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Hydrogen bonds: why life needs water

Water is everywhere on our planet. In the air, in our bodies, in our food and in our breath. Without it life as we know it would not be possible. Water is vital for the survival of all living things, yet as a molecule it has some pretty odd behaviour. Water molecules stick to each other, forming the ‘skin’ on ponds and droplets. The solid form floats on the liquid form. At room temperature water is a liquid, when most of the molecules closely related to it are gasses.

Why does water have so many strange and wonderful properties? What is it about this rather tiny and innocuous molecule that makes it so important for life?

To answer that you have to look at the actual structure of the molecule, exploring a world far, far smaller than microbiology usually goes. The properties of water are determined by the forces that hold it together.

A stylised diagram of a water molecule. All diagrams in this post (c) me.

A stylised diagram of a water molecule. All diagrams in this post (c) me.

The above diagram shows a water molecule, H2O. Two atoms of hydrogen attached to one molecule of oxgyen sharing electrons between them to form bonds. But the red lines that I’ve used to show the bonds hide a far more complicated story. This may be a bond, but it is not a very equal one because while oxgyen is a nice reasonably sized molecule, with eight electrons surrounding each atom, hydrogen is tiny. It only has one electron! Read more

What percent of Earth is water?

The Earth is often compared to a majestic blue marble, especially by those privileged few who have gazed upon it from orbit. This is due to the prevalence of water on the planet’s surface. While water itself is not blue, water gives off blue light upon reflection.

whatpercentoFor those of us confined to living on the surface, the fact that our world is mostly covered in water is a well known fact. But how much of our planet is made up of water, exactly? Like most facts pertaining to our world, the answer is a little more complicated than you might think, and takes into account a number of different qualifications. Read more

When waste water freezes, it is purified

Freezing technology can be utilised in waste water treatment. When waste water freezes, it is purified through the formation of a cleaner layer of ice. The clean layer of ice can be removed from the rest of the waste water, and the remaining waste water is more concentrated.

The new energy-efficient method of purification is based on the natural freezing process of water: energy is required only for breaking the ice and transporting it from the waste water pool.

whenwastewatIn practice, this method could be used by leaving waste water from mines to freeze in special pools under the open sky, after which the cleaner part could be removed by breaking the ice. After that the ice would be taken away using a machine designed for that purpose to another pool where the treated waste water would be recycled, or undergo further treatment using membrane filtration, for example, for the needs of various processes. Recycling water from the industrial process would reduce the amount of fresh water that is used. Read more

Laser-generated surface structures create extremely water-repellent metals

Scientists at the University of Rochester have used lasers to transform metals into extremely water repellent, or super-hydrophobic, materials without the need for temporary coatings.

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University of Rochester’s Institute of Optics Professor Chunlei Guo has developed a technique that uses lasers to render materials hydrophobic, illustrated in this image of a water droplet bouncing off a treated sample. Credit: J. Adam Fenster/University of Rochester

Super-hydrophobic materials are desirable for a number of applications such as rust prevention, anti-icing, or even in sanitation uses. However, as Rochester’s Chunlei Guo explains, most current hydrophobic materials rely on chemical coatings.

In a paper published today in the Journal of Applied Physics, Guo and his colleague at the University’s Institute of Optics, Anatoliy Vorobyev, describe a powerful and precise laser-patterning technique that creates an intricate pattern of micro- and nanoscale structures to give the metals their new properties. This work builds on earlier research by the team in which they used a similar laser-patterning technique that turned metals black. Guo states that using this technique they can create multifunctional surfaces that are not only super-hydrophobic but also highly-absorbent optically. Read more

Nanoparticles for clean drinking water

One way of removing harmful nitrate from drinking water is to catalyse its conversion to nitrogen. This process suffers from the drawback that it often produces ammonia. By using palladium nanoparticles as a catalyst, and by carefully controlling their size, this drawback can be partially eliminated. It was research conducted by Yingnan Zhao of the University of Twente’s MESA+ Institute for Nanotechnology that led to this discovery.

nanoparticleDue to the excessive use of fertilizers, our groundwater is contaminated with nitrates, which pose a problem if they enter the mains water supply. Levels have fallen significantly in recent years, as a result of various European directives. In addition, the Integrated Approach to Nitrogen programme was launched in various Dutch nature reserves at the start of January. Tackling the problem at source is one thing, but it will still be necessary to treat the mains water supply. Read more