Nobel Prize in Chemistry 2012

The Nobel Prize in Chemistry 2012 was awarded jointly to Robert J. Lefkowitz and Brian K. Kobilka "for studies of G-protein-coupled receptors"

The cells in our bodies need to work together, they need sensors to be able to sense what is going on around them. The sensors on the surface of cells are call receptors.

The G-protein-coupled receptors are a family of receptors for adrenalin (epinephrine), dopamine, serotonin, light flavour and odour. A lot of medications that we take act on these receptors.
While these G-protein-coupled receptors are clearly very important, scientists haven't really known very much about how they work until recently.

In 1970 Lefkowitz  announced the discovery of an active receptor. Using radioactive tracers his research group examined how adrenergic receptors, receptors for adrenalin and noradrenalin, work.
In the 1980's his research team started work on trying to find the gene code for the beta receptor in the hope that this would give them clues about how the receptor works.
Kobilka joins the team and has an idea that it makes it possible to isolate the gene.
The receptor is found to consist of 7 long fatty spiral strings (helices).
A different receptor, the light receptor rhodopsin in the retina of the eye, has also been found to be made up of  7 stringed helices.

The groundbreaking discovery was that these two receptors are related even though they have different functions, that is, there is a family of receptors that look alike and function in a similar, yet different, manner.

In 2011 Kobilka and his research team finally got an image of the receptor at the very moment when it transfers the signal from the hormone on the outside of the cell to the G-protein on the inside of the cell.

Reference:
http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2012/popular-chemistryprize2012.pdf

Nobel Prize countdown

As students head back to the class room for a new term of exciting learning, the scientific community is gearing up for a major annual event, the announcement of the Noble Prizes.
With just days to go before the Nobel Prize in Chemistry is to be announced, there is much discussion (and possibly even a bit of betting) about who is likely to be this year's laureate.

Among the contenders this year are:

• Louis E. Brus (Columbia University) for the discovery of colloidal semiconductor nanocrystals (quantum dots)
• Akira Fujishima (University of Tokyo) for the discovery of photocatalytic properties of titanium dioxide (the Honda-Fujishima Effect)
• Masatake Haruta (Tokyo Metropolitan University) and Graham J. Hutchings (Cardiff University) for their discoveries of catalysis by gold

Quantum dots are semiconductors, but their electronic properties are related to the size and shape of the individual crystals. In general, the smaller a crystal is, the more energy is needed to excite the dot, which means that more energy is released when the crystal returns to its ground state. It is hoped that quantum dots will lead to practical quantum computing and increase the efficiency of photovoltaic cells. Quantum dots are being used in preference to some dyes in biological analyses because quantum dots are brighter and more stable.

While working on his Ph.D in 1967, Akira Fujishima exposed a titanium dioxide electrode to strong light and discovered that this catalyzed the decomposition of water into hydrogen and oxygen. This became known as the Honda-Fujishima Effect (Professor Kenichi Honda was Akira Fujishima's supervisor). Finding cheap, effective methods for providing hydrogen would enable the development of hydrogen as fuel.

In the 1980's Masatake Haruta showed that colloidal gold, gold clusters with diameters of 5 nanometers or less, could catalyze reactions involving oxygen gas.
Graham J Hutchings has extended the number of reactions  we now know of that can be catalyzed by gold. Hutchings has shown that primary alcohols can be oxidized to aldehydes using a gold-palladium/titanium dioxide combination without the need for a solvent. He has also developed the rapid synthesis of hydrogen peroxide, H₂O₂, from hydrogen and oxygen  without the formation of water as a by-product.

More Electrochemistry Resources

New teaching and learning resources have been added to AUS-e-TUTE on the following topics:

• Batteries (student learning resources)
• Lead-Acid Battery Case Study (student learning resources) 
• Fuel Cells (student learning resources) 
• Electrical Energy Calculations (student learning resources)
• Half-equations for Ions (teaching resources)
• Redox Reaction Concepts (teaching resources)
• Standard Electrode Potentials for Oxidation and Reduction Reactions (teaching resources)

Become an AUS-e-TUTE member and get the full benefit of using teaching and learning resources developed by experienced science teachers.
Visit http://www.ausetute.com.au.com.au to find out more.

            

Green Hair

Imagine you are living in a small town in Sweden.
You go to bed one night, naturally blonde.
When you wake up in the morning and look in the mirror your blonde hair has turned green!
Not only that, but your naturally blonde neighbour also has green hair!

This actually did happen in 2011, and, no doubt, caused a certain amount of distress.

Where would you begin in order solve the "green hair" mystery?
What could turn hair green?

Blonde hair often turns green after swimming in chlorinated pool water.
Copper, used in compounds to reduce algae growth in water, can be present in concentrations of about 0.5 ppm in pool water. When bleach (often sold as "liquid chlorine") is added to the pool water it oxidizes the copper resulting in a pretty green colour, and the oxidized copper binds to the proteins in the hair.
If you happen to have copper pipes in your bathroom, you've probably seen "green stains" on the pipes where the copper has been oxidized.

So, back to the story in Sweden.
Samples of drinking water were taken from a number of homes in order to measure the amount of copper present but the concentration of copper in the water did not exceed the recommended guidelines (that is, the copper ion concentration was less than 1 ppm).

However, in new houses, when hot water was left overnight and tested the next morning, the concentration of copper in the water increased dramatically. On further investigation it was discovered that the hot water pipes in new houses lacked the coating that the pipes in older houses had. So, overnight, when the water in the pipes was still and not being continuously "flushed" through the pipes, copper particles were being added to the water.

For solving the "Swedish Green Hair Mystery" Johan Pettersson was rewarded with a 2012 Ig Nobel Prize for Chemistry.


References:
http://www.thelocal.se/37994/20111217/
http://www.improbable.com/ig/winners/#ig2012

Further Reading 
http://www.ausetute.com.au/waterana.html 
http://www.ausetute.com.au/aas.html 
http://www.ausetute.com.au/partspm.html 
http://www.ausetute.com.au/concsols.html 
http://www.ausetute.com.au/weightpc.html 
http://www.ausetute.com.au/corrosion.html 

Suggested Study Questions:

1. Describe 2 methods you could use to detect the presence of copper ions in water.
2. Describe the process by which Atomic Absorption Sepctroscopy (AAS) could be used to measure the concentration of copper ions in a water sample.
3. Describe a way that you could prevent copper from entering the water in the copper water pipes in this Swedish town.
4. Copper is often present in soils at a concentration of around 50 ppm. What mass of copper would be present in 0.5 tonne of soil?
5. A particular pool contains 40,000 L of water. If the pool water contains 0.5 ppm copper ions, what is the concentration of copper ions in mol L^-1 ?
6. Chocolate can contain 10 mg/kg  copper. What mass of copper is present in a 250 g bar of chocolate?
7. Doses of copper that exceed 50 mg/kg of body mass can be lethal. Calculate the mass of copper that would be the lethal limit for an 80 kg adult.
8. What advice could you give the inhabitants of this Swedish town in order for them to avoid having green hair?

How many elements can be made?

Since the 1940's scientists have been synthesizing new elements with atomic numbers greater than 92, the so-called transuranium elements.

Just how many elements can we make?

Read more in the September 2012 edition of AUS-e-NEWS.

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Sticking Non-stick Surfaces Together

Polymers made up of non-polar, or only very slightly polar, functional groups are said to have low surface energy and poor adsorption which means that the surfaces are not "sticky".
Teflon (polytetrafluoroethylene or PTFE) is an example of a polymer with a very low surface energy, so low that it is used to provide non-stick coatings to things like pots and pans.
Silicones (polysiloxanes), with the general formula [R₂SiO]_n in which R is an organic group such as a methyl or ethyl group, also tend to have low surface energies. Because most materials do not adhere to, or stick to, silicones, silicones have become widely used to make flexible "rubber" molds.

So, how do you join together materials like these that are not "sticky"?

This is the question that scientists at Kiel University in Germany have been studying, and the solution they have devised is to use nano-scaled crystal linkers as internal staples. These staples are made of zinc oxide in which the crystals are shaped like tetrapods, that is, each staple has 4 legs. Zinc oxide crystals are sprinkled evenly onto a heated layer of teflon. Then a layer of silicone is poured on top. The material is then heated to 100^oC for less than an hour in order to join the materials firmly together.When the zinc oxide crystals are heated, the tetrapods pierce the teflon and silicone materials, sink into them and get anchored.
Peeling the teflon layer off the silicone layer held together by the tetrapod staples is about the same as peeling sticky tape off glass.

Reference:
X. Jin, J. Strueben, L. Heepe, A. Kovalev, Y.K. Mishra, R. Adelung, S.N. Gorb, A. Staubitz. Joining the un-joinable: Adhesion between low surface energy polymers using tetrapodal ZnO linkers. Advances Materials, 2012 DOI: 10.1002/adma201201780

Further Reading
Polymers and Polymerization
Functional Groups
Molecule Polarity

Suggested Study Questions:

1. Define the term polymer
2. Give two examples of polymers that are commonly used in households.
3. Define the term functional group and give three exaples.
4. Explain what is meant by a polar functional group and a non-polar functional group.
5. Give the structural formula for the monomer that can be used to form teflon.
6. Are the bonds in the monomer you have drawn in question 5 polar or non-polar bonds. Explain your answer.
7. Is the molecule that is the monomer in question 5 polar or non-polar. Explain your answer.
8. Given the general formula for silicones provided in the article, write the formula for:
   • polydimethylsiloxane
   • polydiethylsiloxane
9. Give a possible structural formula for the monomer used to produce each of the silicone polymers in question 8.

New Electrochemistry Resources

AUS-e-TUTE has just updated its Faraday's Laws of Electrolysis and added new resources for Q = It and E=QV calculations.

A "draft" of the VCE 2013-16 chemistry syllabus study guide has also been added.

Visit http://www.ausetute.com.au to view these resources.