M artin Kamen had worked for three days and three nights without sleep. The US chemist was finishing off a project in which he and a colleague, Sam Ruben, had bombarded a piece of graphite with subatomic particles. The aim of their work was to create new forms of carbon, ones that might have practical uses. Exhausted, Kamen staggered out of his laboratory at Berkeley in California, having finished off the project in the early hours of 27 February He desperately needed a break.
Natl Acad. USA Scanning reveals two view of the structure of a superlattice formed from layers that are each one atom thick.
Credit: L. McGilly et al. Take two carbon sheets, each only one atom thick. Stack them, then rotate them so that their crystal structures are slightly misaligned.
The bilayer contains tile-shaped regions where its two crystalline sheets are close to an energetically favourable alignment.
The new method not only reveals the tiles but shows, unexpectedly, that the electrons in the material move to the edges of the tiles. Nature Nanotechnol. Heart muscle artificially coloured. Stem cells embedded in a patch that sticks to the heart can form new muscle. Myocardial infarction, or heart attack, is a leading killer that permanently damages heart-muscle cells called cardiomyocytes.
Researchers are interested in repairing the damage using cardiomyocytes made in the laboratory from stem cells, but integrating such cells into the heart has proved challenging. Lijie Grace Zhang, at the George Washington University in Washington, DC, and her colleagues used 3D bioprinting to create patches of stretchable gel scaffolding that matched the curvature of the heart and could expand and contract as the heart beats.
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After being loaded with cardiomyocytes made from stem cells, these cardiac patches were placed onto the hearts of mice that had survived an experimental form of myocardial infarction. The patches had also stimulated heart-muscle formation, providing a potential avenue for therapies that repair heart damage.
Antarctic springtails picture one of the dominant land animals on the continent, eat algae and lichens - and, unwittingly, bits of plastic attached to their food. Plastic has found its way into a tiny animal in one of the most remote spots on the planet - an invasion that could degrade a food web already under threat from climate change. In Februaryresearchers on King George Island off the coast of Antarctica came across a large piece of polystyrene foam, which is used for home insulation, packaging and other purposes.
The foam was covered in moss, lichens, microscopic algae and one-millimetre-long six-legged creatures known as Antarctic springtails Cryptopygus antarcticus. C ryptopygus antarcticus forms part of simple but functional food webs in glacier-free areas and rocky coastal sites where penguins roost and seals gather.
Plastic waste might become a new danger in the already fragile ecosystems of Antarctica. Tissue from the hippocampus includes cell nuclei re glial cells green and neurofilaments blue.
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Roughly half of the neurons in this brain region form during adulthood. The hippocampus, a brain region involved in learning and memory, is known to include cells that arise during both infancy and adulthood. Now, experiments on rats have revealed key differences between those two classes of cell - differences that could endow the late-blooming cells with important capabilities.
In the s, the world tested a bunch of nuclear bombs, and today we're still carrying around the evidence-in our muscles. Here's how that works. Between an the use of atomic bombs. Aug 10, A chemist who had worked on the Manhattan Project to build the first atom bomb, Libby realised that when an organism dies, it will stop absorbing carbon, including carbon Oct 31, Unsurprisingly, the effects of the atom bomb tests in the s and 60s were felt all across the planet. The blasts doubled the amount of carbon isotopes in .
To study the hippocampal cells that arise during maturity, Jason Snyder at the University of British Columbia in Vancouver, Canada, and his colleagues injected the hippocampi of infant and adult rats with viruses that mark only newly created neurons. The researchers estimated that half of the neurons in the hippocampus are generated during adulthood.
Compared to neurons born in the hippocampi of baby rats, those that grew in the brains of adult animals had more thorny protrusions crowning the part of the cell that receives information from other neurons. Adult-born neurons also had a higher number of finger-like structures connecting them with neurons that send inhibitory signals to the brain.
These differences could confer advanced functions on adult-born neurons, including the ability to stimulate other brain cells involved in cognition, the researchers say. Julius Caesar pictured centre, with shield was assassinated in 44 BCwhich helped to set the stage for the rise of the Roman Empire. The eruption of an Alaskan volcano more than two millennia ago caused ruinous climate change - and might have spurred the rise of the Roman Empire.
Written accounts and environmental proxies from the time also document conditions such as severe cold in the Northern Hemisphere in 43 and 42 BC that could have contributed to the social unrest.
All contained layers high in sulfur that came from a 43 BC eruption. Precious commodities: shoppers in Bangkok stock up on toilet paper and kitchen roll. Theo Toppe at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and his colleagues surveyed people in 22 countries across North America and Europe about how they purchased and stored toilet paper. Participants also ranked the threat of COVID on a ten-point scale and took a test that rated them on several core personality traits.
Emotional people tended to worry most about the disease and thus tended to stockpile. Conscientiousness was also linked to stockpiling. The tallest droplets red-tipped are -1, nanometres high. Credit: Danqing Liu. Coatings that can secrete fluids on demand could keep themselves clean or administer medicines to a wound.
The fluid that serves as sweat is stored in numerous micrometre-sized pores surrounded by the long liquid-crystal molecules, which stand vertically on their ends. The coating rests on a layer of glass embedded with metallic electrodes that generate radio waves similar to those produced by a Wi-Fi router.
The coating sweats more as the radio waves become stronger. After the radio waves are switched off, the coating re-absorbs any sweat left on its surface in seconds.
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Matter Credit: Alamy. The ratio should be the same for other planets.
Nature Astron. The bomb pulse has also been used to estimate not validate the age of Greenland sharks by measuring the incorporation of 14 C in the eye lens during development. After having determined the age and measured the length of sharks born around the bomb pulse, it was possible to create a mathematical model in which length and age of the sharks were correlated in order to deduce the age of the larger sharks.
At the moment of death, carbon uptake is ended. Atmospheric bomb 14 C has been used to validate tree ring ages and to date recent trees that have no annual growth rings. From Wikipedia, the free encyclopedia. Sudden increase of carbon in the Earth's atmosphere due to nuclear bomb tests. Retrieved Bibcode : Natur.
Ancient Aliens: Ancient Atomic Blasts (Season 12, Episode 6) - History
Lawrence Livermore National Laboratory. Transactions of the American Fisheries Society.
Journal of Applied Ichthyology. Communications Biology. Canadian Journal of Fisheries and Aquatic Sciences. Marine and Freshwater Research.
Of more recent date was the overcompensating effect of man-made carbon injected into the atmosphere during nuclear bomb testing. The result was a rise in the atmospheric carbon level by more than 50 percent. Fortunately, neither effect has been significant in the case of older samples submitted for carbon dating. HOW CARBON CRACKS THE RIDDLE OF AGE. The carbon dating method is based on an ingeniously simple process. Cosmic rays bombard the upper atmosphere with tremendous energy. These rays produce great numbers of rapidly moving neutrons which collide with nitrogen atoms in the atmosphere. The bulk of these atoms are chemically transmuted into carbon In diamond, every carbon atom connects to four others in a 3D cubic lattice that is strong and hard. But in graphite, each atom bonds only to three others, forming flat sheets of hexagons.
Bibcode : Sci Categories : Nuclear weapons Nuclear weapons testing Radioactivity Molecular biology. There are two human activities recognized to have irreparably changed the global radiocarbon levels-the burning of fossil fuel and nuclear weapons testing.
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Burning of large quantities of fossil fuels like coal, referred as the Suess effect, had significantly lowered the radiocarbon concentration of the atmospheric carbon reservoir.
In contrast, nuclear weapons testing in the s and s dramatically increased the level of carbon 14 in the atmosphere. The phenomenon is often referred to as the bomb effect. Nuclear weapons testing brought about a reaction that simulated atmospheric production of carbon 14 in unnatural quantities.
Carbon, or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Its presence in organic materials is the basis of the radiocarbon dating method pioneered by Willard Libby and colleagues to date archaeological, geological and hydrogeological samples. Carbon was discovered on February 27, , by Martin Kamen and Sam Ruben at the . This bomb radiocarbon has been gradually removed from the atmosphere by by natural processes, but the "bomb spike" can be shown through the dating by means such as comparing the bottle date and radiocarbon age of wines. The surplus "bomb" radiocarbon is just one of the effects human have had on the ratio of 14 C to 12 C. During the industrial revolution ( - present) increasing . From Wikipedia, the free encyclopedia. The bomb pulse is the sudden increase of carbon (14 C) in the Earth's atmosphere due to the hundreds of aboveground nuclear bombs tests that started in and intensified between until , when the Limited Test Ban Treaty was signed by the United States, the Soviet Union and the United Kingdom. These hundreds of blasts were followed by a doubling of .
The huge thermal neutron flux produced by nuclear bombs reacted with nitrogen atoms present in the atmosphere to form carbon The carbon 14 produced is what is known as bomb carbon or artificial radiocarbon. According to literature, nuclear weapons testing in the s and s have nearly doubled the atmospheric carbon 14 content as measured in around The level of bomb carbon in the northern hemisphere reached a peak inand in the southern hemisphere around The change in global radiocarbon levels brought about by human activities necessitated the use of a reference standard for carbon 14 dating.
Radiocarbon dating needed an organic material that was not contaminated with carbon 14 from fossil fuel burning or nuclear weapons testing.
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Oxalic acid stocked by the U. National Bureau of Standards had been adopted as standard for radiocarbon dating.
Its radiocarbon content was theoretically the same as a wood sample grown in A the zero point of the radiocarbon timescale used in quoting carbon dating results.
Even after nuclear weapon testing was banned, the bomb effect still remains.