bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of an Improved Dummy Head for Use in Helmet Certification Tests
Authors: van den Bosch Eric H. L. A. , Leensen Martijn W. B. M. , Klomp Nancy H. M. , Sauren Fons A. A. H. J. , Wismans Jac S. H. M.
Published: November 2021

First order improvements to the rigid headform, used in current helmet certification tests, are made by introducing a skull and brain structure. In developing the new headform certain requirements were taken into consideration. The new headform appears to meet all requirements but one. The 200 mm drop test with Hybrid-III skin padding on the anvil resulted in too low resultant linear head accelerations. Using a stiffer, more realistic padding on the anvil resulted in a resultant linear head acceleration which satisfies the requirements (100 – 150 g).

The padding plays an important role in the evaluation process. Because of the deformable skull, a fairly stiff padding has to be used in order to let the resultant linear head acceleration satisfy the requirements. In contrast to the 200 mm drop test experiments, the padding properties of the skin are of no importance when an EPS padding is placed between the skin and the anvil.
Static and Dynamic Mechanical and Failure Properties of Human Cerebral Vessels
Authors: Monson Kenneth L. , Barbaro Nicholas M. , Goldsmith Werner , Manley Geoffrey
Published: November 2021

Blood vessels on the cortical surface of the temporal lobe of the cerebrum are frequently damaged in head impact, such as occurs in falls, contact sports, or vehicular collisions. An understanding of the mechanical behavior of these arteries and veins, as well as their limiting loads, is required for a proper understanding and modeling of such traumatic processes—as well as providing substantial assistance in preventive measures and even diagnosis and treatment. Measurements have been performed to obtain the quasi-static and dynamic axial stress-strain characteristics up to and including failure of cortical arteries and veins resected from the temporal lobes of living humans. Results show a notable difference in the behavior of arteries and veins, and somewhat smaller differences — in some cases inconclusive — between static and dynamic comportment. A critical difference between this investigation and the few previous studies of cerebral vessels is the examination of vessel properties under conditions as close as possible to those of the living human, in contrast to studies substantially subsequent to the acquisition of the samples, such as autopsy material, which are reputed to exhibit substantially different properties.
One-Dimensional Mixed Poroelastic-Transport-Swelling (MPHETS) Finite Element Models for Soft Tissues
Authors: Nichol Jason W. , Simon Bruce R. , Williams Stuart K.
Published: November 2021

A hydrated soft tissue structure can be viewed as a poroelastic transport model, or specifically a porous, incompressible, fibrous solid matrix, which is saturated by an incompressible fluid (water) containing both positively and negatively charged species. We present a one-dimensional finite element model (FEM), derived from a Mixed-Poro-HyperElastic-Transport-Swelling (MPHETS)model. This FEM can be used to model various soft tissues, such as arteries, and provides a powerful tool to study coupled ion transport under various mechanical loading and water/ species flow conditions.
Preliminary Study of Vascular Endothelial Ca2+ Response to Elevated Temperature
Authors: Schen Aaron , Xu Lisa X.
Published: November 2021

The thermal regulation of tissue is controlled by the sympathetically mediated redistribution of cardiac output and change in local flow resistance of arterioles. The diameter change of the vessel from its resting level is governed by the state of the contractile proteins in vascular smooth muscle which can be influenced by the concentration of free cytosolic calcium ([Ca2+]i) in the vascular endothelial cells (Falcone, 1995).
Properties of HEMA and MMA Polymer for Introducing it as an Interface Material Between Prosthesis and Bone Cement in THR
Authors: Aggarwal Sanjay , Tekawade Avinash , Chew Larry , Nicholson David , Belfield Kevin , Raab Simon
Published: November 2021

Modern hip replacements were developed in the late 1950s and have since evolved in surgical approaches, implants, and postoperative care. Consequently, surgeons use a wide variety of methods to implant more than 120000 total hip prostheses in the United States per year (National Institute of Health, 1994).
Comparision of Cup Anteversion and Tilt Effects on Dislocation Propensity for Small-Head-Size Total Hip Replacements
Authors: Nadzadi Mark E. , Pedersen Douglas R. , Callaghan John J. , Brown Thomas D.
Published: November 2021

While dislocation is a leading cause of total hip replacement failure, empirical observations far outnumber systematic laboratory examinations of this phenomenon. A previously validated three-dimensional, non-linear, contact finite element model was used to study how surgical placement affects dislocation propensity. The computational model employed a widely used 22mm modular system, and examined range of motion prior to impingement as well as peak moment developed to resist dislocation under a typical leg-crossing maneuver. Results were compared to a previous study of an otherwise similar 26mm modular head system, using the same formulation. Similar trends occurred. Increasing tilt and/or anteversion increased both the range of motion and the peak resisting moment, while apparent stiffness seemed to be unaffected. Further, impingement range of motion was independent of head size, but peak resisting moment was nearly 25% less for the 22mm head sizes.
Three Indentor FEA to Identify Tumors Within Soft Tissue
Authors: Ladeji-Osias Jumoke O. , Langrana Noshir A.
Published: November 2021

