Based on the OFES simulation results with a horizontal resolution of 1/30(°)from 1991 to 2019,this study investigates the interannual variability characteristics and regulatory mechanisms of submesoscale kinetic energy(KE)in the northeastern South China Sea(SCS).By calculating the submesoscale KE,it is found that the submesoscale KE in the northeastern SCS exhibits significant interannual variability,with a general periodicity of 3～5 a.Correlation analysis reveals that the interannual variability of submesoscale KE in this region is jointly modulated by the mesoscale strain rate(MSR)and mixed layer depth(MLD).Among these factors,the flow field strain associated with mesoscale eddies is the primary driver of the interannual variability in submesoscale KE,while the contribution of MLD is relatively weaker.Further research indicates that the Kuroshio path in the northeastern SCS during winter plays a crucial role in the intensity of submesoscale KE.When the Kuroshio intrusion exhibits a Looping pattern,the mesoscale strain rate significantly increases,and submesoscale processes become more active.The interannual variability characteristics and regulatory mechanisms of submesoscale KE revealed in this study provide valuable insights for further research on multi-scale dynamic interactions and energy cascade processes in this region.
In response to the problem that the statistical characteristics of wave height no longer satisfy the stationarity assumption due to global climate change and anthropogenic factors,this study aims to more accurately estimate design wave heights for marine engineering.An improved compound extreme value distribution(ICEVD)model is developed based on the traditional compound extreme value distri-bution(CEVD)by integrating non-stationary modeling techniques with extreme wave height data from both typhoon and non-typhoon periods.The computational results of the traditional CEVD and the pro-posed ICEVD under non-stationary conditions are compared.Using four methods—the expected number of exceedances(ENE),design life level(DLL),equal reliability(ER),and average design life level(ADLL)—design wave heights are derived,and an uncertainty analysis is conducted.The results dem-onstrate the improved performance of the ICEVD.This model not only overcomes the limitation of the traditional CEVD,which ignores non-typhoon processes,but also more accurately reflects the non-sta-tionary characteristics of extreme wave heights under climate change.It is particularly suitable for sea areas jointly influenced by typhoon and non-typhoon weather systems,providing a new technical ap-proach for estimating design wave heights in marine engineering.
Activating transcription factor 4(ATF4)is a critical transcription factor involved in stress response.It exerts essential regulatory effects on cellular metabolism.Zebrafish genome contains two ATF4 paralogs,atf4a and atf4b.The function of Atf4a has been documented previously while that of Atf4b remains elusive.To investigate the impact of Atf4b on zebrafish development and metabolism,we generated an atf4b knockout zebrafish using CRISPR/Cas9.Sequence alignment revealed that zebrafish Atf4b shares conserved domains only in the leucine zipper and DNA-binding regions with mammalian ATF4.Morphological examination showed no apparent deformities in atf4b-/-embryos while body length was significantly reduced.Metabolomic profiling demonstrated the elevated citrate level accompanied by reduced downstream metabolites like oxoglutarate,malate and succinate in the tricarboxylic acid(TCA)cycle with a marked decrease in ATP production.Atf4b deficiency induced mitochondrial damage and significantly compromised survival under acidic stress conditions.These findings evidenced the crucial role of Atf4b in zebrafish growth,energy metabolism and stress adaptation,and provided novel insights into the integrated mechanism coupling developmental processes,metabolic homeostasis and stress response.
