bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Analysis of Shell and Tube Type Heat Exchanger Based on Bell Delaware, Flow Stream and Numerical Methods
Authors: Khan Tariq S. , Fawad Hasan , Nawaz Kashif
Published: October 2020

An optimized heat exchanger design is always a challenge to designers. This study presents a simplified simulation study on thermal-hydraulic of a small heat exchanger. Both the heat transfer coefficient and pressure drop are simulated for a nine tube shell and tube heat exchanger. A detailed mesh sensitivity analysis is performed to arrive at numerically converged solution. The results of the study are compared with Bell Delaware (BD) and Flow Stream (FS) analytical methods. Results obtained using all three methods show similar trends. Heat transfer coefficient determined using Bell Delaware method is found to be in good agreement with that of ANSYS CFX, whereas pressure drop calculated using Flow stream method is within small percentage difference with CFX results. Overall, the simulation results are verified by the results obtained using analytical methods.
Particle Concentration Variation for Inflow Profiles in High Reynolds Number Turbulent Boundary Layer
Authors: Rahman Mustafa M. , Samtaney Ravi
Published: October 2020

Large-eddy simulations (LES) of incompressible turbulent boundary-layer flows can simulate a fundamental unsteady turbulent flow, including time-variant streamwise and wall-normal velocity as well as the near-wall locations of significant turbulence intensities. A typical illustration of turbulent flows with such high Reynolds numbers can be roughly approximated to atmospheric boundary-layer flows. To bypass the demanding mesh criteria of near-ground field and direct numerical simulations, we adopt a virtual-wall model with a stretched-vortex subgrid-scale model. We simulate the dynamics of solid particles in this wall-modeled LES approach toward incompressible flow. The particles considered are both charged and uncharged, and have a fixed concentration profile with no fluctuations at the inflow. An extended streamwise simulation domain is implemented as an alternative to rerunning the simulation with a turbulent inflow profile from the simulation of the previous downstream profile. By extending the streamwise domain, the fluctuation dynamics of the particles reach a steady state far downstream from the inflow. The streamwise and altitude variation of the particle parameters are compared for various particle-concentration inflow profiles. Furthermore, an estimate of the streamwise variation of parameters is also observed. This study is the first step towards enhancing our understanding of the particle dynamics in turbulent flows.
Wake Comparison of Open and Ducted Wind Turbines Using Actuator Disc Simulations
Authors: Bagheri-Sadeghi Nojan , Helenbrook Brian T. , Visser Kenneth D.
Published: October 2020

Shrouding a wind turbine inside a duct can significantly augment its power and energy output by increasing the mass flow rate through the rotor and decreasing the cut-in speed. Whether this is an advantage in a turbine array depends on the wake recovery behavior and how this compares to open wind turbines. Axisymmetric CFD simulations using the Reynolds-Averaged Navier-Stokes equations with a k–ω SST turbulence closure were used to compare the wake behavior of open and ducted wind turbines. For both cases, the rotor blades were modeled using an actuator disc. Simulations of open wind turbines revealed significant sensitivity of the wake behavior to the mean turbulence intensity at the rotor. Better agreement with experimental data for the far wake was obtained when the turbulence intensity at the rotor was comparable to values measured experimentally. It was observed that compared to an open wind turbine with similar power output, a DWT has a significantly slower wake recovery. This was attributed to the extra momentum deficit of the wake due to the drag force on the duct.
On the Potential for Low-Frequency Control Valve Vibrations Being Caused by Upstream Oscillating Dean Vortexes
Authors: Lozowy Richard , Forcinito Mario
Published: October 2020

At several natural gas compressor stations control valves have experienced low-frequency vibrations when placed directly downstream of pipe bends. It is know that at pipe bends a pair of counter-rotating vortexes form and extend several diameters downstream. These vortexes are not symmetric and instead oscillate back and forth at a low-frequency phenomenon referred to as swirl-switching. It is suspected that these upstream flow oscillations enter the valve and are the cause of the valve vibrations. Large-eddy simulations have been performed on pipe bends with two different bend radius at a Reynolds number of 80,000. The simulations showed that the frequency of the vortexes decreased as the bend radius increased. When non-dimensionalized the frequency obtained from the simulation is comparable to the field measurement from the compressor station. This consistency provides support to the argument that upstream flow-induced oscillations are the cause of the low-frequency valve vibrations. The velocity fluctuations due to swirl-switching dissipate downstream of the bend and by placing several diameter lengths of straight pipe between a control valve and a pipe bend, the issue of low-frequency vibrations induced at the valve could be avoided. The objective of this study is to provide evidence that low-frequency valve vibrations can be linked to upstream pipe geometry and put forward a plausible explanation of why.
Turbulent Flow Measurements and Visualizations of Supersonic Jets Impinging on a Flat Plate and an Inclined Plate
Authors: Nguyen Thien D. , Maher Blake , Hassan Yassin A.
Published: October 2020

This study experimentally investigates the flow characteristics of a high-pressure air jets impinging on a flat plate and an inclined plate with various nozzle-to-plane gaps of 10 mm, 20 mm, and 30 mm. Full-field measurements of flow characteristics in the central plane of the nozzle and near the impinging surface are performed using two-dimensional two-component (2D2C) particle image velocimetry (PIV) technique. This paper presents results from the nozzle pressure ratio (NPR) of 2.77, approximately yielding the sonic jet with Mach number of 1.2. Flow characteristics obtained from the 2D2C-PIV measurements with various spatial gaps are compared and presented. Results including the first- and second-order flow statistics, such as mean velocity and turbulent kinetic energy, and effects of the impinging surface to the flow patterns are investigated. Finally, proper orthogonal decomposition (POD) analysis is applied to reveal the statistically dominant flow structures that capture the highest amount flow kinetic energy and play important roles to the flow dynamics and heat transfers.
Rheological Measurement of the Gelation Temperature of Thermoresponsive Hydrogels: A Tutorial Using Pluronic F127
Authors: Zhang Haipeng , Ryu Sangjin , Ren Rongguo , Wang Dong
Published: October 2020

Pluronic F127 is a thermoresponsive hydrogel well used for various pharmaceutical applications. An emulsion of F127 can be gelated by heating the mixture, and this thermoresponsive gelation property enables local drug delivery. Thus, it is important to measure the gelation temeperature of F127 and similar thermoresponsive hydrogels for characterizing their gelation process for such applications.

Gelation temperature (Tgel) is a temperature threshold indicating the presence of network formation in F127 and similar thermoresponsive hydrogel materials. A widely used method for Tgel measurement is to measure Tgel based on changes in the storage modulus (G′) and loss modulus (G″) of the hydrogel with respect to temperature. However, this rheological measurement requires careful choices of measurement conditions. In this paper, we present the detailed tuning steps and results of our rheological Tgel measurement of F127 using a rotational rheometer as a tutorial for other researchers.

First, oscillation strain sweep measurements were performed to determine an optimum strain value in the linear viscoelastic region. Second, oscillation frequency sweep measurements were conducted to choose a reasonable oscillation frequency value. Third, G′ and G″ of F127 (25% w/v) were measured in the oscillation temperature sweep mode for the temperature range of 5°C to 45°C with the determined shear strain (0.1%) and oscillation frequency (1 rad/s). Last, Tgel was determined based on the crossover between measured G′ and G″ curves. Additionally, we compared the temperature sweep mode and the temperature ramp mode, and investigated effects of preshearing duration on repeated G′-G″ measurement and Tgel determination. The summarized procedure can be used as a reference to perform reliable and repeatable rheological Tgel measurement of thermoresponsive hydrogel materials.
A LES Study of Ventilation Flow Through a 3-D Room Fitted With Solar Chimney
Authors: Huynh B. Phuoc
Published: October 2020

Solar chimney (thermal chimney) is a device which absorbs solar radiation to heat the air. The heated air, becoming buoyant, rises through the chimney’s passage and induces further air currents. When fitted to a building, solar chimney can thus induce fresh outside air to flow through the building for ventilation. Because only natural means (solar radiation here) are involved to cause the air flow, solar chimney is considered a natural-ventilation device. This work investigates computationally natural ventilation induced by a roof-mounted solar chimney through a real-sized 3-dimensional room, using a commercial CFD (Computational Fluid Dynamics) software package which employs the Finite Volume Method. A LES (Large-Eddy Simulations) formulation with Smagorinsky SGS (Sub-Grid Scale) model is used. All fluid properties are assumed to be constant and corresponding to those of air at 300K (27°C, constant ambient temperature) and standard pressure at sea level (101.3kPa); but Boussinesq approximation (wherein temperature change affects only the fluid density pertaining to buoyancy force) is also assumed. Comparison is made with computational results obtained from a RANS (Reynolds-Averaged Navier-Stokes) formulation. Agreement between LES and RANS results indicate the trustworthiness of CFD methods used.
Fluid-Structure Interaction Modeling and Validation of Idealized Left Ventricular Blood Flow
Authors: Laughlin Megan , Stephens Sam , Jensen Hanna , Jensen Morten , Millett Paul
Published: October 2020

Fluid Structure Interaction (FSI) models are an essential tool in understanding the complex coupling of blood flow in the heart. The objective of this study is to establish a method of comparing data obtained from FSI models and benchtop measurements from phantoms to identify sources of flow changes for use in intraventricular flow analysis.

Two geometries are considered: 1) a vascular model consisting of a straight channel with an ellipsoidal swell and 2) an idealized left ventricle (LV) model representative “acorn” shape. Two phantoms are created for each of the two geometries: 3D printed rigid phantoms from a resin and custom-made tissue-mimicking phantoms from a medical gel. Benchtop measurements are made using the phantoms within a custom flow loop setup with pulsatile flow.

Computational Fluid Dynamics (CFD) simulations are conducted with a Smoothed Particle Hydrodynamics (SPH) model. The two flow channel geometries utilized in the experiments are replicated for the simulations. The cavity walls are defined by ghost particles that are rigidly fixed.

Maximum pressure drops were 57 mmHg and 196 mmHg for the rigid swell and rigid LV, respectively, whereas maximum pressure drops were 155 mmHg for the gel swell and 140 mmHg for the gel LV. Calculations from the simulations resulted in a maximum pressure drop of 55 mmHg for the swell and 110 mmHg for the LV. This data serves as a first step in corroborating our methodology to utilize the information obtained from both methods to identify and better understand mutual sources of changes in flow patterns.
Modeling the Effect of Spacer Grid and Mixing Vanes in Coupled CFD Simulations of Small Modular Reactors
Authors: Fang Jun , Shaver Dillon , Merzari Elia
Published: October 2020

Complex flow structure interaction and heat transfer process take place in the nuclear reactor cores. Given the extreme pressure/temperature and radioactive conditions in the core, numerical simulations offer an attractive (and sometimes more feasible) approach to study the related flow and heat transfer phenomena compared to experiments. Meanwhile, the rapid development and deployment of high-performance computing (HPC) facilities are helping unlock the even greater potential of massively parallel numerical simulations. Under the Exascale Computing Project, this study aims to develop suitable momentum sources that can reproduce the effects of spacer grid and mixing vanes (SGMV) on the core coolant flow. The ultimate project goal is to simulate the full core of a small modular reactor (SMR) with coupled thermal-hydraulics and neutronics. Modeling the SGMV effect without body-fitted computational grid avoids the excessive costs in resolving the local geometric details, and supports all the simulation to be scaled up to larger domain sizes. Thus, it is a crucial steppingstone to achieve the full core simulation on upcoming exascale supercomputers. This paper presents the preliminary results on the momentum source modeling as well as the roadmap for future research.
A Numerical Study of Mesh Type, Size, and Near Wall Grid Thickness Effect on Performance and Erosion Simulations in an Electrical Submersible Pump (ESP)
Authors: Zhu Haiwen , Lin Zimo , Peng Jianlin , Zhang Hong-Quan , Zhu Jianjun , Zhang Jun
Published: October 2020

The performance of multi-stage Electrical Submersible Pumps (ESPs) under different flow conditions and its life span with sand production are commonly predicted by the Computational Fluid Dynamics (CFD) simulations. The mesh generation methodology and optimum grid number are usually validated by pump water catalog curves. Then, the validated mesh geometry is adopted in high viscosity, multiphase flow, and sand erosion simulations to study the effects including but not limited to: discrete phase bubble diameter, turbulence model, body forces, and erosion models. However, the mesh validation by pump water curves is not enough in complex flow conditions, especially in the erosion simulations. Different from the pump hydraulic performance simulation, the accuracy of the erosion simulation can be affected by mesh boundary and inner layer grid thickness, especially for small particles. In addition, the mesh-type (hexahedral and tetrahedral) and size of the inner domain can also significantly affect the particle trajectory. A comprehensive mesh independent study is conducted for water, oil, and gas-liquid conditions of a mixed type ESP in this paper. Then the near-wall inflation layer thickness and inner domain grid size effect to ESP erosion simulation are well analyzed. The mesh generation methodology can be applied to other turbomachinery simulations to improve accuracy.
A Comparative Study of Interpolation Schemes in Overset Meshes for the PLIC-VOF Method in Multiphase Flows
Authors: Chang Yanni , Dai Dezhi , Tong Albert Y.
Published: October 2020

Piecewise Linear Interface Calculation (PLIC) schemes have been extensively employed in the Volume-of-Fluid (VOF) method for interface capturing in numerical simulations of multiphase flows. Dynamic overset meshes can be especially useful in applications involving component motions and complex geometric shapes. The basic idea of the overset mesh is the variable field interpolation within the overlapped region between the background and body meshes. The acceptor cell value is evaluated by a weighted average of its donors. The weighting factors are calculated by different algebraic methods, such as the averageValue, injection and inverseDistance schemes, which are implanted in the foam-extend library. A geometric interpolation scheme of the VOF field in overset meshes for the PLIC-VOF method has been proposed in the present study. The VOF value of an acceptor cell is evaluated geometrically with the reconstructed interfaces from the corresponding donor elements. Test cases of advecting liquid columns of different shapes inside a unit square/cube with a prescribed rotational velocity field have been performed to demonstrate the accuracy of the proposed overset interpolation scheme by comparing it with three algebraic ones. The proposed scheme has been shown to yield higher accuracy.
Analyzing the Characteristics of the Turbulent Vortices at Fast Rolling on Solid Surfaces
Authors: Radulescu Victorita
Published: October 2020

The present paper illustrates a new method for solving the two-dimensional turbulent fluid flow, for an incompressible fluid, near solid walls. Equations of energy conservation and momentum for thin layers have been used and solved with a slip velocity implemented in the Navier-Stokes equations. As a first step, a pseudo-laminar analysis was made. In parallel, some other models for turbulence were analyzed, to estimate the most appropriate model in conformity with the obtained experimental results. The numerical simulation was performed to investigate the effects of the Reynolds number on the flow characteristics, over a two-dimensional rectangular body and a curved shape surface. It was used the CFD, near the solid surfaces with a strong adverse pressure gradient. The viscous layer is expressed as an integral solution, imposing the wall shear stress as a boundary condition on solid surfaces. The velocity and shear stress are deduced from the Navier-Stokes equations as long as the convergence is reached. Numerical modeling was tested for Reynolds numbers ranging from 2040 to 13000. Firstly, the theoretical model for the flow equations and velocity distribution is described. Some details are presented for estimating as better as possible the wall velocity and the shear stresses. Numerical modeling, with the FEM model, is based on the Galerkin formulation. Some aspects referring to the boundary conditions, for the analyzed cases are also mentioned. The flow is restricted at a central vortex, considered the primary vortex. In turbulent boundary layer, for the analyzed applications were not considered the axial vortices. Some aspects referring to the flow domain and the grid generation are mentioned in a dedicated paragraph. For numerical modeling, firstly was adopted the non-viscous solution, as the initial condition. It depends on the available information concerning the shapes geometry, the curvature radius, and the flow conditions for the considered problems. For the first approximation, was used the integral boundary-layer method, which can provide a proper solution. The advantage consists of reducing the number of iteration to reach the numerically final settlement. If it will be used the integral method, will be provided only an approximate distribution for the edge velocity. Variation of the reattachment length of vortices over the analyzed solid bodies is correlated with the experimental results from the literature. Exclusive analysis of the selected data shows that the turbulent values correlated directly to the body length-b are more accurate than those referring to the dimensionless rapport δ/b. From the analyzed models, the K-ε model presents better agreement with experimental data, also for the negative values of the Reynolds shear stress in the re-attachment point. Finally, some conclusions and references are mentioned.
A Hepatic Sinusoids-Based Microreactor for Photocatalytic Degradation of Methylene Blue by Titanium Dioxide
Authors: Shouman Mahmoud A. , El-Shazly Ahmed H. , Salem Mohamed S. , Elmarghany Mohamed R. , Abo-Zahhad Essam M. , Elkady Marwa F. , Sabry Mohamed Nabil , Radwan Ali
Published: October 2020

Microreactor technology is considered a state of art technology that gained great attention from researchers due to the high effectiveness and the small residence time compared with other regular reactors. Great research work has been established to involve microreators in a variety of applications, including fuel production, food and chemical industries, medical applications. In the present study, a hepatic sinusoids-based microreactor is experimentally tested in Methylene blue degradation using titanium dioxide (TiO2) photocatalyst activated with ultraviolet lamp of wavelength 365 nm. Purification of water using photocatalysis is considered a promising technology that attract the industrial community. Different operating conditions are investigated including; flow rate, Methylene blue concentration, and TiO2 concentration. 3 different dye concentrations are used (10 ppm, 20 ppm, and 30 ppm) with 3 different photocatalyst concentrations (100 ppm, 300 ppm, and 500 ppm). The flow rate has a span from 0.25 ml/min to 1 ml/min. Experiments are conducted to determine best operating conditions. Results show that the microreactor system can be effectively used in dye degradation with a very small residence time. A degradation of over 95% was reached at a TiO2 concentration of 300 ppm and a flow rate of 0.25 ml/min for all tested dye concentrations.
Numerical and Experimental Investigation on Evaporation of Water Droplet on Surfaces With Mixed Wettability
Authors: Aboubakri Akam , Yanik Cenk , Akkuş Yiğit , Koşar Ali , Sadaghiani Ali K.
Published: October 2020

Droplet evaporation is one of the most commonly observed phenomena and plays an important role in many applications such as in spray cooling, coating, and inkjet printing. Mechanisms such as dynamics of the contact line, evaporation-induced phase transitions, and formation of patterns on the substrate interact with each other in the evaporation of droplets. In this study, we investigated the effect of surface mixed wettability on water sessile droplet evaporation. The transient contact angle, center-height, contact radius, surface area, and droplet volume were experimentally measured and numerically estimated. Surfaces with mixed wettability consisting of hydrophilic islands surrounded by less hydrophilic area were fabricated. Visualization was conducted to capture droplet dynamics during evaporation using two high-speed cameras. According to the obtained results, there were three distinct stages in the water evaporation process: a constant contact radius mode, a constant contact angle mode, and a mixed-mode. The COMSOL 5.4 software was used for numerical analysis. According to the results, the receding contact angle and Marangoni instability in the droplet are two main factors that alter droplet dynamics and droplet evaporation.
Streamer Formation in Particle Laden Polymeric Flows
Authors: Chandra Navin Kumar , Kumar Aloke , Ghosh Ranajay
Published: October 2020

Particle laden polymeric flows are of interest to the fluid mechanics community due to the possibility of flow induced aggregation and structure formation. Here, we show that when particle laden polymeric suspensions flow through an annular area at moderate Reynolds numbers (∼ 10) and Weissenberg numbers (∼ 10−2–10−1), it can result in formation of flow induced structures. Specifically, the particle can aggregate in the form of thin slender, flexible structures called streamers. The name ‘streamer’ is inspired by their slender morphology which is similar to bacterial streamers formed in bacterial aggregation subjected to continuous hydrodynamic flow. In the present work, polyethylene oxide (PEO) and dry gram flour has been used to create particle laden polymeric fluid suspension. The Taylor-Couette geometry has been modified by employing a stationary needle in the annular space to study the effect of varying hydrodynamic conditions on streamer formation and their morphology. Experimental observations show that depending on the polymer to particle concentration ratio (Cpolymer/Cparticle) and the hydrodynamic condition, different morphologies of streamers can be obtained. This is collated in the form of a state diagram. Surprisingly, it is observed that aged polymeric suspensions enhance streamer formation when employed in conjunction with gram flour powder that function as colloidal particles. Zeta potential and rheological measurements have been performed to gain further insights on the change in properties of polymer on account of ageing.
Contribution to the knowledge of the oribatid mite subgenus Galumna (Neogalumna) (Acari, Oribatida, Galumnidae) with description of a new species from Inner Mongolia, Northeast China

Authors: Pan Xue , Liu Dong
Published: October 2020

The subgenus Galumna (Neogalumna) (Oribatida, Galumnidae) was represented by only one species in China prior to this work. During investigation of farmland soil biodiversity in eastern China in 2019, a new species, Galumna (Neogalumna) tongliaoensis sp. nov., was found from soil of corn farmland in Naiman Banner, Inner Mongolia. Galumna (Neogalumna) tongliaoensis sp. nov. can be distinguished from other congeneric species by the following combination of features: bothridial setae with narrow fusiform and barbed head; interlamellar setae extremely short; lamellar and sublamellar lines curving backwards, parallel; four pairs of porose areas oval or circular; genital plates smooth, with large distance between setae g4 and g5; postanal porose absent. An updated identification key with data on distribution of known species of the subgenus is presented to facilitate the further study on this group.
Antifungal Effects of Drimane Sesquiterpenoids Isolated from
Drimys winteri
against Gaeumannomyces graminis var. tritici
Authors: Paz Cristian , Viscardi Sharon , Iturra Andres , Marin Victor , Miranda Felipe , Barra Patricio Javier , Mendez Isabel , Duran Paola
Published: October 2020

More than two billion tons of pesticides are used every year worldwide. An interesting sustainable alternative to control plant pathogens is the use of natural products obtained from plants, mainly medicinal plants that offer secondary metabolites important to human/animal health. In this study, we isolated and identified six pure drimane sesquiterpenoids obtained from the bark of
Drimys winteri
. Additionally, we evaluated their antifungal activities against
Gaeumannomyces graminis
(the main biotic factor affecting cereal production, especially wheat) by assessing fungal cell wall damage and lipid peroxidation. The compounds obtained showed important antifungal properties against
G. graminis
var. tritici, mainly isodrimenol, which was the second-most-active compound after polygodial, with an LC
50
against
G. graminis
var. tritici of around 9.5 μg ml
−1
. This information could be useful for the development of new natural or hemisynthetic antifungal agents against soilborne phytopathogens that could be used in green agriculture.
Invertases in Phytophthora infestans Localize to Haustoria and Are Programmed for Infection-Specific Expression
Authors: Kagda Meenakshi S. , Martínez-Soto Domingo , Ah-Fong Audrey M. V. , Judelson Howard S.
Published: October 2020

Oomycetes cause hundreds of diseases in economically and environmentally significant plants. How these microbes acquire host nutrients is not well understood. Many oomycetes insert specialized hyphae called haustoria into plant cells, but unlike their fungal counterparts, a role in nutrition has remained unproven. The discovery that
Phytophthora
invertases localize to haustoria provides the first strong evidence that these structures participate in feeding. Since regions of proteins containing signal peptides targeted proteins to the haustorium-plant interface, haustoria appear to be the primary machinery for secreting proteins during biotrophic pathogenesis. Although oomycete invertases were acquired laterally from fungi, their expression patterns have adapted to the
Phytophthora
lifestyle by abandoning substrate-level regulation in favor of developmental control, allowing the enzymes to be produced in anticipation of plant colonization. This study highlights how a widely distributed hydrolytic enzyme has evolved new behaviors in oomycetes.
Screen Time, Social Media Use, and Adolescent Development
Authors: Odgers Candice L. , Schueller Stephen M. , Ito Mimi
Published: October 2020

