scholarly journals Hydrogel tapes for fault-tolerant strong wet adhesion

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Bin Xue ◽  
Jie Gu ◽  
Lan Li ◽  
Wenting Yu ◽  
Sheng Yin ◽  
...  
Keyword(s):  
Fault Tolerant ◽  
Surface Binding ◽  
Covalent Bonds ◽  
Wet Adhesion ◽  
Reversible Adhesion ◽  
Secondary Damage ◽  
Initial Stage ◽  
Strong Surface ◽  
Physical Interactions ◽  
Surgical Operations

AbstractFast and strong bio-adhesives are in high demand for many biomedical applications, including closing wounds in surgeries, fixing implantable devices, and haemostasis. However, most strong bio-adhesives rely on the instant formation of irreversible covalent crosslinks to provide strong surface binding. Repositioning misplaced adhesives during surgical operations may cause severe secondary damage to tissues. Here, we report hydrogel tapes that can form strong physical interactions with tissues in seconds and gradually form covalent bonds in hours. This timescale-dependent adhesion mechanism allows instant and robust wet adhesion to be combined with fault-tolerant convenient surgical operations. Specifically, inspired by the catechol chemistry discovered in mussel foot proteins, we develop an electrical oxidation approach to controllably oxidize catechol to catecholquinone, which reacts slowly with amino groups on the tissue surface. We demonstrate that the tapes show fast and reversible adhesion at the initial stage and ultrastrong adhesion after the formation of covalent linkages over hours for various tissues and electronic devices. Given that the hydrogel tapes are biocompatible, easy to use, and robust for bio-adhesion, we anticipate that they may find broad biomedical and clinical applications.

scholarly journals Hydrogel tapes for fault-tolerant strong wet adhesion

2021 ◽  
Author(s):  
Yi Cao ◽  
Bin Xue ◽  
Jie Gu ◽  
Wenting Yu ◽  
Lan Li ◽  
...  
Keyword(s):  
Fault Tolerant ◽  
Surface Binding ◽  
Covalent Bonds ◽  
Wet Adhesion ◽  
Reversible Adhesion ◽  
Secondary Damage ◽  
Initial Stage ◽  
Strong Surface ◽  
Physical Interactions ◽  
Surgical Operations

Abstract Fast and strong bio-adhesives are in high demand for many biomedical applications, including closing wounds in surgeries, fixing implantable devices, and haemostasis. However, most strong bio-adhesives rely on the instant formation of irreversible covalent crosslinks to provide strong surface binding. Repositioning misplaced adhesives during surgical operations may cause severe secondary damage to tissues. Here, we report hydrogel tapes that can form strong physical interactions with tissues in seconds and gradually form covalent bonds in hours. This timescale-dependent adhesion mechanism allows instant and robust wet adhesion to be combined with fault-tolerant convenient surgical operations. Specifically, inspired by the catechol chemistry discovered in mussel foot proteins, we develop an electrical oxidation approach to controllably oxidize catechol to catecholquinone, which reacts slowly with amino groups on the tissue surface. We demonstrate that the tapes show fast and reversible adhesion at the initial stage and ultrastrong adhesion after the formation of covalent linkages over hours for various tissues and electronic devices. Given that the hydrogel tapes are biocompatible, easy to use, and robust for bio-adhesion, we anticipate that they may find broad biomedical and clinical applications.

scholarly journals Ultrafast self-gelling powder mediates robust wet adhesion to promote healing of gastrointestinal perforations

2021 ◽  
Vol 7 (23) ◽  
pp. eabe8739
Author(s):  
Xin Peng ◽  
Xianfeng Xia ◽  
Xiayi Xu ◽  
Xuefeng Yang ◽  
Boguang Yang ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Gastric Perforation ◽  
Interfacial Water ◽  
Wet Adhesion ◽  
Tissue Interactions ◽  
Tissue Surface ◽  
Strong Adhesion ◽  
Surface Irregularities ◽  
Physical Interactions

Achieving strong adhesion of bioadhesives on wet tissues remains a challenge and an acute clinical demand because of the interfering interfacial water and limited adhesive-tissue interactions. Here we report a self-gelling and adhesive polyethyleneimine and polyacrylic acid (PEI/PAA) powder, which can absorb interfacial water to form a physically cross-linked hydrogel in situ within 2 seconds due to strong physical interactions between the polymers. Furthermore, the physically cross-linked polymers can diffuse into the substrate polymeric network to enhance wet adhesion. Superficial deposition of PEI/PAA powder can effectively seal damaged porcine stomach and intestine despite excessive mechanical challenges and tissue surface irregularities. We further demonstrate PEI/PAA powder as an effective sealant to enhance the treatment outcomes of gastric perforation in a rat model. The strong wet adhesion, excellent cytocompatibility, adaptability to fit complex sites, and easy synthesis of PEI/PAA powder make it a promising bioadhesive for numerous biomedical applications.

scholarly journals Fault-tolerant elastic–plastic lattice material

2019 ◽  
Vol 378 (2162) ◽  
pp. 20190107 ◽  
Author(s):  
Michael Ryvkin ◽  
Viacheslav Slesarenko ◽  
Andrej Cherkaev ◽  
Stephan Rudykh
Keyword(s):  
Energy Absorption ◽  
Fault Tolerant ◽  
Three Dimensional ◽  
Uniaxial Tensile ◽  
Elastoplastic Material ◽  
Beam Elements ◽  
Initial Stage ◽  
Final Failure ◽  
Thin Beams ◽  
Beam Lattice

The paper describes a fault-tolerant design of a special two-dimensional beam lattice. The morphology of such lattices was suggested in the theoretical papers (Cherkaev and Ryvkin 2019 Arch. Appl. Mech. 89 , 485–501; Cherkaev and Ryvkin 2019 Arch. Appl. Mech. 89 , 503–519), where its superior properties were found numerically. The proposed design consists of beam elements with two different thicknesses; the lattice is macro-isotropic and stretch dominated. Here, we experimentally verify the fault-tolerant properties of these lattices. The specimens were three-dimensional-printed from the VeroWhite elastoplastic material. The lattice is subjected to uniaxial tensile loading. Due to its morphology, the failed beams are evenly distributed in the lattice at the initial stage of damage; at this stage, the material remains intact, preserves its bearing ability, and supports relatively high strains before the final failure. At the initial phase of damage, the thinner beams buckle; then another group of separated thin beams plastically yield and rupture. The fatal macro-crack propagates after the distributed damage reaches a critical level. This initial distributed damage stage allows for a better energy absorption rate before the catastrophic failure of the structure. The experimental results are supported by simulations which confirm that the proposed fault-tolerant material possesses excellent energy absorption properties thanks to the distributed damage stage phenomenon. This article is part of the theme issue ‘Modelling of dynamic phenomena and localization in structured media (part 2)’.

scholarly journals The composition of peptidochitodextrins from sarcophagid puparial cases

1971 ◽  
Vol 125 (3) ◽  
pp. 703-716 ◽  
Author(s):  
H. Lipke ◽  
T. Geoghegan
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Protein Complex ◽  
Covalent Bonds ◽  
Aromatic Residues ◽  
Similar Molecular Weight ◽  
X Ray ◽  
Molecular Weights ◽  
Physical Interactions ◽  
The Stability

1. N-Bromosuccinimide cleaved proteins and pigments from fly puparia, increasing the chitin:protein ratio from 0.5 to 1.5. The product afforded subfractions (ratio 5:1) of molecular weights of 1200 and 1600 devoid of aromatic residues and N-terminal β-alanine, direct aryl links between polysaccharide chains being discounted. 2. The chitin–protein complex decreased in molecular weight when treated with Pronase, which suggested polypeptide bridges within the native chitin micelle. The limit dextrins generated by chitinase were mixtures of unsubstituted dextrins and peptidylated oligosaccharides, with the former predominating. 3. Peptidochitodextrins of similar molecular weight but markedly different solubility were prepared, which were indistinguishable with respect to amino acid, glucosamine, acetyl, X-ray or infrared characteristics. It is suggested that physical interactions contribute to the stability of the integument in addition to the covalent bonds that form during sclerotization.

scholarly journals Self-Healing and High Interfacial Strength in Multi-Material Soft Pneumatic Robots via Reversible Diels–Alder Bonds

Actuators ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 34 ◽  
Author(s):  
Seppe Terryn ◽  
Ellen Roels ◽  
Joost Brancart ◽  
Guy Van Assche ◽  
Bram Vanderborght
Keyword(s):  
Interfacial Strength ◽  
Diels Alder ◽  
Self Healing ◽  
Material Interfaces ◽  
Material Interface ◽  
Covalent Bonds ◽  
Pneumatic Actuators ◽  
Multiple Materials ◽  
Physical Interactions ◽  
New Generation

In new-generation soft robots, the actuation performance can be increased by using multiple materials in the actuator designs. However, the lifetime of these actuators is often limited due to failure that occurs at the weak multi-material interfaces that rely almost entirely on physical interactions and where stress concentration appears during actuation. This paper proposes to develop soft pneumatic actuators out of multiple Diels–Alder polymers that can generate strong covalent bonds at the multi-material interface by means of a heat–cool cycle. Through tensile testing it is proven that high interfacial strength can be obtained between two merged Diels–Alder polymers. This merging principle is exploited in the manufacturing of multi-material bending soft pneumatic actuators in which interfaces are no longer the weakest links. The applicability of the actuators is illustrated by their operation in a soft hand and a soft gripper demonstrator. In addition, the use of Diels–Alder polymers incorporates healability in bending actuators. It is experimentally illustrated that full recovery of severe damage can be obtained by subjecting the multi-material actuators to a healing cycle.

scholarly journals Polysaccharide-Based In Situ Self-Healing Hydrogels for Tissue Engineering Applications

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2261
Author(s):  
Sheila Maiz-Fernández ◽  
Leyre Pérez-Álvarez ◽  
Leire Ruiz-Rubio ◽  
Jose Luis Vilas-Vilela ◽  
Senentxu Lanceros-Mendez
Keyword(s):  
Tissue Engineering ◽  
Personalized Medicine ◽  
Tissue Regeneration ◽  
Self Healing ◽  
Covalent Bonds ◽  
Surgical Interventions ◽  
Non Invasive ◽  
Potential Applications ◽  
Physical Interactions

In situ hydrogels have attracted increasing interest in recent years due to the need to develop effective and practical implantable platforms. Traditional hydrogels require surgical interventions to be implanted and are far from providing personalized medicine applications. However, in situ hydrogels offer a wide variety of advantages, such as a non-invasive nature due to their localized action or the ability to perfectly adapt to the place to be replaced regardless the size, shape or irregularities. In recent years, research has particularly focused on in situ hydrogels based on natural polysaccharides due to their promising properties such as biocompatibility, biodegradability and their ability to self-repair. This last property inspired in nature gives them the possibility of maintaining their integrity even after damage, owing to specific physical interactions or dynamic covalent bonds that provide reversible linkages. In this review, the different self-healing mechanisms, as well as the latest research on in situ self-healing hydrogels, is presented, together with the potential applications of these materials in tissue regeneration.

scholarly journals Tree frog adhesion biomimetics: opportunities for the development of new, smart adhesives that adhere under wet conditions

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190131 ◽  
Author(s):  
Fandong Meng ◽  
Quan Liu ◽  
Xin Wang ◽  
Di Tan ◽  
Longjian Xue ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Science And Technology ◽  
Tree Frog ◽  
Theme Issue ◽  
Testing Hypotheses ◽  
Wet Adhesion ◽  
Reversible Adhesion ◽  
Epithelial Structure ◽  
Dry And Wet Conditions ◽  
Tree Frogs

Enlarged adhesive toe pads on the tip of each digit allow tree frogs to climb smooth vertical and overhanging surfaces, and are effective in generating reversible adhesion under both dry and wet conditions. In this review, we discuss the complexities of the structure of tree frog toe pads in relation to their function and review their biomimetic potential. Of particular importance are the (largely) hexagonal epithelial cells surrounded by deep channels that cover the surface of each toe pad and the array of nanopillars on their surface. Fluid secreted by the pads covers the surface of each pad, so the pads adhere by wet adhesion, involving both capillarity and viscosity-dependent forces. The fabrication and testing of toe pad mimics are challenging, but valuable both for testing hypotheses concerning tree frog toe pad function and for developing toe pad mimics. Initial mimics involved the fabrication of hexagonal pillars mimicking the toe pad epithelial structure. More recent ones additionally replicate the nanostructures on their surface. Finally we describe some of the biomimetic applications that have been developed from toe pad mimics, which include both bioinspired adhesives and friction-generating devices. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

scholarly journals COVID-19 PANDEMIC AWARENESS AND ITS IMPACT ON BANGLADESHI PEOPLE: A COMMUNITY BASED SURVEY

2022 ◽  
Author(s):  
Md. Monirul Islam ◽  
Abu Zobayed ◽  
Md. Imran Nur Manik ◽  
Mohammad Asadujjaman
Keyword(s):  
Social Media ◽  
Peer Review ◽  
Urban Areas ◽  
Online Survey ◽  
Daily Lives ◽  
Initial Stage ◽  
Unique System ◽  
Physical Interactions ◽  
Review Reports

