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25 results on '"Valadian, Roozbeh"'

1. Inspection of chicken wings and legs for animal welfare monitoring using X-ray computed tomography, visual examination, and histopathology

Author

Libera, Kacper, Valadian, Roozbeh, Vararattanavech, Patiharn, Dasari, Sri Nithya, Dallman, Timothy J, Weerts, Erik, Lipman, Len, Libera, Kacper, Valadian, Roozbeh, Vararattanavech, Patiharn, Dasari, Sri Nithya, Dallman, Timothy J, Weerts, Erik, and Lipman, Len

Abstract

In broiler chickens, fractures of wings and legs are recorded at poultry slaughterhouses based on the time of occurrence. Prekilling (PRE) fractures occur before the death of animal, so the chicken was still able to experience pain and distress associated with the injury (an animal welfare issue). Postkilling (POST) fractures occur when the chickens are deceased and fully bled-out and consequently unable to feel pain (not an animal welfare issue). Current practice dictates that fractures are recognized visually and recorded by the animal welfare officers as mandated by European Union and/or national regulations. However, new potential monitoring solutions are desired since human inspection suffers from some significant limitations including subjectivism and fatigue. One possible solution in detecting injuries is X-ray computed tomography (CT) scanning and in this study we aim to evaluate the potential of CT scanning and visual inspection in detecting limb fractures and their causes. Eighty-three chicken wings and 60 chicken legs (n = 143) were collected from a single slaughterhouse and classified by an animal welfare officer as PRE, POST or healthy (HEAL). Samples were photographed and CT scanned at a veterinary hospital. The interpretation of CT scans along with photographs took place in 3 rounds (1. CT scans only, 2. CT scans + photographs, 3. photographs only) and was performed independently by 3 veterinarians. The consistency of the interpretation in 3 rounds was compared with the animal welfare officer's classification. Furthermore, selected samples were also analyzed by histopathological examination due to questionability of their classification (PRE/POST). In questionable samples, presence of hemorrhages was confirmed, thus they fit better as PRE. The highest consistency between raters was obtained in the 2nd round, indicating that interpretation accuracy was the highest when CT scans were combined with photographs. These results indicate that CT scanning

Published
2024

2. Inspection of chicken wings and legs for animal welfare monitoring using X-ray computed tomography, visual examination, and histopathology

Author

IRAS OH Epidemiology Microbial Agents, VPDC pathologie, IRAS – One Health Microbial, Libera, Kacper, Valadian, Roozbeh, Vararattanavech, Patiharn, Dasari, Sri Nithya, Dallman, Timothy J, Weerts, Erik, Lipman, Len, IRAS OH Epidemiology Microbial Agents, VPDC pathologie, IRAS – One Health Microbial, Libera, Kacper, Valadian, Roozbeh, Vararattanavech, Patiharn, Dasari, Sri Nithya, Dallman, Timothy J, Weerts, Erik, and Lipman, Len

Published
2024

3. Porous Catalyst Characterization Using X-ray Nano Tomography and Pore Network Modeling

Author

Valadian, Roozbeh and Valadian, Roozbeh

Abstract

This PhD Thesis focuses mainly on the characterization of complex porous materials at the low micrometer and sub-micron length scale. The characterization techniques used in this PhD Thesis can be classified into two synchrotron-based X-ray microscopy (XRM) techniques: i) X-ray holotomography and ii) correlative ptychographic X-ray computed tomography (PXCT) and X-ray fluorescence (XRF) tomography. X-ray holotomography combined with pore network (PN) modeling was used to study deactivation mechanisms caused by coke and metal deposition within a single fluid catalytic cracking (FCC) catalyst particle. Furthermore, the same combination was used for studying the heterogeneity in the fragmentation behavior of a set of metallocene-type catalyst particles at different stages of ethylene polymerization. Correlative PXCT and XRF tomography was used to perform statistical analysis and to quantify the degree of fragmentation of an ensemble of Ziegler-type ethylene polymerization catalyst particles by mapping support, polymer, and mixed phases at high spatial resolution. Moreover, the pore structure as well as the element distribution within a single FCC catalyst particle was mapped using correlative PXCT and XRF tomography. The obtained morphological and elemental information allowed performing a mass transport simulation based on pore network modeling, which revealed invaluable insights into the diffusion behavior of reactant and product molecules as well as active site accessibility within a single FCC catalyst particle.

Published
2022

7. X-ray nanotomography uncovers morphological heterogeneity in a polymerization catalyst at multiple reaction stages

Author

Werny, Maximilian J., Valadian, Roozbeh, Lohse, Leon M., Robisch, Anna Lena, Zanoni, Silvia, Hendriksen, Coen, Weckhuysen, Bert M., Meirer, Florian, Werny, Maximilian J., Valadian, Roozbeh, Lohse, Leon M., Robisch, Anna Lena, Zanoni, Silvia, Hendriksen, Coen, Weckhuysen, Bert M., and Meirer, Florian

Abstract

During olefin polymerization on supported catalysts, the controlled morphological evolution of the catalyst particle is vital for ensuring optimal product properties and high catalyst activity. We employed non-destructive hard X-ray holotomography to quantitatively assess the 3D morphology of multiple silica-supported hafnocene-based catalyst particles during the early stages of gas-phase ethylene polymerization. Image processing and pore network modeling revealed clear variations in the dimensions and interconnectivity of pristine particles' macropore networks. This, together with apparent differences in the fragmentation behavior of pre-polymerized particles, suggests that the reactivity and morphological evolution of individual particles are largely dictated by their unique support and pore space architectures. By minimizing the structural heterogeneity among pristine catalyst particles, more uniform particle morphologies may be obtained. Significant polymerization activity, observed in the particles' interiors, further implies that appropriate polymerization conditions and catalyst kinetics can guarantee sufficiently high particle accessibilities and thus more homogeneous support fragmentation.

Published
2021

8. Heterogeneity in the Fragmentation of Ziegler Catalyst Particles during Ethylene Polymerization Quantified by X-ray Nanotomography

Author

Bossers, Koen W, Valadian, Roozbeh, Garrevoet, Jan, van Malderen, Stijn, Chan, Robert, Friederichs, Nic, Severn, John, Wilbers, Arnold, Zanoni, Silvia, Jongkind, Maarten K, Weckhuysen, Bert M, Meirer, Florian, Bossers, Koen W, Valadian, Roozbeh, Garrevoet, Jan, van Malderen, Stijn, Chan, Robert, Friederichs, Nic, Severn, John, Wilbers, Arnold, Zanoni, Silvia, Jongkind, Maarten K, Weckhuysen, Bert M, and Meirer, Florian

Abstract

Ziegler-type catalysts are the grand old workhorse of the polyolefin industry, yet their hierarchically complex nature complicates polymerization activity-catalyst structure relationships. In this work, the degree of catalyst framework fragmentation of a high-density polyethylene (HDPE) Ziegler-type catalyst was studied using ptychography X-ray-computed nanotomography (PXCT) in the early stages of ethylene polymerization under mild reaction conditions. An ensemble consisting of 434 fully reconstructed ethylene prepolymerized Ziegler catalyst particles prepared at a polymer yield of 3.4 g HDPE/g catalyst was imaged. This enabled a statistical route to study the heterogeneity in the degree of particle fragmentation and therefore local polymerization activity at an achieved 3-D spatial resolution of 74 nm without requiring invasive imaging tools. To study the degree of catalyst fragmentation within the ensemble, a fragmentation parameter was constructed based on a k-means clustering algorithm that relates the quantity of polyethylene formed to the average size of the spatially resolved catalyst fragments. With this classification method, we have identified particles that exhibit weak, moderate, and strong degrees of catalyst fragmentation, showing that there is a strong heterogeneity in the overall catalyst particle fragmentation and thus polymerization activity within the entire ensemble. This hints toward local mass transfer limitations or other deactivation phenomena. The methodology used here can be applied to all polyolefin catalysts, including metallocene and the Phillips catalysts to gain statistically relevant fundamental insights in the fragmentation behavior of an ensemble of catalyst particles.

Published
2021

9. Visualizing defects and pore connectivity within metal-organic frameworks by X-ray transmission tomography

Author

Mayorga-González, Rafael, Rivera-Torrente, Miguel, Nikolopoulos, Nikolaos, Bossers, Koen W., Valadian, Roozbeh, Yus, Joaquín, Seoane, Beatriz, Weckhuysen, Bert M., Meirer, Florian, Mayorga-González, Rafael, Rivera-Torrente, Miguel, Nikolopoulos, Nikolaos, Bossers, Koen W., Valadian, Roozbeh, Yus, Joaquín, Seoane, Beatriz, Weckhuysen, Bert M., and Meirer, Florian

Abstract

Metal-Organic Frameworks (MOFs) have the potential to change the landscape of molecular separations in chemical processes owing to their ability of selectively binding molecules. Their molecular sorting properties generally rely on the micro- and meso-pore structure, as well as on the presence of coordinatively unsaturated sites that interact with the different chemical species present in the feed. In this work, we show a first-of-its-kind tomographic imaging of the crystal morphology of a metal-organic framework by means of transmission X-ray microscopy (TXM), including a detailed data reconstruction and processing approach. Corroboration with Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM) images shows the potential of this strategy for further (non-destructively) assessing the inner architecture of MOF crystals. By doing this, we have unraveled the presence of large voids in the internal structure of a MIL-47(V) crystal, which are typically thought of as rather homogeneous lattices. This challenges the established opinion that hydrothermal syntheses yield relatively defect-free material and sheds further light on the internal morphology of crystals.

Published
2021

10. 3-D X-ray Nanotomography Reveals Different Carbon Deposition Mechanisms in a Single Catalyst Particle

Author

Veselý, Martin, Valadian, Roozbeh, Merten Lohse, Leon, Toepperwien, Mareike, Spiers, Kathryn, Garrevoet, Jan, Vogt, Eelco T. C., Salditt, Tim, Weckhuysen, Bert M., Meirer, Florian, Veselý, Martin, Valadian, Roozbeh, Merten Lohse, Leon, Toepperwien, Mareike, Spiers, Kathryn, Garrevoet, Jan, Vogt, Eelco T. C., Salditt, Tim, Weckhuysen, Bert M., and Meirer, Florian

Abstract

Catalyst deactivation involves a complex interplay of processes taking place at different length and time scales. Understanding this phenomenon is one of the grand challenges in solid catalyst characterization. A process contributing to deactivation is carbon deposition (i.?e., coking), which reduces catalyst activity by limiting diffusion and blocking active sites. However, characterizing coke formation and its effects remains challenging as it involves both the organic and inorganic phase of the catalytic process and length scales from the atomic scale to the scale of the catalyst body. Here we present a combination of hard X-ray imaging techniques able to visualize in 3-D the distribution, effect and nature of carbon deposits in the macro-pore space of an entire industrially used catalyst particle. Our findings provide direct evidence for coke promoting effects of metal poisons, pore clogging by coke, and a correlation between carbon nature and its location. These results provide a better understanding of the coking process, its relation to catalyst deactivation and new insights into the efficiency of the industrial scale process of fluid catalytic cracking.

Published
2021

11. Visualizing defects and pore connectivity within metal-organic frameworks by X-ray transmission tomography

Author

Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Mayorga-González, Rafael, Rivera-Torrente, Miguel, Nikolopoulos, Nikolaos, Bossers, Koen W., Valadian, Roozbeh, Yus, Joaquín, Seoane, Beatriz, Weckhuysen, Bert M., Meirer, Florian, Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Mayorga-González, Rafael, Rivera-Torrente, Miguel, Nikolopoulos, Nikolaos, Bossers, Koen W., Valadian, Roozbeh, Yus, Joaquín, Seoane, Beatriz, Weckhuysen, Bert M., and Meirer, Florian

Published
2021

12. 3-D X-ray Nanotomography Reveals Different Carbon Deposition Mechanisms in a Single Catalyst Particle

Author

Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Veselý, Martin, Valadian, Roozbeh, Merten Lohse, Leon, Toepperwien, Mareike, Spiers, Kathryn, Garrevoet, Jan, Vogt, Eelco T. C., Salditt, Tim, Weckhuysen, Bert M., Meirer, Florian, Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Veselý, Martin, Valadian, Roozbeh, Merten Lohse, Leon, Toepperwien, Mareike, Spiers, Kathryn, Garrevoet, Jan, Vogt, Eelco T. C., Salditt, Tim, Weckhuysen, Bert M., and Meirer, Florian

Published
2021

13. 3-D X-ray Nanotomography Reveals Different Carbon Deposition Mechanisms in a Single Catalyst Particle

Author

Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Veselý, Martin, Valadian, Roozbeh, Merten Lohse, Leon, Toepperwien, Mareike, Spiers, Kathryn, Garrevoet, Jan, Vogt, Eelco T. C., Salditt, Tim, Weckhuysen, Bert M., Meirer, Florian, Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Veselý, Martin, Valadian, Roozbeh, Merten Lohse, Leon, Toepperwien, Mareike, Spiers, Kathryn, Garrevoet, Jan, Vogt, Eelco T. C., Salditt, Tim, Weckhuysen, Bert M., and Meirer, Florian

Published
2021

14. Visualizing defects and pore connectivity within metal-organic frameworks by X-ray transmission tomography

Author

Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Mayorga-González, Rafael, Rivera-Torrente, Miguel, Nikolopoulos, Nikolaos, Bossers, Koen W., Valadian, Roozbeh, Yus, Joaquín, Seoane, Beatriz, Weckhuysen, Bert M., Meirer, Florian, Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Mayorga-González, Rafael, Rivera-Torrente, Miguel, Nikolopoulos, Nikolaos, Bossers, Koen W., Valadian, Roozbeh, Yus, Joaquín, Seoane, Beatriz, Weckhuysen, Bert M., and Meirer, Florian

Published
2021

15. Heterogeneity in the Fragmentation of Ziegler Catalyst Particles during Ethylene Polymerization Quantified by X-ray Nanotomography

Author

Inorganic Chemistry and Catalysis, Sub Inorganic Chemistry and Catalysis, Bossers, Koen W, Valadian, Roozbeh, Garrevoet, Jan, van Malderen, Stijn, Chan, Robert, Friederichs, Nic, Severn, John, Wilbers, Arnold, Zanoni, Silvia, Jongkind, Maarten K, Weckhuysen, Bert M, Meirer, Florian, Inorganic Chemistry and Catalysis, Sub Inorganic Chemistry and Catalysis, Bossers, Koen W, Valadian, Roozbeh, Garrevoet, Jan, van Malderen, Stijn, Chan, Robert, Friederichs, Nic, Severn, John, Wilbers, Arnold, Zanoni, Silvia, Jongkind, Maarten K, Weckhuysen, Bert M, and Meirer, Florian

Published
2021

16. 3-D X-ray Nanotomography Reveals Different Carbon Deposition Mechanisms in a Single Catalyst Particle

Author

Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Veselý, Martin, Valadian, Roozbeh, Merten Lohse, Leon, Toepperwien, Mareike, Spiers, Kathryn, Garrevoet, Jan, Vogt, Eelco T. C., Salditt, Tim, Weckhuysen, Bert M., Meirer, Florian, Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Veselý, Martin, Valadian, Roozbeh, Merten Lohse, Leon, Toepperwien, Mareike, Spiers, Kathryn, Garrevoet, Jan, Vogt, Eelco T. C., Salditt, Tim, Weckhuysen, Bert M., and Meirer, Florian

Published
2021

17. 3-D X-ray Nanotomography Reveals Different Carbon Deposition Mechanisms in a Single Catalyst Particle

Author

Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Veselý, Martin, Valadian, Roozbeh, Merten Lohse, Leon, Toepperwien, Mareike, Spiers, Kathryn, Garrevoet, Jan, Vogt, Eelco T. C., Salditt, Tim, Weckhuysen, Bert M., Meirer, Florian, Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Veselý, Martin, Valadian, Roozbeh, Merten Lohse, Leon, Toepperwien, Mareike, Spiers, Kathryn, Garrevoet, Jan, Vogt, Eelco T. C., Salditt, Tim, Weckhuysen, Bert M., and Meirer, Florian

Published
2021

18. Heterogeneity in the Fragmentation of Ziegler Catalyst Particles during Ethylene Polymerization Quantified by X-ray Nanotomography

Author

Inorganic Chemistry and Catalysis, Sub Inorganic Chemistry and Catalysis, Bossers, Koen W, Valadian, Roozbeh, Garrevoet, Jan, van Malderen, Stijn, Chan, Robert, Friederichs, Nic, Severn, John, Wilbers, Arnold, Zanoni, Silvia, Jongkind, Maarten K, Weckhuysen, Bert M, Meirer, Florian, Inorganic Chemistry and Catalysis, Sub Inorganic Chemistry and Catalysis, Bossers, Koen W, Valadian, Roozbeh, Garrevoet, Jan, van Malderen, Stijn, Chan, Robert, Friederichs, Nic, Severn, John, Wilbers, Arnold, Zanoni, Silvia, Jongkind, Maarten K, Weckhuysen, Bert M, and Meirer, Florian

