Month: January 2007

Icy blast from the past

Cerro HudsonWhat’s the connection between Antarctic ice, old volcanic eruptions and global warming? US researchers think they know.

Volcanic activity can have serious consequences for climate change as particles and gases spewed out by volcanoes enter the upper atmosphere and change its chemical balance altering how Solar radiation is absorbed or reflected. Now, French and US researchers have devised a technique for determining how past volcanic eruptions could have affected this delicate chemical balance. Their findings could reduce significantly the uncertainty in current models of global climate change and so provide more accurate predictions of future global temperatures.

Joël Savarino of the National Center for Scientific Research (CNRS) and the University of Grenoble in France together with colleagues at the University of California San Diego have reported the pattern of sulphur isotopes of volcanic fallout from past eruptions. They also determined how far into the upper atmosphere the volcanic material reached, and what chemical reactions might have occurred there.

More…

Hewlett Packard to Dell again

Sciencebase is not a gadget-fixated site, as regular readers will by now have realized. We leave that to the likes of gizmodo and techcrunch who bring their thousands of subscribers the latest and greatest in carbon-dioxide generating machines and energy-drains as fast as you can say LG chocolate and USB toothbrush. Nevertheless, we are a science and tech site, and we do like to keep up with some of the more techy developments, such as wireless USB and the latest developments in blogging software.

In the spirit of Alex Lifeson’s tourbook instruments page, I was going to provide readers with a list of the gadgets that help keep Sciencebase on its feet, but I changed my mind, there are so few. One thing that I do rely heavily on is a widescreen laptop, although I regret opting for a lower resolution than usual version for the sake of price recently. My previous 17″ widescreen with almost 2000 pixels width was much easier to use than this 15 incher.

LED chips

LED ChipsLight-emitting diodes almost ubiquitously provide the illumination in electronics and potentially will provide energy-efficient brightness in our homes. However, the LED material of choice, gallium nitride, and its method of processing and manufacture into working devices is relatively expensive. Now, US engineers have developed a novel semiconducting material based on zinc oxide that could be used in a new type of LED that is just as effective but could reduce costs for a wide range of applications.

According to Deli Wang and colleagues at the University of California San Diego, an LED requires a positive and a negative semiconducting material. While “n-type” negative-charge carrying nanowires of inexpensive zinc oxide have been easy to make, the researchers have now synthesized nanoscale cylindrical wires of the material that can transport positive charges. These so-called “p-type ZnO nanowires” complete the circuit for making a new type of inexpensive LED.

You can read the full story in the January issue of Intute Spotlight.

Molecular speed bumps

Mark KuzykRegular readers will recall my mention of the Kuzyk Quantum Gap a few days ago and how Intute Spotlight would be covering news on how Kuzyk himself is closing the gap.

Well, here’s the spin: New organic molecules that interact with light more strongly than any other materials could provide the template for new high-speed optical switches for telecommunications and data processing, according to an international team of researchers. The same compounds could also act as the basic units of optical memory systems and be used to produce high-density holograms.

Researchers from Washington State University (WSU), the University of Leuven in Belgium and the Chinese Academy of Sciences have developed and tested an entirely new class of chromophores. The chemists in China synthesised the compounds, which were then evaluated using theoretical calculations by scientists at WSU. The optical properties were then tested by the Belgian team. ‘To our great excitement, the molecules performed better than any other molecules ever measured,’ says WSU physicist Mark Kuzyk.

Read on…

Help with total synthetic spam

Diketone structureSpam comes in all shapes and forms, so I am always suspicious when two emails identical in content and with attachments arrive that purport to be from two different correspondents. However, two such messages arrived this morning one claiming to come from a Dr Suhasini Bhatnagar, the other from Aarif Khatri. Normally, I’d let my spam filter do its job and trash such messages, but my interest was piqued by the subject line, which read “help regarding synthesis”. Often spam arrives with two random words stuck together that are supposed to beat spam filters, but three is rare and even less frequent are subject lines that make logical sense and simultaneously are pertinent to my interests.

So, I read on…

This is what Dr Bhatnagar (and presumably his chemistry supervisor, Prof Khatri) had to say:

“I was looking for help regarding the organic synthesis of a compound…I am doing My DSc from Agra University and the first part of work lasting now for past 3 years was involving Bioinformatics and its now that i need to synthesise the organic diketone type of compound [4-(2,4-dioxopentyl)benzoic acid] and I do not know how. Can you please help me design a simple reaction wherein I can get a few grams of the compound. I have very very limited resources and also knowledge in the subject. Your help would be greatly appreciated.”

Now, it is too far in the dim and distant past when I last did a retrosynthetic analysis, so I’m going to duck out of taking up his offer, but I wondered whether any Sciencebase readers could shed any light on the relevance of this compound and whether or not a total synthesis would be readily accessible. Your comments may also enlighten me as to whether these emails were nothing more than an intricate social engineering endeavour and that I’ve been duped into responding in this way.

I hope not.

Solvent abuse

Adolescent drug use has fallen overall since the late 1990s, but the “recreational” use of solvents is on the increase. Solvent, or inhalant, abuse is now the fourth most abused drug among US teens according to NIDA.

Inhalants, which include volatile organic compounds such as butane and aromatic hydrocarbons (like toluene) activate the same areas of the brain as do other drugs of abuse. However, understanding their precise mode of action has not been clarified until now.

Toluene is found in paint thinners, varnishes and even nail polish remover and is commonly abused and new research shows that it stimulates dopamine release in specific regions of the brain known as drug reward pathways. The results, obtained by Arthur Riegel and colleagues at the Vollom Institute, in Portland, Oregon, suggest that the brain interprets inhalation of toluene as a rewarding experience which can result in continued abuse and re-abuse.The findings could help in developing strategies to prevent and treat addiction to substances containing toluene.

