bluuebunny/crossref_metadata_2025 huggingface dataset:
The costs and benefits of estimating T1 of tissue alongside cerebral blood flow and arterial transit time in pseudo‐continuous arterial spin labeling
Authors: Bladt Piet , den Dekker Arnold J. , Clement Patricia , Achten Eric , Sijbers Jan
Published: November 2019

Multi‐post‐labeling‐delay pseudo‐continuous arterial spin labeling (multi‐PLD PCASL) allows for absolute quantification of the cerebral blood flow (CBF) as well as the arterial transit time (ATT). Estimating these perfusion parameters from multi‐PLD PCASL data is a non‐linear inverse problem, which is commonly tackled by fitting the single‐compartment model (SCM) for PCASL, with CBF and ATT as free parameters. The longitudinal relaxation time of tissue T1t is an important parameter in this model, as it governs the decay of the perfusion signal entirely upon entry in the imaging voxel. Conventionally, T1t is fixed to a population average. This approach can cause CBF quantification errors, as T1t can vary significantly inter‐ and intra‐subject. This study compares the impact on CBF quantification, in terms of accuracy and precision, of either fixing T1t, the conventional approach, or estimating it alongside CBF and ATT. It is shown that the conventional approach can cause a significant bias in CBF. Indeed, simulation experiments reveal that if T1t is fixed to a value that is 10% off its true value, this may already result in a bias of 15% in CBF. On the other hand, as is shown by both simulation and real data experiments, estimating T1t along with CBF and ATT results in a loss of CBF precision of the same order, even if the experiment design is optimized for the latter estimation problem. Simulation experiments suggest that an optimal balance between accuracy and precision of CBF estimation from multi‐PLD PCASL data can be expected when using the two‐parameter estimator with a fixed T1t value between population averages of T1t and the longitudinal relaxation time of blood T1b.
Feasibility of 31P spectroscopic imaging at 7 T in lung carcinoma patients
Authors: van Houtum Quincy (.Q.). , Mohamed Hoesein Firdaus (.F.A.A.). , Verhoeff Joost (.J.J.C.). , van Rossum Peter (.P.S.N.). , van Lindert Anne (.A.S.R.). , van der Velden Tijl (.T.A.). , van der Kemp Wybe (.W.J.M.). , Klomp Dennis (.D.W.J.). , Arteaga de Castro Catalina (.C.S.).
Published: November 2019

Currently, it is difficult to predict effective therapy response to molecular therapies for the treatment of lung cancer based solely on anatomical images. 31P MR spectroscopic imaging could provide as a non‐invasive method to monitor potential biomarkers for early therapy evaluation, a necessity to improve personalized care and reduce cost. However, surface coils limit the imaging volume in conventional 31P MRSI. High‐energetic adiabatic RF pulses are required to achieve flip angle homogeneity but lead to high SAR. Birdcage coils permit use of conventional amplitude modulated pulses, even over large FOV, potentially decreasing overall SAR massively. Here, we investigate the feasibility of 3D 31P MRSI at 7 T in lung carcinoma patients using an integrated 31P birdcage body coil in combination with either a dual‐coil or a 16‐channel receiver.

Simulations showed a maximum decrease in SNR per unit of time of 8% for flip angle deviations in short TR low flip‐angle excitation 3D CSI. The minimal SNR loss allowed for fast 3D CSI without time‐consuming calibration steps (>10:00 min.). 31P spectra from four lung carcinoma patients were acquired within 29:00 minutes and with high SNR using both receivers. The latter allowed discrimination of individual phosphodiesters, inorganic phosphate, phosphocreatine and ATP. The receiver array allowed for an increased FOV compared to the dual‐coil receiver.

3D 31P‐CSI were acquired successfully in four lung carcinoma patients using the integrated 31P body coil at ultra‐high field. The increased spectral resolution at 7 T allowed differentiation of multiple 31P metabolites related to phospholipid and energy metabolism. Simulations provide motivation to exclude 31P B1 calibrations, potentially decreasing total scan duration. Employing large receiver arrays improves the field of view allowing for full organ coverage. 31P MRSI is feasible in lung carcinoma patients and has potential as a non‐invasive method for monitoring personalized therapy response in lung tumors.
A nonuniform L2 formula of Caputo derivative and its application to a fractional Benjamin–Bona–Mahony‐type equation with nonsmooth solutions
Authors: Lyu Pin , Vong Seakweng
Published: November 2019

To recover the full accuracy of discretized fractional derivatives, nonuniform mesh technique is a natural and simple approach to efficiently resolve the initial singularities that always appear in the solutions of time‐fractional linear and nonlinear differential equations. We first construct a nonuniform L2 approximation for the fractional Caputo's derivative of order 1 < α < 2 and present a global consistency analysis under some reasonable regularity assumptions. The temporal nonuniform L2 formula is then utilized to develop a linearized difference scheme for a time‐fractional Benjamin–Bona–Mahony‐type equation. The unconditional convergence of our scheme on both uniform and nonuniform (graded) time meshes are proven with respect to the discrete H1‐norm. Numerical examples are provided to justify the accuracy.
Transformation of tribological modelling of squeeze flows to simulate the flow of highly viscous adhesives and sealants in manufacturing processes
Authors: Müller Michael , Tong Yan , Fricke Holger , Vallée Till
Published: November 2019

