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Multiple damage zones around hydraulic fractures generated by high-frequency pulsating hydraulic fracturing

Petroleum Science 2024年第4期21卷 2688-2702页

作者： Yan Peng Sheng-jie wei Guang-Qing Zhang Da-wei Zhou Chuang-Chao Xu School of Petroleum Engineering China University of Petroleum PetroChina Changqing Oilfield Company

Pulsating hydraulic fracturing(PHF) is a promising fracturing method and can generate a dynamic periodic pressure. The periodic pressure can induce fatigue failure of rocks and decrease initiation pressure of fracture. If the frequency of periodic pressure exceeds 10 Hz, the distribution of pressure along the main fracture will be heterogeneous, which is much different from the one induced by the common fracturing method. In this study, the impact of this special spatial feature of pressure on hydraulic fracture is mainly investigated. A coupled numerical simulation model is first proposed and verified through experimental and theoretical solutions. The mechanism of secondary fracture initiation around the main fracture is then discovered. In addition, sensitivity studies are conducted to find out the application potential of this new method. The results show that(1) this coupled numerical simulation model is accurate. Through comparison with experimental and theoretical data, the average error of this coupled model is less than 1.01%.(2) Even if a reservoir has no natural fracture, this heterogeneous distribution pressure can also cause many secondary fractures around the main fracture.(3) The mechanism of secondary fracture initiation is that this heterogeneous distribution pressure causes tensile stress at many locations along the main fracture.(4) Through adjusting the stimulation parameters, the stimulation efficiency can be improved. The average and amplitude of pressure can increase possibility of secondary fracture initiation. The frequency of this periodic pressure can increase number of secondary fractures. Even 6 secondary fractures along a 100 m-length main fracture can be generated.(5) The influence magnitudes of stimulation parameters are larger than ones of geomechanical properties, therefore, this new fracturing method has a wide application potential.

关键词： Tight reservoir Reservoir stimulation Numerical simulation Secondary fracture Fracture initiation

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Rational design of hydroxytricyanopyrrole-based probes with high affinity and rapid visualization for amyloid-β aggregates in vitro and in vivo

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Chinese Chemical Letters 2024年第5期35卷 290-295页

作者： Jiajia Lv jie Gao Hongyu Li Zeli Yuan Nan dong School of Chemistry and Chemical Engineering Guizhou UniversityGuiyang 550025China School of Pharmacy Zunyi Medical UniversityZunyi 563003China Guizhou International Scientific and Technological Cooperation Base for Medical Photo-Theranostics Technology and Innovative Drug Development Zunyi 563003China

As key biomarkers,amyloid-β(Aβ)plaques are frequently used to diagnose Alzheimer’s disease(AD).Although fluorescence imaging has proven to be effective in detecting these plaques,the gold standard probe thioflavin T(ThT),used for Aβaggregates,cannot be applied in vivo owing to its invasive ***,the development of novel fluorescent probes capable of identifying Aβplaques in situ is *** on the ThT structure,twoπ-conjugated heterocyclic D-π-A probes were designed bearing the hydroxytricyanopyrrole acceptor and N,N-dimethylaminophenyl *** probes exhibited red to near-infrared fluorescence emission(λ_(max)=732 nm),large Stokes shifts(>100 nm),exceptional signal-to-noise ratio,rapid response(<30 s),and high binding affinity(NT-HTCP=33.32 nmol/L;NF-HTCP=53.35 nmol/L)for Aβ*** the best candidate,NT-HTCP was used for in situ imaging of Aβplaques in AD mouse ***,in vivo research demonstrated that NT-HTCP could cross the blood-brain barrier and continue imaging the Aβplaques with a good signal-to-noise ***,the outcomes of the docking computations helped guide the development of the Aβ*** study expands the family of N,N-dimethylaminophenyl-based Aβ-sensitive fluorophores,with NTHTCP emerging as a highly promising imaging agent.

