Modeling of an Interconnected Fluidized Bed Reactor for Chemical Looping Combustion

Chemical Looping Combustion (CLC) is comprised of two reactors, in which direct contact between air and fuel is avoided. A metal oxide, as oxygen carrier, transports oxygen from the air reactor to the fuel reactor while circulating between them. Based on the hydrodynamics coupled with reaction kinetics of oxygen carrier from the literature, a model for an interconnected fluidized bed reactor has been developed to optimize the design and operation of the reactor system. The model considers the chemical reaction of a single particle and a particle population balance for the calculation of bed particle conversion. The core-annulus and two-phase hydrodynamic models are assumed for the air and fuel reactors, respectively. Predictions of the oxygen emission, particle conversion and fuel conversion efficiency under different operating conditions are presented for a pilot scale CLC reactor system

Process, improvisation, holarchic learning loops and all that jazz: experiences in transdisciplinary education for sustainable development

This paper explores the experiences of an ‘Interdisciplinary Sustainability Assessment Laboratory’ (‘ISA Lab’) workshop, which took place over a week at Universitat Politècnica de València during April 2017. The workshop drew together students from a range of disciplines from across engineering and science, law and the social sciences and from a range of countries and backgrounds, including North and South America, Europe and Asia. It also facilitated a rich co-creative learning environment as it was led by (engineering) academic faculty from across Europe (Spain, UK, Netherlands and Ireland) as well as North America (Canada), as well as local experts who helped provide participants with appropriate context and guidance. The workshops culminated with a number of presentations from respective student groups, where they outlined an integrated development plan for a selected real life local project

Exploring transdisciplinary education

Because wicked Sustainability Problems (WSPs) are complex, multi-scaled, value-laden, ill-structured, and difficult to address (for example see Lonngren et al., 2016), teams that include engineers and others with expert knowledge are needed to effectively manage WSPs relating to environmental stress and declining ecosystem health, including WSPs stemming from resource scarcity, biodiversity loss, and climate change. How do we educate engineers to successfully engage in such transdisciplinary teams? What is transdisciplinary education? This paper explores aspects of these questions. First, we review areas of education literature relevant to transdisciplinary teaching and learning, including frameworks such as “Threshold Concepts” (Meyer & Land, 2006) and “Empathic Thinking” (Walther et al., 2017), and pedagogies reported in the literature, including “Value Analysis”, and “Learning Communities” (McGregor, 2017). We introduce the design-based research methodology (DBR) as a framework for developing transdisciplinary education, and we offer a review of the engineering education literature relevant to transdisciplinary training. Next, a case study employing DBR is presented. This case, inspired by the work of Tejedor & Segalas (2018a) and others, extends the work presented by Morgan et al. (2018), which reports a novel sustainable development workshop experience for masters-level graduate students, organized and hosted by the Universitat Politècnica de València (UPV) in the spring of 2017. A second workshop was deployed in June of 2018, during which students from a variety of backgrounds and institutions gathered in UPV to create locally relevant, sustainable, conceptual designs for the built environment. The DBR case study focuses on this 2nd workshop, during which survey, interview, and focus group data reflecting both the student and the facilitator experiences, were collected. An initial interpretation of this data is presented. This paper contributes to engineering education for sustainable development because it emphasizes a meta- framework which conceptualizes the development of transdisciplinary education experiences and which has the potential to enable faculty to reflect on and improve novel transdisciplinary experiences

Atrasentan and renal events in patients with type 2 diabetes and chronic kidney disease (SONAR): a double-blind, randomised, placebo-controlled trial

Background: Short-term treatment for people with type 2 diabetes using a low dose of the selective endothelin A receptor antagonist atrasentan reduces albuminuria without causing significant sodium retention. We report the long-term effects of treatment with atrasentan on major renal outcomes. Methods: We did this double-blind, randomised, placebo-controlled trial at 689 sites in 41 countries. We enrolled adults aged 18–85 years with type 2 diabetes, estimated glomerular filtration rate (eGFR)25–75 mL/min per 1·73 m 2 of body surface area, and a urine albumin-to-creatinine ratio (UACR)of 300–5000 mg/g who had received maximum labelled or tolerated renin–angiotensin system inhibition for at least 4 weeks. Participants were given atrasentan 0·75 mg orally daily during an enrichment period before random group assignment. Those with a UACR decrease of at least 30% with no substantial fluid retention during the enrichment period (responders)were included in the double-blind treatment period. Responders were randomly assigned to receive either atrasentan 0·75 mg orally daily or placebo. All patients and investigators were masked to treatment assignment. The primary endpoint was a composite of doubling of serum creatinine (sustained for ≥30 days)or end-stage kidney disease (eGFR <15 mL/min per 1·73 m 2 sustained for ≥90 days, chronic dialysis for ≥90 days, kidney transplantation, or death from kidney failure)in the intention-to-treat population of all responders. Safety was assessed in all patients who received at least one dose of their assigned study treatment. The study is registered with ClinicalTrials.gov, number NCT01858532. Findings: Between May 17, 2013, and July 13, 2017, 11 087 patients were screened; 5117 entered the enrichment period, and 4711 completed the enrichment period. Of these, 2648 patients were responders and were randomly assigned to the atrasentan group (n=1325)or placebo group (n=1323). Median follow-up was 2·2 years (IQR 1·4–2·9). 79 (6·0%)of 1325 patients in the atrasentan group and 105 (7·9%)of 1323 in the placebo group had a primary composite renal endpoint event (hazard ratio [HR]0·65 [95% CI 0·49–0·88]; p=0·0047). Fluid retention and anaemia adverse events, which have been previously attributed to endothelin receptor antagonists, were more frequent in the atrasentan group than in the placebo group. Hospital admission for heart failure occurred in 47 (3·5%)of 1325 patients in the atrasentan group and 34 (2·6%)of 1323 patients in the placebo group (HR 1·33 [95% CI 0·85–2·07]; p=0·208). 58 (4·4%)patients in the atrasentan group and 52 (3·9%)in the placebo group died (HR 1·09 [95% CI 0·75–1·59]; p=0·65). Interpretation: Atrasentan reduced the risk of renal events in patients with diabetes and chronic kidney disease who were selected to optimise efficacy and safety. These data support a potential role for selective endothelin receptor antagonists in protecting renal function in patients with type 2 diabetes at high risk of developing end-stage kidney disease. Funding: AbbVie

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements