Specialists of the St. Petersburg Research-and-Production Firm for Analytical Instrument-Making (LUMEX) demonstrated a device that had been long awaited by representatives of various areas of science and engineering. This is the so-called laser analyzer of particle sizes – a device that enables to promptly and accurately identify the sizes of microscopic particles and to distribute them by sizes. In other words, the analyzer helps to measure not only the average diameter of particles, but also to determine the quantity of particles of a certain size in the mixture.
The device operates as follows. The sample is poured into a transparent cuvette. This can be a suspended matter of smallest particles or emulsion – that does not matter. As solid particles (more than a micron in size) usually accumulate rather quickly at the bottom, the sample in the cuvette is being constantly agitated by a special stirrer, at that, the rate of stirring may be, if needed, very high – more than a thousand revolutions per minute. The stirrer is designed in such a way that no gas holes occur in the analyzable medium, which could impede the analysis. However, the stirrer may not be switched on – then there is an opportunity to track for example the speed of precipitation of particles of different sizes.
The cuvette is illuminated by a laser ray. Microparticles diffuse its light, with the angle of deflection being determined by the size of each particle. The multielement detector records this scattered radiation, thus allowing to measure intensity of beaming at different angles of deflection. Certainly, it is impossible to “pull out” the information on the particle sizes directly from this data, but the light diffusion theory has already been developed for this purpose – “three-story” equations comprehensible only for specialists, which are not needed to others for the most part. It is sufficient for the users to know that the particle size is promptly and accurately calculated in such a way by the computer, certainly with the help of the software also developed by the LUMEX specialists. The only assumption to be kept in mind is that the particle size is determined by the so-called “hydrodynamic radius” – a “fur coat” consisting of water molecules, ions or some molecules adjacent to the particle and moving together with the particle. So, the size determined for some particles via this method is bigger than it would be seen under the microscope – however, in this case it is needed to compare once the particle analysis results obtained through independent methods and to apply the necessary correction later on. This is always the case with determining the sizes by the laser light diffusion method, though.
It should be noted that till recently the device (called “Laska” by the designers) was intended for analysis of rather big particles, their diameter being no less than a micron. This niche at the analytical instrument-making market was not practically filled – as a rule, the task was solved either with the help of a microscope, which is rather labor-intensive and not always possible, or with the help of highly specialized devices, for example, blood cell counters. As for the nano-range sizes, i.e. the particles smaller than a micron, there existed only one device for them – the so-called nanosizer, the device being good and operating based on the same principle of laser light diffusion, but it is so expensive that there are only few of them available in Moscow .
“Our device already enables to perform analysis of particles of up to 500 nanometers in size, i.e., up to half a micron, says Vladimir Krivoshlyk, one of the developers, head of the group, dispersion department, LUMEX. However, we are working now on the analyzer modification, which would allow to measure sizes of smaller particles. We know already how to do this.”
Nadezda Markina | alfa
Researchers demonstrate three-dimensional quantum hall effect for the first time
19.08.2019 | Singapore University of Technology and Design
A laser for penetrating waves
19.08.2019 | Helmholtz-Zentrum Dresden-Rossendorf
Soft robots have a distinct advantage over their rigid forebears: they can adapt to complex environments, handle fragile objects and interact safely with humans. Made from silicone, rubber or other stretchable polymers, they are ideal for use in rehabilitation exoskeletons and robotic clothing. Soft bio-inspired robots could one day be deployed to explore remote or dangerous environments.
Most soft robots are actuated by rigid, noisy pumps that push fluids into the machines' moving parts. Because they are connected to these bulky pumps by tubes,...
Researchers at TU Graz are working together with European partners on new possibilities of measuring vehicle emissions.
Today, air pollution is one of the biggest challenges facing European cities. As part of the Horizon 2020 research project CARES (City Air Remote Emission...
Over the next three years, researchers from the Vrije Universiteit Brussel, University of Cambridge, École Supérieure de Physique et de Chimie Industrielles de la ville de Paris (ESPCI-Paris) and Empa will be working together with the Dutch Polymer manufacturer SupraPolix on the next generation of robots: (soft) robots that ‘feel pain’ and heal themselves. The partners can count on 3 million Euro in support from the European Commission.
Soon robots will not only be found in factories and laboratories, but will be assisting us in our immediate environment. They will help us in the household, to...
Scientists at the University of Leeds have created a new form of gold which is just two atoms thick - the thinnest unsupported gold ever created.
The researchers measured the thickness of the gold to be 0.47 nanometres - that is one million times thinner than a human finger nail. The material is regarded...
An international team of scientists involving the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg has unraveled the light-induced electron-localization dynamics in transition metals at the attosecond timescale. The team investigated for the first time the many-body electron dynamics in transition metals before thermalization sets in. Their work has now appeared in Nature Physics.
The researchers from ETH Zurich (Switzerland), the MPSD (Germany), the Center for Computational Sciences of University of Tsukuba (Japan) and the Center for...
16.08.2019 | Event News
14.08.2019 | Event News
12.08.2019 | Event News
19.08.2019 | Information Technology
19.08.2019 | Physics and Astronomy
19.08.2019 | Life Sciences