Nonlinear state estimation as tool for online monitoring and adaptive feed in high throughput cultivations.

Robotic facilities that can perform advanced cultivations (e.g., fed-batch or continuous) in high throughput have drastically increased the speed and reliability of the bioprocess development pipeline. Still, developing reliable analytical technologies, that can cope with the throughput of the cultivation system, has proven to be very challenging. On the one hand, the analytical accuracy suffers from the low sampling volumes, and on the other hand, the number of samples that must be treated rapidly is very large. These issues have been a major limitation for the implementation of feedback control methods in miniaturized bioreactor systems, where observations of the process states are typically obtained after the experiment has finished. In this work, we implement a Sigma-Point Kalman Filter in a high throughput platform with 24 parallel experiments at the mL-scale to demonstrate its viability and added value in high throughput experiments. The filter exploits the information generated by the ammonia-based pH control to enable the continuous estimation of the biomass concentration, a critical state to monitor the specific rates of production and consumption in the process. The objective in the selected case study is to ensure that the selected specific substrate consumption rate is tightly controlled throughout the complete Escherichia coli cultivations for recombinant production of an antibody fragment.

Direct Conversion of Syngas to Higher Alcohols via Tandem Integration of Fischer-Tropsch Synthesis and Reductive Hydroformylation.

The selective conversion of syngas to higher alcohols is an attractive albeit elusive route in the quest for effective production of chemicals from alternative carbon resources. We report the tandem integration of solid cobalt Fischer-Tropsch and molecular hydroformylation catalysts in a one-pot slurry-phase process. Unprecedented selectivities (>50 wt %) to C2+ alcohols are achieved at CO conversion levels >70 %, alongside negligible CO2 side-production. The efficient overall transformation is enabled by catalyst engineering, bridging gaps in operation temperature and intrinsic selectivity which have classically precluded integration of these reactions in a single conversion step. Swift capture of 1-olefin Fischer-Tropsch primary products by the molecular hydroformylation catalyst, presumably within the pores of the solid catalyst is key for high alcohol selectivity. The results underscore that controlled cooperation between solid aggregate and soluble molecular metal catalysts, which pertain to traditionally dichotomic realms of heterogeneous and homogeneous catalysis, is a promising blueprint toward selective conversion processes.

Conversion of CO2 and small alkanes to platform chemicals over Mo2C-based catalysts.

The performance of Mo2C-based catalysts in CO2 assisted oxidative dehydrogenation (CO2-ODH) of ethane was evaluated. Mo2C on SiO2 was synthesized via three different techniques: wet impregnation (WI), hybrid nanocrystal technique (HNC) and sol-gel method (SG) and exposed to the same carburization conditions. In terms of characteristic properties, the allotrope composition was the most affected, with the SG sample containing MoOxCy and the WI and HNC samples containing ß-Mo2C. The two different allotropes were suggested to follow different reaction pathways, leading to small differences in the catalytic performance. However, overall, all three catalysts showed a decrease in activity (below 6%) and an increase in C2H4 selectivity (from 60 to 80 C%) with time on stream (TOS). The deactivation mechanism was suggested to be mainly due to oxidation of the carbide to MoOx and carbon deposition. Mo2C was also supported on various metal oxide materials via the wet impregnation technique. Mo2C supported on Al2O3 and ZrO2 increased initial activity (about 8% C2H6 conversion) but a faster deactivation with TOS was observed. Mo2C/Ga2O3 favoured the direct dehydrogenation reaction achieving high C2H4 selectivities (above 80 C%), but deactivation with TOS due to carbon deposition was significant. Mo2C supported on CeO2 and TiO2 had lower activity (about 3% C2H6 conversion). Oxidation to MoO2 and carbon deposition is again suggested to be the main deactivation mechanism. H2 co-feeding, on Mo2C/SiO2 and Mo2C/ZrO2, increased the stability of the catalysts but C2H4 yield was affected (from 5 to 2%). At 17 vol% H2 co-feeding, Mo2C/ZrO2 showed promising catalyst stability over a 20 h period, paralleled by a stable C2H4 yield.

Supported FexNiy catalysts for the co-activation of CO2 and small alkanes.

The effect of both the Fe : Ni ratio (5 to 1 : 1) and the relative Lewis acidity of a metal oxide support on catalytic activity, selectivity and stability was investigated in the CO2 mediated oxidative dehydrogenation of ethane (CO2-ODH). To avoid effects of varying pore sizes, shapes and volumes of the supports, chromia and zirconia overlayers were coated onto a common γ-Al2O3 carrier (CrOx@Al2O3 and ZrOx@Al2O3). Separately, oxidic FexNiy alloy precursor nanoparticles were prepared using a nonaqueous surfactant-free method and deposited by sonication onto the carrier. In comparison to previous studies in the field, this synthesis technique yields closely associated iron and nickel increasing the chances for alloy formation. During reduction, a mixture of a bcc and a fcc alloy phase was formed, with the content of bcc increasing with increasing iron content as predicted by the bulk phase diagram. Upon exposure to carbon dioxide at elevated temperatures, the bcc metallic phase is selectively oxidised to an inverse spinel structure via the dissociation of CO2. When exposed to CO2-ODH conditions, the bare ZrOx@Al2O3 support shows no activity. The presence of FeNi phases increases the conversion of ethane and CO2 marginally (<2%) but forms ethylene at high selectivity (SC2H4 > 80%). The CrOx@Al2O3 support shows some initial activity (XC2H6 < 5%) at very high ethylene selectivity (SC2H4 > 90%) but deactivates with time on stream. Comparison of the ethane and carbon dioxide conversions suggests that direct dehydrogenation rather than the oxidative pathway is taking place. When FeNi particles with the highest Fe content are added, the ethane conversion behavior hardly changes, but the CO2 conversion is increased now supporting the stoichiometric CO2-ODH reaction (SC2H4 > 95%). It is therefore evident that a tandem catalyst system between a reducible oxide carrier and the FeNi species is required. Increasing the Ni content results in an increase in activity and stability while changing the dominant reaction pathway to a combination of dry reforming, CO2-ODH and possibly the reverse Boudouard reaction, with the latter countering catalyst deactivation through carbon deposition.

High-density Peptide Arrays Help to Identify Linear Immunogenic B-cell Epitopes in Individuals Naturally Exposed to Malaria Infection.

High-density peptide arrays are an excellent means to profile anti-plasmodial antibody responses. Different protein intrinsic epitopes can be distinguished, and additional insights are gained, when compared with assays involving the full-length protein. Distinct reactivities to specific epitopes within one protein may explain differences in published results, regarding immunity or susceptibility to malaria. We pursued three approaches to find specific epitopes within important plasmodial proteins, (1) twelve leading vaccine candidates were mapped as overlapping 15-mer peptides, (2) a bioinformatical approach served to predict immunogenic malaria epitopes which were subsequently validated in the assay, and (3) randomly selected peptides from the malaria proteome were screened as a control. Several peptide array replicas were prepared, employing particle-based laser printing, and were used to screen 27 serum samples from a malaria-endemic area in Burkina Faso, West Africa. The immunological status of the individuals was classified as "protected" or "unprotected" based on clinical symptoms, parasite density, and age. The vaccine candidate screening approach resulted in significant hits in all twelve proteins and allowed us (1) to verify many known immunogenic structures, (2) to map B-cell epitopes across the entire sequence of each antigen and (3) to uncover novel immunogenic epitopes. Predicting immunogenic regions in the proteome of the human malaria parasite Plasmodium falciparum, via the bioinformatics approach and subsequent array screening, confirmed known immunogenic sequences, such as in the leading malaria vaccine candidate CSP and discovered immunogenic epitopes derived from hypothetical or unknown proteins.

Rapid Response to Pandemic Threats: Immunogenic Epitope Detection of Pandemic Pathogens for Diagnostics and Vaccine Development Using Peptide Microarrays.

Emergence and re-emergence of pathogens bearing the risk of becoming a pandemic threat are on the rise. Increased travel and trade, growing population density, changes in urbanization, and climate have a critical impact on infectious disease spread. Currently, the world is confronted with the emergence of a novel coronavirus SARS-CoV-2, responsible for yet more than 800 000 deaths globally. Outbreaks caused by viruses, such as SARS-CoV-2, HIV, Ebola, influenza, and Zika, have increased over the past decade, underlining the need for a rapid development of diagnostics and vaccines. Hence, the rational identification of biomarkers for diagnostic measures on the one hand, and antigenic targets for vaccine development on the other, are of utmost importance. Peptide microarrays can display large numbers of putative target proteins translated into overlapping linear (and cyclic) peptides for a multiplexed, high-throughput antibody analysis. This enabled for example the identification of discriminant/diagnostic epitopes in Zika or influenza and mapping epitope evolution in natural infections versus vaccinations. In this review, we highlight synthesis platforms that facilitate fast and flexible generation of high-density peptide microarrays. We further outline the multifaceted applications of these peptide array platforms for the development of serological tests and vaccines to quickly encounter pandemic threats.

Proinflammatory Cytokines Perturb Mouse and Human Pancreatic Islet Circadian Rhythmicity and Induce Uncoordinated ß-Cell Clock Gene Expression via Nitric Oxide, Lysine Deacetylases, and Immunoproteasomal Activity.

Pancreatic ß-cell-specific clock knockout mice develop ß-cell oxidative-stress and failure, as well as glucose-intolerance. How inflammatory stress affects the cellular clock is under-investigated. Real-time recording of Per2:luciferase reporter activity in murine and human pancreatic islets demonstrated that the proinflammatory cytokine interleukin-1ß (IL-1ß) lengthened the circadian period. qPCR-profiling of core clock gene expression in insulin-producing cells suggested that the combination of the proinflammatory cytokines IL-1ß and interferon-γ (IFN-γ) caused pronounced but uncoordinated increases in mRNA levels of multiple core clock genes, in particular of reverse-erythroblastosis virus α (Rev-erbα), in a dose- and time-dependent manner. The REV-ERBα/ß agonist SR9009, used to mimic cytokine-mediated Rev-erbα induction, reduced constitutive and cytokine-induced brain and muscle arnt-like 1 (Bmal1) mRNA levels in INS-1 cells as expected. SR9009 induced reactive oxygen species (ROS), reduced insulin-1/2 (Ins-1/2) mRNA and accumulated- and glucose-stimulated insulin secretion, reduced cell viability, and increased apoptosis levels, reminiscent of cytokine toxicity. In contrast, low (<5,0 µM) concentrations of SR9009 increased Ins-1 mRNA and accumulated insulin-secretion without affecting INS-1 cell viability, mirroring low-concentration IL-1ß mediated ß-cell stimulation. Inhibiting nitric oxide (NO) synthesis, the lysine deacetylase HDAC3 and the immunoproteasome reduced cytokine-mediated increases in clock gene expression. In conclusion, the cytokine-combination perturbed the intrinsic clocks operative in mouse and human pancreatic islets and induced uncoordinated clock gene expression in INS-1 cells, the latter effect associated with NO, HDAC3, and immunoproteasome activity.

Effect of crystallite size on the performance and phase transformation of Co3O4/Al2O3 catalysts during CO-PrOx - an in situ study.

The preferential oxidation of carbon monoxide has been identified as an effective route to remove trace amounts of CO (approx. 0.5-1.0 vol%) in the H2-rich reformate gas stream after the low-temperature water-gas shift. Instead of noble metal-based catalysts, Co3O4-based catalysts were investigated in this study as cheaper and more readily available alternatives. This study aimed at investigating the effect of crystallite size on the mass- and surface area-specific CO oxidation activity as well as on the reduction behaviour of Co3O4. Model Co3O4 catalysts with average crystallite sizes between 3 and 15 nm were synthesised using the reverse micelle technique. Results from the catalytic tests revealed that decreasing the size of the Co3O4 crystallites increased the mass-specific CO oxidation activity in the 50-200 °C temperature range. On the other hand, the surface area-specific CO oxidation activity displayed a volcano-type behaviour where crystallites with an average size of 8.5 nm were the most active within the same temperature range. In situ characterisation in the magnetometer revealed that the Co3O4 crystallites are partially reduced to metallic Co above 225 °C with crystallites larger than 7.5 nm showing higher degrees of reduction under the H2-rich environment of CO-PrOx. In situ PXRD experiments further showed the presence of CoO concurrently with metallic fcc Co in all the catalysts during the CO-PrOx runs. In all experiments, the formation of fcc Co coincided with the formation of CH4. Upon decreasing the reaction temperature below 250 °C under the reaction gas, both in situ techniques revealed that the fcc Co previously formed is partially re-oxidised to CoO.

Size dependent stability of cobalt nanoparticles on silica under high conversion Fischer-Tropsch environment.

Highly monodisperse cobalt crystallites, supported on Stöber silica spheres, as model catalysts for the Fischer-Tropsch synthesis were exposed to simulated high conversion environments in the presence and absence of CO utilising an in house developed in situ magnetometer. The catalyst comprising the smallest crystallites in the metallic state (average diameter of 3.2 nm) experienced pronounced oxidation whilst the ratio of H2O to H2 was increased stepwise to simulate CO conversions from 26% up to complete conversion. Direct exposure of this freshly reduced catalyst to a high conversion Fischer-Tropsch environment resulted in almost spontaneous oxidation of 40% of the metallic cobalt. In contrast, a model catalyst with cobalt crystallites of 5.3 nm only oxidised to a small extent even when exposed to a simulated conversion of over 99%. The largest cobalt crystallites were rather stable and only experienced measurable oxidation when subjected to H2O in the absence of H2. This size dependency of the stability is in qualitative accordance with reported thermodynamic calculations. However, the cobalt crystallites showed an unexpected low susceptibility to oxidation, i.e. only relatively high ratios of H2O to H2 partial pressure caused oxidation. Similar experiments in the presence of CO revealed the significance of the actual Fischer-Tropsch synthesis on the metallic surface as the dissociation of CO, an elementary step in the Fischer-Tropsch mechanism, was shown to be a prerequisite for oxidation. Direct oxidation of cobalt to CoO by H2O seems to be kinetically hindered. Thus, H2O may only be capable of indirect oxidation, i.e. high concentrations prevent the removal of adsorbed oxygen species on the cobalt surface leading to oxidation. However, a spontaneous direct oxidation of cobalt at the interface between the support and the crystallites by H2O forming presumably cobalt silicate type species was observed in the presence and absence of CO. The formation of these metal-support compounds is in accordance with conducted thermodynamic predictions. None of the extreme Fischer-Tropsch conditions initiated hydrothermal sintering. Seemingly, the formation of metal-support compounds stabilised the metallic crystallites and/or higher partial pressures of CO are required to increase the concentration of mobile, cobalt oxide-type species on the metallic surface.

Size-dependent phase transformation of catalytically active nanoparticles captured in situ.

The utilization of metal nanoparticles traverses across disciplines and we continue to explore the intrinsic size-dependent properties that make them so unique. Ideal nanoparticle formulation to improve a process's efficiency is classically presented as exposing a greater surface area to volume ratio through decreasing the nanoparticle size. Although, the physiochemical characteristics of the nanoparticles, such as phase, structure, or behavior, may be influenced by the nature of the environment in which the nanoparticles are subjected1, 2 and, in some cases, could potentially lead to unwanted side effects. The degree of this influence on the particle properties can be size-dependent, which is seldom highlighted in research. Herein we reveal such an effect in an industrially valuable cobalt Fischer-Tropsch synthesis (FTS) catalyst using novel in situ characterization. We expose a direct correlation that exists between the cobalt nanoparticle's size and a phase transformation, which ultimately leads to catalyst deactivation.

Human urine: A novel source of phosphorus for vivianite production.

Human urine contributes up to 50 % of the phosphorus load in domestic wastewater. Decentralized sanitation systems that separately collect urine provide an opportunity to recover this phosphorus. In this study, we leveraged the unique and complex chemistry of urine in favor of recovering phosphorus as vivianite. We found that the type of urine affected the yield and purity of vivianite, but the kind of iron salt used, and reaction temperature, did not affect the yield and purity. Ultimately, it was the urine pH that affected the solubility of vivianite and other co-precipitates, with the highest yield (93 ± 2 %) and purity (79 ± 3 %) of vivianite obtained at pH 6.0. Yield and purity of vivianite were both maximized when Fe:P molar ratio was >1.5:1, but <2.2:1. This molar ratio provided sufficient iron to react with all available phosphorus, while exerting a competitive effect that suppressed the precipitation of other precipitates. Vivianite produced from fresh urine was less pure than vivianite produced from synthetic urine, because of the presence of organics in real urine, but washing the solids with deionized water improved the purity by 15.5 % at pH 6.0. Overall, this novel work adds to the growing body of literature on phosphorus recovery as vivianite from wastewater.