bluuebunny/crossref_metadata_2025 huggingface dataset:
Erosion Testing and Modeling of a Triangular Elbow As Compared to a Circular Elbow
Authors: Kolla Srinivas S. , Asgharpour Alireza , Shirazi Siamack A. , Silva Gabriel
Published: October 2020

The erosion patterns in elbows with circular cross-sections have been investigated extensively experimentally and computationally in the past. However, in a bid to reduce erosion in elbows, a new triangular (in cross-section) elbow has been designed and investigated comprehensively during this study. The goal of this work was to examine experimentally and predict computationally using existing erosion models, the erosion patterns in a triangular elbow geometry and compare it to circular elbows for stainless steel materials. Initially, computational fluid dynamics erosion modeling was used to compare erosion in a triangular in-cross-section elbow to a circular elbow. Computational fluid dynamics were then followed by an experimental investigation using flow visualization with a paint removal study to determine the location where particles impinge and lead to erosion. Erosion measurement experiments are also conducted in a flow loop containing liquid and 300 microns sand particles. Within the experimental rig, to avoid abrupt changes of the triangular elbow with the circular pipe, a smooth transition region is designed and utilized. Various transition geometries such as transition length, eccentricity have been investigated with CFD to ensure smooth flow and reduced erosion from the circular pipe to the triangular elbow. CFD simulation results showed that erosion also occurred on the side of the triangular elbow and have been concurred by the paint study as well. It is observed that the erosion in the triangular elbow is approximately 68% lower than that in the circular elbow for the tested conditions. Thus, it is advantageous to use these elbows for practical applications such as fracturing to reduce replacement time of elbows.
Adaptive Simulation Based on URANS and Ensemble Kalman Filter for Resolving Turbulent Flow on LES
Authors: Ito Sasuga , Furukawa Masato , Kazutoyo Yamada , Manabe Kaito
Published: October 2020

Turbulence is one of the most important phenomena in fluid dynamics. In general, turbulent phenomena can be resolved more clearly with Large Eddy Simulation (LES) compared with Unsteady Reynolds Averaged Navier-Stokes (URANS), and the numerical solution shows good agreements with that based on Direct Numerical Simulation (DNS). However, more time and computational power are needed on LES than those on URANS. If possible, the ideal simulation method is that the method is able to resolve the turbulent phenomena same quality as the results based on DNS and LES with less time and less computational power same as that on URANS. This paper shows an adaptive simulation method based on URANS and Ensemble Kalman Filter (Enkf) to reproduce the flow fields based on LES. In this study, a two-dimensional turbine cascade flow has been solved with URANS and LES. The adaptive simulation method has been also applied to the cascade flow. As the results, in the flow field of URANS with the assimilated turbulence model’s parameters, the separation phenomenon and the boundary layer thickness was close to that of the time averaged LES.
A Computational Fluid Dynamic Study of a Momentum and Energy Method on Rough Surfaces
Authors: Urcia Jose , Kinzel Michael
Published: October 2020

The Discrete Element Roughness Method (DERM) has been used to improve convective heat transfer predictions on surface roughness. This work aims to validate the core momentum-correlation of DERM through evaluating Computational fluid dynamics (CFD)-based solution of the flow around individual roughness elements with the goal of improving the correlations. More specifically, the matrix of scenarios evaluated using includes three different roughness elements at three different pressure drops (or flow rates). Results from these studies are to be used to validate and improve correlations used to approximate roughness in DERM. For further comparison, a fourth roughness element analyzed in previous work will also be compared. For each element, a steady and unsteady case are conducted and analyzed. The momentum loss results obtained from the CFD are then compared to the DERM-based predictions from the same roughness elements in search of any discrepancies. It is observed the momentum-correlation deviates from the CFD prediction with increasing element height.
Effect of Neutrally Buoyant Particles on Horizontal Turbulent Flow Through a Tee-Junction
Authors: Bluestein Andrew M. , Bohl Douglas
Published: October 2020

Turbulent particle-laden flows are of high interest due to their presence in many industrial applications. High Reynolds number flows containing solid particles, create complex flows and erosive environments. The effect that the particles have on the turbulence of the surrounding fluid is referred to in the literature as turbulence modulation. This is an area of research in which there is still much to learn to enable a deeper understanding of the physics behind these complex flows. Data that would be of particular usefulness are at higher Reynolds numbers (Re ≥ 100,000), and dense loadings (ΦV ≥ 1%). In this work, turbulent particle-laden flow through a simplified industrial geometry was studied at an upper Reynolds number of 115,000 and particle loadings up to 5% by weight/volume (specific gravity = 1) to address these needs. The flow within a tee junction with the 90-degree branch closed-off downstream was studied. This is analogous to a duct flow but with an exposed region of fluid at the location of the closed-off branch. Super absorbent particles were used as the solid phase, which became index-matched and neutrally buoyant upon saturation with water. Data were acquired using 2-D planar particle image velocimetry (PIV) along the center span of the tunnel. Mean and root-mean-square (rms) velocities were calculated for the fluid phase. Particle loadings studied were 0%, 1%, 3%, and 5 at flow Reynolds numbers of 11,500 and 115,000. Velocity contour plots are presented to provide a macro description of the flow. Three horizontal positions within the shear layer region were selected for profile comparison (x* = −0.45, 0, 0.45). Prior literature suggested that the particles would attenuate the turbulence, however, the result showed no single trend in the current data. The mean velocities were nominally unaffected by loading for a respective Reynolds number case. Turbulence modulation of the flow was found to be sensitive to the Reynolds number, as at x* = −0.45 weakening of the rms was observed in the low Reynolds number case and strengthening in the high Reynolds number case for the same particle loading in the same region of the geometry.
A Numerical Study of Oblique Water Entry Problems
Authors: Chang Yanni , Tong Albert Y.
Published: October 2020

