PD in Printing of Complex Fluids

Do you have a passion for understanding microscale fluid flows at very high speeds? Are you driven by the challenge of pushing technology innovation to the next level? This postdoctoral researcher (PD) position might be for you!

This project will explore how multicomponent fluids flows in droplets just after being created during the process of inkjet printing using piezoactuation. Inkjet printing has moved beyond printing graphics on paper, and its applicability has been demonstrated for numerous applications such as contact lenses, dental implants, electronic circuit boards, solar panels, 3D rapid prototypes, and even for printing of DNA and protein substances. These new applications demand the utmost in terms of reliability, as an imprecise deposition of even a single droplet can render the printed application useless, e.g. circuit failures in printed electronics. The state-of-the-art applications require inkjet printing to generate as small as possible droplets (few microns in size) of highly complex fluids at the highest possible rates (e.g. 100000 droplets being generated every second, with speeds of several meters per second), while also maintaining constant droplet volumes and impact velocities.

Previous studies have revealed that solid impurities in the ink can cause bubble entrainment causing cavitation or by directly interacting with the oscillating meniscus. Ultra high-speed experimental imaging and corresponding highly resolved numerical simulations have shown that this vorticity field in the fluid arises due to the misalignment of the density and pressure gradients at the liquid-air interface within the nozzle, resulting in meniscus distortions and bubble pinch-off, yielding what are known as satellite droplets. These unwanted droplets can cause direct failure or loss of performance of the final printed features. As inks increase in complexity due to multiple components, and additionally as ink solid fraction, e.g. pigments, increase, the likelihood of these impurities forming increases dramatically.

The aim of this PD project is to gain an in-depth quantitative understanding of the physicochemical hydrodynamics governing the jetting behaviour of a complex multicomponent fluid, i.e. a fluid containing multiple miscible liquids, surfactants, polymers, and colloidal pigment particles just after droplet creation. This experimental project will design, develop, and build a high-speed imaging instrument coupled to a fluorescent light sheet microscope, as well as bespoke colloidal particles and surfactant molecules that enable imaging at such extreme time and length scales.

Your duties and responsibilities include:

• develop your own experimental tools to investigate droplet formation in inkjet printing at high speeds;
• create model ink systems containing multiple components similar to but reduced in complexity to industrial inks;
• explain and communicate your findings to both academic and industrial collaborators;
• working with a larger team of researchers to investigate this interdisciplinary challenge.

You will work here
The research is embedded within the chair group of Physical Chemistry and Soft Matter (link), which is led by Prof. Jasper van der Gucht. You will be co-supervised primarily by dr. Thomas Kodger and supported by dr. Uddalok Sen, member of the Physical Chemistry and Soft Matter laboratory. During your PD, you will directly collaborate with a PhD Candidate who will have approximately 6 months experience in their position.

Postdoc: High throughput microfluidics for protein functionality measurement

Are you fascinated by microfluidic systems? Do you want to contribute to the future of food production within our ‘Future Foods Project’? Ready for your next step in science? This post-doc position might be a good opportunity for you!

With this post-doc position based at the laboratory of Food Process Engineering, you will play a pivotal role in the EU Future Foods project. You will bridge experimental and modelling results in order to arrive at microfluidic device that can be used for high-throughput screening of protein functionality. You will work in an international consortium consisting of both academic and industrial partners, dedicated to boosting the use of proteins that are less impactful for the planet we live in.

As our post-doc you will be responsible for bringing our existing microfluidic techniques to a next level, allowing their use under a wide range of process conditions, to thus be in a position to connect processes that occur at small scale to stability of food products, also at longer time scales. If successful this will speed up food product innovation greatly, and allow the use of alternative protein sources based on first principles.

You will take the lead in connecting with our project partners, manage BSc and MSc thesis students participating in the project, as well as connect with our technical support staff. We expect you to also become a valuable part of our post-doc/PhD candidate community and connect with other scientific staff.

Your duties and responsibilities include:

• design a microfluidic system in which the process conditions can be adjusted over a wide range, thus allowing analysis of protein functionality at high throughput fashion;
• write your findings down in scientific papers, and present at (international) conferences;
• manage the project, and keep close connections with project partners;
• manage projects of thesis students contributing to your project.

Your team
You will work within the chair group of Food Process Engineering of Wageningen University, and will be coached by prof. Karin Schroën. The FPE group has around 20 scientific and support staff, 40 PhD candidates and post-docs. You will become part of this dynamic group that on an annual basis also is the home of 50 thesis students.

You will work here
Information about chair group: https://www.wur.nl/en/chair-groups/food-sciences-and-technology/food-process-engineering.

PhD in Validation Frameworks for Near-Real-Time Land Cover Change Monitoring

Are you fascinated by the rapid evolution of Earth Observation (EO) and eager to shape the next generation of validation methods for near-real-time land change monitoring? Do you hold an MSc (or equivalent) in Remote Sensing, Geoinformation Science, Statistics, or a closely related discipline, and feel comfortable programming in Python/R? Are you a critical thinker who can assess EO products, question their assumptions, limitations, and usability in operational contexts? If so, we have an exciting PhD opportunity for you! If so, we have an exciting PhD opportunity for you!

Recent advances in EO, such as dense satellite time series, rapid data access, and machine learning, have enabled the detection of deforestation, fires, floods, agricultural activities, and land cover transitions at sub-annual or near-real-time intervals. However, validation methods for assessing the monitoring products have not developed at the same pace, creating a gap between what monitoring systems can produce and what policymakers and enforcement agencies can confidently use. The current validation frameworks were designed for annual or static products and fail to address several key areas:

• Time-evolving assessments: both predictions and reference data change over time, requiring methods that account for temporal misalignment.
• Variable observation density: seasonal cloud cover, satellite revisit times, and sensor changes lead to inconsistent data availability.
• Reference data uncertainty: besides temporal misalignment, geolocation errors, and unclear class definitions affect validation reliability.

This PhD research will develop statistically rigorous and operationally feasible validation methods for near-real-time monitoring. The methods will be applicable to both single-class alerts (e.g., forest loss) and multi-class land cover change products.

Specific research objectives

1. Develop spatiotemporal assessment frameworks that evaluate both where and when a monitoring system correctly identifies a change.
2. Account for reference data uncertainty (e.g. timing uncertainty and labelling errors) and incorporate it into performance metrics such as accuracy, timeliness, and detection delay.
3. Design a spatiotemporal sampling strategy for rigorously capturing the variability of land-cover transitions across ecosystems and seasons, while remaining practical for operational monitoring.
4. Implement and test the proposed framework on existing near-real-time and sub-annual EO monitoring products.

The outcomes will improve the reliability, transparency, and comparability of near-real-time monitoring systems across a wide range of applications such as climate mitigation and disaster response.

The research is hosted within the Laboratory for Geo-information Science and Remote Sensing (GRS) and will be supervised by Dr. Nandika Tsendbazar (land cover validation), Dr. Johannes Reiche (near-real-time monitoring), and Prof. Dr. Sytze de Bruin (spatial statistics). This PhD programme is also a part of PE&RC, a collaborative research and PhD training institute coordinated by Wageningen University (WU). The central focus of the collaboration is the PhD programme, embedded in a coherent and productive research environment that aims to conduct academic research of the highest quality. For more information, click here.

Postdoc in Scaling Soil Moisture Retention Practices in East Africa

Are you interested in the scaling of field-level practices for enhanced climate resilience of smallholder farming systems in Ethiopia and Kenya? Are you intrigued by understanding the drivers of scaling processes, and do you have interdisciplinary skills enabling you to conduct trade-off and scenario analyses? Then this may be the perfect postdoc position for you!

As Postdoctoral Researcher in Scaling Soil Moisture Retention (SMR) Practices you will play a key role in the SMARTSCALE project, especially in integrating research findings from across two distinct case studies of SMR scaling processes in respectively Eastern Kenya and Southern Ethiopia. The research question to be addressed is: What are the synergies and trade-offs among different SMR and yield-enhancing practices at farm and landscape levels under current and future climate scenarios? By integrating literature, remote sensing, and field data, you will work on clarifying the links between water and food security in rainfed systems in Ethiopia and Kenya. Cost-benefit and return-to-labor analyses will inform farmer decisions, while multi-criteria analysis will help wider (institutional) stakeholders assess trade-offs.

