Monday, October 26, 2009
Workshop at Taichung
I gave a one-day workshop on the beaded molecules for some junior high school students this summer (7/2-7/3/2009) at Taichung, Taiwan. Here is a picture about the workshop.
In the morning, after a brief introduction on the chemical bonding and a few simple molecular structures, I then started to teach student the platonic solids and basic weaving techniques by asking them to make a C20 (a dodecahedron). I simply asked students follow my instructions step by step without too much explanation. This is because, I think, it is important to have some hands on experience for constructing beaded fullerenes first. Some students can get the basic rules of weaving just after a few steps, others may take a longer time and kept asking me how to do the next step. But it took about an hour for all students to get the first project done. I also found that it is better to use larger beads around 10mm to 12 mm for students who have no experience in beading. To create a C20, one need 30 beads. So it is not too expensive even for a group of 50 students.
The next project in the afternoon was to construct a C60. Of course, before we started to do that, I explain the icosahedron, truncated icosahedron and a few background information on fullerenes to them. Unlike C20, where all atoms and bonds are equivalent, here we have two different bond types, 5-6 and 6-6 bonds, so it is natural to use two different color of beads for the construction. In fact, this is not a burden for weaving. Instead, color of beads can be used as a mnemonic aid for denoting the place of pentagons. One needs 90 beads to represent chemical bonds in a C60. Since students have some experience in the morning for making a C20, I find it convenient and more cost effective to use 6mm beads with two different colors for students to work on in this project. It took about 2 hours for most of students to construct his or her C60.
The picture shown below is the C60 I made in this workshop. At the end, I gave it to one of students in this workshop as a souvenir.
In the morning, after a brief introduction on the chemical bonding and a few simple molecular structures, I then started to teach student the platonic solids and basic weaving techniques by asking them to make a C20 (a dodecahedron). I simply asked students follow my instructions step by step without too much explanation. This is because, I think, it is important to have some hands on experience for constructing beaded fullerenes first. Some students can get the basic rules of weaving just after a few steps, others may take a longer time and kept asking me how to do the next step. But it took about an hour for all students to get the first project done. I also found that it is better to use larger beads around 10mm to 12 mm for students who have no experience in beading. To create a C20, one need 30 beads. So it is not too expensive even for a group of 50 students.
The next project in the afternoon was to construct a C60. Of course, before we started to do that, I explain the icosahedron, truncated icosahedron and a few background information on fullerenes to them. Unlike C20, where all atoms and bonds are equivalent, here we have two different bond types, 5-6 and 6-6 bonds, so it is natural to use two different color of beads for the construction. In fact, this is not a burden for weaving. Instead, color of beads can be used as a mnemonic aid for denoting the place of pentagons. One needs 90 beads to represent chemical bonds in a C60. Since students have some experience in the morning for making a C20, I find it convenient and more cost effective to use 6mm beads with two different colors for students to work on in this project. It took about 2 hours for most of students to construct his or her C60.
The picture shown below is the C60 I made in this workshop. At the end, I gave it to one of students in this workshop as a souvenir.
New P-Type surface
I created a new P-surface with eight unit cells (2x2x2) using white and red beads last weekend. In total, 2880 beads are used. (Note that 90 beads are needed to create a C60.) Unlike previous two P-surfaces, I use red beads for octagons this time. The weaving process for creating a large beaded structure usually takes a long time and is prone to error.
Since the whole weaving process is essentially serial, the beads have to be added one by one along a single string of thread. So, once an error was made in the past, it is difficult to correct it without untieing all the beads up to that point the error was made.
The errors I made are usually something like using 9 beads to create an octagons (3 or 4 times out 128 octagons in the structure) and using 7 beads for hexagon (only 1 times). It is easy to understand why these errors occur more frequently for octagons, since it is more difficult to distinguish octagon and nonagon.
The first P-type structure Chuang and I made together has been given away to Bob Silbey as a gift in the summer of 2008. I made the remaining two P-surfaces by myself.
Silbey's 65 Birthday Symposium. I was in the second row far left.
(photo taken from http://web.mit.edu/newsoffice/2005/silbey.html)
Since the whole weaving process is essentially serial, the beads have to be added one by one along a single string of thread. So, once an error was made in the past, it is difficult to correct it without untieing all the beads up to that point the error was made.
The errors I made are usually something like using 9 beads to create an octagons (3 or 4 times out 128 octagons in the structure) and using 7 beads for hexagon (only 1 times). It is easy to understand why these errors occur more frequently for octagons, since it is more difficult to distinguish octagon and nonagon.
The first P-type structure Chuang and I made together has been given away to Bob Silbey as a gift in the summer of 2008. I made the remaining two P-surfaces by myself.
Silbey's 65 Birthday Symposium. I was in the second row far left.
(photo taken from http://web.mit.edu/newsoffice/2005/silbey.html)
Thursday, September 17, 2009
Buckled carbon nanotube
A few months ago, Chuang and I discovered a new type of carbon nanotubes, when we were studying how to generate the helically coiled carbon nantoubes (HCCNTs) from toroidal carbon nanotubes (TCNTs).
In the following picture, I show a beaded model for a unit cell of the BCNT (bulged or buckled CNT) which has the same molecular graph as that of T120, but with different boundary condition.
From this picture, we can see that the trick for making this type of systems is to take the inner-rim (neck) of the TCNT out, and repeat this basic unit, the resulting structure is a BCNT.
Using this trick, we can easily see that there is a one-to-one correspondence between TCNT and BCNT.
In the following picture, I show a beaded model for a unit cell of the BCNT (bulged or buckled CNT) which has the same molecular graph as that of T120, but with different boundary condition.
From this picture, we can see that the trick for making this type of systems is to take the inner-rim (neck) of the TCNT out, and repeat this basic unit, the resulting structure is a BCNT.
Using this trick, we can easily see that there is a one-to-one correspondence between TCNT and BCNT.
Wednesday, September 16, 2009
Ball of whacks
I bought this ball of whacks in the Smithsonian store at Dullus airport, Wahsington D.C. last month.
This ball is basically a rhombic triacontahedron consisted of 30 magnetic design blocks.
This ball is basically a rhombic triacontahedron consisted of 30 magnetic design blocks.
Paper appeared as an item in ACS homepage
My paper with Chuang on the classification of High-Genus fullerenes has appeared in ACS homepage http://portal.acs.org in July as an item in News & Research.
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