bluuebunny/crossref_metadata_2025 huggingface dataset:
Reverse Engineering: Investigation of Optimization Techniques in Point Clouds Registration
Authors: Yacout George , Shoukry Mohamed Kamal
Published: January 2021

The Reverse Engineering industries has an increasing need for remanufacturing of worn out spare parts or spare parts with lost technical data like drawings or CAD models, in this project a new hybrid algorithm is proposed for the rigid registration of point clouds obtained from scanning of spare parts by a laser scanner. The hybrid algorithm is dividing the registration process into two stages called the coarse and fine registration, the coarse registration is performed by the Genetic Algorithm (GA) that yield an approximate transformation between the two point clouds, and then inherit its findings to the fine registration that is performed by the Interior Point method to reach the accurate transformation and the successful registration of the two point clouds. In this research two techniques for point clouds registration are applied, tested, evaluated and compared to each other. It was found that using the GA and Interior point method is a good alternative for registering point clouds. The objective of this work is to register two point clouds successfully with minimum error, and high reliability.
Kinematic Flexibility Analysis of Active and Inactive Kinase Conformations
Authors: Chen Xiyu , Leyendecker Sigrid , van den Bedem Henry
Published: January 2021

Protein kinases are cellular enzymes that catalyze the transfer of phosphates from adenosine triphosphate (ATP) to their substrates. Phosphorylation regulates a multitude of cellular activities, and impaired kinase activity is frequently oncogenic. Inactive or activated forms of kinases are often classified into specific conformations of their activation loops and surrounding areas. This information is valuable for developing potent and selective kinase inhibitors. However, these classification schemes ignore how the dynamics of kinases can differ between states. Here, we apply kinematic flexibility analysis (KFA) to characterize differences in the degree of rigidification between active and inactive states for a large set of kinases in the Protein Data Bank (PDB). Overall, we found that the activation loop in the active state rigidifies kinase conformations, while this effect is less pronounced in the inactive state.
Numerical analysis of plain and fiber reinforced concrete structures during cyclic loading: Influence of frictional sliding and crack roughness
Authors: Gudžulić Vladislav , Neu Gerrit E. , Meschke Günther
Published: January 2021

Concrete is a quasi‐brittle material, characterized by a non‐negligible, finite‐sized fracture process zone (FPZ) in which various toughening mechanisms play a significant role on crack development and propagation. Concrete is often reinforced with fibers to improve the serviceability and longevity of concrete structures by controlling the maximal crack widths and providing residual carrying capacity to initiated cracks. In quasi‐brittle materials such as concrete, toughening mechanisms such as crack deflection due to the presence of large heterogeneities, contact shielding, i.e., wedging and crack closure induced by debris and rough crack faces, crack bridging by tough aggregates, unbroken ligaments and fibers (in fiber‐reinforced concretes), are mostly governing damage evolution under monotonic and especially under cyclic loadings [1]. All these items contribute to a complex non‐linear response in terms of load‐displacement curves observed in experimental investigations. Many investigations have been performed on plain concrete, but not so many for high‐performance fiber‐reinforced concrete [2] which is the main subject of investigation within the DFG Priority Program 2020. In order to better understand the influence of these toughening mechanisms on the formation of hysteresis during cyclic loading‐unloading of plain and steel fiber‐reinforced high‐performance concrete, we model these mechanisms and their evolving influence on damage development using a discrete crack approach, and take into account the imperfect closure of cracks and friction between crack faces that come in contact during loading/unloading of the specimen. Within the scope of this contribution, we present the formulation of the model and illustrate its performance through selected numerical experiments under monotonic and cyclic loading of plain and fiber‐reinforced high‐performance concrete specimens. Model predictions are compared with laboratory measurements.
A least‐squares finite element formulation to solve incompressible non‐Newtonian fluid flow
Authors: Averweg Solveigh , Schwarz Alexander , Nisters Carina , Schröder Jörg
Published: January 2021

The Modeling of non‐Newtonian fluids is an essential issue for many industrial applications, for example in the field of chemistry, bioengineering and medical science. In this contribution we present a least‐squares (LS) finite element approach to model steady flow of incompressible non‐Newtonian fluids based on the Navier‐Stokes equations. The application of the least‐squares finite element method (LSFEM) especially in the case of fluid mechanics is motivated by some theoretical advantages compared to the well‐known (mixed) Galerkin method. The LSFEM is not restricted to the LBB‐condition and results in a minimization problem with symmetric positive definite equation systems also for differential equations with non self‐adjoint operators. Furthermore, the LSFEM provides an inherent a posteriori error estimator without additional costs, which enables an efficiency enhancement through adaptive mesh refinements.

In this contribution the first‐order LS formulation in terms of stresses and velocities, as introduced in [4], is extended to consider the nonlinear dependence of the viscosity on the shear rate of the fluid. Therefore, the well‐known Carreau model for generalized Newtonian fluids, see for instance [1], is investigated. For the approximation of the independent variables, velocities and stresses, we apply conforming discretizations in H1 and H(div) using standard Lagrange interpolation polynomials and vector‐valued Raviart‐Thomas interpolations functions. A flow through a square domain with exact solution is considered to validate the proposed schemes with respect to accuracy and efficiency.
Around the clock ‐ capsule networks and image transformations
Authors: Schmidt Maximilian
Published: January 2021

Capsule networks are a promising new model class for image processing tasks. We investigate and compare their classification performance with convolutional neural networks on a new entry level image data set. In our experiments the capsules are able to learn the effect of rotated input images from data and outperform a comparable convolutional architecture. The results also show that convolutional and capsule networks need structural adjustment to respond to transformations that are not included in the training set.
Lagrangian analysis of long‐term dynamics of turbulent superstructures
Authors: Schneide Christiane , Padberg-Gehle Kathrin , Schumacher Jörg
Published: January 2021

In Rayleigh‐Bénard convection, turbulent superstructures are large‐scale patterns of circulation rolls created by hot ascending and cold descending thermal plumes. The evolution of these large‐scale patterns happens on very large time scales τ [1]. Spectral clustering applied to Lagrangian particle trajectories on time intervals smaller than τ can be used to create clusters displaying a structure similar to the patterns detected in the Eulerian frame of reference [2]. However, this technique is unfeasible for the analysis of the evolution of turbulent superstructures due to turbulent dispersion. Therefore, we test the application of concepts of evolutionary spectral clustering [3] on Lagrangian particle trajectories to analyze the long‐term dynamics of turbulent superstructures in the Lagrangian frame of reference.
Numerical modeling of the mechanical response of bacterial biofilm to flow by using an SPH poroviscoelastic model
Authors: Feng Dianlei , Neuweiler Insa , Liu Moubin , Nackenhorst Udo
Published: January 2021

We present a weakly‐compressible two‐phase poroviscoelastic biofilm model based on Smoothed Particle Hydrodynamics (SPH) method. The biofilm is modeled as a mixture of solid and fluid phases interacting via drag forces. Benefiting from the Lagrangian feature of the SPH method, large deformations of the solid structure can be modeled straightforwardly.
Enhanced integration scheme for unfitted polygonal elements
Authors: Petö Márton , Duvigneau Fabian , Juhre Daniel , Eisenträger Sascha
Published: January 2021

In this contribution a novel integration scheme, extending the conventional quadtree‐decomposition‐based approach by image compression techniques, is investigated for unfitted polygonal meshes with a particular focus on the rational Wachspress shape functions. It is shown that a meaningful reduction of integration points can be achieved without a significant loss in accuracy. However, the full potential of the method in terms of time savings can only be leveraged when applied to higher order polynomial elements. For more information on this topic see Enhanced Numerical Integration Scheme Based on Image Compression Techniques: Application to Rational Polygonal Interpolants by Petö et al. [1].
Large Scale Sea Ice Modeling – Problems and Perspectives.
Authors: Nisters Carina , Schröder Jörg
Published: January 2021

The visco‐plastic sea ice model based on [7] describes the movement of sea ice over large areas of several thousand square kilometers in time. This model has been considered in many publications and has been extended and adapted by numerically motivated and physically‐based approaches. The basic model for the simulation of sea ice circulation considers sea ice velocities and stresses coupled to the field quantities of sea ice thickness and concentration. Two transient advection equations describe the development of sea ice thickness and concentration coupled with sea ice velocity. Furthermore, the viscosity in the constitutive equation is dependent on the sea ice velocities in the sense of a non‐Newtonian fluid, which makes the constitutive relationship strongly nonlinear. An extension of the model is, for example, the elasto‐visco‐plastic constitutive law proposed by [10], which gives numerical stabilization. Recent research on the finite element implementation of the sea ice model is turned to formulations based on the (mixed) Galerkin variation approach, see for example [1] and [20]. Likewise, in [15], [16], and [18] solvers are proposed for the efficient solution of the problem.

In this paper, we discuss the obstacles and possibilities of a sea ice model implementation, among others, within a least‐squares finite element method (LSFEM). The mixed LSFEM is well established in fluid mechanics, and a significant advantage of the method is its applicability to first‐order systems, see e.g. [12]. Thus, this method leads to stable and robust formulations for non‐self‐adjoint systems, as they are, for example, for the tracer equations. Based on the results of the Taylor least‐squares scheme and a first‐order Crank‐Nicolson time integrator scheme for the tracer equations, see [21], we discuss here possible steps towards an adequate solution strategy for the complete sea ice model.
Influence of the correlation lengths on the continuous mode conversion
Authors: Zimmmermann Eugen , Weber Wolfgang
Published: January 2021

To detect damages using guided waves, the local mode conversion of a symmetric S0 mode into an antisymmetric A0 mode can be utilized. In simulations which use a homogeneous material model, the conversion will take place only at structural irregularities, e.g. damages. In contrast, the wave propagation in carbon reinforced plastics (CFRP) is more complex. Due to the irregular arrangement of the fibres, regions with varying fibre volume fraction are present. This spatial fluctuation causes an inhomogeneous material behaviour, which significantly influences the wave propagation. In addition to the primary induced symmetric S0 waves, secondary A0‐waves arise which are caused by the material itself and extends over the entire structure, they are continuous. These are also present if the structure is intact and consequently makes it more difficult to detect damage. In order to include the spatial variation of the material properties in the numerical model, second order random fields, which are fully represented by their mean and covariance, can be used. The random distribution of the material properties over a region can be achieved by Karhunen‐Loève decomposition. The spatial structure of the decomposition and therefore the random field depend on the chosen covariance function.
Topological electromagnetic and elastic states in phoxonic crystal cavity arrays
Authors: Ma Tian-Xue , Zhang Chuanzeng , Wang Yue-Sheng
Published: January 2021

