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Leiden Science in 2020

Contents We Are Science


Corona 34

Contributing writers Bryce Benda, Martine van Dorsten, Charlotte Ellerman, Hilde Pracht-Altorf, Jeroen Scharroo, Marjolein van Schoonhoven

Research 44

English language editing

Education 54

Design Creja ontwerpen

Science & Society


Facts & Figures


Marilyn Hedges

Photo: Monique Shaw

Leiden Science in a year with corona At the beginning of 2020 we could never have imagined the radical changes we ’d have to come to terms with in the course of the year. Close interactions these days are limited. At work we have to be safe and take strict precautions into account: keep your distance, sneeze in your elbow, wash your hands thoroughly, to name just a few. Despite all the challenges we faced, we managed to move forward together. We worked together and kept education and research going. In this year’s new-style publication, we invite you to learn more about our exceptional year and read the stories of some of our dedicated staff members. 3

We Are Science Staff Our community


250+ 51-250 11-50 1-10 0

56 Nationalities




2384 ** End End 2020 2020 excluding excluding guests guests and and PhD PhD candidates candidates

PhD candidates (%)

Nationalities (%) DUTCH DUTCH
















Students Students


250+ 250+ 51-250 51-250 11-50 11-50 1-10 1-10 00


Nationalities Nationalities End End2020, 2020, among amongallall students studentsatat our ourFaculty. Faculty.


5712 Total Total

* *End End2020 2020excluding excludingguests guests

BSc BSc&&MSc MScstudents students(%) (%)


85% 85% 15% 15%


58% 58%


42% 42%



Working safely during the corona crisis

‘It’s good to see that this crisis has its positive sides after all’ 6

Photo: Pim Rusch

Over the past year, Irma Bakker from the Environment, Health & Safety department has walked many extra miles. In late May, the laboratories were reopened to a limited extent. Before that, all 450 labs at the Faculty had to be checked and prepared for working safely, taking into account the 1.5 metres distance. No small task for a team of five.

Challenging times

From live to video

‘In April we heard that we could probably reopen the labs

The presentations with safety instructions posed another

in May, ’ says Bakker. ‘Obviously, all the researchers were

challenge. Normally, the team provides live lectures for

very keen to get back to their experiments.’ It was quite a

new staff and students. But this year, they had to find

challenge for the team to have everything ready in time.

another way of sharing these vital instructions. ‘Together

‘We even worked on King’s Day.’

with the student affairs department, we came up with

Closer together

André Kamp and Marc Fluttert took care of the

Fortunately, the team was not alone. ‘Everyone from

recordings. One thing we learned is that making videos is

the Facilities department worked together, ’ Bakker

a profession in its own right!’

emphasises. She was also delighted with the help the team received from the laboratory users. ‘They had already done some preliminary work, so we did the rest together, which

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the idea of making safety instruction videos. Colleagues

was really good for our working relationship. It’s good to see that this crisis has its positive sides after all!’

1.5M 7

Corona meant registering every visitor

‘You notice that it’s easier to talk to people you’d never spoken to before’ 8

Photo: Pim Rusch

Angela van der Poel started work at Leiden University in 1982. Since 2004 she has

Registering visitors


As soon as the lockdown started, it became very busy.

‘Once the labs were allowed to open, four to five

‘I thought it would get quieter and that there’d be time

hundred people were allowed in the building every day.

to catch up with some of the backlog of work.

But from that point on, we had some extra help from

I couldn’t have been more wrong.’ Everyone who was

the University Services Department, who took over

present in the buildings had to be registered and at

the registering of visitors.’ That gave the receptionists

first that was the job of the receptionists. ‘The first

the chance to get on with their normal activities.

week there were lots of visitors because people came

‘Receptionists from all the University’s buildings

to collect computer screens and office chairs, but even

were assigned to the Huygens Lab, even people who

after that there were easily a hundred or more people

normally work in catering.’

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been receptionist and point of contact for students and staff.

every day.’ Social contacts Peace has now descended on the reception desks again. ‘It can sometimes even be a bit too quiet with so few students and staff in the buildings.’ The atmosphere is different, but this year the receptionists got to know some new people. Van der Poel: ‘You notice that it’s easier to talk to people you’d never spoken to before. And what’s also nice is that, because of having to register so many people, I was able to put faces to a lot of the names I’d seen passing by in e-mails and post.’


The pros and cons of Physics practicals at home How do you teach Physics practicals in times of corona? Right after the first lockdown, lecturer Paul Logman and colleagues came up with a creative solution: students had to make their own minilab at home.

Lab of LEGO Only a week after the lockdown, Logman and colleagues started teaching the new practicals. ‘Most things worked out very well, and the students were happy about the solution.’ Some of the first-year students became very creative. ‘One student, Louw Feenstra, even built an interferometer set-up with LEGO. Without the lockdown, this would never have happened.’ Cons Of course, there are a lot of downsides as well. ‘You need to



simplify practicals, which means that the level is lower than

‘See you after the summer,’ Logman joked with his

usual. It’s also more expensive because students have to buy

colleagues on 13 March. ‘Well, it turned out not to be a joke

their own equipment. And staying in touch with students

after all,’ he says. ‘At the beginning of the lockdown, I really

is more difficult, so they may be more likely to drop out.

thought we couldn’t give practicals anymore.’ Until Martin

Fortunately, his institute gave Logman and his colleagues

van Exter, Director of the Physics bachelor’s programme

a lot of helpful support, he says. ‘With the current hybrid

at that time, called Logman and asked him which learning

education, our practicals even get priority for the limited

objectives could still be achieved at home. ‘It turned out that

space on campus.’ And luckily for Logman, that means he

practicals at home could satisfy most objectives.’

gets to see his colleagues now and again.

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‘One of the students built an interferometer set-up using LEGO’

Photo: Pim Rusch


Tasting the atmosphere online: student recruitment from home


Photo: Pim Rusch

Organising student recruitment activities has never been so challenging. representative a picture of studying at the Faculty of Science as possible.

Missing the bustle


This year, the University held its first ever online

Things didn’t go completely flawlessly though. ‘We had

Open Days. ‘I really missed walking around a full

some technical hitches and some prospective students

Stadsgehoorzaal, the crowded Academic Building and the

found it a bit intimidating to make video calls with

bustle during the information fair in the Pieterskerk,’ says

lecturers from the study programmes. But, I’m proud of

Van Nus. ‘Our core task is to give students a complete and

the commitment of our students and staff who, even in

realistic picture of studying in Leiden, and that’s just the

these crazy times, still manage to inform and engage with

same with online recruitment.’

students, inspiring them with enthusiasm for our study

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Communication adviser Charlotte van Nus tries to give prospective students as

programmes.’ Tasting the atmosphere Online presentations are perfectly suitable for giving detailed information about study programmes, but, as a prospective student, you want to walk around, meet the people and taste the atmosphere. ‘We try to give interested students this all-round experience as well as we can online by offering them an online 360o tour, one-on-one chats and a webinar week.’ Unlimited capacity The corona crisis has accelerated online activities for student recruitment, and going online also offers advantages. ‘We didn’t have any problems with room

‘I’m proud that we still manage to inform and engage with students, inspiring them with enthusiasm for our study programmes’

capacity, and students could watch recordings of the presentations in their own time. More students than ever attended this year’s Open Days.’ 13

Practicals at one and a half metres distance Not forty but twelve people per room, and very limited space to move around. How can you make sure that practicals can still go ahead? Trudie Brouwer, a Technical Teaching Assistant, and her colleagues worked hard to find solutions.


because no one was allowed to walk around in the

She was about to retire after 25 years at the University,

room. It called for a great deal of improvisation and

but didn’t hesitate for a second when she was asked to

stepping up several gears. ‘In mid-August it was full

stay working for longer. ‘Apparently that’s my strong

steam ahead. We worked in shifts and solved the issues

point, finding solutions to these kinds of situations.’

together. Luckily, we were given a lot of support.’

Her husband just has to be a bit patient, she says, laughing. ‘He was looking forward to my retirement,


but he knows how much I really like working.’

‘Teachers adapted their practical lessons, and students kept to the new rules,’ Brouwer says. ‘That was a great



help. It wasn’t always easy, but I’m happy that it was

‘At first, we all had to work from home. That was

possible to give any lessons at all.’ It’s clear that Brouwer

hard for us because our work is very hands on.’ From

will miss the University. ‘What I’m going to miss most

home, Brouwer and her colleagues thought hard about

is the contact with people. It doesn’t matter what

possible solutions. ‘Twelve people instead of forty per

questions people come and ask, I just enjoy being able

room and everyone had to have their own equipment

to help them.’

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‘It doesn’t matter what people ask, I just enjoy being able to help them’

Photo: Pim Rusch


‘It’s so much easier if you have people to spar with or talk issues through with’


Photo: Pim Rusch

Starting your PhD research is hard enough at the best of times, and the corona crisis doesn’t make it any easier. Luckily for astronomer Thijs Stockmans, he was no stranger to the Faculty of Science and is still able to connect with his colleagues.

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Starting your PhD during a pandemic

Plenty of challenges Nevertheless, corona still poses additional challenges. ‘Productivity, for example, is a tricky issue when you’re working from home. At the beginning of my research, I had to discover a whole new niche field by reading loads of literature. Finding the motivation was a lot more difficult at home than in the office.’ Connection is key One thing Stockmans is happy about is that he can still connect with people. ‘When it was still allowed, we had a Familiar face

dinner with all the new astronomy PhD students. During

Stockmans has been at the Leiden Observatory for five years

this second lockdown, my colleagues and I do fun things

now, having also done his bachelor’s and master’s there.

together, such as online cake baking and weekly coffee

‘That was a great help when I started my PhD. My goal is to

hours. All this makes sure that I don’t feel so alone in this

design and build a new instrument for Earth observation.

early phase of my research and I don’t run into too many

We’re trying to incorporate a new technique to fit colour,

problems. Of course, you still have to solve the problems

space and orientation of light all on a small black and white

yourself, but it’s so much easier if you have people to spar


with, or talk issues through with.’ 17

Getting teaching online pronto!

‘Corona was the catalyst for change, and since March everything has been happening at breakneck speed’


Photo: Pim Rusch

As IT & Education coordinator, Anne-Martine Gielis – together with her colleagues – is the link between course content and technology. The SEEDS team helps lecturers with digital solutions for issues relating to the different courses and assignments. And with the advent

Expanding the team

That way students have more options than to

‘When everything changed in March, there were five

spend hour after hour at their computer listening

people in the team,’ Gielis says. Since then there have

to lectures.’ A new studio was even set up where

been a lot of changes. ‘Now there are twelve of us, some

lecturers could make the recordings. ‘Lecturers can

part-time and some full-time.’

book the studio, where there are such facilities as a blackboard, green screen, and a good camera.’

Digital challenges

These are all things that were unthinkable at the

Being faced with having to get everything online in such

start of 2020. ‘Corona was the catalyst for change,

a short space of time meant the team had a very steep

and since March everything has been happening at

learning curve and had to just get on and try things

breakneck speed.’

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of corona everything had to be done in record-breaking time.

out. ‘Solutions suddenly had to be found for teaching components that don’t easily lend themselves to a digital environment.’ A lot of effort was put into finding workable solutions. ‘We started having daily digital coffee breaks to get people together so we could share our findings and experiences as quickly as possible.’ New facilities The lecturers rapidly adapted their teaching to the new digital environment. ‘They recorded lectures, for example, that could be cut into smaller elements and combined with literature and other materials. 19

From offline to online workshops Suzan Commandeur works as scientific coordinator at the Lorentz Center. Normally, she and her colleagues organise around 80 workshops a year involving researchers from all parts of the world. Hybrid workshops


Organisers saw the workshops they’d been planning

‘It was a struggle, but at the same time also

for ages suddenly go up in smoke. ‘That was a real

a development that needed to take place,’

blow, so we did our best to offer support and then

Commandeur says. Different people were involved

looked together for alternatives,’ Commandeur

in taking this initiative. ‘Together with Tanja

explains. Before doing that, they explored some new

Uitbeijerse and Nienke Tander, I took the lead on

possibilities. ‘We organised a hybrid workshop, for

behalf of the Lorentz Center in sorting things out,

example, where we received a number of Dutch

with the help of the ISSC Helpdesk and SEEDS.’

attendees on campus, in combination with virtual

In the meantime, the wheel was being reinvented

guests from all over the world.’

in several different places at the same time. ‘I’m happy that a University-wide initiative has now


been started to provide broader support not only

It’s clear that online offers new possibilities.

for teaching, but also for researchers.’

‘We did an online public lecture that people all over the world could sign up for.’ Commandeur expects to be making use of more online opportunities in the future. ‘Offline will probably become more exclusive, which reflects the growing preference of scientists to be more selective in their travel because of the carbon footprint.’ 20

‘It was a struggle, but We Are Science

at the same time also a development that needed to take place’

Photo: Pim Rusch


Creating order in the chaos

‘I have enormous respect for how my colleagues handle the situation’ 22

Photo: Pim Rusch

the 1.5-metre distancing rule within a couple of weeks: that was some challenge. This was the situation facing Kees Schoonwater, coordinator of the Facilities Team, and his colleagues earlier this year.

Schoonwater and his team also decided not to empty the rooms of some of the furniture, but to decide on a particular capacity for each room. ‘That choice saved us a lot of time and work. And people were really good at

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Adapting all the Faculty’s locations to

keeping to the instructions.’ Teamwork ‘Working in chaos is second nature to me. Still, my biggest concern was that a source of infection might spring up somewhere. Fortunately, we managed to avoid that,

Exceptional teamwork

which is a great achievement given the number of people

‘The biggest challenge was the amount of work,’

involved.’ It took a lot of teamwork. ‘My team has the daily

Schoonwater explains. ‘For instance, how can you get hold

challenge of talking to people and reminding them of the

of the materials you need quickly?’ His team started by

current guidelines. I have enormous respect for how they

using things they already had on site, while new supplies

handle that.’

were being organised. That made for some exceptional examples of teamwork. ‘We worked with a local company, for example, that hires out theatre equipment. They very quickly started to specialise in making protection screens.’ Common sense ‘There was also a lot of work to be done in deciding policies, drawing up rules and getting the message across.’ Most people were quick to adapt to the rules and also kept to them. ‘We looked critically at what was workable. Making all the stairs one-way traffic wasn’t feasible so we decided to give priority to people going up the stairs.’


The Hortus without visitors ‘Without the volunteers, we wouldn’t have survived the way we did’


Photo: Pim Rusch

Without visitors, the Hortus botanicus Leiden was a quiet place. A bit too quiet for the taste of back-office coordinator Nuala Teerink. She is grateful for all the support from

A wild Hortus


At the beginning of the first lockdown in late March,

‘All our staff worked very hard,’ Teerink says proudly,

back-office coordinator Nuala Teerink had to work from

‘but we absolutely needed the help of volunteers and other

home for two weeks. ‘When I came back to the Hortus, the

relations as well. They were real life-savers, and without

garden and the greenhouses were so much greener and

them, we wouldn’t have survived the way we did. So we

wilder! The lack of visitors made it a serene place, which

really appreciate their understanding, support and help.’

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volunteers and other relations. ‘They helped us to stay alive.’

was nice, but it was a shame that so many people had to miss it.’ New ideas Covid-19 also offered new opportunities. ‘We didn’t have a webshop but thanks to the lockdown, our front-office colleagues finally had time to make one.’ The Hortus also started a crowdfunding campaign to make a big 3D map of Leiden with all the little pavement plants. ‘Because a lot of weddings and other activities were cancelled, our colleagues from the sales department had more time to help us, which was great. And for our gardeners, the lack of visitors made it easier to care for the plants.’


© West 8

Coming soon: Gorlaeus bicycle storage The lower storeys of the old Gorlaeus high-rise were saved from demolition to accommodate a new bicycle storage in green surroundings. The storage will be located on the ground floor and has room for more than 3,000 bikes. The first floor will have a rooftop garden, whilst part of the old steel construction will be transformed into a plant-clad pergola.


We Are Science Photo: Marc de Haan

Douwe Breimer celebrates Professor emeritus of Pharmacology Douwe Breimer was the pro-rector at Rob van Wijk’s PhD defence, the last in Leiden University’s 444th year. On top of that, this is his 44th year as a Leiden professor. And one more celebration: our student association L.P.S.V. „Aesculapius” has celebrated his 30th anniversary as honorary chairman.


‘It’s important to keep on celebrating successes’


Photo: Monique Shaw

Michiel Kreutzer started as Dean of the Faculty of Science in January 2020. He’d been there just eight weeks when everything shut down. How does he look back on the past year?

Everything is possible


‘People sometimes compare a faculty to an oil tanker

Kreutzer is enormously proud of what the Faculty has

in that you can adjust its course just about one degree

achieved. ‘We all feel as if we’re running a marathon.

a year, but this year we completely turned a corner –

We may be a little slower than that, and provided we

and in only two weeks!’ That certainly does prove that

don’t turn it into a red zone workout, things will be

everything is possible, Kreutzer believes. ‘If we really

fine.’ The focus now is on shifting to staying the course.

put our minds to it, there’s nothing we can’t do.’

‘To be able to do that we need to keep on celebrating

A new motto

is one of those successes. Right now we’re all missing

‘The biggest challenge was nobody actually knew how

the personal contacts. I’m looking forward to meeting

to handle the situation we found ourselves in. We were

up with everyone again on campus and showing how

designing a car while we were actually driving it – and

proud we are of what we’ve achieved.’

that asks a lot of people.’ People from all over the place stepped in to get everything up and working as fast as possible, including lecturers as well as staff in support services. ‘We quickly brought people together who had the skills we needed, and we adopted a new motto: ‘a B- is now an A+.’

‘We’ve shown that we can achieve a lot together’

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our successes together. Keeping our teaching going


Girls in Science Day Working on superconductivity, finding an exoplanet or learning how to programme with Python. More than a hundred girls visited our Faculty on Thursday 13 February as part of the Girls in Science Day.


Photo: Liesbeth Dingemans

We Are Science From camel farmer to doctor As an eleven-year-old boy, Francis Lesilau stood face to face with the lion that killed his family’s camel. Forty-two years later, he obtained his doctorate at our Institute of Environmental Sciences on research into how humans and lions in Kenya can live side by side. Lesilau now travels the world as a lion expert.  Photo: Leiden University


A great year for inclusion and ‘Our journal club initiated an institute-wide conversation on equity, diversity and inclusion’


Photo: Pim Rusch

diversity PhD candidate Sanjana


Panchagnula is both

inclusiveness and diversity. ‘We’ve placed posters of

One of the main goals is to raise awareness of

committed to Inclusive

women and people of colour in astronomy around

Astronomy – an equity,

has initiated an institute-wide conversation on equity,

diversity and inclusion (EDI)

diversity and inclusion in academia.’ The committee also

committee – and also acts as

towards ensuring that fifty per cent of all invited

aims to bring about practical changes. ‘We’re working

an ambassador for incoming

speakers to our weekly colloquia are female, with a

PhD candidates.

training for all staff and students.’

focus on people of colour. We also want to provide EDI

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the building, and we’ve set up an EDI journal club that

Ambassador In her role of PhD ambassador, Panchagnula helps incoming PhD candidates. ‘We inform them about Expansion

finding housing, how to set up a bank account, and all

This year, the committee drew up a mission statement

sorts of other logistical issues.’ Normally when students

which can be found on the University website:

arrive, the ambassadors organise gatherings. ‘This year,

‘It solidifies our goals and creates a legacy for future

we couldn’t even do group tours of the campus properly.’

members. ‘The year 2020 marks significant growth after

The restrictions make it harder, but everyone is adapting

a team of volunteers was recruited. ‘Brought together by

quickly. ‘This group in particular has handled it very

associate professor Elena Maria Rossi, who has single-

well. We’ve been organising events every week, but

handedly been doing this work for many years, we are

they’ve also taken the initiative to organise online events,

now a group of fourteen volunteers.’

dinners and even an online Sinterklaas event.’



Photo: Monique Shaw

Corona Faculty in times of corona Many people were eager to return to their work at the Faculty after the first lockdown, to get back to their practical experiments. To guarantee a safe workplace, our colleagues at Facility Management corona-proofed every room in every building. Thank you!

Photo: Monique Shaw


Working from home ‘Our son Luca was born at the beginning of March,’ says Hilde Pracht-Altorf, editor at Communication and Marketing. ‘My close family was just able to visit, but the weeks that followed were unreal and lonely.’ Luckily, there are the Tuesday morning coffee breaks in Teams. ‘Just a chat about anything really, work-related or not.’


Photo: Lotte van Uittert

Corona NGL celebrates 150th anniversary online For exactly a century and a half, the Leiden Science Society (NGL) has been organising high-quality lectures to inform its members about the natural sciences. This year, NGL hosted a two-weekly online lecture series, in which Leiden scientists gave their expert views on corona-related topics.  Flowers are a good way of saying thank you. Photo: Monique Shaw


Hortus botanicus Leiden Covid-19 forced Leiden’s Hortus botanicus to close precisely during the seasonal changes in March and November, when the Hortus is at its best. Luckily, visitors were welcome the rest of the year, albeit with the necessary precautions: booking a time-slot in advance, strictly following the walking routes, and wearing a face mask indoors.


