Research on 3D chatter stability of blade by high-speed turn-milling

High speed turn-milling is regarded as the milling of a curved surface while rotating the workpiece around its centre point, which combines effectively the advantages of both turning and milling, wherein allows for good metal removal with the difficult-to-cut thin-walled workpieces in aviation. The objective of the present work is to study chatter stability of thin-walled blade by high-speed turn-milling in cutting condition. The dynamic model and the stability critical condition determined by the relative dynamic characteristics between cutter subsystem and blade subsystem are put forward. Aiming at the small-stiffness frequency response characteristics of thin walled structures, the stability critical domain is predicted based on the high-order dynamic behavior of the multi-DOF system. It can be shown that the chatter condition in turn-milling is closely related to both cutter speed and depth of cut, besides cutter geometry, engagement conditions, frequency response function, material property of workpiece and so on. Based on chatter stability simulation model to access 3D chatter stability lobes of high-speed turn-milling machining blades. This conclusion provides a theoretical foundation and reference for the orthogonal turn-milling mechanism research

Determination of banned pigment quinoline yellow in pastries by salting out assisted-high performance liquid chromatography

ObjectiveTo develop an analytical method for fast determination of banned pigment quinoline yellow in pastries by salting out assisted-high performance liquid chromatography.MethodsThe sample was extracted with 40% methanol-sodium chloride-water， precipitated with potassium ferrocyanide-zinc acetate solution， eluted with mobile phase of methanol-0.02 mol/L ammonium acetate solution， separated by X-Bridge C18 column v（150 mm×4.6 mm， 3.5 μm）， and detected with diode -array detector by external standard method.ResultsThe method showed good linearity （r>0.999） in the range of 0.4-40.0 μg/mL. The limit of detection （S/N=3） was 1.25 mg/kg and the limit of quantification （S/N=10） was 5.0 mg/kg. The average recoveries of three different concentrations level at 5.0， 10.0 and 50.0 mg/kg ranged from 89.18% to 110.10%， with relative standard deviation in the range of 2.83%-8.65%.ConclusionThe method was convenient， accurate and reproducible， and it was suitable for qualitative and quantitative analysis of banned pigment quinoline yellow in pastries

El patrimonio arqueológico del distrito Tambobamba - Apurímac y sus perspectivas de gestión

Se focaliza en el poblado de Tambobamba, en la cual analiza la situación actual del patrimonio arqueológico, evaluando el estado de protección del patrimonio arqueológico y los lineamientos existentes para implementar la gestión del Patrimonio Arqueológico del poblado de Tambobamba. Se debe indicar, además, que es el punto de partida para futuros trabajos que engloben a todo el distrito. Para el efecto se recurrió a la investigación documental y de campo, mediante el contacto con la realidad estudiada. Los resultados reflejan escasa participación de las autoridades locales en la gestión y manejo de los vestigios arqueológicos ubicados en su territorio; además de una escasa coordinación entre los diversos niveles de gobierno en lo que respecta a la problemática arqueológica. Por lo anterior se considera que es importante realizar un Plan de Gestión con objetivos a corto, mediano y largo plazo para las acciones de implementación, protección y conservación del patrimonio cultural y arqueológico de la zona; asimismo, promover la participación y la coordinación de todos los comprometidos con la protección del patrimonio, autoridades, instituciones del estado, organismos que promueven el turismo (agencias) y la población de la zona.Tesi

Two new psathyrelloid species of Coprinopsis (Agaricales, Psathyrellaceae) from China

In this study, Coprinopsis jilinensis and Coprinopsis pusilla were introduced, based on their morphological characteristics, the internal transcribed spacer (ITS) and large subunit ribosomal (LSU) region sequences of nrDNA. These new psathyrelloid species were found in Jilin Province, China. Coprinopsis jilinensis has brown pileus, utriform pleurocystidia, brown, smooth, dextrinoid basidiospores and tiny pore. It mainly grows on humus. Coprinopsis pusilla has small basidiomata, greyish-white pileus, thick and distinct veil at edges, subcolourless and verrucose basidiospores. It is poreless and it grows on the decaying wood of broad-leaved trees. Both of them belong to the C. sect. Melanthinae. A supplementary description of C. sect. Melanthinae was given in combination with the newly-discovered taxa and an identification key to the fourteen psathyrelloid species of Coprinopsis is provided. Coprinopsis sect. Canocipes and C. sect. Quartoconatae were evaluated and the phylogenetic position of the psathyrelloid species of Coprinopsis was discussed. Psathyrella subagraria, as a confusing species, was also discussed in this study

