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Molecular characterization and structure basis of a malonyltransferase with both substrate promiscuity and catalytic regiospecificity from Cistanche tubulosa

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Acta Pharmaceutica Sinica B 2024年第5期14卷 2333-2348页

作者： Xiao Liu Yuyu Liu Xiping Xu Wenqian Huang Yaru Yan Yingxia Wang Weisheng Tian Ting Mo Xiaoxue Cui Jun Li she-po shi Pengfei Tu Modern Research Center for Traditional Chinese Medicine Beijing Research Institute of Chinese MedicineBeijing University of Chinese MedicineBeijing 100029China Modern Research Center for Traditional Chinese Medicine School of Chinese Materia MedicaBeijing University of Chinese MedicineBeijing 100029China

Enzymatic malonylation of natural glycosides provides a promising alternative method for drug-like malonylated glycosides ***,the catalytic potential and structural basis of plant malonyltransferase are far from being fully *** work identified a new malonyltransferase CtMaT1 from Cistanche *** displayed unprecedented mono-and/or di-malonylation activity toward diverse glucosides with different aglycons.A“one-pot”system by CtMaT1 and a malonyl-CoA synthetase was established to biosynthesize nine new malonylated *** investigations revealed that CtMaT1 possesses an adequately spacious acyl-acceptor pocket capable of accommodating diverse ***,it recognizes malonyl-CoA through strong electrotactic and hydrogen ***/MM calculation revealed the H167-mediated SN2 reaction mechanism of CtMaT1,while dynamic simulations detected the formation of stable hydrogen bonds between the glucose-6-OH group and H167,resulting in its high malonylation *** energy profiles of two isomeric glycosides highlighted lower reaction energy barriers towards glucoside substrates,emphasizing CtMaT1's preference for ***,a mutant CtMaT1H36A with notably increased di-malonylation activity was *** underlying molecular mechanism was illuminated through MM/GBSA binding free energy *** study significantly advances the understanding of plant acyltransferases from both functional and protein structural perspectives,while also providing a versatile tool for enzymatic malonylation applications in pharmacology.

关键词： Plant acyltransferase Malonyltransferase Malonylated glycosides Enzymatic catalysis Enzyme promiscuity

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Promotion effects of salt-alkali on ammonia volatilization in a coastal soil

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Pedosphere 2024年第1期34卷 191-199页

作者： Zhenqi shi Dongli she Yongchun PAN Yongqiu XIA College of Agricultural Science and Engineering Hohai UniversityNanjing 210098China Jiangsu Province Engineering Research Center for Agricultural Soil-Water Efficient Utilization Carbon Sequestration and Emission ReductionNanjing 210098China Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China

Coastal ecosystems are highly susceptible to salt-related problems due to their formation process and geographical location. As such ecosystems are the most accessible land resources on Earth, clarifying and quantifying the effects of salt-alkali conditions on N concentration and ammonia(NH_(3)) volatilization are pivotal for promoting coastal agricultural productivity. The challenge in establishing this effect is to determine how salt-alkali conditions impact NH_(3) volatilization through direct or indirect interactions. An incubation experiment using a coastal soil from a paddy farmland, combined with the structural equation modeling(SEM) method, was conducted to reveal the net effects of salt-alkali on NH_(3) volatilization and the role of environmental and microbial factors in mutual interaction networks. The specific experimental design consisted of four salt treatments(S1, S2, S3, and S4: 1‰, 3‰, 8‰, and 15‰ NaCl by mass of soil, respectively), four alkaline treatments(A1, A2, A3, and A4: 0.5‰, 1‰, 3‰, and 8‰ NaHCO_(3)by mass of soil, respectively) and a control without NaCl or NaHCO_(3) addition(CK), and each treatment had three urea concentrations(N1, N2, and N3: 0.05, 0.10, and 0.15 g N kg^(-1) soil,respectively) and three replicates. At the N1, N2, and N3 levels, NH_(3)volatilization increased by 9.31%–34.98%, 3.07%–26.92%, and 2.99%–43.61% as the NaCl concentration increased from 1‰ to 15‰, respectively, compared with CK. With an increase in the NaHCO_(3)concentration from 0.5‰ to 8‰, NH_(3) volatilization increased by 8.36%–56.46%, 5.49%–30.10%, and 30.72%–73.18% at the N1, N2, and N3 levels, respectively, compared with CK. According to the SEM method, salinity and alkalinity had positive direct effects on NH_(3)volatilization, with standardized path coefficients of 0.40 and 0.19, *** the total effects(net positive and negative effects) in the SEM results, alkalinity had a greater influence than salinity(total standardized coefficien

关键词： alkalinity coastal ecosystem NH_(3)emission N-transforming microbe salinity structural equation modeling

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Chord length sampling correction analysis for dispersion fuel in Monte Carlo simulation

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Nuclear Science and Techniques 2024年第4期35卷 57-64页

作者： Zhao-Yu Liang Ding she Yu-Tong Wen Lei shi Institute of Nuclear and New Energy Technology(INET) Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China

Dispersion fuels,knowned for their excellent safety performance,are widely used in advanced reactors,such as hightemperature gas-cooled *** with deterministic methods,the Monte Carlo method has more advantages in the geometric modeling of stochastic *** explicit modeling method has high computational accuracy and high computational *** chord length sampling(CLS)method can improve computational efficiency by sampling the chord length during neutron transport using the matrix chord length?s probability density *** study shows that the excluded-volume effect in realistic stochastic media can introduce certain deviations into the CLS.A chord length correction approach is proposed to obtain the chord length correction factor by developing the Particle code based on equivalent transmission *** numerical analysis against reference solutions from explicit modeling in the RMC code,it was demonstrated that CLS with the proposed correction method provides good accuracy for addressing the excludedvolume effect in realistic infinite stochastic media.

关键词： Stochastic media Monte Carlo Chord length sampling Excluded-volume effect Chord length correction

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Properties and Characteristics of Regolith-Based Materials for Extraterrestrial Construction

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Engineering 2024年第6期37卷 159-181页

作者： Cheng Zhou Yuyue Gao Yan Zhou Wei she Yusheng shi Lieyun Ding Changwen Miao National Center of Technology Innovation for Digital Construction Huazhong University of Science and TechnologyWuhan 430074China School of Civil and Hydraulic Engineering Huazhong University of Science and TechnologyWuhan 430074China School of Materials Science and Engineering Southeast UniversityNanjing 214135China State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

The construction of extraterrestrial bases has become a new goal in the active exploration of deep *** the construction techniques,in situ resource-based construction is one of the most promising because of its good sustainability and acceptable economic cost,triggering the development of various types of extraterrestrial construction materials.A comprehensive survey and comparison of materials from the perspective of performance was conducted to provide suggestions for material selection and *** types of typical construction materials are discussed in terms of their reliability and applicability in extreme extraterrestrial ***,thermal and optical,and radiation-shielding properties are *** influencing factors and optimization methods for these properties are *** the perspective of material properties,the existing challenges lie in the comprehensive,long-term,and real characterization of regolith-based construction ***,the suggested future directions include the application of high-throughput characterization methods,accelerated durability tests,and conducting extraterrestrial experiments.

关键词： Extraterrestrial construction Characterization Mechanical property Thermal property Optical property Radiation-shielding

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Difference in microstructural characteristics of stamp-charged coke and gravity-charged coke with approximate macroscopic performance

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Journal of Iron and Steel Research International 2024年第5期31卷 1050-1062页

作者： Chong Zou Zheng-yan Huang Jian-yun Li Bin Li shi-wei Liu Yuan she School of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an710311ShaanxiChina Technical Center of Shandong Iron and Steel Co. Ltd.(Laiwu Branch)Jinan271104ShandongChina

The microstructural characteristics including optical texture,porosity and pore structure and chemical structure of stamp-charged coke(SCC)and gravity-charged coke(GCC)with similar conventional macro-indicators were investigated,and the properties including micro-strength,reactivity of coke matrix and that after alkali enrichment were comparatively studied by various characterization *** anisotropic structure of SCC is composed of high content of fine mosaic texture,while the content of medium mosaic texture,coarse texture and fibrous texture is *** statistical average shows that the fine mosaic average of SCC(24.89%)is 3.78 times the GCC average(6.58%),and the coarse mosaic average(1.24%)is only about 1/3 of the GCC average(3.43%).The porosity of SCC is lower than that of GCC,but tamping process does not lead to the fact that the number of closed pores of SCC is significantly lower than that of *** the structure of SCC is compact,its pore number is large and the pore wall is *** of coke with diameter less than 150 nm seem unaffected by tamping *** aromatic structure of SCC was less ordered than that of GCC,which was speculated to be related to the addition of more low metamorphic coal in *** microscopic strength and structural strength of SCC are lower than those of *** reactivity of coke matrix is affected by the specific surface area,but it is not the determining factor of its *** improvement in dissolution reactivity of coke after potassium enrichment is independent of coke type.

关键词： Stamp-charged coke Optical texture porosity Microstructure Reactivity

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Geant4 simulation of fast-electron bremsstrahlung imaging at the HL-3 tokamak

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Nuclear Science and Techniques 2024年第9期35卷 213-229页

作者： shi-Kui Cheng Yi-po Zhang Yue-Jiang shi Jie Zhang Shuai Guan Hong-Bing Xu Qiu-Lei Yang College of Science Chongqing University of TechnologyChongqing 400054China Chongqing Key Laboratory of New Energy Storage Materials and Devices Chongqing 400054China Southwestern Institute of Physics Chengdu 610041China Hebei Key Laboratory of Compact Fusion Langfang 065001China ENN Science and Technology Development Co. Ltd.Langfang 065001China

To further research on high-parameter plasma,we plan to develop a two-dimensional hard X-ray(HXR)imaging system at the HL-3 tokamak to measure HXRs with energies ranging from 20 to 300 *** application of an array-structured detector ensures that this system can measure HXR-radiation spectra from the entire plasma cross ***,it is suitable for the study of fast-electron physics,such as radio-frequency wave current drives,fast electrons driving instabilities,and plasma disruptions in fusion *** this study,we develop a simulation for calculating fast-electron bremsstrahlung in the HL-3 tokamak based on the Monte Carlo simulation code Geant4,in which the plasma geometry and forward scattering of fast-electron bremsstrahlung are *** preliminary calculation results indicate that the HXR energy deposi-tion on the detector is symmetrically distributed,even though the plasma distribution is asymmetric owing to the toroidal *** simulation results are helpful in constructing the relationship between the energy deposition on the detector and parameter distribution on the plasma cross section during HL-3 *** is beneficial for the reconstruction of the fast-electron-distribution function and for optimizing the design of the HXR-imaging system.

关键词： Geant4 simulation HL-3 tokamak Fast-electron bremsstrahlung Hard X-ray imaging

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Effects of desert plant communities on soil enzyme activities and soil organic carbon in the proluvial fan in the eastern foothills of the Helan Mountain in Ningxia,China

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Journal of Arid Land 2024年第5期16卷 725-737页

作者： sheN Aihong shi Yun MI Wenbao YUE Shaoli she Jie ZHANG Fenghong GUO Rui HE Hongyuan WU Tao LI Hongxia ZHAO Na College of Forestry and Prataculture of Ningxia University Yinchuan 750021China School of Geography and Planning of Ningxia University Yinchuan 750021China Ningxia Hui Autonomous Region Agricultural Comprehensive Development Center Yinchuan 750002China Ningxia Helan Mountain National Nature Reserve Administration Yinchuan 750021China Yinchuan Yinxi Ecological Protection Forest Management Center Yinchuan 750002China

It is of great significance to study the effects of desert plants on soil enzyme activities and soil organic carbon(SOC)for maintaining the stability of the desert *** this study,we studied the responses of soil enzyme activities and SOC fractions(particulate organic carbon(poC)and mineral-associated organic carbon(MAOC))to five typical desert plant communities(Convolvulus tragacanthoides,Ephedra rhytidosperma,Stipa breviflora,Stipa tianschanica ***,and Salsola laricifolia communities)in the proluvial fan in the eastern foothills of the Helan Mountain in Ningxia Hui Autonomous Region,*** recorded the plant community information mainly including the plant coverage and herb and shrub species,and obtained the aboveground biomass and plant species diversity through sample surveys in late July *** samples were also collected at depths of 0–10 cm(topsoil)and 10–20 cm(subsoil)to determine the soil physicochemical properties and enzyme *** results showed that the plant coverage and aboveground biomass of *** community were significantly higher than those of ***,***,and *** *** communities(PpoC and MAOC contents than the ***,the content of poC in the topsoil was 18.17%–42.73%higher than that in the *** structural equation model(SEM)indicated that plant species diversity,soil pH,and soil water content(SWC)were the main factors influencing poC and *** soil pH inhibited the formation of poC and promoted the formation of ***,SWC stimulated poC production and hindered MAOC *** study aimed to gain insight into the effects of desert plant c

关键词： proluvial fan desert plant community soil enzyme activity particulate organic carbon mineral-associated organic carbon Helan Mountain

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Double quantum images encryption scheme based on chaotic system

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Chinese Physics B 2024年第4期33卷 305-320页

作者：蒋社想李杨石锦张茹 School of Computer Science and Engineering Anhui University of Science and TechnologyHuainan 232001China Anhui Key Laboratory of Mine Intelligent Equipment and Technology Anhui University of Science&TechnologyHuainan 232001China

