This paper discussed the setting up of a comeuter automatic system for testing the dy-namic dissociating tension of cooked cocoon filament by means of microcomputer tech-niques.The dynamic dissociating tension of two ...This paper discussed the setting up of a comeuter automatic system for testing the dy-namic dissociating tension of cooked cocoon filament by means of microcomputer tech-niques.The dynamic dissociating tension of two kinds of row cocoons with differentreelability was tested and analysed under different cocoon cooking conditions.More relia-ble data have been obtained by quantitative tests.The conclusions reached by analysingthese data are of practical significance to perfecting the cocoon cooking theory,assessingcocoon quality,improving the cocoon cooking process,etc.展开更多
We theoretically investigate the production of cold CN molecules by photodissociating ICN precursors in a brute-force field. The energy shifts and adiabatic orientation of the rotational ICN precursors are first inves...We theoretically investigate the production of cold CN molecules by photodissociating ICN precursors in a brute-force field. The energy shifts and adiabatic orientation of the rotational ICN precursors are first investigated as a function of the external field strength. The dynamical photofragmentation of ICN precursors is numerically simulated for cases with and without orienting field. The CN products are compared in terms of their velocity distributions. A small portion of the CN fragments are recoiled to near zero speed in the lab frame by appropriately selecting the photo energy for dissociation. With a precursor ICN molecular beam of - 1.5 K in rotational temperature, the production of low speed CN fragments can be improved by more than 5 times when an orienting electrical field of 100 k V/cm is present. The corresponding production rate for decelerated fragments with speeds ≤ 50 m/s is simulated to be about ～2.1×10^-4 and CN number densities of 10^8 –10^10 cm^-3 can be reached with precursor ICN densities of ～10^12 –10^14 cm^-3 from supersonic expansion.展开更多
Electrocatalytic oxidation of glycerol for value-added chemicals is a superior strategy to utilize the excess glycerol produced in the biodiesel industry.Pd is one of the few active catalysts for alkaline glycerol oxi...Electrocatalytic oxidation of glycerol for value-added chemicals is a superior strategy to utilize the excess glycerol produced in the biodiesel industry.Pd is one of the few active catalysts for alkaline glycerol oxidation reaction(GOR);however,glycerol inevitably dissociates and converts to carbon dioxide on the Pd surface,which results in its low total Faradaic efficiency(FE)for high-value-added products.Herein,a series of Pd/C and Pd10Bix/C catalysts were synthesized to investigate the GOR pathway.The Pd10Bi3/C catalyst with optimal Bi content achieved an excellent GOR mass activity of 7.5±0.2 A mgPd−1 and an outstanding total FE of 90%±3%,which are much higher than those values on Pd/C(1.2±0.2 A mgPd−1 for mass activity and 63%±4%for total FE).Combined results of in-situ attenuated total reflection surface enhanced infrared absorption spectroscopy and density functional theory calculations show that Bi suppresses the dissociation of glycerol through the“shielding effect”of Bi to the adjacent Pd sites,which weakens the adsorption strength of GOR intermediates on those sites.This work provides a new insight into the GOR mechanism and puts forward a valid strategy for the rational design of catalysts to enable the transformation of glycerol into high-value-added products.展开更多
Electrocatalytic co-reduction of CO_(2)and nitrate offers an attractive and sustainable pathway for urea synthesis,as it enables the simultaneous valorization of nitrogenous waste and CO_(2)into value-added chemicals....Electrocatalytic co-reduction of CO_(2)and nitrate offers an attractive and sustainable pathway for urea synthesis,as it enables the simultaneous valorization of nitrogenous waste and CO_(2)into value-added chemicals.However,achieving ambient and high-performance urea electrosynthesis remains a persistent challenge,as it requires the simultaneous activation of CO_(2)and efficient H_(2)O dissociation to supply active^(*)H for^(*)NO x hydrogenation—ultimately forming key Cand N-containing intermediates necessary for effective C-N coupling.The stringent,sequential nature of the reaction requirements continues to present substantial challenges for the rational design of advanced multifunctional catalysts.Herein,we report a creative two-in-one catalyst,bifunctional Pd-single-atom-modified Cu(Pd_(1)Cu)nanorods,to synergistically promote the adsorption and stepwise activation of dual species,that is,CO_(2)and H_(2)O,thereby effectively steering the reaction pathway toward the highly selective synthesis of urea.By integrating experimental evidence,in situ spectroscopy,and computational analyses,we clearly disclose that the atomically dispersed Pd sites kinetically favor the co-generation of^(*)CO and^(*)NH_(2)(via H_(2)O dissociation-driven proton transfer),thereby forming an optimal intermediate balance that facilitates urea synthesis.More importantly,the rationally designed Pd_(1)Cu leverages dual metal active sites to enhance C-N coupling via combined electronic and geometric effects,substantially lowering the reaction energy barrier and improving selectivity toward urea.展开更多
Accurate temperature measurement is a crucial step in predicting and managing the aerodynamic heating during Mars entry and Earth reentry.These processes often occur at extremely high temperatures and pose challenges ...Accurate temperature measurement is a crucial step in predicting and managing the aerodynamic heating during Mars entry and Earth reentry.These processes often occur at extremely high temperatures and pose challenges for quantitative measurements.A 1-μs time-resolved laser absorption technique was developed for simultaneous and time-dependent temperature and CO-concentration measurements over 3000-6000 K by adopting the P(0,21)and P(2,15)lines.To achieve quantitative measurement,the line strengths and Ar-broadening parameters were calibrated within 3030-5980 K.A“W”-shaped path-amplified strategy was used to increase the absorption features of the two lines during the calibration process.Validation experiments were conducted at 3040-5970 K to verify the accuracy of the technique.The new technique was then applied for simultaneous and time-resolved temperature and CO-concentration measurements during the CO_(2)dissociation process to further demonstrate the feasibility of the developed technique.The temperature-dependent CO_(2)absorption cross-sections at line centers of the two lines were calibrated within 2040-5870 K.The CO_(2)absorption interferences were quantified and subtracted from the measured laser absorbances.The measured results(referring to temperature and CO concentration)were generally consistent with the predictions from the kinetics mechanisms in the literature,highlighting the applicability of the developed technique for temperature measurements and CO_(2)dissociation studies within the investigated temperature range.展开更多
CO_(2)utilization powered by sustainable energy offers a promising route to mitigate carbon emissions while producing value-added chemicals[1].Among these pathways,CO_(2)hydrogenation is especially attractive because ...CO_(2)utilization powered by sustainable energy offers a promising route to mitigate carbon emissions while producing value-added chemicals[1].Among these pathways,CO_(2)hydrogenation is especially attractive because it integrates renewable H 2 with carbon resources,which have achieved notable success in producing methanol,CO,etc.[2,3].展开更多
The accumulation and circulation of carbon and hydrogen contribute to the chemical evolution of ice giant planets.Species separation and diamond precipitation have been reported in carbon-hydrogen systems and have bee...The accumulation and circulation of carbon and hydrogen contribute to the chemical evolution of ice giant planets.Species separation and diamond precipitation have been reported in carbon-hydrogen systems and have been verified by static and shock compression experiments.Nevertheless,the dynamic formation processes underlying these phenomena remain insufficiently understood.In combination with a deep learning model,we demonstrate that diamonds form through a three-step process involving dissociation,species separation,and nucleation processes.Under shock conditions of 125 GPa and 4590 K,hydrocarbons decompose to give hydrogen and low-molecular-weight alkanes(CH_(4) and C_(2)H_(6)),which escape from the carbon chains,resulting in C/H species separation.The remaining carbon atoms without C-H bonds accumulate and nucleate to form diamond crystals.The process of diamond growth is associated with a critical nucleus size at which the dynamic energy barrier plays a key role.These dynamic processes of diamond formation provide insight into the establishment of a model for the evolution of ice giant planets.展开更多
Composite solid electrolytes(CSEs)are considered among the most promising candidates for solid-state batteries.However,their practical application is hindered by low ionic conductivity and a limited lithium-ion transf...Composite solid electrolytes(CSEs)are considered among the most promising candidates for solid-state batteries.However,their practical application is hindered by low ionic conductivity and a limited lithium-ion transference number,primarily owing to the insufficient mobility of Li+.In this work,we design a heterojunc-tion nanoparticle composed of bimetallic zeolitic imidazolate frameworks(ZIFs)coupled with amorphous tita-nium oxide(TiO_(2)@Zn/Co–ZIF)as a filler to fabricate a composite solid-state electrolyte(PVZT).The amor-phous TiO_(2) coating facilitates salt dissociation through Lewis acid–base interactions with the anions of the lithium salt.Meanwhile,the Zn/Co–ZIF framework not only provides additional selective pathways for Li+transport but also effectively restricts anion migration through its confined pore size.The synergistic effect results in a high room-temperature ionic conductivity(8.8×10^(-4) S·cm^(-1))and a lithium-ion transference number of 0.47 for PVZT.A symmetrical cell using PVZT demonstrates stable Li+deposition/stripping for over 1100 h at a current density of 0.1 mA·cm^(-2).Additionally,a LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)/Li full cell using PVZT retains 75.0%of its capacity after 1200 cycles at a 2 C rate.This work offers valuable insights into the design of func-tional fillers for CSEs with highly efficient ion transport.展开更多
Carbon nanotube formation exemplifies atomically precise self-assembly,where atomic interactions dynamically engineer nanoscale architectures with emergent properties that transcend classical material boundaries.Howev...Carbon nanotube formation exemplifies atomically precise self-assembly,where atomic interactions dynamically engineer nanoscale architectures with emergent properties that transcend classical material boundaries.However,elucidating the transient molecular intermediates remains a critical mechanistic frontier.This study investigates the atomic-scale nucleation process of single-walled carbon nanotubes(SWCNTs)from acetylene on iron(Fe)clusters,utilizing GFN(-x)TB-based nanoreactor molecular dynamics simulations.The simulations reveal a consistent nucleation pathway,regardless of iron cluster size(Fe_(13),Fe_(38),Fe_(55)),where the chemisorption and dissociation of acetylene molecules on the Fe clusters lead to the formation of C_(2)H and C_(2)intermediates.These species then undergo oligomerization,initiating the growth of carbon chains.As the chains cross-link and cyclize,five-membered carbon rings are preferentially formed,which eventually evolve into six-membered rings and more complex sp2-hybridized carbon networks,resembling the cap structures of nascent SWCNTs.Although the nucleation mechanism remains similar across all cluster sizes,larger clusters show enhanced catalytic activity,leading to higher molecular weight hydrocarbons and more extensive carbocyclic networks due to their higher density of active sites per reacting molecule.Crucially,the study highlights the role of C_(2)H as the key active species in the carbon network formation process.These findings offer critical insights into the initial stages of SWCNT nucleation,contributing to a deeper understanding of the mechanisms driving SWCNT growth and guiding the development of optimized synthetic strategies.展开更多
For a simple graph G,let A(G)and D(G)be the adjacency matrix and the diagonal degree matrix of G,respectively.[Appl.Anal.Discrete Math.,2017,11(1):81-107]defined the matrix A_(α)(G)of G as A_(α)(G)=αD(G)(1-α)A(G)...For a simple graph G,let A(G)and D(G)be the adjacency matrix and the diagonal degree matrix of G,respectively.[Appl.Anal.Discrete Math.,2017,11(1):81-107]defined the matrix A_(α)(G)of G as A_(α)(G)=αD(G)(1-α)A(G),α∈[0,1].The Aa-spectral radius is the largest eigenvalue of A_(α)(G).Let G_(n,β) be the set graphs with order n and dissociation numberβ.In this paper,we identify the b with maximal A_(α)-spectral radius among all graphs in G_(n,β).展开更多
The dicarbon(C_(2))molecule is an important molecular species observed in many carbon-containing gaseous environments.The spectroscopic and dissociative studies of C_(2)have attracted great attention for a long time f...The dicarbon(C_(2))molecule is an important molecular species observed in many carbon-containing gaseous environments.The spectroscopic and dissociative studies of C_(2)have attracted great attention for a long time for understanding its electronic characters as well as the evolution and cycling of carbon in the universe.In this study,the lifetimes of C_(2)populated at the three high-lying electronic states of(2-4)^(3)Δ_(g) in the vacuum ultraviolet(VUV)region have been experimentally measured using a time-of-flight mass spectrometer and the VUV-pump-UV-probe photoionization scheme.The measurements showed that all the rovibronic levels in the 2(g)^(3)Δ_(g) state exhibit shorter lifetimes than the dynamical limit of the experimental method,consistent with the theoretically predicted radiative lifetimes.Dependence of the lifetime on the vibrational level was observed in the 3^(3)Δ_(g) state,and a marginal rotational dependence was noticed in the vʹ=1 vibrational level.For the 4^(3)Δ_(g) state,the rotationally resolved lifetimes in the vʹ=1 vibrational level were found to be slightly longer than those in the vʹ=0 and 2 vibrational levels.Such a complicated dependence of the lifetime on the rovibronic level makes further experimental and theoretical investigations highly desired for understanding the dynamics in the high-lying excited states of C_(2).展开更多
As antibiotic pollutants cannot be incompletely removed by conventional wastewater treatment plants,ultraviolet(UV)based advanced oxidation processes(AOPs)such as UV/persulfate(UV/PS)and UV/chlorine are increasingly c...As antibiotic pollutants cannot be incompletely removed by conventional wastewater treatment plants,ultraviolet(UV)based advanced oxidation processes(AOPs)such as UV/persulfate(UV/PS)and UV/chlorine are increasingly concerned for the effective removal of antibiotics from wastewaters.However,the specific mechanisms involving degradation kinetics and transformation mechanisms are not well elucidated.Here we report a detailed examination of SO_(4)•−/Cl•-mediated degradation kinetics,products,and toxicities of sulfathiazole(ST),sarafloxacin(SAR),and lomefloxacin(LOM)in the two processes.Both SO_(4)•−/Cl•-mediated transformation kinetics were found to be dependent on pH(P<0.05),which was attributed to the disparate reactivities of their individual dissociated forms.Based on competition kinetic experiments and matrix calculations,the cationic forms(H_(2)ST^(+),H_(2)SAR^(+),and H_(2)LOM^(+))were more highly reactive towards SO_(4)•−in most cases,while the neutral forms(e.g.,HSAR^(0)and HLOM^(0))reacted the fastest with Cl•for the most of the antibiotics tested.Based on the identification of 31 key intermediates using tandem mass spectrometry,these reactions generated different products,of which the majority still retained the core chemical structure of the parent compounds.The corresponding diverse transformation pathways were proposed,involving S−N breaking,hydroxylation,defluorination,and chlorination reactions.Furthermore,the toxicity changes of their reaction solutions as well as the toxicity of each intermediate were evaluated by the vibrio fischeri and ECOSAR model,respectively.Many primary by-products were proven to be more toxic than the parent chemicals,raising the wider issue of extended potency for these compounds with regards to their ecotoxicity.These results have implications for assessing the degradative fate and risk of these chemicals during the AOPs.展开更多
BACKGROUND Left colon cancer surgery relies on laparoscopic hemicolectomy,with digestive tract reconstruction critical.End-to-side anastomosis(ESA)and side-to-side anastomosis(SSA)anastomoses are common,but their comp...BACKGROUND Left colon cancer surgery relies on laparoscopic hemicolectomy,with digestive tract reconstruction critical.End-to-side anastomosis(ESA)and side-to-side anastomosis(SSA)anastomoses are common,but their comparative outcomes,especially in splenic flexure handling and efficacy,need clarification.This study compares ESA and SSA to guide surgical practice.AIM To compare the clinical outcomes of laparoscopically assisted left hemicolectomy with ESA and SSA.METHODS A total of 334 patients were included,with 105 patients from the First Affiliated Hospital of Xiamen University and 229 patients from the First Affiliated Hospital of Fujian Medical University,between January 1,2012,and May 31,2020.The patients were divided into two groups:146 cases in the ESA group and 188 cases in the SSA group.Clinical data from both groups were compared,and the survival prognosis was followed up.RESULTS The operation time for the ESA group was significantly shorter than that of the SSA group(197.1±57.7 minutes vs 218.6±67.5 minutes,χ2=4.298,P=0.039).There were no significant differences between the two groups in intraoperative blood loss,postoperative pain score at 48 hours,time to first bowel movement,number of lymph nodes dissected,or postoperative complications such as anastomotic leakage,bleeding,stenosis.and adhesive intestinal obstruction at 6 months,12 months,and 24 months(P>0.05).Specifically,the incidence of complications like anastomotic leakage was 2.1%in the ESA group vs 4.3%in the SSA group(P=0.264).The 5-year disease-free survival(DFS)rate was 66.4%for the ESA group and 63.9%for the SSA group(P=0.693).There were no significant differences in the overall survival rate between the two groups.The incidence of splenic laceration was significantly higher in the SSA group(3.7%vs 0.7%,P=0.018).Overall,the 5-year DFS was 66.4%for ESA and 63.9%for SSA,with no significant difference in survival between the groups(P=0.693).CONCLUSION Both laparoscopically assisted left hemicolectomy with ESA and SSA are feasible and offer comparable long-term outcomes.ESA may reduce the need for splenic flexure dissociation,particularly when the tumor is located at the descending colon or its junction with the sigmoid colon,and especially in obese patients,elderly individuals with multiple complications,or those with severe adhesions in the splenic flexure of the surgical field.展开更多
Even if dissociation has various facets,it is clear that knowledge of dissociative psychosis and a dissociative schizophrenia-based viewpoint may provide new perspectives on mental disorders.Many researchers screening...Even if dissociation has various facets,it is clear that knowledge of dissociative psychosis and a dissociative schizophrenia-based viewpoint may provide new perspectives on mental disorders.Many researchers screening for comorbid symptoms of“childhood traumatic experiences”and“dissociation”,where specific characteristics are significant to the presence of psychosis and schizophrenia,may lead to an acceptable definition.In recent years,researchers have also reported crucial advances in the understanding of dissociative psychosis and dissociative schizophrenia.Although clinical studies in this area have been ongoing for a long time,research has not demonstrated that a clear and valid relationship exists between dissociation,childhood traumatic experiences,and schizophrenia or psychotic spectrum disorders.However,some results of statistical comparisons have supported the existence of the clinical manifestation known as dissociative psychosis and dissociative schizophrenia.Dissociation,childhood traumatic experiences,and positive psychotic symptoms may be a prominent part of dissociative psychosis and schizophrenia.The intense presence of negative symptoms may indicate classical schizophrenia.In research and clinical practice,researchers and clinicians may use psychometric tests to detect symptoms of dissociative psychosis.Psychotic persons with traumatic experiences likely benefit from treatment focused on trauma symptomatolgy.展开更多
Electrochemical reduction of nitrate(NO_(3^(-)))serves as an eco-friendly friendly alternative to the conventional Haber-Bosch ammonia(NH_(3))synthesis process.The Cu electrocatalyst is widely recognized for its stron...Electrochemical reduction of nitrate(NO_(3^(-)))serves as an eco-friendly friendly alternative to the conventional Haber-Bosch ammonia(NH_(3))synthesis process.The Cu electrocatalyst is widely recognized for its strong adsorption capacity towards nitrate,but its limited H adsorption and slow hydrogenation of oxynitride intermediates hinder the efficiency of converting NO_(3^(-))into NH_(3).Herein,a series of nanocomposite catalysts composed of CuO nanostructure with low NiO content that grow in-situ on carbon paper(Cu O/Ni O_(x)-CP)were synthesized via hydrothermal method and calcination for enhanced nitrate electroreduction utilizing the strong nitrate adsorption capacity of copper and excellent water dissociation ability of NiO to supply hydrogen free radicals(·H).In-situ Raman spectroscopy reveals dynamic reconstruction of Cu/NiO_(x)during the electrochemical nitrate reduction process from Cu O/NiO_(x).Due to the synergistic effect of Cu and NiO,a high Faradaic efficiency(FE,~97.9%)and yield rate(YR,391.5μmol h^(-1)cm^(-2))of ammonia are achieved on CuO/NiO_(2.3%)-CP.Electron paramagnetic resonance(EPR)proves that the presence of Ni O enhances the generation of·H,which can be rapidly consumed during nitrate reduction process.Density functional theory(DFT)calculations indicate that the activation energy of Ni O(0.57 eV)is much lower than Cu(0.84 e V)for water splitting to generate·H,thus facilitating*NO hydrogenations.This drives us to create more effective catalysts for nitrate reduction under neutral conditions by promoting H2O dissociation.展开更多
As a highly reactive reaction intermediate,surface gallium hydride(Ga–H)has garnered significant attention due to its critical role in various catalytic reactions.However,the detailed experimental characterization of...As a highly reactive reaction intermediate,surface gallium hydride(Ga–H)has garnered significant attention due to its critical role in various catalytic reactions.However,the detailed experimental characterization of this unique species remains challenging.Recently,we have demonstrated that solid-state NMR can be an effective tool for studying surface Ga–H.In this work,we report a comparative solid-state NMR study on H_(2) activation over different Ga_(2)O_(3) polymorphs,specificallyα-,β-andγ-Ga_(2)O_(3).^(1)H solid-state NMR enabled the identification of Ga–H species formed on all the three samples following high-temperature H_(2) treatment.The characteristic ^(1)H NMR signals of Ga–H species are resolved using J-coupling-based double-resonance NMR methods,revealing highly similar lineshapes of Ga–H for all the Ga_(2)O_(3) samples.This suggests potentially similar surface Ga–H configurations among different Ga_(2)O_(3) polymorphs.In addition,the local hydrogen environments on the oxide surfaces are further explored using two-dimensional(2D)^(1)H–^(1)H homonuclear correlation spectra,revealing multiple spatially proximate Ga–H and Ga–H/–OH pairs on different Ga_(2)O_(3) polymorphs.These findings provide insights into the potential mechanism of H_(2) dissociation.Overall,this work offers new perspectives on the local structure of surface Ga–H on Ga_(2)O_(3),and the analytical approach presented here can be further extended to the study of other Ga-based catalysts and other metal hydride species.展开更多
Extracting lithium from coal measures can alleviate the shortage of strategic metal resources.However,the lattice substitution characteristics of lithium in carrier minerals and its extremely fine intercalation and en...Extracting lithium from coal measures can alleviate the shortage of strategic metal resources.However,the lattice substitution characteristics of lithium in carrier minerals and its extremely fine intercalation and entrainment behavior are the challenges that constrain the extraction efficiency of lithium from coal series.This study focuses on improving the separation efficiency between lithium-contain-ing minerals and other minerals and the release behavior of lithium in the liquid phase.First,the feasibility of extracting lithium from car-rier minerals is confirmed based on the occurrence state and the process mineralogy characterized by Bgrimm process mineralogy analyz-ing system(BPMA)and time of flight secondary ion mass spectrometry(TOF-SIMS).The optimal selective grinding behavior is achieved within 15 min,allowing Li carrier minerals,including chlorite,kaolinite,and halloysite,to deliver the best dispersion effect with other minerals.Thus,the enriched lithium carrier minerals have been preenriched through screening.The leaching efficiency of Li has reached 97.43%under 1 mol/L hydrochloric acid,15 g/L pulp density,70℃,and 20 min.Leaching kinetics studies indicate that the de-crease in apparent energy validates the impact of grinding on metal leaching,aligning with the rate-controlling step of a chemical reaction.The process proposed in this study achieves the coordinated control of size and components in coal gangue and actualizes the effective se-lective enrichment of lithium through its low energy consumption and environmentally friendly nature.展开更多
Shear strength of hydrate-bearing sediment is an essential parameter for assessing landslide potential ofhydrate reservoirs under exploration conditions. However, the characteristics and simulation of thisshear streng...Shear strength of hydrate-bearing sediment is an essential parameter for assessing landslide potential ofhydrate reservoirs under exploration conditions. However, the characteristics and simulation of thisshear strength under varying dissociation conditions have not been thoroughly investigated. To this end,a series of triaxial compression tests were first carried out on sediments with varying initial hydratesaturations along dissociation pathways. Combining measured data with microscale analysis, the underlyingmechanism for the evolution of shear strength in hydrate-bearing sediment was studied undervarying partial dissociation pathways. Moreover, a shear strength model for hydrate-bearing sedimentwas proposed, taking into account the hydrate saturation and the unhydrated water content. Apart fromthe parameters derived from the hydrate characteristic curve, only one additional model parameter isrequired. The proposed model was validated using measured data on hydrate sediments. The resultsindicate that the proposed model can effectively capture the shear strength behavior of hydrate-bearingsediment under varying dissociation paths. Finally, a sensitivity analysis of the model parameters wasconducted to characterize the proposed model.展开更多
Metal oxide catalysts are widely employed in propane dehydrogenation(PDH)for propylene synthesis,requiring sequential reduction-reaction-regeneration cycles.However,the eff ect of water present in the inlet gas or rea...Metal oxide catalysts are widely employed in propane dehydrogenation(PDH)for propylene synthesis,requiring sequential reduction-reaction-regeneration cycles.However,the eff ect of water present in the inlet gas or reactor on the catalytic per-formance of various metal oxides remains insuffi ciently understood.This study examines the infl uence of water on supported metal oxide catalysts,specifi cally CoO x/Al_(2)O_(3),VO x/Al_(2)O_(3),and an industrial analog CrO x/Al_(2)O_(3) catalyst.By combining titration experiments,in situ Fourier transform infrared spectroscopy,kinetic analysis,and isotopic techniques,we demon-strate that even trace amounts of water can markedly suppress PDH performance via dissociative adsorption on the oxide surface.Methanol pretreatment eff ectively scavenges adsorbed water,recovering Lewis acid-base sites and consequently restoring PDH activity.This work underscores the profound inhibitory role of trace water in PDH over metal oxide catalysts and illustrates the potential of methanol pretreatment as an effective strategy to mitigate this limitation.展开更多
Deuterium(D),a stable and non-radioactive isotope of hydro-gen,is naturally present in the environment and is distinguishedfrom hydrogen by its greater mass.This mass difference resultsin a reduced stretching frequenc...Deuterium(D),a stable and non-radioactive isotope of hydro-gen,is naturally present in the environment and is distinguishedfrom hydrogen by its greater mass.This mass difference resultsin a reduced stretching frequency of the carbon-deuterium(C-D)bond,leading to lower ground state energy and higher bond dis-sociation energy compared to the carbon-hydrogen(C–H)bond.展开更多
文摘This paper discussed the setting up of a comeuter automatic system for testing the dy-namic dissociating tension of cooked cocoon filament by means of microcomputer tech-niques.The dynamic dissociating tension of two kinds of row cocoons with differentreelability was tested and analysed under different cocoon cooking conditions.More relia-ble data have been obtained by quantitative tests.The conclusions reached by analysingthese data are of practical significance to perfecting the cocoon cooking theory,assessingcocoon quality,improving the cocoon cooking process,etc.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11504112,91536218,and 11604100)
文摘We theoretically investigate the production of cold CN molecules by photodissociating ICN precursors in a brute-force field. The energy shifts and adiabatic orientation of the rotational ICN precursors are first investigated as a function of the external field strength. The dynamical photofragmentation of ICN precursors is numerically simulated for cases with and without orienting field. The CN products are compared in terms of their velocity distributions. A small portion of the CN fragments are recoiled to near zero speed in the lab frame by appropriately selecting the photo energy for dissociation. With a precursor ICN molecular beam of - 1.5 K in rotational temperature, the production of low speed CN fragments can be improved by more than 5 times when an orienting electrical field of 100 k V/cm is present. The corresponding production rate for decelerated fragments with speeds ≤ 50 m/s is simulated to be about ～2.1×10^-4 and CN number densities of 10^8 –10^10 cm^-3 can be reached with precursor ICN densities of ～10^12 –10^14 cm^-3 from supersonic expansion.
基金supported by the National Natural Science Foundation of China(Grant number 22172112)and the Fundamental Research Funds for the Central Universities.
文摘Electrocatalytic oxidation of glycerol for value-added chemicals is a superior strategy to utilize the excess glycerol produced in the biodiesel industry.Pd is one of the few active catalysts for alkaline glycerol oxidation reaction(GOR);however,glycerol inevitably dissociates and converts to carbon dioxide on the Pd surface,which results in its low total Faradaic efficiency(FE)for high-value-added products.Herein,a series of Pd/C and Pd10Bix/C catalysts were synthesized to investigate the GOR pathway.The Pd10Bi3/C catalyst with optimal Bi content achieved an excellent GOR mass activity of 7.5±0.2 A mgPd−1 and an outstanding total FE of 90%±3%,which are much higher than those values on Pd/C(1.2±0.2 A mgPd−1 for mass activity and 63%±4%for total FE).Combined results of in-situ attenuated total reflection surface enhanced infrared absorption spectroscopy and density functional theory calculations show that Bi suppresses the dissociation of glycerol through the“shielding effect”of Bi to the adjacent Pd sites,which weakens the adsorption strength of GOR intermediates on those sites.This work provides a new insight into the GOR mechanism and puts forward a valid strategy for the rational design of catalysts to enable the transformation of glycerol into high-value-added products.
基金the funding support from the National Natural Science Foundation of China(22373080)Fujian Pro-vincial Natural Science Foundation of China(2024J08008)+6 种基金the funding support from the National Natural Science Foundation of China(22402163)Fujian Provincial Science and Technology Program for International Cooperation(2025I0002)Natural Science Foundation of Xiamen,China(3502Z202472001)the funding support from the National Natural Science Foundation of China(22078274)the funding support from the Funda-mental Research Funds for the Central Universities(20720240054)Nan-Qiang Youth Scholar Program of Xiamen UniversityXiaomi Young Talents Program/Xiaomi Foundation。
文摘Electrocatalytic co-reduction of CO_(2)and nitrate offers an attractive and sustainable pathway for urea synthesis,as it enables the simultaneous valorization of nitrogenous waste and CO_(2)into value-added chemicals.However,achieving ambient and high-performance urea electrosynthesis remains a persistent challenge,as it requires the simultaneous activation of CO_(2)and efficient H_(2)O dissociation to supply active^(*)H for^(*)NO x hydrogenation—ultimately forming key Cand N-containing intermediates necessary for effective C-N coupling.The stringent,sequential nature of the reaction requirements continues to present substantial challenges for the rational design of advanced multifunctional catalysts.Herein,we report a creative two-in-one catalyst,bifunctional Pd-single-atom-modified Cu(Pd_(1)Cu)nanorods,to synergistically promote the adsorption and stepwise activation of dual species,that is,CO_(2)and H_(2)O,thereby effectively steering the reaction pathway toward the highly selective synthesis of urea.By integrating experimental evidence,in situ spectroscopy,and computational analyses,we clearly disclose that the atomically dispersed Pd sites kinetically favor the co-generation of^(*)CO and^(*)NH_(2)(via H_(2)O dissociation-driven proton transfer),thereby forming an optimal intermediate balance that facilitates urea synthesis.More importantly,the rationally designed Pd_(1)Cu leverages dual metal active sites to enhance C-N coupling via combined electronic and geometric effects,substantially lowering the reaction energy barrier and improving selectivity toward urea.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0620201)the frontier scientific research program of Deep Space Exploration Laboratory(Grant No.2022-QYKYJH-HXYF-019)the National Natural Science Foundation of China(Grant Nos.12388101,12027801,12402274,and U2430202)。
文摘Accurate temperature measurement is a crucial step in predicting and managing the aerodynamic heating during Mars entry and Earth reentry.These processes often occur at extremely high temperatures and pose challenges for quantitative measurements.A 1-μs time-resolved laser absorption technique was developed for simultaneous and time-dependent temperature and CO-concentration measurements over 3000-6000 K by adopting the P(0,21)and P(2,15)lines.To achieve quantitative measurement,the line strengths and Ar-broadening parameters were calibrated within 3030-5980 K.A“W”-shaped path-amplified strategy was used to increase the absorption features of the two lines during the calibration process.Validation experiments were conducted at 3040-5970 K to verify the accuracy of the technique.The new technique was then applied for simultaneous and time-resolved temperature and CO-concentration measurements during the CO_(2)dissociation process to further demonstrate the feasibility of the developed technique.The temperature-dependent CO_(2)absorption cross-sections at line centers of the two lines were calibrated within 2040-5870 K.The CO_(2)absorption interferences were quantified and subtracted from the measured laser absorbances.The measured results(referring to temperature and CO concentration)were generally consistent with the predictions from the kinetics mechanisms in the literature,highlighting the applicability of the developed technique for temperature measurements and CO_(2)dissociation studies within the investigated temperature range.
文摘CO_(2)utilization powered by sustainable energy offers a promising route to mitigate carbon emissions while producing value-added chemicals[1].Among these pathways,CO_(2)hydrogenation is especially attractive because it integrates renewable H 2 with carbon resources,which have achieved notable success in producing methanol,CO,etc.[2,3].
基金supported by the National Natural Science Foundation of China(Grant Nos.12534013,12047561,and 12104507)the Science and Technology Innovation Program of Hunan Province(Grant Nos.2025ZYJ001 and 2021RC4026)the National University of Defense Technology Research Fund Project.
文摘The accumulation and circulation of carbon and hydrogen contribute to the chemical evolution of ice giant planets.Species separation and diamond precipitation have been reported in carbon-hydrogen systems and have been verified by static and shock compression experiments.Nevertheless,the dynamic formation processes underlying these phenomena remain insufficiently understood.In combination with a deep learning model,we demonstrate that diamonds form through a three-step process involving dissociation,species separation,and nucleation processes.Under shock conditions of 125 GPa and 4590 K,hydrocarbons decompose to give hydrogen and low-molecular-weight alkanes(CH_(4) and C_(2)H_(6)),which escape from the carbon chains,resulting in C/H species separation.The remaining carbon atoms without C-H bonds accumulate and nucleate to form diamond crystals.The process of diamond growth is associated with a critical nucleus size at which the dynamic energy barrier plays a key role.These dynamic processes of diamond formation provide insight into the establishment of a model for the evolution of ice giant planets.
基金supported by National Science Fund for Distinguished Young Scholars(Grant No.52325206)National Key Research and Development Program of China(Grant No.2021YFF0500600)+3 种基金National Natural Science Foundation of China(Grant Nos.U2001220 and 52203298)Shenzhen Technical Plan Project(Grant Nos.RCJC20200714114436091,JCYJ20220530143012027,JCYJ20220818101003008,and JCYJ20220818101003007)Tsinghua Shenzhen International Graduate School-Shenzhen Pengrui Young Faculty Program of Shenzhen Pengrui Foundation(Grant No.SZPR2023006)Shenzhen Science and Technology Program(Grant No.WDZC20231126160733001).
文摘Composite solid electrolytes(CSEs)are considered among the most promising candidates for solid-state batteries.However,their practical application is hindered by low ionic conductivity and a limited lithium-ion transference number,primarily owing to the insufficient mobility of Li+.In this work,we design a heterojunc-tion nanoparticle composed of bimetallic zeolitic imidazolate frameworks(ZIFs)coupled with amorphous tita-nium oxide(TiO_(2)@Zn/Co–ZIF)as a filler to fabricate a composite solid-state electrolyte(PVZT).The amor-phous TiO_(2) coating facilitates salt dissociation through Lewis acid–base interactions with the anions of the lithium salt.Meanwhile,the Zn/Co–ZIF framework not only provides additional selective pathways for Li+transport but also effectively restricts anion migration through its confined pore size.The synergistic effect results in a high room-temperature ionic conductivity(8.8×10^(-4) S·cm^(-1))and a lithium-ion transference number of 0.47 for PVZT.A symmetrical cell using PVZT demonstrates stable Li+deposition/stripping for over 1100 h at a current density of 0.1 mA·cm^(-2).Additionally,a LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)/Li full cell using PVZT retains 75.0%of its capacity after 1200 cycles at a 2 C rate.This work offers valuable insights into the design of func-tional fillers for CSEs with highly efficient ion transport.
基金supported by the National Key R&D Program of China(2022YFA1604100)the National Natural Science Foundation of China(22302220,22372187,1972157,21972160,22402218)+2 种基金the National Science Fund for Distinguished Young Scholars of China(22225206)the Fundamental Research Program of Shanxi Province(202203021222403)the Youth Innovation Promotion Association CAS(2020179)。
文摘Carbon nanotube formation exemplifies atomically precise self-assembly,where atomic interactions dynamically engineer nanoscale architectures with emergent properties that transcend classical material boundaries.However,elucidating the transient molecular intermediates remains a critical mechanistic frontier.This study investigates the atomic-scale nucleation process of single-walled carbon nanotubes(SWCNTs)from acetylene on iron(Fe)clusters,utilizing GFN(-x)TB-based nanoreactor molecular dynamics simulations.The simulations reveal a consistent nucleation pathway,regardless of iron cluster size(Fe_(13),Fe_(38),Fe_(55)),where the chemisorption and dissociation of acetylene molecules on the Fe clusters lead to the formation of C_(2)H and C_(2)intermediates.These species then undergo oligomerization,initiating the growth of carbon chains.As the chains cross-link and cyclize,five-membered carbon rings are preferentially formed,which eventually evolve into six-membered rings and more complex sp2-hybridized carbon networks,resembling the cap structures of nascent SWCNTs.Although the nucleation mechanism remains similar across all cluster sizes,larger clusters show enhanced catalytic activity,leading to higher molecular weight hydrocarbons and more extensive carbocyclic networks due to their higher density of active sites per reacting molecule.Crucially,the study highlights the role of C_(2)H as the key active species in the carbon network formation process.These findings offer critical insights into the initial stages of SWCNT nucleation,contributing to a deeper understanding of the mechanisms driving SWCNT growth and guiding the development of optimized synthetic strategies.
基金Supported by NSFC (Nos.12171089,12271235)NSF of Jiangsu (No.BK20190919)NSF of Fujian (No.2021J02048)。
文摘For a simple graph G,let A(G)and D(G)be the adjacency matrix and the diagonal degree matrix of G,respectively.[Appl.Anal.Discrete Math.,2017,11(1):81-107]defined the matrix A_(α)(G)of G as A_(α)(G)=αD(G)(1-α)A(G),α∈[0,1].The Aa-spectral radius is the largest eigenvalue of A_(α)(G).Let G_(n,β) be the set graphs with order n and dissociation numberβ.In this paper,we identify the b with maximal A_(α)-spectral radius among all graphs in G_(n,β).
基金supported by the National Natural Science Foundation of China(No.22122308)Beijing National Laboratory for Molecular Sciences(BNLMS).Hong Gao is also partially supported by the Innovation Capability Support Program of Shaanxi Province(2023-CX-TD-49)supported by the China Postdoctoral Science Foundation(No.2020TQ0324).
文摘The dicarbon(C_(2))molecule is an important molecular species observed in many carbon-containing gaseous environments.The spectroscopic and dissociative studies of C_(2)have attracted great attention for a long time for understanding its electronic characters as well as the evolution and cycling of carbon in the universe.In this study,the lifetimes of C_(2)populated at the three high-lying electronic states of(2-4)^(3)Δ_(g) in the vacuum ultraviolet(VUV)region have been experimentally measured using a time-of-flight mass spectrometer and the VUV-pump-UV-probe photoionization scheme.The measurements showed that all the rovibronic levels in the 2(g)^(3)Δ_(g) state exhibit shorter lifetimes than the dynamical limit of the experimental method,consistent with the theoretically predicted radiative lifetimes.Dependence of the lifetime on the vibrational level was observed in the 3^(3)Δ_(g) state,and a marginal rotational dependence was noticed in the vʹ=1 vibrational level.For the 4^(3)Δ_(g) state,the rotationally resolved lifetimes in the vʹ=1 vibrational level were found to be slightly longer than those in the vʹ=0 and 2 vibrational levels.Such a complicated dependence of the lifetime on the rovibronic level makes further experimental and theoretical investigations highly desired for understanding the dynamics in the high-lying excited states of C_(2).
