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Color-changing strip enables affordable nanoplastic analysis using ordinary microscope

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Color-changing strip enables affordable nanoplastic analysis using ordinary microscope


The optical sieve nanoplastic particles fall into holes of the appropriate size in the test strip. The color of the holes changes. The new color provides information about the size and number of particles. Credit: University of Stuttgart

A joint team from the University of Stuttgart in Germany and the University of Melbourne in Australia has developed a new method for the straightforward analysis of tiny nanoplastic particles in environmental samples. One needs only an ordinary optical microscope and a newly developed test strip—the optical sieve. The research results have now been published in Nature Photonics.

“The test strip can serve as a simple analysis tool in environmental and health research,” explains Prof. Harald Giessen, Head of the 4th Physics Institute of the University of Stuttgart. “In the near future, we will be working toward analyzing concentrations directly on site. But our new method could also be used to test blood or tissue for nanoplastic particles.”

Plastic waste is one of the central and acute global problems of the 21st century. It not only pollutes oceans, rivers, and beaches but has also been detected in living organisms in the form of microplastics. Until now, environmental scientists have focused their attention on larger plastic residues.

However, it has been known for some time that an even greater danger may be on the horizon: nanoplastic particles. These are much smaller than a human hair and are created through the breakdown of larger plastic particles. They cannot be seen with the naked eye. These particles in the sub-micrometer range can also easily cross organic barriers such as the skin or the blood-brain barrier.

Because of the small particle size, their detection poses a particular challenge. As a result, there are not only gaps in our understanding of how particles affect organisms but also a lack of rapid and reliable detection methods.

In collaboration with a research group from Melbourne in Australia, researchers at the University of Stuttgart have now developed a novel method that can quickly and affordably detect such small particles. Color changes on a special test strip make nanoplastics visible in an optical microscope and allow researchers to count the number of particles and determine their size.

“Compared with conventional and widely used methods such as scanning , the new method is considerably less expensive, does not require trained personnel to operate, and reduces the time required for detailed analysis,” explains Dr. Mario Hentschel, Head of the Microstructure Laboratory at the 4th Physics Institute.

The “optical sieve” uses resonance effects in small holes to make the nanoplastic particles visible. A study on optical effects in such holes was first published by the research group at the University of Stuttgart in 2023. The process is based on tiny depressions, known as Mie voids, which are edged into a semiconductor substrate.

Depending on their diameter and depth, the holes interact characteristically with the incident light. This results in a bright color reflection that can be seen with an optical microscope. If a particle falls into one of the indentations, its color changes noticeably. One can therefore infer from the changing color whether a particle is present in the void.

“The test strip works like a classic sieve,” explains Dominik Ludescher, Ph.D. student and first author of the publication. Particles ranging from 0.2 to 1 µm can thus be examined without difficulty. The particles are filtered out of the liquid using the sieve in which the size and depth of the holes can be adapted to the nanoplastic particles, and subsequently by the resulting color change can be detected. This allows us to determine whether the voids are filled or empty.”

The novel detection method used can do even more. If the sieve is provided with voids of different sizes, only one particle of a suitable size will collect in each hole. “If a particle is too large, it won’t fit into the void and will simply be flushed away during the cleaning process,” says Ludescher.

“If a particle is too small, it will adhere poorly to the well and will be washed away during cleaning.” In this way, the test strips can be adapted so that the size and number of particles in each individual hole can be determined from the reflected color.

For their measurements, the researchers used spherical particles of various diameters. These are available in aqueous solutions with specific nanoparticle. Because real samples from bodies of water with known nanoparticle concentrations are not yet available, the team produced a suitable sample themselves.

The researchers used a water sample from a lake that contained a mixture of sand and other organic components and added spherical particles in known quantities. The concentration of plastic particles was 150 µg/ml. The number and size distribution of the nanoplastic particles could also be determined for this sample using the optical sieve.

“In the long term, the optical sieve will be used as a simple analysis tool in environmental and . The technology could serve as a mobile that would provide information on the content of nanoplastics in water or soil directly on site,” explains Hentschel.

The team is now planning experiments with nanoplastic particles that are not spherical. The researchers also plan to investigate whether the process can be used to distinguish between particles of different plastics. They are also particularly interested in collaborating with research groups that have specific expertise in processing real samples from bodies of water.

More information:
D. Ludescher et al, Optical sieve for nanoplastic detection, sizing and counting. Nature Photonics (2025). DOI: 10.1038/s41566-025-01733-x. www.nature.com/articles/s41566-025-01733-x

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Color-changing strip enables affordable nanoplastic analysis using ordinary microscope (2025, September 13)
retrieved 13 September 2025
from https://techxplore.com/news/2025-09-enables-nanoplastic-analysis-ordinary-microscope.html

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OnlyFans Goes to Business School

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OnlyFans Goes to Business School


OnlyFans has tapped the founder of a lingerie company and former nude model to launch business classes on the platform.

Rachael McCrary, a longtime lingerie designer and founder of the company Spice Rack, is launching four videos on OnlyFans Wednesday. The videos are quite different from the usual OnlyFans fare. They’ll focus on pitching investors, building a brand, and navigating being an entrepreneur as a woman, McCrary tells WIRED. More videos will follow. She’s also creating a Spice Rack x OnlyFans clothing line that will launch on the site later this year.

The move is OnlyFans’ first foray into making content focused solely on building a business. It’s part of the platform’s continued push into safe-for-work content that’s meant to complement the adult content it’s known for.

“OnlyFans is a community of over 4 million creator businesses, so it makes sense that we are the perfect platform to share tips on entrepreneurship,” Keily Blair, CEO of OnlyFans, tells WIRED in a statement. “As we’ve seen in other genres like comedy and sport, it takes just one creator to recognize the opportunity and others will follow suit.”

McCrary, 48, said she met Blair at the tech conference Summit Baja last November, when they came up with the idea.

As a former SuicideGirl—a community of alt pin-up girls founded in the early 2000s—she says she felt stigmatized by her past when working in corporate fashion. At one of her jobs, she says her colleagues looked at her SuicideGirls photos while she was at work.

“I just wanted to start crying,” she says.

Then she decided to launch her own businesses, but “pitching underwear to tech VCs, I already felt like I had to prove myself more,” McCrary says. According to Inc., only 1 percent of VC-funded companies were wholly led by women in 2024. Spice Rack, which McCrary says is backed by Sequoia Partners China and Mucker Capital, is among them.

“Being naked on the internet and raising venture capital from the largest funds in the world is a very rare Venn diagram,” McCrary says, adding that OnlyFans was already looking to expand into more non-adult content. “We decided to do a masterclass format of business classes.” The first two classes will be free, while the others will require a subscription to McCrary’s page.

Over the years, McCrary says, she’s been approached by many young women, including sex workers, seeking advice on how to start their own businesses or pivot away from adult content. After she revealed her past as a SuicideGirl on a panel in 2022, she says an adult content creator came up to her and said, “I didn’t know that you were naked on the internet, and that makes me feel like I can have a career after this.”



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Australian police design AI tool to decipher predators’ Gen Z slang

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Australian police design AI tool to decipher predators’ Gen Z slang


Australian police are working with Microsoft to develop a tool that can unravel sinister messages hidden by seemingly innocuous emojis and slang.

Australian police are working on an AI prototype that will help them decipher Gen Z slang and emoji-laden messages written by online predators, a top official said Wednesday.

Australian Federal Police Commissioner Krissy Barrett said social media had become a breeding ground for bullying, and radicalization.

Police were working with software giant Microsoft to develop a tool that would unravel sinister messages hidden by seemingly innocuous emojis and slang, she said.

“Clever AFP members, with Microsoft, are developing a prototype AI tool that will interpret emojis and Gen Z-and-Alpha slang in encrypted communications.

“This prototype aims to make it quicker for our teams to save children from harm much earlier.”

Barrett also warned about the rise of so-called “crimefluencers”—online predators who used their social media savvy to target young and vulnerable users.

“They are crimefluencers, and they are motivated by anarchy and hurting others, with most of their victims pre-teen or ,” she said.

Australia will from December 10 force such as Facebook, Instagram and TikTok to remove users under the age of 16.

There is keen interest in whether Australia’s sweeping restrictions can work, as regulators around the globe wrestle with the dangers of social media.

© 2025 AFP

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Australian police design AI tool to decipher predators’ Gen Z slang (2025, October 29)
retrieved 29 October 2025
from https://techxplore.com/news/2025-10-australian-police-ai-tool-decipher.html

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Rainfall Buries a Mega-Airport in Mexico

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Rainfall Buries a Mega-Airport in Mexico


The story of the park begins in 2014, when Enrique Peña Nieto, the president of Mexico at the time, announced plans for a new transport hub for Mexico City. It would be built on the largely dry bed of Lake Texcoco, the body of water that had once surrounded Mexico City’s ancient ancestor, Tenochtitlán, the center of the Aztec empire. The marketing promise was that NAICM would be one of the greenest airports in the world. The terminal, designed by Norman Foster—winner of the Pritzker Prize in 1999 and the Prince of Asturias Award for the Arts in 2009—was going to be the first to obtain LEED platinum certification, the highest international recognition for energy efficiency and sustainable design.

Its site, Lake Texcoco, had already lost more than 95 percent of its original surface area, and in 2015 plans were made to drain it completely to build the airport. However, when Andrés Manuel López Obrador took office as Mexico’s president in 2018, he canceled the plan. It would end up costing more than $13 billion and would leave behind serious environmental damage: The incomplete project destroyed a key refuge for migratory birds; carved up mountains in the State of Mexico (the federal region that surrounds Mexico City); razed agricultural land; and altered the landscape of the cultural capital of the Nahua, an indigenous people that includes the Mexica (or Aztecs).

Echeverría, who says he has been obsessed with the area for nearly three decades, was appointed by the new government to restore the local ecosystem. “It felt like I was stepping onto Mars,” says the architect, reflecting on being placed at the helm of the project. The park covers an area equivalent to 21 times the area of Mexico City’s enormous Bosque de Chapultepec park. Echeverría offers his own comparisons: “This place is three times the size of the city of Oaxaca and, as a reference for those outside Mexico, it’s roughly three times the size of Manhattan.”

The restoration project wasn’t a mere whim of Mexico’s new president, but the culmination of a century of visions and plans. “We’ve been skating around this for 75 years,” Echeverría says, citing restoration projects that were proposed as early as 1913, including ones by Miguel Ángel de Quevedo (a celebrated early environmentalist) in the 1930s and agronomist Gonzalo Blanco Macías in the 1950s. What was missing, Echeverría says, “wasn’t a lack of ideas, but of political will.”



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