Enhancing the resolution of sparse rock property measurements using machine learning and random field theory

The travel time of rock compressional waves is an essential parameter used for estimating important rock properties,such as porosity,permeability,and lithology.Current methods,like wireline logging tests,provide broad measurements but lack finer resolution.Laboratory-based rock core measurements offer higher resolution but are resource-intensive.Conventionally,wireline logging and rock core measurements have been used independently.This study introduces a novel approach that integrates both data sources.The method leverages the detailed features from limited core data to enhance the resolution of wireline logging data.By combining machine learning with random field theory,the method allows for probabilistic predictions in regions with sparse data sampling.In this framework,12 parameters from wireline tests are used to predict trends in rock core data.The residuals are modeled using random field theory.The outcomes are high-resolution predictions that combine both the predicted trend and the probabilistic realizations of the residual.By utilizing unconditional and conditional random field theories,this method enables unconditional and conditional simulations of the underlying high-resolution rock compressional wave travel time profile and provides uncertainty estimates.This integrated approach optimizes the use of existing core and logging data.Its applicability is confirmed in an oil project in West China.

One dimensional nickel phosphide polymorphic heterostructure as carbon-free functional support loading single-atom iridium for promoted electrocatalytic water oxidation

Although conducting materials such as carbon nanotube and carbon fiber paper(CFP)have been extensively employed as support of electrocatalytic active sites,most of them are of poor catalytic functionality by themselves and undesirable stability during strong acid/alkaline environments or oxidation process.Here we report a novel one-dimensional(1D)nickel phosphide polymorphic heterostructure(denoted as NPPH)to work as one effective carbon-free functional support for loading of single-atom Ir water oxidation electrocatalyst.Specifically,the NPPH composed of both Ni12P5and Ni2P phases is not only active for robust alkaline water oxidation but also is of good stability and hydrophilicity for favorable loading of single-atom dispersed iridium.The NPPH supported single-atom Ir electrocatalyst(Ir/NPPH)is found to exhibit remarkably superior water oxidation activity with respect to the NPPH itself or CFP supported single-atom Ir catalyst(Ir/CFP),demonstrating the synergetic promotion effect between NPPH and single-atom Ir catalyst.Furthermore,the NPPH supported single-atom Ir catalyst can bear alkaline water oxidation for over 120 h at current density of 50 mA cm^(-2).The NPPH developed here is expected as functional support to composite with other water oxidation catalysts,as may be an alternative strategy of developing highly efficient carbon-free electrocatalysts.

Heterostructured MOFs photocatalysts for water splitting to produce hydrogen

Metal-organic frameworks(MOFs) with high designability and structure diversity have been widely developed as promising photocatalytic materials,but most of them suffer from poor charge transportation and separation efficiency.To address it,the construction of MOFs-based heterostructures has been thus highly inspired.In this minireview,we will first introduce the basic principles of photocata lytic water splitting and heterostructure systems,and then discuss state-of-the-art MOFs-based heterostructures for photocata lytic water splitting to produce hydrogen.Meanwhile,special attention will be paid to the key factors affecting the interfacial charge transfer of heterostructures,such as interface connection mode,morphology control,and modification.Eventually,the challenges and prospects faced by the construction of high-efficiency MOFs-based heterostructure water slitting photocatalysts are proposed.

Unexpectedly selective hydrogenation of phenylacetylene to styrene on titania supported platinum photocatalyst under 385 nm monochromatic light irradiation

Conversion of alkynes to alkenes by photocatalysis has inspired extensive interest but it is still challenging to obtain both high conversion and selectivity.Here we first demonstrate the photocatalytic conversion of phenylacetylene(PLE)to styrene(STE)with both high conversion and selectivity by using the titania(TiO2)supported platinum(Pt)as photocatalyst under 385 nm monochromatic light irradiation.It is demonstrated that the conversion rate of PLE is strongly dependent on the content of Pt cocatalyst loaded on the surface of TiO2.Based on our optimization,the conversion of PLE and the selectivity towards STE on the 1 wt%Pt/TiO2 photocatalyst can unexpectedly reach as high as 92.4%and 91.3%,respectively.The highly selective photocatalytic hydrogenation can well be extended to the conversion of other typical alkynes to alkenes,demonstrating the generality of selective hydrogenation of C≡C over the Pt/TiO2 photocatalyst.

