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1. Dynamic Modeling of Fouling in Reverse Osmosis Membranes

Author

Bowen Ling, Peng Xie, David Ladner, and Ilenia Battiato

Subjects
RO membrane, numerical model, OpenFoam, Chemical technology, TP1-1185, Chemical engineering, TP155-156
Abstract

During reverse osmosis (RO) membrane filtration, performance is dramatically affected by fouling, which concurrently decreases the permeate flux while increasing the energy required to operate the system. Comprehensive design and optimization of RO systems are best served by an understanding of the coupling between membrane shape, local flow field, and fouling; however, current studies focus exclusively on simplified steady-state models that ignore the dynamic coupling between fluid flow, solute transport, and foulant accumulation. We developed a customized solver (SUMs: Stanford University Membrane Solver) under the open source finite volume simulator OpenFOAM to solve transient Navier–Stokes, advection–diffusion, and adsorption–desorption equations for foulant accumulation. We implemented two permeate flux reduction models at the membrane boundary: the resistance-in-series (RIS) model and the effective-pressure-drop (EPD) model. The two models were validated against filtration experiments by comparing the equilibrium flux, pressure drop, and fouling pattern on the membrane. Both models not only predict macroscopic quantities (e.g., permeate flux and pressure drop) but also the fouling pattern developed on the membrane, with a good match with experimental results. Furthermore, the models capture the temporal evolution of foulant accumulation and its coupling with flux reduction.

Published
2021
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2. First-attempt success rate of video laryngoscopy in small infants (VISI): a multicentre, randomised controlled trial

Author

Annery G Garcia-Marcinkiewicz, Pete G Kovatsis, Agnes I Hunyady, Patrick N Olomu, Bingqing Zhang, Madhankumar Sathyamoorthy, Adolfo Gonzalez, Siri Kanmanthreddy, Jorge A Gálvez, Amber M Franz, James Peyton, Raymond Park, Edgar E Kiss, David Sommerfield, Heather Griffis, Akira Nishisaki, Britta S von Ungern-Sternberg, Vinay M Nadkarni, Francis X McGowan, John E Fiadjoe, David Ladner, Nicholas Burjek, Narasimhan Jagannathan, John Hadjuk, Saeedah Asaf, Chris Glover, Mary L Stein, Ramesh Kodavatiganti, B B Bruins, Brian Struyk, Luis Sequera-Ramos, Christopher Ward, Elizabeth Laverriere, Harshad Gurnaney, Eric Scheu, Heather Farrell, Paul Stricker, Pilar Castro, Angela Lee, Songyos Valairucha, Judit Szolnoki, Jennifer Zieg, Franklin B Chiao, Brad M Taicher, Jurgen C De Graaff, Nicholas M Dalesio, Robert S Greenberg, Angela R Lucero, Lillian Zamora, Allison Fernandez, Nada Mohamed, Stefano C Sabato, Christopher D Holmes, Somaletha T Bhattacharya, Jonathan Meserve, Paul I Reynolds, Bishr Haydar, Monica Weber, Megan Therrian, Martina Richtsfeld, Mark S Teen, and Anesthesiology

Subjects
Male, medicine.medical_treatment, Laryngoscopy, Video Recording, 030204 cardiovascular system & hematology, law.invention, 03 medical and health sciences, 0302 clinical medicine, Esophagus, Randomized controlled trial, law, medicine, Intubation, Intratracheal, Intubation, Humans, 030212 general & internal medicine, Airway Management, Intention-to-treat analysis, medicine.diagnostic_test, business.industry, Absolute risk reduction, Australia, Gestational age, Infant, General Medicine, Hospitals, Pediatric, United States, Endoscopy, Intention to Treat Analysis, Anesthesia, Airway management, Female, business
Abstract

Background: Orotracheal intubation of infants using direct laryngoscopy can be challenging. We aimed to investigate whether video laryngoscopy with a standard blade done by anaesthesia clinicians improves the first-attempt success rate of orotracheal intubation and reduces the risk of complications when compared with direct laryngoscopy. We hypothesised that the first-attempt success rate would be higher with video laryngoscopy than with direct laryngoscopy. Methods: In this multicentre, parallel group, randomised controlled trial, we recruited infants without difficult airways abnormalities requiring orotracheal intubation in operating theatres at four quaternary children's hospitals in the USA and one in Australia. We randomly assigned patients (1:1) to video laryngoscopy or direct laryngoscopy using random permuted blocks of size 2, 4, and 6, and stratified by site and clinician role. Guardians were masked to group assignment. The primary outcome was the proportion of infants with a successful first attempt at orotracheal intubation. Analysis (modified intention-to-treat [mITT] and per-protocol) used a generalised estimating equation model to account for clustering of patients treated by the same clinician and institution, and adjusted for gestational age, American Society of Anesthesiologists physical status, weight, clinician role, and institution. The trial is registered at ClinicalTrials.gov, NCT03396432. Findings: Between June 4, 2018, and Aug 19, 2019, 564 infants were randomly assigned: 282 (50%) to video laryngoscopy and 282 (50%) to direct laryngoscopy. The mean age of infants was 5·5 months (SD 3·3). 274 infants in the video laryngoscopy group and 278 infants in the direct laryngoscopy group were included in the mITT analysis. In the video laryngoscopy group, 254 (93%) infants were successfully intubated on the first attempt compared with 244 (88%) in the direct laryngoscopy group (adjusted absolute risk difference 5·5% [95% CI 0·7 to 10·3]; p=0·024). Severe complications occurred in four (2%) infants in the video laryngoscopy group compared with 15 (5%) in the direct laryngoscopy group (–3·7% [–6·5 to –0·9]; p=0·0087). Fewer oesophageal intubations occurred in the video laryngoscopy group (n=1 [

Published
2020

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