Characterization of the Mechanical, Biodegradation, and Morphological Properties of NBR/Biopolymer Blend, Integrated with a Risk Evaluation.

Biopolymer blends have attracted considerable attention in industrial applications due to their notable mechanical properties and biodegradability. This work delves into the innovative combination of butadiene-acrylonitrile (referred to as NBR) with a pectin-based biopolymer (NGP) at a 90:10 mass ratio through a detailed analysis employing mechanical characterization, Fourier transform infrared (FTIR) analysis, thermogravimetric analysis (TGA), and morphology studies using SEM. Additionally, biopolymer's biodegradability under aerobic and anaerobic conditions is tested. The study's findings underscore the superior tensile strength and elongation at break of the NGP/NBR blend in comparison to pure NBR, while also exhibiting a decrease in puncture resistance due to imperfect bonds at the particle-matrix interfaces, necessitating the use of a compatibilizer. In anaerobic conditions, evaluation of biodegradable properties reveals 2% and 12% biodegradability in NBR and NGP/NBR blend, respectively. The degradation properties were also aligned with TGA results highlighting a lower decomposition temperature for NGP. Additionally, this research integrates the application of a conditional value-at-risk (CVaR)-based analysis of the blend's tensile properties to evaluate the uncertainty impact in the experiment. Under risk, a significant enhancement in the tensile performance (by 80%) of the NGP/NBR blend was shown compared to pure NBR. Ultimately, the study shows that adding pectin to the NBR compound amplifies the overall performance of the biopolymer significantly under select criteria.

A comprehensive simulation framework for predicting the eCLIPs implant crimping into a catheter and its deployment mechanisms.

Tubular flow diverters (FDs) represent an important subset of the endovascular treatment of cerebral aneurysms (CAs), acting to reduce aneurysm inflow, eventually resulting in aneurysm thrombosis and occlusion. eCLIPs (product of Evasc Neurovascular Enterprises, Vancouver, Canada), an innovative non-tubular implant causes flow diversion by bridging the neck of bifurcation CAs. However, in a small subset of challenging bifurcation aneurysms with fusiform pathology, the currently available eCLIPs models do not provide sufficient neck bridging resulting in a gap created between the device structure and the aneurysm/artery wall. To overcome this challenge, a new design of the eCLIPs (VR-eCLIPs) was developed by varying the rib length to cover such an inflow gap. To optimize the new product development process, and avoiding expensive and time-consuming iterative manufacture of prototype devices, we have developed a new finite element model to simulate the crimping and expansion processes of the VR-eCLIPs implant, and assess the possibility of plastic deformation. Results indicated that neither eCLIPs nor VR-eCLIPs experience plastic deformation during the crimping process. Upon full expansion, the ribs of VR-eCLIPs interact with the aneurysm and artery wall to cover the inflow gap that exists in certain challenging anatomies. This process serves as a basis to expedite design development prior to prototype manufacturing.

Liquid-Templating Aerogels.

Modern materials science has witnessed the era of advanced fabrication methods to engineer functionality from the nano- to macroscales. Versatile fabrication and additive manufacturing methods are developed, but the ability to design a material for a given application is still limited. Here, a novel strategy that enables target-oriented manufacturing of ultra-lightweight aerogels with on-demand characteristics is introduced. The process relies on controllable liquid templating through interfacial complexation to generate tunable, stimuli-responsive 3D-structured (multiphase) filamentous liquid templates. The methodology involves nanoscale chemistry and microscale assembly of nanoparticles (NPs) at liquid-liquid interfaces to produce hierarchical macroscopic aerogels featuring multiscale porosity, ultralow density (3.05-3.41 mg cm-3 ), and high compressibility (90%) combined with elastic resilience and instant shape recovery. The challenges are overcome facing ultra-lightweight aerogels, including poor mechanical integrity and the inability to form predefined 3D constructs with on-demand functionality, for a multitude of applications. The controllable nature of the coined methodology enables tunable electromagnetic interference shielding with high specific shielding effectiveness (39 893 dB cm2 g-1 ), and one of the highest-ever reported oil-absorption capacities (487 times the initial weight of aerogel for chloroform), to be obtained. These properties originate from the engineerable nature of liquid templating, pushing the boundaries of lightweight materials to systematic function design and applications.

