A minisandwich experiment with blended ca-bentonite and pearson water—Hydration, swelling, solute transport and cation exchange

Shaft seals are geotechnical barriers in nuclear waste deposits and underground mines. The Sandwich sealing system consists of alternating sealing segments (DS) of bentonite and equipotential segments (ES). MiniSandwich experiments were performed with blended Ca-bentonite (90 mm diameter and 125 mm height) to study hydration, swelling, solute transport and cation exchange during hydration with A3 Pearson water, which resembles pore water of Opalinus Clay Formation at sandy facies. Two experiments were run in parallel with DS installed either in one-layer hydrate state (1W) or in air-dry two-layer hydrate (2W) state. Breakthrough at 0.3 MPa injection pressure occurred after 20 days and the fluid inlet was closed after 543 days, where 4289 mL and 2984 mL, respectively, passed both cells. Final hydraulic permeability was 2.0–2.7 × 10$^{-17}$ m$^{2}$. Cells were kept for another 142 days before dismantling. Swelling of DS resulted in slight compaction of ES. No changes in the mineralogy of the DS and ES material despite precipitated halite and sulfates occurred. Overall cation exchange capacity of the DS does not change, maintaining an overall value of 72 ± 2 cmol(+)/kg. Exchangeable Na$^{+}$ strongly increased while exchangeable Ca$^{2+}$ decreased. Exchangeable Mg$^{2+}$ and K$^{+}$ remained nearly constant. Sodium concentration in the outflow indicated two different exchange processes while the concentration of calcium and magnesium decreased potentially. Concentration of sulfate increased in the outflow, until it reached a constant value and chloride concentration decreased to a minimum before it slightly increased to a constant value. The available data set will be used to adapt numerical models for a mechanism-based description of the observed physical and geochemical processes

ASpecD: A Modular Framework for the Analysis of Spectroscopic Data Focussing on Reproducibility and Good Scientific Practice

Reproducibility is at the heart of science. However, most published results usually lack the information necessary to be independently reproduced. Even more, most authors will not be able to reproduce the results from a few years ago due to lacking a gap-less record of every processing and analysis step including all parameters involved. There is only one way to overcome this problem: developing robust tools for data analysis that, while maintaining a maximum of flexibility in their application, allow the user to perform advanced processing steps in a scientifically sound way. At the same time, the only viable approach for reproducible and traceable analysis is to relieve the user of the responsibility for logging all processing steps and their parameters. This can only be achieved by using a system that takes care of these crucial though often neglected tasks. Here, we present a solution to this problem: a framework for the analysis of spectroscopic data (ASpecD) written in the Python programming language that can be used without any actual programming needed. This framework is made available open-source and free of charge and focusses on usability, small footprint and modularity while ensuring reproducibility and good scientific practice. Furthermore, we present a set of best practices and design rules for scientific software development and data analysis. Together, this empowers scientists to focus on their research minimising the need to implement complex software tools while ensuring full reproducibility. We anticipate this to have a major impact on reproducibility and good scientific practice, as we raise the awareness of their importance, summarise proven best practices and present a working user-friendly software solution

Anisotropy in shale from Mont Terri

Anisotropy of shales is the subject of this report, and we use an example of the Jurassic Opalinus Clay from Mont Terri (Switzerland) that is being investigated in the context of radioactive waste disposal. The study is targeted at the geomechanical characterization of shale by laboratory testing. The overall aim is to improve the constitutive material laws and their application in numerical models

Results of endoscopic vacuum-assisted closure device for treatment of upper GI leaks

Esophageal perforations and postoperative leakage of esophagogastrostomies are considered to be life-threatening conditions due to the potential development of mediastinitis and consecutive sepsis. Vacuum-assisted closure (VAC) techniques, a well-established treatment method for superficial infected wounds, are based on a negative pressure applied to the wound via a vacuum-sealed sponge. Endoluminal VAC (E-VAC) therapy as a treatment for GI leakages in the rectum was introduced in 2008. E-VAC therapy is a novel method, and experience regarding esophageal applications is limited. In this retrospective study, the experience of a high-volume center for upper GI surgery with E-VAC therapy in patients with leaks of the upper GI tract is summarized. To our knowledge, this series presents the largest patient cohort worldwide in a single-center study. Between October 2010 and January 2017, 77 patients with defects in the upper gastrointestinal tract were treated using the E-VAC application. Six patients had a spontaneous perforation, 12 patients an iatrogenic injury, and 59 patients a postoperative leakage in the upper gastrointestinal tract. Complete restoration of the esophageal defect was achieved in 60 of 77 patients. The average duration of application was 11.0 days, and a median of 2.75 E-VAC systems were used. For 21 of the 77 patients, E-VAC therapy was combined with the placement of self-expanding metal stents. This study demonstrates that E-VAC therapy provides an additional treatment option for esophageal wall defects. Esophageal defects and mediastinal abscesses can be treated with E-VAC therapy where endoscopic stenting may not be possible. A prospective multi-center study has to be directed to bring evidence to the superiority of E-VAC therapy for patients suffering from upper GI defects

Clay in natural and engineered barriers for radioactive waste confinement

International audienc