Adolescents spend much of their daily lives online, and fears abound that digital technology use, and social media in particular, is harming their social and emotional development. Findings to date do not support causal or robust associations between social media use and adolescents’ development. Instead, prior studies have produced a mix of small positive, negative, and often null associations. The narrative around social media and adolescent development has been negative, but empirical support for the story of increasing deficits, disease, and disconnection is limited. This article reviews what is known about the association between social media use and adolescent social and emotional well-being, identifies key limitations in current research, and recommends ways to improve science while also minimizing risk and creating opportunities for positive development in an increasingly digital and uncertain age.
A Case Demonstrating the Pathological Relationship between Granulomatous Vasculitis and Glomerular Lesion in Renal Sarcoidosis
Authors: Kamata Yoshinori , Sato Hiroshi , Sugiura Akira , Miyata Masahiro , Kisu Kiyomi , Azuma Arata
Published: October 2020

We experienced a rare case of tubulointerstitial angiocentric granulomatous vasculitis with focal segmental glomerulosclerosis (FSGS) and associated sarcoidosis. Our patient was an 18-year-old man who presented with exertional cough and dyspnea. He also had overt proteinuria (3.0 g/24 h), normal renal function (eGFR 95 mL/min/1.73 m2), heart failure, and hypertension. He had no previous episode of hypertension. These manifestations immediately improved after the administration of antihypertensive therapy that contained an angiotensin-converting enzyme inhibitor, calcium antagonists, beta antagonists, and diuretics. However, he, later on, developed renal dysfunction, with worsening of both proteinuria and hypertension. Renal biopsy was performed and showed epithelioid cells that were arranged concentrically around small blood vessels in tubulointerstitial granulomas. In the glomeruli, the segmental sclerotic lesions were classified as a perihilar variant of FSGS. There were no inflammatory changes, such as a mesangial lesion, inflammatory cell infiltration, fibrinoid necrosis, or crescent formation, and no glomerular granuloma. In the tubulointerstitial granulomas, the intimal elastic lamina of the interlobular arteries was reduplicated, and the intimal wall thickness of renal arterioles was remarkable. After receiving oral prednisolone therapy, the overt proteinuria resolved, the eGFR recovered from 39.4 to 60.6 mL/min/1.73 m2, and hypertension was managed more easily. Thereafter, he did not experience any recurrence. The concurrent improvement of renal function and proteinuria by steroid treatment suggested a relationship between the glomerular lesions and the tubulointerstitial granulomatous vasculitis with associated sarcoidosis.
Quantitative Morphology of Cerebral Thrombi Related to Intravital Contraction and Clinical Features of Ischemic Stroke
Authors: Khismatullin Rafael R. , Nagaswami Chandrasekaran , Shakirova Asia Z. , Vrtková Adéla , Procházka Václav , Gumulec Jaromír , Mačák Jiří , Litvinov Rustem I. , Weisel John W.
Published: October 2020

Background and Purpose:

The purpose was to assess quantitatively and qualitatively the composition and structure of cerebral thrombi and correlate them with the signs of intravital clot contraction (retraction), as well as with etiology, severity, duration, and outcomes of acute ischemic stroke.

Methods:

We quantified high-resolution scanning electron micrographs of 41 cerebral thrombi for their detailed cellular and noncellular composition and analyzed histological images for the overall structure with the emphasis on red blood cell compression, fibrin age, and the signs of inflammation.

Results:

Cerebral thrombi were quite compact and had extremely low porosity. The prevailing cell type was polyhedral compressed erythrocytes (polyhedrocytes) in the core, and fibrin-platelet aggregates were concentrated at the periphery; both findings are indicative of intravital contraction of the thrombi. The content of polyhedrocytes directly correlated with the stroke severity. The prevalence of fibrin bundles was typical for more severe cases, while the content of fibrin sponge prevailed in cases with a more favorable course. The overall platelet content in cerebral thrombi was surprisingly small, while the higher content of platelet aggregates was a marker of stroke severity. Fibrillar types of fibrin prevailed in atherothrombogenic thrombi. Older fibrin prevailed in thrombi from the patients who received thrombolytics, and younger fibrin dominated in cardioembolic thrombi. Alternating layers of erythrocytes and fibrin mixed with platelets were common for thrombi from the patients with more favorable outcomes. Thrombi with a higher number of leukocytes were associated with fatal cases.

Conclusions:

Most cerebral thrombi undergo intravital clot contraction (retraction) that may be of underestimated clinical importance. Despite the high variability of the composition and structure of cerebral thrombi, the content of certain types of blood cells and fibrin structures combined with the morphological signs of intravital contraction correlate with the clinical course and outcomes of acute ischemic stroke.
Higher-Order Cognition Does Not Affect Multisensory Distractor Processing
Authors: Merz Simon , Jensen Anne , Burau Charlotte , Spence Charles , Frings Christian
Published: October 2020

Multisensory processing is required for the perception of the majority of everyday objects and events. In the case of irrelevant stimuli, the multisensory processing of features is widely assumed to be modulated by attention. In the present study, we investigated whether the processing of audiovisual distractors is also modulated by higher-order cognition. Participants fixated a visual distractor viewed via a centrally-placed mirror and responded to a laterally-presented audiovisual target. Critically, a distractor tone was presented from the same location as the mirror, while the visual distractor feature was presented at an occluded location, visible only indirectly via mirror reflection. Consequently, it appeared as though the visual and auditory features were presented from the same location though, in fact, they actually originated from different locations. Nevertheless, the results still revealed that the visual and auditory distractor features were processed together just as in the control condition, in which the audiovisual distractor features were both actually presented from fixation. Taken together, these results suggest that the processing of irrelevant multisensory information is not influenced by higher-order cognition.
Paraleptopentacta, a new Mediterranean and north-west Atlantic sea cucumber genus, with the first record of P. tergestina n. comb. (Echinodermata: Dendrochirotida: Cucumariidae) from the north-western Algerian coast
Authors: MEZALI KARIM , THANDAR AHMED S. , KHODJA IHCENE
Published: October 2020

The genus Leptopentacta H.L. Clark, 1938 is here reviewed and restricted to include only the type species and related tropical Pacific forms, while a new genus Paraleptopentacta is erected to accommodate the Mediterranean and some north-west Atlantic species, formerly assigned to Leptopentacta. Paraleptopentacta n. gen. is characterized by a calcareous ring usually without posteriorly forked radial plates, in combination with body wall ossicles as an external layer of baskets (sometimes absent) and an inner layer of smooth (in one species knobbed), single-layered, multilocular plates, without a reticulum, as opposed to Leptopentacta H.L. Clark, 1938, which always has forked tails to the radial plates and ossicles as an external layer of rosettes and/or baskets and an inner layer of multi-layered or often reticulated scales/plates. A key separating both the genera and their species is provided. In addition, a first record of P. tergestina n. comb. (Sars, 1859), based on individuals collected as bycatch by a commercial benthic trawler in the Mostaganem region, north-west Algeria, is briefly described and its in vitro behavior noted.
The Shifting Sands of Citizenship: Dispossessions, Constitutional Ruptures and Borderlands*
Authors: Kannabiran Kalpana
Published: October 2020

This article looks at dispossession through four trajectories—segregation/‘untouchables’; eviction/‘encroachers’; de-citizenisation/‘illegal interlopers’; occupation/ ‘anti-nationals’—each of which destabilise the foundational basis of citizenship, and contain gendered reverberations. Violence and structural inequalities lie at the core of state practice, temper constitutional prerogatives and fuel dispossession. Impunity lies at the heart of these processes. Each of these four methods speak to a historical specificity, have distinct consequences and afterlives, different affects and engender distinct modes of resistance. The articulation of the basic idea of dispossession in these terms I argue is itself recall of the tremendous corpus of writing from the borderlands and recall of border imaginings that help us make meaning of territories by dispossession. The four-pronged rupture of constitution-speak jeopardises the constitutional imagination of the nation and affects the very claim to citizenship in the borderlands as set out within the contours the constitution.
Ketamine/Xylazine Anesthesia–Related Corneal Lesions in Rats With Surgically Implanted Venous Catheters Utilized in Nonclinical Intravenous Studies
Authors: Zwick Laura S. , Patrick Daniel J. , Knupp Lauren C. , Ramos Meg F.
Published: October 2020

Nonclinical rodent studies with repeat slow intravenous dosing, such as safety assessments of anticancer therapeutics, often require the use of animals with surgically implanted catheters. Catheterization is a relatively short surgical procedure but requires use of anesthesia. Ketamine/xylazine injectable anesthesia is typically used because it has advantages over inhalation anesthesia including ease of administration, safety and predictability of effects, and relatively low cost. However, ketamine/xylazine anesthesia in rodents can also be associated with the development of undesirable corneal lesions of uncertain mechanism such as mineralization of Bowman’s membrane or stroma, erosion/ulceration, inflammation, fibroplasia, and neovascularization. Such findings have the potential to confound study interpretation in programs for which the cornea is a potential target tissue. This case report describes the occurrence of ketamine/xylazine-related corneal lesions observed in surgically catheterized rats in a 16-day toxicity study for an oncology compound.
When do coalitions form under presidentialism, and why does it matter? A configurational analysis from Latin America
Authors: Albala Adrián
Published: October 2020

This article proposes a new approach to the study of coalition formation in presidential regimes. Drawing on a dataset covering 33 Latin American governments, the article shows that coalition cabinets are, mostly, the product of pre-electoral agreements. I present a six-stage timing of coalition agreements, including four degrees of earliness. Then, I challenge this consideration with the most common – institutional – arguments from the literature about the survival of coalitions in presidential regimes. The findings are quite interesting since they point out that earlier agreements are relevant conditions for enduring coalitions. Moreover, and surprisingly, I show that the institutional argument seems to have been overrated by the literature.
Psychological factors involved in the acquisition of a foreign language among students with visual impairments
Authors: Krisi Miri , Nagar Revital , Knoll Nira
Published: October 2020

