concrete beams subjected to drying and wetting cycles in chloride solution for over three years. A 3D-scanning technique was used to characterise the maximum local corrosion level, μmax, and different pit shape parameters. Digital Image Correlation (DIC) was used to capture the displacement field of the test bars; the engineering strain was measured through the virtual extensometers created in the DIC post-processing software. The proof and ultimate forces showed linear decreasing trends of μmax, while the proof and ultimate strengths (based on the minimum residual cross-sectional area) were not obviously affected by corrosion. The ultimate strain of corroded bars depended on the gauge length due to strain localisation in the pit. Thus, it was emphasised that the ultimate strain may be overestimated if measured based on a short gauge across the pit. It was also observed that when μmax exceeded a critical local corrosion level (μcrit depending on the ratio between the yield and ultimate strengths of the steel), the region outside the pit did not develop yielding. A lower bound of ultimate strain was further derived as a function of the mechanical parameters of uncorroded steel and maximum local corrosion level. This provided a good comparison with the experimental results. Ultimately, a hypothesis for time-dependent assessment of strain capacity is proposed, considering the evolution of corrosion morphology over time.
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| 8. |
- Chen, Teresa E, 1988, et al.
(författare)
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Comparison of the service life, life-cycle costs and assessment of hybrid and traditional reinforced concrete through a case study of bridge edge beams in Sweden
- 2023
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Ingår i: Structure and Infrastructure Engineering. - : Informa UK Limited. - 1573-2479 .- 1744-8980. ; 19:1, s. 39-57
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Tidskriftsartikel (refereegranskat)abstract
- The edge beams of reinforced concrete bridges with de-icing salts sprayed experience extensive corrosion damage. The average service life of edge beams needing replacement in Sweden has been reported as only 45 years, causing great economic loss to both owners and users. Hence, finding a durable solution for edge beams would benefit society. Hybrid reinforced concrete structures, produced by adding a low-to-moderate fibre content into traditional reinforced concrete, can effectively limit the service crack width and improve resistance to chloride-induced corrosion damage. In this paper, different alternatives of hybrid and traditional reinforced edge beams were designed for a case study. The service life of the alternatives was compared by conducting chloride diffusion calculations and by applying a corrosion-induced cracking model. The economic and environmental (indicated by greenhouse gas emissions) benefits of using hybrid reinforced edge beams were assessed by life-cycle cost analysis and life-cycle assessment. The results showed that the service life of edge beams made of hybrid reinforced concrete can be prolonged by over 58%, thereby enabling a significant reduction in the total life-cycle costs and annual total greenhouse gas emissions.
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| 9. |
- Chen, Teresa E, 1988, et al.
(författare)
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Correlation between concrete cracks and corrosion characteristics of steel reinforcement in pre-cracked plain and fibre-reinforced concrete beams
- 2020
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Ingår i: Materials and Structures/Materiaux et Constructions. - : Springer Science and Business Media LLC. - 1359-5997. ; 53:2
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents results on corrosion characteristics of 66 rebars extracted from un- and pre-cracked plain concrete and fibre-reinforced concrete (FRC) beams suffering from corrosion for more than 3 years. The influences of fibre reinforcement, flexural cracks, corrosion-induced cracks and loading condition on the maximum local corrosion level (defined as the maximum cross-sectional area loss percentage) and pit morphology were examined. With 3D-scanning, the corrosion characteristics were analysed, and pit types were classified based on the maximum local corrosion level and geometric parameters of pits. Corrosion pits were observed near some flexural cracks, while the bars at other cracks were free from corrosion. Most rebars in FRC had less maximum local corrosion level than those in plain concrete under the same loading condition and maximum flexural crack width. However, the maximum local corrosion level was not dependent on the maximum flexural crack width (0.1 and 0.4 mm). Longitudinal cracks (corrosion-induced cracks) aggravated the total steel loss and changed the pit morphology by promoting the pit length development. However, longitudinal cracks did not always form, even with severe pitting corrosion. A hypothesis about the time-dependent interplay between transverse and longitudinal cracks and corrosion development was proposed. Further studies on predicting the pitting corrosion evolution and experimental work on specimens exposed for longer periods are needed to understand and quantify the long-term durability of concrete structures reinforced with both conventional reinforcing bars and fibres.
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| 10. |
- Chen, Teresa E, 1988, et al.
