Author: David Bradley

Save a balloon with water

Balloon in a candle flameWhat connects cooling computer chips, melting car engines, and a balloon that will not pop? This week’s science video sees Robert Krampf explaining the principles behind heat sinks, car radiators, water cooling, and how to hold a balloon above a burning candle without it ever popping.

Krampf points out that, “Because we’re using fire, always be sure you keep safety in mind, and be sure you’ve got an adult around, so that you’ll have somebody to blame if something goes wrong!”

So, what is it about water that makes it absorb the heat from the candle flame so fast and so protect the rubber of the balloon from melting or burning? Water has the second highest specific heat capacity of any known chemical compound, after ammonia. This is due to the extensive but transient network of temporary hydrogen bonds that form between the oxygen atom at the centre of each water molecule and a hydrogen atom from a neighbouring water molecule. This fluxional network of loose bonds allows liquid water to rapidly absorb heat and also allows the heat to quickly be dispersed through the bulk liquid.

WARNING: Please don’t attempt this experiment with anything but water in the balloon. Water is about the only fluid that is safe to use but more to the point, it won’t work properly with any other fluid.

Stay Calm, Beat Cancer

EpinephrineA constant flux of the stress hormone, released by the adrenal glands, could underpin certain forms of prostate and breast cancer. According the George Kulik and his colleages at Wake Forest University in North Carolina, epinephrine can change these cells make them resistant to programmed cell death (apoptosis) and so susceptible to the runaway cell division characteristic of cancer. Moreover, triggering cell death is the basis of cancer therapy.

Levels of epinephrine are chronically raised in the stressed and depressed, so Kulik’s research would suggest that overcoming these two problems might lead to a reduced risk of cancer. Writing in JBC, Kulik says that “Stress may both contribute to the development of cancer and may also reduce the effectiveness of cancer treatments.”

InChI=1/C9H13NO3/c1-10-5-9(13)6-2-3-7(11)8(12)4-6/h2-4,9-13H,5H2,1H3

Obesity Gene

Obesity overweightToday’s claims in the media about the recently discovered obesity gene are at best overwrought and at worst downright dangerous. A vast study involving more than twenty research centres across the UK has allegedly demonstrated that almost one fifth of us carry a variant of the gene known as FTO that predisposes us to obesity or overweight.

According to the researchers, “Obesity is a serious international health problem that increases the risk of several common diseases.” Fair comment. They add that, “The genetic factors predisposing to obesity are poorly understood.” Another fair comment.

They then report that while carrying out a genome-wide search for type 2 diabetes susceptibility genes among 13 groups of almost 40000 participants they have identified a common variant in the FTO gene that predisposes to diabetes through an effect on body mass index (BMI).

Additionally, the team reports that there is a cumulative, or additive, association of the variant with BMI. They found that 16% of the adults with the risky genetics weighed about 3 kilograms more than the others and were almost twice as likely to be obese, when compared to people without the risk allele. Moreover, the team says that they observe this genetic risk factor in individuals age 7 years and older and say that it reflects a specific increase in fat mass.

But, all this talk of obesity being down to genes will provide many individuals with an excuse along the lines of “it’s my glands”, which has become something of a serious cliche for some people who simply refuse to reduce the calorie intake and to add serious amounts of exercise to their daily routine.

The politics of obesity aside, I contacted metabolic expert Jeremy Nicholson of Imperial College London who recently discovered that calorie restriction in dogs extends life, reduces the risk of diabetes and metabolic disorders, and could be due to a change in the behaviour of microbes in the gut. He is less than impressed with the response of the media to the Science paper on FTO. “Basically, no amount of genetics can explain how humans have got fat so fast,” he told me. I would have to agree, genetics has long-term effects one usually does not see major changes in body function and form happening across a single generation.

So, might there be an alternative explanation for the apparent obesity epidemic in the developed world? Nicholson thinks so. “Changes in the gut microbes and caloric bioavailability probably could be the explanation,” he says. If we are suffering severe disturbances in the profile of gut bacteria – either they have changed behaviour or the species have changed – then those heading for overweight or who are already obese could be absorbing far more calories even from the same amount of food because of it.

Liposuction, like Vaser, Smartlipo and laser liposuction is one option, but could a dose of live yogurt or an antibiotic regimen be the solution to obesity? We are only just starting the hors d’heuvre when it comes to understanding the interplay between our bodies and microbes. Much more work into metabolism and the role of the guy microflora needs to be done before we can cast aside obesity as yet another genetic construct and so abandon sufferers to the realm of the untreatable.

Nicholson explains that the microflora in our gut are laid down in infancy and there is not a lot we can do about that. However, he says, “The real secret is eating a lot of beans and pulses (lentils etc) – lots of them every day, they keep the lower gut microbes very happy and the products of their
breakdown (catabolism) do not cause diabetes.” Nicholson laments that the windy side-effects of such a diet are far less malign than the problems associated with a diet deficient in beans and pulses.

Genetics, microbes, and beans aside, Nicholson has what I think has to be the final word on the debate: “Even genes and bugs added together still fade into insignificance if you sit on your butt all day eating pork rinds – you will get fat but its not genetic!”

