When it comes to 3D printing, the sky is the limit. As 3D printing technology continues to advance, applications can be as far reaching as airplane and automobile parts to medical devices and even anatomically correct, biocompatible models. Although 3D printing technology is developing at a rapid pace, the technology itself is not new. It emerged in the 1980s as a means of creating rapid prototypes. In recent years the applications for 3D printed models have evolved with the available hardware, software, and printable materials. Evolving technology, paired with the creative and innovative minds of scientists, engineers, and physicians, has been the launching pad for developments within 3D printing technology specific to healthcare. One way 3D printing technology is poised to create better patient outcomes is in creating an anatomically and patient-specific models to aid in surgery and medical procedures. With the capability to 3D ...
Love it or hate it, April showers bring May flowers, but this seasonal rain may bring more than just flowers. If you’ve ever been outside after a heavy rain you may have noticed the inevitable “rain smell.” The curious scientists at Polymer Solutions couldn’t let this go as a natural phenomenon and decided to delve deeper to find out the root cause of this pleasantly nostalgic smell.
The Science Behind the Smell
After a little reading, we found that the smell after it just rained is actually a specific chemical compound, and we know what causes it. The smell of rain is most intense when there’s been a period of dryness before a heavy rain. If you consider yourself a fan of the just rained smell, you might be in heaven if you found yourself in a dry desert after a freak rain shower! There are a few chemical compounds from two different sources that contribute to the smell.
The first is petrichor, an oily compound that exists in the cracks and pores of dry rocks, which is spread when rocks get wet. The name petrichor comes from the Greek words “petro” which is “rock” and “ichor” which is “blood (of gods)” or literally, rock blood. When analyzing this compound, you would find that petrichor is mostly palmitic acid, stearic acid, and oleic acid, and comes from plants. These compounds are frequently used in plastics as lubricants and process aids and the products that contain them do not smell like rain. Even through these are by far the major compounds in the rain smell oil, they are not the real source, rather a transportation method for the compound that really causes the smell.
The real source of the smell is a compound called geosmin. Geosmin is an alcohol with two rings, and is produced by a type of soil bacteria called strepromyces and is a byproduct of the bacteria living their normal bacteria life. This compound is responsible for the rain smell, but it doesn’t need to be a major compound to do so; the human nose is especially sensitive to geosmin, and it can be detected at levels of 5 parts per trillion! That level is comparable to putting one drop of geosmin in 4 Olympic sized swimming pools, and is actually much more (up to 1000 to 100,000 times or more) sensitive than some high-sensitivity analytical equipment can detect for general compounds. The human nose can be an especially powerful instrument when there is a slight odor or color defect in a sample and can often help to point our scientists in the right direction for the next step of analysis.
How do You Test for Smell?
When testing for failure analysis or checking for the source of a particular smell, testing laboratories can be used in a number of ways. Headspace gas chromatography and mass spectrometry is a commonly used testing procedure when identifying various gasses that may be causing an odor. GC-MS vaporizes a sample and analyzes the resultant gasses to give our scientists a better picture of exactly what materials are present in a sample. Whether it’s stinky cheese puffs or the seemingly mysterious rain smell, the scientists at PSI are always eager to get to the bottom of a mystery.
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