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聚合型防老剂

橡胶参考资料 1975年第9期 35-41页

作者： E.Kay D.K.Thomas w.w.wright 吴同锴

在某些应用上,例如高速飞机,要求橡胶另件能在高温并且经常与流体(诸如煤油、酯等液压介质)接触的条件下长期工作。特别是高温用橡胶诸如目前在飞机上广泛应用的氟胶、硅胶甚至最终也要发生老化。这种老化,在很大程度上是热氧作用的结果... 详细信息

在某些应用上,例如高速飞机,要求橡胶另件能在高温并且经常与流体(诸如煤油、酯等液压介质)接触的条件下长期工作。特别是高温用橡胶诸如目前在飞机上广泛应用的氟胶、硅胶甚至最终也要发生老化。这种老化,在很大程度上是热氧作用的结果,如果橡胶能保持在绝氧条件下应用,则可预期使用寿命明显增加。但是从系统中排除氧通常是行不通

关键词：防老剂分子网抗老剂聚合型硫化胶

Superexchange and charge transfer in the nickelate superconductor La_(3)Ni_(2)O_(7) under pressure

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Science China(Physics,Mechanics & Astronomy) 2024年第11期67卷 1-8页

作者： wéi wú Zhihui Luo Dao-Xin Yao Meng wang Center for Neutron Science and Technology Guangdong Provincial Key Laboratory of Magnetoelectric Physics and DevicesSchool of PhysicsSun Yat-sen UniversityGuangzhou 510275China

Recently, a bulk nickelate superconductor La_(3)Ni_(2)O_(7) is discovered at pressures with a remarkable high transition temperature T_(c)~ 80 K. Here, we study a Hubbard model with tight-binding parameters derived from ab initio calculations of La_(3)Ni_(2)O_(7),by employing large scale determinant quantum Monte Carlo and cellular dynamical mean-field theory. Our result suggests that the superexchange couplings in this system are comparable to that of cuprates. The system is a charge transfer insulator as the hole concentration becomes four per site at large Hubbard U. Upon hole doping, two low-energy spin-singlet bands emerge in the system exhibiting distinct correlation properties: while the one composed of the out-of-plane Ni-d_(3z^(2)-r^(2)) and O-p_(z) orbitals demonstrates strong antiferromagnetic correlations and narrow effective bandwidth, the in-plane singlet band consisting of the Ni-d_(x^(2)-y^(2)) and O-p_(x)/p_(y) orbitals is in general more itinerant. Over a broad range of hole doping, the doped holes occupy primarily the d_(x^(2)-y^(2)) and p_(x)/p_(y) orbitals, whereas the d_(3z^(2)-r^(2)) and p_(z) orbitals retain underdoped. we propose an effective t-J model to capture the relevant physics and discuss the implications of our result for comprehending the La_(3)Ni_(2)O_(7) superconductivity.

关键词： superconductivity nickelate superconductors Hubbard model superexchange charge transfer insulator quantum Monte Carlo

Superplasticity of fine-grained Mg-10Li alloy prepared by severe plastic deformation and understanding its deformation mechanisms

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Journal of Magnesium and Alloys 2024年第1期12卷 316-331页

作者： H.T.Jeong S.w.Lee w.J.Kim Department of Materials Science and Engineering Hongik UniversityMapo-guSangsu-dong 72-1Seoul 121-791Republic of Korea

The superplastic behavior and associated deformation mechanisms of a fine-grained Mg-10.1 Li-0.8Al-0.6Zn alloy(LAZ1011)with a grain size of 3.2μm,primarily composed of the BCCβphase and a small amount of the HCPαphase,were examined in a temperature range of 473 K to 623 *** microstructural refinement of this alloy was achieved by employing high-ratio differential speed *** best superplasticity was achieved at 523 K and at strain rates of 10^(-4)-5×10^(-4)s^(-1),where tensile elongations of 550±600%were *** the heating and holding stage of the tensile samples prior to tensile loading,a significant increase in grain size was observed at temperatures above 573 ***,it was important to consider this effect when analyzing and understanding the superplastic deformation behavior and *** the investigated strain rate range,the superplastic flow at low strain rates was governed by lattice diffusion-controlled grain boundary sliding,while at high strain rates,lattice diffusion-controlled dislocation climb creep was the rate-controlling deformation *** was concluded that solute drag creep is unlikely to *** the late stages of deformation at 523 K,it was observed that grain boundary sliding led to the agglomeration of theαphase,resulting in significant strain *** mechanism maps were constructed forβ-Mg-Li alloys in the form of 2D and 3D formats as a function of strain rate,stress,temperature,and grain size,using the constitutive equations for various deformation mechanisms derived based on the data of the current tests.

