Loop Concept Research Articles

Kinetic study of microwave heating-assisted chemical looping dry reforming of methane over magnetite

Dry reforming of methane carried out via the chemical looping concept and employing microwave heating is a sustainable syngas (a mixture comprising hydrogen and carbon monoxide) production technology. Understanding the intrinsic reaction kinetics of reduction and oxidation is essential for successful scale-up of this technology. By employing magnetite as a microwave absorber oxygen carrier, we investigated the reaction kinetics at bulk temperatures in the range of 650–800 °C for reduction and 500–650 °C for oxidation. Results indicated both reactions followed a phase-boundary controlled (contracting sphere) reaction mechanism. Upon developing the reaction kinetics based on solid temperature relevant to microwave-heated particles, we estimated the activation energy to be 85 kJ/mol for the reduction reaction and 22 kJ/mol for the oxidation reaction. By developing the reaction kinetic of the reduction under microwave heating and based on bulk temperature, we estimated 68 kJ/mol as the activation energy of the reduction reaction. Comparing these values with the activation energy of magnetite reduction by methane under conventional heating (around 90 kJ/mol) indicated that microwave irradiation apparently decreased the activation energy. Consequently, by developing the reaction kinetics based on an appropriate temperature, i.e., solid temperature, we demonstrated that microwave primarily had a thermal effect in our study, increasing the reaction rate constant, rather than a non-thermal effect, like altering the activation energy.

A strategic IT policy implementation model for enhancing customer satisfaction in digital markets

In the increasingly competitive landscape of digital markets, customer satisfaction is paramount for sustained business success. This paper proposes a Strategic IT Policy Implementation Model aimed at enhancing customer satisfaction by aligning IT policy development with customer-centric strategies. The model serves as a framework that integrates technological advancements with customer expectations, ensuring that IT policies effectively support business objectives and improve operational reliability. The proposed model emphasizes a holistic approach to IT policy formulation, incorporating stakeholder input, market analysis, and performance metrics. It identifies key areas where IT policies can directly influence customer experiences, including data management, service delivery, and communication channels. By focusing on these elements, organizations can develop IT policies that not only comply with regulatory standards but also enhance user engagement and satisfaction. Central to the model is the concept of continuous feedback loops, which facilitate the ongoing evaluation and refinement of IT policies based on customer insights. This adaptive mechanism enables businesses to remain responsive to changing customer needs and technological advancements, fostering a culture of innovation and customer-centricity. Moreover, the model advocates for cross-departmental collaboration, ensuring that IT policies are harmonized with marketing, sales, and customer service strategies. Implementation of the model is illustrated through case studies of leading technology firms that have successfully aligned their IT policies with customer-centric approaches. These examples highlight the tangible benefits of improved customer satisfaction, increased loyalty, and enhanced operational reliability. Furthermore, the model addresses common challenges faced during implementation, such as resistance to change and resource constraints, offering practical solutions to overcome these obstacles. In conclusion, the Strategic IT Policy Implementation Model provides a structured approach for organizations aiming to enhance customer satisfaction in digital markets. By aligning IT policies with customer-centric strategies, businesses can achieve greater operational efficiency and foster long-term relationships with their customers.

CO2 utilization and on-purpose ethylene production: A chemical looping approach

CO2-assisted ethane dehydrogenation (CO2-ODHE) is a promising carbon atom economy process for upgrading CO2 to CO in tandem with C2H6 to C2H4 conversion. Iron oxide-based materials are selective for on purpose ethylene production through CO2-ODHE. The feed admission mode was found to play an important role on catalytic performance. Alternating C2H6 (reduction step) and CO2 (oxidation step) feedstock to a fixed bed reactor (chemical looping concept, CO2-ODHE-CL) attained constant ethane and CO2 conversion per step at 600 °C, equal to ∼17.6 %, while C2H4 selectivity during the reduction step was ∼75 %. The lattice oxygen mobility is a descriptor for the materials used during the CO2-ODHE-CL, since low mobility resulted in an increased C-H bond scission selectivity, i.e., C2H4 production, during the reduction step. Temperature programmed 18O2 isotope exchange experiments, along with temperature programmed H2 – reduction, were employed to exemplify the latter statement, investigating the lattice oxygen reactivity of the examined materials and the mechanism through which the lattice oxygen is reacting. X-ray techniques (X-ray Diffraction, X-ray Raman Scattering Spectrometry, X-ray Absorption Spectrometry) along with structural modeling demonstrated that the formation of a spinel like arrangement between Mg and Fe, stabilized lattice oxygen and thus minimized the undesired C-C bond scission during the C2H6 step of CO2-ODHE-CL.