This study presents a qualitative analysis of the psychological factors affecting the academic success of students with visual impairments, focusing on the students’ perceptions of their own competence and abilities in learning a foreign language. Interviews were conducted with 28 first-year college students in Israel who met the standard definition of being legally blind. Data were analyzed using a content analysis technique. This was conducted in two stages: first a within-case analysis and then a cross-case analysis. Three distinct themes emerged from the data: (1) self-perceptions of efficacy and feelings of competency, (2) achievement motivation, and (3) locus of control. The analysis of the interviews revealed that each of these three factors influenced students’ experiences throughout their college years, both overall and in regard to their English studies in particular. The factors were interpreted using Bronfenbrenner’s bio-ecological model of human development. Findings suggest that providing emotional and psychological support to students with visual impairments early in their academic studies could prove beneficial by providing them with the necessary tools for coping with the demands and requirements of higher education.
Orthotic treatment for stage I and II posterior tibial tendon dysfunction (flat foot): A systematic review
Authors: Gómez-Jurado Isabel , Juárez-Jiménez José María , Munuera-Martínez Pedro V
Published: October 2020

Objective:

To investigate whether orthotic treatment is effective for the treatment of posterior tibial tendon dysfunction stages I and II (flat foot).

Data Sources:

Five databases (PubMed, Scopus, PEDro, SPORTDiscus and The Cochrane Library) were searched for potential RCTs from their inception until August 2020.

Review Methods:

Only randomised controlled trials (RCT) that included subjects diagnosed with posterior tibial dysfunction in the initial stage and treated with orthotic treatments were selected. The outcomes assessed were whatever symptom related to posterior tibial tendon dysfunction stage I and II. Included RCTs were appraised using the Cochrane collaboration risk of bias tool.

Results:

Four RCT articles and 186 subjects were included. 75% were at high risk of bias for blinding of participants and personnel. Three different types of conservative treatment were used in the studies: foot/ankle-foot orthoses, footwear and stretching /strengthening exercises. Foot orthoses, together with exercise programmes, seemed to improve the effect of orthotic treatment. Foot orthoses with personalised internal longitudinal arch support were more effective than flat insoles or standard treatments in reducing pain.

Conclusions:

The use of orthotic treatment may be effective in reducing pain in the early stages of posterior tibial tendon dysfunction. Further research is needed into individualised orthotic treatment and high-intensity monitored exercise programmes.
Exploring the effects of long-term anti-social behaviour victimisation
Authors: Heap Vicky
Published: October 2020

Despite victimological interest in the impacts of different types of criminal victimisation, there is little empirical work that examines the effects of sub-criminal behaviour on victims. This article begins to redress the balance by reporting the findings from a qualitative research project in England that investigated the effects of long-term anti-social behaviour victimisation. Semi-structured interviews explored victims’ accounts of the long-term anti-social behaviour they experienced and the resultant effects it had on their lives. The research uncovered that victims experience a range of mental and physical health effects as well as behavioural changes and has provided the first in-depth insight into the impact of this type of victimisation. The findings suggest the cumulative harms associated with anti-social behaviour need to be better acknowledged, understood and addressed, with greater support made available to victims.
Turning a blind eye: The complicit trespassing of ‘Chinese walls’ in financial institutions in New York
Authors: Peluso Daniela
Published: October 2020

This article examines the ways in which ‘Chinese walls’ – that is, information barriers within financial institutions – are constituted and subverted by acts of trespass within large investment banking firms in New York. While Chinese walls positively serve to prevent corruption and fraud, they simultaneously attract legal, semi-legal and illegal forms of trespassing. My analysis shows that some trespassing is based on non-verbalized and embodied exchanges of information that are not in and of themselves illegal. Referred to as playing ‘the game’, the result of these forms of trespass is that the Chinese wall becomes an ‘effect’ or fiction. At other times, trespassing can cause inconvenient suspicion, encouraging those who operate amid these walls to participate strategically in various aspects of wilful blindness. Together, these examples reveal the conceptual and material relationships between ‘seeing’ and ‘knowing’, thereby highlighting the complexity of information flows in financial institutions and demonstrating how the critical regulation of financial capitalism is sometimes weakened.
On the banality of wilful blindness: Ignorance and affect in extractive encounters
Authors: Bovensiepen Judith
Published: October 2020

Research on strategic ignorance tends to focus on the deliberate manufacture of non-knowledge as a tool of governance. In contrast, this article highlights the ‘banal’ workings of wilful blindness, how it can become a normalised part of corporate routine. It examines the diverse dynamics of wilful blindness that became visible in the planning and implementation of a mega oil development project in Timor-Leste, including spatial distancing, denial of moral implications, and the production of effervescent moments of collective solidarity. It concludes that affective states are key in the normalisation of wilful blindness, which operates at the unstable boundary between intention and affect. An emphasis on wilful blindness helps us to bridge the gap between political economy approaches that emphasise the disruptive impact of resource abundance, on the one hand, and anthropological approaches that highlight the social logics and ethical evaluations of main actors involved, on the other.