When two substances are brought together, they will eventually settle into a steady state called thermodynamic equilibrium; examples include oil floating on top of water and milk mixing uniformly into coffee. Researchers at Aalto University in Finland wanted to disrupt this sort of state to see what happens—and whether they can control the outcome.
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In their work, the team used combinations of oils with different dielectric constants and conductivities. They then subjected the liquids to an electric field.
“When we turn on an electric field over the mixture, electrical charge accumulates at the interface between the oils. This charge density shears the interface out of thermodynamic equilibrium and into interesting formations,” explains Dr. Nikos Kyriakopoulos, one of the authors of the paper. As well as being disrupted by the electric field, the liquids were confined into a thin, nearly two-dimensional sheet. This combination led to the oils reshaping into various completely unexpected droplets and patterns.
The droplets in the experiment could be made into squares and hexagons with straight sides, which is almost impossible in nature, where small bubbles and droplets tend to form spheres. The two liquids could be also made to form into interconnected lattices: grid patterns that occur regularly in solid materials but are unheard of in liquid mixtures. The liquids can even be coaxed into forming a torus, a donut shape, which was stable and held its shape while the field was applied—unlike in nature, as liquids have a strong tendency to collapse in and fill the hole at the center. The liquids can also form filaments that roll and rotate around an axis.
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The research was carried out at the Department of Applied Physics in the Active Matter research group, led by Professor Timonen. The paper “Diversity of non-equilibrium patterns and emergence of activity in confined electrohydrodynamically driven liquids” is published open-access in Science Advances.
More information: Diversity of non-equilibrium patterns and emergence of activity in confined electrohydrodynamically driven liquids, Science Advances (2021). DOI: 10.1126/sciadv.abh1642
Aggrieved MacBook owners in two separate lawsuits claim Apple’s latest laptops with its M1 chips have defective screens that break easily and malfunction.
The complaints, both filed on Wednesday in a federal district court in San Jose, California, are each seeking class certification in the hope that the law firms involved will get a judicial blessing to represent the presumed large group of affected customers and, if victorious, to share any settlement.
Each of the filings contends Apple’s 2020-2021 MacBook line – consisting of the M1-based MacBook Air and M1-based 13″ MacBook Pro – have screens that frequently fail. They say Apple knew about the alleged defect or should have known, based on its own extensive internal testing, reports from technicians, and feedback from customers.
“[T]he M1 MacBook is defective, as the screens are extraordinarily fragile, cracking, blacking out, or showing magenta, purple and blue lines and squares, or otherwise ceasing to function altogether,” says a complaint filed on behalf of plaintiff Nestor Almeida [PDF]. “Thousands of users from across the globe have reported this issue directly to Apple and on Apple sponsored forums.”
Photograph from one of the lawsuits of a broken screen, redacted by the owner … Click to enlarge
The other complaint [PDF], filed on behalf of plaintiffs Daphne Pareas and Daniel Friend, makes similar allegations.
“The Class Laptops are designed and manufactured with an inherent defect that compromises the display screen,” it says. “During ordinary usage the display screens of the Class Laptops (1) may become obscured with black or gray bars and/or ‘dead spots’ where no visual output is displayed and (2) are vulnerable to cracks that obscure portions of the display. The appearance of black or gray bars on screen may precede, accompany, or follow cracks in the display glass.”
The Almeida complaint says thousands of Apple customers from around the world have reported MacBook screen problems to Apple and in online forums. It claims Apple has often refused to pay for repairs, forcing customers to pay as much as $850 through outside vendors. And where Apple has provided repairs, some customers have seen the problems return.
When two substances are brought together, they will eventually settle into a steady state called thermodynamic equilibrium; examples include oil floating on top of water and milk mixing uniformly into coffee. Researchers at Aalto University in Finland wanted to disrupt this sort of state to see what happens—and whether they can control the outcome.