Based on meteorological stations observational data in Shandong Province and reanalysis data from 1981 to 2023,we apply empirical orthogonal function of the temporal-temporal matrix to extract the modes of temperature intraseasonal variations in winter and analyze the associated atmospheric circu-lation anomalies.The results show that,in addition to the mode of consistent warming or cooling in winter,Shandong's winter temperature exhibits mode of intraseasonal transition from cold to warm(or warm to cold)in winter.The variance contributions of these modes are 15.2% and 10.1%,respective-ly.Under the negative phases of the Arctic oscillation and Northern hemisphere annular mode,the Arc-tic polar vortex weakens.The stratospheric vortex shifts eccentrically toward Eurasia,while the tropo-spheric vortex exhibits an"L"-shaped multi-vortex structure.By late-winter,the concurrent weakening of the polar vortex,the Siberian High,and the Aleutian Low attenuates the East Asian winter mon-soon.This pattern results in a transition from a cold early-winter to a warm late-winter.Conversely,under positive Arctic oscillation and Northern hemisphere annular mode phases,the Arctic polar vortex strengthens with its center near the Arctic.It forms a spindle-shaped structure extending from North A-merica to Eurasia.In late winter,the enhanced polar vortex,alongside intensified Siberian High and A-leutian Low systems,strengthens the winter monsoon circulation.This pattern facilitates a transition from a warm early-winter to a cold late-winter in Shandong.
Prostaglandins(PGs)play extensive regulatory roles in physiological processes such as re-productive development,homeostasis regulation,and tissue regeneration in vertebrates,yet their distri-bution and functions in invertebrates remain poorly characterized.To address this knowledge gap,this study established a quantitative analytical method targeting prostaglandin E2(PGE2)and prostaglandin D2(PGD2)in multiple tissues of bivalves using liquid chromatography-tandem mass spectrometry(LC-MS/MS)with multiple reaction monitoring(MRM),employing the potential model bivalve dwarf surf clam(Mulinia lateralis)as the experimental organism.Through dual validation of characteristic frag-ment ions and retention time,we systematically identified the distribution profiles of PGE2 and PGD2 in six major tissues of M.lateralis:both PGs were detected in the mantle,gill,gonad,and digestive gland.Quantitative analysis,based on external standard calibration curves,revealed that PGE2 concen-trations were consistently higher than PGD2 across all examined tissues.Notably,the gill and mantle e-merged as the primary accumulation sites for PGs,with their combined PGE2 and PGD2 content contrib-uting to 82.14% of the total.Further analysis demonstrated that fast-growing individuals exhibited sig-nificantly higher PGE2 and PGD2 levels than in slow-growing counterparts(increased by 24.51% and 61.11%,respectively;P<0.01),suggesting potential involvement of PGs as key regulatory factors in the growth modulation of M.lateralis.This study provides initial insights into the tissue-specific distri-bution of PGs and their potential association with growth rate in M.lateralis,generating fundamental evidence for investigating growth regulation mechanisms and genetic improvement practices in bivalves.
The authors investigates the variation characteristics of the leading mode of sea surface tem-perature(SST)anomalies in the North Atlantic during 1980-2001 and analyzes its influence on the North Atlantic Oscillation(NAO)and Atmospheric Rivers(ARs).The results indicate that the leading pattern of North Atlantic SST anomalies predominantly exhibits a tripolar structure(North Atlantic Tripole,NAT)during 1980-2001.However,in the early winter of the 1990s,the leading mode shifts to a horseshoe-like pattern(North Atlantic Horseshoe,NAH),which exerts a significant impact on the atmospheric circulation in late winter.Analysis of the physical mechanism reveals that the NAH-like SST anomalies,through the transport of water vapor and heat at the sea-air interface exchange,alter the direction of atmospheric wind fields and moisture transport,which lead to a northward shift in the tracks of ARs.When ARs made landfall in northern Europe,enhanced precipitation-induced diabatic heating over Norway intensified baroclinic instability and storm track activity in this region,further triggering an eastward-shifted NAO anomaly pattern.In contrast,during the early winters of the 1980s,SST anomalies exhibited the NAT-type pattern,and under the influence of abnormally warm SSTs in the Gulf Stream region,the NAO phase rapidly reversed and AR pathways shifted southward.
Using the millimeter-wave radar and lidar data,conventional meteorological observation da-ta,and ERA5 reanalysis data,the authers conducted observational analyses of a sea fog event that oc-curred over the western Yellow Sea in April,2024.A prolonged sea fog event lasting four days on April 12-15,2024 occurred in Qingdao and its adjacent coastal waters.It influenced by warm and moist air-flows behind the maritime high-pressure system.During the fog development stage,favorable air-sea temperature difference,stable air-sea interface,suitable conditions of inversion layer,weak wind shear within the atmospheric boundary layer,and high static stability collectively facilitated the development and maintenance of the sea fog.The lidar deployed at Huangdao National Basic Meteorological Station successfully captured the variation trend of atmospheric visibility throughout the fog's formation and dissipation processes.It also captured the onshore propagation of sea fog during its formation stage.However,significant detection attenuation was observed during the mature stage of sea fog event.The millimeter-wave radar revealed the vertical structural characteristics of this sea fog event at different de-velopmental stages.During the formation stage,see fog echo signals were detected below 0.5 km.Longwave radiative cooling at the fog top resulted in a significantly lower reflectivity factor at the fog top edge compared to the middle and lower layers,inhibiting the upward expansion of the fog top.Dur-ing the mature stage,fine and irregular bright-dark fluctuations emerged within the non-top and non-bottom regions of the fog layer.This phenomenon might have been closely associated with small-scale turbulent motions inside the fog.In the late stage,the coalescence and growth of fog droplets followed by sinking led to echo signals exhibiting a filamentous structure similar to the convective features of weak precipitation,with the echo height rising above 1.2 km.At this time,the conditions were no lon-ger conducive to the maintenance and development of the sea fog.The combined application of conven-tional and new observational equipment,leveraging their complementary advantages,may contribute to an in-depth understanding of the structural characteristics of sea fog over the Yellow Sea.
To improve the imaging depth of high-resolution spectral-domain optical coherence tomography(OCT)in the live zebrafish brain,this study uses an electrically tunable lens.This lens enables precise axial movement of the focal point within the sample arm.OCT images are acquired at different focal positions,thereby overcoming the depth-of-focus limitation of single imaging.In addition,a SwinFusion image fusion network is employed for intelligent perception,extraction,and reconstruction of clear regions.This approach achieves high-quality image fusion.Experimental results show that,after dynamic focusing,the imaging depth increases from 180 μm(single imaging)to 1.26 mm.This depth allows whole-brain imaging of zebrafish.For the SwinFusion method,the edge strength,peak signal-to-noise ratio,information entropy,and standard deviation are 81.351,13.633,6.233,and 51.093,respectively.These values indicate higher imaging quality than the Gabor transform method and the MF-CNN method.In the reconstructed three-dimensional model,different brain regions—including the telencephalon,diencephalon,midbrain,and medulla oblongata—can be clearly distinguished.The study indicates that the combination of dynamic focusing and artificial intelligence image fusion can effectively resolve the limited imaging depth problem of OCT in live zebrafish brain imaging.
To investigate the impact of the cable breakage on the motion response of a ship's mooring system,this study establishes a ship-berth mooring model based on the AQWA hydrodynamic analysis software.First,in the frequency-domain analysis,the six-degree-of-freedom Response Amplitude Oper-ators(RAOs)of the ship are calculated,revealing significant resonance peaks for roll and pitch motions within the range of 0.4～0.6 rad/s.Then,in the time-domain analysis,the C5C6 cable group subjected to the highest load under severe sea conditions(wind scale 7,wave height 2.5 m)are taken as the re-search object.The motion response of the mooring system is simulated under two scenarios:the cable breakage due to its own damage and the cable breakage caused by exceeding the Minimum Breaking Load(MBL;1 500 kN).The results show that both breakage cases lead to a significant increase in surge mo-tion(with velocity increments of 2.1 and 6.5 mm/s,respectively),raise tension in the remaining cables by 32%～45%,and increase fender pressure by more than 36%.In particular,a chain reaction of suc-cessive failures of adjacent cables is observed within 10 minutes after the initial breakage.The findings can provide references for mooring safety,mooring system design,and emergency response during bert-hing operations.
Aiming to clarify the critical supporting role of soluble phosphorus(P)in marine atmospher-ic aerosol deposition on the growth of phytoplankton in surface seawater,this study focuses on elucida-ting the spatiotemporal distribution characteristics of aerosol P concentration and solubility in the Yellow Sea and Bohai Sea,in this study,53 atmospheric total suspended particulate(TSP)samples col-lected during five shared cruises in the Yellow Sea and the Bohai Sea during 2013-2018 were used to ana-lyze the concentrations of total P(TP)and dissolved P(DP),and to investigate the characteristics of the spatial and temporal distributions of the P concentration and solubility in the aerosol,as well as the effects of the source of the air mass and the atmospheric acidification process.The results show that the atmospheric aerosol concentrations of TP in the Yellow Sea and the Bohai Sea range from 1.5 to 135.2 ng/m3,the concentrations of DP range from 1.3 to 39.9 ng/m3,and the solubility of P ranges from 12.5%to 88.9%.P concentration and solubility showed significant spatial and temporal distribu-tions.TP concentration showed the characteristics of spring>autumn>summer,DP showed the charac-teristics of spring and autumn were basically equivalent and both significantly higher than summer,while P solubility was summer>autumn>spring.The spatial distribution shows that the atmospheric TP and DP concentrations in the Bohai Sea are higher than those in the Yellow Sea,but the P solubility is lower than that in the Yellow Sea.The source of air masses and atmospheric acidification are impor-tant factors for this spatial and temporal distribution.The TP concentration is the highest in aerosols from northern continental sources and under the influence of sand and dust(NCS-DS),while the DP concentration is higher in aerosols under the influence of northern continental sources(both sand and dust and non-sand NCS-NDS)than that under the influence of marine sources(MS)and southern conti-nental sources(SCS),and the P solubility is MS>SCS>NCS-NDS>NCS-DS.Atmospheric acidifica-tion effects can increase P solubility in aerosols by 10%～27%.
To investigate the optimal conditions for lipid accumulation in heterotrophically cultured Cyclotella cryptica,we initially conducted autotrophic and heterotrophic single-factor comparative experiments on sodium nitrate(NaNO3),sodium dihydrogen phosphate dihydrate(NaH2PO4·2H2O),sodium silicate(Na2SiO3)concentrations in F/2 medium and determined the cultivation temperature.Using autotrophic optimization results as controls,response surface methodology(RSM)was employed to optimize the cultivation conditions based on the three factors(sodium nitrate concentration,sodium silicate concentration,and temperature)that had the greatest impact on biomass and lipid yield.Combined with transcriptome analysis,the difference in lipid metabolism between the two culture methods was compared.Combined with transcriptome analysis,the difference in lipid metabolism between the two cultivation methods was compared.Single-factor analysis indicated the identical optimal parameters for heterotrophic and autotrophic cultivation,sodium nitrate 149.6 mg/L,sodium dihydrogen phosphate dihydrate 11.44 mg/L,sodium silicate 41.75 mg/L and 25.0℃.However,RSM optimization revealed the distinct heterotrophic optimum condition,sodium nitrate 145.7 mg/L,sodium silicate 43.0 mg/L and 26.0℃,different from that of autotrophic optimum condition,nitrate 147.2 mg/L,sodium silicate 43.0 mg/L and 24.2℃.Under optimized heterotrophic conditions,biomass and total lipid productivity increased by 25.64% and 51.53%,respectively,in comparison with autotrophic cultivation.Transcriptomic analysis demonstrated that the expression of genes associated with the glycolysis,pentose phosphate pathway,fatty acid synthesis and long-chain fatty acid elongation pathways was upregulated under heterotrophy while that of genes functioning in tricarboxylic acid cycle and fatty acid degradation was downregulated.These metabolic shifts confirmed that heterotrophic cultivation significantly enhanced lipid accumulation in C.cryptica.Our findings provided a theoretical basis for large-scale culture and lipid production of C.cryptica.
Streptococcus iniae is an important pathogenic bacterium of fish.To screen suitable antigenic proteins and evaluate its immunogenicity,the RT-qPCR method was used to detect the bacterial load and the in vivo induced expression of 7 virulence-related genes of S.iniae in infecting Selenotoca multifasciata.The α-enolase(rENO)encoded by the eno gene was subsequently recombinantly expressed using a prokaryotic system in E.coli,and the immunoprotective effects of an inactivated S.iniae vaccine and an rENO subunit vaccine were finally compared in S.multifasciata.The bacterial load in liver tissue showed a tendency of increasing and then decreasing.At 48 hours post-challenge,the bacterial load reached its peak.The highest mortality rate of fish occurs 48～72 hours post-challenge,exhibiting characteristics of acute infection.Gene expression detection indicated that the relative expression levels of the virulence genes eno,sag,and pgmA at 72 hours post-infection were significantly higher than those at 48 hours.Additionally,their expression levels under the condition of fish body infection were significantly higher than those under in vitro culture conditions.These results indicated that the eno,sagI and pgmA genes are induced to express during infection,and may play key virulence roles.Among them eno had the highest and stable expression at all time points and conditions.The challenge test results after immunization showed that the relative percentage survival of the inactivated S.iniae vaccine and the rENO subunit vaccine were 94.12% and 70.59%,respectively.This indicated that rENO has the potential for development as a subunit vaccine against S.iniae.In summary,we screened three important virulence genes induced by S.iniae after infection of S.multifasciata,and successfully carried out the recombinant expression of the eno gene in a prokaryotic system of E.coli,and evaluated the immune effect of subunit vaccine.The results will provide references for the prevention and control of S.iniae and the development of vaccine.
This study investigated the distribution patterns of dissolved inorganic nitrogen(DIN;NO-3+NO2+NH3),phosphate(PO4),and silicate(SiO3)in the Kuroshio Extension(KE)region and their controlling factors,based on field data collected in May-June,2021.The results indicate that the Kuro-shio-Oyashio interaction dominates the spatial pattern of nutrients through physical biogeochemical cou-pling processes:the surface nutrient distribution has significant spatial differences,and the NO-3 con-centration in the northern part of the surveyed sea area affected by Oyashio Current is 3～4 times higher than that in the southern part.The vertical distribution of DIN shows a trend of"surface consumption middle enrichment deep gradual decline",and the changes in PO4 and DIN are consistent;And domina-ted by siliceous biological pumps,SiO3 continue to accumulate with depth.Under the synergistic regu-lation of water mass dynamics and biological cycles,NO2 exhibits a bipolar distribution,with the bipo-lar layer corresponding to the nitrification equilibrium zone at the bottom of the euphotic layer and the microbial processes at the tidal front.E2 station's subsurface anticyclone caused the sinking of the iso density surface,forming a warm core and low nutrient zone,while E4 station exhibited low temperature and high nutrient characteristics due to the invasion of the intertidal subsurface.These patterns were regulated by the Kuroshio-Oyashio interaction and biogeochemical processes.Our findings advance the understanding of nutrient dynamics in this ecologically critical region.
This study presents an optimized protocol for acquiring and functionally annotating nuclear magnetic resonance(NMR)metabolic fingerprints of Mizuhopecten yessoensis.To overcome the chal-lenge of low metabolite annotation rates in NMR-based metabolomics,we developed an integrated anno-tation approach combining NMR and transcriptomic data using Weighted gene co-expression network a-nalysis(WGCNA).Through an orthogonal experimental design,we determined the optimal metabolite extraction parameters to be 1∶1 methanol/water,90 s homogenization,D2O at pH 7.4,yielding the highest number of detectable NMR signal peaks with over 90%reproducibility in both qualitative and quantitative analyses.Application of this protocol to various tissues of M.yessoensis revealed distinct metabolic profiles for each tissue.Notably,the hepatopancreas and striated muscle showed particularly higher levels of metabolism,such as fructose,fucose,and glucose,as well as energy metabolism-relat-ed substances like glycogen,ATP,acetoacetate,and carnitine.By constructing gene-metabolite co-oc-currence network using transcriptomic and NMR fingerprint data,we identified metabolite-gene mod-ules that were closely associated with specific tissues.The gene ontology(GO)annotations of genes within these modules were highly consistent with the physiological functions of corresponding tissues.This study provided a robust analytical framework for the functional annotation of NMR spectral and laid a foundation for applying NMR metabolomics in molluscan breeding programs.
