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Concurrent multiscale structural optimization is concerned with the improvement of macroscale structural performance through the design of microscale architectures. The multiscale design space must consider variables at both scales, so design restrictions are often necessary for feasible optimization. This work targets such design restrictions, aiming to increase microstructure complexity through deep learning models. The deep neural network (DNN) is implemented as a model for both microscale structural properties and material shape derivatives (shape sensitivity). The DNN’s profound advantage is its capacity to distill complex, multidimensional functions into explicit, efficient, and differentiable models. When compared to traditional methods for parameterized optimization, the DNN achieves sufficient accuracy and stability in a structural optimization framework. Through comparison with interface-aware finite element methods, it is shown that sufficiently accurate DNNs converge to produce a stable approximation of shape sensitivity through back propagation. A variety of optimization problems are considered to directly compare the DNN-based microscale design with that of the Interface-enriched Generalized Finite Element Method (IGFEM). Using these developments, DNNs are trained to learn numerical homogenization of microstructures in two and three dimensions with up to 30 geometric parameters. The accelerated performance of the DNN affords an increased design complexity that is used to design bio-inspired microarchitectures in 3D structural optimization. With numerous benchmark design examples, the presented framework is shown to be an effective surrogate for numerical homogenization in structural optimization, addressing the gap between pure material design and structural optimization. [ABSTRACT FROM AUTHOR]

Dentin microstructure undergoes changes with age and its materials properties degrade over time. In the present study, we investigate the coupled influence of increased filled tubules and decreased materials properties on the fracture behavior of human dentin. We assume degraded materials properties are linked with increased advanced glycation end-products (AGEs) crosslinks in dentin tissue. We use morphological data of human molars to create 2D and 3D models of dentin microstructure, and utilize a phase field fracture framework to study crack growth trajectories. We construct aged dentin samples (i.e. , filled tubules and degraded properties) and compare the fracture results with the samples without age-related changes. The simulations show an increase in the number of filled tubules can deactivate the toughening mechanisms such as crack deflection and microcracking. In addition, filled tubules have adverse impacts on the ability of peritubular dentin to shield microcracking. We further show how the dentinal tubules' orientations affect the crack surface growth. We also investigate that an increase in the AGEs level can result in increased brittleness. The developed model and findings of the present study provide region-dependent information on crack growth trajectories as well as more understanding of crack surface growth at the presence of filled tubules. • Straight cracks form in the inner dentin by an increase in filled tubules with age. • Filled tubules deteriorate the role of peritubular dentin in shielding microcracks. • Materials degradation and filled tubules adversely affect toughening mechanisms. • Various toughening mechanisms are shown by 2D and 3D phase field fracture models. • Crack growth trajectories in the inner and outer dentin are discussed. [ABSTRACT FROM AUTHOR]

Microglia, the brain's resident myeloid cells, play central roles in brain defense, homeostasis, and disease. Using a prolonged colony-stimulating factor 1 receptor inhibitor (CSF1Ri) approach, we report an unprecedented level of microglial depletion and establish a model system that achieves an empty microglial niche in the adult brain. We identify a myeloid cell that migrates from the subventricular zone and associated white matter areas. Following CSF1Ri, these amoeboid cells migrate radially and tangentially in a dynamic wave filling the brain in a distinct pattern, to replace the microglial-depleted brain. These repopulating cells are enriched in disease-associated microglia genes and exhibit similar phenotypic and transcriptional profiles to white-matter-associated microglia. Our findings shed light on the overlapping and distinct functional complexity and diversity of myeloid cells of the CNS and provide new insight into repopulating microglia function and dynamics in the mouse brain. [ABSTRACT FROM AUTHOR]

The motivation of this study is to evaluate the American put option on zero-coupon bond, when the interest rate model is governed by a fractional CIR (FCIR) interest rate model. Since the existence of fractional Brownian motion, leading to create the arbitrage, we employ the transaction cost for eliminating the arbitrage. We first of all apply the Leland's hedging strategy for a self-financing portfolio that contains an American option and zero-coupon bond and derive a formula for the transaction cost. We perform the least-square Monte Carlo (LSM) method for pricing American option under the proposed interest rate model. [ABSTRACT FROM AUTHOR]

Immobilised molybdenum thiosemicarbazide Schiff base complex on the surface of magnetite nanoparticles (MoO2—thio-SCMNPs) was used as a heterogeneous nanocatalyst for the oxidation of various benzylic alcohols to their corresponding carbonyl compounds in DMF and acetonitrile by H2O2 at 60°C. The progress of reaction was monitored by TLC and the products was characterised by GC. This new oxidising system has advantages over similar oxidant systems in terms of the mild and green reaction conditions, selectivity, simple work-up, and high yield. [ABSTRACT FROM AUTHOR]