An improved plastination method for strengthening bamboo culms, without compromising biodegradability.

Biomaterials are increasingly being designed and adapted to a wide range of structural applications, owing to their superior mechanical property-to-weight ratios, low cost, biodegradability, and CO2 capture. Bamboo, specifically, has an interesting anatomy with long tube-like vessels present in its microstructure, which can be exploited to improve its mechanical properties for structural applications. By filling these vessels with a resin, e.g. an applied external loading would be better distributed in the structure. One recent method of impregnating the bamboo is plastination, which was originally developed for preserving human remains. However, the original plastination process was found to be slow for bamboo impregnation application, while being also rather complicated/methodical for industrial adaptation. Accordingly, in this study, an improved plastination method was developed that is 40% faster and simpler than the original method. It also resulted in a 400% increase in open-vessel impregnation, as revealed by Micro-X-ray Computed Tomography imaging. The improved method involves three steps: acetone dehydration at room temperature, forced polymer impregnation with a single pressure drop to - 23 inHg, and polymer curing at 130 °C for 20 min. Bamboo plastinated using the new method was 60% stronger flexurally, while maintaining the same modulus of elasticity, as compared to the virgin bamboo. Most critically, it also maintained its biodegradability from cellulolytic enzymes after plastination, as measured by a respirometric technique. Fourier transform infrared-attenuated total reflection, and thermogravimetric analyses were conducted and showed that the plastinated bamboo's functional groups were not altered significantly during the process, possibly explaining the biodegradability. Finally, using cone calorimetry, plastinated bamboo showed a faster ignition time, due to the addition of silicone, but a lower carbon monoxide yield. These results are deemed as a promising step forward for further improvement and application of this highly abundant natural fiber in engineering structures.

An Overview of Nanoparticle Protein Corona Literature.

The protein corona forms spontaneously on nanoparticle surfaces when nanomaterials are introduced into any biological system/fluid. Reliable characterization of the protein corona is, therefore, a vital step in the development of safe and efficient diagnostic and therapeutic nanomedicine products. 2134 published manuscripts on the protein corona are reviewed and a down-selection of 470 papers spanning 2000-2021, comprising 1702 nanoparticle (NP) systems is analyzed. This analysis reveals: i) most corona studies have been conducted on metal and metal oxide nanoparticles; ii) despite their overwhelming presence in clinical practice, lipid-based NPs are underrepresented in protein corona research, iii) studies use new methods to improve reliability and reproducibility in protein corona research; iv) studies use more specific protein sources toward personalized medicine; and v) careful characterization of nanoparticles after corona formation is imperative to minimize the role of aggregation and protein contamination on corona outcomes. As nanoparticles used in biomedicine become increasingly prevalent and biochemically complex, the field of protein corona research will need to focus on developing analytical approaches and characterization techniques appropriate for each unique nanoparticle formulation. Achieving such characterization of the nano-bio interface of nanobiotechnologies will enable more seamless development and safe implementation of nanoparticles in medicine.

Special Issue: "Feature Papers in Materials Simulation and Design".

The title of the current Special Issue, "Feature Papers in Materials Simulation and Design", has identified the aims of this collection since its opening: the gathering of research works and comprehensive review papers that advance the understanding and prediction of material behavior at different scales, from atomistic to macroscopic, through innovative modeling and simulation [...].

Bio-macromolecular design roadmap towards tough bioadhesives.

