Health  

Of the five senses, our sense of smell might be the easiest to dismiss. We are told, after all, that compared to many animals, our noses are sub-par. However, smell is connected directly to the limbic area of the brain, which controls the body’s response to outside stimulus. All other sensory input is routed through another part of the brain first.

Smell can be considered our most primary sense. Scientists continue to study what we can learn from the nose and our sense of smell.

Parts of the Nose

The nose has two nostrils, or napes, which lead to the two nasal cavities. These cavities are separated by a wall of cartilage known as the septum. The cavities lead to the sinus cavities, a system of canals and pockets of air responsible for breathing, smelling, and tasting. This is also the first line of the body’s immune system’s defense. The nose is lined with cilia, hair like projections, and the sinuses create mucus. Together, these work to collect particles before they enter the rest of the body.

The olfactory cleft, on the roof of the nasal cavity, is used for “smelling”, and the olfactory bulb and fossa make up the “smelling” part of the brain. Smells are picked up by some of the 450 olfactory receptors in the nose and then travel to the brain.

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Memories: What the Nose Knows

When an odor molecule binds to a receptor, an electrical signal travels from the sensory neuron to the olfactory bulb. The piriform cortex works to identify the smell and this information is sent to the thalamus: the “senses” center of the brain. The thalamus sends this information to the hippocampus and amygdala, brain regions involved in learning and memory. This is why smells are so deeply connected with certain memories. In fact, certain scents may help you remember facts better – something to keep in mind while studying!

Emotional Wellness

From our memory, to our immune system, to our learning ability, smell has an importance that is hard to overstate. New research even suggests that the nose can detect over a trillion different smells, thus outperforming the eyes and ears. The aroma of a certain scent or essential oils like doTERRA oils can trigger specific reactions, emotions, or memories. When a scent in inhaled, it goes through the olfactory system and the connected limbic system, which produces a distinct response based on the experiences associated with the smell.

The nose knows! In the future, additional research will doubtless help make sense of this fascinating sense.

By  Eileen O'Shanassy	Embed

 Graphene  

Scientists have discovered a way to create a highly sensitive chemical sensor based on the crystalline flaws in graphene sheets. The imperfections have unique electronic properties that the researchers were able to exploit to increase sensitivity to absorbed gas molecules by 300 times.

Researchers have discovered a way to create a highly sensitive chemical sensor based on the crystalline flaws in graphene sheets. The imperfections have unique electronic properties that the researchers were able to exploit to increase sensitivity to absorbed gas molecules by 300 times.

The study is available online in advance of print in Nature Communications.

In many applications, grain boundaries are considered faults because they scatter electrons and may weaken the lattice. But Amin Salehi-Khojin and his colleagues showed that these imperfections are important to the working of graphene-based gas sensors.

The team created a micron-sized, individual graphene grain boundary in order to probe its electronic properties and study its role in gas sensing.

Their first discovery was that gas molecules are attracted to the grain boundary and accumulate there, rather than on the graphene crystal, making it the ideal spot for sensing gas molecules. A grain boundary’s electrical properties attract molecules to its surface.

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A theoretical chemistry group at UIC, led by Petr Kral, was able to explain this attraction and additional electronic properties of the grain boundary. The irregular nature of the grain boundary produces hundreds of electron-transport gaps with different sensitivities.

"We can easily fabricate chip-scale sensor arrays using these grain boundaries for real-world use.”

“It’s as though we have multiple switches in parallel,” said graduate student Poya Yasaei, first author on the paper. “Gas molecules accumulate on the grain boundary; there is a charge transfer; and, because these channels are all paralleled together, all the channels abruptly open or close. We see a very sharp response.”

Researchers have been trying to develop a highly sensitive and robust sensor for decades, said UIC postdoctoral fellow Bijandra Kumar, a co-author on the paper.

“We can synthesize these grain boundaries on a micrometer scale in a controlled way,” Kumar said. “We can easily fabricate chip-scale sensor arrays using these grain boundaries for real-world use.”
Salehi-Khojin said it should be possible to “tune” the electronic properties of graphene grain-boundary arrays using controlled doping to obtain a fingerprint response — thus creating a reliable and stable “electronic nose.”

With the grain boundary’s strong attraction for gas molecules and the extraordinarily sharp response to any charge transfer, such an electronic nose might be able to detect even a single gas molecule, Salehi-Khojin believes, and would make an ideal sensor.


SOURCE  University of Illinois at Chicago

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