Monthly examination of the breast continues to be recommended by the American Cancer Society. In order to obtain a better understanding of multi-force palpation, FEA was undertaken. Three forces were applied simultaneously to the surface of a soft tissue model with an included tumor. The effect of tumor size on the surface displacement was measured. The results demonstrate that three indentor analysis provides realistic information on surface deformation.
Design and Evaluation of Tissue Engineered Arteries
Authors: Ku David N.
Published: November 2021

Tissue engineered vascular substitutes have the potential to be used for treatment of clinically advanced atherosclerotic disease. Design considerations for a tissue engineered vascular substitutes include physiologic levels of flow, low thrombogenicity, and adaptation to changes in flow demands. Some of these attributes may be evaluated using less expensive bench top methods before proceeding to in vivo testing. We have recently developed several methods for determining flow, thrombogenicity, and adaptation in tissue engineered arteries.
Relationship Between Orientation Angle in Intracellular Stress Fibers and Range of Uniaxial Cyclic Stretch
Authors: Yamada Hiroshi , Takemasa Tohru , Yamaguchi Takami
Published: November 2021

We hypothesized an avoidance of deformation and a limit of sensitivity of cell response to the mechanical stimulus for the orientation of stress fibers in cultured cells on a silicone membrane which was subjected to a uniaxial cyclic stretch. We compared the theoretical prediction with the experimental result of stress fibers in the human umbilical vein endothelial cells under various ranges of uniaxial cyclic stretch (Takemasa et al. 1998). The results showed that the proposed hypothesis predicted the orientation of stress fibers under various ranges of cyclic stretch well.
Transient Behavior of Seated Human Body During Input From Caudophalad Acceleration
Authors: Lam Paul C. , Mawasha P. Ruby , Conway Ted
Published: November 2021

The objective of this study, is to investigate the dynamic transient response of a four degree-of-freedom lumped parameter model of the seated human body subjected to caudocephalad loading (acceleration from tail to head). The caudocephalad loading used in the model simulated the ejection process of a seated pilot from a high-speed aircraft. During ejection, ejection velocities are high and are developed over short distances hence, the accelerations are also high (10–40 g’s). The model indicates that even though acceleration is applied over short time duration (typically less than 0.25 seconds), serious bodily injury can result due to high dynamic load factor for the frequency range of body resonances.
In Vitro Testing of Posterior Cervical Lateral Mass Plating Systems: Comparison of Constrained Versus Semi-Constrained Screw-Slot Connections
Authors: DiAngelo Denis J. , McVay Bobby J. , Olney Kristine M. , Foley Kevin T.
Published: November 2021

Interspinous or facet wiring has been the standard treatment for posterior cervical spine instability secondary to trauma or decompression (Wellmann et al., 1998). However, wire techniques may be limited when posterior elements are deficient or fractured. Alternative methods, such as posterior lateral mass plate fixation, may restore the stability of the affected region and promote fusion (Wellmann et al., 1998). The objective of the study was to determine if lateral mass plate fixation restored the stability of a reconstructed posterior destabilized cervical spine and to compare the biomechanical stability of two lateral mass plate designs: plates with screws constrained in slots (SCS) versus plates with screws unconstrained and free to translate in slots (SUS). Two posterior destabilized conditions were studied: a one-level (C4-C5) model and a two-level (C4-C6) model in which all posterior ligaments were sectioned.
Kinematics of the Cervical Spine: Path of the Instant Axis of Rotation in Flexion and Extension
Authors: DiAngelo Denis J. , Vossel Keith , Foley Kevin T.
Published: November 2021

Previous Biomechanical Measures of Vertebral Kinematics.

White and Panjabi (1990) have suggested that the Instant Axis of Rotation (IAR) be used to describe the 2-D motion of a vertebral body. However, the location of the IAR for the cervical spine varies amongst spine researchers. White and Panjabi (1990) have suggested the IAR of each vertebra is located in the anterior region of the subjacent vertebra; Porterfield and Derosa (1995) suggest it is located in the mid-region of the subjacent vertebra; and Mameren et al. (1992) found it to lay in the central region of the vertebral body being tracked. Goel and Winterbottom (1991) stated that during flexion and extension, the axis of rotation is located somewhere within the vertebral body itself. Unfortunately, no accurate calculations of the IAR paths of the cervical spine exist; typical vertebral measurements only include the rotational components. Estimation of the vertebrae’s IAR location in vitro depends on the experimental set-up (motion and loading mechanics), anatomical structure, mathematical reduction technique, and accuracy of the measurement equipment. Crisco et al. (1994) determined the theoretical error in calculating the location of the IAR as a function of the measurement system specifications and the placement of the markers on the spinal body. Conventional tracking systems having translational resolutions of 0.1mm to 0.05mm were found to calculate the location of the IAR to within 7mm to 10mm, respectively. This error became significantly larger as the resolution of the measurement system dropped off. Most investigators only calculate the rotational components of a body’s motion and seldom calculate the error involved in their mathematical analysis. Furthermore, overall head movement is often reported (i.e., C0 to T1), but smaller flexion-extension movements of individual spinal bodies are either void in the literature or suspect to large theoretical errors. The objective of the study was to determine the IAR of the sub-axial cervical vertebral bodies under physiological flexion and extension conditions in vitro.
Does the Orientation of a Limberg Flap Matter?
Authors: Coley Lisa M. , Dolovich Allan T. , Watson L. Glen , Valnicek Stan
Published: November 2021

