scholarly journals Bioinspired self-healing materials: lessons from nature

2018 ◽  
Vol 9 ◽  
pp. 907-935 ◽  
Author(s):  
Joseph C Cremaldi ◽  
Bharat Bhushan
Keyword(s):  
Defense Mechanisms ◽  
Cellular Response ◽  
Self Healing ◽  
Vascular Networks ◽  
Muscle Control ◽  
Functional Coatings ◽  
Evolutionary Methods ◽  
Bioinspired Materials ◽  
Living Nature ◽  
The Relationship

Healing is an intrinsic ability in the incredibly biodiverse populations of the plant and animal kingdoms created through evolution. Plants and animals approach healing in similar ways but with unique pathways, such as damage containment in plants or clotting in animals. After analyzing the examples of healing and defense mechanisms found in living nature, eight prevalent mechanisms were identified: reversible muscle control, clotting, cellular response, layering, protective surfaces, vascular networks or capsules, exposure, and replenishable functional coatings. Then the relationship between these mechanisms, nature’s best (evolutionary) methods of mitigating and healing damage, and existing technology in self-healing materials are described. The goals of this top-level overview are to provide a framework for relating the behavior seen in living nature to bioinspired materials, act as a resource to addressing the limitations/problems with existing materials, and open up new avenues of insight and research into self-healing materials.

scholarly journals Rapid synchronized fabrication of vascularized thermosets and composites

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mayank Garg ◽  
Jia En Aw ◽  
Xiang Zhang ◽  
Polette J. Centellas ◽  
Leon M. Dean ◽  
...  
Keyword(s):  
Large Scale ◽  
Capillary Flow ◽  
External Heat ◽  
Frontal Polymerization ◽  
Self Healing ◽  
Vascular Networks ◽  
Ambient Conditions ◽  
External Energy ◽  
Imaging Phantoms ◽  
Vascular Structures

AbstractBioinspired vascular networks transport heat and mass in hydrogels, microfluidic devices, self-healing and self-cooling structures, filters, and flow batteries. Lengthy, multistep fabrication processes involving solvents, external heat, and vacuum hinder large-scale application of vascular networks in structural materials. Here, we report the rapid (seconds to minutes), scalable, and synchronized fabrication of vascular thermosets and fiber-reinforced composites under ambient conditions. The exothermic frontal polymerization (FP) of a liquid or gelled resin facilitates coordinated depolymerization of an embedded sacrificial template to create host structures with high-fidelity interconnected microchannels. The chemical energy released during matrix polymerization eliminates the need for a sustained external heat source and greatly reduces external energy consumption for processing. Programming the rate of depolymerization of the sacrificial thermoplastic to match the kinetics of FP has the potential to significantly expedite the fabrication of vascular structures with extended lifetimes, microreactors, and imaging phantoms for understanding capillary flow in biological systems.

Desire for Self-healing

2017 ◽  
Vol 12 (1-2) ◽  
pp. 317-335
Author(s):  
Ngar-sze Lau
Keyword(s):  
Theravada Buddhism ◽  
Self Healing ◽  
Core Knowledge ◽  
The Third ◽  
The Core ◽  
Physical Suffering ◽  
Mind And Body ◽  
Core Practice ◽  
The Relationship ◽  
Contemporary Chinese

Abstract This practice report describes how Chinese meditators understand the “four foundations of mindfulness” (satipaṭṭhāna, sinianzhu 四念住) as a remedy for both mental and physical suffering. In the tradition of Theravāda Buddhism, satipaṭṭhāna is particularly recognized as the core knowledge for understanding the relationship between mind and body, and the core practice leading to liberation from suffering. Based on interviews with Chinese meditation practitioners, this study develops three main themes concerning how they have alleviated afflictions through the practice of satipaṭṭhāna. The first theme highlights how practitioners learn to overcome meditation difficulties with “right attitude.” The second theme is about practicing awareness with “six sense doors” open in order to facilitate the balance of the “five faculties.” The third theme explores how practitioners cultivate daily life practice through an understanding of the nature of mind and body as impermanent and as not-self. This paper details how these themes and embodied practices of satipaṭṭhāna constitute ways of self-healing for urban educated Buddhists in the contemporary Chinese context.

