激光焊接及焊后热处理K439B合金的显微组织与力学性能

对应用于发动机涡轮上的新型镍基合金K439B进行激光焊接实验,研究焊后热处理对接头显微组织和力学性能的影响。半定量分析结果表明,热处理后接头各区域γ′相均发生长大,一次γ′相和二次γ′相半径分别约为25和150 nm。力学性能测试结果表明,焊后热处理可使焊缝区硬度提高约HV 100,由γ′相提供的临界恢复剪应力从4.8 MPa提高到92 MPa;另一方面,热处理后接头的抗拉强度和屈服强度与母材的相当,大量碳化物的存在导致接头在拉伸过程中优先断裂于母材处。

超高速激光金属沉积增材制造K648高温合金的显微组织与性能

采用一种新型的超高速激光金属沉积工艺以提高高铬高温合金的制造效率。分别使用透射电子显微镜、拉伸试验机、磨损试验机和电化学工作站对超高速激光金属沉积高铬K648高温合金的析出相生长行为、高温力学性能、耐磨性和耐腐蚀性进行研究,并与传统激光金属沉积工艺进行比较。结果表明,超高速激光金属沉积K648合金的析出相尺寸明显小于传统激光金属沉积工艺制备的K648合金,700℃下的高温强度更高,且具有良好的耐磨性和耐腐蚀性。总之,超高速激光金属沉积制造的K648高铬高温合金具有良好的综合性能。

Inhibitory effect of saffron on head and neck squamous cell carcinoma via targeting of ESR1 and CCND1 by its active compound crocetin

Background:Traditional Chinese medicine is promising for managing challenging and complex disorders,including cancer,and in particular,saffron is applied in treating various cancer types.However,its potential therapeutic efficacy and active components in managing squamous cell carcinoma of the head and neck(HNSCC)remain unclear yet.Methods:Using network pharmacology approaches,active ingredients of saffron,their target genes,and HNSCC-related genes were identified.Enrichment analyses were conducted for determining molecular functions and pathways enriched by genes that overlapped between the saffron target gene set and the HNSCC gene set.Among the four known active ingredients of saffron,crocetin was found to have the strongest inhibitory impact on HNSCC,based on the findings of cell viability and migration assays.Therefore,the potential target genes of crocetin in HNSCC cells were examined using molecular docking experiments and were confirmed by qPCR.Result s:Four active ingredients of saffron and 184 of their target genes were identified.Further,a total of 34 overlapping saffron-/HNSCC-associated targets related to the four active ingredients were screened,and crocetin was chosen for further investigation because it had the strongest inhibitory effect on HNSCC cells.Molecular docking experiments indicated that ESR1 and CCND1 were the target genes of crocetin.These results were confirmed through qPCR analysis,in which crocetin was found to lower the expression of the ESR1 and CCND1 genes in AMC-HN-8 and FaDu cells.Conclusion:According to our results,crocetin is a primary active anti-cancer component of saffron that may have potential in the development of novel HNSCC-treating medications.However,more thorough molecular research is necessary for confirming these results and elucidating the anti-cancer mechanism underlying saffron.

纳米CoCrCuFeNi高熵合金原子尺度的实时变形行为

通过分子动力学方法分别在2×10^(8)~1×10^(10)s^(-1)的不同应变率和10~1200 K的不同温度下进行拉伸试验,并研究纳米CoCrCuFeNi高熵合金的实时变形行为。结果表明,在高温和低应变速率下的主要变形机制是晶界滑移。随着温度的降低和应变速率的增加,位错滑移取代晶界滑移来控制塑性变形,进而提高合金的强度。此外,为进一步研究晶界对力学行为的影响,对具有不同晶粒尺寸的合金进行模拟。结果发现,当晶粒尺寸过小时,纳米高熵合金的强度随着晶粒尺寸的增加而增加,表现出反Hall-Petch关系。

Adaptive Backstepping Terminal Sliding Mode Control Method Based on Recurrent Neural Networks for Autonomous Underwater Vehicle

