Long-term behaviour of a dam affected by alkali–silica reaction studied by a multi-scale model

This paper aims to employ a 2D thermo-mechanical multi-scale ASR model for the analysis of a concrete gravity dam in Western Switzerland. Simulation results are compared to the field measurements and observations. Analysis of the results reveals negligible effect of temperature variation on the ASR advancement. The difference in length between the upstream and the downstream faces is identified as the main source for the upstream drift at the level of the crest. Study of the structural effects reveals ASR-related expansion anisotropy and cracks alignment being more pronounced along the upstream part and the foundation. If the former is explained by the transmission of the self-weight, the latter is attributed to the constraining effect of the underlying rock

The development of direct extrusion-injection moulded zein matrices as novel oral controlled drug delivery systems

Purpose: To evaluate the potential of zein as a sole excipient for controlled release formulations prepared by hot melt extrusion. Methods: Physical mixtures of zein, water and crystalline paracetamol were hot melt extruded (HME) at 80°C and injection moulded (IM) into caplet forms. HME-IM Caplets were characterised using differential scanning calorimetry, ATR-FTIR spectroscopy, scanning electron microscopy and powder X-ray diffraction. Hydration and drug release kinetics of the caplets were investigated and fitted to a diffusion model. Results: For the formulations with lower drug loadings, the drug was found to be in the non-crystalline state, while for the ones with higher drug loadings paracetamol is mostly crystalline. Release was found to be largely independent of drug loading but strongly dependent upon device dimensions, and predominately governed by a Fickian diffusion mechanism, while the hydration kinetics shows the features of Case II diffusion. Conclusions: In this study a prototype controlled release caplet formulation using zein as the sole excipient was successfully prepared using direct HME-IM processing. The results demonstrated the unique advantage of the hot melt extruded zein formulations on the tuneability of drug release rate by alternating the device dimensions

Study on the internal crack network of the ASR-affected concrete by the tomography-based numerical model

In this paper, we present a novel finite element model to simulate alkali-silica reaction in a realistic concrete meso-structure. Application of the internal ASR loading leads to the evolution of multiple deviated cracks and corresponding macroscopic expansion. A particular crack-extension algorithm and a solution scheme provide numerical stability and allow to model complicated crack patterns while preserving the physics. The predictive validity of the model is demonstrated by matching an analytical solution of a loaded penny-shaped crack. The model is applied to the experimental dataset comprising the time-evolving X-ray tomograms of the ASR-affected concrete. Similar to the tomography data, the model results in an expanded concrete sample with a developed crack network. Two hypotheses on the crack loading and extension mechanisms are tested by comparing the crack statistics. Simulations with varying number of ASR sites and application of the uniaxial loading bring interesting insights. The latter concerns the role of the ASR-sites number, the individual loading amplitude and the difference in crack patterns

Technique of the laparoscopic pelvic exenteration

Background: Laparoscopic surgery has proved itself to be a “golden standard” for treatment of most abdominal and retroperitoneal cancers. Such a serious procedure as pelvic exenteration continues to be a complex surgical intervention usually performed through a  conventional laparotomic access. However, studies on minimally invasive approach for this intervention have becoming increasingly published in the world literature.Aim: To describe the laparoscopic pelvic exenteration technique of pelvic exenteration, as well as to assess short- and long-term results of these interventions.Materials and methods: From 2011 to 2018, 21 procedures of laparoscopic pelvic exenteration have been performed in 6  surgical centers (Moscow, Russia). Six (6) patients had previously confirmed cervical cancer, 7 patients had bladder cancer, 4 patients had rectal cancer, 1 patient had vaginal cancer, 2 patients had relapsing vaginal cancers after previous uterine extirpation, and 1 patient had an ovarian neoplasm.Results: The laparoscopic pelvic exenteration volumes were as follows: 9  total, 7 anterior and 5 posterior procedures. In 19 out of 21 cases, negative resection margin (R0) was possible. Median duration of the procedure was 254 minutes, median blood loss was 515 ml, and median postoperative hospital stay was 13 days. Postoperative complications were registered in 6 (28.6%) patients. The 3-year overall survival was 85.71%.Сonclusion: The choice of laparoscopic access can reduce blood loss, decrease the rates of early postoperative complications, contributes to a more comfortable postoperative period with early activation and less severe pain syndrome, and leads to a reduction in the duration of hospital stay. These results of the laparoscopic technique are comparable with those of laparoscopic and open pelvic exenteration published by other authors