The transplantation of retinal pigment epithelial (RPE) cells derived from human iPS cells has been shown its effectiveness to age-related macular degeneration. However, the process of RPE ...differentiation takes a few months, and it could make inconsistent between batches. The combination of Yes-associated protein signaling activity which modulates ectodermal differentiation by cell density-dependent and variation in cell density in a vessel from operation might lead to this inconsistency. Therefore, we hypothesized the seeding operation that determines the position of each cell on a culture vessel plays an important role through RPE differentiation.
In this research, we aim to stabilize the early phase of RPE differentiation derived from human iPS cells by mechanization of seeding operation.
Human iPS cells (201B7 line) were seeded manually and mechanically on iMatrix-511-coated culture vessels and incubated with differentiation induction medium. At t = 24 h after seeding, two indices of spatial heterogeneity of cell density (local and global heterogeneity) were calculated by using nuclear stained images. In brief, local and global heterogeneity indicate the variation within each locality and the variation overall a culture vessel, respectively. The cells were collected on day 7 of differentiation and analyzed by flow cytometry to evaluate the ratio of neural ectoderm (Target lineage) and epidermal ectoderm (Non-target lineage).
Based on spatial heterogeneity analysis, variation of global heterogeneity in machinery operation was lower than in manual operation. Then, the mean value of local heterogeneity in machinery operation was higher than in manual operation. Based on flow cytometric analysis, variation of the ratio of neural ectoderm and epidermal ectoderm in machinery operation was lower than manual operation. Moreover, the yield of neural ectoderm was improved by mechanization. It was suggested that the control of spatial heterogeneity by mechanization stabilized the early phase of RPE differentiation.
In conclusion, we demonstrated that stabilization of the early phase of RPE differentiation derived from human iPS cells by mechanization of seeding operation.
In the framework of the energy shift toward Renewable Energy Sources, ammonia is considered a valuable energy vector, due to its very high hydrogen-density and well-established production processes. ...Despite the many potential advantages, its combustion features (narrow flammability limits, high auto-ignition temperature, potential high fuel-NOx emissions) may hinder its wide utilization. To overcome these issues in conventional combustion, “fuel enhancers” are also used. Differently from conventional systems, MILD Combustion already proved to be very effective in oxidizing ammonia in terms of stability and NOx emission. Nevertheless, a “fuel enhancer” can be also useful in MILD Combustion conditions to further improve the process characteristics. The present study focuses on the ammonia/methane combustion characteristics under MILD Combustion conditions in a lab-scale burner. Gaseous pollutant emissions (NOx, NH3, H2, CO) and process stability limits were analysed as a function of the equivalence ratio and NH3/CH4 fuel composition. Results showed that the use of NH3/CH4 blends extends the stable operational range of the system, in terms of both working temperatures and equivalence ratios, with respect to pure NH3. On the other hand, blends produce higher NOx emissions, with respect to both the pure NH3 and CH4 cases. Experimental data were compared with chemical kinetics modelling results. Chemical pathways and rate of production of main intermediate products highlighted that oxidation pathways of carbon and nitrogen-based species are essentially decoupled as experiments suggested. In contrast, the interplay of the methane and ammonia main chemical pathways affects the DeNOx channel in correspondence of the observed NOx emission increase.
The use of stability lobe diagrams in milling is an established tool which is based on the compliance of the production system. Impact hammer tests can be performed to measure this compliance, ...usually at the tip of the non-rotating tool. In this contribution, a systematic characterization of the dynamic compliance is conducted considering the spindle speed-specific influence of a rotating tool on the modal parameters. To account for this, the resulting data was analyzed to allow for a spindle speed-dependent interpolation of these parameter values, which was used for the simulation-based prediction of stability lobe diagrams.
Wire + arc additive manufacturing (WAAM) with cold metal transfer (CMT) process can reduce cost and lead time during the production of large-scale Ni-based components used in the transportation and ...energy sector. This paper investigates the effects of processing parameters and heat treatments employed on CMT-WAAM of a precipitation hardenable Ni-based alloy – Inconel 718. The process stability was analysed by electrical transients and melt pool imaging, showing an opposite trend to the measured heat inputs. A 1.2 mm diameter wire permitted deposition widths of 5.92–13.15 mm, but widths larger than ~10 mm decreased the arc stability considerably. Laves length and carbide diameter decreased with travel speed, while the as-deposited hardness increased. These observations permitted a linear wall to be fabricated with a minimal heat input per layer of 181–185 J/mm. An increase in the solution treatment temperature from 980 to 1040 °C reduced microsegregation, Laves and δ phase precipitation. Localised regions with high microhardness were found near interlayer regions due to a local dissolution of Nb-rich eutectic phases. Compared to powder-based additive manufacturing, CMT-WAAM IN718 exhibits a larger melt pool size and lower as-deposited hardness, but has been found to show satisfactory ageing response and similar Laves phase area fraction.
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•Effects of processing parameters and heat treatments were investigated on Inconel 718 produced by wire + arc additive manufacturing.•Arc voltage signals and melt pool imaging were used to characterise the metal transfer and improve the process stability.•Average Laves length of 1.68–2.60 μm and NbC carbides diameter of 0.59–0.90 μm were measured by microstructural analysis.•Localised regions with high microhardness were found near interlayer regions after precipitation heat treatment.•An increase in the solution treatment temperature from 980 to 1040 °C reduced microsegregation, Laves and δ phase considerably.
Anaerobic digestion (AD) is an established organic waste management technology, producing biogas and organic fertiliser as end-products. Despite being an established technology, AD still faces key ...challenges, including process inefficiencies due to substrate-induced instability and product quality assurance; inability to digest highly lignocellulosic biomass without pre-treatment; and management of effluents and emissions. Commercial grade carbon-based materials have been employed as stabilising agent to improve process efficiency. Biochar, a by-product from biomass pyrolysis, has recently been identified as a sustainable alternative material to commercial grade carbon-based adsorbent used in AD. This review highlights the challenges with the AD process and the limitations of the various conventional approaches in its management. An exposition of the characteristics of biochar and the physico-chemical properties of biochar, that can simultaneously promote AD process stability, increase biomethane yield rate and the agronomic quality of digestate, are presented and discussed.
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•Some challenges persist with anaerobic digestion despite being a matured technology.•Conventional methods for managing the challenges has their limitations.•Biochar as an alternative can potentially improves performance of anaerobic digestion.•Biochar can promote digester stability and methane concentration in biogas.•Biochar can improve digestate agronomic properties and reduce GHG emissions.
•First combined chemical, microbial and thermodynamic study on AD process stability.•The effects of organic overload on the thermodynamics of VFAs were investigated.•Selection of equations for ...thermodynamic calculation depends on microbial analysis.•Thermodynamic disadvantage was more pronounced under high organic loadings.•The potential of changes in Gibbs free energy to identify process status was discussed.
Anaerobic digestion (AD) operating under organic overload stress usually increases the potential for process instability, leading to significant economic and ecological consequences. Volatile fatty acids (VFAs) accumulation is regularly considered a major factor during AD and their degradation is subject to thermodynamic constraints. To date, no study has systematically investigated the mechanisms of VFA degradation on process stability from the perspective of thermodynamics. Hence, increased substrate-to-inoculum ratio was applied in this study to simulate organic overload stress using batch tests with Hybrid Pennisetum. As a result, VFAs accumulation increased, accompanied by decreased methane yield, slower methane production kinetics and even severe process instability. Metagenomic analysis demonstrated that the accumulated propionate and butyrate were degraded by methyl-malonyl-CoA and the β-oxidation pathway while syntrophic acetate oxidation was preferred during acetate degradation. The deviation of stability parameters to varying degrees from the recommended threshold values was observed. However, a subsequent thermodynamic analysis revealed that moderate organic overload stress merely retarded the syntrophic oxidation of propionate, butyrate, and acetate. As a result, the methanogenic activity decreased, and the lag phase of AD was extended, but no adverse thermodynamic effects actually occurred. Changes in the Gibbs free energy for syntrophic propionate and acetate oxidation have the potential to better identify process stability. This study provided novel insights into the underlying thermodynamic mechanisms of VFA degradation and may have important implications for improving the current diagnostic mode for AD process stability.
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•MnFe2O4-biochar enhanced the performance and stability of the AD of SS.•MnFe2O4-biochar addition led to 55.86% increase in cumulative methane yield.•MnFe2O4-biochar enhanced ...digestion performance via help establishing DIET.•MnFe2O4-biochar was helpful for immobilization and risk reduction of HMs in SS.•MnFe2O4-biochar treatment enhanced acetoclastic methanogenesis pathway.