A series of numerical experiments have been carried out on the water entry problem of three-dimensional multi-degree-freedom cylinders. The circular cylinder was released above the water with a specified inclined angle and velocity at entry. The hydrodynamics of the water entry problem have been investigated numerically. The Piecewise Linear Interface Calculation (PLIC) schemes have been applied in conjunction with the Volume of Fluid (VOF) method to capture the interface. Overset meshes have been adopted to handle the moving object. The numerical model is built on the framework of OpenFOAM which is an open-source C++ toolbox. Numerical results have been obtained. Transient flow and pressure distributions have been generated. The presence of air entrapment which has been reported experimentally has also been confirmed in the numerical solution. The fluid physics of the oblique water entry problem such as the formation and development of the air entrapment has been explored. The transient positions and inclined angles of the moving circular cylinder have been found to be in good agreement with the experimental results. Parametric studies have been performed with major findings reported.
Evaluation of a Statistically Targeted Forcing Method for Synthetic Turbulence Generation in Large-Eddy Simulations and Hybrid RANS-LES Simulations
Authors: Shobayo Olalekan O. , Walters D. Keith
Published: October 2020

Computational fluid dynamics (CFD) results are presented for synthetic turbulence generation by a proposed statistically targeted forcing (STF) method. The new method seeks to introduce a fluctuating velocity field with a distribution of first and second moments that match a user-specified target mean velocity and Reynolds stress tensor, by incorporating deterministic time-dependent forcing terms into the momentum equation for the resolved flow. The STF method is formulated to extend the applicability of previously documented methods and provide flexibility in regions where synthetic turbulence needs to be generated or damped, for use in engineering level large-eddy and hybrid large-eddy/Reynolds-averaged Navier-Stokes CFD simulations. The objective of this study is to evaluate the performance of the proposed STF method in LES simulations of isotropic and anisotropic homogeneous turbulent flow test cases. Results are interrogated and compared to target statistical velocity and turbulent stress distributions and evaluated in terms of energy spectra. Analysis of the influence of STF model parameters, mesh resolution, and LES subgrid stress model on the results is investigated. Results show that the new method can successfully reproduce desired statistical distributions in a homogeneous turbulent flow.
Development of Ball-Enabled Miniaturized Valves for Sample Preparation and Microheaters for Pathogen Detection
Authors: Manzanas Carlos , Jiang Xiao , Lednicky John A. , Fan Z. Hugh
Published: October 2020

There have been numerous Zika virus (ZIKV) outbreaks in the past few years, representing a public health problem. The recommended tests for the diagnosis of Zika infections are performed in a laboratory setting. However, diagnostics platforms at the point-of-care (POC) are highly desirable for understanding and preventing ZIKV transmission. To address this need, we have developed a testing platform that (1) can be operated in the field for pathogen detection, (2) is rapid, cost-effective, and reliable, and (3) does not require a power supply.

To realize the platform, we have developed (1) a series of ball-based valves for the storage and sequential delivery of reagents and (2) microheater-enabled RNA amplification, both of which are integral components of this POC device. The multiple reagents are needed for virus lysis, RNA enrichment and purification. These ball-based are employed for fluid-control and they are actuated manually by sliding the unit and a pole under it, which can lift the balls. Nucleic acid amplification is then performed by a smart coffee mug that provides a constant temperature for reverse transcription loop mediated isothermal amplification (RT-LAMP), followed by colorimetric detection. We have demonstrated the detection of Zika virus in human urine and saliva samples using this testing platform.
Particle Tracking Velocimetry in Noisy Environment
Authors: Mousavisani Seyedmohammad , Kelly Scott D. , Kafashi Sajad , Smith Stuart T.
Published: October 2020

The encoded Particle Tracking Velocimetry (ePTV) is introduce in this paper as a specific approach of Particle Tracking Velocimetry (PTV). This method is applied to track particles obtained from flow images that contain significant background noise and relatively low particle density. Encoding is achieved by illuminating the flow with a series of light pulses within individual image exposures. Dependent upon the velocity, each particle will be illuminated multiple times in each image frame with spacing determined by both the pulse train timing and the particle velocity. A search algorithm is used that identifies each particle and seeks the encoded pattern with other particles in the image, repeating this until all encoded particles are found.

