The Poisson-Boltzmann model for implicit solvation of electrolyte solutions: Quantum chemical implementation and assessment via Sechenov coefficients.

We present the theory and implementation of a Poisson-Boltzmann implicit solvation model for electrolyte solutions. This model can be combined with arbitrary electronic structure methods that provide an accurate charge density of the solute. A hierarchy of approximations for this model includes a linear approximation for weak electrostatic potentials, finite size of the mobile electrolyte ions, and a Stern-layer correction. Recasting the Poisson-Boltzmann equations into Euler-Lagrange equations then significantly simplifies the derivation of the free energy of solvation for these approximate models. The parameters of the model are either fit directly to experimental observables-e.g., the finite ion size-or optimized for agreement with experimental results. Experimental data for this optimization are available in the form of Sechenov coefficients that describe the linear dependence of the salting-out effect of solutes with respect to the electrolyte concentration. In the final part, we rationalize the qualitative disagreement of the finite ion size modification to the Poisson-Boltzmann model with experimental observations by taking into account the electrolyte concentration dependence of the Stern layer. A route toward a revised model that captures the experimental observations while including the finite ion size effects is then outlined. This implementation paves the way for the study of electrochemical and electrocatalytic processes of molecules and cluster models with accurate electronic structure methods

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

Selected Physiological and Psychological Work

607 hal.; 22 c

Variant anatomy of the left gastric vein

Introduction: Investigation of the venous vessels of the gastroesophageal transition is an actual problem in the surgery of the portal hypertension, and the basic knowledge of anatomical variants of the left gastric vein, as the main porto-caval anastomosis in the celiac region, is essentially important, because bleeding from the gastric varices accounts for 20-30% of all bleedings from varices and it is hard to stop this bleeding through endoscopy. Materials and methods: From 2008 to 2011 year 90 gastro-intestinal complexes of corpses of adult people, both sexes, who had no gastroenterological diseases, were dissected and the celiac venous vessels were investigated by means of X-ray. At the end of our practical part the investigated information was processed statistically. Results: In 89(98,9%) of 90 cases the left gastric vein (LGV) was found as an isolated vessel. In 1 case (1,11%) the LGV was a type of anatomical variant. Its gastric branch anastomosed with the right gastric vein along the lesser curvature of the stomach. The esophageal branch went up to the esophagus, along the posterior wall of the stomach. During the dissection instead of a unique trunk of the LGV we found 3 small venous vessels in diameter of 2-3 mm, which ran into the portal vein. These vessels ran from the gastric and esophageal branches down to the celiac trunk and formed a plexus around the celiac trunk. We also investigated the relationship between the LGV and other veins of portal system in other 89 cases. In 50 cases the LGV had a duplicative course with the left gastric artery (LGA) and ran into the portal vein (41 cases, 82%) or into the angle of merge of splenic and inferior mesenteric vein (6 cases, 12%), or into the splenic vein (3 cases, 6%). In 39 of 89 cases (43,82%) the LGV was running separately from the LGA, crossing a common hepatic artery (23 of 89cases, 25,84%) or a splenic artery (16 of 89 cases, 17,98%). In both of these variants the LGV ran into the portal or splenic vein. Conclusion: In 1,11% of all investigated cases we haven’t found the unique trunk of the left gastric vein, which takes place in forming the very serious porto-caval anastomosis during the portal hypertension. Existing of such anatomical variants can provide not only very dangerous in diagnosis and prognosis gastro-duodenal bleeding, but also may cause technical problems during the hemostasis