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15 pages, 1391 KiB  
Article
Valorization of Food By-Products: Formulation and Evaluation of a Feed Complement for Broiler Chickens Based on Bonito Fish Meal and Única Potato Peel Flour
by Ashley Marianella Espinoza Davila and Rebeca Salvador-Reyes
Resources 2025, 14(8), 125; https://doi.org/10.3390/resources14080125 (registering DOI) - 1 Aug 2025
Abstract
Restaurants and open markets generate considerable quantities of organic waste. Converting these residues into poultry feed ingredients offers a sustainable disposal route. This study aimed to evaluate the nutritional and sensory viability of a novel feed complement formulated from Bonito fish meal ( [...] Read more.
Restaurants and open markets generate considerable quantities of organic waste. Converting these residues into poultry feed ingredients offers a sustainable disposal route. This study aimed to evaluate the nutritional and sensory viability of a novel feed complement formulated from Bonito fish meal (Sarda chiliensis chiliensis) and Única potato peel flour (Solanum tuberosum L. cv. Única). This study was conducted in three phases: (i) production and nutritional characterization of the two by-product flours; (ii) formulation of a 48:52 (w/w) blend, incorporated into broiler diets at 15%, 30%, and 45% replacement levels over a 7-week trial divided into starter (3 weeks), grower (3 weeks), and finisher (1 week) phases; and (iii) assessment of growth performance (weight gain, final weight, and feed conversion ratio), followed by a sensory evaluation of the resulting meat using a Check-All-That-Apply (CATA) analysis. The Bonito fish meal exhibited 50.78% protein, while the Única potato peel flour was rich in carbohydrates (74.08%). The final body weights of broiler chickens ranged from 1872.1 to 1886.4 g across treatments, and the average feed conversion ratio across all groups was 0.65. Replacing up to 45% of commercial feed with the formulated complement did not significantly affect growth performance (p > 0.05). Sensory analysis revealed that meat from chickens receiving 15% and 45% substitution levels was preferred in terms of aroma and taste, whereas the control group was rated higher in appearance. These findings suggest that the formulated feed complement may represent a viable poultry-feed alternative with potential sensory and economic benefits, supporting future circular-economy strategies. Full article
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21 pages, 719 KiB  
Review
Intra-Arterial Administration of Stem Cells and Exosomes for Central Nervous System Disease
by Taishi Honda, Masahito Kawabori and Miki Fujimura
Int. J. Mol. Sci. 2025, 26(15), 7405; https://doi.org/10.3390/ijms26157405 (registering DOI) - 31 Jul 2025
Abstract
Central nervous system (CNS) disorders present significant therapeutic challenges due to the limited regenerative capacity of neural tissues, resulting in long-term disability for many patients. Consequently, the development of novel therapeutic strategies is urgently warranted. Stem cell therapies show considerable potential for mitigating [...] Read more.