Fault finding and interplanetary rubble

Fault findingThe latest issue of Intute Spotlight from David Bradley and the physical sciences portal is now online:

Fault finding [earth]

Almost half a million US dollars, about £250k, was earmarked by the National Science Foundation (NSF) for a project to map California’s San Andreas Fault, …

Science comes in from the cold [physics]

Research into the phenomenon formerly known as cold fusion is heating up again. Despite an initial chilly reception to anything related to this once-maverick science, it seems that studies of what are now called …

Interplanetary rubble [astronomy]

It’s not the most romantic image of heavenly bodies, but the latest observations of a pair of asteroids suggest that the pair is essentially two piles of rubble dancing an eternal pas de deux. The description emerges from a collation of observations from the world’s largest telescopes as well as the small instrument of a backyard amateur …

Spinneret Secret Unraveled

Spider silk is “pound for pound” stronger than steel and has a greater elasticity than rubber. Such properties would make it a rather useful material for a large variety of medical and engineering applications if only it could be made in large enough quantities and with a useful thickness and consistency.

Thomas Scheibel at the Technical University of Munich has now taken a step towards understanding the spider’s secret with a view to creating an artificial spinneret for producing unlimited quantities of spider silk. Writing in in Angewandte, the team explain how they have discovered that the interaction between the hydrophilic and lipophilic properties of the silk proteins plays an important role in the spinning process.

Fundamentally, the spinning of spider silk represents a phase change from a solution into a solid thread. The silk used by orb weaver spiders to spin the edges and spokes of their webs and to make a quick escape when attacked is composed of two different proteins. The Munich team has now successfully used genetic engineering to produce one of the spider silk proteins of the European garden spider (Araneus daidematus).

While purifying the protein by dialysis, the researchers observed the separation of two different fluid phases. Whereas one phase consisted of protein dimers, the second consisted of oligomers. After adding potassium phosphate, a natural initiator of silk aggregation, the liquid could be pulled into threads. “It is clearly not a structural change in the protein, but rather the degree of oligomerization that is crucial for thread formation,” concludes Scheibel.

Five times faster than BitTorrent

Similarity Enhanced TransferAnyone who has dared to download, a large file using the Bit Torrent system in which chunks of the file are pulled from other BT users in a form of distributed file sharing will know how slow (and sometimes how fast) the method can be. Although much of the BT system is exploited to share pirated movies and music it has a serious, legitimate side that also allows scientists, engineers and programmers to share the burden of huge database and ISO image downloads. Now, thousands of US tax dollars (in the form of an NSF CAREER grant) have been spent on improving on the Bit Torrent system.

David Andersen and colleagues at Carnegie Mellon University spotted the fatal flaw in torrents that often leads to the file sharing system grinding to a halt if the number of users with the complete or almost complete file are offline.

In conventional BT downloads, the files being shared must match exactly across the distributed sharing network or else they are ignored for download purposes. Anderson realized that identifying relevant chunks of files that may not be identical but are similar to a desired file could speed up Bit Torrent downloads. Anderson and his colleagues have designed Similarity-Enhanced Transfer (SET) to exploit this concept.

Anderson claims SET could make some transfers five times faster. “This is a technique that I would like people to steal,” Andersen said. Though he and his colleagues hope to implement SET in a service for sharing software or academic papers, they have no intention of applying it themselves to movie- or music-sharing services. “But it would make P2P transfers faster and more efficient,” he added, “and developers should just take the idea and use it in their own systems.”

SET works in a similar way to BitTorrent. Once a download is started, the source file is broken down into unique chunks. These chunks are downloaded simultaneously from accessible sources on the sharing network and then reassembled on the user’s computer. While this is underway, the SET program continues to search for similar files using a process called handprinting. In this method, sampling of non-identical files is used to find chunks that match the required chunks. Relevant chunks can then be downloaded from the similar files identified by this method, making the overall process much faster.

Although the researchers hope to use the SET approach for legitimate academic file sharing, they tested it on more common music and movie downloads. They saw a more than 70% improvement in downloading an mp3 file. A larger 55 Mb movie trailer was 30% faster when it could pull chunks from movie trailers that were 47 percent similar.

The researchers hope that such efficiency improvements will make SET part of the next generation of high-speed online multimedia delivery. “We believe that handprinting strikes an attractive balance for multi-source transfers. It efficiently locates the sources of exploitable similarity that have the most chunks to contribute to a receiver, and it does so using only a small, constant number of lookups. For these reasons, we believe that this technique is an attractive one to use in any multi-source file transfer system,” say the researchers.

R&R leads to molecular recovery

Mark Kuzyk is at it again. The physicist continues to explore a range of novel, light-sensitive compounds and has found one that degrades over time…but if kept in the dark for a short period of time, spontaneously heals itself. This amazing property could be exploited in industrial processes such as optical data storage and photolithography, which could use the recyclable material instead of having to replace the expensive stuff for every turn over.

Kuzyk and colleagues at Washington State University have found a molecule that loses its ability to fluoresce when bathed with laser light but regains this talent if it gets plenty of rest in the dark. Recovery starts during a half hour power nap and is complete after a good eight hours R&R, say the resarchers.

