Bean counting: Fair trade, Delft Reactor Institute shoots neutrons at coffee beans

Apart from oil, coffee is the worlds most important export product. The large-scale intensive coffee plantations are also one of the worlds biggest users of pesticides. But cautious signs are emerging of return to the traditional, practically pesticide-free, organic growing methods, a trend that started in 1972 with the foundation of the International Federation of Organic Agricultural Movements (ifoam), regarded as the umbrella organisation of organic agriculture. The story goes that consumers in the western world want their coffee to be of impeccable origin. But how do you tell the difference between pesticide-drenched intensively grown coffee and shade-grown organic coffee? Ask the scientists at the Interfaculty Reactor Institute of Delft University of Technology. They can tell by pelting the coffee with neutrons

Focused spraying: Fighting plant disease without making a mess

Each year in the Netherlands alone, some 8,000 tons of pesticides are sprayed onto crops. Some of this is used inside greenhouses, on plants, flowers, and fruit. The problem with spraying is that a large part of the pesticide, something like 80%, ends up anywhere but on the plant. This is not only a waste of material, it also puts the environment at risk, with airborne or waterborne pesticides possibly contaminating our drinking water resources. However, there is hope of improvement in the form of an electrospraying method devised by Dr Kees Geerse, who recently gained his doctorate. His plan may well result in a better method of fighting plant disease

Follow the track: The effects of silicon dioxide on GTA welding

Silicon dioxide, in other words sand, turns out to be a highly useful helper for arc welding processes. It can be used as a tracer for a welding robot to follow the weld line and it can also make welding go faster and "deeper". At the Materials Science department of the Delft University of Technology, chemical engineer Wilma Middel looked into the matter and created the basis for a new type of seam tracking sensor

X-ray view of steel: A 'living' material that does not easily reveal its secrets

Steel is a difficult material, or rather, it tends to guard its secrets jealously. At the Interfaculty Reactor Institute (iri) and the subfaculty of Materials Science and Engineering at TU Delft, Dr. ir. Erik Offerman is doing his utmost to get to the bottom of this enigma. His endeavours even required the support of the synchrotron of the European Synchrotron Radiation Facility (esrf) at Grenoble in France. Using an X-ray beam from this electron accelerator which is about a billion times as strong as the types used in medical X-ray equipment he managed to become the first person to actually observe the changes in steel as they took place, an achievement that got him into Science magazine. In the mean time, Offerman has developed a model that will enable him to explain the observations made at the synchrotron in Grenoble.Delft University of Technolog

A numerical look at the erratic behaviour of drops revealed

When you mix two diff erent liquids, two things can happen. They either mix down to the molecular level (like water and alcohol),or they dont (like oil and water), and instead form minute droplets that coexist. If such a mixture is left alone, the lighter of the two liquids will eventually fl oat to the top, and the heavier liquid will sink to the bottom. During the fi nal stages of the separation process, at the interface of the two layers there is a short but intense bustle of merging droplets, as seen here in a mixture of naptha and water

Nanoparticles made-to-measure: Aerosols prove to be indispensable for nanotechnology

Is it possible to make platinum particles with a diameter of less than eight nanometres? That was the question Jan Marijnissen at the aerosol lab of Delft ChemTech was asked. Together with graduate student Jan van Erven, the famous aerosol expert Sheldon Friedlander of the University of California (UCLA), and the University of Karlsruhe, Germany, Marijnissen set out to experiment. He managed to do achieve this by using his favourite electrospray method. While they were at it, the research teams used an electron microscope to see how a soot filter uses the platinum nanogranules to get rid of its soot