Personalized lattice-structured prosthesis as a graftless solution for mandible reconstruction and prosthetic restoration: A finite element analysis

Oral cavity tumors are a prevalent cause of mandible reconstruction surgeries. The mandible is vital for functions like oralization, respiration, mastication, and deglutition. Current mandible reconstruction methods have low success rates due to complications like plate fracture or exposure, infections, and screw loosening. Autogenous bone grafts are commonly used but carry the risk of donor region morbidity. Despite technological advances, an ideal solution for mandible reconstruction remains elusive. Additive manufacturing in medicine offers personalized prosthetics from patient-specific medical images, allowing for the creation of porous structures with tailored mechanical properties that mimic bone properties. This study compared a commercial reconstruction plate with a lattice-structured personalized prosthesis under different biting and osseointegration conditions using Finite Element Analysis. Patient-specific images were obtained from an individual who underwent mandible reconstruction with a commercial plate and suffered from plate fracture by fatigue after 26 months. Compared to the commercial plate, the maximum von Mises equivalent stress was significantly lowered for the personalized prosthesis, hindering a possible fatigue fracture. The equivalent von Mises strains found in bone were within bone maintenance and remodeling intervals. This work introduces a design that doesn't require grafts for large bone defects and allows for dental prosthesis addition without the need for implants.

Maximizing unsaturated fatty acids production by using sugarcane agroindustry wastes in cultivation of Desmodesmus sp. in a flat plate photobioreactor

Microalgae lipid accumulation can be accomplished by different strategies rather than naturally reaching the stationary phase. Many studies employ nitrogen (N) depletion to improve lipid production; however, this approach might not be a suitable alternative when growth in wastewater is attempted. Agro-industry effluents in particular can have high concentrations of N, so nutrient removal is also required. This study evaluated two possibilities of achieving stress conditions in Desmodesmus sp. cultivation: light intensity and CO₂ concentration. The culture medium also included liquid and solid residues from the sugarcane agro-industry: vinasse and a biofertilizer produced from bagasse biochar. Optimization of growth in a flat plate photobioreactor was conducted by combining a two-level factorial design and simplex methodology. Both the highest biomass and polyunsaturated fatty acid productivities (150.2 and 21.4 mg L^-1 day^-1, respectively) were achieved near the central points (5% CO₂ in air and 1000 μmol m^-2 s^-1 light intensity). These results show the possibility of microalgae growth in a sustainable medium coupled with high-value lipid production, e.g., omegas-3, - 6, and - 9.

Isopropanol-butanol-ethanol production by cell-immobilized vacuum fermentation

The Isopropanol-Butanol-Ethanol productivity by solventogenic clostridia can increase when cells are immobilized on low-cost, renewable fibrous materials; however, butanol inhibition imposes the need for dilute sugar solutions (less than40 g/L). To alleviate this problem, the in-situ vacuum product recovery technique was applied to recover IBE in repeated-batch cultivation of Clostridium beijerinckii DSM 6423 immobilized on sugarcane bagasse. Five repeated batch cycles were conducted in a 7-L bioreactor containing P2 medium (∼60 g/L glucose) and bagasse packed in 3D-printed concentric annular baskets. In three cycles, glucose was consumed by 86% on average, the IBE productivity was 0.35 g/L∙h or 30% and 17% higher relative to free- and immobilized (without vacuum)-cell cultures. Notably, the product stream contained 45 g/L IBE. However, the fermentation was unsatisfactory in two cycles. Finally, by inserting a fibrous bed with hollow annuli in a vacuum fermentation, this work introduces the concept of an internal-loop boiling-driven fibrous-bed bioreactor.

Chemical Engineering Teaching in COVID-19 Times: Successfully Adapting a Capstone Design Course to a Remote Format

The coronavirus COVID-19 pandemic required educational institutions to adapt face-to-face to remote teaching. This study reports the experience in the first semester of 2020 for a Chemical Engineering Capstone Design Course at the University of Campinas in Brazil. In this course, senior year students develop a group project, in which they simulate a chemical plant and evaluate its technoeconomic feasibility. In 2020, the groups were proposed to design a process to replace diesel fuel from the bus fleet in Campinas city with renewable fuel DME. Because of the pandemic, several adaptations were needed: the theoretical classes became asynchronous, group meetings were online, a commercial simulator was replaced by an open access one, and the schedule was extended by 2 weeks. Despite that, the students had a great performance, comparable to face-to-face. To assess student satisfaction, a questionnaire was used. The course met the expectations of most of the students who also recommended keeping it in the remote format or merging it with face-to-face teaching. Therefore, these changes made it possible to apply new teaching dynamics and tools that could be used in the future to improve the course quality.

