At extremely small scales, looks can be deceiving. While at first glance you might see lily pads floating on a tranquil pond, this image is actually a clever adaptation of a snapshot taken on a scanning electron microscope.
In reality, the green spots are only a few micrometers across—smaller than width of a human hair. They make up a surface coating that was developed to limit the transmission of SARS-CoV-2, the virus that causes COVID-19. The coating is composed of a silver-based material applied to a glass surface. The lotus flower, though, was some added artistic flair courtesy of image-editing software.
Mohsen Hosseini, Ph.D. candidate in chemical engineering, and William Ducker, professor of chemical engineering, recently won an award in the National Nanotechnology Coordinated Infrastructure (NNCI) image contest with this image. Both Hosseini and Ducker are affiliated with the Macromolecules Innovation Institute (MII).
Improving the sensitivity of light sensors or the efficiency of solar cells requires fine-tuning of light capturing. KAUST researchers have used complex geometry to develop tiny shell-shaped coverings that can increase the efficiency and speed of photodetectors.
Many optical-cavity designs have been investigated to seek efficiencies of light: either by trapping the electromagnetic wave or by confining light to the active region of the device to increase absorption. Most employ simple micrometer- or nanometer-scale spheres in which the light propagates around in circles on the inside of the surface, known as a whispering gallery mode.
Former KAUST scientist Der-Hsien Lien, now a postdoctoral researcher at the University of California, Berkeley, and his colleagues from China, Australia and the U.S. demonstrate that a more complex geometry comprising convex nanoscale shells improves the performance of photodetectors by increasing the speed at which they operate and enabling them to detect light from all directions.
Surface effects play an important role in the operation of some devices, explains KAUST principal investigator, Jr-Hau He. Nanomaterials offer a way to improve performance because of their high surface-to-volume ratio. “However, although nanomaterials have greater sensitivity in light detection compared to the bulk, the light–matter interactions are weaker because they are thinner,” describes He. “To improve this, we design structures for trapping light.”
A recent study by researchers from the Chinese Academy of Sciences redefines how liquids maintain their contact with solid surfaces—also known as wettability—from an intermolecular force perspective.
The findings were published in Nano Research on Feb 8.
Wettability is relevant to the design of materials because it determines how layers stick together. Says study author and professor Ye Tian from the Key Laboratory of Bio-inspired Materials and Interfacial Science, it “plays a crucial role in many fields, such as the efficiency of catalytic reaction, separation, electrode materials, and the design of bionic smart materials.” For example, smart layers that change their contact depending on moisture could be used in sportswear that adapts to humidity.
Wettability models
Highwettability means that a liquid drop spreads, creating a low angle of contact with the surface, whereas low wettability describes a liquid that resists spreading. Classically, wettability, as indicated by contact angle, is characterized using Young’s equation, which models an ideal, perfectly smooth surface. If the water droplet spreads out to a contact angle lower than 90 degrees, the surface is categorized as hydrophilic or water-loving. If the water droplet makes a contact angle higher than 90 degrees, the surface is categorized as hydrophobic.
One of the most enduring “Holy Grail” experiments in science has been attempts to directly observe atomic motions during structural changes. This prospect underpins the entire field of chemistry because a chemical process occurs during a transition state—the point of no return separating the reactant configuration from the product configuration.
What does that transition state look like and, given the enormous number of different possible nuclear configurations, how does a system even find a way to make it happen?
Now in the journal Applied Physics Letters, researchers at the Max Planck Institute for the Structure and Dynamics of Matter are reporting “ultrabright” electron sources with sufficient brightness to literally light up atomic motions in real time—at a time scale of 100 femtoseconds, making these sources particularly relevant to chemistry because atomic motions occur in that window of time.
After seeing the first atomic movies of phase transitions in bulk thin films using high-energy (100 kilovolt) electron bunches, the researchers wondered if they could achieve atomic resolution of surface reactions—occurring within the first few monolayers of materials—to gain a better understanding of surface catalysis.