This paper explores a double quantum images representation(DNEQR)model that allows for simultaneous storage of two digital images in a quantum superposition ***,a new type of two-dimensional hyperchaotic system based on sine and logistic maps is investigated,offering a wider parameter space and better chaotic behavior compared to the sine and logistic *** on the DNEQR model and the hyperchaotic system,a double quantum images encryption algorithm is ***,two classical plaintext images are transformed into quantum states using the DNEQR ***,the proposed hyperchaotic system is employed to iteratively generate pseudo-random *** chaotic sequences are utilized to perform pixel value and position operations on the quantum image,resulting in changes to both pixel values and ***,the ciphertext image can be obtained by qubit-level diffusion using two XOR operations between the position-permutated image and the pseudo-random *** corresponding quantum circuits are also *** results demonstrate that the proposed scheme ensures the security of the images during transmission,improves the encryption efficiency,and enhances anti-interference and anti-attack capabilities.

关键词： double quantum images encryption chaotic system pixel scrambling XOR operation

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The effect of secondary phase on corrosion behaviors of the titanium–zirconium–molybdenum alloy

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Tungsten 2024年第2期6卷 342-354页

作者： Song-Wei Ge Ping Hu Jie Deng shi-Lei Li Hai-Rui Xing Jia-Yu Han Xing-Jiang Hua Li Wang Jun-Zhou Yang Bo Jin Wen Zhang Kuai-she Wang School of Metallurgy Engineering Xi’an University of Architecture and TechnologyXi’an 710055China National and Local Joint Engineering Research Center for Functional Materials Processing Xi’an University of Architecture and TechnologyXi’an 710055China Western Xinxing Rare and Precious Metals Co. Ltd.Shangluo 726000China Northwest Institute for Non-Ferrous Metal Research Xi’an 710016China

As the range of applications for molybdenum and its alloys has expanded,the corrosive environment for molybdenum alloys has become more *** the past,the content of doping elements has been studied to investigate their infl uence on the corrosion performance of titanium–zirconium–molybdenum(TZM)*** this paper,it is considered that the second phase in the alloy is the main factor aff ecting the corrosion performance of TZM *** comparing the corrosion behavior of molybdenum metal and TZM alloy,the eff ect of the secondary phase on corrosion behaviors of TZM alloy has been *** results show that the second phase reduces the corrosion resistance of the TZM *** potential of the second phase is 73.7 mV higher than that of the Mo matrix,which contributes to the formation of microscopic electric *** the action of microscopic electric couples,pitting corrosion is preferentially formed at the interface between the second phase and the matrix,which accelerates the corrosion of the *** paper provides a theoretical basis for the application of TZM alloys in corrosive environments.

关键词： Secondary phase Electrochemical corrosion Titanium–zirconium–molybdenum(TZM) Galvanic corrosion Corrosion resistance

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钛基石墨烯复合材料的分散性、界面结构及力学性能

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材料导报 2024年第5期38卷 234-241页

作者：佘欢时磊董安平上海应用技术大学机械工程学院上海201418 上海交通大学材料科学与工程学院上海200240 上海市先进高温材料及其精密成形重点实验室上海200240

石墨烯由于独特的结构和优异的力学、导电、润滑等性能,被认为是理想的金属基复合材料的增强体。将石墨烯作为增强体增强钛基复合材料有着巨大的应用潜力。然而,石墨烯的分散性及其与钛基体的反应是制约获得高性能石墨烯增强钛基复合材... 详细信息

石墨烯由于独特的结构和优异的力学、导电、润滑等性能,被认为是理想的金属基复合材料的增强体。将石墨烯作为增强体增强钛基复合材料有着巨大的应用潜力。然而,石墨烯的分散性及其与钛基体的反应是制约获得高性能石墨烯增强钛基复合材料的难点。本文综述了钛基石墨烯复合材料的分散性、界面及力学性能的研究进展。钛基石墨烯复合材料通常采用粉末冶金法制备,石墨烯能较均匀地分散于复合材料组织中,但当石墨烯添加量过多时仍会出现团聚现象。石墨烯与钛基体易发生反应生成TiC,通过固化烧结工艺的改进、基体复合化、石墨烯表面改性以及原位自生等方法可以有效地抑制界面反应并提高界面结合力。随着石墨烯含量的增加,钛基石墨烯复合材料的压缩、拉伸强度与硬度一般呈现先增大后减小的趋势。石墨烯增强钛基复合材料的强化机制通常以载荷传递强化为主,但有些情况下由石墨烯引起的位错强化、细晶强化及奥罗万(Orowan)强化效果也较为显著。

关键词：石墨烯钛基复合材料分散性界面强度强化机制

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