Understanding the characteristics and variations of heat exchange and evaporation of lakes is important for regional water resource management and sustainable development.Based on eddy covariance measurements over Lak...Understanding the characteristics and variations of heat exchange and evaporation of lakes is important for regional water resource management and sustainable development.Based on eddy covariance measurements over Lake Vanajavesi in southern Finland,characteristics of energy fluxes and cold frontal effects on energy exchange were investigated.The lake acted as a heat sink in spring and summer and a heat source in winter.The latent heat flux reached its minimum value in the morning and peaked in the afternoon.The diurnal variation of sensible heat flux was opposite to that of latent heat flux.Impact factors for the sensible heat flux were mainly the lake-air temperature difference and the product of lake-air temperature difference and wind speed.The latent heat flux was mainly affected by the vapor pressure deficit and the product of vapor pressure deficit and wind speed.The annual mean values of bulk transfer coefficients for momentum,heat,and water vapor were 1.98×10^(-3),1.62×10^(-3),and 1.31×10^(-3),respectively.Bulk transfer coefficients for heat and water vapor were not equal,indicating that the parameterization of energy exchange in numerical models,where the assumption that the heat coefficient equals the water vapor coefficient needs improvement.During the ice-free season,cold fronts resulted in 28 sensible heat pulses and 17 latent heat pulses,contributing to 50.59%and 34.89%of sensible and latent heat exchange in Lake Vanajavesi.These results indicate that cold fronts significantly impact the surface energy budget and evaporation over lakes.展开更多
The generation of high-resolution data is increasingly important in understanding the complexities of coastal ocean and developing sound management strategies, especially in view of the long-term impact of severe weat...The generation of high-resolution data is increasingly important in understanding the complexities of coastal ocean and developing sound management strategies, especially in view of the long-term impact of severe weather systems. The impact of severe weather systems, when integrated over time, can be significant when compared with tidal oscillations. This paper presents a study of water transport out of Vermilion Bay in response to a short, intense event associated with a passing atmospheric cold front, and reports the application of an Acoustic Doppler Current Profiler （ADCP） mounted on an Automated Surface Craft （ASC）, known as the auto-boat or unmanned boat, developed in our lab at the Louisiana State University, to generate high resolution data accurately at a fraction of the cost of a manned boat. In our study, we used a manned boat and an unmanned boat, each for over 24 h to cover an entire diurnal tidal cycle, to measure flow velocity profiles to calculate the total transport. A stationary ADCP was deployed in the Southwest Pass of the Vermilion Bay from May 2009 to April 2012, providing data almost continuously （with only one major gap）, with a 717-day record of water transport between the northern Gulf of Mexico and Vermilion Bay, and demonstrates the importance of the pass in water transport.展开更多
The present study identifies wintertime cold fronts in Eurasia from gridded datasets using a new objective two-step identification scheme.The simple and classic conception of a front is adopted,where a cold front is i...The present study identifies wintertime cold fronts in Eurasia from gridded datasets using a new objective two-step identification scheme.The simple and classic conception of a front is adopted,where a cold front is identified as the warm boundary of the frontal zone with a suitable horizontal temperature gradient and cold advection.We combine the traditional thermal front parameter with temperature advection to first identify the cold frontal zone,and then its eastern and southern boundaries are objectively plotted as a cold front in Eurasia.By comparing different cold front identification methods,the results from this two-step cold front identification method and subjective analysis are more consistent,and the positions of the cold front identified with our method are more reasonable.This objective technique is also applied to a nationwide cold wave event over China.Results show that the horizontal extent and movement of the cold front are in good agreement with the related circulation and the associated cold weather.The proposed method and results in this study may shed light on the rapid identification of cold fronts in operational weather analysis and facilitate further research on the long-term activity characteristics of continental cold fronts.展开更多
In order to study the characteristics of cold frontal motion over the arbitrary topography, the velocity of cold frontal movement is derived by using the one layer shallow-water model. The results show that there exis...In order to study the characteristics of cold frontal motion over the arbitrary topography, the velocity of cold frontal movement is derived by using the one layer shallow-water model. The results show that there exist the retardation in upwind side and rapid descent in the lee slope when the cold front crosses the topography.展开更多
[Objective] The aim was to summarize the characteristics of refelectivity factors of Doppler radar of the cold front cloud system. [Method] Judging from the characteristics of reflectivity factors, by dint of the new ...[Objective] The aim was to summarize the characteristics of refelectivity factors of Doppler radar of the cold front cloud system. [Method] Judging from the characteristics of reflectivity factors, by dint of the new generation weather radar in Harbin from 2002 to 2007, the features of the reflectivity factors of the cold front cloud system were summarized. [Result] The cloud formed by the cold front was in banded form in general. However, there was void in the cloud and its intensity was uneven. Most fast moving cold front was long and narrow banded echo and basically the radial velocity turned from northwest wind to southwest. With the changes of month, the feature of the reflective rate also changed. In winter, the cold front cloud was in layer form. The feature of the reflectivity factors was weak and in large area. However, the structure was loose and there was space in the echo. Among them, there were several strong echoes. Strong convection cell echo formed in the two sides of the cold front, and it moved with the entire cloud belt. When the dry cold front moved, regional strong convective current formed, mainly by convective cloud and small echo area. Generally, the changes of the wind direction can not be expounded from the radial velocity. However, the intensity of the convection cell was distinct, 'three-body scattering', 'side lobe echo', and 'weak echo', as well as features of super convection cell. [Conclusion] The study provided positive role for the application of Doppler radar in the surveillance of weather in Heilongjiang Province.展开更多