Effects of cultivation conditions on Chlorella vulgaris and Desmodesmus sp. grown in sugarcane agro-industry residues

Large-scale microalgae cultivation is often associated with high costs, and nutrients account for a significant part. However, the use of cheaper nutrients, carbon, and water sources could reduce expenses. This study aims to produce Chlorella vulgaris and Desmodesmus sp. cultivated in sugarcane biorefinery residues bagasse and vinasse. A biofertilizer from bagasse biochar was produced and characterized, and a pre-treatment by filtration was performed on vinasse. The effects of varying growth conditions (antibiotic, vinasse, and biofertilizer concentrations; air flowrate; pH; light intensity; and photoperiod) were discussed based on the results of a Plackett-Burman design. The highest cell density was achieved by Desmodesmus sp. (46·10⁶ cells mL^-1 from an initial 6.5·10⁶ cells mL^-1) using vinasse (20%) and biofertilizer (1 g L^-1). Specific metabolite accumulation was also observed. Under stress conditions, 21.3% lipids and 51.0% carbohydrates were obtained for two different cultivations. Using 1 g L^-1 of biofertilizer, biomass composition had 74.8% proteins.

Comparative Techno-Economic and Exergetic Analysis of Circulating and Dual Bed Biomass Gasification Systems

In this work, the techno-economic and exergy analyses of two gasification technologies with integration into heat and power combined cycles are presented: i). Circulating fluidized bed (CFB) and ii). Dual fluidized bed (DFB) systems. As feedstock, lignocellulosic biomass (sugarcane bagasse, SCB) was considered. The gasification process of the fluidized-bed systems (circulating and dual bed) and the syngas conversion were performed using Aspen Plus® software. The process design includes biomass drying and gasification, syngas cleaning, combustion, power generation, and heat recovery. The SCB-DFB system has the lowest irreversibility rate and, as a result, the highest overall performance and power generation (achieving 32% in the gasification system and 53% of exergy efficiency when coupled with the combined cycle). From the techno-economic assessment, the SCB-DFB system has the lowest total production costs per unit of energy. Hence, the dual fluidized bed systems could be a more competitive technology for the agro-industrial sector to generate power from lignocellulosic materials.

Three-stage repeated-batch immobilized cell fermentation to produce butanol from non-detoxified sugarcane bagasse hemicellulose hydrolysates

To enable the production of butanol with undiluted, non-detoxified sugarcane bagasse hemicellulose hydrolysates, this study developed a three-staged repeated-batch immobilized cell fermentation in which the efficiency of a 3D-printed nylon carrier to passively immobilize Clostridium saccharoperbutylacetonicum DSM 14923 was compared with sugarcane bagasse. The first stage consisted of sugarcane molasses fermentation, and in the second stage, non-detoxified sugarcane bagasse hemicellulose hydrolysates (SBHH) was pulse-fed to sugarcane molasses fermentation. In the next four batches, immobilized cells were fed with undiluted SBHH supplemented with molasses, and SBHH-derived xylose accounted for approximately 50% of the sugars. Bagasse was a superior carrier, and the average xylose utilization (33%) was significantly higher than the treatment with the 3D-printed carrier (16%). Notably, bagasse allowed for 43% of the butanol to be SBHH-derived. Overall, cell immobilization on lignocellulosic materials can be an efficient strategy to produce butanol from repeated-batch fermentation of non-detoxified hemicellulose hydrolysates.

Sugarcane bagasse hydrolysates as feedstock to produce the isopropanol-butanol-ethanol fuel mixture: Effect of lactic acid derived from microbial contamination on Clostridium beijerinckii DSM 6423

Enzymatic hydrolysis of lignocellulose under industrial conditions is prone to contamination by lactic acid bacteria, and in this study, a cellulose hydrolysate produced from dilute-acid pretreatedsugarcane bagasse contained 13 g/L lactic acid and was used for IBE production by Clostridium beijerinckii DSM 6423. In fermentation of the cellulose hydrolysate supplemented with sugarcane molasses for nutrients and buffering of the medium (40 g/L total sugar), 92% of the lactic acid was consumed, and the butanol yield was as high as 0.28 (7.9 g/L butanol), suggesting that lactic acid was preferentially metabolized to butanol. When the hydrolysate was mixed with a detoxified bagasse hemicellulose hydrolysate and supplemented with molasses (35 g/L total sugar), the culture was able to exhaust glucose and utilized sucrose (by 38%), xylose (31%), and lactic acid (70%). Overall, this study shows that C. beijerinckii DSM 6423 can co-ferment first- and second-generation sugars while consuming lactic acid.

