Endoscopic Nasobiliary Drainage Comparable with Endoscopic Biliary Stenting as a Preoperative Drainage Method for Malignant Hilar Biliary Obstruction : A Multicenter Retrospective Study

Introduction: Preoperative endoscopic biliary drainage (PEBD) for malignant hilar biliary obstruction (MHBO) is widely accepted. Recent PEBD consists of endoscopic nasobiliary drainage (ENBD), conventional endoscopic biliary stenting (CEBS) with plastic stents across the papilla, and endoscopic biliary inside stenting (EBIS) with plastic stents above the papilla, while ENBD is the primary procedure in Asian countries. Thus, we aimed to compare the efficacy of ENBD with those of CEBS and EBIS as a means of PEBD for MHBO. Methods: We retrospectively identified patients with MHBO who underwent upfront surgery between January 2011 and December 2018 in a multicenter setting. The outcome measures were cumulative dysfunction of PEBD, risk factors for PEBD dysfunction, and adverse events. Results: We analyzed a total of 219 patients, comprising 163 males (74.4%); mean age, 69.7 (+/- 7.6) years; Bismuth-Corlette (BC) classification I, II, IIIa, IIIb, and IV in 68, 49, 43, 30, and 29 patients, respectively; and diagnosis of hilar cholangiocarcinoma and gallbladder cancer in 188 and 31 patients, respectively. PEBD procedures were performed in 160 patients with ENBD, 31 patients with CEBS, and 28 patients with EBIS. PEBD dysfunction occurred in 58 patients (26.5%), and the cumulative dysfunction rates were not significantly different among PEBD methods (p = 0.60). Multivariate analysis showed that BC-IV was significantly associated with the occurrence of PEBD dysfunction (hazard ratio = 2.10, p = 0.02). The adverse event rates were not significantly different among PEBD groups (p = 0.70). Conclusion: ENBD as a means of PEBD for MHBO is comparable with CEBS and EBIS in rates of dysfunction and adverse events

A Computational Chemistry Study on Friction of h-MoS2. Part I. Mechanism of Single Sheet Lubrication

International audienceIn this work, we theoretically investigated the friction mechanism of hexagonal MoS2 (a well-known lamellar compound) using a computational chemistry method. First, we determined several parameters for molecular dynamics simulations via accurate quantum chemistry calculations and MoS2 and MoS2-xOx structures were successfully reproduced. We also show that the simulated Raman spectrum and peak shift on X-ray diffraction patterns were in good agreement with those of experiment. The atomic interactions between MoS2 sheets were studied by using a hybrid quantum chemical/classical molecular dynamics method. We found that the predominant interaction between two sulfur layers in different MoS2 sheets was Coulombic repulsion, which directly affects the MoS2 lubrication. MoS2 sheets adsorbed on a nascent iron substrate reduced friction further due to much larger Coulombic repulsive interactions. Friction for the oxygen-containing MoS2 sheets was influenced by not only the Coulomb repulsive interaction but also the atomic-scale roughness of the MoS2/MoS2 sliding interface