Central nervous system (CNS) disorders present significant therapeutic challenges due to the limited regenerative capacity of neural tissues, resulting in long-term disability for many patients. Consequently, the development of novel therapeutic strategies is urgently warranted. Stem cell therapies show considerable potential for mitigating brain damage and restoring neural connectivity, owing to their multifaceted properties, including anti-apoptotic, anti-inflammatory, neurogenic, and vasculogenic effects. Recent research has also identified exosomes—small vesicles enclosed by a lipid bilayer, secreted by stem cells—as a key mechanism underlying the therapeutic effects of stem cell therapies, and given their enhanced stability and superior blood–brain barrier permeability compared to the stem cells themselves, exosomes have emerged as a promising alternative treatment for CNS disorders. A key challenge in the application of both stem cell and exosome-based therapies for CNS diseases is the method of delivery. Currently, several routes are being investigated, including intracerebral, intrathecal, intravenous, intranasal, and intra-arterial administration. Intracerebral injection can deliver a substantial quantity of stem cells directly to the brain, but it carries the potential risk of inducing additional brain injury. Conversely, intravenous transplantation is minimally invasive but results in limited delivery of cells and exosomes to the brain, which may compromise the therapeutic efficacy. With advancements in catheter technology, intra-arterial administration of stem cells and exosomes has garnered increasing attention as a promising delivery strategy. This approach offers the advantage of delivering a significant number of stem cells and exosomes to the brain while minimizing the risk of additional brain damage. However, the investigation into the therapeutic potential of intra-arterial transplantation for CNS injury is still in its early stages. In this comprehensive review, we aim to summarize both basic and clinical research exploring the intra-arterial administration of stem cells and exosomes for the treatment of CNS diseases. Additionally, we will elucidate the underlying therapeutic mechanisms and provide insights into the future potential of this approach. Full article
(This article belongs to the Special Issue Stem Cells Research: Advancing Science and Medicine)
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46 pages, 5039 KiB  
Review
Harnessing Insects as Novel Food Ingredients: Nutritional, Functional, and Processing Perspectives
by Hugo M. Lisboa, Rogério Andrade, Janaina Lima, Leonardo Batista, Maria Eduarda Costa, Ana Sarinho and Matheus Bittencourt Pasquali
Insects 2025, 16(8), 783; https://doi.org/10.3390/insects16080783 - 30 Jul 2025
Viewed by 322
Abstract
The rising demand for sustainable protein is driving interest in insects as a raw material for advanced food ingredients. This review collates and critically analyses over 300 studies on the conversion of crickets, mealworms, black soldier flies, and other farmed species into powders, [...] Read more.
The rising demand for sustainable protein is driving interest in insects as a raw material for advanced food ingredients. This review collates and critically analyses over 300 studies on the conversion of crickets, mealworms, black soldier flies, and other farmed species into powders, protein isolates, oils, and chitosan-rich fibers with targeted techno-functional roles. This survey maps how thermal pre-treatments, blanch–dry–mill routes, enzymatic hydrolysis, and isoelectric solubilization–precipitation preserve or enhance the water- and oil-holding capacity, emulsification, foaming, and gelation, while also mitigating off-flavors, allergenicity, and microbial risks. A meta-analysis shows insect flours can absorb up to 3.2 g of water g−1, stabilize oil-in-water emulsions for 14 days at 4 °C, and form gels with 180 kPa strength, outperforming or matching eggs, soy, or whey in specific applications. Case studies demonstrate a successful incorporation at 5–15% into bakery, meat analogs and dairy alternatives without sensory penalties, and chitin-derived chitosan films extend the bread shelf life by three days. Comparative life-cycle data indicate 45–80% lower greenhouse gas emissions and land use than equivalent animal-derived ingredients. Collectively, the evidence positions insect-based ingredients as versatile, safe, and climate-smart tools to enhance food quality and sustainability, while outlining research gaps in allergen mitigation, consumer acceptance, and regulatory harmonization. Full article
(This article belongs to the Special Issue Insects and Their Derivatives for Human Practical Uses 3rd Edition)
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16 pages, 2260 KiB  
Article
From Shale to Value: Dual Oxidative Route for Kukersite Conversion
by Kristiina Kaldas, Kati Muldma, Aia Simm, Birgit Mets, Tiina Kontson, Estelle Silm, Mariliis Kimm, Villem Ödner Koern, Jaan Mihkel Uustalu and Margus Lopp
Processes 2025, 13(8), 2421; https://doi.org/10.3390/pr13082421 - 30 Jul 2025
Viewed by 183
Abstract
The increasing need for sustainable valorization of fossil-based and waste-derived materials has gained interest in converting complex organic matrices such as kerogen into valuable chemicals. This study explores a two-step oxidative strategy to decompose and valorize kerogen-rich oil shale, aiming to develop a [...] Read more.
The increasing need for sustainable valorization of fossil-based and waste-derived materials has gained interest in converting complex organic matrices such as kerogen into valuable chemicals. This study explores a two-step oxidative strategy to decompose and valorize kerogen-rich oil shale, aiming to develop a locally based source of aliphatic dicarboxylic acids (DCAs). The method combines air oxidation with subsequent nitric acid treatment to enable selective breakdown of the organic structure under milder conditions. Air oxidation was conducted at 165–175 °C using 1% KOH as an alkaline promoter and 40 bar oxygen pressure (or alternatively 185 °C at 30 bar), targeting 30–40% carbon conversion. The resulting material was then subjected to nitric acid oxidation using an 8% HNO3 solution. This approach yielded up to 23% DCAs, with pre-oxidation allowing a twofold reduction in acid dosage while maintaining efficiency. However, two-step oxidation was still accompanied by substantial degradation of the structure, resulting in elevated CO2 formation, highlighting the need to balance conversion and carbon retention. The process offers a possible route for transforming solid fossil residues into useful chemical precursors and supports the advancement of regionally sourced, sustainable DCA production from unconventional raw materials. Full article
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27 pages, 1128 KiB  
Article
Adaptive Multi-Hop P2P Video Communication: A Super Node-Based Architecture for Conversation-Aware Streaming
by Jiajing Chen and Satoshi Fujita
Information 2025, 16(8), 643; https://doi.org/10.3390/info16080643 - 28 Jul 2025
Viewed by 245
Abstract
This paper proposes a multi-hop peer-to-peer (P2P) video streaming architecture designed to support dynamic, conversation-aware communication. The primary contribution is a decentralized system built on WebRTC that eliminates reliance on a central media server by employing super node aggregation. In this architecture, video [...] Read more.
This paper proposes a multi-hop peer-to-peer (P2P) video streaming architecture designed to support dynamic, conversation-aware communication. The primary contribution is a decentralized system built on WebRTC that eliminates reliance on a central media server by employing super node aggregation. In this architecture, video streams from multiple peer nodes are dynamically routed through a group of super nodes, enabling real-time reconfiguration of the network topology in response to conversational changes. To support this dynamic behavior, the system leverages WebRTC data channels for control signaling and overlay restructuring, allowing efficient dissemination of topology updates and coordination messages among peers. A key focus of this study is the rapid and efficient reallocation of network resources immediately following conversational events, ensuring that the streaming overlay remains aligned with ongoing interaction patterns. While the automatic detection of such events is beyond the scope of this work, we assume that external triggers are available to initiate topology updates. To validate the effectiveness of the proposed system, we construct a simulation environment using Docker containers and evaluate its streaming performance under dynamic network conditions. The results demonstrate the system’s applicability to adaptive, naturalistic communication scenarios. Finally, we discuss future directions, including the seamless integration of external trigger sources and enhanced support for flexible, context-sensitive interaction frameworks. Full article
(This article belongs to the Special Issue Second Edition of Advances in Wireless Communications Systems)
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12 pages, 2577 KiB  
Article
Single-Atom Catalysts Dispersed on Graphitic Carbon Nitride (g-CN): Eley–Rideal-Driven CO-to-Ethanol Conversion
by Jing Wang, Qiuli Song, Yongchen Shang, Yuejie Liu and Jingxiang Zhao
Nanomaterials 2025, 15(14), 1111; https://doi.org/10.3390/nano15141111 - 17 Jul 2025
Viewed by 307
Abstract
The electrochemical reduction of carbon monoxide (COER) offers a promising route for generating value-added multi-carbon (C2+) products, such as ethanol, but achieving high catalytic performance remains a significant challenge. Herein, we performed comprehensive density functional theory (DFT) computations to evaluate CO-to-ethanol [...] Read more.