Recent advances in manufacturing based on sacrificial fiber or template techniques have allowed complex networks of microchannels to be embedded in microvascular composites. In the thermal application of interest, a novel battery packaging scheme for electric vehicles is considered where each battery is surrounded by microvascular composite panels for temperature regulation and structural protection. We use simplified thermal and hydraulics models validated against more complex 3D FLUENT simulations and experiments to obtain the surface temperature distribution of the panel and the pressure drops across the microchannels. We further eliminate the cost and complexity associated with mesh generation by applying the interface-enriched generalized finite element method (IGFEM), which allows a non-conforming mesh to capture the discontinuous temperature gradient across the microchannels. The IGFEM thermal solver is then combined with a gradient-based shape optimization scheme to obtain optimal designs of a set of branched microchannel networks. The design parameters are the channel control points, which define the shape of the network. We use the p -mean as a differentiable objective function in place of the maximum temperature. To obtain accurate gradients with respect to the design parameters efficiently, we perform a sensitivity analysis based on a recently developed adjoint method for IGFEM. Starting from many distinct configurations, we obtain the optimal designs for a wide range of network topologies. We also investigate the effect of the coolant flow rate on the optimal design. [ABSTRACT FROM AUTHOR]

A 3D NURBS-based interface-enriched generalized finite element method (NIGFEM) is introduced to solve problems with complex discontinuous gradient fields observed in the analysis of heterogeneous materials. The method utilizes simple structured meshes of hexahedral elements that do not necessarily conform to the material interfaces in heterogeneous materials. By avoiding the creation of conforming meshes used in conventional FEM, the NIGFEM leads to significant simplification of the mesh generation process. To achieve an accurate solution in elements that are crossed by material interfaces, the NIGFEM utilizes Non-Uniform Rational B-Splines (NURBS) to enrich the solution field locally. The accuracy and convergence of the NIGFEM are tested by solving a benchmark problem. We observe that the NIGFEM preserves an optimal rate of convergence, and provides additional advantages including the accurate capture of the solution fields in the vicinity of material interfaces and the built-in capability for hierarchical mesh refinement. Finally, the use of the NIGFEM in the computational analysis of heterogeneous materials is discussed. [ABSTRACT FROM AUTHOR]

A gradient-based shape optimization scheme using an Interface-enriched Generalized Finite Element Method (IGFEM) is presented wherein the design geometry is projected onto a fixed mesh and the IGFEM is used for analysis. This approach eliminates the mesh distortion present in conventional Lagrangian shape optimization methods, as well as the need for remeshing. An analytical sensitivity analysis using both the adjoint or direct approaches is presented to compute derivatives of the objective and constraint functions. Due to the fixed nature of the mesh, the so-called design velocity field only needs to be computed on the structure boundary/interface. A comparison between IGFEM- and conventional FEM-based shape optimization schemes is presented, showing an improved precision for the IGFEM approach. Finally, we solve various numerical examples to demonstrate the capability of the method including the computational design of particulate and microvascular composites. [ABSTRACT FROM AUTHOR]

Background: Microglia are dependent upon colony-stimulating factor 1 receptor (CSF1R) signaling for their survival in the adult brain, with administration of the dual CSF1R/c-kit inhibitor PLX3397 leading to the near-complete elimination of all microglia brainwide. Here, we determined the dose-dependent effects of a specific CSF1R inhibitor (PLX5622) on microglia in both wild-type and the 3xTg-AD mouse model of Alzheimer's disease. Methods: Wild-type mice were treated with PLX5622 for up to 21 days, and the effects on microglial numbers were assessed. 3xTg-AD mice were treated with PLX5622 for 6 or 12 weeks and effects on microglial numbers and pathology subsequently assessed. Results: High doses of CSF1R inhibitor eliminate most microglia from the brain, but a 75 % lower-dose results in sustained elimination of ~30 % of microglia in both wild-type and 3xTg-AD mice. No behavioral or cognitive deficits were found in mice either depleted of microglia or treated with lower CSF1R inhibitor concentrations. Aged 3xTg-AD mice treated for 6 or 12 weeks with lower levels of PLX5622 resulted in improved learning and memory. Aβ levels and plaque loads were not altered, but microglia in treated mice no longer associated with plaques, revealing a role for the CSF1R in the microglial reaction to plaques, as well as in mediating cognitive deficits. Conclusions: We find that inhibition of CSF1R alone is sufficient to eliminate microglia and that sustained microglial elimination is concentration-dependent. Inhibition of the CSF1R at lower levels in 3xTg-AD mice prevents microglial association with plaques and improves cognition. [ABSTRACT FROM AUTHOR]

Summary: The colony-stimulating factor 1 receptor (CSF1R) is a key regulator of myeloid lineage cells. Genetic loss of the CSF1R blocks the normal population of resident microglia in the brain that originates from the yolk sac during early development. However, the role of CSF1R signaling in microglial homeostasis in the adult brain is largely unknown. To this end, we tested the effects of selective CSF1R inhibitors on microglia in adult mice. Surprisingly, extensive treatment results in elimination of ∼99% of all microglia brain-wide, showing that microglia in the adult brain are physiologically dependent upon CSF1R signaling. Mice depleted of microglia show no behavioral or cognitive abnormalities, revealing that microglia are not necessary for these tasks. Finally, we discovered that the microglia-depleted brain completely repopulates with new microglia within 1 week of inhibitor cessation. Microglial repopulation throughout the CNS occurs through proliferation of nestin-positive cells that then differentiate into microglia. [Copyright &y& Elsevier]