Scientists at the University of Basel have found a way to change the spatial arrangement of bipyridine molecules on a surface. These potential components of dye-sensitized solar cells form complexes with metals and thereby alter their chemical conformation. The results of this interdisciplinary collaboration between chemists and physicists from Basel were recently published in the scientific journal ACS Omega.
Dye-sensitized solar cells have been considered a sustainable alternative to conventional solar cells for many years, even if their energy yield is not yet fully satisfactory. The efficiency can be increased with the use of tandem solar cells, where the dye-sensitized solar cells are stacked on top of each other.
The way in which the dye, which absorbs sunlight, is anchored to the semiconductor plays a crucial role in the effectiveness of these solar cells. However, the anchoring of the dyes on nickel oxide surfaces – which are particularly suitable for tandem dye-sensitized cells – is not yet sufficiently understood.
Texas A&M AgriLife Research and the Texas A&M Engineering Experiment Station, TEES, were recently awarded a grant from the U.S. Department of Agriculture’s National Institute of Food and Agriculture to study and develop super-repellent and anti-fouling surfaces for foods.
The grant will be used in their collaboration to help ensure the safety of fresh food products, benefiting both consumers and the produce industry.
“There is a need to reduce those outbreaks associated with microbial contamination that may take place in different operations along the fresh produce chain,” said Dr. Luis Cisneros-Zevallos, AgriLife Research food scientist in College Station and co-principal investigator for the project. “The surfaces we are designing avoid cross-contamination and reduce the risk of biofilm formation.”
“In recent years, we have developed various types of nanotechnology-based coating with an intriguing combination of surface texture and chemistry to inhibit and prevent the attachment of microorganisms on plastics, metals, ceramic and glass at the laboratory scale,” said Dr. Mustafa Akbulut, TEES chemical engineer in College Station and principal investigator for the project.
Two key physical phenomena take place at the surfaces of materials: catalysis and wetting. A catalyst enhances the rate of chemical reactions; wetting refers to how liquids spread across a surface.
Now researchers at MIT and other institutions have found that these two processes, which had been considered unrelated, are in fact closely linked. The discovery could make it easier to find new catalysts for particular applications, among other potential benefits.
“What’s really exciting is that we’ve been able to connect atomic-level interactions of water and oxides on the surface to macroscopic measurements of wetting, whether a surface is hydrophobic or hydrophilic, and connect that directly with catalytic properties,” says Yang Shao-Horn, the W.M. Keck Professor of Energy at MIT and a senior author of a paper describing the findings in the Journal of Physical Chemistry C. The research focused on a class of oxides called perovskites that are of interest for applications such as gas sensing, water purification, batteries, and fuel cells.
Since determining a surface’s wettability is “trivially easy,” says senior author Kripa Varanasi, an associate professor of mechanical engineering, that determination can now be used to predict a material’s suitability as a catalyst. Since researchers tend to specialize in either wettability or catalysis, this produces a framework for researchers in both fields to work together to advance understanding, says Varanasi, whose research focuses primarily on wettability; Shao-Horn is an expert on catalytic reactions.
Lithium nickel manganese cobalt oxide, or NMC, is one of the most promising chemistries for better lithium batteries, especially for electric vehicle applications, but scientists have been struggling to get higher capacity out of them. Now researchers at Lawrence Berkeley National Laboratory…
Semi-Fluorinated Alcanes on HOPG. Maps of Topography, Surface Potential, Dielectric response and dC/dV which were obtained using multiple lock-in scheme characterize local electrostatic properties at the nanometer scale. Sample courtesy: Dr. M. Moeller (#DWI Aachen) Image courtesy: Dr. Sergey Magonov, #ntmdt #next #afm #microscope #nanotechnology #polymers #science by ntmdt http://bit.ly/1J0iUkc
The Olympic Charter declares that winter sports must be practiced on snow or ice. Both are frozen forms of water, which despite its ubiquity, is one of the strangest substances around. In addition to its tendency to expand as it freezes, ice is inherently slippery, and no one’s quite certain yet why.
