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Researchers create the most water-repellent surface ever

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A revised method to create hydrophobic surfaces has implications for any technology where water meets a solid surface, from optics and microfluidics to cooking

An artist’s depiction of the liquid-like layer of molecules repelling water droplets.
« Researchers create the most water-repellent surface ever Image Credit: Ekaterina Osmekhina/Aalto University

Newswise — Researchers have developed a new mechanism to make water droplets slip off surfaces, described in a paper published in Nature Chemistry. The discovery challenges existing ideas about friction between solid surfaces and water and opens up a new avenue for studying droplet slipperiness at the molecular level. The new technique has applications in a range of fields, including plumbing, optics, and the auto and maritime industries.

All around us, water is always interacting with solid surfaces. Cooking, transportation, optics and hundreds of other technologies are affected by how water sticks to surfaces or slides off them. Understanding the molecular dynamics of these microscopic droplets helps scientists and engineers find ways to improve many household and industrial technologies.

Liquid-like surfaces are a new type of droplet-repellent surface that offer many technical benefits over traditional approaches—a topic recently reviewed in Nature Reviews Chemistry by Aalto University professor Robin Ras. They have molecular layers that are highly mobile yet covalently tethered to the substrate, giving solid surfaces a liquid-like quality that acts like a layer of lubricant between the water droplets and the surface itself. A research team led by Ras used a specially-designed reactor to create a liquid-like layer of molecules, called self-assembled monolayers (SAMs), on top of a silicon surface.

Watching self-assembled monolayers grow

‘Our work is the first time that anyone has gone directly to the nanometer-level to create molecularly heterogenous surfaces,’ says doctoral researcher Sakari Lepikko, lead author of the study.

By carefully adjusting conditions such as temperature and water content inside the reactor, the team could fine-tune how much of the silicon surface the monolayer covered.

‘I find it very exciting that by integrating the reactor with an ellipsometer, that we can watch the self-assembled monolayers grow with extraordinary level of detail,’ says Ras.

‘The results showed more slipperiness when SAM coverage was low or high, which are also the situations when the surface is most homogeneous. At low coverage, the silicon surface is the most prevalent component, and at high, SAMs are the most prevalent.’

‘It was counterintuitive that even low coverage yielded exceptional slipperiness,’ Lepikko continues.

At low coverage, the water becomes a film over the surface, which had been thought to increase the amount of friction. ‘We found that, instead, water flows freely between the molecules of the SAM at low SAM coverage, sliding off the surface. And when the SAM coverage is high, the water stays on top of the SAM and slides off just as easily. It’s only in between these two states that water adheres to the SAMs and sticks to the surface.”

The new method proved exceptionally effective, as the team created the slipperiest liquid surface in the world.

Anti-fogging, de-icing, self-cleaning

The discovery promises to have implications wherever droplet-repellent surfaces are needed. According to Lepikko, this covers hundreds of examples from daily life to industrial solutions.

‘Things like heat transfer in pipes, de-icing and anti-fogging are potential uses. It will also help with microfluidics, where tiny droplets need to be moved around smoothly, and with creating self-cleaning surfaces. Our counterintuitive mechanism is a new way to increase droplet mobility anywhere it’s needed,’ Lepikko says.

Next, the team plans to continue experimenting with their self-assembling monolayer setup and improve the layer itself. Lepikko is particularly excited about the information this work has provided for future innovations.

‘The main issue with a SAM coating is that it’s very thin, and so it disperses easily after physical contact. But studying them gives us fundamental scientific knowledge which we can use to create durable practical applications.’

The research used the national research infrastructure OtaNano was carried out by the Soft Matter and Wetting group at the Department of Applied Physics, which has also produced other pioneering water-repellent materials.

Researchers from the University of Jyväskylä also contributed to this study.

Source: Aalto University

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Black History

The Legacy of Garrett Augustus Morgan Sr.: A Trailblazer in Invention, Business, and Community Leadership

Garrett Augustus Morgan Sr.: Inventor, businessman, and community leader whose legacy continues to inspire generations with his groundbreaking contributions.

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Garrett Augustus Morgan Sr., a prominent figure in American history, left an indelible mark through his remarkable contributions as an inventor, businessman, and community leader. Born on March 4, 1877, Morgan’s legacy continues to inspire generations.


One of Morgan’s most renowned inventions was the three-way traffic light, a pivotal innovation that revolutionized road safety and traffic management. Additionally, his creation of the protective ‘smoke hood’ proved instrumental during the 1916 tunnel construction disaster rescue, saving numerous lives and highlighting his commitment to public safety.

Beyond his inventions, Morgan ventured into the realm of haircare, developing a groundbreaking chemical hair-processing solution that led to the establishment of the successful “G. A. Morgan Hair Refining Company.” His entrepreneurial spirit and dedication to innovation paved the way for a complete line of haircare products.

Morgan’s influence extended beyond the business world; he actively engaged in the civic and political advancement of African Americans, particularly in Cleveland, Ohio, and surrounding areas. His efforts exemplified a commitment to fostering positive change and empowerment within his community.

In recognition of his significant contributions, several institutions and landmarks bear Morgan’s name, honoring his legacy. From the Garrett A. Morgan Cleveland School of Science to the Garrett A. Morgan Water Treatment Plant, his impact is immortalized in various locations across the United States.

Notably, Morgan’s legacy was nationally recognized at the Emancipation Centennial Celebration in Chicago in August 1963, underscoring his enduring influence and importance in American history. His inclusion in the book “100 Greatest African Americans” by Molefi Kete Asante further solidifies his place among the most influential figures in African American history.

Morgan’s inventions continue to captivate audiences, with his safety hood featured on popular television shows like “Inventions that Shook the World” and “Mysteries at the Museum,” showcasing the lasting impact of his innovations on society.

As an honorary member of Alpha Phi Alpha fraternity, Morgan’s dedication to excellence and service continues to inspire individuals to strive for greatness and make a positive difference in their communities.

The remarkable life and achievements of Garrett Augustus Morgan Sr. serve as a testament to the power of innovation, entrepreneurship, and advocacy, leaving a lasting legacy that resonates with generations past, present, and future.

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NASA Tech Contributes to Soft Moon Landing, Agency Science Underway

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For the first time in more than 50 years, new NASA science instruments and technology demonstrations are operating on the Moon following the first successful delivery of the agency’s CLPS (Commercial Lunar Payload Services) initiative.

On Feb. 22, 2024, Intuitive Machines’ Odysseus lunar lander captures a wide field of view image of Schomberger crater on the Moon approximately 125 miles (200 km) uprange from the intended landing site, at approximately about 6 miles (10 km) altitude.
Credit: Intuitive Machines

Intuitive Machines’ Nova-C lander, called Odysseus, completed a seven-day journey to lunar orbit and executed procedures to softly land near Malapert A in the South Pole region of the Moon at 5:24 p.m. CST on Feb. 22. The lander is healthy, collecting solar power, and transmitting data back to the company’s mission control in Houston. The mission marks the first commercial uncrewed landing on the Moon.

Carrying six NASA science research and technology demonstrations, among other customer payloads, all NASA science instruments completed transit checkouts en route to the Moon. A NASA precision landing technology demonstration also provided critical last-minute assistance to ensure a soft landing. As part of NASA’s Artemis campaign, the lunar delivery is in the region where NASA will send astronauts to search for water and other lunar resources later this decade.

“For the first time in more than half a century, America returned to the Moon. Congratulations to Intuitive Machines for placing the lunar lander Odysseus carrying NASA scientific instruments to a place no person or machine has gone before, the lunar South Pole,” said NASA Administrator Bill Nelson. “This feat from Intuitive Machines, SpaceX, and NASA demonstrates the promise of American leadership in space and the power of commercial partnerships under NASA’s CLPS initiative. Further, this success opens the door for new voyages under Artemis to send astronauts to the Moon, then onward to Mars.” 

During the journey to the Moon, NASA instruments measured the quantity of cryogenic engine fuel as it has been used, and while descending toward the lunar surface, teams collected data on plume-surface interactions and tested precision landing technologies.

Odysseus’ surface operations are underway and expected to take place through Thursday, Feb. 29.

New lunar science, technology

NASA’s Navigation Doppler Lidar for Precise Velocity and Range Sensing (NDL) guidance system for descent and landing ultimately played a key role in aiding the successful landing. A few hours ahead of landing, Intuitive Machines encountered a sensor issue with their navigation system and leaned on NASA’s guidance system for an assist to precisely land. NASA’s instrument operates on the same principles of radar and uses pulses from a laser emitted through three optical telescopes. It measures speed, direction, and altitude with high precision during descent and touchdown.

“We are thrilled to have NASA on the Moon again, and proud of the agency’s contribution to the successful landing with our NDL technology. Congratulations for completing this first lunar delivery for NASA, paving the way for a bright future for our CLPS initiative,” said Nicky Fox. “Some of the NASA science instruments on this mission will bring us insight on lunar plume interactions and conduct radio astronomy. The valiant efforts and innovation demonstrated by Intuitive Machines is exemplary and we are excited for the upcoming lunar deliveries that will follow this first mission.”  

Now that they are on the lunar surface, NASA instruments will focus on investigating lunar surface interactions and radio astronomy. The Odysseus lander also carries a retroreflector array that will contribute to a network of location markers on the Moon for communication and navigation for future autonomous navigation technologies.

Additional NASA hardware aboard the lander includes:

  • Lunar Node 1 Navigation DemonstratorA small, CubeSat-sized experiment that will demonstrate autonomous navigation that could be used by future landers, surface infrastructure, and astronauts, digitally confirming their positions on the Moon relative to other spacecraft, ground stations, or rovers on the move.
  • Laser Retroreflector Array: A collection of eight retroreflectors that enable precision laser ranging, which is a measurement of the distance between the orbiting or landing spacecraft to the reflector on the lander. The array is a passive optical instrument and will function as a permanent location marker on the Moon for decades to come.   
  • Radio Frequency Mass Gauge: A technology demonstration that measures the amount of propellant in spacecraft tanks in a low-gravity space environment. Using sensor technology, the gauge will measure the amount of cryogenic propellant in Nova-C’s fuel and oxidizer tanks, providing data that could help predict fuel usage on future missions.   
  • Radio-wave Observations at the Lunar Surface of the Photoelectron Sheath: The instrument will observe the Moon’s surface environment in radio frequencies, to determine how natural and human-generated activity near the surface interacts with and could interfere with science conducted there.
  • Stereo Cameras for Lunar Plume-Surface Studies: A suite of four tiny cameras to capture imagery showing how the Moon’s surface changes from interactions with the spacecraft’s engine plume during and after descent.

NASA is committed to supporting its U.S. commercial vendors as they navigate the challenges of sending science and technology to the surface of the Moon.

“In daring to confront one of humanity’s greatest challenges, Intuitive Machines created an entire lunar program that has ventured farther than any American mission to land on the Moon in over 50 years,” said Altemus. “This humbling moment reminds us that pursuing the extraordinary requires both boldness and resilience.”

For more information about CLPS, visit:

https://www.nasa.gov/clps

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astronomy

The Enigmatic Zodiacal Light: A Celestial Phenomenon Around the March Equinox

Witness the ethereal glow of the zodiacal light around the March equinox, a celestial spectacle connecting us to the mysteries of the cosmos.

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As the March equinox approaches, a mystical glow known as the zodiacal light graces the evening sky, captivating skywatchers with its ethereal presence. This luminous cone, visible just after twilight fades, enchants those in the Northern Hemisphere from late February to early March. Glimpsing this elusive spectacle requires a keen eye and a dark sky, offering a unique connection to the cosmos.

What is a false dawn?

The zodiacal light, often mistaken for lingering twilight or distant city lights, holds a fascinating origin story. It arises from sunlight reflecting off dust grains orbiting the sun in the inner solar system. Initially thought to be remnants from our solar system’s formation, recent theories suggest a Martian origin. These dust grains, ranging from millimeter-sized to micron-sized, form a delicate pathway mirroring the sun and moon’s journey across the ecliptic, the plane of our solar system.

For stargazers in the Southern Hemisphere, the zodiacal light presents itself as a hazy pyramid in the east before dawn, offering a celestial dance of light and shadow. Capturing this celestial ballet on camera can be a rewarding experience, showcasing the beauty of our interconnected universe.

The best times to witness this cosmic display vary with the seasons. Spring heralds the zodiacal light in the evening, while autumn reveals its splendor before dawn. The optimal viewing window extends from late August to early November in the Northern Hemisphere and from late February to early May in the Southern Hemisphere, aligning with the equinoxes.

To behold this enigmatic light, one must seek out a dark sky location, free from the glare of city lights. The zodiacal light’s milky radiance surpasses that of the summer Milky Way, offering a serene and awe-inspiring sight. Whether observed after dusk in spring or before dawn in autumn, this celestial phenomenon promises a glimpse into the vastness of our solar system.

As we marvel at the zodiacal light’s gentle glow, we are reminded of the interconnectedness of Earth and the cosmos. So, next time you find yourself under a starlit sky around the equinox, remember to cast your gaze towards the heavens and witness the celestial dance of the zodiacal light.

Source: EarthSky

https://earthsky.org/astronomy-essentials/zodiacal-light-false-dusk-how-to-see-explanation/
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