Canadian Light Source Research Articles

Scanning Transmission X-Ray Microscopy At The Canadian Light Source: Progress And Selected Applications In Geosciences

Scanning Transmission X-Ray Microscopy At The Canadian Light Source: Progress And Selected Applications In Geosciences

Mono- and di-deuterated ammonias: Far-infrared spectra and spectroscopic parameters in the ground state

Transitions of NH2D and ND2H have been detected in the high resolution spectrum of 14ND3 recorded at unapodized resolution of 0.00096 cm−1 in the region 60–600 cm−1 using the Bruker IFS 125 Fourier transform spectrometer located at the synchrotron far-infrared beamline, Canadian Light Source. In this study we report on the observation and analysis of the spectrum for the ground state of NH2D and ND2H. 2153 rotation and rotation-inversion transitions, with J up to 24, were assigned for NH2D, and 3214 transitions, with J up to 28, for ND2H. The newly assigned transitions, together with those present in the literature, were fitted on the basis of a Watson-type S reduced Hamiltonian using the IIIr and IIIl representations for NH2D and ND2H, respectively. The model Hamiltonian includes terms up to the 10th power of the angular momentum and vibration–rotation interaction terms between the inversion states. Precise and extended sets of spectroscopic effective parameters were derived for both isotopologues as results of least squares weighted fit procedures that reproduce the transition wavenumbers at experimental accuracy.

Towards in Operando XAS Investigation of CO2 Electrolysis in Solid Oxide Cells: Synchrotron Studies of La0.3Ca0.7Fe0.7Cr0.3O3-δ Perovskites

Solid oxide cells (SOCs) are poised to provide a significant contribution to the emerging field of green technology. SOCs could form the basis for a closed loop, sustainable energy system in which fuel cells generate power efficiently and any waste products are converted back into fuel or useful products.Early solid oxide fuel cell (SOFC) systems utilized ceramic-metal composites, such as Ni-YSZ, as the fuel electrodes. Ni metal provides electronic conduction while YSZ plays the role of oxygen anion conductor. This requires the catalyst target (e.g., H2) to come into contact with both Ni and YSZ, forming a so-called triple phase boundary.Cermet systems perform well but are typically unstable under oxidizing conditions and are susceptible to passivating phenomena, such as sulfur poisoning. Since then, mixed ionic and electronic conductors (MIECs) have been developed, where a single material such as a perovskite replaces both cermet components. The gas-MIEC interface acts as a double phase boundary, theoretically providing electrochemical reaction sites on the entire surface of the electrode. This makes them less susceptible to poisoning by impurities, and the oxide composition can be tailored to improve stability in reducing or oxidizing environments. SOFCs based on mixed-conducting catalysts have shown marked performance increases over room-temperature fuel cells in ORR catalysis, often with an order of magnitude advantage in current response. Further work led to MIEC compositions being used at SOFC fuel electrodes, and more recently, as active catalysts for the carbon dioxide reduction (CO2RR) reaction in electrolysis cells (SOECs).Our research group recently demonstrated that the perovskite material, La0.3Ca0.7Fe0.7Cr0.3O3-δ (LCFCr), shows excellent stability and activity during the OER and ORR. This single composition is also highly active for the CO2RR, opening the door for reversible and symmetrical SOC devices (RSOFCs) that promise to greatly reduce device complexity. This should ease the difficulty of scaling up these technologies for industrial applications. While we have observed performance gains in both SOC modes of operation using LCFCr, we sought to better understand the underlying mechanism of catalysis in CO2 electrolysis. This has led us to begin a thorough investigation of LCFCr-based reversible SOFCs using synchrotron x-ray absorption spectroscopy (XAS), culminating with in operando studies, where CO2 electrolysis can be tracked as it happens in fully operational electrolysis cells. Harsh operating conditions have made in situ or in operando SOC studies more challenging than those for RT cells, which also share the barriers of access to electrode surfaces and the attenuation effect of feedstocks on incident energy used for spectroscopy.This presentation will introduce our initial efforts in synchrotron XAS studies of the as-synthesized LCFCr material, which was prepared by combustion synthesis of precursor metal nitrates. Synchrotron energy provided by the Canadian Light Source (CLS) was used to study powder samples of this composition; experiments were carried out at both hard (SXRMB) and soft (SGM) x-ray sources at the CLS. Preliminary experiments consisted of ex situ XAS testing of samples heat treated using conditions similar to those encountered in operation (800 °C in air or CO2). When compared to spectra of as-synthesized compositions, this provides a conventional “before and after” comparison and has demonstrated that overall changes in oxidation state and coordination environment could be observed. In situ testing was also carried out at SXRMB on La0.3Ca0.7Fe0.7Cr0.3O3-δ powder samples. Samples were placed in a “six-shot” apparatus that provided a versatile test bed for semi-realistic conditions. In these studies, materials were heated in air to 800 °C, while XANES spectra (Fe K-edge) were collected simultaneously. This process was repeated as the gas was changed to CO2, and then upon cooling. These transitionary XAS measurements allowed us to observe both structure and valence state of the material responding in real time. The results showed changes in the pre-edge feature and edge intensity that we have attributed to a change in local vacancy concentration around Fe metal centers. At each stable set of conditions, full EXAFS spectra were collected for all four metals; initial analysis suggests that chromium undergoes redox changes while the iron valence state remains largely unchanged. Together, this set of experiments is allowing us to assemble a dynamic picture of the chemical and structural state of the catalyst during operation.This study underscores the value of in situ and in operando investigation of SOC catalysts compared to traditional ex situ analysis. Insights into efficient SOC electrolysis of CO2 could give us the ability to reduce carbon emissions. It is both urgent and vital that the underlying mechanisms are understood more completely.

