Assembly Configurations Research Articles

Deep Reconstruction of Mo‐based OER Pre‐Catalysts in Water Electrolysis at High Current Densities

AbstractEvaluating the dynamic structural reconstruction processes of transition metal‐based oxygen evolution reaction (OER) catalysts at industrial current densities in a membrane electrode assembly (MEA) configuration of an anion exchange membrane (AEM) electrolyzer is required for the practical application of OER electrodes in AEM‐type next‐generation electrolyzers. This study unveils the deep reconstruction phenomenon of a Mo‐containing OER catalyst anode during electrolysis at high current densities. A complete reconstruction of the catalyst due to selective Mo‐leaching is inevitable during high current operation and thereby new catalytic surfaces of the Mo‐containing Ni‐based electrodes for sustainable water electrolysis are exposed. The reconstruction was confirmed by ex situ and in situ surface characterization techniques. A scalable route for electrode fabrication demonstrated and it is shown that the reconstruction mechanism of the catalyst leads to a more sustainable operation of the electrolyzer at high current densities.

A Whole-Core Transient Thermal Hydraulic Model for Fluoride Salt-Cooled Reactors

Abstract A thermal hydraulic model is developed for a solid pin-fueled fluoride-salt-cooled small modular advanced high temperature reactor (SmAHTR). This preconceptual SmAHTR was developed by the Oak Ridge National Laboratory (ORNL). For the fuel assembly configuration investigated in this study, the fuel and non-fuel pins are arranged in a hexagonal layout. The molten FLiBe salt coolant flows parallel to the bank of pins. A finite volume model is developed and used to compute temperatures in the solid regions (fuel and non-fuel pins, and the graphite reflectors) in the core. The temperature, flow, and pressure profiles for the coolant flowing through the pin bundles in the core are calculated using the conventional subchannel methodology. Pertinent closure relations are used to compute the hydraulic losses, momentum, and energy exchange between adjacent subchannels, and heat transfer between the solid and fluid regions. The resulting model can perform both steady-state and transient computations across the entire core. This fully implicit model also includes an adaptive time-stepping algorithm for automatic time-step adjustment. A preliminary code-to-code comparison demonstrates good agreement between the present subchannel-based model and a computational fluid dynamics (CFD)-based model for a transient case in which the core inlet flowrate varies with time. Following the code-to-code comparison, the thermal hydraulic model is used to analyze the protected loss of heat sink (P-LOHS) accident scenario. Key results such as the transient evolution of peak fuel, non-fuel, and coolant temperatures, and 3-D core temperature distribution are presented and discussed.

Decontamination of a robot used to reprocess reusable surgical instruments

Using robots to handle medical devices in the decontamination area of the Central Sterile Supply Department (CSSD) can reduce risks and address staff shortages. The gripper design must allow reliable cleaning using standard CSSD procedures to avoid build-up of biofilms and possible cross-contamination between different instrument trays and the gripper's functionality. This study explores the design of the robot's gripper regarding cleanability, aiming to determine whether successful cleaning can be achieved even after prolonged drying for a working shift of 8h. We optimized a gripper for cleanability and used it to assess the spread of different test soils depending on different forms of motion. Subsequently, we analysed the cleanability using sheep's blood as test soil, reprocessing the gripper in different assembly configurations after 4 and 8h of drying, and measuring residual protein. Based on our investigations, we documented the spread of contamination depending on the type of motion of the gripper's components. Sheep's blood exhibited the highest dispersion among the test soils, permeating through thin crevices. Importantly, all samples displayed residual protein levels below the warning threshold, irrespective of drying time and gripper disassembly or cleaning position. Cleaning in a device-specific optimized position achieved results comparable to cleaning the disassembled individual components. These findings indicate that cleaning even after one working shift of 8h and without the labour-intensive disassembly of the gripper is feasible, supporting the future use of robots to handle contaminated medical devices in the CSSD decontamination area.

