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Urea production: An absolute environmental sustainability assessment
No full textThe demand for urea, as the most popular global nitrogen fertilizer, is on the rise and as such, its performance in an environmentally sustainable perspective relative to planetary boundaries is high on the agenda. The increasing interest in nitrogen fertilizers is to improve agricultural methods for a better production rate, but can it become environmentally sustainable? Which is due to the significant contribution of fertilizers in the anthropogenic impacts of industrial activities on nature, should be considered. Here, a system analysis based on real data using life cycle assessment linked to the planetary boundaries framework (PB-LCIA) was conducted to study the performance of total urea consumption in Iran, 1.8E+6 metric tons per year. In LCA, midpoint and endpoint methods (ReCiPe 2016) and for AESA, a PB-LCIA methodology was utilized. Results showed that global warming potential, freshwater eutrophication, and marine eutrophication contribute 1.37E+09 kg CO2 eq, 1.63E+04 kg P eq, and 1.28E+04 kg N eq, respectively, while the GHG emissions of combustion, electricity, and natural gas sweetening have the most contribution to global warming by 35, 24 & 15 %, respectively. Regarding absolute sustainability, global warming, ocean acidification, and biochemical N exceed this activity's assigned share of safe operating space (SoSOS). However, choosing different sharing principles can influence to what extent this activity exceeds or stays within the assigned SoSOS; accordingly, the Nitrogen Biogeochemical flows depend on the sharing principle. Ultimately, the total Iranian urea consumption as fertilizer is not absolutely sustainable. The promising point is that producing sustainable electricity and feedstocks could lead to more sustainable urea fertilizers
Pore-existing phosphor-in-glass film realizing ultra-efficient and uniform laser lighting
No full textThe development of phosphor-converted laser lighting has encountered a significant problem: the difficulty of homogeneously mixing the laser light with the luminescent light. Previous studies reveal that enhancing the scattering of the phosphor can improve color mixing but often sacrifices luminous efficacy and limits the peak luminance. To address this, a pore-existing YAG:Ce-based phosphor-in-glass film is prepared using the screen-printing technique. Interestingly, it is found that the pore size is highly correlated with the thickness, with thicker samples having larger pores. When excited by blue laser, a typical sample with a thickness of 60 μm exhibits an ultra-high luminous efficacy of 261 lm/W and a high saturation threshold of 20.5 W (9.1 W/mm2), resulting in a peak luminous exitance of 1244 lm/mm2@3839 lm. Furthermore, the color mixing was evaluated via angular color temperature distribution, showing uniform light emission with a maximum correlated color temperature (CCT) variation of only ∼800 K
Enhancing biocathode denitrification performance with nano-Fe<sub>3</sub>O<sub>4</sub> under polarity period reversal
No full textThe presence of excessive concentrations of nitrate poses a threat to both the environment and human health, and the bioelectrochemical systems (BESs) are attractive green technologies for nitrate removal. However, the denitrification efficiency in the BESs is still limited by slow biofilm formation and nitrate removal. In this work, we demonstrate the efficacy of novel combination of magnetite nanoparticles (nano-Fe3O4) with the anode-cathode polarity period reversal (PPR-Fe3O4) for improving the performance of BESs. After only two-week cultivation, the highest cathodic current density (7.71 ± 1.01 A m−2) and NO3−-N removal rate (8.19 ± 0.97 g m−2 d−1) reported to date were obtained in the PPR-Fe3O4 process (i.e., polarity period reversal with nano-Fe3O4 added) at applied working voltage of −0.2 and −0.5 V (vs Ag/AgCl) under bioanodic and biocathodic conditions, respectively. Compared with the polarity reversal once only process, the PPR process (i.e., polarity period reversal in the absence of nano-Fe3O4) enhanced bioelectroactivity through increasing biofilm biomass and altering microbial community structure. Nano-Fe3O4 could enhance extracellular electron transfer as a result of promoting the formation of extracellular polymers containing Fe3O4 and reducing charge transfer resistance of bioelectrodes. This work develops a novel biocathode denitrification strategy to achieve efficient nitrate removal after rapid cultivation
Additive Manufacturing of Solid Oxide Electrochemical Cells and Components