The understanding of unusual supercell outbreaks remains limited.This study examines the development and environmental conditions of a supercell outbreak event that occurred on 26 March 2022,when 19 supercells formed ...The understanding of unusual supercell outbreaks remains limited.This study examines the development and environmental conditions of a supercell outbreak event that occurred on 26 March 2022,when 19 supercells formed within just 6 h in the coastal region of southern China.The focus is on analyzing radar characteristics and highlighting the role of a surface cold front in driving the development of rotating storms.The cold front created significant variations in low-level vertical wind shear and conditional instability on its warm and cool sides.Most of the 19 supercells formed along the front or on its adjacent cool side.Both observations and simulations reveal that favorable dynamic conditions for supercell development appeared and concentrated in a relatively narrow area on the cool side of the front,influenced by directional wind shear near the surface,which drove the formation and positioning of supercells.Numerical simulations demonstrate that the supercells developed their rotating updrafts upon encountering the 2-4-km scale misocyclones located at the convergent boundary of the cold front.The rotating storms were enhanced when they traversed the intersection zone created by the cold front and convergent boundaries under the influence of the unique land-sea contrast of the Pearl River Delta.In sum,appropriate dynamic allocation of wind shear,cold front,and landform has facilitated development of the clustered supercell outbreak.These findings may offer valuable insights on improving severe weather forecasts in this tornado-prone area.展开更多
Sea foams are caused by algal blooms and can represent large areas in coastal waters during ocean fronts associated with meteorological changes that establish rainy weather and high wave incidence.Especially in urban ...Sea foams are caused by algal blooms and can represent large areas in coastal waters during ocean fronts associated with meteorological changes that establish rainy weather and high wave incidence.Especially in urban areas along the Brazilian southeast coast,eutrophication has been evidenced as an enhancement factor for this phenomenon.The present study was conducted on Santos City beaches during foam presence,which showed a wide distribution from the surf zone up to urban structures above the high tide limit.Water and foam samples were collected from pluvial canals that connect to Santos Bay to investigate the origin of the foam and the relationship between this phenomenon and eutrophication levels.The eutrophication analysis was based on various species of nutrients(urea,ammonium,nitrite,nitrate,phosphate,and silicate),photo-pigments,and a trophic index.A cold front passage provided intense south winds(>10 m s^(−1))and high waves(>1 m)before the sampling day.In addition to this storm surge,an accumulated rainfall of≈50 mm and a spring tide condition led to overwash at the floodgates of the pluvial canals.Salinity showed negative correlations with dissolved nutrients,indicating that increased freshwater outflows improved the trophic indices on both sides of the floodgates.At the foam sampling site,elevated concentrations of suspended particulate matter were associated with a high algal content,as primarily indicated by high chlorophyll a within particulate organic matter content.This occurred alongside high oxygen saturation and relatively low nutrient concentrations,suggesting the growth of opportunistic phytoplankton species.Our results suggest that eutrophication can intensify sea foam occurrence during overwash periods of the floodgates.However,phytoplankton analyses and more sampling sites need to be integrated into further studies for a better understanding of the local eutrophication influence on sea foam formation.展开更多
The variations of the frontogenetic activity of cold filament driven by the different angle(θ=0°,22.5°,45°,67.5°,and 90°)of the wind and wave fields and the filament axis are studied by non h...The variations of the frontogenetic activity of cold filament driven by the different angle(θ=0°,22.5°,45°,67.5°,and 90°)of the wind and wave fields and the filament axis are studied by non hydrostatic large eddy simulation.Conversion between the frontogenesis and frontolysis of cold filament were created by the chang in the direction of secondary circulations.The changes in the direction of secondary circulation are induced by the Coriolis Effect regardless of wind direction and wave fields.The destructive action of the wind and wave fields on symmetry of the submesoscale flow fields becomes weak as the angle increases.The secondary downwelling jet induced by Stokes shear force is gradually close to that associated with secondary circulations as the angle changes fromθ=0°to 45°and then the downwelling jet is only created by secondary circulations forθ=67.5°and 90°.The frontogenetic intensity of cold filament may be impacted by the angle of the wind and wave fields and the filament axis.The reason is that firstly the odd-symmetry of secondary circulations enhances with the angle increasing,and secondary the secondary downwelling jet created the Stokes shear force gradually weakens and then disappears with the angle increasing.展开更多
In response to the actual demands of the energy storage type organic Rankine power generation cycle,this study proposes a new type of jacketed shell and tube heat exchanger with integrated cold storage and heat exchan...In response to the actual demands of the energy storage type organic Rankine power generation cycle,this study proposes a new type of jacketed shell and tube heat exchanger with integrated cold storage and heat exchange.N-tedecane is selected as the phase change material for cold storage,low-temperature water as the cold source,and R134a as the heat source.The phase change material for cold storage is filled inside the jacket tube of the heat exchanger.Cold fluid is introduced into the inner tube to cause the phase change material to condense and store cold.After the cold storage is completed,R134a flows in from the shell side and condenses through heat exchange with the solidified phase change material for energy storage.This study discusses the influence laws of different cold water mass flow rates and temperatures on the cold storage performance of this heat exchanger,and analyzes the condensation effect of R134a.The results show that when the mass flow rate is 0.5 kg/s and the cold water temperature is between 3 and 4℃,the average power of the energy storage heat exchanger in the condensation experiment is 80W,and the average convective heat transfer coefficient is 110.73 W/(m^(2)⋅K).This research provides an experimental basis for the development of energy storage organic Rankine power generation cycles.展开更多
The cold chain environment is an important route for the long⁃distance transmission of pathogenic micro⁃organisms.In this study,we explored the mechanisms of secondary propagation through surface contact on cold surfa...The cold chain environment is an important route for the long⁃distance transmission of pathogenic micro⁃organisms.In this study,we explored the mechanisms of secondary propagation through surface contact on cold surfaces.A quantitative statistical experimental method was adopted to study the surface⁃contact transmission of micro⁃organisms,wherein the transfer rate of surface contact was the dependent variable and Escherichia coli was used as the indicator bacterium.The effects of contact pressure(0.44,0.86,1.55,2.25,and 2.94 N/cm^(2)),contact time(0,15,30,45,and 60 s),contact angle(15°and 25°),and surface materials(rubber and cotton gloves)were measured at two storage temperatures:cold storage(5℃)and freezing(-18℃).The results showed that as temperature decreases,the transfer of micro⁃organisms through surface contact becomes less probable.The contact time did not significantly influence the transfer rate of micro⁃organisms when items were handled at cold⁃storage temperatures.Based on these results,we recommend placing items as flat as possible to minimize the tilt angle when handling them at cold⁃storage temperatures.Additionally,if the tilt angle cannot be avoided,rubber gloves should be used when handling items stored at large tilt angles,whereas cotton gloves may be used for items placed at smaller angles.展开更多