In this paper, we investigate the topological characteristics of the phoxonic crystal (PxC) arrays. For the PxC system, the electromagnetic transverse electric mode and the elastic in‐plane mode are considered. The PxC possesses the photonic and phononic bandgaps simultaneously. Based on the bandgaps, we design the PxC cavity which can confine the electromagnetic and elastic waves. The interaction strength between the neighboring PxC cavities can be tuned by changing the distance between these cavities. The PxC cavity arrays with the topologically non‐trivial and trivial phases are obtained. We combine the PxC arrays with the topologically non‐trivial and trivial phases together. The electromagnetic and elastic topological interface states can be simultaneously observed at the interface of the PxC cavity arrays.
A robustness measure for singular point and index estimation in discretized orientation and vector fields
Authors: Hoffmann Karl B. , Sbalzarini Ivo F.
Published: January 2021

The identification of singular points or topological defects in discretized vector fields occurs in diverse areas ranging from the polarization of the cosmic microwave background to liquid crystals to fingerprint recognition and bio‐medical imaging. Due to their discrete nature, defects and their topological charge cannot depend continuously on each single vector, but they discontinuously change as soon as a vector changes by more than a threshold. Considering this threshold of admissible change at the level of vectors, we develop a robustness measure for discrete defect estimators. Here, we compare different template paths for defect estimation in discretized vector or orientation fields. Sampling prototypical vector field patterns around defects shows that the robustness increases with the length of template path, but less so in the presence of noise on the vectors. We therefore find an optimal trade‐off between resolution and robustness against noise for relatively small templates, except for the “single pixel” defect analysis, which cannot exclude zero robustness. The presented robustness measure paves the way for uncertainty quantification of defects in discretized vector fields.
Solving linear equation systems on noisy intermediate‐scale quantum computers
Authors: Mielke André , Ricken Tim
Published: January 2021

Quantum computing promises classically unparalleled benefits for various applications. Its properties are exploited in the Harrow‐Hassidim‐Lloyd (HHL) algorithm that, in conjunction with quantum phase estimation, is capable of constructing quantum states that are proportional to the solution of linear equation systems and does so exponentially faster than the fastest known classical algorithms. We explore this capability by computing the nodal displacements of a 1‐dimensional loaded cantilever, discretized by using the finite element method (FEM).
Split‐Hopkinson‐Pressure‐Bar simulations using MPM
Authors: Maassen S. F. , Niekamp R. , Schröder J. , Wiederkehr P. , Theisen W.
Published: January 2021

The material point method (MPM) represents a discretization method that combines the beneficial aspects of a Lagrangian representation of material within an Eulerian solution scheme. Deformable bodies are discretized with material points that carry mass, kinematical quantities such as velocity and material history variables. The material points are not connected via a Lagrangian mesh but a computational background mesh. This mesh is arbitrary and hence not subject to critical distortion. Due to this aspect, the MPM shows promising potential to large deformation problems. In the context of the ”Virtual Machining” project, the MPM will be elaborated for metal cutting simulations of a 42CrMo4 heat treatable steel. The first steps towards this application are experimental investigations on the material parameters. To gather data on the rate dependence in the constitutive response of 42CroMo4, Split‐Hopkinson‐Pressure‐Bar (SHPB) experiments were performed. These tests are subject to numerical analysis using the MPM to get a first impression of the method in this kind of problem. This contribution represents a proof of concept for an SHPB analysis on the here chosen MPM scheme.
Multiscale modeling of Retinal Hypoxia due to Age‐related Macular Degeneration
Authors: Timothy Jithender J. , Holla Vijaya , Meschke Günther
Published: January 2021

Age‐related macular degeneration (AMD) is the leading cause of vision loss in older adults above the age of 50. AMD is attributed to the degeneration and loss of normal function of the outer retina in the macular region. Presence of extracellular material called drusen between the Bruch's membrane (BrM) and the retinal pigment epithelium (RPE) is the hallmark of AMD. Moreover, thickening and reduced diffusivity of the BrM has been observed in patients with AMD. In this paper, we investigate the influence of the BrM microstructure and the drusen size on oxygen transport in the outer retina using a multiscale computational modeling approach. The proposed framework comprises of a cascade lattice micromechanics model for characterizing the overall diffusivity of the BrM, a finite element model for simulating oxygen transport from the vascular system to the photoreceptors and a cellular potts model for simulating morphological changes to the outer retina due to drusen development. Simulations for various levels of BrM blockage and drusen size on oxygen supply to the photoreceptors are presented and their significance on AMD development discussed.
Computational analysis of the influence of drusen growth on the morphology of RPE due to Age‐related Macular Degeneration
Authors: Holla Vijaya , Timothy Jithender J. , Meschke Günther
Published: January 2021