For the description of the flow processes of an adhesive during pressing, existing CFD models are very complex and should be replaced by more efficient methods. The Partially Filled Gap (PFG) model developed for tribological systems, which is firmly established in practice, is used for this purpose. This paper shows an academic example of a comparison between a CFD calculation, the PFG model and an analytical solution based on the Reynolds equation, showing that the PFG method is well suitable to the problem presented. In an outlook the future potential of this approach is discussed.
Comparison of different models for stress singularities in higher order finite element methods for elastic waves
Authors: Bulling Jannis , Gravenkamp Hauke
Published: November 2019

In this contribution, we present three models to capture singularities in combination with the Spectral Element Method. The first model, the continued‐fraction‐based Scaled Boundary Finite Element Method, the second model, a new approach based on enrichment with static modes, and the third model, which uses an hp‐refinement near the singularity, are compared among each other and evaluated in terms of their respective efficiency and accuracy.
Investigation of the Electrodeposition Parameters on the Coating Process on Open Porous Media
Authors: Grill Christine , Jung Anne , Diebels Stefan
Published: November 2019

Porous materials such as bones, sponges or cork are used in nature due to their light weight. Metal foams with stochastically distributed pores are such a porous bionic material based on nature. Their low weight and mechanical properties make them perfect for use in aerospace, automotive and building construction industry. To improve the mechanical properties, hybrid metal foams are produced consisting of a substrate foam with a coating applied by electrodeposition. An electrochemical coating cell consists of a positively charged anode and a negatively charged cathode. The metal of the anode is oxidised to a positively charged cation and electrons. The cation moves through the electrolyte to the cathode, where it is reduced back to the metal and electrons are consumed. Due to this process the cathode is coated with the anode material. The mass transport during the electroplating process can be divided into four parts: Convection, diffusion, migration and reaction. Convection is a forced flow, e.g. by pumping. Diffusion describes the movement caused by concentration gradients and the migration is the movement by an electric field. Reaction is the ion consumption at the cathode during the electrodeposition process and is therefore called sink. During the electrodeposition process, coating thickness inhomogeneities occur due to mass transport limitations [2,4] and lead to non‐uniform mechanical properties within the coated foams. These inhomogeneties motivate an investigation of the electrodeposition process and its parameters.
Model‐Free Adaptive Control Method Applied to Vibration Reduction of a Flexible Crane as MIMO System
Authors: Pham Hoang Anh , Söffker Dirk
Published: November 2019

Model‐free adaptive control (MFAC) approaches are able to be used when system models are not available and some task‐ or system‐specific conditions are fulfilled. This avoids to require exact mathematical models with respect to consideration of modeling errors even in the case of nonlinear systems to be controlled. The control strategy denoted as model‐free when for controller design only the available system data is used. In this contribution based on the knowledge of MFAC, an extension of the existing approach is presented and applied to unknown multivariable systems. The main control idea is that an estimation of real‐time system parameters which represent system dynamical variations is realized by using only inputs and outputs. A novel control algorithm is derived by minimizing both output tracking error and its derivative. The designed controller is applied to a flexible crane, representing a class of MIMO systems. The simulation results demonstrate that the vibrations of a crane system could be reduced significantly.
Numerical simulation of suction cavitation in hydrodynamic journal bearings
Authors: Schmidt Marcus , Reinke Peter , Beckmann Tom
Published: November 2019

The prediction of cavitation in journal bearings is one of the current challenges in the field of computational fluid dynamics. Hydrodynamic journal bearings are used in a wide range of technical and industrial applications because they provide low friction and minimal wear. A failure of the bearing system during operation can be caused by suction cavitation. Cavitation describes the phase change from liquid to vapour of a fluid caused by a decrease in pressure below the fluid's vapour pressure at an approximately constant temperature. The implosion of vapour cavities adjacent to the surface of the bearing liner stresses the liner material which in turn can lead to material erosion. The particular case of suction cavitation can be observed, if the bearing is operated under high loads resulting in high eccentricity between shaft and bushing combined with a significant increase in gap width. Suchlike operating conditions are not uncommon for internal combustion engines with a power of 0.1 to 1.0 MW per cylinder. As a result of the transient shaft displacement a suction effect builds up within in the lubricating film accompanied with a strong pressure gradient. Due to the fluid dynamics of the lubricant film flow at the given pressure gradient, the liquid can only equalize the void caused by the shaft displacement until the fluid pressure reaches the vapor pressure and then vapor is generated. The vapor forms a three‐dimensional layer across the lubricating film. Whereas, current flow calculations for hydrodynamic journal bearings are carried out by means of 2D methods which are limited to analyze the three‐dimensional and transient flow in those areas of the journal bearing where cavitation occurs. This work presents the application of a transient, 3D numerical simulation of the two‐phase fluid flow in a journal bearing under conditions of cavitation. The numerical simulations were performed using the code OpenFOAM, which is based on the finite volume method and uses time‐dependent three‐dimensional, incompressible Navier‐Stokes equations. The study on hand discusses the influence of minimal film thickness and displacement velocity vs. the structure of the vapour distribution. The numerical results include images of complex three‐dimensional flow structures and vapor distributions inside the lubricating film.
Determination of material parameters for a multiphasic modeling of hydrogels
Authors: Mau Beatrice , Erfkamp Jan , Guenther Margarita , Wallmersperger Thomas
Published: November 2019

Stimuli‐responsive hydrogels are electroactive polymers classified as smart materials, consisting of a solid, fluid and ionic phase. As a result of external stimuli, for example through a variation of the chemical conditions in the surrounding solvent, the hydrogels undergo a reversible volume transformation caused by the absorption or the release of solvent. By using a multiphasic model based on the Theory of Porous Media the chemo‐electro‐mechanical interaction of the different phases can be described. Therefore this model requires a large amount of material parameters, whose determination poses a challenge. To determine the parameters for the mechanical behavior it should be ensured that an interaction of the different phases (solid and fluid) and the surrounding solution bath is realized in order to investigate the viscoelastic behavior of the hydrogel. In the present research, a tensile test is performed to identify the mechanical properties of such stimuli‐responsive hydrogels. Therefore, a specific focus is placed on the dependence of these properties on the solid‐fluid ratio due to the multiphasic composition of this material. The aim of this research is to ameliorate the material equations of the modeling and consequently enhance a prediction of the mechanical behavior.
Efficient phase‐field modelling of fatigue crack propagation
Authors: Seiler Martha , Linse Thomas , Hantschke Peter , Kästner Markus
Published: November 2019

Fatigue loads come along with high numbers of load cycles which makes the simulation of fatigue fracture computationally very demanding. We present a numerically efficient method which avoids resolving the loading path and instead requires only one increment per load cycle at most. We combine the phase‐field method for fracture with a classic fatigue concept. A local lifetime variable is obtained, which we use to modify the material resistance incrementally in order to consider the progressive weakening of the material. Focussing on ductile material behaviour, we make use of an elasto‐plastic revaluation technique instead of a full plastic material model. The model allows to describe fatigue crack initiation as well as propagation and reproduces Paris behaviour.
What can we learn from information‐entropy about turbulence and Large‐Eddy‐Simulation?
Authors: Engelmann Linus , Wlokas Irenäus , Kempf Andreas M.
Published: November 2019

The Shannon entropy is a rigorous measure of information that can be used to evaluate the properties of information in turbulent flows. In this study, the behavior of the Shannon entropy is investigated for LES of an incompressible turbulent channel flow based on the classical DNS of Moser et al.. The Shannon entropy is calculated from the velocity fluctuation fields and is compared to the turbulent kinetic energy. The quality and resolution of the LES calculations on different grids has been evaluated against DNS results. The Shannon entropy is calculated for velocities and the turbulent viscosity to observe how it behaves and how it is related to the simulation quality and grid resolution.
Challenges and perspectives in brain tissue testing and modeling
Authors: Budday Silvia , Holzapfel Gerhard A. , Steinmann Paul , Kuhl Ellen
Published: November 2019

While long underestimated, more and more evidence confirms that mechanics play a critical role for brain function and dysfunction. Therefore, computational simulations based on the field equations of nonlinear continuum mechanics can provide important insights into the underlying mechanisms of brain injury and disease. Realistic numerical predictions, however, require models capable of capturing the complex and unique mechanical behavior of this ultrasoft, highly heterogeneous and adaptive tissue. In recent years, contradictory experimental results have retarded progress in this field. Here, we summarize the key characteristics of brain tissue behavior on different length and time scales and propose application‐specific modeling approaches, which are as complex as necessary but as simple as possible. The presented considerations will, on the one hand, facilitate well‐designed future experiments and, on the other hand, help to choose the appropriate constitutive law for a specific application.
Numerical investigations about the use of lattice structures in energy absorbing systems
Authors: Bühring Jannik , Aghdam Nima Jafarzadeh , Mekala Narasimha Rao , Schröder Kai-Uwe
Published: November 2019

Conventional crash structures normally use areal folding mechanisms to absorb energy. In this work, we show an alternative design concept by using three dimensional lattice structures. The study shows that the cell parameters of bending and tension dominated unit cells have great influences on the specific energy absorption. For bending dominated cells face‐centred cubic cells with vertical struts (f2ccz) and for tensions dominated cells, 3D re‐entrant auxetic structures are used. To investigate the influences of the cell parameters on the energy absorption a numerical parametric study is done.
Tuning of vibration and wave propagation characteristics in pre‐deformed periodic lattice frame structures
Authors: Mellmann Marius , Zhang Chuanzeng
Published: November 2019

The design, optimization and application of periodic materials and structures, such as phononic crystals and structures, are receiving increasing attention in recent years. Such materials and structure can manipulate the characteristics of the elastic and acoustic wave propagation [1]. Thus, it is feasible to create the so‐called band‐gaps, designating certain frequency ranges, in which the propagation of elastic or acoustic waves is prohibited [2]. Accordingly, such structures have many promising applications in sound and vibration insulation as well as wave filters. In this paper, pre‐deformed periodic lattice frame structures for the tuning of the vibration and wave propagation characteristics are investigated.
Effect of uncertain parameters on the deflection of beams
Authors: Reppel Thomas , Korzeniowski Tim Fabian , Weinberg Kerstin
Published: November 2019

In the classical Euler‐Bernoulli cantilever beam theory the deflection w depends on different parameters. On the one hand we have material and geometric parameters, like the Young's Modulus E, the second moment of area I and the length of the beam L. On the other hand there are different loading types like point loads F, distributed loads, or varying loads. All these parameters are usually modeled in a deterministic way. In this contribution we analyze the distribution of the maximum beam deflection of a cantilever beam wmax depending on uncertain parameters. To this end we model the input parameters as random variables (XF, XL, XE) or different random fields (Ei). For the random fields Monte‐Carlo simulations are used to calculate the resulting distribution.
On the transformation laws for the macro to micro transformation
Authors: Jahn Momme , Meywerk Martin
Published: November 2019

In this contribution a transformation from macro‐ to micro‐mechanical quantities is shown. The macro‐scale is treated with the Cosserat‐continuum and is simulated with the Finite‐Element‐Method (FEM), while the body in micro‐scale is simulated with the Discrete‐Element‐Method (DEM). The transformation preserve the mass, the kinetic energy, the momentum, the moment of momentum and the energy of stress, couple stress and volume forces.
On EDP‐convergence for gradient systems with different time scales
Authors: Stephan Artur
Published: November 2019

Motivated by the author's work on evolutionary Γ‐convergence of slow‐fast‐reaction systems, we consider a simple evolution equation, an exponential decay which depends very singularly on a small parameter ϵ > 0: the decay rate is proportional to 1/ϵ. Nevertheless the evolution equation can be understood as a gradient system for which structural convergence, the so‐called EDP‐convergence, has been established in recent years. We investigate evolutionary Γ‐convergence based on the energy‐dissipation principle (EDP) for that simple singularly behaving evolution equation.
Numerical Approximation of Heat Transfer on Heterogenous Media
Authors: Scheuermann Tobias M. , Kotyczka Paul , Zanota Marie-Line , Pitault Isabelle , Louati Haithem , Maschke Bernhard
Published: November 2019

In this paper we show the discrete modeling of the heat equation on an open cell metallic foam, exploiting its geometric structure. The topology of the material is described using the incidence matrices of a so called k‐complex. Together with the discrete constitutive equations, a finite‐dimensional model in port‐Hamiltonian form is found.
Phase field modeling of interface effects on cracks in heterogeneous materials
Authors: Kuhn Charlotte , Müller Ralf
Published: November 2019

One of the reasons why the phase field approach has become very popular for modeling fracture processes is that therein the entire evolution of fracture follows from energetic principles without the need for different criteria for crack initiation, nucleation, kinking or branching. Furthermore, these models allow for a straightforward numerical implementation with standard finite elements, since displacement jumps and stress singularities are avoided in these models. Consequently, phase field fracture models are now also used to model and simulate fracture of heterogeneous materials such as composites, where cracks may be arrested, deflected or bifurcated at interfaces between the different components of the composite material, resulting in complicated crack patterns. The crack propagation is not only controlled by the elastic and fracture properties of the bulk phases of the material but also by the properties of the interfaces in between. Thus, it is crucial to take these interface properties into account. Therefore in this work, interfaces are equipped with a fracture energy corresponding to the phase field fracture energy of the bulk phases in order to model the interface fracture properties. In the finite element implementation, the interfaces are modeled by means of surface elements without introducing additional degrees of freedom.
Application of Recurrent Neural Networks in the numerical analysis of reinforced concrete structures considering polymorphic uncertainty
Authors: Leichsenring Ferenc , Fuchs Alexander , Graf Wolfgang , Kaliske Michael
Published: November 2019

The realistic modelling of structures is fundamental for their numerical simulation and is mainly characterized by the physical approach and the consideration of the available data by an adequate uncertainty description. The key idea in the contribution at hand is the consideration of polymorphic uncertainty in the numerical structural analysis and in the mechanical modelling for reinforced concrete structures, which are characterized by a combination of heterogeneous concrete and different types of reinforcement (e.g. steel bars or woven carbon fibres). Typically, the reinforcement is determined by another length scale compared to the overall structural size. The formulation and development of a computational homogenization approach, considering the different homogeneous and heterogeneous characteristics of a macroscopic structure, are essential for a realistic numerical computation. In recent years, focal point of research was on structural analysis considering uncertain material or geometry parameters. Probabilistic approaches are dominating the uncertainty consideration currently, although they are associated with specific disadvantages and limitations. In this contribution, a generalized uncertainty model is utilized in order to take variability, impression as well as inaccuracy, vagueness and incompleteness into account. This allows a separated evaluation of the influence for each uncertainty source on the results. Therefore, polymorphic uncertainty models are applied and developed by combining aleatoric and epistemic uncertainty descriptions, resulting e.g. in the formulation of the uncertainty model “fuzzy probability based randomness”. The information of the different length scales is considered to be uncertain, e.g. the geometry or the material properties of a representative volume element (RVE) at the meso scale. Subsequently, the uncertainty of a macro structure is derived from uncertain results on the meso structure. In the contribution, a parametrized RVE for concrete structures, including cement phase as well as aggregates, is presented. Various material parameters are considered as uncertain, which results in uncertain effective quantities. Assuming, that an uncertain quantity is substitutable by a combination of a representative measure and multiple uncertainty characterizing measures, an approximation of both type of quantities by a recurrent neural network is carried out. The surrogate models are utilized as constitutive description in a numerical structural analysis on macro level, providing uncertain structural responses.
Development of a novel damage approach on the microstructure for modeling woven ceramic matrix composites
Authors: Reuvers Marie-Christine , Rezaei Shahed , Brepols Tim , Reese Stefanie
Published: November 2019

Ceramic Matrix Composites (CMC) overcome limitations associated with classical technical ceramics e.g. low fracture toughness and brittle failure under mechanical or thermomechanical loading [1]. Their high temperature stability and low weight makes them attractive for use in various fields, especially aerospace industry, where they improve engine efficiency compared to metal components. However current CMCs lack well established material property design databases for a reliable use in critical aerospace structures. Demonstrating the durability of this relatively new class of materials is the challenge to face and therefore the failure mechanisms need to be investigated further. This contribution deals with the successive development of a woven representative volume element (RVE) for arbitrary CMCs. In contrast to previously developed continuum mechanical or laminate theory based modeling approaches, the introduced model combines various damage formulations. The fiber bridging effect, resulting from the weak interface bond of matrix and reinforcement, is governed by the use of cohesive zone (CZ) elements [2]. Whereas the matrix damage is represented using a continuum mechanical approach [3].
Hierarchical Parcel‐Swapping: An efficient mixing model for turbulent reactive flows
Authors: Starick Tommy , Schmidt Heiko
Published: November 2019

Hierarchical Parcel‐Swapping (HiPS) developed by A.R. Kerstein [J. Stat. Phys. 153, 142‐161 (2013)] is a computationally efficient and novel model for the effects of turbulence on time‐evolving, diffusive scalar fields. The characteristic feature of HiPS is the interpretation of the one‐dimensional flow domain or a state space as a binary tree structure. Every tree level corresponds to a specific length and time scale, which is based on a turbulence inertial range scaling. The state variables reside at the base of the tree and are interpreted as fluid parcels. The effects of turbulent advection are represented by stochastic swaps of sub‐trees at rates determined by turbulent time scales associated with the sub‐trees. The mixing of adjacent fluid parcels is done at rates consistent with the prevailing diffusion time scales. In this work, we investigate the influence of turbulent time scale variations on an isothermal series‐parallel reaction scheme. The production of a desired chemical species is evaluated by means of a defined selectivity and is strongly affected by the underlying mixing time scales.
The effect of OCoAl‐LDH and OCoFe‐LDH on the combustion behaviors of polyvinyl chloride
Authors: Gao Zehua , Lu Lihong , Shi Congling , Qian Xiaodong
Published: November 2019

The effects of the modified layered double hydroxide (LDH) of Co/Al (OCoAl‐LDH) and the modified LDH of Co/Fe (OCoFe‐LDH) on the combustion behaviors of polyvinyl chloride (PVC) during pyrolysis processes were compared and investigated. The thermal degradation and combustion behavior of the PVC composites were investigated by thermogravimetric analysis (TGA), microscale combustion calorimetry (MCC), and cone calorimetry (CONE). The results indicate that the incorporation of LDHs brought about the improved thermal stability and reduced heat release of PVC composites at a high temperature. The smoke‐suppression properties of the composites are investigated by steady‐state tube furnace (SSTF), and the results indicated that the toxic gases such as CH4, CO, and NxO were inhibited by both of the two LDHs, but the OCoFe‐LDH has a better effect on the smoke suppression. Subsequently, the char layer was investigated by scanning electron microscopy–energy‐dispersive spectrometry (SEM‐EDS) and Raman analysis. The results indicate that the LDHs can promote the dechlorination of PVC during the thermal oxidation process and can inhibit the production of HCl in inert gas. Generally, OCoAl‐LDH and OCoFe‐LDH can be potential catalysts for waste disposal and can improve the fire safety of PVC.
Effect of different ionic layered compounds decorated with zinc hydroxystannate on flame retardancy and smoke performance of epoxy resin
Authors: Xu Wenzong , Li Wu , Wang Xiaoling , Zhang Xuemin , Cheng Zihao
Published: November 2019

ZHS@ Mg‐Al‐LDH and ZHS@α‐ZrP hybrid materials were prepared by electrostatically loading zinc hydroxystannate (ZHS) on the layered compounds (Mg‐Al‐LDH and α‐ZrP) in this work. With the addition of 2 wt% of the two hybrid materials to epoxy resin (EP), respectively, the fire hazard of EP and its composites were investigated. The limiting oxygen index (LOI) of ZHS@ Mg‐Al‐LDH/EP composite increased by 19.0% compared with pure EP, while its peak heat release rate (PHRR), total heat release rate (THR), and peak smoke release rate (SPR) decreased by 48.2%, 20.8%, and 21.6%, respectively, evidenced by the results of the LOI test and cone calorimetry test (CCT). The LOI of ZHS@α‐ZrP/EP composite increased by 20.4%, and its PHRR, THR, and SPR decreased by 47.7%, 21.4%, and 27.1%, respectively. Both hybrid materials showed prominent flame retardant and smoke suppressing properties. In addition, through the analysis of the TG‐IR and Raman spectrum of residual char, the specific mechanism of flame retardance and smoke suppression was explored.
Estimated number of adult survivors of childhood cancer in United States with cancer‐predisposing germline variants
Authors: Wilson Carmen L. , Wang Zhaoming , Liu Qi , Ehrhardt Matthew J. , Mostafavi Roya , Easton John , Mulder Heather , Hedges Dale J. , Wang Shuoguo , Rusch Michael , Edmonson Michael , Levy Shawn , Lanctot Jennifer Q. , Currie Kelsey , Lear Matthew , Patel Aman , Sapkota Yadav , Brooke Russell J. , Moon Wonjong , Chang Ti‐Cheng , Chen Wenan , Kesserwan Chimene A. , Wu Gang , Nichols Kim E. , Hudson Melissa M. , Zhang Jinghui , Robison Leslie L. , Yasui Yutaka
Published: November 2019

Purpose

To estimate the absolute number of adult survivors of childhood cancer in the U.S. population who carry a pathogenic or likely pathogenic variant in a cancer predisposition gene.