Photo: Monique Shaw

Corona Lab work during corona After a long period of silence and emptiness in the spring, our labs reopened for research this summer. Scientists were able to resume their experiments, all while keeping the recommended 1.5 metres distance. Perfect for those who appreciate their personal space.

Photo: Monique Shaw


Welcome new students! Traditionally, the EL CID introduction week is one of the social highlights of the year in Leiden. But at the height of a pandemic, we were happy to physically receive our new bachelor’s and master’s students at the Faculty for just one corona-proof session. Assessor Joost Barendse also hosted a well-attended online information session.


Photo: Pim Rusch

Corona Graduating with a bang! Graduating Covid-style: is there any way of really celebrating this momentous milestone? There is! We transformed the restaurant of the Gorlaeus Lecture Halls into a corona-safe ceremony location, complete with a signing lane and a CO2 blast cannon. The whole event was captured in photos for later.

Photo: Pim Rusch


Predicting, treating and preventing Covid-19

‘By combining computer models and organ-on-a-chip systems, we can accurately determine what is happening in the sick Covid-19 patients’


Photo: Monique Shaw

Covid-19 is a complex disease, and a lot is still unknown. Can we predict which patients will develop critical symptoms? And why is it that some patients are affected much worse than others? Immediately after the global corona outbreak in March, Thomas

Covid fingerprint


For his Covid-19 research, Hankemeier uses his

These studies help researchers identify markers

expertise in metabolomics, the field that studies the

that predict which new patients will develop

unique chemical fingerprints that specific metabolic

serious symptoms. ‘By combining the profiles with

processes leave in our bodies. Think of amino acids,

computer models and organ-on-a-chip systems,

sugars or hormones, for example. These fingerprints

we can accurately determine what is happening in

give a good indication of a person’s current health.

the sick patients,’ says Hankemeier.


Hankemeier, Professor of Analytical Biosciences, started work on finding the answers.

Hankemeier: ‘We are going determine the metabolic fingerprints in the blood of between 5,000 and

Treat and prevent

7,000 Covid-19 patients. This fingerprint consists of

Together with his colleagues, Hankemeier hopes

more than 1,000 metabolic products and lipids. It is

to improve patient care for intensive-care patients,

therefore a direct reflection of all Covid-19-relevant

the elderly and at-risk groups. With the models and

processes that take place in the body, ranging from

fingerprints, they will also be able to test the effect of

the viral infection and its consequences to the

existing and new drugs, and optimise patients’ diets

body’s reaction to it.’

and dietary supplements.


Record-breaking membrane Chemists Xue Liu and GrĂŠgory Schneider have created a new ultrathin membrane just one molecule thick. The membrane can produce a hundred times more power from seawater than the best membranes used today. The discovery opens up whole new possibilities for power generation and desalination and for building much more efficient sustainable fuel cells.


Research New design of metamaterials Metamaterials have properties that depend on their shape and architecture. Physicists Anne Meeussen and Martin van Hecke, together with colleagues at Tel Aviv University, have found a new way of designing these metamaterials and their properties by deliberately incorporating small errors. Applications for this discovery range from shoe soles and prostheses to soft robots.


Barcodes for folded molecules Alireza Mashaghi’s team at drug institute LACDR found a way to determine and classify the shape of proteins. They use simple and precise barcodes, which allow all types of protein folds to be identified. Mashagi: ‘This barcode, which can be seen as a protein fingerprint, allows for more detailed research into diseases caused by misfolded proteins, such as neuromuscular diseases and some cancers.’


Research Asteroids to hit Earth? The discovery that eleven asteroids might collide with our Earth in the future became world news. The research by John Hefele, Francesco Bortolussi and Simon Portegies Zwart has appeared on more than 200 news sites worldwide, from Mexico to Vietnam. They developed and trained an artificial neural network for this discovery. Luckily for us, the first potential collision is not until 2131. Š ESA


Plant longevity gene discovered Harvesting rice from the same field over and over, without sowing new rice plants? Omid Karami’s discovery may bring this scenario closer: the biologist discovered a gene that allows annual plants to continue to grow after flowering, instead of dying. This discovery earned Karami the first Krijn Rietveld Memorial Innovation Award, sponsored by Royal DSM.


