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 nanoplastic 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 tiny particles 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 electron microscopy, 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 health research. The technology could serve as a mobile test strip 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.

OpenAI has reached a new tentative agreement with Microsoft and said its nonprofit, which technically controls its business, will now be given a $100 billion equity stake in its for-profit corporation.

The maker of ChatGPT said it had reached a new nonbinding agreement with Microsoft, its longtime partner, “for the next phase of our partnership.”

The announcements on Thursday include a few details about these new arrangements. OpenAI’s proposed changes to its corporate structure have drawn the scrutiny of regulators, competitors and advocates concerned about the impacts of artificial intelligence.

OpenAI was founded as a nonprofit in 2015 and its nonprofit board has continued to control the for-profit subsidiary that now develops and sells its AI products. It’s not clear whether the $100 billion equity stake the nonprofit will get as part of this announcement represents a controlling stake in the business.

California Attorney General Rob Bonta said last week that his office was investigating OpenAI’s proposed restructuring of its finances and governance. His office said they could not comment on the new announcements but said they are “committed to protecting charitable assets for their intended purpose.”

Bonta and Delaware Attorney General Kathy Jennings also sent the company a letter expressing concerns about the safety of ChatGPT after meeting with OpenAI’s legal team earlier last week in Delaware, where OpenAI is incorporated.

“Together, we are particularly concerned with ensuring that the stated safety mission of OpenAI as a non-profit remains front and center,” Bonta said in a statement last week.

Microsoft invested its first $1 billion in OpenAI in 2019 and the two companies later formed an agreement that made Microsoft the exclusive provider of the computing power needed to build OpenAI’s technology. In turn, Microsoft heavily used the technology behind ChatGPT to enhance its own AI products.

The two companies announced on Jan. 21 that they were altering that agreement, enabling the smaller company to build its own computing capacity, “primarily for research and training of models.” That coincided with OpenAI’s announcements of a partnership with Oracle to build a massive new data center in Abilene, Texas.

But other parts of its agreements with Microsoft remained up in the air as the two companies appeared to veer further apart. Their Thursday joint statement said they were still “actively working to finalize contractual terms in a definitive agreement.” Both companies declined further comment.

OpenAI had given its nonprofit board of directors—whose members now include a former U.S. Treasury secretary—the responsibility of deciding when its AI systems have reached the point at which they “outperform humans at most economically valuable work,” a concept known as artificial general intelligence, or AGI.

Such an achievement, per its earlier agreements, would cut off Microsoft from the rights to commercialize such a system, since the terms “only apply to pre-AGI technology.”

OpenAI’s corporate structure and nonprofit mission are also the subject of a lawsuit brought by Elon Musk, who helped found the nonprofit research lab and provided initial funding. Musk’s suit seeks to stop OpenAI from taking control of the company away from its nonprofit and alleges it has betrayed its promise to develop AI for the benefit of humanity.

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A rough year for electric vehicle adoption just got a little rougher for owners in some parts of the US. Starting next month, EVs will no longer be able to ride in the fast lane in California, after the US federal government and Congress failed to reauthorize a popular program that has given hybrid and electric vehicles access to state carpool lanes—and worked to promote the sale of electrics for more than 25 years.

Under the program, California drivers with qualifying electric, plug-in hybrid, or hydrogen fuel cell vehicles could purchase $27 stickers that gave them access to several highway carpool lanes, plus discounts on a number of toll roads and bridges—even if a driver was alone in their car. Over 1 million decals have been issued to California drivers since the program’s start in 1999, and hundreds of thousands of vehicles have decals today.

However, those decals will no longer be valid after September 30, the California Department of Motor Vehicles said in a press release. Drivers who currently have stickers—even those who purchased them recently—won’t receive refunds, the department confirmed.

California isn’t alone. Another pilot project that gave some New York state electric-vehicle drivers access to carpool lanes will also end. Over 48,000 New Yorkers had received decals through that Clean Pass program.

The programs are ending because they were not reauthorized by the president and Congress, says Walter McClure, a spokesperson for the New York Department of Motor Vehicles. The White House did not respond to WIRED’s questions about why President Donald Trump chose not to reauthorize the program.

The end of the decal program is yet another knock back for US electric vehicles, which are facing long-term slower-than-projected sales in the country following a cut in government support for the newer car tech. EV-curious buyers have rushed to purchase new and used electric vehicles before tax credits, worth up to $7,500, end this month. But analysts expect that US sales will once again slow after the credit expires, even as the rest of the world continues its transition to EVs. Just a year ago, many analysts projected that between a quarter and a half of new US cars sold in 2030 would be electric; since then, those projections have been cut by half.

But while the California program’s end will likely frustrate plenty of EV drivers, it might not make a meaningful dent in the state’s transition to new-energy vehicles. The state has raced ahead of the rest of the country in EV adoption; 22 percent of new light-duty vehicles sold in the state so far this year have been battery-electric, plug-in hybrid, or hydrogen-powered, according to state data. Compare that to the projected 8 percent of new electrified vehicle sales for the rest of the country, and the reason for the program closure might become clearer—it seems the state’s carpool lanes were getting crowded.

The decal program “worked nicely as a bundle with monetary incentives,” says Gil Tal, the director of the Electric Vehicle Research Center at UC Davis, who has studied the effectiveness of the decal program over the past decade. “It was another reason to buy an electric car.”