Timing of mineralization at the Shihu gold deposit in the middle segment of the Taihang Mountain, China

The Shihu gold deposit, located in the middlesouth section of the core of the Fuping mantle branch structure, is hosted in the Archean Fuping Group and adjacent to the quartz diorite porphyrite. The gold deposit is the only large gold deposit with reserves of more than 30 tons gold discovered in western Hebei Province so far. In order to constrain the timing of mineralization of this ore deposit, this paper focuses on the isotopic dating of zircon and pyrite. Zircons in gold-bearing quartz veins are magmatic in origin and no hydrothermal zircon has been found in such quartz veins, indicating that zircons were derived from the wall rocks. U–Pb ages of zircons fall mainly in the two domains: 2492 ± 82 and 136 ± 4 Ma, respectively,indicative of the contribution of the Fuping-Group TTG gneiss and Yanshanian igneous rocks, respectively. The Re–Os isotopic compositions of pyrites in the gold-bearing quartz veins yield an isochron age of 127 ± 31 Ma. Combined with other dating results, we suggest that the main metallogenic age of the Shihu gold deposit is 120–127 Ma.

Metal-seed assistant photodeposition of platinum over Ta_(3)N_(5) photocatalyst for promoted solar hydrogen production under visible light

Cocatalysts play a vital role in accelerating the reaction kinetics and improving the charge separation of photocatalysts for solar hydrogen production.The promotion of the photocatalytic activity largely relies on the loading approach of the cocatalysts.Herein,we introduce a metal-seed assistant photodeposition approach to load the hydrogen evolution cocatalyst of platinum onto the surface of Ta_(3)N_(5) photocatalyst,which exhibits about 3.6 times of higher photocatalytic proton reduction activity with respect to the corresponding impregnation or photodeposition loading.Based on our characterizations,the increscent contact area of the cocatalyst/semiconductor interface with metal-seed assistant photodeposition method is proposed to be responsible for the promoted charge separation as well as enhanced photocatalytic H2 evolution activity.It is interesting to note that this innovative deposition strategy can be easily extended to loading of platinum cocatalyst with other noble or non-noble metal seeds for promoted activities,demonstrating its good generality.Our work may provide an alternative way of depositing cocatalyst for better photocatalytic performances.

Visible Light-Responsive N-Doped TiO_(2) Photocatalysis:Synthesis,Characterizations,and Applications

Photocatalysis based on semiconductors has recently been receiving considerable research interest because of its extensive applications in environmental remediation and renewable energy generation.Various semiconductor-based materials that are vital to solar energy utilization have been extensively investigated,among which titanium oxide(TiO_(2))has attracted considerable attention because of its exceptional physicochemical characteristics.However,the sluggish responsiveness to visible light in the solar spectrum and the inefficient separation of photoinduced electron-hole pairs hamper the practical application of TiO_(2) materials.To overcome the aforementioned serious drawbacks of TiO_(2),numerous strategies,such as doping with foreign atoms,particularly nitrogen(N),have been improved in the past few decades.This review aims to provide a comprehensive update and description of the recent developments of N-doped TiO_(2) materials for visible lightresponsive photocatalysis,such as(1)the preparation of N-doped/co-doped TiO_(2) photocatalysts and(2)mechanistic studies on the reasons for visible light response.Furthermore,the most recent and significant advances in the field of solar energy applications of modified N-doped TiO_(2) are summarized.The analysis indicated the critical need for further development of these types of materials for the solar-to-energy conversion,particularly for water splitting purposes.

