Archive for the ‘Research Blogging’ Category

Soft, wet and rather tough

March 13, 2010

ResearchBlogging.orgHydrogels are the only materials that have the potential to be used as a replacement material for functional tissues like cartilage, sinews or muscles. However, while the biological wet and soft materials have impressive mechanical properties and are generally very tough, conventional hydrogels are rather brittle and tend to disintegrate under duress. With one exception, though: Double Network hydrogels can take a lot more force, even exceeding biological tissues or rubber. I just read a paper in Soft Matter that discusses why this is so. The mechanism is rather intriguing.

Blowing molybdenum sulfide bubbles

March 6, 2010

ResearchBlogging.orgThere has been a veritable hype around fullerenes and carbon nanotubes in recent years, so this modification of carbon has extensively researched. What’s a little less known, is that there are other, very similar structures, made of inorganic building blocks, usually transition metal chalcogenides. There is, however, a difference: In most of the inorganic fullerens (IF) there is no preferred minimal structure like C60.

The one notable exception appears to be MoS2, which forms regular octahedral of discrete sizes, which are about 4 times larger than C60. Calculations show that these octahedra are onion-like, made up of several layers and contain between 1000 and 80000 atoms. As with normal carbon fullerenes, there are several ways to obtain such structures, but their growth mechanism is largely unknown.

Well, what do you do if you don’t know the mechanism of a reaction? You try to catch the intermediates somehow. That’s what researchers from Mainz did with the formation of the MoS2-octahedra. It turns out that the shrink-wrap model of fullerene formation applies to this material as well: In the CVD chamber, large sheets form first, which later on contract into the well-known stable forms. To catch the intermediates, their formation needs to be accelerated, which was why iodine was used to increase solid-state diffusion. The result was rather interesting, because the iodine didn’t do just that.

Piezoelectric fabric… again

February 27, 2010

ResearchBlogging.orgThe latest edition of Nano Letters has yet another paper about some sort of piezoelectric fabric that generates electricity when deformed. In Theory, you could wear pants made from this stuff and power, say, your watch just by walking around. Admittedly this isn’t exactly novel. We heard about it already in 2003 (pdf), 2007 and in February last year (at least. I stopped searching after two minutes). Nevertheless, this paper is rather interesting because it moves away from basic materials design and tackles a question that’s closer to applications: How can devices like this be built into everyday clothes? (more…)

How dangerous are these crystals, then?

February 21, 2010

ResearchBlogging.orgRecently I came across a very interesting article on the website of the German magazine Der Spiegel, which informed me that the current way of storing highly radioactive waste was unsuitable, and the reason for this is chemical. Says there:

Now a US-German research group, in an Article in Angewandte Chemie, raises doubts about the basic principle of storage.

Except that they don’t. The paper is about certain actinide borates with rather complicated structures and interesting properties – basic research with a lot of crystallography. Creating the borate compounds was inspired by a method of storing nuclear waste – very active materials are melted into glass rods and enclosed in a steel container. Depending on the condition, some actinides form crystals within the glass. Not much is known about these crystals, except that they appear to be actinide borates.

Surface reconstruction in platinum covered with CO

February 17, 2010

ResearchBlogging.orgSurfaces are full of surprises, and of course mysteries. Ertl described the intricacies of ammonia formation on flat platin surfaces decades ago and won a Nobel for it, but what happens between real catalysts and the reactions they accelerate remains largely unknown. When it comes to the behavior of steps, kinks and other surface features under real conditions, we have hardly scratched the surface yet.

That is because usually surface interactions are observed by scientists, for practical reasons, in near vacuum and at low temperatures. Lots and lots of interesting things simply don’t happen in near vacuum at low temperatures. Nevertheless it turned out that even under these conditions adsorbates induced significant changes in surface morphology, especially on steps and other nonconformities. One should assume that the changes observed so far pale in comparison to what more extreme conditions will do to surfaces. As we read in this recent Science paper by Feng Tao et al, that is indeed the case.

The strange poison of the Platypus

January 20, 2010

ResearchBlogging.orgThe duck-billed Platypus is such an odd creature that one could get the idea that its survival depends on potential predators laughing themselves to death, but in fact it can rely on a far more potent defense. It carries a venomous sting on its hind legs. Envenoming by a male Ornithorhynchus anatinus causes not only immediate excruciating pain, but also a long-lasting hypersensitivity, probably due to nerve damage.

The venom itself is a complex mixtures of peptides, for example defensin-like peptides similar to those found in venomous reptiles. Curiously those don’t go back to a common ancestor but evolved independently in both lines, as genomic analyses show. Another class of toxins consists of peptides related to C-type natriuretic peptides. CNPs are vasorelaxant peptide hormones that are widely distributed many tissues, notably the central nervous system.

Quantum Chemistry FTW!

January 14, 2010

ResearchBlogging.orgThere have been many new developments in quantum computing during the last few years, but last Sunday a paper appeared in Nature Chemistry that shows how far the area really has come. It seems that now things are getting really interesting: American and Australian scientists just built a quantum circuit that calculated the energy Eigenvalues of molecular hydrogen to an accuracy of 1 KJ/mol.

Of course we knew these Eigenvalues before, they can be calculated e.g. with DFT calculations. The amazing thing is the quantum circuit part. Quantum computers existed only in theory. Until now.

Smell the decay

December 12, 2009

ResearchBlogging.orgBeen to a library lately? Those of you who, like me, get their current literature via the internet, probably thoroughly repressed the memory of literature research without a search mask, but there are things that stay with you. Such as the smell of old books.

Turns out that there is more to this smell that meets the… uh… nose. It is the result of degradation and depends on the age of the book and the type of paper used.