In Today’s Science News we learn about a successful experiment regarding Moon soil, the newly taken photo of the black hole in our galaxy and, returning back to Earth, a technological development that allows for paper-thin loudspeakers (plus an article about ultrathin fuel cells which could have a significant impact on medical science).
Article 1: A first: Scientists grow plants in soil from the Moon
SD-Date: May 12th, 2022
Et-Date: May 13th, 2022
ScienceDaily Summary: „Scientists have, for the first time, grown plants in soil from the Moon. They used soil collected during the Apollo 11, 12 and 17 missions. In their experiment, the researchers wanted to know if plants would grow in lunar soil and, if so, how the plants would respond to the unfamiliar environment, even down to the level of gene expression.“
Method of Research
For this experiment, the researchers only had 12 gram of lunar soil. The soil was collected during the missions of Apollo 11 (July 16, 1969 – July 24, 1969), 12 (November 14, 1969 – November 24, 1969) and 17 (last lunar mission: December 7, 1972 – December 19, 1972).
Anna-Lisa Paul and Robert Ferl applied three times over the course of 11 years before being granted the loan by NASA.
Due to the very limited amount of Moon soil, the researchers had to carry out a small scale, carefully choreographed experiment. Thimble-sized wells in plastic plates, normally used for culturing cells, took on the functions of pots. These „pots“ were then filled with approximately one gram of lunar soil and enriched it with nutrient solutions. Lastly, a few seeds of Arabidopsis plant were added.
For those who do not what the Arabidopsis thaliana is: it is widely used in plant sciences, because its genetic code has been fully mapped. Moreover, it is easy to store and got a relatively small genome size. As the article of the NSF article explains it: „As a photosynthetic organism, Arabidopsis requires only light, air, water and a few minerals to complete its life cycle. It has a fast life cycle, produces numerous self progeny, has very limited space requirements, and is easily grown in a greenhouse or indoor growth chamber. It possesses a relatively small, genetically tractable genome that can be manipulated through genetic engineering more easily and rapidly than any other plant genome.“
This plant allowed the researchers to study the affects the soil has on plants down to the level of gene expression. The control group was placed in non-lunar soils (JSC-1A which mimics real lunar soil, simulated Martian soil and soils from extreme environments).
- Nearly all of the seeds sprouted
- Compared to the control group, the plants grew more slowly, were smaller or varied more in size than their counterparts
- On a genetic level, the plants perceived the lunar soil as a stressor
- There may be a link between where the soil was taken and how it affected the plants: plants grown in mature soil (lunar soil exposed to cosmic wind) experienced the most stress, whereas plants grown in „comparatively less mature soils“ performed better
Article 2: Astronomers reveal first image of the black hole
at the heart of our galaxy
SD-Date: May 12th, 2022
Et-Date: May 14th, 2022
ScienceDaily Summary: „Astronomers have unveiled the first image of the supermassive black hole at the center of our own Milky Way galaxy. This result provides overwhelming evidence that the object is indeed a black hole and yields valuable clues about the workings of such giants, which are thought to reside at the center of most galaxies.“
The image taken of the black hole in our galaxy was the result of the work of more than 300 researchers from 80 institutes around the world that make up the EHT (Event Horizon Telescope) collaboration. Several radio observatories were part of this Earth-wide telescope, amongst them the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder EXperiment (APEX) in the Atacama Desert in Chile, the IRAM 30-meter telescope in Spain, as well as the NOrthern Extended Millimeter Array (NOEMA) in France (since 2018). The data was combined by the supercomputer of the Max Planck Institute for Radio Astronomy in Germany. Furthermore, Europe also contributed to this project through funding granted by the European Research Council and the Max Planck Society in Germany.
Unlike the black hole Messier 87 (M87), the gas around Sagittarius A* (Sgr A*, pronounced „sadge-ay-star“) needs mere minutes to orbit around the black hole which means that the brightness and pattern of the gas changed rapidly. Consequently, it took longer to take a clear picture since new sophisticated tools had to be developed as well.
Sgr A* mass equals about 4 million suns and is 27,000 light years away from Earth.
Making of the Image
Now to the image itself and how it was made.
As explained above, the gas around Sagittarius A* needs only minutes to orbit which makes it difficult to get a clear picture. It also required an ‚Earth-wide‘ telescope, meaning that several radio observatories around the world were virtually connected to focus on said black hole. The main image you see above – and very likely saw in the news too – is the result of averaging together thousands of images through computational methods.
It retains features more commonly seen in the varied images, and suppresses infrequent features.
The bars you see in the small images beneath show the relative number of images belonging to each, with the first three containing thousands and the fourth only hundreds of images. The heights of the bars indicate the „weight“ each of these four images contributed to the main one above.
In case you need to refresh you knowledge on black holes, here a quick read (also from the website of NASA): „What Is a Black Hole?“ (August 21, 2018)
In short: only stars with a certain mass become black holes, when they collapse. Their collapse causes a supernova which blasts parts of the star into space (that’s also how heavier elements were created in the early universe which made life possible in the first place). Our sun, however, doesn’t have enough mass to do that. At the end of its life, in about 5 billion years, the sun will grow to a red giant and consume Mercury, Venus and possibly even Earth. In this state it resides for a billion years before becoming a white dwarf.