The Limberg flap is a standard surgical procedure for closing skin wounds. Finite element analyses were used to investigate how the orientation of the flap, relative to the direction of maximum natural tension in the skin, affects the stresses produced.
Potential Benefits of Bronchoconstriction and Thick Airway Mucus
Authors: Krumpe Peter
Published: November 2021

Wheezes and sputum production are two hallmarks of lung disease. Both are associated with airway obstruction and increased work of breathing. Why should our species invest such a considerable amount of genetic material in the support of airway changes that are viewed as evidence of pathological lung disease? Perhaps bronchoconstriction and thick airway mucous provide advantages in defense of airway clearance that outweighs the mechanical cost of airway obstruction.
Simulation of Respiratory System for Identifying Airway Occlusion
Authors: Al-Jumaily A. M. , Mithraratne P.
Published: November 2021

Respiratory disorders are common in both developed and developing countries. Many of these disorders are directly connected to constrictions in the airways of the human respiratory system. Asthma and bronchitis are typical examples that arise from the constriction of airways. The respiratory system consists of a series of branching tubes which become narrower, shorter and more numerous as they penetrate deeper into the lung. This branching network found within the multiple succussive bifurcation of the pulmonary tree has received theoretical attention [1]. Several attempts have been made to investigate the characteristics of healthy and unhealthy lungs. Some of them theoretical [2–5] while others are experimental [6,7]. The acoustical approach has been considered as one of the leading theoretical approaches to date. This approach is based on linking the acoustical impedance between the branches by using recursive formulae [2]. None of the available references has investigated the effect of occlusions in a branch on the behaviour of the whole respiratory system. Further, the work reported on the dynamic modelling of the respiratory system has overlooked, with the exception of [5], mechanical and physical properties of the airway walls, which are believed to have a considerable impact on the overall dynamics of the system.
Roof Strength: A Factor in Rollover Injuries
Authors: Syson Stephen R.
Published: November 2021

Recently, the National Highway Traffic Safety Administration (NHTSA) reported that injuries and fatalities in rollover continue to be a serious problem out of proportion with the relative frequency of such incidents. (Summers, 1997) On average, 7,797 annual rollover involved fatalities were reported by the Fatal Accident Reporting System (FARS), between 1988 and 1994. There were also between 43,000 and 58,000 annual rollover involved incapacitating injuries between 1988 and 1994, as reported by NASS GES. Approximately 16 percent of serious injuries to passenger car occupants and 42 percent of serious injuries to light truck occupants occurred in vehicles that rolled over. Light trucks, including vans, experienced the highest rollover involvement rate, 25.9 percent, compared to 15.3 percent for passenger cars.
Experimental Intervertebral Disc Degeneration: Compressive Behavior Changes Over Time
Authors: Kim Jesse G. , Lim Tae-Hong , Renner Susan M. , Fujiwara Atsushi , Nuyen Cahn , Yoon Taekhoon , An Howard S.
Published: November 2021

Changes in axial compressive behavior of the intervertebral disc resulting from annulus stab wound were investigated using rabbit discs. Results of this study clearly showed that stabbing incision could cause disc degeneration with losses in disc height, elastic modulus, and energy dissipation capacity in 8 weeks after injury. Disc specimens obtained at 12 weeks after stab incision showed no further changes in disc height and axial compressive behavior from those found in 8 week specimens.
Linking Measurements of Coronary Flow Reserve in Patients During Angioplasty Procedures to Myocardial Perfusion Using Computational Hemodynamics
Authors: Banerjee Rupak K. , Back Lloyd H. , Back Martin R. , Cho Young I.
Published: November 2021

Computational hemodynamics was used to determine the connection between measurements of coronary flow reserve (CFR) and myocardial perfusion in patients with obstructive disease during angioplasty. The 32 patient group (Wilson et al. 1988) had single-vessel, single-lesions with either unstable angina pectoris or stable angina, but no known abnormalities that might affect the vasodilator capacity of the arteriolar vasculature.

The patients’ maximal vasodilation-distal perfusion pressure curve (CFR- P ˜ r h ) was uniquely determined by the intersections of measured values of CFR and computed values of P ˜ r h for the native and residual lesions after percutaneous transluminal coronary balloon angioplasty (PTCA) supplying blood to the same vasculature. Extrapolation of this nearly linear curve to its origin gave a zero-flow mean pressure P ˜ r o of about 20 mm Hg, close to a value of 18 mm Hg known to be associated with ischemia in the subendocardium of dog hearts (Bache and Schwartz, 1982). The corresponding value of P ˜ r h of about 55 mm Hg in the native lesions coincided with the level proposed by Brown et al. 1984 to cause ischemia in the subendocardium of human hearts.
The Linear and Weakly-Nonlinear Stability of a Core Annular Flow in a Corrugated Tube
Authors: Wei Hsien-Hung , Rumschitzki David S.
Published: November 2021

Both linear and weakly nonlinear stability of a core annular flow in a corrugated tube in the limit of thin film and small corrugation are examined. Asymptotic techniques are used to derive the corrugated base flow and corresponding linear and weakly nonlinear stability equations. Interesting features show that the corrugation interaction can excite linear instability, but the nonlinearity still can suppress such instability in the weakly nonlinear regime.
Evaluation of a Torsion Exercise Device for Space Station
Authors: Todd Beth A. , Swindle Stephanie H. , Dunavant Randall J. , Harrison Justin F.
Published: November 2021

An exercise device for use on Space Station was instrumented to determine the force and position of the exerciser. The device was tested in both 1-G and 0-G environments. Differences were found in the performance of the exercise in the two environments. Additionally significant variation was found in the load settings.
A Probabilistic Approach to the Modeling of Fatigue in Gamma-Based Titanium Aluminides
Authors: Lou J. , Shen W. , Soboyejo W. O.
Published: November 2021

This paper presents a statistical framework for the modeling of fatigue in gamma-based titanium aluminide intermetallics. Following an initial description of the physics of fatigue crack growth, a deterministic fracture mechanics model is presented for the estimation approaches are of fatigue life. This is used as a basis for the development of a probabilistic model for the estimation of fatigue life due to variabilities in the initial flow size. The predicted variabilities are compared with measured variabilities from multiple fatigue life experiments performed on three cast lamellar gamma alloys. The implications of the results are then discussed for the estimation of material reliability in gamma-based titanium aluminide intermetallics.
Reliability High Cycle Fatigue Design of Gas Turbine Blading System Using Probabilistic Goodman Diagram
Authors: Shen M.-H. Herman , Nicholas Theodore
Published: November 2021

A framework for the probabilistic analysis of high cycle fatigue is developed. The framework will be useful to U.S. Air Force and aeroengine manufacturers in the design of high cycle fatigue in disk or compressor components fabricated from Ti-6Al-4V under a range of loading conditions that might be encountered during service. The main idea of the framework is to characterize vibratory stresses from random input variables (uncertainties such as initial crack size, crack location, loading, material properties, and manufacturing variability). The characteristics of such vibratory stresses will be portrayed graphically as histograms, or probability density function (PDF). The outcome of the probability measures associated with all the values of a random variable exceeding the material capability is achieved by a failure function g(X) defined by the difference between the vibratory stress and Goodman line or surface such that the probability of HCF failure is P(f) = P(g(X<0)). The framework can be used to facilitate the development design tools for the prediction of inspection schedules and reliability in aeroengine components. Such tools could lead ultimately to improved life extension schemes in aging aircraft, and more reliable methods for the design and inspection of critical components.
Failure by Fatigue and Stress Rupture in Fiber-Reinforced Composites
Authors: Curtin W. A.
Published: November 2021

Composite durability under conditions where the material survives the initial application of load but then deteriorates with time is a major issue in most engineering applications of composites. The degradation can be caused by the propagation of many damage modes: delamination, matrix cracking, interface degradation, creep, and fiber degradation, among others. In many situations, ultimate and total failure is associated with failure of the fiber bundle supporting the dominant portion of the applied load. Here, the lifetime of a composite due to fiber degradation is investigated for two important modes of fiber degradation: fatigue crack growth under cyclic loading and slow crack growth under stress rupture conditions of constant load. In both cases, individual fiber failure is caused by the growth of pre-existing cracks to a critical size via fatigue or rupture, which is modeled here by a Paris law. A simulation model is used to determine the time-dependent stresses on a bundle of uniaxial brittle fibers, each containing an initial distribution of cracks corresponding to a Weibull strength distribution. As individual fibers fail, their stresses are transferred to nearby fibers, which increases the rate of degradation of the nearby fibers. The damage evolution thus accelerates locally, culminating in the very rapid growth of damage across the entire specimen at the failure time. The average failure time for a set of nominally identical specimens is primarily a function of the fiber Weibull modulus, the Paris law exponent in the fatigue or rupture model, the initial fiber strength, and the rate coefficient of the Paris law. Guidance for the major dependencies of the failure time is obtained by considering an analogous “Global Load Sharing” (GLS) model in which broken fibers transfer load equally to all remaining fibers in the same cross-section. The statistical distribution of failure times at fixed composite size and the size scaling of the mean failure time with increasing size, neither of which can be obtained from the GLS model, are presented and discussed.
Time-Dependent Reliability of Ceramic Components Under Transient Loads
Authors: Jadaan Osama , Nemeth Noel , Powers Lynn , Palko Joe , Baker Eric
Published: November 2021

Present capabilities of the NASA CARES/Life code include probabilistic life prediction of ceramic components subjected to fast fracture, slow crack growth (stress corrosion), and cyclic fatigue failure modes. Currently, this code has the capability to compute the time-dependent reliability of ceramic structures subjected to simple time-dependent loading. For example, in slow crack growth (SCG) type failure conditions CARES/Life can handle the cases of sustained and linearly increasing time-dependent loads, while for cyclic fatigue applications various types of repetitive constant amplitude loads can be accounted for. In real applications applied loads are rarely that simple, but rather vary with time in more complex ways such as, for example, engine start up, shut down, and dynamic and vibrational loads. In addition, when a given component is subjected to transient environmental and or thermal conditions, the material properties also vary with time. The objective of this paper is to demonstrate a methodology capable of predicting the time-dependent reliability of components subjected to transient thermomechanical loads that takes into account the change in material response with time. In this paper, the dominant delayed failure mechanism is assumed to be SCG. This methodology has been coded into CARES/Life, which has also been modified to have the capability of interfacing with commercially available FEA codes executed for transient load histories. An example involving a ceramic exhaust valve subjected to combustion cycle loads is presented to demonstrate the viability of this methodology and the CARES/Life program.
Fatigue Reliability Under Corrosion, Creep, and Fretting Damage
Authors: Mahadevan Sankaran
Published: November 2021

This paper presents probabilistic methodologies being developed at Vanderbilt University for the reliability analysis of aging structures. Several deterioration mechanisms such as fatigue, corrosion, creep, and fretting are considered, and probabilistic models are developed. Interactions between the different mechanisms are considered. The effects of various uncertain parameters on the overall life prediction estimates are quantified.

The fatigue damage process induced by pitting corrosion in aging aircraft is composed of seven stages: pitting nucleation, pit growth, transition from pit growth to short crack, short crack growth, transition from short crack to long crack, long crack growth and fracture. A comprehensive mechanics-based probabilistic model for pitting corrosion fatigue life prediction by including all the stages is presented. Analytical FORM/SORM methods as well as advanced Monte Carlo simulation methods are implemented with the proposed model, and probabilistic sensitivity analysis and parametric studies are performed.

Fretting fatigue is one of the main mechanisms of the formation of cracks in riveted lap joint assemblies in aging aircraft and can reduce the fatigue life significantly. A macro-mechanics-based probabilistic model is developed to give the quantitative description of crack nucleation life. Fretting conditions in an idealized, cyclic-loaded pinned connection having dimensions typical of riveted panels are studied. ANSYS finite element analysis is applied to provide the stress, displacement and strain fields in the neighborhood of the contacts between the panel and pin.

Creep is one of the principal damage mechanisms for materials operating at elevated temperatures, such as in aircraft and space propulsion engines. It can produce larger strain deformation, stress relaxation, and crack initiation and growth. Current creep-fatigue life prediction methods use a code-specified bilinear model that has several uncertainties and assumptions regarding material behavior. A new continuous creep-fatigue failure criterion function is introduced directly based on experimental data to facilitate analytical reliability approximations. Such a model is advantageous for new high performance materials where previous experience is limited. A linear damage accumulation rule is used. The use of analytical and simulation methods for reliability analysis with the proposed model is investigated. The effects of the scatter and distributions of different random variables on the creep-fatigue life are studied.

This study is supported by funds from the National Science Foundation.
Challenges and Opportunities for Prime Reliant Thermal Barrier Coating Systems
Authors: Evans Anthony G.
Published: November 2021

Thermal protection systems based on thermal barrier coatings are widely used in turbine engines for propulsion and power generation. They commonly comprise oxide thermal barriers coatings (TBCs) deposited on an intermetallic bond coat (BC), and provide simultaneous thermal and oxidation protection. The benefit of these coatings resides in their ability to inhibit degradation of the underlying structural superalloy component by thermo-mechanical fatigue and oxidation. Existing commercial coatings are well-engineered with established durability and cost benefits. However, they lose adhesion and spall from the underlying metal with cyclic thermal exposure. Because coating failure occurs in a stochastic manner, with no assured cyclic life, the coatings cannot be used in a prime-reliant manner. Prime reliability is only achievable if a high level of basic understanding is gained about failure mechanisms, and material responses, that arise upon thermal cycling. Because of differing manufacturing approaches and operating scenarios, several specific mechanisms are involved. Present understanding of these phenomena has highlighted several nuances and challenges in developing thermal barrier coatings for use as prime-reliant components. This talk will review the current understanding of factors affecting coating durability and presents relationships between the durability, the governing material properties and the salient morphological features. The durability of thermal barrier coatings is governed by a sequence of crack nucleation, propagation and coalescence events that accumulate prior to final failure by large scale buckling and spalling.
Processing and Microstructure Evolution in EB-PVD TBCs
Authors: Terry Scott G. , Cho Junghyun , Levi Carlos G.
Published: November 2021

The connection between processing and performance in thermal barrier coatings produced by electron-beam physical-vapor-deposition is not well understood. A significant component of the problem is the limited understanding of the role that microstructure (including defects) plays in this connection, and the relationships between microstructure and process parameters. This presentation will review recent work aimed at understanding these relationships. The focus will be on the evolution of porosity within the TBC, which is of paramount importance to both thermal conductivity and strain tolerance. Porosity is a result of shadowing processes in the presence of insufficient surface diffusion, and thus deposition temperature and vapor incidence pattern are major parameters. The presentation will highlight the interplay between vapor flux and surface topography, illustrating the relevant phenomena with experimental and modeling results. (Work sponsored by ONR under Grant N00014-99-1-0471 and the UC-LANL Collaborative Research Program.)
Degradation of the Mechanical Properties of Aluminide Coatings as a Result of Thermal Cycling
Authors: Walter Mark , Kim Hyungjun
Published: November 2021

Thermal barrier coatings (TBCs) are typically composed of a ceramic top coat, a thermally grown oxide, and an aluminide bond coat. These three layers each have specific roles in protecting super alloy substrates. State-of-the-art TBCs use Zirconia for the ceramic top coat and develop Alumina thermally grown oxide. Although the bond coats almost universally contain aluminides, their composition and processing vary greatly. In this work, a platinum aluminide bond coat system which was processed using an unactivated pack cementation process is studied. This bond coat system was formed on 1 inch diameter CMSX-4 super alloy disks.
Optimization and Process Control for High Performance Thermal Spray Coatings
Authors: Moreau Christian , Leblanc Luc
Published: November 2021

Thermal spray coatings are used to protect surfaces against exposure to severe conditions. To insure a reliable protection, not only the structure and properties of the sprayed coatings must be optimized but also one needs to develop appropriate process control techniques to produce high performance coatings in a consistent manner, day after day. This is particularly important during plasma spraying as the wear of the electrodes affects significantly the plasma characteristics and consequently the coating properties. First, in this paper, the stability of plasma spray processes is investigated by monitoring in-flight particle characteristics and plasma fluctuations. Secondly, the possibility and advantages of controlling plasma spray processes by monitoring and regulating the condition of the sprayed particles are discussed. Finally, we will see how the properties of thermal barrier coatings and wear resistant coatings can be optimized by controlling the temperature and velocity of the sprayed particles both in the plasma spray and HVOF (high velocity oxy-fuel) processes.
The Functional Performance of Poly Methylmethacrylate Orthopaedic Bone Cement
Authors: Prendergast Patrick J.
Published: November 2021

Materials for fixation of load-bearing implants in the human body should be able to sustain a cyclic load of variable magnitude over an extended period over the remaining lifetime of the parient. A material commonly used for fixation of orthopaedic, dental, and maxillofacial implants is a polymer poly methylmethacrylate (PMMA). However, PMMA does not ideally fulfill this criterion because it undergoes damage accumulation and creep under cyclic loading. This leads to implant loosening and the need for a revision operation.
Fundamental Characteristics of Viscoelastic Fluids Simulated by a Bead-Spring-Damper Macro Model With Interaction
Authors: Ishikawa Takuji , Kawabata Nobuyoshi , Fujita Katsushi , Miyake Yutaka
Published: November 2021

The flow field of viscoelastic fluids is commonly analyzed by using constitutive equations. In this paper, a bead-spring-damper macro model with interaction is proposed as an alternative to analyze a viscoelastic flow. A tetrahedral structure of beads and springs models a gathering of intertwined polymer chains. Behavior of the macro model and the cluster is computed under a simple shear flow condition. Shear-thinning of viscosity, the mechanism of generation of normal stress differences and the effect of slip in the interaction are investigated. The results show that the elongation of clusters to the x direction is the mechanism of the normal stress differences generation, and that the slip in the interaction weakens the stresses. Consequently, it is found that the bead-spring-damper macro model can express the behavior of polymer chains in viscoelastic fluids and basic characteristics of viscoelastic fluids without using constitutive equations.
Calcium-Responsive Diguanylate Cyclase CasA Drives Cellulose-Dependent Biofilm Formation and Inhibits Motility in Vibrio fischeri
Authors: Tischler Alice H. , Vanek Michael E. , Peterson Natasha , Visick Karen L.
Published: November 2021

Biofilm formation and motility are often critical behaviors for bacteria to colonize a host organism.Vibrio fischeriis the exclusive colonizer of its host’s symbiotic organ and requires both biofilm formation and motility to initiate successful colonization, providing a relatively simple model to explore complex behaviors. In this study, we determined how the environmental signal calcium alters bacterial behavior through production of the signaling molecule c-di-GMP.
Microbiota-Dependent and -Independent Production of
l-
Dopa in the Gut of Daphnia magna
Authors: El-Shehawy Rehab , Luecke-Johansson Sandra , Ribbenstedt Anton , Gorokhova Elena
Published: November 2021

Neurotransmitters are commonly implicated in host-microbiome communication, yet the molecular mechanisms of this communication remain largely elusive. We present novel evidence linking the gut microbiome to host development and growth via neurotransmitter
l-
Dopa in
Daphnia
, the established model species in ecology and evolution.
Evolution of the Late Cretaceous Nanaimo Basin, British Columbia, Canada: Definitive provenance links to northern latitudes
Authors: Mahoney J. Brian , Haggart James W. , Grove Marty , Kimbrough David L. , Isava Virginia , Link Paul K. , Pecha Mark E. , Fanning C. Mark
Published: November 2021

Accurate reconstruction of the Late Cretaceous paleogeography and tectonic evolution of the western North American Cordilleran margin is required to resolve the long-standing debate over proposed large-scale, orogen-parallel terrane translation. The Nanaimo Basin (British Columbia, Canada) contains a high-fidelity record of orogenic exhumation and basin subsidence in the southwestern Canadian Cordillera that constrains the tectonic evolution of the region. Integration of detrital zircon U-Pb geochronology, conglomerate clast U-Pb geochronology, detrital muscovite 40Ar/39Ar thermochronology, and Lu-Hf isotopic analysis of detrital zircon defines a multidisciplinary provenance signature that provides a definitive linkage with sediment source regions north of the Sierra Nevada arc system (western United States).