Separation and Semi-Empiric Modeling of Ethanol-Water Solutions by Pervaporation Using PDMS Membrane

High energy demand, competitive fuel prices and the need for environmentally friendly processes have led to the constant development of the alcohol industry. Pervaporation is seen as a separation process, with low energy consumption, which has a high potential for application in the fermentation and dehydration of ethanol. This work presents the experimental ethanol recovery by pervaporation and the semi-empirical model of partial fluxes. Total permeate fluxes between 15.6-68.6 mol m-2 h-1 (289-1565 g m-2 h-1), separation factor between 3.4-6.4 and ethanol molar fraction between 16-171 mM (4-35 wt%) were obtained using ethanol feed concentrations between 4-37 mM (1-9 wt%), temperature between 34-50 ∘C and commercial polydimethylsiloxane (PDMS) membrane. From the experimental data a semi-empirical model describing the behavior of partial-permeate fluxes was developed considering the effect of both the temperature and the composition of the feed, and the behavior of the apparent activation energy. Therefore, the model obtained shows a modified Arrhenius-type behavior that calculates with high precision the partial-permeate fluxes. Furthermore, the versatility of the model was demonstrated in process such as ethanol recovery and both ethanol and butanol dehydration.

Biochemical conversion of sugarcane bagasse into the alcohol fuel mixture of isopropanol-butanol-ethanol (IBE): Is it economically competitive with cellulosic ethanol?

This work presents a techno-economic analysis of the production of isopropanol, butanol, and ethanol (IBE) from sugarcane bagasse using clostridia and compares IBE with cellulosic ethanol for the minimum selling price (MSP) and sustainability aspects. The MSPs of the fuels are similar (15 USD/GJ) provided that glucose and xylose are effectively utilized in both processes, and the IBE process is equipped with a genetically-modified Clostridium species with enhanced IBE yield and a highly productive continuous bioreactor with integrated product recovery. Notably, these technologies can reduce the size (from 23 × 3785-m³ to 3 × 3027-m³ fermentation tanks) and the wastewater footprint (from 50 to 10 m³/m³ IBE) of the IBE plant. Furthermore, given that the production of either fuel results in a similar increase in the value created by the sugarcane biorefinery and its energy efficiency, the alcohol mixture produced by clostridia is a promising alternative to the less energy-dense ethanol fuel.

Principal Component Analysis on Recurrent Venous Thromboembolism

The rates of recurrent venous thromboembolism (RVTE) vary widely, and its causes still need to be elucidated. Statistical multivariate methods can be used to determine disease predictors and improve current methods for risk calculation. The objective of this study was to apply principal component analysis to a set of data containing clinical records of patients with previous venous thromboembolism and extract the main factors that predict recurrent thrombosis. Records of 39 factors including blood and lipid parameters, hereditary thrombophilia, antiphospholipid syndrome, clinical data regarding previous thrombosis and treatment, and Doppler ultrasound results were collected from 235 patients. The results showed that 13 principal components were associated with RVTE and that 18 of 39 factors are the important for the analysis. These factors include red blood cell, white blood cell, hematocrit, red cell distribution width, glucose, lipids, natural anticoagulant, creatinine, age, as well as first deep vein thrombosis data (distal/proximal, d-dimer, and time of anticoagulation). The results demonstrated that simple clinical parameters easy to be collected can be used to predict rates of recurrence and to develop new clinical decision support systems to predict the rates of RVTE.

A Simple Biorefinery Concept to Produce 2G-Lactic Acid from Sugar Beet Pulp (SBP): A High-Value Target Approach to Valorize a Waste Stream

Lactic acid is a high-value molecule with a vast number of applications. Its production in the biorefineries model is a possibility for this sector to aggregate value to its production chain. Thus, this investigation presents a biorefinery model based on the traditional sugar beet industry proposing an approach to produce lactic acid from a waste stream. Sugar beet is used to produce sugar and ethanol, and the remaining pulp is sent to animal feed. Using Bacillus coagulans in a continuous fermentation, 2781.01 g of lactic acid was produced from 3916.91 g of sugars from hydrolyzed sugar beet pulp, with a maximum productivity of 18.06 g L-1h-1. Without interfering in the sugar production, ethanol, or lactic acid, it is also possible to produce pectin and phenolic compounds in the biorefinery. The lactic acid produced was purified by a bipolar membrane electrodialysis and the recovery reached 788.80 g/L with 98% w/w purity.

