Failure Mechanisms in Sand over a Deep Active Trapdoor

An experimental testing program was undertaken to investigate failure mechanisms induced by the active movement of a deep rectangular trapdoor underlying a granular soil. Reduced-scale models were tested under normal gravity as well as under an increased gravitational field using a centrifuge facility. Some models were used to evaluate the performance of both flexible and rigid pipes undergoing a localized loss of support. Failure mechanisms in the longitudinal direction of the models were characterized by a single, well-defined failure surface that developed within the limits of the trapdoor. However, failure mechanisms in the transverse direction of the models were characterized by multiple failure surfaces extending outside the limits of the trapdoor. Significant dilation of the soil located immediately above the trapdoor was identified in the failure of the models. The pattern of the failure mechanisms was found to be affected by the stress level and backfill density. Higher stress levels were found to lead to well-developed failure zones. The influence of backfill density was found to be more relevant in models involving flexible pipes. Pipes embedded within loose backfill were severely damaged after loss of support, while pipes embedded in dense backfill experienced negligible deformations. These results indicate that damage to pipelines caused by ground loss of support can be significantly minimized by controlling the compaction of the fill.     

Occurrence of polar organic contaminants in the dissolved water phase of the Danube River and its major tributaries using SPE-LC-MS analysis

Polar water-soluble organic contaminants were analysed in the dissolved liquid water phase of river water samples from the Danube River and its major tributaries (within the Joint Danube Survey 2). Analyses were performed by solid-phase extraction (SPE) followed by triple-quadrupole liquid chromatography mass spectrometry (LC-MS²). In total, 34 different polar organic compounds were screened. Focus was given on pharmaceutical compounds (such as ibuprofen, diclofenac, sulfamethoxazole, carbamazepine), pesticides and their degradation products (e.g. bentazone, 2,4-D, mecoprop, atrazine, terbutylazine, desethylterbutylazine), perfluorinated acids (PFOS; PFOA), and endocrine disrupting compounds (nonylphenol, NPE₁C, bisphenol A, estrone). The most relevant polar compounds identified in the Danube River basin in terms of frequency of detection, persistency, and concentration levels were 1H-benzotriazole (median concentration 185 ng/L), caffeine (87 ng/L), tolyltriazole (73 ng/L), nonylphenoxy acetic acid (49 ng/L), carbamazepine (33 ng/L), 4-nitrophenol (29 ng/L), 2,4-dinitrophenol (19 ng/L), PFOA (17 ng/L), sulfamethoxazole (16 ng/L), desethylatrazine (11 ng/L), and 2,4-D (10 ng/L). The highest contamination levels were found in the area around Budapest and in the tributary rivers Arges (Romania), Timok (Bulgaria), Rusenski Lom (Bulgaria), and Velika Morava (Serbia).     

Synthesis of the Ammonium Salt of 6‐Amino‐2‐hydroxy‐ 3,5‐dinitropyrazine and a Comparison of its Properties with those of Ammonium 3,5‐Diaminopicrate (ADAP)

The ammonium salt of 6‐amino‐2‐hydroxy‐3,5‐dinitropyrazine has been synthesised from 2,6‐dimethoxy‐3,5‐dinitropyrazine and its properties (DSC, crystal structure, impact sensitiveness and thermochemical properties) are compared with the analogous benzene derivative, ammonium 3,5‐diaminopicrate.     

Discrepancy in responses to the surprise question between hemodialysis nurses and physicians,with focus on patient clinical characteristics: A comparative study

Introduction

The surprise question (SQ) “Would I be surprised if this patient died within the next xx months” can be used by different professions to foresee the need of serious illness conversations in patients approaching end of life. However, little is known about the different perspectives of nurses and physicians in responses to the SQ and factors influencing their appraisals. The aim was to explore nurses' and physicians' responses to the SQ regarding patients on hemodialysis, and to investigate how these answers were associated with patient clinical characteristics.

Methods

This comparative cross-sectional study included 361 patients for whom 112 nurses and 15 physicians responded to the SQ regarding 6 and 12 months. Patient characteristics, performance status, and comorbidities were obtained. Cohen's kappa was used to analyze the interrater agreement between nurses and physicians in their responses to the SQ and multivariable logistic regression was applied to reveal the independent association to patient clinical characteristics.

Findings

Proportions of nurses and physicians responding to the SQ with “no, not surprised” was similar regarding 6 and 12 months. However, there was a substantial difference concerning which specific patient the nurses and physicians responded “no, not surprised”, within 6 (κ = 0.366, p < 0.001, 95% CI = 0.288–0.474) and 12 months (κ = 0.379, p < 0.001, 95% CI = 0.281–0.477). There were also differences in the patient clinical characteristics associated with nurses' and physicians' responses to the SQ.

Discussion

Nurses and physicians have different perspectives in their appraisal when responding to the SQ for patients on hemodialysis. This may reinforce the need for communication and discussion between nurses and physicians to identify the need of serious illness conversations in patients approaching the end of life, in order to adapt hemodialysis care to patient preferences and needs.     

Design,Synthesis and Biological Evaluation of Highly Potent Simplified Archazolids

The archazolids are potent antiproliferative compounds that have recently emerged as a novel class of promising anticancer agents. Their complex macrolide structures and scarce natural supply make the development of more readily available analogues highly important. Herein, we report the design, synthesis and biological evaluation of four simplified and partially saturated archazolid derivatives. We also reveal important structure-activity relationship data as well as insights into the pharmacophore of these complex polyketides.     

Coronary artery bypass grafting versus percutaneous coronary intervention in end-stage kidney disease: A systematic review and meta-analysis of clinical studies

The most significant complication of end-stage kidney disease (ESKD) is cardiovascular disease, mainly coronary artery disease (CAD). Although the effective treatment of CAD is an important prognostic factor, whether percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) is better for treating CAD in this group of patients is still controversial. We searched Pubmed/Medline, Web of Science, Embase, the Cochrane Central Register of Controlled Trials articles that compared the outcomes of CABG versus PCI in patients with ESKD requiring dialysis. A total of 10 observational studies with 39,666 patients were included. Our analysis showed that when compared to PCI, CABG had lower risk of need for repeat revascularization (relative risk [RR] = 2.25, 95% confidence interval [CI] 2.1–2.42, p < 0.00001) and cardiovascular death (RR = 1.19, 95% CI 1.14–1.23, p < 0.00001) and higher risk for short-term mortality (RR = 0.43, 95% CI 0.38–0.48, p < 0.00001). There was no statistically significant difference between the PCI and CABG groups in the risk for late mortality (RR = 1.05, 95% CI 0.97–1.14, p = 0.25), myocardial infarction (RR = 1.05, 95% CI 0.46–2.36, p = 0.91) or stroke (RR = 1.02, 95% CI 0.64–1.61, p = 0.95). This meta-analysis showed that in ESKD patients requiring dialysis, CABG was superior to PCI in regard to cardiovascular death and need for repeat revascularization and inferior to PCI in regard to short term mortality. However, this meta-analysis has limitations and needs confirmation with large randomized controlled trials.     

A Shape‐Induced Orientation Phase within 3D Nanocrystal Solids

When nanocrystals self assemble into ordered superstructures they form functional solids that may inherit the electronical properties of the single nanocrystals. To what extent these properties are enhanced depends on the positional and orientational order of the nanocrystals within the superstructure. Here, the formation of micrometer‐sized free‐standing supercrystals of faceted 20 nm Bi nanocrystals is investigated. The self‐assembly process, induced by nonsolvent into solvent diffusion, is probed in situ by synchrotron X‐ray scattering. The diffusion‐gradient is identified as the critical parameter for controlling the supercrystal‐structure as well as the alignment of the supercrystals with respect to the substrate. Monte Carlo simulations confirm the positional order of the nanocrystals within these superstructures and reveal a unique orientation phase: the nanocrystal shape, determined by the atomic Bi crystal structure, induces a total of 6 global orientations based on facet‐to‐facet alignment. This parallel alignment of facets is a prerequisite for optimized electronic and optical properties within designed nanocrystal solids.     

Arsenate adsorption and desorption kinetics on a Fe(III)-modified montmorillonite

The adsorption-desorption kinetics of arsenate on a Fe(III)-modified montmorillonite (Fe-M) was studied at different arsenate concentrations, pH and stirring rates. The synthesized solid was a porous sample with Fe(III) present as a mix of monomeric and polymeric Fe(III) species in the interlayer and on the external surface. Adsorption took place in a two-step mechanism, with an initial fast binding of arsenate to Fe(III) species at the external surface (half-lives of 1 min or shorter) followed by a slower binding to less accessible Fe(III) species in pores and the interlayer (half-lives of around 1 h). Desorption kinetics also reflected the presence of externally and internally adsorbed arsenate. At pH 6 the maximum adsorbed arsenate was 52 μmol/g, a value that is low as compared to adsorption on ferrihydrite (700 μmol/g) and goethite (192-220 μmol/g). However, since the Fe(III) content of Fe-M is much lower than that of ferrihydrite and goethite, Fe(III) species in Fe-M are more efficient in binding arsenate than in ferrihydrite or goethite (one As atom is attached every 8.95 iron atoms). This high binding efficiency indicates that Fe(III) species are well spread on montmorillonite, forming small oligomeric species or surface clusters containing just a few iron atoms.