Chemistry

Subterms

    Latest story

    150 Shares99 Views

    The development of quantum dots wins the 2023 Nobel prize in chemistry

    by

    Work on tiny dots that light up TV screens and help doctors see the blood vessels that feed tumors has earned three scientists the 2023 Nobel Prize in chemistry.  

    Chemist Moungi Bawendi, chemist Louis Brus and physicist Alexei Ekimov split the prize for the discovery and synthesis of quantum dots, the Royal Swedish Academy of Sciences announced October 4.

    Chemist Moungi Bawendi (left), chemist Louis Brus (middle) and physicist Alexei Ekimov (right) have split the 2023 Nobel Prize in chemistry for “the discovery and development of quantum dots, nanoparticles so tiny that their size determines their properties.”MIT, Columbia University, Nexdot

    “Quantum dots are a new class of materials, different from molecules,” said Heiner Linke, a member of the Nobel committee. Just adjusting the size of these nanoparticles, roughly a few billionths of a meter across, can change their properties — optical, electric, magnetic, even melting points — thanks to quantum mechanics (SN: 6/29/15). 

    That’s also true of color. “If you want to make different colors with molecules, you would choose a new molecule, a new set of atoms” arranged in a different structure, Linke said. But quantum dots of different colors have the exact same arrangement of atoms. The only difference is particle size.

    .email-conversion {
    border: 1px solid #ffcccb;
    color: white;
    margin-top: 50px;
    background-image: url(“/wp-content/themes/sciencenews/client/src/images/cta-module@2x.jpg”);
    padding: 20px;
    clear: both;
    }

    .zephr-registration-form{max-width:440px;margin:20px auto;padding:20px;background-color:#fff;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form *{box-sizing:border-box}.zephr-registration-form-text > *{color:var(–zephr-color-text-main)}.zephr-registration-form-relative-container{position:relative}.zephr-registration-form-flex-container{display:flex}.zephr-registration-form-input.svelte-blfh8x{display:block;width:100%;height:calc(var(–zephr-input-height) * 1px);padding-left:8px;font-size:16px;border:calc(var(–zephr-input-borderWidth) * 1px) solid var(–zephr-input-borderColor);border-radius:calc(var(–zephr-input-borderRadius) * 1px);transition:border-color 0.25s ease, box-shadow 0.25s ease;outline:0;color:var(–zephr-color-text-main);background-color:#fff;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-input.svelte-blfh8x::placeholder{color:var(–zephr-color-background-tinted)}.zephr-registration-form-input-checkbox.svelte-blfh8x{width:auto;height:auto;margin:8px 5px 0 0;float:left}.zephr-registration-form-input-radio.svelte-blfh8x{position:absolute;opacity:0;cursor:pointer;height:0;width:0}.zephr-registration-form-input-color[type=”color”].svelte-blfh8x{width:50px;padding:0;border-radius:50%}.zephr-registration-form-input-color[type=”color”].svelte-blfh8x::-webkit-color-swatch{border:none;border-radius:50%;padding:0}.zephr-registration-form-input-color[type=”color”].svelte-blfh8x::-webkit-color-swatch-wrapper{border:none;border-radius:50%;padding:0}.zephr-registration-form-input.disabled.svelte-blfh8x,.zephr-registration-form-input.disabled.svelte-blfh8x:hover{border:calc(var(–zephr-input-borderWidth) * 1px) solid var(–zephr-input-borderColor);background-color:var(–zephr-color-background-tinted)}.zephr-registration-form-input.error.svelte-blfh8x{border:1px solid var(–zephr-color-warning-main)}.zephr-registration-form-input-label.svelte-1ok5fdj.svelte-1ok5fdj{margin-top:10px;display:block;line-height:30px;font-size:12px;color:var(–zephr-color-text-tinted);font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-input-label.svelte-1ok5fdj span.svelte-1ok5fdj{display:block}.zephr-registration-form-button.svelte-17g75t9{height:calc(var(–zephr-button-height) * 1px);line-height:0;padding:0 20px;text-decoration:none;text-transform:capitalize;text-align:center;border-radius:calc(var(–zephr-button-borderRadius) * 1px);font-size:calc(var(–zephr-button-fontSize) * 1px);font-weight:normal;cursor:pointer;border-style:solid;border-width:calc(var(–zephr-button-borderWidth) * 1px);border-color:var(–zephr-color-action-tinted);transition:backdrop-filter 0.2s, background-color 0.2s;margin-top:20px;display:block;width:100%;background-color:var(–zephr-color-action-main);color:#fff;position:relative;overflow:hidden;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-button.svelte-17g75t9:hover{background-color:var(–zephr-color-action-tinted);border-color:var(–zephr-color-action-tinted)}.zephr-registration-form-button.svelte-17g75t9:disabled{background-color:var(–zephr-color-background-tinted);border-color:var(–zephr-color-background-tinted)}.zephr-registration-form-button.svelte-17g75t9:disabled:hover{background-color:var(–zephr-color-background-tinted);border-color:var(–zephr-color-background-tinted)}.zephr-registration-form-text.svelte-i1fi5{font-size:19px;text-align:center;margin:20px auto;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-divider-container.svelte-mk4m8o{display:flex;align-items:center;justify-content:center;margin:40px 0}.zephr-registration-form-divider-line.svelte-mk4m8o{height:1px;width:50%;margin:0 5px;background-color:var(–zephr-color-text-tinted);;}.zephr-registration-form-divider-text.svelte-mk4m8o{margin:0 12px;color:var(–zephr-color-text-main);font-size:14px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);white-space:nowrap}.zephr-registration-form-input-inner-text.svelte-lvlpcn{cursor:pointer;position:absolute;top:50%;transform:translateY(-50%);right:10px;color:var(–zephr-color-text-main);font-size:12px;font-weight:bold;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-response-message.svelte-179421u{text-align:center;padding:10px 30px;border-radius:5px;font-size:15px;margin-top:10px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-response-message-title.svelte-179421u{font-weight:bold;margin-bottom:10px}.zephr-registration-form-response-message-success.svelte-179421u{background-color:#baecbb;border:1px solid #00bc05}.zephr-registration-form-response-message-error.svelte-179421u{background-color:#fcdbec;border:1px solid #d90c00}.zephr-registration-form-social-sign-in.svelte-gp4ky7{align-items:center}.zephr-registration-form-social-sign-in-button.svelte-gp4ky7{height:55px;padding:0 15px;color:#000;background-color:#fff;box-shadow:0px 0px 5px rgba(0, 0, 0, 0.3);border-radius:10px;font-size:17px;display:flex;align-items:center;cursor:pointer;margin-top:20px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-social-sign-in-button.svelte-gp4ky7:hover{background-color:#fafafa}.zephr-registration-form-social-sign-in-icon.svelte-gp4ky7{display:flex;justify-content:center;margin-right:30px;width:25px}.zephr-form-link-message.svelte-rt4jae{margin:10px 0 10px 20px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-recaptcha-tcs.svelte-1wyy3bx{margin:20px 0 0 0;font-size:15px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-recaptcha-inline.svelte-1wyy3bx{margin:20px 0 0 0}.zephr-registration-form-progress-bar.svelte-8qyhcl{width:100%;border:0;border-radius:20px;margin-top:10px}.zephr-registration-form-progress-bar.svelte-8qyhcl::-webkit-progress-bar{background-color:var(–zephr-color-background-tinted);border:0;border-radius:20px}.zephr-registration-form-progress-bar.svelte-8qyhcl::-webkit-progress-value{background-color:var(–zephr-color-text-tinted);border:0;border-radius:20px}.zephr-registration-progress-bar-step.svelte-8qyhcl{margin:auto;color:var(–zephr-color-text-tinted);font-size:12px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-progress-bar-step.svelte-8qyhcl:first-child{margin-left:0}.zephr-registration-progress-bar-step.svelte-8qyhcl:last-child{margin-right:0}.zephr-registration-form-input-error-text.svelte-19a73pq{color:var(–zephr-color-warning-main);font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-input-select.svelte-19a73pq{display:block;appearance:auto;width:100%;height:calc(var(–zephr-input-height) * 1px);font-size:16px;border:calc(var(–zephr-input-borderWidth) * 1px) solid var(–zephr-color-text-main);border-radius:calc(var(–zephr-input-borderRadius) * 1px);transition:border-color 0.25s ease, box-shadow 0.25s ease;outline:0;color:var(–zephr-color-text-main);background-color:#fff;padding:10px}.zephr-registration-form-input-select.disabled.svelte-19a73pq{border:1px solid var(–zephr-color-background-tinted)}.zephr-registration-form-input-select.unselected.svelte-19a73pq{color:var(–zephr-color-background-tinted)}.zephr-registration-form-input-select.error.svelte-19a73pq{border-color:var(–zephr-color-warning-main)}.zephr-registration-form-input-textarea.svelte-19a73pq{background-color:#fff;border:1px solid #ddd;color:#222;font-size:14px;font-weight:300;padding:16px;width:100%}.zephr-registration-form-input-slider-output.svelte-19a73pq{margin:13px 0 0 10px}.zephr-registration-form-input-inner-text.svelte-lvlpcn{cursor:pointer;position:absolute;top:50%;transform:translateY(-50%);right:10px;color:var(–zephr-color-text-main);font-size:12px;font-weight:bold;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.spin.svelte-1cj2gr0{animation:svelte-1cj2gr0-spin 2s 0s infinite linear}.pulse.svelte-1cj2gr0{animation:svelte-1cj2gr0-spin 1s infinite steps(8)}@keyframes svelte-1cj2gr0-spin{0%{transform:rotate(0deg)}100%{transform:rotate(360deg)}}.zephr-registration-form-checkbox.svelte-1gzpw2y{position:absolute;opacity:0;cursor:pointer;height:0;width:0}.zephr-registration-form-checkbox-label.svelte-1gzpw2y{display:flex;align-items:center;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-checkmark.svelte-1gzpw2y{position:relative;box-sizing:border-box;height:23px;width:23px;background-color:#fff;border:1px solid var(–zephr-color-text-main);border-radius:6px;margin-right:12px;cursor:pointer}.zephr-registration-form-checkmark.checked.svelte-1gzpw2y{border-color:#009fe3}.zephr-registration-form-checkmark.checked.svelte-1gzpw2y:after{content:””;position:absolute;width:6px;height:13px;border:solid #009fe3;border-width:0 2px 2px 0;transform:rotate(45deg);top:3px;left:8px;box-sizing:border-box}.zephr-registration-form-checkmark.disabled.svelte-1gzpw2y{border:1px solid var(–zephr-color-background-tinted)}.zephr-registration-form-checkmark.disabled.checked.svelte-1gzpw2y:after{border:solid var(–zephr-color-background-tinted);border-width:0 2px 2px 0}.zephr-registration-form-checkmark.error.svelte-1gzpw2y{border:1px solid var(–zephr-color-warning-main)}.zephr-registration-form-input-radio.svelte-1qn5n0t{position:absolute;opacity:0;cursor:pointer;height:0;width:0}.zephr-registration-form-radio-label.svelte-1qn5n0t{display:flex;align-items:center;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-radio-dot.svelte-1qn5n0t{position:relative;box-sizing:border-box;height:23px;width:23px;background-color:#fff;border:1px solid #ebebeb;border-radius:50%;margin-right:12px}.checked.svelte-1qn5n0t{border-color:#009fe3}.checked.svelte-1qn5n0t:after{content:””;position:absolute;width:17px;height:17px;background:#009fe3;background:linear-gradient(#009fe3, #006cb5);border-radius:50%;top:2px;left:2px}.disabled.checked.svelte-1qn5n0t:after{background:var(–zephr-color-background-tinted)}.error.svelte-1qn5n0t{border:1px solid var(–zephr-color-warning-main)}.zephr-form-link.svelte-64wplc{margin:10px 0;color:#6ba5e9;text-decoration:underline;cursor:pointer;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-form-link-disabled.svelte-64wplc{color:var(–zephr-color-text-main);cursor:none;text-decoration:none}.zephr-registration-form-google-icon.svelte-1jnblvg{width:20px}.zephr-registration-form-password-progress.svelte-d1zv9r{display:flex;margin-top:10px}.zephr-registration-form-password-bar.svelte-d1zv9r{width:100%;height:4px;border-radius:2px}.zephr-registration-form-password-bar.svelte-d1zv9r:not(:first-child){margin-left:8px}.zephr-registration-form-password-requirements.svelte-d1zv9r{margin:20px 0;justify-content:center}.zephr-registration-form-password-requirement.svelte-d1zv9r{display:flex;align-items:center;color:var(–zephr-color-text-tinted);font-size:12px;height:20px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-password-requirement-icon.svelte-d1zv9r{margin-right:10px;font-size:15px}.zephr-registration-form-password-progress.svelte-d1zv9r{display:flex;margin-top:10px}.zephr-registration-form-password-bar.svelte-d1zv9r{width:100%;height:4px;border-radius:2px}.zephr-registration-form-password-bar.svelte-d1zv9r:not(:first-child){margin-left:8px}.zephr-registration-form-password-requirements.svelte-d1zv9r{margin:20px 0;justify-content:center}.zephr-registration-form-password-requirement.svelte-d1zv9r{display:flex;align-items:center;color:var(–zephr-color-text-tinted);font-size:12px;height:20px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-password-requirement-icon.svelte-d1zv9r{margin-right:10px;font-size:15px}
    .zephr-registration-form {
    max-width: 100%;
    background-image: url(/wp-content/themes/sciencenews/client/src/images/cta-module@2x.jpg);
    font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
    margin: 0px auto;
    margin-bottom: 4rem;
    padding: 20px;
    }

    .zephr-registration-form-text h6 {
    font-size: 0.8rem;
    }

    .zephr-registration-form h4 {
    font-size: 3rem;
    }

    .zephr-registration-form h4 {
    font-size: 1.5rem;
    }

    .zephr-registration-form-button.svelte-17g75t9:hover {
    background-color: #fc6a65;
    border-color: #fc6a65;
    width: 150px;
    margin-left: auto;
    margin-right: auto;
    }
    .zephr-registration-form-button.svelte-17g75t9:disabled {
    background-color: #e04821;
    border-color: #e04821;
    width: 150px;
    margin-left: auto;
    margin-right: auto;
    }
    .zephr-registration-form-button.svelte-17g75t9 {
    background-color: #e04821;
    border-color: #e04821;
    width: 150px;
    margin-left: auto;
    margin-right: auto;
    }
    .zephr-registration-form-text > * {
    color: #FFFFFF;
    font-weight: bold
    font: 25px;
    }
    .zephr-registration-form-progress-bar.svelte-8qyhcl {
    width: 100%;
    border: 0;
    border-radius: 20px;
    margin-top: 10px;
    display: none;
    }
    .zephr-registration-form-response-message-title.svelte-179421u {
    font-weight: bold;
    margin-bottom: 10px;
    display: none;
    }
    .zephr-registration-form-response-message-success.svelte-179421u {
    background-color: #8db869;
    border: 1px solid #8db869;
    color: white;
    margin-top: -0.2rem;
    }
    .zephr-registration-form-text.svelte-i1fi5:nth-child(1){
    font-size: 18px;
    text-align: center;
    margin: 20px auto;
    font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
    color: white;
    }
    .zephr-registration-form-text.svelte-i1fi5:nth-child(5){
    font-size: 18px;
    text-align: left;
    margin: 20px auto;
    font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
    color: white;
    }
    .zephr-registration-form-text.svelte-i1fi5:nth-child(7){
    font-size: 18px;
    text-align: left;
    margin: 20px auto;
    font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
    color: white;
    }
    .zephr-registration-form-text.svelte-i1fi5:nth-child(9){
    font-size: 18px;
    text-align: left;
    margin: 20px auto;
    font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
    color: white;
    }
    .zephr-registration-form-input-label.svelte-1ok5fdj span.svelte-1ok5fdj {
    display: none;
    color: white;
    }
    .zephr-registration-form-input.disabled.svelte-blfh8x, .zephr-registration-form-input.disabled.svelte-blfh8x:hover {
    border: calc(var(–zephr-input-borderWidth) * 1px) solid var(–zephr-input-borderColor);
    background-color: white;
    }
    .zephr-registration-form-checkbox-label.svelte-1gzpw2y {
    display: flex;
    align-items: center;
    font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
    color: white;
    font-size: 20px;
    margin-bottom: -20px;
    }

    When quantum dots are irradiated by light, electrons within get energized, eventually releasing that energy as fluorescent light. The smaller the dots are, the more they compress the wave function of an electron, increasing its energy so that the dot appears blue. Larger dots appear red. 

    Dots of the same size made from different materials may also emit slightly different wavelengths of light, says Jean-Marc Pecourt, a chemist at CAS, a division of the American Chemical Society. Quantum dots are usually made from semiconductor materials, such as graphene, selenite or metal sulfides, Pecourt says. So by adjusting materials or the size of quantum dots, chemists can alter their properties for a wide variety of uses.

    The idea that the size of these nanoparticles could alter their properties was predicted nearly a century ago, but at the time it seemed impossible to reproduce that effect in the real world. To do that, researchers would need a perfectly crystalline material, and would need to control the size of the nanomaterial very precisely, sculpting it atom layer by atom layer.  

    Then, in the early 1980s, Ekimov and Brus independently showed that it could be done. Ekimov, now at Nanocrystals Technology, Inc., in Briarcliff Manor, N.Y., demonstrated this in glass, adding copper chloride to produce tiny crystals and revealing that the color of the glass was linked to the size of those crystals. Brus, of Columbia University, made a similar discovery, but in a different context: He demonstrated the link between size and color for nanoparticles floating freely in a solution and in gaseous compounds (SN: 10/3/92). 