Published
2021

19. 3-D X-ray Nanotomography Reveals Different Carbon Deposition Mechanisms in a Single Catalyst Particle

Author

Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Veselý, Martin, Valadian, Roozbeh, Merten Lohse, Leon, Toepperwien, Mareike, Spiers, Kathryn, Garrevoet, Jan, Vogt, Eelco T. C., Salditt, Tim, Weckhuysen, Bert M., Meirer, Florian, Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Veselý, Martin, Valadian, Roozbeh, Merten Lohse, Leon, Toepperwien, Mareike, Spiers, Kathryn, Garrevoet, Jan, Vogt, Eelco T. C., Salditt, Tim, Weckhuysen, Bert M., and Meirer, Florian

Published
2021

20. 3-D X-ray Nanotomography Reveals Different Carbon Deposition Mechanisms in a Single Catalyst Particle

Author

Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Veselý, Martin, Valadian, Roozbeh, Merten Lohse, Leon, Toepperwien, Mareike, Spiers, Kathryn, Garrevoet, Jan, Vogt, Eelco T. C., Salditt, Tim, Weckhuysen, Bert M., Meirer, Florian, Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Veselý, Martin, Valadian, Roozbeh, Merten Lohse, Leon, Toepperwien, Mareike, Spiers, Kathryn, Garrevoet, Jan, Vogt, Eelco T. C., Salditt, Tim, Weckhuysen, Bert M., and Meirer, Florian

Published
2021

21. Visualizing defects and pore connectivity within metal-organic frameworks by X-ray transmission tomography

Author

Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Mayorga-González, Rafael, Rivera-Torrente, Miguel, Nikolopoulos, Nikolaos, Bossers, Koen W., Valadian, Roozbeh, Yus, Joaquín, Seoane, Beatriz, Weckhuysen, Bert M., Meirer, Florian, Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Mayorga-González, Rafael, Rivera-Torrente, Miguel, Nikolopoulos, Nikolaos, Bossers, Koen W., Valadian, Roozbeh, Yus, Joaquín, Seoane, Beatriz, Weckhuysen, Bert M., and Meirer, Florian

Published
2021

23. Correlated X-ray Ptychography and Fluorescence Nano-Tomography on the Fragmentation Behavior of an Individual Catalyst Particle during the Early Stages of Olefin Polymerization

Author

Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Bossers, Koen W., Valadian, Roozbeh, Zanoni, Silvia, Smeets, Remy, Friederichs, Nic, Garrevoet, Jan, Meirer, Florian, Weckhuysen, Bert M., Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Bossers, Koen W., Valadian, Roozbeh, Zanoni, Silvia, Smeets, Remy, Friederichs, Nic, Garrevoet, Jan, Meirer, Florian, and Weckhuysen, Bert M.

Published
2020

24. Correlated X-ray Ptychography and Fluorescence Nano-Tomography on the Fragmentation Behavior of an Individual Catalyst Particle during the Early Stages of Olefin Polymerization

Author

Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Bossers, Koen W., Valadian, Roozbeh, Zanoni, Silvia, Smeets, Remy, Friederichs, Nic, Garrevoet, Jan, Meirer, Florian, Weckhuysen, Bert M., Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Bossers, Koen W., Valadian, Roozbeh, Zanoni, Silvia, Smeets, Remy, Friederichs, Nic, Garrevoet, Jan, Meirer, Florian, and Weckhuysen, Bert M.

Published
2020

25. Correlated X-ray Ptychography and Fluorescence Nano-Tomography on the Fragmentation Behavior of an Individual Catalyst Particle during the Early Stages of Olefin Polymerization

Author

Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Bossers, Koen W., Valadian, Roozbeh, Zanoni, Silvia, Smeets, Remy, Friederichs, Nic, Garrevoet, Jan, Meirer, Florian, Weckhuysen, Bert M., Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Bossers, Koen W., Valadian, Roozbeh, Zanoni, Silvia, Smeets, Remy, Friederichs, Nic, Garrevoet, Jan, Meirer, Florian, and Weckhuysen, Bert M.

Published
2020

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