关键词： Amyloid-β Fluorescent probe Hydroxytricyanopyrrole Fluorescence imaging Alzheimer’s disease

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Rational design and energy catalytic application of high-loading single-atom catalysts

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Rare Metals 2024年第10期43卷 4844-4866页

作者： Zi-wei Deng Yue Liu jie Lin Wen-Xing Chen Energy and Catalysis Center School of Materials Science and EngineeringBeijing Institute of Technology Ningbo Institute of Materials Technology and Engineering Chinese Academy of Science

It is well known that single-atom catalysts(SACs)have become a hot topic in the field of catalysis due to their advantages such as 100% metal atom utilization efficiency,high catalytic activity and selectivity compared with conventional catalysts and nanocatalysts. However, the isolated metal atoms on SACs have thermodynamic instability and tend to agglomerate, which limit their catalytic ***, it is of great significance to synthesize stable and high-loading single-atom catalysts(HLSACs). In this paper,we review the research progress of HLSACs from two aspects:design and application. Firstly, we comprehensively introduce the synthesis strategies of HLSACs, namely, top-down and bottom-up methods. Secondly, we overview the application status of HLSACs in three fields: electrocatalysis, thermal catalysis and photocatalysis. Finally, we summarize the development prospects and challenges of HLSACs.

关键词： Design Electrocatalysis High-loading single-atom catalysts Photocatalysis Thermal catalysis

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New Vacuum Solar Telescope Achieves Narrowband Infrared Solar Imaging Observation at He I 10830 A

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Research in Astronomy and Astrophysics 2024年第5期24卷 76-84页

作者： wei-jie Meng Fang-Yu Xu Zhen-Yu Jin Yunnan Observatories Chinese Academy of SciencesKunming 650011China Yunnan Key Laboratory of Solar Physics and Space Science Kunming 650216China University of Chinese Academy of Sciences Beijing 100049China

The near-infrared imaging channel constitutes a crucial component of the multichannel high-resolution imaging system of the New Vacuum Solar Telescope(NVST). We have successfully achieved high-resolution, narrowband imaging of the chromosphere using He I 10830 A triplet within this channel, which significantly enhances the imaging observation capabilities of NVST. This paper provides a concise overview of the optical system associated with the near-infrared imaging channel, detailing data processing procedures and presenting several observed images. Leveraging a high-resolution image reconstruction algorithm, we were able to generate a narrowband image near the diffraction limit at 10830 A with a temporal resolution of less than 10 s.

关键词： instrumentation detectors-instrumentation high angular resolution-Sun chromosphere-Sun infrared

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Microstructure and impact behavior of Mg-4Al-5RE-xGd cast magnesium alloys

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Journal of Magnesium and Alloys 2024年第5期12卷 1799-1814页

作者： jie wei Qudong Wang Huisheng Cai Mahmoud Ebrahimi Chuan Lei National Engineering Research Center of Light Alloy Net Forming and Key State Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

This work investigated the microstructure and impact behavior of Mg-4Al-5RE-xGd(RE represents La-Ce mischmetal;x=0,0.2,0.7 wt.%)alloys cast by high-pressure die casting(HPDC),permanent mold casting(PMC),and sand casting(SC)*** results indicated that with increasing Gd content,the grain sizes of the HPDC alloy had a slight change,but the grains of the PMC and SC alloys were significantly ***,the acicular Al_(11)RE_(3)phase was modified into the short-rod shape under the three casting *** impact toughness of the studied alloy was mainly dominated by the absorbed energy during the crack *** increasing Gd content,the impact toughness of the studied alloy monotonically increased due to the lower tendency of the modified second phase toward crack *** impact stress was higher than the tensile stress,exhibiting a strain rate sensitivity for the mechanical response;however,the HPDC alloy had an inconsistent strain rate sensitivity during the impact event due to the transformation of the deformation mechanism from twinning to slip with increasing *** dimples covered the fracture surface of the fine-grained HPDC alloys,indicating a typical ductile ***,due to the deficient{1012}twinning activity and the suppressed grain boundary sliding during the impact event,the HPDC alloys showed insufficient plastic deformation capacity.