Emerging sutureless wound-closure techniques have led to paradigm shifts in wound management. State-of-the-art biomaterials offer biocompatible and biodegradable platforms enabling high cohesion (toughness) and adhesion for rapid bleeding control as well as robust attachment of implantable devices. Tough bioadhesion stems from the synergistic contributions of cohesive and adhesive interactions. This Review provides a biomacromolecular design roadmap for the development of tough adhesive surgical sealants. We discuss a library of materials and methods to introduce toughness and adhesion to biomaterials. Intrinsically tough and elastic polymers are leveraged primarily by introducing strong but dynamic inter- and intramolecular interactions either through polymer chain design or using crosslink regulating additives. In addition, many efforts have been made to promote underwater adhesion via covalent/noncovalent bonds, or through micro/macro-interlock mechanisms at the tissue interfaces. The materials settings and functional additives for this purpose and the related characterization methods are reviewed. Measurements and reporting needs for fair comparisons of different materials and their properties are discussed. Finally, future directions and further research opportunities for developing tough bioadhesive surgical sealants are highlighted.

Investigation of a Sparse Autoencoder-Based Feature Transfer Learning Framework for Hydrogen Monitoring Using Microfluidic Olfaction Detectors.

Alternative fuel sources, such as hydrogen-enriched natural gas (HENG), are highly sought after by governments globally for lowering carbon emissions. Consequently, the recognition of hydrogen as a valuable zero-emission energy carrier has increased, resulting in many countries attempting to enrich natural gas with hydrogen; however, there are rising concerns over the safe use, storage, and transport of H2 due to its characteristics such as flammability, combustion, and explosivity at low concentrations (4 vol%), requiring highly sensitive and selective sensors for safety monitoring. Microfluidic-based metal-oxide-semiconducting (MOS) gas sensors are strong tools for detecting lower levels of natural gas elements; however, their working mechanism results in a lack of real-time analysis techniques to identify the exact concentration of the present gases. Current advanced machine learning models, such as deep learning, require large datasets for training. Moreover, such models perform poorly in data distribution shifts such as instrumental variation. To address this problem, we proposed a Sparse Autoencoder-based Transfer Learning (SAE-TL) framework for estimating the hydrogen gas concentration in HENG mixtures using limited datasets from a 3D printed microfluidic detector coupled with two commercial MOS sensors. Our framework detects concentrations of simulated HENG based on time-series data collected from a cost-effective microfluidic-based detector. This modular gas detector houses metal-oxide-semiconducting (MOS) gas sensors in a microchannel with coated walls, which provides selectivity based on the diffusion pace of different gases. We achieve a dominant performance with the SAE-TL framework compared to typical ML models (94% R-squared). The framework is implementable in real-world applications for fast adaptation of the predictive models to new types of MOS sensor responses.

Modeling and Prediction of Thermophysiological Comfort Properties of a Single Layer Fabric System Using Single Sector Sweating Torso.

Thermophysiological comfort is known to play a primary role in maintaining thermal balance, which corresponds to a person's satisfaction with their immediate thermal environment. Among the existing test methods, sweating torsos are one of the best tools to provide a combined measurement of heat and moisture transfer using non-isothermal conditions. This study presents a preliminary numerical model of a single sector sweating torso to predict the thermophysiological comfort properties of fabric systems. The model has been developed using COMSOL Multiphysics, based on the ISO 18640-1 standard test method and a single layer fabric system used in sportswear. A good agreement was observed between the experimental and numeral results over different exposure phases simulated by the torso test (R2 = 0.72 to 0.99). The model enables a systematic investigation of the effect of fabric properties (thickness, porosity, thermal resistance, and evaporative resistance), environmental conditions (relative humidity, air and radiant temperature, and wind speed), and physiological parameters (sweating rate) to gain an enhanced understanding of the thermophysiological comfort properties of the fabric system.

Can a Black-Box AI Replace Costly DMA Testing?-A Case Study on Prediction and Optimization of Dynamic Mechanical Properties of 3D Printed Acrylonitrile Butadiene Styrene.

