Abu Dhabi researcher closes in on elusive blue glow



ABU DHABI // As Pance Naumov settles into his new job at New York University Abu Dhabi this week, the task ahead of him sounds simple: to make a powder that glows blue when you squeeze it and fire a laser at it.

First, though, he has a bigger question to answer. Why, exactly, do the powders he works with glow under certain circumstances?

And when they do, what is it about them that makes them glow yellow, for example, rather than green?

The answers to these questions could have useful implications in the highly specialised field of sensor technology.

Dr Naumov, who is originally from the Republic of Macedonia, had already been working on them for some years in his previous post at Osaka University in Japan.

For a long time, he and his colleagues, led by José Lopez-de-Luzuriaga from the University of la Rioja, and Antonio Laguna from the University of Zaragoza, have been able to make metal-organic compounds that, when excited with a laser and put under pressure, give out green and red light.

Now, with research published in September's Journal of the American Chemical Society, they have yellow, too.

That means a third colour that can be used as a signal, either to show how much pressure is being applied to the material, or whether a particular gas is present.

Pressure sensors are all around us, controlling and monitoring thousands of everyday applications - in gears, vehicles or in packaging materials.

They can also be used to measure indirectly other variables, such as the flow of fluids or gases, speed, water levels and altitude.

When different pressures are applied, the luminescent material lights up a different colour; the broader the palette of available colours, the more precise information the sensor can indicate.

"This gives more control and more possibilities for application in the real world," said Dr Naumov.

The researchers were able to tune the luminescent colour of their materials by reassembling and altering the chemical bonds between tiny bimetallic clusters, each consisting of two atoms of gold and two of silver.

Using a property of gold known as aurophilicity - the tendency of gold atoms to clump together with weak gold-to-gold bonds - and another phenomenon called halogen bonding - the interaction between a halogen atom (such as fluorine, chlorine, bromine and occasionally iodine) and a "Lewis base" such as gold or silver to assemble the bimetallic clusters into linear chains.

By controlling the length of the chains, they were able to control the way they responded to pressure and gas. A longer chain gives off light with a longer wavelength - meaning light further towards the red end of the spectrum.

"Think of it as sewing beads on a thread - each bead is one gold-silver cluster, each of which consists of two atoms of gold and two atoms of silver," said Dr Naumov.

Previously, the researchers had managed to make single clusters, giving green light, or many clusters within the same chain, giving red.

Now they have managed to modify the ligand - the organic, halogen-containing substance that donates charge to the metal, which is what allows it to light up.

By using a ligand with a differently positioned halogen atom, they made a third structure - two clusters joined together, like a cartoon dumbbell - that emits a different colour of light from the other two.

Their usefulness in sensors comes from a curious property: under simple mechanical force - grinding, for example - or exposure to an organic vapour such as acetonitrile, the substances can be made to flip between the three structures.

Different structure, different coloured glow - so looking at the colour tells you what pressure it is under, or whether a particular gas is present. That gives it a wide range of potential applications; it could be used, for example, to detect pollutants near a factory after a chemical spill.

It would be built into sensor devices, as a tablet-shaped node of powder with a laser pointed at it. When the laser is switched on, if organic vapours are present the tablet would glow different colours depending on the amount of a gas present.

There is much work to be done, though, and Dr Naumov is still unclear exactly what is happening when the material is excited. Nor does he know why the different structures glow different colours.

He will try to get his answer by shining ultrashort pulses of laser light on the materials, using X-ray pulses to get high-resolution images of what is happening to the atomic structure of the material as it changes hue. The hope is that knowledge will lead Dr Naumov to his holy grail: blue. Blue light is often tricky; it has a shorter wavelength and is more energetic than red or green. Once researchers work out what's going on in the compounds, the hope is he will know how to get it to shine blue.

"We would like to have sensors that emit as many colours as possible," he said. "The more colours, the more possibilities."

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Stars: Alyssa Sutherland, Morgan Davies, Lily Sullivan
Rating: 5/5

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TOURNAMENT INFO

Women’s World Twenty20 Qualifier

Jul 3- 14, in the Netherlands
The top two teams will qualify to play at the World T20 in the West Indies in November

UAE squad
Humaira Tasneem (captain), Chamani Seneviratne, Subha Srinivasan, Neha Sharma, Kavisha Kumari, Judit Cleetus, Chaya Mughal, Roopa Nagraj, Heena Hotchandani, Namita D’Souza, Ishani Senevirathne, Esha Oza, Nisha Ali, Udeni Kuruppuarachchi

How Filipinos in the UAE invest

A recent survey of 10,000 Filipino expatriates in the UAE found that 82 per cent have plans to invest, primarily in property. This is significantly higher than the 2014 poll showing only two out of 10 Filipinos planned to invest.

Fifty-five percent said they plan to invest in property, according to the poll conducted by the New Perspective Media Group, organiser of the Philippine Property and Investment Exhibition. Acquiring a franchised business or starting up a small business was preferred by 25 per cent and 15 per cent said they will invest in mutual funds. The rest said they are keen to invest in insurance (3 per cent) and gold (2 per cent).

Of the 5,500 respondents who preferred property as their primary investment, 54 per cent said they plan to make the purchase within the next year. Manila was the top location, preferred by 53 per cent.

Scores:

Day 4

England 290 & 346
Sri Lanka 336 & 226-7 (target 301)

Sri Lanka require another 75 runs with three wickets remaining

UAE players with central contracts

Rohan Mustafa, Ashfaq Ahmed, Chirag Suri, Rameez Shahzad, Shaiman Anwar, Adnan Mufti, Mohammed Usman, Ghulam Shabbir, Ahmed Raza, Qadeer Ahmed, Amir Hayat, Mohammed Naveed and Imran Haider.

Australia tour of Pakistan

March 4-8: First Test, Rawalpindi

March 12-16: Second Test, Karachi

March 21-25: Third Test, Lahore

March 29: First ODI, Rawalpindi

March 31: Second ODI, Rawalpindi

April 2: Third ODI, Rawalpindi

April 5: T20I, Rawalpindi

US tops drug cost charts

The study of 13 essential drugs showed costs in the United States were about 300 per cent higher than the global average, followed by Germany at 126 per cent and 122 per cent in the UAE.

Thailand, Kenya and Malaysia were rated as nations with the lowest costs, about 90 per cent cheaper.

In the case of insulin, diabetic patients in the US paid five and a half times the global average, while in the UAE the costs are about 50 per cent higher than the median price of branded and generic drugs.

Some of the costliest drugs worldwide include Lipitor for high cholesterol. 

The study’s price index placed the US at an exorbitant 2,170 per cent higher for Lipitor than the average global price and the UAE at the eighth spot globally with costs 252 per cent higher.

High blood pressure medication Zestril was also more than 2,680 per cent higher in the US and the UAE price was 187 per cent higher than the global price.

No Windmills in Basra

Author: Diaa Jubaili

Pages: 180

Publisher: Deep Vellum Publishing 


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