P&R Labpak - Everything for your laboratory

P&R Labpak - Everything for your laboratory
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Tuesday, 18 April 2017

Mission control: salty diet makes you hungry, not thirsty

We've all heard it: eating salty foods makes you thirstier. But what sounds like good nutritional advice turns out to be an old-wives' tale. In a study carried out during a simulated mission to Mars, an international group of scientists has found exactly the opposite to be true. "Cosmonauts" who ate more salt retained more water, weren't as thirsty, and needed more energy.

Salt shaker, by Dubravko Sorić SoraZG on Flickr [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
For some reason, no one had ever carried out a long-term study to determine the relationship between the amount of salt in a person's diet and his drinking habits. Scientists have known that increasing a person's salt intake stimulates the production of more urine - it has simply been assumed that the extra fluid comes from drinking. Not so fast! say researchers from the German Aerospace Center (DLR), the Max Delbrück Center for Molecular Medicine (MDC), Vanderbilt University and colleagues around the world. Recently they took advantage of a simulated mission to Mars to put the old adage to the test. Their conclusions appear in two papers in the current issue of The Journal of Clinical Investigation.

What does salt have to do with Mars? Nothing, really, except that on a long space voyage conserving every drop of water might be crucial. A connection between salt intake and drinking could affect your calculations - you wouldn't want an interplanetary traveler to die because he liked an occasional pinch of salt on his food. The real interest in the simulation, however, was that it provided an environment in which every aspect of a person's nutrition, water consumption, and salt intake could be controlled and measured.

The studies were carried out by Natalia Rakova (MD, PhD) of the Charité and MDC and her colleagues. The subjects were two groups of 10 male volunteers sealed into a mock spaceship for two simulated flights to Mars. The first group was examined for 105 days; the second over 205 days. They had identical diets except that over periods lasting several weeks, they were given three different levels of salt in their food.

The results confirmed that eating more salt led to a higher salt content in urine - no surprise there. Nor was there any surprise in a correlation between amounts of salt and overall quantity of urine. But the increase wasn't due to more drinking - in fact, a salty diet caused the subjects to drink less. Salt was triggering a mechanism to conserve water in the kidneys.

Before the study, the prevailing hypothesis had been that the charged sodium and chloride ions in salt grabbed onto water molecules and dragged them into the urine. The new results showed something different: salt stayed in the urine, while water moved back into the kidney and body. This was completely puzzling to Prof. Jens Titze, MD of the University of Erlangen and Vanderbilt University Medical Center and his colleagues. "What alternative driving force could make water move back?" Titze asked.

Experiments in mice hinted that urea might be involved. This substance is formed in muscles and the liver as a way of shedding nitrogen. In mice, urea was accumulating in the kidney, where it counteracts the water-drawing force of sodium and chloride. But synthesizing urea takes a lot of energy, which explains why mice on a high-salt diet were eating more. Higher salt didn't increase their thirst, but it did make them hungrier. Also the human "cosmonauts" receiving a salty diet complained about being hungry.

The project revises scientists' view of the function of urea in our bodies. "It's not solely a waste product, as has been assumed," Prof. Friedrich C. Luft, MD of the Charité and MDC says. "Instead, it turns out to be a very important osmolyte - a compound that binds to water and helps transport it. Its function is to keep water in when our bodies get rid of salt. Nature has apparently found a way to conserve water that would otherwise be carried away into the urine by salt."

The new findings change the way scientists have thought about the process by which the body achieves water homeostasis - maintaining a proper amount and balance. That must happen whether a body is being sent to Mars or not. "We now have to see this process as a concerted activity of the liver, muscle and kidney," says Jens Titze.

"While we didn't directly address blood pressure and other aspects of the cardiovascular system, it's also clear that their functions are tightly connected to water homeostasis and energy metabolism."

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Monday, 10 April 2017

The chemistry behind the new one pound coin

We all know that money makes the world go around, but do you know what goes into it? The new pound coin arrived on 28th March, largely as a preventative measure against counterfeiting.  Take a look at the graphic below for more information about its composition.

Source: Compound Interest

Why the new coin is harder to counterfeit:
  1. 12-sided - its distinctive shape means it stands out by sight and by touch
  2. Bimetallic - The outer ring is gold coloured (nickel-brass) and the inner ring is silver coloured (nickel-plated alloy)
  3. Latent image - it has an image like a hologram that changes from a '£' symbol to the number '1' when the coin is seen from different angles
  4. Micro-lettering - around the rim on the heads side of the coin tiny lettering reads: ONE POUND. On the tails side you can find the year the coin was produced
  5. Milled edges - it has grooves on alternate sides
  6. Hidden high security feature - an additional security feature is built into the coin to protect it from counterfeiting but details have not been revealed

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Monday, 3 April 2017

New device produces hydrogen peroxide for water purification

Limited access to clean water is a major issue for billions of people in the developing world, where water sources are often contaminated with urban, industrial and agricultural waste. Many disease-causing organisms and organic pollutants can be quickly removed from water using hydrogen peroxide without leaving any harmful residual chemicals. However, producing and distributing hydrogen peroxide is a challenge in many parts of the world.

