#nanoscience

Someone asked me why people are placing a couple of packets of silica gel on the dashboard of their car, like right at the bottom of the windshield & whether it works. Surprisingly, yes. The "sponge" is actually silica gel, which is really sand because sand & silica gel have the same chemical formula, SiO₂. The difference is structure, not composition. Sand has large, dense, crystalline quartz grains, while silica gel is an expanded version of sand, meaning there's space between the atoms. So it acts like a small sponge. Small molecules like water can occupy these spaces. Silica gel does not occur in nature. It's made by adding an acid to a water solution of sodium silicate to produce a gelatinous precipitate that is then washed & dehydrated to produce colorless silica gel.

Silica gel has a great hidden surface area. Inside silica gel are millions of tunnels & pores. This creates a massive internal surface area (800 m² per gram/8,611 ft² per gram). One gram of this stuff has the surface area of 3 tennis courts. This huge area gives water molecules countless places to hide. And that's exactly why car owners are putting silica gel on dashboards. Dashboards contain sensors, wiring, plastics, screens & airbag modules. After it rains or in very humid weather, moisture can build up & cause fogging, corrosion, electrical failure, mold, & condensation inside sensors. Silica gel keeps everything dry & stable.

You've probably handled these little packets & they are inserted into pills by manufacturers, with cameras to prevent lens fog, in some packaged food to prevent mold, on leather to prevent mildew, with tools to prevent rust, in museum artifacts to prevent ancient textiles, mummies, & artifacts from cracking, mold or from decay, with ammo to prevent powder degradation, with drones to protect internal electronics, & with 3D printing filament to prevent moisture warping. Silica gel removes through adsorption, not absorption.

In absorption, water enters a material, such as a paper towel. With adsorption, water sticks to the surface of a material, such as activated carbon, which is commonly used in water purifiers like the portable Brita filter. Activated carbon adsorbs chlorine, chloramines, volatile organic chemicals, benzene, toluene, pesticides, and will partially reduce microplastics, trace reductions of some pharmaceuticals, taste-causing organics, and odor-causing organics, as well as trihalomethanes, which are the chemical byproducts created when chlorine reacts with natural organics in the water.

Metamaterials are products of engineering wizardry. They are made from everyday polymers, ceramics, and metals. And when constructed precisely at the microscale, in intricate architectures, these ordinary materials can take on extraordinary properties.

With the help of computer simulations, engineers can play with any combination of microstructures to see how certain materials can transform, for instance, into sound-focusing acoustic lenses or lightweight, bulletproof films.

But simulations can only take a design so far. To know for sure whether a metamaterial will stand up to expectation, physically testing them is a must. But there’s been no reliable way to push and pull on metamaterials at the microscale, and to know how they will respond, without contacting and physically damaging the structures in the process.

Now, a new laser-based technique offers a safe and fast solution that could speed up the discovery of promising metamaterials for real-world applications.

The technique, developed by MIT engineers, probes metamaterials with a system of two lasers — one to quickly zap a structure and the other to measure the ways in which it vibrates in response, much like striking a bell with a mallet and recording its reverb. In contrast to a mallet, the lasers make no physical contact. Yet they can produce vibrations throughout a metamaterial’s tiny beams and struts, as if the structure were being physically struck, stretched, or sheared.

The engineers can then use the resulting vibrations to calculate various dynamic properties of the material, such as how it would respond to impacts and how it would absorb or scatter sound. With an ultrafast laser pulse, they can excite and measure hundreds of miniature structures within minutes. The new technique offers a safe, reliable, and high-throughput way to dynamically characterize microscale metamaterials, for the first time.

“We need to find quicker ways of testing, optimizing, and tweaking these materials,” says Carlos Portela, the Brit and Alex d’Arbeloff Career Development Professor in Mechanical Engineering at MIT. “With this approach, we can accelerate the discovery of optimal materials, depending on the properties you want.”

Portela and his colleagues detail their new system, which they’ve named LIRAS (for laser-induced resonant acoustic spectroscopy) in a paper appearing today in Nature. His MIT co-authors include first author Yun Kai, Somayajulu Dhulipala, Rachel Sun, Jet Lem, and Thomas Pezeril, along with Washington DeLima at the U.S. Department of Energy’s Kansas City National Security Campus.

Keep reading.

This was based off of a #STEMARegional submission by @Ringu_u on Twitter that I selected to include in my region. 

I also gave this Carbink an evolution based off of graphene, a single layer of double-bonded carbons.

As with any regional mons that deal with canon ones, these designs are separate from the region, and the Stema Region is not dependent on canon mons.

This is a Carbink that was originally about seismographs and detection of disturbances in the ground. Seismographs often use a pen (or through creative liberty, a pencil) to record any disturbances. Later, a more direct reference to graphite was made where graphite is crystallized carbon, turning into diamond under heat and pressure. Carbon links to itself in sheets and there is a weak Van der Waals force between the sheets. It is so weak that sheets of carbons can come out of the graphite, allowing it to leave a mark behind.

Carbink (Rock/Dark): These Carbinks leave a trail as they move, and if they feel a disturbance in the ground, they leave a zigzag shape. The minerals of these Carbinks come off easily, so they could spray a cloud of graphite powder to run away.

I don’t know if I might be behind the times a little on this one but I just heard about it and thought it was a really cool use of science in everyday life. Liquid glass is pretty much what it sounds like, small particles of glass (silicon dioxide) suspended in a liquid. It’s a nano-coating first developed in the 80’s, and commercially available since the early 2000’s, which can be used to strengthen phone screens.

It can do this because on a microscopic level your phone screen isn’t all that flat, having lots of little bumps and rigids. The liquid glass, when spread on, can fill in these little gaps making the screen smoother, and therefore less likely to break. In fact, up to six times less likely to break. Being only 100mm thick it’s invisible to the human eye as well, meaning your phone can be protected while still in its ‘naked’ form.

It doesn’t need any glue to be able to stick as it forms weak bonds, called Van der Waals forces, with the glass already on your screen. Liquid glass is also super-phobic, meaning it repels both water and oil-based liquids, is very flexible, is acid and alkaline-resistant, and temperature-resistant. Essentially, a very cool material.

Nanomedicines is a very young branch of science. It has come into the picture only since the 1990s. Wonder what made researchers go down the nanoscale when we already had various drug development systems? The basic flaws in the conventional drug delivery system provided the spark for the emergence of a nano-drug delivery system.

 When we swallow a pill, its contents are constantly lost or tampered. This may be because of the acidic environment of the stomach, detoxification properties of the liver, or due to the presence of proteins and enzymes in the bloodstream which may bind to the drug and change its physiological properties. As the loss at these barriers is very high, a massive dose is required to compensate for this loss. According to David Anderson, a neurobiologist, current medication is like pouring a can of oil all over your car engine. Some of it will dribble into the right spot, but most of it is wasted, and some even does harm. This is the reason why chemotherapy patients lose hair. The drugs are so toxic that they not only affect but also kill normal healthy cells.

These problems can be dealt with if the delivery system of these drugs is altered. This is where nanoscience emerges as a potential solution. Nanomedicines are manufactured on a scale of 10^-9 m and can be even smaller than a virus! Due to its peculiar size, it can exude properties of both quantum and Newtonian mechanics thereby adding to the number of benefits we can avail. Moreover, its surface to mass ratio is exceedingly large, hence, it has the ability to bind, absorb, and carry various compounds. Coating them may also be necessary to prevent agglomeration. This can be done with various substances, such as natural, synthetic, inorganic, etc. To reach only the target site certain compounds are added which function as "Molecular keys". This technology is being harnessed mostly for the treatment of brain cancer as it is one of the most difficult malignancies due to the presence of blood brain barrier which tightly regulates the movement of molecules and ions between blood and brain. Nano-medicines recognize specific markers on cancer cells and their size opens the potential for crossing various biological barriers thereby increasing their efficacy. Anti-cancer drugs such as loperamide and doxorubicin bound to nanomaterials have been shown to cross the intact blood-brain barrier and released at therapeutic concentrations in the brain. In most cases, resistance develops when cancer cells begin expressing a protein, known as p-glycoprotein that is capable of pumping anticancer drugs out of a cell as quickly as they cross through the cell's outer membrane. New research shows that nanoparticles may be able to get anticancer drugs into cells without triggering the p-glycoprotein pump. The researchers studied in vivo efficacy of paclitaxel loaded nanoparticles in paclitaxel-resistant human colorectal tumors. Paclitaxel entrapped in emulsifying wax nanoparticles was shown to overcome drug resistance in a human colon adenocarcinoma cell line (HCT-15).

Many questions are still raised on the safety and cost of the nano-drug delivery system. Therefore, it remains irrefutable that the development of more sophisticated designs and further understanding of the properties at the nanoscale are required to yield such advanced therapies.

Citations:

·       https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2222591/

·       https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2527668/