“It’s almost as if you have a piece of paper that’s yellowed over time, and you put it in a dark room for a day, and it comes back brand-new,” enthuses Kuzyk. Previously, I discussed Kuzyk’s work on Sciencebase and Intute Spotlight.

Kuzyk and students Ye Zhu and Juefei Zhou discovered the “self-healing” property of the dye AF455, which excels at two-photon absorption, an important property in optical data storage and in producing microelectronics for photolithography. The team will report details in the April 15 issue of the journal Optics Letters.

I received a follow-up email to this from Kuzyk: I’ve reproduced the Mark Kuzyk email here.

It’s a dog’s life

Puppy dogCutting out the French fries, burgers, chips, candy, beer, soda, and other delicious yet largely non-nutritious food and drink from your diet is generally a good idea. One of the reasons, health experts suspect, is that somehow a reduced-calorie diet leads to a longer life. Now, researchers at Imperial College London have looked at a dog’s life and discovered why dietary restriction could lead to a longer life.

Jeremy Nicholson and colleagues followed 12 “pairs” of dogs in which one partner in each pair was given 25% less food than the other. Nicholson and his colleagues found that the dogs who had less food lived almost 2 years longer (that perhaps equates to between 10 and 14 years). They also found that those dogs suffered less diabetes and osteoarthritis, and were older on average when plagued by the common diseases of old age.

But, why?

The scientists believe that differences in the populations of microbes in the dogs’ guts could partly explain the metabolic differences. The dogs that were not on a restricted diet had increased levels of potentially unhealthy aliphatic amines in their urine, the team found. The presence of higher levels of these compounds indicate reduced levels of choline, the compound essential for metabolizing fat. Such a microbial profile has, in other studies, been associated with the development of insulin resistance and obesity in humans.

Nicholson explains: “This fascinating study was primarily focused on trying to find optimized nutritional regimes to keep pet animals such as dogs healthy and as long-lived as possible. However these types of life-long studies can help us understand human diseases and aging as well, and that is the added bonus of being able to do long-term non-invasive metabolic monitoring.”

So, might this study be applicable to humans and should we too be cutting down on our doggy treats and Pedigree Chum? Potentially, yes. Despite superficial appearances and the sometimes disgusting things dogs choose to eat, the flora and fauna of our guts are very similar. It all depends on whether cutting your burger and soda intake by 25% is worth it for those extra 10 to 14 dog years.

Details of the study are published today in the Journal of Proteome Research. The paper is one in a special issue of the journal in “Metabolomics, Metabonomics, and Metabolic Profiling in Complex Organisms: The Portals to “Real-Life” Systems Biology”.

Choline chemical structure
InChI=1/C5H14NO/c1-6(2,3)4-5-7/h7H,4-5H2,1-3H3/q+1

In totally, unrelated canine news, scientists from the University of Utah and seven other institutions have identified a piece of doggy DNA that reduces the activity of a growth gene, ensuring that small breeds stay small. More on that via Newswise.

Getting up close and graphic with graphene

GrapheneGraphene recently hit the headlines as a potential replacement for silicon in a future world of molecular computing. However, until silicon technology has run its course and arrays of millions of transistors can be carved at will from this material, scientists will have to be content with investigating its properties and devising novel uses.

Nevertheless an international team led by scientists at MIT has turned the Raman spotlight on graphene and its chemical cousins to help them explain the materials’ unique physicochemical properties.

Mildred Dresselhaus of Massachusetts Institute of Technology, USA, and colleagues there and at the Federal University of Minas Gerais, Brazil, Tohoku University and CREST, Sendai, Japan, point out that Raman spectroscopy has played an important historical role in understanding graphitic materials. Most usefully, Raman can reveal information about defects and stacking of graphene sheets. The team has now used Raman to look at the modern counterparts of these materials, nanographites and individual graphene molecules.

You can read the whole story in this week’s SpectroscopyNOW news round-up from David Bradley.

A Tasty Approach to Flavanoids

FlavanoneThe flavanone structure is a tough act to swallow, synthetically speaking. Its the common skeleton for flavonoids and other compounds in plant-derived food and drink, such as red wine, dark chocolate, green tea, soy, milk thistle, kosam root, and citrus fruits, and are thought to have positive effects on health via anti-tumor and anti-inflammatory behavior. There are literally hundreds scattered throughout nature, but until now chemists had no straightforward method of synthesizing them with enantiomeric purity.

Karl Scheidt of Northwestern University and his colleagues have developed a general route to ten different chiral flavanones and chromanones that relies on simple bifunctional thiourea catalysts. The team reports how decarboxylation of the beta-ketoester proceeds smoothly in a one-pot reaction with 80-94% enantiomeric excess for aryl and alkyl substrates.

The method sets the stage for a new range of potential anticancer drugs ripe for testing. Further details can be found in JACS.

InChI=1/C15H12O2/c16-13-10-15(11-6-2-1-3-7-11)17-14-9-5-4-8-12(13)14/h1-9,15H,10H2