Effects of Electric Pulse Current on the Aging Kinetics of 2219 Aluminum Alloy

The conventional aging experiments and the low density electric pulse current (LDEPC for short) added aging experiments, with the self-made positive and negative alternating pulse power equipment, were conducted to study the influence of LDEPC on the dynamics of phase transformation in 2219 aluminum alloy by means of measuring the variation of hardness with aging time. The results showed that the hardness in both aging systems increased with the increasing of aging time until it reached the peak value; then it gradually reduced. The hardness of LDEPC added aging is generally greater than the conventional one before the peak aging time. The Avrami dynamics equation of conventional isothermal aging was obtained based on the hardness evolution law. The effects of electromigration and ponderomotive force were introduced into the Avrami empirical equation; in turn, the dynamics equation of LDEPC added aging was established. At last, the isothermal transformation curves of both the regular aging and the LDEPC added aging were derived which revealed that the nucleation rate, as well as the growth rate, was promoted by electric pulse current. The research work provided the theoretical support for the regulation of the coupling energy field on the dynamics of phase transformation in 2219 aluminum alloy

Evaluation of anti-fatigue property of Porphyridium cruentum in mice

Purpose: To evaluate the potential effects of Porphyridium cruentum (PC) on fatigue induced by forced swimming test in mice. Methods: Mice were randomly divided into normal control group (NC, i.e., untreated non-swimming); model control group (MC, untreated swimming); Spirulina treated group (SP, 800 mg/kg); PC-treated groups (50, 100, and 200 mg/kg), respectively. After intragastric administration for 14 consecutive days, a weight-bearing swimming experiment was conducted for the mice, and the biochemical indicators related to fatigue were examined, including exhaustive swimming time, glucose levels (Glu), hepatic glycogen contents (HG), muscle glycogen contents (MG), glutathione peroxidase activities (GSH-Px), creatine kinase (CK), malondialdehyde (MDA), urea nitrogen levels (SUN), lactate dehydrogenase activities (LDH), lactic acid (LA) as well as superoxide dismutase (SOD). Results: PC significantly prolonged the swimming endurance time compared to MC. After PC treatment, Glu, HG and MG were effectively increased dose-dependently, SUN, LA, LDH and CK levels in serum were significantly reduced. Moreover, PC treatment elevated the bioactivities of two antioxidant enzymes, namely, GSH-Px and SOD, while MDA content decreased when compared to MC group. Conclusion: These results indicate that PC exhibits strong anti-fatigue effect. Thus, PC may be suitable for incorporation in functional food to counter fatigue

Interface structures of i n c l i n e d ZnO thin film on ( 011 ) -MgO substrate with bulk-like optical properties

Abstract(#br)Combining different phase structure materials with unique properties to design novel devices plays a significant role in the development of modern electronics. Here, we explore the characteristics of this type of complex interface and epitaxy structures based on the coupling between hexagonal ZnO film and cubic MgO substrate. The ZnO film was prepared by the molecular beam epitaxy technique on the MgO ( 011 ) substrate. The analysis results from the in situ reflection high energy electron diffraction patterns, X-ray diffraction (XRD)-pole figures and high resolution transmission electron microscopy images demonstrate that the film exhibits two-fold symmetry domains with a growth direction deviated from c-axis at about 31 ° along the [ 010 ] MgO or [ 0 1 ¯ 0 ] MgO azimuth. Despite the intertwined diffusion from Zn and Mg atoms in the interface, which is the possible origin of a blue shift of about 0.083 eV in the Photoluminescence (PL) spectrum, the inclined film shows a full width at half maximum value that is close to the reported value from the high quality film. This work hopefully provides useful insights to the design and exploration of the novel optoelectronic devices that involve the integration of materials with different structure and different properties

PyPose v0.6: The Imperative Programming Interface for Robotics

PyPose is an open-source library for robot learning. It combines a learning-based approach with physics-based optimization, which enables seamless end-to-end robot learning. It has been used in many tasks due to its meticulously designed application programming interface (API) and efficient implementation. From its initial launch in early 2022, PyPose has experienced significant enhancements, incorporating a wide variety of new features into its platform. To satisfy the growing demand for understanding and utilizing the library and reduce the learning curve of new users, we present the fundamental design principle of the imperative programming interface, and showcase the flexible usage of diverse functionalities and modules using an extremely simple Dubins car example. We also demonstrate that the PyPose can be easily used to navigate a real quadruped robot with a few lines of code

3,3′Diindolylmethane Suppresses Vascular Smooth Muscle Cell Phenotypic Modulation and Inhibits Neointima Formation after Carotid Injury

3,3'Diindolylmethane (DIM), a natural phytochemical, has shown inhibitory effects on the growth and migration of a variety of cancer cells; however, whether DIM has similar effects on vascular smooth muscle cells (VSMCs) remains unknown. The purpose of this study was to assess the effects of DIM on the proliferation and migration of cultured VSMCs and neointima formation in a carotid injury model, as well as the related cell signaling mechanisms.DIM dose-dependently inhibited the platelet-derived growth factor (PDGF)-BB-induced proliferation of VSMCs without cell cytotoxicity. This inhibition was caused by a G0/G1 phase cell cycle arrest demonstrated by fluorescence-activated cell-sorting analysis. We also showed that DIM-induced growth inhibition was associated with the inhibition of the expression of cyclin D1 and cyclin-dependent kinase (CDK) 4/6 as well as an increase in p27(Kip1) levels in PDGF-stimulated VSMCs. Moreover, DIM was also found to modulate migration of VSMCs and smooth muscle-specific contractile marker expression. Mechanistically, DIM negatively modulated PDGF-BB-induced phosphorylation of PDGF-recptorβ (PDGF-Rβ) and the activities of downstream signaling molecules including Akt/glycogen synthase kinase(GSK)3β, extracellular signal-regulated kinase1/2 (ERK1/2), and signal transducers and activators of transcription 3 (STAT3). Our in vivo studies using a mouse carotid arterial injury model revealed that treatment with 150 mg/kg DIM resulted in significant reduction of the neointima/media ratio and proliferating cell nuclear antigen (PCNA)-positive cells, without affecting apoptosis of vascular cells and reendothelialization. Infiltration of inflammatory cells was also inhibited by DIM administration.These results demonstrate that DIM can suppress the phenotypic modulation of VSMCs and neointima hyperplasia after vascular injury. These beneficial effects on VSMCs were at least partly mediated by the inhibition of PDGF-Rβ and the activities of downstream signaling pathways. The results suggest that DIM has the potential to be a candidate for the prevention of restenosis

The Influence of Different External Fields on Aging Kinetics of 2219 Aluminum Alloy

By undertakig an aging experiment on 2219 aluminum alloy under different external field and by the method of hardness test, a comparative study on the kinetics of aging generated under different external fields was conducted. Furthermore, the time-temperature-transformation curves (TTT curve) were obtained, and the microstructure and mechanical property of the alloy under the effect of different external fields were tested. Results indicated that the effect of magnetic field postponed the alloy’s aging precipitation process, and slightly reduced its mechanical property; the effects of electric field accelerated the alloy’s aging precipitation, increased its mechanical property and made the precipitated phase of alloy smaller and diffused. In addition, through analysis, it was concluded that the performance of the specimen was even more balanced under the effect of electromagnetic field

Effect of Creep Aging Process on Microstructures and Properties of the Retrogressed Al-Zn-Mg-Cu Alloy

The creep aging behaviors of retrogressed Al-Zn-Mg-Cu alloy were studied by uniaxial tensile creep tests at 140 °C. The effects of creep aging time and applied stress on microstructures and properties of the studied alloy were investigated by using transmission electron microscope (TEM), hardness, and corrosion resistance tests. Results show that the effects of the creep aging process on microstructures and properties are significant. The size of matrix precipitate (MPt), distance between MPts, width of precipitate-free zone (PFZ), and distance between grain boundary precipitates (GBPs) increase with the increase of creep aging time and applied stress. With the increase of creep aging time and applied stress, the corrosion resistance of the studied alloy improved. After creep aging for 20 h, the electrical conductivity varied with different applied stress from 35.99% to 37.24% International Annealed Copper Standard (IACS), and the exfoliation corrosion (EXCO) resistance increased to the corrosion rating of “EB”, which express slight surface corrosion. Compared with the traditional retrogression and re-aging process (RRA), the retrogression and creep aging process (RCA) can increase the MPt size, widen the precipitates distribution, narrow the PFZ width, and enhance the corrosion resistance while offering the hardness comparable to that of the RRA process