The electrochemical reduction of carbon monoxide (COER) offers a promising route for generating value-added multi-carbon (C2+) products, such as ethanol, but achieving high catalytic performance remains a significant challenge. Herein, we performed comprehensive density functional theory (DFT) computations to evaluate CO-to-ethanol conversion on single metal atoms anchored on graphitic carbon nitride (TM/g–CN). We showed that these metal atoms stably coordinate with edge N sites of g–CN to form active catalytic centers. Screening 20 TM/g–CN candidates, we identified V/g–CN and Zn/g–CN as optimal catalysts: both exhibit low free-energy barriers (<0.50 eV) for the key *CO hydrogenation steps and facilitate C–C coupling via an Eley–Rideal mechanism with a negligible kinetic barrier (~0.10 eV) to yield ethanol at low limiting potentials, which explains their superior COER performance. An analysis of d-band centers, charge transfer, and bonding–antibonding orbital distributions revealed the origin of their activity. This work provides theoretical insights and useful guidelines for designing high-performance single-atom COER catalysts. Full article
(This article belongs to the Section Theory and Simulation of Nanostructures)
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21 pages, 1847 KiB  
Article
Global Division of Responsibility Sharing: How Refugee Systems Operate Through the Economic Management of Mobility and Immobility
by Austin H. Vo and Michelle S. Dromgold-Sermen
Soc. Sci. 2025, 14(7), 434; https://doi.org/10.3390/socsci14070434 - 15 Jul 2025
Viewed by 260
Abstract
In 2023, there were approximately 32 million refugees globally. Nine out of the ten countries with the highest origins of refugees were in the Global South; conversely, only three of the ten countries hosting the highest numbers of refugees were in the Global [...] Read more.
In 2023, there were approximately 32 million refugees globally. Nine out of the ten countries with the highest origins of refugees were in the Global South; conversely, only three of the ten countries hosting the highest numbers of refugees were in the Global North. In this study, we introduce the conceptual framework of a global division of responsibility sharing to describe how functions of Global North countries as permanent “resettlement” countries and Global South countries as perpetual countries of “asylum” and “transit” constitute unequal burdens with unequal protections for refugees. We illustrate—theoretically and empirically—how the structural positions of state actors in a global network introduce and reify a global division in refugee flows. Empirically, we test and develop this framework with network analysis of refugee flows to countries of asylum from 1990 to 2015 in addition to employing data on monetary donations to the United Nations High Commissioner for Refugees (UNHCR) from 2017 to 2021. We (1) provide evidence of the structure and role of intermediary countries in refugee flows and (2) examine how UNHCR monetary aid conditions intermediary countries’ role of routing and transit. We illustrate how network constraints and monetary donations affect and constitute a global division in the management of historic and contemporary international refugee flows and explore the consequences of this global division for refugees’ access to resources and social and human rights. Full article
(This article belongs to the Special Issue Migration, Citizenship and Social Rights)
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20 pages, 1893 KiB  
Article
Acute Dermatotoxicity of Green-Synthesized Silver Nanoparticles (AgNPs) in Zebrafish Epidermis
by Grace Emily Okuthe and Busiswa Siguba
Toxics 2025, 13(7), 592; https://doi.org/10.3390/toxics13070592 - 15 Jul 2025
Viewed by 295
Abstract
Silver nanoparticles (AgNPs), lauded for their unique antibacterial and physicochemical attributes, are proliferating across industrial sectors, raising concerns about their environmental fate, in aquatic systems. While “green” synthesis offers a sustainable production route with reduced chemical byproducts, the safety of these AgNPs for [...] Read more.