Research Disease-transmitting mosquitoes The changes that humans are making to the landscape are beneficial for mosquitoes that spread diseases such as Zika, chikungunya and dengue. That’s what environmental scientist Maarten Schrama and colleagues wrote in Nature Scientific Reports. ‘If we know where mosquitoes thrive best, we can design our own living environment in a way that limits the risk of mosquito-borne diseases.’


Networks-on-chips Networks-on-chips are hardware that enable communication between different parts of a microchip. They have been around for over twenty years, but they are still not used widely because they consume too much power. During his PhD research, computer scientist Peng Wang found a solution for this power inefficiency.


Research Testing vaccines without lab animals Laboratory animals are still frequently used to test the quality of vaccines. But drug researchers Thomas Michiels, Wim Jiskoot and Gideon Kersten, together with vaccinology institute Intravacc, are developing a new test method that makes animal testing unnecessary. A change in the degradation rate of the vaccine should indicate whether it has been successfully inactivated or defused.


SAILS takes Artificial Intelligence to the next level ‘Together with Delft and Rotterdam, we make up a strong AI cluster in South Holland’


Photo: Patricia Nauta

Society artificial intelligence and Life Sciences, or SAILS, is a new University-wide intelligence within Leiden University. Computer scientist Joost Batenburg joined the initiative this year as SAILS professor.

AI is everywhere

Strong AI cluster

‘Artificial intelligence (AI) – the use of computer

If there’s one thing we can be sure of, it’s that AI is

systems that can perform intelligent tasks and

going to become more important as time goes on,

decision-making – is all around us,’ says Professor

says the SAILS professor. ‘Fortunately, we make

Batenburg, who is also the new Programme

up a strong AI cluster in South Holland, together

Director of SAILS. ‘AI is used in hospitals and in

with Delft and Rotterdam, the university medical

industry, but you can also find it at our Faculty.

centres and, of course, the business community.

For example, our pharmacologists use AI to make

Another plus is that Leiden Professor Holger

the search for medicines more efficient.’

Hoos is the founder of CLAIRE, the organisation


initiative that looks to build on and expand the current expertise on artificial

that brings AI in Europe together. So we’re going Platform for collaboration

strong here in Leiden!’

Batenburg and his SAILS colleagues will focus on creating and strengthening active and vibrant research collaborations across the faculties of the University. ‘I aim to use the advances in the field of AI as a powerful platform for interdisciplinary research collaboration, linking the available domain expertise with machine intelligence.’


Š Tom Langelaar

World champions The students from iGEM Leiden have won the Grand Prize at the iGEM international biology competition. They impressed the judges with Rapidemic, a test kit to detect infectious diseases such as Covid-19 at an early stage. The kit is easy to produce and can be adapted quickly to different pathogens, which can help prevent future pandemics.


Education Kids’ outlook on computer scientists Children think programmers are more social than writers. That is one remarkable conclusion drawn by computer scientists Shirley de Wit, Efthimia Aivaloglou and Felienne Hermans. Even so, programming is not very popular as a profession: something our computer scientists are hoping to change.


© Space in Your Living Room

Space in your living room This summer, Space in Your Living Room brought astronauts, artists, space scientists and engineers into living rooms across Europe and beyond. During Leiden Observatory’s online astronomy summer programme, children interacted with space professionals from different backgrounds, through competitions, meet ‘n greets and hands-on online workshops.



Photo: screenshot from video

Tutoring children from The Hague In the Leiden Tutor programme, Leiden students support junior school pupils from lower socio-economic backgrounds. That’s no easy task, so our Science Communication & Society department has now launched a website offering tips and tricks that can also be used by other tutors in the Netherlands.


Meet the Professor Talking about your research at your old primary school: Professor of Immunobiology Annemarie Meijer from the Leiden Institute of Biology gave a guest lecture to pupils in group 7 on the occasion of Leiden University’s Dies Natalis. She was one of no fewer than a hundred professors who took part in the Meet the Professor event on 7 February.


