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Enantioselective trapping of oxonium ylide intermediates by N-benzhydryl-α-imino ester：Synthesis of β-tetrasubstituted α-amino acids

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Chinese Chemical Letters 2017年第2期28卷 213-217页

作者： shi-kun jia Yu-Bing Lei Long-Long Song Shun-Ying Liu Wen-Hao Hu Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development School of Chemistry and Chemical Engineering East China Normal University Shanghai 200062 China

A synergistic rhodium（Ⅱ）/phosphoric acid catalyzed three component reaction of 3-diazooxindoles,alcohols and N-benzhydryl-α-imino ester is developed for the efficient construction of chiral β-alkoxy C-β-tetrasubstituted α-amino acid derivatives in good yields and with excellent diastereoselectivities and high *** synthetic application of the resulting products was illustrated by reducing with Pd/C under H_2 atmosphere followed reacting with CSCl_2 at room temperature to rapid afford 3-spirocyclic oxindole in a good yield with a chirality *** three-component reaction is proposed to proceed through an electrophilic trapping of the oxonium ylides by N-benzhydryl-α-imino ester.

关键词： Three-component reaction Oxonium ylide N-Benzhydryl-α-imino ester β-Tetrasubstituted α-amino acids Chiral phosphoric acid

Microstructural characterization and mechanical properties of(TiC+TiB)/TA15 composites prepared by an in-situ synthesis method

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China Foundry 2024年第2期21卷 168-174页

作者： Zhi-yong Zhang jiao-jiao Cheng jia-qi Xie shi-bing Liu kun shi Jun Zhao Shenyang Research Institute of Foundry Co. Ltd.CAMShenyang 110022China National Key Laboratory of Advanced Casting Technologies Shenyang 110022China

Titanium matrix composites reinforced with ceramic particles are considered a promising engineering material due to their combination of high specific strength,low density,and high *** this study,the TA15-based composites reinforced with a volume fraction of 10% to 25%(TiB+TiC)were prepared using powder metallurgy and casting *** characterization and phase constitution were examined using optical microscopy(OM),scanning electron microscopy(SEM),and X-ray diffraction(XRD).In addition,the microhardness,room temperature(RT)and high temperature(HT)tensile properties of the composites were *** revealed that the reinforcements are distributed uniformly even in the composites with a high volume of TiB and ***,as the volume fraction exceeds 15%,TiB and TiC particles become coarsening and exhibit rod-like and dendritic-like *** increases gradually from 321.2 HV for the base alloy to a maximum of 473.3 HV as the reinforcement increases to 25vol.%.Tensile test results indicate that a reinforcement volume fraction above 20% is beneficial for enhancing tensile strength and yield strength at high temperatures,but it has an adverse effect on room temperature ***,if the reinforcement volume fraction is below 20%,it can improve high-temperature elongation when the temperature exceeds 600℃.

关键词： titanium matrix composites microstucture microhardness tensile properties in-situ synthesis

Diastereodivergent formal[4+1]cycloaddition of azoalkenes as one-carbon synthons

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绿色合成与催化(英文) 2023年第3期4卷 258-262页

作者： Chun-Yan Guan Tian-jiao Han shi-kun jia Yuan-Zhao Hua Guang-jian Mei Green Catalysis Center College of ChemistryZhengzhou UniversityZhengzhou 450001China

The first diastereodivergent formal[4+1]cycloaddition reactions of azoalkenes with p-quinone methides(pQMs)have been *** reported reaction occurred via a domino oxa-1,4-addition/1,6-addition process,allowing the use of common azoalkenes as C1 synthons.A broad range of 2,3-dihydrobenzofurans was smoothly prepared in good yields and with reversible *** steric hindrance and hydrogenbonding interaction were proposed to account for the two different modes of *** projected reaction features the employment of azoalkene as carbene-like C1 synthon,mild conditions,broad substrate scope and tunable diastereoselectivity.

关键词： Azoalkene One-carbon synthon Diastereodivergent [4+1]Cycloaddition para-Quinone methides

Design and performance evaluation of a large field-of-view dual-particle time-encoded imager based on a depth-of-interaction detector

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Nuclear Science and Techniques 2024年第4期35卷 1-14页

作者： Dong Zhao Xu-Wen Liang Ping-kun Cai Wei Cheng Wen-Bao jia Da-Qian Hei Qing Shan Yong-Sheng Ling Chao shi Department of Nuclear Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 211106China Collaborative Innovation Center of Radiation Medicine of jiangsu Higher Education Institutions Suzhou 215000China School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China

Time-encoded imaging is useful for identifying potential special nuclear materials and other radioactive sources at a *** this study,a large field-of-view time-encoded imager was developed for gamma-ray and neutron source hotspot imaging based on a depth-of-interaction(DOI)*** imager primarily consists of a DOI detector system and a rotary dual-layer cylindrical coded *** EJ276 plastic scintillator coupled with two SiPMs was designed as the DOI detector to increase the field of view and improve the imager *** difference in signal time at both ends and the log of the signal amplitude ratio were used to calculate the interaction position *** position resolution of the DOI detector was calibrated using a collimated Cs-137 source,and the full width at half maximum of the reconstruction position of the Gaussian fitting curve was approximately 4.4 *** DOI detector can be arbitrarily divided into several units to independently reconstruct the source distribution *** unit length was optimized via Am-Be source-location experiments.A multidetector filtering method is proposed for image *** method can effectively reduce image noise caused by poor DOI detector position *** vertical field of view of the imager was(-55°,55°)when the detector was placed in the center of the coded mask.A DT neutron source at 20 m standoff could be located within 2400 s with an angular resolution of 3.5°.

关键词： Time-encoded imager Depth-of-interaction detector Dual-particle imaging Hotspot imaging

Reactive transport modeling constraints on the complex genesis of a lacustrine dolomite reservoir: A case from the Eocene Qaidam Basin,China

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Petroleum Science 2024年第4期21卷 2240-2256页

作者： Ying Xiong Bo Liu Xiu-Cheng Tan Zheng-Meng Hou jia-Shun Luo Ya-Chen Xie Kai-Bo shi kun-Yu Wu School of Earth and Space Sciences Peking University Institute of Oil and Gas Peking University China National Petroleum Corporation Key Laboratory of Carbonate Reservoirs Southwest Petroleum University Institute of Subsurface Energy Systems Clausthal University of Technology Research Institute of Exploration and Development PetroChina Qinghai Oil Field Company

Reactive transport modeling(RTM) is an emerging method used to address geological issues in diagenesis research. However, the extrapolation of RTM results to practical reservoir prediction is not sufficiently understood. This paper presents a case study of the Eocene Qaidam Basin that combines RTM results with petrological and mineralogical evidence. The results show that the Eocene Xiaganchaigou Formation is characterized by mixed siliciclastic-carbonate-evaporite sedimentation in a semiclosed saline lacustrine environment. Periodic evaporation and salinization processes during the syngeneticpenecontemporaneous stage gave rise to the replacive genesis of dolomites and the cyclic enrichment of dolomite in the middle-upper parts of the meter-scale depositional sequences. The successive change in mineral paragenesis from terrigenous clastics to carbonates to evaporites was reconstructed using RTM simulations. Parametric uncertainty analyses further suggest that the evaporation intensity(brine salinity) and particle size of sediments(reactive surface area) were important rate-determining factors in the dolomitization, as shown by the relatively higher reaction rates under conditions of higher brine salinity and fine-grained sediments. Combining the simulation results with measured mineralogical and reservoir physical property data indicates that the preservation of original intergranular pores and the generation of porosity via replacive dolomitization were the major formation mechanisms of the distinctive lacustrine dolomite reservoirs(widespread submicron intercrystalline micropores) in the Eocene Qaidam Basin. The results confirm that RTM can be effectively used in geological studies, can provide a better general understanding of the dolomitizing fluid-rock interactions, and can shed light on the spatiotemporal evolution of mineralogy and porosity during dolomitization and the formation of lacustrine dolomite reservoirs.

关键词： Reactive transport modeling Lacustrine dolomite Mineralogy and porosity evolution Reservoir genesis

Late-onset Cholestasis with Paucity of Portal Area Secondary 􀁗􀁒􀀃􀀫􀀱􀀩􀀔􀈕􀀃􀀧􀁈􀁉􀁌􀁆􀁌􀁈􀁑􀁆􀁜􀀃􀁌􀁑􀀃􀀤􀁇􀁘􀁏􀁗􀁋􀁒􀁒􀁇􀀝􀀃􀀤􀀃􀀦􀁄􀁖􀁈􀀃􀀵􀁈􀁓􀁒􀁕􀁗

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Journal of Clinical and Translational Hepatology 2024年第3期12卷 327-331页

作者： Xuemei Zhang kun Liu Xiaona Lu Wenlan Zheng jia shi shihan Yu Hai Feng Zhuo Yu Department of Hepatopathy Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese MedicineShanghaiChina Department of Pathology Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese MedicineShanghaiChina Institute of Infectious Disease Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese MedicineShanghaiChina

Hepatocyte nuclear factor 1β(HNF1β)is essential for biliary development,while its genetic defect triggers the dysplasia of interlobular bile ducts,leading to life-threatening hepatitis and *** date,this disorder has mainly been docu-mented in ***,we report a case of cholestasis in an adult patient caused by a de novo HNF1β mutation.A liver biopsy revealed remarkable shrinkage of the portal area accompanied by a decrease or absence of interlobular bile ducts,veins,and arteries in the portal *** case showed that an HNF1β defect could induce late-onset cholestasis with paucity of the portal area in adulthood.

关键词： HNF1β Cholestasis Adult patient Paucity of the portal area Renal cysts Case report

The Role of Consumer Privacy Concerns in Shaping Platform Strategy for Online Markets

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Journal of the Operations Research Society of China 2024年第2期12卷 363-386页

作者： Jin-kun Yang Yong-Rui Duan jia-Zhen Huo School Economics and Management Tongji UniversityShanghai 200092China

We investigate the effects of consumer privacy concerns on the pricing and personal data collection strategy of an online *** online platform derives revenues from disclosing consumer information to *** compete for the information in order to enable them to price discriminate and thus derive revenues from consumer purchases.A novel aspect of our research is that we allow the online platform to sell only a subset of consumer *** develop analytical models where consumers can/cannot protect their *** analysis yields three main ***,in the monopoly case,we find that when the consumer privacy disclosure aversion cost is relatively low,it is optimal for the platform to sell all consumer information to the ***,in the duopoly case,we illustrate that when the consumer privacy disclosure aversion cost is relatively low,the platform will sell all consumer information to only one firm;when the cost is moderate,the platform will choose to sell the information of only some consumers and to only one firm;when the cost is relatively high,the platform will select only some of the consumers and sell their information to both ***,it will be better for the platform to provide the information protection service for free when the privacy cost is low.

关键词： Price discrimination User privacy Consumer information Two-sided market Privacy disclosure aversion cost

Pressure transient characteristics of non-uniform conductivity fractured wells in viscoelasticity polymer flooding based on oil-water two-phase flow

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Petroleum Science 2024年第1期21卷 343-351页

作者： Yang Wang jia Zhang shi-Long Yang Ze-Xuan Xu shi-Qing Cheng National Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing102249China

Polymer flooding in fractured wells has been extensively applied in oilfields to enhance oil *** contrast to water,polymer solution exhibits non-Newtonian and nonlinear behavior such as effects of shear thinning and shear thickening,polymer convection,diffusion,adsorption retention,inaccessible pore volume and reduced effective ***,the flux density and fracture conductivity along the hydraulic fracture are generally non-uniform due to the effects of pressure distribution,formation damage,and proppant *** this paper,we present an oil-water two-phase flow model that captures these complex non-Newtonian and nonlinear behavior,and non-uniform fracture characteristics in fractured polymer *** hydraulic fracture is firstly divided into two parts:high-conductivity fracture near the wellbore and low-conductivity fracture in the far-wellbore section.A hybrid grid system,including perpendicular bisection(PEBI)and Cartesian grid,is applied to discrete the partial differential flow equations,and the local grid refinement method is applied in the near-wellbore region to accurately calculate the pressure distribution and shear rate of polymer *** combination of polymer behavior characterizations and numerical flow simulations are applied,resulting in the calculation for the distribution of water saturation,polymer concentration and reservoir *** with the polymer flooding well with uniform fracture conductivity,this non-uniform fracture conductivity model exhibits the larger pressure difference,and the shorter bilinear flow period due to the decrease of fracture flow ability in the far-wellbore *** field case of the fall-off test demonstrates that the proposed method characterizes fracture characteristics more accurately,and yields fracture half-lengths that better match engineering reality,enabling a quantitative segmented characterization of the near-wellbore section with high fracture conductivity and th

关键词： Polymer flooding Non-Newtonian fluid Non-uniform fracture conductivity Two-phase flow Pressure transient analysis

Engineered extracellular vesicles for targeted reprogramming of cancer-associated fibroblasts to potentiate therapy of pancreatic cancer

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Signal Transduction and Targeted Therapy 2024年第7期9卷 3077-3096页

作者： Pengcheng Zhou Xuanlong Du Weilu jia kun Feng Yewei Zhang Department of General Surgery Affiliated Hospital of Nantong UniversityNantongChina School of Medicine Southeast UniversityNanjingChina Nanjing Medical University NanjingChina Hepatobiliary and Pancreatic Center The Second Affiliated Hospital of Nanjing Medical UniversityNanjingChina

Pancreatic cancer is one of the deadly malignancies with a significant mortality rate and there are currently few therapeutic options for *** tumor microenvironment(TME)in pancreatic cancer,distinguished by fibrosis and the existence of cancer-associated fibroblasts(CAFs),exerts a pivotal influence on both tumor advancement and resistance to *** advancements in the field of engineered extracellular vesicles(EVs)offer novel avenues for targeted therapy in pancreatic *** study aimed to develop engineered EVs for the targeted reprogramming of CAFs and modulating the TME in pancreatic *** obtained from bone marrow mesenchymal stem cells(BMSCs)were loaded with miR-138-5p and the anti-fibrotic agent pirfenidone(PFD)and subjected to surface modification with integrinα5-targeting peptides(named IEVs-PFD/138)to reprogram CAFs and suppress their pro-tumorigenic ***α5-targeting peptide modification enhanced the CAF-targeting ability of ***-138-5p directly inhibited the formation of the FERMT2-TGFBR1 complex,inhibiting TGF-βsignaling pathway *** addition,miR-138-5p inhibited proline-mediated collagen synthesis by directly targeting the FERMT2-PYCR1 *** combination of miR-138-5p and PFD in EVs synergistically promoted CAF reprogramming and suppressed the pro-cancer effects of *** experiments using the orthotopic stroma-rich and patient-derived xenograft mouse models yielded promising *** particular,IEVs-PFD/138 effectively reprogrammed CAFs and remodeled TME,which resulted in decreased tumor pressure,enhanced gemcitabine perfusion,tumor hypoxia amelioration,and greater sensitivity of cancer cells to ***,the strategy developed in this study can improve chemotherapy *** IEVs-PFD/138 as a targeted therapeutic agent to modulate CAFs and the TME represents a promising therapeutic approach for pancreatic cancer.

关键词： inhibited targeted chemotherapy