Analysis of spatial and temporal provenance variations within Nanaimo Group strata documents a bimodal sediment supply with a local source derived from the adjacent magmatic arc in the southern Coast Mountains batholith and an extra-regional source from the Mesoproterozoic Belt Supergroup and the Late Cretaceous Atlanta lobe of the Idaho batholith. Particularly robust linkages include: (1) juvenile (εHf >+10) Late Cretaceous zircon derived from the southern Coast Mountains batholith; (2) a bimodal Proterozoic detrital zircon signature consistent with derivation from Belt Supergroup (1700–1720 Ma) and ca. 1380 Ma plutonic rocks intruding the Lemhi subbasin of central Idaho (northwestern United States); (3) quartzite clasts that are statistical matches for Mesoproterozoic and Cambrian strata in Montana and Idaho (northwestern United States) and southern British Columbia; and (4) syndepositional evolved (εHf >−10) Late Cretaceous zircon and muscovite derived from the Atlanta lobe of the Idaho batholith. These provenance constraints support a tectonic restoration of the Nanaimo Basin, the southern Coast Mountains batholith, and Wrangellia to a position outboard of the Idaho batholith in Late Cretaceous time, consistent with proposed minimal- fault- offset models (<~1000 km).
Idiopathic portal vein thrombosis not related to hepatic disease or malignancy
Authors: Alkassis Samer , Zaher Nathan , Kaloti Zaid , Levine Diane
Published: November 2021

Acute portal vein thrombosis (PVT) is a rare disorder defined by the sudden occlusion of the portal vein, which could be partial or complete. Prothrombotic states, inherited or acquired, are thought to be the cause in patients without cirrhosis or malignancy. However, the aetiology of some cases remains idiopathic despite a multidisciplinary diagnostic approach. The initial diagnostic modality to confirm PVT is either contrast-enhanced abdominal (CT) or MRI; as it can identify predisposing factors, and detect evidence of complications. Eliciting the underlying aetiology is critical to guide overall management and prevent future recurrence. The purpose of treatment is to stop thrombus extension and achieve portal vein patency by anticoagulation to optimise outcomes. Herein, we present an unusual case of spontaneous PVT in a young woman. We will also discuss the evaluation of patients without obvious aetiology.
Prospective cohort study to evaluate the accuracy of sleep measurement by consumer-grade smart devices compared with polysomnography in a sleep disorders population
Authors: Ellender Claire M , Zahir Syeda Farah , Meaklim Hailey , Joyce Rosemarie , Cunnington David , Swieca John
Published: November 2021

Objectives

Consumer-grade smart devices are now commonly used by the public to measure waking activity and sleep. However, the ability of these devices to accurately measure sleep in clinical populations warrants more examination. The aim of the present study was to assess the accuracy of three consumer-grade sleep monitors compared with gold standard polysomnography (PSG).

Design

A prospective cohort study was performed.

Setting

Adults undergoing PSG for investigation of a suspected sleep disorder.

Participants

54 sleep-clinic patients were assessed using three consumer-grade sleep monitors (Jawbone UP3, ResMed S+ and Beddit) in addition to PSG.

Outcomes

Jawbone UP3, ResMed S+ and Beddit were compared with gold standard in-laboratory PSG on four major sleep parameters—total sleep time (TST), sleep onset latency (SOL), wake after sleep onset (WASO) and sleep efficiency (SE).

Results

The accelerometer Jawbone UP3 was found to overestimate TST by 28 min (limits of agreement, LOA=−100.23 to 157.37), with reasonable agreement compared with gold standard for TST, WASO and SE. The doppler radar ResMed S+ device underestimated TST by 34 min (LOA=−257.06 to 188.34) and had poor absolute agreement compared with PSG for TST, SOL and SE. The mattress device, Beddit underestimated TST by 53 min (LOA=−238.79 to 132) on average and poor reliability compared with PSG for all measures except TST. High device synchronisation failure occurred, with 20% of recordings incomplete due to Bluetooth drop out and recording loss.

Conclusion

Poor to moderate agreement was found between PSG and each of the tested devices, however, Jawbone UP3 had relatively better absolute agreement than other devices in sleep measurements compared with PSG. Consumer grade devices assessed do not have strong enough agreement with gold standard measurement to replace clinical evaluation and PSG sleep testing. The models tested here have been superseded and newer models may have increase accuracy and thus potentially powerful patient engagement tools for long-term sleep measurement.
What are the needs and preferences of patients and family members discharged from the emergency department within 24 hours? A qualitative study towards a family-centred approach
Authors: Østervang Christina , Lassen Annmarie Touborg , Jensen Charlotte Myhre , Coyne Elisabeth , Dieperink Karin Brochstedt
Published: November 2021

Objective

There is an increase in patients being discharged after short stays in the emergency department, but there is limited knowledge of their perspectives on treatment and care. This study aims to explore and understand the needs and preferences of emergency care from the perspective of patients and family members discharged from the emergency department within 24 hours of admission.

Design

The study reports from the first phase in an overall participatory design project. Systematic text condensation was used to identify key themes from field observations and interviews with patients and family members.