A hydrated amorphous iron oxide nanoparticle as active water oxidation catalyst

Developing efficient water oxidation catalysts(WOCs)with earth‐abundant elements still remains a challenging task for artificial photosynthesis.Iron‐based WOC is a promising candidate because it is economically cheap,little toxic and environmentally friendly.In this study,we found that the catalytic water oxidation activity on amorphous iron‐based oxide/hydroxide(FeOx)can be decreased by an order of magnitude after the dehydration process at room temperature.Thermogravimetric analysis,XRD and Raman results indicated that the dehydration process of FeOx at room temperature causes the almost completely loss of water molecule with no bulk structural changes.Based on this finding,we prepared hydrated ultrasmall(ca.2.2 nm)FeOx nanoparticles of amorphous feature,which turns out to be extremely active as WOC with turnover frequency(TOF)up to 9.3 s^-1 in the photocatalytic Ru(bpy)3^2+‐Na2S2O8 system.Our findings suggest that future design of active iron‐based oxides as WOCs requires the consideration of their hydration status.

Development of a bismuth-based metal-organic framework for photocatalytic hydrogen production

A novel 3 D bismuth-organic framework(called Bi-TBAPy) single crystal was synthesized by employing 1,3,6,8-tetrakis(p-benzoic acid)pyrene(H4TBAPy) as an organic linker. The study demonstrates that the Bi-TBAPy not only possesses good chemical stability and suitable band edge positions for promising photocatalytic H2 evolution, but it also exhibits a typical ligand-to-metal charge transfer for favorable charge separation. The photocatalytic H2 evolution rates on the as-obtained Bi-TBAPy with different cocatalysts modified were examined with triethanolamine as the sacrificial reagent. Based on this, the hydrogen evolution rate of 140 μmol h-1 g-1 was obtained on the optimized sample with a loading of 2 wt% Pt as a cocatalyst. To the best of our knowledge, this is the first bismuth-based metal-organic framework(MOF) that functions as an effective photocatalyst for photocatalytic water reduction. Our study not only adds a new member to the family of photocatalyst materials, but also reveals the importance of cocatalyst modification in improving photocatalytic activity of MOFs.

Tip-induced directional charge separation on one-dimensional BiVO4 nanocones for asymmetric light absorption

One dimensional(1D)semiconductor is a class of extensively attractive materials for many emerging solar energy conversion technologies.However,it is still of shortage to assess the impact of 1D structural symmetry on spatial charge separation and understand its underlying mechanism.Here we take controllably-synthesized 1D BiVO_(4)nanocones and nanorods as prototypes to study the influence of 1D symmetry on charge separation.It is found that the asymmetric BiVO_(4)nanocones enable more effective charge separation compared with the symmetric nanorods.The unexpected spatial charge separation on the nanocones is mainly ascribed to uneven light absorption induced diffusion-controllable charge separation due to symmetry breaking of 1D nanostructure,as evidenced by spatial and temporal resolved spectroscopy.Moreover,the promotion effect of charge separation on the nanocones was quantitatively evaluated to be over 20 times higher than that in BiVO_(4)nanorods.This work gives the first demonstration of the influence of 1D structural symmetry on the charge separation behavior,providing new insights to design and fabricate semiconductor materials for efficient solar energy conversion.

Synthesis of perovskite BaTaO_(2)N with low defect by Zn doping for boosted photocatalytic water reduction

Perovskite BaTaO_(2) N(BTON) is one of the most promising photocatalysts for solar water splitting due to its wide visible-light absorption and suitable conduction/valence bands,but it still confronts the challenge of high defect density causing decreased charge separation as well as photocatalytic activity.In this work,we develop a simple zinc doping strategy to greatly suppress its defect density and promote its water reduction performance.It is found that the defect formation on the nitrided Ba(Zn_(1/3-x)Ta_(2/3))O_(3-y)N_z(denoted as BZTON hereafter) will be greatly inhibited when the Zn-doped Ba(Zn_(1/3)Ta_(2/3))O_(3)(BZTO) oxide is used as the nitridation precursor.The structural characterizations and discussion demonstrate that the effective inhibition of Ta^(5+)into Ta^(4+)defects in BZTON mainly results from the easy reduction of zinc ions into metal and further the evaporation of zinc metal under the thermal ammonia flow.Interestingly,this simply doping methodology can be easily extended into the synthesis of SrTaO_(2) N(STON) with extremely low defect density,demonstrating its generality.Benefiting from the successful control to the defect density,the as-obtained BZTON photocatalyst exhibits remarkably promoted charge separation as well as water reduction activity to produce hydrogen with respect to the pristine BTON.Our work may provide an alternative avenue to prepare oxynitride semiconductors with reduced defect density for promoted solar energy conversion.

Heterostructure of Ta_(3)N_(5) nanorods and CaTaO_(2)N nanosheets fabricated using a precursor template to boost water splitting under visible light

Fabrication of heterostructure composed of one-dimensional(1D)and 2D semiconductors has inspired extensive interest in promoting photogenerated charge separation as well as performances of solar fuel production,but it is still challenging for(oxy)nitride photocatalysts due to their uncontrollable ammonia thermal preparative process.In this work,we report a synthesis on heterostructure of Ta_(3)N_(5)nanorods and CaTaO_(2)N(CTON)nanosheets(denoted as Ta_(3)N_(5)/CTON)by directly nitriding a 2D Dion-Jacobson(DJ)type of perovskite KCa_(2)Ta_(3)O_(10)(KCTO)precursor under the assistance of K_(2)CO_(3)flux.It is demonstrated that the 2D morphology of KCTO can be well inherited to get 2D CTON,and the Ta-rich(nonstoichiometric ratio of Ca:Ta compared to CTON)feature of the KCTO as well as the easy evaporation of K species results in the formation of 1D Ta_(3)N_(5)nanorods.Meanwhile,the formation of intermediate species K_(2)Ca_(2)Ta_(3)O_(9)N owning similar crystal lattice as Ta_(3)N_(5)was detected and deduced to be responsible for the generation of Ta_(3)N_(5)nanorods and observation of intimate interface between CTON and Ta_(3)N_(5).Benefitting from the formation of special 1D/2D type-II heterostructure,obviously promoted charge separation as well as photocatalytic water splitting performance can be obtained.Extended discussion demonstrates the generality of the hard-template preparative strategy developed here.To our knowledge,this should be the first fabrication of 1D/2D heterostructure for the(oxy)nitride semiconductors,and the developed hard-template strategy may provide an alternative way of fabricating heterostructures of other semiconductors prepared at high temperature.

Multiple carbon interface engineering to boost oxygen evolution of Ni Fe nanocomposite electrocatalyst

Interface engineering has been widely investigated to regulate the structure and performance of electrodes and photoelectrodes,but the investigation of multiple carbon interface modifications on the electrocatalytic oxygen evolution reaction(OER)is still shortage.Herein,we report remarkable promotion of OER performance on the NiFe‐based nanocomposite electrocatalyst via the synergy of multiple carbon‐based interface engineering.Specifically,carbon nanotubes were in situ grown on carbon fiber paper to improve the interface between CFP and NiFeO_(x)H_(y),and graphite carbon nanoparticles were in situ loaded and partly doped into the NiFeO_(x)H_(y) to modify the intergranular interface charge transfer and electronic structure of NiFeO_(x)H_(y).Consequently,the as‐obtained NiFeO_(x)H_(y)‐C/CNTs/CFP catalyst exhibited significantly enhanced electrocatalytic OER activity with an overpotential of 202 mV at 10 mA cm^(-2) in 1 mol L^(-1) KOH.Our work not only extends application of carbon materials but also provides an alternative strategy to develop highly efficient electrocatalysts.

