The prediction of a ship＇s resistance especially the viscous wave-making resistance is an important issue in CFD applications. In this paper, the resistances of six ships from hull 1 to hull 6 with different hull for...The prediction of a ship＇s resistance especially the viscous wave-making resistance is an important issue in CFD applications. In this paper, the resistances of six ships from hull 1 to hull 6 with different hull forms advancing in still water are numerically studied using the solver naoe-FOAM-SJTU, which was developed based on the open source code package OpenFOAM. Different components of the resistances are computed and compared while considering two speed conditions （12 kn and 16 kn）. The resistance of hull 3 is the smallest while that of hull 5 is the largest at the same speed. The results show hull 3 is a good reference for the design of similar ships, which can provide some valuable guidelines for hull form optimization.展开更多
Cronobacter spp.has strong resistance to desiccation and high permeability in Enterobacteriaceae,and powdered infant formula(PIF)is one of the main contamination routes.In recent years,the contamination of Cronobacter...Cronobacter spp.has strong resistance to desiccation and high permeability in Enterobacteriaceae,and powdered infant formula(PIF)is one of the main contamination routes.In recent years,the contamination of Cronobacter spp.in PIF incidents occurs from time to time,causing infant serious diseases or death.In this investigation,matrix-assisted laser desorption/ionization time of flight mass spectrometry was used to identify the phenotypes of 35 Cronobacter strains isolated from PIF and its processing environment.Subsequently,the isolates were evaluated for drying and osmotic pressure tolerance.The results showed that the deactivation rate of the strains ranged from 9.01%to 77.57%,and the highest osmotic pressure condition the strains could tolerate was 6 g/100 mL Na Cl.In addition,there was a positive correlation between biofilm formation ability and desiccation resistance.Combined with transcriptomics,Cronobacter spp.could activate biofilm synthesis,produce more trehalose,accumulate betaine and electrolytes to stabilize intracellular structure under the two treatment conditions.A total of 31 and 43 genes were found related to desiccation and permeability resistance,respectively.And some genes(cysM,thuF,ycjO,etc.)were found to be associated with two tolerances for the first time.展开更多
BACKGROUND: Inappropriate antibiotic treatment for patients with viral infections has led to a surge in antimicrobial resistance, increasing mortality and healthcare costs. Viral and bacterial infections are often dif...BACKGROUND: Inappropriate antibiotic treatment for patients with viral infections has led to a surge in antimicrobial resistance, increasing mortality and healthcare costs. Viral and bacterial infections are often difficult to distinguish. Myxovirus resistance protein A(MxA), an essential antiviral factor induced by interferon after viral infection, holds promise for distinguishing between viral and bacterial infections. This study aimed to determine the ability of Mx A to distinguish viral from bacterial infections.METHODS: We quantified MxA in 121 infected patients via dry immunofluorescence chromatography. The Kruskal-Wallis test and receiver operating characteristic(ROC) curve analysis were used to determine the diagnostic value of Mx A, either alone or in combination with C-reactive protein(CRP) or procalcitonin(PCT), in patients with viral, bacterial, or co-infections.RESULTS: The value of MxA(ng/mL) was significantly higher in patients with viral infections than in those with bacterial and co-infections(82.3 [24.5–182.9] vs. 16.4 [10.8–26.5], P<0.0001)(82.3 [24.5–182.9] vs. 28.5 [10.2–106.8], P=0.0237). The area under the curve(AUC) of the ROC curve for distinguishing between viral and bacterial infections was 0.799(95% confidence interval [95% CI] 0.696–0.903), with a sensitivity of 68.9%(95% CI 54.3%–80.5%) and specificity of 90.0%(95% CI 74.4%–96.5%) at the threshold of 50.3 ng/mL. Combining the MxA level with the CRP or PCT level improved its ability. MxA expression was low in cytomegalovirus(15.8 [9.6–47.6] ng/mL) and Epstein-Barr virus(12.9 [8.5–21.0] ng/mL) infections.CONCLUSION: Our study showed the diagnostic efficacy of Mx A in distinguishing between viral and bacterial infections, with further enhancement when it was combined with CRP or PCT. Moreover, EpsteinBarr virus and human cytomegalovirus infections did not elicit elevated Mx A expression.展开更多
With resource exploitation and engineering construction gradually going deeper,the surrounding rock dynamic disaster becomes frequent and violent.The anchorage support is a common control method of surrounding rock in...With resource exploitation and engineering construction gradually going deeper,the surrounding rock dynamic disaster becomes frequent and violent.The anchorage support is a common control method of surrounding rock in underground engineering.To study the dynamic damage characteristics of anchored rock and the energy absorption control mechanism of dynamic disasters,a new type of constant resistance and energy absorption(CREA)material with high strength,high elongation and high energy absorption characteristics is developed.A contrast test of rockbursts in anchored rock with different support materials is conducted.The test results show that the surface damage rates and energy release degree of anchored rock with common bolt(CB)and CREA are lower than those of unanchored rock,respectively.The total energy,average energy and maximum energy released by CREA anchored rock are 30.9%,94.3%and 84.4%lower than those of CB anchored rock.Compared with unanchored rock,the rockburst peak stress in the CREA anchored rock is increased by 39.9%,and the rockburst time is delayed by 53.2%.Based on the rockburst energy calculation model,the evolution law of rockburst peak stress and energy release is investigated.The control mechanism of CREA support units on rock dynamic failure is clarified.展开更多
To elucidate the yielding performance of compact yielding anchor cables in working state,a yielding mechanical model incorporating extrusion friction and fastening rotation under confining pressure is constructed.The ...To elucidate the yielding performance of compact yielding anchor cables in working state,a yielding mechanical model incorporating extrusion friction and fastening rotation under confining pressure is constructed.The yielding resistance enhancement effect(ω)caused by working environment constraints is evaluated through multi-layer composite sleeve hole expansion analysis,forming a theoretical framework for calculating the working yielding force.Laboratory and in-situ pull-out tests are conducted to determine the yielding performance and validate the analytical theory.The main conclusions are:(1)Yielding force and energy-release capacity increase withω,significantly outperforming the unconfined state.(2)In-situ tests under varying rockmass and geostress conditions(F1–F3)determine the yielding force increases to 183.4–290.1,204.0–290.8,and 235.0–327.1 kN.(3)The slight deviation(–12.5%to 6.2%)between the theoretical and measured yielding force confirms that the analytical theory effectively describes the working yielding performance.(4)ωincreases with higher geostress and improved rock mechanical properties,with initial geostress(σ_(0))and elastic modulus of surrounding rock(E_(3))identified as critical parameters.展开更多