Beneficial effect of gelatin on iron gall ink corrosion

Iron gall Inks corrosion causes paper degradation (browning, embrittlement) and treatments were developed to tackle this issue. They often include resizing with gelatin to reinforce the paper and its cellulosic fibers (of diameter approx. 10 µm). This work aimed at measuring the distribution of ink components at the scale of individual paper fibers so as to give a better understanding of the impact of gelatin (re-)sizing on iron gall ink corrosion. For this purpose, scanning transmission X-ray microscopy (STXM) was used at the Canadian light source synchrotron (CLS, Saskatoon). This technique combines nano-scale mapping (resolution of 30 nm) and near edge X-ray absorption fine structure (NEXAFS) analysis. Fe L-edge measurements enabled to map iron distribution and to locate iron(II) and iron(III) rich areas. N K-edge measurement made it possible to map gelatin distribution. C K-edge measurements allowed mapping and discrimination of cellulose, gallic acid, iron gall ink precipitate and gelatin. Three fibers were studied: an inked fiber with no size, a sized fiber that was afterwards inked and an inked fiber sprayed with gelatin. Analysis of gelatin and ink ingredients distribution indicated a lower amount of iron inside the treated cellulosic fiber, which may explain the beneficial effect of gelatin on iron gall ink corrosion.

In-situ synchrotron X-ray imaging of ultrasound (US)-generated bubbles: Influence of US frequency on microbubble cavitation for membrane fouling remediation

