Unraveling the weak hydrogen bonds of ethynylpyridines and ethynylbenzene with trimethylphosphate - A combined FT-Raman spectroscopic and quantum-chemical study

The interplay of secondary hydrogen bonds of 2- and 3-ethynylpyridine or ethynylbenzene with trimethylphosphate in tetrachloroethene was elucidated using FT-Raman spectroscopy and MP2/6-311 + G(d,p) calculations. The direct participation of C C moiety in the complex formation was demonstrated by the change in the shape of the C C stretching band and further characterized in terms of vibrational dephasing of C C stretching. With this aim, the complex band pattern in frequency domain was decomposed using analytical function, introduced by Egelstaff and Schofield and further disseminated by Kirillov, with analytical counterpart in the time domain. The amplitude of frequency fluctuations (M-2), frequency modulation time (T-omega) and vibrational dephasing time (T-v) were determined for both unassociated (C C) and associated (C C center dot center dot center dot) ethynyl moieties of 2- and 3-ethynylpyridine and ethynylbenzene. The differences in the dynamical parameters indicate broader distribution of the frequency fluctuations for C C center dot center dot center dot moiety (M-2 similar to 1-2 ps(-2)) than for C C moiety (M-2 approximate to 0.5 ps(-2)), while the average time between perturbative events, as well as the time needed for the phase being completely lost, were shorter for C C center dot center dot center dot (T-omega similar to 0.2-0.7 ps, T-nu approximate to 1ps) than for C C moiety (T-omega similar to.4-1.7 ps, T-v approximate to ps). The shorter T-omega, for moiety of 2-ethynylpyridine (T-omega approximate to .23 ps), in comparison with analogous quantity of 3-ethynylpyridine and ethynylbenzene (T-omega approximate to 0.6 and 0.68 ps), is attributed to more frequent hindering of the C C center dot center dot center dot HCH2 hydrogen bond by spatially close N-atom which competes for H-atom of CH3 group thus making the N center dot center dot center dot HCH2 hydrogen bond, as predicted by MP2 calculations. Additionally, a hydrogen bond between ortho H-atom of 3-ethynylpyridine and P-O(CH3) group of trimethylphosphate is suggested from experimental FT-Raman spectra as well and also computationally verified. (C) 2016 Elsevier B.V. All rights reserved

Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

© 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 licenseBackground: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit