Seismic monitoring of sub-seafloor fluid processes in the Haima cold seep area using an Ocean Bottom Seismometer (OBS)

The use of ocean bottom seismometers provides an effective means of studying the process and the dynamic of cold seeps by continuously recording micro-events produced by sub-seafloor fluid migration.We deployed a four-component Ocean Bottom Seismometer(OBS)at an active site of the Haima cold seep from 6 November to 19 November in 2021.Here,we present the results of this short-term OBS monitoring.We first examine the OBS record manually to distinguish(by their distinctive seismographic signatures)four types of events:shipping noises,vibrations from our remotely operated vehicle(ROV)operations,local earthquakes,and short duration events(SDEs).Only the SDEs are further discussed in this work.Such SDEs are similar to those observed in other sea areas and are interpreted to be correlated with sub-seafloor fluid migration.In the OBS data collected during the 14-day monitoring period.We identify five SDEs.Compared to the SDE occurrence rate observed in other cold seep regions,five events is rather low,from which it could be inferred that fluid migration,and subsequent gas seepage,is not very active at the Haima site.This conclusion agrees with multi-beam and chemical observations at that site.Our observations thus provide further constraint on the seepage activity in this location.This is the first time that cold seep-related SDEs have been identified in the South China Sea,expanding the list of sea areas where SDEs are now linked to cold seep fluid migration.

The Exact Inference of Beta Process and Beta Bernoulli Process From Finite Observations

Beta Process is a typical nonparametric Bayesian model.and the Beta Bernoulli Process provides a Bayesian nonparametric prior for models involving collections of binary valued features.Some previous studies considered the Beta Process inference problem by giving the Stick-Breaking sampling method.This paper focuses on analyzing the form of precise probability distribution based on a Stick-Breaking approach,that is,the joint probability distribution is derived from any finite number of observable samples:It not only determines the probability distribution function of the Beta Process with finite observation(represented as a group of number between[0,1]),but also gives the distribution function of the Beta Bernoulli Process with the same finite dimension(represented as a matrix with element value of 0 or,1)by using this distribution as a prior.

Numerical simulation of the dynamic migration mechanism and prediction of saturation of tight sandstone oil

Quantitative characterization of tight sandstone oil migration and accumulation is an emerging research frontier in the field of oil and gas exploration.In this study,a conceptual model containing multiple basic geological elements is developed,and a nonlinear seepage numerical model for tight sandstone oil migration and accumulation is established.The effects of the slip effect,overpressure driving force,buoyancy,and capillary force on the migration and accumulation of tight oil are examined.The results showed that(1)the differences in oil migration and accumulation between tight and conventional reservoirs are reflected in the growth mode of oil saturation,distribution characteristics of oil and water,and extent of the effect of the formation dip angle;(2)the slip effect has a significant impact when the average pore throat radius is less than 150 nm and the overpressure driving force and capillary force are the main mechanical mechanisms controlling oil migration and accumulation in tight sandstone,while the coupling effect of buoyancy,capillary force,and overpressure driving force controls the upper and lower limits of oil saturation.Finally,a dimensional and dimensionless identification chart for rapidly predicting the oil saturation of tight sandstone is proposed and verified using the measured data.This study provides a basis for analyzing the migration and accumulation mechanisms of tight sandstone oil and a new approach for predicting oil saturation.Additionally,we developed digital and visual analysis methods for the migration results,enriching the expression of the dynamics of hydrocarbon accumulation.

Highly Efficient and Selective Photocatalytic Nonoxidative Coupling of Methane to Ethylene over Pd-Zn Synergistic Catalytic Sites

Photocatalytic nonoxidative coupling of CH_(4)to multicarbon(C^(2+))hydrocarbons(e.g.,C,H4)and H,under ambient conditions provides a promising energy-conserving approach for utilization of carbon resource.However,as the methyl intermediates prefer to undergo self-coupling to produce ethane,it is a challenging task to control the selective conversion of CH to higher valueadded CH4.Herein,we adopt a synergistic catalysis strategy by integrating Pd-Zn active sites on visible light-responsive defective WO_(3)nanosheets for synergizing the adsorption,activation,and dehydrogenation processes in CH_(4)to C_(2)H_(4)conversion.Benefiting from the synergy,our model catalyst achieves a remarkable C^(2+)compounds yield of 31.85μmolgh with an exceptionally high C,H4 selectivity of 75.3%and a stoichiometric H_(2)evolution.In situ spectroscopic studies reveal that the Zn sites promote the adsorption and activation of CH_(4)molecules to generate methyl and methoxy intermediates with the assistance of lattice oxygen,while the Pd sites facilitate the dehydrogenation of methoxy to methylene radicals for producing C_(2)H_(4)and suppress overoxidation.This work demonstrates a strategy for designing efficient photocatalysts toward selective coupling of CH_(4)to higher value-added chemicals and highlights the importance of synergistic active sites to the synergy of key steps in catalytic reactions.