Interfacial solar-driven evaporation technology shows great potential in the field of industrial seawater desalination, and the development ofefficient and low-cost evaporation materials is key to achieving large-scale ...Interfacial solar-driven evaporation technology shows great potential in the field of industrial seawater desalination, and the development ofefficient and low-cost evaporation materials is key to achieving large-scale applications. Hydrogels are considered to be promising candidates;however, conventional hydrogel-based interfacial solar evaporators have difficulty in simultaneously meeting multiple requirements, including ahigh evaporation rate, salt resistance, and good mechanical properties. In this study, a Janus sponge-like hydrogel solar evaporator (CPAS) withexcellent comprehensive performance was successfully constructed. The introduction of biomass agar (AG) into the polyvinyl alcohol (PVA)hydrogel backbone reduced the enthalpy of water evaporation, optimized the pore structure, and improved the mechanical properties. Meanwhile, by introducing hydrophobic fumed nano-silica aerogel (SA) and a synergistic foaming-crosslinking process, the hydrogel spontaneouslyformed a Janus structure with a hydrophobic surface and hydrophilic bottom properties. Based on the reduction of the evaporation enthalpy andthe modulation of the pore structure, the CPAS evaporation rate reached 3.56 kg m^(-2) h^(-1) under one sun illumination. Most importantly, owingto the hydrophobic top surface and 3D-interconnected porous channels, the evaporator could work stably in high concentrations of salt-water(25 wt% NaCl), showing strong salt resistance. Efficient water evaporation, excellent salt resistance, scalable preparation processes, and low-costraw materials make CPAS extremely promising for practical applications.展开更多
The two-dimensional magnetic van der Waals heterojunctions have opened unprecedented opportunities to explore new physics due to their potential for spintronic applications.Here,combing density functional theory with ...The two-dimensional magnetic van der Waals heterojunctions have opened unprecedented opportunities to explore new physics due to their potential for spintronic applications.Here,combing density functional theory with non-equilibrium Green’s function technique.展开更多
The grain boundary phase affects the magnetic properties and corrosion resistance of sintered NdFeB magnets.In this work,a small amount of In was added to NdFeB magnets by induction melting to systematically investiga...The grain boundary phase affects the magnetic properties and corrosion resistance of sintered NdFeB magnets.In this work,a small amount of In was added to NdFeB magnets by induction melting to systematically investigate its effect on the evolution of the microstructure,magnetic properties and corrosion resistance of NdFeB magnets.Microstructural analysis illustrated that minor In addition generated more grain boundary phases and an abundant amorphous phase at the triple-junction grain boundary.While the addition of In failed to enhance the magnetic isolation effect between adjacent matrix grains,its incorporation fortuitously elevated the electrochemical potential of the In-containing magnets.Besides,during corrosion,an In-rich precipitate phase formed,hindering the ingress of the corrosive medium into the magnet.Consequently,this significantly bolstered the corrosion resistance of the sintered NdFeB magnets.The phase formation,magnetic properties and corrosion resistance of In-doped NdFeB magnets are detailed in this work,which provides new prospects for the preparation of high-performance sintered NdFeB magnets.展开更多
Conventional four-probe methods for measuring the resistance of Josephson junctions can damage superconducting thin films,making them unsuitable for frequency measurements of superconducting qubits.In this study,we pr...Conventional four-probe methods for measuring the resistance of Josephson junctions can damage superconducting thin films,making them unsuitable for frequency measurements of superconducting qubits.In this study,we present a custom probe station measurement system that employs the fritting contact technique to achieve in situ,non-destructive measurements of Josephson junction resistance.Our experimental results demonstrate that this method allows for accurate prediction of qubit frequency with an error margin of 17.2 MHz.Moreover,the fritting contact technique does not significantly affect qubit coherence time or the integrity of the superconducting film,confirming its non-destructive nature.This innovative approach provides a dependable foundation for frequency tuning and addressing frequency collision issues,thus supporting the advancement and practical deployment of superconducting quantum computing.展开更多
Direct methanol fuel cells(DMFC) are widely considered to be an ideal green energy conversion device but their widespread applications are limited by the high price of the Pt-based catalysts and the instability in ter...Direct methanol fuel cells(DMFC) are widely considered to be an ideal green energy conversion device but their widespread applications are limited by the high price of the Pt-based catalysts and the instability in terms of surface CO toxicity in long-term operation.Herein,the PtFe alloy nanoparticles(NPs) with small particle size(~4.12 nm) supported on carbon black catalysts with different Pt/Fe atomic ratios(Pt_(1)Fe_(2)/C,Pt_(3)Fe_(4)/C,Pt_(1)Fe_(1)/C,and Pt_(2)Fe_(1)/C) are successfully prepared for enhanced anti-CO poisoning during methanol oxidation reaction(MOR).The optimal atomic ratio of Pt/Fe for the MOR is 1:2,and the mass activity of Pt_(1)Fe_(2)/C(5.40 A mg_(Pt)^(-1)) is 13.5 times higher than that of conventional commercial Pt/C(Pt/C-JM)(0.40 A mg_(Pt)^(-1)).The introduction of Fe into the Pt lattice forms the PtFe alloy phase,and the electron density of Pt is reduced after forming the PtFe alloy.In-situ Fourier transform infrared results indicate that the addition of oxyphilic metal Fe has reduced the adsorption of reactant molecules on Pt during the MOR.The doping of Fe atoms helps to desorb toxic intermediates and regenerate Pt active sites,promoting the cleavage of C-O bonds with good selectivity of CO_(2)(58.1%).Moreover,the Pt_(1)Fe_(2)/C catalyst exhibits higher CO tolerance,methanol electrooxidation activity,and long-term stability than other Pt_(x)Fe_(y)/C catalysts.展开更多
Drug resistance is one of the most intractable issues in targeted therapy for cancer diseases.It has also been demonstrated to be related to cancer heterogeneity,which promotes the emergence of treatment-refractory ca...Drug resistance is one of the most intractable issues in targeted therapy for cancer diseases.It has also been demonstrated to be related to cancer heterogeneity,which promotes the emergence of treatment-refractory cancer cell populations.Focusing on how cancer cells develop resistance during the encounter with targeted drugs and the immune system,we propose a mathematical model for studying the dynamics of drug resistance in a conjoint heterogeneous tumor-immune setting.We analyze the local geometric properties of the equilibria of the model.Numerical simulations show that the selectively targeted removal of sensitive cancer cells may cause the initially heterogeneous population to become a more resistant population.Moreover,the decline of immune recruitment is a stronger determinant of cancer escape from immune surveillance or targeted therapy than the decay in immune predation strength.Sensitivity analysis of model parameters provides insight into the roles of the immune system combined with targeted therapy in determining treatment outcomes.展开更多
