Online – Page 11 – Akshat Rathi

New laser-printed material is lighter than water, as strong as steel

February 4, 2014 Akshat RathiLeave a comment

Materials shape human progress – think stone age or bronze age. The 21st century has been referred to as the molecular age, a time when scientists are beginning to manipulate materials at the atomic level to create new substances with astounding properties.

Taking a step in that direction, Jens Bauer at the Karlsruhe Institute of Technology (KIT) and his colleagues have developed a bone-like material that is less dense than water, but as strong as some forms of steel. “This is the first experimental proof that such materials can exist,” Bauer said.

Material world

Since the Industrial Revolution our demand for new materials has outstripped supply. We want these materials to do many different things, from improving the speed of computers to withstanding the heat when entering Mars’ atmosphere. However, a key feature of most new materials still remains in their strength and stiffness – that is, how much load can they carry without bending or buckling.

All known materials can be represented quite neatly in one chart (where each line means the strength or density of the material goes up ten times):

Jens Bauer/PNAS

The line in the middle at 1000kg/m³ is the density of water – all materials to its left are lighter than water and those on the right are heavier. Few fully dense solid materials are lighter than water. Those that are tend to be porous, like wood or bone, and they exhibit exquisite structures when observed under a microscope, and they served as inspiration for Bauer’s work.

For many years, material scientists have thought that some empty areas on the compressive strength-density chart should be filled by materials that theory predicts. Computer simulations could be used to indicate an optimum microstructure that would give a material the right properties. However, nobody had tools to build materials with defined patterns at the scale of a human hair.

With recent developments in lasers and 3D printing, however, a German company called Nanoscribe started offering lasers that could do just what Bauer wanted. Nanoscribe’s system involves the use of a polymer that reacts when exposed to light and a laser that can be neatly focused on a tiny spot with the help of lenses.

A drop of a honey-like polymer is placed on a glass slide and the laser is turned on. A computer-aided design is fed into the system and the slide carefully moves such that the laser’s stationary focus touches only those points where the material is to be made solid. Once complete, the extra liquid is washed away, leaving behind materials with intricate internal structures.

However, these materials on their own are not as strong as Bauer wanted. So he coats them with a thin layer of alumina (aluminium oxide) before subjecting them to stress tests. Based on the tests, he was able to improve the theoretical models he used to design the internal structure of the materials. Their results were just published in the Proceedings of the National Academy of Sciences.

Even though alumina layers increase the density of these materials, all of them remain lighter than water. Bauer’s strongest material has a specific honeycomb internal structure and is coated with a 50 nanometre-thick (billionth of a metre) layer of alumina. It beats all natural and man-made materials that are lighter than 1000kg/m³, being able to withstand a load of 280MPa (mega pascals is a unit of measuring pressure), which makes it as strong as some forms of steel.

There are limitations. Nanoscribe’s system can only make objects that are tens of micrometres in size. “One of their newer machines can make materials in the milimetre-range, but that’s about it for now”, Bauer added. But that is not enough for any real-life application.

However, there have been rapid improvements in all the areas this work relies on: 3D printing, new polymers and laser technology. That means we may soon have a suite of new, super lightweight materials for everything from skis to aircraft parts. If nothing else, Bauer’s work shows that we are definitely in the molecular age.

First published on The Conversation. Image credit: Jens Bauer.

Is education the great leveller? No, says UNESCO

January 31, 2014April 18, 2014 Akshat RathiLeave a comment

Immigrant students and those from poor backgrounds living in developed countries are being failed by the school system and face a high risk of marginalisation, according to a UNESCO report.

Data from the 2009 results of the OECD’s Programme for International Student Assessment (PISA) shows that only 60% of French 15-year-old students pass the minimum benchmark for reading if they are immigrants. This is the same proportion achieved by an average Mexican student. Non-immigrant students in France fare much better, with 82% achieving that benchmark.

Similarly, reading levels of England’s immigrant students’ are on par with an average student in Turkey, and Germany’s are on par with an average student in Chile.

According to Stephen Gorard, professor of education and public policy at Durham University, “On average economic migrants and refugees from less educated social backgrounds may tend to do worse, wherever they go.” He said that when UNESCO quotes difference in attainment rates for immigrants in different countries, “it is important to bear in mind how developed these countries are and where the influx is from.”

This comparison between immigrants and non-immigrants may mask issues over first-generation immigrants studying in a second language. Gorard said factors of social class are of key importance. Where new children perform worse at school than their indigenous peers, “this is not necessarily a consequence of their immigrant status of their treatment by others.”