    Those discoveries triggered intense interest in how to harness these little dots for a variety of applications. But manufacturing them would require being able to control the size of the particles to precise specifications. 

    A decade later, Bawendi, of MIT, developed a method to precisely control the speed of the crystals’ growth in a solution, figuring out how to stop them right when they reach a desired size. He did this by first injecting chemical reagents into the solution that instantaneously formed the tiny crystals and then promptly adjusting the temperature of the solution, halting their growth. 

    “I’m deeply honored and surprised and shocked by the announcement this morning,” Bawendi said October 4 during an MIT news conference. “I’m especially honored to share this with Lou Brus, who was my postdoctoral mentor [from] whom I learned so much. I tried to emulate his scholarship and his mentoring style as a professor myself when I came to MIT.” 

    Bawendi started working on quantum dots after he met Brus at Nokia Bell Labs, headquartered in Murray Hill, N.J. The researchers needed high quality quantum dots to study the physics of the nanoparticles, Bawendi said. “It wasn’t because I wanted to make the best quantum dots possible for application, it was because we needed to make the best possible quantum dots to study them.” It took years of trial and error to work out the method, he said.

    By making it possible to manufacture quantum dots, Bawendi’s method opened up a world of possible uses for the nanoparticles. Quantum dots make it possible to very precisely change the color of LED lights and dramatically improve their efficiency. Dots that glow with fluorescent light, injected into the body and attached to immune cells that swarm to cancerous tissues, can help surgeons distinguish even hard-to-see tumors (SN: 8/3/04). The ability to be tuned to absorb different wavelengths of light could also allow the manufacture of customized solar cells that are highly efficient in different light conditions. The dots might also be used to build quantum computers, Pecourt says (SN: 2/14/18). 

    Biomedical engineer and chemist Warren Chan says the prize is well deserved. “They’re the ones who built the foundation,” says Chan, of the University of Toronto. “I’m really happy that the field is getting credit for really changing the world, not just in quantum dots, but in a lot of different areas.” 

    .subscribe-cta {
    color: black;
    margin-top: 0px;
    background-image: url(“”);
    background-size: cover;
    padding: 20px;
    border: 1px solid #ffcccb;
    border-top: 5px solid #e04821;
    clear: both;
    }

    Subscribe to Science News

    Get great science journalism, from the most trusted source, delivered to your doorstep.

    One of the first applications came in the late 1990s when Chan and colleagues used quantum dots to tag cells in the lab, he says. “The surface modifications that were used for integrating quantum dots for applications were then also adapted for other types of nanoparticles.”

    The Nobel committee looks not only at past contributions, but also the effect a discovery may have on the future, Chan says. The ability to tune nanoparticles by changing their size or surface properties could open a wide variety of possibilities that have not yet been explored. Chan and colleagues are now using quantum dots to detect infectious diseases, including HIV, influenza and hepatitis B.

    “I was absolutely thrilled to see this,” says Judith Giordan, president of the American Chemical Society. “We have three people recognized who brought this technology from a dream, a hope, a theoretical construct … all the way through synthesis and manufacture.”

    Earlier this week, the development of mRNA vaccines — widely speculated as a candidate for the 2023 chemistry Nobel Prize — received the Nobel in medicine or physiology instead (SN: 10/2/23). 

    “Sometimes chemistry gets a bad rap,” Giordan says. “But here are two magnificent examples of how chemistry has solved problems in the world.”

    The three winners will share the prize of 11 million Swedish kronor, or about $1 million. More

    More stories

    • 113 Shares129 Views

      in Physics

      Chemists turned plastic waste into tiny bars of soap

      by

      Luis Melecio-Zambrano is the summer 2023 science writing intern at Science News. They are finishing their master’s degree in science communication from the University of California, Santa Cruz, where they have reported on issues of environmental justice and agriculture. More

    • 100 Shares99 Views

      in Heart

      Magnetic ‘rusty’ nanoparticles pull estrogen out of water

      by

      A new “smart rust” could one day help pull pollutants out of waterways, leaving cleaner water behind.

      Researchers adorned tiny particles of iron oxide, better known as rust, with “sticky” molecules that grab on to estrogen and similar hormones in water samples. A magnet can then remove both the particles and the trapped pollutants from the water, materials scientist Lukas Müller reports August 16 in San Francisco at a meeting of the American Chemical Society.

      .email-conversion {
      border: 1px solid #ffcccb;
      color: white;
      margin-top: 50px;
      background-image: url(“/wp-content/themes/sciencenews/client/src/images/cta-module@2x.jpg”);
      padding: 20px;
      clear: both;
      }

      .zephr-registration-form{max-width:440px;margin:20px auto;padding:20px;background-color:#fff;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form *{box-sizing:border-box}.zephr-registration-form-text > *{color:var(–zephr-color-text-main)}.zephr-registration-form-relative-container{position:relative}.zephr-registration-form-flex-container{display:flex}.zephr-registration-form-input.svelte-blfh8x{display:block;width:100%;height:calc(var(–zephr-input-height) * 1px);padding-left:8px;font-size:16px;border:calc(var(–zephr-input-borderWidth) * 1px) solid var(–zephr-input-borderColor);border-radius:calc(var(–zephr-input-borderRadius) * 1px);transition:border-color 0.25s ease, box-shadow 0.25s ease;outline:0;color:var(–zephr-color-text-main);background-color:#fff;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-input.svelte-blfh8x::placeholder{color:var(–zephr-color-background-tinted)}.zephr-registration-form-input-checkbox.svelte-blfh8x{width:auto;height:auto;margin:8px 5px 0 0;float:left}.zephr-registration-form-input-radio.svelte-blfh8x{position:absolute;opacity:0;cursor:pointer;height:0;width:0}.zephr-registration-form-input-color[type=”color”].svelte-blfh8x{width:50px;padding:0;border-radius:50%}.zephr-registration-form-input-color[type=”color”].svelte-blfh8x::-webkit-color-swatch{border:none;border-radius:50%;padding:0}.zephr-registration-form-input-color[type=”color”].svelte-blfh8x::-webkit-color-swatch-wrapper{border:none;border-radius:50%;padding:0}.zephr-registration-form-input.disabled.svelte-blfh8x,.zephr-registration-form-input.disabled.svelte-blfh8x:hover{border:calc(var(–zephr-input-borderWidth) * 1px) solid var(–zephr-input-borderColor);background-color:var(–zephr-color-background-tinted)}.zephr-registration-form-input.error.svelte-blfh8x{border:1px solid var(–zephr-color-warning-main)}.zephr-registration-form-input-label.svelte-1ok5fdj.svelte-1ok5fdj{margin-top:10px;display:block;line-height:30px;font-size:12px;color:var(–zephr-color-text-tinted);font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-input-label.svelte-1ok5fdj span.svelte-1ok5fdj{display:block}.zephr-registration-form-button.svelte-17g75t9{height:calc(var(–zephr-button-height) * 1px);line-height:0;padding:0 20px;text-decoration:none;text-transform:capitalize;text-align:center;border-radius:calc(var(–zephr-button-borderRadius) * 1px);font-size:calc(var(–zephr-button-fontSize) * 1px);font-weight:normal;cursor:pointer;border-style:solid;border-width:calc(var(–zephr-button-borderWidth) * 1px);border-color:var(–zephr-color-action-tinted);transition:backdrop-filter 0.2s, background-color 0.2s;margin-top:20px;display:block;width:100%;background-color:var(–zephr-color-action-main);color:#fff;position:relative;overflow:hidden;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-button.svelte-17g75t9:hover{background-color:var(–zephr-color-action-tinted);border-color:var(–zephr-color-action-tinted)}.zephr-registration-form-button.svelte-17g75t9:disabled{background-color:var(–zephr-color-background-tinted);border-color:var(–zephr-color-background-tinted)}.zephr-registration-form-button.svelte-17g75t9:disabled:hover{background-color:var(–zephr-color-background-tinted);border-color:var(–zephr-color-background-tinted)}.zephr-registration-form-text.svelte-i1fi5{font-size:19px;text-align:center;margin:20px auto;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-divider-container.svelte-mk4m8o{display:flex;align-items:center;justify-content:center;margin:40px 0}.zephr-registration-form-divider-line.svelte-mk4m8o{height:1px;width:50%;margin:0 5px;background-color:var(–zephr-color-text-tinted);;}.zephr-registration-form-divider-text.svelte-mk4m8o{margin:0 12px;color:var(–zephr-color-text-main);font-size:14px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);white-space:nowrap}.zephr-registration-form-input-inner-text.svelte-lvlpcn{cursor:pointer;position:absolute;top:50%;transform:translateY(-50%);right:10px;color:var(–zephr-color-text-main);font-size:12px;font-weight:bold;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-response-message.svelte-179421u{text-align:center;padding:10px 30px;border-radius:5px;font-size:15px;margin-top:10px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-response-message-title.svelte-179421u{font-weight:bold;margin-bottom:10px}.zephr-registration-form-response-message-success.svelte-179421u{background-color:#baecbb;border:1px solid #00bc05}.zephr-registration-form-response-message-error.svelte-179421u{background-color:#fcdbec;border:1px solid #d90c00}.zephr-registration-form-social-sign-in.svelte-gp4ky7{align-items:center}.zephr-registration-form-social-sign-in-button.svelte-gp4ky7{height:55px;padding:0 15px;color:#000;background-color:#fff;box-shadow:0px 0px 5px rgba(0, 0, 0, 0.3);border-radius:10px;font-size:17px;display:flex;align-items:center;cursor:pointer;margin-top:20px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-social-sign-in-button.svelte-gp4ky7:hover{background-color:#fafafa}.zephr-registration-form-social-sign-in-icon.svelte-gp4ky7{display:flex;justify-content:center;margin-right:30px;width:25px}.zephr-form-link-message.svelte-rt4jae{margin:10px 0 10px 20px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-recaptcha-tcs.svelte-1wyy3bx{margin:20px 0 0 0;font-size:15px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-recaptcha-inline.svelte-1wyy3bx{margin:20px 0 0 0}.zephr-registration-form-progress-bar.svelte-8qyhcl{width:100%;border:0;border-radius:20px;margin-top:10px}.zephr-registration-form-progress-bar.svelte-8qyhcl::-webkit-progress-bar{background-color:var(–zephr-color-background-tinted);border:0;border-radius:20px}.zephr-registration-form-progress-bar.svelte-8qyhcl::-webkit-progress-value{background-color:var(–zephr-color-text-tinted);border:0;border-radius:20px}.zephr-registration-progress-bar-step.svelte-8qyhcl{margin:auto;color:var(–zephr-color-text-tinted);font-size:12px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-progress-bar-step.svelte-8qyhcl:first-child{margin-left:0}.zephr-registration-progress-bar-step.svelte-8qyhcl:last-child{margin-right:0}.zephr-registration-form-input-error-text.svelte-19a73pq{color:var(–zephr-color-warning-main);font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-input-select.svelte-19a73pq{display:block;appearance:auto;width:100%;height:calc(var(–zephr-input-height) * 1px);font-size:16px;border:calc(var(–zephr-input-borderWidth) * 1px) solid var(–zephr-color-text-main);border-radius:calc(var(–zephr-input-borderRadius) * 1px);transition:border-color 0.25s ease, box-shadow 0.25s ease;outline:0;color:var(–zephr-color-text-main);background-color:#fff;padding:10px}.zephr-registration-form-input-select.disabled.svelte-19a73pq{border:1px solid var(–zephr-color-background-tinted)}.zephr-registration-form-input-select.unselected.svelte-19a73pq{color:var(–zephr-color-background-tinted)}.zephr-registration-form-input-select.error.svelte-19a73pq{border-color:var(–zephr-color-warning-main)}.zephr-registration-form-input-textarea.svelte-19a73pq{background-color:#fff;border:1px solid #ddd;color:#222;font-size:14px;font-weight:300;padding:16px;width:100%}.zephr-registration-form-input-slider-output.svelte-19a73pq{margin:13px 0 0 10px}.zephr-registration-form-input-inner-text.svelte-lvlpcn{cursor:pointer;position:absolute;top:50%;transform:translateY(-50%);right:10px;color:var(–zephr-color-text-main);font-size:12px;font-weight:bold;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.spin.svelte-1cj2gr0{animation:svelte-1cj2gr0-spin 2s 0s infinite linear}.pulse.svelte-1cj2gr0{animation:svelte-1cj2gr0-spin 1s infinite steps(8)}@keyframes svelte-1cj2gr0-spin{0%{transform:rotate(0deg)}100%{transform:rotate(360deg)}}.zephr-registration-form-checkbox.svelte-1gzpw2y{position:absolute;opacity:0;cursor:pointer;height:0;width:0}.zephr-registration-form-checkbox-label.svelte-1gzpw2y{display:flex;align-items:center;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-checkmark.svelte-1gzpw2y{position:relative;box-sizing:border-box;height:23px;width:23px;background-color:#fff;border:1px solid var(–zephr-color-text-main);border-radius:6px;margin-right:12px;cursor:pointer}.zephr-registration-form-checkmark.checked.svelte-1gzpw2y{border-color:#009fe3}.zephr-registration-form-checkmark.checked.svelte-1gzpw2y:after{content:””;position:absolute;width:6px;height:13px;border:solid #009fe3;border-width:0 2px 2px 0;transform:rotate(45deg);top:3px;left:8px;box-sizing:border-box}.zephr-registration-form-checkmark.disabled.svelte-1gzpw2y{border:1px solid var(–zephr-color-background-tinted)}.zephr-registration-form-checkmark.disabled.checked.svelte-1gzpw2y:after{border:solid var(–zephr-color-background-tinted);border-width:0 2px 2px 0}.zephr-registration-form-checkmark.error.svelte-1gzpw2y{border:1px solid var(–zephr-color-warning-main)}.zephr-registration-form-input-radio.svelte-1qn5n0t{position:absolute;opacity:0;cursor:pointer;height:0;width:0}.zephr-registration-form-radio-label.svelte-1qn5n0t{display:flex;align-items:center;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-radio-dot.svelte-1qn5n0t{position:relative;box-sizing:border-box;height:23px;width:23px;background-color:#fff;border:1px solid #ebebeb;border-radius:50%;margin-right:12px}.checked.svelte-1qn5n0t{border-color:#009fe3}.checked.svelte-1qn5n0t:after{content:””;position:absolute;width:17px;height:17px;background:#009fe3;background:linear-gradient(#009fe3, #006cb5);border-radius:50%;top:2px;left:2px}.disabled.checked.svelte-1qn5n0t:after{background:var(–zephr-color-background-tinted)}.error.svelte-1qn5n0t{border:1px solid var(–zephr-color-warning-main)}.zephr-form-link.svelte-64wplc{margin:10px 0;color:#6ba5e9;text-decoration:underline;cursor:pointer;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-form-link-disabled.svelte-64wplc{color:var(–zephr-color-text-main);cursor:none;text-decoration:none}.zephr-registration-form-google-icon.svelte-1jnblvg{width:20px}.zephr-registration-form-password-progress.svelte-d1zv9r{display:flex;margin-top:10px}.zephr-registration-form-password-bar.svelte-d1zv9r{width:100%;height:4px;border-radius:2px}.zephr-registration-form-password-bar.svelte-d1zv9r:not(:first-child){margin-left:8px}.zephr-registration-form-password-requirements.svelte-d1zv9r{margin:20px 0;justify-content:center}.zephr-registration-form-password-requirement.svelte-d1zv9r{display:flex;align-items:center;color:var(–zephr-color-text-tinted);font-size:12px;height:20px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-password-requirement-icon.svelte-d1zv9r{margin-right:10px;font-size:15px}.zephr-registration-form-password-progress.svelte-d1zv9r{display:flex;margin-top:10px}.zephr-registration-form-password-bar.svelte-d1zv9r{width:100%;height:4px;border-radius:2px}.zephr-registration-form-password-bar.svelte-d1zv9r:not(:first-child){margin-left:8px}.zephr-registration-form-password-requirements.svelte-d1zv9r{margin:20px 0;justify-content:center}.zephr-registration-form-password-requirement.svelte-d1zv9r{display:flex;align-items:center;color:var(–zephr-color-text-tinted);font-size:12px;height:20px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-password-requirement-icon.svelte-d1zv9r{margin-right:10px;font-size:15px}
      .zephr-registration-form {
      max-width: 100%;
      background-image: url(/wp-content/themes/sciencenews/client/src/images/cta-module@2x.jpg);
      font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
      margin: 0px auto;
      margin-bottom: 4rem;
      padding: 20px;
      }

      .zephr-registration-form-text h6 {
      font-size: 0.8rem;
      }

      .zephr-registration-form h4 {
      font-size: 3rem;
      }

      .zephr-registration-form h4 {
      font-size: 1.5rem;
      }

      .zephr-registration-form-button.svelte-17g75t9:hover {
      background-color: #fc6a65;
      border-color: #fc6a65;
      width: 150px;
      margin-left: auto;
      margin-right: auto;
      }
      .zephr-registration-form-button.svelte-17g75t9:disabled {
      background-color: #e04821;
      border-color: #e04821;
      width: 150px;
      margin-left: auto;
      margin-right: auto;
      }
      .zephr-registration-form-button.svelte-17g75t9 {
      background-color: #e04821;
      border-color: #e04821;
      width: 150px;
      margin-left: auto;
      margin-right: auto;
      }
      .zephr-registration-form-text > * {
      color: #FFFFFF;
      font-weight: bold
      font: 25px;
      }
      .zephr-registration-form-progress-bar.svelte-8qyhcl {
      width: 100%;
      border: 0;
      border-radius: 20px;
      margin-top: 10px;
      display: none;
      }
      .zephr-registration-form-response-message-title.svelte-179421u {
      font-weight: bold;
      margin-bottom: 10px;
      display: none;
      }
      .zephr-registration-form-response-message-success.svelte-179421u {
      background-color: #8db869;
      border: 1px solid #8db869;
      color: white;
      margin-top: -0.2rem;
      }
      .zephr-registration-form-text.svelte-i1fi5:nth-child(1){
      font-size: 18px;
      text-align: center;
      margin: 20px auto;
      font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
      color: white;
      }
      .zephr-registration-form-text.svelte-i1fi5:nth-child(5){
      font-size: 18px;
      text-align: left;
      margin: 20px auto;
      font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
      color: white;
      }
      .zephr-registration-form-text.svelte-i1fi5:nth-child(7){
      font-size: 18px;
      text-align: left;
      margin: 20px auto;
      font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
      color: white;
      }
      .zephr-registration-form-text.svelte-i1fi5:nth-child(9){
      font-size: 18px;
      text-align: left;
      margin: 20px auto;
      font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
      color: white;
      }
      .zephr-registration-form-input-label.svelte-1ok5fdj span.svelte-1ok5fdj {
      display: none;
      color: white;
      }
      .zephr-registration-form-input.disabled.svelte-blfh8x, .zephr-registration-form-input.disabled.svelte-blfh8x:hover {
      border: calc(var(–zephr-input-borderWidth) * 1px) solid var(–zephr-input-borderColor);
      background-color: white;
      }
      .zephr-registration-form-checkbox-label.svelte-1gzpw2y {
      display: flex;
      align-items: center;
      font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
      color: white;
      font-size: 20px;
      margin-bottom: -20px;
      }

      The new technology could potentially limit excess estrogen’s harmful effects on animals, especially those that live in waterways.

      With the nanoparticles, “we are able … to clean very different kinds of environmental pollutants,” says Müller, of Friedrich-Alexander-Universität Erlangen-Nürnberg in Germany.

      Estrogen hormones typically enter waterways through humans’ and other animals’ waste (SN: 1/2/02). Even low concentrations can have harmful chronic effects on aquatic life, like higher instances of cancer or reproductive issues, says Konrad Wojnarowski, a biologist at Ludwig-Maximilians-Universität München who was not involved in the study. Wastewater treatment plants can remove some estrogen hormones, he says, but the process isn’t cheap or energy efficient.

      For now, “we still don’t have an ideal way of dealing with estrogen pollution in the environment,” but nanoparticles could help, Wojnarowski says.

      To build the estrogen-catching particles, Müller and Marcus Halik, a chemist also at Friedrich-Alexander-Universität, drew on prior experience designing iron oxide nanoparticles that can catch other kinds of pollutants like oil or herbicides (SN: 7/25/08). The tiny iron oxide cores are each about 10 nanometers in diameter. Each core is then covered in phosphonic acid molecules, which act like sticky hairs that scoop up contaminants.

      The new version of the nanoparticles specifically targets estrogen by including two types of phosphonic acid. One kind is long, repels water and attaches to the neutrally charged part of the estrogen molecule. The other is positively charged to attract parts of estrogen hormones that carry a slight negative charge.

      The smart rust removed much of the estrogen from small water samples prepared in the lab, the researchers found. Their next step is to test the nanoparticles on samples from actual waterways.

      And the team is investigating exactly how the molecules on the nanoparticle surfaces grab and hold on to estrogen at the atomic scale. With this information, Halik says, they can improve the estrogen binding even more. More

    • 125 Shares149 Views

      in Physics

      One photon is all it takes to kick off photosynthesis

      by

      For photosynthesis, one photon is all it takes.

      Only a single particle of light is required to spark the first steps of the biological process that converts light into chemical energy, scientists report June 14 in Nature.

      While scientists have long assumed that the reactions of photosynthesis begin upon the absorption of just one photon, that hadn’t yet been demonstrated, says physical chemist Graham Fleming, of the University of California, Berkeley. He and colleagues decided “we would just look to see was it really true that one photon was enough to start the whole thing off.”

      .email-conversion {
      border: 1px solid #ffcccb;
      color: white;
      margin-top: 50px;
      background-image: url(“/wp-content/themes/sciencenews/client/src/images/cta-module@2x.jpg”);
      padding: 20px;
      clear: both;
      }