Widespread biochemical reaction networks enable Turing patterns without imposed feedback

Understanding self-organized pattern formation is fundamental to biology. In 1952, Alan Turing proposed a pattern-enabling mechanism in reaction-diffusion systems containing chemical species later conceptualized as activators and inhibitors that are involved in feedback loops. However, identifying pattern-enabling regulatory systems with the concept of feedback loops has been a long-standing challenge. To date, very few pattern-enabling circuits have been discovered experimentally. This is in stark contrast to ubiquitous periodic patterns and symmetry in biology. In this work, we systematically study Turing patterns in 23 elementary biochemical networks without assigning any activator or inhibitor. These mass action models describe post-synthesis interactions applicable to most proteins and RNAs in multicellular organisms. Strikingly, we find ten simple reaction networks capable of generating Turing patterns. While these network models are consistent with Turing’s theory mathematically, there is no apparent connection between them and commonly used activator-feedback intuition. Instead, we identify a unifying network motif that enables Turing patterns via regulated degradation pathways with flexible diffusion rate constants of individual molecules. Our work reveals widespread biochemical systems for pattern formation, and it provides an alternative approach to tackle the challenge of identifying pattern-enabling biological systems.

Learning Health Systems Are Resilient Health Systems Comment on "Re-evaluating Our Knowledge of Health System Resilience During COVID-19: Lessons From the First Two Years of the Pandemic".

Saulnier's review, "Re-evaluating Our Knowledge of Health System Resilience During COVID-19: Lessons From the First Two Years of the Pandemic," analyzes health systems resilience in the first two years of the COVID-19 pandemic. A key finding was the importance of learning. In this commentary, we argue that strengthening systems-level learning capabilities could build resilient health systems. Drawing on learning theories and evidence from organizational resilience and management scholarship, we link the concept of learning loops with Blanchet's resilience capacities framework, demonstrating the importance of higher levels of learning to build adaptive and transformative resilience capacities. We also argue for an increased focus on power analysis to analyze what is learned, who learns it, and who responds as determining factors to adaptation and transformation. Future research should empirically investigate the extent to which different types of learning supports - or impedes - the building of resilient health systems.

Techno-economic analysis of chemical looping processes with biomass resources for energy production and CO2 utilization. Comparison of CLC and CLOU technologies

Bioenergy coupled with carbon capture utilization and storage (BECCUS) is an attractive greenhouse gas mitigation technology that can produce negative CO2 emissions by combining bioenergy resources with the utilization or geological storage of the captured CO2.The main objective of this work was to evaluate the technical and economic feasibility of two BECCUS technologies based on chemical looping concept with two biomass waste as fuels, i.e., swine manure and pine sawdust, for the production of thermal energy and a pure CO2 stream that is subsequently used as raw material in agricultural greenhouses. Direct use of solid biomass resources was considered for the Chemical Looping with Oxygen Uncoupling option, whereas biogas production was the starting point for Chemical Looping Combustion.The profitability of the chemical looping scenarios was assessed through the Levelized Cost of CO2. This parameter was estimated at 218.31 €/t CO2 for the Chemical Looping Combustion scenario, a value much higher than those for the Chemical Looping with Oxygen Uncoupling scenarios (73.04–87.32 €/t CO2) due to the limited conversion degree of the carbon present in the fuel waste to biogas and the need for an additional experimental plant to the Chemical Looping Combustion unit, i.e., the biogas production plant. Comparing the Chemical Looping with Oxygen Uncoupling scenarios, the economic analysis revealed that the profitability of the biomass-fueled chemical looping facility was markedly sensitive to the selling price of the biomass resource. Furthermore, the values of the Levelized Cost of CO2 parameter for the Chemical Looping with Oxygen Uncoupling scenarios were lower than those estimated in other research studies that implemented BECCUS technologies and utilized the captured CO2 for identical purposes. In the particular case of swine manure, this result becomes even more noteworthy since it demonstrates that the energy use of this biomass resource through Chemical Looping with Oxygen Uncoupling technology is an economically profitable and environmentally sustainable solution to the difficult challenge of managing this livestock waste. Therefore, it can be concluded that Chemical Looping with Oxygen Uncoupling processes fed with biomass are a very attractive BECCUS technology for heat generation where, in addition, the pure CO2 stream obtained at the outlet of the fuel reactor can be considered a marketable, high value-added product.