Abstract: The computational design of an actively-cooled 3D woven microvascular composite plate with sinusoidal and straight microchannels is presented. The design objectives include minimizing the maximum temperature of the composite, the microchannel volume fraction, and the pressure drop needed to circulate the coolant in the microchannels. We study the impact of a variety of parameters on the optimal design of a microvascular composite plate subjected to a uniform heat flux over its bottom surface. These parameters include the spacing, wavelength, and amplitude of the microchannels, the coolant type and flow rate, and the applied thermal loads. To facilitate the computational design process, a mesh-independent Interface-enriched Generalized Finite Element Method (IGFEM) is employed to evaluate the temperature field in the actively-cooled composite. The IGFEM solver also includes the streamline upwind Petrov-Galekin stabilization scheme to eliminate the spurious oscillations in the temperature field due to the convection-dominated heat transfer in the microchannels. This study reveals that the straight microchannels are often the optimal configuration. Design maps are presented to evaluate the required flow rate as a function of the applied thermal load and the plate dimensions. [Copyright &y& Elsevier]

Improvement in power system reliability is considered today to be one of the main system planning needs. Meanwhile, there is a growing tendency toward reliability studies considering renewable energies. In this article, for reliability assessment of a power system including wind power, an analytical method based on the frequency and duration approach is utilized to model a wind farm as a multi-state conventional unit. A suitable time-series model—the auto-regressive moving average—is employed in this study to predict wind speeds. The equivalent unit approach is modeled, representing the benefits of interconnection between the two systems in terms of an equivalent multi-state unit. This model includes the constraints and parameters of the tie-lines interconnecting the two systems. Results confirm that the adequacy of the generating capacity in a power system is normally improved by interconnecting the system to another power system. To do so, the wind farm is considered as an assisting system for a test system, and reliability indices of the total system are then calculated. [ABSTRACT FROM PUBLISHER]

Controlled splitting of an interconnected power system is the last defense line against wide-area blackout. As a special protection scheme, the methodology of system splitting is a comprehensive decision-making problem. This article introduces a novel approach for separation of the integrated power systems into several stable islands. The proposed method combines both the dynamic and static characteristics of interconnected power networks and determines the proper splitting schemes. The presented algorithm searches for proper islanding strategies using the Krylov projection method and a new optimization algorithm to find the proper splitting points such that the total load shedding is minimized. The method reduces the huge initial search space of islanding strategies by considering dynamic characteristics of integrated power systems. A spanning-tree-based Prim algorithm is used to find all possible combination of the islands. The speed of the proposed algorithm is remarkably high, and it can be used for real-time splitting of the power systems. The algorithm is applied to an IEEE 118-bus test system. Results show the effectiveness and capability of the method for determining fast and accurate proper islanding strategies. The stability of the islands is verified by time domain simulation. [ABSTRACT FROM AUTHOR]

Background: Microglia, the primary resident myeloid cells of the brain, play critical roles in immune defense by maintaining tissue homeostasis and responding to injury or disease. However, microglial activation and dysfunction has been implicated in a number of central nervous system (CNS) disorders, thus developing tools to manipulate and replace these myeloid cells in the CNS is of therapeutic interest.Methods: Using whole body irradiation, bone marrow transplant, and colony-stimulating factor 1 receptor inhibition, we achieve long-term and brain-wide (~ 80%) engraftment and colonization of peripheral bone marrow-derived myeloid cells (i.e., monocytes) in the brain parenchyma and evaluated the long-term effects of their colonization in the CNS.Results: Here, we identify a monocyte signature that includes an upregulation in Ccr1, Ms4a6b, Ms4a6c, Ms4a7, Apobec1, Lyz2, Mrc1, Tmem221, Tlr8, Lilrb4a, Msr1, Nnt, and Wdfy1 and a downregulation of Siglech, Slc2a5, and Ccl21a/b. We demonstrate that irradiation and long-term (~ 6 months) engraftment of the CNS by monocytes induces brain region-dependent alterations in transcription profiles, astrocytes, neuronal structures, including synaptic components, and cognition. Although our results show that microglial replacement with peripherally derived myeloid cells is feasible and that irradiation-induced changes can be reversed by the replacement of microglia with monocytes in the hippocampus, we also observe that brain-wide engraftment of peripheral myeloid cells (relying on irradiation) can result in cognitive and synaptic deficits.Conclusions: These findings provide insight into better understanding the role and complexity of myeloid cells in the brain, including their regulation of other CNS cells and functional outcomes. [ABSTRACT FROM AUTHOR]

The shape of the talus, its internal structure, and its mechanical properties are important in determining talar behavior during loading, which may be significant for the design of surgical tools and implants. Although recent studies using statistical shape modeling have described quantitative talar external shape variation, no similar quantitative study exists to describe the density distribution of internal talar structure. The goal of this study is to quantify statistical variation in talar shape and density to benefit the design of talar implants. To this end, weight‐bearing computed tomography (CT) scans of the ankle were collected in neutral, bilateral standing posture, and three‐dimensional models were generated for each talus. Local density derived from the Hounsfield unit of each CT voxel was extracted. A weighted spherical harmonic analysis was performed to quantify the talar external shape. One hundred and seventy‐nine volumes of interest were placed in the same relative position within each talus to quantify the talar density. Additionally, a finite element analysis (FEA) was conducted on a talus with both heterogeneous and homogeneous material properties to observe the effect of these properties on the stress and strain response. Significant differences were found in the talar density in sex and age, as well as in the stress and strain response between homogeneous and heterogeneous FEA. These differences show the importance of considering heterogeneity when examining the load response of tarsal bones. [ABSTRACT FROM AUTHOR]

Fixation with suture anchors and metallic hardware for osteosynthesis is common in orthopedic surgeries. Most metallic commercial bone anchors achieve their fixation to bone through shear of the bone located between the threads. They have several deficiencies, including stress‐shielding due to mechanical properties mismatch, generation of acidic by‐products, poor osteointegration, low mechanical strength and catastrophic failure often associated with large bone defects that may be difficult to repair. To overcome these deficiencies, a swelling porous copolymeric material, to be used as bone anchors with osteointegration potential, was introduced. The purpose of this study was to investigate the fixation strength of these porous, swelling copolymeric bone anchors in artificial bone of various densities. The pull‐out and subsidence studies indicate an effective fixation mechanism based on friction including re‐fixation capabilities, and minimization of damage following complete failure. The study suggests that this swelling porous structure may provide an effective alternative to conventional bone anchors, particularly in low‐density bone. [ABSTRACT FROM AUTHOR]

Microvascular materials containing internal microchannels are able to achieve multi-functionality by flowing different fluids through vasculature. Active cooling is one application to protect structural components and devices from thermal overload, which is critical to modern technology including electric vehicle battery packaging and solar panels on space probes. Creating thermally efficient vascular network designs requires state-of-the-art computational tools. Prior optimization schemes have only considered steady-state cooling, rendering a knowledge gap for time-varying heat transfer behavior. In this study, a transient topology optimization framework is presented to maximize the active-cooling performance and mitigate computational cost. Here, we optimize the channel layout so that coolant flowing within the vascular network can remove heat quickly and also provide a lower steady-state temperature. An objective function for this new transient formulation is proposed that minimizes the area beneath the average temperature versus time curve to simultaneously reduce the temperature and cooling time. The thermal response of the system is obtained through a transient Geometric Reduced Order Finite Element Model (GRO-FEM). The model is verified via a conjugate heat transfer simulation in commercial software and validated by an active-cooling experiment conducted on a 3D-printed microvascular metal. A transient sensitivity analysis is derived to provide the optimizer with analytical gradients of the objective function for further computational efficiency. Example problems are solved demonstrating the method’s ability to enhance cooling performance along with a comparison of transient versus steady-state optimization results. In this comparison, both the steady-state and transient frameworks delivered different designs with similar performance characteristics for the problems considered in this study. This latest computational framework provides a new thermal regulation toolbox for microvascular material designers. [ABSTRACT FROM AUTHOR]

Background: Microglia are dependent upon colony-stimulating factor 1 receptor (CSF1R) signaling for their survival in the adult brain, with administration of the dual CSF1R/c-kit inhibitor PLX3397 leading to the near-complete elimination of all microglia brainwide. Here, we determined the dose-dependent effects of a specific CSF1R inhibitor (PLX5622) on microglia in both wild-type and the 3xTg-AD mouse model of Alzheimer's disease.Methods: Wild-type mice were treated with PLX5622 for up to 21 days, and the effects on microglial numbers were assessed. 3xTg-AD mice were treated with PLX5622 for 6 or 12 weeks and effects on microglial numbers and pathology subsequently assessed.Results: High doses of CSF1R inhibitor eliminate most microglia from the brain, but a 75% lower-dose results in sustained elimination of ~30 of microglia in both wild-type and 3xTg-AD mice. No behavioral or cognitive deficits were found in mice either depleted of microglia or treated with lower CSF1R inhibitor concentrations. Aged 3xTg-AD mice treated for 6 or 12 weeks with lower levels of PLX5622 resulted in improved learning and memory. Aβ levels and plaque loads were not altered, but microglia in treated mice no longer associated with plaques, revealing a role for the CSF1R in the microglial reaction to plaques, as well as in mediating cognitive deficits.Conclusions: We find that inhibition of CSF1R alone is sufficient to eliminate microglia and that sustained microglial elimination is concentration-dependent. Inhibition of the CSF1R at lower levels in 3xTg-AD mice prevents microglial association with plaques and improves cognition. [ABSTRACT FROM AUTHOR]

Electric vehicle (EV) batteries require both thermal regulation and crash protection. A novel battery packaging scheme is presented that uses microvascular composite panels with 2D channel networks to accomplish both objectives. Microvascular carbon fiber/epoxy composite panels are fabricated by vacuum assisted resin transfer molding, with the channel network formed by post-cure vaporization of an embedded polylactide channel template. Panel cooling performance is evaluated for parallel, bifurcating, serpentine, and spiral channel designs at different coolant flow rates and channel diameter. The spiral design provides the best thermal performance, but requires high pumping pressure (>100 kPa) at the flow rates needed for adequate cooling (>30 mL min −1 ). The bifurcating design and a network obtained by computational optimization offer much lower pressure with slightly reduced thermal performance. Channel diameter has negligible effect on cooling performance, but strongly affects pumping pressure. Computational fluid dynamics (CFD) simulations are also performed and correlate well with the experimental data. Simulations confirm that microvascular composite panels can cool typical battery cells generating 500 W m −2 heat flux below the target temperature of 40 °C. [ABSTRACT FROM AUTHOR]