      .zephr-registration-form{max-width:440px;margin:20px auto;padding:20px;background-color:#fff;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form *{box-sizing:border-box}.zephr-registration-form-text > *{color:var(–zephr-color-text-main)}.zephr-registration-form-relative-container{position:relative}.zephr-registration-form-flex-container{display:flex}.zephr-registration-form-input.svelte-blfh8x{display:block;width:100%;height:calc(var(–zephr-input-height) * 1px);padding-left:8px;font-size:16px;border:calc(var(–zephr-input-borderWidth) * 1px) solid var(–zephr-input-borderColor);border-radius:calc(var(–zephr-input-borderRadius) * 1px);transition:border-color 0.25s ease, box-shadow 0.25s ease;outline:0;color:var(–zephr-color-text-main);background-color:#fff;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-input.svelte-blfh8x::placeholder{color:var(–zephr-color-background-tinted)}.zephr-registration-form-input-checkbox.svelte-blfh8x{width:auto;height:auto;margin:8px 5px 0 0;float:left}.zephr-registration-form-input-radio.svelte-blfh8x{position:absolute;opacity:0;cursor:pointer;height:0;width:0}.zephr-registration-form-input-color[type=”color”].svelte-blfh8x{width:50px;padding:0;border-radius:50%}.zephr-registration-form-input-color[type=”color”].svelte-blfh8x::-webkit-color-swatch{border:none;border-radius:50%;padding:0}.zephr-registration-form-input-color[type=”color”].svelte-blfh8x::-webkit-color-swatch-wrapper{border:none;border-radius:50%;padding:0}.zephr-registration-form-input.disabled.svelte-blfh8x,.zephr-registration-form-input.disabled.svelte-blfh8x:hover{border:calc(var(–zephr-input-borderWidth) * 1px) solid var(–zephr-input-borderColor);background-color:var(–zephr-color-background-tinted)}.zephr-registration-form-input.error.svelte-blfh8x{border:1px solid var(–zephr-color-warning-main)}.zephr-registration-form-input-label.svelte-1ok5fdj.svelte-1ok5fdj{margin-top:10px;display:block;line-height:30px;font-size:12px;color:var(–zephr-color-text-tinted);font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-input-label.svelte-1ok5fdj span.svelte-1ok5fdj{display:block}.zephr-registration-form-button.svelte-17g75t9{height:calc(var(–zephr-button-height) * 1px);line-height:0;padding:0 20px;text-decoration:none;text-transform:capitalize;text-align:center;border-radius:calc(var(–zephr-button-borderRadius) * 1px);font-size:calc(var(–zephr-button-fontSize) * 1px);font-weight:normal;cursor:pointer;border-style:solid;border-width:calc(var(–zephr-button-borderWidth) * 1px);border-color:var(–zephr-color-action-tinted);transition:backdrop-filter 0.2s, background-color 0.2s;margin-top:20px;display:block;width:100%;background-color:var(–zephr-color-action-main);color:#fff;position:relative;overflow:hidden;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-button.svelte-17g75t9:hover{background-color:var(–zephr-color-action-tinted);border-color:var(–zephr-color-action-tinted)}.zephr-registration-form-button.svelte-17g75t9:disabled{background-color:var(–zephr-color-background-tinted);border-color:var(–zephr-color-background-tinted)}.zephr-registration-form-button.svelte-17g75t9:disabled:hover{background-color:var(–zephr-color-background-tinted);border-color:var(–zephr-color-background-tinted)}.zephr-registration-form-text.svelte-i1fi5{font-size:19px;text-align:center;margin:20px auto;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-divider-container.svelte-mk4m8o{display:flex;align-items:center;justify-content:center;margin:40px 0}.zephr-registration-form-divider-line.svelte-mk4m8o{height:1px;width:50%;margin:0 5px;background-color:var(–zephr-color-text-tinted);;}.zephr-registration-form-divider-text.svelte-mk4m8o{margin:0 12px;color:var(–zephr-color-text-main);font-size:14px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);white-space:nowrap}.zephr-registration-form-input-inner-text.svelte-lvlpcn{cursor:pointer;position:absolute;top:50%;transform:translateY(-50%);right:10px;color:var(–zephr-color-text-main);font-size:12px;font-weight:bold;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-response-message.svelte-179421u{text-align:center;padding:10px 30px;border-radius:5px;font-size:15px;margin-top:10px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-response-message-title.svelte-179421u{font-weight:bold;margin-bottom:10px}.zephr-registration-form-response-message-success.svelte-179421u{background-color:#baecbb;border:1px solid #00bc05}.zephr-registration-form-response-message-error.svelte-179421u{background-color:#fcdbec;border:1px solid #d90c00}.zephr-registration-form-social-sign-in.svelte-gp4ky7{align-items:center}.zephr-registration-form-social-sign-in-button.svelte-gp4ky7{height:55px;padding:0 15px;color:#000;background-color:#fff;box-shadow:0px 0px 5px rgba(0, 0, 0, 0.3);border-radius:10px;font-size:17px;display:flex;align-items:center;cursor:pointer;margin-top:20px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-social-sign-in-button.svelte-gp4ky7:hover{background-color:#fafafa}.zephr-registration-form-social-sign-in-icon.svelte-gp4ky7{display:flex;justify-content:center;margin-right:30px;width:25px}.zephr-form-link-message.svelte-rt4jae{margin:10px 0 10px 20px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-recaptcha-tcs.svelte-1wyy3bx{margin:20px 0 0 0;font-size:15px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-recaptcha-inline.svelte-1wyy3bx{margin:20px 0 0 0}.zephr-registration-form-progress-bar.svelte-8qyhcl{width:100%;border:0;border-radius:20px;margin-top:10px}.zephr-registration-form-progress-bar.svelte-8qyhcl::-webkit-progress-bar{background-color:var(–zephr-color-background-tinted);border:0;border-radius:20px}.zephr-registration-form-progress-bar.svelte-8qyhcl::-webkit-progress-value{background-color:var(–zephr-color-text-tinted);border:0;border-radius:20px}.zephr-registration-progress-bar-step.svelte-8qyhcl{margin:auto;color:var(–zephr-color-text-tinted);font-size:12px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-progress-bar-step.svelte-8qyhcl:first-child{margin-left:0}.zephr-registration-progress-bar-step.svelte-8qyhcl:last-child{margin-right:0}.zephr-registration-form-input-error-text.svelte-19a73pq{color:var(–zephr-color-warning-main);font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-input-select.svelte-19a73pq{display:block;appearance:auto;width:100%;height:calc(var(–zephr-input-height) * 1px);font-size:16px;border:calc(var(–zephr-input-borderWidth) * 1px) solid var(–zephr-color-text-main);border-radius:calc(var(–zephr-input-borderRadius) * 1px);transition:border-color 0.25s ease, box-shadow 0.25s ease;outline:0;color:var(–zephr-color-text-main);background-color:#fff;padding:10px}.zephr-registration-form-input-select.disabled.svelte-19a73pq{border:1px solid var(–zephr-color-background-tinted)}.zephr-registration-form-input-select.unselected.svelte-19a73pq{color:var(–zephr-color-background-tinted)}.zephr-registration-form-input-select.error.svelte-19a73pq{border-color:var(–zephr-color-warning-main)}.zephr-registration-form-input-textarea.svelte-19a73pq{background-color:#fff;border:1px solid #ddd;color:#222;font-size:14px;font-weight:300;padding:16px;width:100%}.zephr-registration-form-input-slider-output.svelte-19a73pq{margin:13px 0 0 10px}.zephr-registration-form-input-inner-text.svelte-lvlpcn{cursor:pointer;position:absolute;top:50%;transform:translateY(-50%);right:10px;color:var(–zephr-color-text-main);font-size:12px;font-weight:bold;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.spin.svelte-1cj2gr0{animation:svelte-1cj2gr0-spin 2s 0s infinite linear}.pulse.svelte-1cj2gr0{animation:svelte-1cj2gr0-spin 1s infinite steps(8)}@keyframes svelte-1cj2gr0-spin{0%{transform:rotate(0deg)}100%{transform:rotate(360deg)}}.zephr-registration-form-checkbox.svelte-1gzpw2y{position:absolute;opacity:0;cursor:pointer;height:0;width:0}.zephr-registration-form-checkbox-label.svelte-1gzpw2y{display:flex;align-items:center;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-checkmark.svelte-1gzpw2y{position:relative;box-sizing:border-box;height:23px;width:23px;background-color:#fff;border:1px solid var(–zephr-color-text-main);border-radius:6px;margin-right:12px;cursor:pointer}.zephr-registration-form-checkmark.checked.svelte-1gzpw2y{border-color:#009fe3}.zephr-registration-form-checkmark.checked.svelte-1gzpw2y:after{content:””;position:absolute;width:6px;height:13px;border:solid #009fe3;border-width:0 2px 2px 0;transform:rotate(45deg);top:3px;left:8px;box-sizing:border-box}.zephr-registration-form-checkmark.disabled.svelte-1gzpw2y{border:1px solid var(–zephr-color-background-tinted)}.zephr-registration-form-checkmark.disabled.checked.svelte-1gzpw2y:after{border:solid var(–zephr-color-background-tinted);border-width:0 2px 2px 0}.zephr-registration-form-checkmark.error.svelte-1gzpw2y{border:1px solid var(–zephr-color-warning-main)}.zephr-registration-form-input-radio.svelte-1qn5n0t{position:absolute;opacity:0;cursor:pointer;height:0;width:0}.zephr-registration-form-radio-label.svelte-1qn5n0t{display:flex;align-items:center;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-radio-dot.svelte-1qn5n0t{position:relative;box-sizing:border-box;height:23px;width:23px;background-color:#fff;border:1px solid #ebebeb;border-radius:50%;margin-right:12px}.checked.svelte-1qn5n0t{border-color:#009fe3}.checked.svelte-1qn5n0t:after{content:””;position:absolute;width:17px;height:17px;background:#009fe3;background:linear-gradient(#009fe3, #006cb5);border-radius:50%;top:2px;left:2px}.disabled.checked.svelte-1qn5n0t:after{background:var(–zephr-color-background-tinted)}.error.svelte-1qn5n0t{border:1px solid var(–zephr-color-warning-main)}.zephr-form-link.svelte-64wplc{margin:10px 0;color:#6ba5e9;text-decoration:underline;cursor:pointer;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-form-link-disabled.svelte-64wplc{color:var(–zephr-color-text-main);cursor:none;text-decoration:none}.zephr-registration-form-google-icon.svelte-1jnblvg{width:20px}.zephr-registration-form-password-progress.svelte-d1zv9r{display:flex;margin-top:10px}.zephr-registration-form-password-bar.svelte-d1zv9r{width:100%;height:4px;border-radius:2px}.zephr-registration-form-password-bar.svelte-d1zv9r:not(:first-child){margin-left:8px}.zephr-registration-form-password-requirements.svelte-d1zv9r{margin:20px 0;justify-content:center}.zephr-registration-form-password-requirement.svelte-d1zv9r{display:flex;align-items:center;color:var(–zephr-color-text-tinted);font-size:12px;height:20px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-password-requirement-icon.svelte-d1zv9r{margin-right:10px;font-size:15px}.zephr-registration-form-password-progress.svelte-d1zv9r{display:flex;margin-top:10px}.zephr-registration-form-password-bar.svelte-d1zv9r{width:100%;height:4px;border-radius:2px}.zephr-registration-form-password-bar.svelte-d1zv9r:not(:first-child){margin-left:8px}.zephr-registration-form-password-requirements.svelte-d1zv9r{margin:20px 0;justify-content:center}.zephr-registration-form-password-requirement.svelte-d1zv9r{display:flex;align-items:center;color:var(–zephr-color-text-tinted);font-size:12px;height:20px;font-family:var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont)}.zephr-registration-form-password-requirement-icon.svelte-d1zv9r{margin-right:10px;font-size:15px}
      .zephr-registration-form {
      max-width: 100%;
      background-image: url(https://www.sciencenews.org/wp-content/uploads/2023/05/newsletter-signup-background_REV.jpg);
      background-position: top 75% left 67%;
      font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
      margin: 0px auto;
      margin-bottom: 4rem;
      padding: 20px;
      }

      .zephr-registration-form-text.svelte-i1fi5 p {
      padding-left: 10px;
      padding-right: 10px;
      padding-bottom: 10px;
      }