During heavy oil recovery in the Bohai Oilfield,substantial emulsification of oil and water occurred,primarily forming water-in-oil emulsions.This phenomenon could alter fluid dynamics within the subsurface porous med...During heavy oil recovery in the Bohai Oilfield,substantial emulsification of oil and water occurred,primarily forming water-in-oil emulsions.This phenomenon could alter fluid dynamics within the subsurface porous media,potentially impacting well production performance.To elucidate the properties of water-in-oil emulsions and their associated liquid resistance effects,this study conducted a series of rheological tests,microscopic examinations,and injection experiments.The results show that the droplet size and distribution of water-in-oil emulsions were primarily influenced by shear rate and water content,which in turn modified emulsion viscosity.The stability of water-in-oil emulsions was reduced when they flowed through porous media.The increase in emulsion viscosity and the liquid resistance effect collectively enhanced the seepage resistance of water-in-oil emulsions flowing through porous media.Notably,when the emulsion droplet size exceeded the pore throat size,over 90%of the total seepage resistance was attributable to the liquid resistance effect.Conversely,when the majority of the emulsion droplets were smaller than the pore throat,the viscosity accounted for more than 60%of the seepage resistance.Water-in-oil emulsions flowed through cores with permeabilities ranging from 50 to 100 mD,exhibiting threshold pressure gradients between 35 and 43 MPa/m.At a core permeability of 300 mD,the threshold pressure gradient was significantly reduced to 1 MPa/m.The presence of a waterin-oil emulsion in the reservoir could result in a production pressure differential falling below the threshold pressure,thereby reducing reservoir productivity.展开更多
A reasonable heat treatment process for TC4 ELI titanium alloy is crucial to tune microstructures to improve its explosion resistance.However,there is limited investigation on tuning microstructures of TC4 ELI to impr...A reasonable heat treatment process for TC4 ELI titanium alloy is crucial to tune microstructures to improve its explosion resistance.However,there is limited investigation on tuning microstructures of TC4 ELI to improve explosion resistance.Moreover,the current challenge is quantifying microstructural changes'effects on explosion resistance and incorporating microstructural changes into finite element models.This work aims to tune microstructures to improve explosion resistance and elucidate their anti-explosion mechanism,and find a suitable method to incorporate microstructural changes into finite element models.In this work,we systematically study the deformation and failure characteristics of TC4 ELI plates with varying microstructures using an air explosion test and LS-DYNA finite element modeling.The Johnson-Cook(JC)constitutive parameters are used to quantify the effects of microstructural changes on explosion resistance and incorporate microstructural changes into finite element models.Because of the heat treatment,one plate has equiaxed microstructure and the other has bimodal microstructure.The convex of the plate after the explosion has a quadratic relationship with the charge mass,and the simulation results demonstrate high reliability,with the error less than 17.5%.Therefore,it is feasible to obtain corresponding JC constitutive parameters based on the differences in microstructures and mechanical properties and characterize the effects of microstructural changes on explosion resistance.The bimodal target exhibits excellent deformation resistance.The response of bimodal microstructure to the shock wave may be more intense under explosive loading.The well-coordinated structure of the bimodal target enhances its resistance to deformation.展开更多
With the prevalence of obesity and obesity-related metabolic syndrome,such as insulin resistance in recent years,it is urgent to explore effective interventions to prevent the progression of obesity-related metabolic ...With the prevalence of obesity and obesity-related metabolic syndrome,such as insulin resistance in recent years,it is urgent to explore effective interventions to prevent the progression of obesity-related metabolic syndrome.Palmitoleic acid is a monounsaturated fatty acid that is available from dietary sources,mainly derived from marine products.P almitoleic acid plays a positive role in maintaining glucose homeostasis and reducing inflammation.However,it is still unknow the mechanism of palmitoleic acid in ameliorating insulin resistance.Here,we investigated the effects of palmitoleic acid on chow diet(CD)-fed and high-fat diet(HFD)-fed mice,which were fed CD or HFD for 12 weeks before administration.We administrated mice with BSA(control),oleic acid,or palmitoleic acid for 6 weeks on top of CD or HFD feeding.We found that palmitoleic acid only improved glucose homeostasis in HFD-fed obese mice by increasing glucose clearance and reducing HOMA-IR.Further study explored that palmitoleic acid changed the composition of gut microbiota by decreasing Firmicutes population and increasing Bacteroidetes population.In colon,palmitoleic acid increased intestinal tight junction integrity and reduced inflammation.Moreover,palmitoleic acid decreased macrophage infiltration in liver and adipose tissue and increase glucose uptake in adipose tissue.Diacylglycerol(DAG)in tissue(for example,liver)is found to positively correlated with HOMA-IR.HFD enhanced the levels of DAGs in liver but not in adipose tissue in this study.Palmitoleic acid did not reverse the high DAG levels induced by HFD in liver.Therefore,in HFD-fed mice,palmitoleic acid reduced insulin resistance by an independent-manner of DAGs.It might be associated with the beneficial effects of palmitoleic acid on altering the gut microbiota composition,improving of intestinal barrier function,and downregulating the inflammation in colon,liver,and adipose tissue.展开更多
This study investigated the effects of a xylitol-casein non-covalent complex(XC)on parameters related to type 2 diabetes mellitus(T2DM),in addition to related changes in gut microbiome composition and functions.High-f...This study investigated the effects of a xylitol-casein non-covalent complex(XC)on parameters related to type 2 diabetes mellitus(T2DM),in addition to related changes in gut microbiome composition and functions.High-fat-diet(HFD)+streptozotocin(STZ)-induced T2DM mice were treated with xylitol(XY),casein(CN),and XC,after which fecal samples were collected for gut microbiota composition and diversity analyses based on 16S rRNA high-throughput sequencing and multivariate statistics.XC decreased body weight and improved glucose tolerance,insulin sensitivity,pancreas impairment,blood lipid levels,and liver function in T2DM mice compared to XY-and CN-treated mice.Furthermore,XC modulated theα-diversity,β-diversity and gut microbiota composition.Based on Spearman’s correlation analysis,the relative abundances of Alistipes,Bacteroides,and Faecalibaculum were positively correlated and those of Akkermansia,Lactobacillus,Bifidobacterium,and Turicibacter were negatively correlated with the phenotypes related to the improvement of T2DM.In conclusion,we found that XC alleviated insulin resistance by restoring the gut microbiota of T2DM mice.Our results provide strong evidence for the beneficial effects of XC on T2DM and motivation for further investigation in animal models and,eventually,human trials.展开更多
Multidrug-resistant(MDR)Enterobacteriaceae critically threaten duck farming and public health.The phenotypes,genotypes,and associated mobile genetic elements(MGEs)of MDR Enterobacteriaceae isolated from 6 duck farms i...Multidrug-resistant(MDR)Enterobacteriaceae critically threaten duck farming and public health.The phenotypes,genotypes,and associated mobile genetic elements(MGEs)of MDR Enterobacteriaceae isolated from 6 duck farms in Zhejiang Province,China,were investigated.A total of 215 isolates were identified as Escherichia coli(64.65%),Klebsiella pneumoniae(12.09%),Proteus mirabilis(10.23%),Salmonella(8.84%),and Enterobacter cloacae(4.19%).Meanwhile,all isolates were resistant to at least two antibiotics.Most isolates carried tet(A)(85.12%),blaTEM(78.60%)and sul1(67.44%)resistance genes.Gene co-occurrence analysis showed that the resistance genes were associated with IS26 and integrons.A conjugative IncFII plasmid pSDM004 containing all the above MGEs was detected in Proteus mirabilis isolate SDM004.This isolate was resistant to 18 antibiotics and carried the blaNDM-5 gene.MGEs,especially plasmids,are the primary antibiotic resistance gene transmission route in duck farms.These findings provide a theoretical basis for the rational use of antibiotics in farms which are substantial for evaluating public health and food safety.展开更多
To study the anti-explosion protection effect of polyurea coating on reinforced concrete box girder,two segmental girder specimens were made at a scale of 1:3,numbered as G(without polyurea coating)and PCG(with polyur...To study the anti-explosion protection effect of polyurea coating on reinforced concrete box girder,two segmental girder specimens were made at a scale of 1:3,numbered as G(without polyurea coating)and PCG(with polyurea coating).The failure characteristics and dynamic responses of the specimens were compared through conducting explosion tests.The reliability of the numerical simulation using LS-DYNA software was verified by the test results.The effects of different scaled distances,reinforcement ratios,concrete strengths,coating thicknesses and ranges of polyurea were studied.The results show that the polyurea coating can effectively enhance the anti-explosion performance of the girder.The top plate of middle chamber in specimen G forms an elliptical penetrating hole,while that in specimen PCG only shows a very slight local dent.The peak vertical displacement and residual displacement of PCG decrease by 74.8% and 73.7%,respectively,compared with those of specimen G.For the TNT explosion with small equivalent,the polyurea coating has a more significant protective effect on reducing the size of fracture.With the increase of TNT equivalent,the protective effect of polyurea on reducing girder displacement becomes more significant.The optimal reinforcement ratio,concrete strength,thickness and range of polyurea coating were also drawn.展开更多
In order to understand the influence of bow shape on ice resistance and provide guidelines for hull line design in the early design stage,an investigation of the impact of bow shape on ice resistance for the Arctic LN...In order to understand the influence of bow shape on ice resistance and provide guidelines for hull line design in the early design stage,an investigation of the impact of bow shape on ice resistance for the Arctic LNG carriers is carried out based on semi-empirical methods.Firstly,some typical semi-empirical formulas developed for ice resistance estimation of cargo carriers in different ice conditions are summarized.Then,formulas appropriate for ice resistance estimation of Arctic LNG carriers under different ice conditions are verified according to the result comparison between semi-empirical formulas and experimental tests.The comparison result indicates that the Lindqvist formula is appropriate for ice resistance estimation in level ice conditions,Zuev and Dobrodeev formula for ice resistance estimation in broken ice conditions,and Dobrodeev formula for ice resistance estimation in brash ice conditions.After that,the parameters considered in the selected formulas are summarized,and the influence of critical parameters on ice resistance is analyzed.Some parameters describing the ship's bow shape characteristic like ship breadth,waterline angle and stem angle greatly influence the ice resistance.Ice resistance increases with both the growth of ship breadth under all ice conditions and the growth of stem angle in level ice and broken ice conditions while ice resistance decreases with the development of waterline angle under all ice conditions.Finally,the optimization of the bow shape is discussed,and an optimized bow shape with both a large waterline angle and low stem angle is proposed.The optimized bow shape can decrease ice resistance by 9.9%in the level ice condition and reduce ice resistance by 11.3%in the brash ice condition.展开更多
Slickwater fracturing fluids are widely used in the development of unconventional oil and gas resources due to the advantages of low cost,low formation damage and high drag reduction performance.However,their performa...Slickwater fracturing fluids are widely used in the development of unconventional oil and gas resources due to the advantages of low cost,low formation damage and high drag reduction performance.However,their performance is severely affected at high temperatures.Drag reducing agent is the key to determine the drag reducing performance of slickwater.In this work,in order to further improve the temperature resistance of slickwater,a temperature-resistant polymeric drag reducing agent(PDRA)was synthesized and used as the basis for preparing the temperature-resistant slickwater.The slickwater system was prepared with the compositions of 0.2 wt%PDRA,0.05 wt%drainage aid nonylphenol polyoxyethylene ether phosphate(NPEP)and 0.5 wt%anti-expansion agent polyepichlorohydrindimethylamine(PDM).The drag reduction ability,rheology properties,temperature and shear resistance ability,and core damage property of slickwater were systematically studied and evaluated.In contrast to on-site drag reducing agent(DRA)and HPAM,the temperature-resistant slickwater demonstrates enhanced drag reduction efficacy at 90℃,exhibiting superior temperature and shear resistance ability.Notably,the drag reduction retention rate for the slickwater achieved an impressive 90.52%after a 30-min shearing period.Additionally,the core damage is only 5.53%.We expect that this study can broaden the application of slickwater in high-temperature reservoirs and provide a theoretical basis for field applications.展开更多
The intensive development of tight reservoirs has positioned them as a strategic alternative to conventional oil and gas resources. Existing enhanced oil recovery(EOR) methods struggle to effectively exploring reservo...The intensive development of tight reservoirs has positioned them as a strategic alternative to conventional oil and gas resources. Existing enhanced oil recovery(EOR) methods struggle to effectively exploring reservoir oil, resulting in low recovery rates. Novel and effective means of developing tight reservoirs are urgently needed. Nanomaterials have shown promising applications in improving water flooding efficiency, with in-depth research into mechanisms that lower injection pressure and increase water injection volumes. However, the extent of improvement remains limited. In this study, a silicon quantum dots(Si-QDs) material was synthesized via a hydrothermal synthesis method and used to prepare a nanofluid for the efficient recovery of tight reservoir. The Si-QDs, with an approximate diameter of 3 nm and a spherical structure, were surface functionalized with benzenesulfonic acid groups to enhance the performance. The developed nanofluid demonstrated stability without aggregation at 120℃ and a salinity of 60000 mg/L. Core flooding experiments have demonstrated the attractive EOR capabilities of Si-QDs, shedding light of the EOR mechanisms. Si-QDs effectively improve the wettability of rocks, enhancing the sweeping coefficient of injected fluids and expanding sweeping area.Within this sweeping region, Si-QDs efficiently stripping adsorbed oil from the matrix, thus increasing sweeping efficiency. Furthermore, Si-QDs could modify the state of pore-confined crude oil, breaking it down into smaller particles that are easier to displacement in subsequent stages. Si-QDs exhibit compelling EOR potential, positioning them as a promising approach for effectively developing tight oil reservoirs.展开更多
基金Foundation item： Supported by the National Natural Science Foundation of China （Grant Nos.l1072154, 51379125）, the National Key Basic Research Development Plan （973 Plan） Project of China （Grant No.2013CB036103）, the High Technology of Marine Research Project of the Ministry of Industry and Information Technology of China and the Program for Professor of Special Appointment （Eastern Scholar） at Shanghai Institutions of Higher Learning （Grant No. 2013022）.