The key question is what happens over time, perhaps over a generation or two. But, he said, “This is in no way an excuse for situations where there is direct evidence of unfair treatment of recent immigrant students.”

A 2013 report by the Coram Children’s Legal Centre, pointed to chidren of some migrants being denied access to education and housing.

Their analysis found that in England, the gap between rich and poor children achieving minimum levels in maths grows as they progress through school. At grade four (nine-year-olds), the gap was 8%, but it was 19% by grade eight (13-year-olds).

New Zealand has similar disparities, with only two thirds of poor students achieving standards, compared to nearly all rich students. In Australia, the problem has persisted for more than a decade, with two-thirds of indigenous grade 8 students achieving the minimum level in maths between 1994-5 and 2011, compared to 90% of non-indigenous students.

Such discrepancies are not inevitable. Policies in East Asian countries such as Japan and Korea, as well as in Finland, have promoted quality teaching and helped level reduce disparities in learning, creating a level playing field for students from different social class.

Policy interventions to address discrepancies between ethnic groups can be difficult to get political attention. When it comes to analysis of achievement of different ethnic groups, David Gilborn, professor of critical race studies at the University of Birmingham, said race equality isn’t currently taken very seriously in debates around education in the UK. “I think certainly over the last few years, policymakers have not just taken their eye off the ball in terms of inclusive education. They’ve removed it from the agenda all together.”

Gilborn has worked on the differences in attainment between children of black Caribbean heritage, and the national average, which he said remain pronounced. “Education policy at the moment is dominated by a kind of colour blind rhetoric that emphasises standards and choice, and if anything, talk about inclusion and social justice tends to emphasise a particular view of white students being the race victims,” he said.

The UNESCO report points out that 250m of the world’s 650m primary school-age children are not learning the basics of reading and maths. The researchers put the cost of this to governments at $129bn, or 10% of global spending on primary education.

Bearing the price in mind and the fact that many of the children going through the school system are not actually achieving basic levels in reading and maths, it is possible to break down the cost-efficiency of spending on primary education. For example, in Burundi, the average spend per pupil is $60. But if you remove those who are not learning the basics, and the cost per pupil is $204.

Written with Gemma Ware. First published on The Conversation.

Image credit: PennState

Olympic costs always overrun, but nobody really cares

January 30, 2014January 30, 2014 Akshat RathiLeave a comment

As we inch towards the start of the winter Olympics in Sochi, Putin’s government would be happy that soon they won’t have to keep draining their banks. All costs included, it is estimated that Russians will have spent $51 billion to host the event. This makes it the most expensive Olympic games ever held.

What’s worse is that Sochi has only one-third the number of events compared to the summer version of the games. On average, then, each Sochi event will cost $520m, nearly four times that of Beijing 2008 Olympic games, which costed an overall $43 billion.

The initial budget, according to the original bid, was about $12 billion. The spiralling costs have brought accusations of corruption and waste on the Kremlin. For instance, the Russians have spent $8.7 billion just to construct a 31-mile rail and road connection between Adler and Krasnaya Polyana. According to an estimate by the Russian Esquire magazine, that would be the same price if the road were to be covered with a one-centimetre layer of Beluga caviar.

According to an analysis by Bent Flyvbjerg, chair of major project management at the University of Oxford, and his colleague Allison Stewart, all Olympic games since 1960 have had a cost overrun. On average, they cost nearly three times the initial budget.

In their analysis Flyvbjerg and Stewart only considered sports-related direct costs, such as building stadiums and paying staff for running events. Other indirect costs, such as new infrastructure in the form of highways or hotels, were not included because of lack of reliable data. But these costs can be significant, especially in developing countries or completely new locations. And they are reflected in the price tag for the games in Sochi and Beijing.

According to Will Jennings at the University of Southampton, as he writes on The Conversation, such mega-events offer great opportunities to emerging economies with a potential audience of billions. However, their leaders often don’t take into account the spiralling financial and human costs associated with them.

Or, alternatively, it might be that they don’t care about those costs. Of the 27 games held between 1960 and 2012, only 16 could be duly analysed by Flyvbjerg and Stewart. They write that the lack of data means “for 41% of Olympic Games (we analysed) no one asked how well the budget held thus hampering learning regarding how to develop more reliable ones”.

So it is anybody’s guess whether these games are hosted to get a country that much-needed economic boost or just to showcase their global ambitions regardless of the price.

First published on The Conversation.