Whether it is new and groundbreaking research results, university topics or events – in our press releases you can find everything you need to know about the happenings at Goethe University. To subscribe, just send an email to ott@pvw.uni-frankfurt.de
New experimental technique with Goethe University’s reaction microscope allows “X-ray” of individual molecules
FRANKFURT. For
more than 100 years, we have been using X-rays to look inside matter, and progressing
to ever smaller structures – from crystals to nanoparticles. Now, within the
framework of a larger international collaboration on the X-ray laser European XFEL in Schenefeld near Hamburg, physicists at Goethe University have
achieved a qualitative leap forward: using a new experimental technique, they
have been able to “X-ray" molecules such as oxygen and view their motion in the
microcosm for the first time.
“The smaller the particle, the bigger the
hammer." This rule from particle physics, which looks inside the interior of
atomic nuclei using gigantic accelerators, also applies to this research. In
order to “X-ray" a two-atom molecule such as oxygen, an extremely powerful and
ultra-short X-ray pulse is required. This was provided by the European XFEL
which started operations in 2017 and is one of the the strongest X-ray source
in the world
In order to expose individual molecules, a
new X-ray technique is also needed: with the aid of the extremely powerful
laser pulse the molecule is quickly robbed of two firmly bound electrons. This
leads to the creation of two positively charged ions that fly apart from each
other abruptly due to the electrical repulsion. Simultaneously, the fact that
electrons also behave like waves is used to advantage. “You can think of it
like a sonar," explains project manager Professor Till Jahnke from the Institute
for Nuclear Physics. “The electron wave is scattered by the molecular structure
during the explosion, and we recorded the resulting diffraction pattern. We
were therefore able to essentially X-ray the molecule from within, and observe
it in several steps during its break-up."
For this technique, known as “electron
diffraction imaging", physicists at the Institute for Nuclear Physics spent
several years further developing the COLTRIMS technique, which was conceived
there (and is often referred to as a “reaction microscope"). Under the
supervision of Dr Markus Schöffler, a corresponding apparatus was modified for
the requirements of the European XFEL in advance, and designed and realised in
the course of a doctoral thesis by Gregor Kastirke. No simple task, as Till
Jahnke observes: “If I had to design a spaceship in order to safely fly to the
moon and back, I would definitely want Gregor in my team. I am very impressed
by what he accomplished here."
The result, which was published in the
current issue of the renowned Physical Review X, provides the first evidence that
this experimental method works. In the future, photochemical reactions of individual
molecules can be studied using these images with their high temporal resolution.
For example, it should be possible to observe the reaction of a medium-sized
molecule to UV rays in real time. In addition, these are the first measurement
results to be published since the start of operations of the Small Quantum
Systems (SQS) experiment station at the European XFEL at the end of 2018.
Publication:
Photoelectron diffraction imaging of a
molecular breakup using an X-ray free-electron laser. Gregor
Kastirke et al. Phys. Rev. X 10, 021052 https://doi.org/10.1103/PhysRevX.10.021052
Images
may be downloaded at this link: http://www.uni-frankfurt.de/89043339
Caption:
During the explosion of an oxygen molecule:
the X-ray laser XFEL knocks electrons out of the two atoms of the oxygen
molecule and initiates its breakup. During the fragmentation, the X-ray laser
releases another electron out of an inner shell from one of the two oxygen
atoms that are now charged (ions). The electron has particle and wave
characteristics, and the waves are scattered by the other oxygen ion. The
diffraction pattern are used to image the breakup of the oxygen molecules and
to take snapshots of the fragmentation process (electron diffraction imaging).
Credit: Till Jahnke, Goethe University Frankfurt
Further
information:
Professor Till Jahnke
Institute for Nuclear Physics
Goethe University Frankfurt
Tel.: +49 69 798-47025
E-Mail: jahnke@atom.uni-frankfurt.de.