文摘The prediction of a ship＇s resistance especially the viscous wave-making resistance is an important issue in CFD applications. In this paper, the resistances of six ships from hull 1 to hull 6 with different hull forms advancing in still water are numerically studied using the solver naoe-FOAM-SJTU, which was developed based on the open source code package OpenFOAM. Different components of the resistances are computed and compared while considering two speed conditions （12 kn and 16 kn）. The resistance of hull 3 is the smallest while that of hull 5 is the largest at the same speed. The results show hull 3 is a good reference for the design of similar ships, which can provide some valuable guidelines for hull form optimization.
基金supported by the Joint Funds of the National Natural Science Foundation of China(U21A20272)。
文摘Cronobacter spp.has strong resistance to desiccation and high permeability in Enterobacteriaceae,and powdered infant formula(PIF)is one of the main contamination routes.In recent years,the contamination of Cronobacter spp.in PIF incidents occurs from time to time,causing infant serious diseases or death.In this investigation,matrix-assisted laser desorption/ionization time of flight mass spectrometry was used to identify the phenotypes of 35 Cronobacter strains isolated from PIF and its processing environment.Subsequently,the isolates were evaluated for drying and osmotic pressure tolerance.The results showed that the deactivation rate of the strains ranged from 9.01%to 77.57%,and the highest osmotic pressure condition the strains could tolerate was 6 g/100 mL Na Cl.In addition,there was a positive correlation between biofilm formation ability and desiccation resistance.Combined with transcriptomics,Cronobacter spp.could activate biofilm synthesis,produce more trehalose,accumulate betaine and electrolytes to stabilize intracellular structure under the two treatment conditions.A total of 31 and 43 genes were found related to desiccation and permeability resistance,respectively.And some genes(cysM,thuF,ycjO,etc.)were found to be associated with two tolerances for the first time.
基金supported by the National Natural Science Foundation of China (82272196 and 82272220)。
文摘BACKGROUND: Inappropriate antibiotic treatment for patients with viral infections has led to a surge in antimicrobial resistance, increasing mortality and healthcare costs. Viral and bacterial infections are often difficult to distinguish. Myxovirus resistance protein A(MxA), an essential antiviral factor induced by interferon after viral infection, holds promise for distinguishing between viral and bacterial infections. This study aimed to determine the ability of Mx A to distinguish viral from bacterial infections.METHODS: We quantified MxA in 121 infected patients via dry immunofluorescence chromatography. The Kruskal-Wallis test and receiver operating characteristic(ROC) curve analysis were used to determine the diagnostic value of Mx A, either alone or in combination with C-reactive protein(CRP) or procalcitonin(PCT), in patients with viral, bacterial, or co-infections.RESULTS: The value of MxA(ng/mL) was significantly higher in patients with viral infections than in those with bacterial and co-infections(82.3 [24.5–182.9] vs. 16.4 [10.8–26.5], P<0.0001)(82.3 [24.5–182.9] vs. 28.5 [10.2–106.8], P=0.0237). The area under the curve(AUC) of the ROC curve for distinguishing between viral and bacterial infections was 0.799(95% confidence interval [95% CI] 0.696–0.903), with a sensitivity of 68.9%(95% CI 54.3%–80.5%) and specificity of 90.0%(95% CI 74.4%–96.5%) at the threshold of 50.3 ng/mL. Combining the MxA level with the CRP or PCT level improved its ability. MxA expression was low in cytomegalovirus(15.8 [9.6–47.6] ng/mL) and Epstein-Barr virus(12.9 [8.5–21.0] ng/mL) infections.CONCLUSION: Our study showed the diagnostic efficacy of Mx A in distinguishing between viral and bacterial infections, with further enhancement when it was combined with CRP or PCT. Moreover, EpsteinBarr virus and human cytomegalovirus infections did not elicit elevated Mx A expression.
基金supported by the National Key Research and Development Program of China(No.2023YFC2907600)the National Natural Science Foundation of China(Nos.42477166 and 42277174)+2 种基金the Fundamental Research Funds for the Central Universities,China(No.2024JCCXSB01)the Opening Project of State Key Laboratory of Explosion Science and Safety Protection,Beijing Institute of Technology(No.KFJJ24-01M)the Open Foundation of Collaborative Innovation Center of Green Development and Ecological Restoration of Mineral Resources(No.HLCX2024-04)。
文摘With resource exploitation and engineering construction gradually going deeper,the surrounding rock dynamic disaster becomes frequent and violent.The anchorage support is a common control method of surrounding rock in underground engineering.To study the dynamic damage characteristics of anchored rock and the energy absorption control mechanism of dynamic disasters,a new type of constant resistance and energy absorption(CREA)material with high strength,high elongation and high energy absorption characteristics is developed.A contrast test of rockbursts in anchored rock with different support materials is conducted.The test results show that the surface damage rates and energy release degree of anchored rock with common bolt(CB)and CREA are lower than those of unanchored rock,respectively.The total energy,average energy and maximum energy released by CREA anchored rock are 30.9%,94.3%and 84.4%lower than those of CB anchored rock.Compared with unanchored rock,the rockburst peak stress in the CREA anchored rock is increased by 39.9%,and the rockburst time is delayed by 53.2%.Based on the rockburst energy calculation model,the evolution law of rockburst peak stress and energy release is investigated.The control mechanism of CREA support units on rock dynamic failure is clarified.
基金supported by the National Natural Science Foundation of China(Nos.U2468217,U2034205,and 52308391)。
文摘To elucidate the yielding performance of compact yielding anchor cables in working state,a yielding mechanical model incorporating extrusion friction and fastening rotation under confining pressure is constructed.The yielding resistance enhancement effect(ω)caused by working environment constraints is evaluated through multi-layer composite sleeve hole expansion analysis,forming a theoretical framework for calculating the working yielding force.Laboratory and in-situ pull-out tests are conducted to determine the yielding performance and validate the analytical theory.The main conclusions are:(1)Yielding force and energy-release capacity increase withω,significantly outperforming the unconfined state.(2)In-situ tests under varying rockmass and geostress conditions(F1–F3)determine the yielding force increases to 183.4–290.1,204.0–290.8,and 235.0–327.1 kN.(3)The slight deviation(–12.5%to 6.2%)between the theoretical and measured yielding force confirms that the analytical theory effectively describes the working yielding performance.(4)ωincreases with higher geostress and improved rock mechanical properties,with initial geostress(σ_(0))and elastic modulus of surrounding rock(E_(3))identified as critical parameters.
基金supported by the National Natural Science Foundation of China(22278110)China Postdoctoral Science Foundation(2022M720984)+1 种基金the Natural Science Foundation of Hebei Province of China(B2021202012)Tianjin Technical Innovation Guidance Special Project(20YDTPJC00630).
