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  • Scientists Say: Valence electrons

    Scientists Say: Valence electrons

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    atom: The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and uncharged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.

    bond: (in chemistry) A semi-permanent attachment between atoms — or groups of atoms — in a molecule. It’s formed by an attractive force between the participating atoms. Once bonded, the atoms will work as a unit. To separate the component atoms, energy must be supplied to the molecule as heat or some other type of radiation.

    chemical: A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

    chlorine: A chemical element with the scientific symbol Cl. It is sometimes used to kill germs in water. Compounds that contain chlorine are called chlorides.

    electron: A negatively charged particle, usually found orbiting the outer regions of an atom; also, the carrier of electricity within solids.

    element: A building block of some larger structure. (in chemistry) Each of more than one hundred substances for which the smallest unit of each is a single atom. Examples include hydrogen, oxygen, carbon, lithium and uranium.

    neutron: A subatomic particle carrying no electric charge that is one of the basic pieces of matter. Neutrons belong to the family of particles known as hadrons.

    nucleus: Plural is nuclei. (in biology) A dense structure present in many cells. Typically a single rounded structure encased within a membrane, the nucleus contains the genetic information. (in astronomy) The rocky body of a comet, sometimes carrying a jacket of ice or frozen gases. (in physics) The central core of an atom, containing most of its mass.

    particle: A minute amount of something.

    proton: A subatomic particle that is one of the basic building blocks of the atoms that make up matter. Protons belong to the family of particles known as hadrons.

    salt: A compound made by combining an acid with a base (in a reaction that also creates water). The ocean contains many different salts — collectively called “sea salt.” Common table salt is a made of sodium and chlorine.

    sodium: A soft, silvery metallic element that will interact explosively when added to water. It is also a basic building block of table salt (a molecule of which consists of one atom of sodium and one atom of chlorine: NaCl). It is also found in sea salt.

    technology: The application of scientific knowledge for practical purposes, especially in industry — or the devices, processes and systems that result from those efforts.

    valence: (in chemistry and physics) The electrons of an atom that are involved in chemical bonding. Valence electrons usually are the outermost electrons (those orbiting farthest from the nucleus).

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  • Climate change: Something strange is happening in the Pacific and we must find out why

    Climate change: Something strange is happening in the Pacific and we must find out why

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    The Pacific “cold tongue”, an area of ocean that stretches West from Ecuador is cooler than expected

    Harvepino/shutterstock

    FOR years, climate models have predicted that as greenhouse gas emissions rise, ocean waters will warm. For the most part, they have been correct. Yet in a patch of the Pacific Ocean, the opposite is happening. Stretching west from the coast of Ecuador for thousands of kilometres lies a tentacle of water that has been cooling for the past 30 years. Why is this swathe of the eastern Pacific defying our predictions? Welcome to the mystery of the cold tongue.

    This isn’t just an academic puzzle. Pedro DiNezio at the University of Colorado Boulder calls it “the most important unanswered question in climate science”. The trouble is that not knowing why this cooling is happening means we also don’t know when it will stop, or whether it will suddenly flip over into warming. This has global implications. The future of the cold tongue could determine whether California is gripped by permanent drought or Australia by ever-deadlier wildfires. It influences the intensity of monsoon season in India and the chances of famine in the Horn of Africa. It could even alter the extent of climate change globally by tweaking how sensitive Earth’s atmosphere is to rising greenhouse gas emissions.

    Given all this, it isn’t surprising that climate scientists are trying to find out what is going on with increasing urgency. Like any good mystery, this is a tale of intrigue, confusion and competing theories. We haven’t quite…

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  • A single particle of light can kick off photosynthesis

    A single particle of light can kick off photosynthesis

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    algae: Single-celled organisms, once considered plants (they aren’t). As aquatic organisms, they grow in water. Like green plants, they depend on sunlight to make their food.

    bacteria: (singular: bacterium) Single-celled organisms. These dwell nearly everywhere on Earth, from the bottom of the sea to inside other living organisms (such as plants and animals). Bacteria are one of the three domains of life on Earth.

    chemical reaction: A process that involves the rearrangement of the molecules or structure of a substance, as opposed to a change in physical form (as from a solid to a gas).