Gaining an in-depth understanding of the characteristics and dynamics of ultrasound (US)--generated bubbles is crucial to effectively remediate membrane fouling. The goal of present study is to conduct in-situ visualization of US-generated microbubbles in water to examine the influence of US frequency on the dynamics of microbubbles. This study utilized synchrotron in-line phase contrast imaging (In-line PCI) available at the biomedical imaging and therapy (BMIT) beamlines at the Canadian Light Source (CLS) to enhance the contrast of liquid/air interfaces at different US frequencies of 20, 28 and 40 KHz at 60 Watts. A high-speed camera was used to capture 2,000 frames per second of the bubble cavitation generated in water under the ultrasound influence. Key parameters at the polychromatic beamlines were optimized to maximize the phase contrast of gas/liquid of the microbubbles with a minimum size of 5.5 µm. ImageJ software was used to analyze the bubble characteristics and their behavior under the US exposure including the microbubble number, size, and fraction of the total area occupied by the bubbles at each US frequency. Furthermore, the bubble characteristics over the US exposure time and at different distances from the transducer were studied. The qualitative and quantitative data analyses showed that the microbubble number or size did not change over time; however, it was observed that most bubbles were created at the middle of the frames and close to the US field. The number of bubbles created under the US exposure increased with the frequency from 20 kHz to 40 kHz (about 4.6 times). However, larger bubbles were generated at 20 kHz such that the average bubble radius at 20 kHz was about 6.8 times of that at 40 kHz. Microbubble movement/traveling through water was monitored, and it was observed that the bubble velocity increased as the frequency was increased from 20 kHz to 40 kHz. The small bubbles moved faster, and the majority of them traveled upward towards the US transducer location. The growth pattern (a correlation between the mean growth ratio and the exposure time) of bubbles at 20 kHz and 60 W was obtained by tracking the oscillation of 22 representative microbubbles over the 700 ms of imaging. The mean growth ratio model was also obtained.

First Results Operating a Long-Period EPU in Universal Mode at the Canadian Light Source

First Results Operating a Long-Period EPU in Universal Mode at the Canadian Light Source

Vertical Phase Space Measurement Progress at Canadian Light Source

Vertical Phase Space Measurement Progress at Canadian Light Source

Upgrades to the Booster to Storage Ring Transfer Line at the Canadian Light Source

Upgrades to the Booster to Storage Ring Transfer Line at the Canadian Light Source

Energy Compression System Radio Frequency Design at the Canadian Light Source

Energy Compression System Radio Frequency Design at the Canadian Light Source

Review of health research at the Canadian Light Source

Health research is a key focus area at the Canadian Light Source (CLS). From 2017 through 2019, researchers from across Canada have made impressive use of the capabilities of CLS beamlines to collect data and advance many challenging projects. These researchers published more than 200 health-related papers and deposited more than 400 structure coordinates in the Protein Data Bank during this period. The summaries presented in this review highlight a representative selection of this research, covering a range of health issues including; cystic fibrosis, hearing loss, osteoporosis, Alzheimer’s, malaria, cancer, and the role of the microbiome. Advances in the development of new antibiotics and other novel pharmaceuticals are also discussed.

Operating the Canadian Light Source during the Pandemic: Safety, Innovations, and Perseverance

2020 was a very difficult year. Everyone, everywhere, experienced some level of disruption and every light source was affected. The Canadian Light Source (CLS) was in the middle of a planned outage...

Structure of Enterohemorrhagic Escherichia coli O157:H7 Intimin Virulence Factor Bound to Nanobodies

Enterohemorrhagic E. coli O157:H7 (EHEC) is a food and water-born pathogen that presents a significant risk to human health worldwide. EHEC naturally resides in the intestinal tract of cattle as normal flora but can be transmitted to humans when contaminated food is ingested. Once EHEC invades and colonizes the human intestinal tract, it secretes Shiga-like toxins causing serious and potentially fatal gastrointestinal diseases. Unlike most foodborne bacterial diseases, antibiotics are not recommended for treatment of EHEC as antibiotics can induce enterotoxin release, increasing the risk of hemolytic uremic syndrome. There is currently no effective treatment or vaccine against enterohemorrhagic E. coli. EHEC pathogenicity involves intimin, a virulence factor which mediates bacterial colonization of the host GI tract. Due to its critical role in EHEC pathogenesis, intimin has attracted attention as an antibacterial drug target. Inhibiting the interaction of intimin with its cognate bacterial secreted receptor Tir could neutralize bacterial colonization of the gastrointestinal tract. One novel solution for treating EHEC infection comes from a unique class of antibodies known as nanobodies. Nanobodies are the antigen binding domain of heavy chain antibodies produced by the Camelid family. Intimin specific nanobodies were generated by immunizing a llama followed by phage display and selection for high affinity intimin binding nanobodies. The resultant intimin-specific nanobodies neutralized EHEC in vitro. We hypothesize that nanobodies specifically bind the Tir-binding domain of intimin in order to neutralizing EHEC infection. The goal of this research project is to determine the complex crystal structure of the nanobodies bound to intimin. The structure of nanobodies-intimin would show their protein-protein interaction binding site revealing key amino acids involved in binding. These residues could also be involved in the binding of intimin to its natural ligand, Tir. Thus, revealing such residues could form the bases for identifying and developing novel therapeutics and biosensors for treating and preventing EHEC pathogenesis.We show through size exclusion chromatography that nanobodies bind intimin and form stable complexes. We have set up crystal trails of five nanobodies (Int1, Int2, Int3, Int4, and IntN1) complexed to intimin. Two of the five complexed proteins, Int2-intimin and Int3-intimn formed crystals. The crystal condition for the two protein complexes Int2 and Int3 bound to intimin were optimized by varying the concentration of precipitants and pH range. Crystals of the protein complexes were sent to the Canadian Light Source for X-ray diffraction data collection. Diffraction measurements of Int2-intimin and Int3-intimin complexes were collected and processed in space groups P1 and P222, respectively. Currently, we are analyzing the structure by molecular replacement.