Age‐related macular degeneration (AMD) is a disease that affects the macular region of the outer retina. AMD is characterized by the presence of large extracellular debris called drusen between the Bruch's Membrane (BrM) in the choroid and the retinal pigment epithelium (RPE) in the outer retina. An important feature of AMD is the degenerative changes in the RPE and the photoreceptors that leads to the deterioration and loss of central vision. In this contribution, the effect of drusen size on the morphological changes in the RPE, BrM and photoreceptors are investigated using the cellular potts model (CPM) and machine learning. Numerical simulation of the influence of drusen growth and its effect on the morphology of the outer retinal layers of the macula is presented and the implications for AMD progression discussed.
Reformulating Bilevel Problems by SQP Embedding
Authors: Schäfer Kai , Fliege Jörg , Flaßkamp Kathrin , Büskens Christof
Published: January 2021

Due to their inherently complex structure, bilevel optimization problems are often transformed into single‐level problems in order to make them numerically solvable. In this work, we present a novel reformulation strategy, in which we introduce sets of variables and constraints that represent the process of numerically solving the lower‐level problem based on a full step exact Hessian sequential quadratic programming method. The reformulated problem approximates a solution to the original one in the following sense: For a suitable number of imitated lower‐level iteration steps, the lower‐level problem is approximately solved in case a feasible point is found. The approach is illustrated by an example.
A Newmark space‐time approach in structural mechanics
Authors: Bamer Franz , Shirafkan Nima , Cao Xiaodan , Oueslati Abdelbacet , Stoffel Marcus , De Saxcé Géry , Markert Bernd
Published: January 2021

In this contribution, we present a non‐incremental time integration scheme using the implicit Newmark approximations. The result is one space‐time equation that can be solved using the proper general decomposition ansatz.
Active Damping of Thin Film Shape Memory Alloy Devices
Authors: Ahmadi S. , Jacob K. , Wendler F. , Padhy A. , Kohl M.
Published: January 2021

The thermomechanical coupling in shape memory alloys (SMAs) provides an effective mechanism of vibration damping by a cyclic structural phase transition. Here, we present simulations for an active SMA damper device based on a polycrystalline film materials, in which active damping via the one‐way shape memory effect is exploited. We apply an extension of a previously reported superelastic model, that combines transition state kinetics with a phase field approach for the case of shock loading. By this approach, we are able to describe the time‐resolved active damping performance of the device in agreement with experimental results.
A deep learning‐based ensemble filter for nonlinear data assimilation
Authors: Hoang Truong-Vinh , Matthies Hermann G.
Published: January 2021

This article presents a novel deep learning‐based ensemble conditional mean filter (DL‐EnCMF) for nonlinear data assimilation. The filter's key component is the approximation of the conditional expectation (CE) using deep neural networks (DNNs). We implement the DL‐EnCMF for tracking the states of the Lorenz‐63 system. Numerical results show that the DL‐EnCMF outperforms the ensemble Kalman filter (EnKF)—a common technique for data assimilation.
Thermomechanical phase‐field fracture modeling of fluid‐saturated porous media
Authors: Nguyen Cam-Lai , Sweidan Abdel Hassan , Heider Yousef , Markert Bernd
Published: January 2021

In this work, the problem of brittle fracture in a fluid‐saturated porous material is extended by considering the non‐isothermal states of the sample. The temperature field will affect the problem in two aspects: 1) Temperature‐dependent material parameters, such as elasticity modulus (E) and critical energy release rate (Gc). 2) Thermal expansion due to thermo‐mechanical volume coupling. In hydraulic fracturing, we further study the effect of the temperature difference between the injected fluid and the surrounding porous media ambient on the crack behavior. The modeling of the porous media domain is based on the macroscopic theory of porous media (TPM), whereas the phase‐field method (PFM) is applied to approximate the sharp crack edges by diffusive ones. In the numerical implementation, the coupled system of partial differential equations will be solved using the FEM in order to simulate the heat transition in the crack and non‐crack regions.
Crack path comparisons of a mixed phase‐field fracture model and experiments in punctured EPDM strips
Authors: Fehse Andreas , Kröger Nils Hendrik , Mang Katrin , Wick Thomas
Published: January 2021

Working on quasi‐static phase‐field fracture modeling in nearly incompressible solids for crack propagation is a challenging task. To avoid arising locking effects therein, a mixed form for the solid displacement equation is developed, resulting in two unknowns: a displacement field and a hydro‐static pressure variable. In order to fulfil an inf‐sup condition, stable Taylor‐Hood elements are employed for the displacement‐pressure system. The irreversibility condition of the crack evolution is handled by help of a primal‐dual active set method. To get both a sharper crack and reasonable computational costs, adaptive meshes are used based on a predictor‐corrector scheme. The crack paths from the numerical simulations are compared on the experimentally observed crack paths in carbon black filled ethylene propylene diene monomer (EPDM) rubber strips. The punctured EPDM strips with a hole and a given notch at different heights are stretched till total failure.
The Loewner framework for nonlinear identification and reduction of Hammerstein cascaded dynamical systems
Authors: Karachalios Dimitrios S. , Gosea Ion Victor , Antoulas Athanasios C.
Published: January 2021

We present an algorithm for data‐driven identification and reduction of nonlinear cascaded systems with Hammerstein structure. The proposed algorithm relies on the Loewner framework (LF) which constitutes a non‐intrusive algorithm for identification and reduction of dynamical systems based on interpolation. We address the following problem: the actuator (control input) enters a static nonlinear block. Then, this processed signal is used as an input for a linear time‐invariant system (LTI). Additionally, it is considered that the orders of the linear transfer function and of the static nonlinearity are not a priori known.
Limit cycle computation of self‐excited dynamic systems using nonlinear modes
Authors: Tatzko Sebastian , Stender Merten , Jahn Martin , Hoffmann Norbert
Published: January 2021

A self‐excited dynamic system is able to oscillate periodically by itself. Corresponding solutions of the autonomous differential equation are called limit cycles or periodic attractors. To find these solutions, a simple approach would be brute‐force search for the corresponding basins of attraction. However, grid searching might become unfeasible with increasing number of degrees of freedom. Instead, solution path continuation techniques are often used to keep computational costs low. As the continuation of solution branches and their bifurcations provides only solutions which are connected to each other, isolas and detached branches are missed out. We present a method for fast limit cycle detection of self‐excited systems with isolas based on nonlinear modes. A nonlinear mode, often referred to as nonlinear normal mode, is defined as a periodic motion of the undamped and unforced mechanical system. For nonconservative systems however, e.g. with friction nonlinearity, damping cannot be neglected as it is characteristic for the oscillators nonlinear dynamics. Therefore, the Extended Periodic Motion Concept (E‐PMC) was proposed recently to find periodic solutions of nonconservative nonlinear systems. In this work, the E‐PMC is applied to self‐excited dynamic systems in order to find periodic attractors along its nonlinear modes. Zero crossings of the nonlinear damping curve indicate autonomous solutions which can be used as starting points for single parameter continuation. Thus, solutions corresponding to the main branch and detached curves in the solution space are connected by nonlinear modes. The proposed method is applied to a frictional oscillator with cubic stiffness and proves to be robust in the search for isolated periodic solutions that are already known from literature.
Prevalence of short stature among children in China: A systematic review
Authors: Li Fulun , Liu Ke , Zhao Qianlong , Chen Junyi , Liu Lingfei , Xie Qingmu , Yang Jing
Published: January 2021

Importance

The prevalence and characteristics of short stature (SS) among children in China should be assessed to provide guidance for planning and implementation of nationwide public health policies. Thus far, there have been no accurate estimates of the prevalence of SS in China.

Objective

To analyze the prevalence of SS among children in China and to explore the influences of sex, area, age, study year, and study site on prevalence rates.

Methods

Relevant literature was identified by searching the following databases: PubMed, Embase, The Cochrane Library, Chinese Biomedical Literature, China Knowledge Resource Integrated, WeiPu, and WanFang databases. Meta‐analysis was carried out using STATA 11.2.

Results

This meta‐analysis included 39 studies with 348 326 Chinese participants; the studies covered 20 provinces, municipalities, and autonomous regions. The pooled prevalence of SS was 3.2% (95% confidence interval [CI], 2.6%–3.7%; I2 = 99.8%). The prevalence of SS in boys and girls were 3.1% (95% CI, 2.5%–3.7%) and 3.2% (95% CI, 2.6%–3.9%), respectively. The sex difference was not statistically significant (P > 0.05). The prevalence of SS was higher in rural areas than in urban areas (4.7% [95% CI, 3.6%–5.8%] vs. 2.8% [95% CI, 2.2%–3.4%]; P < 0.001). The prevalence of SS was higher in West China (5.2%; 95% CI, 4.4%–6.0%) than in Northeast China (0.6%; 95% CI, 0.3%–0.8%), East China (2.3%; 95% CI, 1.9%–2.8%), or Central China (2.9%; 95% CI, 1.9%–3.9%).

Interpretation

The prevalence of SS among children was higher in western and rural areas of China. Close attention to children’s growth and development is needed to prevent the occurrence of SS.
Portal venous gas resulting from umbilical vein catheterization in a very‐low‐birth‐weight infant with no interruption in early feeding
Authors: Wang Jun , Yue Guang , Yang Hua , Li Jing , Ju Rong
Published: January 2021

Introduction

Portal venous gas (PVG) is common in necrotizing enterocolitis and occasionally occurs in neonates after umbilical vein catheterization (UVC). Therefore, determining the cause of PVG requires further clinical evaluation in these cases.

Case presentation

We report the case of a very‐low‐birth‐weight infant who underwent UVC after birth. PVG was an unexpected finding on ultrasound following catheterization. The UVC was immediately removed and replaced with a peripherally inserted central catheter. The infant’s physical examination was unremarkable. Bedside X‐ray revealed neither PVG nor pneumatosis intestinalis, which would indicate the onset of necrotizing enterocolitis. After full evaluation, breastfeeding was started on the same day. The infant did not develop feeding intolerance, necrotizing enterocolitis, or other disorders.

