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Hydrodynamics plays a major role in transport of heat and mass transfer in microchannels. This includes flow patterns and flow regimes in which the micro-channels are operated. The flow patterns have a major impact the transport properties. Another important aspect is the pressure drop in micro-channels. In the present review, the experimental and Computational Fluid Dynamics (CFD) studies covering all the above aspects have been covered. The effect of geometrical parameters like shape of channel, channel size, material of construction of channels; operating parameters like flow velocity, flow ratio and fluid properties have been presented and analyzed. Experimental and analytical work of different pressure drop models has also been presented. All the literature related to influence of flow patterns on transport properties like volumetric mass transfer coefficients (VMTC) and heat transfer coefficients (HTC) have been presented and analyzed. It is found that most works in Liquid-Liquid Extraction (LLE) systems have been carried out in slug flow and T-junctions. Models for coupled systems of flow and mass transfer have been presented and works carried out for different coupled systems have been listed. CFD simulations match experimental results within 20% deviations in quantitative and qualitative predictions of flow phenomena for most research articles referred in this review. There is a disparity in prediction of a generalized regime map and a generalized regime map for prediction of flow patterns for various systems would need the help of Artificial Intelligence.

In the present work, three-dimensional (3D) simulations have been performed for the characterization of a rectangular column for a uniform gas distributor with µm-sized holes at a ratio of 5. The model is first validated with experimental data from the literature. Simulations are then performed for a gas distributor with identical pitch but two different hole sizes, namely 600 µm and 200 µm. Three superficial gas velocities, namely 0.002 m/s, 0.004 m/s, and 0.006 m/s, were used for each distributor type. The gas movement in the fluid is found to be a strong function of hole size. For a 600 µm hole size, the operating condition has minimal impact on gas plume movement and moves centrally in a fully aerated regime. However, for a hole size of 200 µm, for all superficial velocities, the gas plume movement is dynamic and partially aerated. The plume moves along the right wall initially and then follows vertically. These characteristics are different from the meandering plume in centrally located spargers. The liquid mixing in the bulk is a function of time. During the plume development flow, different shapes are observed. Based on the analogy with the shapes found in nature, these shapes have been termed as balloon, cap, jet or candle flame, bull horn, mushroom, tree shape, and disintegrated mushroom shapes. Quantitative insights have been obtained in the form of time-averaged radial profiles of both volume fractions and liquid axial velocities. A symmetric parabolic shape for a hole size of 600 µm and skewed asymmetric shapes for a 200 µm hole size for three different axial positions, namely 0.1, 0.25, and 0.4 m, are observed. Correlations for gas holdup and liquid velocity have been proposed for low superficial velocities, which are in good agreement with the CFD simulation data, with a deviation of 15–20%. The deviations are partly due to the use of the k-ε turbulent model. The correlations perform better than the correlations available in the reported literature for similar superficial gas velocities.

The use of solar energy for power generation using the innovative solar chimney concept has been explored by many researchers mostly with the help of analytical models as well as CFD simulations while experimental studies for a pilot and bench scale facilities have been carried out. The efficiencies of these chimneys, however, are less than 1% (~0.07% for 50 kW pilot plant similar to Manzanares plant in Spain). In the present study, an effort has been made to make modifications in the chimney design to improve the efficiency of the chimney in terms of power generation. CFD simulations have been carried out for this modified design and the efficiency is seen to improve to 0.12% for a 50 kW chimney. Furthermore, a techno-economic feasibility analysis has been carried out for a conventional 5 MW solar power plant which can be installed on the western part of India, which receives good solar irradiation throughout the year. Two cases with and without government subsidies have been considered. It is observed that a high rate of return (~20.4%) is obtained for a selling price of electricity of Rs 5 per kWh with government subsidy, while a rate of return of ~19% is obtained for Rs 10 per kWh without government subsidy.

Natural convection in enclosures heated from both sides is a topic of interest in various space and safety applications in nuclear power reactors. The transient dynamics during natural convection in enclosures is critically dependent on micro-scaled boundary layers and also the timescales of micromixing. In the present work, a square enclosure operating at two high Rayleigh numbers (Ra = 3.27 × 1010 and Ra = 6.55 × 1010, with water as the working fluid) have been chosen for study. First, the velocity and timescales were found using Computational Fluid Dynamic (CFD) simulations for the square enclosure with Ra 3.27 × 1010 and compared with scaling laws that presently define them. An empirical correlation for heat transfer is then developed for the Ra range (1.3 × 1010 < Ra < 6.55 × 1010). Then, an existing DL framework (Proper Orthogonal Decomposition and Long Short-Term Memory (POD-LSTM)) network) is compared qualitatively and quantitatively with the CFD data. The transient data Ra = 6.55 × 1010 was chosen for this purpose. The scaling laws show a 30% deviation for the predictions of the transient length and time scales as compared to CFD and DL model predictions. Further, accurate results up to 99.6% have been obtained by the DL model when compared with the CFD model. The DL model is also found to require an order of magnitude less time than the one required for a CFD simulation.

Background Patient-reported outcomes (PROs) are important when evaluating treatment benefits in rheumatoid arthritis (RA). We compared upadacitinib, an oral, selective JAK-1 inhibitor, with placebo to assess clinically meaningful improvements in PROs in patients with RA who have had inadequate responses to biologic disease-modifying antirheumatic drugs (bDMARD-IR). Methods PRO responses between upadacitinib 15 mg or 30 mg and placebo were evaluated at week 12 from the SELECT-BEYOND trial. Improvement was determined by measuring Patient Global Assessment of Disease Activity (PtGA), pain, Health Assessment Questionnaire Disability Index (HAQ-DI), Short Form-36 Health Survey (SF-36), duration and severity of morning (AM) stiffness, and Insomnia Severity Index (ISI). Least squares mean changes and percentage of patients reporting improvements ≥ minimum clinically important differences (MCID) and scores greater than or equal to normative values were determined. The number needed to treat (NNT) to achieve clinically meaningful improvements was calculated. Results In 498 patients, both upadacitinib doses resulted in statistically significant changes from baseline versus placebo in PtGA, pain, HAQ-DI, SF-36 Physical Component Summary (PCS), 7 of 8 SF-36 domains (15 mg), 6 of 8 SF-36 domains (30 mg), and AM stiffness duration and severity. Compared with placebo, more upadacitinib-treated patients reported improvements ≥ MCID in PtGA, pain, HAQ-DI, SF-36 PCS, 7 of 8 SF-36 domains (15 mg), 5 of 8 SF-36 domains (30 mg), AM stiffness duration and severity, and ISI (30 mg) and scores ≥ normative values in HAQ-DI and SF-36 domains. Across most PROs, NNTs to achieve MCID with upadacitinib ranged from 4 to 7 patients. Conclusions In bDMARD-IR RA patients, upadacitinib (15 mg or 30 mg) improved multiple aspects of quality of life, and more patients reached clinically meaningful improvements approaching normative values compared with placebo. Trial registration The trial is registered with ClinicalTrials.gov (NCT02706847), registered 6 March 2016.

The present review focuses on the recent studies carried out in passive micromixers for understanding the hydrodynamics and transport phenomena of miscible liquid–liquid (LL) systems in terms of pressure drop and mixing indices. First, the passive micromixers have been categorized based on the type of complexity in shape, size, and configuration. It is observed that the use of different aspect ratios of the microchannel width, presence of obstructions, flow and operating conditions, and fluid properties majorly affect the mixing characteristics and pressure drop in passive micromixers. A regime map for the micromixer selection based on optimization of mixing index (MI) and pressure drop has been identified based on the literature data for the Reynolds number (Re) range (1 ≤ Re ≤ 100). The map comprehensively summarizes the favorable, moderately favorable, or non-operable regimes of a micromixer. Further, regions for special applications of complex micromixer shapes and micromixers operating at low Re have been identified. Similarly, the operable limits for a micromixer based on pressure drop for Re range 0.1 < Re < 100,000 have been identified. A comparison of measured pressure drop with fundamentally derived analytical expressions show that Category 3 and 4 micromixers mostly have higher pressure drops, except for a few efficient ones. An MI regime map comprising diffusion, chaotic advection, and mixed advection-dominated zones has also been devised. An empirical correlation for pressure drop as a function of Reynolds number has been developed and a corresponding friction factor has been obtained. Predictions on heat and mass transfer based on analogies in micromixers have also been proposed.

Background To evaluate the effect of upadacitinib on patient-reported outcomes (PROs) in patients with RA who had an inadequate response to csDMARDs. Methods Patients in SELECT-NEXT, a randomised controlled trial, were on a background of csDMARDs and received upadacitinib 15 mg and 30 mg or placebo daily for 12 weeks. PROs included Patient Global Assessment of Disease Activity (PtGA), pain, Health Assessment Questionnaire-Disability Index (HAQ-DI), Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F), duration and severity of morning (AM) joint stiffness, Short Form 36 Health Survey (SF-36), and Work Instability Scale for RA (RA-WIS). Least squares mean (LSM) changes were based on mixed-effect repeated measure models. Percentages of patients reporting improvements ≥ minimum clinically important differences (MCIDs) and scores ≥ normative values and number needed to treat (NNT) were determined; group comparisons used chi-square tests. Results Data from 661 patients were analysed. Compared with placebo, patients receiving upadacitinib reported statistically significant improvements (both doses, P  < 0.05) in PtGA, pain, HAQ-DI, FACIT-F, duration and severity of AM stiffness, SF-36 (PCS and 6/8 domains), and RA-WIS at week 12. Significantly, more upadacitinib-treated patients (both doses, P  < 0.05) reported improvements ≥ MCID in PtGA, pain, HAQ-DI, FACIT-F, AM stiffness, SF-36 (PCS and 4 or 7/8 domains), and RA-WIS and scores ≥ normative values in HAQ-DI, FACIT-F, and SF-36 (PCS and 4 or 5/8 domains). For most PROs, the incremental NNT with upadacitinib to report clinically meaningful improvement from baseline ranged from 4 to 8 patients. Conclusions Upadacitinib 15 mg or 30 mg daily for 12 weeks resulted in significant and clinically meaningful improvements in global disease activity, pain, physical function, fatigue, duration and severity of AM stiffness, HRQOL, and work instability among csDMARD-IR patients with RA. Trial registration Clinicaltrials.gov, NCT02675426 . Retrospectively registered 5 February 2016.