The complex and non-linear nature of material properties evolution during 3D printing continues to make experimental optimization of Fused Deposition Modeling (FDM) costly, thus entailing the development of mathematical predictive models. This paper proposes a two-stage methodology based on coupling limited data experiments with black-box AI modeling and then performing heuristic optimization, to enhance the viscoelastic properties of FDM processed acrylonitrile butadiene styrene (ABS). The effect of selected process parameters (including nozzle temperature, layer height, raster orientation and deposition speed) as well as their combinative effects are also studied. Specifically, in the first step, a Taguchi orthogonal array was employed to design the Dynamic Mechanical Analysis (DMA) experiments with a minimal number of runs, while considering different working conditions (temperatures) of the final prints. The significance of process parameters was measured using Lenth's statistical method. Combinative effects of FDM parameters were noted to be highly nonlinear and complex. Next, artificial neural networks were trained to predict both the storage and loss moduli of the 3D printed samples, and consequently, the process parameters were optimized via Particle Swarm Optimization (PSO). The optimized process of the prints showed overall a closer behavior to that of the parent (unprocessed) ABS, when compared to the unoptimized set-up.

Enhanced protection face masks do not adversely impact thermophysiological comfort.

The World Health Organization has advocated mandatory face mask usage to combat the spread of COVID-19, with multilayer masks recommended for enhanced protection. However, this recommendation has not been widely adopted, with noncompliant persons citing discomfort during prolonged usage of face masks. And yet, a scientific understanding on how face mask fabrics/garment systems affect thermophysiological comfort remains lacking. We aimed to investigate how fabric/garment properties alter the thermal and evaporative resistances responsible for thermophysiological strain. We constructed 12 different layered facemasks (D1-D5, T1-T6, Q1) with various filters using commercially available fabrics. Three approaches were employed: (1) the evaporative and thermal resistances were measured in all the test face masks using the medium size to determine the effect of fabric properties; (2) the effect of face mask size by testing close-fitted (small), fitted (medium) and loose fitted (large) face mask T-6; (3) the effect of face mask fit by donning a large size face mask T-6, both loose and tightened using thermal manikin, Newton. ANOVA test revealed that the additional N95 middle layer filter has no significant effect on the thermal resistances of all the face masks, and evaporative resistances except for face masks T-2 and T-3 (P-values<0.05) whereas size significantly affected thermal and evaporative resistances (P-values<0.05). The correlation coefficient between the air gap size and the thermal and evaporative resistance of face masks T-6 were R2 = 0.96 and 0.98, respectively. The tight fit large face mask had superior performance in the dissipation of heat and moisture from the skin (P-values <0.05). Three-layer masks incorporating filters and water-resistant and antimicrobial/antiviral finishes did not increase discomfort. Interestingly, using face masks with fitters improved user comfort, decreasing thermal and evaporative resistances in direct opposition to the preconceived notion that safer masks decrease comfort.

Flexible polyfluorinated bis-diazirines as molecular adhesives.

Motivated by a desire to develop flexible covalent adhesives that afford some of the same malleability in the adhesive layer as traditional polymer-based adhesives, we designed and synthesized two flexible, highly fluorinated bis-diazirines. Both molecules are shown to function as effective crosslinkers for polymer materials, and to act as strong adhesives when painted between two polymer objects of low surface energy, prior to thermal activation. Data obtained from lap-shear experiments suggests that greater molecular flexibility is correlated with improved mechanical compliance in the adhesive layer.

Additively Manufactured Gradient Porous Ti-6Al-4V Hip Replacement Implants Embedded with Cell-Laden Gelatin Methacryloyl Hydrogels.

Laser additive manufacturing has led to a paradigm shift in the design of next-generation customized porous implants aiming to integrate better with the surrounding bone. However, conflicting design criteria have limited the development of fully functional porous implants; increasing porosity improves body fluid/cell-laden prepolymer permeability at the expense of compromising mechanical stability. Here, functionally gradient porosity implants and scaffolds designed based on interconnected triply periodic minimal surfaces (TPMS) are demonstrated. High local porosity is defined at the implant/tissue interface aiming to improve the biological response. Gradually decreasing porosity from the surface to the center of the porous constructs provides mechanical strength in selective laser melted Ti-6Al-4V implants. The effect of unit cell size is studied to discover the printability limit where the specific surface area is maximized. Furthermore, mechanical studies on the unit cell topology effects suggest that the bending-dominated architectures can provide significantly enhanced strength and deformability, compared to stretching-dominated architectures. A finite element (FE) model developed also showed great predictability (within ∼13%) of the mechanical responses of implants to physical activities. Finally, in vitro biocompatibility studies were conducted for two-dimensional (2D) and three-dimensional (3D) cases. The results of the 2D in conjunction with surface roughness show favored physical cell attachment on the implant surface. Also, the results of the 3D biocompatibility study for the scaffolds incorporated with a cell-laden gelatin methacryloyl (GelMA) hydrogel show excellent viability. The design procedure proposed here provides new insights into the development of porous hip implants with simultaneous high mechanical and biological responses.

