The intermetallic compounds based on the tetragonal ThMn_(12) prototype crystal structure have exhibited great potential as advanced rare-earth-lean permanent magnets due to their excellent intrinsic magnetic properti...The intermetallic compounds based on the tetragonal ThMn_(12) prototype crystal structure have exhibited great potential as advanced rare-earth-lean permanent magnets due to their excellent intrinsic magnetic properties.However,the trade-off between the phase stability and the magnetic performance is often encountered in the ThMn_(12)-type magnets.This work was focused on the effects of V doping and nanos-tructuring on the phase stability and magnetic properties of ThMn_(12)-type Sm-Co-based magnets.Novel SmCo_(12)-based nanocrystalline alloys with the SmCo_(12) main phase were prepared for the first time.The prepared alloys from the optimal design achieved obviously higher coercivity than the isotropic SmFe_(12)-based alloys,together with comparable performance of other magnetic features.The enhancement in the coercivity was ascribed to the pinning of domain walls by the nanocrystalline grain boundaries and stacking faults.First-principles calculations and magnetic structure analysis disclosed that V substitution can stabilize the SmCo_(12) lattice and elevate its magnetocrystalline anisotropy.This study provides a new approach to developing stabilized metastable structured rare-earth-lean alloys with high magnetic per-formance.展开更多
In order to increase the stability of the Mongolia power system, a single-phase automatic reclosing device (SPAR) was introduced on double-circuit power lines built with a size of 330 kV, operating on a voltage of 220...In order to increase the stability of the Mongolia power system, a single-phase automatic reclosing device (SPAR) was introduced on double-circuit power lines built with a size of 330 kV, operating on a voltage of 220 kV and a length of 250 km. These overhead power lines (L-213, L-214) connect the 220/110/35 kV “Songino” substation with the “Mandal” substation and form system networks. This paper presents the challenges encountered when implementing single-phase automatic reclosing (SPAR) devices and compares the changes in power system parameters before and after SPAR deployment for a long 220 kV line. Simulations and analyses were carried out using DIgSILENT PowerFactory software, focusing on rotor angle stability, and the overall impact on the power system during short-circuit faults. The evaluation also utilized measurement data from the Wide Area Monitoring System (WAMS) to compare system behavior pre- and post-implementation of SPAR. The findings reveal that SPAR significantly enhances system reliability and stability, effectively mitigating the risk of oscillations and stability loss triggered by short circuits. This improvement contributes to a more resilient power system, reducing the potential for disturbances caused by faults.展开更多
Augmenting the working voltage is an effective way to maximize the energy density of Ni-rich layered Li[Ni_(0.8)Co_(0.1)Mn_(0.1)]O_(2)(NCM)to approach its theoretical capacity.However,NCM suffers from structural degra...Augmenting the working voltage is an effective way to maximize the energy density of Ni-rich layered Li[Ni_(0.8)Co_(0.1)Mn_(0.1)]O_(2)(NCM)to approach its theoretical capacity.However,NCM suffers from structural degradation in deep delithiation state,which is often accompanied by severe surface lattice oxygen loss and transition metal dissolution,leading to restricted cycle life.Herein,a facile and effective surfacestrengthening strategy is proposed,in which Mn(OH)_(2)nanoshells are uniformly grown on the NCM surface as a Li~+capturer and then converted to thin spinel Li_(4)Mn_(5)O_(12)layers during subsequent hightemperature sintering.The resultant Li_(4)Mn_(5)O_(12)layers can enhance cathode-electrolyte interface electrochemical stability with inhibited electrolyte corrosion and accelerated Li~+kinetics.The theoretical calculations confirms that the Mn-O bonds formed at the interfaces can effectively decrease the oxygen activity,thereby further inhibiting the lattice oxygen release and structural degradation caused by the irreversible phase transition.Consequently,the Li_(4)Mn_(5)O_(12)-coated NCM displays high capacity retention of 80.3%and 94.9%at 1 C and 5 C compared to the pristine NCM(52.5%and 10.1%)after 200 cycles and can operate stably at 2.7-4.6 V and 60℃.The spinel Li_(4)Mn_(5)O_(12)-coating demonstrates an effective route to enhance the structural/electrochemical stability of NCM for next-generation advanced lithium-ion batteries.展开更多
Selective electrocatalytic semi-hydrogenation(ECSH)of alkynes in water using Cu catalysts is highly relevant for the production of value-added chemicals.However,achieving high olefin selectivity still poses extreme ch...Selective electrocatalytic semi-hydrogenation(ECSH)of alkynes in water using Cu catalysts is highly relevant for the production of value-added chemicals.However,achieving high olefin selectivity still poses extreme challenges due to the susceptibility of the copper cathode in a reduction environment.Herein,a small molecule modulation electrodeposition strategy is introduced that regulates the structure of Cubased materials through modification with citric acid(CA)ligands,aiming for highly active and selective ECSH.The as-prepared EDCu-CA electrode achieves more than 97%alkyne conversion and 99%olefin selectivity.In-situ Raman and Auger electron spectroscopy(AES)data provide evidence that active Cu^(+)sites can stably exist in the EDCu-CA during the catalytic process.Density functional theory(DFT)calculations indicate that the modulation by CA contributes to maintaining Cu in a positive valence state,and Cu^(+)can inhibit the over-hydrogenation of olefins.Moreover,by utilizing a large-area electrode for longterm electrolysis,g-level conversion and a 92%separation yield of olefin can be achieved,demonstrating a viable application prospect.This study offers a promising route for designing Cu-based catalysts for the highly selective electrocata lytic conversion of organic substrates to value-added chemicals in water.展开更多
Neutral oxygen evolution reaction(OER)is a crucial half-reaction for electrocatalytic chemical production under mild condition,but with limited development due to low activity and poor stability.Herein,a tungsten-dope...Neutral oxygen evolution reaction(OER)is a crucial half-reaction for electrocatalytic chemical production under mild condition,but with limited development due to low activity and poor stability.Herein,a tungsten-doped cobalt molybdate(WDCMO)catalyst was synthesized for efficient and durable OER under neutral electrolyte.It is demonstrated that catalyst reconstruction is suppressed by W doping,which stabilizes the Co-O-Mo point-to-point connection in CoMoO_(4) architecture and stimulates to a lower valence state of active sites over the surface phase.Thereby,the surface structure maintains to avoid compound dissolution caused by over-oxidation during OER.Meanwhile,the WDCMO catalyst promotes charge transfer and optimizes*OH intermediate adsorption,which improves reaction kinetics and intrinsic activity.Consequently,the WDCMO electrode exhibits an overpotential of 302 mV at 10 mA cm^(-2) in neutral electrolyte with an improvement of 182 mV compared with CoMoO4 electrode.Furthermore,W doping significantly improves the electrode stability from 50 h to more than 320 h,with a suppressive potential attenuation from 2.82 to 0.29 mV h^(-1).This work will shed new light on designing rational electrocatalysts for neutral OER.展开更多