A Modified Artificial Bee Colony Algorithm Based on Search Space Division and Disruptive Selection Strategy

Artificial bee colony (ABC) algorithm has attracted much attention and has been applied to many scientific and engineering applications in recent years. However, there are still some insufficiencies in ABC algorithm such as poor quality of initial solution, slow convergence, premature, and low precision, which hamper the further development and application of ABC. In order to further improve the performance of ABC, we first proposed a novel initialization method called search space division (SSD), which provided high quality of initial solutions. And then, a disruptive selection strategy was used to improve population diversity. Moreover, in order to accelerate convergence rate, we changed the definition of the scout bee phase. In addition, we designed two types of experiments to testify our proposed algorithm. On the one hand, we conducted experiments to make sure how much each modification makes contribution to improving the performance of ABC. On the other hand, comprehensive experiments were performed to prove the superiority of our proposed algorithm. The experimental results indicate that SDABC significantly outperforms other ABCs, contributing to higher solution accuracy, faster convergence speed, and stronger algorithm stability

Allicin Inhibits Proliferation and Invasion in Vitro and in Vivo via SHP-1-Mediated STAT3 Signaling in Cholangiocarcinoma

Background/Aims: Cholangiocarcinoma (CCA) is a malignant tumor that is resistant to chemotherapy, so new therapeutic agents are needed. Allicin which is rapidly converted from allin by allinase, is one of the most biologically active compounds in freshly crushed garlic and has been shown to have strong anti-tumor effects. Our aim was to explore the molecular mechanism by which allicin affects the cell proliferation and invasion of CCA. Methods: Cell viability and apoptosis were measured using the CCK-8 assay, colony formation assay, and flow cytometry. Cell migration and invasion were evaluated by wound healing and Transwell assays, respectively. The expression of several proteins involved in cell apoptosis and invasion were assessed by Western blot. The activation of STAT3 signaling was detected by Western blot and immunofluorescence staining. The involvement of SHP-1 was determined using small interfering RNA (siRNA). Moreover, a nude mouse model of human CCA was established to assess the anti-tumor effects of allicin in vivo. Results: Allicin significantly suppressed CCA cell proliferation by activating the caspase cascade, inducing apoptosis, and reducing the expression of proteins downstream of STAT3, such as B-cell lymphoma 2 (Bcl-2), while upregulating Bcl-2-associated X (Bax) protein. In addition, allicin inhibited the migration, invasion, and epithelial-mesenchymal transition (EMT) of CCA cells. Moreover, the protein expression of MMP-2 and MMP-9 was significantly downregulated in CCA cells treated with allicin compared with CCA cells treated with control. Mechanistic investigations indicated that allicin upregulated SHP-1 expression in CCA, and pervanadate treatment reversed the allicin-induced downregulation of STAT3. Moreover, suppression of SHP-1 by siRNA overturned the effect of allicin on the induction of SHP-1 and inhibition of STAT3 activation. Additionally, treatment with allicin attenuated tumor growth in the nude mouse model of CCA. Conclusions: Our findings suggest that allicin suppresses cell proliferation and invasion via STAT3 signaling and may be a potential therapeutic agent for CCA

Synergistic Effect of Zn–Co Bimetallic Selenide Composites for Lithium–Sulfur Battery