As a large family of RNA helicases,DEAD-box(DDX)RNA helicases play crucial roles in almost all cellular RNA processing activities.However,the role of the DDX gene family in cold tolerance of mei(Prunus mume)remains un...As a large family of RNA helicases,DEAD-box(DDX)RNA helicases play crucial roles in almost all cellular RNA processing activities.However,the role of the DDX gene family in cold tolerance of mei(Prunus mume)remains unclear.In this study,we identified 45 DDX genes through whole-genome analysis unevenly distributed across eight chromosomes and scaffolds of mei.Based on the phylogenetic tree and gene structure analysis,the DDX genes were classified into nine subfamilies based on their motif compositions and intron-exon structures.The results of synteny analysis showed that segmental duplication was considered a major factor contributing to the amplification of the PmDDX family.RNA-Seq and qRT-PCR results revealed differential expression of PmDDX genes under cold stress.Among these,PmDDX39 was significantly up-regulated under cold stress,suggesting its positive role in modulating mei cold tolerance.We found that silenced PmDDX39 under cold stress led to greater damage than the wild seedlings via virus-induced gene silencing(VIGS).Conversely,overexpression of PmDDX39 in Arabidopsis enhanced cold stress tolerance.Moreover,dual luciferase and yeast one-hybrid(Y1H)demonstrated that PmDDX39 directly activates the expression of the C-repeat binding factor(PmCBFf)by binding to its promoters.This study provides new insights into the structure,evolution,and functional role of the PmDDX gene family in mei responses to cold stress.展开更多
This study presents the first systematic investigation of the rock geochemistry,hydrogeochemistry,geochronology,and formation mechanisms of the calcareous travertine-type cold volcano at Muji,Xinjiang.The Muji cold vo...This study presents the first systematic investigation of the rock geochemistry,hydrogeochemistry,geochronology,and formation mechanisms of the calcareous travertine-type cold volcano at Muji,Xinjiang.The Muji cold volcano is composed predominantly of travertine,which exhibited light rare earth element enrichment relative to heavy rare earth elements.The δ^(13)C values range from 7.1‰ to 11.1‰,while δ^(18)O values span from -12.3‰ to -7.8‰,classifying it as hypogean travertine.CO_(2) primarily originates from carbonate rock decarbonation,with a portion derived from the mantle.Water samples collected from the crater show HCO 3-Ca and HCO 3-Ca·Mg hydrochemistry types.U-Th dating of calcite indicates the Muji cold volcano formed between approximately 6.3 and 2.7 ka BP.The morphology and distribution pattern of the cold volcanoes are primarily controlled by hydrostatic pressure and the southwest boundary fault of the Muji Basin.Hydrostatic pressure of groundwater determines the growth height of the cones.The bead-like distribution orientation of the volcanic cones and the major axis direction of the elliptical contour lines of the cones align with the strike of the southwest boundary fault of the Muji Basin,indicating significant control by this fault.展开更多
A clear goal in cold tumor research is to identify strategies for converting them into immunologically‘hot’tumors with enhanced immune cell infiltration and activity,thereby improving their responsiveness to immunot...A clear goal in cold tumor research is to identify strategies for converting them into immunologically‘hot’tumors with enhanced immune cell infiltration and activity,thereby improving their responsiveness to immunotherapy.The genesis of cold tumors is exceedingly intricate.In recent times,as the analysis of this phenomenon has been pursued with greater depth,a suite of advanced diagnostic and therapeutic technologies has surfaced.These novel approaches and tactics are anticipated to modulate the tumor immune microenvironment across various dimensions,thereby facilitating the advancement of personalized and precise treatment modalities for cold tumors.The present article addresses the challenge of diminished therapeutic responsiveness to“cold tumors”within clinical settings.It systematically elucidates the multi-faceted regulatory mechanisms underlying immune evasion in cold tumors and offers a detailed analysis of advanced therapeutic strategies that incorporate nanotechnology,gene editing,and artificial intelligence methodologies.Furthermore,the future development trends of immunotherapy were explored in greater depth.It was posited that the convergence of artificial intelligence,multidimensional genomics,and emerging biotechnologies has presented positive prospects for the treatment of cold tumors,and has offered a theoretical foundation and technical framework for the transformation of cold tumors into“hot tumors”.展开更多
Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis t...Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis to examine the grain size characteristics of major riparian dunes in the typical cold and arid deserts of China.The results indicate that major riparian dunes of deserts in study area can be classified into three types based on their grain size characteristics.The Bartlett test of sphericity and the Kaiser-Meyer-Olkin(KMO)test were also performed,and their significance values were found to be 0.000 and 0.584,respectively.The results of the principal component analysis revealed that the cumulative contribution rate of the total variance reached 85.9%for the two principal components with characteristic roots greater than 1.0.The primary principal component included medium sand,whereas the secondary principal component included fine sand.We conducted a cluster analysis and classified the samples into three major types.Type I rivers include the Keriya River,Langqu River,Tora River and Heihe River,which are characterized by by fine particle size,and well-sorted.Type II includes Mu Bulag River,Kuye River,and the Xar Moron River,Compared with type I,it has a relatively coarser mean grain size and relatively poor sorting for this type.Type III includes the Maquan River,which is characterized mainly by fine sand and medium sand,accounting for more than 90%,and the sorting coefficient(0.52)suggests relatively well sorting in this pattern.Moreover,principal component analysis was applied to determine the particle sizes of samples from different watersheds.Moreover,these sediments exhibit both hydromorphic and aeolian features.At the drainage basin scale,the mode and intensity of aeolian-fluvial interactions depend on climatic conditions.In arid and semi-arid climate regions,wind is the dominant force,and the grain size exhibits significant aeolian features.Conversely,in the semi-humid region,flowing water is the dominant force,and riparian dunes in this region are formed by aeolian-fluvial interaction.The angle between the wind direction and flow direction in different reaches influences both the supply of sediment sources and the development of riparian dunes.This study will provide a new perspective for evaluating aeolian-fluvial interactions on riparian dunes in the deserts of China’s cold and arid regions.展开更多
The evolution of the S'precipitate in Al−Cu−Mg alloy was investigated using transmission electron microscopy(TEM),high-angle annular dark-field scanning transmission electron microscopy(HAADF−STEM),molecular dynam...The evolution of the S'precipitate in Al−Cu−Mg alloy was investigated using transmission electron microscopy(TEM),high-angle annular dark-field scanning transmission electron microscopy(HAADF−STEM),molecular dynamics(MD)simulations,and other analytical techniques.The precipitation behavior during different aging stages of the supersaturated solid solution formed after rapid cold punching was focused,which induces rapid dissolution of precipitates.The findings reveal that the precipitation sequence is significantly influenced by aging temperature.At higher aging temperatures,which mitigate lattice distortion in the matrix,the precipitation sequence follows the conventional path.Conversely,at lower aging temperatures,where lattice distortion persists,the sequence deviates,suppressing the formation of Guinier−Preston−Bagaryatsky(GPB)zones.MD simulations confirm that the variations in solute atom diffusion rates at different aging temperatures lead to the differences in the S'phase precipitation sequence.展开更多