Purified drinking water

Now scientists at the Department of Energy's SLAC National Accelerator Laboratory and Stanford University have created a small device for hydrogen peroxide production that could be powered by renewable energy sources, like conventional solar panels.

"The idea is to develop an electrochemical cell that generates hydrogen peroxide from oxygen and water on site, and then use that hydrogen peroxide in groundwater to oxidize organic contaminants that are harmful for humans to ingest," said Chris Hahn, a SLAC associate staff scientist.

Their results were reported March 1 in Reaction Chemistry and Engineering.
The project was a collaboration between three research groups at the SUNCAT Center for Interface Science and Catalysis, which is jointly run by SLAC and Stanford University.

"Most of the projects here at SUNCAT follow a similar path," said Zhihua (Bill) Chen, a graduate student in the group of Tom Jaramillo, an associate professor at SLAC and Stanford. "They start from predictions based on theory, move to catalyst development and eventually produce a prototype device with a practical application."

In this case, researchers in the theory group led by SLAC/Stanford Professor Jens Nørskov used computational modeling, at the atomic scale, to investigate carbon-based catalysts capable of lowering the cost and increasing the efficiency of hydrogen peroxide production. Their study revealed that most defects in these materials are naturally selective for generating hydrogen peroxide, and some are also highly active. Since defects can be naturally formed in the carbon-based materials during the growth process, the key finding was to make a material with as many defects as possible.

"My previous catalyst for this reaction used platinum, which is too expensive for decentralized water purification," said research engineer Samira Siahrostami. "The beautiful thing about our cheaper carbon-based material is that it has a huge number of defects that are active sites for catalyzing hydrogen peroxide production."

Stanford graduate student Shucheng Chen, who works with Stanford Professor Zhenan Bao, then prepared the carbon catalysts and measured their properties. With the help of SSRL staff scientists Dennis Nordlund and Dimosthenis Sokaras, these catalysts were also characterized using X-rays at SLAC's Stanford Synchrotron Radiation Lightsource (SSRL), a DOE Office of Science User Facility.

"We depended on our experiments at SSRL to better understand our material's structure and check that it had the right kinds of defects," Shucheng Chen said.

Finally, he passed the catalyst along to his roommate Bill Chen, who designed, built and tested their device.

"Our device has three compartments," Bill Chen explained. "In the first chamber, oxygen gas flows through the chamber, interfaces with the catalyst made by Shucheng and is reduced into hydrogen peroxide. The hydrogen peroxide then enters the middle chamber, where it is stored in a solution." In a third chamber, another catalyst converts water into oxygen gas, and the cycle starts over.

Separating the two catalysts with a middle chamber makes the device cheaper, simpler and more robust than separating them with a standard semi-permeable membrane, which can be attacked and degraded by the hydrogen peroxide.

The device can also run on renewable energy sources available in villages. The electrochemical cell is essentially an electrical circuit that operates with a small voltage applied across it. The reaction in chamber one puts electrons into oxygen to make hydrogen peroxide, which is balanced by a counter reaction in chamber three that takes electrons from water to make oxygen - matching the current and completing the circuit. Since the device requires only about 1.7 volts applied between the catalysts, it can run on a battery or two standard solar panels.

The research groups are now working on a higher-capacity device.

Currently the middle chamber holds only about 10 microliters of hydrogen peroxide; they want to make it bigger. They're also trying to continuously circulate the liquid in the middle chamber to rapidly pump hydrogen peroxide out, so the size of the storage chamber no longer limits production.

They would also like to make hydrogen peroxide in higher concentrations. However, only a few milligrams are needed to treat one liter of water, and the current prototype already produces a sufficient concentration, which is one-tenth the concentration of the hydrogen peroxide that you buy at the store for your basic medical needs.

In the long term, the team wants to change the alkaline environment inside the cell to a neutral one that's more like water. This would make it easier for people to use, because the hydrogen peroxide could be mixed with drinking water directly without having to neutralize it first.

The team members are excited about their results and feel they are on the right track to developing a practical device.

"Currently it's just a prototype, but I personally think it will shine in the area of decentralized water purification for the developing world," said Bill Chen. "It's like a magic box. I hope it can become a reality."