Compared with monometallic selenides, heterogeneous bimetallic selenides have rich phase boundaries and superior electrical conductivity. ZnSe/CoSe2 composites were prepared by introducing Zn metal and using ZIF-8/67 as the precursor through the synergistic effect between Zn and Co after selenification. The electrocatalytic conversion of polysulfide is accelerated by ZnSe through chemical adsorption and the catalytic effect. The conductive CoSe2 surface provides a rapid diffusion path for lithium ions, accelerating the conversion of the polysulfide. On the basis of their individual strengths, ZnSe and CoSe2 can jointly promote the smooth adsorptive–diffuse–catalytic conversion process of polysulfide and induce the growth of lithium sulfide around its heterogeneous interface, thus enhancing the electrochemical performance of the lithium–sulfur battery cathode materials. The ZnSe/CoSe2–S electrode, at the optimal Zn-to-Co ratio of 1:1, has a 790.06 mAh g−1 initial specific capacity at 0.2 C and excellent cycling stability at 1 C. After 300 cycles, the final capacity is 300.85 mAh g−1, and the capacity retention rate reaches 82.71%

Refractive Index Sensor Based on the Fano Resonance in Metal–Insulator–Metal Waveguides Coupled with a Whistle-Shaped Cavity

A plasmonic refractive index sensor based on surface plasmon polaritons (SPPs) that consist of metal–insulator–metal (MIM) waveguides and a whistle-shaped cavity is proposed. The transmission properties were simulated numerically by using the finite element method. The Fano resonance phenomenon can be observed in their transmission spectra, which is due to the coupling of SPPs between the transmission along the clockwise and anticlockwise directions. The refractive index-sensing properties based on the Fano resonance were investigated by changing the refractive index of the insulator of the MIM waveguide. Modulation of the structural parameters on the Fano resonance and the optics transmission properties of the coupled structure of two MIM waveguides with a whistle-shaped cavity were designed and evaluated. The results of this study will help in the design of new photonic devices and micro-sensors with high sensitivity, and can serve as a guide for future application of this structure

Cytocompatibility and early inflammatory response of human endothelial cells in direct culture with Mg-Zn-Sr alloys

Crystalline Mg-Zinc (Zn)-Strontium (Sr) ternary alloys consist of elements naturally present in the human body and provide attractive mechanical and biodegradable properties for a variety of biomedical applications. The first objective of this study was to investigate the degradation and cytocompatibility of four Mg-4Zn-xSr alloys (x=0.15, 0.5, 1.0, 1.5wt%; designated as ZSr41A, B, C, and D respectively) in the direct culture with human umbilical vein endothelial cells (HUVEC) in vitro. The second objective was to investigate, for the first time, the early-stage inflammatory response in cultured HUVECs as indicated by the induction of vascular cellular adhesion molecule-1 (VCAM-1). The results showed that the 24-h in vitro degradation of the ZSr41 alloys containing a β-phase with a Zn/Sr at% ratio ∼1.5 was significantly faster than the ZSr41 alloys with Zn/Sr at% ∼1. Additionally, the adhesion density of HUVECs in the direct culture but not in direct contact with the ZSr41 alloys for up to 24h was not adversely affected by the degradation of the alloys. Importantly, neither culture media supplemented with up to 27.6mM Mg2+ ions nor media intentionally adjusted up to alkaline pH 9 induced any detectable adverse effects on HUVEC responses. In contrast, the significantly higher, yet non-cytotoxic, Zn2+ ion concentration from the degradation of ZSr41D alloy was likely the cause for the initially higher VCAM-1 expression on cultured HUVECs. Lastly, analysis of the HUVEC-ZSr41 interface showed near-complete absence of cell adhesion directly on the sample surface, most likely caused by either a high local alkalinity, change in surface topography, and/or surface composition. The direct culture method used in this study was proposed as a valuable tool for studying the design aspects of Zn-containing Mg-based biomaterials in vitro, in order to engineer solutions to address current shortcomings of Mg alloys for vascular device applications.Statement of significanceMagnesium (Mg) alloys specifically designed for biodegradable implant applications have been the focus of biomedical research since the early 2000s. Physicochemical properties of Mg alloys make these metallic biomaterials excellent candidates for temporary biodegradable implants in orthopedic and cardiovascular applications. As Mg alloys continue to be investigated for biomedical applications, it is necessary to understand whether Mg-based materials or the alloying elements have the intrinsic ability to direct an immune response to improve implant integration while avoiding cell-biomaterial interactions leading to chronic inflammation and/or foreign body reactions. The present study utilized the direct culture method to investigate for the first time the in vitro transient inflammatory activation of endothelial cells induced by the degradation products of Zn-containing Mg alloys