(författare)
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Corrosion Pattern and Mechanical Behaviour of Corroded Rebars in Cracked Plain and Fibre Reinforced Concrete
- 2021
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Ingår i: RILEM Bookseries. - Cham : Springer International Publishing. - 2211-0844 .- 2211-0852. ; 30, s. 477-488
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Konferensbidrag (refereegranskat)abstract
- This paper presents experimental results of corrosion pattern and tensile behaviour of corroded rebars extracted from 4 uncracked and 18 pre-cracked plain concrete and fibre reinforced concrete (FRC) beams. The beams were pre-cracked through three-point bending to a target maximum crack width of 0.1 and 0.4 mm, and then subjected to natural corrosion through cyclic exposure to a 16.5% NaCl solution for more than three years. 3D-scanning was used to characterise the pit morphology and evaluate the maximum local corrosion level of extracted rebars. Under the same loading condition and crack width, most rebars in FRC had smaller maximum local corrosion level than those in plain concrete. Subsequently, tensile tests were carried out on the extracted rebars, with Digital Image Correlation (DIC) technique adopted to investigate the influence of pit morphology on the local strain development. Finally, the time-dependent influence of transverse and longitudinal cracks on the pit morphology which governs the ultimate strain of corroded rebars was discussed. The time-varying nature of corrosion morphology should be considered when predicting the durability and long-term safety of conventional reinforced concrete and FRC structures with reinforcing bars under chloride environments.
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| 11. |
- Chen, Teresa E, 1988, et al.
(författare)
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Hybridarmerade konstruktioner i kloridhaltiga miljöer – beständighet, säkerhet och livscykelkostnader
- 2020
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Ingår i: Bygg och teknik. - 0281-658X. ; 2020:6, s. 14-19
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Livslängden för armerade betongkonstruktioner i kloridhaltiga miljöer kan förlängas genom att kombinera traditionell armering med fibrer i så kallade hybridarmerade lösningar. Detta visades experimentellt i ett tidigare doktorandprojekt i samarbete mellan Chalmers tekniska högskola och Thomas Concrete Group. I ett efterföljande postdocprojekt har vi nu utvecklat modeller som kvantitativt utvärderar fibrernas effekt på beständighet och säkerhet – därigenom visas de positiva resultaten i praktisk användning. Vi har också genomfört en fallstudie som visar de ekonomiska och miljömässiga fördelarna med att använda hybridarmerad betong i kantbalkar.
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| 12. |
- Chiang, Michael F., et al.
(författare)
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International Classification of Retinopathy of Prematurity, Third Edition
- 2021
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Ingår i: Ophthalmology. - : Elsevier. - 0161-6420 .- 1549-4713. ; 128:10, s. 51-68
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The International Classification of Retinopathy of Prematurity is a consensus statement that creates a standard nomenclature for classification of retinopathy of prematurity (ROP). It was initially published in 1984, expanded in 1987, and revisited in 2005. This article presents a third revision, the International Classification of Retinopathy of Prematurity, Third Edition (ICROP3), which is now required because of challenges such as: (1) concerns about subjectivity in critical elements of disease classification; (2) innovations in ophthalmic imaging; (3) novel pharmacologic therapies (e.g., antievascular endothelial growth factor agents) with unique regression and reactivation features after treatment compared with ablative therapies; and (4) recognition that patterns of ROP in some regions of the world do not fit neatly into the current classification system.Design: Review of evidence-based literature, along with expert consensus opinion. Participants: International ROP expert committee assembled in March 2019 representing 17 countries and comprising 14 pediatric ophthalmologists and 20 retinal specialists, as well as 12 women and 22 men.Methods: The committee was initially divided into 3 subcommittees-acute phase, regression or reactivation, and imaging-each of which used iterative videoconferences and an online message board to identify key challenges and approaches. Subsequently, the entire committee used iterative videoconferences, 2 in-person multiday meetings, and an online message board to develop consensus on classification.Main Outcome Measures: Consensus statement.Results: The ICROP3 retains current definitions such as zone (location of disease), stage (appearance of disease at the avascular-vascular junction), and circumferential extent of disease. Major updates in the ICROP3 include refined classification metrics (e.g., posterior zone II, notch, subcategorization of stage 5, and recognition that a continuous spectrum of vascular abnormality exists from normal to plus disease). Updates also include the definition of aggressive ROP to replace aggressive-posterior ROP because of increasing recognition that aggressive disease may occur in larger preterm infants and beyond the posterior retina, particularly in regions of the world with limited resources. ROP regression and reactivation are described in detail, with additional description of long-term sequelae.Conclusions: These principles may improve the quality and standardization of ROP care worldwide and may provide a foundation to improve research and clinical care.
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| 13. |
- Garcia, S., et al.
(författare)
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Optimization of planar LIF/Mie imaging for droplet sizing characterization of dilute sprays
- 2023
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Ingår i: Experiments in Fluids. - 0723-4864. ; 64:10
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work is to investigate the planar LIF/Mie droplet sizing technique from an experimental and theoretical point of view. This technique is a good alternative compared to point measurements (e.g., phase Doppler anemometry) or integral approaches (e.g., laser diffraction). It allows measurement of the Sauter mean diameter over a wide field, providing the spray topology and droplet size in a limited amount of time. Nevertheless, its implementation remains challenging due to the fact that the usual assumptions underlying the technique are not fully valid in practice. To overcome these limitations, an innovative experimental set-up has been developed including the use of a telecentric lens and a TwinCam beam splitter device. The benefit of the key optical elements introduced in the set-up will be discussed and quantified in the paper. In particular, it is shown that the telecentric lens removes angular dependency of the Lorenz–Mie optical signals. This is demonstrated using an ethanol hollow cone spray (seeded with rhodamine 6G) generated from a simplex injector at atmospheric pressure and ambient room temperature. A calibration procedure, based on phase Doppler anemometry measurements, is used to convert the LIF/Mie into Sauter mean diameter maps. The optical depth of the spray has been measured, exhibiting values less than 0.4 (equal to 67% light transmission), which corresponds to a dilute cloud of droplets where multiple light scattering is not an issue. These effects have been quantified using Monte Carlo simulations. Finally, a study of the injection parameters has been undertaken, showing the robustness and efficiency of the planar LIF/Mie droplet sizing method to obtain two-dimensional maps of the Sauter mean diameter.
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| 14. |
- Gil Berrocal, Carlos, 1986, et al.
(författare)
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Analysis of the flexural response of hybrid reinforced concrete beams with localized reinforcement corrosion
- 2023
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Ingår i: Structural Concrete. - 1751-7648 .- 1464-4177. ; 24:4, s. 4799-4822
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a modeling approach to analyze the flexural response of hybrid reinforced concrete beams with localized corrosion. A new mechanical model based on extensive uniaxial testing is proposed to describe the stress–strain relationship of corroded bars with a single pit. The proposed mechanical model is then incorporated into a sectional analysis to determine the moment curvature relationship of hybrid reinforced concrete sections with pitting corrosion. The actual crack pattern is used to divide a beam into discrete hinge elements which are then combined to compute the load–deflection response of statically determinate beams. The modeling approach is evaluated with available experimental data showing good predictive capabilities. A parametric study revealed the importance of the interaction between the tensile reinforcement ratio and the concrete postcracking residual stress. Furthermore, the deformation capacity of reinforcement bars with pitting corrosion levels beyond 0.25 was shown to have a dominant effect on the ultimate deflection of hybrid reinforced concrete beams.
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| 15. |
- Guénot, D., et al.
(författare)
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Simultaneous laser-driven x-ray and two-photon fluorescence imaging of atomizing sprays
- 2020
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Ingår i: Optica. - 2334-2536. ; 7:2, s. 131-134
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Tidskriftsartikel (refereegranskat)abstract
- In this Letter, we report for the first time, to the best of our knowledge, the possibility of visualizing an atomizing spray by simultaneously recording x-ray absorption and two-photon laser-induced fluorescence imaging. This unique illumination/detection scheme is made possible due to the use of soft x rays emitted from a laser-driven x-ray source. An 800 mJ laser pulse of 38 fs duration is used to generate an x-ray beam with up to 4 × 108 photons ranging from 1 to 10 keV, allowing projection radiography of water jets generated by an automotive port fuel injector. In addition, a fraction of the laser pulse (∼10mJ) is employed to form a light sheet and to induce two-photon fluorescence in a dye added to the water. The resulting high-contrast fluorescence images provide fine details of the spray structure, with reduced blur from multiple light scattering, while the integrated liquid mass is extracted from the x-ray radiography. In this proof of principle, we show that the combination of these two highly complementary techniques, in both the visible and soft x-ray regimes, is very promising for future characterization of challenging spray, as well as for further understanding of the physics of liquid atomization.
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| 16. |
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