High-Fidelity Simulations of Shield Assembly Mixed-Convection Flows with Applications Toward Reduced-Resolution Modeling

Flow circulation and heat removal through shield and reflector assemblies can have major impacts on safety in long transients for sodium fast reactors (SFRs). These transients are typically categorized by reduced flow rates and large-scale organized flow patterns, including potential intra-assembly circulation. Such low-flow cases can provide challenges for experiments because of complications in measuring the flow rates and temperatures with high accuracy in different areas. This consequently also raises the uncertainty of many modeling approaches for these phenomena. In an effort to address some of these issues, high-fidelity large eddy simulations are performed using the highly parallel solver NekRS. A 19-pin configuration of a tight-lattice wire-wrapped hexagonal bundle (pitch-to-diameter ratio = 1.07), representing a prototypical internal configuration of a shield assembly, was investigated. The sodium flow was set at a bundle Reynolds number of 2000, with simulations being performed for modified Richardson numbers of 0.0 (i.e., no buoyancy), 0.01, and 0.04, where mixed-convection effects are anticipated. The flow and temperature fields for these cases are discussed in detail. The high-fidelity data should prove useful as reference data for expanding and improving on various reduced-resolution approaches. A basic framework for combining subchannel and computational fluid dynamics methodologies in SFRs is also presented, with preliminary results from simulations of light water reactor bundles and a discussion of changes that need to be made for potential application to SFRs.

Design and Technological Engineering of Gear Wheel Working Surfaces in a Gas Turbine Engine

The design and production of gear wheels includes a number of specialized principles and disciplines aimed to practical application of scientific and practical knowledge. The proposed design method for the subsequent production of the gear configuration together with the technology of virtual life cycle modeling allows predicting its behavior in certain operating modes taking into account the capabilities of an existing production at the design stage. Ensuring the functional properties of the gearing is a complex task, which is solved at all stages of the mechanism life cycle. The solution requires a model of design and technological control of operability, covering the whole life cycle, based on the management of the gearing configuration and the way of objective assessment of the operational properties, based on ensuring the functionality and acceptability. A model of design engineering based on the analysis of the gear acceptability, particularly of the tooth working surface damage classification, based on the reliability of strength calculations, knowledge of materials and precision machining inherent in serial production, with the analysis of the serviceability by functional parameters is proposed. This model allows considering the inconsistencies as acceptable, which often appear, but are not significant. The possibility of making optimal design decisions at the design stage of developing the mechanism configuration in the conditions of using information on serial technological capabilities based on the concept of a “digital twin” when performing feedback between the technological and design directions of gear wheel creating is considered. This creates the groundwork for the development of a new organizational approach to the engineering development of the configuration of assemblies with a tight advantageous cooperation of the designer and technologist.

Numerical investigation on the effect of impeller axial position on hemodynamics of an extracorporeal centrifugal blood pump

Extracorporeal centrifugal blood pumps are used to treat cardiogenic shock. Owing to the imbalanced excitation or initial assembly configurations, the variation in the impeller axial position has the potential to affect the blood pump performance. This study compared the hydrodynamics and hemolysis outcomes at different impeller axial positions via numerical simulations. The result shows that pressure difference of the blood pump decreased with increasing impeller axial position, with decreasing by 4.5% at a flow rate of 2 L/min. Under axial impeller motion close to the top pump casing, average wall shear stress and scalar shear stress reached their maximum values (64.2 and 29.1 Pa, respectively). The residence time in the impeller center hole and bottom clearance were extended to 0.5 s by increasing impeller axial position. Compared to the baseline blood pump, hemolysis index increased by 12.3% and 24.3% when impeller axial position is 2.5 and 4.0 mm, respectively. As a novelty, the findings reveal that the impeller axial position adversely affects hemolysis performance when the impeller is close to the pump casing. Therefore, in the development process of centrifugal blood pumps, the optimal axial position of the impeller must be defined to ensure hemodynamic performance.

Decoding the role of gut microbiota in Alzheimer's pathogenesis and envisioning future therapeutic avenues.