No full textSolid oxide cells (SOCs) are exceptionally efficient electrochemical energy conversion devices, featuring reversibility between fuel cell (SOFC) and electrolysis (SOEC) modes. It is an important renewable energy technology with great potential to play a key role in future power grid supply systems and strategies for managing excess electricity. However, the complexity of manufacturing and integrating SOC stacks, coupled with the challenge of corrosion in metal components during long-term operation, has constrained the further development and application of SOC technology. Besides the intrinsic properties of the materials used, the performance and stability of SOCs are strongly influenced by the structural characteristics of the SOC system or its components. Consequently, optimizing the structure of SOCs is an effective way to enhance their performance and stability. However, conventional SOC manufacturing techniques, such as tape casting and screen printing, are primarily suited for creating flat structural components and pose significant challenges in producing complex 3D structures, substantially constraining the possibilities for design optimization of SOC structures. This has resulted in the structure of commercial SOCs being predominantly confined to flat plate configurations over the past several decades, with virtually no advancement in the design of their components.Additive manufacturing technology, also known as 3D printing, boasts a high degree of freedom and precision in shaping complex 3D structural components, surpassing the capabilities of conventional manufacturing methods. Over the past decade, this technology has seen rapid advancements, with successful applications in metals, ceramics, and polymers. It has now become an integral part of modern industrial manufacturing, impacting sectors such as aerospace, automotive, maritime, medical devices, and so on.Leveraging the robust manufacturing capabilities of 3D printing technology for complex 3D structures opens up vast imaginative possibilities for the redesign of SOC structures. This paper systematically explores the feasibility of employing 3D printing technology in the manufacturing of SOCs or their components:(1) We design a monolithic self-supported SOC based-on a gyroid electrolyte. The ceramic electrolyte, sealing components, and support structures are seamlessly integrated into a unified form, fabricated using DLP-based VAT photopolymerization (VPP) 3D printing technology. The fuel electrolyte and oxygen electrode are applied to the opposing surfaces of the electrolyte using a self-designed air jet-assisted wet coating method, and after undergoing a co-sintering process, they form a functioning SOC. The sealed glass and metal interconnects for conventional SOC stacks are no longer required for our design. Moreover, switching from 2D (planar) to 3D (gyroid) electrolytes has maximized spatial utilization. Our design markedly enhances the lightness and compactness of SOCs. Compared to conventional planar SOC stacks, 3D monolithic SOCs (3D SOCs) demonstrate a tenfold improvement in electrochemical performance, both in terms of mass and volume indices. Meanwhile, 3D SOCs exhibit electrochemical stability and microstructural stability compatible with conventional SOCs. This design successfully transitions SOC technology from a 2D to a 3D concept, resulting in an ultra-lightweight and ultra-compact 3D SOC that avoids degradation from metal components, thereby significantly expanding the application prospects of SOCs.(2) We employ laser powder bed fusion (LPBF) 3D printing technology to design a metal support featuring low-tortuosity gas channels for third-generation SOCs. LPBF technology, based on melting metal powder and rapid solidification forming, diverges from conventional powder sintering techniques. This divergence circumvents the formation of sintering necks among powder particles in porous supports, which are susceptible to rapid oxidation/corrosion and subsequent loss of conductivity. Consequently, optimizing this structure enhances the stability of electron conduction of metal supports. We have additionally developed a multi-coating method that combines electrophoretic deposition (EPD) and infiltration to create high-quality oxidation-resistant coatings on metal supports. The metal supports, featuring simplified straight gas channels, enable the uniform formation of coatings on their surface through EPD techniques. The subsequent infiltration process further enhances the quality of the interface between the metal support and the ceramic coating, as well as the density of the coating, thereby endowing the metal support with excellent high-temperature oxidation/corrosion resistance.This work substantially boosts performance by pioneering the optimization of SOC component structures, demonstrating the potential of additive manufacturing technology in SOCs. This thesis also thoroughly analyzes the applications of additive manufacturing for SOCs, anticipating future developments and strategies for scale-up
High voltage pre-treatment on cheddar cheese for model cheese feed preparation
No full textThe growing consumer demand for clean label food products has led to the search for alternatives to calcium-chelating salts in cheese powder production. Pulsed electric field (PEF) technology presents a promising green processing approach with its ability to disrupt casein networks. This study investigated the impact of PEF treatment on Cheddar cheese properties and the resulting model cheese emulsion. Response surface methodology revealed that pulse repetition and electric field strength are the primary parameters influencing the solubilization of calcium and phosphorus from the cheese matrix. Texture profile analysis indicated a notable reduction in cheese hardness with the application of PEF. Despite the significant impact of PEF on cheese structure, our study found no substantial alterations in the emulsion stability of cheeses treated with the applied PEF parameters. These promising results highlight the need for further exploration of alternative PEF parameters, such as different waveforms (i.e. exponential) or shorter pulse durations (nanoseconds), to unlock the full potential of PEF for clean label cheese powder production
Chemical synthesis of natural and azido-modified UDP-rhamnose and -arabinofuranose for glycan array-based characterization of plant glycosyltransferases
No full textChemical syntheses of UDP-rhamnose and UDP-arabinofuranose and respective azido-modified analogues are reported. The prepared substrates are useful for the glycan array-based analysis of glycosyltransferases, as exemplified with the plant cell wall-biosynthetic enzymes PvXAT3, AtRRT4 and PtRRT5.</p
Fault diagnosis and prognosis capabilities for wind turbine hydraulic pitch systems
No full textWind energy is the leading non-hydro renewable technology. Increasing reliability is a key factor in reducing the downtime of high-power wind turbines installed in remote off-shore places, where maintenance is costly and less reactive. Defects in the pitch system are responsible for up to 20% of a wind turbine downtime. Thus, monitoring such defects is essential for avoiding it. This paper presents a generic assessment of the diagnosis capabilities in hydraulic pitch systems, which are used in high-power wind turbines. A mathematical model of the non-linear system dynamics is presented along with a description of the most frequent faults that occur. Structural analysis is used to assess which defects can be detected in the pitch system. The structural properties are furthermore explored to investigate the possibility of reducing the amount of sensors without compromising the fault diagnosis capabilities. Robustness to model uncertainty is finally addressed and generic principles for estimating the detectable magnitude of wear and tear are presented.</p
Organophotocatalytic Carbamoylation of Morita-Baylis-Hillman Carbonates
No full textHerein, we demonstrate that carbamoyl radicals generated through an organophotocatalytic protocol from 4-carbamoyl-dihydropyridines (carbamoyl-DHPs) can be incorporated into Morita-Baylis-Hillman (MBH) carbonates, affording a range of polyfunctionalized scaffolds with yields ranging from 63–98%. Reaction monitoring experiments, scale-up, reuse of the organophotocatalyst, and the hydrogenation of the succinamic ester's alkene moiety was also conducted, in order to showcase the mechanistic features and the robustness of this photochemical protocol.</p
An 8Tx/32Rx head-neck coil at 7T by combining 2Tx/32Rx Nova coil with 6Tx shielded coaxial cable elements
No full textPurposeStandard head coils used at 7T MRI suffer from high signal loss at lower brain regions and neck. This study aimed to increase the field of view (FOV) of a birdcage coil to image the lower brain regions and neck with a straightforward approach of using add-on transmit shielded coaxial cable coil (SCC) elements.MethodsA new head-neck coil was modeled as a combination of the 2Tx/32Rx Nova head coil and 6Tx SCC elements. The add-on transmit SCC elements have been produced. The full wave electromagnetic simulations were performed to analyze the coil geometry and estimate the local specific absorption ratio (SAR). The B1+field maps and structural images were acquired in a phantom and in vivo on a 7T scanner.ResultsThe computed SAR histogram revealed a peak SAR10g of 4.08 W/kg. The simulated and measured maps are in good agreement. The manufactured coil's S-parameters are below 10 dB. The field measurements on a subject presented the increase in the FOV. The T1-weighted structural images of three subjects acquired with the head-neck coil showed increased coverage compared to the head coil only.ConclusionCombining the 2Tx/32Rx Nova head coil and 6Tx SCC elements allowed imaging of the whole brain with an increased FOV down to the C4 spine. The coil stayed fully functional when different subjects were scanned. We conclude that the SCC transmit-only coils are a robust adjunct to conventional coil designs and can meaningfully enhance and expand their field of view.<br/