      .zephr-registration-form-text.svelte-i1fi5 h2 {
      padding-top: 10px;
      }

      .zephr-registration-form-text h6 {
      font-size: 0.8rem;
      }

      .zephr-registration-form h4 {
      font-size: 3rem;
      }

      .zephr-registration-form h4 {
      font-size: 1.5rem;
      }

      .zephr-registration-form-button.svelte-17g75t9:hover {
      background-color: #fc6a65;
      border-color: #fc6a65;
      width: 150px;
      margin-left: auto;
      margin-right: auto;
      }
      .zephr-registration-form-button.svelte-17g75t9:disabled {
      background-color: #e04821;
      border-color: #e04821;
      width: 150px;
      margin-left: auto;
      margin-right: auto;
      }
      .zephr-registration-form-button.svelte-17g75t9 {
      background-color: #e04821;
      border-color: #e04821;
      width: 150px;
      margin-left: auto;
      margin-right: auto;
      }
      .zephr-registration-form-text > * {
      color: #FFFFFF;
      font-weight: bold
      font: 25px;
      background-color: rgba(10,10,10,0.7)
      }
      .zephr-registration-form-progress-bar.svelte-8qyhcl {
      width: 100%;
      border: 0;
      border-radius: 20px;
      margin-top: 10px;
      display: none;
      }
      .zephr-registration-form-response-message-title.svelte-179421u {
      font-weight: bold;
      margin-bottom: 10px;
      display: none;
      }
      .zephr-registration-form-response-message-success.svelte-179421u {
      background-color: #8db869;
      border: 1px solid #8db869;
      color: white;
      margin-top: -0.2rem;
      }
      .zephr-registration-form-text.svelte-i1fi5:nth-child(1){
      font-size: 18px;
      text-align: center;
      margin: 20px auto;
      font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
      color: white;
      }
      .zephr-registration-form-text.svelte-i1fi5:nth-child(5){
      font-size: 18px;
      text-align: left;
      margin: 20px auto;
      font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
      color: white;
      }
      .zephr-registration-form-text.svelte-i1fi5:nth-child(7){
      font-size: 18px;
      text-align: left;
      margin: 20px auto;
      font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
      color: white;
      }
      .zephr-registration-form-text.svelte-i1fi5:nth-child(9){
      font-size: 18px;
      text-align: left;
      margin: 20px auto;
      font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
      color: white;
      }
      .zephr-registration-form-input-label.svelte-1ok5fdj span.svelte-1ok5fdj {
      display: none;
      color: white;
      }
      .zephr-registration-form-input.disabled.svelte-blfh8x, .zephr-registration-form-input.disabled.svelte-blfh8x:hover {
      border: calc(var(–zephr-input-borderWidth) * 1px) solid var(–zephr-input-borderColor);
      background-color: white;
      }
      .zephr-registration-form-checkbox-label.svelte-1gzpw2y {
      display: flex;
      align-items: center;
      font-family: var(–zephr-typography-body-font), var(–zephr-typography-body-fallbackFont);
      color: white;
      font-size: 20px;
      margin-bottom: -20px;
      }
      .zephr-registration-progress-bar-step.svelte-8qyhcl:first-child {
      display: none;
      }
      .zephr-registration-progress-bar-step.svelte-8qyhcl:last-child {
      display: none;
      }

      The sunlight that falls on Earth’s surface seems brilliant to human eyes. But on small scales, that translates to a dribble of photons. Only a few tens of photons of the appropriate wavelengths of sunlight fall on a square nanometer per second, the scale of the tiny chlorophyll and bacteriochlorophyll molecules that are central to photosynthesis in plants and bacteria.

      Many laboratory experiments on photosynthesis use lasers, much more powerful light sources, to kick off the reactions. Instead, Graham and colleagues used a source of light that produces just two photons at a time. One photon served as a herald, going off to a detector to let researchers know when two photons were released. The other photon went into a solution containing photon-absorbing structures from the photosynthetic bacterium Rhodobacter sphaeroides. These structures, called light-harvesting 2 complexes, or LH2, are made up of two rings of bacteriochlorophyll and other molecules.

      In a normal photosynthesis reaction, LH2 absorbs a photon and passes its energy to another LH2 complex, and then another, like a game of hot potato. Eventually the energy reaches another type of ring, called the light-harvesting 1 complex, or LH1, which then passes it to the reaction center where the energy is finally converted into a form that the bacterium can use.

      In the experiment, there was no LH1, so the LH2 instead emitted a photon of a different wavelength than the first, a sign that energy had been transferred from the first ring of LH2 to the second, a first step of photosynthesis. The researchers detected that second photon, and by comparing the detection times to those of the initial herald photons, confirmed that the LH2 needed to absorb only one photon to kick things off.

      Plants and bacteria use different processes for photosynthesis, but the initial steps are similar enough that in plants, too, a single photon would set off the initial steps, Fleming says. However, in plants, multiple independently absorbed photons are needed in order to complete the reaction.

      The role of single photons isn’t surprising, says biochemist Richard Cogdell of the University of Glasgow in Scotland. The important thing the researchers have done, he says, is to demonstrate the new technique. “By doing this you’re able to essentially interrogate what will be happening in nature,” he says.  

      Some scientists suspect that photosynthesis relies on quantum physics (SN: 2/3/10). While it’s not clear whether the new technique could resolve the role of quantum effects, it could help scientists disentangle natural effects from artifacts of using intense sources of light in studies of photosynthesis.

      “You can really work out what’s happening in the early reactions in photosynthesis as it were outside,” says Cogdell, “[as if] you could shrink yourself down and watch these photons moving around.” More

    • 113 Shares199 Views

      in Physics

      Here’s why some Renaissance artists egged their oil paintings

      by

      Art historians often wish that Renaissance painters could shell out secrets of the craft. Now, scientists may have cracked one using chemistry and physics.

      Around the turn of the 15th century in Italy, oil-based paints replaced egg-based tempera paints as the dominant medium. During this transition, artists including Leonardo da Vinci and Sandro Botticelli also experimented with paints made from oil and egg (SN: 4/30/14). But it has been unclear how adding egg to oil paints may have affected the artwork.  

      Science News headlines, in your inbox

      Headlines and summaries of the latest Science News articles, delivered to your email inbox every Thursday.

      Thank you for signing up!

      There was a problem signing you up.

      “Usually, when we think about art, not everybody thinks about the science which is behind it,” says chemical engineer Ophélie Ranquet of the Karlsruhe Institute of Technology in Germany.

      In the lab, Ranquet and colleagues whipped up two oil-egg recipes to compare with plain oil paint. One mixture contained fresh egg yolk mixed into oil paint, and had a similar consistency to mayonnaise. For the other blend, the scientists ground pigment into the yolk, dried it and mixed it with oil — a process the old masters might have used, according to the scant historical records that exist today. Each medium was subjected to a battery of tests that analyzed its mass, moisture, oxidation, heat capacity, drying time and more.

      In both concoctions, the yolk’s proteins, phospholipids and antioxidants helped slow paint oxidation, which can cause paint to turn yellow over time, the team reports March 28 in Nature Communications. 

      In the mayolike blend, the yolk created sturdy links between pigment particles, resulting in stiffer paint. Such consistency would have been ideal for techniques like impasto, a raised, thick style that adds texture to art. Egg additions also could have reduced wrinkling by creating a firmer paint consistency. Wrinkling sometimes happens with oil paints when the top layer dries faster than the paint underneath, and the dried film buckles over looser, still-wet paint.

      The hybrid mediums have some less than eggs-ellent qualities, though. For instance, the eggy oil paint can take longer to dry. If paints were too yolky, Renaissance artists would have had to wait a long time to add the next layer, Ranquet says.

      “The more we understand how artists select and manipulate their materials, the more we can appreciate what they’re doing, the creative process and the final product,” says Ken Sutherland, director of scientific research at the Art Institute of Chicago, who was not involved with the work.

      Research on historical art mediums can not only aid art preservation efforts, Sutherland says, but also help people gain a deeper understanding of the artworks themselves. More

    • 113 Shares189 Views

      in Physics

      These chemists cracked the code to long-lasting Roman concrete

      by

      MIT chemist Admir Masic really hoped his experiment wouldn’t explode.

      Masic and his colleagues were trying to re-create an ancient Roman technique for making concrete, a mix of cement, gravel, sand and water. The researchers suspected that the key was a process called “hot mixing,” in which dry granules of calcium oxide, also called quicklime, are mixed with volcanic ash to make the cement. Then water is added.

      Hot mixing, they thought, would ultimately produce a cement that wasn’t completely smooth and mixed, but instead contained small calcium-rich rocks. Those little rocks, ubiquitous in the walls of the Romans’ concrete buildings, might be the key to why those structures have withstood the ravages of time.

      Science News headlines, in your inbox

      Headlines and summaries of the latest Science News articles, delivered to your email inbox every Thursday.

      Thank you for signing up!

      There was a problem signing you up.

      That’s not how modern cement is made. The reaction of quicklime with water is highly exothermic, meaning that it can produce a lot of heat — and possibly an explosion.

      “Everyone would say, ‘You are crazy,’” Masic says.

      But no big bang happened. Instead, the reaction produced only heat, a damp sigh of water vapor — and a Romans-like cement mixture bearing small white calcium-rich rocks.

      Researchers have been trying for decades to re-create the Roman recipe for concrete longevity — but with little success. The idea that hot mixing was the key was an educated guess.

      Masic and colleagues had pored over texts by Roman architect Vitruvius and historian Pliny, which offered some clues as to how to proceed. These texts cited, for example, strict specifications for the raw materials, such as that the limestone that is the source of the quicklime must be very pure, and that mixing quicklime with hot ash and then adding water could produce a lot of heat.