基金supported by the Key Research and Development Program of Shaanxi Province(No.2024SF-YBXM-567)the National Natural Science Foundation of China(Nos.21976045,22076112)the China Scholarship Council(CSC)Scholarship(No.202308610123).
文摘As antibiotic pollutants cannot be incompletely removed by conventional wastewater treatment plants,ultraviolet(UV)based advanced oxidation processes(AOPs)such as UV/persulfate(UV/PS)and UV/chlorine are increasingly concerned for the effective removal of antibiotics from wastewaters.However,the specific mechanisms involving degradation kinetics and transformation mechanisms are not well elucidated.Here we report a detailed examination of SO_(4)•−/Cl•-mediated degradation kinetics,products,and toxicities of sulfathiazole(ST),sarafloxacin(SAR),and lomefloxacin(LOM)in the two processes.Both SO_(4)•−/Cl•-mediated transformation kinetics were found to be dependent on pH(P<0.05),which was attributed to the disparate reactivities of their individual dissociated forms.Based on competition kinetic experiments and matrix calculations,the cationic forms(H_(2)ST^(+),H_(2)SAR^(+),and H_(2)LOM^(+))were more highly reactive towards SO_(4)•−in most cases,while the neutral forms(e.g.,HSAR^(0)and HLOM^(0))reacted the fastest with Cl•for the most of the antibiotics tested.Based on the identification of 31 key intermediates using tandem mass spectrometry,these reactions generated different products,of which the majority still retained the core chemical structure of the parent compounds.The corresponding diverse transformation pathways were proposed,involving S−N breaking,hydroxylation,defluorination,and chlorination reactions.Furthermore,the toxicity changes of their reaction solutions as well as the toxicity of each intermediate were evaluated by the vibrio fischeri and ECOSAR model,respectively.Many primary by-products were proven to be more toxic than the parent chemicals,raising the wider issue of extended potency for these compounds with regards to their ecotoxicity.These results have implications for assessing the degradative fate and risk of these chemicals during the AOPs.
文摘BACKGROUND Left colon cancer surgery relies on laparoscopic hemicolectomy,with digestive tract reconstruction critical.End-to-side anastomosis(ESA)and side-to-side anastomosis(SSA)anastomoses are common,but their comparative outcomes,especially in splenic flexure handling and efficacy,need clarification.This study compares ESA and SSA to guide surgical practice.AIM To compare the clinical outcomes of laparoscopically assisted left hemicolectomy with ESA and SSA.METHODS A total of 334 patients were included,with 105 patients from the First Affiliated Hospital of Xiamen University and 229 patients from the First Affiliated Hospital of Fujian Medical University,between January 1,2012,and May 31,2020.The patients were divided into two groups:146 cases in the ESA group and 188 cases in the SSA group.Clinical data from both groups were compared,and the survival prognosis was followed up.RESULTS The operation time for the ESA group was significantly shorter than that of the SSA group(197.1±57.7 minutes vs 218.6±67.5 minutes,χ2=4.298,P=0.039).There were no significant differences between the two groups in intraoperative blood loss,postoperative pain score at 48 hours,time to first bowel movement,number of lymph nodes dissected,or postoperative complications such as anastomotic leakage,bleeding,stenosis.and adhesive intestinal obstruction at 6 months,12 months,and 24 months(P>0.05).Specifically,the incidence of complications like anastomotic leakage was 2.1%in the ESA group vs 4.3%in the SSA group(P=0.264).The 5-year disease-free survival(DFS)rate was 66.4%for the ESA group and 63.9%for the SSA group(P=0.693).There were no significant differences in the overall survival rate between the two groups.The incidence of splenic laceration was significantly higher in the SSA group(3.7%vs 0.7%,P=0.018).Overall,the 5-year DFS was 66.4%for ESA and 63.9%for SSA,with no significant difference in survival between the groups(P=0.693).CONCLUSION Both laparoscopically assisted left hemicolectomy with ESA and SSA are feasible and offer comparable long-term outcomes.ESA may reduce the need for splenic flexure dissociation,particularly when the tumor is located at the descending colon or its junction with the sigmoid colon,and especially in obese patients,elderly individuals with multiple complications,or those with severe adhesions in the splenic flexure of the surgical field.
文摘Even if dissociation has various facets,it is clear that knowledge of dissociative psychosis and a dissociative schizophrenia-based viewpoint may provide new perspectives on mental disorders.Many researchers screening for comorbid symptoms of“childhood traumatic experiences”and“dissociation”,where specific characteristics are significant to the presence of psychosis and schizophrenia,may lead to an acceptable definition.In recent years,researchers have also reported crucial advances in the understanding of dissociative psychosis and dissociative schizophrenia.Although clinical studies in this area have been ongoing for a long time,research has not demonstrated that a clear and valid relationship exists between dissociation,childhood traumatic experiences,and schizophrenia or psychotic spectrum disorders.However,some results of statistical comparisons have supported the existence of the clinical manifestation known as dissociative psychosis and dissociative schizophrenia.Dissociation,childhood traumatic experiences,and positive psychotic symptoms may be a prominent part of dissociative psychosis and schizophrenia.The intense presence of negative symptoms may indicate classical schizophrenia.In research and clinical practice,researchers and clinicians may use psychometric tests to detect symptoms of dissociative psychosis.Psychotic persons with traumatic experiences likely benefit from treatment focused on trauma symptomatolgy.
基金supported by the National Natural Science Foundation of China(No.U22A20253)。
文摘Electrochemical reduction of nitrate(NO_(3^(-)))serves as an eco-friendly friendly alternative to the conventional Haber-Bosch ammonia(NH_(3))synthesis process.The Cu electrocatalyst is widely recognized for its strong adsorption capacity towards nitrate,but its limited H adsorption and slow hydrogenation of oxynitride intermediates hinder the efficiency of converting NO_(3^(-))into NH_(3).Herein,a series of nanocomposite catalysts composed of CuO nanostructure with low NiO content that grow in-situ on carbon paper(Cu O/Ni O_(x)-CP)were synthesized via hydrothermal method and calcination for enhanced nitrate electroreduction utilizing the strong nitrate adsorption capacity of copper and excellent water dissociation ability of NiO to supply hydrogen free radicals(·H).In-situ Raman spectroscopy reveals dynamic reconstruction of Cu/NiO_(x)during the electrochemical nitrate reduction process from Cu O/NiO_(x).Due to the synergistic effect of Cu and NiO,a high Faradaic efficiency(FE,~97.9%)and yield rate(YR,391.5μmol h^(-1)cm^(-2))of ammonia are achieved on CuO/NiO_(2.3%)-CP.Electron paramagnetic resonance(EPR)proves that the presence of Ni O enhances the generation of·H,which can be rapidly consumed during nitrate reduction process.Density functional theory(DFT)calculations indicate that the activation energy of Ni O(0.57 eV)is much lower than Cu(0.84 e V)for water splitting to generate·H,thus facilitating*NO hydrogenations.This drives us to create more effective catalysts for nitrate reduction under neutral conditions by promoting H2O dissociation.
基金financially supported by the National Key R&D Program of China(No.2021YFA1502803)the National Natural Science Foundation of China(Nos.22325405,22372160,22432005 and 22321002)Dalian Science and Technology Talent Innovation Program(No.2024RG009).
文摘As a highly reactive reaction intermediate,surface gallium hydride(Ga–H)has garnered significant attention due to its critical role in various catalytic reactions.However,the detailed experimental characterization of this unique species remains challenging.Recently,we have demonstrated that solid-state NMR can be an effective tool for studying surface Ga–H.In this work,we report a comparative solid-state NMR study on H_(2) activation over different Ga_(2)O_(3) polymorphs,specificallyα-,β-andγ-Ga_(2)O_(3).^(1)H solid-state NMR enabled the identification of Ga–H species formed on all the three samples following high-temperature H_(2) treatment.The characteristic ^(1)H NMR signals of Ga–H species are resolved using J-coupling-based double-resonance NMR methods,revealing highly similar lineshapes of Ga–H for all the Ga_(2)O_(3) samples.This suggests potentially similar surface Ga–H configurations among different Ga_(2)O_(3) polymorphs.In addition,the local hydrogen environments on the oxide surfaces are further explored using two-dimensional(2D)^(1)H–^(1)H homonuclear correlation spectra,revealing multiple spatially proximate Ga–H and Ga–H/–OH pairs on different Ga_(2)O_(3) polymorphs.These findings provide insights into the potential mechanism of H_(2) dissociation.Overall,this work offers new perspectives on the local structure of surface Ga–H on Ga_(2)O_(3),and the analytical approach presented here can be further extended to the study of other Ga-based catalysts and other metal hydride species.
基金supported by the National Key R&D Program of China(No.2023YFC2907701)This work was also supported by the Fundamental Research Program of Shanxi Province,China(No.202103021223045)+4 种基金the Shanxi Scholarship Council of China(No.2022-062)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi,China(No.2021L064)This study was also funded by Open Foundation of State Key Laboratory of Mineral Processing(No.BGRIMM-KJSKL-2025-26)This work was supported by the National Natural Science Foundation of China(No.52104260)This work was supported by Young Elite Scientists Sponsorship Program by CAST(No.2022QNRC001).
文摘Extracting lithium from coal measures can alleviate the shortage of strategic metal resources.However,the lattice substitution characteristics of lithium in carrier minerals and its extremely fine intercalation and entrainment behavior are the challenges that constrain the extraction efficiency of lithium from coal series.This study focuses on improving the separation efficiency between lithium-contain-ing minerals and other minerals and the release behavior of lithium in the liquid phase.First,the feasibility of extracting lithium from car-rier minerals is confirmed based on the occurrence state and the process mineralogy characterized by Bgrimm process mineralogy analyz-ing system(BPMA)and time of flight secondary ion mass spectrometry(TOF-SIMS).The optimal selective grinding behavior is achieved within 15 min,allowing Li carrier minerals,including chlorite,kaolinite,and halloysite,to deliver the best dispersion effect with other minerals.Thus,the enriched lithium carrier minerals have been preenriched through screening.The leaching efficiency of Li has reached 97.43%under 1 mol/L hydrochloric acid,15 g/L pulp density,70℃,and 20 min.Leaching kinetics studies indicate that the de-crease in apparent energy validates the impact of grinding on metal leaching,aligning with the rate-controlling step of a chemical reaction.The process proposed in this study achieves the coordinated control of size and components in coal gangue and actualizes the effective se-lective enrichment of lithium through its low energy consumption and environmentally friendly nature.
基金supported by the National Natural Science Foundation of China(Grant No.51939011)the Science and Technology Program of CNOOC Research Institute(Grant No.2023OTKK03)supported by the program of the Youth Innovation Promotion Association,Chinese Academy of Sciences(Grant No.2020326).
文摘Shear strength of hydrate-bearing sediment is an essential parameter for assessing landslide potential ofhydrate reservoirs under exploration conditions. However, the characteristics and simulation of thisshear strength under varying dissociation conditions have not been thoroughly investigated. To this end,a series of triaxial compression tests were first carried out on sediments with varying initial hydratesaturations along dissociation pathways. Combining measured data with microscale analysis, the underlyingmechanism for the evolution of shear strength in hydrate-bearing sediment was studied undervarying partial dissociation pathways. Moreover, a shear strength model for hydrate-bearing sedimentwas proposed, taking into account the hydrate saturation and the unhydrated water content. Apart fromthe parameters derived from the hydrate characteristic curve, only one additional model parameter isrequired. The proposed model was validated using measured data on hydrate sediments. The resultsindicate that the proposed model can effectively capture the shear strength behavior of hydrate-bearingsediment under varying dissociation paths. Finally, a sensitivity analysis of the model parameters wasconducted to characterize the proposed model.
基金supported by the National Key R&D Program of China(No.2023YFA1507800)the National Science Foundation of China(Nos.22121004,22122808,22478279,and 22108201)+1 种基金the Haihe Laboratory of Sustainable Chemical Trans-formations,the Program of Introducing Talents of Discipline to Uni-versities(No.BP0618007)the XPLORER PRIZE.
文摘Metal oxide catalysts are widely employed in propane dehydrogenation(PDH)for propylene synthesis,requiring sequential reduction-reaction-regeneration cycles.However,the eff ect of water present in the inlet gas or reactor on the catalytic per-formance of various metal oxides remains insuffi ciently understood.This study examines the infl uence of water on supported metal oxide catalysts,specifi cally CoO x/Al_(2)O_(3),VO x/Al_(2)O_(3),and an industrial analog CrO x/Al_(2)O_(3) catalyst.By combining titration experiments,in situ Fourier transform infrared spectroscopy,kinetic analysis,and isotopic techniques,we demon-strate that even trace amounts of water can markedly suppress PDH performance via dissociative adsorption on the oxide surface.Methanol pretreatment eff ectively scavenges adsorbed water,recovering Lewis acid-base sites and consequently restoring PDH activity.This work underscores the profound inhibitory role of trace water in PDH over metal oxide catalysts and illustrates the potential of methanol pretreatment as an effective strategy to mitigate this limitation.
基金Financial support from Science and Technology Innovation Program of Hunan Province(No.2022RC4044)。
文摘Deuterium(D),a stable and non-radioactive isotope of hydro-gen,is naturally present in the environment and is distinguishedfrom hydrogen by its greater mass.This mass difference resultsin a reduced stretching frequency of the carbon-deuterium(C-D)bond,leading to lower ground state energy and higher bond dis-sociation energy compared to the carbon-hydrogen(C–H)bond.