文摘Interfacial solar-driven evaporation technology shows great potential in the field of industrial seawater desalination, and the development ofefficient and low-cost evaporation materials is key to achieving large-scale applications. Hydrogels are considered to be promising candidates;however, conventional hydrogel-based interfacial solar evaporators have difficulty in simultaneously meeting multiple requirements, including ahigh evaporation rate, salt resistance, and good mechanical properties. In this study, a Janus sponge-like hydrogel solar evaporator (CPAS) withexcellent comprehensive performance was successfully constructed. The introduction of biomass agar (AG) into the polyvinyl alcohol (PVA)hydrogel backbone reduced the enthalpy of water evaporation, optimized the pore structure, and improved the mechanical properties. Meanwhile, by introducing hydrophobic fumed nano-silica aerogel (SA) and a synergistic foaming-crosslinking process, the hydrogel spontaneouslyformed a Janus structure with a hydrophobic surface and hydrophilic bottom properties. Based on the reduction of the evaporation enthalpy andthe modulation of the pore structure, the CPAS evaporation rate reached 3.56 kg m^(-2) h^(-1) under one sun illumination. Most importantly, owingto the hydrophobic top surface and 3D-interconnected porous channels, the evaporator could work stably in high concentrations of salt-water(25 wt% NaCl), showing strong salt resistance. Efficient water evaporation, excellent salt resistance, scalable preparation processes, and low-costraw materials make CPAS extremely promising for practical applications.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB3505301)the Natural Science Basic Research Program of Shanxi(Grant No.20210302124252)the Innovation Project For Teaching Reform of Shanxi(Grant No.J20230616)。
文摘The two-dimensional magnetic van der Waals heterojunctions have opened unprecedented opportunities to explore new physics due to their potential for spintronic applications.Here,combing density functional theory with non-equilibrium Green’s function technique.
基金funded by Ningbo Key R&D Plan and“Unveiling and Leading”(Grant No.2023Z093)Ningbo Science and Technology Innovation 2025 Major Special Project(Grant No.2022Z106)Hezhou City Central Leading Local Science and Technology Development Special Fund Project(Grant No.HK ZY2022002).
文摘The grain boundary phase affects the magnetic properties and corrosion resistance of sintered NdFeB magnets.In this work,a small amount of In was added to NdFeB magnets by induction melting to systematically investigate its effect on the evolution of the microstructure,magnetic properties and corrosion resistance of NdFeB magnets.Microstructural analysis illustrated that minor In addition generated more grain boundary phases and an abundant amorphous phase at the triple-junction grain boundary.While the addition of In failed to enhance the magnetic isolation effect between adjacent matrix grains,its incorporation fortuitously elevated the electrochemical potential of the In-containing magnets.Besides,during corrosion,an In-rich precipitate phase formed,hindering the ingress of the corrosive medium into the magnet.Consequently,this significantly bolstered the corrosion resistance of the sintered NdFeB magnets.The phase formation,magnetic properties and corrosion resistance of In-doped NdFeB magnets are detailed in this work,which provides new prospects for the preparation of high-performance sintered NdFeB magnets.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12034018 and 11625419).
文摘Conventional four-probe methods for measuring the resistance of Josephson junctions can damage superconducting thin films,making them unsuitable for frequency measurements of superconducting qubits.In this study,we present a custom probe station measurement system that employs the fritting contact technique to achieve in situ,non-destructive measurements of Josephson junction resistance.Our experimental results demonstrate that this method allows for accurate prediction of qubit frequency with an error margin of 17.2 MHz.Moreover,the fritting contact technique does not significantly affect qubit coherence time or the integrity of the superconducting film,confirming its non-destructive nature.This innovative approach provides a dependable foundation for frequency tuning and addressing frequency collision issues,thus supporting the advancement and practical deployment of superconducting quantum computing.
基金supported by the National Natural Science Foundation of China(22162012 and 22202089)the Youth Jinggang Scholars Program in Jiangxi Province([2019]57)+6 种基金the Thousand Talents Plan of Jiangxi Province(jxsq2019201083)the Natural Science Foundation of Jiangxi Province for Distinguished Young Scholars(20224ACB213005)the Program of Qingjiang Excellent Young Talents,Jiangxi University of Science and Technology(JXUSTQJBJ2019002)the Research Foundation of Education Bureau of Jiangxi Province of China(GJJ210833)the Foundation of State Key Laboratory of Physical Chemistry of Solid Surfaces(202022)the China Postdoctoral Science Foundation(2021M693893)the Jiangxi Provincial Key Laboratory of Functional Molecular Materials Chemistry(20212BCD42018)。
文摘Direct methanol fuel cells(DMFC) are widely considered to be an ideal green energy conversion device but their widespread applications are limited by the high price of the Pt-based catalysts and the instability in terms of surface CO toxicity in long-term operation.Herein,the PtFe alloy nanoparticles(NPs) with small particle size(~4.12 nm) supported on carbon black catalysts with different Pt/Fe atomic ratios(Pt_(1)Fe_(2)/C,Pt_(3)Fe_(4)/C,Pt_(1)Fe_(1)/C,and Pt_(2)Fe_(1)/C) are successfully prepared for enhanced anti-CO poisoning during methanol oxidation reaction(MOR).The optimal atomic ratio of Pt/Fe for the MOR is 1:2,and the mass activity of Pt_(1)Fe_(2)/C(5.40 A mg_(Pt)^(-1)) is 13.5 times higher than that of conventional commercial Pt/C(Pt/C-JM)(0.40 A mg_(Pt)^(-1)).The introduction of Fe into the Pt lattice forms the PtFe alloy phase,and the electron density of Pt is reduced after forming the PtFe alloy.In-situ Fourier transform infrared results indicate that the addition of oxyphilic metal Fe has reduced the adsorption of reactant molecules on Pt during the MOR.The doping of Fe atoms helps to desorb toxic intermediates and regenerate Pt active sites,promoting the cleavage of C-O bonds with good selectivity of CO_(2)(58.1%).Moreover,the Pt_(1)Fe_(2)/C catalyst exhibits higher CO tolerance,methanol electrooxidation activity,and long-term stability than other Pt_(x)Fe_(y)/C catalysts.
基金supported by the National Natural Science Foundation of China(11871238,11931019,12371486)。
文摘Drug resistance is one of the most intractable issues in targeted therapy for cancer diseases.It has also been demonstrated to be related to cancer heterogeneity,which promotes the emergence of treatment-refractory cancer cell populations.Focusing on how cancer cells develop resistance during the encounter with targeted drugs and the immune system,we propose a mathematical model for studying the dynamics of drug resistance in a conjoint heterogeneous tumor-immune setting.We analyze the local geometric properties of the equilibria of the model.Numerical simulations show that the selectively targeted removal of sensitive cancer cells may cause the initially heterogeneous population to become a more resistant population.Moreover,the decline of immune recruitment is a stronger determinant of cancer escape from immune surveillance or targeted therapy than the decay in immune predation strength.Sensitivity analysis of model parameters provides insight into the roles of the immune system combined with targeted therapy in determining treatment outcomes.