      The rocks were not mentioned, but the team had a feeling they were important.

      Subscribe to Science News

      Get great science journalism, from the most trusted source, delivered to your doorstep.

      “In every sample we have seen of ancient Roman concrete, you can find these white inclusions,” bits of rock embedded in the walls. For many years, Masic says, the origin of those inclusions was unclear — researchers suspected incomplete mixing of the cement, perhaps. But these are the highly organized Romans we’re talking about. How likely is it that “every operator [was] not mixing properly and every single [building] has a flaw?”

      What if, the team suggested, these inclusions in the cement were actually a feature, not a bug? The researchers’ chemical analyses of such rocks embedded in the walls at the archaeological site of Privernum in Italy indicated that the inclusions were very calcium-rich.

      That suggested the tantalizing possibility that these rocks might be helping the buildings heal themselves from cracks due to weathering or even an earthquake. A ready supply of calcium was already on hand: It would dissolve, seep into the cracks and re-crystallize. Voila! Scar healed.

      But could the team observe this in action? Step one was to re-create the rocks via hot mixing and hope nothing exploded. Step two: Test the Roman-inspired cement. The team created concrete with and without the hot mixing process and tested them side by side. Each block of concrete was broken in half, the pieces placed a small distance apart. Then water was trickled through the crack to see how long it took before the seepage stopped.

      “The results were stunning,” Masic says. The blocks incorporating hot mixed cement healed within two to three weeks. The concrete produced without hot mixed cement never healed at all, the team reports January 6 in Science Advances.

      Cracking the recipe could be a boon to the planet. The Pantheon and its soaring, detailed concrete dome have stood nearly 2,000 years, for instance, while modern concrete structures have a lifespan of perhaps 150 years, and that’s a best case scenario (SN: 2/10/12). And the Romans didn’t have steel reinforcement bars shoring up their structures.

      More frequent replacements of concrete structures means more greenhouse gas emissions. Concrete manufacturing is a huge source of carbon dioxide to the atmosphere, so longer-lasting versions could reduce that carbon footprint. “We make 4 gigatons per year of this material,” Masic says. That manufacture produces as much as 1 metric ton of CO2 per metric ton of produced concrete, currently amounting to about 8 percent of annual global CO2 emissions.

      Still, Masic says, the concrete industry is resistant to change. For one thing, there are concerns about introducing new chemistry into a tried-and-true mixture with well-known mechanical properties. But “the key bottleneck in the industry is the cost,” he says. Concrete is cheap, and companies don’t want to price themselves out of competition.

      The researchers hope that reintroducing this technique that has stood the test of time, and that could involve little added cost to manufacture, could answer both these concerns. In fact, they’re banking on it: Masic and several of his colleagues have created a startup they call DMAT that is currently seeking seed money to begin to commercially produce the Roman-inspired hot-mixed concrete. “It’s very appealing simply because it’s a thousands-of-years-old material.” More

    • 125 Shares139 Views

      in Heart

      This eco-friendly glitter gets its color from plants, not plastic

      by

      All that glitters is not green. Glitter and shimmery pigments are often made using toxic compounds or pollutive microplastics (SN: 4/15/19). That makes the sparkly stuff, notoriously difficult to clean up in the house, a scourge on the environment too.

      A new, nontoxic, biodegradable alternative could change that. In the material, cellulose — the main building block of plant cell walls — creates nanoscale patterns that give rise to vibrant structural colors (SN: 9/28/21). Such a material could be used to make eco-friendly glitter and shiny pigments for paints, cosmetics or packaging, researchers report November 11 in Nature Materials.

      The inspiration to harness cellulose came from the African plant Pollia condensata, which produces bright, iridescent blue fruits called marble berries. Tiny patterns of cellulose fibers in the berries’ cell walls reflect specific wavelengths of light to create the signature hue. “I thought, if the plants can make it, we should be able to make it,” says chemist Silvia Vignolini of the University of Cambridge. 

      Vignolini and colleagues whipped up a watery mixture containing cellulose fibers and poured it onto plastic. As the liquid dried into a film, the rodlike fibers settled into helical structures resembling spiral staircases. Tweaking factors such as the steepness of those staircases changed which wavelengths of light the cellulose arrangements reflected, and therefore the color of the film.

      That allowed the researchers, like fairy-tale characters spinning straw into gold, to transform their clear, plant-based slurry into meter-long shimmery ribbons in a rainbow of colors. These swaths could then be peeled off their plastic platform and ground up to make glitter.

      This gleaming ribbon contains tiny arrangements of eco-friendly cellulose that reflect light in specific ways to give the material its color.Benjamin Drouguet

      “You can use any type of cellulose,” Vignolini says. Her team used cellulose from wood pulp, but could have used fruit peels or cotton fibers left over from textile production.

      The researchers need to test the environmental impacts of their newfangled glitter. But Vignolini is optimistic that materials using such natural ingredients have a bright future. More

    • 100 Shares169 Views

      in Heart

      Many cosmetics contain hidden, potentially dangerous ‘forever chemicals’

      by

      A new chemical analysis has revealed an ugly truth about beauty products: Many may contain highly persistent, potentially harmful “forever chemicals” called PFAS.

      PFAS, short for per- and polyfluoroalkyl substances, include thousands of chemicals that are so sturdy they can linger in the body for years and the environment for centuries. The health effects of only a few PFAS are well known, but those compounds have been linked to high cholesterol, thyroid diseases and other problems.

      “There is no known good PFAS,” says chemist and physicist Graham Peaslee of the University of Notre Dame in Indiana.

      In the first large screening of cosmetics for PFAS in the United States and Canada, Peaslee and colleagues found that 52 percent of over 200 tested products had high fluorine concentrations, suggesting the presence of PFAS, the researchers report online June 15 in Environmental Science & Technology Letters.

      The potential health risks of PFAS in makeup are not yet clear, Peaslee says. But besides people ingesting or absorbing PFAS when wearing makeup, cosmetics washed down the drain could get into drinking water (SN: 11/25/18).

      Peaslee’s team measured the amount of fluorine, a key component of PFAS, in 231 cosmetics. Sixty-three percent of foundations, 55 percent of lip products and 82 percent of waterproof mascara contained high levels of fluorine — at least 0.384 micrograms of fluorine per square centimeter of product spread on a piece of paper. Long-lasting or waterproof products were especially likely to contain lots of fluorine. That makes sense, since PFAS are water-resistant.

      Twenty-nine products further tested for specific PFAS all contained at least four of these chemicals, but only one product listed PFAS among its ingredients. In addition to posing their own potential health risks, these compounds can break down in the body into other PFAS, such as perfluorooctanoic acid, which has been linked to cancers and low birth weights (SN: 6/4/19).

      Sign Up For the Latest from Science News

      Headlines and summaries of the latest Science News articles, delivered to your inbox More

    • 138 Shares139 Views

      in Heart

      A new technique could make some plastic trash compostable at home

      by

      A pinch of polymer-munching enzymes could make biodegradable plastic packaging and forks truly compostable.

      With moderate heat, enzyme-laced films of the plastic disintegrated in standard compost or plain tap water within days to weeks, Ting Xu and her colleagues report April 21 in Nature.

      “Biodegradability does not equal compostability,” says Xu, a polymer scientist at the University of California, Berkeley and Lawrence Berkeley National Laboratory. She often finds bits of biodegradable plastic in the compost she picks up for her parents’ garden. Most biodegradable plastics go to landfills, where the conditions aren’t right for them to break down, so they degrade no faster than normal plastics.

      Embedding polymer-chomping enzymes in biodegradable plastic should accelerate decomposition. But that process often inadvertently forms potentially harmful microplastics, which are showing up in ecosystems across the globe (SN: 11/20/20). The enzymes clump together and randomly snip plastics’ molecular chains, leading to an incomplete breakdown. “It’s worse than if you don’t degrade them in the first place,” Xu says.

      Her team added individual enzymes into two biodegradable plastics, including polylactic acid, commonly used in food packaging. They inserted the enzymes along with another ingredient, a degradable additive Xu previously developed, which ensured the enzymes didn’t clump together and didn’t fall apart. The solitary enzymes grabbed the ends of the plastics’ molecular chains and ate as though they were slurping spaghetti, severing every chain link and preventing microplastic formation.

      Filaments of a new plastic material degrade completely (right) when submerged in tap water for several days.Adam Lau/Berkeley Engineering

      Adding enzymes usually makes plastic expensive and compromises its properties. However, Xu’s enzymes make up as little as 0.02 percent of the plastic’s weight, and her plastics are as strong and flexible as one typically used in grocery bags.

      The technology doesn’t work on all plastics because their molecular structures vary, a limitation Xu’s team is working to overcome. She’s filed a patent application for the technology, and a coauthor founded a startup to commercialize it. “We want this to be in every grocery store,” she says. More