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Research

Jun 26th, 2024
Tel Aviv University Shatters Limits with Self-Healing Glass

TAU researchers create transparent, self-healing adhesive glass that forms in contact with water.

  • Life Sciences
  • Engineering

Researchers from TAU have created a new type of glass with unique and even contradictory properties, such as being a strong adhesive (sticky) and incredibly transparent at the same time. The glass, which forms spontaneously when in contact with water at room temperature, could revolutionize in an array of diverse industries such as optics and electro-optics, satellite communication, remote sensing and biomedicine. The glass has been discovered by a team of researchers from Israel and the world, led by PhD student Gal Finkelstein-Zuta and Prof. Ehud Gazit from the Shmunis School of Biomedicine and Cancer Research at the Faculty of Life Sciences and the Department of Materials Science and Engineering at the Faculty of Engineering at TAU. The research results were published last week in the prestigious scientific journal Nature.

 

"In our laboratory, we study bio-convergence and specifically use the wonderful properties of biology to produce innovative materials", explains Prof. Gazit. “Among other things, we study sequences of amino acids, which are the building blocks of proteins. Amino acids and peptides have a natural tendency to connect and form ordered structures with a defined periodic arrangement, but during the research, we discovered a unique peptide that behaves differently from anything we know: it didn’t form any ordered pattern but an amorphous, disordered one, that describes glass".

 

(Left to right) Gal Finkelstein-Zuta and Prof. Ehud Gazit.

 

Just Add Water

At the molecular level, glass is a liquid-like substance that lacks order in its molecular structure. Still, its mechanical properties are solid-like. Glass is usually manufactured by rapidly cooling molten materials and “freezing” them in this state before they are allowed to crystallize, resulting in an amorphous state that allows unique optical, chemical and mechanical properties – alongside durability, versatility, and sustainability. The researchers from TAU discovered that the aromatic peptide, which consists of a three-tyrosine sequence (YYY), forms a molecular glass spontaneously, upon evaporation of an aqueous solution, under room-temperature conditions.

 

"The commercial glass we all know is created by the rapid cooling of molten materials, a process called vitrification", says Gal Finkelstein-Zuta. "The amorphous liquid-like organization should be fixed before it arranges in a more energy-efficient way as in crystals, and for that energy is required – it should be heated to high temperatures and cooled down immediately. On the other hand, the glass we discovered made of biological building blocks, forms spontaneously at room temperature, without the need for energy such as high heat or pressure. Just dissolve a powder in water – just like making Kool-Aid, and the glass will form. For example, we made lenses from our new glass. Instead of undergoing a lengthy process of grinding and polishing, we simply dripped a drop onto a surface, where we control its curvature – and hence its focus – by adjusting the solution volume alone".

 

Solid peptide glass after preparation.

 

The properties of the innovative glass from TAU are unique in the world – and even contradict each other: it is very hard, but it can repair itself at room temperature; It is a strong adhesive, and at the same time, it is transparent in a wide spectral range, ranging from the visible light to the mid-infrared range.

 

An Unbreakable Marvel

"This is the first time anyone has succeeded in creating molecular glass under simple conditions", says Prof. Gazit, "but not less important than that are the properties of the glass we created. It is a very special glass. On the one hand, it is very strong and on the other hand, very transparent – much more transparent than ordinary glass. The normal silicate glass we all know is transparent in the visible light range, the molecular glass we created is transparent deep into the infrared range. This has many uses in fields such as satellites, remote sensing, communications and optics. It is also a strong adhesive, it can glue different glasses together, and at the same time, can repair cracks that are formed in it. It is a set of properties that do not exist in any glass in the world, which has great potential in science and engineering, and we got all this from a single peptide - one little piece of protein".

Research

Jun 16th, 2024
Why Did Early Humans Prefer to Hunt Near Water Sources?

Elephant Hunting and Stone Quarries in the Paleolithic Era

  • Humanities
  • Archeology

Archaeologists from Tel Aviv University have uncovered the mystery surrounding extensive Paleolithic stone quarrying and tool-making sites: Why did Homo erectus repeatedly revisit the very same locations for hundreds of thousands of years? The answer lies in the migration routes of elephants, which they hunted and dismembered using flint tools crafted at these quarrying sites.

 

The research was led by Dr. Meir Finkel and Prof. Ran Barkai of Tel Aviv University’s Jacob M. Alkow Department of Archaeology and Ancient Near Eastern Cultures. The study was published in the journal Archaeologies.

 

Prof. Ran Barkai.

 

Prof. Ran Barkai explains: “Ancient humans required three things: water, food, and stone. While water and food are necessities for all creatures, humans relied on stone tools to hunt and butcher animals, as they lacked the sharp claws or fangs of other predators. The question is, why do we find rock outcrops that were used for the production of flint tools, surrounded by thousands of stone tools, and next to them rock outcrops containing flint that was not used for the production of tools? A study of indigenous groups that lived until recently, with some still alive today, shows that hunter-gatherers attribute great importance to the source of the stone — the quarry itself — imbuing it with potency and sanctity, and hence also spiritual worship. People have been making pilgrimages to such sites for generations upon generations, leaving offerings at the rock outcrop, while adjacent outcrops, equally suitable for stone tool production, remain untouched. We sought to understand why; what is special about these sites?”

 

How did elephant migration routes affect prehistoric quarry locations?

For nearly 20 years, Prof. Barkai and his colleagues have been researching flint quarrying and tool-making sites in the Upper Galilee. These sites are characterized by large nodules of flint convenient for crafting and are located within walking distance of the major Paleolithic sites of the Hula Valley — Gesher Benot Ya’akov and Ma’ayan Baruch. These sites boast thousands of quarrying and extraction localities where, until half a million years ago, in the Lower Paleolithic period, prehistoric humans fashioned tools and left offerings, despite the presence of flint in other geological formations in various places. Because elephants were the primary dietary component for these early humans, the Tel Aviv University researchers cross-referenced the database of the sites’ distribution with the database of the elephants’ migration routes and discovered that the flint quarrying and knapping sites were situated in rock outcrops near the elephants’ migration paths.

 

“An elephant consumes 400 liters of water a day on average, and that’s why it has fixed movement paths,” says Dr. Finkel. “These are animals that rely on a daily supply of water, and therefore on water sources — the banks of lakes, rivers and streams. In many instances, we discover elephant hunting and processing sites at “necessary crossings” — where a stream or river passes through a steep mountain pass, or when a path along a lakeshore is limited to the space between the shore and a mountain range. At the same time, given the absence of available means of preservation and the presence of predatory animals in the area, the window of opportunity for a group of hunter-gatherers to exhaust their elephant prey was limited. Therefore, it was imperative to prepare suitable cutting tools in large quantities in advance and nearby. For this reason, we find quarrying and knapping sites in the Upper Galilee located a short distance from elephant butchering sites, which are positioned along the elephants’ movement paths.”

 

Quarries and flint piles in the Galilee (Photo: Meir Finkel).

 

Subsequently, the researchers sought to apply an adapted model from the one they developed in Israel to several sites from the Lower Paleolithic period in Asia, Europe and Africa, where such a “triad” exists. These included both sites where the hunted animals were elephants or mammoths, as well as later sites where other animals, such as hippos, camels, and horses, were the prey.

 

"It appears that the Paleolithic holy trinity holds true universally: Wherever there was water, there were elephants, and wherever there were elephants, humans had to find suitable rock outcrops to quarry stone and make tools in order to hunt and butcher their favorite megaherbivores", says Prof. Barkai.

 

"It was a tradition: For hundreds of thousands of years, the elephants wandered along the same route, while humans produced stone tools nearby. Ultimately, those elephants became extinct, and the world changed forever" - Prof. Barkai.

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