关键词： Mg-Al-RE alloy Gadolinium Microstructure Impact behavior

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Optimal Strategy for Aircraft Pursuit-evasion Games via Self-play Iteration

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Machine Intelligence Research 2024年第3期21卷 585-596页

作者： Xin Wang Qing-Lai wei Tao Li jie Zhang State Key Laboratory of Management and Control for Complex Systems Institute of AutomationChinese Academy of SciencesBeijing100190China School of Artificial Intelligence University of Chinese Academy of SciencesBeijing100049China Institute of Systems Engineering Macao University of Science and TechnologyMacao999078China

In this paper,the pursuit-evasion game with state and control constraints is solved to achieve the Nash equilibrium of both the pursuer and the evader with an iterative self-play *** the condition where the Hamiltonian formed by means of Pontryagin’s maximum principle has the unique solution,it can be proven that the iterative control law converges to the Nash equilibrium ***,the strong nonlinearity of the ordinary differential equations formulated by Pontryagin’s maximum principle makes the control policy difficult to figured *** the system dynamics employed in this manuscript contains a high dimensional state vector with *** practical applications,such as the control of aircraft,the provided overload is ***,in this paper,we consider the optimal strategy of pursuit-evasion games with constant constraint on the control,while some state vectors are restricted by the function of the *** address the challenges,the optimal control problems are transformed into nonlinear programming problems through the direct collocation ***,two numerical cases of the aircraft pursuit-evasion scenario are given to demonstrate the effectiveness of the presented method to obtain the optimal control of both the pursuer and the evader.

关键词： Differential games pursuit-evasion games nonlinear control optimal control Nash equilibrium solution

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Formation and properties of a Zr-based amorphous coating by laser cladding

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Rare Metals 2024年第4期43卷 1809-1814页

作者： Ning Zhang Ying Liu wei Yang Shu-jie Pang Key Laboratory of Aerospace Materials and Performance(Ministry of Education) School of Materials Science and EngineeringBeihang UniversityBeijing100191China

(Zr_(0.53)Al_(0.1)Ni_(0.05)Cu_(0.3)Ti_(0.02))_(99)Y_1(at%)coating with amorphous layer of about 180μm thick was prepared on a steel substrate by using laser cladding *** coating is compact and shows good metallurgical bonding with *** microstructure,microhardness and corrosion behavior along the depth from the coating surface to the substrate were *** is found that a gradient structure consisted of amorphous surface layer,amorphous-crystalline transitional layer and substrate is formed after the laser *** microhardness and corrosion behavior exhibit variation with the microstructural evolution at different depths from the coating *** microhardness and corrosion resistance in 3.5 wt%NaCl solution of the amorphous surface layer are comparable to those of the as-cast Zr-based BMG with the same composition,and higher than those of the steel substrate.

关键词： Laser cladding Amorphous coating Microstructure Hardness Corrosion resistance

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Synergistic Brønsted Base/Photoredox-Catalyzed Three-Component Coupling with Malonates to Synthesize δ-Hydroxy Esters and δ-Keto Esters

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Chinese Journal of Chemistry 2024年第9期42卷 957-962页

作者： Ting Li wei Wang Ming dong Zhije Zhang Sha Yu Zhengchu Chen Siping wei dong Yi Green Pharmaceutical Technology Key Laboratory of Luzhou City Central Nervous System Drug Key Laboratory of Sichuan ProvinceSchoolof PharmacySouthwestMedicalUniversityLuzhouSichuan 646000China Nuclear Medicine and Molecular Imaging Key Laboratory of Sichuan Province LuzhouSichuan 646000China