Understanding the factors triggering slope failure is essential to ensure the safety of buildings and transportation infrastructure on slopes. Specifically,the failure of stabilizing piles due to groundwater migration...Understanding the factors triggering slope failure is essential to ensure the safety of buildings and transportation infrastructure on slopes. Specifically,the failure of stabilizing piles due to groundwater migration and freeze–thaw(FT) cycles is a significant factor causing slope failure. This study aims to investigate the transmedia seepage characteristics at slope–concrete stabilizing pile interface systems by using silty clay and concrete with varying microstructure characteristics under FT cycles. To this end, a self-developed indoor test device for transmedia water migration, combined with a macro-meso-micro multiscale testing approach, was used to analyze the laws and mechanisms of transmedia seepage at the interface systems. The effect of the medium's microstructure characteristics on the transmedia seepage behavior at the interface systems under FT cycles was also assessed. Results indicated that the transmedia water migration exhibited particularity due to the migration of soil particles and the low permeability characteristics of concrete. The water content in the media increased significantly within the range of 1/3–2/3 of the height from the interface for soil and within 5 mm from the interface for concrete.FT cycles promoted the increase and penetration of cracks within the medium, enhancing the permeability of the slope-concrete stabilizing pile interface systems.With the increase in FT cycles, the porosity inside the medium first decreased and then increased, and the porosity reached the minimum after 25 FT cycles and the maximum after 75 FT cycles, and the water content of the medium after water migration was positively correlated with the porosity. FT cycles also significantly influenced the temporal variation characteristics of soil moisture and the migration path of water in concrete. The study results could serve as a reference for related research on slope stability assessment.展开更多
Vitamin C,a potent antioxidant with broad therapeutic applications,is limited by rapid degradation under environmental stressors,which compromises its stability and bioactivity.This study addresses these limitations b...Vitamin C,a potent antioxidant with broad therapeutic applications,is limited by rapid degradation under environmental stressors,which compromises its stability and bioactivity.This study addresses these limitations by formulating a double nano-emulsion(W/O/W)system incorporating macadamia oil and tea tree oil,using homogenization and phase inversion temperature(PIT)techniques.Comprehensive physicochemical charac-terization,including droplet size,polydispersity index(PDI),zeta potential,turbidity,Fourier transform infrared spectroscopy(FTIR),and SEM,was conducted alongside stability assessments under varying pH,temperature,and storage conditions.The optimized nano-emulsions exhibited nanoscale droplet sizes(10-40 nm),low PDI values(indicating high uniformity),and robust stability.Interestingly,the formulation with 2%W/O loading,with a particle size of 11.57 nm and a PDI of 0.04,demonstrated an antioxidant capacity of 4622.62μg ascorbic acid equivalents(AA)/g,which was significantly higher(p<0.05)compared to both natural oils(macadamia oil:20.91μg AA/g,tea tree oil:16.86μg AA/g)and a 10%Vitamin C aqueous solution(592.94μg AA/g).FTIR analysis confirmed the molecular integrity of Vitamin C and its successful encapsulation with macadamia and tea tree oils,while SEM images revealed uniformly spherical and well-dispersed droplets.Moreover,the formulation retained its structural integrity and antioxidant functionality under diverse pH and thermal conditions.These findings underscore the potential of double nano-emulsion systems to overcome the stability challenges of Vitamin C,offering a promising approach to enhance its bioavailability and therapeutic performance in phar-maceutical and cosmetic applications.展开更多
Niobium alloys have found extensive application in industries,such as aerospace,nuclear reactor,and emerging electronic technologies,owing to their high melting point,low density,and remarkable formability.Nevertheles...Niobium alloys have found extensive application in industries,such as aerospace,nuclear reactor,and emerging electronic technologies,owing to their high melting point,low density,and remarkable formability.Nevertheless,they still fall short in terms of comprehensive strength,toughness,and thermal stability when subjected to complex impacts and/or torsional forces during service.Here,a dual-phase(BCC/FCC)Nb alloy with attractive mechanical properties and thermal stability was designed by tuning stable element C in the Nb-BCC matrix assisted by hot deformation and aging processes.Our findings reveal that the formation of discontinuous carbides at the grain boundary promotes the phase transformation of the matrix from BCC to FCC(K-S orientation relationship),resulting in the formation of FCC thin layers and nano particles.This unique configuration hinders the slipping of dislocations during deformation and impedes the degeneration of microstructures during the thermal cycling process from 200°C to 900°C.Moreover,the discontinuous carbides at GBs provide channels to transfer dislocations between various phases and/or grains,which results in attractive mechanical properties and thermal stability.The ultimate tensile strength,yield strength,elongation,and elasticity modulus of the designed Nb alloy reach impressive values of 790.5 MPa,436.5 MPa,39.1%,and 63.5 MPa,respectively.These observations provide guidelines for designing dual-phase Nb alloys with remarkable strength,toughness,and thermal stability for aerospace applications by tuning the stabilizing element C in the Nb-BCC matrix.展开更多
ln order to improve the level of investment promotion and redouble effortsto enhance services,on February l9th,the 2025 Action Plan for StabilizingForeign lnvestment was released,proposing 20 measures in four aspects....ln order to improve the level of investment promotion and redouble effortsto enhance services,on February l9th,the 2025 Action Plan for StabilizingForeign lnvestment was released,proposing 20 measures in four aspects.Cur-rently,with increasing uncertainties in the external environment,China facesmultple difficulties and challenges in attracting foreign investment.展开更多
Aqueous sodium-ion batteries(ASIBs) offer significant advantages for energy storage on a large scale,attributed to their economical cost,secure operatio n,and eco-friend ly natu re.Among the leading cathode materials ...Aqueous sodium-ion batteries(ASIBs) offer significant advantages for energy storage on a large scale,attributed to their economical cost,secure operatio n,and eco-friend ly natu re.Among the leading cathode materials for ASIBs,Na_(3)V_(2)(PO_(4))_(3)(NVP) exhibits excellent structural stability and a high Na+diffusion coefficient,making it a promising option.However,the high solubility of vanadium-based materials in aqueous electrolytes engenders suboptimal cycling stability for Na_(3)V_(2)(PO_(4))_(3),constraining its application in ASIBs.Herein,the Cr-substituted Na_(3)V_(1.3)Cr_(0.7)(PO_(4))3@C(NV_(1.3)Cr_(0.7)P) cathode material was synthesized via a simple sol-gel method.It is found that Cr substitution reduces the cell parameters of NV_(1.3)Cr_(0.7)P,effectively reinforcing the crystal structure.Furthermore,NV_(1.3)Cr_(0.7)P alters the Na^(+)insertion/extraction mechanism,transforming the typical two-phase reaction between Na_(1)V_(2)(PO_(4))_(3)and Na_(3)V_(2)(PO_(4))3into continuous solid-solution reactions with stable intermediates.The Cr substitution diminishes the sodium-ion diffusion energy barrier in NV_(1.3)Cr_(0.7)P,leading to smoother Na+insertion and extraction processes.Consequently,NV_(1.3)Cr_(0.7)P exhibits impressive cycling stability,retaining 74.8% of its capacity after 5,000 cycles at a current density of 5 A g^(-1),along with an outstanding rate performance of 79,2% at 10 A g^(-1).This work elucidates the stable Na^(+)insertion/extraction processes in Cr-substituted NV_(1.3)Cr_(0.7)P,offering insights into the application of vanadium-based materials in aqueous sodium-ion batteries.展开更多
With the construction of the Three Gorges Reservoir dam,frequent reservoir landslide events have been recorded.In recent years,multi-row stabilizing piles(MRSPs)have been used to stabilize massive reservoir landslides...With the construction of the Three Gorges Reservoir dam,frequent reservoir landslide events have been recorded.In recent years,multi-row stabilizing piles(MRSPs)have been used to stabilize massive reservoir landslides in China.In this study,two centrifuge model tests were carried out to study the unreinforced and MRSP-reinforced slopes subjected to reservoir water level(RWL)operation,using the Taping landslide as a prototype.The results indicate that the RWL rising can provide lateral support within the submerged zone and then produce the inward seepage force,eventually strengthening the slope stability.However,a rapid RWL drawdown may induce outward seepage forces and a sudden debuttressing effect,consequently reducing the effective soil normal stress and triggering partial pre-failure within the RWL fluctuation zone.Furthermore,partial deformation and subsequent soil structure damage generate excess pore water pressures,ultimately leading to the overall failure of the reservoir landslide.This study also reveals that a rapid increase in the downslope driving force due to RWL drawdown significantly intensifies the lateral earth pressures exerted on the MRSPs.Conversely,the MRSPs possess a considerable reinforcement effect on the reservoir landslide,transforming the overall failure into a partial deformation and failure situated above and in front of the MRSPs.The mechanical transfer behavior observed in the MRSPs demonstrates a progressive alteration in relation to RWL fluctuations.As the RWL rises,the mechanical states among MRSPs exhibit a growing imbalance.The shear force transfer factor(i.e.the ratio of shear forces on pile of the n th row to that of the first row)increases significantly with the RWL drawdown.This indicates that the mechanical states among MRSPs tend toward an enhanced equilibrium.The insights gained from this study contribute to a more comprehensive understanding of the failure mechanisms of reservoir landslides and the mechanical behavior of MRSPs in reservoir banks.展开更多
Thermo-responsive nanocomposites have recently emerged as potential nanoplugging agents for shale stabilization in high-temperature water-based drilling fluids(WBDFs). However, their inhibitory properties have not bee...Thermo-responsive nanocomposites have recently emerged as potential nanoplugging agents for shale stabilization in high-temperature water-based drilling fluids(WBDFs). However, their inhibitory properties have not been very effective in high-temperature drilling operations. Thermo-responsive Janus nanocomposites are expected to strongly interact with clay particles from the inward hemisphere of nanomaterials, which drive the establishment of a tighter hydrophobic membrane over the shale surface at the outward hemisphere under geothermal conditions for shale stabilization. This work combines the synergistic benefits of thermo-responsive and zwitterionic nanomaterials to synchronously enhance the chemical inhibitions and plugging performances in shale under harsh conditions. A novel thermoresponsive Janus nanosilica(TRJS) exhibiting zwitterionic character was synthesized, characterized,and assessed as shale stabilizer for WBDFs at high temperatures. Compared to pristine nanosilica(Si NP)and symmetrical thermo-responsive nanosilica(TRS), TRJS exhibited anti-polyelectrolyte behaviour, in which electrolyte ions screened the electrostatic attraction between the charged particles, potentially stabilizing nanomaterial in hostile shaly environments(i.e., up to saturated brine or API brine). Macroscopically, TRJS exhibited higher chemical inhibition than Si NP and TRS in brine, prompting a better capability to control pressure penetration. TRJS adsorbed onto the clay surface via chemisorption and hydrogen bonding, and the interactions became substantial in brine, according to the results of electrophoretic mobility, surface wettability, and X-ray diffraction. Thus, contributing to the firm trapping of TRJS into the nanopore structure of the shale, triggering the formation of a tight hydrophobic membrane over the shale surface from the outward hemisphere. The addition of TRJS into WBDF had no deleterious effect on fluid properties after hot-treatment at 190℃, implying that TRJS could find potential use as a shale stabilizer in WBDFs in hostile environments.展开更多
Solution processability significantly advances the development of highly-efficient perovskite solar cells.However,the precursor solution tends to undergo irreversible degradation reactions,impairing the device perform...Solution processability significantly advances the development of highly-efficient perovskite solar cells.However,the precursor solution tends to undergo irreversible degradation reactions,impairing the device performance and reproducibility.Here,we utilize a reductive natural amino acid,Nacetylcysteine(NALC),to stabilize the precursor solution for printable carbon-based hole-conductorfree mesoscopic perovskite solar cells.We find that I_(2) can be generated in the aged solution containing methylammonium iodide(MI) in an inert atmosphere and speed up the MA-FA^(+)(formamidinium) reaction which produces large-size cations and hinders the formation of perovskite phase.NALC effectively stabilizes the precursor via its sulfhydryl group which reduces I_(2) back to I^(-)and provides H^(+).The NALC-stabilized precursor which is aged for 1440 h leads to devices with a power conversion efficiency equivalent to 98% of that for devices prepared with the fresh precursor.Furthermore,NALC improves the device power conversion efficiency from 16.16% to 18.41% along with enhanced stability under atmospheric conditions by modifying grain boundaries in perovskite films and reducing associated defects.展开更多
High-density coherent nanoprecipitates have been widely introduced into the design of new structural materials to achieve a superior strength-ductility balance.However,the thermal instability of nanostructures limits ...High-density coherent nanoprecipitates have been widely introduced into the design of new structural materials to achieve a superior strength-ductility balance.However,the thermal instability of nanostructures limits their fabrication and application.In this study,we investigated the temporal evolution of nanoprecipitates in coherent nanoprecipitation-strengthened Al_(0.5)Cr_(0.9)FeNi_(2.5)V_(0.2)high-entropy alloy during isothermal aging.When annealed at 600℃for more than 100 h,we found that its nanoprecipitates were invariably stable,with no obvious changes occurring in terms of morphology and distribution.The excellent stability was mainly attributed to the restricted state of interface migration and diffusion owing to the hierarchical nanostructure.The Cr-enriched nano-lamellar BCC phase divided the Cr-depleted FCC(L1_(2))matrix,forming barriers to long-range diffusion and resulting in a kinetically slow coarsening rate.As the nano-lamellar BCC phase spheroidized as the aging temperature increased to 700℃,the diffusion barriers were destroyed.Remarkable coarsening occurred after that,which further verified the significant effect of the nano-lamellar BCC phase on the microstructural stability.These results provide a paradigm for designing alloys stabilized via hierarchical nanostructure,achieving good strength-ductility synergy while excellent thermal stability.展开更多
Fatty acids are the main constituents of vegetable oils.To determine the fatty acid compositions of small trade vegetable oils and some less well studied beneficial vegetable oils,and investigate their relationships w...Fatty acids are the main constituents of vegetable oils.To determine the fatty acid compositions of small trade vegetable oils and some less well studied beneficial vegetable oils,and investigate their relationships with antioxidant activity and oxidative stability,gas chromatography-mass spectrometry was performed to characterize the associated fatty acid profiles.The antioxidant activity of vegetable oils,based on their DPPH-scavenging capacity(expressed as IC_(50) values),was used to assess their impact on human health,and their oxidative stability was characterized by performing lipid oxidation analysis to determine the oxidative induction time of fats and oils.In addition,correlation analyses were performed to examine associations between the fatty acid composition of the oils and DPPH-scavenging capacity and oxidative stability.The results revealed that among the assessed oils,coffee seed oil has the highest saturated fatty acid content(355.10 mg/g),whereas Garddenia jaminoides oil has the highest unsaturated fatty acid content(844.84 mg/g).Coffee seed oil was also found have the lowest DPPH IC_(50) value(2.30 mg/mL)and the longest oxidation induction time(17.09 h).Correlation analysis revealed a significant linear relationship(P<0.05)between oxidative stability and unsaturated fatty acid content,with lower contents tending to be associated with better oxidative stability.The findings of this study provide reference data for the screening of functional edible vegetable oils.展开更多