For European XFEL und SQS:
Dr. Michael Meyer
Holzkoppel 4
22689 Schenefeld
Tel.: 040 8998 5614
E-Mail: michael.meyer@xfel.eu
Frankfurt neuroscientists: Both hemispheres of the brain make a unique contribution to speech control – new research casts doubt on current doctrine
FRANKFURT. Speaking requires both sides of the
brain. Each hemisphere takes over a part of the complex task of forming sounds,
modulating the voice and monitoring what has been said. However, the
distribution of tasks is different than has been thought up to now, as an
interdisciplinary team of neuroscientists and phoneticians at Goethe University
Frankfurt and the Leibniz-Centre General Linguistics Berlin has discovered: it
is not just the right hemisphere that analyses how we speak – the left
hemisphere also plays a role.
Until now, it has been assumed that the spoken word arises in left side of the brain and is analysed by the right side. According to accepted doctrine, this means that when we learn to speak English and for example practice the sound equivalent to “th", the left side of the brain controls the motor function of the articulators like the tongue, while the right side analyses whether the produced sound actually sounds as we intended.
The division of labour actually follows
different principles, as Dr Christian Kell from the Department of Neurology at
Goethe University explains: “While the left side of the brain controls temporal
aspects such as the transition between speech sounds, the right hemisphere is
responsible for the control of the sound spectrum. When you say 'mother', for
example, the left hemisphere primarily controls the dynamic transitions between
“th" and the vowels, while the right hemisphere primarily controls the sounds themselves."
His team, together with the phonetician Dr Susanne Fuchs, was able to
demonstrate this division of labour in temporal and spectral control of speech
for the first time in studies in which speakers were required to talk while
their brain activities were recorded using functional magnetic resonance
imaging.
A possible explanation for this division
of labour between the two sides of the brain is that the left hemisphere
generally analyses fast processes such as the transition between speech sounds
better than the right hemisphere. The right hemisphere could be better at
controlling the slower processes required for analysing the sound spectrum. A
previous study on hand motor function that was published in the scientific
publication “elife" demonstrates that this is in fact the case. Kell and his
team wanted to learn why the right hand was preferentially used for the control
of fast actions and the left hand preferred for slow actions. For example, when
cutting bread, the right hand is used to slice with the knife while the left hand
holds the bread.
In the experiment, scientists had
right-handed test persons tap with both hands to the rhythm of a metronome. In
one version they were supposed to tap with each beat, and in another only with
every fourth beat. As it turned out, the right hand was more precise during the
quick tapping sequence and the left hemisphere, which controls the right side
of the body, exhibited increased activity. Conversely, tapping with the left
hand corresponded better with the slower rhythm and resulted in the right
hemisphere exhibiting increased activity.
Taken together, the two studies create a
convincing picture of how complex behaviour – hand motor functions and speech –
are controlled by both cerebral hemispheres. The left side of the brain has a
preference for the control of fast processes while the right side tends to
control the slower processes in parallel.
Publications:
Floegel M, Fuchs S, Kell CA (2020)
Differential contributions of the two cerebral hemispheres to temporal and
spectral speech feedback control. Nature Communications, 11:2839. https://doi.org/10.1038/s41467-020-16743-2
Pflug A, Gompf F, Muthuraman M, Groppa S,
Kell CA (2019) Differential contributions of the two human cerebral hemispheres
to action timing. eLife, 8:48404 https://doi.org/10.7554/eLife.48404
Further information: Dr. Christian Kell, Cognitive Neuroscience Group, Clinic for Neurology, Goethe University Frankfurt/ University Hospital Frankfurt, Tel.: +49 69 6301-6395, E-mail: c.kell@em.uni-frankfurt.de
Unique long-term videos show the bee nursery in the hive
FRANKFURT. A newly developed video technique has
allowed scientists at Goethe University Frankfurt at the Bee Research Institute
of the Polytechnical Society to record the complete development of a honey bee
in its hive for the first time. It also led to the discovery that certain
pesticides – neonicotinoids – changed the behaviour of the nurse bees:
researchers determined that they fed the larvae less often. Larval development
took up to 10 hours longer. A longer development period in the hive can foster
infestation by parasites such as the Varroa
mite (Scientific Reports, DOI 10.1038/s41598-020-65425-y).
