Tag Archives: National Taiwan University

Clay film keeps your apples fresh

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Which apple would you like to eat?

Caption: Extent of decay in apples treated with clay film and cling wrap. Credit: Miharu Eguchi National Institute for Materials Science eguchi.miharu@nims.go.jp

This research into food packaging comes from Japan’s National Institute for Materials in a March 8, 2022 press release (also on EurekAlert but published on April 12, 2022),

An international research team consisting of NIMS, The University of Queensland and National Taiwan University has succeeded in creating a clay film with its gas permeability optimized for long-term storage of fresh produce by adjusting the sizes of the clay nanosheet particles comprising it. The team then uniformly coated the surfaces of various fruits with the film. This treatment kept the fruits’ respiration rates low without completely depriving them of oxygen, preventing them from decaying.

Efforts have been made to develop gas barrier films using clay nanosheets. Although some researchers attempted to improve the film properties of clay nanosheets by adding organic polymers to them, films can also be formed using only clay nanosheets without additives. Only a few studies had previously evaluated the physical properties of clay films composed solely of clay nanosheets.

This international joint research team focused on the gas permeability of clay films and found that a film composed of clay nanosheets with particle sizes in the range of several dozen nanometers (1 nm = one millionth of 1 mm) had relatively high permeability to gas molecules as they can pass through gaps between particles. This gas permeability is equivalent to that of plastic bags with minute pores used to store fresh produce. These bags are able to adequately reduce oxygen supply to fresh fruit, preventing it from ripening too rapidly. The gas permeability similarities between the clay film and the plastic bags inspired the research team to assess the ability of the clay film to preserve the quality of fresh produce for long periods of time.

In this research, the team applied a suspension of clay nanosheets to the surfaces of various fruits (e.g., apples, bananas and oranges) to form uniform films on their surfaces. The team also prepared untreated fruits and fruits covered in cling wrap for comparison. The gas emissions and appearance of these treated and untreated fruits were monitored for several months. As shown in the figure [above], the untreated apples (the first photo from the left) had decayed by the end of the experimental period and the apples covered only in cling wrap (the fourth photo from the left) had also decayed and grown mold. By contrast, the apples coated with the clay film (the two middle photos) did not decay or grew mold, presumably because the film reduced the external oxygen supply needed for ripening and mold growth. In addition, the clay film was confirmed to be in tight contact with the surfaces of the apples it coated, suggesting that it may be able to effectively block the diffusion of ethylene into the air, a phytohormone which plays an important role in inducing fruit ripening.

In addition to its potential ability to restrict the external oxygen supply and ethylene diffusion, the clay film may be able to prevent odor compounds produced by fresh produce from diffusing into the air, possibly making them less attractive to pests. In future research, the team plans to improve the ease of application and strength of the clay film to make it more suitable for preserving the quality of fresh produce during its transportation to the market.

This project was carried out by an international joint research team consisting of Miharu Eguchi (Senior Researcher, Mesoscale Materials Chemistry Group, International Center for Materials Nanoarchitectonics, NIMS) and researchers from The University of Queensland and National Taiwan University. This work was supported in part by  JST-ERATO Yamauchi Materials Space-Tectonics Project.

Here’s a link to and a citation for the paper,

Highly adhesive and disposable inorganic barrier films: made from 2D silicate nanosheets and water by Miharu Eguchi, Muxina Konarova, Nagy L. Torad, Te-An Chang, Dun-Yen Kang, Joe Shapter and Yusuke Yamauchi. J. Mater. Chem. A, 2022,10, 1956-1964 DOI: https://doi.org/10.1039/D1TA08837H First published 02 Dec 2021 Print version published January 28, 2022

This paper is behind a paywall.

The ‘Queen’s Head” in Yehliu Geopark (Taiwan) and nanotechnology

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http://focustaiwan.tw/news/asoc/201505250028.aspx

http://focustaiwan.tw/news/asoc/201505250028.aspx

As you can see, the Queen’s Head rests on a thin (and getting thinner) neck. This thinning is cause for consternation in Taiwan as a May 25, 2015 news item on the focustaiwan.tv website notes,

The “Queen’s Head,” the most famous rock formation in Yehliu Geopark, faces an uncertain fate despite an all-out effort to prevent its thinning neck from snapping, the North Coast & Guanyinshan National Scenic Area said Monday.

Kuo Chen-ling (郭振陵), the secretary-general of the scenic area administration, said Monday that experiments done on four mushroom rocks near the Queen’s Head have found that nanotechnology can prevent erosion, but it still has some drawbacks that have yet to be overcome.

In the experiments done over the past nine months, nanotechnology has proven that it could reinforce the queen’s neck and delay the weathering process, Kuo said.

