Science – Page 293 – David Bradley

Periodic Table History

UPDATE: June 2011 – debate is raging as to what format the Periodic Table should ultimately take and indeed whether there is an ultimate, fundamental structure or whether it is merely a convenience. Check out the periodic table debate here.

Here’s a book no chemist, or indeed no scientist, should miss – The Periodic Table: Its Story and Its Significance, by UCLA chemical philosopher Eric Scerri. Older readers will recall my Alchemist interview with Eric Scerri.

The book has already had some excellent advance reviews, one in particular from my good friend John Emsley, of Cambridge U says: “Written to a high standard of scholarship, ‘The Periodic Table’ is the only book of its kind currently on the market, giving both an historical and philosophical perspective to the development of this key to the elements. The philosophical discussion Scerri weaves through its pages is rarely found in chemistry books, giving it a special quality that will appeal to the scientific community at large. In years to come it will be seen as essential reading for all who aspire to lecture and write on the subject.”

Peter Atkins, who I have never met admittedly, had this to say: “Few concepts are more important in chemistry than the periodic table, and Eric Scerri’s book offers a wonderfully thorough, lucid, and provocative introduction for both chemists and the scientifically literate to this major cultural contribution. Anyone interested in the foundations of chemistry will take delight, inspiration, and information from this highly approachable book.”

You can place an advance order via amazon, the book hits the shelves September 15 at $35 hardcover.

The Periodic Table

Turning Sperm Heads

Size really does matter! In fact a micro device that can analyse even the smallest of the small could help solve one of “man’s” greatest mysteries – what turns a sperm’s head and sends it in the direction of the egg for that fertilizatory encounter?

Sperm are well-known for turning their microscopic heads and changing direction (at least to those with a microscope who like to view such tiny events). Previous research (about which I wrote in 1991 under the heading “Not every sperm is sacred”) revealed that sperm turn in response to chemical signals, a process termed chemotaxis, and even have their own olfactory receptors. Such chemical messages may play key roles in the fertilization process. Defects in sperm chemotaxis may be a cause of infertility, and sperm chemotaxis could potentially be used as a diagnostic tool to determine sperm quality to treat male infertility.

However, Milos Novotny and Stephen Jacobson of Indiana University have developed a new tool to probe exactly how sperm chemotaxis occurs. In the current issue of Anal Chem, they describe the initial tests on their microfluidic device for studying sperm chemotaxis: “An advantage of the microfluidic platform over conventional chemotaxis assays is the ability to create chemical gradients with temporal and spatial stability, leading to greater repeatability in the experimental conditions.”

They add that microfluidic devices provide a convenient, disposable platform for conducting chemotaxis assays.

http://dx.doi.org/10.1021/ac052087i

Two-faced Electronic Paper

Two-faced microscopic beads that rotate through a half turn when an electric field is applied to them could be the key to creating electronic paper, according to Japanese scientists. Takasi Nisisako and his team in the Department of Precision Engineering at the University of Tokyo have developed a new technique that allows them to produce these “Janus” particles much more efficiently and with uniform size.

Other researchers have previously developed two-colored beads of between 30 and 150 micrometers diameter (a micrometer is a thousandth of a millimeter) for experimental electronic paper applications. A thin film of these particles is sandwiched between a control grid and a protective surface. Applying a voltage to specific regions of the layer through the control grid can make clusters of individual particles flip over so that they appear black against a background of un-flipped white particles. Such technology could allow a device to display an image, words or pattern that is retained using no additional power until an erase voltage is applied making the particles flip back to white.

Such electronic paper has not yet entered the mainstream electronic gadgetry market because making the particles all the same size and of consistent quality is difficult. Prototype devices based on these Janus particles cannot yet produce a perfect picture. Nisisako and his team have now solved the quality control problem by side-stepping the standard manufacturing approach and have instead turned to microfluidic technology.

The team built a tiny device that comprises a sliver of glass into which is etched a Y-shaped channel. The researchers then seal this beneath a second layer of glass leaving the ends of the channel open. The two starting ingredients are liquid monomers designed to produce particles that respond to an electric current and have a different color on each of their two faces. The team feeds each ingredient into the arms of the “Y” where the materials form a two-color stream at the junction, which travels down the leg of the “Y”. The emerging fluid droplets are all identical and are then “cured” to form solid microscopic particles.

By integrating any number of these microfluidic devices, Nisisako suggests it should be possible to scale-up the manufacture of Janus particles for commercial applications. He adds that their approach is not limited to polymer ingredients and making microparticles from other starting materials such as ceramics or metals should also be possible.

Advanced Materials

Science News with a Spectral Twist

Channelling toxins Novel treatments for high blood pressure and other disorders could emerge from high-resolution solid-state NMR studies that reveal how toxins affect the structure of potasssium channels in the cell.

Marc Baldus of the Max Planck Institute for Biophysical Chemistry in GÃ¶ttingen and colleagues in France and Germany have exploited a special protein synthesis procedure to follow how potassium channels and toxins combine to change the structure of the channel.

Zeolites step-by-step The evolution of zeolites has been followed by University of Minnesota chemical engineer Michael Tsapatsis and colleagues using microscopy and X-ray diffraction. Their study could lead to a new approach to designing and synthesizing novel variations on the zeolite theme for use as molecular sieves, catalysts, and sensors.

Analytical raft floats organic NLOs A combination of analytical techniques has proved its worth in assessing a series of non-linear optical materials for use in future organic optoelectronics devices. Juan LÃ³pez Navarrete of the University of Malaga, Spain, and colleagues at the University of Zaragoza-CSIC and the University of Minnesota, Morris, USA, used UV-vis, IR, and Raman spectroscopy, nonlinear optical (NLO) measurements, X-ray diffraction, and cyclic voltammetry to assess the properties of a series of tricyanovinyl (TCV)-substituted oligothiophenes.

A particularly golden study US researchers have devised what they describe as a very efficient method for making well-defined gold nanoparticles with equal numbers of hydrophobic and hydrophilic arms. The V-shaped arms are alternately distributed across the surface of 2 nanometre gold core particles. The solubility of these nanoparticles in a wide range of solvents means that they should be amenable to further processing with various chemical modifiers. Such nanoparticles have potential in optoelectronics, catalysis, and biomedical applications.

Cool Science Experiments

Sciencebase hosts a collection of science experiments from a cool coffee experiment to how to build a homemade electric motor.

Here is a brief list of possible science experiments, although Sciencebase no longer provides these particular write-ups you can download similar science projects via the links.

Black Light Experiment
Sinking and Floating Experiment
Oil and water experiment
Cartesian Diver Experiment
Why is the sky blue experiment
Clean up tarnished silver
Floating Soap Bubbles Experiment
Bending Water Experiment

Built in Code in Da Vinci Judgement

Mr Justic Peter Smith who recently presided over the alleged plagiarism UK case concerning Dan Brown’s The Da Vinci Code (it should really be The Leonardo Code, of course) and the “non-fiction” The Holy Blood and The Holy Grail turns out to be something of a wiggy wag.

Smith italicised a couple of dozen characters in his judgement which cleared Brown of the charges. So what, you might ask? Well, Smith is something of a code maker himself and confided in a Guardian journalist (once the lawyers finally spotted the wheeze) that the italics “don’t look like typos, do they?”

So here are those very letters:

j a e i e x t o s t g p s a c g r e a m q w f k a d p m q z v

The Register says Smith “will cough” as soon as someone figures it out. Be nice if it were a Sciencebase reader – let me know if you crack it!

Alchemical Slicing

Slicing up carbon to make a new class of electronics, caught The Alchemist’s eye first this week, and then a new class of antibiotics that slices up bacteria came to light. In this issue, we also learn how layered ceramics could build three-dimensional nano-devices and that cars produce too much carbon dioxide for environmental targets. Finally this week, designer zeolites could soon be with us thanks to a new model of the crystal growth process.

Check out The Alchemist’s discoveries on the relaunched ChemWeb site.

Defining Obesity

Following on from Wednesday’s posting on the subject of an obesity stifling pill, health professionals have been told that they need to use more than tape measures and scales to define and tackle obesity. The claim appears in the British Journal of Advanced Nursing.

Maryanne Davidson of Yale University discovered that many women fail to make the link between high weight and poor health and that culture is to blame, playing a key role in how positively they see themselves. Davidson reviewed key papers published over a 10-year period to see how health professionals and black and white American women define obesity and to identify differences in attitudes.

The study revealed that while health professionals used quantitative methods, such as Body Mass Index (BMI) measurements based on the height to weight ratio, women are more likely to base their ideal weight on cultural criteria. “My review revealed that black American participants defined obesity in positive terms, relating it to attractiveness, sexual desirability, body image, strength or goodness, self esteem and social acceptability,” Davidson says, “In addition they didn’t view obesity as cause for concern when it came to their health.”

White Americans, on the other hand, expressed completely the opposite view: “They defined obesity in negative terms, describing it as unattractive, not socially desirable, associated with negative body image and decreased self-esteem and being socially unacceptable,” explains Davidson. Worryingly, she adds, “when it came to the links between body weight and health, this group was much more likely to voice mixed views, with some expressing concern and others feeling that weight wasn’t a health issue.”

From the clinical care perspective, Davidson has also discovered that there are variations in how health professionals define obesity. “Although most of them use BMI to actually measure obesity, we found different views about what level of BMI constitutes normal weight and what level indicates obesity,” she says. Such findings provide a real challenge for healthcare professions.