Honey bees have very complex breeding
behaviour: a cleaning bee cleans an empty comb (brood cell) of the remains of
the previous brood before the queen bee lays an egg inside it. Once the bee
larva has hatched, a nurse bee feeds it for six days. Then the nurse bees caps
the brood cell with wax. The larva spins a cocoon and goes through metamorphosis,
changing the shape of its body and developing a head, wings and legs. Three
weeks after the egg was laid, the fully-grown bee hatches from the cocoon and
leaves the brood cell.
Using a new video technique, scientists at
Goethe University Frankfurt have now succeeded for the first time in recording
the complete development of a honey bee in a bee colony at the Bee Research
Institute of the Polytechnical Society. The researchers built a bee hive with a
glass pane and were thus able to film a total of four bee colonies
simultaneously over several weeks with a special camera set-up. They used deep red
light so that the bees were not disturbed, and recorded all the movements of
the bees in the brood cells.
The researchers were particularly
interested in the nursing behaviour of the nurse bees, to whose food (a sugar
syrup) they added small amounts of pesticides known as neonicotinoids. Neonicotinoids
are highly effective insecticides that are frequently used in agriculture. In
natural environments, neonicotinoids arrive in bee colonies through nectar and
pollen collected by the bees. It is already known that these substances disturb
the navigational abilities and learning behaviour of bees. In a measure
criticised by the agricultural industry, the European Union has prohibited the
use of some neonicotinoids in crop cultivation.
Using machine learning algorithms
developed by the scientists together with colleagues at the Centre for
Cognition and Computation at Goethe University, they were able to evaluate and quantify
the nursing behaviour of the nurse bees semi-automatically. The result: even
small doses of the neonicotinoids Thiacloprid or Clothianidin led to the nurse
bees feeding the larva during the 6-day larval development less frequently, and
consequently for a shorter daily period. Some of the bees nursed in this manner
required up to10 hours longer until the cell was capped with wax.
“Neonicotinoids affect the bees' nervous
systems by blocking the receptors for the neurotransmitter acetylcholine," explains
Dr Paul Siefert, who carried out the experiments in Professor Bernd Grünewald's
work group at the Bee Research Institute Oberursel. Siefert: “For the first
time, we were able to demonstrate that neonicotinoids also change the social
behaviour of bees. This could point to the disruptions in nursing behaviour due
to neonicotinoids described by other scientists." Furthermore, parasites such
as the feared Varroa mite (Varroa destructor) profit from an
extended development period, since the mites lay their eggs in the brood cells
shortly before they are capped: if they remain closed for a longer period, the
young mites can develop and multiply without interruption.
However, according to Siefert, it still
remains to be clarified whether the delay in the larval development is caused
by the behavioural disturbance of the nurse bee, or whether the larvae develop
more slowly because of the altered jelly. The nurse bees produce the jelly and
feed it to the larvae. “From other studies in our work group, we know that the
concentration of acetylcholine in the jelly is reduced by neonicotinoids," says
Siefert. “On the other hand, we have observed that with higher dosages, the
early embryonal development in the egg is also extended – during a period in
which feeding does not yet occur." Additional studies are needed to determine
which factors are working together in these instances.
In any case, the new video technique and
the evaluation algorithms offer great potential for future research projects.
In addition to feeding, behaviours for heating and construction were also able
to be reliably identified. Siefert: “Our innovative technology makes it
possible to gain fundamental scientific insights into social interactions in
bee colonies, the biology of parasites, and the safety of pesticides."
Publication:
Paul Siefert, Rudra
Hota, Visvanathan Ramesh, Bernd Grünewald. Chronic
within-hive video recordings detect altered nursing behaviour and retarded
larval development of neonicotinoid treated honey bees. Sci. Rep. 10,
8727 (2020).
Video:
Development of a bee larva https://www.nature.com/articles/s41598-020-65425-y (Supplementary
Material)
Images may be downloaded
here: http://www.uni-frankfurt.de/88682581
Captions:
Figure 1: Diagram/monitoring of brood cells – side view of the construction and camera view of the brood area. The brood area of the bees was filmed with a camera (green) through a dome lighting (grey). The specially designed hive (brown) was only 2.4 cm wide, so that the bees would raise young as quickly as possible (right). Credit: Paul Siefert/Bee Research Institute Oberursel/Goethe University Frankfurt
Figure.
