The APMO-MOLPRO interface: Highly correlated electronic structure calculations with the inclusion of quantum nuclear effects at Hartree-Fock level

A computational interface between the MOLPRO [1] electronic structure package and the AMPO [2] code is presented here. The AMPO code is an implementation of the nuclear and molecular orbital approach [3,4,5] in which electrons and light nuclei of molecular systems are described simultaneously with molecular orbitals at Hartree-Fock and second-order Möller-Pleset levels of theory. The APMO-MOLPRO interface extends the applicability of the APMO code by allowing to correlate the electronic structure part at higher levels of ab-initio theory and to describe the nuclear response to electronic correlation effects. Some applications are presented to illustrate the advantages of this approach over standard electronic structure treatments.Peer Reviewe

Fabrication and upconversion luminescence of Er3+/Yb 3+ codoped TeO2-WO3-Na2O-Nb 2O5-Al2O3 glass fibers

The tellurite fibers based on glasses with the composition TeO 2-WO3-Nb2O5-Na2O-Al 2O3-Er2O3-Yb2O 3 were fabricated by the rod-in-tube technique using a Heathway drawing tower. The upconversion luminescence of Er3+/Yb3+ codoped tellurite glass fibers under 980 nm excitation were investigated. The Er3+/Yb3+co-doped tellurite fibers show an efficient up-conversion process in comparison with the Er3+-doped tellurite fibers. The pump power dependent intensities were discussed, which showed that two photons are involved in the upconversion process. © 2012 Elsevier B.V. All rights reserved

Fabricación y caracterización de fibras ópt icas convencionales de telurito co-dopadas con Er3+ /Yb3+

En este trabajo se presenta la fabricación y caracterización de fibras ópticas convencionales de telurito (FCTs). Las fibras ópticas se fabricaron utilizando el sistema vítreo TeO2-WO3-Nb2O5-Na2O + Al2O3. El núcleo de las fibras ópticas fue dopado con altas concentraciones de iones de Er3+ o co-dopado con iones de Er3+ e Yb3+. Para realizar las medidas de luminiscencia se utilizó como fuente de bombeo óptico un láser diodo que emite en 980 nm. Los resultados de luminiscencia en las FCTs, revelan que las FCTs co-dopadas con Er3+/Yb3+ producen una emisión más intensa y eficiente tanto en la región visible como en el infrarrojo cercano en comparación con las fibras de telurito dopadas solamente con iones de Er3+

Decarbonizing ethanol production via gas fermentation: Impact of the CO/H₂/CO₂ mix source on greenhouse gas emissions and production costs

This study explores key success factors for ethanol production via fermentation of gas streams, by assessing the effects of eight process variables driving the fermentation performance on the production costs and greenhouse gas emissions. Three fermentation feedstocks are assessed: off-gases from the steel industry, lignocellulosic biomass-derived syngas and a mixture of H2 and CO2. The analysis is done through a sequence of (i) sensitivity analyses based on stochastic simulations and (ii) multi-objective optimizations. In economic terms, the use of steel off-gas leads to the best performance and the highest robustness to low mass transfer coefficients, low microbial tolerance to ethanol, acetic-acid co-production and to dilution of the gas feed with CO2, due to the relatively high temperature at which the gas feedstock is available. The ethanol produced from the three feedstocks lead to lower greenhouse gas emissions than fossil-based gasoline and compete with first and second generation ethanol.BT/Biotechnology and SocietyBT/Bioprocess Engineerin

A systematic approach for the processing of experimental data from anaerobic syngas fermentations

This study describes a methodological framework designed for the systematic processing of experimental syngas fermentation data for its use by metabolic models at pseudo-steady state and at transient state. The developed approach allows the use of not only own experimental data but also from experiments reported in literature which employ a wide range of gas feed compositions (from pure CO to a mixture between H2 and CO2), different pH values, two different bacterial strains and bioreactor configurations (stirred tanks and bubble columns). The developed data processing framework includes i) the smoothing of time-dependent concentrations data (using moving averages and statistical methods that reduce the relevance of outliers), ii) the reconciliation of net conversion rates such that mass balances are satisfied from a black-box perspective (using minimizations), and iii) the estimation of dissolved concentrations of the syngas components (CO, H2 and CO2) in the fermentation broth (using mass transfer models). Special care has been given such that the framework allows the estimation of missing or unreported net conversion data and metabolite concentrations at the intra or extracellular spaces (considering that there is availability of at least two replicate experiments) through the use of approximative kinetic equations.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.BT/Bioprocess EngineeringBT/Biotechnology and Societ