Enhancing (de)hydrogenation kinetics properties of the Mg/MgH_(2) system by adding ANi_(5)(A=Ce,Nd,Pr,Sm,and Y) alloys via ball milling

Magnesium(Mg)-based alloys have already been widely studied as the hydrogen storage materials because of their high reversible hydrogen storage capacity,low cost,light weight,etc.However,the poor de/hydrogenation kinetic properties dramatically hinder the practical applications.In this work,the MgH_(2)-ANi_(5)(A=Ce,Nd,Pr,Sm,and Y) composites were prepared by a high-energy ball milling method.which can effectively refine the particle size thus improving the kinetic properties.Experimental results reveal that the MgH_(2)-ANi_(5) composites mainly consist of Mg_(2)NiH_(4),MgH_(2) and rare earth(RE) hydride,which will be dehydrogenated to form Mg_(2)Ni,Mg and stable RE hydride reversibly.Accordingly,the asmilled MgH_(2)-ANi_(5)(A=Ce,Nd,Pr,Sm,and Y) composites with various A-elements can respectively contribute to a reversible hydrogen storage capacity of 6.16 wt%,5.7 wt%,6.21 wt%,6.38 wt%,and 6.5 wt%at a temperature of 300℃,and show much better kinetic properties in comparison to the pure MgH_(2) without any additive.In-situ formed Mg_(2) Ni and stable RE hydride(such as CeH_(2.73) and YH_(2)) might act as effective catalysts to significantly improve the hydrogen storage properties of MgH_(2).The present work provides a guideline on improving the kinetic properties of the Mg-based hydrogen storage alloys.

Profiles of and variations in aluminum species in PAC-MC used for the removal of blooming microalgae

Polyaluminum chloride modified clay(PAC-MC)is a safe and efficient red tide control agent that has been studied and applied worldwide.Although it is well known that the distribution of hydrolytic aluminum species in PAC affects its flocculation,little is known about the influence of particulars aluminum species on the microalgae removal efficiency of PAC-MC;this lack of knowledge creates a bottleneck in the development of more efficient MCs based on aluminum salts.The ferron method was used in this study to quantitatively analyze the distributions of and variations in different hydrolytic aluminum species during the process of microalgae removal by PAC-MC.The results showed that Ala,which made up 5%–20%of the total aluminum,and Alp,which made up 15%–55%of the total aluminum,significantly affected microalgae removal,with Pearson’s correlation coefficients of 0.83 and 0.89,respectively.Most of the aluminum in the PAC-MC sank rapidly into the sediments,but the rate and velocity of settlement were affected by the dose of modified clay.The optimal dose of PAC-MC for precipitating microalgae was determined based on its aluminum profile.These results provide guidance for the precise application of PAC-MC in the control of harmful algal blooms.

Integrating bimetallic AuPd nanocatalysts with a 2D aza-fused π-conjugated microporous polymer for light-driven benzyl alcohol oxidation

Efficient catalytic system with low energy consumption exhibits increasing importance due to the upcoming energy crisis.Given this situation,it should be an admirable strategy for reducing energy input by effectively utilizing incident solar energy as a heat source during catalytic reactions.Herein,aza-fused7 r-conjugated microporous polymer(aza-CMP)with broad light absorption and high photothermal conversion efficiency was synthesized and utilized as a support for bimetallic AuPd nanocatalysts in light-driven benzyl alcohol oxidation.The AuPd nanoparticles anchored on aza-CMP(aza-CM P/Au_xPdy)exhibited excellent catalytic performance for benzyl alcohol oxidation under 50 mW/cm^2 light irradiation.The improved catalytic performance by the aza-CMP/Au_xPdy is attributed to the unique photothermal effect induced by aza-CMP,which can promote the catalytic benzyl alcohol oxidation occurring at Au Pd.This work presents a novel approach to effectively utilize solar energy for conventional catalytic reactions through photothermal effect.

Identification and Design of Active Sites on Photocatalysts for the Direct Artificial Carbon Cycle

CONSPECTUS:Imitating the natural carbon cycle,the utilization of the carbon-based greenhouse gases(i.e.,carbon dioxide(CO_(2))and methane(CH_(4)))from the atmosphere as the carbon feedstocks for valuable fuel and chemical production represents a prospective strategy for achieving the sustainable development of human society.In light of this,photocatalytic CO_(2)/CH_(4)conversions,which can directly harvest solar energy for the production of valuable fuels and chemicals,show gigantic potential for closing the loop of the artificial carbon cycle.In the past several decades,immense progress has been made in this field,showing its practical feasibility.However,the photocatalytic conversion efficiency and selectivity of such reactions remain discouraging.Considering that the photocatalytic reaction is intimately related to the surface catalytic reaction on the active sites of the photocatalysts,the active site design has been proven to be effective for optimizing photocatalytic performance,yet the lack of effective techniques for the identification of the active sites,which is normally at the molecular level,greatly limits its potential in photocatalysis.Fortunately,with the rapid expansion in the field of materials science,a large number of advanced characterization techniques have been developed,equipping the materials scientist and chemist with powerful tools for unveiling the mask of the active sites on the photocatalysts.Concomitantly,the active site design for the photocatalysts has undergone a revival.Today,the identification and design of active sites have emerged as hot topics in catalysis and are expected to push forward development in the field of the artificial carbon cycle.

Intraoperative neurophysiological monitoring in selective dorsal rhizotomy (SDR)

For decades,intraoperative neurophysiological monitoring(IONM)has been used to guide selective dorsal rhizotomy(SDR)for the treatment of spastic cerebral palsy(CP).Electromyography(EMG)interpretation methods,which are the core of IONM,have never been fully discussed and addressed,and their importance and necessity in SDR have been questioned for years.However,outcomes of CP patients who have undergone IONM-guided SDR have been favorable,and surgery-related complications are extremely minimal.In this paper,we review the history of evolving EMG interpretation methods as well as their neuroelectrophysiological basis.