The interplay between solute-solvent and solventsolvent interactions plays an essential role in solvation dynamics that has important effects on the mechanism and dynamics of chemical reactions in solution. In this study, the rearrangement of the hydration shell induced by photoionization of a solute molecule is probed in a state-and isomer-specific manner by resonant multiphoton ionization detected IR spectroscopy of the prototypical 4-aminobenzonitrileÀ (H 2 O) 2 cluster produced in a molecular beam. IR spectra reveal that the water molecules form a cyclic solvent network around the CN group in the initial neutral state (S 0 ). Different from the singly-hydrated cluster, in which either the CN or the NH 2 group is hydrated, hydration of the NH 2 group is not observed in the dihydrated cluster. IR spectra obtained after ionizing the solute molecule into the cation ground state (D 0 ) exhibit features ascribed to both NHbound and CN-bound isomers, indicating that water molecules migrate from the CN to the NH site upon ionization with a yield depending on the ionization excess energy.Analysis of the IR spectra as a function of the excess energy shows that migration produces two different NH 2 solvated structures, namely (i) the most stable structure in which both NÀ H bonds are singly hydrated and (ii) the second most stable isomer in which one of the NÀ H bonds is hydrated by a H-bonded (H 2 O) 2 dimer. The product branching ratio of the two isomers depends on the excess energy. The role of the water-water interaction in the hydration rearrangement is discussed based on the potential energy landscape. Solvation dynamics plays an important role in reaction mechanisms in the condensed phase, where not only solute-solvent solvation but also solvent-solvent interactions have a significant influence on the dynamics. Thus, the investigation of solvation dynamics at the molecular level substantially contributes to our understanding of the reaction mechanism. In this study, the dihydrated cluster of 4ABN was utilized as a model for the first solvation layer to elucidate solvent motions induced by ionization of the solute and the role of WÀ W interactions for the solvent relaxation.
Background: Rocuronium consumption with or without intraoperative objective neuromuscular monitoring in clinical settings of unrestricted use of sugammadex and neuromuscular monitoring has not been reported. The aim of the study was to investigate the association between the use of intraoperative objective neuromuscular monitoring and rocuronium consumption in patients undergoing laparoscopic abdominal surgery.Methods: Data were collected by reviewing electronic medical records of patients who received laparoscopic abdominal surgery under general anesthesia with rocuronium and reversal with sugammadex at Asahikawa Medical University Hospital between May 2017 and April 2018. Multiple linear regression model was developed to compare the amount of rocuronium consumption per weight per hour (mg/kg/h) between the group in which intraoperative objective neuromuscular monitoring was used (NM+ group) and the group in which intraoperative neuromuscular monitoring was not used (NM- group). Additionally, we performed an interaction test with reference to the results of the subgroup analysis.Results: A total of 429 patients were evaluated, with 371 patients (86%) included in NM+ group and 58 patients (14%) in NM- group. In the NM+ group, 94% of the patients received additional rocuronium after reappearance of TOF response while 6% of the patients received additional rocuronium before reappearance of TOF in order to maintain post-tetanic count. Log-transformed rocuronium consumption between NM+ group and NM- group was not significantly different (back-transformed β-coefficients [95%CI]: 1.054 [0.946–1.174]; P=0.34). Male sex and body mass index (BMI) were independent factors associated with 15% (0.854 [0.789–0.925]; P<0.001) and 3% (for every 1 kg/m2 increase in BMI) (0.970 [0.962–0.979]; P<0.001) decrease in intraoperative rocuronium consumption, respectively. A significant interaction was detected between the use of neuromuscular monitoring and age≥65 (β: 0.843 [0.759–0.936]; P=0.001).Conclusions: This single center retrospective study demonstrated that although the use of intraoperative objective neuromuscular monitoring was not an individual factor influencing intraoperative rocuronium consumption, the use of intraoperative neuromuscular monitoring reduced rocuronium consumption by approximately 15% during laparoscopic abdominal surgery in elderly patients.
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