bluuebunny/crossref_metadata_2025 huggingface dataset:
Decoupled Antagonistic SMA Actuator for Valve Applications
Authors: Britz Rouven , Seelecke Stefan , Rizzello Gianluca , Motzki Paul
Published: November 2020

This paper presents a novel shape memory alloy (SMA) valve actuator concept for active venting in injection molding applications. The developed system can be used to expel air which is trapped during the injection molding process. If such air bubbles are not properly removed from the cavity, they would result into an uncomplete cast and, in turn, in an unsuccessful molding. To address this issue, we propose a new valve system based on an agonist-antagonist SMA-spring actuator concept. By means of the developed SMA valve, the same dynamic performance of conventional actuators can be achieved with a more compact and lightweight actuator design. Design process, assembly, and validation of the novel SMA actuator are first described. In addition, development of an electronics concept and a test rig is discussed. First validation results are finally presented, showing the prototype electro-mechanical response when operating at different ambient temperatures.
Design and Test of an Articulation Mechanism for a Morphing Missile Nosecone
Authors: Ehler Andrew , Hoppe Christopher , Kovarik Hayden , Lamy Reed , Loo Connor , Moore Aaron , Shu Benjamin , Snyder Matthew
Published: November 2020

This paper covers the design and development of a mechanism to change the angle of an air-to-air missile nosecone relative to the missile body while in flight. A group of senior cadets at the United States Air Force Academy performed the work in fulfillment of requirements for their capstone design project. The Air Force Research Laboratory (AFRL) sponsored the project and provided a set of requirements to guide the design. These requirements include the challenge of torque transfer under significant loading in order to drive the nosecone to a new angle. The report will cover significant design changes from last year’s design and the justification for these changes. A complete sub-system breakdown follows. Finally, the planned testing and evaluation of the design is discussed.
The Effect of Fatigue Loading on Electrical Impedance in Open-Hole Carbon Nanofiber-Modified Glass Fiber/Epoxy Composites
Authors: Karnik I. T. , Tallman T. N.
Published: November 2020

Composite materials are ideal for many weight-conscious applications such as aerospace and automotive structures because of their exceptionally high specific properties. However, composite materials are susceptible to complex damage and difficult-to-predict damage growth. This necessitates the application of structural health monitoring (SHM) for in-operation monitoring of damage formation and accumulation. Self-sensing materials are strong candidates for composite SHM because they do not suffer from limitations associated with traditional, point-based sensors. A common approach to self-sensing is the piezoresistive effect in nanofiller-modified materials. To date, work in the area of self-sensing via the piezoresistive effect has focused overwhelmingly on the direct current (DC) response of these materials. This is an important limitation because alternating current (AC) effects inherently provide more information by relating both impedance and phase to damage. Therefore, this work explores the effect of high-cycle fatigue loading on the AC response of carbon nanofiber (CNF)-modified glass fiber/epoxy laminates. Specifically, impedance magnitude and phase angle are both measured through the thickness and along the length of a tension-tension fatigue-loaded specimen with an open-hole stress concentration as a function of load cycle and up to 10 MHz. The collected impedance data is then fit to an equivalent circuit model and correlated to stiffness changes. This means that changes in equivalent circuit behavior can be used to track fatigue-induced softening in self-sensing composites. In light of these promising preliminary results, AC effects appear to have considerable potential for real-time tracking of damage accumulation.
Tunable Postbuckling Systems of Bi-Walled Nonuniform Beams
Authors: Salem Talal , Jiao Pengcheng , Bolandi Hamed , Lajnef Nizar
Published: November 2020

Structural instability, in particular postbuckling resulted in predefined constraints, has been performing advantages in many applications given their promising mechanical characteristics. However, inadequate studies have been conducted to effectively control and tune the postbuckling behavior of bilaterally constrained nonuniform beams. This study develops postbuckling systems comprised of multiple nonuniform beams subjected to bilateral confinements. Theoretical model is developed using Euler-Bernoulli theory and small deformation assumptions to predict postbuckling response of the beam systems under quasi-static axial loading. To locate the minimum energy path of the deformed beam system, the minimization problem of total potential energies of the bi-walled beam systems is solved by Nelder-Mead algorithm. Snap-through transitions of buckled systems are shown by drops in the response curves. To validate the developed model with existing models in literature, the model was simplified to account for single uniform beam under displacement control. The proposed model is experimentally and numerically validated, and satisfactory agreements are obtained. Parametric studies are carried out to investigate the influence of varying the geometric parameters (i.e., length, thickness) of the nonuniform beams on the tunable systems. Using the presented theoretical model, the postbuckling events can be accurately controlled by the geometry properties of the nonuniform beams.
Vibration Response Studies of a Bi-Morph SMA Hybrid Composite Using 3D Laser Doppler Vibrometer
Authors: Srivastava Rupal , Kumar Ranjeet , Bhattacharya Bishakh
Published: November 2020

With the advancement in the field of morphing and adaptive structures, there has been a tremendous increase in the application of such systems in the civil and aerospace engineering, especially wherever space constraint and variable operational environment demand frequent changes in system configuration. The control of stiffness and hence dynamic response of such deployable structures can be achieved through smart material based actuation mechanisms such as shape memory alloys (SMA), and piezoelectric active fiber composites. Selection of appropriate smart material hinges on the requirements of the speed of actuation, actuator bandwidth, and force requirement. In this work, we study the vibration modes of a bi-morph SMA reinforced composite with controlled current input. The composite consists of two layers of SMA reinforcements with 0° and 90° orientation angles placed orthogonally in alternate plies. The temperatures of these layers are raised through Joule heating, first individually, and then followed by combined actuation, where the current supply is controlled using a programmable DC supply. As the material properties of SMA are temperature dependent, we observe thermal contraction and a resulting increase in laminate stiffness. The change of compliance at multiple step-input current contributes to variation in the natural frequency which is recorded using a 3D laser doppler vibrometer (LDV). This study gives us a deep insight into the application of SMA-based bimorph composites for active damping and vibration control subject to varying temperatures.
Investigation of Analysis and Gradient-Based Design Optimization Using Neural Networks
Authors: Fuchi Kazuko W. , Wolf Eric M. , Makhija David S. , Wukie Nathan A. , Schrock Christopher R. , Beran Philip S.
Published: November 2020

Design optimization of adaptive systems requires a robust analysis method that can accommodate various changes in design and boundary conditions. In this work, physics-informed neural networks (PINNs) are used to approximate solutions to differential equations across a range of problem parameter values. This mesh-free method simply requires residual evaluation at sampling points within the analysis domain and along boundaries, and the training process does not require any reference problem to be solved through conventional solution methods. The trained model can be used to predict the solution field, conduct parameter space analysis and design optimization. Using automatic differentiation, the design objective and their derivatives can be computed as a post process for a gradient-based design optimization. The method is demonstrated in a 1D heat transfer problem governed by the steady-state heat equation. Use of the PINN model for design optimization is illustrated in a problem of finding a material transition location to minimize temperature at a specified location. The PINN model that does not include problem parameters as input can be trained to within 0.05% error. PINN models that involve problem parameters as inputs are more difficult to train, especially when the input-to-output relationship is complex.
A Two Dimensional Finite Element Model for Prestress Effects on Magnetoelectric Laminated Composites
Authors: Sridhar Sudersan , Arunachalakasi Arockiarajan
Published: November 2020

Magnetoelectric (ME) composites are viable candidates for use in numerous applications owing to their multifunctional capabilities. These composites develop voltages across the piezo-electric phase under external magnetic fields. Numerous models available in literature consider the magnetostriction under pure magnetic loading. However, fabrication of ME composites results in development of compressive stresses on the magnetostrictive layer, which leads to a poor ME response and hence an initial effective tensile prestress to the magnetostrictive phase is required to either compensate or enhance the ME coupling. In this work, the ME response of an unsymmetric laminate is predicted using a finite element procedure based on Mindlin plate theory, giving due consideration the magnetostrictive nonlinearity, the direction of the applied field and the effect of the stress state on the magnetostrictive response. The model predicts that initial shear stresses, positive or negative, provide the best enhancement to the ME coupling.
The Effects of Additive Manufacturing and Electric Poling Techniques on PVdF Thin Films: Towards 3D Printed Functional Materials
Authors: Fan Jinsheng , Gonzalez David , Garcia Jose , Newell Brittany , Nawrocki Robert A.
Published: November 2020

Mechanical flexibility, faster processing, lower fabrication cost and biocompatibility enable poly (vinylidene fluoride) (PVdF) to have a wide range of applications. This work investigated the use of a piezoelectric polymeric material, PVdF, in combination with 3D printing, to explore new strategies for the fabrication of smart materials with embedded functions, namely sensing. The motivation behind this research was to design and fabricate PVdF thin films that will be used to build pressure sensors with applications in active intelligent structures. In this work, 3D printed PVdF thin films with thickness values in the range of 250 to 350 μm were poled under high direct current electrical fields, which were varied from 0.4 to 12 MV/m and temperatures from 80 to 140 °C. Copper electrodes were applied, forming a standard capacitor layered structure, to facilitate poling and to collect piezoelectric output voltage. The poling process enabled the piezoelectric crystalline phase transition of printed PVdF films to transfer from the non-active a α-phase to the piezoelectric active β-phase and rearranged the dipole alignments of the β-phase. The efficiency of poling was evaluated through the piezoelectric constant calculated from measured calibration curves. These calibration curves demonstrated the PVdF sensing device have a positive linear correlation between mechanical input and voltage output. We found that a peak value in piezoelectric constant correlated with poling voltages and temperatures. The highest piezoelectric constant achieved through contact poling was 32.29 pC/N poled at 750 V and 120 °C, and temperature was deemed the most important factors to influence piezoelectric constant. We believe that the present work demonstrates a path towards fully 3D printed smart, functional materials.
The Piezoresistive Response of CNF/Epoxy to One-Dimensional Strain Wave Excitation via Remote Loading
Authors: Hernandez J. A. , Tallman T. N.
Published: November 2020

The piezoresistive effect in conductive nanofiller-modified polymer, cementitious, and ceramic composites has immense potential to enable multifunctional properties such as intrinsic self-sensing. To date, much work has been done to study the piezoresistive effect under quasi-static loading. Some work has also been done to study the piezoresistive effect under cyclic loading such as when a piezoresistive patch is adhered directly to an oscillating substrate. However, little-to-no work has been done with regard to general dynamic loading conditions such as strain waves originating from a remote source. This is an important gap in the state of the art for two reasons: One, coupling the self-sensing nature of nanocomposites with general elastodynamics is a possible pathway to enabling the study of full-field dynamics (i.e. using the piezoresistive effect to study internal dynamics as opposed to just surface measurements available via tools such as accelerometers and laser vibrometry). And two, coupling piezoresistive self-sensing with damage detection via vibratory methods could lead to transformative gains in the areas of structural health monitoring (SHM) and nondestructive evaluation (NDE). Therefore, we herein work towards addressing this gap in the state of the art by developing basic knowledge on the relation between elastic strain waves and piezoresistive response. Specifically, an electromagnetic-piezoelectric shaker is used to inject highly-controlled strain waves into a long and slender carbon nanofiber (CNF)-modified epoxy rod. Resistance changes along the length of the rod are then measured as strain waves travel along the length of the rod. It is shown that the measured resistance response closely matches the applied mechanical loading. Results from this preliminary study suggest the establishment of an exciting new field — piezoresistive elastodynamics.
Development of Shape Memory-Based Elastic-Adaptive Damping Elements for Sport and Rehabilitation Equipment
Authors: Hoffmann Fabian , Roj Robin , Theiß Ralf , Dültgen Peter
Published: November 2020

The generation and variation of forces necessary to achieve a training stimulus is often realized in sports and rehabilitation equipment by manually adjustable masses or by complex motor-brake systems. This leads to heavy and unwieldy systems, which cannot be used flexibly, and in addition to high costs. The main objective of this paper is to prove that pseudoelastic shape memory alloys (SMA) are potentially suitable for use in sports and rehabilitation equipment and offer additional value in the area of training flexibility combined with high training resistance. Therefore, the properties of pseudoelastic SMAs for this application were investigated. These multifunctional materials offer the potential for special elastic and sensory properties. The pseudoelastic effect is based on stress-induced martensite formation, which allows high elastic deformations. During this phase transformation, the mechanical stress passes through a plateau. The stress plateau can be moved by changing the temperature of the SMA. The determination of properties of pseudoelastic SMAs with different alloy compositions was carried out according to the specifications of “VDI 2248: Product Development with Shape Memory Technology”. With a functional model based on the material tests, which replaces a commercially available force clamping device, the monitoring of force, displacement and temperature changes can be realized by the integrated sensor technology. This paper presents the methodology, experiments and findings for the use of pseudoelastic SMAs in sport and rehabilitation devices. It concludes with prospects to commercial application.
Performance of a Multifunctional Spiral Shaped Acoustic Metamaterial With Synchronized Low-Frequency Noise Filtering and Energy Harvesting Capability
Authors: Mir Fariha , Banerjee Sourav
Published: November 2020

Metamaterials are man-made materials that behave uniquely and possess exclusively desired properties that are not found in natural materials. Usually, it is the combination of two or more materials and can be engineered to perform tasks that are not possible with traditional materials. These were initially discovered while working with electromagnetic radiation. Apart from electromagnetic radiation, metamaterials are also capable of affecting the wave propagation characteristics through any fluid such as air. These metamaterials are called acoustic metamaterials. Many acoustic metamaterials have gone beyond its definition but still, characterize the waveguiding properties. Incorporation of smart materials while constructing acoustic metamaterial, can achieve multifunctionality of the design. A prospective application field for such acoustic metamaterials is energy harvesting from low-frequency vibration. It is conceptualized that acoustic metamaterials can be used as noise barrier materials to filter roadside and industrial noise. This application can get extended to the aerospace application where engine noise mitigation inside the cabin is a challenge. In this article, a spiral-shaped acoustic metamaterial is modeled which has a dual function of noise filtering and energy harvesting. This acoustic metamaterial has a comparatively high reflection coefficient closer to the anti-resonance frequencies, resulting in high sound transmission loss. The filtered noise is trapped inside the cell in the form of strain energy. Hence, we claim that if the trapped energy which is any way wasted in the material could be harvested to power the local electronic devices, the new solution could make transformative for the 21st century’s green energy solution. Calculated placement of smart materials in the cell-matrix can help to extract the strain energy in the form of power. The acoustic metamaterial cell presented in this work has the capability of isolating noise and reducing diffraction by trapping sound in low frequencies and at the same time recover the trapped abundant energy in the form of electrical potential using piezoelectric materials. The spiral design is sensitive to vibration due to trampoline shaped attachments inside the cell. This makes it capable of harvesting energy using vibration also. This is a promising acoustoelastic metamaterial with multifunctionality properties for future applications.
Non-Traditional Shape Variations on Bistable Carbon Fiber Reinforced Polymer Laminates
Authors: Nelon Christopher M. , Figueroa Jonathan , Myers Oliver J. , Shepard Aaron
Published: November 2020

The ability of a material to display two equilibrium states, called bistability, has been previously observed in carbon fiber reinforced polymers (CFRPs). For bistability to occur, the laminate must consist of an unsymmetric layup about its midplane which generates internal residual stress from thermal contraction. Prior studies have observed bistability in CFRPs with small-scale rectangular geometries where all sides were less than 250 mm. The aim of this paper is to demonstrate the existence of bistability in large-scale CFRPs with rectangular and non-rectangular geometries. Experiments and finite element analyses were conducted to determine the viability of bistability in large-scale CFRPs where at least one length aspect of the specimen was greater than or equal to 304.8 mm.

Specimens whose shapes included rectangles, deltoids, triangles, and circles, were fabricated and tested to determine the presence of bistability and the associated curvature for each cured equilibrium state. Rectangular specimens had a side length of 914.4 mm and widths that varied from 177.8 to 457.2 mm. For the deltoids, triangles, and circles, one length aspect (i.e. the height, hypotenuse, and diameter, respectively) equaled 304.8 mm. Finite element models were created to compare the equilibrium shapes’ curvatures and displacements with the experimental laminates; the existence of bistability was also examined using a nondimensionalized bifurcation plot.

Experimentally, bistability was found to occur for the fabricated laminates up to six plies. As the studied laminates could be considered thin, they displayed cylindrical cured shapes. The non-traditional shaped CFRPs followed bistability trends found for traditional, small-scale, rectangular laminates. An inverse relationship between the ply count and curvature was exhibited for the large-scale, rectangular laminates; curvature decreased as the number of plies in the laminate increased.
Structurally Embedded Gradient Index Lens for Extended Amplification of Guided Waves in Polymer Pipes
Authors: Danawe H. , Wang Z. , Tol S. , Okudan G. , Ozevin D.
Published: November 2020

In this paper, we propose a novel gradient index metamaterial lens to focus elastic wave energy in polymer pipes. We investigate multi-mode focusing of guided ultrasonic waves in a poly-vinyl chloride (PVC) pipe by designing and integrating an embedded gradient index (GRIN) lens within the pipe wall. The metamaterial lens is composed of equally spaced cylindrical brass inserts embedded into the pipe wall. All the inserts are of same height which is equal to the half-thickness of the pipe. Insert diameters are varied in circumferential direction to realize hyperbolic secant distribution of refractive index around the circumference of pipe. We explore focusing of three pipe wave modes commonly used for guided wave inspection of pipelines namely, L(0,2), L(0,1) and T(0,1), using a single lens design. We further verify the lens performance through numerical simulations estimating the amplification of wave energy in focal regions of the GRIN lens for these three modes. We also estimate attenuation of guided waves propagating in PVC pipe through experimental measurements.
Autonomous Multifunctional Vehicle With Integrated Bio-Inspired SMA Actuated Grasper
Authors: Changoski Vasko , Domazetovska Simona , Anachkova Maja , Jovanova Jovana
Published: November 2020

The space exploration activities are merging new technologies in order to develop systems challenged to achieve capabilities for high mission experience. Inspired by the numerous applications in space exploration, with the integration of shape memory alloys (SMAs), a 3D printed continuous All Terrain Grasper Transport (AT-GT) vehicle with implemented multi-locomotion grasper was created.

In order to reduce failure of the mechanical system, the vehicle is equipped with SMA suspension and SMA tensioner of a pulley system with adaptable height able to achieve movement on a given trajectory and adjust to any terrain. SMA actuators provide controllable actuation based on the simplicity of their design and the shape memory effect.

By using the advantages of the origami engineering, soft robotics and smart material implementation, a bio-inspired autonomous grasper was integrated on the AT-GT, capable of leaving the vehicle, grabbing an object and bringing it back to the vehicle.

The concept development, the analytical models and the prototype including the benefits of the combined work of the vehicle and the grasper are presented.
Flow Control and Separation Delay in Morphing Wing Aircraft Using Traveling Wave Actuation
Authors: Olivett A. , Corrao P. , Karami M. A.
Published: November 2020

This study examines the biomimicry of wave propagation, a mode of locomotion in aquatic life for the use-case of morphing aircraft surfaces for boundary layer control. Such motion is theorized to inject momentum into the flow on the upper surface of airfoils, and as a consequence, creates a forcible pressure gradient thereby increasing lift. It is thought that this method can be used to control flow separation and reduce likelihood of stall at high angles of attack. The motivation for such a mechanism is especially relevant for aircraft requiring abrupt maneuvers, and especially at high angles of attack as a safety measure against stalling. The actuation mechanism consists of lightweight piezoelectric ceramic transducers placed beneath the upper surface of an airfoil. An open-loop system controls surface morphing. A two-dimensional Fourier Transform technique is used to estimate traveling to standing wave ratio, which is verified analytically using Euler Bernoulli beam theory, and experimentally using a prototype wing. Propagating wave control is tuned and verified using a series of scanning laser vibrometry tests. A custom two-dimensional NACA 0018 airfoil tests the concept in a low-speed wind tunnel with approximate Reynolds Number of 50,000. Both traveling waves and the changes in lift and drag will be experimentally characterized.
A Computational Framework for Predicting Properties From Multifield Processing Conditions in Polymer Matrix Composites
Authors: Widdowson Denise , von Lockette Paris , Erol Anil , Rodriguez Manuel A.
Published: November 2020

Composites can be tailored to specific applications by adjusting process variables. These variables include those related to composition, such as volume fraction of the constituents and those associated with processing methods, methods that can affect composite topology. In the case of particle matrix composites, orientation of the inclusions affects the resulting composite properties, particularly so in instances where the particles can be oriented and arranged into structures. In this work, we study the effects of coupled electric and magnetic field processing with externally applied fields on those structures, and consequently on the resulting material properties that arise. The ability to vary these processing conditions with the goal of generating microstructures that yield target material properties adds an additional level of control to the design of composite material properties. Moreover, while analytical models allow for the prediction of resulting composite properties from constituents and composite topology, these models do not build upward from process variables to make these predictions.

This work couples simulation of the formation of microscale architectures, which result from coupled electric and magnetic field processing of particulate filled polymer matrix composites, with finite element analysis of those structures to provide a direct and explicit linkages between process, structure, and properties. This work demonstrates the utility of these method as a tool for determining composite properties from constituent and processing parameters. Initial particle dynamics simulation incorporating electromagnetic responses between particles and between the particles and the applied fields, including dielectrophoresis, are used to stochastically generate representative volume elements for a given set of process variables. Next, these RVEs are analyzed as periodic structures using FEA yielding bulk material properties. The results are shown to converge for simulation size and discretization, validating the RVE as an appropriate representation of the composite volume. Calculated material properties are compared to traditional effective medium theory models. Simulations allow for mapping of composite properties with respect to not only composition, but also fundamentally from processing simulations that yield varying particle configurations, a step not present in traditional or more modern effective medium theories such as the Halpin Tsai or double-inclusion theories.
Controlling the Rotational DOF of Laminar Jamming Structures With End Clamping Mechanism
Authors: Allen Emily A. , Swensen John P.
Published: November 2020

Variable stiffness structures lie at the nexus of soft robots and traditional robots as they enable the execution of both high-force tasks and delicate manipulations. Laminar jamming structures, which consist of thin flexible sheets encased in a sealed chamber, can alternate between a rigid state when a vacuum is applied and a flexible state when the layers are allowed to slide in the absence of a pressure gradient. In this work, an additional mode of controllability is added by clamping and unclamping the ends of a simple laminar jamming beam structure. Previous works have focused on the translational degree of freedom that may be controlled via vacuum pressure; here we introduce a rotational degree of freedom that may be independently controlled with a clamping mechanism. Preliminary results demonstrate the ability to switch between three states: high stiffness (under vacuum), translational freedom (with clamped ends, no vacuum), and rotational freedom (with ends free to slide, no vacuum).
Deadbands Tell No Tails: X-56A Dynamic Actuation Requirements
Authors: Pankonien Alexander M. , Suh Peter M. , Schaefer Jacob R. , Mitchell Robert M.
Published: November 2020

Following significant effort over the past several years by AFRL and NASA, the X-56A flight vehicle has proven to be a useful platform for exploring controllers and distributed actuation on a flexible, swept flying-wing. The program sought to advance the state of the art in airworthiness for vehicles encountering flutter, leading to relaxed design constraints that could drastically decrease structural weight and improve aircraft performance. Specifically, the vehicle was designed to encounter different forms of flutter: body-freedom flutter, and wing-bending torsion flutter, making it an ideal candidate for identifying dynamic actuation challenges. Flight testing led to fundamental observations by controller designers about the actuation needs for such a vehicle. Namely, the small inherent actuator deadband led to significant constant-amplitude limit cycle oscillations of the system during post-flutter controlled flight. This work captures these observations by exploring theoretical changes in the actuators via a nonlinear simulation tuned with flight testing data and shows that a 60% reduction in actuator deadband can improve ride quality by nearly 50%. The results are combined into a set of actuation challenges for the adaptive structures community at large, including precise actuation for a large number of cycles over multiple timescales, with a relevant baseline described by original actuation system.
Characterization of a Multifunctional Bioinspired Piezoelectric Swimmer and Energy Harvester
Authors: Wang Yu-Cheng , Kohtanen Eetu , Erturk Alper
Published: November 2020

Fiber-based flexible piezoelectric composites with interdigitated electrodes, namely Macro-Fiber Composite (MFC) structures, strike a balance between the deformation and actuation force capabilities for effective underwater bio-inspired locomotion. These materials are also suitable for vibration-based energy harvesting toward enabling self-powered electronic components. In this work, we design, fabricate, and experimentally characterize an MFC-based bio-inspired swimmer-energy harvester platform. Following in vacuo and in air frequency response experiments, the proposed piezoelectric robotic fish platform is tested and characterized under water for its swimming performance both in free locomotion (in a large water tank) and also in a closed-loop water channel under imposed flow. In addition to swimming speed characterization under resonant actuation, hydrodynamic thrust resultant in both quiescent water and under imposed flow are quantified experimentally. We show that the proposed design easily produces thrust levels on the order of biological fish with similar dimensions. Overall it produces thrust levels higher than other smart material-based designs (such as soft material-based concepts), while offering geometric scalability and silent operation unlike large scale robotic fish platforms that use conventional and bulky actuators. The performance of this untethered swimmer platform in piezoelectric energy harvesting is also quantified by underwater base excitation experiments in a quiescent water and via vortex induced-vibration (VIV) experiments under imposed flow in a water channel. Following basic resistor sweep experiments in underwater base excitation experiments, VIV tests are conducted for cylindrical bluff body configurations of different diameters and distances from the leading edge of the energy harvesting tail portion. The resulting concept and design can find use for underwater swimmer and sensor applications such as ecological monitoring, among others.
Cystic renal diseases: role of ultrasound. Part II, genetic cystic renal diseases
Authors: Kabaalioglu Adnan , Gunduz Nesrin , Keven Ayse , Durmaz Emel , Aslan Mine , Aslan Ahmet , Guneyli Serkan
Published: November 2020

Kidney cysts are quite common in adults. Though small simple renal cysts in an adult over 30-40 years of age are not too unusual, however, if the same cysts are seen in a child, and especially if there are additional findings, then several diagnostic possibilities may come to mind. The role of ultrasound, together with the help of intravenous contrast agents and Doppler mode, are very critical in describing the morphologic features and follow-up of the complex or multiple and bilateral renal cysts. These sonographic signs are occasionally specific for diagnosis, but in many cases sonographic clues should be evaluated together with the other genetic and clinical data to reach diagnosis.The first part of this pictorial essay included the introduction into the subject and the classification of non-genetic cystic renal diseases. The key features for the non-genetic cystic renal diseases are illustrated. In the second part, eye-catching features of genetic cystic renal diseases are demonstrated.
Sodium Tetraphenylborate Displays Selective Bactericidal Activity against Neisseria meningitidis and N. gonorrhoeae and Is Effective at Reducing Bacterial Infection Load
Authors: Bernet Eve , Lebughe Marthe , Vincent Antony T. , Haghdoost Mohammad Mehdi , Golbaghi Golara , Laplante Steven , Castonguay Annie , Veyrier Frederic J.
Published: November 2020

Neisseria meningitidis
and
Neisseria gonorrhoeae
, two highly related species that might have emerged from a common commensal ancestor, constitute major human threats. Vaccines are available to prevent
N. meningitidis
infection, whereas there are only a limited number of antibiotics available for
N. gonorrhoeae
. Unfortunately, some strains of these species are rapidly evolving and capable of escaping human interventions.
Pharmacodynamics of Posaconazole in Experimental Invasive Pulmonary Aspergillosis: Utility of Serum Galactomannan as a Dynamic Endpoint of Antifungal Efficacy
Authors: Gastine Silke , Hope William , Hempel Georg , Petraitiene Ruta , Petraitis Vidmantas , Mickiene Diana , Bacher John , Walsh Thomas J. , Groll Andreas H.
Published: November 2020

Aspergillus
galactomannan antigenemia is an accepted tool for the diagnosis of invasive pulmonary aspergillosis (IPA) in neutropenic patients. Little is known, however, about the utility of this biomarker to assess the efficacy of antifungal therapies. The pharmacokinetics (PK) and pharmacodynamics (PD) of posaconazole in treatment and prophylaxis were investigated in the persistently neutropenic rabbit model of
Aspergillus fumigatus
IPA at doses between 2 and 20 mg/kg per day.
Differential
In Vitro
Activities of Individual Drugs and Bedaquiline-Rifabutin Combinations against Actively Multiplying and Nutrient-Starved Mycobacterium abscessus
Authors: Lee Jin , Ammerman Nicole , Agarwal Anusha , Naji Maram , Li Si-Yang , Nuermberger Eric
Published: November 2020

Current treatment options for lung disease caused by
Mycobacterium abscessus
complex infections have limited effectiveness. To maximize the use of existing antibacterials and to help inform regimen design for treatment, we assessed the
in vitro
bactericidal activity of single drugs against actively multiplying and net nonreplicating
M. abscessus
populations in nutrient-rich and nutrient-starvation conditions, respectively. As single drugs, bedaquiline and rifabutin exerted bactericidal activity only against nutrient-starved and actively growing
M. abscessus
, respectively.
Complete Genome Sequence of Francisella tularensis subsp.
holarctica
Strain A271_1 (FDC408), Isolated from a Eurasian Beaver (Castor fiber)
Authors: Sundell David , Uneklint Ingrid , Öhrman Caroline , Salomonsson Emelie , Karlsson Linda , Bäckman Stina , Näslund Jonas , Sjödin Andreas , Forsman Mats , Appelt Sandra , Drechsel Oliver , Jacob Daniela , Heuner Klaus , Myrtennäs Kerstin
Published: November 2020