2 Excerpts from the video of the development of
a worker bee. Above left: The queen lays an egg (arrow) in the cell. The growing
larva (arrow) is fed with jelly. Below left: the metamorphosis takes about one
hour and includes the rupture of the larval skin (arrow); the pupa is beneath
it. Finally, the adult bee hatches out of the cell. Credit: Paul Siefert/Bee
Research Institute Oberursel/Goethe University Frankfurt
Further
information:
Dr Paul Siefert
Bee Research Institute Oberursel
Subsidiary of the Polytechnical Society
Frankfurt am Main,
Faculty of Biosciences
Goethe University Frankfurt am Main
Tel.:
+49 6171 21278
siefert@bio.uni-frankfurt.de
www.institut-fuer-bienenkunde.de
Two research aircraft investigate reduced concentrations of pollutants in the air
FRANKFURT. The COVID-19 pandemic is not only
affecting almost every aspect of our daily lives, but also the environment. A
German team including atmosphere researchers around Prof. Joachim Curtius
(Goethe University Frankfurt) now wants to find out how strong these effects
are on the atmosphere. Over the next two weeks, as part of the BLUESKY research
programme, the scientists led by the Max Planck Institute for Chemistry and the
German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) will measure
concentrations of trace gases and pollutants in the air over European urban
areas and in the flight corridor to North America. The aim of these research
missions is to investigate how reduced emissions from industry and transport
are changing atmospheric chemistry and physics.
A German research team now wants to make
rapid use of this unusual situation for the BLUESKY project. Scientists from
DLR, the Max Planck Institute for Chemistry, Goethe University Frankfurt, and
the research centres at Jülich and Karlsruhe intend to use two DLR research
aircraft to conduct a globally unique investigation into the resulting changes
in Earth's atmosphere for the first time. DLR’s HALO and Falcon research
aircraft have been equipped with highly specialised instrumentation and will
fly over Germany, Italy, France, Great Britain and Ireland in the course of the
next two weeks. They will also fly over the North Atlantic, along the flight
corridor to North America.
“DLR is deploying part of its unique
research aircraft fleet to exploit an almost unique opportunity. During these
missions, the atmosphere will be analysed in a state that could be achieved in
the future with sustainable management of human activities. We will observe how
the environment changes with the ramp-up of industrial activities. This will
give us an entirely new perspective on the anthropogenic influence on Earth’s
atmosphere,” explains Rolf Henke, DLR Executive Board Member responsible for
aeronautics research. “Together with our partners, we are making a significant
contribution to redefining humankind’s activities once the pandemic is under
control.”
Coordinated research flights with two measurement
aircraft
Jos Lelieveld, Director of the Max Planck Institute
for Chemistry, wants to use the BLUESKY missions to clarify whether there is a
correlation between the clear blue sky during the lockdown and the prevalence
of aerosol particles in the atmosphere. “The unique blue sky of recent weeks
cannot be explained by meteorological conditions and the decrease in emissions
near the ground. Aircraft may have a greater impact on the formation of aerosol
particles than previously thought,” says the atmospheric researcher, who is the
Scientific Director of the HALO flights. Aerosols, microscopic particles in the
air that also influence cloud formation, are finely distributed. They scatter
and absorb solar radiation and thus also have an impact on the climate, because
they influence the radiation balance of the atmosphere. Aerosols are created,
amongst other ways, during the combustion of fossil fuels.
Christiane Voigt, Head of the Cloud
Physics Department at the DLR Institute of Atmospheric Physics and Scientific
Director of the Falcon flights, also sees a unique opportunity with BLUESKY.
“The current state of the atmosphere represents a kind of ‘zero point’ for
science. We will be able to measure a reference atmosphere that is only
slightly polluted with emissions from industry and transport, including
aviation. This gives us a unique opportunity to better understand the effects
of the anthropogenic emissions prior to the shutdown.” The atmospheric
physicist emphasises that, only through the cooperation of all the partners,
was it possible to plan and implement the scientifically and logistically
highly complex missions at very short notice.
Emissions from air transport, industry and road
traffic in urban areas
Voigt and her colleagues believe that the
BLUESKY data will provide a clearer picture of anthropogenic influences on the
composition of Earth’s atmosphere. With the equipment on board both research
aircraft, the BLUESKY scientists are investigating aircraft emissions such as
nitrogen oxides, sulphur dioxide and aerosols at cruising altitude, in addition
to the few remaining contrails. Among other things, they want to find out how
much these emissions have decreased over Europe and the North Atlantic flight
corridor. Approximately 30,000 aircraft fly over Europe every day, with
correspondingly significant emissions. The reduced air traffic will allow more
flexible flight routes for the measurements.
In addition, the researchers want to
investigate the reduced emission plumes from urban areas and clarify how
emissions are distributed at the atmospheric boundary layer. For example, the
BLUESKY scientists plan to fly over the Ruhr area and the regions around
Frankfurt am Main, Berlin and Munich. Flights over the Po Valley in Italy and
around Paris and London are also planned. “Close to cities and conurbations, we
will approach the atmospheric boundary layer at an altitude of one to two
kilometres, since emissions from road traffic and industry are concentrated
there,” explains Jos Lelieveld. “We are interested in how much the
concentrations of sulphur dioxide, nitrogen oxides, hydrocarbons and their
chemical reaction products, as well as ozone and aerosols, have changed.” He is
also very proud that the team is the first in the world to implement a
measurement campaign of this type.
Rapid preparations for flights – with special
infection control rules
In recent weeks, two DLR research aircraft
–measuring the Falcon 20E and the Gulfstream G550 HALO – have been successfully
converted at short notice for the BLUESKY missions. The conversions were
carried out at the DLR Flight Operations Facility in Oberpfaffenhofen.
“Numerous instruments have had to be installed and adapted, and the aircraft
modified for the upcoming missions,” says Burkard Wigger, Head of DLR Flight
Experiments. “Close cooperation between the various scientific organisations
has made it possible for these two research aircraft to operate simultaneously
under the challenging conditions resulting from the Coronavirus pandemic.”
The preparation, execution and follow-up
of the flights is being carried out in accordance with the current rules
regarding personal interactions and infection control. Joint flights by Falcon
and HALO are planned until the first half of June. The evaluation of the data
and the analysis of the results will then take several months. The analysis
will include comparative data from previous HALO research flight campaigns on
air traffic emissions and emissions from major cities and conurbations.
About HALO: The High Altitude and Long Range (HALO) research aircraft is a joint initiative of German environmental and climate research institutions. HALO is supported by grants from the Federal Ministry of Education and Research (BMBF), the German Research Foundation (DFG), the Helmholtz Association of German Research Centres, the Max Planck Society (MPG), the Leibniz Association, the Free State of Bavaria, the Karlsruhe Institute of Technology (KIT), the Forschungszentrum Jülich and the German Aerospace Center (DLR).
More information: Prof. Joachim Curtius, Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Phone: +49 (0)69 798-40258, curtius@iau.uni-frankfurt.de
International research project observes ultrafast particle growth through ammonia and nitric acid
FRANKFURT. When winter smog takes over Asian
mega-cities, more particulate matter is measured in the streets than expected.
An international team, including researchers from Goethe University Frankfurt,
as well as the universities in Vienna and Innsbruck, has now discovered that
nitric acid and ammonia in particular contribute to the formation of additional
particulate matter. Nitric acid and ammonia arise in city centres predominantly
from car exhaust. Experiments show that the high local concentration of the vapours
in narrow and enclosed city streets accelerates the growth of tiny nanoparticles
into stabile aerosol particles (Nature, DOI 10.1038/s41586-020-2270-4).
In crowded urban centres, high concentrations of particulate matter cause considerable health effects. Especially in winter months, the situation in many Asian mega-cities is dramatic when smog significantly reduces visibility and breathing becomes difficult.
Particulates, with a diameter of less than
2.5 micrometres, mostly form directly through combustion processes, for example
in cars or heaters. These are called primary particulates. Particulates also
form in the air as secondary particulates, when gases from organic substances,
sulphuric acid, nitric acid or ammonia, condense on tiny nanoparticles. These grow
into particles that make up a part of particulate matter.
Until now, how secondary particulates
could be newly formed in the narrow streets of mega-cities was a puzzle.