    laser: A device that generates an intense beam of coherent light of a single color. Lasers are used in drilling and cutting, alignment and guidance, in data storage and in surgery.

    molecule: An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).

    particle: A minute amount of something.

    photon: A particle representing the smallest possible amount of light or other type of electromagnetic radiation.

    photosynthesis: (verb: photosynthesize) The process by which green plants and some other organisms use sunlight to produce foods from carbon dioxide and water.

    physicist: A scientist who studies the nature and properties of matter and energy.

    wavelength: The distance between one peak and the next in a series of waves, or the distance between one trough and the next. It’s also one of the “yardsticks” used to measure radiation. Visible light — which, like all electromagnetic radiation, travels in waves — includes wavelengths between about 380 nanometers (violet) and about 740 nanometers (red). Radiation with wavelengths shorter than visible light includes gamma rays, X-rays and ultraviolet light. Longer-wavelength radiation includes infrared light, microwaves and radio waves.

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  • How Benjamin Franklin fought money counterfeiters

    How Benjamin Franklin fought money counterfeiters

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    Though perhaps better known for its newspapers and almanacs, Benjamin Franklin’s printing business also churned out paper money to support the colonial economy. Now, scientists are confirming some of the ways that Franklin and his associates thwarted counterfeiters to help early American paper currency succeed, including by adding a reflective mineral to bills.

    Franklin’s bills “served as an archetype for printed money” to come, says Khachatur Manukyan, a physical chemist at the University of Notre Dame in Indiana. “It was very sophisticated for that time.”

    In past studies, Manukyan and his colleagues have analyzed ancient Roman coins, medieval manuscripts and other artifacts using nuclear imaging techniques. When the researchers realized that Notre Dame housed paper money bills dating to the early colonial days of North America, the team decided to take a closer look. They examined about 600 paper notes.

    By using techniques such as infrared, electron energy loss spectroscopy, and X-ray analysis, the researchers could see features such as colored threads and muscovite — a crystalized mineral — incorporated into the paper. The blue threads are visible to the naked eye, and the muscovite produces a glimmer that reflects light — features most knock-offs wouldn’t have been able to reproduce, the team reports July 17 in the Proceedings of the National Academy of Sciences.

    The muscovite, found in about 95 percent of the analyzed Franklin bills produced after 1754, was probably sourced from the same geologic area, the team says. The mineral was also probably used to increase the durability of the notes so they could hold up better during circulation.

    It’s wonderful that scientists are using these techniques to analyze these bills, says Jessica Linker, a historian at Northeastern University in Boston who studies early moneymaking. Still, she says, historians have known for some time from historical documents that muscovite — also known as mica — and blue threads were incorporated into old paper money to fight counterfeiting.

    What’s more, while Franklin contracted with the colonial governments to print money, others were involved in the decisions about its manufacture — not just Franklin, she says.

    Two photos of Benjamin Franklin’s incorporated elements like blue thread (left) and microscopic muscovite (right) in their paper money.
    Franklin’s operations incorporated elements like blue thread (left) and muscovite (microscope image, right) in their paper money in an effort to make it difficult to counterfeit.K. Manukyan et al/PNAS 2023

    The new analyses also showed that Franklin’s operations used graphite in their black ink. Other money printers of the time, including Paul Revere, generally used a type of black ink that had a higher proportion of chemicals that came from burnt bones like phosphorus and calcium. Counterfeiters had figured out how to fake the bone black ink, and some knock-off Franklin notes are distinguishable by the fact they use this bone black rather than graphite.

    Franklin’s operations may have used graphite to one-up the counterfeiters, the researchers say. But Franklin wasn’t the first printer to use graphite in ink, Linker says. Black lead — the historical term for graphite — is listed in some 18th century ink recipes, she says.

    “Even if it was unique to the money or new in the mid-Atlantic, it’s possibly not a Franklin innovation, but something he read about, experimented with and used to improve the quality of the ink generally,” she says — not necessarily something to fight counterfeiting.

    Still, the discovery of the graphite in Franklin’s notes is intriguing, she says. “I don’t think historians of colonial American printing would expect it to be there,” mostly because graphite was relatively scarce in the colonies at the time. Linker wonders whether this ink was used more broadly in Franklin’s other imprints or used exclusively for paper money.

