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The advent of additive manufacturing has been a disruptive technology in various fields, including medicine. One of the main causes of orthopedic implant failure is the mismatch between the implant material and the bone, causing bone resorption and aseptic loosening. In this regard, the use of additively manufactured lattice structures as orthopedic implant material has several advantages, such as producing a material with an adequate stiffness match with bone. Nevertheless, its behavior in service is not fully understood: the human body is a complex environment, and an orthopedic implant material is subjected to corrosion, wear, and tribocorrosion. In this work, Ti-6Al-4V solid and lattice structured samples were designed with pore sizes of 500, 700, and 900 µm and produced by PBF-EB. Microstructural and geometrical characterization was made on produced samples. The effect of pore sizes was analyzed under corrosion, wear, and tribocorrosion conditions, and compared with solid bulk samples. During corrosion tests, porous samples presented pitting attacks at high potentials, as the solid samples did not. The porous and solid samples presented similar behaviors under wear and tribocorrosion, with abrasive and adhesive wear as the predominant mechanism, and no statistical difference in the specific wear rates was found.

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 Society, BT/Bioprocess Engineering

Ti–6Al–4V ELI scaffolds produced by additive manufacturing and functionalized by anodizing technique in two different conditions have been evaluated using scanning electron microscopy, energy-dispersive X-ray spectroscopy, optical confocal microscopy, cyclic potentiodynamic polarization curves (CPP), and electrochemical impedance spectroscopy (EIS). Despite the differences in composition and morphological features between the anodic layers grown, the results revealed an improvement of the corrosion resistance in both anodized conditions regarding non-anodized samples. The non-anodized scaffolds presented pitting corrosion in phosphate-buffered saline solution at 37 °C. Conversely, the anodized samples prevented pitting corrosion and enhanced barrier properties by decreasing the passive current density in two orders of magnitude. EIS data show, anodized scaffolds presented good stability after 168 h of immersion time and better protective properties than non-anodized samples.

Exergy and environmental analyses have been developed to determine the performance of the electricity generation in the Dutch mix. A comparative assessment of diverse technological routes, including fossil and renewable energy resources consumption, is carried out in terms of the exergy costs and specific CO2 emissions. Hence, an exergoeconomy methodology is used to properly allocate the renewable and non-renewable exergy costs and specific CO2 emissions among the various products of the polygeneration energy systems. By using a suitable methodology, the distribution of irreversibility throughout the different steps of the energy conversion processes of the Dutch electricity mix is characterized in the light of the Second Law of Thermodynamics. The results may help to propose performance indicators that support the Dutch government and research institutions. To identify sustainable energy planning strategies and fairly comparing electricity generation and end-use processing stages with other types of energy resources, such as fuels used in transportation, residential and industrial sectors. In brief, the weighted average of the renewable and non-renewable unit exergy costs and the specific CO2 emissions of the electricity generated in each route of the Dutch mix is calculated and compared to another electricity mix with a higher share of renewable energy resources. The weighted average renewable and non-renewable unit exergy costs of the electricity generated in the Netherlands are calculated as cR = 0.8375 kJ/kJE/W and cNR = 1.7180 kJ/kJE/W, respectively (cR/cNR= 0.49). Furthermore, the specific CO2 emissions in the Dutch electricity generation achieve 373.21 gCO2/kWhE/W., BT/Biotechnology and Society

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 mode, BT/Biotechnology and Society, BT/Bioprocess Engineering

In this work, a model was developed to predict the performance of a bubble column reactor for syngas fermentation and the subsequent recovery of anhydrous ethanol. The model was embedded in an optimization framework which employs surrogate models (artificial neural networks) and multi-objective genetic algorithm to optimize different process conditions and design variables with objectives related to investment, minimum selling price, energy efficiency and bioreactor productivity. The results indicate the optimal trade-offs between these objectives while providing a range of solutions such that, if desired, a single solution can be picked, depending on the priority conferred to different process targets. The Pareto-optimal values of the decision variables were discussed for different case studies with and without the recovery unit. It was shown that enhancing the gas-liquid mass transfer coefficient is a key strategy toward sustainability improvement., BT/Bioprocess Engineering, BT/Biotechnology and Society

In this work, the effects of various operating parameters of the two-stage yeast treatment on the VHG fermentation performance were evaluated. First, a central composite design was used to investigate the effects of temperature and pH on cell viability and flocculation dispersion in the acid treatment unit (1st stage). Second, the effects of temperature, oxidation-reduction potential (ORP) and sugar concentration in the yeast reactivation (2nd stage) on the performance parameters (productivity, ethanol yield and cell viability) of the VHG fermentation were evaluated through a full factorial design. The results indicated that the acid treatment around 2.65 pH and temperature controlled at 30 °C for 30 min led to higher cell viability. The conditions of yeast reactivation stage that positively influenced the VHG fermentation performance were relatively low temperature and negative ORP. A mechanistic model quantitatively revealed the influence of the operating parameters studied on cell growth kinetics. The two-stage yeast treatment promoted the increase in cell viability through the cell membrane recovery, which led to the maintenance or improvement the VHG fermentation performance.