The trajectory tracking control problem is addressed for autonomous underwater vehicle(AUV) in marine environ?ment, with presence of the influence of the uncertain factors including ocean current disturbance, dynamic modeling uncertainty, and thrust model errors. To improve the trajectory tracking accuracy of AUV, an adaptive backstepping terminal sliding mode control based on recurrent neural networks(RNN) is proposed. Firstly, considering the inaccu?rate of thrust model of thruster, a Taylor’s polynomial is used to obtain the thrust model errors. And then, the dynamic modeling uncertainty and thrust model errors are combined into the system model uncertainty(SMU) of AUV; through the RNN, the SMU and ocean current disturbance are classified, approximated online. Finally, the weights of RNN and other control parameters are adjusted online based on the backstepping terminal sliding mode controller. In addition, a chattering?reduction method is proposed based on sigmoid function. In chattering?reduction method, the sigmoid function is used to realize the continuity of the sliding mode switching function, and the sliding mode switching gain is adjusted online based on the exponential form of the sliding mode function. Based on the Lyapu?nov theory and Barbalat’s lemma, it is theoretically proved that the AUV trajectory tracking error can quickly converge to zero in the finite time. This research proposes a trajectory tracking control method of AUV, which can e ectively achieve high?precision trajectory tracking control of AUV under the influence of the uncertain factors. The feasibility and e ectiveness of the proposed method is demonstrated with trajectory tracking simulations and pool?experi?ments of AUV.

Evolution of interfacial dislocation networks during long term thermal aging in Ni-based single crystal superalloy DD5

Interfacial dislocations found in single crystal superalloys after long term thermal aging have an important effect on mechanical properties. Long term thermal aging tests for DD5 single crystal superalloy were carried out at 1,100 ℃ for 20, 100, 200, 500 and 1000 h, and then cooled by air. The effect of long term thermal aging on the dislocation networks at the γ/γ' interfaces was investigated by FE-SEM. Results showed that during the long term thermal aging at 1,100 ℃, misfit dislocations formed firstly and then reorientation in the(001) interfacial planes occurred. Different types of square or rectangular dislocation network form by dislocation reaction. Square dislocation networks consisting of four groups of dislocations can transform into octagonal dislocation networks, and then form another square dislocation network by dislocation reaction. Rectangular dislocation networks can also transform into hexagonal dislocation networks. The interfacial dislocation networks promote the γ' phase rafting process. The dislocation networks spacings become smaller and smaller, leading to the effective lattice misfit increasing from-0.10% to-0.32%.

A Hemophagocytic Lymphohistiocytosis Patient Initiated with Prominent Liver Dysfunction: a Case Report

HEMOPHAGOCYTIC lymphohistiocytosis(HLH)is an aggressive and potentially fatal syndrome that results from inappropriate activation of lymphocytes and macrophages.It is characterized by fever,hepatosplenomegaly,cytopenias,hypertriglyceridemia,hypofibrinogenemia,and pathologic findings of hemophagocytosis in the bone marrow or other tissues.We report an adult HLH case admitted to hepatology department.

Differential Innervation of Secretory Coils and Ducts in Human Eccrine Sweat Glands

Background： Previous studies demonstrate that eccrine sweat glands are innervated by both cholinergic and adrenergic nerves. However, it is still unknown whether the secretory coils and ducts ofeccrine sweat glands are equally innervated by the sympathetic nerve fibers. To welt understand the mechanisms on sweat secretion and reabsorption, the differential innervation of secretory coils and ducts in human eccrine sweat glands was investigated in the study. Methods： From June 2016 to June 2017, six human skins were fixed, paraffin-embedded, and cut into 5 μm-thick sections, followed by costaining for nerve fiber markers protein gene product 9.5 （PGP 9.5）, tyrosine hydroxylase （TH） and vasoactive intestinal peptide （VIP）, and eccrine sweat gland markers K7, S100P, and K14 by combining standard immunofluorescence with tyramide signal amplification （IF-TSA）. Stained sections were observed under the microscope, photographed, and analyzed. Results： The fluorescent signals of PGP 9.5, TH, and VIP were easily visualized, by 1F-TSA, as circular patterns surrounding eccrine sweat glands, but only PGP 9.5 could be observed by standard IF. The IF-TSA method is more sensitivity than standard IF in detecting antigens expressed at low levels. PGP 9.5, TH, and VIP appeared primarily surrounding the secretory coils and sparsely surrounding the sweat ducts. Conclusion： Sweat secretion is mainly controlled by autonomic nerves whereas sweat reabsorption is less affected by nerve activity.