F.EN08: Scientific Basis for Nuclear Waste Management

Dennis Grödler, University of Cologne

Nanostructured Uranium Oxide Thin Films Developed by Molecular Precursors Using Chemical Vapor Deposition

Written by Emma Perry

UF₆ is a waste product of the enrichment stage in nuclear fuel fabrication. It reacts with water to create hydrofluoric acid so it has to be managed very carefully. It is not profitable to convert UF₆ into UO₂ for nuclear fuel but perhaps it is for something else. For example, uranium dioxide is known to be a very good catalyst and to have semiconducting properties. In an experiment using alpha- Fe₂O₃ and U₃O₈ layers to enhance photoelectrical chemical properties of bare hematite, it was found that the heterojunction between U₃O₈ and Fe₂O₃ enhances the properties more than either layer separately. In order to create uranium oxide based catalysts and semiconductors it is necessary to make uranium oxide thin films.

Thin films can be made from chemical vapor deposition but first a precursor is needed that is stable in air, is volatile, is not toxic and has a defined decomposition.  Beta-ketonamines have been successful in the chemical vapor deposition of other compounds and can make a complex through simple salt metathesis. By experimenting with the ratios of reactants and catalysts it was possible to isolate a heteroleptic U(IV) complex. However, these were not volatile. Therefore a homeoleptic U(IV) complex was formed that is volatile and is stable in air.

F.MT03: Frontiers of Imaging and Spectroscopy in Electron Microscopy

Katherine Jungjohann, Sandia National Laboratories

Mapping Structure and Composition of Intact Li-Metal Anodes after Cycling

Written by Emma Perry

By using cryogenic focused ion beam and ultrashort pulse laser ablation it has been possible to observe the cross section of an intact lithium battery for the first time. A lithium coin cell battery is comprised of lithium, a separator, copper, and a liquid electrolyte. A solid-electrolyte interphase forms on top of the lithium. The characterization can distinguish between these regions and has proven to be extremely advantageous since the whole battery is involved in the processes that ultimately limit the lifetime of the battery. It is now thought that the solid electrolyte interphase disfiguration of the separators provides a pathway for lithium plating through the separator gradually reducing the amount of lithium in the electrode.

The wide range in length scales from 1 mm to 500 nm is what makes this technique so special. Katherine Jungjohann recommends intact characterization for understanding electrochemical variations in battery performance and invites users to apply the facilities at Sandia National Laboratories.

Symposium F.SM08: Regenerative Engineering and Synthetic Biology

Christopher Chen, Boston University

Engineering Vasculature Using Physical and Structural Cues

Written by Jessalyn Low Hui Ying

The establishment of perfusable vascular networks in three-dimensional tissue constructs is critical for the viability of cells and tissues in tissue engineering. In this talk, Christopher Chen presents his research team’s work on how physical and structural cues can be used to engineering such vascular networks.

Chen first explains that using a lab-on-a-chip model consisting of a cylindrical channel lined with endothelium, different growth factors and angiogenic factors can be introduced. This allowed the researchers to understand angiogenesis sprouting needed to form a capillary bed. As expected, it was observed that the rate of angiogenesis sprouting increases with decreasing matrix stiffness. Interestingly, however, if stiffness is too low, cells are scattered and a vascular network cannot be formed, attributed to decreased myosin activity.

With this understanding, the researchers then studied the capillary bed that forms after sprouting is completed. For this, they took inspiration from vasculogenesis – the process of vascular network formation during early development, and built a vasculogenesis-on-a-chip model. When endothelial cells were scattered in the gel, they were able to form an interconnected network, but were not perfusable. Perfusion of this network occurred only upon the addition of stromal fibroblasts. Chen explains that the presence of these fibroblasts, however, may cause fibrosis. Therefore, to engineer the removal of stromal fibroblasts, the researchers took inspiration from synthetic biology to add a split caspase construct. Upon dimerization, the caspase cascade is activated and apoptosis of stromal fibroblasts occurs. It was shown that with this process, fibroblasts were greatly reduced, but network remained intact and perfusion could still occur.

Chen then moved on to explain how this knowledge can be translated to achieving better perfused vascular networks in vivo. While the introduction of proangiogenic factors drives vascular network formation, the capillary bed is dense and disorganized, leading to a lack of perfusion and clotting off. Therefore, the researchers designed a pre-patterned network so as to guide incoming vascular networks and provide more structure. They found that by implanting endothelial networks built in vitro, the implanted structure gets interconnected with host vasculature and can be perfused. In fact, studies showed that when implanted into the ischemic zone of the heart, anastomosis between vasculature of well-perfused and ischemic areas occurred. Heart function was increased, further showing the potential of using these vascular network constructs to guide tissue formation and improve outcomes of tissue-engineered implants.

F20MRS Meeting: Soft Electrically-Driven Actuators for Wearable Haptics

For me personally, the talks and live panels on virtual reality (VR) were the most interesting and engaging talks as it is wonderful to see how scientists are developing heptic devices that could bring stimulated sense of touch in a way that we could feel the texture and sense the virtual structures.

Why don’t we have haptic suits with thousands of individual actuators (taxels) when every smartphone display has millions of individually addressed pixels? To answer that, Dr. Shea from EPFL has tried to give us his perspective obout this field and the challenges ahead.

Dr. Shea addresses the challenges very delicately: generating localized forces on the human body in a comfortable and safe way is a major challenge for soft actuation: both fast motion and high forces are needed, yet the device must conform to the human body, and consume low power

Dr. Shea's lab has focused on electrostatic actuation, using high electric fields to deform elastomers or textile structures. They have developed a textile-based brakes, with a fine thickness of 1 mm , that can effectively block the motion of two sliding strips in a few milliseconds and control the joint motion. Using such a technology, users could manipulate virtual objects much better with more accuracy and feel deeper immersion. 

Their new fabrication method allows for high forces for use in full-body kinesthetic haptics by blocking shoulder and elbow motion to so that we could feel  for instance how heavy an object is to push and feel it's "weight". Thier method also generate normal and shear forces with high spatial resolution, that allows mimicking different feeling such as if something is about to slip out of our hands.

There is definitely much more to learn by watching Dr. Shea's talk on MRS meeting website using this link.

F20MRS Meeting: Towards Solid-State Batteries for Electric Vehicles

Dr. Doeff is a Senior Scientist and member of the Electrochemical Technologies Group (ECT) at Lawrence Berkeley National Laboratory. She is mainly working on sodium and lithium polymer batteries and more interestingly all-solid Li-ion batteries.

During this year's MRS meeting, Dr. Doeff has delivered a very informative talk about ceramic-based electrolytes and the challenges which exist for their design and application in vehicles. 

All-solid-state lithium batteries are advantageous against lithium-ion batteries as they could offer better energy density, safety, and reliability. The main problem with the current thin-film configurations is that their practical energy density is low and require expensive vacuum technologies to develop and scale.

Dr. Doeff and her coworkers at LBNL are developing a scalable freeze tape casting method to produce porous ceramic structures of LLZO (oxide-based solid electrolyte that is stable toward Li metal) to be used for all-solid-state lithium-ion batteries.

The microscopy work combined with synchrotron tomography that they have employed makes this talk very interesting and informative!

To watch this talk please use this link.

 

Engineering innate immune-mediated cancer cell killing by antibody recruiting macromolecules

F.SM07.04.11 Engineering innate immune-mediated cancer cell killing by antibody recruiting macromolecules

Annemiek Uvyn, Ghent University

Antibody therapy focuses on targeting antibodies onto the surface of cancer cells by innate immune mechanisms such as complement activation, antibody-dependent cell-mediated cytotoxicity, or antibody-dependent cellular phagocytosis to induce cancer cell killing. Monoclonal antibody therapy is limited in its high cost and side effects. And the research work lead by Annemiek Uvyn, from Ghent University, suggests that using synthetic systems that can recruit endogenous antibodies onto cancer cell surfaces can be a viable alternative for antibody therapy.

The research group works on developing antibody-recruiting polymers that can be used for cancer immunotherapy. These antibody recruiting polymers contain a target binding domain (to bind to the cell surface ) and an antibody binding domain (to bind to the antibody F-ab region). They can be injected directly into tumors to induce their attachment to cancer cell surfaces at one end and covalently attach the endogenous antibodies at the other. This binding would thus recruit immune cell-mediated cancer killing.

Interestingly, Annemiek says that a lipid anchor inserted into the phospholipid cell membrane is being used to covalently conjugate to the glycocalyx of metabolically azido-labeled cells. And azido-labelling becomes crucial to enhance the binding efficiency of antibody recruiting polymers (DBCO or DNP polymers) on to the cells. In vitro analysis of the polymers with cancers showed that a dialkyl group lipid polymer attached to cancer cells could high efficiently recruit anti-DNP into the cell surface. Eventually, the polymer conjugated cancer cell killing efficiency was visualized with macrophages to show phagocytosis is being activated with the lipid polymers. This approach of developing antibody-recruiting polymers can revolutionize monoclonal antibody cancer immunotherapy.

Fundamentals/Therapeutics: F.GI01.11: Live Keynote III

Fundamentals/Therapeutics: F.GI01.11: Live Keynote III

F.GI01.01.03 Membrane Based Affinity Capture to Quantify Antibodies to COVID-19

Merlin Bruening, University of Notre Dame

This live session talk is part of the Fundamentals/Therapeutics Live Keynote III. Prof Merlin Bruening, from the University of Notre Dame, and their group have devised a process to use membrane-based affinity to capture, elute, and quantify the concentration of COVID-19 specific antibodies. This technique could elucidate an easy way to calculate the amounts of antibodies against SARS-CoV2 in serum. 

The aim is to remove/elute antibody of interest specific to SARS-CoV2 from the mix of antibodies and proteins available in serum. To make this possible, the team uses nylon membrane and functionalizes them to capture/attract antibodies. The nylon membrane is functionalized with layer-by-layer deposition of polyelectrolytes like poly(acrylic acid) (PAA). Rinsing the membrane at low pH effects in carboxylic acid groups which can be used to then be modified with polyethyleneimine (PEI) polycations. Further after functionalization, a peptide mimotope can be added to the modified nylon which binds to specific protein regions. Preliminary data shows that when using Avastin/serum and eluting them using SDS/DTT, the resulting eluate contains pure Avastin captured and eluted. The next objective was to quantify the Avastin antibody. Avastin antibody quantitation was performed with spot blotting over PAA membrane and observing fluorescence with a secondary fluorescent-labeled antibody.

 

For calibration of the technique with COVID-19 antibodies, an anti-RBD protein is being functionalized with the membrane which showed a calibrated increase in the spot intensity of SARS-CoV2 monoclonal Antibodies. Data collected from fluorescence capturing of COVID antibodies would be helpful in analyzing if the patient has sufficient amounts of antibodies to have monoclonal antibody therapy. Further developments can yield in an efficient antibody detecting system!

 

 

 

 

 

 

 

 

Picture credit: Anal. Chem - Liu et al. Anal. Chem. 2018, 90, 20, 12161-12167

 

 

 

 

Following the third lecture in the session, a panel discussion was conducted. 