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Monday, 27 March 2017

On this day in science history: polyethylene was discovered

Polyethylene was first synthesized by the German chemist Hans von Pechmann, who prepared it by accident in 1898 while investigating diazomethane. When his colleagues Eugen Bamberger and Friedrich Tschirner characterized the white, waxy substance that he had created, they recognized that it contained long –CH2– chains and termed it polymethylene.

Polythylene balls, by Lluis tgn (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons
The first industrially practical polyethylene synthesis (diazomethane is a notoriously unstable substance that is generally avoided in industrial application) was discovered in 1933 by Eric Fawcett and Reginald Gibson, again by accident, at the Imperial Chemical Industries (ICI) works in Northwich, England.  Upon applying extremely high pressure (several hundred atmospheres) to a mixture of ethylene and benzaldehyde they again produced a white, waxy material. Because the reaction had been initiated by trace oxygen contamination in their apparatus, the experiment was, at first, difficult to reproduce. It was not until 1935 that another ICI chemist, Michael Perrin, developed this accident into a reproducible high-pressure synthesis for polyethylene that became the basis for industrial LDPE production beginning in 1939. Because polyethylene was found to have very low-loss properties at very high frequency radio waves, commercial distribution in Britain was suspended on the outbreak of World War II, secrecy imposed, and the new process was used to produce insulation for UHF and SHF coaxial cables of radar sets. During World War II, further research was done on the ICI process and in 1944 Bakelite Corporation at Sabine, Texas, and Du Pont at Charleston, West Virginia, began large-scale commercial production under license from ICI.

The breakthrough landmark in the commercial production of polyethylene began with the development of catalyst that promote the polymerization at mild temperatures and pressures. The first of these was a chromium trioxide–based catalyst discovered in 1951 by Robert Banks and J. Paul Hogan at Phillips Petroleum. In 1953 the German chemist Karl Ziegler developed a catalytic system based on titanium halides and organoaluminium compounds that worked at even milder conditions than the Phillips catalyst. The Phillips catalyst is less expensive and easier to work with, however, and both methods are heavily used industrially. By the end of the 1950s both the Phillips- and Ziegler-type catalysts were being used for HDPE production. In the 1970s, the Ziegler system was improved by the incorporation of magnesium chloride. Catalytic systems based on soluble catalysts, the metallocenes, were reported in 1976 by Walter Kaminsky and Hansjörg Sinn. The Ziegler- and metallocene-based catalysts families have proven to be very flexible at copolymerizing ethylene with other olefins and have become the basis for the wide range of polyethylene resins available today, including very low density polyethylene and linear low-density polyethylene. Such resins, in the form of UHMWPE fibers, have (as of 2005) begun to replace aramids in many high-strength applications.

One of the main problems of polyethylene is that without special treatment it's not readily biodegradable, and thus accumulates. In Japan, getting rid of plastics in an environmentally friendly way was the major problem discussed until the Fukushima disaster in 2011. It was listed as a $90 billion market for solutions. Since 2008, Japan has rapidly increased the recycling of plastics, but still has a large amount of plastic wrapping which goes to waste.

In May 2008, Daniel Burd, a 16-year-old Canadian, won the Canada-Wide Science Fair in Ottawa after discovering that Pseudomonas fluorescens, with the help of Sphingomonas, can degrade over 40% of the weight of plastic bags in less than three months.

The thermophilic bacterium Brevibacillus borstelensis (strain 707) was isolated from a soil sample and found to use low-density polyethylene as a sole carbon source when incubated together at 50°C. Biodegradation increased with time exposed to ultraviolet radiation.

In 2010, a Japanese researcher, Akinori Ito, released the prototype of a machine which creates oil from polyethylene using a small, self-contained vapor distillation process.

In 2014, a Chinese researcher discovered that Indian mealmoth larvae could metabolize polyethylene from observing that plastic bags at his home had small holes in them. Deducing that the hungry larvae must have digested the plastic somehow, he and his team analyzed their gut bacteria and found a few that could use plastic as their only carbon source. Not only could the bacteria from the guts of the Plodia interpunctella moth larvae metabolize polyethylene, they degraded it significantly, dropping its tensile strength by 50%, its mass by 10% and the molecular weights of its polymeric chains by 13%.

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Tuesday, 21 March 2017

Why water splashes: New theory reveals secrets

New research from the University of Warwick generates fresh insight into how a raindrop or spilt coffee splashes.

Dr James Sprittles from the Mathematics Institute has created a new theory to explain exactly what happens - in the tiny space between a drop of water and a surface - to cause a splash.

Water splash

When a drop of water falls, it is prevented from spreading smoothly across a surface by a microscopically thin layer of air that it can't push aside - so instead of wetting the surface, parts of the liquid fly off, and a splash is generated.

A layer of air 1 micron in size - fifty times smaller than the width of a human hair - can obstruct a 1mm drop of water which is one thousand times larger.

This is comparable to a 1cm layer of air stopping a tsunami wave spreading across a beach.

Dr Sprittles has established exactly what happens to this miniscule layer of air during the super-fast action by developing a new theory, capturing its microscopic dynamics - factoring in different physical conditions, such as liquid viscosity and air pressure, to predict whether splashes will occur or not.

The lower the air pressure, the easier the air can escape from the squashed layer - giving less resistance to the water drop - enabling the suppression of splashes. This is why drops are less likely to splash at the top of mountains, where the air pressure is reduced.

Understanding the conditions that cause splashing enables researchers to find out how to prevent it - leading to potential breakthroughs in various fields.

In 3D printing, liquid drops can form the building blocks of tailor-made products such as hearing aids; stopping splashing is key to making products of the desired quality.

Splashes are also a crucial part of forensic science - whether blood drops have splashed or not provides insight into where they came from, which can be vital information in a criminal investigation.

Dr Sprittles comments:

"You would never expect a seemingly simple everyday event to exhibit such complexity. The air layer's width is so small that it is similar to the distance air molecules travel between collisions, so that traditional models are inaccurate and a microscopic theory is required.

"Most promisingly, the new theory should have applications to a wide range of related phenomena, such as in climate science - to understand how water drops collide during the formation of clouds or to estimate the quantity of gas being dragged into our oceans by rainfall."

The research, 'Kinetic Effects in Dynamic Wetting', is published in Physical Review Letters.

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Tuesday, 14 March 2017

Looking for signs of the first stars

It may soon be possible to detect the universe's first stars by looking for the blue colour they emit on explosion.

The universe was dark and filled with hydrogen and helium for 100 million years following the Big Bang. Then, the first stars appeared, and metals were created by thermonuclear fusion reactions within stars.

Stars in the sky, ESA/Hubble [CC BY 4.0 (http://creativecommons.org/licenses/by/4.0)], via Wikimedia Commons
These metals were spread around the galaxies by exploding stars or 'supernovae'. Studying first-generation supernovae, which are more than 13 billion years old, provides a glimpse into what the universe might have looked like when the first stars, galaxies and supermassive black holes formed. But to-date, it has been difficult to distinguish a first-generation supernova from a later one.

New research, led by Alexey Tolstov from the Kavli Institute for the Physics and Mathematics of the Universe, has identified characteristic differences between these supernovae types after experimenting with supernovae models based on observations of extremely metal-poor stars.

Similar to all supernovae, the luminosity of metal-poor supernovae shows a characteristic rise to a peak brightness followed by a decline. The phenomenon starts when a star explodes with a bright flash, caused by a shock wave emerging from its surface after its core collapses. This is followed by a long 'plateau' phase of almost constant luminosity lasting several months, followed by a slow exponential decay.

The team calculated the light curves of metal-poor blue versus metal-rich red supergiant stars. The shock wave and plateau phases are shorter, bluer and fainter in metal-poor supernovae. The team concluded that the colour blue could be used as an indicator of a first-generation supernova. In the near future, new, large telescopes, such as the James Webb Space Telescope scheduled to be launched in 2018, will be able to detect the first explosions of stars and may be able to identify them using this method.

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Monday, 27 February 2017

The chemistry behind the 'Oscar'

A BIT of a mix up might have dinted the magical chemistry of the Oscars this year, but it didn’t damage the sheen on those golden statuettes! 

So, what exactly IS the chemistry behind the world’s most famous prize? Check out the graphic below to learn exactly WHAT goes into an Oscar statuette. 

Source: Compound Interest

So, who knew the statuette wasn’t made from REAL gold? And what is the history of Britannium? First produced in 1769 or 1770, Britannium metal was created by James Vickers after purchasing the formula from a dying friend. It was originally known as "Vickers White Metal" when made under contract by the Sheffield manufacturers Ebenezer Hancock and Richard Jessop. In 1776 James Vickers took over the manufacturing himself and remained as owner until his death in 1809, when the company passed to his son, John, and Son-in-Law, Elijah West. In 1836 the company was sold to John Vickers's nephew Ebenezer Stacey (the son of Hannah Vickers and John Stacey).

After the development of electroplating with silver in 1846, Britannia metal was widely used as the base metal for silver-plated household goods and cutlery. The abbreviation EPBM on such items denotes "electroplated Britannia metal". Britannia metal was generally used as a cheaper alternative to electroplated nickel silver (EPNS) which is more durable.

In his essay, A Nice Cup of Tea, writer George Orwell asserts that "britanniaware" teapots "produce inferior tea" (when compared to Chinaware).

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