This study mainly focuses on the laws governing the replenishment of coastal subsurface brine with marine-derived salts.Taking Yangkou Saltworks in Laizhou Bay as a case study,we integrat-ed field monitoring with numerical modeling.Fieldwork included electrical resistivity tomography(ERT)and groundwater multi-parameter measurements across tidal cycles.The established hydrogeo-logical model simulated water-salt migration under tidal influence.Results demonstrate a dual-peak sa-linity supply pattern.Larger tidal ranges advanced the first salinity peak by 1 h while reducing peak con-centration by 0.2～0.3 g/L.Cessation of brine mining triggered seawater intrusion and salinity loss.Tidal creek networks were identified as critical pathways for the first salinity peak formation.Key find-ings reveal that tidal dynamics control the phreatic brine salinity variation amplitude.The high-permea-bility tidal creek system enables rapid salt transport.Subsurface brine mining activities dominate the land-sea hydraulic gradient.This study provides theoretical support for optimizing brine resource man-agement in coastal zones.
This study evaluated whether dietary creatine supplementation could alleviate growth retardation and flesh quality deterioration induced by high soybean oil (SO) diets in juvenile large yellow croaker (Larimichthys crocea). Five experimental diets were formulated using fish oil (FO), soybean oil (SO) and SO supplemented with 5, 10, and 20 g/kg creatine. After a 70-day feeding trial, fish fed the SO diet exhibited impaired growth performance, reduced muscle springiness, gumminess and water-holding capacity, and increased lipid deposition compared with the FO group. Notably, supplementation with 10 g/kg creatine significantly improved growth performance and markedly enhanced muscle hardness, springiness and water-holding capacity. These improvements were accompanied by increased myofiber density, reduced myofiber diameter, and a reduction in muscle triglyceride and cholesterol contents. Mechanistically, creatine supplementation inhibited SO diet-induced expression of myostatin (mstn), and increased expression of myogenesis-related factors (e.g., myod, myog, mef2c). Meanwhile, creatine supplementation downregulated lipogenesis-related genes while promoting lipid transport and fatty acid oxidation in muscle. These findings demonstrate that creatine effectively reshapes muscle development and lipid deposition patterns under SO-based feeding conditions, thereby improving growth performance and flesh quality in large yellow croaker.
Seismic activity is one of the important factors affecting the safe operation of submarine ca-bles.For the problem of damage analysis of submarine cable impacted by earthquake-induced surface displacement,this paper establishes a three-dimensional dynamic response model of"seabed-submarine cable"based on ABAQUS,and the deformation process of submarine cable subjected to different surface impact velocities is explored.It obtains the longitudinal compression rates of conductors and optical fi-ber unit of submarine cable at different buffer distances,and advice for reasonable laying is provided.The results show that the submarine cable has obvious bending deformation under the impact of surface.The amplitude of stress oscillations in each structure of the submarine cable decreases with the increase of time,and finally tends to be stabilized.Therefore,it can be concluded that the soil medium can re-duce the impact to the submarine cable.The buffering capacity of different backfill soils varies,among which basalt has the strongest buffering capacity.When basalt is used as the backfill material and the buffer distance is greater than 2.4 m,it can effectively ensure the normal operation of the submarine ca-ble.This research method can provide theoretical references for the damage analysis and maintenance of submarine cables.
To investigate the mechanical behavior of unbonded flexible pipes under axisymmetric cyclic loading,this study accounts for nonlinear effects including large structural deformations,interlayer con-tact between multiple layers,and interlayer friction.A complete structural model of an eight-layer un-bonded flexible pipe was established using the ABAQUS finite element analysis software.The structural deformation characteristics of the flexible pipe under two types of axisymmetric cyclic loading,axial ten-sion-compression cyclic loading and bidirectional torsional cyclic loading,were studied along with the in-fluence of interlayer friction coefficient on the pipe's mechanical properties under these two loading con-ditions.The results indicate that the load-deformation curves of the flexible pipe under axisymmetric cy-clic loading exhibit hysteretic characteristics.Both the deformation characteristics of the tensile armor layer steel strips and the interlayer friction coefficient have a significant impact on the hysteretic behav-ior of the axisymmetric cyclic load-deformation curves.
To explore the nitrogen removal performance and mechanism of a strain of Bacillus mojavensis,C3,isolated from the sediment of the Yellow Sea cold water mass,we investigated its nitrogen removal performance and mechanism.The results showed that C3 effectively removed NH4+-N,NO2--N and NO3--N from sole nitrogen sources media with the initial inorganic nitrogen concentration of 21 mg/L,with the removal rate of 85.95％,75.89％and 96.29％,respectively,and the maximum nitrogen removal rate,0.36 mg/(L·h),0.36 mg/(L·h),and 0.50 mg/(L·h),correspondingly.Nitrogen balance analysis revealed that inorganic nitrogen in the system was removed through assimilation and heterotrophic nitrification-aerobic denitrification(HN-AD).Among these,nitrogen assimilation dominated the strain's inorganic nitrogen metabolism transformation while nitrogen released into the atmosphere through heterotrophic nitrification-aerobic denitrification varied between 13.29％and 16.83％of the total.The results of 15N isotope tracing showed that it only produced 15N2O but not 15N2 when strain C3 used 15NH4+-N,15NO2--N and 15NO3--N as the sole nitrogen source,indicating that N2O was the primary gaseous product of denitrification of C3.Further exploration of the nitrification pathway using ammonia oxidation inhibitors revealed that adding different concentrations of allylthiourea(ATU)had no significant effect on ammonia removal rate or nitrogen loss,suggesting that C3 may possess a novel ammonia monooxygenase with a unique enzymatic structure,being capable of converting NH4+-N to NH2OH.Whole-genome sequencing analysis revealed that nitrogen utilization during assimilation mainly occurs through the glutamate dehydrogenase(GDH)pathway(extracellular NO3/NO2-/NH4+→intracellular N H4+→ Glutamate → Bacterial protein)and the glutamine synthetase/glutamate synthase(GS/GOGAT)pathway(extracellular NO3-/NO2-/NH4+→intracellular NH4+→Glutamine→ Glutamate → Bacterial protein).The results indicated that C3 achieves nitrogen dissimilation through the heterotrophic nitrification-aerobic denitrification(HN-AD)pathway which includes heterotrophic nitrification(NH4+→NH2OH→NO→N2O)and aerobic denitrification(NO3-→NO2-→NO→N2O).These findings provided important insights into the nitrogen transformation metabolism mechanism of B.mojavensis and offered a scientific basis for the potential application of C3 in the treatment of wastewater from marine aquaculture.
Aiming at the problem of spanwise deformation during the operation of oscillating hydro-foils,this study adopts the computational fluid dynamics(CFD)method.Based on the k-ω turbulence model under the simulation condition of Reynolds number NRe=150 000,a user-defined function(UDF)is utilized to control the spanwise deformation,so as to investigate the influence of different spanwise deformation degrees on the hydrodynamic performance of the oscillating hydrofoil with a twin-support configuration.By actively controlling the spanwise deformation of the hydrofoil and combining different deformation coefficients,the flow field simulation of the oscillating hydrofoil and the calculation of hy-drodynamic coefficients are carried out,and the evolution laws of the pressure distribution on the hydro-foil surface and the vortex shedding characteristics are analyzed simultaneously.The computational re-sults indicate that:spanwise deformation affects the shedding of spanwise vortices on the pressure side and the formation of vortices on the suction side of the oscillating hydrofoil,thereby altering the pres-sure distribution along the spanwise direction of the hydrofoil;compared with the rigid hydrofoil(α=0),the energy extraction efficiency of the oscillating hydrofoil with spanwise deformation decreases by 2％to 5.8％,and the efficiency reduction amplitude increases with the increase of the deformation coef-ficient α.When α=1.5,the system power coefficient decreases by 5.4％compared with that of the rig-id hydrofoil,indicating that the span wise deformation degree exhibits a significant negative correlation with the energy capture performance.In engineering applications,methods such as material selection should be adopted to suppress the span wise deformation of the hydrofoil,thereby achieving the optimal overall performance of the device.