关键词： Magnesium-lithium alloy Superplasticity Severe plastic deformation Grain size Grain growth

Pervasive Attentive Neural Network for Intelligent Image Classification Based on N-CDE’s

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Computers, Materials & Continua 2024年第4期79卷 1137-1156页

作者： Anas w.Abulfaraj Department of Information Systems Faculty of Computing and Information TechnologyKing Abdulaziz UniversityRabigh21911Saudi Arabia

The utilization of visual attention enhances the performance of image classification *** attentionbased models have demonstrated notable performance,but many of these models exhibit reduced accuracy when confronted with inter-class and intra-class similarities and ***-Controlled Differential Equations(N-CDE’s)and Neural Ordinary Differential Equations(NODE’s)are extensively utilized within this ***’s possesses the capacity to effectively illustrate both inter-class and intra-class similarities and differences with enhanced *** this end,an attentive neural network has been proposed to generate attention maps,which uses two different types of N-CDE’s,one for adopting hidden layers and the other to generate attention *** distinct attention techniques are implemented including time-wise attention,also referred to as bottom N-CDE’s;and element-wise attention,called topN-CDE’***,a trainingmethodology is proposed to guarantee that the training problem is sufficiently *** classification tasks including fine-grained visual classification andmulti-label classification,are utilized to evaluate the *** proposedmethodology is employed on five publicly available datasets,including CUB-200-2011,ImageNet-1K,PASCAL VOC 2007,PASCAL VOC 2012,and MS *** obtained visualizations have demonstrated that N-CDE’s are better appropriate for attention-based activities in comparison to conventional NODE’s.

关键词： Differential equations neural-controlled DE image classification attention maps N-CDE’s

The quasi-Gramian solution of a non-commutative extension of the higher-order nonlinear Schr?dinger equation

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Communications in Theoretical Physics 2024年第3期76卷 51-61页

作者： H w A Riaz J Lin Department of Physics Zhejiang Normal UniversityJinhua 321004China

The nonlinear Schr?dinger(NLS)equation,which incorporates higher-order dispersive terms,is widely employed in the theoretical analysis of various physical *** this study,we explore the non-commutative extension of the higher-order NLS *** treat real or complex-valued functions,such as g_(1)=g_(1)(x,t)and g_(2)=g_(2)(x,t)as non-commutative,and employ the Lax pair associated with the evolution equation,as in the commutation *** derive the quasi-Gramian solution of the system by employing a binary Darboux *** soliton solutions are presented explicitly within the framework of *** visually understand the dynamics and solutions in the given example,we also provide simulations illustrating the associated ***,the solution can be used to study the stability of plane waves and to understand the generation of periodic patterns within the context of modulational instability.

关键词： integrable systems Darboux transformation solitons

Outcomes of endoscopic submucosal dissection in cirrhotic patients: First American cohort

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world Journal of Hepatology 2024年第5期16卷 784-790页

作者： Robert Luke Pecha Fares Ayoub Ankur Patel Abdullah Muftah Michael w wright Mai A Khalaf Mohamed O Othman Department of Gastroenterology and Hepatology UC DavisSacramentoCA 95817United States Department of Gastroenterology and Hepatology Baylor College of MedicineHoustonTX 77030United States Internal Medicine Baylor College of MedicineHoustonTX 77030United States Department of Gastroenterology and Hepatology University of Texas Medical Branch at GalvestonGalvestonTX 77550United States Medical School Baylor College of MedicineHoustonTX 77030United States Department of Tropical Medicine Tanta UniversityTanta 31527Egypt

BACKGROUND Among patients with cirrhosis and pre-malignant or early malignant mucosal lesions,surgical intervention carries a much higher bleeding *** such lesions are discovered,endoscopic submucosal dissection(ESD)may offer curative therapy with lower risks than surgery and improved outcomes compared to traditional endoscopic *** To evaluate the outcomes of ESD in patients with *** Patients with cirrhosis undergoing ESD between July 2015 and August 2022 were retrospectively matched in 1:2 fashion to controls based on lesion location,size,and anticoagulation *** outcomes were compared between *** A total of 64 Lesions from 59 patients were included(16 cirrhosis,43 control).There were no differences in patient or lesion characteristics between *** bloc and curative resection was achieved in 84.21%,78.94%of the cirrhosis group and 88.89%,68.89%of controls,respectively,with no significant *** patients had significantly higher rates of intra-procedural coagulation grasper use for control of bleeding(47.37%vs 20%;P=0.02).There were otherwise no significant differences in adverse event *** the 29 patients with follow up,we found higher rates of recurrence in the cirrhosis group compared to controls(40%vs 5.26%;P=0.019),however this effect did not persist on multivariable analysis controlling for known *** ESD may be safe and effective in patients with *** procedure related outcomes were not significantly different between ***-procedural bleeding requiring use of the coagulation grasper use was expectedly higher in the cirrhosis group given the known effects of liver disease on hemostasis.

关键词： Endoscopic aubmucosal dissection Cirrhosis Advanced polypectomy Intraprocedural bleeding Colon cancer

Recent Advances in the Synthesis and Polymerization of New CO_(2)-Based Cyclic

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Chinese Journal of Chemistry 2024年第4期42卷 430-443页

作者： Matteo Lanzi Arjan w.Kleij Institute of Chemical Research of Catalonia(ICIQ) The Barcelona Institute of Science and Technology(BIST)Av.Països Catalans 1643007 TarragonaSpain Catalan Institute of Research and Advanced Studies(ICREA) Pg.Lluís Companys 2308010 BarcelonaSpain

Carbon dioxide can be converted into functional heterocycles known as cyclic carbonates,whose recent reactivity has been expanded towards the formation of tailor-made engineering *** minireview gives an overview of the most topical developments in this area with a special focus on the synthetic methods employed to prepare these CO_(2)based *** addition,their application potential in the area of polymer science using a variety of polymerization techniques is discussed that have in common the ring-opening of the carbonate *** perspectives are provided that provide impetus for the scientific communities aligning research to the use of sustainable processes for polymers from recyclable carbon sources such as CO_(2).

关键词： Carbon dioxide Cyclic carbonates Functional macromolecules Heterocycles Polycarbonates Recycling Ring opening polymerization

Effect of Eu3+,Bi3+,and Li+ doping on luminescent property of GdNbO4

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Journal of Rare Earths 2024年第1期42卷 66-75页

作者： S.w.wi Y.S.Lee Department of Physics and Integrative Institute of Basic Sciences Soongsil University

we investigated the emission properties of Eu3+-doped GdNbO4-based oxide phosphors,aiming at improving the Eu3+emission by codoping of Bi3+and Li+.Eu3+singly doped,Eu3+and Bi3+doubly doped,and Eu3+,Bi3+,and Li+triply doped GdNbO4were prepared using a high-temperature solid-state reaction *** red-orange emissions from Eu3+in the singly doped samples are significantly improved by the codoping of Bi3+,mainly due to the energy transfer from Bi3+to Eu3+.The additional codoping of Li+is found to increase the Eu3+emission *** improvement might be attributed to the increase in the photoluminescent quantum yield originating from larger grain sizes and better crystallinity.A detailed analysis of the X-ray diffraction pattern and the asymmetric ratio estimated from the photoluminescence spectra show that the local lattice environment around Eu3+in GdNbO4does not change significantly with the codoping of Bi3+and Li+.Our results indicate that Li+doping is a promising way to improve the emission properties of rare-earth ion-doped GdNbO4phosphors.

关键词： Eu 3+ GdNbO 4 Codoping of Li + Photoluminescence Sensitizer Rare earths

Integrins and their potential roles in mammalian pregnancy

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Journal of Animal Science and Biotechnology 2024年第1期15卷 1-19页

作者： Gregory A.Johnson Robert C.Burghardt Fuller w.Bazer Heewon Seo Joe w.Cain Department of Veterinary Integrative Biosciences School of Veterinary Medicine and Biomedical SciencesTexas A&M UniversityCollege StationTX 77843‑4459USA Department of Animal Science College of Agriculture and Life SciencesTexas A&M UniversityCollege StationTX 77843‑2471USA

Integrins are a highly complex family of receptors that, when expressed on the surface of cells, can mediate reciprocal cell-to-cell and cell-to-extracellular matrix(ECM) interactions leading to assembly of integrin adhesion complexes(IACs) that initiate many signaling functions both at the membrane and deeper within the cytoplasm to coordinate processes including cell adhesion, migration, proliferation, survival, differentiation, and metabolism. All metazoan organisms possess integrins, and it is generally agreed that integrins were associated with the evolution of multicellularity, being essential for the association of cells with their neighbors and surroundings, during embryonic development and many aspects of cellular and molecular biology. Integrins have important roles in many aspects of embryonic development, normal physiology, and disease processes with a multitude of functions discovered and elucidated for integrins that directly influence many areas of biology and medicine, including mammalian pregnancy, in particular implantation of the blastocyst to the uterine wall, subsequent placentation and conceptus(embryo/fetus and associated placental membranes) development. This review provides a succinct overview of integrin structure, ligand binding, and signaling followed with a concise overview of embryonic development, implantation, and early placentation in pigs, sheep, humans, and mice as an example for rodents. A brief timeline of the initial localization of integrin subunits to the uterine luminal epithelium(LE) and conceptus trophoblast is then presented, followed by sequential summaries of integrin expression and function during gestation in pigs, sheep, humans, and rodents. As appropriate for this journal, summaries of integrin expression and function during gestation in pigs and sheep are in depth, whereas summaries for humans and rodents are brief. Because similar models to those illustrated in Fig. 1, 2, 3, 4, 5 and 6 are present throughout the sc

关键词： Humans Implantation Integrins Pigs Pregnancy Rodents Sheep