Conclusion

PVG occasionally occurs in neonates who undergo UVC and is considered to be caused by exogenous gases. PVG is more easily detected with ultrasound than with X‐ray and does not affect early feeding in premature infants.
Self‐talk in middle childhood: A mechanism for motivational resilience during learning
Authors: Flanagan Róisín M. , Symonds Jennifer E.
Published: January 2021

All individuals possess an inner voice that helps them to navigate life and its challenges. However, little is known about how children use self‐talk to maintain their momentary engagement during academic tasks. Using qualitative methods, this study investigated how 19 children (aged 8–12 years) from one primary school prospectively used self‐talk to maintain their motivation. Vignettes were used to prompt children's reports on what they would say to themselves to stay motivated during challenges they might typically encounter in the classroom. These included becoming frustrated or tired, and having to choose between work and play. The data were deductively coded into 11 coping families typically measured in academic settings within the framework of motivational resilience. The data were then inductively coded within the best represented coping families to uncover subthemes of coping. The results extend the motivational resilience literature and illustrate the multidimensional nature of coping with challenges in classrooms.
Developmental plasticity of Brachypodium distachyon in response to P deficiency: Modulation by inoculation with phosphate‐solubilizing bacteria
Authors: Baudson Caroline , Delory Benjamin M. , Spaepen Stijn , du Jardin Patrick , Delaplace Pierre
Published: January 2021

Background

Mineral phosphorus (P) fertilizers must be used wisely in order to preserve rock phosphate, a limited and non‐renewable resource. The use of bio‐inoculants to improve soil nutrient availability and trigger an efficient plant response to nutrient deficiency is one potential strategy in the attempt to decrease P inputs in agriculture.

Method

An in vitro co‐cultivation system was used to study the response of Brachypodium distachyon to contrasted P supplies (soluble and poorly soluble forms of P) and inoculation with P solubilizing bacteria. Brachypodium's responses to P conditions and inoculation with bacteria were studied in terms of developmental plasticity and P use efficiency.

Results

Brachypodium showed plasticity in its biomass allocation pattern in response to variable P conditions, specifically by prioritizing root development over shoot productivity under poorly soluble P conditions. Despite the ability of the bacteria to solubilize P, shoot productivity was depressed in plants inoculated with bacteria, although the root system development was maintained. The negative impact of bacteria on biomass production in Brachypodium might be attributed to inadequate C supply to bacteria, an increased competition for P between both organisms under P‐limiting conditions, or an accumulation of toxic bacterial metabolites in our cultivation system. Both P and inoculation treatments impacted root system morphology. The modulation of Brachypodium's developmental response to P supplies by P solubilizing bacteria did not lead to improved P use efficiency.

Conclusion

Our results support the hypothesis that plastic responses of Brachypodium cultivated under P‐limited conditions are modulated by P solubilizing bacteria. The considered experimental context impacts plant–bacteria interactions. Choosing experimental conditions as close as possible to real ones is important in the selection of P solubilizing bacteria. Both persistent homology and allometric analyses proved to be useful tools that should be considered when studying the impact of bio‐inoculants on plant development in response to varying nutritional context.
The Differential Effect of First‐Time Single‐Point Cane Use between Healthy Young and Older Adults
Authors: Omana Humberto , Madou Edward , Divine Alison , Wittich Walter , Hill Keith D. , Johnson Andrew M. , Holmes Jeffrey D. , Hunter Susan W.
Published: January 2021

Background

Walking aids are often introduced to older adults to enable independent mobility. Single‐point canes are the most common device used. Benefits are tempered by research suggesting that walking aids increase fall risk. A better understanding of the effect of walking aid use on gait performance is required.

Objective

To evaluate differences in the effect of initial single‐point cane use on gait between younger (YAs) and older adults (OAs).

Design

Cross‐sectional.

Setting

Community‐dwelling.

Participants

Twenty‐six YAs (mean age ± standard deviation [SD]: 23.7 ± 2.8 years) and 25 OAs (mean age ± SD: 70.8 ± 14.1 years) participated. Inclusion criteria were 18 to 35 years of age for YAs or ≥50 years for OAs, be able to ambulate unassisted, and without any condition affecting mobility.

Interventions

Not applicable.

Main Outcome Measure(s)

Gait velocity and stride time variability under different walking path configurations (straight path, Groningen Meander Walking Test, Figure‐of‐8 Walk Test) and conditions (unassisted walking, walking with a single‐point cane, and walking with a single‐point cane while completing a cognitive task) were recorded in a laboratory. The arithmetic task of subtracting 1s from 100 was used as the secondary cognitive task. Data analysis included separate three‐way mixed analyses of variance (ANOVAs; path/condition/group).

Results

There was a statistically significant two‐way interaction between walking path and condition for velocity (P < .001, ω2 = 0.03) and stride time variability (P = .032, ω2 = 0.02). In addition, a significant main effect of group was also observed (velocity: P = .004, ω2 = 0.07; stride time variability: P = .001, ω2 = 0.09).

Conclusions

Using a single‐point cane decreased velocity and increased stride time variability in both YAs and OAs. However, the cognitive load and effect on gait of initial cane use was not different between age groups. Standardized guidelines aimed at facilitating a clientʼs transition toward the safe use of a walking aid are needed. Future research should evaluate if training can mitigate some of the adverse changes to gait stability observed with initial walking aid use.
Betanidin isomerisation and decarboxylation, thermodynamic and charge transfer dye properties towards dye sensitised solar cells application
Authors: Costa Rene , Pogrebnoi Alexander , Pogrebnaya Tatiana
Published: January 2021

Along with attractiveness of natural dyes for solar technologies, the instability is a well‐known drawback of the dyes, which impedes their usage for dye sensitised solar cells (DSSCs) application. The planar isomer appeared to be predominant in equilibrium vapour despite its less energetic stability. Both betanidins belong to red–purple pigments betacyanins, which experimentally demonstrated good adsorption in a visible range. In this study, the structural, thermodynamic, and optoelectronic properties of betanidins have been determined from density functional theory (DFT) and time‐dependent DFT (TD–DFT) computations. On the basis of the thermodynamic approach, isomerisation reaction between two structural conformers of betanidin, bent and planar, and also decarboxylation reactions have been analysed. The planar isomer appeared to be predominant in equilibrium vapour despite its less energetic stability; both betanidin molecules exhibit an inclination to decay into decarboxylated betanidin and CO2. As for worthy optoelectronic properties and applicability in DSSCs, the dyes considered satisfy most requirements to sensitise the semiconductor TiO2 and be regenerated by electrolytes. Adsorption of the dyes at the TiO2 surface has been simulated; for the dye@TiO2 complexes, the binding energies, electronic spectra, and relevant molecular orbital (MO) isosurfaces have been computed and discussed.
Methanol synthesis from CO2 using Ni and Cu supported Fe catalytic system: Understanding the role of nonthermal plasma surface discharge
Authors: Joshi Nitesh , Loganathan Sivachandiran
Published: January 2021

The present study combines nonthermal plasma (NTP) and thermal catalysis to exploit the synergism for direct conversion of CO2 to CH3OH using H2. Series of catalyst, that is, CuO/QW, NiO/QW, Fe2O3/QW, NiO/Fe2O3/QW, CuO/Fe2O3/QW have been tested for CO2 conversion and CH3OH selectivity. And it was observed that 5 wt% CuO/Fe2O3/QW exhibited better CO2 conversion and CH3OH selectivity as compared to other catalysts. With 5 wt% CuO/Fe2O3/QW, at 200°C and 2‐W NTP input power (100 ml/min feed flow and 1:3 ratio of CO2 and H2) about 16.7% CO2 conversion and 32.7% CH3OH selectivity have been reached. Indeed, the highest of 9.32 mmol h−1 gcat−1 of CH3OH space‐time yield is obtained over CuO/Fe2O3/QW, which is about two times higher than the reported value in the literature (4.41 mmol h−1 gcat−1 of CH3OH using Cu/ZnO/Al2O3, 30°C, feed flow 40 ml/min, and 30‐W input power).
Discrete‐time systems with slope restricted nonlinearities: Zames–Falb multiplier analysis using external positivity
Authors: Turner Matthew C. , Drummond Ross
Published: January 2021

This article exploits positive systems theory in the search for Zames–Falb multipliers for the analysis of discrete‐time Lurie systems, where the nonlinearity is assumed to be slope‐restricted. Although a similar problem has been tackled in a continuous time context, the results in discrete‐time take a different form and require a somewhat different approach to overcome certain technical problems. The work has two compelling features: (i) the arising algorithms are completely convex; and (ii) numerical results compare well with the state‐of‐the‐art in some cases, providing the least conservative result in one instance.
CuAAC Mediated Synthesis of 2‐HBT Linked Bioactive 1,2,3‐Triazole Hybrids: Investigations through Fluorescence, DNA Binding, Molecular Docking, ADME Predictions and DFT Study
Authors: Nehra Nidhi , Kumar Tittal Ram , Ghule Vikas D. , Kumar Nikhil , Kumar Paul Avijit , Lal Kashmiri , Kumar Ashwini
Published: January 2021

A series of three different classes of benzothiazole linked 1,2,3‐triazole hybrid molecules with varying alkyl spacers (ethyl, propyl, and butyl) between 2‐hydroxyphenyl benzothiazoles and 1,2,3‐triazoles are efficiently synthesized under CuAAC condition. All compounds are satisfactorily characterized by FTIR, 1H‐NMR, 13C‐NMR, ESI‐MS data and structures of some compounds were finally supported by single‐crystal X‐ray diffraction data. Most of the synthesized compounds exhibited good to better DNA binding property (0.28×105 M−1 to 2.91×105 M−1) and well drug‐like properties. Some promising compounds showed good agreement to all experimental and theoretical computed properties (fluorescence study, DNA binding, molecular docking, DFT, and ADME Predictions).
Design, Synthesis, Evaluation and Molecular Docking Studies of Novel Triazole Linked 1,4‐Dihydropyridine‐isatin Scaffolds as Potent Anticancer Agents
Authors: Deswal Nidhi , Shrivastava Ankita , Summon Hossain Md. , Gahlyan Parveen , Bawa Rashim , Gupta Rinkoo Devi , Kumar Rakesh
Published: January 2021