Alzheimer's disease (AD) emerges as a perturbing neurodegenerative malady, with a profound comprehension of its underlying pathogenic mechanisms continuing to evade our intellectual grasp. Within the intricate tapestry of human health and affliction, the enteric microbial consortium, ensconced within the milieu of the human gastrointestinal tract, assumes a role of cardinal significance. Recent epochs have borne witness to investigations that posit marked divergences in the composition of the gut microbiota between individuals grappling with AD and those favored by robust health. The composite vicissitudes in the configuration of the enteric microbial assembly are posited to choreograph a participatory role in the inception and progression of AD, facilitated by the intricate conduit acknowledged as the gut-brain axis. Notwithstanding, the precise nature of this interlaced relationship remains enshrouded within the recesses of obscurity, poised for an exhaustive revelation. This review embarks upon the endeavor to focalize meticulously upon the mechanistic sway exerted by the enteric microbiota upon AD, plunging profoundly into the execution of interventions that govern the milieu of enteric microorganisms. In doing so, it bestows relevance upon the therapeutic stratagems that form the bedrock of AD's management, all whilst casting a prospective gaze into the horizon of medical advancements.

Recent progress in organic waste recycling materials for solar cell applications.

Organic waste-derived solar cells (OWSC) are a classification of third-generation photovoltaic cells in which one or more constituents are fabricated from organic waste material. They are an inspirational complement to the conventional third-generation solar cell with the potential of revolutionizing our future approach to solar cell manufacture. This article provides a study and summary of solar cells that fall under the category of OWSC. OWSC own their merit to low cost of manufacturing and environmental friendliness. This review article reveals different organic waste raw materials, preparation-to-assembly methodologies, and novel approaches to solar cell manufacturing. Ideas for the optimization of the performance of OWSC are presented. The assembly configurations and photovoltaic parameters of reported OWSC are compared in detail. An overview of the trends in the research regarding OWSC in the past decade is given. Also, the advantages and disadvantages of the different solar cell technologies are discussed, and possible trends are proposed. Industrial organic waste raw materials such as paper, coal, and plastics are among the least explored and yet most attractive for solar cell fabrication. The power conversion efficiencies for the cited works are mentioned while emphasizing the products and functions of the organic waste raw materials used.

Electrosynthesis of ethylene glycol from C1 feedstocks in a flow electrolyzer

Ethylene glycol is a widely utilized commodity chemical, the production of which accounts for over 46 million tons of CO2 emission annually. Here we report a paired electrocatalytic approach for ethylene glycol production from methanol. Carbon catalysts are effective in reducing formaldehyde into ethylene glycol with a 92% Faradaic efficiency, whereas Pt catalysts at the anode enable formaldehyde production through methanol partial oxidation with a 75% Faradaic efficiency. With a membrane-electrode assembly configuration, we show the feasibility of ethylene glycol electrosynthesis from methanol in a single electrolyzer. The electrolyzer operates a full cell voltage of 3.2 V at a current density of 100 mA cm−2, with a 60% reduction in energy consumption. Further investigations, using operando flow electrolyzer mass spectroscopy, isotopic labeling, and density functional theory (DFT) calculations, indicate that the desorption of a *CH2OH intermediate is the crucial step in determining the selectively towards ethylene glycol over methanol.

Design and optimization of dual-cooled fuel assembly in a 12×12 configuration for NuScale SMR based on neutronic-thermohydraulic parameters using the combined ANN-GA approach

The Small Modular Reactors (SMRs) use conventional solid fuels. To increase the safety of SMRs, Dual-Cooled Fuel (DCF) can be used. The DCF with two heat transfer surfaces improves heat removal from the fuel. For the first time, this study investigated the use of DCF in a new fuel assembly configuration for the NuScale reactor. Important neutronic and thermohydraulic (N–Th) parameters are obtained. Finally, the optimal DCF rod in a 12 × 12 configuration for the NuScale reactor has been presented. For this purpose, initially, a DCF assembly in a 12 × 12 configuration was designed for the reactor. The fuel mass, enrichment of 235U, and dimensions of fuel assemblies and the core are kept fixed. Then, 32 types of fuel rods with different internal radii were proposed for this assembly. Each of these fuels was placed separately in the assembly and simulated by neutronic codes under cold-clean and full power conditions. Also, the designed fuels were simulated using Computational fluid dynamics (CFD) software, and important thermohydraulic parameters were obtained. Also, to select the optimal fuel rod, the Artificial Neural Network (ANN) and Genetic Algorithm (GA) coupled method is used. To investigate the optimal DCF effects on N–Th parameters in the NuScale reactor, the reference reactor was also simulated and compared with the results of optimal DCF. As one of the most important results of this study, the fuel rod with an internal radius of 0.413423 cm was introduced as the optimal fuel. Also, optimal fuel reduces the temperature and pressure drop, and increases the Departure from Nucleate Boiling Ratio (DNBR).

