Development of Lab-Scale Continuous Stirred-Tank Reactor as Flow Process Tool for Oxidation Reactions Using Molecular Oxygen.

The use of sustainable oxidants is of great interest to the chemical industry, considering the importance of oxidation reactions for the manufacturing of chemicals and society's growing awareness of its environmental impact. Molecular oxygen (O2), with an almost optimal atom efficiency in oxidation reactions, presents one of the most attractive alternatives to common reagents that are not only toxic in most cases but produce stoichiometric amounts of waste that must be treated. However, fire and explosion safety concerns, especially when used in combination with organic solvents, restrict its easy use. Here, we use state-of-the-art 3D printing and experimental feedback to develop a miniature continuous stirred-tank reactor (mini-CSTR) that enables efficient use of O2 as an oxidant in organic chemistry. Outstanding heat dissipation properties, achieved through integrated jacket cooling and a high surface-to-volume ratio, allow for a safe operation of the exothermic oxidation of 2-ethylhexanal, surpassing previously reported product selectivity. Moving well beyond the proof-of-concept stage, we characterize and illustrate the reactor's potential in the gas-liquid-solid triphasic synthesis of an endoperoxide precursor of antileishmanial agents. The custom-designed magnetic overhead stirring unit provides improved stirring efficiency, facilitating the handling of suspensions and, in combination with the borosilicate gas dispersion plate, leading to an optimized gas-liquid interface. These results underscore the immense potential that lies within the use of mini-CSTR in sustainable chemistry.

A Review of Polylactic Acid as a Replacement Material for Single-Use Laboratory Components.

Every year, the EU emits 13.4 Mt of CO2 solely from plastic production, with 99% of all plastics being produced from fossil fuel sources, while those that are produced from renewable sources use food products as feedstocks. In 2019, 29 Mt of plastic waste was collected in Europe. It is estimated that 32% was recycled, 43% was incinerated and 25% was sent to landfill. It has been estimated that life-sciences (biology, medicine, etc.) alone create plastic waste of approximately 5.5 Mt/yr, the majority being disposed of by incineration. The vast majority of this plastic waste is made from fossil fuel sources, though there is a growing interest in the possible use of bioplastics as a viable alternative for single-use lab consumables, such as petri dishes, pipette tips, etc. However, to-date only limited bioplastic replacement examples exist. In this review, common polymers used for labware are discussed, along with examining the possibility of replacing these materials with bioplastics, specifically polylactic acid (PLA). The material properties of PLA are described, along with possible functional improvements dure to additives. Finally, the standards and benchmarks needed for assessing bioplastics produced for labware components are reviewed.

Distance Teaching in Chemistry: Opportunities and Limitations.

Remote teaching in the tertiary education sector is a relatively common practice, and the implementation of digital solutions in chemistry teaching offers many new opportunities and tools. A survey was conducted after 3 months of emergency remote teaching linked to the COVID-19 pandemic and showed that half of the students estimated it was difficult to study remotely, and reported they had to invest more time compared to classroom teaching, which led to a drop in motivation. Professors also noted that the time necessary to invest in order to produce digital teaching content was enormous. Massive open online laboratories (MOOLs) and process simulators are interesting tools, but practical lab work and related know-how cannot fully be replaced by digital techniques. Finally, it appeared that the professor-student interaction is very important in the distance-learning process, and that a high level of pedagogical (inter)activity is mandatory to maintain motivation and better quality of teaching and learning.

Analytical Platforms at Swiss Universities of Applied Sciences.

Numerous projects and industrial and academic collaborations benefit from state-of-the-art facilities and expertise in analytical chemistry available at the Swiss Universities of Applied Sciences. This review summarizes areas of expertise in analytical sciences at the University of Applied Sciences and Arts Northwestern Switzerland (FHNW), the University of Applied Sciences and Arts Western Switzerland (HES-SO), and the Zurich University of Applied Sciences (ZHAW). We briefly discuss selected projects in different fields of analytical sciences.

Continuous Monitoring of Shelf Lives of Materials by Application of Data Loggers with Implemented Kinetic Parameters.

The evaluation of the shelf life of, for example, food, pharmaceutical materials, polymers, and energetic materials at room or daily climate fluctuation temperatures requires kinetic analysis in temperature ranges which are as similar as possible to those at which the products will be stored or transported in. A comparison of the results of the evaluation of the shelf life of a propellant and a vaccine calculated by advanced kinetics and simplified 0th and 1st order kinetic models is presented. The obtained simulations show that the application of simplified kinetics or the commonly used mean kinetic temperature approach may result in an imprecise estimation of the shelf life. The implementation of the kinetic parameters obtained from advanced kinetic analyses into programmable data loggers allows the continuous online evaluation and display on a smartphone of the current extent of the deterioration of materials. The proposed approach is universal and can be used for any goods, any methods of shelf life determination, and any type of data loggers. Presented in this study, the continuous evaluation of the shelf life of perishable goods based on the Internet of Things (IoT) paradigm helps in the optimal storage/shipment and results in a significant decrease of waste.

International Relations at Universities of Applied Sciences.

An overview of international relations at the Universities of Applied Sciences in Switzerland is presented.

International Relations at Universities of Applied Sciences.

An overview of international relations at the Universities of Applied Sciences in Switzerland is presented.

On-line Monitoring and Control of Fed-batch Fermentations in Winemaking.

The fermentation of yeast in fed-batch mode shows great potential in winemaking because it allows the concentration of sugars to be kept low and constant throughout the process which, in turn, reduces cell stress and leads to a significant decrease in the production of unwanted secondary metabolites. The implementation of this technique requires reliable on-line analysis of sugar and a robust control strategy to maintain sugar concentrations at defined levels over the course of the fermentation. In this study, a laboratory-scale setup was used to implement and assess a fully automated fed-batch fermentation of Saccharomyces cerevisiae in grape must. Total sugar levels were monitored in-line by FT-MIR ATR spectroscopy and kept constant at 50 g/kg by a modified PI controller regulating the must feed flow rate. Good setpoint tracking and disturbance rejection were achieved in fermentations of up to four days despite occasional yeast sedimentation on the ATR crystal. The controller parameter adaptation strategy needs to be optimized for longer fermentations.

PAT at the Universities of Applied Sciences.

An overview of activities in the field of Process Analytical Technologies (PAT) at the Universities of Applied Sciences in Switzerland is presented.

PAT at the Universities of Applied Sciences.

An overview of activities in the field of Process Analytical Technologies (PAT) at the Universities of Applied Sciences in Switzerland is presented.

Optimization of chemical reactor feed by simulations based on a kinetic approach.

Chemical incidents are typically caused by loss of control, resulting in runaway reactions or process deviations in different stages of the production. In the case of fed-batch reactors, the problem generally encountered is the accumulation of heat. This is directly related to the temperature of the process, the reaction kinetics and adiabatic temperature rise, which is the maximum temperature attainable in the event of cooling failure. The main possibility to control the heat accumulation is the use of a well-controlled adapted feed. The feed rate can be adjusted by using reaction and reactor dynamic models coupled to Model Predictive Control. Thereby, it is possible to predict the best feed profile respecting the safety constraints.

Simple control of specific growth rate in biotechnological fed-batch processes based on enhanced online measurements of biomass.

Reliable control of the specific growth rate (µ) in fed-batch fermentations depends on the availability of accurate online estimations of the controlled variable. Due to difficulties in measuring biomass, µ is typically estimated using reference models relating measurements of substrate consumption or oxygen uptake rate to biomass growth. However, as culture conditions vary, these models are adapted dynamically, resulting in complex algorithms that lack the necessary robustness for industrial applicability. A simpler approach is presented where biomass is monitored using dielectric spectroscopy. The measurements are subjected to online balances and reconciled in real time against metabolite concentrations and off-gas composition. The reconciled biomass values serve to estimate the growth rate and a simple control scheme is implemented to maintain the desired value of µ. The methodology is developed with the yeast Kluyveromyces marxianus, tested for disturbance rejection and validated with two other strains. It is applicable to other cellular systems with minor modifications.

Data reconciliation of concentration estimates from mid-infrared and dielectric spectral measurements for improved on-line monitoring of bioprocesses.

Real-time data reconciliation of concentration estimates of process analytes and biomass in microbial fermentations is investigated. A Fourier-transform mid-infrared spectrometer predicting the concentrations of process metabolites is used in parallel with a dielectric spectrometer predicting the biomass concentration during a batch fermentation of the yeast Saccharomyces cerevisiae. Calibration models developed off-line for both spectrometers suffer from poor predictive capability due to instrumental and process drifts unseen during calibration. To address this problem, the predicted metabolite and biomass concentrations, along with off-gas analysis and base addition measurements, are reconciled in real-time based on the closure of mass and elemental balances. A statistical test is used to confirm the integrity of the balances, and a non-negativity constraint is used to guide the data reconciliation algorithm toward positive concentrations. It is verified experimentally that the proposed approach reduces the standard error of prediction without the need for additional off-line analysis.

Cole-Cole, linear and multivariate modeling of capacitance data for on-line monitoring of biomass.

This work evaluates three techniques of calibrating capacitance (dielectric) spectrometers used for on-line monitoring of biomass: modeling of cell properties using the theoretical Cole-Cole equation, linear regression of dual-frequency capacitance measurements on biomass concentration, and multivariate (PLS) modeling of scanning dielectric spectra. The performance and robustness of each technique is assessed during a sequence of validation batches in two experimental settings of differing signal noise. In more noisy conditions, the Cole-Cole model had significantly higher biomass concentration prediction errors than the linear and multivariate models. The PLS model was the most robust in handling signal noise. In less noisy conditions, the three models performed similarly. Estimates of the mean cell size were done additionally using the Cole-Cole and PLS models, the latter technique giving more satisfactory results.

On-line recalibration of spectral measurements using metabolite injections and dynamic orthogonal projection.

Spectrometers are enjoying increasing popularity in bioprocess monitoring due to their non-invasiveness and in situ sterilizability. Their on-line applicability and high measurement frequency create an interesting opportunity for process control and optimization tasks. However, building and maintaining a robust calibration model for the on-line estimation of key variables of interest (e.g., concentrations of selected metabolites) is time consuming and costly. One of the main drawbacks of using infrared (IR) spectrometers on-line is that IR spectra are compromised by both long-term drifts and short-term sudden shifts due to instrumental effects or process shifts that might be unseen during calibration. The effect of instrumental drifts can normally be reduced by referencing the measurements against a background solution, but this option is difficult to implement for single-beam instruments due to sterility issues. In this work, in order to maintain the robustness of calibration models for single-beam IR and to increase resistance to process and instrumental drifts, planned spikes of small amounts of analytes were injected periodically into the monitored medium. The corresponding measured difference spectra were scaled-up and used as reference measurements for updating the calibration model in real time based on dynamic orthogonal projection (DOP). Applying this technique led to a noticeable decrease in the standard error of prediction of metabolite concentrations monitored during an anaerobic fermentation of the yeast Saccharomyces cerevisiae.