Surprisingly, researchers also found that toluene-containing substances are most effective at low concentrations. Since toluene is rapidly absorbed by the brain, this might explain why the preferred mode of delivery is by “huffing” or “sniffing”. Sniffing is frequently considered a harmless recreational or party drug but unlike other drugs, even a single session of inhaling the compound can disrupt heart rhythms enough to cause cardiac arrest and lower oxygen levels enough to cause suffocation. Not a good thing.

The research is published today in the journal Neuropsychopharmacology.

Obesity and colon cancer link

Obesity is a major risk factor for colon cancer, but until now medical scientists were at a loss to explain why. Now, a study of on three human colon cancer cell-lines has demonstrated that the “fat hormone” leptin may enhance the growth of colonic cancer cells. The discovery not only offers an explanation as to the underlying cause of the increase colon cancer risk in obesity but could lead to a new approach to fighting this type of cancer.

The hormone leptin is released by fat cells, adipocytes, so the higher your body fat content (calculate your body fat now), the higher the concentration of leptin in your blood stream is likely to be. Leptin plays a key role in regulating metabolism, body weight and energy expenditure.

According to previous research, people who are obese are two to three times more likely to develop colon cancer than their leaner counterparts. Other research revealed that some colon cancer cells carry receptors for leptin.

Now, scientists at the University of California San Diego School of Medicine believe they have found the link.

“These results may explain why obesity increases a person’s risk of colonic cancer, and the fact that we have shown how leptin stimulates these cells means that drug companies may be in a better position to develop new treatments against the disease,’ says UCSD’s Kim Barrett.

The team grew cancer cells in the laboratory and found that leptin could stimulate their growth. In two out of three cell lines, leptin also blocked normal programmed cell death, apoptosis, which usually prevents runaway cell growth. When apoptosis fails normal cells can become cancerous.

The researchers explain that they have also found the complex chemical signalling pathways in the cell that are influenced by leptin, which reinforces their claim that leptin does indeed play a critical part in influencing cancer cell growth in the colon.

The results are published in detail in the journal BJS.

Two for tea

Two tea time stories in the news today. The first reports on a very small study showing that adding milk to tea negates the cardiovascular health benefits because it interferes with nitric oxide (NO), the natural vasodilation controller (You’ll know it from my article on Viagra. The second news item is about the antibacterial effects of green tea (it doesn’t say whether adding milk negates those benefits, but I cannot imagine drinking green tea with milk anyway.)

New York Smells

Today, the New York City authorities were investigating a persistent smell of “gas” across a large part of the lower Manhattan area of the city.

Hundreds of people reported the odd, but apparently not noxious smell, to the New York Police Department, but at the time of writing the identity of the gas remained unknown. Despite this, Mayor Michael Bloomberg somehow manages to make confident proclamations that the gas is “not dangerous”.

Over on Digg, a heated debate has been raging since the first news of the mystery smell was released on an unsuspecting public. Some members of the so-called online “news” community, claim to live in NYC and that there is no smell. Others muse that Howard Stern is to blame, while yet others are confused as to whether this represents a homeland security issue.

Some New Yorkers are saying the gas smells of gasoline (petrol to those of us this side of the pond), while others reckon it’s more like natural gas (methane, of course, has no odour so a very strong smelling sulfur-containing compound – mercaptan – is added in tiny amounts to give it a smell).

The BBC reported that the source was across the Hudson River in New Jersey, where officials said a natural gas leak originating in the Chelsea district of Manhattan, had occurred.

New York, new york, so good they named it twice…

Explosive Electronics

I am currently writing about the latest research from Mark Kuzyk – famed discoverer of the Kuzyk effect also known as the Kuzyk quantum gap. He and his colleagues have discovered a whole new class of compounds that could eventually revolutionize optical information processing (more on that in the January issue of Intute Spotlight). Anyway, he told me that getting a stronger and stronger optical, so-called non-linear response, from the materials he and his colleagues are devising will “require deliberate and painstaking molecular design and synthesis.”

But, there are also some even more serious obstacles than acumen in synthetic chemistry. He explained that molecules that have a large nonlinear-optical susceptibility, i.e. are perfect for the job in hand are often rather unstable too. Now, obviously that’s something that you have to avoid if you’re going to incorporate a molecule into a device (ask Richard Friend who has spent the last decade and a half working with his chemist colleagues to make their plastic LEDs not only bright and useful but as long-lived as possible).

All compounds are created with an intrinsic stability but some are created more unstable than others. Kuyzk told me that he had once suggested to a chemist colleague when he was at Bell Labs in the 1980s that he should try and make a specific molecule the structure of which should have produced a large optical response. “He laughed when he saw the structure,” Kuyzk said, “claiming that it would be much more explosive than TNT.” Now, I wouldn’t have liked to have been the project student charged with synthesising that nonlinear optical compound without some understanding of the stability, or otherwise, of conjugated organic bonding systems.

On a related matter, photo-stability (as opposed to thermal stability), Kuzyk also revealed to me that several years ago, a student in his group, Brent Howell, serendipitously stumbled upon a dye-doped polymer system that not only acted as a laser but recovered from photo-degradation if the system was left in the dark for a couple of days.

Furthermore, the material could be hardened to photodegradation by cycling through degradation and recovery. “We have proposed a model of the mechanisms, and are still doing experiments to test our hypothesis,” Kuyzk adds. A paper that shows recovery in two-photon absorbing materials appears in Optics Letters.