Here, we report the complete genome sequence of
Francisella tularensis
subsp.
holarctica
strain A271_1, isolated from a Eurasian beaver (
Castor fiber
) in 2012 in the Berlin/Brandenburg region, Germany.
Widespread Traces of Lytic Kaposi Sarcoma-Associated Herpesvirus in Primary Effusion Lymphoma at Single-Cell Resolution
Authors: Rondeau Nicole C. , Finlayson Michael O. , Miranda JJ L.
Published: November 2020

Cancer cells of primary effusion lymphoma (PEL) often contain both Kaposi sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV). We measured the interplay of human, KSHV, and EBV transcription in a cell culture model of PEL using single-cell RNA sequencing. The data detect widespread trace expression of lytic KSHV genes.
Draft Genome Sequences of Lactobacillus delbrueckii subsp.
bulgaricus
Strains CBC-LB69 and CBC-LB8, Isolated from Homemade Dairy Foods in Bulgaria
Authors: Shehata Hanan R. , Chandler Richmond A. , Newmaster Steven G.
Published: November 2020

Here, we report the ndraft genome sequences of
Lactobacillus delbrueckii
subsp.
bulgaricus
strains CBC-LB69 and CBC-LB8. The strains were isolated from naturally processed, homemade dairy foods in Bulgaria. The two genome assemblies each resulted in 39 contigs, with total lengths of 1,752,493 and 1,759,908 bp and GC contents of 49.80% and 49.90%, respectively.
Dating lacustrine carbonate strata with detrital zircon U-Pb geochronology
Authors: Finzel Emily S. , Rosenblume Justin A.
Published: November 2020

Carbonate lacustrine strata in nonmarine systems hold great potential for refining depositional ages through U-Pb dating of detrital zircons. The low clastic sediment flux in carbonate depositional environments may increase the relative proportion of zircons deposited by volcanic air fall, potentially increasing the chances of observing detrital ages near the true depositional age. We present U-Pb geochronology of detrital zircons from lacustrine carbonate strata that provides proof of concept for the effectiveness of both acid-digestion recovery and resolving depositional ages of nonmarine strata. Samples were collected from Early Cretaceous foreland basin fluvial sandstone and lacustrine carbonate in southwestern Montana (USA). Late Aptian–early Albian (ca. 115–110 Ma) maximum depositional ages young upsection and agree with biostratigraphic ages. Lacustrine carbonate is an important component in many types of tectonic basins, and application of detrital zircon U-Pb geochronology holds considerable potential for dating critical chemical and climatic events recorded in their stratigraphy. It could also reveal new information for the persistent question about whether the stratigraphic record is dominated by longer periods of background fine-grained sedimentation versus short-duration coarse-grained events. In tectonically active basins, lacustrine carbonates may be valuable for dating the beginning of tectonic subsidence, especially during periods of finer-grained deposition dominated by mudrocks and carbonates.
Evaporite weathering and deposition as a long-term climate forcing mechanism
Authors: Shields Graham A. , Mills Benjamin J.W.
Published: November 2020

Although it is widely accepted that Earth’s long-term surface temperature is regulated by the mutual dependence of silicate weathering and climate on CO2, the root causes of some climatic events remain unresolved. We show here for the first time that imbalances between evaporite weathering and deposition can affect climate through the process of carbonate sedimentation. Calcium sulfate weathering supplies Ca2+ ions to the ocean unaccompanied by carbonate alkalinity, so that increased carbonate precipitation strengthens greenhouse forcing through transfer of CO2 to the atmosphere. Conversely, calcium sulfate deposition weakens greenhouse forcing, while the high depositional rates of evaporite giants may overwhelm the silicate weathering feedback, causing several degrees of planetary cooling. Non-steady-state evaporite dynamics and related feedbacks have hitherto been overlooked as drivers of long-term carbon cycle change. Here, we illustrate the importance of evaporite deposition, in particular, by showing how a series of massive depositional events contributed to global cooling during the mid–late Miocene.
Two-year outcomes after dextrose gel prophylaxis for neonatal hypoglycaemia
Authors: Griffith Rebecca , Hegarty Joanne Elizabeth , Alsweiler Jane M , Gamble Greg D , May Robyn , McKinlay Christopher Joel Dorman , Thompson Benjamin , Wouldes Trecia Ann , Harding Jane E
Published: November 2020

Objective

To determine the effect of prophylactic dextrose gel for prevention of neonatal hypoglycaemia on neurodevelopment and executive function at 2 years’ corrected age.

Design

Prospective follow-up of a randomised trial.

Setting

New Zealand.

Patients

Participants from the pre-hypoglycaemia Prevention with Oral Dextrose (pre-hPOD) trial randomised to one of four dose regimes of buccal 40% dextrose gel or equivolume placebo.

Main outcome measures

Coprimary outcomes were neurosensory impairment and executive function. Secondary outcomes were components of the primary outcomes, neurology, anthropometry and health measures.

Results

We assessed 360 of 401 eligible children (90%) at 2 years’ corrected age. There were no differences between dextrose gel dose groups, single or multiple dose groups, or any dextrose and any placebo groups in the risk of neurosensory impairment or low executive function (any dextrose vs any placebo neurosensory impairment: relative risk (RR) 0.77, 95% CI 0.50 to 1.19, p=0.23; low executive function: RR 0.50, 95% CI 0.24 to 1.06, p=0.07). There were also no differences between groups in any secondary outcomes. There was no difference between children who did or did not develop neonatal hypoglycaemia in the risk of neurosensory impairment (RR 1.05, 95% CI 0.68 to 1.64, p=0.81) or low executive function (RR 0.73, 95% CI 0.34 to 1.59, p=0.43).