Modeling ethanol production through gas fermentation: A biothermodynamics and mass transfer-based hybrid model for microbial growth in a large-scale bubble column bioreactor

Background: Ethanol production through fermentation of gas mixtures containing CO, CO2 and H2 has just started operating at commercial scale. However, quantitative schemes for understanding and predicting productivities, yields, mass transfer rates, gas flow profiles and detailed energy requirements have been lacking in literature; such are invaluable tools for process improvements and better systems design. The present study describes the construction of a hybrid model for simulating ethanol production inside a 700 m3 bubble column bioreactor fed with gas of two possible compositions, i.e., pure CO and a 3:1 mixture of H2 and CO2. Results: Estimations made using the thermodynamics-based black-box model of microbial reactions on substrate threshold concentrations, biomass yields, as well as CO and H2 maximum specific uptake rates agreed reasonably well with data and observations reported in literature. According to the bioreactor simulation, there is a strong dependency of process performance on mass transfer rates. When mass transfer coefficients were estimated using a model developed from oxygen transfer to water, ethanol productivity reached 5.1 g L-1 h-1; when the H2/CO2 mixture is fed to the bioreactor, productivity of CO fermentation was 19% lower. Gas utilization reached 23 and 17% for H2/CO2 and CO fermentations, respectively. If mass transfer coefficients were 100% higher than those estimated, ethanol productivity and gas utilization may reach 9.4 g L-1 h-1 and 38% when feeding the H2/CO2 mixture at the same process conditions. The largest energetic requirements for a complete manufacturing plant were identified for gas compression and ethanol distillation, being higher for CO fermentation due to the production of CO2. Conclusions: The thermodynamics-based black-box model of microbial reactions may be used to quantitatively assess and consolidate the diversity of reported data on CO, CO2 and H2 threshold concentrations, biomass yields, maximum substrate uptake rates, and half-saturation constants for CO and H2 for syngas fermentations by acetogenic bacteria. The maximization of ethanol productivity in the bioreactor may come with a cost: low gas utilization. Exploiting the model flexibility, multi-objective optimizations of bioreactor performance might reveal how process conditions and configurations could be adjusted to guide further process development.BT/Biotechnology and SocietyBT/Bioprocess Engineerin

The apmo-molpro interface: highly correlated electronic structure calculations with the inclusion of quantum nuclear effects at hartree-fock level

International Meeting on Atomic and Molecular Physics and Chemistry, Scuola Normale Superiore Pisa, Italy, 12-14 September 2012Peer Reviewe

Negative emissions at negative cost-an opportunity for a scalable niche

In the face of the rapidly dwindling carbon budgets, negative emission technologies are widely suggested as required to stabilize the Earth’s climate. However, finding cost-effective, socially acceptable, and politically achievable means to enable such technologies remains a challenge. We propose solutions based on negative emission technologies to facilitate wealth creation for the stakeholders while helping to mitigate climate change. This paper comes up with suggestions and guidelines on significantly increasing carbon sequestration in coffee farms. A coffee and jackfruit agroforestry-based case study is presented along with an array of technical interventions, having a special focus on bioenergy and biochar, potentially leading to “negative emissions at negative cost.” The strategies for integrating food production with soil and water management, fuel production, adoption of renewable energy systems and timber management are outlined. The emphasis is on combining biological and engineering sciences to devise a practically viable niche that is easy to adopt, adapt and scale up for the communities and regions to achieve net negative emissions. The concerns expressed in the recent literature on the implementation of emission reduction and negative emission technologies are briefly presented. The novel opportunities to alleviate these concerns arising from our proposed interventions are then pointed out. Our analysis indicates that 1 ha coffee jackfruit-based agroforestry can additionally sequester around 10 tonnes of CO2-eq and lead to an income enhancement of up to 3,000–4,000 Euros in comparison to unshaded coffee. Finally, the global outlook for an easily adoptable nature-based approach is presented, suggesting an opportunity to implement revenue-generating negative emission technologies on a gigatonne scale. We anticipate that our approach presented in the paper results in increased attention to the development of practically viable science and technology-based interventions in order to support the speeding up of climate change mitigation efforts