Design for Manufacturing and Assembly (DfMA) of Standardized Modular Wood Components

The challenges posed by urbanization and the linear product model of “obtain-consume-abolish” has led to irreversible damage to ecological resources. Design principles for manufacturing and assembly (DfMA) of construction projects are critical to significantly increase overall productivity, reduce costs, minimize on-site waste generation, and improve engineering quality and worker safety. This research develops a robot-assisted off-site solution that utilizes wooden components (digital material) designed as interlocking structures for easy installation and disassembly. The workflow of component-design-fabrication-assembly-reconfiguration, connector design, and assembly configuration is combined with mechanical construction, guided by DfMA principles while establishing a Circular Economy (CE) framework. This research contributes to developing robotic construction practices that enhance circularity and mitigate the negative impacts of urbanization on the environment.

Numerical Investigation of Gas Dynamic Foil Bearings Conjugated with Contact Friction by Elastic Multi-Leaf Foils

With increasing demand for load capacity and dynamic responses, the new generation of Gas Dynamic Foil Bearings (GDFB), assembled from preloaded elastic multi-leaf foils, has been put forward. It exhibits steady and dynamic characteristics that are more sensitive to the contact friction produced by foil–foil bearings and the housings of foil bearings, distinguishing its response to rigidity from those of classic bearings. This study aims to employ numerical simulations to explore GDFBs conjugated with contact friction using elastic multi-leaf foils. A numerical method with Bidirectional Fluid–Structure Interactions (BFSIs), which strengthens the steady and dynamic characteristics of GDFBs, has been developed. The results showed that the distribution of steady stiffness was closely associated with the configuration of the foil assembly and the state of contact friction. The maximum steady stiffness occurred near the key blocks and was accompanied by the support of bump foils. The contact friction increased the stiffness of the foil assembly, which was unfavorable to its operational stability, and the GDFB was prone to rigidity. The contact friction hindered the pull-back of the top foils near the negative pressure area. An increase in the rotational speed and eccentricity increased the load capacity while decreasing the operational stability. The maximum pressure of the gas film was inconsistent with the maximum deformation along the circumferential direction because of the configuration of the foil assembly. The contact friction induced energy dissipation, whereas increases in the integrated stiffness inhibited loss. The fixed constraint of the key block increased the dynamic cross-stiffness more than the contact constraint did, which was unfavorable to operational stability. The results obtained in this study are significant because they provide a physical basis for GDFBs and can be used to guide their operational optimization.

DIAMOND CRYSTALLIZATION AND PHASE COMPOSITION IN THE FeNi – GRAPHITE – CaCO3 SYSTEM AT 5.5 Gpa

An experimental simulation of diamond crystallization in the system FeNi - graphite - calcium carbonate at a pressure of 5.5 GPa and a temperature of 1400℃ was carried out. Two sample assembly configurations were used. In the first one – the starting materials were put layer by layer, and in the second one - the components were mixed. It has been established that calcium carbonate, when interacting with the FeNi-melt, decomposes with the formation of Ca,Fe oxides and the release of CO2. Magnetite may be present as an accessory phase. Due to the formation of solid reaction products (Ca,Fe oxides) during layer-by-layer filling of the growth volume, the presence of calcium carbonate between graphite and FeNi-melt prevents diamond crystallization in the graphite layer and carbon transport to diamond seed crystals. When the components are mixed in the growth volume, diamond synthesis and growth onto seed crystals occur. The phenomenon of segregation of diamond crystals together with calcium carbonate and oxide phases, the products of the reaction in the bulk of the metal, has been discovered. Aliphatic, cyclic, and oxygenated hydrocarbons, including heavy compounds (C13-C17), CO2, H2O, nitrogen- and sulfonated compounds, were identified in the fluid phase captured by diamonds in the form of inclusions during growth. The composition of the fluid phase in the studied diamonds is more oxidized compared to the composition of fluid inclusions in diamonds grown in the FeNi – graphite system without carbonate. The results obtained correlate with the data on natural diamonds, among which there are crystals with “essentially carbon dioxide” compositions of fluid inclusions, which indicates the possible participation of crustal carbonate matter in the processes of diamond formation during subduction into the deep mantle.

Preliminary development of machine learning-based error correction model for low-fidelity reactor physics simulation

Better prediction capability in reactor simulation procedures can result in better fuel planning, increased safety, and compliance with the Technical Specifications. Motivated by this necessity in the nuclear industry, we develop a method to improve the current reactor core simulation process using a machine learning approach. With a well-trained machine learning model, it is possible to predict the errors of the low-fidelity diffusion-based core simulator without a significant increase in complexity and computational cost. For the machine learning models, we have tested two different models based on Deep Neural Network and Extreme Gradient Boosting trained on high-fidelity Monte Carlo reactor simulation data. The proposed method has been verified in this work on simple 2x2 boiling water reactor color sets. We collected large data points that include different variations of assembly configuration, burnup, void fraction, and control blade insertion in both low-fidelity and high-fidelity data. The developed models can accurately predict errors in eigenvalue and assembly power. Utilizing the predicted errors, the machine learning-aided simulation results in a significant improvement over the conventional reactor simulation approach.

A Micro-Reference Electrode for Electrode-Resolved Impedance and Potential Measurements in All-Solid-State Battery Pouch Cells and Its Application to the Study of Indium-Lithium Anodes

Impedance measurements are a powerful tool to investigate interfaces in lithium-ion batteries (LIBs). In order to deconvolute the anode and cathode contributions to the cell impedance, a reference electrode (RE) is required. However, there are only very few reports on the use of a three-electrode setup with an RE for all-solid-state batteries (ASSBs), which is due to the complexity of integrating an RE with a suitable geometry into the typical ASSB test cells that are based on a compressed electrolyte pellet. In this study, we present a straightforward approach to implement a micro-reference electrode (μ-RE) for electrode-resolved impedance and potential measurements into ASSB pouch cells. The μ-RE consists of an insulated ∼64 μm diameter gold wire that is sandwiched between two Li6PS5Cl/polymer separator sheets and activated by in situ electrochemical lithiation. Using this μ-RE, we investigate the electrode potential and the accessibility of cyclable lithium at the separator interface of indium-lithium anodes, which are prepared by stacking lithium and indium foils with a molar excess of indium. We compare two different cell assembly configurations, with the separator faced by either (i) the formerly In-side or (ii) the formerly Li-side, showing that only the latter case provides a reservoir of cyclable lithium.

Design and fabrication by selective laser melting of a LIDAR reflective unit using metal matrix composite material

The selective laser melting is an additive manufacturing technology able to directly fabricate full dense metal part from a virtual model. The geometrical complexity degree of freedom allows the implementation to several industrial applications such as the laser imaging detection and ranging systems. A key component of this system is the reflective unit produced with traditional technology (surface with ribs) with optimized geometry for lightweight, which must be further lightened while continuing to meet functional requirements. Aim of this work is to reach these goals by using an integrated product/process methodology which considers all the fabrication steps. A complete redesign allowed to exploit the additive manufacturing advantages of a metal matrix composite based on AA 2000 series combined with a high content of ceramic. The increased mechanical properties, such as the tensile strength of 484 MPa and Young modulus of 96GPa, combined with a lattice structure empowered the SLM capability. The component was validated via finite element method simulation focused on the most critical polishing operation. Results on static and dynamic analysis showed the 25% lightened mirror satisfies the requirements. The testing on the physical prototype confirmed the enhanced mechanical properties and the interferometric measurement proved the mirror functionality with a surface front error less than the required wavelength of 1550 nm. The work evidenced that polishing and the assembly configurations must be selected with particular care; otherwise, the final outcome is compromised for this SLMed component.

GEM-Gate: A Low-Cost, Flexible Approach to BioBrick Assembly

Rapid and modular assembly of DNA parts is crucial to many synthetic biologists. This can be achieved through Golden Gate assembly, which often requires purchase and delivery of new primers for each part and assembly configuration. Here, we report on a small set of primers that can be used to amplify any DNA from the Registry of Standard Biological Parts for Golden Gate assembly. These primers bind to regions common to the backbone plasmid for these parts, but pair imperfectly and introduce type IIS restriction enzyme sites in a way that minimizes assembly scars. This approach makes redesign of assembly strategies faster and less expensive and can help expand access to synthetic biology to a wider group of scientists and students.

A general cost model to assess the implementation of collaborative robots in assembly processes

In assembly processes, collaborative robots (cobots) can provide valuable support to improve production performance (assembly time, product quality, worker wellbeing). However, there is a lack of models capable of evaluating cobot deployment and driving decision-makers to choose the most cost-effective assembly configuration. This paper tries to address this gap by proposing a novel cost model to evaluate and predict assembly costs. The model allows a practical and straightforward comparison of different potential assembly configurations in order to guide the selection towards the most effective one. The proposed cost model considers several cost dimensions, including manufacturing, setup, prospective, retrospective, product quality and wellbeing costs. The cost estimation also considers learning effects on assembly time and quality, particularly relevant in low-volume and mass customised productions. Three real manufacturing case studies accompany the description of the model.

Scalable Synthesis of Multi-Metal Electrocatalyst Powders and Electrodes and their Application for Oxygen Evolution and Water Splitting.

Multi-metal electrocatalysts provide nearly unlimited catalytic possibilities arising from synergistic element interactions. We propose a polymer/metal precursor spraying technique that can easily be adapted to produce a large variety of compositional different multi-metal catalyst materials. To demonstrate this, 11 catalysts were synthesized, characterized, and investigated for the oxygen evolution reaction (OER). Further investigation of the most active OER catalyst, namely CoNiFeMoCr, revealed a polycrystalline structure, and operando Raman measurements indicate that multiple active sites are participating in the reaction. Moreover, Ni foam-supported CoNiFeMoCr electrodes were developed and applied for water splitting in flow-through electrolysis cells with electrolyte gaps and in zero-gap membrane electrode assembly (MEA) configurations. The proposed alkaline MEA-type electrolyzers reached up to 3 A cm-2 , and 24 h measurements demonstrated no loss of current density of 1 A cm-2 .

Fine-Tuned Polymer Nanoassembly for Codelivery of Chemotherapeutic Drug and siRNA.

Successful clinical application of siRNA to liver-associated diseases reinvigorates the RNAi therapeutics and delivery vectors, especially for anticancer combination therapy. Fine tuning of copolymer-based assembly configuration is highly important for a desirable synergistic cancer cell-killing effect via the codelivery of chemotherapeutic drug and siRNA. Herein, an amphiphilic triblock copolymer methoxyl poly(ethylene glycol)-block-poly(L-lysine)-block-poly(2-(diisopropyl amino)ethyl methacrylate) (abbreviated as mPEG-PLys-PDPA or PLD) consisting of a hydrophilic diblock mPEG-PLys and a hydrophobic block PDPA is synthesized. Three distinct assemblies (i.e., nanosized micelle, nanosized polymersome, and microparticle) are acquired, along with the increase in PDPA block length. Furthermore, the as-obtained polymersome can efficiently codeliver doxorubicin hydrochloride (DOX) as a hydrophilic chemotherapeutic model and siRNA against ADP-ribosylation factor 6 (siArf6) as an siRNA model into cancer cell via lysosomal pH-triggered payload release. PC-3 prostate cell is synergistically killed by the DOX- and siArf6-coloading polymersome (namely PLD@DOX/siArf6). PLD@DOX/siArf6 may serve as a robust nanomedicine for anticancer therapy.