Aeration of the Human Prussak's Space: A 3D Synchrotron Imaging Study.

Prussak's space (PS) is an intricate middle ear region which may play an essential role in the development of middle ear disease. The three-dimensional (3D) anatomy of the human PS and its drainage routes remain relatively unknown. Earlier studies have histologically analyzed PS, by micro-dissection and endoscopy. Here, we used synchrotron-radiation phase-contrast imaging (SR-PCI), 3D reconstructions, and modeling to study the framework of the human PS, including aeration pathways. It may lead to increased understanding of development of middle ear pathology. Nine human temporal bone specimens underwent in-line SR-PCI at the Canadian Light Source in Saskatoon, Saskatchewan, Canada. Data were processed with volume-rendering software to create 3D reconstructions using scalar opacity mapping and segmentations to visualize its walls in fixed, undecalcified human temporal bones. The PS was found to be an irregular, variably shaped chamber with different aeration systems. Three different drainage pathways were found: 1) via the posterior malleolar pouch of von Tröltsch in seven of nine ears; 2) directly posterior-inferior into the mesotympanum medial to the posterior malleolar pouch in one ear; and 3) anteriorly in another. The posterior-inferior communications depended on the anatomy of the posterior malleolar fold. In one bilateral case, the aeration differed between the ears. Earlier descriptions of upper ventilation routes between the PS and the epitympanic spaces could not be substantiated. The 3D anatomy of the membrane folds organizing the PS in humans was demonstrated for the first time using in-line SR-PCI. The PS was always aerated into the mesotympanum, suggesting its relative independence of attic ventilation. The impact of its various drainage routes on middle ear ventilation and disease were discussed.

The lower energy diffraction and scattering side-bounce beamline for materials science at the Canadian Light Source

A new diffraction beamline for materials science has been built at the Canadian Light Source synchrotron. The X-ray source is an in-vacuum wiggler with a 2.5 T peak magnetic field at 5.2 mm gap. The optical configuration includes a toroidal mirror, a single side-bounce Bragg monochromator, and a cylindrical mirror, producing a sub-150 µm vertical× 500 µm horizontal focused beam with a photon energy range of 7-22 keV and a flux of 1012 photons per second at the sample position. Three endstations are currently open to general users, and the techniques available include high-resolution powder diffraction, small molecule crystallography, X-ray reflectivity, in situ rapid thermal annealing, and SAXS/WAXS. The beamline design parameters, calculated and measured performance, and initial experimental results are presented to demonstrate the capabilities for materials science.

Developing a Microbubble-Based Contrast Agent for Synchrotron In-Line Phase Contrast Imaging.