Multicomponent alkene 1,2-dicarbofunctionalizations(DCFs)have emerged as a powerful strategy to rapidly incorporate both two carbon subunits across one C-C double bond in one step for enhancing molecular complexity and *** the best of our knowledge,there is only one report on photoredox-catalyzed three-component DCFs with malonates through the radical−radical cross-coupling,while photoredox-catalyzed radical-polar crossover(RPC)-type DCFs with malonates were still ***,we describe a redox-neutral RPC-type 1,2-dialkylation of styrenes with malonates and aldehydes through the synergistic Brønsted base/photoredox catalysis *** transition-metal-free strategy provides an efficient and clean approach to a broad variety ofδ-hydroxy esters and also features exceptionally mild conditions,wide compatibility of substrate scope and functional groups,and high atomic ***,three-component 1,2-alkylacylation from the same starting materials was achieved in one-pot manner through such RPC-type coupling and subsequent two-electron oxidation process,providing a set ofδ-keto esters of interest in pharmaceutical research.

关键词： Alkene difunctionalization Photoredox catalysis Malonates Radical reactions C-C coupling Synthetic methods Aldehydes Alkylation Multicomponentreactions

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A topology approach to overcome the pore size/volume trade-offs for autonomous indoor humidity control

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Science China Chemistry 2024年第9期67卷 2968-2974页

作者： Zhi-Shuo Wang Xue-Wen Zhang Kai Zheng Xiao-Xian Chen dong-dong Zhou jie-Peng Zhang MOE Key Laboratory of Bioinorganic and Synthetic Chemistry GBRCE for Functional Molecular EngineeringSchool of ChemistryIGCMESun Yat-Sen UniversityGuangzhou 510275China Chemistry and Chemical Engineering Guangdong Laboratory Shantou 515021China

Autonomous indoor humidity control is gaining more and more attention but is limited by the trade-offs among pore volume,pore size and water stability of water *** solve this problem by using a unique coordination network topology combined with hydrolytically stable M(Ⅲ)carboxylate *** extending the ligand length from 9.0 to 11.2 and 13.7?,the pore volume significantly increases from 0.99 to 1.40 and 1.78 cm^(3)g^(-1),which proportionally increases the saturated water adsorption ***,the pore size slightly increases from 10.4 to 11.0 and 13.5A,which restricts the isotherm inflection pressure and hysteresis width to meet the requirement of indoor humidity *** single-crystals suitable for Xray diffraction studies were obtained by using Fe(Ⅲ)salts,while isostructural frameworks with sufficiently high water stabilities were synthesized by using Cr(Ⅲ)salts,which offer record working capacity of 0.90 and 1.10 g g^(-1)for indoor humidity control.

关键词： metal-organic frameworks water adsorption indoor humidity control water stability pore engineering

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The Impact of Sulfur Fertilizer Concentration on the Nutrient Concentration of Parts of the Soybean Plant

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Phyton-International Journal of Experimental Botany 2024年第8期93卷 1851-1873页

作者： Xinhe wei wei Zhao Yanbin Sun Shoukun dong College of Agriculture Agricultural College of Northeast Agricultural UniversityHarbin150030China

Soybean is a crucial crop utilized for both food and oil production,with balanced crop nutrition being a key determinant of soybean yield throughout its growth ***,an essential nutrient for crop growth,substantially impacts soybean *** this study,two soybean cultivars,Laidou 2 and Hefeng 55,were used to study the changes in nitrogen,phosphorus,potassium,and sulfur contents in soybean plants at different growth ***,the effects of dry matter accumulation under five different sulfur levels were *** results showed that the sulfur levels had varying effects on the nitrogen,phosphorus,potassium,and sulfur contents and accumulation in different parts of the soybean *** were marked differences in the accumulation and distribution of dry matter in different parts of the soybean *** dry matter weight shows the best overall performance under the S80 *** increasing sulfur nutrition,the nitrogen,phosphorus,potassium,and sulfur contents in various plant parts exhibited an unimodal trend,reaching maximum values when the sulfur content was 80 mg/*** study elucidates the dynamic changes in nutrient elements in soybeans under different sulfur levels and is important in guiding the rational application of sulfur fertilizers in agricultural production.

关键词： Interaction sulfur elemental content

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