Effects of Pollution on Swallowing: How Little We Know

1992 ◽  
Vol 106 (6) ◽  
pp. 706-712 ◽  
Author(s):  
Jeffrey B. Palmer ◽  
Kenneth H. C. Silver
Keyword(s):  
Defense Mechanisms ◽  
Alimentary Tract ◽  
Direct Effects ◽  
Future Directions ◽  
Environmental Agents ◽  
Food Particles ◽  
Essential Function ◽  
Airway Defense ◽  
Relationship Of ◽  
The Relationship

Swallowing is an essential function of the upper alimentary tract. It is highly complex, requiring precise coordination of numerous nerves and muscles of the oral cavity, pharynx, larynx, and esophagus. Swallowing is integrated with other physiologic functions, Including mastication and respiration. Impairments of swallowing may result from many different structural or physiologic disorders. Little is currently known about the direct effects of pollution on swallowing. Structures critical to swallowing, however, are vulnerable to damage by environmental hazards such as exposure to ionizing radiation or intake of toxins by ingestion or inhalation. The relationship of swallowing to environmental lung disease is an area of particular Interest because Impaired swallowing may result in aspiration of food particles into the lung, and because pollutants may hamper airway defense mechanisms. In this article, we discuss the possible impact of selected environmental agents on swallowing and suggest future directions for research.

scholarly journals The Mediating Role of Alexithymia in the Relationship Between Defense Mechanisms and Tendency to High-risk Behaviors Among Adolescents

2021 ◽  
Vol 11 (1) ◽  
pp. 29-36
Author(s):  
Zahra Nikmanesh ◽  
◽  
Mehdi Darvish Molla ◽  
Mehrnosh Mehranfard ◽  
◽  
...  
Keyword(s):  
High School Students ◽  
High Risk ◽  
Path Analysis ◽  
Risk Behaviors ◽  
Defense Mechanisms ◽  
Related Factors ◽  
High Risk Behaviors ◽  
Mediating Role ◽  
The Relationship

Background: Although high-risk behaviors lead to adverse physical, psychological, and sociological consequences, less attention has been paid to identifying their related factors. The aim of this study was to investigate the mediating role of alexithymia in the relationship between defense mechanisms and high-risk behaviors among adolescents in Zahedan. Methods: In this descriptive-correlative study, junior and senior high school students of Zahedan, Iran were studied in the academic year 2015-2016. A sample of 250 (125 males and 125 females) students were chosen by multi-stage cluster sampling and asked to complete the Defense Style Questionnaire (DSQ), Toronto Alexithymia Scale (TAS), and the Risk-Taking Scale (IARS) for Iranian Adolescents. Data analysis was conducted by measuring coefficients of correlation and performing a path analysis. Results: Path analysis showed a significant correlation between defense mechanisms and alexithymia (P<0.01) and a significant correlation was found between immature defense mechanisms and high-risk behaviors (P<0.01). Conclusion: In the relationship between dysfunctional defense mechanisms and high-risk activities, alexithymia played a mediating role. It can be inferred that dysfunctional defense mechanisms play a key role in high-risk activities by influencing alexithymia.

scholarly journals Hypoxia-inducible factor–1 and associated upstream and downstream proteins in the pathophysiology and management of glioblastoma

2014 ◽  
Vol 37 (6) ◽  
pp. E8 ◽  
Author(s):  
Matthew Womeldorff ◽  
David Gillespie ◽  
Randy L. Jensen
Keyword(s):  
Cellular Response ◽  
Treatment Options ◽  
Hypoxia Inducible Factor ◽  
Hypoxia Inducible Factor 1 ◽  
Poor Patient ◽  
Growth Development ◽  
The Relationship ◽  
Insight Into ◽  
Upstream Regulators

Glioblastoma multiforme (GBM) is a highly aggressive brain tumor with an exceptionally poor patient outcome despite aggressive therapy including surgery, radiation, and chemotherapy. This aggressive phenotype may be associated with intratumoral hypoxia, which probably plays a key role in GBM tumor growth, development, and angiogenesis. A key regulator of cellular response to hypoxia is the protein hypoxia-inducible factor–1 (HIF-1). An examination of upstream hypoxic and nonhypoxic regulation of HIF-1 as well as a review of the downstream HIF-1–regulated proteins may provide further insight into the role of this transcription factor in GBM pathophysiology. Recent insights into upstream regulators that intimately interact with HIF-1 could provide potential therapeutic targets for treatment of this tumor. The same is potentially true for HIF-1–mediated pathways of glycolysis-, angiogenesis-, and invasion-promoting proteins. Thus, an understanding of the relationship between HIF-1, its upstream protein regulators, and its downstream transcribed genes in GBM pathogenesis could provide future treatment options for the care of patients with these tumors.

Different Chilling-Induced Symptoms and the Underlying Oxidative Stress and Antioxidative Defense in the Exocarp and Mesocarp of Immature Sponge Gourd (Luffa cylindrica) Fruit

2021 ◽  
Author(s):  
Pichaya Chuenchom ◽  
Sompoch Noichinda ◽  
Kitti Bodhipadma ◽  
Chalermchai Wongs-Aree ◽  
David W. M. Leung
Keyword(s):  
Oxidative Stress ◽  
Defense Mechanisms ◽  
Considerable Increase ◽  
Chilling Injury ◽  
Oxygen Species ◽  
Antioxidative Defense ◽  
Sponge Gourd ◽  
Lower Temperature ◽  
High Level ◽  
The Relationship

Immature sponge gourd fruit is consumed as a vegetable with a limited shelf life. Although cold storage is a simple and powerful tool for maintaining postharvest fruit quality, storage at a low temperature may not be appropriate for vegetables as some chilling injury (CI) of the immature sponge gourd fruit may occur. Therefore, this research aimed to elucidate the relationship between CI, oxidative stress, and the antioxidative defense mechanisms in the exocarp and mesocarp of immature sponge gourd fruit. After storage at 5°C for 6 days, visual CI symptoms, including browning and surface pitting, were found in the peel (exocarp) but not in the mesocarp. There were, however, more dead cells (stained by Evans blue) in the mesocarp of the fruit stored at 5°C. There was a more considerable increase in the electrolyte leakage rate in both fruit tissues held at 5°C than 25°C. The CI was correlated with malondialdehyde (MDA) levels in the tissues. The MDA of fruit exocarp at 5°C was 1.6 fold higher than that at 25°C on day 6, while the lipoxygenase (LOX) activity in mesocarp was 50% higher in fruit stored at a lower temperature. The action of ascorbate peroxidase (APX) was high in the exocarp of the fruit stored at 5°C, but there appeared to be a continuous depletion of the co-substrate or ascorbic acid. In conclusion, the CI in the exocarp was mainly associated with a high level of reactive oxygen species (ROS). In contrast, the CI in the mesocarp appeared to be primarily associated with increased lipid peroxidation by the elevated LOX activity under cold stress compared to storage at 25°C.

scholarly journals Electrospinning: A Powerful Tool to Improve the Corrosion Resistance of Metallic Surfaces Using Nanofibrous Coatings

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 350 ◽  
Author(s):  
Pedro J. Rivero ◽  
Deyo Maeztu Redin ◽  
Rafael J. Rodríguez
Keyword(s):  
Surface Engineering ◽  
Good Control ◽  
Self Healing ◽  
Intrinsic Properties ◽  
Functional Coatings ◽  
Metallic Surfaces ◽  
Electrospinning Technique ◽  
Deposition Parameters ◽  
Efficient Alternative ◽  
Fibre Morphology

The use of surface engineering techniques to tune-up the composition of nanostructured thin-films for developing functional coatings with advanced properties is a hot topic within the scientific community. The control of the coating structure at the nanoscale level allows improving the intrinsic properties of the surface compared to bulk materials. A nanodeposition technique with increasing popularity in the field of nanotechnology is electrospinning. This technique permits the fabrication of long and continuous fibres on the micro-nano scale. The good control over fibre morphology combined with its simplicity, cost-effectiveness, easy exploitability and scalability make electrospinning a very interesting tool for technological applications. This review is focused on the use of the electrospinning technique to protect metallic surfaces against corrosion. Polymeric precursors, from natural or biodegradable to synthetic polymers and copolymers can be electrospun with an adequate control of the operational deposition parameters (applied voltage, flow rate, distance tip to collector) and the intrinsic properties of the polymeric precursor (concentration, viscosity, solvent). The electrospun fibres can be used as an efficient alternative to encapsulate corrosion inhibitors of different nature (inorganic or organic) as well as self-healing agents which can be released to reduce the corrosion rate in the metallic surfaces.

scholarly journals Development of 3D Printed Networks in Self-Healing Concrete

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1328 ◽  
Author(s):  
Cristina De Nardi ◽  
Diane Gardner ◽  
Anthony Duncan Jefferson
Keyword(s):  
Vascular System ◽  
Physical And Mechanical Properties ◽  
Self Healing ◽  
Vascular Networks ◽  
Minimal Impact ◽  
Cementitious Matrix ◽  
Healing Agent ◽  
3D Printed ◽  
Series Of Experiments ◽  
Concrete Elements

This paper presents a new form of biomimetic cementitious material, which employs 3D-printed tetrahedral mini-vascular networks (MVNs) to store and deliver healing agents to damage sites within cementitious matrices. The MVNs are required to not only protect the healing agent for a sufficient period of time but also survive the mixing process, release the healing agent when the cementitious matrix is damaged, and have minimal impact on the physical and mechanical properties of the host cementitious matrix. A systematic study is described which fulfilled these design requirements and determined the most appropriate form and material for the MVNs. A subsequent series of experiments showed that MVNs filled with sodium silicate, embedded in concrete specimens, are able to respond effectively to damage, behave as a perfusable vascular system and thus act as healing agent reservoirs that are available for multiple damage-healing events. It was also proved that healing agents encapsulated within these MVNs can be transported to cracked zones in concrete elements under capillary driving action, and produce a recovery of strength, stiffness and fracture energy.

Sign in / Sign up

Export Citation Format

Share Document