Silver nanoparticles (AgNPs), lauded for their unique antibacterial and physicochemical attributes, are proliferating across industrial sectors, raising concerns about their environmental fate, in aquatic systems. While “green” synthesis offers a sustainable production route with reduced chemical byproducts, the safety of these AgNPs for aquatic fauna remains uncertain due to nanoparticle-specific effects. Conversely, mast cells play crucial roles in fish immunity, orchestrating innate and adaptive immune responses by releasing diverse mediators and recognizing danger signals. Goblet cells are vital for mucosal immunity and engaging in immune surveillance, regulation, and microbiota interactions. The interplay between these two cell types is critical for maintaining mucosal homeostasis, is central to defending against fish diseases and is highly responsive to environmental cues. This study investigates the acute dermatotoxicity of environmentally relevant AgNP concentrations (0, 0.031, 0.250, and 5.000 μg/L) on zebrafish epidermis. A 96 h assay revealed a biphasic response: initial mucin hypersecretion at lower AgNP levels, suggesting an early stress response, followed by a concentration-dependent collapse of mucosal integrity at higher exposures, with mucus degradation and alarm cell depletion. A rapid and generalized increase in epidermal mucus production was observed across all AgNP exposure groups within two hours of exposure. Further mechanistic insights into AgNP-induced toxicity were revealed by concentration-dependent alterations in goblet cell dynamics. Lower AgNP concentrations initially led to an increase in both goblet cell number and size. However, at the highest concentration, this trend reversed, with a significant decrease in goblet cell numbers and size evident between 48 and 96 h post-exposure. The simultaneous presence of neutral and acidic mucins indicates a dynamic epidermal response suggesting a primary physical barrier function, with acidic mucins specifically upregulated early on to enhance mucus viscosity, trap AgNPs, and inhibit pathogen invasion, a clear defense mechanism. The subsequent reduction in mucin-producing cells at higher concentrations signifies a critical breakdown of this protective strategy, leaving the epidermis highly vulnerable to damage and secondary infections. These findings highlight the vulnerability of fish epidermal defenses to AgNP contamination, which can potentially compromise osmoregulation and increase susceptibility to threats. Further mechanistic research is crucial to understand AgNP-induced epithelial damage to guide sustainable nanotechnology. Full article
(This article belongs to the Section Ecotoxicology)
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21 pages, 4142 KiB  
Review
Nanomaterial-Enabled Enhancements in Thylakoid-Based Biofuel Cells
by Amit Sarode and Gymama Slaughter
Nanomaterials 2025, 15(14), 1092; https://doi.org/10.3390/nano15141092 - 14 Jul 2025
Viewed by 365
Abstract
Thylakoid-based photosynthetic biofuel cells (TBFCs) harness the inherent light-driven electron transfer pathways of photosynthesis to enable sustainable solar-to-electrical energy conversion. While TBFCs offer a unique route toward biohybrid energy systems, their practical deployment is hindered by sluggish electron transfer kinetics, unstable redox mediators, [...] Read more.
Thylakoid-based photosynthetic biofuel cells (TBFCs) harness the inherent light-driven electron transfer pathways of photosynthesis to enable sustainable solar-to-electrical energy conversion. While TBFCs offer a unique route toward biohybrid energy systems, their practical deployment is hindered by sluggish electron transfer kinetics, unstable redox mediators, and inefficient interfacing between biological and electrode components. This review critically examines recent advances in TBFCs, with a focus on three key surface engineering strategies: (i) incorporation of nanostructured materials to enhance electrode conductivity and surface area; (ii) application of redox mediators to facilitate charge transfer between photosynthetic proteins and electrodes; and (iii) functional exploitation of individual thylakoid components, including Photosystem I (PSI) and Photosystem II (PSII), to augment photogenerated current output. By systematically evaluating current advancements, this review highlights the synergistic role of materials and biological components in advancing TBFC technology and offers insights into next generation biohybrid solar energy systems with enhanced efficiency and scalability. Full article
(This article belongs to the Special Issue Advanced Nanotechnology in Fuel Cells)
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15 pages, 3241 KiB  
Article
Cu@Pt Core–Shell Nanostructures for Ammonia Oxidation: Bridging Electrocatalysis and Electrochemical Sensing
by Bommireddy Naveen and Sang-Wha Lee
Inorganics 2025, 13(7), 241; https://doi.org/10.3390/inorganics13070241 - 11 Jul 2025
Viewed by 358
Abstract
Electro-oxidation of ammonia has emerged as a promising route for sustainable energy conversion and pollutant mitigation. In this study, we report the facile fabrication of dendritic Cu@Pt core–shell nanostructures electrodeposited on pencil graphite, forming an efficient electrocatalyst for the ammonia oxidation reaction (AOR). [...] Read more.
Electro-oxidation of ammonia has emerged as a promising route for sustainable energy conversion and pollutant mitigation. In this study, we report the facile fabrication of dendritic Cu@Pt core–shell nanostructures electrodeposited on pencil graphite, forming an efficient electrocatalyst for the ammonia oxidation reaction (AOR). The designed electrocatalyst exhibited high catalytic activity towards AOR, achieving high current density at very low potentials (−0.3 V vs. Ag/AgCl), with a lower Tafel slope of 16.4 mV/dec. The catalyst also demonstrated high electrochemical stability over 1000 potential cycles with a regeneration efficiency of 78%. In addition to catalysis, Cu@Pt/PGE facilitated very sensitive and selective electrochemical detection of ammonia nitrogen by differential pulse voltammetry, providing an extensive linear range (1 μM to 1 mM) and a low detection limit of 0.78 μM. The dual functionality of Cu@Pt highlights its potential in enhancing ammonia-based fuel cells and monitoring ammonia pollution in aquatic environments, thereby contributing to the development of sustainable energy and environmental technologies. Full article
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18 pages, 1085 KiB  
Article
Overcoming the Reversibility in the Diels–Alder Reaction of Bio-Based Electron-Poor Furans with Maleimides Through Liquid-to-Solid Phase Transition
by Konstantin I. Galkin, Daria V. Zakharova, Rinat R. Aysin, Anastasia A. Danshina, Alexandra M. Pak, Irina V. Sandulenko, Roman A. Novikov and Ksenia S. Egorova
Int. J. Mol. Sci. 2025, 26(14), 6550; https://doi.org/10.3390/ijms26146550 - 8 Jul 2025
Viewed by 379
Abstract
In the chemistry of bio-based furans, the Diels–Alder reaction plays an important role as a renewable route for the synthesis of fuels, fine chemicals, and monomers. Nonetheless, the unfavorable kinetic and thermodynamic parameters inherent to the Diels–Alder reaction involving furans as dienes often [...] Read more.
In the chemistry of bio-based furans, the Diels–Alder reaction plays an important role as a renewable route for the synthesis of fuels, fine chemicals, and monomers. Nonetheless, the unfavorable kinetic and thermodynamic parameters inherent to the Diels–Alder reaction involving furans as dienes often lead to the reversibility of cycloaddition, resulting in decreased equilibrium conversion and diastereoselectivity. In this study, we present a new strategy for overcoming the problem of reversibility in chemical reactions. We demonstrate that conducting the reaction under solvent-free conditions can facilitate the transition from a molten state formed by the initial reactants to a solid phase containing the reaction product along with an excess of the initial substrate. According to our results, such a liquid-to-solid transition of the reaction mixture can lead to exceptionally high conversion and diastereoselectivity in the furan–maleimide Diels–Alder reaction, particularly for challenging electron-poor furanic substrates. Our approach enables the reversible furan–maleimide Diels–Alder reaction to be performed in a cleaner and more environmentally friendly manner, free from the complexities associated with the use of solvents and the need for purification from side products. Full article
(This article belongs to the Section Physical Chemistry and Chemical Physics)
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18 pages, 4443 KiB  
Article
Comparative Study on Ni/MgO-Al2O3 Catalysts for Dry and Combined Steam–CO2 Reforming of Methane
by Tingting Zheng, Yuqi Zhou, Hongjie Cui and Zhiming Zhou
Catalysts 2025, 15(7), 659; https://doi.org/10.3390/catal15070659 - 6 Jul 2025
Viewed by 378
Abstract
The dry reforming of methane (DRM) and the combined steam–CO2 reforming of methane (CSCRM) are promising routes for syngas production while simultaneously utilizing two major greenhouse gases—CO2 and CH4. In this study, a series of Ni/MgO-Al2O3 [...] Read more.
