Featured Research

from universities, journals, and other organizations

How the kilogram has put on weight

Date:
January 7, 2013
Source:
Newcastle University
Summary:
Using a state-of-the-art Theta-probe XPS machine, experts in the UK have shown the original kilogram is likely to be tens of micrograms heavier than it was when the first standard was set in 1875. And they say a suntan could be the key to helping it lose weight.

Post-Christmas and most of us are feeling the over-indulgence. But take heart -- experts at Newcastle University have shown even the kilogram itself has put on weight.

Using a state-of-the-art Theta-probe XPS machine -- the only one of its kind in the world -- the team have shown the original kilogram is likely to be tens of micrograms heavier than it was when the first standard was set in 1875.

And they say a suntan could be the key to helping it lose weight.

The original kilogram -- known as the International Prototype Kilogram or the IPK -- is the standard against which all other measurements of mass are set. Stored in the International Bureau of Weights and Measures in Paris, forty official replicas of the IPK were made in 1884 and distributed around the world in order to standardise mass. The UK holds replica 18 at the National Physical Laboratory (NPL).

But despite efforts to protect the IPK and its duplicates, industrialisation and modern living have taken their toll on the platinum-based weights and contaminants have built up on the surface.

Now Professor Peter Cumpson and Dr Naoko Sano have used cutting-edge X-ray Photoelectron Spectroscopy (XPS) to analyse surfaces similar to the standard kilogram to assess the build-up of hydrocarbons -- and how to remove them.

Publishing their findings this month in the journal of Metrologia, they reveal how giving the kilogram a suntan could be the answer to helping it lose weight.

"Statute decrees the IPK is the kilogram," explains research lead Peter Cumpson, Professor of MicroElectroMechanical Systems (MEMS) at Newcastle University.

"It doesn't really matter what it weighs as long as we are all working to the same exact standard -- the problem is there are slight differences. Around the world, the IPK and its 40 replicas are all growing at different rates, diverging from the original.

"We're only talking about a very small change -- less than 100 micrograms -- so, unfortunately, we can't all take a couple of kilograms off our weight and pretend the Christmas over-indulgence never happened.

"But mass is such a fundamental unit that even this very small change is significant and the impact of a slight variation on a global scale is absolutely huge. There are cases of international trade in high-value materials -- or waste -- where every last microgram must be accounted for.

"What we have done at Newcastle is effectively give these surfaces a suntan. By exposing the surface to a mixture of UV and ozone we can remove the carbonaceous contamination and potentially bring prototype kilograms back to their ideal weight."

The kilogram is one of the seven SI base units from which all other units can be derived and is the only one which is measured against a physical object -- the IPK -- all others are standardised against known constants.

The Newcastle team are now moving on to study the addition of mercury from the atmosphere, something Professor Cumpson first identified while working at the NPL in the 1990's. But it is the development of techniques such as XPS which has allowed them to accurately measure how the build up of chemicals such as hydrocarbons can be most effectively removed.

Newcastle University hosts the 3million National XPS service funded by the Engineering and Physical Sciences Research Council (EPSRC).

Using a Theta-probe XPS machine -- the only one of its kind in the world -- Professor Cumpson and Dr Sano showed how the UV/ozone wash could be used to remove contamination without damaging the platinum surface.

"The Theta probe allows us to look at the composition of very thin layers by measuring the angle at which the electrons emerge from it," explains Professor Cumpson.

"Rather like an MRI scanner, it takes a cross section of the material but at an atomic level. The second part of the machine is the Argon cluster ion gun -- which fires charged 'droplets', each containing about a thousand Argon atoms -- and it is this which makes the Newcastle machine unique.

"The Argon cluster ion gun allows us to analyse organic materials without damaging the inorganic surface, in this case the platinum alloy."

Work is underway internationally in several National Measurement Institutes to find an alternative to the IPK -- a standardised value for the kilogram that is not based on a matchbox- sized piece of metal. But until then, the prototype kilograms are what the world relies on for its mass scale.

"If the kilogram does put on weight then it's imperative that we understand exactly how the IPK is changing," says Professor Cumpson.


Story Source:

The above story is based on materials provided by Newcastle University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Peter Cumpson, Naoko Sano. Stability of reference masses V: UV/ozone treatment of gold and platinum surfaces. Metrologia, 2013; 50 (1): 27 DOI: 10.1088/0026-1394/50/1/27

Cite This Page:

Newcastle University. "How the kilogram has put on weight." ScienceDaily. ScienceDaily, 7 January 2013. <www.sciencedaily.com/releases/2013/01/130107082614.htm>.
Newcastle University. (2013, January 7). How the kilogram has put on weight. ScienceDaily. Retrieved July 26, 2014 from www.sciencedaily.com/releases/2013/01/130107082614.htm
Newcastle University. "How the kilogram has put on weight." ScienceDaily. www.sciencedaily.com/releases/2013/01/130107082614.htm (accessed July 26, 2014).

Share This




More Matter & Energy News

Saturday, July 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins