Simulations of extensional flow in microrheometric devices

We present a detailed numerical study of the flow of a Newtonian fluid through microrheometric devices featuring a sudden contraction–expansion. This flow configuration is typically used to generate extensional deformations and high strain rates. The excess pressure drop resulting from the converging and diverging flow is an important dynamic measure to quantify if the device is intended to be used as a microfluidic extensional rheometer. To explore this idea, we examine the effect of the contraction length, aspect ratio and Reynolds number on the flow kinematics and resulting pressure field. Analysis of the computed velocity and pressure fields show that, for typical experimental conditions used in microfluidic devices, the steady flow is highly three-dimensional with open spiraling vortical structures in the stagnant corner regions. The numerical simulations of the local kinematics and global pressure drop are in good agreement with experimental results. The device aspect ratio is shown to have a strong impact on the flow and consequently on the excess pressure drop, which is quantified in terms of the dimensionless Couette and Bagley correction factors. We suggest an approach for calculating the Bagley correction which may be especially appropriate for planar microchannels

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Capture and release of traveling intrinsic localized mode in coupled cantilever array

A method to manipulate intrinsic localized mode (ILM) is numerically discussed in a nonlinear coupled oscillator array, which is obtained by modeling a microcantilever array. Prior to the manipulation, coexistence and dynamical stability of standing ILMs are first investigated. The stability of coexisting ILMs is determined by a nonlinear coupling coefficient of the array. In addition, the global phase structure, which dominates traveling ILMs, is also changed with the stability. It makes possible to manipulate a traveling ILM by adjusting the nonlinear coupling coefficient. The capture and release manipulation of the traveling ILM is shown numerically

Comparative techno-economic analysis for steam methane reforming in a sorption-enhanced membrane reactor: Simultaneous H-2 production and CO2 capture

Hydrogen (H-2) is currently receiving significant attention as a sustainable energy carrier. Steam methane reforming (SMR) accounts for approximately 50% of H-2 production methods worldwide. However, SMR is concern because of the prodigious carbon dioxide (CO2) emissions that have resulted in a global climate emergency. CO2 emissions remain, although some efforts have been made in a membrane reactor (MR) coupled with membranes to improve the H-2 yield. A sorption-enhanced membrane reactor (SEMR) has been proposed as a next-generation process for simultaneous H-2 production and CO2 capture. In this study, the thermodynamic and economic evaluation of SEMR were implemented using a process simulation, an itemized cost estimation, a sensitivity analysis (SA), and an uncertainty analysis (UA). The thermodynamic analysis results revealed that unit H-2 production costs of 4.53,1.98, and 3.04 $kgH(2)(- 1) were obtained at 773 K for a conventional packed-bed reactor (PBR), a MR, and a SEMR, respectively. The SA results identified PSA as the most critical economic parameter for a unit H-2 production cost for a PBR, whereas natural gas is determined to be the most influential parameter for a MR and a SEMR. The UA results from a Monte-Carlo simulation provided a broad range of unit H-2 production costs, with 4.26-5.44$ kgH(2)(-1) for a PBR, 1.61-2.94 $kgH(2)(- 1) for a MR, and 2.83-4.19$ kgH(2)(-1)for an SEMR. This indicates that using a SEMR for next-generation H-2 production and CO2 capture is beneficial. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved