THE HISTORY OF OUR GAeF LOGO
by H. Horvath, March 29, 2019
Around the world there are at least 16 associations promoting Aerosol Science and many of them have logos, which relate to one specific aspect of aerosols. This can be a size distribution (FAAR), the scattering of two laser beams by a particle (HAeS), particles of various sizes and colors (ACEyTA, ASFERA, JAAST, KAPAR, NOSA), an electron micrograph of a complex particle (IAS), a particle in the flow of a virtual impactor (IAAR), or trajectories of particles in an impactor (AAAR, TAAR). Obviously the graphical representations of trajectories are oversimplified in order to produce an eye catching logo. It seems, that the logos deal with subjects of aerosol research, which were “hot” when the logo was created, which usually was around the founding year of the corresponding aerosol association.
The old GAeF logo has a long history: We have to go back to the third quarter of the 20th century. In Germany underground coal mining was the backbone for the reconstruction after the disastrous war, and many of the miners suffered from silicosis, a serious lung disease, caused by inhaling quartz particles. This could have easily been prevented, when a mask with a particle filter were worn, but the filter needs a pressure drop, which makes breathing strenuous, so frequently the mask was not used, especially since the damage to the lung was not noted immediately. At the Institute of Silicosis Research in Bochum, Germany, scientists therefore tried to reduce the pressure drop in the filter.
This could e.g. be achieved by charging the particles, and depositing them on charged fibers in an electric field. Since a much smaller number of fibers, i.e. no dense packing, is needed, the pressure drop is would be minimal. (This is similar to the much smaller pressure drop in electrostatic precipitators compared to baghouse filters in power plants). The power consumption for producing the electric field and charging the particles would be minimal, compared to power needed to overcome the pressure drop in a conventional filter by means of a pump. So the miner only would need to carry a small battery when using the envisaged filter.
GGünter Zebel, on leave from the Institute of Silicosis Research, calculated trajectories of charged particles around a fiber, using the excellent computational facilities during his stay at NCAR, Boulder, Colorado, USA. But this theoretical finding needed to be proven experimentally. Fortunately Dieter Hochrainer, a young PhD. from the University of Vienna with outstanding experimental skills, stayed at NCAR at the same time. He built an apparatus which permitted investigations on the movement of charged particles around a charged fiber and he was able to record the position of the particles by a 16 mm movie camera. Analyzing each frame by hand, the particles’ trajectories could be found. The theoretical calculations by Zebel thus were proven (Hochrainer et al., 1969). The trajectories of the particles were impressive and from 1985 to 1999 they decorated the cover page of the Journal of Aerosol Science (see Figure 1). The image represents the motion of positively charged particles around a negatively charged metal fiber. The flow is from the top to the bottom, the direction of the electric field is from the bottom to the top.
Figure 1. Cover page of Journal of Aerosol science with the trajectories for charged particles around a charged fiber.
These particle trajectories also were the logo of GAeF (which by then was in association with the Journal of Aerosol Science). The second International Aerosol Conference, taking place in Berlin in 1986, was organized jointly by GAeF and AAAR, and obviously the cover page of the abstract book has the logos of the two associations, i.e. the simplified motion of particles in an impactor for AAAR and the trajectories of particles around a fiber for GAeF (see Figure 2).
Since the founding of the EAA, the Journal of Aerosol Science is in association with the EAA. The title page of the Journal of Aerosol Science was changed in 2000 and the cover page now has six images of aerosol particles: a bio particle, TEM images of spherical particles, of an agglomerate, of magnetic particles, the diffraction of radiation by a particle and a mineral particle. Still the trajectories of charged particles around a fiber can now be found on the inside cover page. But the image is upside down, i.e. the particles flow from the bottom to the top. Whether this happened by accident or is on purpose, is unknown (see Figure 3).
Figure 2 (left): Cover page of the abstract book of the Second International Aerosol Conference, showing the logos of AAAR (left) and GAeF (right).
Figure 3 (right): Inside cover page of the Journal of Aerosol Science.
D. Hochrainer, G. M Hidy, G Zebel (1969). Creeping motion of charged particles around a cylinder in an electrical field. Journal of Colloid and Interface Science, 30(4), August 1969, Pages 553-567