Structure of dicarbonylbis-(μ-3,5-dimethylpyrazolyl)-bis(4-tolyl diphenylphosphinite)diiridium(I)–dichloromethane (1/1)

In bis(μ-3,5-dimethylpyrazolyl-N:N')-bis[carbonyl( 4-tolyl diphenylphosphinite-P)iridium(I)] dichloromethane solvate, two Ir^I atoms are joined by two 3,5-dimethylpyrazolyl bridges with one carbonyl and one 4-tolyl diphenylphosphinite ligand completing the square-planar geometry about each Ir atom. The Ir· · ·Ir distance of 3.307 (1) Å is greater than the distance of 3.22 Å found in a similar pyrazolyl-bridged iridium(I) dimer [Fox (1989). PhD dissertation, California Institute of Technology, USA]

Secondary structure in lung surfactant SP-B peptides: IR and CD studies of bulk and monolayer phases

AbstractPulmonary surfactant protein SP-B is known to facilitate adsorption and spreading of surfactant components across the air/water interface. This property appears essential for in vivo function in the alveolar subphase and at the air/alveolar surface. Three peptides with amino acid sequences based on SP-B containing predicted α-helical regions (SP-B1-20, SP-B9-36A, SP-B40-60A) have been synthesized to probe structure-function relationships and protein-lipid interaction in bulk phase and monolayer environments. IR and CD studies are reported along with traditional surface pressure-molecular area (π-A) isotherms and IR reflection-absorption spectroscopy (IRRAS) investigations conducted at the air/water interface. In bulk phase, helix-promoting environments (methanol and aqueous dispersions of lipid vesicles), SP-B1-20 and SP-B9-36A contained significant amounts of α-helical structure, whereas varying degrees of α-helix, random coil, and β-sheet were observed in aqueous solutions and monolayers. The most striking behavior was observed for SP-B9-36A, which displayed reversible surface pressure-induced β-sheet formation. Bulk phase lipid melting curves and monolayer experiments with peptide-lipid mixtures showed subtle differences in the degree of bulk phase interaction and substantial differences in peptide surface activity. The uniqueness of IRRAS is emphasized as the importance of evaluating secondary structure in both bulk phase and monolayer environments for lung surfactant peptide mimics is demonstrated

Photoinduced Electron Transfer in Iridium(spacer)pyridinium Complexes

Photoinduced electron-transfer (ET) reactions in a series of iridium(spacer)pyridinium complexes, [Ir(µ-pz*)-(CO)Ph_2POC_6H_4(CH_2)_n-A^+]_2 (pz* = 3,5-dimethylpyrazolyI; Ph = C_6H_5; C_6H_4 = phenylene; A^+ = pyridinium (py^+) or substituted py^+; n = 0-3), have been studied in acetonitrile solution at room temperature. The rates of singlet (^1Irz* → A^+: ^1ET) reactions were determined for each complex, and for n = 1 and 2 species, the rates of thermal charge recombination (ET^b) also were measured. The ET rates for the n = 1 system display a Gaussian free-energy dependence ( λ = 1.0 eV, H_(AB) = 5 cm^(-1)). With one exception, maximum ET rates exhibit an exponential dependence upon the number of carbon atoms (α_c) in the spacer. The exception is the n = 1 (α_c = 5) system; k_(max) is almost a factor of 100 slower than predicted by the exponential dependence on α_c, indicating that donor-acceptor electronic coupling through a single methylene link is unusually weak

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020