In case you want to know what the critical mass for a star is to turn into a black hole, here the answer from the National Radio Astronomy Observatory (NRAO):
„[…] Since the exact mass of an object like a star that must ultimately become a black hole is a function of its radius, there isn’t an exact mass above which that object must collapse to a black hole. Said another way, any object which collapses to the point where its radius is less than a certain limit must ultimately become a black hole. This radius is called the Schwarzschild radius (Rs), and it is given by the following equation:
Rs = 2MG/c^2
where M is the mass of the object, G is the gravitational constant, and c is the speed of light. If you plug in values for the constants G and c and use solar masses for M and km for Rs, this equation reduces to the following rather simple form:
Rs = 2.95*M(solar masses) km
So, for a star with the same mass as our Sun, the Schwarzschild radius is about 3 km, or about 2 miles. In general, stars with final masses in the range 2 to 3 solar masses are believed to ultimately collapse to a black hole.“ – answer by Jeff Mangum
Now that scientists got two black hole images, they can compare and contrast them to each other. The new data can be used to test theories and models of how gas behaves around supermassive black holes – a process that is not fully understood yet, but is thought to play a key role in shaping the formation and evolution of galaxies.
And this isn’t all either, to quote ScienceDaily: „Progress on the EHT continues: a major observation campaign in March 2022 included more telescopes than ever before. The ongoing expansion of the EHT network and significant technological upgrades will allow scientists to share even more impressive images as well as movies of black holes in the near future.“
Article 3: Researchers develop a paper-thin loudspeaker
SD-Date: April 26th, 2022
Et-Date: May 14th, 2022
ScienceDaily Summary: „Researchers created an ultrathin loudspeaker that can turn any rigid surface into a high-quality, active audio source. The fabrication process can enable the thin-film devices to be produced at scale.“
Loudspeakers that are usually found in headphones or other audio systems use electric current inputs that pass through a coil of wire that generates a magnetic field, which moves a speaker membrane, that moves the air above it, thus creating the sound we hear (see animation).
The newly developed loudspeakers have a simplified design by using a thin film of shaped piezoelectric material (piezo is greek for „push“, materials with this property can generate internal electrical charges from applied mechanical stress) that moves when voltage is applied over it, in turn it moves the air above it and generates sound.
Until now, the majority of thin-film speakers could only work when they were freestanding due to the film having to bend in order to produce sound. This problem was solved by letting only tiny domes vibrate individually on a thin layer of piezoelectric material instead of the entire material: „These domes, each only a few hair-widths across, are surrounded by spacer layers on the top and bottom of the film that protect them from the mounting surface while still enabling them to vibrate freely. The same spacer layers protect the domes from abrasion and impact during day-to-day handling, enhancing the loudspeaker’s durability.“
Building the Loudspeakers
The researchers used a thin sheet of PET – a type of light-weight plastic – and cut tiny holes in it with a laser. Then, the underside of the holed PET layer was laminated with a very thin film (~ 8 microns) of piezoelectric material called PVDF. A Vacuum was applied above the bonded sheets and a heat source, at 80 °C (176 °F), underneath them.
Because the PVDF layer was so thin, the pressure difference created by the vacuum and heat source caused it to bulge. In areas where it wasn’t blocked by the PET layer, domes started to protrude. Lastly, the researchers laminated the other side of the PVDF with another PET layer to act as a spacer between the domes and the bonding surface.
Once a roll-to-roll process has been integrated, „it could be fabricated in large amounts, like wallpaper to cover walls, cars, or aircraft interiors“ (Jinchi Han, co-author of the study).
In other words: it can produced on large scales.
Another benefit of this paper-thin loudspeaker is the simple fabrication process which also allows for domes with a larger radius which displace more air and produce more sound, however, they also have a lower resonance frequency (frequence at which a device operates most efficiently, a low resonance leads to audio distortion).
- Noise cancellation: generating sound of the same amplitude in a cockpit but in opposite phase; thus the two sounds cancel each other out.
- Immersive entertainment: providing three-dimensional audio in a theater or theme park ride.
- Ultrasound detection: using the sound like echolocation of a bat and locating a person in a room and how they move.
- Adding a reflective surface to create patterns of light -> for future display technologies.
Immersed in liquid, they could enable chemical processing techniques to use less energy.
Bonus: Ultrathin fuel cell uses the body’s own sugar to generate electricity
Techxplore Date: May 13th, 2022
Et Date: 14th May, 2022
Only a short overview over this interesting article I found, in bullet points.
- Inspiration for the new fuel cell came in 2016
- Not the first with the idea of a glucose fuel cell; back in the 1960s it was initially introduced but scrapped due to the appearence of lithium-iodide batteries which became the standard power source for medical implants, e.g. cardiac pacemaker
- Benefit of fuel cells is direct energy conversion, no energy needs to be stored
- There are three layers to it: a top anode, a middle electrolyte, and a bottom cathode
- The team looked for improvements of the materials and designs, due to polymer quickly degrading at high temperatures
- Glucose fuel cell with an electrolyte made from ceria (a ceramic material)
- 150 individual glucose cells were fabricated on a chip, about 400 nanometers thin and 300 micrometers wide (ca. the width of 30 human hair)
- The cells were patterned onto silicon wafers to show that they are compatible with semiconductor material
- 80 millivolts was the peak voltage of many cells, given their size it was the biggest power density of any existing glucose fuel cell design
Moreover, this new design withstands temperatures up to 600 °C and the sugary power source generates about 43 microwatts per square centimeter of electricity.
To end it with a quote of Jennifer L. M. Rupp: „Instead of using a battery, which can take up 90 percent of an implant’s volume, you could make a device with a thin film, and you’d have a power source with no volumetric footprint.“