Development of Sn^(2+)-based oxyfluoride photocatalyst with visible light response of ca.650 nm via strengthened hybridization of Sn 5s and O 2p orbitals

The hybridization between the outmost s orbitals of metal(Bi^(3+),Sn^(2+),Pb^(2+),Ag^(+))and O 2 p orbitals has been widely employed to develop innovative semiconductors with upshift valence band as well as extended visible light response,but it is still challenging to obtain photocatalyst with absorption edge of above 550 nm.Here we report a novel Sn^(2+)-based oxyfluoride Sn_(2)TiNbO_6 F(STNOF)photocatalyst with a pyrochlore structure to exhibit an extended absorption edge to 650 nm and dual functionalities of both water reduction and oxidation.Density functional theory calculations suggest that the unprecedented broad-spectrum response of STNOF is mainly ascribed to the strengthened hybridization between O 2 p and Sn 5 s orbitals remarkably upshifting the valence band,which is caused by the distortion and compressive strain in the Sn06 F2 dodecahedron with second-order Jahn-Teller effect due to partial fluorine substitution.The structural distortion and compressive strain are experimentally confirmed by the Fourier-transformed extended X-ray absorption fine spectra.As probe tests of the photocatalytic functionalities,water reduction and oxidation half reactions were examined to see obvious H_(2)and O_(2)evolution under visible light irradiation.This work may provide an alternative strategy of developing extended visible light responsive semiconductors for promising solar energy conversion.

Model gradient: unified model and policy learning in model-based reinforcement learning

Model-based reinforcement learning is a promising direction to improve the sample efficiency of reinforcement learning with learning a model of the environment.Previous model learning methods aim at fitting the transition data,and commonly employ a supervised learning approach to minimize the distance between the predicted state and the real state.The supervised model learning methods,however,diverge from the ultimate goal of model learning,i.e.,optimizing the learned-in-the-model policy.In this work,we investigate how model learning and policy learning can share the same objective of maximizing the expected return in the real environment.We find model learning towards this objective can result in a target of enhancing the similarity between the gradient on generated data and the gradient on the real data.We thus derive the gradient of the model from this target and propose the Model Gradient algorithm(MG)to integrate this novel model learning approach with policy-gradient-based policy optimization.We conduct experiments on multiple locomotion control tasks and find that MG can not only achieve high sample efficiency but also lead to better convergence performance compared to traditional model-based reinforcement learning approaches.

Kinetics for hydrogen production by methanol steam reforming in fluidized bed reactor

Hydrogen is one of the best energy carriers.Fluidized bed reactor provides a promising approach for hydrogen production. To describe the hydrogen generating rate with methanol steam reforming in fluidized bed reactor quantitatively, dual-rate kinetic models of the reactions with exponent form were developed, including that of steam reforming reaction(SR) and decomposition reaction(DE).The reaction rate per unit mass of catalyst was related to partial pressures of components. The exponentials in kinetic equations were obtained by linear least-squares method based on the experimental data. The variance homogeneity test(F test) shows that the dynamic models are feasible with high accuracy, which can be used to predict the generating rate of hydrogen under different reaction temperatures and feed flow rates in fluidized bed reactor. The SR and DE activation energy obtained indicates that ESR\ EDE, which can explain the previous observation that the CO_2 selectivity decreased with the temperature increase.

Occurrence, variations, and risk assessment of neonicotinoid insecticides in Harbin section of the Songhua River, northeast China

Neonicotinoid insecticides(NNIs)have been intensively used and exploited,resulting in their presence and accumulation in multiple environmental media.We herein investigated the current levels of eight major NNIs in the Harbin section of the Songhua River in northeast China,providing the first systematic report on NNIs in this region.At least four NNIs in water and three in sediment were detected,with total concentrations ranging from 30.8 to 135 ng L^(-1) and from 0.61 to 14.7 ng g^(-1) dw,respectively.Larger spatial variations in surface water NNIs concentrations were observed in tributary than mainstream(p<0.05)due to the intensive human activities(e.g.,horticulture,urban landscaping,and household pet flea control)and the discharge of wastewater from many treatment plants.There was a significant positive correlation(p<0.05)between the concentrations of residual imidacloprid(IMI),clothianidin(CLO),and S4NNIs in the sediment and total organic carbon(TOC).Due to its high solubility and low octanol-water partition coefficient(Kow),the sediment-water exchange behavior shows that NNIs in sediments can re-enter into the water body.Human exposure risk was assessed using the relative potency factor(RPF),which showed that infants have the highest exposure risk(estimated daily intake(SIMIeq EDI):31.9 ng kg^(-1) bw$d^(-1)).The concentration thresholds of NNIs for aquatic organisms in the Harbin section of the Songhua River were determined using the species sensitivity distribution(SSD)approach,resulting in a value of 355 ng L^(-1) for acute hazardous concentration for 5%of species(HC5)and 165 ng L^(-1) for chronic HC5.Aquatic organisms at low trophic levels were more vulnerable to potential harm from NNIs.