X-ray phase contrast imaging generates contrast from refraction of X-rays, enhancing soft tissue contrast compared to conventional absorption-based imaging. Our goal is to develop a contrast agent for X-ray in-line phase contrast imaging (PCI) based on ultrasound microbubbles (MBs), by assessing size, shell material, and concentration. Polydisperse perfluorobutane-core lipid-shelled MBs were synthesized and size separated into five groups between 1 and 10μm. We generated two size populations of polyvinyl-alcohol (PVA)-MBs, 2-3μm and 3-4μm, whose shells were either coated or integrated with iron oxide nanoparticles (SPIONs). Microbubbles were then embedded in agar at three concentrations: 5×107, 5×106 and 5×105 MBs/ml. In-line phase contrast imaging was performed at the Canadian Light Source with filtered white beam micro-computed tomography. Phase contrast intensity was measured by both counting detectable MBs, and comparing mean pixel values (MPV) in minimum and maximum intensity projections of the overall samples. Individual lipid-MBs 6-10μm, lipid-MBs 4-6μm and PVA-MBs coated with SPIONs were detectable at each concentration. At the highest concentration, lipid-MBs 6-10μm and 4-6μm showed an overall increase in positive contrast, whereas at a moderate concentration, only lipid-MBs 6-10μm displayed an increase. Negative contrast was also observed from two largest lipid-MBs at high concentration. These data indicate that lipid-MBs larger than 4μm are candidates for PCI, and 5×106 MBs/ml may be the lowest concentration suitable for generating visible phase contrast in vivo. Identifying a suitable MB for PCI may facilitate future clinical translation.

Electroless Deposition for Nanoscale Applications: Challenges and Opportunities

We recently developed a maskless, electroless, high-P-content, Ni(P) process to protect the final Cu bitline wiring level in our STTM MRAM test vehicles to enable functional testing in an air atmosphere at elevated temperatures for evaluation of MRAM device memory state retention. The process was developed as a replacement for the final aluminum level, and drastically shortened wafer processing cycle time. We demonstrated an electroless Ni(P) that selectively deposited on Cu bit lines with effective spacing approaching 200 nm without shorting, for coating thicknesses up to ca. 50 - 60 nm, with excellent bitline coverage (no pinholes). This was achieved through optimization of Cu surface cleanliness, surface catalyzation using an acidic Pd solution, and finally electroless Ni(P) deposition (1).Testing (electrical resistance and magnetoresistance (R & MR)) of Ni(P)-coated wafers, showed virtually unchanged R & MR for MRAM 4Kb arrays encompassing a large range of device critical dimensions (CDs). Figure 1 shows a topdown SEM image of a region of electroless Ni(P)-coated Cu bitlines.While electroless deposition is capable of depositing only a limited number of metals and alloys compared to electrodeposition, it is often easier to obtain coatings of uniform thickness and composition, since one does not have the current density uniformity problem of electrodeposition. Although it is not always possible to obtain pure materials using electroless deposition, nevertheless, materials with unique properties, such as Ni(P) (corrosion resistance), and Co(P) (magnetic properties) and related alloys e.g., Co(W)(P), are readily obtained by electroless deposition methods. These materials may be crystalline or amorphous, and the crystallization kinetics of the latter type may be strongly dependent on film thickness, and have a two-dimensional character due to interfacial effects.It is important to understand how such materials transform upon heating, given that back-end-of-line (BEOL) processing may involve temperature excursions to 400 ⁰C. We will discuss in detail the kinetics of crystallization of our high-P-content, amorphous, electroless Ni(P) films on Cu thin films using synchrotron X-Ray diffraction analysis (2). For 1 um thick Ni-P films deposited on Cu/Ta/TaN underlayer, as we increase the rates at which the temperature is raised during ramp anneals, crystallization temperatures vary from about 360C to 400C from which we extract an activation energy of 3.4 eV for this crystallization. The in-situ data also shows a gradual reduction in lattice constant for the underlying Ta layer. We will complement the synchrotron X-Ray analysis study results with TEM, SIMS and X-ray fluorescence (XRF) results of Ni(P) film composition for unpatterned and patterned (sub-micron) features.In addition to the subtlety of its mechanisms and range of solution formulations, electroless deposition has much to offer in terms of niche applications, which explains why it is often turned to first by researchers seeking creative deposition methods in the still emerging field of nanofabrication. Given the wide range of materials involved in electroless deposition, whether it is the final product, or the choice of a reasonable reducing agent, the mechanism of electroless deposition tends to be complex. This talk will include a discussion of the mechanism of electroless deposition, and whether the sought after, one-mechanism-fits-all approach, is tenable.[1]. E. J. O'Sullivan et al 2019 Meet. Abstr. MA2019-02 916; https://doi.org/10.1149/MA2019-02/15/916 [2]. Canadian Light Source Inc., 44 Innovation Boulevard Saskatoon, SK S7N 2V3, Canada. Acknowledgements The authors gratefully acknowledge the efforts of the staff of the Microelectronics Research Laboratory (MRL) at the IBM T. J. Watson Research Center, where some of the fabrication work described in this talk was carried out. Part of the research described in this paper was performed at the Canadian Light Source, a national research facility of the University of Saskatchewan, which is supported by the Canada Foundation for Innovation (CFI), the Natural Sciences and Engineering Research Council (NSERC), the National Research Council (NRC), the Canadian Institutes of Health Research (CIHR), the Government of Saskatchewan, and the University of Saskatchewan.

In-Situ Soft X-Ray Spectromicroscopy Characterization of Electrochemical Processes

Soft X-ray Scanning Transmission X-ray microscopy (STXM) is a synchrotron-based technique which can provide both spectroscopic characterization (near edge X-ray absorption fine structure, NEXAFS) and chemically selective imaging with high spatial resolution (~30 nm). Recently, we have developed in situ flow electrochemical devices [1,2] which allow control of the electrochemical environment while conducting STXM measurements, thus providing a platform for in-situ studies of electrochemical oxidation and reduction processes. This presentation reports results of in situ flow electrochemical STXM studies on three different systems to demonstrate the present capabilities. First, the ability to rapidly exchange the electrolyte is demonstrated by a STXM Fe 2p and in situ electrochemical study of the ferro/ferricyanide solution redox system. Second Cu and Ag-doped Cu catalysts for CO2 electrochemical reduction (CO2R) were successfully prepared using in situ electrodeposition. Third, the electrolyte was changed from CuSO4 to NaHCO3 (as substrate for CO2R) and the cell was operated under electrochemical CO2 reduction conditions, while monitoring the changes to the Cu deposited layer at various potentials, including –0.5 V where CO2 reduction is expected [3]. The figure shows a cyclic voltammogram (CV) and color-coded Cu oxidation state maps which were derived from Cu 2p stacks measured under chronoamperometric conditions at the indicated potentials. These results demonstrate that in situ flow electrochemical STXM measurements can be performed in our device under varying electrochemical reaction conditions, enabling visualization of the morphology changes from selective energy imaging, and quantitative tracking of electrochemical transformations from spectromicroscopy. This system will be used for in situ studies of CO2 electrochemical reduction catalysis with the goal of obtaining mechanistic insights to guide the development of catalysts with improved efficiency and selectivity. In addition, the system will be used to study a variety of material science, chemistry and environmental science related questions associated with oxidation or reduction processes, such as mechanisms of extra-cellular electron transport in marine sediment microbial biofilms [4].This research is supported by NSERC (Canada). STXM measurements were performed at the ambient STXM facility at the Canadian Light Source, which is funded by the Canadian Foundation for Innovation.[1] V. Prabu et al., Rev. Sci. Inst. 89 (2018) 063702.[2] P. Ingino, et al., in preparation[3] L. Wang, D.C. Higgins, et al., Proc. Nat. Acad. Sci. (2020) 01821683. DOI: 10.1073/pnas.1821683117[4] M. Obst, et al., Microsc. Microanal. 24 (S-2) (2018) 502-504. Figure 1

Very high-resolution synchrotron radiation far-infrared (FIR) spectrum of methanol‑D2 (CHD2OH) & millimeter-wave (MMW) measurements involving highly excited torsional vibrational rotational states, and identification of optically pumped FIR laser lines

Synchrotron radiation-based very high-resolution far-infrared (FIR) spectrum recorded at the Canadian Light Source (CSL) of doubly deuterated asymmetric methanol molecule (CHD2OH) have been analyzed for transitions associated with highly excited torsional-vibration–rotation levels. Complimentary millimeter-wave (MMW) transition frequencies have been measured using a backward wave oscillator based spectrometer at the Ohio State University. A new and simplified model has been proposed to treat the Hamiltonian Eigenvalues which do not require a large number of parameters with uncertain physical significance. A systematic approach has been laid out on how to proceed in order to obtain self-consistent and rigorously confirmed assignment of an extremely complicated spectrum arising due interaction with other states. New measurements in the MMW region should facilitate astrophysical determination of column densities of this abundant molecular species in cold interstellar clouds, especially in star-forming regions. The scarcity of MMW and the FIR laboratory database severely hindered the astrophysical work in the past. All the FIR assignments have been rigorously confirmed by closed combination relations (CR) using the MMW measurements and/or through ground state CRs from fundamental vibrational band analysis. These FIR transitions are presented in the form an atlas of about 900 lines. As a byproduct of the measurements, it was possible to put forward tentative assignments of optically pumped FIR laser lines.

Synchrotron based Micro Tomography (SR-μCT), Experimental, and Computational Studies to Investigate the Influences of Cross Flow Air Injection in Ultrafiltration Process

The goal of the present study is to gain an in depth understanding of the influences of air injected concurrently and counter currently on membrane fouling and permeate flux for homogeneous Polycarbonate (PC) and heterogeneous Polysulfone (PS) membranes in the cross-flow ultrafiltration (UF). The Synchrotron-based X-ray microtomography (SR-μCT) technique, available at the biomedical imaging and therapy (BMIT) beamlines at the Canadian Light Source (CLS), answered the key research questions related to quantitative analysis and the visualization of particle depositions, layer by layer, in heterogeneous membrane matrices that would otherwise be opaque to optical access. In particular, high photon flux to achieve high resolution is infeasible, using lab-based radiography systems. SR-μCT was used to assess the influence of air injection on membrane fouling in each membrane layer of PS membrane matrices. A multiphase cross-flow filtration and the hydrodynamics was simulated, in the rectangular filtration channel, using computational fluid dynamics (CFD) at different air velocities. Furthermore, the scanning electron microscope (SEM) and confocal microscope imaging were used at different positions of the membranes to examine the influences of the velocity profiles on membrane fouling. SR-μCT innovative techniques proved that counter current air flow resulted in the elimination of membrane fouling at the top layers, but severe fouling between intermediate and lower layers of the investigated region inside the PS membrane matrices using counter-current air injection compared to concurrent air injection. These results indicate more particle deposited and trapped inside membrane matrices when air was injected counter-currently, which led to more turbulences and a reduction of the permeate flux. On the other hand, top layer indices depict strongly fouling on the bare PS without air injection. CFD analyses supported the experimental results, where the concurrently injected air was more effective in increasing the shear rate and reducing the concentration polarization while reducing turbulences and vortexes, as compared to the counter currently injected air. This innovative study is the first to report the SR-μCT for investigating membrane fouling in UF process for water and wastewater treatment.

Glovebox-integrated XES and XAS station for in situ studies in tender x-ray region

X-ray emission spectroscopy (XES), as a complementary technique to x-ray absorption spectroscopy (XAS), is powerful in the analysis of the electronic structure of the materials by probing the occupied density of states with high energy resolution. Recently, an XES spectrometer optimized for the tender x-ray region (2–5 keV) was successfully installed into an inert atmosphere glovebox, and the entire system was successfully integrated into the SXRMB (soft x-ray microcharacterization beamline) at the Canadian Light Source. Here, the technical design and the performance of the SXRMB XES-integrated glovebox station is presented. High energy resolution of ∼1 eV or better has been achieved for the spectrometer in the tender energy x-ray ranges. Capability of the station for in-situ XES and XAS measurements is demonstrated using an example of phosphorus phase transformation in phosphorus anodes for lithium-ion battery research.