Photo: Hielco Kuipers

Education Students help municipalities In the Resilient Cities Hub, students research how we can make the cities of Leiden and The Hague more sustainable and resilient. They presented their findings to municipal officials during a knowledge cafÊ in January. A virtual reality artist was present to visualise the students’ research findings. Photo: Bryce Benda


© Royal Society of Chemistry

The world’s tiniest boat This tiny boat made quite a splash: from CNN to Japanese news media, the whole world was intrigued by this 3D-printed boat made by Rachel Doherty, Daniela Kraft and other physicists. From prow to stern, the boat measures 30 micrometres, about a third of the thickness of a hair. It is part of a study into micro-swimmers moving in fluids.


Science & Society Š Lisa Pothoven

Sustainable conferences Leonard Burtscher, together with international astronomers, has calculated that the face-to-face astronomy conference EAS2019 contributed 3,000 times more carbon dioxide than the online conference EAS2020. The 2020 event was due to be held in Leiden, but was moved online due to corona. The researchers suggest that a combination of online lectures with regional offline meetings could be a sustainable alternative for future conferences.


Photo: Jayshri Murli

A fusion of reading and programming What do reading and computer programming have in common? Well, stories are a great way of making children enthusiastic about programming, Felienne Hermans (left) and author Inge Strijker (right) thought. ‘It’s not a textbook or schoolbook, but an exciting story that lets children programme and experience exciting adventures,’ says Hermans.


Science & Society © DASPO

Calculating cancer survival probabilities When treating cancer, it’s important to know the patient’s survival probability, but making an accurate estimate isn’t easy. Based on worldwide cancer patient data, mathematician Anja Rüten-Budde (2nd from the right) developed a statistical method to calculate survival probabilities of soft-tissue sarcoma patients. Her results have been used to create a prediction app for doctors and patients.


In Ovo saves chicks At present, newly hatched chicks are sorted manually according to sex. As the males cannot lay eggs, they are destroyed immediately after hatching. Biotech company In Ovo, a Leiden University spin-off, was awarded a European Innovation Council Accelerator Pilot Grant . The company will use this grant of 2.5 million euros in its mission to stop the culling of male chicks.


Š In Ovo

Science & Society Reducing litter in 2020 Biology students had an environmentally friendly introduction to the Leiden Bio Science Park, with the help of Plastic Spotters Liselotte Rambonnet and Auke-Florian Hiemstra. Carrying rubbish bags and trash pickers, they toured the park and collected litter, and gathered data about the types of litter and litter hotspots in the area. Photo: Liselotte Rambonnet


Computers against illegal logging Illegal logging rarely leads to prosecution as studying the wood anatomy is one of the only ways to trace  the origin of the timber. At the same time, wood anatomists are becoming increasingly scarce. Computer scientists Fons Verbeek, Mehrdad Jahanbanifard and Xiaoqin Tang, anatomists from Naturalis and internationally renowned wood experts are therefore working on a computer-aided tool for wood identification. 


Science & Society Pesticide thiacloprid banned The Living Lab has contributed to the ban on the agricultural pesticide thiacloprid. Environmental scientists Martina Vijver and Henrik Barmentlo showed that the pesticide is up to 2,500 times more harmful to insects than had been estimated based on lab tests. The outdoor lab consists of 38 small water-filled channels in open nature, resulting in much more realistic research outcomes. Photo: Monique Shaw


© Hendrik Lenstra and colleagues

Escher’s unfinished artwork In 2000, mathematician Hendrik Lenstra came across the unfinished artwork Print Gallery, a fractal-like lithography by Dutch artist M.C. Escher. Three years later, he and his colleagues managed to complete the artwork. Now, a further seventeen years later, Lenstra’s efforts have been described in Nature Physics as part of a review of an Escher exhibition in Italy.


Science & Society Photo: Charlotte Ellerman

Gorlaeus high-rise lives on Once the backbone of Leiden’s laboratories, now the skeleton of two new buildings: our former Gorlaeus high-rise continues to live on. If you look closely, you can spot the metal beams in the skeleton of PLNT’s Circular Pavilion near Leiden Central Station. The beams have also been used for the circular construction of BioPartner 5 at the Leiden Bio Science Park.


1225 Diplomas 2019-2020


M Bachelor’s

719 9





cum laude

cum laude

summa cum laude

summa cum laude

+ 70


Honours College



156 193 202 654 318 117 3


Full professors

Assistant & associate professors


PhD candidates

Guest PhD candidates

3445 2267 42% 1147 849

BSc students

MSc students


Facts & Figures


Intake BSc students

Intake MSc students

PhD defences

Cum laude PhD defences 71

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