基金financially supported by the National Natural Science Foundation of China(No.ZX20230212)。
文摘During heavy oil recovery in the Bohai Oilfield,substantial emulsification of oil and water occurred,primarily forming water-in-oil emulsions.This phenomenon could alter fluid dynamics within the subsurface porous media,potentially impacting well production performance.To elucidate the properties of water-in-oil emulsions and their associated liquid resistance effects,this study conducted a series of rheological tests,microscopic examinations,and injection experiments.The results show that the droplet size and distribution of water-in-oil emulsions were primarily influenced by shear rate and water content,which in turn modified emulsion viscosity.The stability of water-in-oil emulsions was reduced when they flowed through porous media.The increase in emulsion viscosity and the liquid resistance effect collectively enhanced the seepage resistance of water-in-oil emulsions flowing through porous media.Notably,when the emulsion droplet size exceeded the pore throat size,over 90%of the total seepage resistance was attributable to the liquid resistance effect.Conversely,when the majority of the emulsion droplets were smaller than the pore throat,the viscosity accounted for more than 60%of the seepage resistance.Water-in-oil emulsions flowed through cores with permeabilities ranging from 50 to 100 mD,exhibiting threshold pressure gradients between 35 and 43 MPa/m.At a core permeability of 300 mD,the threshold pressure gradient was significantly reduced to 1 MPa/m.The presence of a waterin-oil emulsion in the reservoir could result in a production pressure differential falling below the threshold pressure,thereby reducing reservoir productivity.
基金National Key Laboratory of Science and Technology on Materials under Shock and Impact(Grant No.WDZC2022-4)to provide fund for conducting experiments。
文摘A reasonable heat treatment process for TC4 ELI titanium alloy is crucial to tune microstructures to improve its explosion resistance.However,there is limited investigation on tuning microstructures of TC4 ELI to improve explosion resistance.Moreover,the current challenge is quantifying microstructural changes'effects on explosion resistance and incorporating microstructural changes into finite element models.This work aims to tune microstructures to improve explosion resistance and elucidate their anti-explosion mechanism,and find a suitable method to incorporate microstructural changes into finite element models.In this work,we systematically study the deformation and failure characteristics of TC4 ELI plates with varying microstructures using an air explosion test and LS-DYNA finite element modeling.The Johnson-Cook(JC)constitutive parameters are used to quantify the effects of microstructural changes on explosion resistance and incorporate microstructural changes into finite element models.Because of the heat treatment,one plate has equiaxed microstructure and the other has bimodal microstructure.The convex of the plate after the explosion has a quadratic relationship with the charge mass,and the simulation results demonstrate high reliability,with the error less than 17.5%.Therefore,it is feasible to obtain corresponding JC constitutive parameters based on the differences in microstructures and mechanical properties and characterize the effects of microstructural changes on explosion resistance.The bimodal target exhibits excellent deformation resistance.The response of bimodal microstructure to the shock wave may be more intense under explosive loading.The well-coordinated structure of the bimodal target enhances its resistance to deformation.
基金by National Natural Science Foundation of China(81803224)Young Scholars Program of Shandong University(2018WLJH33)to X.G.+3 种基金National Natural Science Foundation of China(81973031)Cheeloo Young Scholar Program of Shandong University(21320089963054)to H.W.Young Scholars Program of Shandong University(2018WLJH34)the Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology(LMDBKF-2019-05)to L.D.
文摘With the prevalence of obesity and obesity-related metabolic syndrome,such as insulin resistance in recent years,it is urgent to explore effective interventions to prevent the progression of obesity-related metabolic syndrome.Palmitoleic acid is a monounsaturated fatty acid that is available from dietary sources,mainly derived from marine products.P almitoleic acid plays a positive role in maintaining glucose homeostasis and reducing inflammation.However,it is still unknow the mechanism of palmitoleic acid in ameliorating insulin resistance.Here,we investigated the effects of palmitoleic acid on chow diet(CD)-fed and high-fat diet(HFD)-fed mice,which were fed CD or HFD for 12 weeks before administration.We administrated mice with BSA(control),oleic acid,or palmitoleic acid for 6 weeks on top of CD or HFD feeding.We found that palmitoleic acid only improved glucose homeostasis in HFD-fed obese mice by increasing glucose clearance and reducing HOMA-IR.Further study explored that palmitoleic acid changed the composition of gut microbiota by decreasing Firmicutes population and increasing Bacteroidetes population.In colon,palmitoleic acid increased intestinal tight junction integrity and reduced inflammation.Moreover,palmitoleic acid decreased macrophage infiltration in liver and adipose tissue and increase glucose uptake in adipose tissue.Diacylglycerol(DAG)in tissue(for example,liver)is found to positively correlated with HOMA-IR.HFD enhanced the levels of DAGs in liver but not in adipose tissue in this study.Palmitoleic acid did not reverse the high DAG levels induced by HFD in liver.Therefore,in HFD-fed mice,palmitoleic acid reduced insulin resistance by an independent-manner of DAGs.It might be associated with the beneficial effects of palmitoleic acid on altering the gut microbiota composition,improving of intestinal barrier function,and downregulating the inflammation in colon,liver,and adipose tissue.
基金supported by the “Thirteenth Five Year” National Science and Technology Plan Project of China (2018YFC1603703,2018YFC1604302)National Natural Science Foundation of China (2013BAD18B03)+1 种基金Shenyang Technological Innovation Project (Y170-028)LiaoNing Revitalization Talents Project (XLYC1902083)
文摘This study investigated the effects of a xylitol-casein non-covalent complex(XC)on parameters related to type 2 diabetes mellitus(T2DM),in addition to related changes in gut microbiome composition and functions.High-fat-diet(HFD)+streptozotocin(STZ)-induced T2DM mice were treated with xylitol(XY),casein(CN),and XC,after which fecal samples were collected for gut microbiota composition and diversity analyses based on 16S rRNA high-throughput sequencing and multivariate statistics.XC decreased body weight and improved glucose tolerance,insulin sensitivity,pancreas impairment,blood lipid levels,and liver function in T2DM mice compared to XY-and CN-treated mice.Furthermore,XC modulated theα-diversity,β-diversity and gut microbiota composition.Based on Spearman’s correlation analysis,the relative abundances of Alistipes,Bacteroides,and Faecalibaculum were positively correlated and those of Akkermansia,Lactobacillus,Bifidobacterium,and Turicibacter were negatively correlated with the phenotypes related to the improvement of T2DM.In conclusion,we found that XC alleviated insulin resistance by restoring the gut microbiota of T2DM mice.Our results provide strong evidence for the beneficial effects of XC on T2DM and motivation for further investigation in animal models and,eventually,human trials.