Conclusion

Prophylactic dextrose gel did not alter neurodevelopment or executive function and had no adverse effects to 2 years’ corrected age, but this study was underpowered to detect potentially clinically important effects on neurosensory outcomes.
PEACE in the midst of an emergency: a rash not to miss
Authors: Stavrou Christiana , Mackenzie Strachan , Pocock Rachael , Wilson Andrew J
Published: November 2020

We present the case of a 29-year-old woman who initially presented to her GP with a short history of non-pruritic annular skin lesions with central clearing. A month later, she developed signs and symptoms of bone marrow failure with bruising, epistaxis and fatigue. After urgent review of a blood film, she was diagnosed with acute promyelocytic leukaemia (APML), which is a haematological emergency. Treatment with all-trans retinoic acid (ATRA) was commenced immediately and she was subsequently treated with arsenic trioxide (ATO). The annular rash was subsequently diagnosed as paraneoplastic erythema annulare centrifugum (PEACE), which resolved with treatment. This case demonstrates the importance of the urgent diagnosis of APML and highlights PEACE as a rash that clinicians should be aware of, as it can be the initial manifestation of a number of both haematological and non-haematological malignancies.
Gestational breast cancer: current challenges in staging and treatment of breast cancer
Authors: Schad Aimee , Slostad Jessica , Rao Ruta
Published: November 2020

Gestational breast cancer (GBC) is the most common form of invasive cancer in pregnancy and has unique challenges in both staging and treatment given the dual goal of appropriate cancer management and minimising the risk of fetal toxicity. A 38-year-old woman with no significant medical history and 21 weeks pregnant presented with a palpable right breast mass. She was diagnosed with human epidermal growth factor receptor 2-positive infiltrating ductal carcinoma with advanced disease. The patient underwent treatment; however, unfortunately, she passed away after developing devastating distant disease recurrence.

We highlight both the challenges and current guidelines for management of GBC. Our goal is to discuss the current limitations of GBC management and the necessity of further investigation for safe novel imaging and treatment modalities for pregnant women. It is crucial to increase awareness across multiple subspecialities, as a multidisciplinary team is necessary for proper treatment of GBC.
Clozapine in the management of persistent destructive behaviour in a 17-year-old boy with intellectual disability
Authors: Dadlani Navin , Small Jacqueline , Starling Jean , Einfeld Stewart
Published: November 2020

The management of challenging and refractory destructive behaviour in young patients with intellectual disability (ID) is a major issue faced by families, carers and healthcare professionals who support them. Often, paediatricians and psychiatrists use various behavioural and psychopharmacological approaches, including polypharmacy. We report on one such patient who benefitted greatly from a trial of clozapine, resulting in less aggression, improved quality of life and potentially huge cost savings. We conclude that clozapine may represent a beneficial though seldom-used option for severe, destructive behaviour in young people with ID.
Lockdown dilemma: ingestion of magnetic beads presenting as right iliac fossa pain and subacute small bowel obstruction
Authors: Oyewole Bankole , Sandhya Anu , Maheswaran Ian , Campbell-Smith Timothy
Published: November 2020

A 13-year-old girl presented with a 3-day history of migratory right iliac fossa pain. Observations and inflammatory markers were normal, and an ultrasound scan was inconclusive. A provisional diagnosis of non-specific abdominal pain or early appendicitis was made, and she was discharged with safety netting advice. She presented again 6 days later with ongoing abdominal pain now associated with multiple episodes of vomiting; hence, the decision was made to proceed to diagnostic laparoscopy rather than a magnetic resonance scan for further assessment. Intraoperative findings revealed 200 mL of serous fluid in the pelvis, normal-looking appendix, dilated stomach and a tangle of small bowel loops. Blunt and careful dissection revealed fistulous tracts that magnetised the laparoscopic instruments. A minilaparotomy was performed with the extraction of 14 magnetic beads and the repair of nine enterotomies. This case highlights the importance of careful history taking in children presenting with acute abdominal pain of doubtful aetiology.
Unilateral lymphoedema of lower limb: an unusual presenting feature of hidden tuberculosis verrucosa cutis of foot
Authors: Kaur Maninder , Asati Dinesh P , Khurana Ujjawal , Patra Suman
Published: November 2020

A 42-year-old Indian farmer presented with gradually progressive swelling of the right lower limb for the last 20 years. There were few verrucous plaques over the right foot for the same duration. Those plaques were initially ignored and mistaken as lymphoedema-induced secondary changes by primary care physicians. Histopathology of the skin lesion showed pseudoepitheliomatous hyperplasia with upper dermal granulomatous infiltrate and a diagnosis of tuberculosis verrucosa cutis was suspected. Subsequently, the lesions as well as lymphoedema improved significantly with antitubercular therapy.