The network flow problem involves finding the optimum route through a flow network; a directed graph where each arc has a capacity and each arc receives a flow. Typical examples include: evacuation plans and delivery services. The problem involves students analysing the plan of a school canteen and deciding whether...

This Catalyst article looks at the use of fluoride in water supplies. The UK health secretary has announced that more water companies would be encouraged to add fluoride to the water supplies. The article looks at why fluoride is added, what the advantages and risks are and why should it be put into water.

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This poster describes four people in four different companies who all work together to produce an innovative flood defence system. To manufacture the produce requires the collaboration of designers, engineers, materials...

This Catalyst article explores how high-speed photography can reveal how mosquitoes can keep dry while flying in the rain.

To find out how mosquitoes survive impacts with raindrops, a group of engineers from Georgia Institute of Technology (USA) developed a system which allowed them to photograph collisions...

This Catalyst article looks at what it means to say that an astronaut is 'weightless'. The article looks at how astronauts are trained in aircraft and how underwater work can also help prepare them for space travel.

This article is from Catalyst: Secondary Science Review 2008, Volume 19, Issue 1.

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This publication, from the Technology Enhancement Programme (TEP), looks at the topic of flywheels and how they can be used to store or smooth energy flows. The book initially provides information for students on the following topics:

• The energy-storage system
• Cyclicity of supply
• ...

What do dental fillings, catalytic converters, mobile phones and jewellery have in common? They all make use of the metal palladium. This Catalyst article explains the properties of this metal, and how it can be used for a vast array of objects.

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A Catalyst article about careers in the food industry. The food and drink industries are part of a chain linking farming and growing through to food processing, manufacture and finally to the sale of food in supermarkets and restaurants. This article describes some of the many career areas in food technology...

This Catalyst article describes how food waste can be treated by anaerobic digestion to produce methane and fertiliser.

This article is from Catalyst: Secondary Science Review 2011,...

A Catalyst article about food chains and food webs. The article studies evidence for global climate change and considers possible causes. It also explores how climate change might affect the food web, with evidence from a long-term study which started in 1931.

This article is from Catalyst: GCSE Science...

A Catalyst article about food additives. Some additives are natural and some are manufactured by the chemical industry. Some, like vitamin C, can come from either natural or artificial sources. As with every other component of food all additives are chemicals. Even organic food can contain a certain number of...