The pressing environmental concerns and the depletion of fossil fuel reserves necessitate a transition toward sustainable energy sources.Ethanol,a renewable biomass-derived fuel,is a promising alternative due to its a...The pressing environmental concerns and the depletion of fossil fuel reserves necessitate a transition toward sustainable energy sources.Ethanol,a renewable biomass-derived fuel,is a promising alternative due to its availability and high energy density.This study investigates the synthesis of gold nanoparticles(Au NPs)via a square-wave pulse deposition technique,aiming to enhance catalytic activity for ethanol electrooxidation.By varying pulse durations,we were able to exert precise control over Au NP size and distribution without stabilizing agents.Characterization using field emission scanning electron microscopy and X-ray diffraction techniques confirmed the formation of clustered nanoparticles of metallic gold phase.Electrochemical characteristics analyses revealed that Au NPs synthesized with a 900 ms pulse duration exhibited the lowest charge transfer resistance and the highest electrochemically active surface area.The electrocatalytic performance test of these Au NPs demonstrated an anodic current density of 2.5 mA cm^-(2)and a Tafel slope of 78 mV dec^(-1),indicating superior catalytic performance and reaction kinetics.Additionally,the Au NPs showed high resistance to poisoning,as evidenced by a low j_(b)/j_(f)ratio of 0.28 and stable chronoamperometric response.These findings underscore the potential of this synthesis method for producing high-performance electrocatalysts utilized in exploiting ethanol's potential as an environmentally friendly energy carrier.展开更多
Reversible solid oxide cell(RSOC)is a new energy conversion device with significant applications,especially for power grid peaking shaving.However,the reversible conversion process of power generation/energy storage p...Reversible solid oxide cell(RSOC)is a new energy conversion device with significant applications,especially for power grid peaking shaving.However,the reversible conversion process of power generation/energy storage poses challenges for the performance and stability of air electrodes.In this work,a novel high-entropy perovskite oxide La_(0.2)Pr_(0.2)Gd_(0.2)Sm_(0.2)Sr_(0.2)Co_(0.8)Fe_(0.2)O_(3−δ)(HE-LSCF)is proposed and investigated as an air electrode in RSOC.The electrochemical behavior of HE-LSCF was studied as an air electrode in both fuel cell and electrolysis modes.The polarization impedance(Rp)of the HE-LSCF electrode is only 0.25Ω·cm^(2) at 800℃ in an air atmosphere.Notably,at an electrolytic voltage of 2 V and a temperature of 800℃,the current density reaches up to 1.68 A/cm^(2).The HE-LSCF air electrode exhibited excellent reversibility and stability,and its electrochemical performance remains stable after 100 h of reversible operation.With these advantages,HE-LSCF is shown to be an excellent air electrode for RSOC.展开更多
Backfill is often employed in mining operations for ground support,with its positive impact on ground stability acknowledged in many underground mines.However,existing studies have predominantly focused only on the st...Backfill is often employed in mining operations for ground support,with its positive impact on ground stability acknowledged in many underground mines.However,existing studies have predominantly focused only on the stress development within the backfill material,leaving the influence of stope backfilling on stress distribution in surrounding rock mass and ground stability largely unexplored.Therefore,this paper presents numerical models in FLAC3D to investigate,for the first time,the time-dependent stress redistribution around a vertical backfilled stope and its implications on ground stability,considering the creep of surrounding rock mass.Using the Soft Soil constitutive model,the compressibility of backfill under large pressure was captured.It is found that the creep deformation of rock mass exercises compression on backfill and results in a less void ratio and increased modulus for fill material.The compacted backfill conversely influenced the stress distribution and ground stability of rock mass which was a combined effect of wall creep and compressibility of backfill.With the increase of time or/and creep deformation,the minimum principal stress in the rocks surrounding the backfilled stope increased towards the pre-mining stress state,while the deviatoric stress reduces leading to an increased factor of safety and improved ground stability.This improvement effect of backfill on ground stability increased with the increase of mine depth and stope height,while it is also more pronounced for the narrow stope,the backfill with a smaller compression index,and the soft rocks with a smaller viscosity coefficient.Furthermore,the results emphasize the importance of minimizing empty time and backfilling extracted stope as soon as possible for ground control.Reduction of filling gap height enhances the local stability around the roof of stope.展开更多
As the penetration rate of distributed energy increases,the transient power angle stability problem of the virtual synchronous generator(VSG)has gradually become prominent.In view of the situation that the grid impeda...As the penetration rate of distributed energy increases,the transient power angle stability problem of the virtual synchronous generator(VSG)has gradually become prominent.In view of the situation that the grid impedance ratio(R/X)is high and affects the transient power angle stability of VSG,this paper proposes a VSG transient power angle stability control strategy based on the combination of frequency difference feedback and virtual impedance.To improve the transient power angle stability of the VSG,a virtual impedance is adopted in the voltage loop to adjust the impedance ratio R/X;and the PI control feedback of the VSG frequency difference is introduced in the reactive powervoltage link of theVSGto enhance the damping effect.Thesecond-orderVSGdynamic nonlinearmodel considering the reactive power-voltage loop is established and the influence of different proportional integral(PI)control parameters on the system balance stability is analyzed.Moreover,the impact of the impedance ratio R/X on the transient power angle stability is presented using the equal area criterion.In the simulations,during the voltage dips with the reduction of R/X from 1.6 to 0.8,Δδ_(1)is reduced from 0.194 rad to 0.072 rad,Δf_(1)is reduced from 0.170 to 0.093 Hz,which shows better transient power angle stability.Simulation results verify that compared with traditional VSG,the proposedmethod can effectively improve the transient power angle stability of the system.展开更多
The present work aims to stabilize the room temperature allotropic transition of ammonium nitrate(AN)particles utilizing a microencapsulation technique,which involves solvent/non-solvent in which nitrocellulose(NC)has...The present work aims to stabilize the room temperature allotropic transition of ammonium nitrate(AN)particles utilizing a microencapsulation technique,which involves solvent/non-solvent in which nitrocellulose(NC)has been employed as a coating agent.The SEM micrographs revealed distinct features of both pure AN and NC,contrasting with the irregular granular surface topography of the coated AN particles,demonstrating the adherence of NC on the AN surface.Structural analysis via infrared spectroscopy(IR)demonstrated a successful association of AN and NC,with slight shifts observed in IR bands indicating interfacial interactions.Powder X-ray Diffraction(PXRD)analysis further elucidated the structural changes induced by the coating process,revealing that the NC coating altered the crystallization pattern of its pure form.Thermal analysis demonstrates distinct profiles for pure and coated AN,for which the coated sample exhibits a temperature increase and an enthalpy decrease of the room temperature allotropic transition by 6℃,and 36%,respectively.Furthermore,the presence of NC coating alters the intermolecular forces within the composite system,leading to a reduction in melting enthalpy of coated AN by~39%compared to pure AN.The thermal decomposition analysis shows a two-step thermolysis process for coated AN,with a significant increase in the released heat by about 78%accompanied by an increase in the activation barrier of NC and AN thermolysis,demonstrating a stabilized reactivity of the AN-NC particles.These findings highlight the synergistic effect of NC coating on AN particles,which contributed to a structural and reactive stabilization of both AN and NC,proving the potential application of NC-coated AN as a strategically advantageous oxidizer in composite solid propellant formulations.展开更多
基金supported by the National Key R&D Program of China(Nos.2021YFB3501502 and 2021YFB3501504).