A series of novel triazole linked isatin‐dihydropyridine hybrids (N1‐N15) have been synthesized and examined for their anti proliferative activity against human cancer cell lines viz. HeLa, Huh‐7, PC‐3, IMR‐32 and MCF‐7. All of the synthesized hybrids have shown moderate to potent cytotoxicity against all the tested cell lines except IMR‐32. Compounds N1, N2 and N13 have displayed an enhanced inhibitory potency against Huh‐7 cell line as compared to the standard drug, doxorubicin. Out of the three, N2 has shown the highest in vitro inhibitory action with IC50 values of 6.73±0.33 μM and 17.94±0.23 μM against Huh‐7 and MCF‐7 cell lines, respectively. The docking studies of these most potent compounds have also been investigated which identified that N2 might be an excellent drug‐like candidate worthy of further pursuit.
Highly Efficient Electrocatalyst for Oxygen Evolution Reaction: DFT Investigation on Transition Metal‐Tetracyanoquinodimethane Monolayer
Authors: Mukherjee Biswanath
Published: January 2021

To search for efficient electrocatalyst towards oxygen evolution reaction (OER) for sustainable energy production, a family of transition metal‐tetracyanoquinodimethane (TM‐TCNQ) (TM=Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd)monolayers have been studied by first principle based density functional theory (DFT) computations. The systematic investigations on various TM‐TCNQ structures revealed that Ni‐TCNQ monolayer exhibits best catalytic activity towards OER. At equilibrium potential (1.23 Vvs RHE), the free energy profile of Ni‐TCNQ monolayer for different reaction intermediates is not completely downhill which points out that water could not be oxidized by the photo‐generated holes at that potential. However, at and above 1.71 V, all the OER reaction steps on Ni‐TCNQ surface is found to be thermodynamically downhill, measuring a low onset overpotential, ca. 0.48 V in acidic media (pH=0). The estimated overpotential for other TM‐TCNQ structures are comparatively higher to promote energy‐efficient OER activity. The excellent performance of Ni‐TCNQ monolayer as OER catalyst were explained in terms of volcano plot, scaling diagram, d‐ band centre model, band structure and charge analysis.
Oxidative C(SP2)‐P Formation: Direct Construction of C‐P Bond on Quinoxalines via Aromatic Phosphorous Oxide
Authors: Xiong Yunkui , Zhang Jianye , Qi Liping , Zhang Yu , Wang Tao
Published: January 2021

Oxidative coupling has been widely used in the construction of C−C, C−N and C−S bond. Nevertheless, the method of oxidative coupling is rarely used to construct C−P bond and has not attracted enough attention. Herein, we found an innovative and simple method to construct C−P bond by oxidative coupling. Through the method, we successfully constructed the C−P bond on quinoxaline, and using this method, a series of quinoxaline derivatives were synthesized in good to excellent yield. Furthermore, the method is also suitable for large‐scale production and may be used to industrial application
Electrochemical Reduction and Oxidation of the Antibiotic Cefoxitin‐Cu2+ Complex and its Analytical Applications
Authors: Alhagri Ibrahim A. , Temerk Yassien M. , Al‐Hazmy Sadeq M. , Alhemiary Nabil A. , Alhakimi Ahmed N. , Hassan Mohammed
Published: January 2021

The interaction of cefoxitin, being a compound of interest for antibiotic research, with Cu2+ resulted in the formation of a 1 : 1 complex. The electrochemical reduction at a hanging mercury drop electrode and oxidation at a renewable pencil graphite electrode of the formed cefoxitin‐Cu2+ complex was investigated using cyclic voltammetry and differential pulse voltammetry in Britton‐Robinson buffers (pH 2–9). For the electrochemical reduction or oxidation of the examined complex, a new well‐defined voltammetric peak was obtained and the features of the surface redox and oxidation peaks were studied. Calculations of the values of stability constant and the change on Gibbs free energy for cefoxitin‐Cu2+ complex suggest that the complexation is a spontaneous process. The sharp peak of the electroreduction and oxidation of the investigated complex associated with an effective interfacial accumulation of this complex facilitates the determination of the antibacterial drug cefoxitin in the bulk and blood serum samples. Cefoxitin was determined by electrochemical reduction and oxidation of the cefoxitin‐Cu2+ complex, with detection limits of 6.94×10−9M and 9.07×10−8M respectively.
Ladybug Inspired Double‐Layered Adhesive with Enhanced Robustness of Surface Roughness
Authors: Yang Xiaochen , Zhong Hongmei , Zhang Peng , Wang Tao , Zhang Yiyuan , Gu Ping , Zhao Yang
Published: January 2021

Surface flexibility and structure stability are two design considerations and opposing sides for biologically‐inspired dry adhesives in real world. Here a ladybug inspired adhesive with double‐layered structure is presented to solve this problem. The bottom layer is made of magnetorheological elastomers (MREs) and the top layer is made of polydimethylsiloxane (PDMS) with controllable Young's modulus and thickness. To investigate the adaptability of the double‐layered adhesives to surface roughness, silicon wafers are polished to achieve various surface roughness. The adhesion performance of composite structure is characterized by using a mechanical testing machine with the target Si surfaces. The experiment results indicate double‐layered adhesive shows good surface adaptation and robustness to different surface roughness with approximately 3 N/cm2 adhesion stress. This work shows the adhesion performance of double‐layered dry adhesive considering the real world surface and illustrates that the mechanical properties of the biomimetic adhesives have a significant impact on their adhesion performance.