Most people have heard the theory that ice skating is possible due to high pressure melting the ice beneath the narrow blade. But realistically, pressure melting should only work for ice down to about -3.5 degrees Celsius. By contrast, the ideal temperatures for figure skating and ice hockey are -5.5 and -9 degrees Celsius, respectively. Melting due to friction might account for slipperiness a few more degrees below freezing, but it doesn’t explain why ice can be slippery when you’re just standing on it.
When physicist Michael Faraday suggested in 1850 that ice has a thin liquid-like layer at its surface, many discounted the theory. But modern experimental techniques and computer simulations have shown that Faraday was right. Ice has a liquid-like layer some 1 to 100 nanometers thick at its surface, and this layer persists to temperatures below -30 degrees Celsius. The process is known as surface pre-melting and what causes it is an area of active research for physical chemists. Current theories include hydrogen bonding and even quantum mechanical effects. (Image credit: AP Photo/B. Armangue; research credit: R. Rosenberg;Y. Li and G. Somorjai;F. Paesani and G. Voth)
This opens FYFD’s two-week series on the physics and fluid dynamics of the Winter Olympics. Stay tuned! - Nicole
When molecules interact with solid surfaces, a whole range of dynamic processes can take place. These are of enormous interest in the context of catalytic reactions, e.g. the conversion of natural gas into hydrogen that can then be used to generate clean electricity.
Specifically, the interaction of methanemolecules with catalyst surface such as nickel is of interest if we are to gain a detailed and meaningful understanding of the process on a molecular level. But studying scattering dynamics of polyatomic molecules such as methane has been challenging because current detection techniques are unable to resolve all the quantum states of the scattered molecules.
The lab of Rainer Beck at EPFL has now used novel infrared laser techniques to study methane scattering on a nickel surface for the first time with full quantum-state resolution. Quantum-state resolved techniques have contributed much to our understanding of surface-scattering dynamics, but the innovation here was that the EPFL team was able to extend such studies to methane by combining infrared lasers with a cryogenic bolometer: a highly sensitive heat detector cooled to 1.8 K that can pick up the kinetic and internal energy of the incoming methane molecules.
With the autumn and winter months upon us in the northern hemisphere, it’s time for a bit of hygge! I had originally thought this little set would become something bigger, so it’s been sitting around half-done for awhile now, but ‘tis the season, so I’ll just release what I have! I give my deepest apologies to all who get annoyed that the world has taken the Danish concept of cosiness and turned it into an aesthetic, but man I love it so much.
Chevron Door | 11 swatches base game compatible
Painted Front Door | 20 swatches base game compatible
Folk Art Tile | 16 swatches base game compatible
Blanket Stack | 24 swatches base game compatible
Sleek End Table | 16 swatches requires Get to Work
A little set with a few of my favorite items, all recolored in that hipster Pinterest aesthetic that I love so well, but can’t afford IRL. I wanted them to all feel like you could pick them up at a flea market or thrift store, and with a little bit of paint, really make them your own!
Vintage Dresser
requires Parenthood
26 swatches - 16 solids in @plumbobteasociety‘s Cottage garden palette, and 10 in Rifle Paper Co patterns
I am excited to finally share the LOTTIE BEDROOM set! Embrace the comfy vibes with boho-inspired pieces from this new collection of bedroom items. The set features both functional and décor buy mode objects.
MeetARRIE OFFICE – a set of 10 contemporary office objects. The set features both functional and décor buy mode objects. Today also happens to be my birthday, so I am excited to celebrate it with this release!
Sometimes I just run with an idea because it’s so good I just need more of it. Hamptons was a good example, and the same can be said for Hinterlands. This week, it’s a (bit delayed) dining collection. I really don’t have enough country styles in my catalogue, so having more is really nice.