Background: The present study has been carried out to find out the people’s perception about the COVID-19 pandemic and the effects of this pandemic on their daily lives. Methods: A Google form was used to create an online survey questionnaire distributed via personal relationships and social media. Data were collected using questionnaires consisting of socio-demographic status of participants, COVID-19 concepts and changes in the participants’ lifestyle. A total of 1088 respondents took part in the survey, and the results were evaluated using several statistical approaches. The results were presented in a variety of tables and graphs. Results: Males made up 53.3% of the participants, while females made up 46.7% who were from villages (29.87%), cities (53.77%), and semi-urban areas (16.36%). Most participants reported that they got information about the COVID-19 pandemic from social media, and they cited 'fever' as an indicator of the sickness. Although the amount of physical interactions with friends and family has not dropped much, working conditions and employment status have significantly altered. The majority of the participants claimed they have no concerns about the COVID-19. Conclusion: For up-to-date information regarding COVID-19, people in Bangladesh from all walks of life rely largely on social media. COVID-19 awareness isn't enough to inhibit the spreading of the virus from community to community. Employees' work schedules have also been drastically altered. To prevent transmission, we should all follow the safety rules strictly.               Peer Review History: Received: 4 November 2021; Revised: 17 December; Accepted: 28 December, Available online: 15 January 2022 Academic Editor: Dr. Muhammad Zahid Iqbal, AIMST University, Malaysia, [email protected] UJPR follows the most transparent and toughest ‘Advanced OPEN peer review’ system. The identity of the authors and, reviewers will be known to each other. This transparent process will help to eradicate any possible malicious/purposeful interference by any person (publishing staff, reviewer, editor, author, etc) during peer review. As a result of this unique system, all reviewers will get their due recognition and respect, once their names are published in the papers. We expect that, by publishing peer review reports with published papers, will be helpful to many authors for drafting their article according to the specifications. Auhors will remove any error of their article and they will improve their article(s) according to the previous reports displayed with published article(s). The main purpose of it is ‘to improve the quality of a candidate manuscript’. Our reviewers check the ‘strength and weakness of a manuscript honestly’. There will increase in the perfection, and transparency.  Received file:                Reviewer's Comments: Average Peer review marks at initial stage: 5.5/10 Average Peer review marks at publication stage: 7.0/10 Reviewers: Dr. Eyassu Mathewos, School of public health, college of health sciences and medicine, Wolaita Soddo university- P.O. Box 158, Wolaita Soddo, Ethiopia. Dr. Barkat Ali Khan, Kampala International University , Uganda, [email protected] Similar Articles:  COVID-19: PHARMACOLOGICAL AND THERAPEUTIC APPROACHES COVID-19 IN MEXICO: PREPARING FOR FUTURE PANDEMICS

Two-qubit quantum gates construction via unitary factorization

2017 ◽  
Vol 17 (9&10) ◽  
pp. 721-746
Author(s):  
Francisco Delgado
Keyword(s):  
Quantum Computer ◽  
Fault Tolerant ◽  
Pulse Sequence ◽  
Quantum Gate ◽  
Magnetic Systems ◽  
Research Areas ◽  
Non Local ◽  
Physical Interactions ◽  
Physical Elements ◽  
Gate Design

Quantum information and quantum computation are emerging research areas based on the properties of quantum resources, such as superposition and entanglement. In the quantum gate array version, the use of convenient and proper gates is essential. While these gates adopt theoretically convenient forms to reproduce computational algorithms, their design and feasibility depend on specific quantum systems and physical resources used in their setup. These gates should be based on systems driven by physical interactions ruled by a quantum Hamiltonian. Then, the gate design is restricted to the properties and the limitations imposed by the interactions and the physical elements involved. This work shows how anisotropic Heisenberg-Ising interactions, written in a non-local basis, allow the reproduction of quantum computer operations based on unitary processes. We show that gates can be generated by a pulse sequence of driven magnetic fields. This fact states alternative techniques in quantum gate design for magnetic systems. A brief final discussion around associated fault tolerant extensions to the current work is included.

Heat induced gelation of acid milk: balance between weak and covalent bonds

2003 ◽  
Vol 70 (2) ◽  
pp. 253-256 ◽  
Author(s):  
Olivier Surel ◽  
Marie-Hélène Famelart
Keyword(s):  
Protein Interactions ◽  
Whey Proteins ◽  
High Heat ◽  
Heat Treatments ◽  
Protein Protein Interactions ◽  
Casein Micelles ◽  
Covalent Bonds ◽  
Disulphide Bonds ◽  
Initial Stage ◽  
Β Lactoglobulin

Gelation of acidified milk at pH[ges ]5, after heat treatments is a well known phenomenon, due to the precipitation of whey proteins, and especially β-lactoglobulin onto κ-casein (Sawyer, 1969). High heat treatments cause denaturation of whey proteins which associate with κ-casein through disulphide interchange reactions (Hill, 1989). Since their charge is reduced, the denatured proteins associated with casein micelles become susceptible to aggregation when milk is then acidified, which promotes enhanced protein–protein interactions (Lucey et al. 1997). The gelation phenomenon involves disulphide bonds (Hashizume & Sato, 1988; Goddard, 1996) which are responsible for the gel firmness (Goddard, 1996). However, other interactions between proteins can occur, such as hydrogen and hydrophobic bonds, especially at the initial stage of interactions (Haque et al. 1987; Haque & Kinsella, 1988; Jang & Swaisgood, 1990). It is therefore relevant to investigate a possible contribution of weak linkages to the gel structure and firmness.

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