Hydrogen is known to have the potential to become an important source of energy. And there’s an abundant supply of it, in our water, if we can just find a low-cost, efficient way of getting the oxygen in H2O to let go of it. The University of Houston (UH) has just announced that they may have just found it.
Splitting the hydrogen and oxygen in water is accomplished using a process called “water electrolysis” in which both the hydrogen and oxygen molecules separate into individual gasses via separate “evolution reactions.” Each evolution reaction is induced by an electrode in the presence of a catalyst.
Water can also be split using photocatalysis that uses solar power directly instead of electricity, but it’s less efficient since water only absorbs a small range of the light spectrum.
It’s been the lack of an efficient, low-cost catalyst for the oxygen molecules that’s been holding the full-scale extraction of hydrogen back. Up until now, oxygen catalysts have been based on scarce, expensive “noble” metals such as iridium, platinum, or ruthenium.
This is a problem that has been thwarting the full-scale commercial extraction of hydrogen for energy for some time, and UH isn’t the only entity searching for a replacement. Just last spring, the Canadian Department of Energy’s SLAC National Accelerator Laboratory and the University of Toronto announced the discovery of a new oxygen…
Shannon D. asks: How come people who smell really bad can never seem to smell their own stench?
Have you ever sat next to a woman on a bus who lost her sense of smell? Or, at least, you assume so as the eye-watering fragrance wafting from her perfume is so overpowering that the nausea it induces makes you appreciate the subtle scent of a dryer sheet… If so, you might wonder, what causes a person to become blind to their own smell?
Technically referred to as olfactory fatigue, olfactory habituation, or odor adaptation, being “nose-blind” might appear to be something of a defect, but the ability to have the scent of a specific fragrance (such as your own) dwindle over time is very beneficial. Imagine tip-toeing through the tulips, enjoying the lovely aroma around you along with your own equally lovely stench. If these smells didn’t diminish over time, you might miss the new smell of a cougar about to use you as a tasty meal. Or, perhaps you’re the hunter and are trying to pick up the scent of your prey. In these sorts of scenarios that our sweaty, hunter-gatherer ancestors with deodorantless armpits frequently found themselves in, scanning for new smells was much more useful than continuing to experience their own. The drawback is, of course, in more modern times perfume-Peggy doesn’t realize the overpowering nature of her cougar-scent…
But how does this work?
To begin with, in the back of your nasal cavity, about 2 ¾ inches or 7 centimeters above and behind your nostrils, lies a special grouping of cells called olfactory epithelium. These cells are attached to the olfactory bulb within the brain by olfactory neurons. At the end of each neuron lies a receptor cell. When microscopic molecules circulating within the air or molecules broken down in the act of chewing your food come into contact with a receptor cell, they attach. The process is called protein-ligand binding. Once attached, it will cause an electrical signal to be transmitted down the neuron to your brain. The signal your brain receives gives us the perception of smell.
There are around 350 genes (from the nearly 1,000 olfactory genes) that make olfactory receptors. Each gene produces a different type of receptor. Each specific receptor will react to a specific group of structurally similar molecules- molecules from coffee, tomatoes, or Peggy’s generously applied perfume, for example. A combination of several different receptors being activated will also be perceived as a different type of smell. In this way, your body can distinguish countless number of different odors.
(And note: it was once thought that humans were only able to recognize around 10,000 different fragrances. Dr. Leslie Vosshall and her colleagues at Rockefeller University, however, have recently shown humans are actually able to detect at least 1 trillion different smells, and this number might be too low by a long shot. Dr. Vosshall’s study only used 128 different types of odor molecules to achieve the nearly 1 trillion different sensations of smell. She points out that there are many more odor compounds found in…