Search Results (113)

Virophages are satellite viruses that depend on the replication machinery of giant double-stranded DNA viruses and influence the structure and dynamics of viral communities through multilayered interactions among giant viruses, their hosts, and virophages. Since the discovery of the Sputnik virophage in 2008, virophages have been increasingly recognized for their roles in regulating giant virus replication, contributing to host defense mechanisms, and shaping the evolution of mobile genetic elements. However, quantitative syntheses examining how virophage research has developed over time, particularly in marine environments, remain limited. Here, we conducted a bibliometric analysis of virophage research published between 2008 and 2025 using the Web of Science Core Collection. By comparing an overall virophage research corpus with a marine virophage sub-corpus, we assessed publication and citation trends, collaboration structures, and keyword-based intellectual and thematic evolution. Our results show that virophage research has gradually transitioned from an early phase dominated by landmark discoveries and experimental model systems to a data-intensive stage driven by genome- and metagenome-based analyses and computational approaches. Although marine virophage studies represent a relatively small proportion of the total literature, they exhibit sustained citation impact and form a distinct research axis within the field. In particular, marine-focused studies emphasize metagenomic discovery, genome sequence alignment, and the analysis of mobile genetic elements such as polinton-like viruses, highlighting the role of marine environments in accelerating the intellectual transition of virophage research. Collectively, these findings demonstrate that virophage research has moved beyond a “discovery and definition” phase toward data-driven integrative interpretation, with marine virophage research emerging as a key domain for understanding the structure and evolutionary dynamics of marine viral ecosystems. Full article

Naphthopyranones represent a structurally diverse family of fungal polyketides exhibiting a broad range of biological activities, including antibacterial, antifungal, and cytotoxic properties. Despite extensive investigations of terrestrial-derived naphthopyranones, the biosynthetic machinery responsible for their production in marine fungi has remained unexplored. Here, we report the first characterization of naphthopyranone biosynthetic gene clusters (BGCs) from a deep-sea-derived fungus. Genome mining of the cold seep-associated Penicillium javanicum OUCF108 revealed two highly homologous polyketide synthase gene clusters, pig1 and pig2. Comparative transcriptomics combined with targeted disruption of the core PKS gene pigA2 demonstrated that pig2 is the essential BGC responsible for (R)-semivioxanthin (1) production. Stepwise reconstruction of the pig2 pathway in Aspergillus oryzae NSAR1 unraveled the complete biosynthetic route from the heptaketide precursor nor-toralactone (2) to (R)-semivioxanthin (1) and its dimeric derivatives. In vitro biochemical characterization revealed that the O-methyltransferase PigN2 catalyzes regioselective 6-O-methylation with relaxed substrate specificity, that the laccase PigF2 mediates oxidative dimerization of 1 to afford dimeric derivatives, and that the fasciclin-like protein PigG2 alters this default regiochemistry, affording abundant alternative regioisomeric dimers alongside the 5,5′-linked product. Notably, a new naphthopyranone derivative, nor-4-hydroxy-toralactone (4), was isolated and structurally elucidated. Antimicrobial evaluation of all isolated compounds revealed that 4 exhibits moderate antifungal activity against the multidrug-resistant pathogen Candida auris (MIC = 12.5 μg mL⁻¹). Structure–activity relationship analysis identified the C-4 hydroxyl moiety is critical for activity. This study highlights the potential of deep-sea fungi as an untapped reservoir of bioactive naphthopyranones and provides enzymatic insights for the construction of regioselectively coupled biaryl scaffolds. Full article

Background: Inflammatory signaling and oxidative stress machinery are interconnected and play roles in apoptosis, proliferation, redox state control, and the progression of many diseases, including cancer. The marine environment harbors a wealth of organisms that produce a wide variety of bioactive molecules with significant biological activities. Over the last decade, the advent of AI-driven approaches has enhanced the study and analysis of peptides, helping to reduce costly and time-consuming conventional laboratory testing, validation, and synthetic procedures. Methods: In this study, we predicted the antioxidative and anti-inflammatory activities of peptides isolated from proteomic data obtained from circulating cells and humoral components of the sea cucumber defense system using a bioinformatic workflow based on different artificial intelligence tools. Results: We identified 40 top-ranked peptides with antioxidative and anti-inflammatory activity and a sub-class of eight peptides shared by FreD domains. Molecular docking and molecular dynamics simulations showed that they have active binding sites for different key molecules involved in inflammatory and oxidative processes. Conclusions: The results showed that the peptides highlighted by our analysis workflow can be identified as potential molecules used as therapeutic strategies for diseases by targeting both inflammatory and oxidative processes. Full article

PEEK coatings have been applied to sliding bearings in marine machinery and equipment, but their low bonding force, poor thermal conductivity and weak oleophilicity result in insufficient anti-adhesive wear performance. To solve this problem, the textured surface of the substrate was fabricated using laser texturing technology to enhance the bonding force. The PEEK coatings were reinforced by introducing oleophilic-modified nano-SiO₂ and graphene. The tribological properties of the PEEK composite coatings were studied using the ball–disc reciprocating friction wear test and Abaqus wear simulation. The results show that the texturing treatment of the substrate surface improves the bonding force of the coating. The addition of nano-SiO₂ and graphene enhances the hardness, thermal conductivity and oleophilicity of the composite coating, which shifts the wear mechanism from adhesive to abrasive. Under dry friction conditions, the composite coating containing 5 wt% SiO₂ and 1 wt% graphene exhibits a low friction coefficient and the lowest wear rate. Under oil lubrication conditions, the composite coating containing 2 wt% graphene shows the lowest friction coefficient and wear rate. In summary, under the load-bearing capacity enhancement of nano-SiO₂ and the thermal conductivity enhancement of graphene, the composite coating exhibits excellent anti-adhesive wear performance. Full article

In engineering flow systems such as hydraulic machinery and marine propulsion, interactions among cavitation bubbles can significantly influence collapse dynamics. This study investigates the collapse behavior of unequal-sized dual cavitation bubbles in a free field, focusing on jet formation modes, morphological evolution, and the characteristics of the Bjerknes force and Kelvin impulse. Particular emphasis is placed on the effect of the bubble radius ratio on the collapse dynamics. The results indicate that: (1) as the radius ratio decreases, the counter-directed jets formed during the collapse of dual cavitation bubbles gradually disappear; (2) with a decreasing radius ratio, the amplitude of the bubble wall velocity first decreases and then increases; and (3) both the Bjerknes force and the Kelvin impulse decrease as the radius ratio decreases. Full article

The marine centrifugal pump is one of the most energy-intensive pieces of equipment in ship auxiliary machinery, and the efficient design of its hydraulic components can effectively reduce the total energy consumption of the ship system. Aiming at the complex three-dimensional twisted blade profile structure of the marine centrifugal pump, this paper optimized the clonal selection algorithm and constructed an automatic hydraulic optimization design method for the high-efficiency centrifugal pump impeller. Considering the multi-condition operation characteristics of the marine centrifugal pump, a performance test platform for the marine centrifugal pump was built, and the actual operating conditions of the model pump were tested to obtain its performance characteristics under operating conditions. The numerical simulation method was employed to capture and analyze the internal flow field and flow characteristics of the model pump. Addressing the design challenges of the marine centrifugal pump impeller, which involve multiple parameters with significant interactions, a traditional clonal selection algorithm was enhanced using a Slime Mold Algorithm, and a hybrid Clonal Selection Algorithm integrated with Slime Mold and Tangent Flight mechanisms was established. Based on the MATLAB and ANSYS platforms, an automated hydraulic optimization design framework for the centrifugal pump impeller was established. Using the optimized clonal selection algorithm, with the operational efficiency of the model pump as the optimization objective and controlling ten key geometric parameters of the blade profile through Bézier curves, the blade profile optimization design was achieved. The pump hydraulic efficiency under the rated flow condition increased by 7%. The unsteady internal flow efficiency of the optimized marine centrifugal pump was significantly improved. The blade optimization alleviated flow separation phenomena on the tangential surface of the impeller and in partial regions of the volute, reduced the flow loss area, and significantly decreased overall flow losses. Full article

A sand-laden vortex is a common phenomenon in marine engineering, particularly in coastal near-bed water intake and pumping facilities, and is widely recognized as an unfavorable factor affecting the safe and efficient operation of hydraulic machinery. The purpose of this study is to explore the energy characteristics of the development process of a sediment-laden vortex in the inlet pool. The research method is to use the V3V (Three-Dimensional Velocity Measurement System) to measure the three-dimensional velocity field of a sand-laden vortex, and analyze the energy characteristics of the evolution process of a sand-laden vortex in combination with energy gradient theory. The results indicate that in the early stage of vortex development, the turbulent kinetic energy of the sand-laden vortex gradually increases with time. After reaching its maximum value, the turbulent kinetic energy of the sediment-laden vortex continues to develop for about 0.4 s, then sharply decreases and completely dissipates within 0.3 s. The axial development speed of the vortex is closely related to the distance from the pump impeller. The energy gradient during the vortex evolution process indicates that the energy around the sand-laden vortex at different stages accumulates and dissipates as the vortex evolves. The research results of this article provide mechanistic insights into the evolution of a sand-laden vortex and offer theoretical support for sediment control and hydraulic optimization in marine and coastal pumping systems. Full article

Microbial degradation of pectin is a fundamental process for the carbon cycle and a strategic approach for treating industrial residues. This study characterizes a novel marine bacterium, Paenarthrobacter sp. FR1, isolated from East China Sea intertidal sediment, which exhibits the ability to utilize pectin. Its draft genome (4.83 Mb, 62.92% GC content) is predicted to encode 4498 protein-coding genes. Genomic analysis revealed a rich repertoire of Carbohydrate-Active Enzymes (CAZymes) crucial for this process, including 108 glycoside hydrolases (GHs), 7 polysaccharide lyases (PLs), 35 carbohydrate esterases (CEs), and 11 auxiliary activities (AAs). Genomic analysis provides supportive evidence that FR1 may target both homogalacturonan (HG) and rhamnogalacturonan (RG) pectin domains, potentially through complementary hydrolytic and oxidative pathways. Phylogenomic analysis based on Average Nucleotide Identity (ANI, 83.56%) and digital DNA-DNA Hybridization (dDDH, 27.8%) confirmed its status as a potential novel species. Notably, FR1 is a rare Paenarthrobacter isolate with innate pectinolytic capability, a characteristic not previously documented in this genus. This strain’s unique enzymatic machinery highlights its importance in marine carbon cycling and provides a valuable biotechnological resource for degrading pectin-rich wastes. Full article

Heat hardening induces complex biochemical reprogramming that enhances thermal resilience in marine bivalves. Despite this technique’s promising results in marine animals, the molecular basis of heat hardening is far from understood. This study elucidates the molecular mechanisms underlying the hardening process in Mytilus galloprovincialis exposed to a 4-day sublethal heat treatment. Induction of hsf-1, hsp70, and hsp90 genes revealed the activation of the heat shock response and proteostasis machinery, ensuring proper protein folding and preventing oxidative and proteotoxic stress. Simultaneous upregulation of mitochondrial (atpase6, cox1, nadh) and glycolytic (pk, cs) genes reflects enhanced oxidative phosphorylation and glycolytic flux, maintaining ATP supply and metabolic flexibility under elevated temperatures. Increased hif-1α expression suggests transient hypoxia signaling, coordinating oxygen utilization with redox control. Reinforcement of antioxidant defenses, together with elevated autophagy-related transcription, denotes a shift toward oxidative stress mitigation and damaged organelle clearance. Balanced expression of pro- (bax) and anti-apoptotic (bcl-2) factors, along with nf-κb modulation, supports tight regulation of cell survival and inflammatory responses. These findings underscore a highly integrated biochemical network linking proteostasis, intermediary metabolism, redox balance, and antioxidant defense with cellular quality control, which together underpin the physiological plasticity of heat-hardened M. galloprovincialis, enhancing survival under transient thermal stress. Full article

Peptaibols represent a large family of membrane-active, linear fungal peptides, with variable lengths from 5 to 21 α–amino acid residues. As products of nonribosomal peptide synthetase (NRPS) biosynthetic machinery, they encompass several non-proteinogenic amino acids, particularly the Cα–tetrasubstituted residues, such as α–aminoisobutyric acid (Aib) and its homologue isovaline (Iva). Further distinctive features include an N-acyl terminus, such as an acetyl group, and a C-terminus containing an amino alcohol residue (such as phenylalaninol, leucinol, and valinol, among others), which neutralize charges at both termini and confer them a hydrophobic nature. Peptaibols not only represent the most abundant class among nonribosomal peptides, but they have also attracted continuous scientific interest due to their diverse pharmacological properties, including antimicrobial, cytotoxic, antifungal, and antiviral activities. In this review, we present for the first time the recently explored chemodiversity of fungal peptaibiotics derived from marine sources, with a particular focus on peptaibols. We discuss their distinctive structural features, chemical characterization, biosynthetic pathways, and biological activity profiles, with the aim of supporting ongoing research toward their development as potential pharmaceutical agents. Full article

In the field of rotating machinery, such as marine propulsion shafting, magnetic bearing-supported propulsion systems have garnered significant attention due to their non-mechanical contact advantages. To address the problem that the design of magnetic bearing controllers, based on theoretical models, neglects the dynamic characteristics of practical components like power amplifiers and displacement sensors, making it difficult to achieve ideal performance in practical applications, this paper proposes a control method for Hybrid Magnetic Bearings (HMBs) that combines a time-domain identification model with robust control. The method first models the power amplifier, HMB, and displacement sensor as an equivalent single system and obtains its high-precision transfer function model by performing system identification on its time-domain data using the least squares method. Based on this foundation, a PID controller is designed using the loop-shaping method to enhance the system’s robustness and control performance. Both simulations and experiments on an HMB test rig confirmed the controller’s effectiveness. The system showed excellent levitation, dynamic stability, and disturbance rejection, with experimental results closely matching simulations. The experimental results are consistent with the simulation results. This method provides a practical and feasible technical approach for enhancing the control performance of magnetic bearing-supported propulsion shafting. Full article

The maritime industry is rapidly advancing towards Industry 4.0 and the integration of autonomous shipping technologies. As the main propulsion system for autonomous vessels, marine engines play a critical role in ensuring the safety and reliability of operations at sea. Therefore, assessing the reliability and associated risks of marine engine systems is essential to prevent failures that could compromise autonomous navigation. This study conducts a comprehensive bibliometric analysis to provide up-to-date insights into the reliability assessment of marine engine machinery in the context of autonomous shipping. A total of 139 publications were retrieved from Web of Science and 133 from the Scopus database. The analysis addresses the key questions like (i) Which countries are leading research in this field? (ii) Which sources are most active in publishing this research? (iii) Which articles have had the greatest impact? (iv) Who are the most influential authors? (v) What keywords appear most frequently? (vi) What methodologies are commonly used? The findings indicate that this research area has attracted global attention, with Norway, the United States, Finland, Poland, and China being the most active contributors. However, Norway is leading in total output. Among the methodologies employed, the Bayesian network has been identified as the most widely used approach for reliability assessment of marine propulsion systems in MASS. Full article

Deep hole structures are widely used in the fields of aerospace, engineering machinery, marine, etc. During the deep hole machining processes, especially for boring procedures, the vibration phenomenon caused by the large aspect ratio of boring tools seriously restricts the machining accuracy and production efficiency. Therefore, extensive research has been devoted to the design and development of damped boring tools with different structures to suppress machining vibration. According to varied vibration reduction technologies, the damped boring tools can be divided into active and passive categories. This paper systematically reviews the advancements of vibration reduction principles, structure design, and practical applications of typical active and passive damped boring tools. Active damped boring tools rely on the synergistic action of sensors, actuators, and control systems, which can monitor vibration signals in real-time during the machining process and achieve dynamic vibration suppression through feedback adjustment. Their advantages include strong adaptability and wide adjustment capability for different machining conditions, including precision machining scenarios. Comparatively, vibration-absorbing units, such as mass dampers and viscoelastic materials, are integrated into the boring bars for passive damped tools, while an energy dissipation mechanism is utilized with the aid of boring tool structures to suppress vibration. Their advantages include simple structure, low manufacturing cost, and independence from an external energy supply. Furthermore, the potential development directions of vibration damped boring bars are discussed. With the development of intelligent manufacturing technologies, the multifunctional integration of damped boring tools has become a research hotspot. Future research will focus more on the development of an intelligent boring tool system to further improve the processing efficiency of deep hole structures with difficult-to-machine materials. Full article

Background: Seafarers are highly susceptible to work-related injuries, which can result in serious consequences or permanent disabilities. Understanding the frequency and characteristics of occupational injuries is crucial for developing effective prevention strategies and identifying their underlying patterns and causes. This study aimed to determine the frequency and characteristics of telemedicine-assisted work-related injuries among seafarers on board Italian-flagged vessels. Methods: A retrospective descriptive study was conducted to analyze occupational injuries using medical data recorded in the Centro Internazionale Radio Medico (C.I.R.M.) database from 1 January 2010 to 31 December 2022. Injuries in the database were coded according to the 10th revision of the International Classification of Diseases (ICD-10) by the World Health Organization (WHO). Variables extracted from the database included injury type, seafarers’ age, rank, nationality, worksite, gender, date of injury, affected body region, clinical outcomes, and other demographic and occupational characteristics. Injury frequency and characteristics (e.g., location, type, and cause) were analyzed and stratified by seafarers’ rank and worksite groups. Results: The analysis included 793 seafarers who sustained injuries. Their average age was 39.15 ± 10.49 years (range: 21 to 70 years). Deck ratings and engine officers accounted for 27.9% and 20% of those who claimed injuries, respectively. 39.2% of injured seafarers were aged between 30 and 40 years. In terms of affected body parts, the most reported injuries were to the hand/wrist (33.3%), followed by the knee/lower legs (21%), and the head/eye (19%). Open wounds (38%) and burns/abrasions (14%) were the most common types of injury. Slips/falls (32%), burns/explosions (16.6%), and overexertion while lifting or carrying (14.8%) were the leading causes of injury during the study period. Nearly 35% of injuries affected workers on the deck and were due mainly to slips/falls, 19% in the engine room were due to being caught in machinery or equipment, and 32.5% in the catering department were due to burns/explosions. Conclusions: One-third of seafarers who suffered work-related injuries sustained hand and/or wrist injuries, with slips/falls being a significant cause. The results of this study emphasize the need for preventative measures in the marine sector, particularly to reduce risks associated with slips and falls, overexertion, and other injury-causing factors. Campaigns for the larger use of protective equipment are desirable to reduce occupational accidents at sea and provide better health protection for seafarers. Full article