Methods

Using the Surveillance, Epidemiology, and End Results (SEER) Program, we estimated the number of childhood cancer survivors on December 31, 2016 for each childhood cancer diagnosis, multiplied this by the proportion of carriers of pathogenic/likely pathogenic variants in the St. Jude Lifetime Cohort (SJLIFE) study, and projected the resulting number onto the U.S. population.

Results

Based on genome sequence data, 11.8% of 2450 SJLIFE participants carry a pathogenic/likely pathogenic variant in one of 156 cancer predisposition genes. Given this information, we estimate that 21 800 adult survivors of childhood cancer in the United States carry a pathogenic/likely pathogenic variant in one of these genes. The highest estimated absolute number of variant carriers are among survivors of central nervous system tumors (n = 4300), particularly astrocytoma (n = 1800) and other gliomas (n = 1700), acute lymphoblastic leukemia (n = 4300), and retinoblastoma (n = 3500). The most frequently mutated genes are RB1 (n = 3000), NF1 (n = 2300), and BRCA2 (n = 800).

Conclusion

Given the increasing number of childhood cancer survivors in the United States, clinicians should counsel survivors regarding their potential genetic risk, consider referral for genetic counseling and testing, and, as appropriate, implement syndrome‐specific cancer surveillance or risk‐reducing measures.
The association of mediastinal mass in the formation of thrombi in pediatric patients with non‐lymphoblastic lymphomas
Authors: Gartrell Jessica , Kaste Sue C. , Sandlund John T. , Flerlage Jamie , Zhou Yinmei , Cheng Cheng , Estepp Jeremie , Metzger Monika L.
Published: November 2019

Background

Children diagnosed with cancer are at a significantly higher risk of developing a thrombotic event (TE) compared with the general population. The rarity of these events makes it difficult to discern the specific risk factors; however, age, sex, presence of central venous lines, inherited thrombophilia, and mediastinal mass may play a role. The primary aim of this study is to identify prognostic characteristics of children diagnosed with non‐lymphoblastic lymphomas associated with a greater risk of developing a TE early on in their disease, with an increased focus on mediastinal mass characteristics.

Methods

Retrospective chart review of pediatric patients diagnosed with non‐lymphoblastic lymphoma between 2004 and 2014 at St. Jude Children's Research Hospital.

Results

TE occurred in 8.5% (n = 28/330) of individuals at a median of 21 days from the diagnosis of a non‐lymphoblastic lymphoma, with 60% of TEs occurring within 30 days of diagnosis. Of the variables evaluated, only presence of a peripherally inserted central catheter (odds ratio [OR]: 3.14 [95% CI: 1.24‐7.98; P = 0.02]) and degree of superior vena cava (SVC) compression of > 25% increased the odds of developing a TE (OR: 2.2 [95% CI: 1.01‐4.93; P = 0.048]).

Conclusion

Pediatric patients with non‐lymphoblastic lymphoma are at increased risk of developing TEs. In contrast to previous studies, the presence of a mediastinal mass alone was not associated with a higher risk of TE, but individuals with a mediastinal mass with 25% or greater degree of SVC compression were more likely to develop a TE. This finding highlights a high‐risk group of children who may benefit from prophylactic anticoagulation.
Hypoalbuminemia in children with cancer treated with chemotherapy
Authors: McLean Thomas Williams , Stewart Ryan Michael , Curley Thomas Patrick , Dewsnup Mark Young , Thomas Sydney Gillian , Russell Thomas Bennett , Tooze Janet Austin
Published: November 2019

Background

Hypoalbuminemia is a well‐recognized finding associated with cancer, but its prevalence and prognostic significance have not been well studied in children with cancer.

Objective

To determine the prevalence of hypoalbuminemia prior to starting chemotherapy in children with cancer and its association with relapse‐free survival (RFS) and overall survival (OS).

Design/method

We performed a single institution, IRB‐approved, retrospective review of pediatric oncology patients diagnosed between 1998 and 2012. Five‐year survival was estimated using the Kaplan‐Meier method; groups were compared using Cox regression.

Results

We identified 659 pediatric patients with a first diagnosis of cancer and a serum albumin level prior to starting chemotherapy. Mean age was 8.6 years (SD = 5.8); 62% were male and 92% were non‐Hispanic. Hypoalbuminemia prior to starting chemotherapy was present at least once in 302 (45.8%). The five‐year RFS and OS of those with hypoalbuminemia and without hypoalbuminemia were not significantly different. However, patients with severe hypoalbuminemia (defined as a value 10% or more below the lower limit of normal) had inferior RFS and OS for patients with hematologic/lymphatic malignancies, and inferior RFS for patients with metstatic Ewing sarcoma.

Conclusion

Hypoalbuminemia prior to starting chemotherapy in pediatric oncology patients is common (nearly half in this cohort). Severe hypoalbuminemia was associated with inferior 5‐year RFS in some subgroups.
Development of a comprehensive pediatric oncology rehabilitation program
Authors: L'Hotta Allison J. , Beam Irene A. , Thomas Kristin M.
Published: November 2019

Comprehensive cancer rehabilitation programs are essential to enhance patient outcomes. Services vary by institution, and few oncology programs have comprehensive cancer rehabilitation programs. Current rehabilitation program recommendations focus on the needs of adults; the unique needs of children and adolescents with cancer also require attention. Pediatric oncology rehabilitation is an emerging area of practice, and more pediatric institutions are exploring how to develop consistent and streamlined services. To assist practitioners in program development and to raise awareness of the rehabilitation needs of this population throughout the continuum of care, we describe the development of a multidisciplinary pediatric cancer rehabilitation program.
Exploring heterogeneity of adrenal cortical tumors in children: The French pediatric rare tumor group (Fracture) experience
Authors: Picard Cécile , Faure‐Conter Cécile , Leblond Pierre , Brugières Laurence , Thomas‐Teinturier Cécile , Hameury Frédéric , Defachelles Anne‐Sophie , Verschuur Arnauld , Brisse Hervé J , Sarnacki Sabine , Dijoud Frédérique , Reguerre Yves , Chastagner Pascal , Carton Matthieu , Orbach Daniel
Published: November 2019

Introduction

Pediatric adrenal cortical tumors are characterized by a wide spectrum of behavior. Questions remain regarding intermediate disease stages with isolated tumor rupture or relapse.

Objectives

To describe clinical characteristics, treatment strategy, and outcome of patients depending on disease stage, tumor rupture, or in case of a refractory tumor, to discuss optimal management.

Material and methods

Pediatric patients with histological material reviewed and treated between 2000 and 2018 in 23 French oncology centers were included.

Results

Among 95 cases, 59% of patients had stage I tumors (n = 55), 16% had stage II tumors (n = 16), 19% had stage III tumors (n = 17), and 5% had stage IV tumors (n = 5) (missing data: 2). Overall, 27% of patients (n = 25) had an unfavorable histology. Initial tumor resection was performed for 90% of patients (n = 86). Systemic therapies included mitotane in 20 cases and chemotherapy in 13 cases. Among 17 stage III patients, 12 had microscopic residual tumor due to an initial biopsy (n = 5), intraoperative rupture (n = 8), or surgical resection with microscopic residue or tumor spillage surgery (n = 1) (two patients with two modalities). After a median follow‐up of 96 months (25‐119), four early progressions and two relapses occurred. A total of seven patients died, including five of disease. Stage III diseases due to microscopic residual disease correlated with a worse prognosis: 5‐year progression‐free survival 44% (95% CI, 22‐87%) versus 82% (95% CI, 73‐91%) for the whole cohort (P < .0001). Among the 14 patients with refractory disease, only 3 were alive and free of disease after multimodal second‐line therapy.

Conclusions

Stage III diseases due to a microscopic residual tumor have a dismal prognosis, arguing for the systematic use of adjuvant therapy. Patients with a relapsed disease should be included in experimental studies.
Prenatal cerebral imaging features of a new syndromic entity related to KIAA1109 pathogenic variants mimicking tubulinopathy
Authors: Cabet Sara , Putoux Audrey , Buenerd Annie , Gueneau Lucie , Reymond Alexandre , Thia Edwin W.H. , Lai Angeline H.M. , Schindewolf Erica M. , Sanlaville Damien , Lesca Gaetan , Guibaud Laurent
Published: November 2019

What's already known?

KIAA1109 pathogenic variants are associated with disorders of brain development ranging from major cerebral malformations to moderate cerebral atrophy.

The most severe form of tubulinopathies includes microlissencephaly, voluminous germinal matrices and brainstem dysgenesis.

What does this study add?

The prenatal cerebral pattern of the most severe form of KIAA1109‐related disorder can be similar to the one found in tubulinopathies but was, in our short series, associated with clubfoot and/or arthrogryposis and, in some cases, with cardiac and ophthalmologic anomalies.
Quantifying how small variations in design elements affect risk in an incident cohort study in claims
Authors: Izem Rima , Huang Ting‐Ying , Hou Laura , Pestine Ella , Nguyen Michael , Maro Judith C.
Published: November 2019

Background

Epidemiological study reporting is improving but is not transparent enough for easy evaluation or replication. One barrier is insufficient details about design elements in published studies.

Methods

Using a previously conducted drug safety evaluation in claims as a test case, we investigated the impact of small changes in five key design elements on risk estimation. These elements are index day of incident exposure's determination of look‐back or follow‐up periods, exposure duration algorithms, heparin exposure exclusion, propensity score model variables, and Cox proportional hazard model stratification. We covaried these elements using a fractional factorial design, resulting in 24 risk estimates for one outcome. We repeated eight of these combinations for two additional outcomes. We measured design effects on cohort sizes, follow‐up time, and risk estimates.

Results

Small changes in specifications of index day and exposure algorithm affected the risk estimation process the most. They affected cohort size on average by 8 to 10%, follow‐up time by up to 31%, and magnitude of log hazard ratios by up to 0.22. Other elements affected cohort before matching or risk estimate's precision but not its magnitude. Any change in design substantially altered the matched control‐group subjects in 1:1 matching.

Conclusions

Exposure‐related design elements require attention from investigators initiating, evaluating, or wishing to replicate a study or from analysts standardizing definitions. The methods we developed, using factorial design and mapping design effect on causal estimation process, are applicable to planning of sensitivity analyses in similar studies.
Data linkage in pharmacoepidemiology: A call for rigorous evaluation and reporting
Authors: Pratt Nicole L. , Mack Christina D. , Meyer Anne Marie , Davis Kourtney J. , Hammill Bradley G. , Hampp Christian , Setoguchi Soko , Raman Sudha R. , Chun Danielle S. , Stürmer Til , Lund Jennifer L.
Published: November 2019

Purpose

The purpose of this paper is to provide guidance on the evaluation of data linkage quality through the development of a checklist for reporting key elements of the linkage process.

Methods

Responding to a call for manuscripts from the International Society for Pharmacoepidemiology (ISPE), a working group including international representation from the academic, industry, and contract research, and regulatory sectors was formed to develop a checklist for evaluation of data linkage performance and reporting data linkage specifically for pharmacoepidemiologic research. This checklist expands on the reporting of studies conducted using observational routinely collected health data specific to pharmacoepidemiology (RECORD‐PE) guidelines.

Results

A key aspect of data linkage evaluation for pharmacoepidemiology is to articulate how a linkage process was performed and its accuracy in terms of validation and verification of the resulting linked data. This study generates a checklist, which covers domains including data sources, linkage variables, linkage methods, linkage results, and linkage evaluation. For each domain, specific recommendations provide a clear and transparent assessment of the linkage process.

Conclusions

Linking data sources can help to enrich analytic databases to more accurately define study populations, enable adjustment for confounding, and improve the capture of health outcomes. Clear and transparent reporting of data linkage processes will help to increase confidence in the evidence generated from these data by allowing researchers and end users to critically assess the potential for bias owing to the data linkage process.
Enlarging Surface/Bulk Ratios of NiO Nanoparticles toward High Utilization and Rate Capability for Supercapacitors
Authors: Hei Jinpei , Su Liwei , Chen Siyuan , Ye Weijun , Zhan Jing , Wang Lianbang , Gao Yunfang , Wang Hongxia , Wang Yuanhao
Published: November 2019

Reasonable design and delicate control of microstructures are critical to achieve high energy density of active materials for pseudocapacitors that seriously depend on usable reaction interface. This work shows the effect of ultrasmall particle size on enhancing utilization and rate performance of active materials. Three types of NiO nanocrystals with different sizes of 3.36, 6.24, and 7.18 nm in average diameter are uniformly distributed on mesoporous carbon nanosheets derived from corn straw piths. The nanosheets with 3.36 nm NiO particles present an extremely high NiO utilization of 93.4% (2404 F g−1 at 0.5 A g−1), which is 2–2.5‐fold higher than materials with large sizes (6.24 and 7.18 nm). This enhancement is ascribed to more complete conversion and higher ionic/electronic conductivity from a preferable surface/bulk ratio of NiO. By coupling with commercial activated carbon, the asymmetric supercapacitors present high energy and power densities (28.53 Wh kg−1 at 375 W kg−1), with 78.3% capacitance retention after 10 000 cycles at 10 A g−1.
Identifying pneumococci in parapneumonic pleural effusion: Is there a role for culture‐independent methods?
Authors: Pizzutti Kauana , Perez Vinícius P. , Barbiero Caroline , d'Azevedo Pedro A. , Fischer Gilberto B. , Dias Cícero
Published: November 2019

Objective

To evaluate culture‐independent procedures (immunochromatography and quantitative polymerase chain reaction [qPCR]) in the detection and susceptibility of Streptococcus pneumoniae directly from culture‐negative pleural fluid (PF) in children.

Method

Detection of S. pneumoniae in PF of children with parapneumonic effusion and/or empyema by using two culture‐independent methods: an immunochromatographic membrane test (IMT) which identifies the pneumococcal C antigen, and a real‐time PCR test to detect pneumococcal genes lytA and pbp2b, a marker of susceptibility of β‐lactam agents, in PF samples.

Results

We tested 36 PF specimens and recorded the previous use of antimicrobials. In the final analysis, 34 samples were included. IMT and qPCR presented positive results in 23 (67.6%) and 24 (70.6%) of the samples, respectively, showing a moderate agreement (k = 0.518) between the two methods.

From the 36 children included, 34 (94.4%) had antibiotic data available by the time when PFs were collected. Thirty‐four (100%) children had been given treatment before PF sampling, with 33 (97%) receiving β‐lactam antibiotics administered empirically. Of the 24 lytA real‐time positive samples, 21 (87.5%) were also positive for pbp2b, a marker of β‐lactam susceptibility.

Conclusion

The reduced sensitivity of culture for pneumococcal detection can be improved through the addition of IMT and qPCR analysis. The utility of qPCR combining detection of lytA and a marker of β‐lactam susceptibility should be explored further.