文摘The intermetallic compounds based on the tetragonal ThMn_(12) prototype crystal structure have exhibited great potential as advanced rare-earth-lean permanent magnets due to their excellent intrinsic magnetic properties.However,the trade-off between the phase stability and the magnetic performance is often encountered in the ThMn_(12)-type magnets.This work was focused on the effects of V doping and nanos-tructuring on the phase stability and magnetic properties of ThMn_(12)-type Sm-Co-based magnets.Novel SmCo_(12)-based nanocrystalline alloys with the SmCo_(12) main phase were prepared for the first time.The prepared alloys from the optimal design achieved obviously higher coercivity than the isotropic SmFe_(12)-based alloys,together with comparable performance of other magnetic features.The enhancement in the coercivity was ascribed to the pinning of domain walls by the nanocrystalline grain boundaries and stacking faults.First-principles calculations and magnetic structure analysis disclosed that V substitution can stabilize the SmCo_(12) lattice and elevate its magnetocrystalline anisotropy.This study provides a new approach to developing stabilized metastable structured rare-earth-lean alloys with high magnetic per-formance.
文摘In order to increase the stability of the Mongolia power system, a single-phase automatic reclosing device (SPAR) was introduced on double-circuit power lines built with a size of 330 kV, operating on a voltage of 220 kV and a length of 250 km. These overhead power lines (L-213, L-214) connect the 220/110/35 kV “Songino” substation with the “Mandal” substation and form system networks. This paper presents the challenges encountered when implementing single-phase automatic reclosing (SPAR) devices and compares the changes in power system parameters before and after SPAR deployment for a long 220 kV line. Simulations and analyses were carried out using DIgSILENT PowerFactory software, focusing on rotor angle stability, and the overall impact on the power system during short-circuit faults. The evaluation also utilized measurement data from the Wide Area Monitoring System (WAMS) to compare system behavior pre- and post-implementation of SPAR. The findings reveal that SPAR significantly enhances system reliability and stability, effectively mitigating the risk of oscillations and stability loss triggered by short circuits. This improvement contributes to a more resilient power system, reducing the potential for disturbances caused by faults.
基金financial support from the Key Research and Development Project in Shaanxi Province(2023-YBGY-446)the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(No.2022SX-TD003)+1 种基金the Natural Science Basic Research Program of Shaanxi(No.2024JC-YBQN-0108)the Key Laboratory of Interface Science and Engineering in Advanced Materials,Ministry of Education(KLISEAM202202)。
文摘Augmenting the working voltage is an effective way to maximize the energy density of Ni-rich layered Li[Ni_(0.8)Co_(0.1)Mn_(0.1)]O_(2)(NCM)to approach its theoretical capacity.However,NCM suffers from structural degradation in deep delithiation state,which is often accompanied by severe surface lattice oxygen loss and transition metal dissolution,leading to restricted cycle life.Herein,a facile and effective surfacestrengthening strategy is proposed,in which Mn(OH)_(2)nanoshells are uniformly grown on the NCM surface as a Li~+capturer and then converted to thin spinel Li_(4)Mn_(5)O_(12)layers during subsequent hightemperature sintering.The resultant Li_(4)Mn_(5)O_(12)layers can enhance cathode-electrolyte interface electrochemical stability with inhibited electrolyte corrosion and accelerated Li~+kinetics.The theoretical calculations confirms that the Mn-O bonds formed at the interfaces can effectively decrease the oxygen activity,thereby further inhibiting the lattice oxygen release and structural degradation caused by the irreversible phase transition.Consequently,the Li_(4)Mn_(5)O_(12)-coated NCM displays high capacity retention of 80.3%and 94.9%at 1 C and 5 C compared to the pristine NCM(52.5%and 10.1%)after 200 cycles and can operate stably at 2.7-4.6 V and 60℃.The spinel Li_(4)Mn_(5)O_(12)-coating demonstrates an effective route to enhance the structural/electrochemical stability of NCM for next-generation advanced lithium-ion batteries.
基金financially supported by the National Natural Science Foundation of China(NSFC)(22179056,22172018)the Liaoning Revitalization Talents Program(XLYC2002097,1807210)+2 种基金the Key Projects of Liaoning Provincial Education Department(JYTZD2023001)the Fundamental Research Funds for the Central Universities(DUT23LAB611)Yingkou Talents Program。
文摘Selective electrocatalytic semi-hydrogenation(ECSH)of alkynes in water using Cu catalysts is highly relevant for the production of value-added chemicals.However,achieving high olefin selectivity still poses extreme challenges due to the susceptibility of the copper cathode in a reduction environment.Herein,a small molecule modulation electrodeposition strategy is introduced that regulates the structure of Cubased materials through modification with citric acid(CA)ligands,aiming for highly active and selective ECSH.The as-prepared EDCu-CA electrode achieves more than 97%alkyne conversion and 99%olefin selectivity.In-situ Raman and Auger electron spectroscopy(AES)data provide evidence that active Cu^(+)sites can stably exist in the EDCu-CA during the catalytic process.Density functional theory(DFT)calculations indicate that the modulation by CA contributes to maintaining Cu in a positive valence state,and Cu^(+)can inhibit the over-hydrogenation of olefins.Moreover,by utilizing a large-area electrode for longterm electrolysis,g-level conversion and a 92%separation yield of olefin can be achieved,demonstrating a viable application prospect.This study offers a promising route for designing Cu-based catalysts for the highly selective electrocata lytic conversion of organic substrates to value-added chemicals in water.
文摘Neutral oxygen evolution reaction(OER)is a crucial half-reaction for electrocatalytic chemical production under mild condition,but with limited development due to low activity and poor stability.Herein,a tungsten-doped cobalt molybdate(WDCMO)catalyst was synthesized for efficient and durable OER under neutral electrolyte.It is demonstrated that catalyst reconstruction is suppressed by W doping,which stabilizes the Co-O-Mo point-to-point connection in CoMoO_(4) architecture and stimulates to a lower valence state of active sites over the surface phase.Thereby,the surface structure maintains to avoid compound dissolution caused by over-oxidation during OER.Meanwhile,the WDCMO catalyst promotes charge transfer and optimizes*OH intermediate adsorption,which improves reaction kinetics and intrinsic activity.Consequently,the WDCMO electrode exhibits an overpotential of 302 mV at 10 mA cm^(-2) in neutral electrolyte with an improvement of 182 mV compared with CoMoO4 electrode.Furthermore,W doping significantly improves the electrode stability from 50 h to more than 320 h,with a suppressive potential attenuation from 2.82 to 0.29 mV h^(-1).This work will shed new light on designing rational electrocatalysts for neutral OER.
基金financially supported by Jilin Provincial Natural Science Foundation (No.20220101164JC)。
文摘Understanding the factors triggering slope failure is essential to ensure the safety of buildings and transportation infrastructure on slopes. Specifically,the failure of stabilizing piles due to groundwater migration and freeze–thaw(FT) cycles is a significant factor causing slope failure. This study aims to investigate the transmedia seepage characteristics at slope–concrete stabilizing pile interface systems by using silty clay and concrete with varying microstructure characteristics under FT cycles. To this end, a self-developed indoor test device for transmedia water migration, combined with a macro-meso-micro multiscale testing approach, was used to analyze the laws and mechanisms of transmedia seepage at the interface systems. The effect of the medium's microstructure characteristics on the transmedia seepage behavior at the interface systems under FT cycles was also assessed. Results indicated that the transmedia water migration exhibited particularity due to the migration of soil particles and the low permeability characteristics of concrete. The water content in the media increased significantly within the range of 1/3–2/3 of the height from the interface for soil and within 5 mm from the interface for concrete.FT cycles promoted the increase and penetration of cracks within the medium, enhancing the permeability of the slope-concrete stabilizing pile interface systems.With the increase in FT cycles, the porosity inside the medium first decreased and then increased, and the porosity reached the minimum after 25 FT cycles and the maximum after 75 FT cycles, and the water content of the medium after water migration was positively correlated with the porosity. FT cycles also significantly influenced the temporal variation characteristics of soil moisture and the migration path of water in concrete. The study results could serve as a reference for related research on slope stability assessment.
基金Ho Chi Minh City University of Technology(HCMUT),VNU-HCM for supporting this study.
文摘Vitamin C,a potent antioxidant with broad therapeutic applications,is limited by rapid degradation under environmental stressors,which compromises its stability and bioactivity.This study addresses these limitations by formulating a double nano-emulsion(W/O/W)system incorporating macadamia oil and tea tree oil,using homogenization and phase inversion temperature(PIT)techniques.Comprehensive physicochemical charac-terization,including droplet size,polydispersity index(PDI),zeta potential,turbidity,Fourier transform infrared spectroscopy(FTIR),and SEM,was conducted alongside stability assessments under varying pH,temperature,and storage conditions.The optimized nano-emulsions exhibited nanoscale droplet sizes(10-40 nm),low PDI values(indicating high uniformity),and robust stability.Interestingly,the formulation with 2%W/O loading,with a particle size of 11.57 nm and a PDI of 0.04,demonstrated an antioxidant capacity of 4622.62μg ascorbic acid equivalents(AA)/g,which was significantly higher(p<0.05)compared to both natural oils(macadamia oil:20.91μg AA/g,tea tree oil:16.86μg AA/g)and a 10%Vitamin C aqueous solution(592.94μg AA/g).FTIR analysis confirmed the molecular integrity of Vitamin C and its successful encapsulation with macadamia and tea tree oils,while SEM images revealed uniformly spherical and well-dispersed droplets.Moreover,the formulation retained its structural integrity and antioxidant functionality under diverse pH and thermal conditions.These findings underscore the potential of double nano-emulsion systems to overcome the stability challenges of Vitamin C,offering a promising approach to enhance its bioavailability and therapeutic performance in phar-maceutical and cosmetic applications.
基金supported financially by the National Natural Science Foundation of China(No.51901252)the Hunan Province Natural Science Foundation(No.2023JJ30684)the support from the State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China.
文摘Niobium alloys have found extensive application in industries,such as aerospace,nuclear reactor,and emerging electronic technologies,owing to their high melting point,low density,and remarkable formability.Nevertheless,they still fall short in terms of comprehensive strength,toughness,and thermal stability when subjected to complex impacts and/or torsional forces during service.Here,a dual-phase(BCC/FCC)Nb alloy with attractive mechanical properties and thermal stability was designed by tuning stable element C in the Nb-BCC matrix assisted by hot deformation and aging processes.Our findings reveal that the formation of discontinuous carbides at the grain boundary promotes the phase transformation of the matrix from BCC to FCC(K-S orientation relationship),resulting in the formation of FCC thin layers and nano particles.This unique configuration hinders the slipping of dislocations during deformation and impedes the degeneration of microstructures during the thermal cycling process from 200°C to 900°C.Moreover,the discontinuous carbides at GBs provide channels to transfer dislocations between various phases and/or grains,which results in attractive mechanical properties and thermal stability.The ultimate tensile strength,yield strength,elongation,and elasticity modulus of the designed Nb alloy reach impressive values of 790.5 MPa,436.5 MPa,39.1%,and 63.5 MPa,respectively.These observations provide guidelines for designing dual-phase Nb alloys with remarkable strength,toughness,and thermal stability for aerospace applications by tuning the stabilizing element C in the Nb-BCC matrix.
文摘ln order to improve the level of investment promotion and redouble effortsto enhance services,on February l9th,the 2025 Action Plan for StabilizingForeign lnvestment was released,proposing 20 measures in four aspects.Cur-rently,with increasing uncertainties in the external environment,China facesmultple difficulties and challenges in attracting foreign investment.
基金financially supported by the Scientific and Technological Plan Project of Guizhou Province ([2024]054)Additional support came from the Industry and Education Combination Innovation Platform of Intelligent Manufacturing and Graduate Joint Training Base at Guizhou University (2020-520000-83-01324061)the Guizhou Engineering Research Center for Smart Services (2203-520102-04-04-298868)。
文摘Aqueous sodium-ion batteries(ASIBs) offer significant advantages for energy storage on a large scale,attributed to their economical cost,secure operatio n,and eco-friend ly natu re.Among the leading cathode materials for ASIBs,Na_(3)V_(2)(PO_(4))_(3)(NVP) exhibits excellent structural stability and a high Na+diffusion coefficient,making it a promising option.However,the high solubility of vanadium-based materials in aqueous electrolytes engenders suboptimal cycling stability for Na_(3)V_(2)(PO_(4))_(3),constraining its application in ASIBs.Herein,the Cr-substituted Na_(3)V_(1.3)Cr_(0.7)(PO_(4))3@C(NV_(1.3)Cr_(0.7)P) cathode material was synthesized via a simple sol-gel method.It is found that Cr substitution reduces the cell parameters of NV_(1.3)Cr_(0.7)P,effectively reinforcing the crystal structure.Furthermore,NV_(1.3)Cr_(0.7)P alters the Na^(+)insertion/extraction mechanism,transforming the typical two-phase reaction between Na_(1)V_(2)(PO_(4))_(3)and Na_(3)V_(2)(PO_(4))3into continuous solid-solution reactions with stable intermediates.The Cr substitution diminishes the sodium-ion diffusion energy barrier in NV_(1.3)Cr_(0.7)P,leading to smoother Na+insertion and extraction processes.Consequently,NV_(1.3)Cr_(0.7)P exhibits impressive cycling stability,retaining 74.8% of its capacity after 5,000 cycles at a current density of 5 A g^(-1),along with an outstanding rate performance of 79,2% at 10 A g^(-1).This work elucidates the stable Na^(+)insertion/extraction processes in Cr-substituted NV_(1.3)Cr_(0.7)P,offering insights into the application of vanadium-based materials in aqueous sodium-ion batteries.
基金funded by Chongqing Natural Science Key Program of China(Grant No.cstc2020jcyj-zdxmX0019)China Geological Survey Program(Grant No.DD20190637/DD20221748).
文摘With the construction of the Three Gorges Reservoir dam,frequent reservoir landslide events have been recorded.In recent years,multi-row stabilizing piles(MRSPs)have been used to stabilize massive reservoir landslides in China.In this study,two centrifuge model tests were carried out to study the unreinforced and MRSP-reinforced slopes subjected to reservoir water level(RWL)operation,using the Taping landslide as a prototype.The results indicate that the RWL rising can provide lateral support within the submerged zone and then produce the inward seepage force,eventually strengthening the slope stability.However,a rapid RWL drawdown may induce outward seepage forces and a sudden debuttressing effect,consequently reducing the effective soil normal stress and triggering partial pre-failure within the RWL fluctuation zone.Furthermore,partial deformation and subsequent soil structure damage generate excess pore water pressures,ultimately leading to the overall failure of the reservoir landslide.This study also reveals that a rapid increase in the downslope driving force due to RWL drawdown significantly intensifies the lateral earth pressures exerted on the MRSPs.Conversely,the MRSPs possess a considerable reinforcement effect on the reservoir landslide,transforming the overall failure into a partial deformation and failure situated above and in front of the MRSPs.The mechanical transfer behavior observed in the MRSPs demonstrates a progressive alteration in relation to RWL fluctuations.As the RWL rises,the mechanical states among MRSPs exhibit a growing imbalance.The shear force transfer factor(i.e.the ratio of shear forces on pile of the n th row to that of the first row)increases significantly with the RWL drawdown.This indicates that the mechanical states among MRSPs tend toward an enhanced equilibrium.The insights gained from this study contribute to a more comprehensive understanding of the failure mechanisms of reservoir landslides and the mechanical behavior of MRSPs in reservoir banks.
基金financially supported by the National Natural Science Foundation of China(Grant No.52150410427)the Key Support Program for Foreign Experts of the Ministry of Science and Technology of the People's Republic of China(No.wgxz2022057)funding for post-doctoral work by the Department of Human Resources and Social Security of Hubei Province。
文摘Thermo-responsive nanocomposites have recently emerged as potential nanoplugging agents for shale stabilization in high-temperature water-based drilling fluids(WBDFs). However, their inhibitory properties have not been very effective in high-temperature drilling operations. Thermo-responsive Janus nanocomposites are expected to strongly interact with clay particles from the inward hemisphere of nanomaterials, which drive the establishment of a tighter hydrophobic membrane over the shale surface at the outward hemisphere under geothermal conditions for shale stabilization. This work combines the synergistic benefits of thermo-responsive and zwitterionic nanomaterials to synchronously enhance the chemical inhibitions and plugging performances in shale under harsh conditions. A novel thermoresponsive Janus nanosilica(TRJS) exhibiting zwitterionic character was synthesized, characterized,and assessed as shale stabilizer for WBDFs at high temperatures. Compared to pristine nanosilica(Si NP)and symmetrical thermo-responsive nanosilica(TRS), TRJS exhibited anti-polyelectrolyte behaviour, in which electrolyte ions screened the electrostatic attraction between the charged particles, potentially stabilizing nanomaterial in hostile shaly environments(i.e., up to saturated brine or API brine). Macroscopically, TRJS exhibited higher chemical inhibition than Si NP and TRS in brine, prompting a better capability to control pressure penetration. TRJS adsorbed onto the clay surface via chemisorption and hydrogen bonding, and the interactions became substantial in brine, according to the results of electrophoretic mobility, surface wettability, and X-ray diffraction. Thus, contributing to the firm trapping of TRJS into the nanopore structure of the shale, triggering the formation of a tight hydrophobic membrane over the shale surface from the outward hemisphere. The addition of TRJS into WBDF had no deleterious effect on fluid properties after hot-treatment at 190℃, implying that TRJS could find potential use as a shale stabilizer in WBDFs in hostile environments.
基金financial support from the National Natural Science Foundation of China(grant nos.52172198,51902117,and 91733301)。
文摘Solution processability significantly advances the development of highly-efficient perovskite solar cells.However,the precursor solution tends to undergo irreversible degradation reactions,impairing the device performance and reproducibility.Here,we utilize a reductive natural amino acid,Nacetylcysteine(NALC),to stabilize the precursor solution for printable carbon-based hole-conductorfree mesoscopic perovskite solar cells.We find that I_(2) can be generated in the aged solution containing methylammonium iodide(MI) in an inert atmosphere and speed up the MA-FA^(+)(formamidinium) reaction which produces large-size cations and hinders the formation of perovskite phase.NALC effectively stabilizes the precursor via its sulfhydryl group which reduces I_(2) back to I^(-)and provides H^(+).The NALC-stabilized precursor which is aged for 1440 h leads to devices with a power conversion efficiency equivalent to 98% of that for devices prepared with the fresh precursor.Furthermore,NALC improves the device power conversion efficiency from 16.16% to 18.41% along with enhanced stability under atmospheric conditions by modifying grain boundaries in perovskite films and reducing associated defects.
基金supported by the National Na-ture Science Foundation of China(Nos.U2241234,52201152,and 52301127)the China Postdoctoral Science Foundation(No.2022M720150)the Advanced Photon Source at Argonne National Laboratory was supported by the US Department of En-ergy(No.DE-AC02-06CH11357).
文摘High-density coherent nanoprecipitates have been widely introduced into the design of new structural materials to achieve a superior strength-ductility balance.However,the thermal instability of nanostructures limits their fabrication and application.In this study,we investigated the temporal evolution of nanoprecipitates in coherent nanoprecipitation-strengthened Al_(0.5)Cr_(0.9)FeNi_(2.5)V_(0.2)high-entropy alloy during isothermal aging.When annealed at 600℃for more than 100 h,we found that its nanoprecipitates were invariably stable,with no obvious changes occurring in terms of morphology and distribution.The excellent stability was mainly attributed to the restricted state of interface migration and diffusion owing to the hierarchical nanostructure.The Cr-enriched nano-lamellar BCC phase divided the Cr-depleted FCC(L1_(2))matrix,forming barriers to long-range diffusion and resulting in a kinetically slow coarsening rate.As the nano-lamellar BCC phase spheroidized as the aging temperature increased to 700℃,the diffusion barriers were destroyed.Remarkable coarsening occurred after that,which further verified the significant effect of the nano-lamellar BCC phase on the microstructural stability.These results provide a paradigm for designing alloys stabilized via hierarchical nanostructure,achieving good strength-ductility synergy while excellent thermal stability.
文摘Fatty acids are the main constituents of vegetable oils.To determine the fatty acid compositions of small trade vegetable oils and some less well studied beneficial vegetable oils,and investigate their relationships with antioxidant activity and oxidative stability,gas chromatography-mass spectrometry was performed to characterize the associated fatty acid profiles.The antioxidant activity of vegetable oils,based on their DPPH-scavenging capacity(expressed as IC_(50) values),was used to assess their impact on human health,and their oxidative stability was characterized by performing lipid oxidation analysis to determine the oxidative induction time of fats and oils.In addition,correlation analyses were performed to examine associations between the fatty acid composition of the oils and DPPH-scavenging capacity and oxidative stability.The results revealed that among the assessed oils,coffee seed oil has the highest saturated fatty acid content(355.10 mg/g),whereas Garddenia jaminoides oil has the highest unsaturated fatty acid content(844.84 mg/g).Coffee seed oil was also found have the lowest DPPH IC_(50) value(2.30 mg/mL)and the longest oxidation induction time(17.09 h).Correlation analysis revealed a significant linear relationship(P<0.05)between oxidative stability and unsaturated fatty acid content,with lower contents tending to be associated with better oxidative stability.The findings of this study provide reference data for the screening of functional edible vegetable oils.
