Inhomogeneity of bulk nanoporous silver fabricated via dealloying Ag-Zn alloy in sulphuric acid

Micro & nano letters

article

Zhiqiang Li¹  Lu Bai¹  Xing Lu¹ 

[1] Liaoning Key Materials Laboratory for Railway, School of Materials Science and Engineering, Dalian Jiaotong University

关键词: cracks;    electrolytes;    nanofabrication;    nanoporous materials;    porosity;    silver;    solid-state phase transformations;    solidification;    stacking faults;    surface diffusion;    surface morphology;    twinning;    bulk nanoporous silver;    dealloying;    sulfuric acid;    crystal structure;    close-packed hexagonal-face-centred cubic phase transition;    inhomogeneous morphology;    coarsening;    surface diffusion;    electrolyte;    parallel orientation structures;    cracks;    solidification;    lattice defects;    stacking faults;    lattice distortions;    twinning;    size 12 mm;    size 5.4 mm;    time 100 h;    temperature 293 K to 298 K;    voltage 0.4 V;    Ag;   

DOI  :  10.1049/mnl.2013.0567

学科分类：计算机科学（综合）

来源: Wiley

【 摘 要 】

Introduction: Anesthesia induced during a surgical intervention, the duration of the surgical intervention, and the surgical intervention itself tend to affect immune functions, resulting in the formation of free radicals in the metabolism. Free radicals can cause postoperative disorders by targeting biomolecules in the cell, such as lipids, carbohydrates, proteins, and DNA. In the present study, we used remifentanil or esmolol to induce a controlled hypotension in patients who were undergoing septorhinoplasty under general anesthesia, and we planned to compare the effect of these agents on hemodynamics and oxidative stress relative to the control group. Methodology: A total of 75 patients aged between 18 and 65 y, ASA I-II, planned to undergo elective septorhinoplasty, were included in this study. Patients were randomly divided into the following three groups: Group R (remifentanil group, n = 25); Group E (esmolol group, n = 25); and Group C (control, n = 25). Anesthesia was induced with 2 mg/kg propofol 2 mg/kg, fentanyl 1 µg/kg, and rocuronium 0.6 mg/kg. Immediately after induction, Group R was started loading dose of remifentanil 1 µg/kg/min, followed by infusion at 0.25–0.50 µg/kg/min. In Group E, a loading dose of esmolol 500 µg/kg was given for 1 min, then infusion was continued @ 150–300 µg/kg. A targeted mean arterial pressure (MAP) of 55–65 mmHg was aimed. In Group C, remifentanil was infused at 0.1–0.2 µg/kg/min until a MAP of 70–100 mmHg was reached. During operation; systolic (SAP), diastolic (DAP) and mean arterial pressure (MAP), heart rate (HR), peripheral oxygen saturation (SpO2), EtCO2 (end tidal CO2) were recorded before induction, after induction, after intubation, at 5-min intervals during the first 30 min, and then at 10-min intervals during the intervention. The amounts of remifentanil and esmolol consumed by the patients during the operation were calculated and recorded. Blood samples that were taken twice, preoperatively and postoperatively, for malondialdehyde (MDA), superoxide dismutase (SOD), total oxidant level (TOL), total antioxidant level (TAL), and oxidative stress index (OSI). Results: MAP showed a greater decrease starting from the 25th min and 40th min after intubation in remifentanil group and esmolol group respectively, compared to the control group. In the remifentanil and control groups, there was a statistically significant decrease in the postoperative OSI levels compared to the preoperative levels. One the other hand, in the esmolol group, there was no statistically significant difference between the preoperative and postoperative median OSI levels. There was a significant increase in the postoperative TAL of the remifentanil group compared to the preoperative level. Conclusion: It was observed that during a hypotensive anesthesia induced by remifentanil or esmolol, remifentanil ensured more stable operating conditions in terms of hemodynamics compared with esmolol, and that remifentanil was also superior to esmolol in reducing oxidative stress.

【 授权许可】

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