Electrode-Integrated Textile-Based Sensors for In Situ Temperature and Relative Humidity Monitoring in Electrochemical Cells.

Temperature and humidity measurements in electrochemical energy devices are essential for maximizing their overall performance under different operating conditions and avoiding hazardous consequences that may arise from the malfunction of these systems. Using sensors for in situ measurements of temperature and relative humidity (RH) is a promising approach for continuous monitoring and management of electrochemical power sources. Here, we report on the feasibility of using thread-based sensors for in situ measurements of temperature and RH in proton exchange membrane fuel cells (PEMFCs) as an example of electrochemical energy devices. Commodity threads are low-cost and flexible materials that hold great promise for the creation of complex three-dimensional (3D) circuits using well-established textile methods such as weaving, braiding, and embroidering. Ex situ and in situ characterization show that threads can be introduced in the gas diffusion layer (GDL) structure to inscribe water highways within the GDL with minimal impact on the GDL microstructure and transport properties. Fluorinated ethylene propylene (FEP) is coated on thread-based sensors to decouple the response to temperature and humidity; the resulting threads achieve a linear change of resistance with temperature (-0.31%/°C), while RH is monitored with a second thread coated with poly(dimethylsiloxane) (PDMS). The combination of both threads allows for minimally invasive and dynamically responsive monitoring of local temperature and RH within the electrode of PEMFCs.

Fabrication and Characterization of Lignin/Dendrimer Electrospun Blended Fiber Mats.

Blending lignin as the second most abundant polymer in Nature with nanostructured compounds such as dendritic polymers can not only add value to lignin, but also increase its application in various fields. In this study, softwood Kraft lignin/polyamidoamine dendritic polymer (PAMAM) blends were fabricated by the solution electrospinning to produce bead-free nanofiber mats for the first time. The mats were characterized through scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, zeta potential, and thermogravimetry analyses. The chemical intermolecular interactions between the lignin functional groups and abundant amino groups in the PAMAM were verified by FTIR and viscosity measurements. These interactions proved to enhance the mechanical and thermal characteristics of the lignin/PAMAM mats, suggesting their potential applications e.g. in membranes, filtration, controlled release drug delivery, among others.

A Review of Current Challenges and Case Study toward Optimizing Micro-Computed X-Ray Tomography of Carbon Fabric Composites.

X-ray computed tomography provides qualitative and quantitative structural and compositional information for a broad range of materials. Yet, its contribution to the field of advanced composites such as carbon fiber reinforced polymers is still limited by factors such as low imaging contrast, due to scarce X-ray attenuation features. This article, through a review of the state of the art, followed by an example case study on Micro-computed tomography (CT) analysis of low X-ray absorptive dry and prepreg carbon woven fabric composites, aims to highlight and address some challenges as well as best practices on performing scans that can capture key features of the material. In the case study, utilizing an Xradia Micro-CT-400, important aspects such as obtaining sufficient contrast, an examination of thin samples, sample size/resolution issues, and image-based modeling are discussed. The outcome of an optimized workflow in Micro-CT of composite fabrics can assist in further research efforts such as the generation of surface or volume meshes for the numerical modeling of underlying deformation mechanisms during their manufacturing processes.

Nano-porous anodic alumina: fundamentals and applications in tissue engineering.