The panel consisted of, 

Elizabeth Wayne, Carnegie Mellon University

Kaitlyn Sadtler, National Institutes of Health

Jonathan Rivnay, Northwestern University

Merlin Bruening, University of Notre Dame

Susan Daniel, Cornell University 

Burak Ozdoganlar, Carnegie Mellon University

 

Merlin Bruening hopes that the research systems would get more opportunities and collaborations with companies that would aid in bringing out a clinical product from labs, such as quantitation of antibodies at a short time during a pandemic. Elizabeth from the panel Therapeutics section focuses on how the advances in diagnostics and therapy-based approaches to fulfill the therapeutic needs during the pandemic. 

Susan Daniel addresses suggesting that the structure-function relation is the key to figure out mechanisms to invent vaccines for new viruses like SARS-CoV2. Susan adds that viruses being non-alive particles, like small nanomachines to figure out how they work in the field. She urges on the shift of using the engineering part of nanodevices to cater the needs of viral detection engineering. Burak comments by stating that with the current lack of scalable manufacturing systems, many companies looking into using microneedle arrays to manage logistics and the pandemic need. But, difficulties in fabrication technology to cover costs and scalability makes them hard to get implemented into vaccines. 

Written by Arun Kumar. You can catch the session anytime through December 31^st! Follow us on Twitter for more updates: @Arun Kumar @Materials_MRS

Symposium F.GI01: Special Symposium on Materials Approaches for Tackling COVID-19

Panelists: Burak Ozdoganlar, Carnegie Mellon University; Susan Daniel, Cornell University; Merlin Bruening, University of Notre Dame

Live Panel Discussion III: Fundamentals/Therapeutics

Written by Jessalyn Low Hui Ying

Three panelists presented key research contributing to therapeutic strategies for fighting the ongoing COVID-19 pandemic. While in different areas, one unifying factor is that their materials research projects were done during this pandemic and notably builds on the prior body of knowledge and research done in their respective research groups. In the live panel discussion of this session, besides addressing keynote-specific questions, much insightful discussion was raised on how COVID-19 has influenced the way research is done and public perception of science.

One key recurring idea in this panel discussion is how fighting COVID-19 is a multidisciplinary problem that requires much interdisciplinary collaboration between clinicians, biologists, materials engineers, computer scientists, and many other specialists. This is especially so as to achieve engineering solutions in a quick amount of time like in the case of pandemics, as well as to drive conversations and seek inspiration on how one’s expertise can be leveraged for achieving solutions for COVID-19. For example, Burak Ozdoganlar shared how their lab has been developing their microneedle array technology prior to COVID-19, but not for the delivery of vaccines. After building a collaboration with the Center for Vaccine Research at the University of Pittsburgh, conversation was generated on how their microneedle array technology can be used to deliver live attenuated viruses, which started the transition into research work for COVID-19. Susan Daniel also mentions how biology exhibits a strong structural-functional relationship and raises the possibility of using artificial intelligence to establish such relationships instead of achieving them empirically.

However, it is not only such scientific and technical collaborations that are important. Merlin Bruening points out that to realize the potentials of translational research, collaboration with industry and companies is essential to commercializing technology developed in academia. This is especially so to bring out technology rapidly, given the timescale of COVID-19. To this end, session co-chair Kaitlyn Sadtler highlights the importance of science communication to explain discipline-specific work to people from other fields, which also ties into public trust in science.

In fact, this pandemic has brought about many opportunities. COVID-19 has shown how researchers can be creative and adapt their research for advancing knowledge and technology in this pandemic, such as in therapeutics, diagnostic tools, and personal protective equipment. More importantly, researchers have built the body of work essential for preparedness for future pandemics, should this happen. Research and implementation, however, is a long-drawn preposition, as Ozdoganlar points out. He notes that for this, sustained good amounts of funding is critical for researchers to continue progressing with this work even when the COVID-19 pandemic subsides, to deliver something that is clinically relevant.

The panel discussion also raised insights on how COVID-19 has influenced the public perception of science and demonstrated how science is important in managing this pandemic. Bruening raises the fact that it is basic science and the fundamental discoveries in the past 20 years or so that has led to many scientific advances today like in therapeutics for tackling COVID-19. Besides this, Daniel also highlights how COVID-19 has drawn importance to the need for managing public health, other than personalized medicine which has been a huge focus pre-COVID-19. This underlies the fact that people and communities are deeply interconnected, leading to session co-chair Elizabeth Wayne pointing out, too, the importance of sociocultural dynamics in fighting COVID-19.

Kaitlyn Sadtler of the National Institutes of Health and Elizabeth Wayne of Carnegie Mellon University co-chaired this session, which can be viewed online through December 31st. Following are reports on each panelist prior to the discussion.

Burak Ozdoganlar, Carnegie Mellon University

Microneedles Arrays for Effective and Efficient Mass Vaccinations

An effective vaccination strategy, especially in the wake of COVID-19, should involve a potent vaccine and an efficient delivery system. Traditional vaccine delivery approaches via intramuscular or subcutaneous routes have many disadvantages, in particular requiring high doses. The skin, however, has a robust immune network that can be leveraged for vaccine delivery. In this talk, Burak Ozdoganlar presents an intradermal delivery strategy using dissolvable microneedle arrays (MNAs) developed by his research group.

MNAs involve hundreds of microsized needles fabricated in a patch form, and for dissolvable MNAs, these needles are formed from a mixture of dissolvable sugar-based material and biocargo. The fabrication of dissolvable MNAs involves a diamond micromilling process to achieve precise geometries and with high reproducibility. Upon insertion into the skin, the MNAs dissolve and deliver the biocargo into the skin, a process which takes only 10-15 minutes. These dissolvable MNAs for intradermal delivery of biologics host many advantages over traditional techniques (Mantoux technique), including being dose-sparing, reproducible, and pain-free. In vivo and ex vivo studies demonstrated the successful delivery of siRNAs and adeno-associated virus (AAV) vectors using this technology. Ozdoganlar mentions that there are, however, certain drawbacks that may affect the scalability of using dissolvable MNAs for clinical vaccination, in particular sterilization, which could affect the viability of vaccines; regulation challenges, whereby new FDA approval must be attained for each vaccine; and interference of dissolvable materials with presentation of vaccines.  

Ozdoganlar therefore next presents in his talk a novel next-generation system – hybrid MNAs. Here, the microneedle tips remain dissolvable, but cannulas are non-dissolvable. Instead, these cannulas connect to a reservoir of vaccines which allow for the continued delivery of vaccines from the backside upon dissolution of the tips when inserted. Having the vaccines in a reservoir provides many advantages, including being able to deliver any type of vaccine like live attenuated viruses, co-delivery of adjuvants, and non-influence of sterilization on vaccine bioactivity. In short, these hybrid MNAs retain all advantages yet addresses problems of dissolvable MNAs. This brings about immense potential for achieving a scalable and effective vaccine delivery system for global immunization programs.

Susan Daniel, Cornell University

Insight from the Physical Sciences on Coronavirus Host Entry and Therapeutic Interventions

For coronaviruses (CoV), the fusion of the virus and host cell membrane is mediated by the spike protein (S). Particularly, the fusion peptide (FP) within S interacts with the host cell membrane and plays a key role for viral genome transfer. Therefore, if the FP interaction with host membrane is inhibited, it may bring about significant advances in developing therapies against coronaviruses such as SARS-CoV-2, as in the case of COVID-19. In this talk, Susan Daniel presents her research team’s work on understanding the impact of calcium binding on CoV infection.

Daniel explains in this talk that the idea behind this was observing how the FP sequence is highly conserved across different coronavirus types like SARS-CoV and SARS-CoV-2, and in this sequence, runs of charged residues are present, which led the researchers to hypothesize whether calcium ions (Ca²⁺), which are fusiogens in other cellular processes, interact with charged residues of FP. In fact, cell infectivity studies using SARS-CoV showed that infectivity increased with Ca²⁺. To gain physical insight into this mechanism, various biophysical studies were done. Results showed that Ca²⁺ promotes the structural organization and alpha-helix stability of FP, which increases FP membrane insertion and lipid ordering of the host membrane. This is a precursor for membrane fusion to occur, associated with increased infectivity. In fact, isothermal calorimetry studies showed that Ca²⁺ interact directly with FP and knockout studies show that the charged residues of FP are indeed critical for calcium binding and infection.

With such knowledge that Ca increases CoV infection, the researchers tested if calcium channel blockers, typically used for treating cardiac disorders, can similarly limit SARS-CoV-2 infection. In vitro studies showed that some did successfully limit infection. Daniel explains that more studies are still needed, but these preliminary results indicate the potential for repurposing calcium channel blockers for the treatment of COVID-19.  

Merlin Bruening, University of Notre Dame

Membrane Based Affinity Capture to Quantify Antibodies to COVID-19

Antibody detection and quantification are essential for the management of viruses, especially in the case of pandemics where many clinical and public health decisions need to be made. In this talk, Merlin Bruening presents a porous membrane system that can be used to quantify antibodies which can be used for COVID-19.  

Bruening first explains the working principle behind this. These membranes are functionalized through a layer-by-layer deposition function to deposit polyacrylic acid (PAA) which contains carboxyl (COOH) groups. These can then be used to immobilize affinity molecules and consequently capture the antibodies of interest when serum is passed through the membrane. After rinsing, the elute can then be quantified to determine the antibody concentration. This is because when the researchers used a peptide mimotope to bind the monoclonal antibody Avastin, the elute was pure and showed high specificity. Fluorescence quantification of eluted Avastin gave a linear calibration curve and showed high recovery of Avastin, which indicates that this membrane-based affinity capture technique can be used for rapid absolute quantification of antibodies.

Bruening also further presents two different membrane-based designs that leverage on the same principle, but with a simpler design for antibody quantification. The first design is achieved via spotting the affinity molecules at the center of the membrane, then passing through fluorescence-labeled secondary antibodies after first passing through the serum with antibodies. In this way, the antibody concentration, which is proportional to fluorescence signal, can be analyzed directly from the membrane without a need for elution. The second design he talked about also uses fluorescence-labeled secondary antibodies, but this time, the entire 96-well plate is modified with the membrane at the bottom. In this way, no membrane holder is needed.

Bruening ends his talk showing how this membrane system can be used for the detection of monoclonal antibodies against COVID-19. To this end, they immobilized SARS-CoV-2 receptor-binding domain (RBD) proteins via amide bonds to the membrane and results showed that the absolute concentration of SARS-CoV-2 monoclonal antibodies could be quantified from conjugated fluorescence-labeled secondary antibodies. These studies highlight how this membrane system can enable rapid antibody quantification, even at the µg to ng/mL level.   

For more MRS Meeting Scene coverage of materials approaches for attacking COVID-19, see:

Personal protective equipment in the lab

Vaccination without injection – microneedle array skin patch to the rescue!

The role of calcium ions in coronavirus infection

Screening and Management of COVID-19 with Paper-Based Nanoparticle Tests

Towards the Design of a Novel Antimicrobial/Antiviral Filtration System

Plenary Session Featuring The Fred Kavli Distinguished Lectureship in Materials Science

Darío Gil, IBM T. J. Watson Research Center
Scaling the Scientific Method to Enter the Era of Accelerated Materials Discovery

“Right now is the most exciting time in computing in probably the last 60 years,” said Darío Gil, director of research at IBM T. J. Watson Research Center, “where we are witnessing the convergence of different ways to represent and process information.”

Gil is referring to the convergence of bits, neurons, and qubits enabled by the “cloud” programming environment with the help of artificial intelligence (AI) that changes the way problems can be solved. It is ushering us into the era of accelerated discovery. This is particularly critical for addressing global problems such as the current pandemic and climate change. 

To put this in perspective, Gil said the discovery of a new material—from the design concept to commercialization—takes about a decade, using capital of USD$10 million to USD$100 million. IBM wants to cut this effort by 90 percent.

Gil said, “We envision in the future inserting this technology [of quantum computing] to work in tandem with the AI-enriched simulation step of materials discovery loop.”

As our society is getting more and more digitalized, materials discovery in the field of semiconductors needs to accelerate significantly. IBM is aware that all of the materials going into computer chips must be as sustainable as possible. Gil focused his talk on the R&D of photoresists. Photoresists are a light-sensitive material used for forming semiconductor patterning.

Currently, photoresists carry potential toxic risks, so the research community needs to search for new photoacid generators (PAG). Gil showed step-by-step the advantages of using, first, the deep search method, which can complete complex queries on a photoacid generator—38 million edges (connections between entities or nodes that hold information that can also hold information)—in 0.1 s. This process led researchers to a PAG that was used for other applications but never tested for extreme ultra-violet (EUV) lithography.

AI-enriched simulation was then used to augment the material dataset with predicted properties. Generative modeling—a new capability in AI—accepted the information on materials properties and design constraints and filled in the gaps by generating 1000 PAG cation candidates with targeted properties. The next step is autonomous chemical synthesis in order to reduce trial and error and increase reliability and achieve scalability. This is where Cloud-based AI-driven autonomous laboratories become useful and IBM was able to show, on November 19, 2020, the first PAG material formed through this process.

Quantum computing works in tandem with AI, offering another revolution in discovery acceleration. A classical computer can be used for solving easy problems. However, for hard problems such as simulating materials, classical computers can provide only an approximation. “But there’s another technology that alters the equation between what’s possible to solve and what will be possible to solve,” said Gil, “and that is the world of quantum computers.”

IBM uses superconducting qubits, and has made its quantum computing accessible worldwide from the Cloud. In a nutshell, researchers write their programs which they send to the quantum computer that converts the 0s and 1s into microwave pulses that travel to the quantum processor. “We perform superposition, entanglement, and interference operations to perform the computation,” Gil said, then send the information back. Gil said that over 360 billion quantum circuits have been executed by quantum computers to date over the past four years with over 260k users. 

The Kavli Foundation is dedicated to advancing science for the benefit of humanity, promoting public understanding of scientific research and supporting scientists and their work.

Symposium F.EN08: Scientific Basis for Nuclear Waste Management

Daniel Gregg, Australian Nuclear S&T Org

Hot isostatic pressing of Synroc-C - the effect of Ti-metal additions

Written by Emma Perry

Daniel Gregg began this live session with a touching tribute to a valued member of this symposia for a number of decades, Eric ‘Lou’ Vance,

‘Although he was a world renowned scientist and authority on the development of waste forms for nuclear waste, Lou kept a relatively low profile, mainly because of his humble and unassuming nature but Lou’s career was absolutely stellar’

(see on demand talk F.EN.08.01.01). Many talks in the symposia drew on Lou’s work studying iodine incorporation into waste forms. In this talk Daniel Gregg updates us with the latest progress regarding Synroc-C, a material Lou Vance pioneered and continued to work on until he died in March last year.

Synroc is a multiphase ceramic composite waste form containing perovskite, hollandite, zircolite, and rutile designed to immobilize highly active waste produced in reprocessing spent nuclear fuel. The synroc durability can be increases by increasing the reducing the conditions in fabrication. It was hypothesized that titanium could facilitate this by absorbing oxygen.

In these experiments an ordinary synroc waste form is compared to those containing 4% and 8% titanium metal. When there is no titanium, Cs₂MoO₄ is observed to crystallize and dissolve in leaching tests. When 8% is added zirconolite and hollandite destabilize. But 4% titanium appears to be just right. At this percentage, there is no longer an interaction between the cannister and the waste form and the durability is greatly improved.