    Efforts to thwart counterfeiters of early American money were eventually upended by the British, who figured out some of the techniques when they flooded their upstart colony with fake bills as a destabilizing tactic during the American Revolution. The value of American money tanked, and in the years following the revolution, the United States typically favored coins, only issuing treasury notes during later wars.

    Even so, some of Franklin’s techniques would go on to form the basis of increasingly sophisticated methods used to combat savvier forgers, Manukyan says. “The techniques utilized in producing pre-federal American currency were refined and enhanced during the 19th century whenever new bills were printed,” he says. “For that time, [Franklin’s paper money] was really groundbreaking.”


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  • Finding Inspiration for Sobriety

    reasons to stay sober

    Very rarely are there black and white answers to things. When I was an active drug addict, my perceptions were all backwards. The things that I thought were important, really weren’t. These days I like to think I have it a little more figured out, although I know there is a lot more room for growth. That is why the“12 Step” program, requires individuals to admit that they are powerless over their use before they can heal. Non-alcoholic beer can be a misleading name, as there are still trace amounts of alcohol in these drinks.

    How to Celebrate a Sobriety Anniversary

    • Schedule an exact time each day to internally check in.
    • Alcoholism strips people of their ability to be trusted, seeing as they will go to any lengths to continue supporting their habit.
    • Working a recovery program will instill the morals and principles that you never thought you could develop.
    • This newfound control can be a powerful motivator and source of sobriety inspiration to help you stay committed to your recovery.
    • This enables individuals to express themselves more effectively and establish stronger connections with others.
    • Many individuals in recovery find themselves facing a tsunami of feelings they’ve long suppressed or numbed.

    I have my family, I have my health, I have my dream girl, I have my dog who has been with me through all of this and still wags his tail when I walk in the door. The anxiety and tension that comes along with being an addict or alcoholic is hard to explain. If you are sitting you want to stand, if you are standing you want to sit. If you get to where your going, you find that you want to be be somewhere else. No matter how much I disagree with someone, I am able to stay open minded and put myself in their shoes. I have learned, through time and through self analysis, that the world is gray.

    Identify Your Personal Triggers

    It can range from getting sober for your health to getting sober for your family. As we said in the Army, “If it’s stupid but it works, it isn’t stupid.” That goes for addiction–it doesn’t matter why you get sober, only that you get and stay sober. Substance use, particularly alcohol and drugs, hijacks the brain’s natural reward system.

    • This means that over time, activities that initially seemed boring in early sobriety can become increasingly pleasurable.
    • Remember, the goal is to find activities that you genuinely enjoy and that support your recovery journey.
    • Yes, however, not all reengagements with alcohol and drug use are necessarily the same.

    Addressing Common Questions About Sobriety Anxiety

    Friendships play a crucial role in our happiness and well-being. Loneliness is a significant factor that can drive addiction, making it essential to cultivate and maintain meaningful friendships to support a lasting recovery. Surrounding yourself with supportive and understanding friends can provide the encouragement and accountability needed for sobriety inspiration. Thankfully, I am still very close with my friend and she wasn’t super upset about me missing her birthday, but I certainly was. I think that alcohol can sometimes make you a really flaky friend and a terrible partner.

    reasons to stay sober

    Not only that, but it also contributes to better physical appearance and weight management, helping you maintain a healthy body. Stress, anxiety, and depression often play significant roles in both the development of addiction and the challenges of maintaining sobriety. Many individuals use substances as a form of self-medication to cope with these mental health issues.

    Paying for Treatment

    reasons to stay sober

    In short, not drinking alcohol greatly contributes to happier, healthier organs and body systems. Taking care of your organs is one of the positive effects of sobriety. Your organs work hard to keep your body running smoothly. Drinking alcohol can stress or impair these functions, leading to organ damage. The good news is, quitting drinking, even if it’s for only a month, heroin addiction allows your body time to heal. Being sober greatly contributes to liver health and regeneration.

    reasons to stay sober

    Guilt is a sense of doing something wrong, whereas shame is the sense of being a bad person. When drinking or substance use gets out of one’s control, it can spiral downward at a rapid pace. The difference between casual drinking and drinking to cope with underlying issues is that the latter eventually gets out of one’s control, causing increasing harms as use escalates. Sobriety opens the door not only to personal healing, but to becoming a source of hope and support for those still struggling.

    reasons to stay sober

    • By choosing sobriety, individuals can break this pattern, allowing them to regain control over their emotions and mental well-being.
    • Whether it’s a hike or a nice park, heading into nature is a good way to watch the natural world moving and slow down your thinking.
    • One of the benefits is improved sleep patterns, leading to a reduction in instances of insomnia.
    • Sobriety isn’t just about quitting alcohol; it’s about gaining control of your life and rediscovering what it truly means to live fully.
    • Sobriety can actually lead to improved emotional regulation.
    • So whether you’re a skeptic, a believer, a data-driven engineer or artistic painter, a few of these tips should apply.

    Addiction often strains family bonds, leading to conflicts and misunderstandings. Being present and reliable for your family can bring immense joy and fulfillment. Your family deserves the best version of you, and sobriety can help you become reasons to stay sober that person. Okay, this one is kinda tough because I don’t know if I’ve necessarily saved money!

  • Test the effect of temperature on reaction time

    Test the effect of temperature on reaction time

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    amplitude: A measure of the height of a recurring wave in some signal, water or beam of radiation. In sound, wave amplitude corresponds with intensity — loudness or softness.

    angle: The space (usually measured in degrees) between two intersecting lines or surfaces at or close to the point where they meet.

    antacid: A medicine used to neutralize the acid in the stomach.

    app: Short for application, or a computer program designed for a specific task.

    aspirin: A common non-prescription drug, also known as acetylsalicylic acid. For more than a century, it has been widely used to treat headaches, joint pain, muscle pain, toothaches and more. It also reduces fevers and inflammation. Ancient papyrus texts indicate that as long as 5,000 years ago, the Sumerians and Egyptians were using willow bark (the source of aspirin’s active ingredient) to treat aches and pains.

    audio: Having to do with sound.

    average: (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.

    carbon: A chemical element that is the physical basis of all life on Earth. Carbon exists freely as graphite and diamond. It is an important part of coal, limestone and petroleum, and is capable of self-bonding, chemically, to form an enormous number of chemically, biologically and commercially important molecules.

    carbon dioxide: (or CO2) A colorless, odorless gas produced by all animals when the oxygen they inhale reacts with the carbon-rich foods that they’ve eaten. Carbon dioxide also is released when organic matter burns (including fossil fuels like oil or gas). Carbon dioxide acts as a greenhouse gas, trapping heat in Earth’s atmosphere. Plants convert carbon dioxide into oxygen during photosynthesis, the process they use to make their own food.

    constant: Continuous or uninterrupted. 

    data: Facts and/or statistics collected together for analysis but not necessarily organized in a way that gives them meaning. For digital information (the type stored by computers), those data typically are numbers stored in a binary code, portrayed as strings of zeros and ones.

    decibel: A measurement scale used for the intensity of sounds that can be picked up by the human ear. It starts at zero decibels (dB), a sound hardly audible to people with good hearing. A sound 10 times louder would be 10 dB. Because the scale is logarithmic, a sound 100 times louder than 0 dB would be 20 dB; one that’s 1,000 times louder than 0 dB would be described as 30 dB.

    degree: (in geometry) A unit of measurement for angles. Each degree equals one three-hundred-and-sixtieth of the circumference of a circle.

    dissolve: To turn a solid into a liquid and disperse it into that starting liquid. (For instance, sugar or salt crystals, which are solids, will dissolve into water. Now the crystals are gone and the solution is a fully dispersed mix of the liquid form of the sugar or salt in water.)

    equation: In mathematics, the statement that two quantities are equal. In geometry, equations are often used to determine the shape of a curve or surface.

    error: (In statistics) The non-deterministic (random) part of the relationship between two or more variables.

    error bar: A line (it can be vertical or horizontal) drawn through a point or a bar on a graph. The distance from one end of the line to the other represents how precise a measurement is, or how far the real value of something might fall from the data point reported in the experiment.

    factor: Something that plays a role in a particular condition or event; a contributor.