But it has also caused the rocks to whiten and slivers of the rocks’ surfaces to break off amid the dramatic changes in temperature, moisture and sunshine on the North Coast, he said.

…

An August 29, 2014 news item on the China Post website gives a description of the attempted remedy,

The Tourism Bureau began preparations Thursday for repairs on the iconic Queen’s Head rock formation at Yehliu Geopark in New Taipei, in a bid to protect the popular tourist attraction from further erosion.

Capitalizing on the sunny weather, which is essential to an experiment on how best to preserve the rock, a group of specialists led by Hsieh Kuo huang, a professor at National Taiwan University’s Institute of Polymer Science and Engineering, injected various nano-sealants into four less-popular rock formations with a similar structure to the Queen’s Head.

The team has coded the rocks A, B, C and D and applied different treatments to them to compare the results.

…

Comprised of nano-sealant mixed with gravel, the remedy can help resist winds up to 250 kilometers per hour and magnitude-7.0 earthquakes, according to the Tourism Bureau.

I’m sorry the first tests were not more successful and I hope they will be able to find a solution in time.

This project reminded me of a European Union (EU) project where they too were attempting to save important stone structures, from my Oct. 21, 2014 posting,

… an Oct. 20, 2014 news item on Nanowerk,

Castles and cathedrals, statues and spires… Europe’s built environment would not be the same without these witnesses of centuries past. But, eventually, even the hardest stone will crumble. EU-funded researchers have developed innovative nanomaterials to improve the preservation of our architectural heritage.

“Our objective,” says Professor Gerald Ziegenbalg of IBZ Salzchemie, “was to find new possibilities to consolidate stone and mortar, especially in historical buildings.” The products available at the time, he adds, didn’t meet the full range of requirements, and some could actually damage the artefacts they were meant to preserve. Alternatives compatible with the original materials were needed.

For those interested in more, there are details about the EU project the product, CaLoSil, that the scientists devised, and links to more resources in my post.

Are you sure my artificial muscles don’t smell like onions?

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A May 5, 2015 news item on ScienceDaily highlights some research on artificial muscles from the National Taiwan University,

Just one well-placed slice into a particularly pungent onion can send even the most seasoned chef running for a box of tissues. Now, this humble root vegetable is proving its strength outside the culinary world as well — in an artificial muscle created from onion cells. Unlike previous artificial muscles, this one, created by a group of researchers from National Taiwan University, can either expand or contract to bend in different directions depending on the driving voltage applied.

A May 5, 2015 American Institute of Physics (AIP) news release by Laurel Hamers,  which originated the news item, describes the research goals,

“The initial goal was to develop an engineered microstructure in artificial muscles for increasing the actuation deformation [the amount the muscle can bend or stretch when triggered],” said lead researcher Wen-Pin Shih. “One day, we found that the onion’s cell structure and its dimensions were similar to what we had been making.” Shih lead the study along with graduate student Chien-Chun Chen and their colleagues.

The onion epidermis — the fragile skin found just beneath the onion’s surface — is a thin, translucent layer of blocky cells arranged in a tightly-packed lattice. Shih and his colleagues thought that onion epidermal cells might be a viable candidate for the tricky task of creating a more versatile muscle that could expand or contract while bending. To date, Shih said, artificial muscles can either bend or contract, but not at the same time.

The researchers treated the cells with acid to remove the hemicellulose, a protein that makes the cell walls rigid. Then, they coated both sides of the onion layer with gold. When current flowed through the gold electrodes, the onion cells bent and stretched much like a muscle.

“We intentionally made the top and bottom electrodes a different thickness so that the cell stiffness becomes asymmetric from top to bottom,” said Shih. The asymmetry gave the researchers control over the muscle’s response: a low voltage made them expand and flex downwards, towards the thicker bottom layer. A high voltage, on the other hand, caused the cells to contract and flex upwards, towards the thinner top layer.

“We found that the single-layer lattice structure can generate unique actuation modes that engineered artificial muscle has never achieved before,” said Shih.

To demonstrate their device’s utility, the researchers combined two onion muscles into a pair of tweezers, which they used to pick up a cotton ball. In the future, they hope to increase the lifting power of their artificial muscles. “Our next step is to reduce the driving voltage and the actuating force,” said Shih.

Here’s a link to and a citation for the paper,

Onion artificial muscles by Chien-Chun Chen, Wen-Pin Shih, Pei-Zen Chang, Hsi-Mei Lai, Shing-Yun Chang, Pin-Chun Huang and Huai-An Jeng. Appl. Phys. Lett. 106, 183702 (2015); http://dx.doi.org/10.1063/1.4917498

This appears to be open access.