People have been obsessed with their weight since records began, Davidson adds. She points out that the “Spartans” reportedly ostracised a man for being too fat and Socrates danced every day to keep his weight within reason! Such apocryphal tales tell us nothing about the health implications of being overweight today.

People see this as a genuine issue and spend a lot of money on trying to reduce their weight. Others spend time in the gym and take the healthy option while others face the risks of going under the knife. Bariatric surgery and liposuction prices are just a few of the factors that potential patients must consider.

“Obesity is a major issue for health professionals as it is emerging as a worldwide healthcare epidemic,” says Davidson, “The World Health Organization estimates that there are at least 300 million obese people worldwide and a further one billion who are overweight.”

Hormone Stifles Appetite, Fights Obesity

Researchers in the UK have discovered that topping up levels of a gut hormone could help people stave off feelings of hunger as well as increase activity in overweight and obese people.

According to research to be published in the International Journal of Obesity injections of the appetite-suppressing hormone oxyntomodulin, which is found in the lower intestine, have a “double effect” on people.

Chief researcher Steve Bloom of Imperial College London points out that, “The discovery that this hormone has a double effect, increasing energy expenditure as well as reducing food intake, could be of huge importance. When most people diet, this produces a reduction in activity, which is probably an adaptive trait to conserve energy during times of famine. However, this does make it especially difficult for obese individuals trying to loose weight. In contrast, oxyntomodulin decreases calorific intake, but actually increases energy expenditure, making it an ideal intervention for the obese.”

The research builds on Bloom’s earlier findings reported in the journal Diabetes in 2005, which were hailed as a major breakthrough in treating obesity.

Sex Gets Up Womens Noses

Spray-on sex could usher in an age of McNookie, according to an article in The Observer on Sunday. PT-141 is billed as libido in an atomiser, says the paper, and could finally offer women the chance to turn on their sexual desire as and when they need it.

“A dose of PT-141 results, in most cases, in a stirring in the loins in as little as 15 minutes,” reports Julian Dibbell, “Women, according to one set of results, feel ‘genital warmth, tingling and throbbing’, not to mention ‘a strong desire to have sex’.”

So, what is PT-141?

It’s an odourless and colourless synthetic chemical that you inhale deeply through a small, white plastic inhaler. The compound, produced by Palatin Technologies and currently undergoing regulatory assessment, is a melanocortin-based therapy that seems to work directly on the brain rather than simply stimulating the loins as is the case with Viagra.

The drug’s market name is Bremelanotide and it’s a word you’re sure to see a lot more of in the near future as spammers start offering it and variations on the theme (watch out for Bremelan0tide in your email subject lines). Its mode of action is poorly understood, but unlike thousands of years of rhino horn, tiger dick, and oysters this one definitely seems to work.

Molecular structure of Palatin's PT-141 (Bremelanotide)

“It’s not merely allowing a sexual response to take place more easily,” Michael Perelman, co-director of the Human Sexuality Program at New York Presbyterian Hospital and a sexual-medicine adviser on the PT-141 trials explains, “It may be having an effect, literally, on how we think and feel.” What is known is that it acts on at least one of five known melanocortin receptor subtypes in the brain. These are chemical receptors that regulate a diverse array of functions including sexual arousal, appetite, energy maintenance and inflammation. The company is working on drugs to affect these receptors and so help with sexual dysfunction, obesity and cachexia (disease-related muscle loss).

One has to wonder though whether the advent of drugs like PT-141 is simply another example of the kind of drug mongering I discussed a few years ago my Alchemist column on ChemWeb. There now seem to be dozens more “diseases” than there ever were. Is it just coincidence that problems that were not considered problems are now categorised as syndromes and disorders have emerged at just the time when the patents are expiring on the billion dollar staples of the pharmaceutical industry? Maybe, maybe not. Some of those disorders, such as restless legs syndrome, may sound like spurious ailments invented by a desperate industry, but they certainly aren’t for those who suffer from them. Even shyness and anxiety might one day succumb to drugs, and why not? If these disorders are debilitating then who are we to suggest that sufferers have no right to a treatment that “cures” them?

Sometimes there is no relief for a whole range of problems without pharmaceutical intervention. Whether or not we should allow people the option to control their sexual desire chemically is a moot point, the fact is humans have used all kinds of methods to loosen up a libido for millennia, and will continue to do so whether that’s with a regulated drug or something else. Palatin seems simply to be hoping to take a slice out of the action.

Anyway, for those interested in such things Palatin gives the basic structure of its product as a short cyclic peptide with the sequence – Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH. It’s currently in Phase III clinical trials, so it shouldn’t be too long before those spams start arriving.