This study investigated the effects of MnFe2O4-biochar on sludge anaerobic digestion performance, methane production and heavy metal stabilization. The highest cumulative methane yield was achieved when the MnFe2O4-biochar dose was 1.50 g, which was 55.86% higher than control. A suitable dose of MnFe2O4-biochar stimulated methanogenic activities and improved methane yield, whereas excessive addition shows an inhibitory effect on anaerobic digestion. MnFe2O4-biochar addition significantly enhanced the biodegradation of organic matter, as the average volatile fatty acids degradation rate increased by 35.44%, compared to the control. Chemical speciation analyses demonstrated that MnFe2O4-biochar addition was more helpful for immobilization and risk reduction of heavy metals in sewage sludge. Simultaneously, microbial community analysis indicated that MnFe2O4-biochar obviously enriched acetoclastic methanogens Methanosarcina that capable of participating in direct interspecies electron transfer, which could accelerate substrate decomposition and methane production. These findings supply useful information for the resource utilization of sewage sludge.
•AD is a well-established technology for FW management.•Performance instability is a common operational issue for AD of FW.•Methods for improving the stability of anaerobic digesters are ...reviewed.•Process monitoring and control are suitable for evaluating digester operation.•Microbial management facilitates early diagnosis and optimization of digesters.
Food waste (FW) is rich in biomass energy, and increasing numbers of national programs are being established to recover energy from FW using anaerobic digestion (AD). However process instability is a common operational issue for AD of FW. Process monitoring and control as well as microbial management can be used to control instability and increase the energy conversion efficiency of anaerobic digesters. Here, we review research progress related to these methods and identify existing limitations to efficient AD; recommendations for future research are also discussed. Process monitoring and control are suitable for evaluating the current operational status of digesters, whereas microbial management can facilitate early diagnosis and process optimization. Optimizing and combining these two methods are necessary to improve AD efficiency.
Despite having been widely investigated, dark fermentative H2 production from organic residues is still limited by process-related issues which may hamper the perspectives of full-scale process ...implementation. Such constraints are mainly due to the process complexity, which is largely affected by multiple and often mutually interacting factors. In the present work, the results of continuous fermentative H2 production experiments using synthetic cheese whey as the input substrate were used to gain detailed knowledge of the process features and identify suitable and critical operating conditions. Specifically, innovative process interpretation involved a combination of analytical characterization of the fermentation broth, mass balance calculations and statistical methods (correlation and principal component analyses) to derive systematic considerations for process characterization and scale-up. The metabolic products mainly included acetate and butyrate, which however were likely to derive (in different proportions depending on the operating conditions) from both hydrogenogenic and competing pathways. For some tests, lactate and succinate were also found to have been formed. It was observed that the main features of the process (H2 yield and rate, stability condition) were correlated with the operational and analytical parameters. The first three principal components identified by the statistical analysis were able to account for: 1) the effect of retention time and total metabolites produced; 2) biogas (H2 and CO2) generation, butyrate production and stability condition; and 3) organic loading rate and propionate production. The results suggested that the main features of hydrogenogenic fermentation can be described by a reduced set of factors that may be usefully adopted for both process monitoring and prediction purposes.
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•Both hydrogenogenic and competing pathways were observed during fermentation.•Hydraulic control proved successful to enhance H2 production in view of scale-up.•Homoacetogenesis was promoted by either low HRTs or high OLRs.•PCA identified a reduced set of factors that explained the main process features.•Chemometric analyses can assist both process monitoring and performance prediction.
Partial nitritation/anammox (PN/A) has been one of the most innovative developments in biological wastewater treatment in recent years. With its discovery in the 1990s a completely new way of ...ammonium removal from wastewater became available. Over the past decade many technologies have been developed and studied for their applicability to the PN/A concept and several have made it into full-scale. With the perspective of reaching 100 full-scale installations in operation worldwide by 2014 this work presents a summary of PN/A technologies that have been successfully developed, implemented and optimized for high-strength ammonium wastewaters with low C:N ratios and elevated temperatures. The data revealed that more than 50% of all PN/A installations are sequencing batch reactors, 88% of all plants being operated as single-stage systems, and 75% for sidestream treatment of municipal wastewater. Additionally an in-depth survey of 14 full-scale installations was conducted to evaluate practical experiences and report on operational control and troubleshooting. Incoming solids, aeration control and nitrate built up were revealed as the main operational difficulties. The information provided gives a unique/new perspective throughout all the major technologies and discusses the remaining obstacles.
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•More than 100 full-scale partial nitritation/anammox installations worldwide by 2014.•In depth survey of 14 full-scale installations.•Discussion of practical experiences, process control and troubleshooting.
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