Setting

This study was conducted in two emergency departments in the Region of Southern Denmark.

Participants

All adults aged ≥18 years who had been discharged from the emergency department within 24 hours were eligible to take part. Purposeful sampling was used to recruit patients and family members with different sociodemographic features.

Results

Field observational studies (n=50 hours), individual interviews with patients (N=19) and family members (N=3), and joint interviews with patients and family members (N=4) were carried out. Four themes were derived from the material: (1) being in a vulnerable place—having emotional concerns; (2) having a need for person-centred information; (3) the atmosphere in the emergency department and (4) implications of family presence.

Conclusion

This study demonstrates a gap between patients’ and family members’ needs and preferences and what current emergency departments deliver. The findings highlight the importance of family and person-centred care. Tailored communication and information with genuine involvement of family members is found to be essential needs during acute illness.
Nurse staffing and patient-perceived quality of nursing care: a cross-sectional analysis of survey and administrative data in German hospitals
Authors: Winter Vera , Dietermann Karina , Schneider Udo , Schreyögg Jonas
Published: November 2021

Objective

To examine the impact of nurse staffing on patient-perceived quality of nursing care. We differentiate nurse staffing levels and nursing skill mix as two facets of nurse staffing and use a multidimensional instrument for patient-perceived quality of nursing care. We investigate non-linear and interaction effects.

Setting

The study setting was 3458 hospital units in 1017 hospitals in Germany.

Participants

We contacted 212 554 patients discharged from non-paediatric, non-intensive and non-psychiatric hospital units who stayed at least two nights in the hospital between January and October 2019. Of those, 30 174 responded, yielding a response rate of 14.2%. Our sample included only those patients. After excluding extreme values for our nurse staffing variables and removing observations with missing values, our final sample comprised 28 136 patients ranging from 18 to 97 years of age (average: 61.12 years) who had been discharged from 3458 distinct hospital units in 1017 hospitals.

Primary and secondary outcome measures

Patient-perceived quality of nursing care (general nursing care, guidance provided by nurses, and patient loyalty to the hospital).

Results

For all three dimensions of patient-perceived quality of nursing care, we found that they significantly decreased as (1) nurse staffing levels decreased (with decreasing marginal effects) and (2) the proportion of assistant nurses in a hospital unit increased. The association between nurse staffing levels and quality of nursing care was more pronounced among patients who were less clinically complex, were admitted to smaller hospitals or were admitted to medical units.

Conclusions

Our results indicate that, in addition to nurse staffing levels, nursing skill mix is crucial for providing the best possible quality of nursing care from the patient perspective and both should be considered when designing policies such as minimum staffing regulations to improve the quality of nursing care in hospitals.
Supplementation withBifidobacterium longumsubspeciesinfantisEVC001 for mitigation of type 1 diabetes autoimmunity: the GPPAD-SINT1A randomised controlled trial protocol
Authors: Ziegler Anette-Gabriele , Arnolds Stefanie , Kölln Annika , Achenbach Peter , Berner Reinhard , Bonifacio Ezio , Casteels Kristina , Elding Larsson Helena , Gündert Melanie , Hasford Joerg , Kordonouri Olga , Lundgren Markus , Oltarzewski Mariusz , Pekalski Marcin L , Pfirrmann Markus , Snape Matthew D , Szypowska Agnieszka , Todd John A
Published: November 2021

Introduction

The Global Platform for the Prevention of Autoimmune Diabetes-SINT1A Study is designed as a randomised, placebo-controlled, double-blind, multicentre, multinational, primary prevention study aiming to assess whether daily administration ofBifidobacterium infantisfrom age 7 days to 6 weeks until age 12 months to children with elevated genetic risk for type 1 diabetes reduces the cumulative incidence of beta-cell autoantibodies in childhood.

Methods and analysis

Infants aged 7 days to 6 weeks from Germany, Poland, Belgium, UK and Sweden are eligible for study participation if they have a >10.0% expected risk for developing multiple beta-cell autoantibodies by age 6 years as determined by genetic risk score or family history and HLA genotype. Infants are randomised 1:1 to daily administration ofB. infantisEVC001 or placebo until age 12 months and followed for a maximum of 5.5 years thereafter. The primary outcome is the development of persistent confirmed multiple beta-cell autoantibodies. Secondary outcomes are (1) Any persistent confirmed beta-cell autoantibody, defined as at least one confirmed autoantibody in two consecutive samples, including insulin autoantibodies, glutamic acid decarboxylase, islet tyrosine phosphatase 2 or zinc transporter 8, (2) Diabetes, (3) Transglutaminase autoantibodies associated with coeliac disease, (4) Respiratory infection rate in first year of life during supplementation and (5) Safety. Exploratory outcomes include allergy, antibody response to vaccines, alterations of the gut microbiome or blood metabolome, stool pH and calprotectin.

Ethics and dissemination

The study was approved by the local ethical committees of the Technical University Munich, Medical Faculty, the Technische Universität Dresden, the Medizinische Hochschule Hannover, the Medical University of Warsaw, EC Research UZ Leuven and the Swedish ethical review authority. The results will be disseminated through peer-reviewed journals and conference presentations and will be openly shared after completion of the study.

Trial registration number

NCT04769037.