Science

1283 Articles

Radio Emissions Over Sunspots Challenge Models Of Stellar Magnetism

December 1, 2023 by 1 Comment

Sustained radio emissions originating from high over a sunspot are getting researchers thinking in new directions. Unlike solar radio bursts — which typically last only minutes or hours — these have persisted for over a week. They resemble auroral radio emissions observed in planetary magnetospheres and some stars, but seeing them from about 40,000 km above a sunspot is something new. They don’t seem tied to solar flare activity, either.

The signals are thought to be the result of electron cyclotron maser (ECM) emissions, which involves how electrons act in converging geometries of magnetic fields. These prolonged emissions challenge existing models and ideas about how solar and stellar magnetic processes unfold, and understanding it better could lead to a re-evaluation of existing astrophysical models. Perhaps even leading to new insights into the behavior of magnetic fields and energetic particles.

This phenomenon was observed from our very own sun, but it has implications for better understanding distant stellar bodies. Speaking of our sun, did you know it is currently in it’s 25th Solar Cycle? Check out that link for a reminder of the things the awesome power of our local star is actually capable of under the right circumstances.

Crystal structure of Cr2Te3 thin films. (Credit: Hang Chi et al. 2023)

Chromium(III) Telluride As Ferromagnetic Material With Tunable Anomalous Hall Effect

November 29, 2023 by 7 Comments

Chromium(III) Telluride (Cr2Te3) is an interesting material for (ferro)magnetic applications, with Yao Wen and colleagues reporting in a 2020 Nano Letters paper that they confirmed it to show spontaneous magnetization at a thickness of less than fifty nanometers, at room temperature. Such a 2D ferromagnet could be very useful for spintronics and other applications. The confirmation of magnetization is performed using a variety of methods, including measuring the Hall Effect (HE) and the Anomalous Hall Effect (AHE), the latter of which is directly dependent on the magnetization of the material, rather than an externally applied field.

More recently, in a June 2023 article by Hang Chi and colleagues in Nature Communications, it is described how such epitaxially obtained Cr2Te3 films show a distinct change in the AHE (in the form of sign reversal) depending on the strain induced by the interface with the various types of substrates (Al2O3, SrTiO3) and the temperature, likely owing to the different thermal expansion rates of the film and substrate. Underlying this change in the observed AHE is the Berry phase and the related curvature. This is a phenomenon that was also noted by Quentin Guillet and colleagues in their 2023 article in Physical  Review Materials, effectively independently confirming the AHE

Using Cr2Te3 in combination with the appropriate substrate might ultimately lead to spintronics-based memory and other devices, even if such applications will still take considerable R&D.

Top image: Crystal structure of Cr2Te3 thin films. (Credit: Hang Chi et al. 2023)

CAR T Cell Immunotherapy And The Quiet Hope For A Universal Cancer Treatment

November 27, 2023 by 1 Comment

All of us have to deal with the looming threat of developing cancer during our lifetime, no matter how good our genetics are, or how healthy our lifestyle is. Despite major improvements to the way that we treat and even cure cases of cancer, the reality today is that not all types of cancer are treatable, in many cases there’s the likelihood that one day it will return even after full remission, and chemotherapy in particular comes with potential life-long health issues. Of the most promising new and upcoming treatments, immunotherapy, is decidedly among the most interesting.

With this approach, it is the body’s own immune system that is taught to attack those cancer cells, requiring little more than a few tweaks to T-cells harvested from the patient’s body, after which they’re sent on their merry cancer-killing way.  Yet as simple as this sounds, finding the right characteristics which identify the cancerous cells, and getting a solid and long-lasting immune response is a tough challenge. Despite highly promising results with immunotherapy treatment for non-solid cancers like leukemia – that have resulted in almost miraculous cures – translating this success to other cancer types has so far remained elusive.

New research now shows that changing some characteristics of these modified (chimeric antigen receptors, or CAR) T-cells may be key to making them significantly more long-lived and effective within a patient’s body. Is this the key to making immunotherapy possible for many more cancers?

Continue reading “CAR T Cell Immunotherapy And The Quiet Hope For A Universal Cancer Treatment” →

The Slow March Of Sodium-Ion Batteries To Compete With Lithium-Ion

November 26, 2023 by 56 Comments

The process of creating new battery chemistries that work better than existing types is a slow and arduous one. Not only does it know more failures than successes, it’s rare that a once successful type gets completely phased out, which is why today we’re using lead-acid, NiMH, alkaline, lithium, zinc-air, lithium-ion and a host of other battery types alongside each other. For one of the up-and-coming types in the form of sodium (Na)-based batteries the same struggles are true as it attempts to hit the right balance between anode, cathode and electrolyte properties. A pragmatic solution here involves Prussian Blue for the cathode and hard carbon for the anode, as is the case with Swedish Northvolt’s newly announced sodium-ion battery (SIB) which is sampling next year.

Commercialization of different SIB battery chemistries by various companies. (Credit: Yadav et al. 2022)
Commercialization of different SIB battery chemistries by various companies. (Credit: Yadav et al., 2022)

The story of SIBs goes back well over a decade, with a recent review article by Poonam Yadav and colleagues in Oxford Open Materials Science providing a good overview of the many types of anodes, cathodes and electrolytes which have been attempted and the results. One of the issues that prevents an SIB from directly using the carbon-based anodes employed with today’s lithium-ion batteries (LIB) is its much larger ionic radius that prevents intercalation without altering the carbon material to accept Na+ ions.

This is essentially where the hard carbon (HC) anode used by a number of SIB-producing companies comes into play, which has a far looser structure that does accept these ions and thus can be used with SIBs. The remaining challenges lie then with the electrolyte – which is where an organic form is the most successful – and the material for the sodium-containing cathode.

Although oxide forms and even sodium vanadium fluorophosphate (NVPF) are also being used, Prussian Blue analogs (PBAs) are attractive for being very low-cost and effective as cathode material once processed. An efficient way to process PB into fully sodiated and reduced Prussian White was demonstrated a few years ago, followed by successive studies backing up this assessment.

Although SIBs are seeing limited commercial use at this point, signs are that if it can be commercialized for the consumer market, it would have similar capacity as current LIBs, albeit with the potential to be cheaper, more durable and easier to recycle.

Harvard SETI Project Helps ID Mystery Sound

November 23, 2023 by 27 Comments

Last month, thousands of people in New Hampshire took to social media to report an explosion in the sky that was strong enough to rattle windows. Naturally aliens were blamed by some, while cooler heads theorized it may have been a sonic boom from a military aircraft. But without any evidence, who could say?

Luckily for concerned residents, this was precisely the sort of event Harvard’s Galileo Project was designed to investigate. Officially described as a way to search for “technological signatures of Extraterrestrial Technological Civilizations (ETCs)”, the project keeps a constant watch on the sky with a collection of cameras and microphones. With their gear, the team was able to back up the anecdotal reports with with hard data.

Continue reading “Harvard SETI Project Helps ID Mystery Sound” →

A giemsa stained blood smear from a person with beta thalassemia (Credit: Dr Graham Beards, Wikimedia Commons)

First CRISPR-Based Therapies For Sickle Cell Disease And Beta Thalassemia Approved In The UK

November 19, 2023 by 20 Comments

The gene-therapy-based treatment called Casgevy was recently approved in the UK, making it the first time that a treatment based on the CRISPR-Cas9 gene editing tool has been authorized for medical treatments. During the clinical trials, a number of patients were enrolled with either sickle cell disease (SCD) or β thalassemia, both of which are blood disorders that affect the production of healthy red blood cells. Of the 45 who enrolled for the SCD trial, 29 were evaluated in the initial 12-month efficacy assessment, with 28 of those found to be still free of the severe pain crises that characterizes SCD. For the β thalassemia trial, 42 patients were evaluated and 39 were still free of the need for red blood cell transfusions and iron chelation after the 12-month period, with the remaining three showing a marked reduction in the need for these.

Both of these blood disorders are inherited via recessive genes, meaning that in the case of SCD two abnormal copies of the β-globin (HBB) gene are required to trigger the disorder. For β thalassemia a person can be a carrier or have a variety of symptoms based on the nature of the two sets of mutated genes that involve the production of HbA (adult hemoglobin), with the severest form (β thalassemia major) requiring the patient to undergo regular transfusions. Both types of conditions have severe repercussions on overall health and longevity, with few individuals living to the age of 60.

The way that the Casgevy treatment works involves taking stem cells out of the bone marrow of the patient, after which the CRISPR-Cas9 tool is used to target the BCL11A gene and cut it out completely. This particular gene is instrumental in the switch from fetal γ globin (HBG1, HBG2) to adult β globin form. Effectively this modification causes the resulting cells to produce fetal-type hemoglobin (HbF) instead of adult HbA which would have the mutations involved in the blood disorder.

For the final step in the treatment, the modified stem cells have to be inserted back into the patient’s bone marrow, which requires another treatment to make the bone marrow susceptible to hosting the new cells. After this the patient will ideally be cured, as the stem cells produce new, HbF-producing cells that go on to create healthy hemoglobin. Although safety and costs (~US$2M per patient) considerations of such a CRISPR-Cas9 gene therapy may give pause, this has to be put against the prospect of 40-60 years of intensive symptom management.

Currently, the US FDA as well as the EU’s EMA are also looking at possibly approving the treatment, which might open the gates for similar gene-therapies.

Top image: A giemsa stained blood smear from a person with beta thalassemia. Note the lack of coloring. (Credit: Dr Graham Beards, Wikimedia Commons)

Fixing Astronomy In The Blink Of An Eye

November 19, 2023 by 37 Comments

If you’ve ever set a telescope up in your backyard, you probably learned how quick any kind of lighting ruins your observation. In fact, a recent study found that every year, about 10% of the stars that were visible the previous year disappear in the mishmash of light scattering through the atmosphere. A company called StealthTransit has a solution: blink the lights in a controlled way. They have an animated video explaining the concept.

The technology, named DarkSkyProtector, assumes there is LED lighting and that the light’s owner (or manufacturer) will put a simple device in line that causes the LED to blink imperceptibly. As you might guess, the telescope — presumably some giant observatory uses a GPS receiver to synchronize and then images only when the LED lights all turn off. That presumes, of course, that you have a significant number of lights under control.

It is hard to imagine every city and home having astronomy-safe lighting. However, we can imagine a university installing a lighting system on its campus to protect night viewing. The system underwent a test in the Caucasus mountains using a 24-inch telescope and was apparently quite successful with a shutter rate of about 150 Hz. We weren’t clear if each LED control module has to have a GPS-disciplined time source, but it seems like you’d have to. However, the post talks about how the bulbs wouldn’t cost more to make than conventional ones, so maybe they don’t have anything fancy in them.

You can see satellites in the day with some tech tricks. Want to check out observatories? Hit the road. Or, get time on a telescope with Skynet University.