基金supported by the National Research and Innovation Agency(BRIN)and Lembaga Pengelola Dana Pendidikan(LPDP)Ministry of Finance,Republic of Indonesia through Riset dan Inovasi Untuk Indonesia Maju(RIIM)scheme batch 2 with contract number 1/PG.02.00.PT/LPPM/IV/2024(110/IV/KS/11/2022).
文摘The pressing environmental concerns and the depletion of fossil fuel reserves necessitate a transition toward sustainable energy sources.Ethanol,a renewable biomass-derived fuel,is a promising alternative due to its availability and high energy density.This study investigates the synthesis of gold nanoparticles(Au NPs)via a square-wave pulse deposition technique,aiming to enhance catalytic activity for ethanol electrooxidation.By varying pulse durations,we were able to exert precise control over Au NP size and distribution without stabilizing agents.Characterization using field emission scanning electron microscopy and X-ray diffraction techniques confirmed the formation of clustered nanoparticles of metallic gold phase.Electrochemical characteristics analyses revealed that Au NPs synthesized with a 900 ms pulse duration exhibited the lowest charge transfer resistance and the highest electrochemically active surface area.The electrocatalytic performance test of these Au NPs demonstrated an anodic current density of 2.5 mA cm^-(2)and a Tafel slope of 78 mV dec^(-1),indicating superior catalytic performance and reaction kinetics.Additionally,the Au NPs showed high resistance to poisoning,as evidenced by a low j_(b)/j_(f)ratio of 0.28 and stable chronoamperometric response.These findings underscore the potential of this synthesis method for producing high-performance electrocatalysts utilized in exploiting ethanol's potential as an environmentally friendly energy carrier.
基金supported by Fundamental Research Funds for the Central Universities(2023KYJD1008)the Science Research Projects of the Anhui Higher Education Institutions of China(2022AH051582).
文摘Reversible solid oxide cell(RSOC)is a new energy conversion device with significant applications,especially for power grid peaking shaving.However,the reversible conversion process of power generation/energy storage poses challenges for the performance and stability of air electrodes.In this work,a novel high-entropy perovskite oxide La_(0.2)Pr_(0.2)Gd_(0.2)Sm_(0.2)Sr_(0.2)Co_(0.8)Fe_(0.2)O_(3−δ)(HE-LSCF)is proposed and investigated as an air electrode in RSOC.The electrochemical behavior of HE-LSCF was studied as an air electrode in both fuel cell and electrolysis modes.The polarization impedance(Rp)of the HE-LSCF electrode is only 0.25Ω·cm^(2) at 800℃ in an air atmosphere.Notably,at an electrolytic voltage of 2 V and a temperature of 800℃,the current density reaches up to 1.68 A/cm^(2).The HE-LSCF air electrode exhibited excellent reversibility and stability,and its electrochemical performance remains stable after 100 h of reversible operation.With these advantages,HE-LSCF is shown to be an excellent air electrode for RSOC.
基金the funding support from the National Natural Science Foundation of China(Grant Nos.52304101 and 52004206)the China Postdoctoral Science Foundation(Grant No.2023MD734215)。
文摘Backfill is often employed in mining operations for ground support,with its positive impact on ground stability acknowledged in many underground mines.However,existing studies have predominantly focused only on the stress development within the backfill material,leaving the influence of stope backfilling on stress distribution in surrounding rock mass and ground stability largely unexplored.Therefore,this paper presents numerical models in FLAC3D to investigate,for the first time,the time-dependent stress redistribution around a vertical backfilled stope and its implications on ground stability,considering the creep of surrounding rock mass.Using the Soft Soil constitutive model,the compressibility of backfill under large pressure was captured.It is found that the creep deformation of rock mass exercises compression on backfill and results in a less void ratio and increased modulus for fill material.The compacted backfill conversely influenced the stress distribution and ground stability of rock mass which was a combined effect of wall creep and compressibility of backfill.With the increase of time or/and creep deformation,the minimum principal stress in the rocks surrounding the backfilled stope increased towards the pre-mining stress state,while the deviatoric stress reduces leading to an increased factor of safety and improved ground stability.This improvement effect of backfill on ground stability increased with the increase of mine depth and stope height,while it is also more pronounced for the narrow stope,the backfill with a smaller compression index,and the soft rocks with a smaller viscosity coefficient.Furthermore,the results emphasize the importance of minimizing empty time and backfilling extracted stope as soon as possible for ground control.Reduction of filling gap height enhances the local stability around the roof of stope.
基金supported by theMajor Science and Technology Projects of China Southern Power Grid(Grant number CGYKJXM20210328).
文摘As the penetration rate of distributed energy increases,the transient power angle stability problem of the virtual synchronous generator(VSG)has gradually become prominent.In view of the situation that the grid impedance ratio(R/X)is high and affects the transient power angle stability of VSG,this paper proposes a VSG transient power angle stability control strategy based on the combination of frequency difference feedback and virtual impedance.To improve the transient power angle stability of the VSG,a virtual impedance is adopted in the voltage loop to adjust the impedance ratio R/X;and the PI control feedback of the VSG frequency difference is introduced in the reactive powervoltage link of theVSGto enhance the damping effect.Thesecond-orderVSGdynamic nonlinearmodel considering the reactive power-voltage loop is established and the influence of different proportional integral(PI)control parameters on the system balance stability is analyzed.Moreover,the impact of the impedance ratio R/X on the transient power angle stability is presented using the equal area criterion.In the simulations,during the voltage dips with the reduction of R/X from 1.6 to 0.8,Δδ_(1)is reduced from 0.194 rad to 0.072 rad,Δf_(1)is reduced from 0.170 to 0.093 Hz,which shows better transient power angle stability.Simulation results verify that compared with traditional VSG,the proposedmethod can effectively improve the transient power angle stability of the system.
文摘The present work aims to stabilize the room temperature allotropic transition of ammonium nitrate(AN)particles utilizing a microencapsulation technique,which involves solvent/non-solvent in which nitrocellulose(NC)has been employed as a coating agent.The SEM micrographs revealed distinct features of both pure AN and NC,contrasting with the irregular granular surface topography of the coated AN particles,demonstrating the adherence of NC on the AN surface.Structural analysis via infrared spectroscopy(IR)demonstrated a successful association of AN and NC,with slight shifts observed in IR bands indicating interfacial interactions.Powder X-ray Diffraction(PXRD)analysis further elucidated the structural changes induced by the coating process,revealing that the NC coating altered the crystallization pattern of its pure form.Thermal analysis demonstrates distinct profiles for pure and coated AN,for which the coated sample exhibits a temperature increase and an enthalpy decrease of the room temperature allotropic transition by 6℃,and 36%,respectively.Furthermore,the presence of NC coating alters the intermolecular forces within the composite system,leading to a reduction in melting enthalpy of coated AN by~39%compared to pure AN.The thermal decomposition analysis shows a two-step thermolysis process for coated AN,with a significant increase in the released heat by about 78%accompanied by an increase in the activation barrier of NC and AN thermolysis,demonstrating a stabilized reactivity of the AN-NC particles.These findings highlight the synergistic effect of NC coating on AN particles,which contributed to a structural and reactive stabilization of both AN and NC,proving the potential application of NC-coated AN as a strategically advantageous oxidizer in composite solid propellant formulations.