Based on probability analysis and finite image size an analytic model is developed to determine the ratio of true particles, false particles and those that are ‘lost’ by exiting the image frame.

This ePTV technique has been experimentally implemented to track spherical particles suspended in stationary vortices.

By using a suspension of micro-particles, subsequent imaging with encoded pulse trains provided snap-shots of the complex flow patterns. Typically, even after filtering, the images show around 100 to 200 particles from which encoded trajectories have been extracted and typically account for about 30% of the objects identified in the image.
Estimation of the Risk Zones Affected by Repeated Floods by Numerical Modeling
Authors: Radulescu Victorita
Published: October 2020

In Romania, in the last decades, was not realized any complex plan of management concerning the environmental rehabilitation of the natural riverbeds, even if there are even in present many places confronted with repeated floods. After the floods from 2004, 2005 and 2014 have been recorded in some places large deposits of sediments or contrary, in other zones with erosion and uncontrolled coastal slides. As an immediate effect, zones with risk for the local population and not only, have appeared. The present paper estimates the capacity of transport for a riverbed in natural conditions, based on the local measurements registered before and after a flood. The model is tested for a tributary of the Bistrita River, the Cracau River, near the Siret basin, an area well-known for such repeated floods sometimes even two or three recorded in the same year, as it was in 2005 and 2008. Three of these floods were confronted with human losses, many dead animals, and agricultural flooded areas. Near the analyzed watercourse there are many localities, with a high density of population. The realized numerical model for the flow with free surface was taking into account the possibility of the permanent changing of the lateral surfaces (riverbeds) during the floods. A continuous balance of the entered and transported sediments is realized, due to the erosion and sediment transportation. The time variation of the discharged liquid and the solid phases are directly connected with the sediment transport. In these conditions, the fine fractions of sediments from the bed’s structure are removed from its surface. In some places, the sediments become “armored” with the coarser part of the bed sediment. It is proposed a mathematical model to simulate the effect of both types of deposits into a fluid flow in open channels, with a movable bed. The entire alluvial stream, until the base rock, is considered with a small thickness so the non-uniformity of the grain size in the vertical distribution in riverbed could be neglected. The boundary conditions in the flood analysis consist of the upstream hydrograph and the stationary level of the downstream watercourse. Knowing the flow rate and the water levels by direct measurements, there is possible to establish the risk zones, far away from the river borders. The primary purpose of this study is to minimize the effects of such uncontrolled floods by determining the risk zones and to present a solution for increasing population safety which lives near the riverbed. Finally, some conclusions and references are mentioned.
Comprehensive Analysis of Fluid-Structure Interactive Schemes for Modeling Aircraft Water Impact Scenarios
Authors: Megharaja Suraj Jain , Bayandor Javid
Published: October 2020

Aircraft emergency water landings (ditching) are uncommon but remain an ever-present possibility. Therefore, crashworthiness standards as part of the Federal Aviation Regulations demand such situations to be accounted for during the certification phase. The criteria require aircraft to prove its ability to survive ditching and be able to float after impact for a duration long enough for the passengers to be rescued. In emergency scenarios, it is preferred to choose an open body of water as the landing location as opposed to hard terrain. It would be prohibitively expensive to test impacts of this nature to cover all required certification cases. The data collection can also be a tedious process. Due to these hindrances, performing numerical validation of aircraft water ditching (fluid-solid) interactions has become more important than ever. In case of hard terrain impact, most of the energy is absorbed by the frame of an aircraft. However, in water impacts, the initial load is distributed over the skin. As a result, the ability of an aircraft to withstand crash becomes dependent on the strength of the shear panels to allow an effective transfer of impact energy to damage-absorbing members and mechanisms before failling. Large full-scale simulations to capture the structural response of an aircraft under severe impact loading however can be computationally intensive. This work focusses on comparative analysis of numerical strategies for assessing fluid-structural Interactions. Two of the methods considered are Lagrangian, and Arbitrary Lagrangian and Eulerian (ALE) schemes.

For preliminary validations, the experimental studies performed by other research groups have been used to investigate the effect of mesh refinement and computational time on the Lagrangian and ALE schemes. These simulations will provide a basis for selecting the right formulations when developing fluid-solid interactive models for aerospace applications. Based on the results of the studies conducted, the most computationally efficient scheme was then used to perform the simulations of an aircraft fuselage section when impacting water in an emergency landing situation. The fuselage model used in this project was pre-validated against a rigid terrain experimental drop test before it was applied to the ditching studies. Overall, this investigation aims at assessing advanced modeling techniques and approaches that can pave the way for analysis-assited water impact certification and, ultimately, certification by analysis.
Thermal-Fluid Analysis and Optimization of Micro-Scale Heat Sinks With Slip Boundary Condition Using Entropy Generation Minimization Method
Authors: Pourghasemi Mahyar , Fathi Nima , Anderson Kevin R.
Published: October 2020

