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Category Archives: Chemistry/Physics

The Writers Forensics Blog: 100 Top Websites to Bookmark

The crew over at FornesicScienceDegrees.org have listed The Writers Forensics Blog as one of their Top 100 Websites to Bookmark, which they describe as a “list of great sites to present practical, real-world information on the subject.” Many great sources here.

Thanks. I’m flattered.

 

 

Surgery in Zero Gravity

How do you do surgery in zero gravity?

Very carefully. And it helps to have NASA’s latest toy.

You’ve probably seen videos of astronauts playing with water in space. No dripping or dropping here. Due to their inherent surface tension and the lack of gravity applying any external force, liquids tend to form into spheres and float around. Fun stuff.

 

But what about blood? Of gall bladder fluid? Or, yuck, pus from an infected wound? These are not materials you want floating around in your space capsule, or your face.

The Aqueous Immersion Surgical System (AISS) just might solve this problem. It is a saline-filled transparent box with airtight ports through which orthoscopic surgical tools can be passed.

 

 

Very clever and very cool.

 
 

Metabolic Fingerprints

Metabolomics, also called Metabonomics, is the study of the unique chemical fingerprints the metabolic processes within the body leave behind. I like the term Metabolic Fingerprint since it’s easier to say.

In medicine, metabolism simply means the array of chemical processes that silently go on within our bodies. The digestion of food, the alteration or destruction of medicines or drugs by the liver, the conversion of protein to muscle tissue, the use of various sugars for energy, the repair of injured tissues, and every other chemical process within the body would fall under the broad umbrella of metabolism.

We are a product of our genetic makeup and our environment, the two working in concert to determine virtually everything about our lives. Our genes determine how each of our metabolic processes will work. For example, an individual with diabetes metabolizes sugar and produces chemical byproducts of this metabolism much differently than does someone without diabetes.

Since each of us has a different genetic makeup and each of us is exposed to different environmental influences, including diet, medications or drugs consumed, exposure to illnesses, workplace toxin exposures, stresses, and many other things, it would be expected that each of us possesses a different metabolism and therefore a unique Metabolic Fingerprint.

The key point Is that each of us is unique genetically and environmentally, each of us has different metabolic processes going on inside, and therefore each of us produces a unique combination of chemicals and metabolic byproducts in our body. A German research team has begun using Nuclear Magnetic Resonance (NMR) Spectroscopy to develop these Metabolic Fingerprints, or as they call them Metabonomic Fingerprints.

Does Metabolic Fingerprinting have a place in current medicine and forensic science? Not yet, but maybe soon. The beauty of friction ridge prints (standard fingerprints) is that they are unique and they do not change over a lifetime. If either of these were not true, then fingerprinting would not the useful forensic tool that it is. In order for any identification technique to be useful, it must fulfill both the criteria–it is individual and it does not change over time. This is not only true in fingerprinting but also in DNA analysis.

Do our Metabolic Fingerprints fulfill these criteria? The answer is maybe. We need to know much more. With the ongoing research using NMR spectroscopy and other modalities we may soon have the answer. The problem I see is that our metabolism changes from day to day simply because each day we are exposed to different nutrients, stresses, and environmental influences. Unlike fingerprints, which are static physical properties, our metabolic properties are in constant motion. If researchers can prove that our Metabolic Fingerprint is unique and does not change over time, this could be a useful tool for forensic investigation. If the metabolic analysis of biologic materials left at a crime scene could be matched to a particular individual, when fingerprints and DNA were not available, then this could serve as a useful method for identification. DNA can often be found in latent fingerprints (the so-called touch DNA) but not always. Perhaps one day, the oils left behind in a smudged and DNA-free fingerprint will be chemically fingerprinted and matched to a particular individual. It will be interesting to watch this research and see how it develops.

Science Base Article

 

Caylee Anthony Autopsy Released

The autopsy report on the death of little Caylee Anthony was released this week. It is both interesting and disturbing. It showed:

No evidence of trauma–one speculation was that Caylee might have been killed by trauma, either intentional or accidental.

No drugs of any kind–another speculation was that the child might have been sedated and that the death was due to an overdose, again either accidental or intentional.

Several layers of duct tape were wrapped around Caylee’s mouth and face and it appears these might have been placed before of just after death. Could this have been to silence her? Could she have suffocated from the tape? Very disturbing thoughts.

The chemical analysis of the air in Casey’s (Caylee’s mother) car  trunk revealed 80 chemicals associated with body decomposition. In this test, air samples are taken from the trunk and subjected to various chemical analyses, the most important being chromatography, a test that can separate a chemical mixture and identify many of the components. If a decomposing corpse had been in the trunk, molecules of the gases produced would permeate the trunk carpeting. These would remain after the corpse was removed and would then be slowly released into the trunk space. Sampling and testing the air would then reveal whatever chemicals were present–in this case the chemicals associated with decomposition.

Autopsy of Caylee Marie Released: Be sure and read the autopsy and forensic reports linked to in this article. This will give you an idea of just how detailed these reports are.

Caylee Anthony: Autopsy Suggests She ‘Suffered Tremendously’

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Caylee Anthony’s Mother Casey in Court

 

Fingerprint Chemistry: More Than Just Ridges and Patterns

In an earlier post I talked about “Touch DNA,” where DNA can be extracted from some fingerprints. The typical fingerprint is made up of oils, dirt, skin cells, and other debris that are deposited whenever someone touches a surface. The cells left behind are the source of the DNA. But fingerprints reveal much more.

A new technique developed by R. Graham Cooks of Purdue University allows for chemical analysis of fingerprints. This technique is called Desorption Electrospray Ionization or DESI, for short. DESI can reveal drugs, explosives, and other materials the person might have handled. It can even be used when fingerprints are laid down one on top of another by several different people. Each person’s print has a unique chemical make up and it is this difference that allows examiners to separate these piled up prints from one another. The usefulness of this technique in analyzing crime scene prints should be obvious.

Read more about this fascinating new tool:

DESI Gives Fingerprinting Some New Respect

Finding Evidence in Fingerprints

New Fingerprinting Technique Has Surprising Advantages

Sticky Fingers

 
 
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