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34 pages, 606 KiB  
Article
Role of Thermal Fluctuations in Nucleation of Three-Flavor Quark Matter
by Mirco Guerrini, Giuseppe Pagliara, Andrea Lavagno and Alessandro Drago
Universe 2025, 11(8), 258; https://doi.org/10.3390/universe11080258 - 5 Aug 2025
Abstract
We present a framework that aims to investigate the role of thermal fluctuations in matter composition and color superconductivity in the nucleation of three-flavor deconfined quark matter in the typical conditions of high-energy astrophysical systems related to compact stars. It is usually assumed [...] Read more.
We present a framework that aims to investigate the role of thermal fluctuations in matter composition and color superconductivity in the nucleation of three-flavor deconfined quark matter in the typical conditions of high-energy astrophysical systems related to compact stars. It is usually assumed that the flavor composition is locally fixed during the formation of the first seed of deconfined quark matter, since a weak interaction acts too slowly to re-equilibrate flavors. However, the matter composition fluctuates around its average equilibrium values at the typical temperatures of high-energy astrophysical processes. Here, we extend our previous two-flavor nucleation formalism to a three-flavor case. We develop a thermodynamic framework incorporating finite-size effects and thermal fluctuations in the local composition to compute the nucleation probability as the product of droplet formation and composition fluctuation rates. Moreover, we discuss the role of color superconductivity in nucleation, arguing that it can play a role only in systems larger than the typical coherence length of diquark pairs. We found that thermal fluctuations in the matter composition led to lowering the potential barrier between the metastable hadronic phase and the stable quark phase. Moreover, the formation of diquark pairs reduced the critical radius and thus the potential barrier in the low baryon density and temperature regime. Full article
(This article belongs to the Special Issue Compact Stars in the QCD Phase Diagram 2024)
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16 pages, 1652 KiB  
Review
Lipid−lncRNA Crossroads: An Overview of Interactions Between Lipids and lncRNA
by Andrea Bayona-Hernandez, Ana Miladinović, Ludovica Antiga, Pavel Hozak, Martin Sztacho and Enrique Castano
Cells 2025, 14(15), 1193; https://doi.org/10.3390/cells14151193 - 2 Aug 2025
Viewed by 217
Abstract
Long non-coding RNAs (lncRNAs) interact with a variety of biomolecules, including DNA, mRNAs, microRNA, and proteins, to regulate various cellular processes. Recently, their interactions with lipids have gained increasing attention as an emerging research area. Both lipids and lncRNAs play central roles in [...] Read more.
Long non-coding RNAs (lncRNAs) interact with a variety of biomolecules, including DNA, mRNAs, microRNA, and proteins, to regulate various cellular processes. Recently, their interactions with lipids have gained increasing attention as an emerging research area. Both lipids and lncRNAs play central roles in cellular regulation, and growing evidence reveals a complex interplay between these molecules. These interactions contribute to key biological functions, such as cancer progression, lipid droplet transport, autophagy, liquid−liquid phase separation, and the formation of organelles without membranes. Understanding the lipid−lncRNA interface opens new avenues for unraveling cellular regulation and disease mechanisms, holding great potential not only for elucidating the fundamental aspects of cellular biology but also for identifying innovative therapeutic targets for metabolic disorders and cancer. This review highlights the biological relevance of lipid–lncRNA interactions by exploring their roles in cellular organization, regulation, and diseases, including metabolic and cancer-related disorders. Full article
(This article belongs to the Section Cell Microenvironment)
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16 pages, 2155 KiB  
Article
Emulsifying Properties of Oat Protein/Casein Complex Prepared Using Atmospheric Cold Plasma with pH Shifting
by Yang Teng, Mingjuan Ou, Jihuan Wu, Ting Jiang, Kaige Zheng, Yuxing Guo, Daodong Pan, Tao Zhang and Zhen Wu
Foods 2025, 14(15), 2702; https://doi.org/10.3390/foods14152702 - 31 Jul 2025
Viewed by 226
Abstract
An oat protein isolate is an ideal raw material for producing a wide range of plant-based products. However, oat protein exhibits weak functional properties, particularly in emulsification. Casein-based ingredients are commonly employed to enhance emulsifying properties as a general practice in the food [...] Read more.
An oat protein isolate is an ideal raw material for producing a wide range of plant-based products. However, oat protein exhibits weak functional properties, particularly in emulsification. Casein-based ingredients are commonly employed to enhance emulsifying properties as a general practice in the food industry. pH-shifting processing is a straightforward method to partially unfold protein structures. This study modified a mixture of an oat protein isolate (OPI) and casein by combining a pH adjustment (adjusting the pH of two solutions to 12, mixing them at a 3:7 ratio, and maintaining the pH at 12 for 2 h) with an atmospheric cold plasma (ACP) treatment to improve the emulsifying properties. The results demonstrated that the ACP treatment significantly enhanced the solubility of the OPI/casein mixtures, with a maximum solubility of 82.63 ± 0.33%, while the ζ-potential values were approximately −40 mV, indicating that all the samples were fairly stable. The plasma-induced increase in surface hydrophobicity supported greater protein adsorption and redistribution at the oil/water interface. After 3 min of treatment, the interfacial pressure peaked at 8.32 mN/m. Emulsions stabilized with the modified OPI/casein mixtures also exhibited a significant droplet size reduction upon extending the ACP treatment to 3 min, decreasing from 5.364 ± 0.034 μm to 3.075 ± 0.016 μm. The resulting enhanced uniformity in droplet size distribution signified the formation of a robust interfacial film. Moreover, the ACP treatment effectively enhanced the emulsifying activity of the OPI/casein mixtures, reaching (179.65 ± 1.96 m2/g). These findings highlight the potential application value of OPI/casein mixtures in liquid dairy products. In addition, dairy products based on oat protein are more conducive to sustainable development than traditional dairy products. Full article
(This article belongs to the Special Issue Food Proteins: Innovations for Food Technologies)
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32 pages, 7358 KiB  
Article
XYLT1 Deficiency of Human Mesenchymal Stem Cells: Impact on Osteogenic, Chondrogenic, and Adipogenic Differentiation
by Thanh-Diep Ly, Vanessa Schmidt, Matthias Kühle, Kai Oliver Böker, Bastian Fischer, Cornelius Knabbe and Isabel Faust-Hinse
Int. J. Mol. Sci. 2025, 26(15), 7363; https://doi.org/10.3390/ijms26157363 - 30 Jul 2025
Viewed by 220
Abstract
Xylosyltransferase-I (XT-I) plays a crucial role in skeletal development and cartilage integrity. An XT-I deficiency is linked to severe bone disorders, such as Desbuquois dysplasia type 2. While animal models have provided insights into XT-I’s role during skeletal development, its specific effects on [...] Read more.
Xylosyltransferase-I (XT-I) plays a crucial role in skeletal development and cartilage integrity. An XT-I deficiency is linked to severe bone disorders, such as Desbuquois dysplasia type 2. While animal models have provided insights into XT-I’s role during skeletal development, its specific effects on adult bone homeostasis, particularly in human mesenchymal stem cell (hMSC) differentiation, remain unclear. This study investigates how XT-I deficiency impacts the differentiation of hMSCs into chondrocytes, osteoblasts, and adipocytes—key processes in bone formation and repair. The aim of this study was to elucidate for the first time the molecular mechanisms by which XT-I deficiency leads to impaired bone homeostasis. Using CRISPR-Cas9-mediated gene editing, we generated XYLT1 knockdown (KD) hMSCs to assess their differentiation potential. Our findings revealed significant disruption in the chondrogenic differentiation in KD hMSCs, characterized by the altered expression of regulatory factors and extracellular matrix components, suggesting premature chondrocyte hypertrophy. Despite the presence of perilipin-coated lipid droplets in the adipogenic pathway, the overall leptin mRNA and protein expression was reduced in KD hMSCs, indicating a compromised lipid metabolism. Conversely, osteogenic differentiation was largely unaffected, with KD and wild-type hMSCs exhibiting comparable mineralization processes, indicating that critical aspects of osteogenesis were preserved despite the XYLT1 deficiency. In summary, these results underscore XT-I’s pivotal role in regulating differentiation pathways within the bone marrow niche, influencing cellular functions critical for skeletal health. A deeper insight into bone biology may pave the way for the development of innovative therapeutic approaches to improve bone health and treat skeletal disorders. Full article
(This article belongs to the Special Issue Molecular Insight into Bone Diseases)
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12 pages, 4156 KiB  
Article
Harnessing Nanoporous Hexagonal Structures to Control the Coffee Ring Effect and Enhance Particle Patterning
by Yu Ju Han, Myung Seo Kim, Seong Min Yoon, Seo Na Yoon, Woo Young Kim, Seok Kim and Young Tae Cho
Molecules 2025, 30(15), 3146; https://doi.org/10.3390/molecules30153146 - 27 Jul 2025
Viewed by 308
Abstract
The coffee-ring effect, while harnessed in diverse fields such as biosensing and printing, poses challenges for achieving uniform particle deposition. Controlling this phenomenon is thus essential for precision patterning. This study proposes a novel method to regulate coffee-ring formation by tuning surface wettability [...] Read more.
The coffee-ring effect, while harnessed in diverse fields such as biosensing and printing, poses challenges for achieving uniform particle deposition. Controlling this phenomenon is thus essential for precision patterning. This study proposes a novel method to regulate coffee-ring formation by tuning surface wettability via integrated nanoporous and hexagonal microstructures. Four distinct surface types were fabricated using UV nanoimprint lithography: planar, porous planar, hexagonal wall, and porous hexagonal wall. The evaporation behavior of colloidal droplets and subsequent particle aggregation were analyzed through contact angle measurements and confocal microscopy. Results demonstrated that nanoscale porosity significantly increased surface wettability and accelerated evaporation, while the hexagonal pattern enhanced droplet stability and suppressed contact line movement. The porous hexagonal surface, in particular, enabled the formation of connected dual-ring patterns with higher particle accumulation near the contact edge. This synergistic design facilitated both stable evaporation and improved localization of particles. The findings provide a quantitative basis for applying patterned porous surfaces in evaporation-driven platforms, with implications for enhanced sensitivity and reproducibility in surface-enhanced Raman scattering (SERS) and other biosensing applications. Full article
(This article belongs to the Special Issue Novel Porous Materials for Environmental Applications)
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22 pages, 8824 KiB  
Article
Pro-Inflammatory Microglia Exacerbate High-Altitude-Induced Cognitive Impairment by Driving Lipid Droplet Accumulation in Astrocytes
by Xiaoyang Fan, Sitong Cao, Yujie Fang, Li Zhu and Xueting Wang
Antioxidants 2025, 14(8), 918; https://doi.org/10.3390/antiox14080918 - 26 Jul 2025
Viewed by 556
Abstract
High-altitude cognitive impairment (HACI) results from acute or chronic exposure to hypoxic conditions. Brain lipid homeostasis is crucial for cognitive function, and lipid droplet (LD) accumulation in glia cells is linked to cognitive decline in aging and stroke. However, whether high-altitude exposure affects [...] Read more.
High-altitude cognitive impairment (HACI) results from acute or chronic exposure to hypoxic conditions. Brain lipid homeostasis is crucial for cognitive function, and lipid droplet (LD) accumulation in glia cells is linked to cognitive decline in aging and stroke. However, whether high-altitude exposure affects brain lipid homeostasis is unclear. Microglia, key regulators of brain homeostasis and inflammation, play a significant role in pathological cognitive impairment and are implicated in LD formation. This study investigates whether lipid dysregulation contributes to HACI and explores microglia-driven mechanisms and potential interventions. Mice were exposed to a simulated 7000 m altitude for 48 h, followed by a week of recovery. Cognitive function and LD accumulation in brain cells were assessed. Microglia were depleted using PLX5622, and mice were exposed to hypoxia or lipopolysaccharide (LPS) to validate microglia’s role in driving astrocytic LD accumulation and cognitive decline. Minocycline was used to inhibit inflammation. In vitro, co-culture systems of microglia and astrocytes were employed to confirm microglia-derived pro-inflammatory factors’ role in astrocytic LD accumulation. Hypobaric hypoxia exposure induced persistent cognitive impairment and LD accumulation in hippocampal astrocytes and microglia. Microglia depletion alleviated cognitive deficits and reduced astrocytic LD accumulation. Hypoxia or LPS did not directly cause LD accumulation in astrocytes but activated microglia to release IL-1β, inducing astrocytic LD accumulation. Microglia depletion also mitigated LPS-induced cognitive impairment and astrocytic LD accumulation. Minocycline reduced hypoxia-induced LD accumulation in co-cultured astrocytes and improved cognitive function. Hypoxia triggers pro-inflammatory microglial activation, leading to LD accumulation and the release of IL-1β, which drives astrocytic LD accumulation and neuroinflammation, exacerbating HACI. Minocycline effectively restores brain lipid homeostasis and mitigates cognitive impairment. This study provides novel insights into HACI mechanisms and suggests potential therapeutic strategies. Full article
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18 pages, 6124 KiB  
Article
Extraction of Alumina and Alumina-Based Cermets from Iron-Lean Red Muds Using Carbothermic Reduction of Silica and Iron Oxides
by Rita Khanna, Dmitry Zinoveev, Yuri Konyukhov, Kejiang Li, Nikita Maslennikov, Igor Burmistrov, Jumat Kargin, Maksim Kravchenko and Partha Sarathy Mukherjee
Sustainability 2025, 17(15), 6802; https://doi.org/10.3390/su17156802 - 26 Jul 2025
Viewed by 435
Abstract
A novel strategy has been developed for extracting value-added resources from iron-lean, high-alumina- and -silica-containing red muds (RMs). With little or no recycling, such RMs are generally destined for waste dumps. Detailed results are presented on the carbothermic reduction of 100% RM (29.3 [...] Read more.
A novel strategy has been developed for extracting value-added resources from iron-lean, high-alumina- and -silica-containing red muds (RMs). With little or no recycling, such RMs are generally destined for waste dumps. Detailed results are presented on the carbothermic reduction of 100% RM (29.3 wt.% Fe2O3, 22.2 wt.% Al2O3, 20.0 wt.% SiO2, 1.2 wt.% CaO, 12.2 wt.% Na2O) and its 2:1 blends with Fe2O3 and red mill scale (MS). Synthetic graphite was used as the reductant. Carbothermic reduction of RM and blends was carried out in a Tamman resistance furnace at 1650 °C for 20 min in an Ar atmosphere. Reduction residues were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), elemental mapping and X-ray diffraction (XRD). Small amounts of Fe3Si alloys, alumina, SiC and other oxide-based residuals were detected in the carbothermic residue of 100% RM. A number of large metallic droplets of Fe–Si alloys were observed for RM/Fe2O3 blends; no aluminium was detected in these metallic droplets. A clear segregation of alumina was observed as a separate phase. For the RM/red MS blends, a number of metallic Fe–Si droplets were seen embedded in an alumina matrix in the form of a cermet. This study has shown the regeneration of alumina and the formation of alumina-based cermets, Fe–Si alloys and SiC during carbothermic reduction of RM and its blends. This innovative recycling strategy could be used for extracting value-added resources from iron-lean RMs, thereby enhancing process productivity, cost-effectiveness of alumina regeneration, waste utilization and sustainable developments in the field. Full article
(This article belongs to the Special Issue Sustainable Materials, Waste Management, and Recycling)
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13 pages, 1394 KiB  
Article
Cucurbitacin E Suppresses Adipogenesis and Lipid Accumulation in 3T3-L1 Adipocytes Without Cytotoxicity
by Tien-Chou Soong, Kuan-Ting Lee, Yi-Chiang Hsu and Tai-Hsin Tsai
Biomedicines 2025, 13(8), 1826; https://doi.org/10.3390/biomedicines13081826 - 25 Jul 2025
Viewed by 307
Abstract
Background: Cucurbitacin E (CuE), a natural tetracyclic triterpenoid compound extracted from the melon stems of Cucurbitaceae plants, has been reported to exhibit anti-inflammatory and anti-cancer properties, along with the ability to enhance cellular immunity. However, its role and molecular mechanism in regulating [...] Read more.
