The gas giants in the outer solar system are the homes to ring systems today, but almost half a billion years ago, our planet may have had a temporary ring, too.
For academic researchers, the cell format for testing lithium-ion batteries is often overlooked. However, choices in cell format and their design can affect cell performance more than one may expect. Coin cells that utilize either a lithium metal or greatly oversized graphite negative electrode are common but can provide unrealistic testing results when compared to commercial pouch-type cells. Instead, single-layer pouch cells provide a more similar format to those used in industry while not requiring large amounts of active material. Moreover, their assembly process allows for better positive/negative electrode alignment, allowing for assembly of single-layer pouch cells without negative electrode overhang. This talk presents a comparison between coin, single-layer pouch, and stacked pouch cells, and shows that single-layer pouch cells without negative electrode overhang perform best. Additionally, a careful study of the detrimental effects of excess electrode material is shown. The single-layer pouch cell format can also be used to measure pressure and volume in situ, something that is not possible in a coin cell. Last, a guide to assembling reproducible single-layer pouch cells without negative electrode overhang is presented.
An interactive Q&A session follows the presentation.
Matthew Garayt
Matthew D L Garayt is a PhD candidate in the Jeff Dahn, Michael Metzger, and Chongyin Yang Research Groups at Dalhousie University. His work focuses on materials for lithium- and sodium-ion batteries, with a focus on increased energy density and lifetime. Before this, he worked at E-One Moli Energy, the first rechargeable lithium battery company in the world, where he worked on high-power lithium-ion batteries, and completed a summer research term in the Obrovac Research Group, also at Dalhousie. He received a BSc (Hons) in applied physics from Simon Fraser University.
Osteosarcoma, the most common type of bone tumour, is a highly malignant cancer that mainly affects children and young adults. Patients are typically treated with an aggressive combination of resection and chemotherapy, but survival rates have not improved significantly since the 1970s. With alternative therapies urgently needed, a research team at Aston University has developed a gallium-doped bioactive glass that selectively kills over 99% of bone cancer cells.
The main objective of osteosarcoma treatment is to destroy the tumour and prevent recurrence. But over half of long-term survivors are left with bone mass deficits that can lead to fractures, making bone restoration another important goal. Bioactive glasses are already used to repair and regenerate bone – they bond with bone tissue and induce bone formation by releasing ions such as calcium, phosphorus and silicon. But they can also be designed to release therapeutic ions.
Team leader Richard Martin and colleagues propose that bioactive glasses doped with gallium ions could address both tasks – helping to prevent cancer recurrence and lowering the risk of fracture. They designed a novel biomaterial that provides targeted drug delivery to the tumour site, while also introducing a regenerative scaffold to stimulate the new bone growth.
“Gallium is a toxic ion that has been widely studied and is known to be effective for cancer therapy. Cancer cells tend to be more metabolically active and therefore uptake more nutrients and minerals to grow – and this includes the toxic gallium ions,” Martin explains. “Gallium is also known to inhibit bone resorption, which is important as bone cancer patients tend to have lower bone density and are more prone to fractures.”
Glass design
Starting with a silicate-based bioactive glass, the researchers fabricated six glasses doped with between 0 and 5 mol% of gallium oxide (Ga2O3). They then ground the glasses into powders with a particle size between 40 and 63 µm.
Martin notes that gallium is a good choice for incorporating into the glass, as it is effective in a variety of simple molecular forms. “Complex organic molecules would not survive the high processing temperatures required to make bioactive glasses, whereas gallium oxide can be incorporated relatively easily,” he says.
To test the cytotoxic effects of the bioactive glasses on cancer cells, the team created “conditioned media”, by incubating the gallium-doped glass particles in cell culture media at concentrations of 10 or 20 mg/mL. After 24 h, the particles were filtered out to leave various levels of gallium ions in the media.
The researchers then exposed osteosarcoma cells, as well as normal osteoblasts as controls, to conditioned media from the six gallium-doped powders. Cell viability assays revealed significant cytotoxicity in cancer cells exposed to the conditioned media, with a reduction in cell viability correlating with gallium concentration.
After 10 days, cancer cells exposed to media conditioned with 10 mg/mL of 4 and 5% gallium-doped glass showed decreased cell viability, to roughly 60% and less than 10%, respectively. The 20 mg/mL of 4% and 5% gallium-doped glass were the most toxic to the cancer cells, causing 60% and more than 99% cell death, respectively, after 10 days.
Exposure to gallium-free bioglass did not significantly impact cell viability – confirming that the toxicity is due to gallium and not the other components of the glass (calcium, sodium, phosphorus and silicate ions).
While the glasses preferentially killed osteosarcoma cells compared with normal osteoblasts, some cytotoxic effects were also seen in the control cells. Martin believes that this slight toxicity to normal healthy cells is within safe limits, noting that the localized nature of the treatment should significantly reduce side effects compared with orally administered gallium.
“Further experiments are needed to confirm the safety of these materials,” he says, “but our initial studies show that these gallium-doped bioactive glasses are not toxic in vivo and have no effects on major organs such as the liver or kidneys.”
The researchers also performed live/dead assays on the osteosarcoma and control cells. The results confirmed the highly cytotoxic effect of gallium-doped bioactive glass on the cancer cells with relatively minor toxicity towards normal cells. They also found that exposure to the gallium-doped glass significantly reduced cancer cell proliferation and migration.
Bone regeneration
To test whether the bioactive glasses could also help to heal bone, the team exposed glass samples to simulated body fluid for seven days. Under these physiological conditions, the glasses gradually released calcium and phosphorous ions.
FTIR and energy dispersive X-ray spectroscopy revealed that these ions precipitated onto the glass surface to form an amorphous calcium phosphate/hydroxyapatite layer – indicating the initial stages of bone regeneration. For clinical use, the glass particles could be mixed into a paste and injected into the void created during tumour surgery.
“This bioactivity will help generate new bone formation and prevent bone mass deficits and potential future fractures,” Martin and colleagues conclude. “The results when combined strongly suggest that gallium-doped bioactive glasses have great potential for osteosarcoma-related bone grafting applications.”
Next, the team plans to test the materials on a wide range of bone cancers to ensure the treatment is effective against different cancer types, as well as optimizing the dosage and delivery before undertaking preclinical tests.
RSV infects almost every child before they turn 2, and kills more than 100,000 infants worldwide each year. Machine learning and statistical models are identifying those most at risk.
Deep brain stimulation (DBS) is an established treatment for patients with Parkinson’s disease who experience disabling tremors and slowness of movements. But because the therapy is delivered with constant stimulation parameters – which are unresponsive to a patient’s activities or variations in symptom severity throughout the day – it can cause breakthrough symptoms and unwanted side effects.
In their latest Parkinson’s disease initiative, researchers led by Philip Starr from the UCSF Weill Institute for Neurosciences have developed an adaptive DBS (aDBS) technique that may offer a radical improvement. In a feasibility study with four patients, they demonstrated that this intelligent “brain pacemaker” can reduce bothersome side effects by 50%.
The self-adjusting aDBS, described in Nature Medicine, monitors a patient’s brain activity in real time and adjusts the level of stimulation to curtail symptoms as they arise. Generating calibrated pulses of electricity, the intelligent aDBS pacemaker provides less stimulation when Parkinson’s medication is active, to ward off excessive movements, and increases stimulation to prevent slowness and stiffness as the drugs wear off.
Starr and colleagues conducted a blinded, randomized feasibility trial to identify neural biomarkers of motor signs during active stimulation, and to compare the effects of aDBS with optimized constant DBS (cDBS) during normal, unrestricted daily life.
The team recruited four male patients with Parkinson’s disease, ranging in age from 47 to 68 years, for the study. Although all participants had implanted DBS devices, they were still experiencing symptom fluctuations that were not resolved by either medication or cDBS therapy. They were asked to identify the most bothersome residual symptom that they experienced.
To perform aDBS, the researchers developed an individualized data-driven pipeline for each participant, which turns the recorded subthalamic or cortical field potentials into personalized algorithms that auto-adjust the stimulation amplitudes to alleviate residual motor fluctuations. They used both in-clinic and at-home neural recordings to provide the data.
“The at-home data streaming step was important to ensure that biomarkers identified in idealized, investigator-controlled conditions in the clinic could function in naturalistic settings,” the researchers write.
The four participants received aDBS alongside their existing DBS therapy. The team compared the treatments by alternating between cDBS and aDBS every two to seven days, with a cumulative period of one month per condition.
The researchers monitored motor symptoms using wearable devices plus symptom diaries completed daily by the participants. They evaluated the most bothersome symptoms, in most cases bradykinesia (slowness of movements), as well as stimulation-associated side effects such as dyskinesia (involuntary movements). To control for other unwanted side effects, participants also rated other common motor symptoms, their quality of sleep, and non-motor symptoms such as depression, anxiety, apathy and impulsivity.
The study revealed that aDBS improved each participant’s most bothersome symptom by roughly 50%. Three patients also reported improved quality-of-life using aDBS. This change was so obvious to these three participants that, even though they did not know which treatment was being delivered at any time, they could often correctly guess when they were receiving aDBS.
The researchers note that the study establishes the methodology for performing future trials in larger groups of males and females with Parkinson’s disease.
“There are three key pathways for future research,” lead author Carina Oehrn tells Physics World. “First, simplifying and automating the setup of these systems is essential for broader clinical implementation. Future work by Starr and Simon Little at UCSF, and Lauren Hammer (now at the Hospital of the University of Pennsylvania) will focus on automating this process to increase access to the technology. From a practicality standpoint, we think it necessary to develop an AI-driven smart device that can identify and auto-set treatment settings with a patient-activated button.”
“Second, long-term monitoring for safety and sustained effectiveness is crucial,” Oehrn added. “Third, we need to expand these approaches to address non-motor symptoms in Parkinson’s disease, where treatment options are limited. I am studying aDBS for memory and mood in Parkinson’s at the University of California-Davis. Little is investigating aDBS for sleep disturbances and motivation.”
Halley’s Comet appears only once every 75 years, sparking excitement among both casual observers and astronomers. Learn what makes this celestial event so special.
The decay of dark matter could have played a crucial role in triggering the formation of supermassive black holes (SMBHs) in the early universe, according to a trio of astronomers in the US. Using a combination of gas-cloud simulations and theoretical dark matter calculations, Yifan Lu and colleagues at the University of California, Los Angeles, uncovered promising evidence that the decay of dark matter may have provided the radiation necessary to prevent primordial gas clouds from fragmenting as they collapsed.
SMBHs are thought to reside at the centres of most large galaxies, and can be hundreds of thousands to billions of times more massive than the Sun. For decades, astronomers puzzled over how such immense objects could have formed, and the mystery has deepened with recent observations by the James Webb Space Telescope (JWST).
Since 2023, JWST has detected SMBHs that existed less than one billion years after the birth of the universe. This is far too early to be the result of conventional stellar evolution, whereby smaller black holes coalesce to create a SMBH.
Fragmentation problem
An alternative explanation is that vast primordial gas clouds in the early universe collapsed directly into SMBHs. However, as Lu explains, this theory challenges our understanding of how matter behaves. “Detailed calculations show that, in the absence of any unusual radiation, the largest gas clouds tend to fragment and form a myriad of small halos, not a single supermassive black hole,” he says. “This is due to the formation of molecular hydrogen, which cools the rest of the gas by radiating away thermal energy.”
For SMBHs to form under these conditions, molecular hydrogen would have needed to be somehow suppressed, which would require an additional source of radiation from within these ancient clouds. Recent studies have proposed that this extra energy could have come from hypothetical dark-matter particles decaying into photons.
“This additional radiation could cause the dissociation of molecular hydrogen, preventing fragmentation of large gas clouds into smaller pieces,” Lu explains. “In this case, gravity forces the entire large cloud to collapse as a whole into a [SMBH].”
In several recent studies, researchers have used simulations and theoretical estimates to investigate this possibility. So far, however, most studies have either focused on the mechanics of collapsing gas clouds or on the emissions produced by decaying dark matter, with little overlap between the two.
Extra ingredient needed
“Computer simulations of clouds of gas that could directly collapse to black holes have been studied extensively by groups farther on the astrophysics side of things, and they had examined how additional sources of radiation are a necessary ingredient,” explains Lu’s colleague Zachary Picker.
“Simultaneously, people from the dark matter side had performed some theoretical estimations and found that it seemed unlikely that dark matter could be the source of this additional radiation,” adds Picker.
In their study, Lu, Picker, and Alexander Kusenko sought to bridge this gap by combining both approaches: simulating the collapse of a gas cloud when subjected to radiation produced by the decay of several different candidate dark-matter particles. As they predicted, some of these particles could indeed provide the missing radiation needed to dissociate molecular hydrogen, allowing the entire cloud to collapse into a single SMBH.
However, dark matter is a hypothetical substance that has never been detected directly. As a result, the trio acknowledges that there is currently no reliable way to verify their findings experimentally. For now, this means that their model will simply join a growing list of theories that aim to explain the formation of SMBHs. But if the situation changes in the future, the researchers hope their model could represent a significant step forward in understanding the early universe’s evolution.
“One day, hopefully in my lifetime, we’ll find out what the dark matter is, and then suddenly all of the papers written about that particular type will magically become ‘correct’,” Picker says. “All we can do until then is to keep trying new ideas and hope they uncover something interesting.”
Since its 2012 detection, the Higgs boson has fascinated researchers for its unique role in separating forces of nature. Find out how the "God" particle helps shape our universe.
A superconducting wire segment based on rare-earth barium copper oxide (REBCO) is the highest performing yet in terms of current density, carrying 190 MA/cm2 in the absence of any external magnetic field at a temperature of 4.2 K. At warmer temperatures of 20 K (which is the proposed application temperature for magnets used in commercial nuclear fusion reactors), the wires can still carry over 150 MA/cm2. These figures mean that the wire, despite being only 0.2 micron thick, can carry a current comparable to that of commercial superconducting wires that are almost 10 times thicker, according to its developers at the University at Buffalo in the US.
High-temperature superconducting (HTS) wires could be employed in a host of applications, including energy generation, storage and transmission, transportation, and in the defence and medical sectors. They might also be used in commercial nuclear fusion, offering the possibility of limitless clean energy. Indeed, if successful, this niche application could help address the world’s energy supply issues, says Amit Goyal of the University at Buffalo’s School of Engineering and Applied Science, who co-led this new study.
Record-breaking critical current density and pinning force
Before such large-scale applications see the light of day, however, the performance of HTS wires must be improved – and their cost reduced. Goyal and colleagues’ new HTS wire has the highest values of critical current density reported to date. This is particularly true at lower operating temperatures ranging from 4.2–30 K, which is of interest for the fusion application. While still extremely cold, these are much higher than the absolute zero temperatures that traditional superconductors function at, says Goyal.
And that is not all, the wires also have the highest pinning force (that is, the ability to hold magnetic vortices) ever reported for such wires: around 6.4 TN/m3 per cubic metre at 4.2 K and about 4.2 TN/m3 at 20 K, both under a 7 T applied magnetic field.
“Prior to this work, we did not know if such levels of critical current density and pinning were possible to achieve,” says Goyal.
The researchers made their wire using a technique called pulsed laser deposition. Here, a laser beam impinges on a target material and ablates material that is deposited as a film on the substrate, explains Goyal. “This technique is employed by a majority of HTS wire manufacturers. In our experiment, the high critical current density was made possible thanks to a combination of pinning effects from rare-earth doping, oxygen-point defects and insulating barium zirconate nanocolumns as well as optimization of deposition conditions.”
This is a very exciting time for the HTS field, he tells Physics World. “We have a very important niche large-scale application – commercial nuclear fusion. Indeed, one company, Commonwealth Fusion, has invested $1.8bn in series B funding. And within the last 5 years, almost 20 new companies have been founded around the world to commercialize this fusion technology.”
Goyal adds that his group’s work is just the beginning and that “significant performance enhancements are still possible”. “If HTS wire manufacturers work on optimizing the conditions under which the wires are deposited, they should be able to achieve a much higher critical current density, which will result in much better price/performance metric for the wires and enable applications. Not just in fusion, but all other large-scale applications as well.”
The researchers say they now want to further enhance the critical current density and pinning force of their 0.2 micron-thick wires. “We also want to demonstrate thicker films that can carry much higher current,” says Goyal.
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