For the aspiring forensic scientists...

We have learnt from all the police/detective shows that we see so much of on television that fingerprints are important evidence to collect from the crime scene. Fingerprints are left behind on everything that we touch due to the sweat on the skin as well as the oil, dirts and salts that are lodged in the tiny ridges of our fingertips. One of the simplest methods to get samples of fingerprints is to dust the touched area with magnesium powder, then "lift" the prints by photographing them.

Up to now, fingerprints can only be obtained from smooth and hard surfaces such as plastic and glass. Recently, forensic experts from the University of Abertay Dundee and the Scottish Police Services Authority (SPSA) have developed a method of getting fingerprints from cloth. This is accomplished using a technique called vacuum metal deposition. The cloth is first placed in a vacuum and then coated with a layer of gold. Zinc is then introduced and it will adhere to gold at places which have not experienced any contact by human hands. In this way, the scientists will be able to see the fingerprints as areas that are not covered by the grey film of zinc.

While it is still difficult to obtain clear enough fingerprints from fabrics for identification purposes, this technique provides evidence that can help the police to deduce the order of events that occurred at the crime scene. For example, they can now find out whether a person has been pushed down a building from the back by looking for handprints on the back of the shirt that he/she was wearing when it happened. New materials for CSI~

Carcinogenic Benzene

In the lecture this morning, it was mentioned that benzene is a carcinogenic compound, which causes people who are exposed to it for long periods of time to develop cancer. The carcinogenic property of benzene was only conclusively recognised a few decades ago. I remember one of my lecturers in university telling us that chemists of the past used to use benzene to wash their hands after handling organic experiments.

Here is quite an old video about how a worker developed leukaemia after being exposed to benzene on his job.

Help!!! I don't understand hybridization!

I know that some people will panic every time we talk about hybridization. It is one of those things that, at this stage, you need to just take for granted and not question too much, because you are not taught quite enough to comprehend the theory fully.

Here are some videos that may help you to visualise what hybridisation is about and hopefully, you will be able to understand it better.

This video was shown during the lecture

This video is rather clear in explaining how sp3 hybridisation occurs. A little long-winded at the beginning but have patience and watch it to the end as the second half of the video is good.

And here is the video for sp2 hybridisation. Similarly, watch it to the end!