In addition to amyloid-β plaque and tau neurofibrillary tangle deposition, neuroinflammation is considered a key feature of Alzheimer's disease pathology. Inflammation in Alzheimer's disease is characterized by the presence of reactive astrocytes and activated microglia surrounding amyloid plaques, implicating their role in disease pathogenesis. Microglia in the healthy adult mouse depend on colony-stimulating factor 1 receptor (CSF1R) signalling for survival, and pharmacological inhibition of this receptor results in rapid elimination of nearly all of the microglia in the central nervous system. In this study, we set out to determine if chronically activated microglia in the Alzheimer's disease brain are also dependent on CSF1R signalling, and if so, how these cells contribute to disease pathogenesis. Ten-month-old 5xfAD mice were treated with a selective CSF1R inhibitor for 1 month, resulting in the elimination of ∼80% of microglia. Chronic microglial elimination does not alter amyloid-β levels or plaque load; however, it does rescue dendritic spine loss and prevent neuronal loss in 5xfAD mice, as well as reduce overall neuroinflammation. Importantly, behavioural testing revealed improvements in contextual memory. Collectively, these results demonstrate that microglia contribute to neuronal loss, as well as memory impairments in 5xfAD mice, but do not mediate or protect from amyloid pathology. [ABSTRACT FROM AUTHOR]

The classical phase field model using the second-order geometric function α (φ) = φ 2 (i.e., AT2 model), where φ ∈ 0 , 1 is an auxiliary phase field variable representing material damage state, has wide applications in static and dynamic scenarios for brittle materials, but nonlinearity and inelasticity are found in its stress–strain curve. The phase field model using the linear geometric function α (φ) = φ (i.e., AT1 model), can avoid this, and a linear elastic threshold is available in its stress–strain curve. However, both AT2 and AT1 models are length scale sensitive phase field models, which could have difficulty in adjusting fracture strength and crack band simultaneously through a single parameter (the length scale). In this paper, a generalized quadratic geometric function (linear combination of AT1 and AT2 models) is used in the phase field model, where the extra parameter in this geometric function makes it a length scale insensitive phase field model. Similar to the AT1 model, negative phases can happen in the proposed generalized quadratic geometric function model. To solve this problem, a bound-constrained optimization using the Lagrange multiplier is derived, and the Karush–Kuhn–Tucker (KKT) conditions change from strain energy and maximum history strain energy (an indirect method acting on phase) to phase and Lagrange multiplier (a direct method acting on phase). Several simulations successfully validated the proposed model. A single element analysis and a bar under cyclic loading show the different stress–strain curves obtained from different models. A simulation of Mode I Brazilian test is compared with the experiment conducted by the authors, and two more simulations of Mode II shear test and mixed mode PMMA tensile test are compared with results from the literature. • A bound-constrained optimization using the Lagrange multiplier is applied to enforce the irreversibility constraint of fracture propagation. • It is verified that the KKT conditions using Lagrange multiplier work better than the classical KKT conditions using strain energy. • Tangent stiffness matrix has been derived for the displacement-phase-Lagrange- multiplier-coupled problem. • An extra parameter in the generalized quadratic geometric function gives a length scale insensitive phase field fracture model. [ABSTRACT FROM AUTHOR]

Motivated by recent advances in manufacturing techniques for high-temperature microvascular composites, a NURBS-based interface-enriched generalized finite element method (IGFEM) is developed to solve a simplified thermal model of microchannels embedded in the materials. This method is capable of handling curved and branched microchannels. Solutions more accurate than those achieved with the conventional finite element method can be obtained with coarse meshes that do not conform to the geometry of the microchannels. Near-optimal asymptotic convergence rate is also achieved with this method even for highly curved microchannels. The capability of the numerical scheme is demonstrated by solving problems with complex microchannel configurations. [ABSTRACT FROM AUTHOR]

Developing advanced fracture tools can increase the understanding of crack growth trajectories in human cortical bone. The present study investigates fracture micromechanics of human cortical bone under compressive and tensile loadings utilizing a phase field method. We construct two-dimensional finite element models from cortical microstructure of a human tibia cross section. We apply compression on the cortical bone models to create compressive microcracks. Then, we simulate the fracture of these models under tension to discover influential parameters on microcracks formation and post-yielding behavior. The results show that cement lines are susceptible sites to damage nucleation under compression rather than tension. The findings of this study also indicate a higher accumulation of initial damage (induced by compression) can lead to a lower microscopic stiffness as well as a less resistant material to damage initiation under tension. The simulations further indicate that the post-yielding properties (e.g., toughness) can be dependent on different variables such as morphological information of the osteons, the initial accumulation of microcracks, and the total length of cement lines. [ABSTRACT FROM AUTHOR]

Nearly all‐natural and synthetic composites derive their characteristic attributes from a hierarchical makeup. Engineered metamaterials exhibit properties not existing in natural composites by precise patterning, often periodically on size scales smaller than the wavelength of the phenomenon they influence. Lightweight fiber‐reinforced polymer composites, comprising stiff/strong fibers embedded within a continuous matrix, offer a superior structural platform for micro‐architectured metamaterials. The emergence of microvascular fiber‐composites, originally conceived for bioinspired self‐healing via microchannels filled with functional fluids, provides a unique pathway for dynamic reconfigurable behavior. Demonstrated here is the new ability to modulate both electromagnetic and thermal responses within a single structural composite by fluid substitution within a serpentine vasculature. Liquid metal infiltration of varying density micro‐channels alters polarized radio‐frequency wave reflection, while water circulation through the same vasculature enables active‐cooling. This latest approach to control bulk property plurality by widespread vascularization exhibits minimal impact on structural performance. Detailed experimental/computational studies, presented in this paper, unravel the effects of micro‐vascular topology on macro‐mechanical behavior. The results, spanning multiple physics, provide a new benchmark for future design optimization and real‐world application of multifunctional and adaptive microvascular composite metamaterials. [ABSTRACT FROM AUTHOR]

In the present work, mortar beams reinforced with polymeric reinforcing elements are manufactured using Polylactic acid (PLA), inspired by crack propagation deflecting architectures found in nature such as Sinusoidal and Bouligand architectures. Mechanical flexural properties of mortar beams are studied and compared with that of reinforcing elements with an architecture parallel to the direction of tensile stress as well as non-reinforced mortar beams. Furthermore, the reinforcement configuration and ratio are designed using principles from mechanics of materials. A Digital Image Correlation (DIC) technique is used to obtain the load-deflection curves during flexural evaluation. Results show that changing the microarchitecture of the reinforcement can enhance the flexural performance of the beam. Additionally, interface properties between the mortar and the reinforcing element are studied using pull-out tests. Interface properties were enhanced by introducing architectural patterns on the surface of the reinforcement. Finally, using material properties of the mortar, reinforcement and the interface obtained from experiments, a numerical model is developed and calibrated. The outcome of this study helps explore the opportunities of using novel nature-inspired reinforcement to enhance the mechanical properties of cementitious composites. • Changing the micro-architecture of the reinforcement from parallel to a nature-inspired twisting pattern improved ductility. • Various reinforcement ratios were studied to find sufficient reinforcement based on material properties of each component. • The bond between 3D-printed elements and mortar was enhanced by introducing surface features to the polymeric element. • A critical embedment length was established for polymeric reinforcement based on its cross-sectional area and surface texture. • Numerical studies were able to simulate the overall experimental flexural behavior of the reinforced cementitious beams. [ABSTRACT FROM AUTHOR]

We present a computational framework for Hybrid Topology/Shape (HyTopS) optimization of actively-cooled microvascular composites under uncertainty. We developed a novel HyTopS optimization scheme for microvascular composites which can perform the topological change during the shape optimization process. This task has been done by introducing a new set of design parameters to add/remove microchannels and change the topology of the network. The profound advantage of the HyTopS method in contrast to a solely shape optimization approach is that the design space in HyTopS is not limited to the topology of the initial configuration. We integrate the HyTopS optimization method with the non-intrusive polynomial chaos expansion (PCE) approach to conduct a robust and reliable design. The non-intrusive nature of the proposed method allows for almost any source of uncertainty to be incorporated virtually in the design optimization process. The PCE representations of the response metrics enable the optimizer to efficiently and precisely approximate the statistical moments, failure probabilities, and their sensitivities with respect to the design variables. We solve several numerical examples to demonstrate the advantages of using the suggested optimization scheme over deterministic optimization method for microvascular composites. The results reveal that the optimized designs obtained from performing optimization process under uncertainty outperform the optimized configurations of the deterministic optimization approach in terms of reducing the sensitivity of the design performance to the various random variables. • HyTopS optimization scheme under uncertainty is developed for microvascular materials. • Fully analytic sensitivity analysis for the optimization framework is derived. • Uncertainty is quantified using non-intrusive PCE to conduct RBDO and RDO schemes. • Computational cost is hugely reduced by using IGFEM and simplified thermal model. [ABSTRACT FROM AUTHOR]

• BioFiber were developed using core-fiber, endospore-laden hydrogel, and protective shell. • Polyester and polyvinyl alcohol fibers were used as core-fiber, and alginate as bio-agent carrier. • Endospore Lysinibacillus sphaericus strain MB284 was used as self-healing agent. • A blend of polystyrene and polylactic acid was selected as protective shell layer. • BioFiber showed satisfactory results for further incorporation in quasi-brittle matrix. In this study, we developed nature-inspired multi-functional polymeric fibers (called BioFiber) to deliver bio-self-healing agents into cementitious materials. BioFibers were manufactured using a load-bearing core-fiber, a sheath of endospore-laden hydrogel, and an outer damage-responsive polymeric shell layer. The innovative BioFiber integrates three key functionalities into the quasi-brittle matrix: (i) autonomous bio-self-healing, (ii) crack growth control, and (iii) damage-responsiveness. The hydrogel sheath contained endospores, as bio-agents, to establish microbially-induced calcium carbonate precipitation (MICCP) as a self-healing end-product. The core-fibers provided crack growth control functionality into quasi-brittle engineering materials. Additionally, the outer shell coating integrated a robust damage-responsive self-healing activation strategy in concrete. A comprehensive parametric study was conducted to explore material options and the influential parameters for tailoring the processing-compositions-structure properties of the developed BioFiber. The findings of this study revealed that a concentration of 8 w/v sodium-alginate crosslinked with calcium acetate provided higher solution uptake capacity required for MICCP. As for the shell, the polymer blend of polystyrene and polylactic acid (1:1 wt%), with polymer/solvent ratio of 18 w/v-single layer coating, effectively protected BioFibers during simulated concrete casting process. Lastly, each BioFiber was able to produce 40–80 mg of calcium carbonate within the first 30 h of activation. [ABSTRACT FROM AUTHOR]

Recent studies have shown that melatonin can be secreted, in addition to other sources, by peripheral blood mononuclear cells (PBMCs). We investigated whether melatonin could also be secreted by cultured polymorphonuclear (PMNs) and whole blood (WB) cells under resting and stimulated conditions. In addition, influences of the intensity and color of light on the production of melatonin by these cells were estimated. Blood samples were collected from a healthy volunteer, and PBMCs and PMNs were isolated. The PBMC, PMN, and WB cultures were exposed for 8 h to light intensities of 0, 20, 50, 100, 300, and 500 lux and to white, red, blue, and green lights in the presence/absence of mitogens. Levels of melatonin in supernatants were detected by enzyme-linked immunosorbent assay (ELISA). In addition to PBMCs, PMNs and WB cells were found to also produce melatonin, and this production was increased due to mitogen activations. The most effective intensity of light, which suppresses melatonin secretion, was 100 lux. There were no significant differences between the influences of different monochromatic lights on the melatonin production by the examined blood cell cultures. Thus, PBMCs, PMNs, and WB cultures can produce melatonin, and mitogen activation causes a higher production of this hormone. Moreover, although white light suppressed melatonin secretion at 100 lux, there was no difference among various types of lights. [ABSTRACT FROM AUTHOR]

Microglia, the resident immune cell of the brain, can be eliminated via pharmacological inhibition of the colony‐stimulating factor 1 receptor (CSF1R). Withdrawal of CSF1R inhibition then stimulates microglial repopulation, effectively replacing the microglial compartment. In the aged brain, microglia take on a "primed" phenotype and studies indicate that this coincides with age‐related cognitive decline. Here, we investigated the effects of replacing the aged microglial compartment with new microglia using CSF1R inhibitor‐induced microglial repopulation. With 28 days of repopulation, replacement of resident microglia in aged mice (24 months) improved spatial memory and restored physical microglial tissue characteristics (cell densities and morphologies) to those found in young adult animals (4 months). However, inflammation‐related gene expression was not broadly altered with repopulation nor the response to immune challenges. Instead, microglial repopulation resulted in a reversal of age‐related changes in neuronal gene expression, including expression of genes associated with actin cytoskeleton remodeling and synaptogenesis. Age‐related changes in hippocampal neuronal complexity were reversed with both microglial elimination and repopulation, while microglial elimination increased both neurogenesis and dendritic spine densities. These changes were accompanied by a full rescue of age‐induced deficits in long‐term potentiation with microglial repopulation. Thus, several key aspects of the aged brain can be reversed by acute noninvasive replacement of microglia. [ABSTRACT FROM AUTHOR]

In this paper, a numerical analysis has been conducted to predict the fracture response of a novel type of fiber-reinforced concrete blocks, called "multi-functional fiber reinforced concretes" (MFRCs). In MFRCs, fibers have been coated with a shell. This will allow the structure to be used for multiple purposes, including concrete self-healing. This study is conducted utilizing phase-field fracture framework. The shell thickness and the ratio of fiber length to diameter are the geometrical parameters whose effects on the fracture resistance of the MFRCs have been analyzed. As choosing the right shell material is under investigation, in the next step of the study, in addition to the geometrical factors, different material mismatch cases for the critical energy release rate of the shell has been analyzed. Moreover, the application of two different fibers, polyester fiber and polypropylene fiber (with almost 10 times higher critical energy release rate), are looked into. All the structures undergo three loading conditions: tensile loading, compressive loading, and three-point bending. In order to judge what configuration performs best, the values of peak force and absorbed energy of each structure in each case study have been taken into consideration and compared with those of other structures. It was seen that the most favorable performance and configuration depend on the loading condition and also the material set. Under tension, MFRCs with the lowest fiber length to diameter ratio exhibit the highest peak force and absorbed energy in the case of polyester fiber. The same observation was made for all models and material sets under compressive loading. Under three-point bending loading condition, for the cases of polyester fiber, similar results were obtained as the lowest fiber length to diameter ratio showed the best mechanical response. Having said that, it must be mentioned that shell material had a dominant effect on the fracture response of the structure under this loading condition. Polypropylene fibers also managed to increase the peak forces in different loading conditions. • A novel multi-functional coated fiber-reinforced concrete (MFRC) is proposed. • Parametric study on fracture of MFRCs is conducted through phase-field framework. • For polyester fiber, lower lengths of fiber show higher toughness. • Polypropylene fiber increases peak forces while fail at lower displacement loads. • Less tough coating increases energy absorption under flexural loading. [ABSTRACT FROM AUTHOR]

Objective Headache Impact Test ( HIT-6) measures the impact headaches in a 1-month period. We validated the Persian translation of HIT-6, compared the HIT-6 psychometric analysis between migraine and tension-type headache ( TTH) patients, and evaluated the capability of HIT-6 to differentiate between TTH, chronic migraine, and episodic migraine. Methods Qualified participants, including 274 patients diagnosed with migraine or TTH, were required to complete HIT-6, SF-36v2, and a symptoms questionnaire on their first visit. At 3 and 8 weeks from first visit, participants completed HIT-6. Internal consistency (Cronbach's α) and test-retest reproducibility (Pearson's correlation coefficient) were used to assess reliability. Convergent validity was also assessed. Results Tension-type headache, episodic, and chronic migraines included 24.5%, 61.9%, and 13.6% of the participants, respectively. Internal consistency among all patients, TTH, and migraine in the first visit were 0.74, 0.77, and 0.73, respectively. Test-retest reliability for HIT-6 between visit 1 and 2 showed a moderate level of correlation ( r = 0.50). Convergent validity and also item total correlation were acceptable. There was no significant difference in HIT-6 total score between TTH and migraine. Conclusion Persian HIT-6 is a valid and reliable questionnaire for the evaluation of headache. However, it cannot differentiate between chronic migraine, episodic migraine, and TTH in Iranian population. [ABSTRACT FROM AUTHOR]

SUMMARY Higher penetration of distributed generation in distribution systems makes the islanding operation more realistic. In this paper, an adequacy assessment is presented in the presence of wind energy sources in distribution system for an islanded area. Wind speed simulation is performed using auto-regressive moving average time series. For adequacy assessment, well-being indices are introduced and calculated for an islanded area through an islanding algorithm. Then, sensitivity analysis is conducted to investigate the dependency of well-being indices on key parameters of analysis. Finally, the results are presented and discussed. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Bioinspired, electromagnetic modulation, fiber-composites, metamaterial, microvascular, multifunctional, thermal regulation A Microvascular-Based Multifunctional and Reconfigurable Metamaterial (Adv. Keywords: bioinspired; electromagnetic modulation; fiber-composites; metamaterial; microvascular; multifunctional; thermal regulation EN bioinspired electromagnetic modulation fiber-composites metamaterial microvascular multifunctional thermal regulation 1 1 1 11/09/21 20211101 NES 211101 B Microvascular-Based Metamaterial b In article number 2100433, Jason F. Patrick and coworkers demonstrate a microvascular-based multifunctional and reconfigurable metamaterial where various physical properties (i.e., electromagnetic signature and thermal profile) are dynamically modulated within a structural fiber-reinforced composite via fluid exchange (i.e., liquid metal and water) within a bioinspired vasculature. [Extracted from the article]

Diabetes is associated with increased fracture risk in human bone, especially in the elderly population. In the present study, we investigate how simulated advanced glycation end-products (AGEs) and materials heterogeneity affect crack growth trajectory in human cortical bone. We used a phase field fracture framework on 2D models of cortical microstructure created from human tibias to analyze crack propagation. The increased AGEs level results in a higher rate of crack formation. The simulations also indicate that the mismatch between the fracture properties (e.g., critical energy release rate) of osteons and interstitial tissue can alter the post-yielding behavior. The results show that if the critical energy release rate of cement lines is lower than that of osteons and the surrounding interstitial matrix, cracks can be arrested by cement lines. Additionally, activation of toughening mechanisms such as crack merging and branching depends on bone microstructural morphology (i.e., osteons geometrical parameters, canals, and lacunae porosities). In conclusion, the present findings suggest that materials heterogeneity of microstructural features and the crack-microstructure interactions can play important roles in bone fragility. [ABSTRACT FROM AUTHOR]

Background: The effects of chronic valproic acid administration on bone health have been a matter of concern and controversy. In this study, the bone status following valproate intake was assessed by using several bone-related biochemical markers. Materials and Methods: In this case-control study, 62 epileptic patients and 40 age- and gender-matched controls were enrolled. The patients had been under chronic valproate therapy (758 ± 29 mg/day) for at least the past 6 months, without any vitamin D/or calcium supplementation. Serum markers of bone turnover (carboxy-terminal telopeptide of type I collagen (CTX) and bone-specific alkaline phosphatase [BALP]), calcium, phosphorus, total alkaline phosphatase, and parathyroid hormone levels were measured in both groups. Results: The markers of bone turnover as well as other measured bone biochemical parameters did not statistically differ between the two groups. Conclusion: Valproate therapy at the mentioned doses does not seem to change bone turnover in adult epileptic patients. [ABSTRACT FROM AUTHOR]

• A HyTopS optimization scheme is presented for microvascular materials using IGFEM. • The analytical sensitivity for the HyTopS optimization scheme is derived. • The method is experimentally validated using a recent 3D-printing technique. • The computational cost is reduced by using IGFEM and simplified thermal model. Construction of bioinspired vasculature in synthetic materials enables multi-functional performance via mass transport through internal fluidic networks. However, exact reproduction of intricate, natural microvascular architectures is nearly impossible and thus there is a need to create practical, manufacturable designs guided by multi-physics principles. Here we present a Hybrid Topology/Shape (HyTopS) optimization scheme for microvascular materials using the Interface-enriched Generalized Finite Element Method (IGFEM). This new approach, which can simultaneously perform topological changes as well as shape optimization of microvascular materials, is demonstrated in the context of thermal regulation. In the current study, we present a new feature that enables the optimizer to augment network topology by creating/removing microchannels during the shape optimization process. This task has been accomplished by introducing a new set of design parameters, which act analogous to the penalization factor in the Solid Isotropic Material with Penalization (SIMP) method. The analytical sensitivity for the HyTopS optimization scheme has been derived and the sensitivity accuracy is verified against the finite difference method. We impose a set of geometrical constraints to account for manufacturing limitations and produce a design which is suitable for large-scale production without the need to perform post-processing on the obtained optimum. The method is validated by active-cooling experiments on vascularized carbon-fiber composites. Finally, we compare various application examples to demonstrate the advantages of the newly introduced HyTopS optimization scheme over solely shape optimization for microvascular materials. [ABSTRACT FROM AUTHOR]