Background: Cucurbitacin E (CuE), a natural tetracyclic triterpenoid compound extracted from the melon stems of Cucurbitaceae plants, has been reported to exhibit anti-inflammatory and anti-cancer properties, along with the ability to enhance cellular immunity. However, its role and molecular mechanism in regulating lipid metabolism and adipogenesis remain unclear. This study aims to investigate the potential anti-adipogenic and anti-obesity effects of CuE in 3T3-L1 adipocytes. Materials and Methods: 3T3-L1 preadipocytes were cultured and induced to differentiate using a standard adipogenic cocktail containing dexamethasone, 3-isobutyl-1-methylxanthine (IBMX), and insulin (DMI). CuE was administered during the differentiation process at various concentrations. Lipid accumulation was assessed using Oil Red O staining, and cell viability was evaluated via the MTT assay. To determine whether CuE induced apoptosis or necrosis, flow cytometry was performed using annexin V/PI staining. Additional molecular analyses, such as Western blotting and RT-PCR, were used to examine the expression of key adipogenic markers. Results: Treatment with CuE significantly reduced lipid droplet formation in DMI-induced 3T3-L1 adipocytes in a dose-dependent manner, as shown by decreased Oil Red O staining. Importantly, CuE did not induce apoptosis or necrosis in 3T3-L1 cells at effective concentrations, indicating its safety toward normal adipocytes. Moreover, CuE treatment downregulated the expression of adipogenic markers such as PPARγ and C/EBPα at both mRNA and protein levels. Discussion: Our findings suggest that CuE exerts a non-cytotoxic inhibitory effect on adipocyte differentiation and lipid accumulation. This anti-adipogenic effect is likely mediated through the suppression of key transcription factors involved in adipogenesis. The absence of cytotoxicity supports the potential application of CuE as a safe bioactive compound for obesity management. Further investigation is warranted to elucidate the upstream signaling pathways and in vivo efficacy of CuE. Conclusions: Cucurbitacin E effectively inhibits adipogenesis in 3T3-L1 adipocytes without inducing cytotoxic effects, making it a promising candidate for the development of functional foods or therapeutic agents aimed at preventing or treating obesity. This study provides new insights into the molecular basis of CuE’s anti-obesity action and highlights its potential as a natural lipogenesis inhibitor. Full article
(This article belongs to the Section Cell Biology and Pathology)
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23 pages, 5262 KiB  
Article
Designing Gel-Inspired Food-Grade O/W Pickering Emulsions with Bacterial Nanocellulose–Chitosan Complexes
by Antiopi Vardaxi, Eftychios Apostolidis, Ioanna G. Mandala, Stergios Pispas, Aristeidis Papagiannopoulos and Erminta Tsouko
Gels 2025, 11(8), 577; https://doi.org/10.3390/gels11080577 - 24 Jul 2025
Viewed by 331
Abstract
This study explored the potential of chitosan (CH)/bacterial cellulose (BC) complexes (0.5% w/v) as novel emulsifiers to stabilize oil-in-water (o/w) Pickering emulsions (20% v/v sunflower oil), with a focus on their gel-like behavior. Emulsions were prepared using CH [...] Read more.
This study explored the potential of chitosan (CH)/bacterial cellulose (BC) complexes (0.5% w/v) as novel emulsifiers to stabilize oil-in-water (o/w) Pickering emulsions (20% v/v sunflower oil), with a focus on their gel-like behavior. Emulsions were prepared using CH combined with BNC derived via H2SO4 (BNC1) or H2SO4-HCl (BNC2) hydrolysis. Increasing BNC content improved stability by reducing phase separation and enhancing viscosity, while CH contributed interfacial activity and electrostatic stabilization. CH/BNC125:75 emulsions showed the highest stability, maintaining an emulsion stability index (ESI) of up to 100% after 3 days, with minimal change in droplet size (Rh ~8.5–8.8 μm) and a positive ζ-potential (15.1–29.8 mV), as confirmed by dynamic/electrophoretic light scattering. pH adjustment to 4 and 10 had little effect on their ESI, while ionic strength studies showed that 0.1 M NaCl caused only a slight increase in droplet size combined with the highest ζ-potential (−35.2 mV). Higher salt concentrations led to coalescence and disruption of their gel-like structure. Rheological analysis of CH/BNC125:75 emulsions revealed shear-thinning behavior and dominant elastic properties (G′ > G″), indicating a soft gel network. Incorporating sunflower-seed protein isolates into CH/BNC1 (25:75) emulsions led to coacervate formation (three-layer system), characterized by a decrease in droplet size and an increase in ζ-potential (up to 32.8 mV) over 7 days. These findings highlight CH/BNC complexes as sustainable stabilizers for food-grade Pickering emulsions, supporting the development of biopolymer-based emulsifiers aligned with bioeconomy principles. Full article
(This article belongs to the Special Issue Recent Advances in Food Gels (2nd Edition))
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18 pages, 3268 KiB  
Article
In Situ Emulsification Synergistic Self-Profile Control System on Offshore Oilfield: Key Influencing Factors and EOR Mechanism
by Liangliang Wang, Minghua Shi, Jiaxin Li, Baiqiang Shi, Xiaoming Su, Yande Zhao, Qing Guo and Yuan Yuan
Energies 2025, 18(14), 3879; https://doi.org/10.3390/en18143879 - 21 Jul 2025
Viewed by 280
Abstract
The in situ emulsification synergistic self-profile control system has wide application prospects for efficient development on offshore oil reservoirs. During water flooding in Bohai heavy oil reservoirs, random emulsification occurs with superimposed Jamin effects. Effectively utilizing this phenomenon can enhance the efficient development [...] Read more.
The in situ emulsification synergistic self-profile control system has wide application prospects for efficient development on offshore oil reservoirs. During water flooding in Bohai heavy oil reservoirs, random emulsification occurs with superimposed Jamin effects. Effectively utilizing this phenomenon can enhance the efficient development of offshore oilfields. This study addresses the challenges hindering water flooding development in offshore oilfields by investigating the emulsification mechanism and key influencing factors based on oil–water emulsion characteristics, thereby proposing a novel in situ emulsification flooding method. Based on a fundamental analysis of oil–water properties, key factors affecting emulsion stability were examined. Core flooding experiments clarified the impact of spontaneous oil–water emulsification on water flooding recovery. Two-dimensional T1–T2 NMR spectroscopy was employed to detect pure fluid components, innovating the method for distinguishing oil–water distribution during flooding and revealing the characteristics of in situ emulsification interactions. The results indicate that emulsions formed between crude oil and formation water under varying rheometer rotational speeds (500–2500 r/min), water cuts (30–80%), and emulsification temperatures (40–85 °C) are all water-in-oil (W/O) type. Emulsion viscosity exhibits a positive correlation with shear rate, with droplet sizes primarily ranging between 2 and 7 μm and a viscosity amplification factor up to 25.8. Emulsion stability deteriorates with increasing water cut and temperature. Prolonged shearing initially increases viscosity until stabilization. In low-permeability cores, spontaneous oil–water emulsification occurs, yielding a recovery factor of only 30%. For medium- and high-permeability cores (water cuts of 80% and 50%, respectively), recovery factors increased by 9.7% and 12%. The in situ generation of micron-scale emulsions in porous media achieved a recovery factor of approximately 50%, demonstrating significantly enhanced oil recovery (EOR) potential. During emulsification flooding, the system emulsifies oil at pore walls, intensifying water–wall interactions and stripping wall-adhered oil, leading to increased T2 signal intensity and reduced relaxation time. Oil–wall interactions and collision frequencies are lower than those of water, which appears in high-relaxation regions (T1/T2 > 5). The two-dimensional NMR spectrum clearly distinguishes oil and water distributions. Full article
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23 pages, 9638 KiB  
Article
A Study on the Influence Mechanism of the Oil Injection Distance on the Oil Film Distribution Characteristics of the Gear Meshing Zone
by Wentao Zhao, Lin Li and Gaoan Zheng
Machines 2025, 13(7), 606; https://doi.org/10.3390/machines13070606 - 14 Jul 2025
Viewed by 309
Abstract
Under the trend of lightweight and high-efficiency development in industrial equipment, precise regulation of lubrication in gear reducers is a key breakthrough for enhancing transmission system efficiency and reliability. This study establishes a three-dimensional numerical model for high-speed gear jet lubrication using computational [...] Read more.
Under the trend of lightweight and high-efficiency development in industrial equipment, precise regulation of lubrication in gear reducers is a key breakthrough for enhancing transmission system efficiency and reliability. This study establishes a three-dimensional numerical model for high-speed gear jet lubrication using computational fluid dynamics (CFD) and dynamic mesh technology. By implementing the volume of fluid (VOF) multiphase flow model and the standard k-ω turbulence model, the study simulates the dynamic distribution of lubricant in gear meshing zones and analyzes critical parameters such as the oil volume fraction, eddy viscosity, and turbulent kinetic energy. The results show that reducing the oil injection distance significantly enhances lubricant coverage and continuity: as the injection distance increases from 4.8 mm to 24 mm, the lubricant shifts from discrete droplets to a dense wedge-shaped film, mitigating lubrication failure risks from secondary atomization and energy loss. The optimized injection distance also improves the spatial stability of eddy viscosity and suppresses excessive dissipation of turbulent kinetic energy, enhancing both the shear-load capacity and thermal management. Dynamic data from monitoring point P show that reducing the injection distance stabilizes lubricant velocity and promotes more consistent oil film formation and heat transfer. Through multiphysics simulations and parametric analysis, this study elucidates the interaction between geometric parameters and hydrodynamic behaviors in jet lubrication systems. The findings provide quantitative evaluation methods for structural optimization and energy control in gear lubrication systems, offering theoretical insights for thermal management and reliability enhancement in high-speed transmission. These results contribute to the lightweight design and sustainable development of industrial equipment. Full article
(This article belongs to the Section Friction and Tribology)
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35 pages, 5144 KiB  
Systematic Review
A Systematic Review of Two-Phase Expansion Losses: Challenges, Optimization Opportunities, and Future Research Directions
by Muhammad Syaukani, Szymon Lech, Sindu Daniarta and Piotr Kolasiński
Energies 2025, 18(13), 3504; https://doi.org/10.3390/en18133504 - 2 Jul 2025
Cited by 1 | Viewed by 363
Abstract
Two-phase expansion processes have emerged as a promising technology for enhancing energy efficiency in power generation, refrigeration, waste heat recovery systems (for example, partially evaporated organic Rankine cycle, organic flash cycle, and trilateral flash cycle), oil and gas, and other applications. However, despite [...] Read more.
Two-phase expansion processes have emerged as a promising technology for enhancing energy efficiency in power generation, refrigeration, waste heat recovery systems (for example, partially evaporated organic Rankine cycle, organic flash cycle, and trilateral flash cycle), oil and gas, and other applications. However, despite their potential, widespread adoption is hindered by inherent challenges, particularly energy losses that reduce operational efficiency. This review systematically evaluates the current state of two-phase expansion technologies, focusing on the root causes, impacts, and mitigation strategies for expansion losses. This work used Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Using the PRISMA framework, 52 relevant publications were identified from Scopus and Web of Science to conduct the systematic review. A preliminary co-occurrence analysis of keywords was also conducted using VOSviewer version 1.6.20. Three clusters were observed in this co-occurrence analysis. However, the results may not be significant. Therefore, the extended work was done through a comprehensive analysis of experimental and simulation studies from the literature. This study identifies critical loss mechanisms in key components of two-phase expanders, such as the nozzle, diffuser, rotor, working chamber, and vaneless space. Also, losses arising from wetness, such as droplet formation, interfacial friction, and non-equilibrium phase transitions, are examined. These phenomena degrade performance by disrupting flow stability, increasing entropy generation, and causing mechanical erosion. Several losses in the turbine and volumetric expanders operating in two-phase conditions are reported. Ejectors, throttling valves, and flashing flow systems that exhibit similar challenges of losses are also discussed. This review discusses the mitigation and the strategy to minimize the two-phase expansion losses. The geometry of the inlet of the two-phase expanders plays an important role, which also needs improvement to minimize losses. The review highlights recent advancements in addressing these challenges and shows optimization opportunities for further research. Full article
(This article belongs to the Special Issue Design and Experimental Study of Organic Rankine Cycle System)
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17 pages, 4494 KiB  
Article
Experimental Investigation on the Erosion Resistance Characteristics of Compressor Impeller Coatings to Water Droplet Impact
by Richárd Takács, Ibolya Zsoldos, Norbert Kiss, Izolda Popa-Müller, István Barabás, Balázs Dobos, Miklós Zsolt Tabakov, Csaba Tóth-Nagy and Pavel Novotny
Coatings 2025, 15(7), 767; https://doi.org/10.3390/coatings15070767 - 28 Jun 2025
Viewed by 362
Abstract
This study presents a comparative analysis of the water droplet erosion resistance of three compressor wheels coated with Ni-P and Si-P layers. The tests were conducted using a custom-developed experimental apparatus in accordance with the ASTM G73-10 standard. The degree of erosion was [...] Read more.
This study presents a comparative analysis of the water droplet erosion resistance of three compressor wheels coated with Ni-P and Si-P layers. The tests were conducted using a custom-developed experimental apparatus in accordance with the ASTM G73-10 standard. The degree of erosion was monitored through continuous precision mass measurements, and structural changes on the surfaces of both the base materials and the coatings were examined using a Zeiss Crossbeam 350 scanning electron microscope (SEM). Hardness values were determined using a Vickers KB 30 hardness tester, while the chemical composition was analysed using a WAS Foundry Master optical emission spectrometer. Significant differences in erosion resistance were observed among the various compressor wheels, which can be attributed to differences in coating hardness values, as well as to the detachment of the Ni-P layer from the base material under continuous erosion. In all cases, water droplet erosion led to a reduction in the isentropic efficiency of the compressor—measured using a hot gas turbocharger testbench—with the extent of efficiency loss depending upon the type of coating applied. Although blade protection technologies for turbocharger compressor impellers used in the automotive industry have been the subject of only a limited number of studies, modern technologies, such as the application of certain alternative fuels and exhaust gas recirculation, have increased water droplet formation, thereby accelerating the erosion rate of the impeller. The aim of this study is to evaluate the resistance of three different coating layers to water droplet erosion through standardized tests conducted using a custom-designed experimental apparatus. Full article
(This article belongs to the Section Ceramic Coatings and Engineering Technology)
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18 pages, 1467 KiB  
Article
Volume of Fluid (VOF) Method as a Suitable Method for Studying Droplet Formation in a Microchannel
by Felipe Santos Paes da Silva and Paulo Noronha Lisboa-Filho
Micromachines 2025, 16(7), 757; https://doi.org/10.3390/mi16070757 - 27 Jun 2025
Viewed by 470
Abstract
Microfluidics is a rapidly advancing field focused on optimizing microdevices for applications such as organ-on-a-chip systems and enhancing laboratory analyses. Understanding the physical parameters of droplet generation is crucial for these devices. Computational fluid dynamics (CFD) techniques are essential for providing insights into [...] Read more.
Microfluidics is a rapidly advancing field focused on optimizing microdevices for applications such as organ-on-a-chip systems and enhancing laboratory analyses. Understanding the physical parameters of droplet generation is crucial for these devices. Computational fluid dynamics (CFD) techniques are essential for providing insights into the limitations and efficiency of numerical methods for studying fluid dynamics and improving our understanding of various application conditions. However, the influence of different numerical methods on the analysis of physical parameters in problems involving droplet generation in microchannels remains an area of ongoing research. This study implements the Volume of Fluid (VOF) method to investigate key physical parameters, including droplet size and the effect of the capillary number on fluid regimes, in droplet generation within a microchannel featuring a T-junction geometry. We compare the VOF method with the widely used Level Set Method (LSM) to evaluate its suitability for this context. The results show that the VOF method agrees with the LSM in fundamental outcomes, such as the reduction in droplet diameter as the flow rate ratio increases and the identification of the capillary number’s influence on fluid regime classification. The VOF method provides a clearer understanding of transitions between fluid regimes by detecting stages of non-uniformity in droplet size. It identifies a transition region between regimes with variations in droplet size, proving to be effective at mapping fluid flow regimes. This study highlights the potential of the VOF method in offering more detailed insights into instabilities and transitions between fluid regimes at the microscale. Full article
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12 pages, 2285 KiB  
Article
Interfacial Engineering-Free Microfluidics: Toward a Mild and Cost-Effective Strategy for Surfactant- and Demulsifier-Free Hydrogel Microsphere Fabrication
by Qing Qin, Yu Zhang, Yubei Wei, Jinnuo Lv, Meiling Tian, Yuanyuan Sun, Wei Fang, Xingjian Huang, Jianglin Li, Yifeng Su, Xiaoliang Xiang, Xing Hu and Zhizhi Zhou
Micromachines 2025, 16(7), 733; https://doi.org/10.3390/mi16070733 - 22 Jun 2025
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Abstract
This study proposes a simple yet versatile microfluidic strategy for fabricating monodisperse alginate hydrogel microspheres using a symmetric flow-focusing device. The system integrates three key innovations: (1) Cost-effective mold fabrication: A paper-based positive master replaces conventional SU-8 photoresist, significantly simplifying device prototyping. (2) [...] Read more.
This study proposes a simple yet versatile microfluidic strategy for fabricating monodisperse alginate hydrogel microspheres using a symmetric flow-focusing device. The system integrates three key innovations: (1) Cost-effective mold fabrication: A paper-based positive master replaces conventional SU-8 photoresist, significantly simplifying device prototyping. (2) Surfactant-free droplet generation: Alginate hydrogel droplets are formed at the first flow-focusing junction without requiring interfacial stabilizers. (3) In situ solidification with coalescence suppression: Acetic acid-infused corn oil is introduced at the adjacent junction, simultaneously triggering ionic crosslinking of alginate via pH reduction while preventing droplet aggregation. Notably, the hydrogel microspheres can be efficiently harvested through oscillatory aqueous phase separation, removing post-fabrication washing steps (typically 6–8 cycles for surfactant and oil removal). This integrated approach demonstrates exceptional advantages in fabrication simplicity, process scalability, and operational robustness for high-throughput hydrogel microsphere production. Full article
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