    function: The specific role some structure or device plays. (in math) A relationship between two or more variables in which one variable (the dependent one) is exactly determined by the value of the other variables.

    glass: A hard, brittle substance made from silica, a mineral found in sand. Glass usually is transparent and fairly inert (chemically nonreactive). Aquatic organisms called diatoms build their shells of it.

    hydrogen: The lightest element in the universe. As a gas, it is colorless, odorless and highly flammable. It’s an integral part of many fuels, fats and chemicals that make up living tissues. It’s made of a single proton (which serves as its nucleus) orbited by a single electron.

    ion: (adj. ionized) An atom or molecule with an electric charge due to the loss or gain of one or more electrons. An ionized gas, or plasma, is where all of the electrons have been separated from their parent atoms.

    kinetic energy: The energy held by an object due to its being in motion. The amount of this energy contained will depend on both the mass (usually weight) of the object and its speed.

    liquid: A material that flows freely but keeps a constant volume, like water or oil.

    molecule: An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).

    particle: A minute amount of something.

    plastic: Any of a series of materials that are easily deformable; or synthetic materials that have been made from polymers (long strings of some building-block molecule) that tend to be lightweight, inexpensive and resistant to degradation. (adj.) A material that is able to adapt by changing shape or possibly even changing its function.

    point: (in mathematics) A precise point in space that is so small that it has no size. It merely has an address.

    range: The full extent or distribution of something. For instance, a plant or animal’s range is the area over which it naturally exists. (in math or for measurements) The extent to which values can vary (such as the highest to lowest temperatures). Also, the distance within which something can be reached or perceived.

    right angle: A 90-degree angle, equivalent to any inside corner on a square.

    sensor: A device that picks up information on physical or chemical conditions — such as temperature, barometric pressure, salinity, humidity, pH, light intensity or radiation — and stores or broadcasts that information. Scientists and engineers often rely on sensors to inform them of conditions that may change over time or that exist far from where a researcher can measure them directly.

    smartphone: A cell (or mobile) phone that can perform a host of functions, including search for information on the internet.

    sodium: A soft, silvery metallic element that will interact explosively when added to water. It is also a basic building block of table salt (a molecule of which consists of one atom of sodium and one atom of chlorine: NaCl). It is also found in sea salt.

    sodium bicarbonate: Also known as baking soda, this white, chemical powder occurs naturally. Its formula is NaHCO 3 . It also has been used as a natural product to extinguish small electrical and grease fires. When ingested, it can help settle acid stomachs. Indeed, it is the main ingredient of many antacids sold in grocery stores.

    solid: Firm and stable in shape; not liquid or gaseous.

    solution: A liquid in which one chemical has been dissolved into another.

    standard deviation: (in statistics) The amount that each a set of data varies from the mean.

    tool: An object that a person or other animal makes or obtains and then uses to carry out some purpose such as reaching food, defending itself or grooming.

    vertical: A term for the direction of a line or plane that runs up and down, as the vertical post for a streetlight does. It’s the opposite of horizontal, which would run parallel to the ground.

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  • Ozempic, Wegovy and beyond: Could the next wave of weight-loss drugs end obesity?

    Ozempic, Wegovy and beyond: Could the next wave of weight-loss drugs end obesity?

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    New Scientist Default Image

    There are TikTok hashtags with millions of followers, endless column inches over celebrities’ waistlines and streams of media coverage when trial results come out. It is rare that a new medicine gets so much attention. Then again, it is even rarer that a licensed drug causes safe and rapid weight loss with minimal effort.

    A year ago, most people hadn’t heard of semaglutide, a drug developed to treat type 2 diabetes around a decade ago under the brand name Ozempic. Then, in 2021, it was approved in the US as a weight-loss aid under the name Wegovy. The medicine can cause people to lose a whopping 15 per cent of their body weight.

    The impact of this new class of medicines could be unprecedented – potentially bringing to an end the world’s growing obesity epidemic. “I don’t think it’s fully sunk in yet,” says Jonathan Campbell at Duke University in North Carolina, who investigates how these drugs affect the body.

    For one thing, Wegovy was just the start. The next generation of these drugs is in development and will be cheaper, easier to use and, crucially, even more potent. What’s more, emerging evidence suggests Wegovy and its ilk work better when given at a younger age, so doctors are exploring their use in teenagers and young children. This raises the prospect of switching from obesity treatment to prevention. “We have watched the obesity landscape change dramatically over the last 40 years,” says Campbell. “Now, maybe we’re at a turning point where that goes backwards.”

    Why obesity is on the rise

    The rise in obesity has been happening since about the 1970s…

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  • Tear-resistant rubbery materials could pave the way for tougher tires

    Tear-resistant rubbery materials could pave the way for tougher tires

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    A new material design could reduce pollution where the rubber meets the road.

    Strategically adding weak points along microscopic chains called polymers actually makes them harder to tear, researchers report in the June 23 Science. Because polymers are used in car tires, the findings could help reduce plastic pollution as tires wear down over time.

    When tires scrape against the road, they drop tiny particles of rubber and plastic polymers, which pollute waterways and contaminate the air (SN: 11/12/18). Every year, tires release an estimated 6 million metric tons of these microplastics into the environment. Stronger polymers that break apart less easily could limit the amount of particles shed annually.

    To make such tough materials, Stephen Craig, a chemist at Duke University, and colleagues added molecules called cross-linkers to the polymers. These cross-linkers connected jumbled-up polymer chains to their many neighbors, and they were specifically designed to break apart easily. At the microscopic scale, the polymers act like a tangle of spaghetti strands with the cross-linkers holding them all together and helping them retain their shape, says Craig’s collaborator Shu Wang, a chemist at MIT.

    [embed]https://www.youtube.com/watch?v=dmsznnE92w8[/embed]
    A rubbery plastic polymer with weak cross-linkers, shown on the left, requires more stretching force to tear than a similar polymer with stronger cross-linkers, shown on the right. Adding the weak cross-linkers to rubber could lead to tougher car tires.

    When the team stretched the polymer spaghetti, the individual cross-linkers broke easily, as expected. But the bulk material required more force to rip than they expected.

    The secret to the increased toughness lies in the path the tear has to take, Craig says. The tear propagates through the easy-to-break cross-linkers rather than through the tougher polymer strands. Each broken connection follows the path of least resistance but dodging the long polymer strands means breaking many cross-linkers, which requires more stretching force overall.

    This isn’t the first time researchers have used weak connectors to make polymers stronger. But unlike in similar materials, the increased toughness doesn’t come at the expense of other beneficial properties like stiffness.

    Craig says he hopes the findings will help extend the lifetimes of car tires and plastics, potentially limiting annual microplastic pollution.

    Skyler Ware

    Skyler Ware was the 2023 AAAS Mass Media Fellow with Science News. She is a fifth-year Ph.D. student at Caltech, where she studies chemical reactions that use or create electricity.


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  • How CRISPR therapy could cure everything from cancer to infertility

    How CRISPR therapy could cure everything from cancer to infertility

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    New Scientist Default Image

    THE bouts of terrible pain began further back than Victoria Gray can remember. Her grandmother would try to ease the discomfort with hot towels and medication, but it was fruitless. “I was born having to endure pain,” she says. “It was a life that I felt wasn’t worth living.”

    Gray has an inherited condition known as sickle cell disease, which causes red blood cells to form an abnormal “sickle” shape that can block capillaries, causing pain and sometimes organ damage. As Gray aged, her pain got worse. On one occasion, she temporarily lost the use of her arms and legs. By her 30s, Gray required in-home care. So, when she was offered the chance to become the first person to receive an experimental CRISPR gene-editing treatment, she took it.

    Today, four years after this took place, she no longer has episodes of pain and works full time. “Now my life is full of optimism,” she says.

    The treatment involved will probably be given the green light by regulators in the US, UK and Europe soon, which will make it the first CRISPR therapy to be approved. It won’t be the last.

    There is now no doubt that this technology – used to edit genes – can treat and potentially even cure a huge range of conditions. The only question is, just how far can it go? Will it be an expensive therapy used only occasionally? Or will it become so widely used that many of us will be getting a CRISPR jab to, say, lower our cholesterol levels and enable us to live longer, healthier lives?

    CRISPR gene editing exploded onto the…

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  • 1.6-billion-year-old steroid fossils hint at a lost world of microbial life

    1.6-billion-year-old steroid fossils hint at a lost world of microbial life

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    Molecular fossils found in ancient sedimentary rocks have unveiled a lost world of primitive eukaryotes that dominated aquatic ecosystems from at least 1.6 billion to 800 million years ago.

    The findings, published June 7 in Nature, come from laboratory analyses of rock samples from around the world that revealed remnants of primitive compounds called protosteroids. The majority of these molecules, which form in the process of creating steroids, were likely produced by primordial eukaryotes, relatively complex life-forms that today include animals, plants, algae and fungi, the researchers say. 

    Almost all eukaryotes produce molecules called steroids, like cholesterol, that are crucial components of cell membranes. Steroids don’t degrade easily and their remnants can be detected in sedimentary rocks as molecular fossils.

    The last common ancestor of all eukaryotes lived around 1.2 billion to more than 1.8 billion years ago. But scientists know almost nothing about the abundance, ecology and habitats of those early microorganisms. Molecular and physical fossils of eukaryotes dated to 800 million years ago have been found. But farther back in time, their physical fossils become scarce and molecular fossils of the steroids become undetectable. The existence of protosteroids had been predicted but it was unclear what they would look like — or if they could even be detected — until the researchers figured out a way to re-create those molecular footprints in the lab.

    “This study explains why we don’t see footprints of these guys in the rocks, as researchers were looking for the wrong thing,” says biologist Laura Katz, a biologist at Smith College in Northampton, Mass., who was not involved with the new work. “It fills a void in the fossil records.”

    A dearth of obvious eukaryote fossils before 800 million years ago led scientists to speculate that the ecosystem at that time was dominated by bacteria. Alternatively, primordial eukaryotes may have simply lacked strength in numbers to leave behind detectable steroid remnants. 

    Some scientists had a different explanation: What if some intermediate molecule in the chemical pathway that produces modern steroids was actually the end product of the process in primordial eukaryotes? This theory had been proposed by the biochemist Konrad Bloch, who won the Nobel Prize in physiology or medicine in 1964 for discovering the biosynthetic pathway of cholesterol.

    To test this, geochemist Jochen Brocks of the Australian National University in Canberra and colleagues artificially matured molecules made in the first few steps of steroid biosynthesis, including lanosterol and cycloartenol. That revealed what the compounds’ molecular fossils would look like. Then the researchers looked for these fossils in tarlike bitumens and oils extracted from ancient rocks from all over the world. 

    The researchers discovered a deluge of the protosteroids in samples ranging from deep to relatively shallow water environments. The oldest sample, dating back to 1.6 billion years ago, came from the Barney Creek Formation in Australia.

    “One of the greatest puzzles of early evolution is, why didn’t our highly capable eukaryotic ancestors come to dominate the world’s ancient waterways? Where were they hiding?” says Benjamin Nettersheim, a geobiologist at University of Bremen in Germany. “We show that the protosteroid-producing microorganisms were hiding in plain sight and were in fact abundant in the world’s ancient oceans and lakes all along.”

    While most bacteria produce a different molecule, called hopanoids, some bacteria also have the chemical tools to kick-start protosteroid production. But these bacteria exist in niche environments, such as methane seeps and hydrothermal vents. And their molecular footprints have not been found in sediments older than 800 million years, leading the researchers to conclude that eukaryotes dominated the ancient ecosystems.

    “Konrad Bloch would have been delighted, had he lived, to see this,” says MIT geobiologist Roger Summons, who wasn’t involved in the study. “This paper has elegantly confirmed his prediction that biosynthetic precursors to cholesterol reflect ancient life’s quest for improvement.” (Bloch died in 2000.)

    Making these steroid precursors requires less oxygen and energy, so that may have given the primordial eukaryotes an advantage in thriving in early Earth’s harsh low oxygen conditions, the researchers propose (SN: 10/30/15).

    “If true, [this study] suggests that we may be able to examine the stepwise evolution of eukaryotes at [an] unprecedented level of detail,” says evolutionary biologist Yosuke Hoshino of the GFZ German Research Centre for Geosciences in Potsdam, who was not involved in the study. “This is such a great opportunity to understand the evolution of complex life, which biologists have always dreamed of.”


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