The dry reforming of methane (DRM) and the combined steam–CO2 reforming of methane (CSCRM) are promising routes for syngas production while simultaneously utilizing two major greenhouse gases—CO2 and CH4. In this study, a series of Ni/MgO-Al2O3 catalysts with varying Mg/Al molar ratios (Ni/MgAl(x), x = 0.5–0.9), along with Ni/MgO and Ni/Al2O3, were synthesized, characterized, and evaluated in both the DRM and CSCRM. Ni/MgO and Ni/Al2O3 exhibited a lower activity due to fewer active sites and a poor CH4/CO2 activation balance. In contrast, Ni/MgAl(0.6), Ni/MgAl(0.7), and Ni/MgAl(0.8) showed an enhanced activity, attributed to more abundant active sites and a more balanced activation of CH4 and CO2. Ni/MgAl(0.7) delivered the best DRM performance, whereas Ni/MgAl(0.8) was optimal for the CSCRM, likely due to its greater number of strong basic sites promoting CO2 and H2O adsorption. At 750 °C and 0.1 MPa over 100 h, Ni/MgAl(0.7) maintained a stable DRM performance (77% CH4 and 86% CO2 conversion; H2/CO = 0.9) at 120 L/(gcat·h), while Ni/MgAl(0.8) achieved a stable CSCRM performance (80% CH4 and 62% CO2 conversion; H2/CO = 2.1) at 132 L/(gcat·h). This study provides valuable insights into designing efficient Ni/MgO-Al2O3 catalysts for targeted syngas production. Full article
(This article belongs to the Section Catalytic Reaction Engineering)
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26 pages, 5399 KiB  
Article
Microwave-Assisted Pyrolysis of Polyethylene and Polypropylene from End-of-Life Vehicles: Hydrogen Production and Energy Valorization
by Grigore Psenovschi, Ioan Calinescu, Alexandru Fiti, Ciprian-Gabriel Chisega-Negrila, Sorin-Lucian Ionascu and Lucica Barbes
Sustainability 2025, 17(13), 6196; https://doi.org/10.3390/su17136196 - 6 Jul 2025
Viewed by 602
Abstract
Plastic waste is currently a major concern in Romania due to the annual increase in quantities generated from anthropogenic and industrial activities, especially from end-of-life vehicles (ELVs), and the need to reduce environmental impact. This study investigates an alternative valorization route for polypropylene [...] Read more.
Plastic waste is currently a major concern in Romania due to the annual increase in quantities generated from anthropogenic and industrial activities, especially from end-of-life vehicles (ELVs), and the need to reduce environmental impact. This study investigates an alternative valorization route for polypropylene (PP) and polyethylene (PE) plastic waste through microwave-assisted pyrolysis, aiming to maximize conversion into gaseous products, particularly hydrogen-rich gas. A monomode microwave reactor was employed, using layered configurations of plastic feedstock, silicon carbide as a microwave susceptor, and activated carbon as a catalyst. The influence of catalyst loading, reactor configuration, and plastic type was assessed through systematic experiments. Results showed that technical-grade PP, under optimal conditions, yielded up to 81.4 wt.% gas with a hydrogen concentration of 45.2 vol.% and a hydrogen efficiency of 44.8 g/g. In contrast, PE and mixed PP + PE waste displayed lower hydrogen performance, particularly when containing inorganic fillers. For all types of plastics studied, the gaseous fractions obtained have a high calorific value (46,941–55,087 kJ/kg) and at the same time low specific CO2 emissions (4.4–6.1 × 10−5 kg CO2/kJ), which makes these fuels very efficient and have a low carbon footprint. Comparative tests using conventional heating revealed significantly lower hydrogen yields (4.77 vs. 19.7 mmol/g plastic). These findings highlight the potential of microwave-assisted pyrolysis as an efficient method for transforming ELV-derived plastic waste into energy carriers, offering a pathway toward low-carbon, resource-efficient waste management. Full article
(This article belongs to the Special Issue Novel and Scalable Technologies for Sustainable Waste Management)
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12 pages, 811 KiB  
Article
Kynurenic Acid Synthesis from D-Kynurenine in the Cerebellum: A Distinct Role of D-Amino Acid Oxidase
by Verónica Pérez de la Cruz, Korrapati V. Sathyasaikumar, Xiao-Dan Wang, Tonali Blanco Ayala, Sarah Beggiato, Dinora F. González Esquivel, Benjamin Pineda and Robert Schwarcz
Cells 2025, 14(13), 1030; https://doi.org/10.3390/cells14131030 - 5 Jul 2025
Viewed by 511
Abstract
The enzymatic formation of kynurenic acid (KYNA), a neuromodulator metabolite of the kynurenine pathway (KP) of tryptophan metabolism, in the mammalian brain is widely attributed to kynurenine aminotransferase II (KATII). However, an alternative biosynthetic route, involving the conversion of D-kynurenine (D-KYN) to KYNA [...] Read more.