Introduction Prior studies have reported that hidradenitis suppurativa (HS) is accompanied by a myriad of physical and mental conditions. However, given the small sample sizes and the limited number of pre-selected comorbidities, these studies do not provide a complete picture of the comorbidity burden of HS in the USA. Moreover, the relationship between HS severity and comorbidity burden has yet to be characterized. Using a large US claims database, we estimated the comorbidity burden associated with HS, stratified by disease severity. Methods A retrospective matched cohort design was used. Patients with HS were classified into two severity cohorts (milder and more severe) using an empirical algorithm based on treatments received. The comorbidity burden was compared between each HS cohort and their matched HS-free cohort, and between patients with milder vs. those with more severe forms of HS. Results Several physical and mental comorbidities were found to be more prevalent in both cohorts of patients with milder and more severe forms of HS than in their matched HS-free cohorts. The comorbidity burden also increased greatly as the disease progressed to more severe forms. Conclusions The results of this study highlight the complexity of the comorbidity burden of HS patients and the need for a multidisciplinary approach to optimize the management of HS and its numerous associated comorbidities. Funding AbbVie, Inc.

Background The perceived bother of skin and joint-related manifestations of psoriatic disease may differ among patients, rheumatologists, and dermatologists. This study identified and compared the patient and dermatologist/rheumatologist-perceived bother of psoriatic disease manifestations. Methods Online surveys were administered to patients with both psoriasis and psoriatic arthritis and to dermatologists and rheumatologists. Object-case best–worst scaling was used to identify the most and least bothersome items from a set of five items in a series of questions. Each item set was drawn from 20 items describing psoriatic disease skin and joint symptoms and impacts on daily activities. Survey responses were analyzed using random-parameters logit models for each surveyed group, yielding a relative-bother weight (RBW) for each item compared with joint pain, soreness, or tenderness. Results Surveys were completed by 200 patients, 150 dermatologists, and 150 rheumatologists. Patients and physicians agreed that joint pain, soreness, and tenderness are among the most bothersome manifestations of psoriatic disease (RBW 1.00). For patients, painful, inflamed, or broken skin (RBW 1.03) was more bothersome, while both rheumatologists and dermatologists considered painful skin much less bothersome (RBW 0.17 and 0.22, respectively) than joint pain. Relative to joint pain, rheumatologists were more likely to perceive other joint symptoms as bothersome, while dermatologists were more likely to perceive other skin symptoms as bothersome. Conclusions This study has identified important areas of discordance both between patients and physicians and between rheumatologists and dermatologists about the relative bother of a comprehensive set of psoriatic disease symptoms and functional impacts. Both physician specialists should ask patients which manifestations of psoriatic disease are most bothersome to them, as these discussions may have important implications for drug and other patient management options.

Background. Treatment preferences of patients with high-risk localized prostate cancer (HRLPC) and metastatic hormone-sensitive prostate cancer (mHSPC) are expected to be influenced by cultural and institutional differences across countries. We aimed to evaluate this expectation by quantifying the importance of treatment outcomes for patients with HRLPC and mHSPC. Methods. A discrete-choice experiment survey included adults (≥18 y of age) diagnosed with HRLPC or mHSPC from 5 countries—France, Spain, China, South Korea, and Japan—with or without previous experience of androgen-deprivation therapy. A latent-class random-parameters logit model was used to evaluate the importance patients assigned to treatment attributes and the consistency in treatment preferences across the 5 countries. Results. In total, 468 patients completed the survey. Respondents with shared treatment preferences from all 5 countries had a chance of being in pooled class 1 (44.5%) or pooled class 2 (37.9%). The main factors of concern were skin rash, fatigue, and use of steroids for pooled class 1 and chemotherapy-associated problems for pooled class 2. Our analysis could not explain class assignments based on clinically relevant characteristics of patients, which were used as covariates. Conclusion. Despite cultural and institutional differences across the 5 countries, our model identified significant consistency in treatment preferences among patients with prostate cancer. Given the attribute levels in our study, efficacy was the most significant driver of patient preference. We also found that using 2 sets of preferences was sufficient to reasonably characterize the perspectives of about 80% of surveyed patients. That these 2 patient classes differed in terms of treatment concerns but not in clinical factors highlights the need for promoting communication between patients and clinicians about treatment choices. Highlights Our study demonstrates that discrete-choice experiments (DCEs) are valuable for capturing health-related preferences among patients with prostate cancer. Contextual factors, such as efficacy and the country-specific health care system in which choices are presented, influence the ability to pool DCE data across countries. DCEs have the potential to enhance patient-centered care, shaping the future of evidence-based health care decision making. Graphical Abstract This is a visual representation of the abstract.