MgF_(2)涂层对Mg-Zn-Ca合金在模拟体液中应力腐蚀开裂行为的影响

采用慢应变拉伸测试方法对Mg-3wt.%Zn-0.2wt.%Ca(质量分数)(MZC)合金和氟化镁(MgF_(2))涂层Mg-3wt.%Zn-0.2wt.%Ca合金(MZC-MF)的应力腐蚀开裂行为进行研究。结果表明,MgF_(2)涂层可以显著提高MZC合金在模拟体液(SBF)中的耐腐蚀性并延长其断裂失效时间。MgF_(2)涂层明显降低MZC合金在SBF中的应力腐蚀敏感性,应力腐蚀开裂敏感性指数(Iscc)分别降低21%(UTS),22%(tf),23%(δ),7%(φ)和15%(A)。

Model-based deep learning for fiber bundle infrared image restoration

As the representative of flexibility in optical imaging media,in recent years,fiber bundles have emerged as a promising architecture in the development of compact visual systems.Dedicated to tackling the problems of universal honeycomb artifacts and low signal-to-noise ratio(SNR)imaging in fiber bundles,the iterative super-resolution reconstruction network based on a physical model is proposed.Under the constraint of solving the two subproblems of data fidelity and prior regularization term alternately,the network can efficiently“regenerate”the lost spatial resolution with deep learning.By building and calibrating a dual-path imaging system,the real-world dataset where paired low-resolution(LR)-high-resolution(HR)images on the same scene can be generated simultaneously.Numerical results on both the United States Air Force(USAF)resolution target and complex target objects demonstrate that the algorithm can restore high-contrast images without pixilated noise.On the basis of super-resolution reconstruction,compound eye image composition based on fiber bundle is also embedded in this paper for the actual imaging requirements.The proposed work is the first to apply a physical model-based deep learning network to fiber bundle imaging in the infrared band,effectively promoting the engineering application of thermal radiation detection.

Magneto-thermo-mechanical characterization of giant magnetostrictive materials

The variations of magnetization and magneto- striction with temperature and stress were investigated through the analysis of the effective field, induced by temperature and stress. A nonlinear magnetostrictive model of giant magnetostrictive materials was proposed. The proposed model can be used to calculate the magnetostrictive characterization of giant magnetostrictive materi- als in different temperatures and under different stresses. The coupling effects of axial stress, magnetic field, and temperature on the magnetostriction of a Terfenol-D rod were numerically simulated as well as experimentally tested. Comparison between the calculating and experimental results shows that the proposed model can better describe the magneto-thermo-mechanical characteristics of Terfenol-D rod under different temperatures and compressive stress. Therefore, the proposed model possesses an important significance for the design of magnetostrictive devices.

Importance of the stem cell microenvironment for ophthalmological cell-based therapy

Cell therapy is a promising treatment for diseases that are caused by cell degeneration or death. The cells for clinical transplantation are usually obtained by culturing healthy allogeneic or exogenous tissue invitro. However, for diseases of the eye, obtaining the adequate number of cells for clinical transplantation is difficult due to the small size of tissue donors and the frequent needs of long-term amplification of cells in vitro, which results in low cell viability after transplantation. In addition, the transplanted cells often develop fibrosis or degrade and have very low survival. Embryonic stem cells(ESCs) and induced pluripotent stem cells(i PS) are also promising candidates for cell therapy. Unfortunately, the differentiation of ESCs can bring immune rejection, tumorigenicity and undesired differentiated cells, limiting its clinical application. Although i PS cells can avoid the risk of immune rejection caused by ES cell differentiation post-transplantation, the low conversion rate, the risk of tumor formation and the potentially unpredictable biological changes that could occur through genetic manipulation hinder its clinical application. Thus, the desired clinical effect of cell therapy is impaired by these factors. Recent research findings recognize that the reason for low survival of the implanted cells not only depends on the seeded cells, but also on the cell microenvironment, which determines the cell survival, proliferation and even reverse differentiation. When used for cell therapy, the transplanted cells need a specific three-dimensional structure to anchor and specific extra cellular matrix components in addition to relevant cytokine signaling to transfer the required information to support their growth. These structures present in the matrix in which the stem cells reside are known as the stem cell microenvironment. The microenvironment interaction with the stem cells provides the necessary homeostasis for cell maintenance and growth. A large number of studies suggest that to explore how to reconstruct the stem cell microenvironment and strengthen its combination with the transplanted cells are key steps to successful cell therapy. In this review, we will describe the interactions of the stem cell microenvironment with the stem cells, discuss the importance of the stem cell microenvironment for cell-based therapy in ocular diseases, and introduce the progress of stem cell-basedtherapy for ocular diseases.

Extrusion process of 304L H-shaped stainless steel used in passive residual heat removal heat exchanger

304L H-shaped stainless steel is used as the support frame of the passive residual heat removal heat exchanger(PRHR HX) in a nuclear fission reactor. The extrusion process is adopted to manufacture the 304L H-shaped stainless steel. Finite element method simulation is herein used to analyze metal flow characteristics, optimize the extrusion die, and predict the extrusion force at different temperatures and speeds. A Φ400-mm container and Φ388-mm forging billet are selected, and the 304L H-shaped stainless steel is successfully manufactured using a Germany SMS 60 MN horizontal extruder. The mechanical properties and microstructure of the manufactured 304L H-shaped stainless steel meet the requirements of the PRHR HX, and the surfaces of the product pass the dye penetration test. The H-shaped stainless steels are used in Haiyang nuclear power plant in Shandong Province.

Effect of Physical Aging on Heterogeneity of Poly(ε-caprolactone)Toughening Poly(lactic acid)Probed by Nanomechanical Mapping

Poly(lactic acid) (PLA) is a promising bio-based environmentally-friendly plastic. Nevertheless, the physical aging-induced brittleness of PLA limits its widespread applications. Blending with immiscible ductile polymer is an effective way to toughen PLA. However, the underlying details of the toughening mechanism and, in particular, the effect of physical aging are not well understood. Herein, atomic force microscopy (AFM) based nanomechanical mapping technology was utilized to visualize the differences in the deformation mechanisms between unaged and aged PLA/poly(ε-caprolactone) (PCL) blend upon uniaxial drawing. Results show that physical aging has a significant effect on the microscopic Young’s modulus and its distribution of PLA matrix, resulting in a highly heterogeneous response of the PLA/PCL blend to external stress and affecting the mechanical properties of the PLA phase under different extensions. This work provides a new experimental basis for understanding the effect of physical aging on the mechanical properties of PLA-based materials.

Au-Catalyzed 1,3-Acyloxy Migration/Cyclization Cascade:A Direct Strategy toward the Synthesis of Functionalized Abietane-Type Diterpenes

A direct strategy toward the synthesis of functionalized abietane-type diterpenes and related polycyclic molecules was developed through an Au-catalyzed 1,3-acyloxy migration/cyclization/electrophilic aromatic substitution cascade.Unlike the known polyene-type cyclization strategies for the construction of abietane-type diterpene skeletons,propargylic ester groups were used for the cyclization process,which can readily lead to the key skeleton with C2 and C3 functionalization.As a demonstration of the potential application of this tandem reaction,a collective total synthesis of(±)-2-ketoferruginol,(±)-fleuryinol B,(±)-salviol,(±)-2β-acetoxyferruginol,and(±)-2β-acetoxysugiyl methyl ether was achieved.Among these molecules,(±)-fleuryinol B and(±)-2β-acetoxyferruginol were synthesized for the first time.