Study on the characteristics of high temperature alloy surface profile grinding process

High-temperature alloy profile grinding is mainly used in the machining of aero-engine turbine structural parts, which require high surface quality and high machining efficiency. However, the process ability of machining high-temperature alloys is poor. For this reason, this paper conducts experimental research on the surface profile grinding process of high-temperature alloys to meet the surface quality and machining efficiency requirements of high-temperature alloy structural parts. Using a precision profile grinding machine, WA and SG grinding wheels are selected for profile grinding tests on three types of workpieces with curved surfaces: flat, convex, and concave. Each shape of the workpiece was shaped-ground using WA and SG grinding wheels separately. The orthogonal experimental method was used to perform profile grinding by changing three factors: grinding wheel speed, feed, and backlash. The surface roughness after grinding was measured and compared, and the most suitable process parameters for grinding three curved workpieces with WA and SG grinding wheels were obtained by comparing the surface quality and machining efficiency. The grinding strategy is also given for surface roughness and machining efficiency. It provides a basis for the improvement of the quality and efficiency of high-temperature alloy forming and grinding

A Hydrothermal Synthesis of Fe3O4@C Hybrid Nanoparticle and Magnetic Adsorptive Performance to Remove Heavy Metal Ions in Aqueous Solution

Abstract Advanced core-shelled material with a high specific area has been considered as an effective material to remove heavy metal from aqueous solutions. A core-shelled Fe3O4@C hybrid nanoparticle aggregates with environmental-friendly channel in the study. Moreover, the higher exposure of adsorption sites can be achieved for the special configuration that higher Brunauer-Emmet-Teller (BET) surface area reaches up to 238.18 m2 g−1. Thus, a more efficiently heavy metal ion removal is obtained, Pb (II), Cd (II), Cu (II), and Cr (VI) up to 100, 99.2, 96.6, and 94.8%, respectively. In addition, the products are easy to be separated from the aqueous solutions after adsorption, due to the relative large submicrometer size and the enhanced external magnetic fields introduced by the iron-based cores. We provide an ideal mode to remove heavy metal ions using core-shelled Fe3O4@C under the water treatment condition. A new approach is clarified that core-shell nano/micro-functional materials can be synthesized well on large scales which are used in many fields such as environmental remediation, catalyst, and energy

Mortar dynamic coupled model for calculating interface gas exchange between organic and inorganic matters of shale

Shale gas has revolutionized the world energy in recent years. In this work, a mortar dynamic coupled model (MDCM) is successfully built for simulating gas transport from molecular motion in nanopores to highly permeable fractures. Results show that the production duration of MDCM can reach about tenfold that of a single medium model, which affords a microscale explanation for the long tail production. We also propose a two-stage process in the variation of the mass-exchange-rate with the pressure difference of organic matter and inorganic matter: it is nonlinear in Stage I, while shows a linear relationship in Stage II. Combined with theoretical analyses, numerical simulations and dimensional analyses, an effi-cient and practical relation for calculating the interface gas exchange in tail production is obtained. The relation offers a valuable tool for the gas transport properties in fractured shale and is finally validated by a gas expansion experiment. Better performance can be obtained in terms of accuracy and precision than the current model. These results stress the need for a change of paradigm from statistic to dynamic trans scale transport. The new insights into transport in the long-term shale gas production suggest new leads for the industry. (c) 2021 Elsevier Ltd. All rights reserved

Ultrasound–enhanced brain delivery of edaravone provides additive amelioration on disease progression in an ALS mouse model

Background: Although amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease and unfortunately incurable yet, incremental attention has been drawn to targeting the health of corticospinal motor neurons. Focused ultrasound combined with systemically circulating microbubbles (FUS/MB) is an emerging modality capable of site-specific molecular delivery temporarily and noninvasively within a range of appropriate parameters. Objective: To investigate the effect of FUS/MB–enhanced delivery of therapeutics to the motor cortex on the disease progression by using a transgenic mouse model of ALS. Methods: Multiple FUS/MB–enhanced deliveries of Edaravone (Eda) to the motor cortex were performed on the SOD1G93A mouse model of ALS. The motor function of the animals was evaluated by gait analysis, grip strength and wire hanging tests. Corticospinal and spinal motor neuronal health, misfolded SOD1 protein and neuroinflammation after treatments were evaluated by histological examination. Results: Ultrasound–enhanced delivery of Eda in the targeted motor cortex was achieved by a two-fold increase without gross tissue damage. Compared with the ALS mice administered Eda treatments only, the animals given additionally FUS/MB–enhanced brain delivery of Eda (FUS/MB + Eda) exhibited further improvements in neuromuscular functions characterized by gait patterns, muscular strength, and motor coordination along with rescued muscle atrophy. FUS/MB + Eda treatments conferred remarkable neuroprotection to both upper and lower motor neurons revealed by normalized neuronal morphology with increasing cell body size and profoundly alleviated neuroinflammation and misfolded SOD1 protein in the brains and lumbar spinal cords. Conclusion: We report a pilot study that non-invasive ultrasound–enhanced brain delivery of Eda provides additive amelioration on disease progression of ALS and suggest that broadening the target from spinal to cortical network functions using the FUS/MB–enhanced delivery can be a rational therapeutic strategy of this debilitating disorder

Effect of Temperature and Microwave Power Levels on Microwave Drying Kinetics of Zhaotong Lignite

Microwave drying is a promising and effective way to drying and upgrading lignite. The influence of temperature (100⁻140 °C) and microwave power levels (500⁻800 W) on thin-layer drying characteristics of Zhaotong lignite under microwave irradiation were investigated. Fourteen thin-layer drying models were used to analyze the microwave drying process while six thin-layer drying models were used to analyze the hot-air drying process. The microwave drying processes at all temperature (100⁻140 °C) or low microwave power levels (500⁻700 W) exhibited four periods: a warm-up period, a short constant period, the first and second falling rate period, while one falling rate period was found during hot-air drying. The effective diffusion coefficient of lignite were calculated and it increases with increasing temperature and microwave power levels. During microwave drying, the two-term exponential model is the most suitable model for all applied conditions, while the Modified Page model is the most suitable model to describe the hot-air drying experiments. The apparent activation energy were determined from Arrhenius equation and the values for the first and second falling rate period are 3.349 and 20.808 kJ·mol−1 at different temperatures, while they are 13.455 and 19.580 W·g−1 at different microwave power levels. This implies the apparent activation energy is higher during the second falling rate period, which suggest that the dewatering of absorbed water is more difficult than capillary water. The value of apparent activation energy in hot-air drying is between the first and second falling rate period of microwave drying. Results indicate that microwave drying is more suitable to dewatering free water and capillary water of lignite

VASOCONSTRICTIVE EFFECT OF XINMAILONG IN RAT AORTA

Background: Cockroach has been utilized traditionally in China for the therapy of cardiovascular disorders, such as heart failure. The present study was aimed to assess the vasoconstrictive effect of Xinmailong Injection (XML), a bioactive composite from American cockroach. Methodology: The isometric tensions of rat aortic rings were measured after acutely treated with XML. Meanwhile, the systemic blood pressures (SBPs) were recorded and the levels of the endothelium-derived cytokines in blood samples were detected after rats were administered with XML for 3 days. Protein expression for the L-type Ca2+ channels (Cav1.2) was also determined in rat thoracic aorta. Results: XML induced vasoconstrictions in rat aortic rings with or without endothelium. In addition, the vasoconstrictions due to extracellular Ca2+ influx and intracellular Ca2+ release were also elevated by XML. After treatment with XML for 3 days, the levels of prostacyclin (PGI2) were markedly elevated whereas the levels of nitric oxide (NO) and endothelin-1 (ET-1) were not significantly changed in rats. Furthermore, expression of the Cav1.2 protein was significantly enhanced in aorta but the SBPs of rats were not influenced. Conclusion: XML plays an important role in regulating vascular tone. The increases of the extracellular Ca2+ influx and the intracellular Ca2+ release may contribute to the vasoconstriction induced by XML. Our findings pave the ways to better understand the therapeutic effects of XML on cardiovascular system

On-line microscopic imaging investigation on oil charging characteristics in tight reservoirs

The reservoir space of tight reservoir with low-permeability is controlled by micro and nano scale pores, making the influence of capillary force significantly enhanced. Therefore, understanding the microscopic charging characteristics of oil and gas is the basis for analyzing the migration and accumulation of reservoirs. In this paper, the self-developed on-line three-dimensional microscopic imaging system for core fluid displacement is used to observe the oil charging process of two tight reservoir samples, and core-level and pore-level quantitative analysis methods for oil content characteristics are proposed. Taking the on-line nuclear magnetic resonance testing with the same process of displacement as a contrast, it is revealed that the average difference of on-line 2D DR (Digital Radiography) images at different times can be used to evaluate the overall oil content change of the sample. The calculation method of pore level fluid saturation based on high-precision pore network extraction algorithm realizes the quantitative evaluation of oil charging degree of the CT resolved pores and pore throats. The combination of multi-level data and different methods can meet the different needs of different researches on dynamic feature capture, pore resolution and imaging field of vision. The analysis results show that the oil saturation of two rock samples from different tight reservoirs in the Ordos Basin increases rapidly at the beginning and slows down later with oil injection increasing. At the same injection flow rate, the oil saturation of the sample with higher permeability increases faster at the initial oil charging stage, making its final oil saturation higher. With the increase of oil injection, the oil saturation of macropores in the sample with higher permeability continuously increases, while that of macropores in the sample with lower permeability shows a U-shaped change, showing the characte-ristics of repeated occupation of pores by oil and water

Global DNA Methylation and mRNA-miRNA Variations Activated by Heat Shock Boost Early Microspore Embryogenesis in Cabbage (Brassica oleracea)

Microspore culture, a type of haploid breeding, is extensively used in the cultivation of cruciferous crops such as cabbage. Heat shock (HS) treatment is essential to improve the embryo rate during the culture process; however, its molecular role in boosting early microspore embryogenesis (ME) remains unknown. Here we combined DNA methylation levels, miRNAs, and transcriptome profiles in isolated microspores of cabbage ‘01-88’ under HS (32 °C for 24 h) and normal temperature (25 °C for 24 h) to investigate the regulatory roles of DNA methylation and miRNA in early ME. Global methylation levels were significantly different in the two pre-treatments, and 508 differentially methylated regions (DMRs) were identified; 59.92% of DMRs were correlated with transcripts, and 39.43% of miRNA locus were associated with methylation levels. Significantly, the association analysis revealed that 31 differentially expressed genes (DEGs) were targeted by methylation and miRNA and were mainly involved in the reactive oxygen species (ROS) response and abscisic acid (ABA) signaling, indicating that HS induced DNA methylation, and miRNA might affect ME by influencing ROS and ABA. This study revealed that DNA methylation and miRNA interfered with ME by modulating key genes and pathways, which could broaden our understanding of the molecular regulation of ME induced by HS pre-treatment