Performance of a micro-scale heat sink with slip boundary condition at walls is evaluated using entropy generation minimization (EGM) approach. Optimum geometrical parameters and working conditions are obtained by applying two different constraints of fixed microchannel height and constant maximum pressure drop. It has been observed that with fixed channel height constraint, the optimum aspect ratio and Reynolds number are 2.5 and 700, respectively. Slip boundary condition has negligible effect on optimum working parameters while it enhances the thermal performance of the heat sink by almost 4% at fixed height constraint. At maximum pressure drop constraint, the optimum working parameters are aspect ratio of 2.25 and Reynolds number of 850. Slip on the microchannel walls reduces pressure drop and enhances the thermal performance of the heat sink by 11%.
Performance Evaluation of a New Configuration of Direct Contact Humidification Dehumidification (DCHDH) Desalination System
Authors: Aguiar Fernando G. , Kandlikar Satish G.
Published: October 2020

In the present study, the performance of a humidification-dehumidification (HDH) desalination system with the humidifier and the dehumidifier contained in the same enclosure is evaluated. In this design the humidifier system is composed of a vertical copper tube coated with a hydrophilic air-laid paper layer in which saline water is dripped and hot water (from 42.3 to 79.4 °C) flows inside to heat the humidifier system while the dehumidifier consists of an aluminum plate with internal channels for cold water (16 °C) flow. The experimental results show a pure water production rate per unit system volume up to 19.13 L/m3h at a water temperature of 79.4 °C at the evaporator inlet and a hot water mass flow rate of 135 mL/min. This new design has potential for application in desalination systems, especially sin mall systems for use by families living in arid regions.
Active High-Throughput Micromixer Using Injected Magnetic Mixture Underneath Microfluidic Channel
Authors: Surendran Athira N. , Zhou Ran
Published: October 2020

Microfluidics has a lot of applications in fields ranging from pharmaceutical to energy, and one of the major applications is micromixers. A challenge faced by most micromixers is the difficulty in mixing within micro-size fluidic channels because of the domination of laminar flow in a small channel. Hence, magnetic field generated by permanent magnets and electromagnets have been widely used to mix ferrofluids with other sample fluids on a micro level. However, permanent magnets are bulky, and electromagnets produce harmful heat to biological samples; both properties are detrimental to a microfluidic chip’s performance. Taking these into consideration, this study proposes rapid mixing of ferrofluid using a two-layer microfluidic device with microfabricated magnet. Two microfluidic chips that consist of microchannels and micromagnets respectively are fabricated using a simple and low-cost soft lithography method. The custom-designed microscale magnet consists of an array of stripes and is bonded below the plane of the microchannel. The combination of the planar location and angle of the array of magnets allow the migration of ferrofluids, hence mixing it with buffer flow. Parametric studies are performed to ensure comprehensive understanding, including the angle of micro-scale magnets with respect to the fluidic channels, total flow rate and density of the array of magnets. The result from this study can be applied in chemical synthesis and pre-processing, sample dilution, or inducing reactions between samples and reagent.
High Speed Imaging of Bubble Interface Motion in a Tapered Microgap
Authors: Chauhan Aranya , Kandlikar Satish G.
Published: October 2020

The current industrial trend requires development of efficient heat dissipation systems. A tapered microgap on the heater surface provides an efficient pool boiling heat transfer technique in dissipating large heat fluxes. This study is focused on capturing the high-speed images of bubble nucleation, growth and expansion processes. The interface velocities are estimated by tracking the interface of the growing bubble. The insight into interface motion will help in estimating the magnitude of the expanding force and predicting the pressure recovery effect during two-phase flow in the gap. The expansion force helps in establishing high flow rates resulting in high heat transfer coefficient (HTC) and critical heat flux (CHF) values. The effect of design parameters such as taper angle and height of the microgap on the bubble growth patterns are evaluated. The results show that the bubbles are nucleated and are then confined in the narrow gap. The tapered configuration propels the leading bubble interface in the flow direction and eventually the entire bubble in that direction. The bubble motion causes liquid to enter from the narrow region of the microgap. This effect, combined with the pressure recovery resulting from the two-phase flow in the expanding section of the microgap provides a bubble pumping mechanism. This configuration results in improving both the critical heat flux and heat transfer coefficient during pool boiling.
Fundamental Insight on Morphological Changes of Graphene Nanoplatelets-Copper (GNP-Cu) Coatings: Effects of Repetitive Pool Boiling Tests
Authors: Rishi Aniket M. , Gupta Anju
Published: October 2020

Being an extremely vigorous process involving a continuous intense bubble activity, repetitive pool boiling study is essential for many industrial applications. In this work, we have utilized highly thermally conductive and highly wettable graphene nanoplatelets (GNP) to form GNP-Copper based composite coatings for enhancing the pool boiling heat transfer performance. A multi-step electrodeposition technique was implemented to develop robust coatings on the copper substrates. Repetitive pool boiling studies were conducted on the 2% GNP-Cu coating which achieved the highest CHF of 286 W/cm2 and HTC of 204 kW/m2-°C. After investigating the effect of repetitive boiling on deposited GNP layers and morphology, it was found that GNP were reduced to form r-GNP (reduced GNP) and small increment in pore sizes was observed. Additionally, with repetitive boiling, it was observed that the heat transfer coefficient was continuously increased and compared to pristine copper surface 2% GNP-Cu coating yielded ∼456% increment in HTC at the end of third repetitive test.
A Proposed Approach for Accurate Estimation of Interface Surface Area in Multiphase Simulations
Authors: Shipkowski Simon Peter , Perez-Raya Isaac , Kandlikar Satish G.
Published: October 2020

Multiphase simulations and computational methods with precisely quantified interfaces are important for variety of engineering applications. A few of these applications are: heat transfer utilizing boiling processes, optimizing combustion, and additive printing/deposition processes. In these applications, calculating the length of the interface between two phases (e.g. a vapor and liquid) is particularly critical. Errors in the calculation of the size of the interface propagate over subsequent time steps thereby producing inaccurate rates of phase-change, fluid velocities, and convection heat transfer. This work proposes a method to reduce the reduce error in interface calculations in multiphase simulations. The proposed method uses the interface inclination and the vapor volume-fraction on each computational cell to compute the interface surface area. Moreover, this work provides details on proper declaration and computation of mass transfer with the Volume-of-Fluid sharp interface tracking algorithm. The performance of the proposed approach is compared with the accepted method that estimates interface surface area with gradients of vapor volume fractions. Computer simulations of spherical bubble growth in superheated liquid demonstrate the relevance of the proposed approach. Results indicate that the errors with the accepted method could propagate to 20% (relative to the theoretical estimation) in the prediction of bubble growth rate and fluid velocities. The proposed approach leads to errors of less than 1% in the prediction of bubble growth rate and fluid velocities.
Simulation of Subcooled Flow Boiling in Manifold Microchannel Heat Sink
Authors: Luo Yang , Zhang Jingzhi , Li Wei
Published: October 2020

The manifold microchannel (MMC) heat sink has become the most popular one among emerging technologies for high heat flux thermal management because of its high surface-to-volume ratio. Even though numerous numerical studies have been performed for the single-phase flow in the MMC heat sink, researches on two-phase flow boiling/condensation in this type of microchannel is seldomly reported because of its issues with flow pattern prediction. In the present work, a numerical approach involving two-phase interface capturing, phase change and solid heat conduction is conducted for the simplified MMC unit cell model. Heat and mass transfers of Lee model and interfacial heat resistance model for phase change are validated by the single bubble growth problem. Besides, both phase-change models are shown to provide good predictions against the experimental temperature database, with all of the data points falling within −5% to +20% and −5% to +10% error bands for Lee model and interfacial resistance model, respectively. Furthermore, a liquid-vapor interface region with thin thickness and accurate interface temperature can be obtained by the interfacial resistance model coupled with homogeneous nucleation-site model.
3D Investigation of Droplet Generation in a Miniaturized Coflowing Device Using Micro-Computed Tomography
Authors: Schuler Julia , Neuendorf Laura Maria , Petersen Kai , Kockmann Norbert
Published: October 2020

For many applications, such as liquid-liquid or gas-liquid reactions, the generation of monodisperse droplets is of major interest. Therefore, knowledge about the physics of droplet formation is essential and the subject of numerous studies. Droplet formation is usually investigated using optical cameras, which makes optical accessibility necessary. Furthermore, properties defining droplet evolution is obtained from 2D images. In this work, we present a methodology for the 3D investigation of droplet formation in the laminar regime using micro-computed tomography. A special imaging concept and image processing, incorporating the use of a convolutional neural network, is presented. Water droplets are injected into a continuous polydimethylsiloxane stream in a coflowing configuration using a cannula with an inner diameter di = 800 μm and an outer diameter do = 1050 μm that is centered in a thin polymer tube with an inner diameter di = 1600 μm. Volume flow rates of polydimethylsiloxane and water are varied between 0.2 and 0.3 mL min−1. Furthermore, the influence of cannula positioning on droplet formation is investigated. Different quantitative 3D properties are extracted from the CT scans, such as droplet volume and surface of the interface. Thereby, different stages of droplet formation can be identified and the physical understanding of droplet formation is improved.
Fully-Developed Convective Heat Transfer and Pressure Drop in a Square Duct With Baffle Inserts Using CFD Analysis
Authors: Christensen Lasse U. , Holebæk Stefan , Thanabalasingham Nisanthan , Hærvig Jakob , Sørensen Henrik
Published: October 2020

The scope of this project is to investigate how the geometry of baffles affect heat transfer and pressure loss of a fluid flow at Re = 1000 through a square duct. For this purpose, Large Eddy Simulations are performed to investigate the effect of baffle height and baffle width. Focus is on the fully-developed flow that repeats itself at streamwise stations. The flow field predicted by Computational Fluid Dynamics simulations was validated using Particle Image Velocimetry.

The different designs are evaluated in terms of Nusselt number, Nu and a loss coefficient, f, which are normalised using a reference geometry consisting of a square duct without baffles. The two parameters are additionally combined into a performance parameter eta η = (Nu/Nu0)/(f / f0)(1/3).

It was found that adding baffles can result in a quadrupling of η. Reducing the height of baffles decreases heat transfer, while significantly reducing pressure loss and ultimately leading to a higher η. Reducing baffle height was also found to increase the temperature gradient at the upper wall and reduce it at the lower wall. Reducing baffle width resulted in the largest temperature gradient, but lead to poor heat transfer within the fluid.
Contact Line Pinning and Depinning Prior to Rupture of an Evaporating Droplet in a Simulated Soil Pore
Authors: Chakraborty Partha P. , Derby Melanie M.
Published: October 2020

Altering soil wettability by inclusion of hydrophobicity could be an effective way to restrict evaporation from soil, thereby conserving water resources. In this study, 4-μL sessile water droplets were evaporated from an artificial soil millipore comprised of three glass (i.e. hydrophilic) and Teflon (i.e. hydrophobic) 2.38-mm-diameter beads. The distance between the beads were kept constant (i.e. center-to-center spacing of 3.1 mm). Experiments were conducted in an environmental chamber at an air temperature of 20°C and 30% and 75% relative humidity (RH). Evaporation rates were faster (i.e. ∼19 minutes and ∼49 minutes at 30% and 75% RH) from hydrophilic pores than the Teflon one (i.e. ∼24 minutes and ∼52 minutes at 30% and 75% RH) due in part to greater air-water contact area. Rupture of liquid droplets during evaporation was analyzed and predictions were made on rupture based on contact line pinning and depinning, projected surface area just before rupture, and pressure difference across liquid-vapor interface. It was observed that, in hydrophilic pore, the liquid droplet was pinned on one bead and the contact line on the other beads continuously decreased by deforming the liquid-vapor interface, though all three gas-liquid-solid contact lines decreased at a marginal rate in hydrophobic pore. For hydrophilic and hydrophobic pores, approximately 1.7 mm2 and 1.8–2 mm2 projected area of the droplet was predicted at 30% and 75% RH just before rupture occurs. Associated pressure difference responsible for rupture was estimated based on the deformation of curvature of liquid-vapor interface.
Rsr1 Palmitoylation and GTPase Activity Status Differentially Coordinate Nuclear, Septin, and Vacuole Dynamics in Candida albicans
Authors: Bedekovic T. , Agnew E. , Brand A. C.
Published: October 2020

Understanding how single eukaryotic cells self-organize to replicate and migrate is relevant to health and disease. In the fungal pathogen,
Candida albicans
, the small GTPase, Rsr1, guides the directional growth of hyphae that invade human tissue during life-threatening infections. Rsr1 is a Ras-like GTPase and a homolog of the conserved Rap1 subfamily, which directs migration in mammalian cells. Research into how this single GTPase delivers complex intracellular patterning is challenging established views of GTPase regulation, trafficking, and interaction. Here, we show that Rsr1 directly and indirectly coordinates the spatial and temporal development of key intracellular macrostructures, including septum formation and closure, vacuole dynamics, and nuclear division and segregation, as well as whole-cell morphology by determining branching patterns. Furthermore, we categorize these functions by differential Rsr1 localization and activity state and provide evidence to support the emerging view that the cytosolic pool of Ras-like GTPases is functionally active.
Reduced Independence in Daily Living Is Associated with the Gut Microbiome in People with HIV and HCV
Authors: Taylor Bryn C. , Weldon Kelly C. , Ellis Ronald J. , Franklin Donald , McDonald Daniel , Humphrey Gregory , Bryant MacKenzie , Toronczak Julia , Schwartz Tara , Iudicello Jennifer , Heaton Robert , Grant Igor , Gianella Sara , Letendre Scott , Swafford Austin , Dorrestein Pieter C. , Knight Rob
Published: October 2020

The microbes in the gut and the chemicals they produce by metabolism have been linked to brain function. In earlier work, we showed that infection with two viruses, HIV and HCV, changed the gut microbes and metabolism in ways that were associated with a lifetime history of major depressive disorder. Here, we extend this analysis looking at a measurement of independence in daily living. We find that in individuals with HIV, whether or not they also have HCV, those who reported reduced independence were enriched in a genus of bacteria called
Bacteroides
. This result is interesting because
Bacteroides
is strongly associated with diets low in carbohydrates and high in animal protein, suggesting that diet changes may help preserve independent living in people living long-term with HIV (although clinical intervention trials would be needed in order to confirm this).
Impact of low and no alcohol beers on purchases of alcohol: interrupted time series analysis of British household shopping data, 2015–2018
Authors: Anderson Peter , Jané Llopis Eva , O’Donnell Amy , Manthey Jakob , Rehm Jürgen
Published: October 2020

Objective

To assess the impact of new low and no alcohol beers and reformulated beers in Great Britain on household purchases of grams of alcohol.

Design

Interrupted time series analysis.

Setting

Purchase data from Kantar Worldpanel’s household shopping panel for 2015–2018.

Participants

64 286 British households.

Interventions

Introduction of new no and low alcohol beers during 2017–2018 and reformulation of existing beers to contain less alcohol during 2018.

Main outcome measures

Average alcoholic strength of beer and number of grams of alcohol purchased by households.

Results

As assessed by British household purchase data, 46 new low and no alcohol beer products were introduced during 2015–2018, with a step-jump in volume purchased occurring at the beginning of March 2017 (event 1). During 2015–2018, 33 beer products were reformulated to contain less alcohol, with a step-jump in volume purchased occurring during mid-March 2018 (event 2). Interrupted time series analyses found a combined associated impact of both events with relative reductions of alcohol by volume of beer between 1.2% and 2.3%; purchases of grams of alcohol within beer between 7.1% and 10.2%; and purchases of grams of alcohol as a whole between 2.6% and 3.9%. The reductions were greater for reformulation than for the introduction of new low and no alcohol products. Reductions were independently higher for younger age groups of shoppers and for households that bought the most alcohol.

Conclusions

Even though the events were associated with significant beneficial changes, the volume of purchases of new low and no alcohol beer products (2.6% of the volume of all beers purchased during 2018) and of new reformulated beer products (6.9% of the volume of all beers purchased during 2018) was very small. This indicates that there are future opportunities to increase the volume of such products so as to reduce the harm done by alcohol.
Dynamic prediction of overall survival: a retrospective analysis on 979 patients with Ewing sarcoma from the German registry
Authors: Liu Chuchu , Rueten-Budde Anja J , Ranft Andreas , Dirksen Uta , Gelderblom Hans , Fiocco Marta
Published: October 2020

Objectives

This study aimed at developing a dynamic prediction model for patients with Ewing sarcoma (ES) to provide predictions at different follow-up times. During follow-up, disease-related information becomes available, which has an impact on a patient’s prognosis. Many prediction models include predictors available at baseline and do not consider the evolution of disease over time.

Setting

In the analysis, 979 patients with ES from the Gesellschaft für Pädiatrische Onkologie und Hämatologie registry, who underwent surgery and treatment between 1999 and 2009, were included.

Design

A dynamic prediction model was developed to predict updated 5-year survival probabilities from different prediction time points during follow-up. Time-dependent variables, such as local recurrence (LR) and distant metastasis (DM), as well as covariates measured at baseline, were included in the model. The time effects of covariates were investigated by using interaction terms between each variable and time.

Results

Developing LR, DM in the lungs (DMp) or extrapulmonary DM (DMo) has a strong effect on the probability of surviving an additional 5 years with HRs and 95% CIs equal to 20.881 (14.365 to 30.353), 6.759 (4.465 to 10.230) and 17.532 (13.210 to 23.268), respectively. The effects of primary tumour location, postoperative radiotherapy (PORT), histological response and disease extent at diagnosis on survival were found to change over time. The HR of PORT versus no PORT at the time of surgery is equal to 0.774 (0.594 to 1.008). One year after surgery, the HR is equal to 1.091 (0.851 to 1.397).

Conclusions

The time-varying effects of several baseline variables, as well as the strong impact of time-dependent variables, show the importance of including updated information collected during follow-up in the prediction model to provide accurate predictions of survival.
Effectiveness and cost-effectiveness of a virtual community of practice to improve the empowerment of patients with ischaemic heart disease: study protocol of a randomised controlled trial
Authors: González-González Ana Isabel , Perestelo-Pérez Lilisbeth , Koatz Débora , Ballester Marta , Pacheco-Huergo Valeria , Ramos-García Vanesa , Torres-Castaño Alezandra , Rivero-Santana Amado , Toledo-Chávarri Ana , Valcárcel-Nazco Cristina , Mateos-Rodilla Juana , Obaya-Rebollar Juan Carlos , García-García Javier , Díaz-Sánchez Santiago , Morales-Cobos Luis , Bosch-Fontcuberta Josep María , Vallejo-Camazón Nuria , Rodríguez-Almodovar Ana , del Castillo José Carlos , Muñoz-Balsa Marcos , del Rey-Granado Yolanda , Garrido-Elustondo Sofía , Tello-Bernabé María-Eugenia , Ramírez-Puerta Ana Belén , Orrego Carola
Published: October 2020

Introduction

Virtual Communities of Practice (VCoP) or knowledge-sharing virtual communities offer ubiquitous access to information and exchange possibilities for people in similar situations, which might be especially valuable for the self-management of patients with chronic diseases. In view of the scarce evidence on the clinical and economic impact of these interventions on chronic conditions, we aim to evaluate the effectiveness and cost-effectiveness of a VCoP in the improvement of the activation and other patient empowerment measures in patients with ischaemic heart disease (IHD).

