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Particle Analysis CSI Style and Interference is Everywhere...
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It's All In The Particulates

You may have heard reference to ‘particulates analysis’ on TV series such as CSI or Bones, where the investigators send off all kinds of things to ‘The Lab’ for Particulates. From shoes to car bumpers, and skin swabs to plants, this can help these fictional investigators solve a wide variety of mysteries.

This isn’t just fiction! Particulates analysis is used in real life to solve all kinds of puzzles – to determine where an object has been, how a motor is failing, where that piece of glass was manufactured or whether it’s your neighbour’s fault that your car is covered in dust.

Particulates analysis involves identifying particulate material and separating the expected particulates (natural dust, dust from your own industrial processes or projects, etc) from contaminant or suspect particulates (dust from nearby factories, metal shavings, sawdust, etc). By examining the morphology (shape) and elemental composition of particles, we can match them to known sources of dust or compare them to samples from the suspected source.

In the past, Microanalysis Australia has helped to prove:

  • Dust found on cars was from the spray painting and grinding conducted at a nearby panel beaters;
  • The identity and potential hazards of foreign objects in packaged food;
  • The source of localised discolouration on cooked chicken;
  • The identity of contaminants in food products;
  • A lung biopsy sample was alpha-quartz;
  • A blocked filter was from the epoxy pipe lining failure;
  • Which nearby factory was causing dust problems in neighbouring residential areas; and
  • Whether paint was over thinned/filled or diluted with the wrong thinners.

We use a variety of techniques to identify particulates, including SEM, XRD and FTIR, depending on the type of material. Ask us about the best way to solve your own mysteries!

Iron oxide sphere with iron sulphide crystals. Image taken on SEM by Sandy Lam

Interference is Everywhere


Interference (unwanted signal or noise) is everywhere, and isn’t always what you predict!

Any scientific analysis has to take into account any possible sources of interference. From fluorescence in X-ray diffraction (XRD) to magnets in the Scanning Electron Microscope (SEM), a good scientist must always be aware of the factors that may affect, bias or obscure their results.
Unfortunately those sources of interference aren’t always easy to pinpoint as was shown recently at the Parkes Observatory earlier this year. Parkes Observatory, in central west NSW, houses one of the radio telescopes comprising CSIRO’s Australia Telescope National Facility and has contributed significantly to global astronomical discoveries.

The Parkes radio telescope has the capacity to pick up a range of radio signals from terrestrial and non-terrestrial sources. The observatory has for some time been picking up mysterious radio signals known as ‘perytons’, named after a mythical winged stag and similar in nature to the extraterrestrial FRBs (fast radio bursts) but determined to be terrestrial (from earth) in origin.

After much confusion, the mystery was solved early this year when it was discovered that the perytons were the result of the observatory’s lunchroom microwave ovens releasing brief pulses of radio waves when the doors was opened too quickly (interesting science can give you quite an appetite!). The two microwave ovens responsible were both over 27 years old, and were found to be the origin of perytons for the last 17 years! It appears the radio bursts only occurred when the microwave door was opened prior to the microwave (resonator) turning off.

While slightly embarrassing, this did lead to the discovery that perytons are distinguishable from FRBs, and that the first known FRB, which was also the first FRB detected by the Parkes telescope could not be attributed to the microwave ovens.

Even in the search for interference, science marches on (after lunch of course).
 

Image Of The Month
This month’s image is of a chicken feather kindly requested and submitted by our work experience student from Kalamunda High School.

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Image taken by Rick Hughes
Copyright © 2015 Microanalysis Australia Pty Ltd, All rights reserved.


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