In recent years,the amount of waste generated during milling has increased dramatically,and improper disposal poses a significant environmental challenge.To mitigate environmental pollution and enhance the road perfor...In recent years,the amount of waste generated during milling has increased dramatically,and improper disposal poses a significant environmental challenge.To mitigate environmental pollution and enhance the road performance of emulsified asphalt cold recycled mixtures(ECRM),this study employed recycled asphalt pavement(RAP)and reclaimed inorganic binder stabilized aggregate(RAI)as dual recycled materials for ECRM preparation.The blending ratios of reclaimed base and surface layer mixtures significantly influence ECRM's performance,with adjusted proportions substantially improving compressive strength and dynamic modulus.Firstly,three distinct proportioning options were developed for the recycled materials.Mix designs incorporating varying RAP/RAI ratios were used to determine the optimal mix parameters:moisture content,cement dosage,and emulsified asphalt content.Subsequently,comprehensive performance evaluations were conducted through high-temperature wheel tracking tests,freeze-thaw splitting tests,uniaxial compression tests,and dynamic modulus measurements to analyze the pavement characteristics of the three ECRM formulations.Experimental results demonstrate:Compared with ECRM with a blending ratio of RAP:RAI:new aggregate=30:50:20(Option 1),the dynamic stability,freeze-thaw splitting strength ratio,compressive strength,and compressive resilient modulus of ECRM under Option 3(RAP:RAI:new aggregate=50:30:20)decreased by 31.8%,5.2%,16.4%,and 13.1%,respectively.This indicates that increasing RAP content while reducing RAI proportion enhances the tensile strength of ECRM,yet adversely affects its high-temperature stability,moisture resistance,and compressive performance.This work not only addresses the challenge of jointly utilizing asphalt pavement waste and base waste,but also provides a cost-effective and sustainable method for the stable application of milling material resources in road engineering.展开更多
Objective:To evaluate the clinical efficacy of umbilical herbal application combined with pestle needle therapy in the treatment of functional diarrhea(FD)due to deficient cold of the spleen and stomach.Methods:A tota...Objective:To evaluate the clinical efficacy of umbilical herbal application combined with pestle needle therapy in the treatment of functional diarrhea(FD)due to deficient cold of the spleen and stomach.Methods:A total of 72 patients with FD were enrolled and randomly assigned to two groups using the random number table method,with 36 patients in each group.Both groups received conventional Western medication treatment.The observation group additionally received umbilical application of Wen Yang Bu Pi Gao(Yang-warming and spleenstrengthening herbal paste)combined with pestle needle therapy.After 7 d of treatment,the clinical efficacy was assessed.Traditional Chinese medicine(TCM)symptom scores,irritable bowel syndrome-quality of life(IBS-QOL)score,and the incidence of adverse reactions were compared between the two groups.Results:The total effective rate in the observation group was 91.7%,which was significantly higher than 69.4%in the control group(P<0.05).After treatment,TCM symptom and IBS-QOL scores in both groups were significantly reduced compared to those before treatment(P<0.05),and the scores in the observation group were significantly lower than those in the control group(P<0.05).No adverse reactions occurred in either group during the treatment period.Conclusion:Compared to conventional Western medication treatment alone,the addition of umbilical application of Wen Yang Bu Pi Gao combined with pestle needle therapy can more effectively alleviate clinical symptoms and improve the quality of life in patients with FD due to deficient cold of the spleen and stomach.展开更多
A 3D mesoscale model is applied in a marine cold front case in order to investigate the impact of latent heating on the structure of cold fronts.Results of the moist and dry simulations are compared to stress the effe...A 3D mesoscale model is applied in a marine cold front case in order to investigate the impact of latent heating on the structure of cold fronts.Results of the moist and dry simulations are compared to stress the effects of moist processes.It is found that both the temperature gradient and the cyclonic vorticity across the frontal zone considerably increase due to the latent heating,especially in the lower troposphere.A thermally direct cross-front ageostrophic circulation.forced by frontogenesis,is found better developed and organized in the moist case than in the dry case.This cross-front direct ageostrophic circulation,particularly its ascending branch,is considerably enhanced by latent heating due to increased frontogenetical forcing and reduced effective static stability in the rising motion region where condensation occurs.One important feature in most observed cold fronts is the presence of an intense rising cell just above their leading edge.This intense rising cell is well simulated in the moist case but is less clear and much weaker in the dry case,indicating the important contribution by the la- tent heat release to the formation of this intense updraft above the surface cold front.展开更多
The motion equation of atmospheric boundary layer with cold front surface under geostrophic momentum approximation is solved and some characteristics of the stream field for the cold front surface in the boundary laye...The motion equation of atmospheric boundary layer with cold front surface under geostrophic momentum approximation is solved and some characteristics of the stream field for the cold front surface in the boundary layer are derived,for example,the slope of the cold front surface increases with the increases of geostrophic vorticity and the temporal tendency of geostrophic wind speed, and also increases with the decrease of the component of thermal wind speed along the motion direction of the front:the stream field above and below the cold front surface in the boundary layer depends on the slope of the front surface,geostrophic wind speed and its temporal and spatial distributions.A common characteristic is that there exist updraft motion above the cold front surface and downdraft motion below it.展开更多
基金supported by funds from the National Natural Science Foundation of China(Grant Nos:42275079,41975017,42411530052,and 42161144010)the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0105)。
文摘Understanding the characteristics and variations of heat exchange and evaporation of lakes is important for regional water resource management and sustainable development.Based on eddy covariance measurements over Lake Vanajavesi in southern Finland,characteristics of energy fluxes and cold frontal effects on energy exchange were investigated.The lake acted as a heat sink in spring and summer and a heat source in winter.The latent heat flux reached its minimum value in the morning and peaked in the afternoon.The diurnal variation of sensible heat flux was opposite to that of latent heat flux.Impact factors for the sensible heat flux were mainly the lake-air temperature difference and the product of lake-air temperature difference and wind speed.The latent heat flux was mainly affected by the vapor pressure deficit and the product of vapor pressure deficit and wind speed.The annual mean values of bulk transfer coefficients for momentum,heat,and water vapor were 1.98×10^(-3),1.62×10^(-3),and 1.31×10^(-3),respectively.Bulk transfer coefficients for heat and water vapor were not equal,indicating that the parameterization of energy exchange in numerical models,where the assumption that the heat coefficient equals the water vapor coefficient needs improvement.During the ice-free season,cold fronts resulted in 28 sensible heat pulses and 17 latent heat pulses,contributing to 50.59%and 34.89%of sensible and latent heat exchange in Lake Vanajavesi.These results indicate that cold fronts significantly impact the surface energy budget and evaporation over lakes.
基金The Louisiana Board of Regents EPSCoR(pFund)the Louisiana Board of Regents Traditional Enhancement Program under contract No.LEQSF(2016-17)-ENH-TR-05+1 种基金the North Pacific Research Board under contract No.1229the Louisiana Department of Wildlife and Fisheries under contract No.699775/514-100210
文摘The generation of high-resolution data is increasingly important in understanding the complexities of coastal ocean and developing sound management strategies, especially in view of the long-term impact of severe weather systems. The impact of severe weather systems, when integrated over time, can be significant when compared with tidal oscillations. This paper presents a study of water transport out of Vermilion Bay in response to a short, intense event associated with a passing atmospheric cold front, and reports the application of an Acoustic Doppler Current Profiler （ADCP） mounted on an Automated Surface Craft （ASC）, known as the auto-boat or unmanned boat, developed in our lab at the Louisiana State University, to generate high resolution data accurately at a fraction of the cost of a manned boat. In our study, we used a manned boat and an unmanned boat, each for over 24 h to cover an entire diurnal tidal cycle, to measure flow velocity profiles to calculate the total transport. A stationary ADCP was deployed in the Southwest Pass of the Vermilion Bay from May 2009 to April 2012, providing data almost continuously （with only one major gap）, with a 717-day record of water transport between the northern Gulf of Mexico and Vermilion Bay, and demonstrates the importance of the pass in water transport.
基金This work is supported by the National Key Research and Development Pro-gram of China under contract(Grant No.2019YFC1510201 and Grant No.2018YFC1505602).
文摘The present study identifies wintertime cold fronts in Eurasia from gridded datasets using a new objective two-step identification scheme.The simple and classic conception of a front is adopted,where a cold front is identified as the warm boundary of the frontal zone with a suitable horizontal temperature gradient and cold advection.We combine the traditional thermal front parameter with temperature advection to first identify the cold frontal zone,and then its eastern and southern boundaries are objectively plotted as a cold front in Eurasia.By comparing different cold front identification methods,the results from this two-step cold front identification method and subjective analysis are more consistent,and the positions of the cold front identified with our method are more reasonable.This objective technique is also applied to a nationwide cold wave event over China.Results show that the horizontal extent and movement of the cold front are in good agreement with the related circulation and the associated cold weather.The proposed method and results in this study may shed light on the rapid identification of cold fronts in operational weather analysis and facilitate further research on the long-term activity characteristics of continental cold fronts.
文摘In order to study the characteristics of cold frontal motion over the arbitrary topography, the velocity of cold frontal movement is derived by using the one layer shallow-water model. The results show that there exist the retardation in upwind side and rapid descent in the lee slope when the cold front crosses the topography.
文摘[Objective] The aim was to summarize the characteristics of refelectivity factors of Doppler radar of the cold front cloud system. [Method] Judging from the characteristics of reflectivity factors, by dint of the new generation weather radar in Harbin from 2002 to 2007, the features of the reflectivity factors of the cold front cloud system were summarized. [Result] The cloud formed by the cold front was in banded form in general. However, there was void in the cloud and its intensity was uneven. Most fast moving cold front was long and narrow banded echo and basically the radial velocity turned from northwest wind to southwest. With the changes of month, the feature of the reflective rate also changed. In winter, the cold front cloud was in layer form. The feature of the reflectivity factors was weak and in large area. However, the structure was loose and there was space in the echo. Among them, there were several strong echoes. Strong convection cell echo formed in the two sides of the cold front, and it moved with the entire cloud belt. When the dry cold front moved, regional strong convective current formed, mainly by convective cloud and small echo area. Generally, the changes of the wind direction can not be expounded from the radial velocity. However, the intensity of the convection cell was distinct, 'three-body scattering', 'side lobe echo', and 'weak echo', as well as features of super convection cell. [Conclusion] The study provided positive role for the application of Doppler radar in the surveillance of weather in Heilongjiang Province.
基金Supported by the National Natural Science Foundation of China(42275006 and 42305002)Guangdong Basic and Applied Basic Research Foundation(2024A1515510006)+2 种基金China Meteorological Administration Tornado Key Laboratory(TKL202302)Guangdong-Hong Kong-Macao Greater Bay Area(GBA)Meteorological Science and Technology Collaborative Research Project(GHMA2024Z03)Guangdong Meteorological Administration Research Project(GRMC2023M47)。
文摘The understanding of unusual supercell outbreaks remains limited.This study examines the development and environmental conditions of a supercell outbreak event that occurred on 26 March 2022,when 19 supercells formed within just 6 h in the coastal region of southern China.The focus is on analyzing radar characteristics and highlighting the role of a surface cold front in driving the development of rotating storms.The cold front created significant variations in low-level vertical wind shear and conditional instability on its warm and cool sides.Most of the 19 supercells formed along the front or on its adjacent cool side.Both observations and simulations reveal that favorable dynamic conditions for supercell development appeared and concentrated in a relatively narrow area on the cool side of the front,influenced by directional wind shear near the surface,which drove the formation and positioning of supercells.Numerical simulations demonstrate that the supercells developed their rotating updrafts upon encountering the 2-4-km scale misocyclones located at the convergent boundary of the cold front.The rotating storms were enhanced when they traversed the intersection zone created by the cold front and convergent boundaries under the influence of the unique land-sea contrast of the Pearl River Delta.In sum,appropriate dynamic allocation of wind shear,cold front,and landform has facilitated development of the clustered supercell outbreak.These findings may offer valuable insights on improving severe weather forecasts in this tornado-prone area.
基金The authors would like to thank CNPq Proc.308916//2022-0 for the financial support and the collaboration of Giovanna N.Basile.
文摘Sea foams are caused by algal blooms and can represent large areas in coastal waters during ocean fronts associated with meteorological changes that establish rainy weather and high wave incidence.Especially in urban areas along the Brazilian southeast coast,eutrophication has been evidenced as an enhancement factor for this phenomenon.The present study was conducted on Santos City beaches during foam presence,which showed a wide distribution from the surf zone up to urban structures above the high tide limit.Water and foam samples were collected from pluvial canals that connect to Santos Bay to investigate the origin of the foam and the relationship between this phenomenon and eutrophication levels.The eutrophication analysis was based on various species of nutrients(urea,ammonium,nitrite,nitrate,phosphate,and silicate),photo-pigments,and a trophic index.A cold front passage provided intense south winds(>10 m s^(−1))and high waves(>1 m)before the sampling day.In addition to this storm surge,an accumulated rainfall of≈50 mm and a spring tide condition led to overwash at the floodgates of the pluvial canals.Salinity showed negative correlations with dissolved nutrients,indicating that increased freshwater outflows improved the trophic indices on both sides of the floodgates.At the foam sampling site,elevated concentrations of suspended particulate matter were associated with a high algal content,as primarily indicated by high chlorophyll a within particulate organic matter content.This occurred alongside high oxygen saturation and relatively low nutrient concentrations,suggesting the growth of opportunistic phytoplankton species.Our results suggest that eutrophication can intensify sea foam occurrence during overwash periods of the floodgates.However,phytoplankton analyses and more sampling sites need to be integrated into further studies for a better understanding of the local eutrophication influence on sea foam formation.
基金Supported by the National Natural Science Foundation of China (Nos.92158204,42176027,41876017,42076026)the project supported by Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(No.SML2023SP240)+1 种基金the Open Research Project Program of the State Key Laboratory of Internet of Things for Smart City (University of Macao)(No.SKL-IoTSC (UM)-2021-2023/ORPF/A20/2022)the Postdoctoral Innovation Practice Base of Hezhu University and the Guangxi Yuchai New Energy Co.,Ltd.。
文摘The variations of the frontogenetic activity of cold filament driven by the different angle(θ=0°,22.5°,45°,67.5°,and 90°)of the wind and wave fields and the filament axis are studied by non hydrostatic large eddy simulation.Conversion between the frontogenesis and frontolysis of cold filament were created by the chang in the direction of secondary circulations.The changes in the direction of secondary circulation are induced by the Coriolis Effect regardless of wind direction and wave fields.The destructive action of the wind and wave fields on symmetry of the submesoscale flow fields becomes weak as the angle increases.The secondary downwelling jet induced by Stokes shear force is gradually close to that associated with secondary circulations as the angle changes fromθ=0°to 45°and then the downwelling jet is only created by secondary circulations forθ=67.5°and 90°.The frontogenetic intensity of cold filament may be impacted by the angle of the wind and wave fields and the filament axis.The reason is that firstly the odd-symmetry of secondary circulations enhances with the angle increasing,and secondary the secondary downwelling jet created the Stokes shear force gradually weakens and then disappears with the angle increasing.
基金the the basic scientific research Funds project of Heilongjiang Universities[grant numbers 2024-KYYWF-0554].
文摘In response to the actual demands of the energy storage type organic Rankine power generation cycle,this study proposes a new type of jacketed shell and tube heat exchanger with integrated cold storage and heat exchange.N-tedecane is selected as the phase change material for cold storage,low-temperature water as the cold source,and R134a as the heat source.The phase change material for cold storage is filled inside the jacket tube of the heat exchanger.Cold fluid is introduced into the inner tube to cause the phase change material to condense and store cold.After the cold storage is completed,R134a flows in from the shell side and condenses through heat exchange with the solidified phase change material for energy storage.This study discusses the influence laws of different cold water mass flow rates and temperatures on the cold storage performance of this heat exchanger,and analyzes the condensation effect of R134a.The results show that when the mass flow rate is 0.5 kg/s and the cold water temperature is between 3 and 4℃,the average power of the energy storage heat exchanger in the condensation experiment is 80W,and the average convective heat transfer coefficient is 110.73 W/(m^(2)⋅K).This research provides an experimental basis for the development of energy storage organic Rankine power generation cycles.
基金National Natural Science Foundation of China(Grant No.52278121).
文摘The cold chain environment is an important route for the long⁃distance transmission of pathogenic micro⁃organisms.In this study,we explored the mechanisms of secondary propagation through surface contact on cold surfaces.A quantitative statistical experimental method was adopted to study the surface⁃contact transmission of micro⁃organisms,wherein the transfer rate of surface contact was the dependent variable and Escherichia coli was used as the indicator bacterium.The effects of contact pressure(0.44,0.86,1.55,2.25,and 2.94 N/cm^(2)),contact time(0,15,30,45,and 60 s),contact angle(15°and 25°),and surface materials(rubber and cotton gloves)were measured at two storage temperatures:cold storage(5℃)and freezing(-18℃).The results showed that as temperature decreases,the transfer of micro⁃organisms through surface contact becomes less probable.The contact time did not significantly influence the transfer rate of micro⁃organisms when items were handled at cold⁃storage temperatures.Based on these results,we recommend placing items as flat as possible to minimize the tilt angle when handling them at cold⁃storage temperatures.Additionally,if the tilt angle cannot be avoided,rubber gloves should be used when handling items stored at large tilt angles,whereas cotton gloves may be used for items placed at smaller angles.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.QNTD202503)Forestry and Grassland Science and Technology Innovation Youth Top Talent Project of China(Grant No.2020132608)Beijing High-Precision Discipline Project,Discipline of Ecological Environment of Urban and Rural Human Settlements.
文摘As a large family of RNA helicases,DEAD-box(DDX)RNA helicases play crucial roles in almost all cellular RNA processing activities.However,the role of the DDX gene family in cold tolerance of mei(Prunus mume)remains unclear.In this study,we identified 45 DDX genes through whole-genome analysis unevenly distributed across eight chromosomes and scaffolds of mei.Based on the phylogenetic tree and gene structure analysis,the DDX genes were classified into nine subfamilies based on their motif compositions and intron-exon structures.The results of synteny analysis showed that segmental duplication was considered a major factor contributing to the amplification of the PmDDX family.RNA-Seq and qRT-PCR results revealed differential expression of PmDDX genes under cold stress.Among these,PmDDX39 was significantly up-regulated under cold stress,suggesting its positive role in modulating mei cold tolerance.We found that silenced PmDDX39 under cold stress led to greater damage than the wild seedlings via virus-induced gene silencing(VIGS).Conversely,overexpression of PmDDX39 in Arabidopsis enhanced cold stress tolerance.Moreover,dual luciferase and yeast one-hybrid(Y1H)demonstrated that PmDDX39 directly activates the expression of the C-repeat binding factor(PmCBFf)by binding to its promoters.This study provides new insights into the structure,evolution,and functional role of the PmDDX gene family in mei responses to cold stress.
基金supported by the National Natural Science Foundation of China(Grant No.42272349).
文摘This study presents the first systematic investigation of the rock geochemistry,hydrogeochemistry,geochronology,and formation mechanisms of the calcareous travertine-type cold volcano at Muji,Xinjiang.The Muji cold volcano is composed predominantly of travertine,which exhibited light rare earth element enrichment relative to heavy rare earth elements.The δ^(13)C values range from 7.1‰ to 11.1‰,while δ^(18)O values span from -12.3‰ to -7.8‰,classifying it as hypogean travertine.CO_(2) primarily originates from carbonate rock decarbonation,with a portion derived from the mantle.Water samples collected from the crater show HCO 3-Ca and HCO 3-Ca·Mg hydrochemistry types.U-Th dating of calcite indicates the Muji cold volcano formed between approximately 6.3 and 2.7 ka BP.The morphology and distribution pattern of the cold volcanoes are primarily controlled by hydrostatic pressure and the southwest boundary fault of the Muji Basin.Hydrostatic pressure of groundwater determines the growth height of the cones.The bead-like distribution orientation of the volcanic cones and the major axis direction of the elliptical contour lines of the cones align with the strike of the southwest boundary fault of the Muji Basin,indicating significant control by this fault.
文摘A clear goal in cold tumor research is to identify strategies for converting them into immunologically‘hot’tumors with enhanced immune cell infiltration and activity,thereby improving their responsiveness to immunotherapy.The genesis of cold tumors is exceedingly intricate.In recent times,as the analysis of this phenomenon has been pursued with greater depth,a suite of advanced diagnostic and therapeutic technologies has surfaced.These novel approaches and tactics are anticipated to modulate the tumor immune microenvironment across various dimensions,thereby facilitating the advancement of personalized and precise treatment modalities for cold tumors.The present article addresses the challenge of diminished therapeutic responsiveness to“cold tumors”within clinical settings.It systematically elucidates the multi-faceted regulatory mechanisms underlying immune evasion in cold tumors and offers a detailed analysis of advanced therapeutic strategies that incorporate nanotechnology,gene editing,and artificial intelligence methodologies.Furthermore,the future development trends of immunotherapy were explored in greater depth.It was posited that the convergence of artificial intelligence,multidimensional genomics,and emerging biotechnologies has presented positive prospects for the treatment of cold tumors,and has offered a theoretical foundation and technical framework for the transformation of cold tumors into“hot tumors”.
基金Under the auspices of the General Project of Science and Technology Department of Shaanxi Province(No.2023-JCYB-264)General Program of National Natural Science Foundation of China(No.41801004,42371008,42471012)。
文摘Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis to examine the grain size characteristics of major riparian dunes in the typical cold and arid deserts of China.The results indicate that major riparian dunes of deserts in study area can be classified into three types based on their grain size characteristics.The Bartlett test of sphericity and the Kaiser-Meyer-Olkin(KMO)test were also performed,and their significance values were found to be 0.000 and 0.584,respectively.The results of the principal component analysis revealed that the cumulative contribution rate of the total variance reached 85.9%for the two principal components with characteristic roots greater than 1.0.The primary principal component included medium sand,whereas the secondary principal component included fine sand.We conducted a cluster analysis and classified the samples into three major types.Type I rivers include the Keriya River,Langqu River,Tora River and Heihe River,which are characterized by by fine particle size,and well-sorted.Type II includes Mu Bulag River,Kuye River,and the Xar Moron River,Compared with type I,it has a relatively coarser mean grain size and relatively poor sorting for this type.Type III includes the Maquan River,which is characterized mainly by fine sand and medium sand,accounting for more than 90%,and the sorting coefficient(0.52)suggests relatively well sorting in this pattern.Moreover,principal component analysis was applied to determine the particle sizes of samples from different watersheds.Moreover,these sediments exhibit both hydromorphic and aeolian features.At the drainage basin scale,the mode and intensity of aeolian-fluvial interactions depend on climatic conditions.In arid and semi-arid climate regions,wind is the dominant force,and the grain size exhibits significant aeolian features.Conversely,in the semi-humid region,flowing water is the dominant force,and riparian dunes in this region are formed by aeolian-fluvial interaction.The angle between the wind direction and flow direction in different reaches influences both the supply of sediment sources and the development of riparian dunes.This study will provide a new perspective for evaluating aeolian-fluvial interactions on riparian dunes in the deserts of China’s cold and arid regions.
基金supported by the China Scholarship Council (CSC) Local Cooperation Program (No. 202308430176)the National Natural Science Foundation of China (No. 52271177)the Hunan Provincial Natural Science Foundation Regional Joint Fund, China (No. 2023JJ50173)。
文摘The evolution of the S'precipitate in Al−Cu−Mg alloy was investigated using transmission electron microscopy(TEM),high-angle annular dark-field scanning transmission electron microscopy(HAADF−STEM),molecular dynamics(MD)simulations,and other analytical techniques.The precipitation behavior during different aging stages of the supersaturated solid solution formed after rapid cold punching was focused,which induces rapid dissolution of precipitates.The findings reveal that the precipitation sequence is significantly influenced by aging temperature.At higher aging temperatures,which mitigate lattice distortion in the matrix,the precipitation sequence follows the conventional path.Conversely,at lower aging temperatures,where lattice distortion persists,the sequence deviates,suppressing the formation of Guinier−Preston−Bagaryatsky(GPB)zones.MD simulations confirm that the variations in solute atom diffusion rates at different aging temperatures lead to the differences in the S'phase precipitation sequence.
基金sponsored by National Natural Science Foundation of China(No.52308466)SASAC Science and Technology Innovation Project(JF-23-01-0063)Shaanxi Provincial Transportation Research Project(25-84 K,25-85 K).
文摘In recent years,the amount of waste generated during milling has increased dramatically,and improper disposal poses a significant environmental challenge.To mitigate environmental pollution and enhance the road performance of emulsified asphalt cold recycled mixtures(ECRM),this study employed recycled asphalt pavement(RAP)and reclaimed inorganic binder stabilized aggregate(RAI)as dual recycled materials for ECRM preparation.The blending ratios of reclaimed base and surface layer mixtures significantly influence ECRM's performance,with adjusted proportions substantially improving compressive strength and dynamic modulus.Firstly,three distinct proportioning options were developed for the recycled materials.Mix designs incorporating varying RAP/RAI ratios were used to determine the optimal mix parameters:moisture content,cement dosage,and emulsified asphalt content.Subsequently,comprehensive performance evaluations were conducted through high-temperature wheel tracking tests,freeze-thaw splitting tests,uniaxial compression tests,and dynamic modulus measurements to analyze the pavement characteristics of the three ECRM formulations.Experimental results demonstrate:Compared with ECRM with a blending ratio of RAP:RAI:new aggregate=30:50:20(Option 1),the dynamic stability,freeze-thaw splitting strength ratio,compressive strength,and compressive resilient modulus of ECRM under Option 3(RAP:RAI:new aggregate=50:30:20)decreased by 31.8%,5.2%,16.4%,and 13.1%,respectively.This indicates that increasing RAP content while reducing RAI proportion enhances the tensile strength of ECRM,yet adversely affects its high-temperature stability,moisture resistance,and compressive performance.This work not only addresses the challenge of jointly utilizing asphalt pavement waste and base waste,but also provides a cost-effective and sustainable method for the stable application of milling material resources in road engineering.
基金supported by 2023 Annual Public Welfare Technological Application Research Project of Jinhua City(2023年度金华市公益性技术应用研究项目,No.2023-4-256).
文摘Objective:To evaluate the clinical efficacy of umbilical herbal application combined with pestle needle therapy in the treatment of functional diarrhea(FD)due to deficient cold of the spleen and stomach.Methods:A total of 72 patients with FD were enrolled and randomly assigned to two groups using the random number table method,with 36 patients in each group.Both groups received conventional Western medication treatment.The observation group additionally received umbilical application of Wen Yang Bu Pi Gao(Yang-warming and spleenstrengthening herbal paste)combined with pestle needle therapy.After 7 d of treatment,the clinical efficacy was assessed.Traditional Chinese medicine(TCM)symptom scores,irritable bowel syndrome-quality of life(IBS-QOL)score,and the incidence of adverse reactions were compared between the two groups.Results:The total effective rate in the observation group was 91.7%,which was significantly higher than 69.4%in the control group(P<0.05).After treatment,TCM symptom and IBS-QOL scores in both groups were significantly reduced compared to those before treatment(P<0.05),and the scores in the observation group were significantly lower than those in the control group(P<0.05).No adverse reactions occurred in either group during the treatment period.Conclusion:Compared to conventional Western medication treatment alone,the addition of umbilical application of Wen Yang Bu Pi Gao combined with pestle needle therapy can more effectively alleviate clinical symptoms and improve the quality of life in patients with FD due to deficient cold of the spleen and stomach.
文摘A 3D mesoscale model is applied in a marine cold front case in order to investigate the impact of latent heating on the structure of cold fronts.Results of the moist and dry simulations are compared to stress the effects of moist processes.It is found that both the temperature gradient and the cyclonic vorticity across the frontal zone considerably increase due to the latent heating,especially in the lower troposphere.A thermally direct cross-front ageostrophic circulation.forced by frontogenesis,is found better developed and organized in the moist case than in the dry case.This cross-front direct ageostrophic circulation,particularly its ascending branch,is considerably enhanced by latent heating due to increased frontogenetical forcing and reduced effective static stability in the rising motion region where condensation occurs.One important feature in most observed cold fronts is the presence of an intense rising cell just above their leading edge.This intense rising cell is well simulated in the moist case but is less clear and much weaker in the dry case,indicating the important contribution by the la- tent heat release to the formation of this intense updraft above the surface cold front.
基金This work was supported by the National Natural Science Foundation of China(No.49735180).
文摘The motion equation of atmospheric boundary layer with cold front surface under geostrophic momentum approximation is solved and some characteristics of the stream field for the cold front surface in the boundary layer are derived,for example,the slope of the cold front surface increases with the increases of geostrophic vorticity and the temporal tendency of geostrophic wind speed, and also increases with the decrease of the component of thermal wind speed along the motion direction of the front:the stream field above and below the cold front surface in the boundary layer depends on the slope of the front surface,geostrophic wind speed and its temporal and spatial distributions.A common characteristic is that there exist updraft motion above the cold front surface and downdraft motion below it.