Methods and analysis

A pragmatic randomised controlled trial will be performed in Catalonia, Madrid and Canary Islands, Spain. Two hundred and fifty patients with a recent diagnosis of IHD attending the participating centres will be selected and randomised to the intervention or control group. The intervention group will be offered participation for 12 months in a VCoP based on a gamified web 2.0 platform where there is interaction with other patients and a multidisciplinary professional team. Intervention and control groups will receive usual care. The primary outcome will be measured with the Patient Activation Measure questionnaire at baseline, 6, 12 and 18 months. Secondary outcomes will include: clinical variables; knowledge (Questionnaire of Cardiovascular Risk Factors), attitudes (Self-efficacy Managing Chronic Disease Scale), adherence to the Mediterranean diet (Mediterranean Diet Questionnaire), level of physical activity (International Physical Activity Questionnaire), depression (Patient Health Questionnaire), anxiety (Hospital Anxiety Scale-A), medication adherence (Adherence to Refill Medication Scale), quality of life (EQ-5D-5L) and health resources use. Data will be collected from self-reported questionnaires and electronic medical records.

Ethics and dissemination

The trial was approved by Clinical Research Ethics Committee of Gregorio Marañón University Hospital in Madrid, Nuestra Señora de Candelaria University Hospital in Santa Cruz de Tenerife and IDIAP Jordi Gol in Barcelona. The results will be disseminated through workshops, policy briefs, peer-reviewed publications, local/international conferences.

Trial registration number

ClinicalTrials.gov Registry (NCT03959631). Pre-results.
Long-term mortality in young and middle-aged adults hospitalised with chronic disease: a Danish cohort study
Authors: Skajaa Nils , Ording Anne Gulbech , Darvalics Bianka , Horvath-Puho Erzsebet , Sørensen Henrik Toft
Published: October 2020

Objectives

To examine the long-term outcomes for patients hospitalised with chronic diseases at age 30, 40 or 50 years.

Design

Nationwide, population-based cohort study.

Setting

All Danish hospitals, 1979–1989, with follow-up through 2014.

Participants

Patients hospitalised during the study period with one, two or three or more chronic diseases and age-matched and sex-matched persons from the general population without chronic disease leading to hospitalisation: age-30 group: 13 857 patients and 69 285 comparators; age-40 group: 24 129 patients and 120 645 comparators; and age-50 group, 37 807 patients and 189 035 comparators.

Main outcome measures

Twenty-five-year mortality risks based on Kaplan-Meier estimates, years-of-life-lost (YLLs) and mortality rate ratios based on Cox regression analysis. YLLs were computed for each morbidity level, as well as in strata of income, employment, education and psychiatric conditions.

Results

Twenty-five-year mortality risks and YLLs increased steadily with increasing number of morbidities leading to hospitalisation and age, but the risk difference with general population comparators remained approximately constant across age cohorts. In the age-30 cohort, the risk differences for patients compared with comparators were 35.0% (95% CI 32.5 to 37.5) with two diseases and 62.5% (54.3% to 70.3%) with three or more diseases. In the age-50 cohort, these differences were, respectively, 48.4% (47.4 to 49.3) and 61.7% (60.1% to 63.0%). Increasing morbidity burden augmented YLLs resulting from low income, unemployment, low education level and psychiatric conditions. In the age-30 cohort, YYLs attributable to low income were 2.4 for patients with one disease, 6.2 for patients with two diseases and 11.5 for patients with three or more diseases.

Conclusions

Among patients with multiple chronic diseases, the risk of death increases steadily with the number of chronic diseases and with age. Multimorbidity augments the already increased mortality among patients with low socioeconomic status.
Prognostic factors in metastatic breast cancer: a prospective single-centre cohort study in a Finnish University Hospital
Authors: Karihtala Peeter , Jääskeläinen Anniina , Roininen Nelli , Jukkola Arja
Published: October 2020

Objectives

Although novel early breast cancer prognostic factors are being continuously discovered, only rare factors predicting survival in metastatic breast cancer have been validated. The prognostic role of early breast cancer prognostic factors in metastatic disease also remains mostly unclear.

Design and setting

Prospective cohort study in a Finnish University Hospital.

Participants and outcomes

594 women with early breast cancer were originally followed. Sixty-one of these patients developed distant metastases during the follow-up, and their primary breast cancer properties, such as tumour size, nodal status, oestrogen receptor (ER) and progesterone receptor expression, grade, proliferation rate, histopathological subtype and breast cancer subtype were analysed as potential prognostic factors for metastatic disease.

Results

In multivariate analysis, the presence of lymph node metastases at the time of early breast cancer surgery (HR, 2.17; 95% CI, 1.09–4.31; p=0.027) and ER status (negative vs positive, HR, 2.16; 95% CI, 1.14–4.10; p=0.018) were significant predictors of survival in metastatic disease.

Conclusions

These results confirm ER status as a primary prognostic factor in metastatic breast cancer. Furthermore, it also suggests that the presence of initial lymph node metastases could serve as a prognostic factor in recurrent breast cancer.