Photoinduced Electronic and Spin Topological Phase Transitions in Monolayer Bismuth.

Ultrathin bismuth exhibits rich physics including strong spin-orbit coupling, ferroelectricity, nontrivial topology, and light-induced structural dynamics. We use abinitio calculations to show that light can induce structural transitions to four transient phases in bismuth monolayers. These light-induced phases exhibit nontrivial topological character, which we illustrate using the recently introduced concept of spin bands and spin-resolved Wilson loops. Specifically, we find that the topology changes via the closing of the electron and spin band gaps during photoinduced structural phase transitions, leading to distinct edge states. Our study provides strategies to tailor electronic and spin topology via ultrafast control of photoexcited carriers and associated structural dynamics.

Enhancing human-human musical interaction through kinesthetic haptic feedback using wearable exoskeletons: theoretical foundations, validation scenarios, and limitations.

In this perspective paper, we explore the use of haptic feedback to enhance human-human interaction during musical tasks. We start by providing an overview of the theoretical foundation that underpins our approach, which is rooted in the embodied music cognition framework, and by briefly presenting the concepts of action-perception loop, sensorimotor coupling and entrainment. Thereafter, we focus on the role of haptic information in music playing and we discuss the use of wearable technologies, namely lightweight exoskeletons, for the exchange of haptic information between humans. We present two experimental scenarios in which the effectiveness of this technology for enhancing musical interaction and learning might be validated. Finally, we briefly discuss some of the theoretical and pedagogical implications of the use of technologies for haptic communication in musical contexts, while also addressing the potential barriers to the widespread adoption of exoskeletons in such contexts.

Teaching and learning game design with the concept of gameplay loops

Teaching and learning game design with the concept of gameplay loops

Highly sintering-resistant iron oxide with a hetero-oxide shell for chemical looping water splitting

Chemical looping water splitting is a promising technology that couples carbonaceous fuel oxidation to produce H2 with inherent CO2 separation. Redox catalyst with long-term performance is the key issue but is hampered in traditional Fe2O3-based approaches due to Fe sintering. This study reports a one-step sol-gel synthetic method to construct Fe2O3@Hetero-oxide redox catalysts with core-shell structure, leading to outstanding anti-sintering property in TGA analysis (>250 cycles, 5000 min). Fixed-bed reactor tests showed that hydrogen yield approached theoretical value (16.7 mmol/g-Fe2O3), with ∼100 % H2 purity. This result is significantly better than dispersing a mixed ionic-electronic conductor (MIEC) in Fe2O3 matrix using high energy ball milling. Although the latter can enhance the durability due to facilitated O2− and electron transportation, Fe sintering and redox catalysts deactivation is inevitable. This study offers a generalized structure design and synthetic approach for anti-sintering redox catalysts within chemical looping concepts.

The truth of the artwork From the artistic object to the artwork as a Loop

Through the interpretations of artwork provided by Hegel, Kant, and Heidegger, the artwork presents itself as complex and often irreducible. The reading offered by Harman, grounded in Object-Oriented Ontology (OOO), constructs a historically significant interpretation but does not exhaust the problematic nature of artwork represents. Through this article, I have attempted to demonstrate the functionality of the concept of loop applied to artwork, providing general connotations and linguistic tools for interpreting artwork as a loop.

Building models of quarks and gluons with an arbitrary number of colors using Cartan-Polyakov loops

In this work we introduce the concept of Cartan-Polyakov loops, a special subset of Polyakov loops in the fundamental and antifundamental representation of the SU(Nc) group, ℓF,k and ℓ‾F,k respectively, with charges k=1,…,(Nc−1)/2. It constitutes a sufficient set of independent degrees of freedom and it is used to parametrize the thermal Wilson line. Polyakov loops not contained in this set are classified as non-Cartan-Polyakov loops. Using properties of the characteristic polynomial of the thermal Wilson line, we write a non-Cartan-Polyakov loop charge decomposition formula. This formalism allows one to readily build effective models of quarks and gluons with an arbitrary number of colors. We apply it to the Polyakov-Nambu-Jona-Lasinio model and to an effective glue model, in the mean field approximation, showing how to directly extend these models to higher values of Nc.