Data-Driven Modeling of Smartphone-Based Electrochemiluminescence Sensor Data Using Artificial Intelligence

Understanding relationships among multimodal data extracted from a smartphone-based electrochemiluminescence (ECL) sensor is crucial for the development of low-cost point-of-care diagnostic devices. In this work, artificial intelligence (AI) algorithms such as random forest (RF) and feedforward neural network (FNN) are used to quantitatively investigate the relationships between the concentration of Ru(bpy)32+ luminophore and its experimentally measured ECL and electrochemical data. A smartphone-based ECL sensor with Ru(bpy)32+/TPrA was developed using disposable screen-printed carbon electrodes. ECL images and amperograms were simultaneously obtained following 1.2-V voltage application. These multimodal data were analyzed by RF and FNN algorithms, which allowed the prediction of Ru(bpy)32+ concentration using multiple key features. High correlation (0.99 and 0.96 for RF and FNN, respectively) between actual and predicted values was achieved in the detection range between 0.02 µM and 2.5 µM. The AI approaches using RF and FNN were capable of directly inferring the concentration of Ru(bpy)32+ using easily observable key features. The results demonstrate that data-driven AI algorithms are effective in analyzing the multimodal ECL sensor data. Therefore, these AI algorithms can be an essential part of the modeling arsenal with successful application in ECL sensor data modeling.

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.

Acetone-free biobutanol production: Past and recent advances in the Isopropanol-Butanol-Ethanol (IBE) fermentation

Production of butanol for fuel via the conventional Acetone-Butanol-Ethanol fermentation has been considered economically risky because of a potential oversupply of acetone. Alternatively, acetone is converted into isopropanol by specific solventogenic Clostridium species in the Isopropanol-Butanol-Ethanol (IBE) fermentation. This route, although less efficient, has been gaining attention because IBE mixtures are a potential fuel. The present work is dedicated to reviewing past and recent advances in microorganisms, feedstock, and fermentation equipment for IBE production. In our analysis we demonstrate the importance of novel engineered IBE-producing Clostridium strains and cell retention systems to decrease the staggering number of fermentation tanks required by IBE plants equipped with conventional technology. We also summarize the recent progress on recovery techniques integrated with fermentation, especially gas stripping. In addition, we assessed ongoing pilot-plant efforts that have been enabling IBE production from woody feedstock.

Dynamic modeling of syngas fermentation in a continuous stirred-tank reactor: Multi-response parameter estimation and process optimization

Syngas fermentation is one of the bets for the future sustainable biobased economies due to its potential as an intermediate step in the conversion of waste carbon to ethanol fuel and other chemicals. Integrated with gasification and suitable downstream processing, it may constitute an efficient and competitive route for the valorization of various waste materials, especially if systems engineering principles are employed targeting process optimization. In this study, a dynamic multi‐response model is presented for syngas fermentation with acetogenic bacteria in a continuous stirred‐tank reactor, accounting for gas–liquid mass transfer, substrate (CO, H₂) uptake, biomass growth and death, acetic acid reassimilation, and product selectivity. The unknown parameters were estimated from literature data using the maximum likelihood principle with a multi‐response nonlinear modeling framework and metaheuristic optimization, and model adequacy was verified with statistical analysis via generation of confidence intervals as well as parameter significance tests. The model was then used to study the effects of process conditions (gas composition, dilution rate, gas flow rates, and cell recycle) as well as the sensitivity of kinetic parameters, and multiobjective genetic algorithm was used to maximize ethanol productivity and CO conversion. It was observed that these two objectives were clearly conflicting when CO‐rich gas was used, but increasing the content of H₂ favored higher productivities while maintaining 100% CO conversion. The maximum productivity predicted with full conversion was 2 g·L⁻¹·hr⁻¹ with a feed gas composition of 54% CO and 46% H₂ and a dilution rate of 0.06 hr⁻¹ with roughly 90% of cell recycle.

Cardiac tissue engineering: current state-of-the-art materials, cells and tissue formation

Cardiovascular diseases are the major cause of death worldwide. The heart has limited capacity of regeneration, therefore, transplantation is the only solution in some cases despite presenting many disadvantages. Tissue engineering has been considered the ideal strategy for regenerative medicine in cardiology. It is an interdisciplinary field combining many techniques that aim to maintain, regenerate or replace a tissue or organ. The main approach of cardiac tissue engineering is to create cardiac grafts, either whole heart substitutes or tissues that can be efficiently implanted in the organism, regenerating the tissue and giving rise to a fully functional heart, without causing side effects, such as immunogenicity. In this review, we systematically present and compare the techniques that have drawn the most attention in this field and that generally have focused on four important issues: the scaffold material selection, the scaffold material production, cellular selection and in vitro cell culture. Many studies used several techniques that are herein presented, including biopolymers, decellularization and bioreactors, and made significant advances, either seeking a graft or an entire bioartificial heart. However, much work remains to better understand and improve existing techniques, to develop robust, efficient and efficacious methods.