The enzymatic formation of kynurenic acid (KYNA), a neuromodulator metabolite of the kynurenine pathway (KP) of tryptophan metabolism, in the mammalian brain is widely attributed to kynurenine aminotransferase II (KATII). However, an alternative biosynthetic route, involving the conversion of D-kynurenine (D-KYN) to KYNA by D-amino acid oxidase (D-AAO), may play a role as well. In the present study, we first confirmed that purified D-AAO efficiently converted D-KYN—but not L-KYN—to KYNA. We then examined KYNA formation from D-KYN (100 µM) in vitro, using tissue homogenates from several human brain regions. KYNA was generated in all areas, with D-AAO-specific production being most effective by far in the cerebellum. Next tested in homogenates from rat cerebellum, KYNA neosynthesis was significantly reduced by D-AAO inhibition, whereas KATII inhibition had no effect. Finally, KYNA production was assessed by in vivo microdialysis in rat cerebellum. Local D-KYN perfusion, alone and in combination with inhibitors of D-AAO (kojic acid) or aminotransferases (AOAA), caused a substantive increase in extracellular KYNA levels. This effect was attenuated dose-dependently by micromolar concentrations of kojic acid, whereas co-perfusion of AOAA (1 mM) was ineffective. Together, our findings indicate that D-AAO should be considered a major contributor to KYNA production in the cerebellum, highlighting region-specific qualitative differences in cerebral KYNA metabolism. Full article
(This article belongs to the Section Cell Signaling)
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19 pages, 2086 KiB  
Article
Strategic Doping for Precise Structural Control and Intense Photocurrents Under Visible Light in Ba2M0.4Bi1.6O6 (M = La, Ce, Pr, Pb, Y) Double Perovskites
by Tirong Guo, Wen Tian Fu and Huub J. M. de Groot
Nanomaterials 2025, 15(13), 1039; https://doi.org/10.3390/nano15131039 - 4 Jul 2025
Viewed by 323
Abstract
Developing functional perovskites is important for advancing solar energy conversion technologies. This study investigates the effects of dopants on the structural, optical, electronic, and solar conversion performances of Ba2M0.4Bi1.6O6 double perovskites. X-ray diffraction (XRD) and Rietveld [...] Read more.
Developing functional perovskites is important for advancing solar energy conversion technologies. This study investigates the effects of dopants on the structural, optical, electronic, and solar conversion performances of Ba2M0.4Bi1.6O6 double perovskites. X-ray diffraction (XRD) and Rietveld refinement confirm crystallization in the I2/m space group (M = La, Ce, Pr, Pb), and Fm3¯m and I2/m space groups (M = Y). The B1-O-B2 structure modulates to highly ordered (M = La, Y), partially ordered (M = Pr), or disordered (M = Ce, Pb). UV-vis spectra show strong light absorption, with Tauc plots estimating ~1.57 eV (M = La) and ~1.73 eV (M = Pr) optical band gaps. Under AM 1.5G illumination, the M = La photoelectrode generates photocurrents of 1 mA cm−2 at 0.3 VRHE, surpassing M = Ce and Pb (1 μm, 4-times spin-coating). Increasing its thickness to 7.7 μm (4-times dip-coating) further enhances the photocurrents to 2.3 mA cm−2 at 0.2 VRHE, outperforming all counterparts due to improved stability. Fine-tuning crystal and electronic structures via strategic B-site doping provides a new route for engineering Ba2Bi2O6-based double perovskites for broad solar energy conversion applications. Full article
(This article belongs to the Special Issue Organic/Perovskite Solar Cell)
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