According to calculations, the tiny nanoparticles should accumulate on the abundantly
available larger particles rather than forming new particulates.
Scientists in the international research
project CLOUD have now recreated the conditions that prevail in the streets of
mega-cities in a climate chamber at the particle accelerator CERN in Geneva,
and reconstructed the formation of secondary particulates: in the narrow and
enclosed streets of a city, a local increase of pollutants occurs. The cause of
the irregular distribution of the pollutants is due in part to the high pollutant
emissions at the street level. Furthermore, it takes a while before the
street air mixes with the surrounding air. This leads to the two pollutants
ammonia and nitric acid being temporarily concentrated in the street air. As the
CLOUD experiments demonstrate, this high concentration creates conditions in
which the two pollutants can condense onto nanoparticles: ammonium nitrate
forms on condensation cores the size of only a few nanometres, causing these
particles to grow rapidly.
“We have observed that these nanoparticles
grow rapidly within just a few minutes. Some of them grow one hundred times
more quickly than we had previously ever seen with other pollutants, such as
sulphuric acid," explains climate researcher Professor Joachim Curtius from
Goethe University Frankfurt. “In crowded urban centres, the process we observed
therefore makes an important contribution to the formation of particulate
matter in winter smog – because this process only takes place at temperatures
below about 5 degrees Celsius." The aerosol physicist Paul Winkler from the
University of Vienna adds: “When conditions are warmer, the particles are too
volatile to contribute to growth."
The formation of aerosol particles from
ammonia and nitric acid probably takes place not only in cities and crowded
areas, but on occasion also in higher atmospheric altitudes. Ammonia, which is primarily
emitted from animal husbandry and other agriculture, arrives in the upper
troposphere from air parcels rising from close to the ground by deep convection,
and lightning creates nitric acid out of nitrogen in the air. “At the
prevailing low temperatures there, new ammonium nitrate particles are formed
which as condensation seeds play a role in cloud formation," explains ion physicist
Armin Hansel from the University of Innsbruck, pointing out the relevance of
the research findings for climate.
The experiment CLOUD (Cosmics Leaving
OUtdoor Droplets) at CERN studies how new aerosol particles are formed in the atmosphere
out of precursor gases and continue to grow into condensation seeds. CLOUD
thereby provides fundamental understanding on the formation of clouds and
particulate matter. CLOUD is carried out by an international consortium
consisting of 21 institutions. The CLOUD measuring chamber was developed with
CERN know-how and achieves very precisely defined measuring conditions. CLOUD experiments
use a variety of different measuring instruments to characterise the physical
and chemical conditions of the atmosphere consisting of particles and gases. In
the CLOUD project, the team led by Joachim Curtius from the Institute for
Atmosphere and Environment at Goethe University Frankfurt develops and operates
two mass spectrometers to detect trace gases such as ammonia and sulphuric acid
even at the smallest concentrations as part of projects funded by the BMBF and
the EU. At the Faculty of Physics at the University of Vienna, the team led by
Paul Winkler is developing a new particle measuring device as part of an ERC
project. The device will enable the quantitative investigation of aerosol dynamics
specifically in the relevant size range of 1 to 10 nanometres. Armin Hansel
from the Institute for Ion Physics and Applied Physics at the University of Innsbruck
developed a new measuring procedure (PTR3-TOF-MS) to enable an even more
sensitive analysis of trace gases in the CLOUD experiment with his research
team as part of an FFG project.
Publication:
Wang, M., Kong, W., et al. Rapid growth of
new atmospheric particles by nitric acid and ammonia condensation. Nature, DOI
10.1038/s41586-020-2270-4.
Further information: Prof. Dr. Joachim Curtius, Institute for Atmosphere and Environment, Goethe University Frankfurt am Main, Tel: +49 69 798-40258, email: curtius@iau.uni-frankfurt.de
Prof. Dr. Armin Hansel, Institute for Ion Physics and Applied Physics, University of Innsbruck, Tel.: +43 512 507 52640, email: armin.hansel@uibk.ac.at
Prof. Dr. Paul Winkler, Aerosol physics and Environmental Physics, Faculty for Physics, University of Vienna, Tel: +43-1-4277-734 03, email: paul.winkler@univie.ac.at