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Carbon fiber reinforced silicon carbide matrix composites (Cf/SiC composites) are lightweight, high strength, wear-resistant, and heat-resistant, making them widely used in aerospace and other industries. However, machining holes in Cf/SiC composites is a great challenge due to the anisotropy and high hardness of the material. In this paper, a brazed diamond grinding rod was employed to grind 1 mm diameter holes in Cf/SiC composites, and the influence of grinding parameters on grinding force, hole entrance/exit defects, and hole wall quality was investigated. In addition, the material removal mechanism of Cf/SiC composites and the wear mechanism of the diamond grinding rod were explored. The findings showed that the damage at the hole entrance and exit predominantly manifests as tearing and burring. The damage factor at the hole exit is 3.5% larger than that at the hole entrance, and the damage factor at both the hole entrance and exit reduces with the growth of spindle speed and the decrease of feed rate. In addition, the diameter errors of the hole entrances and exits are all less than 10%, and the entrance diameter is 2.9% larger than the exit. The hole wall defects include fiber fracture, silicon carbide matrix peeling, and inherent porosity, with poorer surface quality at fiber orientation angles (FOA) of 90° to 180°. The main wear mechanisms were identified as abrasive wear and the spalling of abrasive grains. [ABSTRACT FROM AUTHOR]

This study was designed to explore the expression changes of P2Y1 receptors in the distal colonic myenteric layer of rats. An opioid induced constipation(OIC) rat model was generated by intraperitoneal (i.p) injection of loperamide. At 7 days post-treatment, the model rats were assessed by calculating the fecal water content and the gastrointestinal transit ratio. The immunofluorescence (IF)-based histochemical study was used to observe the distribution of P2Y1 receptors in the distal colonic myenteric plexus. Western blotting (WB) was performed to evaluate the expression changes of P2Y1 proteins in the myenteric layer, and the electrophysiological approaches were carried out to determine the regulatory roles of P2Y1 receptors on distal colonic motor function. IF showed that P2Y1 receptors are co-expressed MOR in the enteric nerve cells of the distal colonic myenteric plexus. Moreover, the WB revealed that the protein levels of P2Y1 were significantly decreased in the distal colonic myenteric layer of OIC rats. In vitro tension experiments exhibited that the P2Y1 receptor antagonist MRS2500 enhanced the spontaneous contraction amplitude, adding EM2 and β-FNA did not have any effect on MRS2500. Therefore, P2Y1 receptor expression could be associated with the occurrence of OIC in this rat model and the regulation of colonic motility by MOR may be related to the release of purine neurotransmitters such as ATP in the colonic nervous system. [ABSTRACT FROM AUTHOR]

Introduction: Early oral feeding (EOF) has been shown to improve postoperative recovery for many surgeries. However, surgeons are still skeptical about EOF after gastric cancer surgery due to possible side effects. This updated systematic review and meta-analysis aimed to investigate the efficacy and safety of EOF in patients after gastric cancer surgery., Methods: Randomized controlled trials (RCTs) investigating EOF in patients after gastric cancer surgery were searched in the databases of PubMed, Embase, Clinicaltrials.gov, and Cochrane from 2005 to 2023, and an updated meta-analysis was performed using RevMan 5.4 software., Results: The results of 11 RCTs involving 1,352 patients were included and scrutinized in this analysis. Hospital days [weighted mean difference (WMD), -1.72; 95% confidence interval (CI), -2.14 to -1.30; p<0.00001), the time to first flatus (WMD, -0.72; 95% CI, -0.99 to -0.46; p<0.00001), and hospital costs (WMD, -3.78; 95% CI, -4.50 to -3.05; p<0.00001) were significantly decreased in the EOF group. Oral feeding tolerance [risk ratio (RR), 1.00; 95% CI, 0.95-1.04; p=0.85), readmission rates (RR, 1.28; 95% CI, 0.50-3.28; p=0.61), postoperative complications (RR, 1.02; 95% CI, 0.81-1.29; p=0.84), anastomotic leakage (RR, 0.83; 95% CI, 0.25-2.78; p=0.76), and pulmonary infection (RR, 0.65; 95% CI, 0.31-1.39; p=0.27) were not significantly statistical between two groups., Conclusion: This meta-analysis reveals that EOF could reduce hospital days, the time to first flatus, and hospital costs, but it was not associated with oral feeding tolerance, readmission rates, or postoperative complications especially anastomotic leakage and pulmonary infection, regardless of whether laparoscopic or open surgery, partial or total gastrectomy, or the timing of EOF initiation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Xu, Li, Liu, Wang and Dou.)

This study was designed to explore the expression changes of P2Y 1 receptors in the distal colonic myenteric layer of rats. An opioid induced constipation(OIC) rat model was generated by intraperitoneal (i.p) injection of loperamide. At 7 days post-treatment, the model rats were assessed by calculating the fecal water content and the gastrointestinal transit ratio. The immunofluorescence (IF)-based histochemical study was used to observe the distribution of P2Y 1 receptors in the distal colonic myenteric plexus. Western blotting (WB) was performed to evaluate the expression changes of P2Y 1 proteins in the myenteric layer, and the electrophysiological approaches were carried out to determine the regulatory roles of P2Y 1 receptors on distal colonic motor function. IF showed that P2Y 1 receptors are co-expressed MOR in the enteric nerve cells of the distal colonic myenteric plexus. Moreover, the WB revealed that the protein levels of P2Y 1 were significantly decreased in the distal colonic myenteric layer of OIC rats. In vitro tension experiments exhibited that the P2Y 1 receptor antagonist MRS2500 enhanced the spontaneous contraction amplitude, adding EM2 and β-FNA did not have any effect on MRS2500. Therefore, P2Y 1 receptor expression could be associated with the occurrence of OIC in this rat model and the regulation of colonic motility by MOR may be related to the release of purine neurotransmitters such as ATP in the colonic nervous system., (© 2024. The Author(s).)