Process design and economics of a flexible ethanol-butanol plant annexed to a eucalyptus kraft pulp mill

This work proposes a strategy, from a process design standpoint, for pulp companies to enter the Brazilian ethanol market. The flexible plant converts eucalyptus-derived glucose to either ethanol or butanol (according to market conditions) and xylose only to butanol production. Depending on the biomass pretreatment technology, Monte Carlo simulations showed that the Net Present Value (NPV) of the flexible plant increases by 20-28% in relation to an ethanol-dedicated plant. Whereas the lower costs of the steam explosion technology turns the investment more attractive (NPV = 184 MMUSD; IRR = 29%), the organosolv technology provides better flexibility to the plant. This work also shows that excessive power consumption is a hurdle in the development of flash fermentation technology chosen for the flexible plant. These results indicate that conventional batch fermentation is preferable if the enzymatic hydrolysis step operates with solids loading up to 20 wt%.

Influence of sugarcane bagasse variability on sugar recovery for cellulosic ethanol production

In the context of cellulosic ethanol production, special attention must be given to the raw material, as it affects final product yield. As observed for sugarcane, bagasse variations may derive from several elements, for instance edaphoclimatic factors, seasonality, maturation stage and harvesting techniques. Therefore, in the present work, to investigate the impact of raw material characteristics on process performance, sugarcane bagasse from four harvests from October/2010 to October/2011 was pretreated by steam explosion and had its soluble and insoluble solids contents measured, following enzymatic hydrolysis to assess glucan conversion. As confirmed by ANOVA, glucose concentration was related to the solids content in the reactor, whereas glucan conversion was related to the enzymatic load. Variations in raw material composition were indeed observed to significantly interfere in the final sugar recovery, probably due to the increase in the impurities observed as a result of the type of harvest performed in 2011.

Electrospun polyurethane membranes for Tissue Engineering applications

Tissue Engineering proposes, among other things, tissue regeneration using scaffolds integrated with biological molecules, growth factors or cells for such regeneration. In this research, polyurethane membranes were prepared using the electrospinning technique in order to obtain membranes to be applied in Tissue Engineering, such as epithelial, drug delivery or cardiac applications. The influence of fibers on the structure and morphology of the membranes was studied using scanning electron microscopy (SEM), the structure was evaluated by Fourier transform infrared spectroscopy (FT-IR), and the thermal stability was analyzed by thermogravimetry analysis (TGA). In vitro cells attachment and proliferation was investigated by SEM, and in vitro cell viability was studied by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays and Live/Dead® assays. It was found that the membranes present an homogeneous morphology, high porosity, high surface area/volume ratio, it was also observed a random fiber network. The thermal analysis showed that the membrane degradation started at 254°C. In vitro evaluation of fibroblasts cells showed that fibroblasts spread over the membrane surface after 24, 48 and 72h of culture. This study supports the investigation of electrospun polyurethane membranes as biocompatible scaffolds for Tissue Engineering applications and provides some guidelines for improved biomaterials with desired properties.

Bio-based polyurethane for tissue engineering applications: How hydroxyapatite nanoparticles influence the structure, thermal and biological behavior of polyurethane composites

In this work, thermoset polyurethane composites were prepared by the addition of hydroxyapatite nanoparticles using the reactants polyol polyether and an aliphatic diisocyanate. The polyol employed in this study was extracted from the Euterpe oleracea Mart. seeds from the Amazon Region of Brazil. The influence of hydroxyapatite nanoparticles on the structure and morphology of the composites was studied using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), the structure was evaluated by Fourier transform infrared spectroscopy (FT-IR), thermal properties were analyzed by thermogravimetry analysis (TGA), and biological properties were studied by in vitro and in vivo studies. It was found that the addition of HA nanoparticles promoted fibroblast adhesion while in vivo investigations with histology confirmed that the composites promoted connective tissue adherence and did not induce inflammation. In this manner, this study supports the further investigation of bio-based, polyurethane/hydroxyapatite composites as biocompatible scaffolds for numerous tissue engineering applications.