Hydrogen production and CO2 capture from Linz-Donawitz converter gas via a chemical looping concept

Linz-Donawitz converter gas (LDG), an important by-product in the steel industry with CO (55–60 vol%) and CO2 (15–20 vol%) as the main components, is usually used as fuel for heating or power generation, releasing massive of diluted CO2 with the concentration lower than 15 % that is difficult to capture. Herein, we propose a method to produce pure H2 via chemical looping water splitting by using LDG as reducing agent, which can easily concentrate CO2 for capture. Fe2O3, one of the most environmentally friendly and low-cost oxides, was chosen as the oxygen carrier to perform this concept. It was found that the addition of small amounts of Ce0.75Zr0.25O2 solid solution could strongly improve the activity of Fe2O3 for CO conversion, especially at relatively low temperatures. Compared with pure Fe2O3, the CO conversion and H2 yield were increased from 39.5 % and 0.34 mmol·g−1 to 100 % and 2.32 mmol·g−1 at 650 °C, respectively, after adding 5 wt% of Ce0.75Zr0.25O2. The strong interaction between the two oxides contributed to the enhanced performance via promoting CO adsorption and lattice oxygen releasing. Water splitting assisted by air oxidation could fully regenerate the reduced oxygen carrier, and the oxygen carrier was stable during the long-term chemical looping process, with the CO2 capture rate at ca. 95.8 %. In situ DRIFTS results showed that CO2 was producedthrough a direct reaction of lattice oxygen with CO, and the decomposition of carbonate species intermediate by adsorption of CO on the surface of oxygen carriers. This study gave full evidence that it was feasible for achieving H2 generation and CO2 capture in one step via chemical looping reforming of reducing exhaust gases (e.g., LDG) from industrial emissions.

Carbon Dioxide Capture and Hydrogen Production with a Chemical Looping Concept: A Review on Oxygen Carrier and Reactor

Carbon Dioxide Capture and Hydrogen Production with a Chemical Looping Concept: A Review on Oxygen Carrier and Reactor

Influence of Fluidised Bed Inventory on the Performance of Limestone Sorbent in Calcium Looping for Thermochemical Energy Storage

This research work deals with the application of the calcium looping concept for thermochemical energy storage. Experiments were carried out in a lab-scale fluidised bed reactor, which was electrically heated. An Italian limestone (98.5% CaCO3, 420–590 μm) was present in the bed alone, or in combination with silica sand/silicon carbide (this last material was chosen as per its high absorption capacity in the solar spectrum). Calcium looping tests (20 calcination/carbonation cycles) were carried out under operating conditions resembling the “closed-loop” scheme (calcination at 950 °C, carbonation at 850 °C, fluidising atmosphere composed of pure CO2 in both cases). Carbonation degree, particle size distribution, and particle bulk density were measured as cycles progressed, together with the application of a model equation to relate carbonation degree to the number of cycles. Mutual relationships between the nature of the bed material and possible interactions, the degree of CaO carbonation, the generation of fragments, and changes in particle density and porosity are critically discussed. An investigation of the segregation behaviour of the bed material has been carried out through tests in a devoted fluidisation column, equipped with a needle-type capacitive probe (to measure solid concentration).

Dark loops: contagion effects, consistency and chemosocial matrices in psychedelic-assisted therapy trials.

What happens when an emerging programme of medical research overlaps with a surging social movement? In this article we draw on the anthropological term 'chemosociality' to describe forms of sociality born of shared chemical exposure. Psychedelic administration in the context of recent clinical trials appears to have been particularly chemosocial in nature. We argue that one consequence is that psychedelic-assisted therapy (PAT) clinical research trials tend to breach key assumptions underlying the logic of causal inference used to establish efficacy. We propose the concept of dark loops to describe forms of sociality variously emerging from, and impacting participant experiences in, PAT trials. These dark loops are not recorded, let alone incorporated into the causal pathways in the interpretation of psychedelic trial data to date. We end with three positions which researchers might adopt in response to these issues: chemosocial minimisation where research is designed to attenuate or eliminate the effects of dark loops in trials; chemosocial description where dark loops (and their impacts) are openly and candidly documented and chemosocial valorisation where dark loops are hypothesised to contribute to trial outcomes and actively drawn upon for positive effect. Our goal is to fold in an appreciation of how the increasingly-discussed hype surrounding psychedelic research and therapeutics continues to shape the phenomena under study in complex ways, even as trials become larger and more rigorous in their design.

Stream power curve–loop–spiral conceptual method and an application to rivers of Taiwan

Study regionEighteen main rivers in Taiwan. Study focusThe concept of total stream power (TSP) or specific stream power (SSP) has been investigated previously as an index for assessing the status of a river channel. Here, we introduce a new diagram called the “stream power loop” to review variations in fluvial conditions, morphology, and sediment transport potential from river source to estuary. Because of its physical basis, the loop diagram reflects fluvial morphology and watershed conditions. Additionally, we present a spiral diagram that depicts variations in the spatial gradients of TSP and SSP. The gradient implied the sediment transport trend, which from upstream to downstream changes gradually from scouring to siltation in ideal conditions. The loop and spiral diagrams provide an overview of the fluvial system. New hydrological insights for the regionThe loop diagram applications in Taiwan categorized the rivers into three types: simple loop, maple-leaf loop, and complex loop. Diverse geology increases the likelihood of large tributaries and abrupt changes in terrain, both of which affect the components of stream power–discharge and slope. The scatter distribution of all the data aggregated from the 18 rivers showed a shrinking radius and a counter-clockwise spiral pathway, passing through the mountain river zone, the braided river zone, and finally to the straight & meandering river zone. The result supported the concept of stream power loop and indicated that stream power loop can interpret the status of the river systems.

On the extension of the grain loop concept from 2D to 3D granular assemblies

On the extension of the grain loop concept from 2D to 3D granular assemblies

Prototype of a Recommendation Model with Artificial Intelligence for Computational Thinking Improvement of Secondary Education Students

There is a growing interest in finding new ways to address the difficult task of introducing programming to secondary students for the first time to improve students’ computational thinking (CT) skills. Therefore, extensive research is required in this field. Worldwide, new ways to address this difficult task have been developed: visual execution environments and approaches by text programming or visual programming are among the most popular. This paper addresses the complex task by using a visual execution environment (VEE) to introduce the first programming concepts that should be covered in any introductory programming course. These concepts include variables, input and output, conditionals, loops, arrays, functions, and files. This study explores two approaches to achieve this goal: visual programming (using Scratch) and text programming (using Java) to improve CT. Additionally, it proposes an AI recommendation model into the VEE to further improve the effectiveness of developing CT among secondary education students. This integrated model combines the capabilities of an AI learning system module and a personalized learning module to better address the task at hand. To pursue this task, an experiment has been carried out among 23 preservice secondary teachers’ students in two universities, one in Madrid, Spain, and the other in Galway, Ireland. The overall results showed a significant improvement in the Scratch group. However, when analyzing the results based on specific programming concepts, significance was observed only in the Scratch group, specifically for the Loop concept.

How feedback loops between meso- and macrofauna and organic residues contrasting in chemical quality determine decomposition dynamics in soils

The concept of feedback loops between changes in chemical quality of decomposing organic residues and changes in faunal communities was employed in studying how such feedback loops, representing distinct ecological successional stages, determine decomposition dynamics in soils. A 52-week litterbag decomposition study was superimposed onto an 18-year long term field experiment. Four types of organic residues contrasting in chemical quality (i.e., nitrogen (N), lignin, polyphenols, cellulose) were incorporated into soil annually to assess decomposition and associated meso- and macrofauna communities. In the first 4 weeks after residue incorporation (loop #1), the abundances (densities) of both mesofauna and macrofauna were positively influenced by labile cellulose and N. The mesofauna Collembola and Acari contributed 70–100% and 0–30% to the decomposition, respectively, while the macrofauna beetles and flies contributed 20–90% and 10–66%, respectively. The abundances were highest under groundnut (high N, low lignin) ([1.35 and 0.85 individual number (g dry litter)−1] for mesofauna and macrofauna, respectively). The presence of macrofauna at week 2 led to a mass loss (R2 = 0.67**), indicating that macrofauna preceded mesofauna in degrading residue. In week 8 (transition of loop #2 to #3), only macrofauna (beetles dominated contributing 65%) played an important role in lignin decomposition (R2 = 0.56**), resulting in a mass loss (R2 = 0.52**). In week 52 (loop #4) macrofauna, ants (Formicidae) replaced beetles as the dominant decomposers showing a feedback reaction to availability of protected cellulose. The Formicidans contributed 94% to the decomposition and influenced losses of mass (R2 = 0.36*) and N (R2 = 0.78***). The feedback loop concept provides a more comprehensive “two-sided” view into decomposition, as regulated simultaneously by two factors, than earlier “one-sided” approaches to soil fauna-mediated decomposition.