The SMARTSCALE project, funded by NWO under the NL-CGIAR Water-Food Nexus programme, aims to help farmers in semiarid Kenya and Ethiopia use soil moisture more effectively to grow food, mitigate climate risks, and improve their livelihoods. Many past efforts on scaling and adoption of SMR practices have not reached vulnerable groups or created impact at scale. SMARTSCALE brings together scientists, local partners, and governments to learn from past experiences and design better ways to spread moisture-saving practices. By focusing on local needs, government systems, and inclusive solutions for women and youth, the project aims to make lasting change. Partners include Alliance Bioversity-CIAT, Wageningen University, Bahir Dar University, JKUAT, and the Ministries of Agriculture in both countries. The postdoc will work in close collaboration with the project partners and with PhD and MSc students in Kenya and Ethiopia.

Your duties and responsibilities

• Contextualize scaling in top-down vs bottom-up environments by conducting a comparative analysis of the contextual barriers and opportunities in supply-push vs decentralized, market-mediated governance and institutional settings;
• Compare planned vs observed applicability domains of SMR practices across agroecological zones using mixed methods (e.g. statistical databases, remote sensing, field observations, interviews);
• Conduct landscape level ex-ante scenario impact assessments to quantify short-term climate risks, long-term resilience, and economic performance. Drivers for the analyses will be the intervention plans of multi-stakeholder platforms (Ethiopia) and expected behaviors of agripreneurs and farmers (Kenya) using agent-based models;
• Assess the potential for co-developed SMRPs in changing social-ecological systems by comparing the measured effects of scaling interventions and evaluating opportunities for SMRP bundles;
• Co-supervision of PhD and MSc students working on related activities within the SMARTSCALE project.

Your team
You’ll be offered an initial 18-month contract from Wageningen University & Research. After this period, it is a possibility to continue as a postdoc in this same project for another 30 months, on an employment contract offered by Alliance Bioversity – CIAT based in Nairobi or Addis Abeba. In this postdoc role you will work intensively with all project partner organisations, and PhD and MSc students, on location and virtually. Within Wageningen University, the chair groups Soil Physics and Land Management (SLM) and Development Economics (DEC) are contributing to the SMARTSCALE project.

You will work here
The position is embedded within the chair Soil Physics and Land Management (SLM). The SLM group advances understanding of soil physical processes and their role in supporting soil functions and addresses sustainable soil and land management to support global societal challenges of climate, water and food security. The SLM group is a dynamic group with ca. 20 academic staff, 10 postdocs and support staff and 60 PhD students. You will work under the supervision of Dr. Luuk Fleskens. You will work from Wageningen, with project meetings and fieldwork taking place in Ethiopia and Kenya.

All-round laboratorium medewerker Visserij

Houd jij van afwisseling in het werk en wil jij een bijdrage leveren aan het vis- en visserijonderzoek en werk je graag samen? Dan hebben we bij Wageningen Marine Research een leuke vacature als allround labmedewerker in IJmuiden voor jou! Deze functie wordt in eerste instantie aangeboden voor een periode van zes maanden.

Met jouw praktische ervaring, soortenkennis en nauwkeurigheid zorg jij ervoor dat de onderzoeken goed kunnen worden uitgevoerd.

Jouw taken en verantwoordelijkheden als labmedewerker zijn:

• monsterverwerking in onderzoeksruimtes van WMR of tijdens bezoeken aan de visafslagen in het land;
• logistieke organisatie van monstername zowel op het lab als in het land;
• bezoeken van vissersschepen om monsters op te halen;
• onderzoeksdata vastleggen, eventuele afwijkingen signaleren en data aanleveren aan onderzoekers.

Jij gaat samenwerken met verschillende collega’s in diverse projectgroepen op het gebied van vis- en visserij en bent breed inzetbaar voor diverse onderzoeken, zoals bijvangsten en commerciële vis. Jouw uitvalbasis is het kantoor en de onderzoeksruimtes van Wageningen Marine Research in IJmuiden.