基金supported by the National Natural Science Foundation of China(32172188)Science and Technology Cooperation Project of ZheJiang Province(2023SNJF058-3)。
文摘Multidrug-resistant(MDR)Enterobacteriaceae critically threaten duck farming and public health.The phenotypes,genotypes,and associated mobile genetic elements(MGEs)of MDR Enterobacteriaceae isolated from 6 duck farms in Zhejiang Province,China,were investigated.A total of 215 isolates were identified as Escherichia coli(64.65%),Klebsiella pneumoniae(12.09%),Proteus mirabilis(10.23%),Salmonella(8.84%),and Enterobacter cloacae(4.19%).Meanwhile,all isolates were resistant to at least two antibiotics.Most isolates carried tet(A)(85.12%),blaTEM(78.60%)and sul1(67.44%)resistance genes.Gene co-occurrence analysis showed that the resistance genes were associated with IS26 and integrons.A conjugative IncFII plasmid pSDM004 containing all the above MGEs was detected in Proteus mirabilis isolate SDM004.This isolate was resistant to 18 antibiotics and carried the blaNDM-5 gene.MGEs,especially plasmids,are the primary antibiotic resistance gene transmission route in duck farms.These findings provide a theoretical basis for the rational use of antibiotics in farms which are substantial for evaluating public health and food safety.
基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20200494)China Postdoctoral Science Foundation(Grant No.2021M701725)+3 种基金Jiangsu Postdoctoral Research Funding Program(Grant No.2021K522C)Fundamental Research Funds for the Central Universities(Grant No.30919011246)National Natural Science Foundation of China(Grant No.52278188)Natural Science Foundation of Jiangsu Province(Grant No.BK20211196)。
文摘To study the anti-explosion protection effect of polyurea coating on reinforced concrete box girder,two segmental girder specimens were made at a scale of 1:3,numbered as G(without polyurea coating)and PCG(with polyurea coating).The failure characteristics and dynamic responses of the specimens were compared through conducting explosion tests.The reliability of the numerical simulation using LS-DYNA software was verified by the test results.The effects of different scaled distances,reinforcement ratios,concrete strengths,coating thicknesses and ranges of polyurea were studied.The results show that the polyurea coating can effectively enhance the anti-explosion performance of the girder.The top plate of middle chamber in specimen G forms an elliptical penetrating hole,while that in specimen PCG only shows a very slight local dent.The peak vertical displacement and residual displacement of PCG decrease by 74.8% and 73.7%,respectively,compared with those of specimen G.For the TNT explosion with small equivalent,the polyurea coating has a more significant protective effect on reducing the size of fracture.With the increase of TNT equivalent,the protective effect of polyurea on reducing girder displacement becomes more significant.The optimal reinforcement ratio,concrete strength,thickness and range of polyurea coating were also drawn.
文摘In order to understand the influence of bow shape on ice resistance and provide guidelines for hull line design in the early design stage,an investigation of the impact of bow shape on ice resistance for the Arctic LNG carriers is carried out based on semi-empirical methods.Firstly,some typical semi-empirical formulas developed for ice resistance estimation of cargo carriers in different ice conditions are summarized.Then,formulas appropriate for ice resistance estimation of Arctic LNG carriers under different ice conditions are verified according to the result comparison between semi-empirical formulas and experimental tests.The comparison result indicates that the Lindqvist formula is appropriate for ice resistance estimation in level ice conditions,Zuev and Dobrodeev formula for ice resistance estimation in broken ice conditions,and Dobrodeev formula for ice resistance estimation in brash ice conditions.After that,the parameters considered in the selected formulas are summarized,and the influence of critical parameters on ice resistance is analyzed.Some parameters describing the ship's bow shape characteristic like ship breadth,waterline angle and stem angle greatly influence the ice resistance.Ice resistance increases with both the growth of ship breadth under all ice conditions and the growth of stem angle in level ice and broken ice conditions while ice resistance decreases with the development of waterline angle under all ice conditions.Finally,the optimization of the bow shape is discussed,and an optimized bow shape with both a large waterline angle and low stem angle is proposed.The optimized bow shape can decrease ice resistance by 9.9%in the level ice condition and reduce ice resistance by 11.3%in the brash ice condition.
基金supported by the National Natural Science Foundation of China(Nos.52222403,52074333,52120105007)Taishan Scholar Young Expert(No.tsqn202211079)。
文摘Slickwater fracturing fluids are widely used in the development of unconventional oil and gas resources due to the advantages of low cost,low formation damage and high drag reduction performance.However,their performance is severely affected at high temperatures.Drag reducing agent is the key to determine the drag reducing performance of slickwater.In this work,in order to further improve the temperature resistance of slickwater,a temperature-resistant polymeric drag reducing agent(PDRA)was synthesized and used as the basis for preparing the temperature-resistant slickwater.The slickwater system was prepared with the compositions of 0.2 wt%PDRA,0.05 wt%drainage aid nonylphenol polyoxyethylene ether phosphate(NPEP)and 0.5 wt%anti-expansion agent polyepichlorohydrindimethylamine(PDM).The drag reduction ability,rheology properties,temperature and shear resistance ability,and core damage property of slickwater were systematically studied and evaluated.In contrast to on-site drag reducing agent(DRA)and HPAM,the temperature-resistant slickwater demonstrates enhanced drag reduction efficacy at 90℃,exhibiting superior temperature and shear resistance ability.Notably,the drag reduction retention rate for the slickwater achieved an impressive 90.52%after a 30-min shearing period.Additionally,the core damage is only 5.53%.We expect that this study can broaden the application of slickwater in high-temperature reservoirs and provide a theoretical basis for field applications.
基金the financial support from the National Natural Science Foundation of China (Nos. 52074249, 51874261, 52304011)。
文摘The intensive development of tight reservoirs has positioned them as a strategic alternative to conventional oil and gas resources. Existing enhanced oil recovery(EOR) methods struggle to effectively exploring reservoir oil, resulting in low recovery rates. Novel and effective means of developing tight reservoirs are urgently needed. Nanomaterials have shown promising applications in improving water flooding efficiency, with in-depth research into mechanisms that lower injection pressure and increase water injection volumes. However, the extent of improvement remains limited. In this study, a silicon quantum dots(Si-QDs) material was synthesized via a hydrothermal synthesis method and used to prepare a nanofluid for the efficient recovery of tight reservoir. The Si-QDs, with an approximate diameter of 3 nm and a spherical structure, were surface functionalized with benzenesulfonic acid groups to enhance the performance. The developed nanofluid demonstrated stability without aggregation at 120℃ and a salinity of 60000 mg/L. Core flooding experiments have demonstrated the attractive EOR capabilities of Si-QDs, shedding light of the EOR mechanisms. Si-QDs effectively improve the wettability of rocks, enhancing the sweeping coefficient of injected fluids and expanding sweeping area.Within this sweeping region, Si-QDs efficiently stripping adsorbed oil from the matrix, thus increasing sweeping efficiency. Furthermore, Si-QDs could modify the state of pore-confined crude oil, breaking it down into smaller particles that are easier to displacement in subsequent stages. Si-QDs exhibit compelling EOR potential, positioning them as a promising approach for effectively developing tight oil reservoirs.
