RESUMEN
Magnesium phosphate cement (MPC) is a high-performance repairing material suitable for the interfacial disease of slab track. In this study, the early properties of MPC were optimized using central composite design (CCD) approach based on response surface methodology (RSM). Three factors with five levels and three responses were considered. The significance of the factors and their interactions were verified by using analysis of variance (ANOVA). The result show that the mass ratio of water-to-binder (W/b) affects fluidity, while the mass ratio of magnesia-to-phosphate (M/P) and borax-to-magnesia (B/M) impact the setting time of MPC. Higher W/b results in higher fluidity, while an increase in M/P reduces the setting time by increasing the neutralization reaction. Borax addition retards the reaction, prolonging the setting time. The three factors significantly affect the early compressive strength of MPC. At M/P = 3.5, the interweaving of MgO and K-struvite (MKP) forms a dense network structure, enhancing the strength. Borax and W/b interact to affect compressive strength, with borax retarding MKP crystal growth and higher W/b reducing compactness. Combined with microscopic property test, the strength generation mechanism of MPC with optimized mixing ratio was revealed, And the feasibility of field application of MPC was verified by strength test.
RESUMEN
OBJECTIVE: To verify the feasibility of electroacupuncture analgesia applied to gynecologic outpatient operation. METHODS: Two hundred patients were randomly divided into an electroacupuncture analgesia group and an intravenous anesthesia group, 100 cases in each group. Operation types included artificial abortion, diagnostic curettage and remove of intrauterine divice. The electroacupuncture analgesia group was treated with electroacupuncture at bilateral Hegu (LI 4) and Neiguan (PC 6), and the routine gynecologic outpatient operation was performed under patients' waking state. The intravenous anesthesia group was treated with routine gynecologic outpatient operation after intravenous injection of fentanyl and propofol. RESULTS: The excellent rate and the effective rate of analgesia were 88.0% (88/100) and 100.0% (100/100) in the electroacupuncture analgesia group, and 94.0% (94/100) and 100.0% (100/100) in the intravenous anesthesia group, with no statistically significant differences between the two groups (all P > 0.05). There was no adverse reaction in the electroacupuncture anesthesia group, but 11 cases of adverse reactions in the intravenous anesthesia group. CONCLUSION: Electroacupuncture analgesia can effectively alleviate the pain during gynecologic outpatient operation and it is simple and safe without adverse reactions.