Homogeneous nitrogen-doped(111)-type layered Sr5Nb4O15-xNx as a visible-light-responsive photocatalyst for water oxidation

The development of visible-light-responsive photocatalysts for promoting solar-driven oxygen(O2)production from water splitting is a potentially attractive but still a challenging scheme.In the present work,a(111)-type layered perovskite oxynitride,Sr5Nb4O15-xNx,was synthesized via the nitridation treatment of the disk-like oxide precursor under the ammonia flow,which was fabricated using a flux method.The homogeneous dispersion of nitrogen(N)dopant in N-doped Sr5Nb4O15 was ascertained by energy-dispersive X-ray spectroscopy characterization,and the Sr5Nb4O15-xNx was found to be a direct semiconductor with a light absorption edge of approximately 640 nm.Density functional theory investigation implies that the hybridization between the outmost N 2p orbitals and O 2p orbitals upshifts the original valence band maximum of Sr5Nb4O15 and endows its visible-light-responsive characteristics.Loading with cobalt oxide(CoOx)as cocatalyst,the as-prepared Sr5Nb4O15-xNx exhibited an enhanced photocatalytic O2 evolution activity from water splitting under visible-light illumination(λ>420 nm).Moreover,another homogeneous N-doped layered perovskite-type niobium(Nb)-based oxynitride,Ba5Nb4O15-xNx,was also developed and investigated for the visible-light-actuated O2 production,highlighting the versatility of the present approach for exploring novel visible-light-responsive photocatalysts.

Reversed configuration of photocatalyst to exhibit improved properties of basic processes compared to conventional one

Performances of semiconductor photocatalysts are integrally determined by efficiencies of basic processes such as light absorption,charge separation and surface catalysis,but conventional configurations of photocatalysts normally suffers from the competition of light absorption originating from cocatalyst deposition and limited interface charge separation between the photocatalyst and cocatalyst.Herein we give the first proof-of-concept illustration that a reversed configuration of photocatalysts with a core/shell structure of microsized Mo2N cocatalysts and nanosized CdS photocatalysts,which exhibits superior solar hydrogen production to the conventional configuration with nanosized Mo2N cocatalysts deposited on the surface of CdS photocatalysts.It is revealed that the reversed configuration outperforms the conventional one in all areas of light absorption,charge separation and surface catalysis.Strikingly,the special core/shell structure introduced here can well avoid the competition of light absorption by cocatalysts and make an effective confinement effect to promote the surface catalysis of Mo2N.Our finding provides an alternative strategy to improve performances of photocatalysts.

Water-stable Mn-based MOF nanosheet as robust visible-light-responsive photocatalyst in aqueous solution

Development of visible-light-responsive metal-organic frameworks(MOFs) for promising solar energy conversion has inspired continuous interest, but it still suffers from poor stability especially in aqueous solution and/or under photoirradiation due to their relatively labile coordination bonds. Herein, a new synthesized layered Mn-based MOF(Mn-TBAPy-BK) and its exfoliated twodemensional nanosheets(Mn-TBAPy-NS) are revealed to be highly stable no matter in aqueous solution with wide p H region or under visible light irradiation. As expected, the exfoliated Mn-TBAPy-NS exhibits enhanced surface area, shortened charge transfer distance, and superior charge separation with respect to the bulk one. Moreover, the as-obtained nanosheets can be employed as effective building block for nanocomposite and heterostructure assembly to further promote charge separation as well as solar hydrogen production from aqueous solution under visible light. The finding of water stable MOF nanosheet under visible light demonstrates its promising future for solar energy conversion.