Recently, nanomaterials have been widely utilized in tissue engineering applications due to their unique properties such as the high surface to volume ratio and diversity of morphology and structure. However, most methods used for the fabrication of nanomaterials are rather complicated and costly. Among different nanomaterials, anodic aluminum oxide (AAO) is a great example of nanoporous structures that can easily be engineered by changing the electrolyte type, anodizing potential, current density, temperature, acid concentration and anodizing time. Nanoporous anodic alumina has often been used for mammalian cell culture, biofunctionalization, drug delivery, and biosensing by coating its surface with biocompatible materials. Despite its wide application in tissue engineering, thorough in vivo and in vitro studies of AAO are still required to enhance its biocompatibility and thereby pave the way for its application in tissue replacements. Recognizing this gap, this review article aims to highlight the biomedical potentials of AAO for applications in tissue replacements along with the mechanism of porous structure formation and pore characteristics in terms of fabrication parameters.

Evolving Magnetically Levitated Plasma Proteins Detects Opioid Use Disorder as a Model Disease.

There are several methods (e.g., enzyme-linked immunosorbent assay and liquid chromatography mass spectroscopy) that already use human plasma to detect a variety of possible diseases. However, this paper introduces the capabilities of magnetic levitation (Maglev) to detect disease (Opioid Use Disorder, used here as a model disease) by using levitation of human plasma proteins. The presented proof-of-concept findings revealed that the optical images of magnetically levitated plasma proteins carry important information about the health spectrum of plasma donors. In addition, the liquid chromatography mass spectroscopy analysis of the magnetically levitated plasma proteins demonstrated remarkable differences between the plasma of healthy individuals and patients with opioid use disorders. Overall, the presented method provides diagnostic value for disease detection using optical images of evolving magnetically levitated plasma proteins and/or proteomic information.

Environmental Durability Enhancement of Natural Fibres Using Plastination: A Feasibility Investigation on Bamboo.

Natural fibers are gaining wide attention due to their much lower carbon footprint and economic factors compared to synthetic fibers. The moisture affinity of these lignocellulosic fibres, however, is still one of the main challenges when using them, e.g., for outdoor applications, leading to fast degradation rates. Plastination is a technique originally used for the preservation of human and animal body organs for many years, by replacing the water and fat present in the tissues with a polymer. This article investigates the feasibility of adapting such plastination to bamboo natural fibres using the S-10 room-temperature technique in order to hinder their moisture absorption ability. The effect of plastination on the mechanical properties and residual moisture content of the bamboo natural fibre samples was evaluated. Energy dispersive x-ray spectroscopy (EDS) and X-ray micro-computed tomography (Micro-CT) were employed to characterize the chemical composition and 3-dimensional morphology of the plastinated specimens. The results clearly show that, as plastination lessens the hydrophilic tendency of the bamboo fibres, it also decreases the residual moisture content and increases the tensile strength and stiffness of the fibers.

3D-Printed Ultra-Robust Surface-Doped Porous Silicone Sensors for Wearable Biomonitoring.

Three-dimensional flexible porous conductors have significantly advanced wearable sensors and stretchable devices because of their specific high surface area. Dip coating of porous polymers with graphene is a facile, low cost, and scalable approach to integrate conductive layers with the flexible polymer substrate platforms; however, the products often suffer from nanoparticle delamination and overtime decay. Here, a fabrication scheme based on accessible methods and safe materials is introduced to surface-dope porous silicone sensors with graphene nanoplatelets. The sensors are internally shaped with ordered, interconnected, and tortuous internal geometries (i.e., triply periodic minimal surfaces) using fused deposition modeling (FDM) 3D-printed sacrificial molds. The molds were dip coated to transfer-embed graphene onto the silicone rubber (SR) surface. The presented procedure exhibited a stable coating on the porous silicone samples with long-term electrical resistance durability over ∼12 months period and high resistance against harsh conditions (exposure to organic solvents). Besides, the sensors retained conductivity upon severe compressive deformations (over 75% compressive strain) with high strain-recoverability and behaved robustly in response to cyclic deformations (over 400 cycles), temperature, and humidity. The sensors exhibited a gauge factor as high as 10 within the compressive strain range of 2-10%. Given the tunable sensitivity, the engineered biocompatible and flexible devices captured movements as rigorous as walking and running to the small deformations resulted by human pulse.